Solid-state polymer electrolytes are crucial for advancing solid-state lithium-metal batteries owing to their flexibility,excellent manufacturability,and strong interfacial compatibility.However,their widespread appli...Solid-state polymer electrolytes are crucial for advancing solid-state lithium-metal batteries owing to their flexibility,excellent manufacturability,and strong interfacial compatibility.However,their widespread applications are hindered by low ionic conductivity at room temperature and lithium dendrite growth.Herein,we report a novel solid-state composite membrane electrolyte design that combines the vertically aligned channel structure and copolymer with a radial gradient composition.Within the vertically aligned channels,the composition of poly(vinyl ethylene carbonate-co-poly(ethylene glycol)diacrylate)(P(VEC-PEGDA)varies in a gradient along the radial direction:from the center to the wall of vertically aligned channels,the proportion of vinyl ethylene carbonate(VEC)in the copolymer decreases,while the proportion of poly(ethylene glycol)diacrylate(PEGDA)increases accordingly.It can be functionally divided into a mechanical-reinforcement layer and a fast-ion-conducting layer.The resulting solid-state composite membrane electrolyte achieves a high critical current density of 1.2 mA cm^(-2)and high ionic conductivity of 2.03 mS cm^(-1)at room temperature.Employing this composite membrane electrolyte,a Li//Li symmetric cell exhibits stable cycling for over 1850 h at 0.2 m A cm^(-2)/0.2 m A h cm^(-2),and a Li//LiFePO4(LFP)battery maintains 77.3% capacity retention at 2 C after 300 cycles.Our work provides insight into the rational design of safer and more efficient solidstate batteries through electrolyte structural engineering.展开更多
The development of aqueous zinc ion battery cathode materials with high capacity and high magnification is still a challenge.Herein,porous vanadium oxide/carbon(p-VO_(x)@C,mainly VO_(2) with a small amount of V_(2)O_(...The development of aqueous zinc ion battery cathode materials with high capacity and high magnification is still a challenge.Herein,porous vanadium oxide/carbon(p-VO_(x)@C,mainly VO_(2) with a small amount of V_(2)O_(3)) core/shell microspheres with oxygen vacancies are facilely fabricated by using a vanadium-based metal-organic framework(MIL-100(V)) as a sacrificial template.This unique structure can improve the conductivity of the VO_(x),accelerate electrolyte diffusion,and suppress structural collapse during circulation.Subsequently,H_(2)O molecules are introduced into the interlayer of VO_(x) through a highly efficient in-situ electrochemical activation process,facilitating the intercalation and diffusion of zinc ions.After the activation,an optimal sample exhibits a high specific capacity of 464.3 mA h g^(-1) at0.2 A g^(-1) and 395.2 mA h g^(-1) at 10 A g^(-1),indicating excellent rate performance.Moreover,the optimal sample maintains a capacity retention of about 89.3% after 2500 cycles at 10 A g^(-1).Density functional theory calculation demonstrates that the presence of oxygen vacancies and intercalated water molecules can significantly reduce the diffusion barrier for zinc ions.In addition,it is proved that the storage of zinc ions in the cathode is achieved by reversible intercalation/extraction during the charge and discharge process through various ex-situ analysis technologies.This work demonstrates that the p-VO_(x)@C has great potential for applications in aqueous ZIBs after electrochemical activation.展开更多
In this work,Ag/Ag_(2)Se composite films with excellent thermoelectric(TE)properties and flexibility are prepared based on a simple one-pot method.By adjusting the nominal ratios of Ag/Se,an optimal Ag/Ag_(2)Se compos...In this work,Ag/Ag_(2)Se composite films with excellent thermoelectric(TE)properties and flexibility are prepared based on a simple one-pot method.By adjusting the nominal ratios of Ag/Se,an optimal Ag/Ag_(2)Se composite film shows a large power factor of~2275 μW m^(-1) K^(-2) at 300 K.Such an outstand-ing TE performance of the composite film is due to the unique microstructure and the synergistic effect between the Ag and Ag_(2)Se.Meanwhile,the composite film also shows outstanding flexibility(~91.8%of the initial electrical conductivity is maintained,and the S is unchanged after 1500 bending cycles with a bending radius of 4 mm).Furthermore,a 4-leg flexible TE generator assembled with the optimal film produces a voltage of 14.06 mV and 4.96 μW at a temperature difference of 30.4 K.This work provides a new inspiration for the preparation of flexible Ag_(2)Se-based films with excellent TE performance near room temperature.展开更多
High piezoelectric properties and superior thermal stability are both important indicators of piezoelectric ceramics serving at high temperature.However,since these properties are usually mutually exclusive,high perfo...High piezoelectric properties and superior thermal stability are both important indicators of piezoelectric ceramics serving at high temperature.However,since these properties are usually mutually exclusive,high performance and superior thermal stability are hard to achieve simultaneously.Here we report that a high piezoelectricity(d_(33)∼562 pC/N)and superior thermal stability(the variation is within 7%from 20 to 330℃)were both achieved in 0.4 mol%ZnO-doped 0.02Pb(Sb_(1/2)Nb_(1/2))-0.51PbZrO_(3)-0.47PbTiO_(3) by high-temperature poling.Compared with traditional poling method,high-temperature poling method forms a small-sized and highly oriented domain structure,which can effectively improve the piezoelectric and dielectric properties of piezoelectric ceramics.At the same time,the enhanced pinning effect of defect ions and stabilized domain structure due to high-temperature poling also contribute to the superior temperature stability of the piezoelectric and dielectric properties.This work provides an effective method for designing piezoelectric materials with high performance and good temperature stability for high temperature sensor applications.展开更多
With vigorous developments in nanotechnology,the elaborate regulation of microstructure shows attractive potential in the design of electromagnetic wave absorbers.Herein,a hierarchical porous structure and composite h...With vigorous developments in nanotechnology,the elaborate regulation of microstructure shows attractive potential in the design of electromagnetic wave absorbers.Herein,a hierarchical porous structure and composite heterogeneous interface are constructed successfully to optimize the electromagnetic loss capacity.The macro–micro-synergistic graphene aerogel formed by the ice template‑assisted 3D printing strategy is cut by silicon carbide nanowires(SiC_(nws))grown in situ,while boron nitride(BN)interfacial structure is introduced on graphene nanoplates.The unique composite structure forces multiple scattering of incident EMWs,ensuring the combined effects of interfacial polarization,conduction networks,and magnetic-dielectric synergy.Therefore,the as-prepared composites present a minimum reflection loss value of−37.8 dB and a wide effective absorption bandwidth(EAB)of 9.2 GHz(from 8.8 to 18.0 GHz)at 2.5 mm.Besides,relying on the intrinsic high-temperature resistance of SiC_(nws) and BN,the EAB also remains above 5.0 GHz after annealing in air environment at 600℃ for 10 h.展开更多
Vanadium pentoxide(V_(2)O_(5))displays the characteristics of high theoretical specific capacity,high operating voltage,and adjustable layered structure,possessing the considerable potential as cathode in magnesium me...Vanadium pentoxide(V_(2)O_(5))displays the characteristics of high theoretical specific capacity,high operating voltage,and adjustable layered structure,possessing the considerable potential as cathode in magnesium metal batteries(MMBs).Nevertheless,the large charge-radius ratio of Mg^(2+)induces the strong interactions of Mg^(2+)with solvent molecules of electrolyte and anionic framework of cathode,resulting in a notable voltage polarization and structural deterioration during cycling process.Herein,an in-situ multi-scale structural engineering is proposed to activate the interlayer-expanded V_(2)O_(5)cathode(pillared by tetrabutylammonium cation)via adding hexadecyltrimethylammonium bromide(CTAB)additive into electrolyte.During cycling,the in-situ incorporation of CTA^(+)not only enhances the electrostatic shielding effect and Mg species migration,but also stabilizes the interlayer spacing.Besides,CTA^(+)is prone to be adsorbed on cathode surface and induces the loss-free pulverization and amorphization of electroactive grains,leading to the pronounced effect of intercalation pseudocapacitance.CTAB additive also enables to scissor the Mg^(2+)solvation sheath and tailor the insertion mode of Mg species,further endowing V_(2)O_(5)cathode with fast reaction kinetics.Based on these merits,the corresponding V2O5‖Mg full cells exhibit the remarkable rate performance with capacities as high as 317.6,274.4,201.1,and 132.7 mAh g^(-1)at the high current densities of 0.1,0.2,0.5,and 1 A g^(-1),respectively.Moreover,after 1000 cycles,the capacity is still preserved to be 90,4 mAh g^(-1)at 1 A g^(-1)with an average coulombic efficiency of~100%.Our strategy of synergetic modulations of cathode host and electrolyte solvation structures provides new guidance for the development of high-rate,large-capacity,and long-life MMBs.展开更多
High-temperature piezoelectric vibration sensors are the preferred choice for structural health monitoring in harsh environments such as high temperatures and complex vibrations.Bismuth layer-structured CaBi_(4)Ti_(4)...High-temperature piezoelectric vibration sensors are the preferred choice for structural health monitoring in harsh environments such as high temperatures and complex vibrations.Bismuth layer-structured CaBi_(4)Ti_(4)O_(15)(CBT)high-temperature piezoelectric ceramics,with high Curie temperature(TC),are the key components for piezoelectric vibration sensors operating at temperatures exceeding 500℃.However,their low piezoelectric coefficient(d_(33))greatly limits their high-temperature applications.In this work,a novel Bi^(3+)self-doping strategy was employed to enhance the piezoelectric performance of CBT ceramics.The enhancement is attributed to an increase in the number of grain boundaries,providing more sites for space charge accumulation and promoting formation of space charge polarization.Furthermore,given that space charge polarization predominantly occurs at low frequencies,dielectric temperature spectra at different frequencies were used to elucidate the mechanism by which space charge polarization enhances piezoelectric properties of CBT ceramics.Excellent overall performance was achieved for the CBT-based high-temperature piezoelectric ceramics.Among them,TC reached 778℃,d_(33) increased by more than 30%,reaching 20.1 pC/N,and the electrical resistivity improved by one order of magnitude(reaching 6.33×10^(6)Ω·cm at 500℃).These advancements provide a key functional material with excellent performance for practical applications of piezoelectric vibration sensors at 500℃and above.展开更多
Ceramic dielectric materials with high dielectric strength and mechanisms of their internal factors affecting dielectric strength are significantly valuable for industrial application,especially for selection of suita...Ceramic dielectric materials with high dielectric strength and mechanisms of their internal factors affecting dielectric strength are significantly valuable for industrial application,especially for selection of suitable dielectric materials for high-power microwave transmission devices and reliable power transmission.Pure magnesium oxide(MgO),a kind of ceramic dielectric material,possesses great application potential in high-power microwave transmission devices due to its high theoretical dielectric strength,low dielectric constant,and low dielectric loss properties,but its application is limited by high sintering temperature during preparation.This work presented the preparation of a new type of multiphase ceramics based on MgO,which was MgO-1%ZrO_(2)-1%CaCO_(3-x)%MnCO_(3)(MZCM_(x),x=0,0.25,0.50,1.00,1.50,in molar),and their phase structures,morphological features,and dielectric properties were investigated.It was found that inclusion of ZrO_(2) and CaCO_(3) effectively inhibited excessive growth of MgO grains by formation of second phase,while addition of MnCO_(3) promoted the grain boundary diffusion process during the sintering process and reduced activation energy for the grain growth,resulting in a lower ceramic sintering temperature.Excellent performance,including high dielectric strength(Eb=92.3 kV/mm)and quality factor(Q×f=216642 GHz),simultaneously accompanying low dielectric loss(<0.03%),low temperature coefficient of dielectric constant(20.3×10^(–6)℃^(–1),85℃)and resonance frequency(–12.54×10^(–6)℃^(–1)),was achieved in MZCM1.00 ceramics under a relatively low sintering temperature of 1350℃.This work offers an effective solution for selecting dielectric materials for high-power microwave transmission devices.展开更多
Severe lithium dendrite growth and elevated thermal runaway risks pose significant hurdles for fast-charging lithium metal batteries(LMBs)This study reports a polydopamine-functionalized hydroxyapatite/aramid(PDA@HA)h...Severe lithium dendrite growth and elevated thermal runaway risks pose significant hurdles for fast-charging lithium metal batteries(LMBs)This study reports a polydopamine-functionalized hydroxyapatite/aramid(PDA@HA)hybrid nanofibers separator to synchronously improve th fast-charging LMB's stability and safety.(1)The separator's surface,enriched with lithiophilic carbonyl and hydroxyl groups,accelerates Li~+ion desolvation,while electrophilic imine groups impede anion movement.This dual mechanism optimizes the Li^(+)-ion flux distribution on th anode,mitigating dendrite formation.(2)The polar PDA modification layer fosters the development of a Li_(3)N/LiF-rich solid electrolyt interface,further enhancing Li anode stability.Consequently,Li//Li symmetric cells with PDA@HA separators exhibit extended cycle life in L plating/stripping tests:5000 h at 1 mA cm^(-2)and 700 h at 20 mA cm^(-2),respectively,outperforming PP separators(80 h and 8 h).In LiFePO_(4)(LFP,^(2.1)mg cm^(-2))//Li full cell evaluation,the PDA@HA separator enables stable operation for 11,000 cycles at 18.2C with 87%capacity retention,significantly outperforming existing fast-charging LMB counterparts in literature.At a high LFP loading of 15.5 mg cm^(-2),the cel maintains 137.6 mAh g^(-1)(2.13 mAh cm^(-2))over 250 cycles at 3C,achieving 98%capacity retention.Moreover,the PDA@HA separato increases threshold temperature for thermal runaway and reduces the exothermic rate,intensifying the battery's thermal safety.This research underscores the importance of functional separator design in improving Li metal anode reversibility,fast-charging performance,and therma safety of LMBs.展开更多
Poor Li plating reversibility and high thermal runaway risks are key challenges for fast charging lithiumion batteries with graphite anodes.Herein,a dielectric and fire-resistant separator based on hybrid nanofibers o...Poor Li plating reversibility and high thermal runaway risks are key challenges for fast charging lithiumion batteries with graphite anodes.Herein,a dielectric and fire-resistant separator based on hybrid nanofibers of barium sulfate(BS)and bacterial cellulose(BC)is developed to synchronously enhance the battery's fast charging and thermal-safety performances.The regulation mechanism of the dielectric BS/BC separator in enhancing the Li^(+)ion transport and Li plating reversibility is revealed.(1)The Max-Wagner polarization electric field of the dielectric BS/BC separator can accelerate the desolvation of solvated Li^(+)ions,enhancing their transport kinetics.(2)Moreover,due to the charge balancing effect,the dielectric BS/BC separator homogenizes the electric field/Li^(+)ion flux at the graphite anode-separator interface,facilitating uniform Li plating and suppressing Li dendrite growth.Consequently,the fast-charge graphite anode with the BS/BC separator shows higher Coulombic efficiency(99.0%vs.96.9%)and longer cycling lifespan(100 cycles vs.59 cycles)than that with the polypropylene(PP)separator in the constantlithiation cycling test at 2 mA cm^(-2).The high-loading LiFePO4(15.5 mg cm^(-2))//graphite(7.5 mg cm^(-2))full cell with the BS/BC separator exhibits excellent fast charging performance,retaining 70%of its capacity after 500 cycles at a high rate of 2C,which is significantly better than that of the cell with the PP separator(retaining only 27%of its capacity after 500 cycles).More importantly,the thermally stable BS/BC separator effectively elevates the critical temperature and reduces the heat release rate during thermal runaway,thereby significantly enhancing the battery's safety.展开更多
Solid-state polymer sodium batteries(SPSBs)are promising candidates for achieving higher energy density and safe energy storage.However,interface issues between oxide cathode and solid-state polymer electrolyte are a ...Solid-state polymer sodium batteries(SPSBs)are promising candidates for achieving higher energy density and safe energy storage.However,interface issues between oxide cathode and solid-state polymer electrolyte are a great challenge for their commercial application.In contrast,soft sulfur-based materials feature better interface contact and chemical compatibility.Herein,an interfacial compatible polysulfide Ti_(4)P_(8)S_(29) with robust Ti-S bonding and a highly active P-S unit is tailored as a high-performance cathode for SPSBs.The Ti_(4)P_(8)S_(29) cathode possesses a three-dimensional channel structure for offering ample Na+diffusion pathways.The assembled poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)-based SPSBs deliver a discharge capacity of 136 mAh·g^(-1)at 0.5C after 200 cycles.Furthermore,a discharge capacity of 88 mAh·g^(-1)is retained after 600 cycles at a high rate of 2C,surpassing many cathode materials in SPSBs.A dual-site redox of Ti^(4+)/Ti^(3+)and S^(-)/S^(2-)is verified by X-ray photoelectron spectroscopy(XPS)and cyclic voltammetry(CV)tests.Interestingly,a refined locally-ordered amorphous structure is unveiled by in situ and ex situ characterizations.The as-formed electrode structure with lots of open channels and isotropic properties are more beneficial for ion diffusion on the interface of electrode and solid-state polymer electrolytes(SPEs),leading to faster Na+diffusion kinetics.This work proposes a strategy of modulating open-channel to boost conversion kinetics in polysulfide cathode and opens a new pathway for designing high-performance SPSBs.展开更多
The bismuth-telluride-based alloy is the only thermoelectric material commercialized for the applications of refrigeration and energy harvesting,but its low cost-effectiveness severely restricts its large-scale ap-pli...The bismuth-telluride-based alloy is the only thermoelectric material commercialized for the applications of refrigeration and energy harvesting,but its low cost-effectiveness severely restricts its large-scale ap-plication.The introduction of a porous structure in bulk thermoelectric materials has been theoretically proven to effectively reduce thermal conductivity and cost.However,the electrical properties of highly porous materials are considerably suppressed due to the strong carrier scattering at the interface be-tween the matrix and pores,ultimately leading to decreased figure of merit,ZT.Here,we use an atomic layer deposition strategy to introduce some hollow glass bubbles with nano-oxide layers into commercial Bi_(0.5)Sb_(1.5)Te_(3)for preparing high-performance porous thermoelectric materials.Experimental results indi-cate that the nano-oxide layers weaken carrier scattering at the interface between pores and matrix while maintaining high-strength phonon scattering,thereby optimizing carrier/phonon transport behaviors,and effectively increasing the ZT by 23.2%(from 0.99 to 1.22 at 350 K).Besides,our strategy has excellent universality confirmed by its effectiveness in improving the ZT of Bi_(2)Te_(2.7)Se_(0.3),therefore demonstrating great potential for developing low-cost and high-performance thermoelectric materials.展开更多
As a promising cathode material,Na_(3)V_(2)(PO_(4))_(2)F_(3)(NVPF)has attracted wide attention for sodium-ion batteries(SIBs)because of its high operating voltage and high structural stability.However,the low intrinsi...As a promising cathode material,Na_(3)V_(2)(PO_(4))_(2)F_(3)(NVPF)has attracted wide attention for sodium-ion batteries(SIBs)because of its high operating voltage and high structural stability.However,the low intrinsic electronic conductivity and insufficient Na ion mobility of NVPF limit its development.Herein,K-doping NVPF is prepared through a facile ball-milling combined calcination method.The effects of K-doping on the crystal structure,kinetic properties and electrochemical performance are investigated.The results demonstrate that the Na_(2.90)K_(0.10)V_(2)(PO_(4))_(3)F_(3)(K0.10-NVPF)exhibits a high capacity(120.8 mAh g^(-1) at 0.1 C),high rate capability(66 mAh g^(-1) at 30 C)and excellent cycling performance(a capacity retention of 97.5%at 1 C over 500 cycles).Also,the occupation site of K ions in the lattice,electronic band structure and Na-ion transport kinetic property in K-doped NVPF are investigated by density functional theory(DFT)calculations,which reveals that the K-doped NVPF exhibits improved electronic and ionic conductivities,and located K^(+) ions in the lattice to contribute to high reversible capacity,rate capability and cycling stability.Therefore,the K-doped NVPF serves as a promising cathode material for high-energy and high-power SIBs.展开更多
Among various earth-abundant and noble metal-free catalysts for oxygen reduction reaction(ORR),manganese-based oxides are promising candidates owing to the rich variety of manganese valence.Herein,an extremely facile ...Among various earth-abundant and noble metal-free catalysts for oxygen reduction reaction(ORR),manganese-based oxides are promising candidates owing to the rich variety of manganese valence.Herein,an extremely facile method for the synthesis of cubic and orthorhombic phase coexisting Mn(Ⅱ)O electrocatalyst as an efficient ORR catalyst was explored.The obtained MnO electrocatalyst with oxygen vacancies shows a significantly elevated ORR catalytic activity with a half-wave potential(E1/2) of as high as 0.895 V,in comparison with that of commercial Pt/C(E1/2=0.877 V).More impressively,the MnO electrocatalyst exhibits a marked activity enhancement after test under a constant applied potential for 1000 s thanks to the in situ generation and stable presence of high-valence manganese species(Mn^3+ and Mn^4+) during the electrochemical process,initiating a synergetic catalytic effect with oxygen vacancies,which is proved to largely accelerate the adsorption and reduction of O_2 molecules favoring the ORR activity elevation.Such an excellent ORR catalytic performance of this MnO electrocatalyst is applied in Zn-air battery,which shows an extra-high peak power density of 63.2 mW cm^-2 in comparison with that(47.4 m W cm^-2) of commercial Pt/C under identical test conditions.展开更多
Na-ion O3-type layered oxides are prospective cathodes for Na-ion batteries due to high energy density and low-cost.Nevertheless,such cathodes usually suffer from phase transitions,sluggish kinetics and air instabilit...Na-ion O3-type layered oxides are prospective cathodes for Na-ion batteries due to high energy density and low-cost.Nevertheless,such cathodes usually suffer from phase transitions,sluggish kinetics and air instability,making it difficult to achieve high performance solid-state sodium-ion batteries.Herein,the high-entropy design and Li doping strategy alleviate lattice stress and enhance ionic conductivity,achieving high-rate performance,air stability and electrochemically thermal stability for Na_(0.95)Li_(0.06)Ni_(0.25)Cu_(0.05)Fe_(0.15)Mn_(0.49)O_(2).This cathode delivers a high reversible capacity(141 mAh g^(−1)at 0.2C),excellent rate capability(111 mAh g^(−1)at 8C,85 mAh g^(−1)even at 20C),and long-term stability(over 85%capacity retention after 1000 cycles),which is attributed to a rapid and reversible O3–P3 phase transition in regions of low voltage and suppresses phase transition.Moreover,the compound remains unchanged over seven days and keeps thermal stability until 279℃.Remarkably,the polymer solid-state sodium battery assembled by this cathode provides a capacity of 92 mAh g^(−1)at 5C and keeps retention of 96%after 400 cycles.This strategy inspires more rational designs and could be applied to a series of O3 cathodes to improve the performance of solid-state Na-ion batteries.展开更多
Lead-free ferroelectric ceramics,0.67Bi_(1-x)Eu_(x)FeO_(3)-0.33BaTiO_(3)(BF-BT-xEu,x=0-0.02),were prepared via a solid-state reaction,The effect of Eu^(3+) doping on the microstructure,dielectric properties,ferroelect...Lead-free ferroelectric ceramics,0.67Bi_(1-x)Eu_(x)FeO_(3)-0.33BaTiO_(3)(BF-BT-xEu,x=0-0.02),were prepared via a solid-state reaction,The effect of Eu^(3+) doping on the microstructure,dielectric properties,ferroelectric properties,and electric-field-induced strain was investigated.The X-ray diffraction(XRD) results indicate the presence of a mixed phase of tetragonal and rhombohedral at the morphotropic phase boundary(MPB).Doping with an appropriate amount of Eu^(3+) reduces the Fe^(3+) content and decreases the leakage current in the binary system.A converse piezoelectric coefficient(d_(33)*) of 392 pm/V is obtained at BF-BT-0.003Eu under an electric field of 60 kV/cm at room temperature,which has a Curie temperature(T_(C)) of 414℃,The unipolar strain and d_(33)* of BF-BT-0.003Eu ceramics increase to 0.438%and 730 pm/V at 125℃ The field-induced strain response of the BF-BT-0.003Eu ceramics is greater than that of 0.67BF-0.33BT,mainly due to its optimal grain size,reduction of leakage current,and coexistence of ferroelectric-relaxation phases,BF-BT-0.003Eu ceramic is a lead-free candidate for high-temperature actuator applications.展开更多
ZrB_(2)-based ceramics typically necessitate high temperature and pressure for sintering,whereas ZrB_(2)-SiC ceramics can be fabricated at 1500℃using the process of reactive melt infiltration with Si.In comparison to...ZrB_(2)-based ceramics typically necessitate high temperature and pressure for sintering,whereas ZrB_(2)-SiC ceramics can be fabricated at 1500℃using the process of reactive melt infiltration with Si.In comparison to the conventional preparation method,reactive synthesis allows for the more facile production of ultra-high temperature ceramics with fine particle size and homogeneous composition.In this work,ZrSi_(2),B4C,and C were used as raw materials to prepare ZrB_(2)-SiC via combination of tape casting and reactive melt infiltration herein referred to as ZBC ceramics.Control sample of ZrB_(2)-SiC was also prepared using ZrB_(2)and SiC as raw materials through an identical process designated as ZS ceramics.Microscopic analysis of both ceramic groups revealed smaller and more uniformly distributed particles of the ZrB_(2)phase in ZBC ceramics compared to the larger particles in ZS ceramics.Both sets of ceramics underwent cyclic oxidation testing in the air at 1600℃for a cumulative duration of 5 cycles,each cycle lasting 2 h.Analysis of the oxidation behavior showed that both ZBC ceramics and ZS ceramics developed a glassy SiO_(2)-ZrO_(2)oxide layer on their surfaces during the oxidation.This layer severed as a barrier against oxygen.In ZBC ceramics,ZrO_(2)is finely distributed in SiO_(2),whereas in ZS ceramics,larger ZrO_(2)particles coexist with glassy SiO_(2).The surface oxide layer of ZBC ceramics maintains a dense structure because the well-dispersed ZrO_(2)increases the viscosity of glassy SiO_(2),preventing its crystallization during the cooling.Conversely,some SiO_(2)in the oxide layer of ZS ceramics may crystallize and form a eutectic with ZrO_(2),leading to the formation of ZrSiO_(4).This leads to cracking of the oxide layer due to differences in thermal expansion coefficients,weakening its barrier effect.An analysis of the oxidation resistance shows that ZBC ceramics exhibit less increase in oxide layer thickness and mass compared to ZS ceramics,suggesting superior oxidation resistance of ZBC ceramics.展开更多
Bioceramics have attracted extensive attention for bone defect repair due to their excellent bioactivity and degradability.However,challenges remain in matching the rate between bioceramic degradation and new bone for...Bioceramics have attracted extensive attention for bone defect repair due to their excellent bioactivity and degradability.However,challenges remain in matching the rate between bioceramic degradation and new bone formation,necessitating a deeper understanding of their degradation properties.In this study,density functional theory(DFT)calculations was employed to explore the structural and electronic characteristics of silicate bioceramics.These findings reveal a linear correlation between the maximum isosurface value of the valence band maximum(VBM_(Fmax))and the degradability of silicate bioceramics.This correlation was subsequently validated through degradation experiments.Furthermore,the investigation on phosphate bioceramics demonstrates the potential of this descriptor in predicting the degradability of a broader range of bioceramics.This discovery offers valuable insights into the degradation mechanism of bioceramics and holds promise for accelerating the design and development of bioceramics with controllable degradation.展开更多
Sodium-ion batteries are economical and environmentally sustainable energy storage batteries.Among them,β-NaMnO_(2),a promising sodium-ion cathode material,is a manganese-based oxide with a corrugated laminar structu...Sodium-ion batteries are economical and environmentally sustainable energy storage batteries.Among them,β-NaMnO_(2),a promising sodium-ion cathode material,is a manganese-based oxide with a corrugated laminar structure,which has attracted significant attention due to its structural robustness and relatively high specific capacity.However,it has short cycle life and poor rate capability.To address these issues,Ti atoms,known for enhancing structural stability,and Cu atoms,which facilitate desodiation,were doped intoβ-NaMnO_(2) by first-principles calculation and crystal orbital Hamilton population(COHP)analysis.β-NaMn_(0.8)Ti_(0.1)Cu_(0.1)O_(2) exhibits a notable increase in reversible specific capacity and remarkable rate properties.Operating at a current density of 0.2C(1C=219 mA·g^(–1))and within a voltage range of 1.8–4.0 V,the modified material delivers an initial discharge capacity of 132 mAh·g^(–1).After charge/discharge testing at current densities of 0.2C,0.5C,1C,3C,and 0.2C,the material still maintains a capacity of 110 mA h·g^(–1).The doping of Ti atoms slows down the changes in the crystal structure,resulting in only minimal variation in the lattice constant c/a during the desodiation process.Mn and Cu engage in reversible redox reactions at voltages below 3.0 V and around 3.5 V,respectively.The extended plateau observed in the discharge curve below 3.0 V signifies that Mn significantly contributes to the overall battery capacity.This study provides insights into modifyingβ-NaMnO_(2) as a cathode material,offering experimental evidence and theoretical guidance for enhancing battery performance in Na-ion batteries.展开更多
Under illumination by 405,520 and 655 nm monochromatic visible light(light intensity of 30 kW/m^(2)),large photostriction(ΔL/L)of 0.19%,0.13%and 0.26%for 67BiFeO_(3)-33BaTiO_(3)(67BF-33BT)lead-free ferroelectric cera...Under illumination by 405,520 and 655 nm monochromatic visible light(light intensity of 30 kW/m^(2)),large photostriction(ΔL/L)of 0.19%,0.13%and 0.26%for 67BiFeO_(3)-33BaTiO_(3)(67BF-33BT)lead-free ferroelectric ceramics are obtained,respectively.By studying the ferroelectric and photoelectric properties in conjunction with in situ Raman spectroscopy,it is found that the photostrictive effect of 67BF-33BT is not caused by the electrical strain induced by abnormal photovoltaic voltage,but related to the optical induced oxygen octahedral distortion.The 67BF-33BT lead-free ferroelectric material with excellent photostrictive response in the visible light region is expected to play an important role in the field of optical drive electromechanical devices.展开更多
基金supported by the National Natural Science Foundation of China(52372099,52202328,22461142135,22479046)the Shanghai Sailing Program(22YF1455500)the Shanghai Magnolia Talent Plan Pujiang Project(24PJD128)。
文摘Solid-state polymer electrolytes are crucial for advancing solid-state lithium-metal batteries owing to their flexibility,excellent manufacturability,and strong interfacial compatibility.However,their widespread applications are hindered by low ionic conductivity at room temperature and lithium dendrite growth.Herein,we report a novel solid-state composite membrane electrolyte design that combines the vertically aligned channel structure and copolymer with a radial gradient composition.Within the vertically aligned channels,the composition of poly(vinyl ethylene carbonate-co-poly(ethylene glycol)diacrylate)(P(VEC-PEGDA)varies in a gradient along the radial direction:from the center to the wall of vertically aligned channels,the proportion of vinyl ethylene carbonate(VEC)in the copolymer decreases,while the proportion of poly(ethylene glycol)diacrylate(PEGDA)increases accordingly.It can be functionally divided into a mechanical-reinforcement layer and a fast-ion-conducting layer.The resulting solid-state composite membrane electrolyte achieves a high critical current density of 1.2 mA cm^(-2)and high ionic conductivity of 2.03 mS cm^(-1)at room temperature.Employing this composite membrane electrolyte,a Li//Li symmetric cell exhibits stable cycling for over 1850 h at 0.2 m A cm^(-2)/0.2 m A h cm^(-2),and a Li//LiFePO4(LFP)battery maintains 77.3% capacity retention at 2 C after 300 cycles.Our work provides insight into the rational design of safer and more efficient solidstate batteries through electrolyte structural engineering.
基金supported by the National Natural Science Foundation of China(Nos.92163118,51972234)。
文摘The development of aqueous zinc ion battery cathode materials with high capacity and high magnification is still a challenge.Herein,porous vanadium oxide/carbon(p-VO_(x)@C,mainly VO_(2) with a small amount of V_(2)O_(3)) core/shell microspheres with oxygen vacancies are facilely fabricated by using a vanadium-based metal-organic framework(MIL-100(V)) as a sacrificial template.This unique structure can improve the conductivity of the VO_(x),accelerate electrolyte diffusion,and suppress structural collapse during circulation.Subsequently,H_(2)O molecules are introduced into the interlayer of VO_(x) through a highly efficient in-situ electrochemical activation process,facilitating the intercalation and diffusion of zinc ions.After the activation,an optimal sample exhibits a high specific capacity of 464.3 mA h g^(-1) at0.2 A g^(-1) and 395.2 mA h g^(-1) at 10 A g^(-1),indicating excellent rate performance.Moreover,the optimal sample maintains a capacity retention of about 89.3% after 2500 cycles at 10 A g^(-1).Density functional theory calculation demonstrates that the presence of oxygen vacancies and intercalated water molecules can significantly reduce the diffusion barrier for zinc ions.In addition,it is proved that the storage of zinc ions in the cathode is achieved by reversible intercalation/extraction during the charge and discharge process through various ex-situ analysis technologies.This work demonstrates that the p-VO_(x)@C has great potential for applications in aqueous ZIBs after electrochemical activation.
基金National Natural Science Foundation of China (Nos. 92163118 and 51972234).
文摘In this work,Ag/Ag_(2)Se composite films with excellent thermoelectric(TE)properties and flexibility are prepared based on a simple one-pot method.By adjusting the nominal ratios of Ag/Se,an optimal Ag/Ag_(2)Se composite film shows a large power factor of~2275 μW m^(-1) K^(-2) at 300 K.Such an outstand-ing TE performance of the composite film is due to the unique microstructure and the synergistic effect between the Ag and Ag_(2)Se.Meanwhile,the composite film also shows outstanding flexibility(~91.8%of the initial electrical conductivity is maintained,and the S is unchanged after 1500 bending cycles with a bending radius of 4 mm).Furthermore,a 4-leg flexible TE generator assembled with the optimal film produces a voltage of 14.06 mV and 4.96 μW at a temperature difference of 30.4 K.This work provides a new inspiration for the preparation of flexible Ag_(2)Se-based films with excellent TE performance near room temperature.
基金financially supported by the National Key Research and Development Program of China(No.2018YFC0308603)the Pilot Technology for Chinese Academy of Sciences(No.XDA2203003)the National Natural Science Foundation of China(Nos.51972321 and 51879269)。
文摘High piezoelectric properties and superior thermal stability are both important indicators of piezoelectric ceramics serving at high temperature.However,since these properties are usually mutually exclusive,high performance and superior thermal stability are hard to achieve simultaneously.Here we report that a high piezoelectricity(d_(33)∼562 pC/N)and superior thermal stability(the variation is within 7%from 20 to 330℃)were both achieved in 0.4 mol%ZnO-doped 0.02Pb(Sb_(1/2)Nb_(1/2))-0.51PbZrO_(3)-0.47PbTiO_(3) by high-temperature poling.Compared with traditional poling method,high-temperature poling method forms a small-sized and highly oriented domain structure,which can effectively improve the piezoelectric and dielectric properties of piezoelectric ceramics.At the same time,the enhanced pinning effect of defect ions and stabilized domain structure due to high-temperature poling also contribute to the superior temperature stability of the piezoelectric and dielectric properties.This work provides an effective method for designing piezoelectric materials with high performance and good temperature stability for high temperature sensor applications.
基金sponsored by National Natural Science Foundation of China(No.52302121,No.52203386)Shanghai Sailing Program(No.23YF1454700)+1 种基金Shanghai Natural Science Foundation(No.23ZR1472700)Shanghai Post-doctoral Excellent Program(No.2022664).
文摘With vigorous developments in nanotechnology,the elaborate regulation of microstructure shows attractive potential in the design of electromagnetic wave absorbers.Herein,a hierarchical porous structure and composite heterogeneous interface are constructed successfully to optimize the electromagnetic loss capacity.The macro–micro-synergistic graphene aerogel formed by the ice template‑assisted 3D printing strategy is cut by silicon carbide nanowires(SiC_(nws))grown in situ,while boron nitride(BN)interfacial structure is introduced on graphene nanoplates.The unique composite structure forces multiple scattering of incident EMWs,ensuring the combined effects of interfacial polarization,conduction networks,and magnetic-dielectric synergy.Therefore,the as-prepared composites present a minimum reflection loss value of−37.8 dB and a wide effective absorption bandwidth(EAB)of 9.2 GHz(from 8.8 to 18.0 GHz)at 2.5 mm.Besides,relying on the intrinsic high-temperature resistance of SiC_(nws) and BN,the EAB also remains above 5.0 GHz after annealing in air environment at 600℃ for 10 h.
基金supported by the National Natural Science Foundation of China(52372249)support by the Program of Shanghai Academic Research Leader(21XD1424400)。
文摘Vanadium pentoxide(V_(2)O_(5))displays the characteristics of high theoretical specific capacity,high operating voltage,and adjustable layered structure,possessing the considerable potential as cathode in magnesium metal batteries(MMBs).Nevertheless,the large charge-radius ratio of Mg^(2+)induces the strong interactions of Mg^(2+)with solvent molecules of electrolyte and anionic framework of cathode,resulting in a notable voltage polarization and structural deterioration during cycling process.Herein,an in-situ multi-scale structural engineering is proposed to activate the interlayer-expanded V_(2)O_(5)cathode(pillared by tetrabutylammonium cation)via adding hexadecyltrimethylammonium bromide(CTAB)additive into electrolyte.During cycling,the in-situ incorporation of CTA^(+)not only enhances the electrostatic shielding effect and Mg species migration,but also stabilizes the interlayer spacing.Besides,CTA^(+)is prone to be adsorbed on cathode surface and induces the loss-free pulverization and amorphization of electroactive grains,leading to the pronounced effect of intercalation pseudocapacitance.CTAB additive also enables to scissor the Mg^(2+)solvation sheath and tailor the insertion mode of Mg species,further endowing V_(2)O_(5)cathode with fast reaction kinetics.Based on these merits,the corresponding V2O5‖Mg full cells exhibit the remarkable rate performance with capacities as high as 317.6,274.4,201.1,and 132.7 mAh g^(-1)at the high current densities of 0.1,0.2,0.5,and 1 A g^(-1),respectively.Moreover,after 1000 cycles,the capacity is still preserved to be 90,4 mAh g^(-1)at 1 A g^(-1)with an average coulombic efficiency of~100%.Our strategy of synergetic modulations of cathode host and electrolyte solvation structures provides new guidance for the development of high-rate,large-capacity,and long-life MMBs.
基金National Natural Science Foundation of China (51932010)。
文摘High-temperature piezoelectric vibration sensors are the preferred choice for structural health monitoring in harsh environments such as high temperatures and complex vibrations.Bismuth layer-structured CaBi_(4)Ti_(4)O_(15)(CBT)high-temperature piezoelectric ceramics,with high Curie temperature(TC),are the key components for piezoelectric vibration sensors operating at temperatures exceeding 500℃.However,their low piezoelectric coefficient(d_(33))greatly limits their high-temperature applications.In this work,a novel Bi^(3+)self-doping strategy was employed to enhance the piezoelectric performance of CBT ceramics.The enhancement is attributed to an increase in the number of grain boundaries,providing more sites for space charge accumulation and promoting formation of space charge polarization.Furthermore,given that space charge polarization predominantly occurs at low frequencies,dielectric temperature spectra at different frequencies were used to elucidate the mechanism by which space charge polarization enhances piezoelectric properties of CBT ceramics.Excellent overall performance was achieved for the CBT-based high-temperature piezoelectric ceramics.Among them,TC reached 778℃,d_(33) increased by more than 30%,reaching 20.1 pC/N,and the electrical resistivity improved by one order of magnitude(reaching 6.33×10^(6)Ω·cm at 500℃).These advancements provide a key functional material with excellent performance for practical applications of piezoelectric vibration sensors at 500℃and above.
基金Student Training Program for Innovation and Entrepreneurship of Hangzhou Institute for Advanced Study,UCAS(CXCY20230305)Chinese Academy of Sciences Key Project(ZDRW-CN-2021-3-1-18)。
文摘Ceramic dielectric materials with high dielectric strength and mechanisms of their internal factors affecting dielectric strength are significantly valuable for industrial application,especially for selection of suitable dielectric materials for high-power microwave transmission devices and reliable power transmission.Pure magnesium oxide(MgO),a kind of ceramic dielectric material,possesses great application potential in high-power microwave transmission devices due to its high theoretical dielectric strength,low dielectric constant,and low dielectric loss properties,but its application is limited by high sintering temperature during preparation.This work presented the preparation of a new type of multiphase ceramics based on MgO,which was MgO-1%ZrO_(2)-1%CaCO_(3-x)%MnCO_(3)(MZCM_(x),x=0,0.25,0.50,1.00,1.50,in molar),and their phase structures,morphological features,and dielectric properties were investigated.It was found that inclusion of ZrO_(2) and CaCO_(3) effectively inhibited excessive growth of MgO grains by formation of second phase,while addition of MnCO_(3) promoted the grain boundary diffusion process during the sintering process and reduced activation energy for the grain growth,resulting in a lower ceramic sintering temperature.Excellent performance,including high dielectric strength(Eb=92.3 kV/mm)and quality factor(Q×f=216642 GHz),simultaneously accompanying low dielectric loss(<0.03%),low temperature coefficient of dielectric constant(20.3×10^(–6)℃^(–1),85℃)and resonance frequency(–12.54×10^(–6)℃^(–1)),was achieved in MZCM1.00 ceramics under a relatively low sintering temperature of 1350℃.This work offers an effective solution for selecting dielectric materials for high-power microwave transmission devices.
基金supported by the National Natural Science Foundation of China(Grant No.52202328,52372099,52271222)the Shanghai Sailing Program(22YF1455500)。
文摘Severe lithium dendrite growth and elevated thermal runaway risks pose significant hurdles for fast-charging lithium metal batteries(LMBs)This study reports a polydopamine-functionalized hydroxyapatite/aramid(PDA@HA)hybrid nanofibers separator to synchronously improve th fast-charging LMB's stability and safety.(1)The separator's surface,enriched with lithiophilic carbonyl and hydroxyl groups,accelerates Li~+ion desolvation,while electrophilic imine groups impede anion movement.This dual mechanism optimizes the Li^(+)-ion flux distribution on th anode,mitigating dendrite formation.(2)The polar PDA modification layer fosters the development of a Li_(3)N/LiF-rich solid electrolyt interface,further enhancing Li anode stability.Consequently,Li//Li symmetric cells with PDA@HA separators exhibit extended cycle life in L plating/stripping tests:5000 h at 1 mA cm^(-2)and 700 h at 20 mA cm^(-2),respectively,outperforming PP separators(80 h and 8 h).In LiFePO_(4)(LFP,^(2.1)mg cm^(-2))//Li full cell evaluation,the PDA@HA separator enables stable operation for 11,000 cycles at 18.2C with 87%capacity retention,significantly outperforming existing fast-charging LMB counterparts in literature.At a high LFP loading of 15.5 mg cm^(-2),the cel maintains 137.6 mAh g^(-1)(2.13 mAh cm^(-2))over 250 cycles at 3C,achieving 98%capacity retention.Moreover,the PDA@HA separato increases threshold temperature for thermal runaway and reduces the exothermic rate,intensifying the battery's thermal safety.This research underscores the importance of functional separator design in improving Li metal anode reversibility,fast-charging performance,and therma safety of LMBs.
基金financially supported by the National Natural Science Foundation of China(Grant No.52202328,52372099)the Shanghai Sailing Program(22YF1455500).
文摘Poor Li plating reversibility and high thermal runaway risks are key challenges for fast charging lithiumion batteries with graphite anodes.Herein,a dielectric and fire-resistant separator based on hybrid nanofibers of barium sulfate(BS)and bacterial cellulose(BC)is developed to synchronously enhance the battery's fast charging and thermal-safety performances.The regulation mechanism of the dielectric BS/BC separator in enhancing the Li^(+)ion transport and Li plating reversibility is revealed.(1)The Max-Wagner polarization electric field of the dielectric BS/BC separator can accelerate the desolvation of solvated Li^(+)ions,enhancing their transport kinetics.(2)Moreover,due to the charge balancing effect,the dielectric BS/BC separator homogenizes the electric field/Li^(+)ion flux at the graphite anode-separator interface,facilitating uniform Li plating and suppressing Li dendrite growth.Consequently,the fast-charge graphite anode with the BS/BC separator shows higher Coulombic efficiency(99.0%vs.96.9%)and longer cycling lifespan(100 cycles vs.59 cycles)than that with the polypropylene(PP)separator in the constantlithiation cycling test at 2 mA cm^(-2).The high-loading LiFePO4(15.5 mg cm^(-2))//graphite(7.5 mg cm^(-2))full cell with the BS/BC separator exhibits excellent fast charging performance,retaining 70%of its capacity after 500 cycles at a high rate of 2C,which is significantly better than that of the cell with the PP separator(retaining only 27%of its capacity after 500 cycles).More importantly,the thermally stable BS/BC separator effectively elevates the critical temperature and reduces the heat release rate during thermal runaway,thereby significantly enhancing the battery's safety.
基金supported by the National Key Research and Development Program of China(No.2019YFA0210600)the National Natural Science Foundation of China(Nos.51922103 and 51972326)+1 种基金the Natural Science Foundation of Jiangxi Province(Nos.20224BAB204002 and GJJ211320)Jingdezhen Science and Technology Bureau(No.20212GYZD009-15)。
文摘Solid-state polymer sodium batteries(SPSBs)are promising candidates for achieving higher energy density and safe energy storage.However,interface issues between oxide cathode and solid-state polymer electrolyte are a great challenge for their commercial application.In contrast,soft sulfur-based materials feature better interface contact and chemical compatibility.Herein,an interfacial compatible polysulfide Ti_(4)P_(8)S_(29) with robust Ti-S bonding and a highly active P-S unit is tailored as a high-performance cathode for SPSBs.The Ti_(4)P_(8)S_(29) cathode possesses a three-dimensional channel structure for offering ample Na+diffusion pathways.The assembled poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)-based SPSBs deliver a discharge capacity of 136 mAh·g^(-1)at 0.5C after 200 cycles.Furthermore,a discharge capacity of 88 mAh·g^(-1)is retained after 600 cycles at a high rate of 2C,surpassing many cathode materials in SPSBs.A dual-site redox of Ti^(4+)/Ti^(3+)and S^(-)/S^(2-)is verified by X-ray photoelectron spectroscopy(XPS)and cyclic voltammetry(CV)tests.Interestingly,a refined locally-ordered amorphous structure is unveiled by in situ and ex situ characterizations.The as-formed electrode structure with lots of open channels and isotropic properties are more beneficial for ion diffusion on the interface of electrode and solid-state polymer electrolytes(SPEs),leading to faster Na+diffusion kinetics.This work proposes a strategy of modulating open-channel to boost conversion kinetics in polysulfide cathode and opens a new pathway for designing high-performance SPSBs.
基金supported by the National Natural Science Foundation of China(Nos.U21A2054,21905007)the Key Discipline of Materials Science and Engineering,Bureau of Education of Guangzhou(Grant No.202255464).
文摘The bismuth-telluride-based alloy is the only thermoelectric material commercialized for the applications of refrigeration and energy harvesting,but its low cost-effectiveness severely restricts its large-scale ap-plication.The introduction of a porous structure in bulk thermoelectric materials has been theoretically proven to effectively reduce thermal conductivity and cost.However,the electrical properties of highly porous materials are considerably suppressed due to the strong carrier scattering at the interface be-tween the matrix and pores,ultimately leading to decreased figure of merit,ZT.Here,we use an atomic layer deposition strategy to introduce some hollow glass bubbles with nano-oxide layers into commercial Bi_(0.5)Sb_(1.5)Te_(3)for preparing high-performance porous thermoelectric materials.Experimental results indi-cate that the nano-oxide layers weaken carrier scattering at the interface between pores and matrix while maintaining high-strength phonon scattering,thereby optimizing carrier/phonon transport behaviors,and effectively increasing the ZT by 23.2%(from 0.99 to 1.22 at 350 K).Besides,our strategy has excellent universality confirmed by its effectiveness in improving the ZT of Bi_(2)Te_(2.7)Se_(0.3),therefore demonstrating great potential for developing low-cost and high-performance thermoelectric materials.
基金financially funded by the Regional Innovation and Development Joint Fund,National Natural Science Foundation of China(No.U20A20249)National Key Research Program of China(No.2016YFB0901500)。
文摘As a promising cathode material,Na_(3)V_(2)(PO_(4))_(2)F_(3)(NVPF)has attracted wide attention for sodium-ion batteries(SIBs)because of its high operating voltage and high structural stability.However,the low intrinsic electronic conductivity and insufficient Na ion mobility of NVPF limit its development.Herein,K-doping NVPF is prepared through a facile ball-milling combined calcination method.The effects of K-doping on the crystal structure,kinetic properties and electrochemical performance are investigated.The results demonstrate that the Na_(2.90)K_(0.10)V_(2)(PO_(4))_(3)F_(3)(K0.10-NVPF)exhibits a high capacity(120.8 mAh g^(-1) at 0.1 C),high rate capability(66 mAh g^(-1) at 30 C)and excellent cycling performance(a capacity retention of 97.5%at 1 C over 500 cycles).Also,the occupation site of K ions in the lattice,electronic band structure and Na-ion transport kinetic property in K-doped NVPF are investigated by density functional theory(DFT)calculations,which reveals that the K-doped NVPF exhibits improved electronic and ionic conductivities,and located K^(+) ions in the lattice to contribute to high reversible capacity,rate capability and cycling stability.Therefore,the K-doped NVPF serves as a promising cathode material for high-energy and high-power SIBs.
基金the support of this research by Natural Science Foundation of Shanghai (19ZR1479400)the State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University (KF1818)the State Key Laboratory of Advanced Technology for Materials Synthesis and Processing (Wuhan University of Technology)。
文摘Among various earth-abundant and noble metal-free catalysts for oxygen reduction reaction(ORR),manganese-based oxides are promising candidates owing to the rich variety of manganese valence.Herein,an extremely facile method for the synthesis of cubic and orthorhombic phase coexisting Mn(Ⅱ)O electrocatalyst as an efficient ORR catalyst was explored.The obtained MnO electrocatalyst with oxygen vacancies shows a significantly elevated ORR catalytic activity with a half-wave potential(E1/2) of as high as 0.895 V,in comparison with that of commercial Pt/C(E1/2=0.877 V).More impressively,the MnO electrocatalyst exhibits a marked activity enhancement after test under a constant applied potential for 1000 s thanks to the in situ generation and stable presence of high-valence manganese species(Mn^3+ and Mn^4+) during the electrochemical process,initiating a synergetic catalytic effect with oxygen vacancies,which is proved to largely accelerate the adsorption and reduction of O_2 molecules favoring the ORR activity elevation.Such an excellent ORR catalytic performance of this MnO electrocatalyst is applied in Zn-air battery,which shows an extra-high peak power density of 63.2 mW cm^-2 in comparison with that(47.4 m W cm^-2) of commercial Pt/C under identical test conditions.
基金National Natural Science Foundation of China(52202327)Science and Technology Commission of Shanghai Municipality(22ZR1471300)+2 种基金National Science Foundation of China(Grant 51972326)Youth Innovation Promotion Association CAS,Foundation Strengthening ProjectProgram of Shanghai Academic Research Leader(Grant 22XD1424300).
文摘Na-ion O3-type layered oxides are prospective cathodes for Na-ion batteries due to high energy density and low-cost.Nevertheless,such cathodes usually suffer from phase transitions,sluggish kinetics and air instability,making it difficult to achieve high performance solid-state sodium-ion batteries.Herein,the high-entropy design and Li doping strategy alleviate lattice stress and enhance ionic conductivity,achieving high-rate performance,air stability and electrochemically thermal stability for Na_(0.95)Li_(0.06)Ni_(0.25)Cu_(0.05)Fe_(0.15)Mn_(0.49)O_(2).This cathode delivers a high reversible capacity(141 mAh g^(−1)at 0.2C),excellent rate capability(111 mAh g^(−1)at 8C,85 mAh g^(−1)even at 20C),and long-term stability(over 85%capacity retention after 1000 cycles),which is attributed to a rapid and reversible O3–P3 phase transition in regions of low voltage and suppresses phase transition.Moreover,the compound remains unchanged over seven days and keeps thermal stability until 279℃.Remarkably,the polymer solid-state sodium battery assembled by this cathode provides a capacity of 92 mAh g^(−1)at 5C and keeps retention of 96%after 400 cycles.This strategy inspires more rational designs and could be applied to a series of O3 cathodes to improve the performance of solid-state Na-ion batteries.
基金Project supported by the National Natural Science Foundation of China Youth Project (51702317)the Youth Project of the Natural Science Foundation of Jiangxi Provincial Science and Technology (20212BAB214019)the Program of Qingjiang Excellent Young Talents of Jiangxi University of Science and Technology (JXUSTQJYX2020004)。
文摘Lead-free ferroelectric ceramics,0.67Bi_(1-x)Eu_(x)FeO_(3)-0.33BaTiO_(3)(BF-BT-xEu,x=0-0.02),were prepared via a solid-state reaction,The effect of Eu^(3+) doping on the microstructure,dielectric properties,ferroelectric properties,and electric-field-induced strain was investigated.The X-ray diffraction(XRD) results indicate the presence of a mixed phase of tetragonal and rhombohedral at the morphotropic phase boundary(MPB).Doping with an appropriate amount of Eu^(3+) reduces the Fe^(3+) content and decreases the leakage current in the binary system.A converse piezoelectric coefficient(d_(33)*) of 392 pm/V is obtained at BF-BT-0.003Eu under an electric field of 60 kV/cm at room temperature,which has a Curie temperature(T_(C)) of 414℃,The unipolar strain and d_(33)* of BF-BT-0.003Eu ceramics increase to 0.438%and 730 pm/V at 125℃ The field-induced strain response of the BF-BT-0.003Eu ceramics is greater than that of 0.67BF-0.33BT,mainly due to its optimal grain size,reduction of leakage current,and coexistence of ferroelectric-relaxation phases,BF-BT-0.003Eu ceramic is a lead-free candidate for high-temperature actuator applications.
基金National Key R&D Program of China(2022YFB3707700)Shanghai Science and Technology Innovation Action Plan(21511104800)+3 种基金National Natural Science Foundation of China(52172111)National Science and Technology Major Project(2017-IV-0005-0042)Key Research Program of the Chinese Academy of Sciences(ZDRW-CN-2021-2-2)Science Center for Gas Turbine Project(P2022-B-IV-001-001)。
文摘ZrB_(2)-based ceramics typically necessitate high temperature and pressure for sintering,whereas ZrB_(2)-SiC ceramics can be fabricated at 1500℃using the process of reactive melt infiltration with Si.In comparison to the conventional preparation method,reactive synthesis allows for the more facile production of ultra-high temperature ceramics with fine particle size and homogeneous composition.In this work,ZrSi_(2),B4C,and C were used as raw materials to prepare ZrB_(2)-SiC via combination of tape casting and reactive melt infiltration herein referred to as ZBC ceramics.Control sample of ZrB_(2)-SiC was also prepared using ZrB_(2)and SiC as raw materials through an identical process designated as ZS ceramics.Microscopic analysis of both ceramic groups revealed smaller and more uniformly distributed particles of the ZrB_(2)phase in ZBC ceramics compared to the larger particles in ZS ceramics.Both sets of ceramics underwent cyclic oxidation testing in the air at 1600℃for a cumulative duration of 5 cycles,each cycle lasting 2 h.Analysis of the oxidation behavior showed that both ZBC ceramics and ZS ceramics developed a glassy SiO_(2)-ZrO_(2)oxide layer on their surfaces during the oxidation.This layer severed as a barrier against oxygen.In ZBC ceramics,ZrO_(2)is finely distributed in SiO_(2),whereas in ZS ceramics,larger ZrO_(2)particles coexist with glassy SiO_(2).The surface oxide layer of ZBC ceramics maintains a dense structure because the well-dispersed ZrO_(2)increases the viscosity of glassy SiO_(2),preventing its crystallization during the cooling.Conversely,some SiO_(2)in the oxide layer of ZS ceramics may crystallize and form a eutectic with ZrO_(2),leading to the formation of ZrSiO_(4).This leads to cracking of the oxide layer due to differences in thermal expansion coefficients,weakening its barrier effect.An analysis of the oxidation resistance shows that ZBC ceramics exhibit less increase in oxide layer thickness and mass compared to ZS ceramics,suggesting superior oxidation resistance of ZBC ceramics.
基金National Key Research and Development Program of China (2023YFB3813000)National Natural Science Foundation of China (52272256)State Key Laboratory of Advanced Technology for Materials Synthesis and Processing (Wuhan University of Technology)(2022-KF-77)。
文摘Bioceramics have attracted extensive attention for bone defect repair due to their excellent bioactivity and degradability.However,challenges remain in matching the rate between bioceramic degradation and new bone formation,necessitating a deeper understanding of their degradation properties.In this study,density functional theory(DFT)calculations was employed to explore the structural and electronic characteristics of silicate bioceramics.These findings reveal a linear correlation between the maximum isosurface value of the valence band maximum(VBM_(Fmax))and the degradability of silicate bioceramics.This correlation was subsequently validated through degradation experiments.Furthermore,the investigation on phosphate bioceramics demonstrates the potential of this descriptor in predicting the degradability of a broader range of bioceramics.This discovery offers valuable insights into the degradation mechanism of bioceramics and holds promise for accelerating the design and development of bioceramics with controllable degradation.
基金National Key R&D Program of China(2022YFB3807700)National Natural Science Foundation of China(22133005,22103093)+4 种基金Science and Technology Commission of Shanghai Municipality(21ZR1472900,22ZR1471600,23ZR1472600)Youth Innovation Promotion Association CAS(2022251)Shanghai Super Post-Doctor Incentive Program(2022665)China Postdoctoral Science Foundation(2023M733621)Shanghai Explorer Program(Batch I)(23TS1401500)。
文摘Sodium-ion batteries are economical and environmentally sustainable energy storage batteries.Among them,β-NaMnO_(2),a promising sodium-ion cathode material,is a manganese-based oxide with a corrugated laminar structure,which has attracted significant attention due to its structural robustness and relatively high specific capacity.However,it has short cycle life and poor rate capability.To address these issues,Ti atoms,known for enhancing structural stability,and Cu atoms,which facilitate desodiation,were doped intoβ-NaMnO_(2) by first-principles calculation and crystal orbital Hamilton population(COHP)analysis.β-NaMn_(0.8)Ti_(0.1)Cu_(0.1)O_(2) exhibits a notable increase in reversible specific capacity and remarkable rate properties.Operating at a current density of 0.2C(1C=219 mA·g^(–1))and within a voltage range of 1.8–4.0 V,the modified material delivers an initial discharge capacity of 132 mAh·g^(–1).After charge/discharge testing at current densities of 0.2C,0.5C,1C,3C,and 0.2C,the material still maintains a capacity of 110 mA h·g^(–1).The doping of Ti atoms slows down the changes in the crystal structure,resulting in only minimal variation in the lattice constant c/a during the desodiation process.Mn and Cu engage in reversible redox reactions at voltages below 3.0 V and around 3.5 V,respectively.The extended plateau observed in the discharge curve below 3.0 V signifies that Mn significantly contributes to the overall battery capacity.This study provides insights into modifyingβ-NaMnO_(2) as a cathode material,offering experimental evidence and theoretical guidance for enhancing battery performance in Na-ion batteries.
基金Funded by the National Key Research and Development Program of China(No.2023YFB3812200)the National Key Basic Research Program of China(973 Program)(No.2015CB654601)。
文摘Under illumination by 405,520 and 655 nm monochromatic visible light(light intensity of 30 kW/m^(2)),large photostriction(ΔL/L)of 0.19%,0.13%and 0.26%for 67BiFeO_(3)-33BaTiO_(3)(67BF-33BT)lead-free ferroelectric ceramics are obtained,respectively.By studying the ferroelectric and photoelectric properties in conjunction with in situ Raman spectroscopy,it is found that the photostrictive effect of 67BF-33BT is not caused by the electrical strain induced by abnormal photovoltaic voltage,but related to the optical induced oxygen octahedral distortion.The 67BF-33BT lead-free ferroelectric material with excellent photostrictive response in the visible light region is expected to play an important role in the field of optical drive electromechanical devices.
