Among their several unique properties,the high electrical conductivity and mechanical strength of carbon nanofibers make them suitable for applications such as catalyst support for fuel cells,flexible electrode materi...Among their several unique properties,the high electrical conductivity and mechanical strength of carbon nanofibers make them suitable for applications such as catalyst support for fuel cells,flexible electrode materials for secondary batteries,and sensors.However,their performance requires improvement for practical applications.Several methods have been pursued to achieve this,such as growing carbon nanotubes from carbon nanofibers;however,the transition metal catalyst used to grow carbon nanotubes causes problems,including side reactions.This study attempts to address this issue by growing numerous branched carbon nanofibers from the main carbon nanofibers using alkali metals.Excellent electrical conductivity is achieved by growing densely branched carbon nanofibers.Consequently,a current collector,binder,and conductive material-free anode material is realized,exhibiting excellent electrochemical performance compared with existing carbon nanofibers.The proposed method is expected to be a powerful tool for secondary batteries and have broad applicability to various fields.展开更多
Electrophoretic deposition in conjunction with electrochemical reduction was used to make flexible free-standing graphene-like films. Firstly, graphene oxide （GO） film was deposited on graphite substrate by electrop...Electrophoretic deposition in conjunction with electrochemical reduction was used to make flexible free-standing graphene-like films. Firstly, graphene oxide （GO） film was deposited on graphite substrate by electrophoretic deposition method, and then reduced by subsequent electrochemical reduction of GO to obtain reduced GO （ERGO） film with high electrochemical performance. The morphology, structure and electrochemical performance of the prepared graphene-like film were confirmed by SEM, XRD and FT-IR. These unique materials were found to provide high specific capacitance and good cycling stability. The high specific capacitance of 254 F/g was obtained from cyclic voltammetry measurement at a scan rate of 10 mV/s. When the current density increased to 83.3 A/g, the specific capacitance values still remained 132 F/g. Meanwhile, the high powder density of 39.1 kW/kg was measured at energy density of 11.8 W-h/kg in 1 mol/L H2SO4 solution. Furthermore, at a constant scan rate of 50 mV/s, 97.02% of its capacitance was retained for 1000 cycles. These promising results were attributed to the unique assembly structure of graphene film and low contact resistance, which indicated their potential application to electrochemical capacitors.展开更多
Dramatic capacity fading and poor rate performance are two main obstacles that severely hamper the widespread application of the Si anode owing to its large volume variation during cycling and low intrinsic electrical...Dramatic capacity fading and poor rate performance are two main obstacles that severely hamper the widespread application of the Si anode owing to its large volume variation during cycling and low intrinsic electrical conductivity.To mitigate these issues,free-standing N-doped porous carbon nanofibers sheathed pumpkin-like Si/C composites(Si/C-ZIF-8/CNFs)are designed and synthesized by electrospinning and carbonization methods,which present greatly enhanced electrochemical properties for lithium-ion battery anodes.This particular structure alleviates the volume variation,promotes the formation of stable solid electrolyte interphase(SEI)film,and improves the electrical conductivity.As a result,the as-obtained free-standing Si/C-ZIF-8/CNFs electrode delivers a high reversible capacity of 945.5 mAh g^(-1) at 0.2 A g^(-1) with a capacity retention of 64% for 150 cycles,and exhibits a reversible capacity of 538.6 mA h g^(-1) at 0.5 A g^(-1) over 500 cycles.Moreover,the full cell composed of a freestanding Si/C-ZIF-8/CNFs anode and commercial LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)(NCM)cathode shows a capacity of 63.4 mA h g^(-1) after 100 cycles at 0.2 C,which corresponds to a capacity retention of 60%.This rational design could provide a new path for the development of high-performance Si-based anodes.展开更多
As a promising energy-storage device,the hybrid lithium-ion capacitor coupling with both a large energy density battery-type anode and a high power density capacitor-type cathode is attracting great attention.For the ...As a promising energy-storage device,the hybrid lithium-ion capacitor coupling with both a large energy density battery-type anode and a high power density capacitor-type cathode is attracting great attention.For the sake of improving the energy density of hybrid lithium-ion capacitor,the free-standing anodes with good electrochemical performance are essential.Herein,we design an effective electrospinning strategy to prepare free-standing MnS/Co4S3/Ni3S2/Ni/C-nanofibers(TMSs/Ni/C-NFs)film and firstly use it as a binder-free anode for hybrid lithium-ion capacitor.We find that the carbon nanofibers can availably prevent MnS/Co4S3/Ni3S2/Ni nanoparticles from aggregation as well as significantly improve the electrochemical performance.Therefore,the binder-free TMSs/Ni/C-NFs membrane displays an ultrahigh reversible capacity of 1246.9 m Ah g-1at 100 m A g-1,excellent rate capability(398 mAh g-1 at2000 mA g-1),and long-term cyclic endurance.Besides,we further assemble the hybrid lithium-ion capacitor,which exhibits a high energy density of 182.0 Wh kg-1at 121.1 W kg-1(19.0 Wh kg-1 at 3512.5 W kg-1)and remarkable cycle life.展开更多
Electrochemical reduction of molecular O2 to hydrogen peroxide(H2O2)offers a promising solution for water purification and environmental remediation.Here,we design a hierarchical free-standing single-Co-atom(with Co-N...Electrochemical reduction of molecular O2 to hydrogen peroxide(H2O2)offers a promising solution for water purification and environmental remediation.Here,we design a hierarchical free-standing single-Co-atom(with Co-N4 coordination)electrode for oxygen reduction reaction(ORR)via a two-electron pathway to make H2O2 in acidic media.The current density of the single-Co-atom electrode reached 51 mA/cm2 at 0.1 V vs reversible hydrogen electrode,lasting for more than 10 hours of continuous operation with H2O2 selectivity greater than 80%.Toward practical application,the single-Co-atom electrode was directly used to assemble an electrochemical cell to produce H2O2 at a rate of 676 mol/kgcat/h with a cell voltage of about 1.6 V.展开更多
Wearable and portable mobile phones play a critical role in the market, and one of the key technologies is the flexible electrode with high specific capacity and excellent mechanical flexibility. Herein, a wire-in-wir...Wearable and portable mobile phones play a critical role in the market, and one of the key technologies is the flexible electrode with high specific capacity and excellent mechanical flexibility. Herein, a wire-in-wire TiO_(2)/C nanofibers (TiO_(2) ww/CN) film is synthesized via electrospinning with selenium as a structural inducer. The interconnected carbon network and unique wire- in-wire nanostructure cannot only improve electronic conductivity and induce effective charge transports, but also bring a superior mechanic flexibility. Ulti-mately, TiO_(2) ww/CN film shows outstanding electrochemical performance as free-standing electrodes in Li/K ion batteries. It shows a discharge capacity as high as 303 mAh g^(−1) at 5 A g^(−1) after 6000 cycles in Li half-cells, and the unique structure is well-reserved after long-term cycling. Moreover, even TiO_(2) has a large diffusion barrier of K^(+), TiO_(2) ww/CN film demonstrates excellent perfor-mance (259 mAh g^(−1) at 0.05 A g^(−1) after 1000 cycles) in K half-cells owing to extraordinary pseudocapacitive contribution. The Li/K full cells consisted of TiO_(2) ww/CN film anode and LiFePO_(4)/Perylene-3,4,9,10-tetracarboxylic dianhydride cathode possess outstanding cycling stability and demonstrate practical application from lighting at least 19 LEDs. It is, therefore, expected that this material will find broad applications in portable and wearable Li/K-ion batteries.展开更多
The defect chemistry is successfully modulated on free-standing and binder-free carbon cathodes for highly efficient Li-S redox reactions.Such rationally regulated defect engineering realizes the synchronization of io...The defect chemistry is successfully modulated on free-standing and binder-free carbon cathodes for highly efficient Li-S redox reactions.Such rationally regulated defect engineering realizes the synchronization of ion/electron-conductive and defect-rich networks on the threedimension carbon cathode,leading to its tunable activity for both relieving the shuttle phenomenon and accelerating the sulfur redox reaction kinetics.As expected,the defective carbon cathode harvests a high rate capacity of 1217.8 mAh g^(-1)at 0.2 C and a superior capacity retention of61.7%at 2 C after 500 cycles.Even under the sulfur mass loading of 11.1 mg cm^(-2),the defective cathode still holds a remarkable areal capacity of 8.5 mAh cm^(-2).展开更多
Electrocatalytic nitrogen reduction reaction is a carbon-free and energy-saving strategy for efficient synthesis of ammonia under ambient conditions.Here,we report the synthesis of nanosized Bi2O3 particles grown on f...Electrocatalytic nitrogen reduction reaction is a carbon-free and energy-saving strategy for efficient synthesis of ammonia under ambient conditions.Here,we report the synthesis of nanosized Bi2O3 particles grown on functionalized exfoliated graphene(Bi2O3/FEG)via a facile electrochemical deposition method.The obtained free-standing Bi2O3/FEG achieves a high Faradaic efficiency of 11.2%and a large NH3 yield of 4.21±0.14μgNH3 h^-1 cm^-2 at-0.5 V versus reversible hydrogen electrode in 0.1 M Na2SO4,better than that in the strong acidic and basic media.Benefiting from its strong interaction of Bi 6p band with the N2p orbitals,binder-free characteristic,and facile electron transfer,Bi2O3/FEG achieves superior catalytic performance and excellent long-term stability as compared with most of the previous reported catalysts.This study is significant to design low-cost,high-efficient Bi-based electrocatalysts for electrochemical ammonia synthesis.展开更多
The keen interest in fuel cells and metal-air batteries stimulates a great deal of research on the development of a cost-efficient and high-performance catalyst as an alternative to traditional Pt to boost the sluggis...The keen interest in fuel cells and metal-air batteries stimulates a great deal of research on the development of a cost-efficient and high-performance catalyst as an alternative to traditional Pt to boost the sluggish oxygen reduction reaction(ORR)at the cathode.Herein,we report a facile and scalable strategy for the large-scale preparation of a free-standing and flexible porous atomically dispersed Fe-N-doped carbon microtube(FeSAC/PCMT)sponge.Benefiting from its unique structure that greatly facilitates the catalytic kinetics,mass transport,and electron transfer,our FeSAC/PCMT electrode exhibits excellent performance with an ORR potential of 0.942 V at^(-3) mA cm^(-2).When the FeSAC/PCMT sponge was directly used as an oxygen electrode for liquid-state and flexible solid-state zinc-air batteries,high peak power densities of 183.1 and 58.0 mW cm^(-2) were respectively achieved,better than its powdery counterpart and commercial Pt/C catalyst.Experimental and theoretical investigation results demonstrate that such ultrahigh ORR performance can be attributed to atomically dispersed Fe-N_(5) species in FeSAC/PCMT.This study presents a cost-effective and scalable strategy for the fabrication of highly efficient and flexible oxygen electrodes,provides a significant new insight into the catalytic mechanisms,and helps to realize significant advances in energy devices.展开更多
Highly efficient electrocatalysts towards hydrogen evolution reaction(HER) with large current density at all-pH values are critical for the sustainable hydrogen production. Herein, we report a free-standing HER electr...Highly efficient electrocatalysts towards hydrogen evolution reaction(HER) with large current density at all-pH values are critical for the sustainable hydrogen production. Herein, we report a free-standing HER electrode, phosphorous-doped molybdenum nitride nanoparticles embedded in 3-dimentional carbon nanosheet matrix(P-Mo2N-CNS) fabricated via one-step carbonization and in-situ formation. The asprepared catalyst shows free-standing architecture with interconnected porous microstructure. P-doped Mo2N nanoparticles with an average diameter of 4.4 nm are well embedded in the 3-dimentional vertical carbon nanosheets matrix. Remarkable electrocatalytic HER performance is observed in alkaline, neutral and acidic media at large current densities. The overpotential of P-Mo2N-CNS to drive a current density of 100 mA cm-2 in 0.5 M H2SO4 and 1.0 M PBS is only 181 and 221 mV, respectively. In particular, the current density reaches up to 1000 mA cm-2 at a low overpotential of 256 mV in 1.0 M KOH, much better than that of the commercial Pt/C catalyst. Density functional theory calculations suggest the optimized H sorption kinetics on Mo2N after P doping, elucidating the superior activity.展开更多
Vanadium pentoxide （V2O5.nH2O） nanoribbons are synthesized via a hydrothermal process. These ribbons are 20nm thick, 200nm to 1 μm wide and several tens of micrometers long. Free-standing binder-free films are prep...Vanadium pentoxide （V2O5.nH2O） nanoribbons are synthesized via a hydrothermal process. These ribbons are 20nm thick, 200nm to 1 μm wide and several tens of micrometers long. Free-standing binder-free films are prepared by using these nanoribbons with multi-walled carbon nanotubes （MWCNTs） and used as the cathode for rechargeable sodium batteries. The large interlayer space between the V20s5 bilayers can enhance the kinetics of sodium ion intercalation/deintercalation. In addition, the intertwining network of the V2O5. 0.34H2O film provides efficient electron conduction pathways and shortens diffusion distances of sodium ion. The electrochemical tests prove that the free- standing V2O5. 0.34H2O film cathode delivers high reversible specific capacities （190 mAh/g） and good cycling stabilities （170 mAh/g after 150 cycles） in the voltage range between 1.5V and 3.5V.展开更多
Most efficient visible-light-responsive photocatalysts are in the form of powder,leading to the tedious separation from the reaction media.Herein,we developed a versatile method for the general synthesis of free-stand...Most efficient visible-light-responsive photocatalysts are in the form of powder,leading to the tedious separation from the reaction media.Herein,we developed a versatile method for the general synthesis of free-standing polyacrylonitrile(PAN)/Ag/AgX(X=Br,I)nanofiber mats,where fibrous PAN/Ag precursor was firstly prepared via an electroless plating strategy,followed by a direct elemental halogenation with Br2/H2O or I2/ethanol solution.The as-obtained PAN/Ag/AgX nanofiber mats exhibit exceptional photocatalytic activity toward degradation of organic pollutants.Furthermore,the flexibility enables it to be easily recovered after the reaction was completed.This work provides new insights into the fabrication of membrane-based photocatalysts on a large scale.展开更多
The development of sulfur cathodes with high areal capacity and high energy density is crucial for the practical application of lithium-sulfur batteries(LSBs).LSBs can be built by employing(ultra)high-loading sulfur c...The development of sulfur cathodes with high areal capacity and high energy density is crucial for the practical application of lithium-sulfur batteries(LSBs).LSBs can be built by employing(ultra)high-loading sulfur cathodes,which have rarely been realized due to massive passivation and shuttling.Herein,microspheres of a carbon-carbon nitride composite(C@CN)with large mesopores are fabricated via molecular cooperative assembly.Using the C@CN-based electrodes,the effects of the large mesopores and N-functional groups on the electrochemical behavior of sulfur in LSB cells are thoroughly investigated under ultrahigh sulfur-loading conditions(>15 mgS cm^(-2)).Furthermore,for high-energy-density LSBs,the C@CN powders are pelletized into a thick free-standing electrode(thickness:500^m;diameter:11 mm)via a simple briquette process;here,the total amount of energy stored by the LSB cells is 39 mWh,corresponding to a volumetric energy density of 440 Wh L-1 with an areal capacity of 24.9 and 17.5 mAh cm^(-2) at 0.47 and 4.7 mA cm^(-2),respectively(at 24mgS cm^(-2)).These results have significantly surpassed most recent records due to the synergy among the large mesopores,(poly)sulfide-philic surfaces,and thick electrodes.The developed strategy with its potential for scale-up successfully fills the gap between laboratory-scale cells and practical cells without sacrificing the high areal capacity and high energy density,providing a solid foundation for the development of practical LSBs.展开更多
Two shapes of Co_3O_4 nanoarrays(i.e., nanosheets, nanowires) with different densities of exposed catalytic active sites were synthesized through a facile hydrothermal method on Ni foam substrates and tested as the bi...Two shapes of Co_3O_4 nanoarrays(i.e., nanosheets, nanowires) with different densities of exposed catalytic active sites were synthesized through a facile hydrothermal method on Ni foam substrates and tested as the binder/carbon free and free-standing cathodes for Li–O_2 batteries. Particularly, the single crystalline feature of Co_3O_4 nanosheets with a predominant high reactivity {112} exposed crystal plane and hierarchical porous nanostructure displayed better catalytic performance for both oxygen reduction reaction(during discharge process) and oxygen evolution reaction(during charge process). Li–O_2 battery with Co_3O_4 nanosheets cathode exhibited a higher discharge specific capacity(965 m Ah g^(-1)), lower discharge/charge over-potential and better cycling performance over 63 cycles at 100 mA g^(-1) with the specific capacity limited at 300 mAh g^(-1). The superior catalytic performance of Co_3O_4 nanosheets cathode is ascribed to the enlarging specific area and increasing the exposed Co^(3+) catalytic active sites within predominant {112} crystal plane which plays the key role in determining the adsorption energy for the reactants, enabling high round-trip efficiency and cyclic life.展开更多
Flexible electronic devices have attracted much attention due to their practical and commercial value. Integration of thin films with soft substrate is an effective way to fabricate flexible electronic devices. Ga_2O_...Flexible electronic devices have attracted much attention due to their practical and commercial value. Integration of thin films with soft substrate is an effective way to fabricate flexible electronic devices. Ga_2O_3 thin films deposited directly on soft substrates would be amorphous mostly. However, the thickness of the thin film obtained by mechanical exfoliation method is difficult to control and the edge of the film is fragile and easy to be damaged. In this work, we fabricated free-standing Ga_2O_3 thin films using the water-soluble perovskite Sr_3Al_2O_6 as a sacrificial buffer layer. The obtained Ga_2O_3 thin films were polycrystalline. The thickness and dimension of the films were controllable. A flexible Ga_2O_3solar-blind UV photodetector was fabricated by transferring the free-standing Ga_2O_3 film on a flexible polyethylene terephthalate substrate. The results displayed that the photoelectric performances of the flexible Ga_2O_3 photodetector were not sensitive to bending of the device. The free-standing Ga_2O_3 thin films synthesized through the method described here can be transferred to any substrates or integrated with other thin films to fabricate electronic devices.展开更多
Recently,with the rapid development of chemical vapor deposition(CVD)technology,large area free-standing CVD diamond films have been produced successfully.However,the coarse grain size on the surface and the non-unifo...Recently,with the rapid development of chemical vapor deposition(CVD)technology,large area free-standing CVD diamond films have been produced successfully.However,the coarse grain size on the surface and the non-uniform thickness of unprocessed CVD diamond films make it difficult to meet the application requirement.The current study evaluates several existing polishing methods for CVD diamond films,including mechanical polishing,chemical mechanical polishing and tribochemical polishing technology.展开更多
Similar to free-standing pile groups, piled raft foundations are conventionally designed in which the piles carry the total load of structure and the raft bearing capacity is not taken into account. Numerous studies i...Similar to free-standing pile groups, piled raft foundations are conventionally designed in which the piles carry the total load of structure and the raft bearing capacity is not taken into account. Numerous studies indicated that this method is too conservative. Only when the pile cap is elevated from the ground level,the raft bearing contribution can be neglected. In a piled raft foundation, pileesoileraft interaction is complicated. Although several numerical studies have been carried out to analyze the behaviors of piled raft foundations, very few experimental studies are reported in the literature. The available laboratory studies mainly focused on steel piles. The present study aims to compare the behaviors of piled raft foundations with free-standing pile groups in sand, using laboratory physical models. Cast-in-place concrete piles and concrete raft are used for the tests. The tests are conducted on single pile, single pile in pile group, unpiled raft, free-standing pile group and piled raft foundation. We examine the effects of the number of piles, the pile installation method and the interaction between different components of foundation. The results indicate that the ultimate bearing capacity of the piled raft foundation is considerably higher than that of the free-standing pile group with the same number of piles. With installation of the single pile in the group, the pile bearing capacity and stiffness increase. Installation of the piles beneath the raft decreases the bearing capacity of the raft. When the raft bearing capacity is not included in the design process, the allowable bearing capacity of the piled raft is underestimated by more than 200%. This deviation intensifies with increasing spacing of the piles.展开更多
The ever-increasing demands for advanced lithium-ion batteries with high energy density have greatly stimulated the pursuit of thick electrodes with high active material loading.However,it is not feasible to prepare t...The ever-increasing demands for advanced lithium-ion batteries with high energy density have greatly stimulated the pursuit of thick electrodes with high active material loading.However,it is not feasible to prepare thick electrodes with traditional coating methods due to mechanical instability.Herein,using single-wall carbon nanotubes(SWCNT)as conductive carbon and binder,free-standing LiMn_(2)O_(4) thick electrodes(F-LMO)with ultrahigh-mass loading up to~190 mg cm^(-2)were prepared by vacuum filtration combined with freeze-drying.The thick electrodes with~30 mg cm^(-2)mass loading achieved a high specific capacity of 106.7 mAh g^(-1)with a good capacity retention of 94%over 50 cycles at 0.5 C,which was superior to the traditional coating electrodes(~20 mg cm^(-2))of 99.3 mAh g^(-1)with 95%because of the enhanced electronic conductivity originated from SWCNT.In addition,the high active material ratio of 97.5 wt%,near-theoretical reversible capacity,and high mass loading gave ultrathick F-LMO electrodes(600μm)of~190 mg cm^(-2)with a remarkable areal capacity of 20 mAh cm^(-2).Moreover,the concentration polarization that occurred in the thick F-LMO electrodes under high current density was discussed via electrochemical stimulation.展开更多
Rational construction of flexible free-standing electrocatalysts featuring long-lasting durability,high efficiency,and wide temperature tolerance under harsh practical operations are fundamentally significant for comm...Rational construction of flexible free-standing electrocatalysts featuring long-lasting durability,high efficiency,and wide temperature tolerance under harsh practical operations are fundamentally significant for commercial zinc-air batteries.Here,3D flexible free-standing bifunctional membrane electrocatalysts composed of covalently cross-linked supramolecular polymer networks with nitrogen-deficient carbon nitride nanotubes are fabricated(referred to as PEMAC@NDCN)by a facile self-templated approach.PEMAC@NDCN demonstrates the lowest reversible oxygen bifunctional activity of 0.61 V with exceptional long-lasting durability,which outperforms those of commercial Pt/C and RuO_(2).Theoretical calculations and control experi-ments reveal the boosted electron transfer,electrolyte mass/ion transports,and abundant active surface site preferences.Moreover,the constructed alkaline Zn-air battery with PEMAC@NDCN air-cathode reveals superb power density,capacity,and discharge-charge cycling stability(over 2160 cycles)compared to the reference Pt/C+RuO_(2).Solid-state Zn-air batteries enable a high power density of 211 mW cm^(−2),energy density of 1056 Wh kg^(−1),stable charge-discharge cycling of 2580 cycles for 50 mA cm^(−2),and wide temperature tolerance from−40 to 70℃with retention of 86%capacity compared to room-temperature counterparts,illustrating prospects over harsh operations.展开更多
Li metal with high-energy density is considered as the most promising anode for the next-generation rechargeable Li metal batteries;however,the growth of Li dendrites seriously hinders its practical application.Herein...Li metal with high-energy density is considered as the most promising anode for the next-generation rechargeable Li metal batteries;however,the growth of Li dendrites seriously hinders its practical application.Herein,3D free-standing carbon nanofibers modified by lithiophilic metal particles(CNF/Me,Me=Sn,Fe,Co)are obtained in situ by the electrospinning method.Benefiting from the lithophilicity,the CNF/Me composite may effectively prevent the formation of Li dendrites in the Li metal batteries.The optimized CNF/Sn–Li composite electrode exhibits a stable cycle life of over 2350 h during Li plating/stripping.When matched with typical commercial LiFePO_(4)(LFP)cathode,the LFP//CNF/Sn–Li full cell presents a high initial discharge specific capacity of 139 mAh g^(−1)at 1 C,which remains at 146 mAh g^(−1)after 400 cycles.When another state-of-the-art commercial LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM(811))cathode is used,the assembled NCM//CNF/Sn–Li full cell shows a large initial specific discharge capacity of 206 mAh g^(−1)at substantially enhanced 10 C,which keeps at the good capacity of 99 mAh g^(−1)after 300 cycles.These results are greatly superior to the counterparts with Li as the anodes,indicating the great potential for practical utilization of the advanced CNF/Sn–Li electrode.展开更多
基金supported by the Ministry of Education of the Republic of Korea and the National Research Foundation of Korea(NRF2023R1A2C2004191)supported by Korea Basic Science Institute(National research Facilities and Equipment Center)grant funded by Ministry of Education(grant No.2022R1A6C101B738).
文摘Among their several unique properties,the high electrical conductivity and mechanical strength of carbon nanofibers make them suitable for applications such as catalyst support for fuel cells,flexible electrode materials for secondary batteries,and sensors.However,their performance requires improvement for practical applications.Several methods have been pursued to achieve this,such as growing carbon nanotubes from carbon nanofibers;however,the transition metal catalyst used to grow carbon nanotubes causes problems,including side reactions.This study attempts to address this issue by growing numerous branched carbon nanofibers from the main carbon nanofibers using alkali metals.Excellent electrical conductivity is achieved by growing densely branched carbon nanofibers.Consequently,a current collector,binder,and conductive material-free anode material is realized,exhibiting excellent electrochemical performance compared with existing carbon nanofibers.The proposed method is expected to be a powerful tool for secondary batteries and have broad applicability to various fields.
基金Projects(21361020,21061012)supported by the National Natural Science Foundation of ChinaProject(NZ12156)supported by the Natural Science Foundation of Ningxia,ChinaProject(N-09-13)supported by Project of State Key Laboratory of Catalysis,Dalian Institute of Chemical Physics of the Chinese Academy of Sciences
文摘Electrophoretic deposition in conjunction with electrochemical reduction was used to make flexible free-standing graphene-like films. Firstly, graphene oxide （GO） film was deposited on graphite substrate by electrophoretic deposition method, and then reduced by subsequent electrochemical reduction of GO to obtain reduced GO （ERGO） film with high electrochemical performance. The morphology, structure and electrochemical performance of the prepared graphene-like film were confirmed by SEM, XRD and FT-IR. These unique materials were found to provide high specific capacitance and good cycling stability. The high specific capacitance of 254 F/g was obtained from cyclic voltammetry measurement at a scan rate of 10 mV/s. When the current density increased to 83.3 A/g, the specific capacitance values still remained 132 F/g. Meanwhile, the high powder density of 39.1 kW/kg was measured at energy density of 11.8 W-h/kg in 1 mol/L H2SO4 solution. Furthermore, at a constant scan rate of 50 mV/s, 97.02% of its capacitance was retained for 1000 cycles. These promising results were attributed to the unique assembly structure of graphene film and low contact resistance, which indicated their potential application to electrochemical capacitors.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.21965034,21703185,U1903217,51901013,and 21666037)the Xinjiang Autonomous Region Major Projects(2017A02004)+4 种基金the Leading Project Foundation of Science Department of Fujian Province(Grant No.2018H0034)the Resource Sharing Platform Construction Project of Xinjiang Province(PT1909)the Nature Science Foundation of Xinjiang Province(2017D01C074)the Opening Project of National Joint Engineering Research Center for Abrasion Control and Molding of Metal Materials,Henan University of Science and Technology(No.HKDNM201906)the Young Scholar Science Foundation of Xinjiang Educational Institutions(XJEDU2016S030)。
文摘Dramatic capacity fading and poor rate performance are two main obstacles that severely hamper the widespread application of the Si anode owing to its large volume variation during cycling and low intrinsic electrical conductivity.To mitigate these issues,free-standing N-doped porous carbon nanofibers sheathed pumpkin-like Si/C composites(Si/C-ZIF-8/CNFs)are designed and synthesized by electrospinning and carbonization methods,which present greatly enhanced electrochemical properties for lithium-ion battery anodes.This particular structure alleviates the volume variation,promotes the formation of stable solid electrolyte interphase(SEI)film,and improves the electrical conductivity.As a result,the as-obtained free-standing Si/C-ZIF-8/CNFs electrode delivers a high reversible capacity of 945.5 mAh g^(-1) at 0.2 A g^(-1) with a capacity retention of 64% for 150 cycles,and exhibits a reversible capacity of 538.6 mA h g^(-1) at 0.5 A g^(-1) over 500 cycles.Moreover,the full cell composed of a freestanding Si/C-ZIF-8/CNFs anode and commercial LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)(NCM)cathode shows a capacity of 63.4 mA h g^(-1) after 100 cycles at 0.2 C,which corresponds to a capacity retention of 60%.This rational design could provide a new path for the development of high-performance Si-based anodes.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51072173, 51272221 and 51302239)Specialized Research Fund for the Doctoral Program of Higher Education (Grant Nos. 20134301130001)the Natural Science Foundation of Hunan Province, China (Grant Nos. 13JJ4051).
文摘As a promising energy-storage device,the hybrid lithium-ion capacitor coupling with both a large energy density battery-type anode and a high power density capacitor-type cathode is attracting great attention.For the sake of improving the energy density of hybrid lithium-ion capacitor,the free-standing anodes with good electrochemical performance are essential.Herein,we design an effective electrospinning strategy to prepare free-standing MnS/Co4S3/Ni3S2/Ni/C-nanofibers(TMSs/Ni/C-NFs)film and firstly use it as a binder-free anode for hybrid lithium-ion capacitor.We find that the carbon nanofibers can availably prevent MnS/Co4S3/Ni3S2/Ni nanoparticles from aggregation as well as significantly improve the electrochemical performance.Therefore,the binder-free TMSs/Ni/C-NFs membrane displays an ultrahigh reversible capacity of 1246.9 m Ah g-1at 100 m A g-1,excellent rate capability(398 mAh g-1 at2000 mA g-1),and long-term cyclic endurance.Besides,we further assemble the hybrid lithium-ion capacitor,which exhibits a high energy density of 182.0 Wh kg-1at 121.1 W kg-1(19.0 Wh kg-1 at 3512.5 W kg-1)and remarkable cycle life.
基金This study was supported by the funds from the Singapore Ministry of Education Academic Research Fund,Tier 1:RG111/15 and RG10/16 and Tier 2:MOE2016-T2-2 to 004.
文摘Electrochemical reduction of molecular O2 to hydrogen peroxide(H2O2)offers a promising solution for water purification and environmental remediation.Here,we design a hierarchical free-standing single-Co-atom(with Co-N4 coordination)electrode for oxygen reduction reaction(ORR)via a two-electron pathway to make H2O2 in acidic media.The current density of the single-Co-atom electrode reached 51 mA/cm2 at 0.1 V vs reversible hydrogen electrode,lasting for more than 10 hours of continuous operation with H2O2 selectivity greater than 80%.Toward practical application,the single-Co-atom electrode was directly used to assemble an electrochemical cell to produce H2O2 at a rate of 676 mol/kgcat/h with a cell voltage of about 1.6 V.
基金the National Natural Science Foundation of China(Grant Nos.51672234,52072325)the Key Research Foundation of Education Bureau of Hunan Province,China(Grant No.20A486)+1 种基金Hunan 2011 Collaborative Innovation Center of Chemical Engineering and Technology with Environmental Benignity and Effective Resource Utilization,Program for Innovative Research Cultivation Team in University of Ministry of Education of China(1337304)the 111 Project(B12015).
文摘Wearable and portable mobile phones play a critical role in the market, and one of the key technologies is the flexible electrode with high specific capacity and excellent mechanical flexibility. Herein, a wire-in-wire TiO_(2)/C nanofibers (TiO_(2) ww/CN) film is synthesized via electrospinning with selenium as a structural inducer. The interconnected carbon network and unique wire- in-wire nanostructure cannot only improve electronic conductivity and induce effective charge transports, but also bring a superior mechanic flexibility. Ulti-mately, TiO_(2) ww/CN film shows outstanding electrochemical performance as free-standing electrodes in Li/K ion batteries. It shows a discharge capacity as high as 303 mAh g^(−1) at 5 A g^(−1) after 6000 cycles in Li half-cells, and the unique structure is well-reserved after long-term cycling. Moreover, even TiO_(2) has a large diffusion barrier of K^(+), TiO_(2) ww/CN film demonstrates excellent perfor-mance (259 mAh g^(−1) at 0.05 A g^(−1) after 1000 cycles) in K half-cells owing to extraordinary pseudocapacitive contribution. The Li/K full cells consisted of TiO_(2) ww/CN film anode and LiFePO_(4)/Perylene-3,4,9,10-tetracarboxylic dianhydride cathode possess outstanding cycling stability and demonstrate practical application from lighting at least 19 LEDs. It is, therefore, expected that this material will find broad applications in portable and wearable Li/K-ion batteries.
基金supported by the National Natural Science Foundation of China(52172239)Project of State Key Laboratory of Environment-Friendly Energy Materials+2 种基金Southwest University of Science and Technology(Grant Nos.21fksy24 and 18ZD320304)Chongqing Talents:Exceptional Young Talents Project(Grant No.CQYC201905041)Natural Science Foundation of Chongqing China(Grant No.cstc2021jcyj-jqX0031)。
文摘The defect chemistry is successfully modulated on free-standing and binder-free carbon cathodes for highly efficient Li-S redox reactions.Such rationally regulated defect engineering realizes the synchronization of ion/electron-conductive and defect-rich networks on the threedimension carbon cathode,leading to its tunable activity for both relieving the shuttle phenomenon and accelerating the sulfur redox reaction kinetics.As expected,the defective carbon cathode harvests a high rate capacity of 1217.8 mAh g^(-1)at 0.2 C and a superior capacity retention of61.7%at 2 C after 500 cycles.Even under the sulfur mass loading of 11.1 mg cm^(-2),the defective cathode still holds a remarkable areal capacity of 8.5 mAh cm^(-2).
基金financially supported by Liaoning Revitalization Talents Program—Pan Deng Scholars(XLYC1802005)Liaoning BaiQianWan Talents Program+4 种基金the National Science Fund of Liaoning Province for Excellent Young ScholarsScience and Technology Innovative Talents Support Program of Shenyang(RC180166)Australian Research Council(ARC)through Discovery Early Career Researcher Award(DE150101306)and Linkage Project(LP160100927)Faculty of Science Strategic Investment Funding of University of NewcastleCSIRO Newcastl Energy Centre。
文摘Electrocatalytic nitrogen reduction reaction is a carbon-free and energy-saving strategy for efficient synthesis of ammonia under ambient conditions.Here,we report the synthesis of nanosized Bi2O3 particles grown on functionalized exfoliated graphene(Bi2O3/FEG)via a facile electrochemical deposition method.The obtained free-standing Bi2O3/FEG achieves a high Faradaic efficiency of 11.2%and a large NH3 yield of 4.21±0.14μgNH3 h^-1 cm^-2 at-0.5 V versus reversible hydrogen electrode in 0.1 M Na2SO4,better than that in the strong acidic and basic media.Benefiting from its strong interaction of Bi 6p band with the N2p orbitals,binder-free characteristic,and facile electron transfer,Bi2O3/FEG achieves superior catalytic performance and excellent long-term stability as compared with most of the previous reported catalysts.This study is significant to design low-cost,high-efficient Bi-based electrocatalysts for electrochemical ammonia synthesis.
基金supported by the start-up fund from Kunming University of Science and Technology,the National Natural Science Foundation of China (Grants 52102046,51872293,52130209,52072375)Liaoning Revitalization Talents Program (XLYC2002037)Basic Research Project of Natural Science Foundation of Shandong Province,China (ZR2019ZD49).
文摘The keen interest in fuel cells and metal-air batteries stimulates a great deal of research on the development of a cost-efficient and high-performance catalyst as an alternative to traditional Pt to boost the sluggish oxygen reduction reaction(ORR)at the cathode.Herein,we report a facile and scalable strategy for the large-scale preparation of a free-standing and flexible porous atomically dispersed Fe-N-doped carbon microtube(FeSAC/PCMT)sponge.Benefiting from its unique structure that greatly facilitates the catalytic kinetics,mass transport,and electron transfer,our FeSAC/PCMT electrode exhibits excellent performance with an ORR potential of 0.942 V at^(-3) mA cm^(-2).When the FeSAC/PCMT sponge was directly used as an oxygen electrode for liquid-state and flexible solid-state zinc-air batteries,high peak power densities of 183.1 and 58.0 mW cm^(-2) were respectively achieved,better than its powdery counterpart and commercial Pt/C catalyst.Experimental and theoretical investigation results demonstrate that such ultrahigh ORR performance can be attributed to atomically dispersed Fe-N_(5) species in FeSAC/PCMT.This study presents a cost-effective and scalable strategy for the fabrication of highly efficient and flexible oxygen electrodes,provides a significant new insight into the catalytic mechanisms,and helps to realize significant advances in energy devices.
基金the National Natural Science Foundation of China(Grant Nos.51772089,21872046 and 51902100)the Outstanding Youth Scientist Foundation of Hunan Province(Grant No.2018JJ1009)+5 种基金the Youth 1000 Talent Program of Chinathe Science and Technology Innovation Platform and Talent Plan of Hunan Province(Grant No.2017XK2023)the Research and Development Plan of Key Areas in Hunan Province(Grant No.2019GK2235)China Postdoctoral Science Foundation(2018M642971)the Youth Scientist Foundation of Hunan Province(Grant No.2019JJ50087)the Shenzhen Science and Technology Innovation Committee(Grant No.JCYJ20151013162733704)。
文摘Highly efficient electrocatalysts towards hydrogen evolution reaction(HER) with large current density at all-pH values are critical for the sustainable hydrogen production. Herein, we report a free-standing HER electrode, phosphorous-doped molybdenum nitride nanoparticles embedded in 3-dimentional carbon nanosheet matrix(P-Mo2N-CNS) fabricated via one-step carbonization and in-situ formation. The asprepared catalyst shows free-standing architecture with interconnected porous microstructure. P-doped Mo2N nanoparticles with an average diameter of 4.4 nm are well embedded in the 3-dimentional vertical carbon nanosheets matrix. Remarkable electrocatalytic HER performance is observed in alkaline, neutral and acidic media at large current densities. The overpotential of P-Mo2N-CNS to drive a current density of 100 mA cm-2 in 0.5 M H2SO4 and 1.0 M PBS is only 181 and 221 mV, respectively. In particular, the current density reaches up to 1000 mA cm-2 at a low overpotential of 256 mV in 1.0 M KOH, much better than that of the commercial Pt/C catalyst. Density functional theory calculations suggest the optimized H sorption kinetics on Mo2N after P doping, elucidating the superior activity.
基金supported by the National Natural Science Foundation of China (Nos.51372060,21676067 and 21606065)Anhui Provincial Natural Science Foundation of China (No.1708085QE98)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Opening Project of CAS Key Laboratory of Materials for Energy Conversion (No.KF2016005)
文摘Vanadium pentoxide （V2O5.nH2O） nanoribbons are synthesized via a hydrothermal process. These ribbons are 20nm thick, 200nm to 1 μm wide and several tens of micrometers long. Free-standing binder-free films are prepared by using these nanoribbons with multi-walled carbon nanotubes （MWCNTs） and used as the cathode for rechargeable sodium batteries. The large interlayer space between the V20s5 bilayers can enhance the kinetics of sodium ion intercalation/deintercalation. In addition, the intertwining network of the V2O5. 0.34H2O film provides efficient electron conduction pathways and shortens diffusion distances of sodium ion. The electrochemical tests prove that the free- standing V2O5. 0.34H2O film cathode delivers high reversible specific capacities （190 mAh/g） and good cycling stabilities （170 mAh/g after 150 cycles） in the voltage range between 1.5V and 3.5V.
基金financially supported by the Key Project of Natural Science Foundation of Tianjin (No. 18JCZDJC97200)
文摘Most efficient visible-light-responsive photocatalysts are in the form of powder,leading to the tedious separation from the reaction media.Herein,we developed a versatile method for the general synthesis of free-standing polyacrylonitrile(PAN)/Ag/AgX(X=Br,I)nanofiber mats,where fibrous PAN/Ag precursor was firstly prepared via an electroless plating strategy,followed by a direct elemental halogenation with Br2/H2O or I2/ethanol solution.The as-obtained PAN/Ag/AgX nanofiber mats exhibit exceptional photocatalytic activity toward degradation of organic pollutants.Furthermore,the flexibility enables it to be easily recovered after the reaction was completed.This work provides new insights into the fabrication of membrane-based photocatalysts on a large scale.
基金the R&D Convergence Program of NST(National Research Council of Science&Technology)of the Republic of Korea(CAP-15-02-KBSI)a National Research Foundation of Korea(NRF)grant funded by the Korean Government(MSIT)(No.2019R1C1C1007745)a National Research Foundation of Korea(NRF)grant funded by the Korean Government(Ministry of Science,ICT&Future Planning)(No.2019R1A4A2001527).
文摘The development of sulfur cathodes with high areal capacity and high energy density is crucial for the practical application of lithium-sulfur batteries(LSBs).LSBs can be built by employing(ultra)high-loading sulfur cathodes,which have rarely been realized due to massive passivation and shuttling.Herein,microspheres of a carbon-carbon nitride composite(C@CN)with large mesopores are fabricated via molecular cooperative assembly.Using the C@CN-based electrodes,the effects of the large mesopores and N-functional groups on the electrochemical behavior of sulfur in LSB cells are thoroughly investigated under ultrahigh sulfur-loading conditions(>15 mgS cm^(-2)).Furthermore,for high-energy-density LSBs,the C@CN powders are pelletized into a thick free-standing electrode(thickness:500^m;diameter:11 mm)via a simple briquette process;here,the total amount of energy stored by the LSB cells is 39 mWh,corresponding to a volumetric energy density of 440 Wh L-1 with an areal capacity of 24.9 and 17.5 mAh cm^(-2) at 0.47 and 4.7 mA cm^(-2),respectively(at 24mgS cm^(-2)).These results have significantly surpassed most recent records due to the synergy among the large mesopores,(poly)sulfide-philic surfaces,and thick electrodes.The developed strategy with its potential for scale-up successfully fills the gap between laboratory-scale cells and practical cells without sacrificing the high areal capacity and high energy density,providing a solid foundation for the development of practical LSBs.
基金supported by the Key Program of Equipment PreResearch Foundation of China(6140721020103)the National Basic Research Program of China(973 Program)(2013CB934001)the National Natural Science Foundation of China(51074011 and51274017)
文摘Two shapes of Co_3O_4 nanoarrays(i.e., nanosheets, nanowires) with different densities of exposed catalytic active sites were synthesized through a facile hydrothermal method on Ni foam substrates and tested as the binder/carbon free and free-standing cathodes for Li–O_2 batteries. Particularly, the single crystalline feature of Co_3O_4 nanosheets with a predominant high reactivity {112} exposed crystal plane and hierarchical porous nanostructure displayed better catalytic performance for both oxygen reduction reaction(during discharge process) and oxygen evolution reaction(during charge process). Li–O_2 battery with Co_3O_4 nanosheets cathode exhibited a higher discharge specific capacity(965 m Ah g^(-1)), lower discharge/charge over-potential and better cycling performance over 63 cycles at 100 mA g^(-1) with the specific capacity limited at 300 mAh g^(-1). The superior catalytic performance of Co_3O_4 nanosheets cathode is ascribed to the enlarging specific area and increasing the exposed Co^(3+) catalytic active sites within predominant {112} crystal plane which plays the key role in determining the adsorption energy for the reactants, enabling high round-trip efficiency and cyclic life.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51572033,51572241,61774019,61704153,and 11404029)the Fund of State Key Laboratory of IPOC(BUPT)+1 种基金the Open Fund of IPOC(BUPT)Beijing Municipal Commission of Science and Technology,China(Grant No.SX2018-04)
文摘Flexible electronic devices have attracted much attention due to their practical and commercial value. Integration of thin films with soft substrate is an effective way to fabricate flexible electronic devices. Ga_2O_3 thin films deposited directly on soft substrates would be amorphous mostly. However, the thickness of the thin film obtained by mechanical exfoliation method is difficult to control and the edge of the film is fragile and easy to be damaged. In this work, we fabricated free-standing Ga_2O_3 thin films using the water-soluble perovskite Sr_3Al_2O_6 as a sacrificial buffer layer. The obtained Ga_2O_3 thin films were polycrystalline. The thickness and dimension of the films were controllable. A flexible Ga_2O_3solar-blind UV photodetector was fabricated by transferring the free-standing Ga_2O_3 film on a flexible polyethylene terephthalate substrate. The results displayed that the photoelectric performances of the flexible Ga_2O_3 photodetector were not sensitive to bending of the device. The free-standing Ga_2O_3 thin films synthesized through the method described here can be transferred to any substrates or integrated with other thin films to fabricate electronic devices.
基金Science and technology plan project of Hebei Academy of Sciences(No.191408)Natural Science Foundation of Hebei Province(E2019302005)
文摘Recently,with the rapid development of chemical vapor deposition(CVD)technology,large area free-standing CVD diamond films have been produced successfully.However,the coarse grain size on the surface and the non-uniform thickness of unprocessed CVD diamond films make it difficult to meet the application requirement.The current study evaluates several existing polishing methods for CVD diamond films,including mechanical polishing,chemical mechanical polishing and tribochemical polishing technology.
文摘Similar to free-standing pile groups, piled raft foundations are conventionally designed in which the piles carry the total load of structure and the raft bearing capacity is not taken into account. Numerous studies indicated that this method is too conservative. Only when the pile cap is elevated from the ground level,the raft bearing contribution can be neglected. In a piled raft foundation, pileesoileraft interaction is complicated. Although several numerical studies have been carried out to analyze the behaviors of piled raft foundations, very few experimental studies are reported in the literature. The available laboratory studies mainly focused on steel piles. The present study aims to compare the behaviors of piled raft foundations with free-standing pile groups in sand, using laboratory physical models. Cast-in-place concrete piles and concrete raft are used for the tests. The tests are conducted on single pile, single pile in pile group, unpiled raft, free-standing pile group and piled raft foundation. We examine the effects of the number of piles, the pile installation method and the interaction between different components of foundation. The results indicate that the ultimate bearing capacity of the piled raft foundation is considerably higher than that of the free-standing pile group with the same number of piles. With installation of the single pile in the group, the pile bearing capacity and stiffness increase. Installation of the piles beneath the raft decreases the bearing capacity of the raft. When the raft bearing capacity is not included in the design process, the allowable bearing capacity of the piled raft is underestimated by more than 200%. This deviation intensifies with increasing spacing of the piles.
基金financial support from the National Natural Science Foundation of China(52122407,52174285,and 51974370)the Program of Huxiang Young Talents(2019RS2002)the Innovation and entrepreneurship project of Hunan Province,China(Grant No.2020GK4051)。
文摘The ever-increasing demands for advanced lithium-ion batteries with high energy density have greatly stimulated the pursuit of thick electrodes with high active material loading.However,it is not feasible to prepare thick electrodes with traditional coating methods due to mechanical instability.Herein,using single-wall carbon nanotubes(SWCNT)as conductive carbon and binder,free-standing LiMn_(2)O_(4) thick electrodes(F-LMO)with ultrahigh-mass loading up to~190 mg cm^(-2)were prepared by vacuum filtration combined with freeze-drying.The thick electrodes with~30 mg cm^(-2)mass loading achieved a high specific capacity of 106.7 mAh g^(-1)with a good capacity retention of 94%over 50 cycles at 0.5 C,which was superior to the traditional coating electrodes(~20 mg cm^(-2))of 99.3 mAh g^(-1)with 95%because of the enhanced electronic conductivity originated from SWCNT.In addition,the high active material ratio of 97.5 wt%,near-theoretical reversible capacity,and high mass loading gave ultrathick F-LMO electrodes(600μm)of~190 mg cm^(-2)with a remarkable areal capacity of 20 mAh cm^(-2).Moreover,the concentration polarization that occurred in the thick F-LMO electrodes under high current density was discussed via electrochemical stimulation.
基金supported by the Creative Materials Discovery Program (Grant No. 2018M3D1A1057844) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICTthe Basic Science Research Program through the NRF funded by the Ministry of Science, ICT and Future Planning (Grant No. 2021R1A2B5B01002879).
文摘Rational construction of flexible free-standing electrocatalysts featuring long-lasting durability,high efficiency,and wide temperature tolerance under harsh practical operations are fundamentally significant for commercial zinc-air batteries.Here,3D flexible free-standing bifunctional membrane electrocatalysts composed of covalently cross-linked supramolecular polymer networks with nitrogen-deficient carbon nitride nanotubes are fabricated(referred to as PEMAC@NDCN)by a facile self-templated approach.PEMAC@NDCN demonstrates the lowest reversible oxygen bifunctional activity of 0.61 V with exceptional long-lasting durability,which outperforms those of commercial Pt/C and RuO_(2).Theoretical calculations and control experi-ments reveal the boosted electron transfer,electrolyte mass/ion transports,and abundant active surface site preferences.Moreover,the constructed alkaline Zn-air battery with PEMAC@NDCN air-cathode reveals superb power density,capacity,and discharge-charge cycling stability(over 2160 cycles)compared to the reference Pt/C+RuO_(2).Solid-state Zn-air batteries enable a high power density of 211 mW cm^(−2),energy density of 1056 Wh kg^(−1),stable charge-discharge cycling of 2580 cycles for 50 mA cm^(−2),and wide temperature tolerance from−40 to 70℃with retention of 86%capacity compared to room-temperature counterparts,illustrating prospects over harsh operations.
基金supported by the Chinese National Natural Science Foundation(No.22075008,21571010,U0734002)National Basic Research Programs of China(973 Program,No.2014CB931800,2011CB935700)+1 种基金Chinese Aeronautic Project(No.2013ZF51069)111 Project(No.B14009).
文摘Li metal with high-energy density is considered as the most promising anode for the next-generation rechargeable Li metal batteries;however,the growth of Li dendrites seriously hinders its practical application.Herein,3D free-standing carbon nanofibers modified by lithiophilic metal particles(CNF/Me,Me=Sn,Fe,Co)are obtained in situ by the electrospinning method.Benefiting from the lithophilicity,the CNF/Me composite may effectively prevent the formation of Li dendrites in the Li metal batteries.The optimized CNF/Sn–Li composite electrode exhibits a stable cycle life of over 2350 h during Li plating/stripping.When matched with typical commercial LiFePO_(4)(LFP)cathode,the LFP//CNF/Sn–Li full cell presents a high initial discharge specific capacity of 139 mAh g^(−1)at 1 C,which remains at 146 mAh g^(−1)after 400 cycles.When another state-of-the-art commercial LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM(811))cathode is used,the assembled NCM//CNF/Sn–Li full cell shows a large initial specific discharge capacity of 206 mAh g^(−1)at substantially enhanced 10 C,which keeps at the good capacity of 99 mAh g^(−1)after 300 cycles.These results are greatly superior to the counterparts with Li as the anodes,indicating the great potential for practical utilization of the advanced CNF/Sn–Li electrode.
