Layered oxides have attracted significant attention as cathodes for sodium-ion batteries(SIBs)due to their compositional versatility and tuneable electrochemical performance.However,these materials still face challeng...Layered oxides have attracted significant attention as cathodes for sodium-ion batteries(SIBs)due to their compositional versatility and tuneable electrochemical performance.However,these materials still face challenges such as structural phase transitions,Na^(+)/vacancy ordering,and Jahn–Teller distortion effect,resulting in severe capacity decay and sluggish ion kinetics.We develop a novel Cu/Y dual-doping strategy that leads to the formation of"Na–Y"interlayer aggregates,which act as structural pillars within alkali metal layers,enhancing structural stability and disrupting the ordered arrangement of Na^(+)/vacancies.This disruption leads to a unique coexistence of ordered and disordered Na^(+)/vacancy states with near-zero strain,which significantly improves Na^(+)diffusion kinetics.This structural innovation not only mitigates the unfavorable P2–O2 phase transition but also facilitates rapid ion transport.As a result,the doped material demonstrates exceptional electrochemical performance,including an ultra-long cycle life of 3000 cycles at 10 C and an outstanding high-rate capability of~70 mAh g^(−1)at 50 C.The discovery of this novel interlayer pillar,along with its role in modulating Na^(+)/vacancy arrangements,provides a fresh perspective on engineering layered oxides.It opens up promising new pathways for the structural design of advanced cathode materials toward efficient,stable,and high-rate SIBs.展开更多
An amorphous ferric oxide layer was prepared on a bismuth vanadate photoanode.This resulted in improved charge carrier separation and surface catalytic performance compared with the photoanode without the oxide layer....An amorphous ferric oxide layer was prepared on a bismuth vanadate photoanode.This resulted in improved charge carrier separation and surface catalytic performance compared with the photoanode without the oxide layer.The photocurrent of the oxide‐layer‐containing photoanode was2.52mA/cm2at1.23V versus the reversible hydrogen electrode,in potassium phosphate buffer,(0.5mol/L,pH=7.0).The amorphous ferric oxide layer on the photoanode contained low‐valence‐state iron species(FeII),which enabled efficient hole extraction and transfer.展开更多
Oxygen release and electrolyte decomposition under high voltage endlessly exacerbate interfacial ramifications and structu ral degradation of high energy-density Li-rich layered oxide(LLO),leading to voltage and capac...Oxygen release and electrolyte decomposition under high voltage endlessly exacerbate interfacial ramifications and structu ral degradation of high energy-density Li-rich layered oxide(LLO),leading to voltage and capacity fading.Herein,the dual-strategy of Cr,B complex coating and local gradient doping is simultaneously achieved on LLO surface by a one-step wet chemical reaction at room temperature.Density functional theory(DFT)calculations prove that stable B-O and Cr-O bonds through the local gradient doping can significantly reduce the high-energy O 2p states of interfacial lattice O,which is also effective for the near-surface lattice O,thus greatly stabilizing the LLO surface,Besides,differential electrochemical mass spectrometry(DEMS)indicates that the Cr_(x)B complex coating can adequately inhibit oxygen release and prevents the migration or dissolution of transition metal ions,including allowing speedy Li^(+)migration,The voltage and capacity fading of the modified cathode(LLO-C_(r)B)are adequately suppressed,which are benefited from the uniformly dense cathode electrolyte interface(CEI)composed of balanced organic/inorganic composition.Therefore,the specific capacity of LLO-CrB after 200 cycles at 1C is 209.3 mA h g^(-1)(with a retention rate of 95.1%).This dual-strategy through a one-step wet chemical reaction is expected to be applied in the design and development of other anionic redox cathode materials.展开更多
Layered transition metal oxides have emerged as promising cathode materials for sodium ion batteries.However,irreversible phase transitions cause structural distortion and cation rearrangement,leading to sluggish Na+d...Layered transition metal oxides have emerged as promising cathode materials for sodium ion batteries.However,irreversible phase transitions cause structural distortion and cation rearrangement,leading to sluggish Na+dynamics and rapid capacity decay.In this study,we propose a medium-entropy cathode by simultaneously introducing Fe,Mg,and Li dopants into a typical P2-type Na_(0.75)Ni_(0.25)Mn_(0.75)O_(2)cathode.The modified Na_(0.75)Ni_(0.2125)Mn_(0.6375)Fe_(0.05)Mg_(0.05)Li_(0.05)O_(2)cathode predominantly exhibits a main P2 phase(93.5%)with a minor O3 phase(6.5%).Through spectroscopy techniques and electrochemical investigations,we elucidate the redox mechanisms of Ni^(2+/3+/4+),Mn^(3+/4+),Fe^(3+/4+),and O_(2)-/O_(2)^(n-)during charging/discharging.The medium-entropy doping mitigates the detrimental P2-O_(2)phase transition at high-voltage,replacing it with a moderate and reversible structural evolution(P2-OP4),thereby enhancing structural stability.Consequently,the modified cathode exhibits a remarkable rate capacity of 108.4 mAh·g^(-1)at 10C,with a capacity retention of 99.0%after 200 cycles at 1C,82.5%after 500 cycles at 5C,and 76.7%after 600 cycles at 10C.Furthermore,it also demonstrates superior electrochemical performance at high cutoff voltage of 4.5 V and extreme temperature(55 and 0℃).This work offers solutions to critical challenges in sodium ion batteries cathode materials.展开更多
The cobalt-free Mn-based Li-rich layered oxide material has the advantages of low cost,high energy density,and good performance at low temperatures,and is the promising choice for energy storage batteries.However,the ...The cobalt-free Mn-based Li-rich layered oxide material has the advantages of low cost,high energy density,and good performance at low temperatures,and is the promising choice for energy storage batteries.However,the long-cycling stability of batteries needs to be improved.Herein,the Mn-based Li-rich cathode materials with small amounts of Li2 MnO3 crystal domains and gradient doping of Al and Ti elements from the surface to the bulk have been developed to improve the structure and interface stability.Then the batteries with a high energy density of 600 Wh kg^(-1),excellent capacity retention of 99.7%with low voltage decay of 0.03 mV cycle^(-1) after 800 cycles,and good rates performances can be achieved.Therefore,the structure and cycling stability of low voltage Mn-based Li-rich cathode materials can be significantly improved by the bulk structure design and interface regulation,and this work has paved the way for developing low-cost and high-energy Mn-based energy storage batteries with long lifetime.展开更多
Sodium-ion batteries(SIBs)have attracted significant attention in large-scale energy storage system because of their abundant sodium resource and cost-effectiveness.Layered oxide materials are particularly promising a...Sodium-ion batteries(SIBs)have attracted significant attention in large-scale energy storage system because of their abundant sodium resource and cost-effectiveness.Layered oxide materials are particularly promising as SIBs cathodes due to their high theoretical capacities and facile synthesis.However,their practical applications are hindered by the limitations in energy density and cycling stability.The comprehensive understanding of failure mechanisms within bulk structure and at the cathode/electrolyte interface of cathodes is still lacking.In this review,the issues related to bulk phase degradation and surface degradation,such as irreversible phase transitions,cation migration,transition metal dissolution,air/moisture instability,intergranular cracking,interfacial reactions,and reactive oxygen loss,are discussed.The latest advances and strategies to improve the stability of layered oxide cathodes and full cells are provided,as well as our perspectives on the future development of SIBs.展开更多
Mn-based layered oxides(KMO)have emerged as one of the promising low-cost cathodes for potassiumion batteries(PIBs).However,due to the multiple-phase transitions and the distortion in the MnO6structure induced by the ...Mn-based layered oxides(KMO)have emerged as one of the promising low-cost cathodes for potassiumion batteries(PIBs).However,due to the multiple-phase transitions and the distortion in the MnO6structure induced by the Jahn-Teller(JT)effect associated with Mn-ion,the cathode exhibits poor structural stability.Herein,we propose a strategy to enhance structural stability by introducing robust metal-oxygen(M-O)bonds,which can realize the pinning effect to constrain the distortion in the transition metal(TM)layer.Concurrently,all the elements employed have exceptionally high crustal abundance.As a proof of concept,the designed K_(0.5)Mn_(0.9)Mg_(0.025)Ti_(0.025)Al_(0.05)O_(2)cathode exhibited a discharge capacity of approximately 100 mA h g^(-1)at 20 mA g^(-1)with 79%capacity retention over 50 cycles,and 73%capacity retention over 200 cycles at 200 mA g^(-1),showcased much better battery performance than the designed cathode with less robust M-O bonds.The properties of the formed M-O bonds were investigated using theoretical calculations.The enhanced dynamics,mitigated JT effect,and improved structural stability were elucidated through the in-situ X-ray diffractometer(XRD),in-situ electrochemical impedance spectroscopy(EIS)(and distribution of relaxation times(DRT)method),and ex-situ X-ray absorption fine structure(XAFS)tests.This study holds substantial reference value for the future design of costeffective Mn-based layered cathodes for PIBs.展开更多
Nickel-rich(Ni≥90%)layered oxides materials have emerged as a promising candidate for nextgeneration high-energy-density lithium-ion batteries(LIBs).However,their widespread application is hindered by structural fati...Nickel-rich(Ni≥90%)layered oxides materials have emerged as a promising candidate for nextgeneration high-energy-density lithium-ion batteries(LIBs).However,their widespread application is hindered by structural fatigue and lattice oxygen loss.In this work,an epitaxial surface rock-salt nanolayer is successfully developed on the LiNi_(0.9)Co_(0.1)O_(2)sub-surface via heteroatom anchoring utilizing high-valence element molybdenum modification.This in-situ formed conformal buffer phase with a thickness of 1.2 nm effectively suppresses the continuous interphase side-reactions,and thus maintains the excellent structure integrity at high voltage.Furthermore,theoretical calculations indicate that the lattice oxygen reversibility in the anion framework of the optimized sample is obviously enhanced due to the higher content of O 2p states near the Fermi level than that of the pristine one.Meanwhile,the stronger Mo-O bond further reduces cell volume alteration,which improves the bulk structure stability of modified materials.Besides,the detailed charge compensation mechanism suggests that the average oxidation state of Ni is reduced,which induces more active Li+participating in the redox reactions,boosting the cell energy density.As a result,the uniquely designed cathode materials exhibit an extraordinary discharge capacity of 245.4 mAh g^(-1)at 0.1 C,remarkable rate performance of 169.3 mAh g^(-1)at 10 C at 4.5 V,and a high capacity retention of 70.5% after 1000 cycles in full cells at a high cut-off voltage of 4.4 V.This strategy provides an valuable insight into constructing distinctive heterostructure on highperformance Ni-rich layered cathodes for LIBs.展开更多
Facilitating anion redox chemistry is an effective strategy to increase the capacity of layered oxides for sodium-ion batteries.Nevertheless,there remains a paucity of literature pertaining to the oxygen redox chemist...Facilitating anion redox chemistry is an effective strategy to increase the capacity of layered oxides for sodium-ion batteries.Nevertheless,there remains a paucity of literature pertaining to the oxygen redox chemistry of O3-type layered oxide cathode materials.This work systematically investigates the effect of Fe doping on the anionic oxygen redox chemistry and electrochemical reactions in O3-NaNi_(0.4)Cu_(0.1)Mn_(0.4)Ti_(0.1)O_(2).The results of the density functional theory(DFT)calculations indicate that the electrons of the O 2p occupy a higher energy level.In the ex-situ X-ray photoelectron spectrometer(XPS)of O 1s,the addition of Fe facilitates the lattice oxygen(O^(n-))to exhibit enhanced activity at 4.45 V.The in-situ X-ray diffraction(XRD)demonstrates that the doping of Fe effectively suppresses the Y phase transition at high voltages.Furthermore,the Galvanostatic Intermittent Titration Technique(GITT)data indicate that Fe doping significantly increases the Na~+migration rate at high voltages.Consequently,the substitution of Fe can elevate the cut-off voltage to 4.45 V,thereby facilitating electron migration from O^(2-).The redox of O^(2-)/O^(n-)(n<2)contributes to the overall capacity.O3-Na(Ni_(0.4)Cu_(0.1)Mn_(0.4)Ti_(0.1))_(0.92)Fe_(0.08)O_(2)provides an initial discharge specific capacity of 180.55 mA h g^(-1)and71.6%capacity retention at 0.5 C(1 C=240 mA g^(-1)).This work not only demonstrates the beneficial impact of Fe substitution for promoting the redox activity and reversibility of O^(2-)in 03-type layered oxides,but also guarantees the structural integrity of the cathode materials at high voltages(>4.2 V).It offers a novel avenue for investigating the anionic redox reaction in O3-type layered oxides to design advanced cathode materials.展开更多
Sodium-ion batteries(SIBs)have the advantages of environmental friendliness,cost-effectiveness,and high energy density,which are considered one of the most promising candidates for lithium-ion batteries(LIBs).The cath...Sodium-ion batteries(SIBs)have the advantages of environmental friendliness,cost-effectiveness,and high energy density,which are considered one of the most promising candidates for lithium-ion batteries(LIBs).The cathode materials influence the cost and energy output of SIBs.Therefore,the development of advanced cathode materials is crucial for the practical application of SIBs.Among various cathode materials,layered transition metal oxides(LTMOs)have received widespread attention owing to their straightforward preparation,abundant availability,and cost-competitiveness.Notably,layered Fe-based oxide cathodes are deemed to be one of the most promising candidates for the lowest price and easy-to-improve performance.Nevertheless,the challenges such as severe phase transitions,sluggish diffusion kinetics and interfacial degradation pose significant hurdles in achieving high-performance cathodes for SIBs.This review first briefly outlines the classification of layered structures and the working principle of layered oxides.Then,recent advances in modification strategies employed to address current issues with layered iron-based oxide cathodes are systematically reviewed,including ion doping,biphasic engineering and surface modification.Furthermore,the review not only outlines the prospects and development directions for layered Fe-based oxide cathodes but also provides novel insights and directions for future research endeavors for SIBs.展开更多
Expanding the cutoff voltage of layered oxide cathodes for sodium-ion batteries(SIBs)is crucial for overcoming their existing energy density limitations.However,cationic/anodic redox-triggered multiple phase transitio...Expanding the cutoff voltage of layered oxide cathodes for sodium-ion batteries(SIBs)is crucial for overcoming their existing energy density limitations.However,cationic/anodic redox-triggered multiple phase transitions and unfavorable interfacial side reactions accelerate capacity and voltage decay.Herein,we present a straightforward melting plus reactive wetting strategy using H_(3)BO_(3)for surface modification of O_(3)-type Na_(0.9)Cu_(0.12)Ni_(0.33)Mn_(0.4)Ti_(0.15)O_(2)(CNMT).The transformation of H_(3)BO_(3)from solid to liquid under mild heating facilitates the uniform dispersion and complete surface coverage of CNMT particles.By neutralizing the residual alkali and extracting Na^(+)from the CNMT lattice,H_(3)BO_(3)forms a multifunctional Na_(2)B_(2)O_(5)-dominated layer on the CNMT surface.This Na_(x)B_(y)O_(z)(NBO)layer plays a positive role in providing low-barrier Na^(+)transport channels,suppressing phase transitions,and minimizing the generation of O_(2)/CO_(2)gases and resistive byproducts.As a result,at a charge cutoff voltage of 4.5 V,the NBO-coated CNMT delivers a high discharge capacity of 149,1 mAh g^(-1)at 10 mA g^(-1)and exhibits excellent cycling stability at 100 mA g^(-1)over 200 cycles with a higher capacity retention than that of pristine CNMT(86,4%vs,62.1%).This study highlights the effectiveness of surface modification using lowmelting-point solid acids,with potential applications for other layered oxide cathode materials to achieve stable high-voltage cycling.This proposed strategy opens new avenues for the construction of highquality coatings for high-voltage layered oxide cathodes in SIBs.展开更多
Surface oxide layers play a significant role in forming secondary oxidation inclusions during the casting process.In this study,three typical Mg-RE alloys(Mg-3Nd(NZ30K),Mg-3Nd-3Gd(EV33)and Mg-3Nd-4Y(WE43A))are selecte...Surface oxide layers play a significant role in forming secondary oxidation inclusions during the casting process.In this study,three typical Mg-RE alloys(Mg-3Nd(NZ30K),Mg-3Nd-3Gd(EV33)and Mg-3Nd-4Y(WE43A))are selected.Their surface oxide layers formed during the solidification are characterized in detail,and the corresponding oxidation mechanisms are discussed.The results reveal that RE elements obviously influence the characteristics of surface oxide layers,which depends on their ability to purify the formed MgO in the melt via the reaction(2RE+3MgO=3Mg+RE_(2)O_(3)).On the one hand,as Nd and Gd do not easily displace MgO already formed in the melt,the loose oxide layers in NZ30K and EV33 alloys are mainly composed of MgO matrix with embedded RE-rich oxide particles.On the other hand,due to the strong ability of Y to purify MgO in the melt,the oxide layer of WE43A alloy becomes a denser and thinner Y_(2)O_(3) oxide layer.Note that the differences in surface oxide layers well explain the different secondary inclusions that occur in three typical Mg-RE alloys during the casting process.展开更多
Mn-based layered oxides are widely recognized as cathode materials for potassium-ion batteries(KIBs)due to their high specific capacity derived from their low molar mass.However,the structural instability caused by th...Mn-based layered oxides are widely recognized as cathode materials for potassium-ion batteries(KIBs)due to their high specific capacity derived from their low molar mass.However,the structural instability caused by the Jahn-Teller effect of Mn^(3+)and the large ionic radius of K+results in poor electrochemical performance.Herein,we propose an effective structural stabilization strategy for P2-type Mn-based layered oxide cathodes of KIBs through Li-incorporation into the transition metal layer.Using the firstprinciples calculations and experiments,we demonstrate that the P2-K_(0.48)[Li_(0.1)Mn_(0.9)]O_(2)(P2-KLMO)delivers improved electrochemical performance,specific capacity and average discharge voltage of~124.4 m A h g^(-1)and~2.7 V(vs.K^(+)/K)at 0.05C(1C=260 mA g^(-1)),outperforming P2-K_(0.5)MnO_(2).Operando X-ray diffraction analysis confirms the P2-OP4 phase transition and Mn^(3+)-induced Jahn-Teller distortion are significantly suppressed in P2-KLMO.These improvements are attributed to the lithium introduction into transition metal layers,leading to strengthened structural stability and enhanced K+diffusion kinetics.Moreover,synthetic accessibility through the conventional solid-state method provides an additional advantage for practical application of Li-incorporated Mn-based P2-type cathodes in KIBs.We believe our study offers a simple yet effective strategy for designing highperformance and practical cathode materials for KIBs.展开更多
Sodium-ion batteries(SIBs)employ P2-type layered transition metal oxides as promising cathode materials,primarily due to their abundant natural reserves and environmentally friendly characteristics.However,structural ...Sodium-ion batteries(SIBs)employ P2-type layered transition metal oxides as promising cathode materials,primarily due to their abundant natural reserves and environmentally friendly characteristics.However,structural instability and complex phase transitions during electrochemical cycling pose significant challenges to their practical applications.Employing cation substitution serves as a straightforward yet effective strategy for stabilizing the structure and improving the kinetics of the active material.In this study,we introduce a Ni-rich honeycomb-layered Na_(2+x)Ni_(2)TeO_(6)(NNTO)cathode material with variable sodium content(x=0,0.03,0.05,0.10).Physicochemical characterizations reveal that excess sodium content at the atomic scale modifies the surface and suppresses phase transitions,while preserving the crystal structure.This results in enhanced cyclic performance and improved electrochemical kinetics at room temperature.Furthermore,we investigate the performance of the NNTO cathode material containing 10%excess sodium at a relatively high temperature of 60℃,where it exhibits 71.6%capacity retention compared to 60%for the pristine.Overall,our results confirm that a preconstructed surface layer(induced by excess sodium)effectively safeguards the Ni-based cathode material from surface degradation and phase transitions during the electrochemical processes,thus exhibiting superior capacity retention relative to the pristine NNTO cathode.This study of the correlation between structure and performance can potentially be applied to the commercialization of SIBs.展开更多
P2-type layered oxide Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)(NM)is a promising cathode material for sodium-ion batteries(SIBs).However,the severe irreversible phase transition,sluggish Na+diffusion kinetics,and interfacial sid...P2-type layered oxide Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)(NM)is a promising cathode material for sodium-ion batteries(SIBs).However,the severe irreversible phase transition,sluggish Na+diffusion kinetics,and interfacial side reactions at high-voltage result in grievous capacity degradation and inferior electrochemical performance.Herein,a dual-function strategy of entropy tuning and artificial cathode electrolyte interface(CEI)layer construction is reported to generate a novel P2-type medium-entropy Na_(0.75)Li_(0.1)Mg_(0.05)Ni_(0.18)Mn_(0.66)Ta_(0.01)O_(2)with NaTaO_(3)surface modification(LMNMT)to address the aforementioned issues.In situ X-ray diffraction reveals that LMNMT exhibits a near zero-strain phase transition with a volume change of only 1.4%,which is significantly lower than that of NM(20.9%),indicating that entropy tuning effectively suppresses irreversible phase transitions and enhances ion diffusion.Kinetic analysis and post-cycling interfacial characterization further confirm that the artificial CEI layer promotes the formation of a stable,thin NaF-rich CEI and reduces interfacial side reactions,thereby further enhancing ion transport kinetics and surface/interface stability.Consequently,the LMNMT electrode exhibits outstanding rate capability(46 mA h g^(−1)at 20 C)and cycling stability(89.5%capacity retention after 200 cycles at 2 C)within the voltage range of 2–4.35 V.The LMNMT also exhibits superior all-climate performance and air stability.This study provides a novel path for the design of high-voltage cathode materials for SIBs.展开更多
The O3-type layered cathode with high Ni content has attracted much attention because of its high capacity and simple synthesis process.However,surface side reaction and O3-P3 phase transitions would occur during Na+i...The O3-type layered cathode with high Ni content has attracted much attention because of its high capacity and simple synthesis process.However,surface side reaction and O3-P3 phase transitions would occur during Na+insertion/extraction,resulting in unsatisfying electrochemical performance.Herein,O3-Na[Ni_(0.6)Co_(0.2)Mn_(0.2)]O_(2)(NNCM622)cathode is modified by a NaTiOx coating layer in a wet chemistry method,which reduces the parasitic reaction and facilitates Na+migration.Simultaneously,the partially doped Ti improves structural stability by restraining the irreversible multiple-phase transition.As a result,the modified NNCM622 cathode obtains a high specific capacity of 143.4 mAh g^(−1)and an improved capacity retention of 69%after 300 cycles.Our work offers new prospects for stabilizing the NNCM622 cathode with a feasible coating strategy.展开更多
O3-type layered oxide cathodes for sodium-ion batteries are promising owing to high theoretical capacity and broad temperature adaptability,yet hindered by structural degradation and sluggish Na^(+)diffusion kinetics....O3-type layered oxide cathodes for sodium-ion batteries are promising owing to high theoretical capacity and broad temperature adaptability,yet hindered by structural degradation and sluggish Na^(+)diffusion kinetics.Herein,we present a sodium-deficient high-entropy layered oxide cathode(Na_(0.85)Ni_(0.3)Mn_(0.3)Fe_(0.1)Co_(0.15)Ti_(0.1)Cu_(0.05)B_(0.02)O_(2),denoted as Na0.85-HEO),combining sodium content optimization and high-entropy composition design.Incorporating six transition metals and light element boron creates a unique high-entropy configuration,effectively mitigating local lattice distortion and internal strain through chemical disorder effects,thereby enabling highly reversible phase transitions(O3-P3-O3)and smaller volume change(0.6A^(3))during the initial cycle.The sodium-deficient high-entropy design effectively increases the sodium interlayer spacing to 0.322 nm,facilitating the Na^(+)diffusion kinetics.Moreover,this high-entropy strategy enables the cathode to have a completely solid solution charge curve and significantly reduces the proportion of(O_(2))^(n-),thereby suppressing gas release during the cycling process.The resultant cathode demonstrates exceptional cyclability(80% capacity retention after 400 cycles at 100 mA g^(-1)in a full cell),and remarkable low-temperature performance(108.6 mAh g^(-1)at -40℃).This work guides the design of high-entropy electrode materials with tailored ionic transport channels for extreme-temperature energy storage applications.展开更多
In the realm of sodium-ion batteries(SIBs),Mn-based layered oxide cathodes have garnered considerable attention owing to their anionic redox reactions(ARRs).Compared to other types of popular sodium-ion cathodes,Mn-ba...In the realm of sodium-ion batteries(SIBs),Mn-based layered oxide cathodes have garnered considerable attention owing to their anionic redox reactions(ARRs).Compared to other types of popular sodium-ion cathodes,Mn-based layered oxide cathodes with ARRs exhibit outstanding specific capacity and energy density,making them promising for SIB applications.However,these cathodes still face some scientific challenges that need to be addressed.This review systematically summarizes the composition,structure,oxygen-redox mechanism,and performance of various types of Mn-based cathodes with ARRs,as well as the main scientific challenges they face,including sluggish ion diffusion,cationic migration,O_(2) release,and element dissolution.Currently,to resolve these challenges,efforts mainly focus on six aspects:synthesis methods,structural design,doped modification,electrolyte design,and surface engineering.Finally,this review provides new insights for future direction,encompassing both fundamental research,such as novel cathode types,interface optimization,and interdisciplinary research,and considerations from an industrialization perspective,including scalability,stability,and safety.展开更多
The detrimental phase transformations of sodium layered transition metal oxides(Na_(x)TMO_(2))during desodiation/sodiation seriously suppress their practical applications for sodium ion batteries(SIBs).Undoubtedly,com...The detrimental phase transformations of sodium layered transition metal oxides(Na_(x)TMO_(2))during desodiation/sodiation seriously suppress their practical applications for sodium ion batteries(SIBs).Undoubtedly,comprehensively investigating of the dynamic crystal structure evolutions of Na_(x)TMO_(2)associating with Na ions extraction/intercalation and then deeply understanding of the relationships between electrochemical performances and phase structures drawing support from advanced characterization techniques are indispensable.In-situ high-energy X-ray diffraction(HEXRD),a powerful technology to distinguish the crystal structure of electrode materials,has been widely used to identify the phase evolutions of Na_(x)TMO_(2)and then profoundly revealed the electrochemical reaction processes.In this review,we begin with the descriptions of synchrotron characterization techniques and then present the advantages of synchrotron X-ray diffraction(XRD)over conventional XRD in detail.The optimizations of structural stability and electrochemical properties for P2-,O3-,and P2/O3-type Na_(x)TMO_(2)cathodes through single/dual-site substitution,high-entropy design,phase composition regulation,and surface engineering are summarized.The dynamic crystal structure evolutions of Na_(x)TMO_(2)polytypes during Na ion extraction/intercalation as well as corresponding structural enhancement mechanisms characterizing by means of HEXRD are concluded.The interior relationships between structure/component of Na_(x)TMO_(2)polytypes and their electrochemical properties are discussed.Finally,we look forward the research directions and issues in the route to improve the electrochemical properties of Na_(x)TMO_(2)cathodes for SIBs in the future and the combined utilizations of multiple characterization techniques.This review will provide significant guidelines for rational designs of high-performance Na_(x)TMO_(2)cathodes.展开更多
In the field of lithium-ion battery cathode materials, lithium-rich layered oxide materials have garnered significant attention due to their exceptional discharge specific capacity and high operating voltage. However,...In the field of lithium-ion battery cathode materials, lithium-rich layered oxide materials have garnered significant attention due to their exceptional discharge specific capacity and high operating voltage. However, their limitations in terms of cycling stability and rate capability remain major impediments to their wider application. In this study, an innovative approach was employed by simultaneously utilizing the acidic and oxidative properties of phosphomolybdic acid to generate a spinel structure and in-situ coating of a conductive polymer(polypyrrole) on the surface of lithium-rich layered oxide materials. This strategy aimed to mitigate structural degradation during charge-discharge cycles, enhance the ionic/electronic conductivity, and suppress side reactions. Experimental results demonstrated that after 200 cycles at a current density of 1 C, the modified sample exhibited a discharge specific capacity of 193.4 m Ah/g, with an improved capacity retention rate of 83.3% and a minimal voltage decay of only 0.27 V. These findings provide compelling support for the development and application of next-generation high-performance lithium-ion batteries.展开更多
基金supported by the“Pioneer”and“Leading Goose”R&D Program of Zhejiang Province of China(No.2024C01056)。
文摘Layered oxides have attracted significant attention as cathodes for sodium-ion batteries(SIBs)due to their compositional versatility and tuneable electrochemical performance.However,these materials still face challenges such as structural phase transitions,Na^(+)/vacancy ordering,and Jahn–Teller distortion effect,resulting in severe capacity decay and sluggish ion kinetics.We develop a novel Cu/Y dual-doping strategy that leads to the formation of"Na–Y"interlayer aggregates,which act as structural pillars within alkali metal layers,enhancing structural stability and disrupting the ordered arrangement of Na^(+)/vacancies.This disruption leads to a unique coexistence of ordered and disordered Na^(+)/vacancy states with near-zero strain,which significantly improves Na^(+)diffusion kinetics.This structural innovation not only mitigates the unfavorable P2–O2 phase transition but also facilitates rapid ion transport.As a result,the doped material demonstrates exceptional electrochemical performance,including an ultra-long cycle life of 3000 cycles at 10 C and an outstanding high-rate capability of~70 mAh g^(−1)at 50 C.The discovery of this novel interlayer pillar,along with its role in modulating Na^(+)/vacancy arrangements,provides a fresh perspective on engineering layered oxides.It opens up promising new pathways for the structural design of advanced cathode materials toward efficient,stable,and high-rate SIBs.
基金supported by the National Natural Science Foundation of China(21373083,21573068)Program of Shanghai Subject Chief Scientist(15XD1501300)+1 种基金the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education MinistryScience Technology Commission of Shanghai Municipality(14JC1490900)~~
文摘An amorphous ferric oxide layer was prepared on a bismuth vanadate photoanode.This resulted in improved charge carrier separation and surface catalytic performance compared with the photoanode without the oxide layer.The photocurrent of the oxide‐layer‐containing photoanode was2.52mA/cm2at1.23V versus the reversible hydrogen electrode,in potassium phosphate buffer,(0.5mol/L,pH=7.0).The amorphous ferric oxide layer on the photoanode contained low‐valence‐state iron species(FeII),which enabled efficient hole extraction and transfer.
基金financially supported by the National Natural Science Foundation of China(No.12304077)the Natural Science Foundation of Science and Technology Department of Sichuan Province(No.23NSFSC6224)+3 种基金Sichuan Science and Technology Program(No.2024NSFSC0989)the Key Laboratory of Computational Physics of Sichuan Province(No.YBUJSWL-YB-2022-03)the Material Corrosion and Protection Key Laboratory of Sichuan Province(No.2023CL14 and No.2023CL01)the National Innovation Practice Project(No.202411079005S).
文摘Oxygen release and electrolyte decomposition under high voltage endlessly exacerbate interfacial ramifications and structu ral degradation of high energy-density Li-rich layered oxide(LLO),leading to voltage and capacity fading.Herein,the dual-strategy of Cr,B complex coating and local gradient doping is simultaneously achieved on LLO surface by a one-step wet chemical reaction at room temperature.Density functional theory(DFT)calculations prove that stable B-O and Cr-O bonds through the local gradient doping can significantly reduce the high-energy O 2p states of interfacial lattice O,which is also effective for the near-surface lattice O,thus greatly stabilizing the LLO surface,Besides,differential electrochemical mass spectrometry(DEMS)indicates that the Cr_(x)B complex coating can adequately inhibit oxygen release and prevents the migration or dissolution of transition metal ions,including allowing speedy Li^(+)migration,The voltage and capacity fading of the modified cathode(LLO-C_(r)B)are adequately suppressed,which are benefited from the uniformly dense cathode electrolyte interface(CEI)composed of balanced organic/inorganic composition.Therefore,the specific capacity of LLO-CrB after 200 cycles at 1C is 209.3 mA h g^(-1)(with a retention rate of 95.1%).This dual-strategy through a one-step wet chemical reaction is expected to be applied in the design and development of other anionic redox cathode materials.
基金supported by the National Natural Science Foundation of China(No.21805018)by Sichuan Science and Technology Program(Nos.2022ZHCG0018,2023NSFSC0117 and 2023ZHCG0060)Yibin Science and Technology Program(No.2022JB005)and China Postdoctoral Science Foundation(No.2022M722704).
文摘Layered transition metal oxides have emerged as promising cathode materials for sodium ion batteries.However,irreversible phase transitions cause structural distortion and cation rearrangement,leading to sluggish Na+dynamics and rapid capacity decay.In this study,we propose a medium-entropy cathode by simultaneously introducing Fe,Mg,and Li dopants into a typical P2-type Na_(0.75)Ni_(0.25)Mn_(0.75)O_(2)cathode.The modified Na_(0.75)Ni_(0.2125)Mn_(0.6375)Fe_(0.05)Mg_(0.05)Li_(0.05)O_(2)cathode predominantly exhibits a main P2 phase(93.5%)with a minor O3 phase(6.5%).Through spectroscopy techniques and electrochemical investigations,we elucidate the redox mechanisms of Ni^(2+/3+/4+),Mn^(3+/4+),Fe^(3+/4+),and O_(2)-/O_(2)^(n-)during charging/discharging.The medium-entropy doping mitigates the detrimental P2-O_(2)phase transition at high-voltage,replacing it with a moderate and reversible structural evolution(P2-OP4),thereby enhancing structural stability.Consequently,the modified cathode exhibits a remarkable rate capacity of 108.4 mAh·g^(-1)at 10C,with a capacity retention of 99.0%after 200 cycles at 1C,82.5%after 500 cycles at 5C,and 76.7%after 600 cycles at 10C.Furthermore,it also demonstrates superior electrochemical performance at high cutoff voltage of 4.5 V and extreme temperature(55 and 0℃).This work offers solutions to critical challenges in sodium ion batteries cathode materials.
基金supported by the National Key R&D Program of China(No.2022YFB2404400)the National Natural Science Foundation of China(Nos.U23A20577,52372168,92263206 and 21975006)+1 种基金the“The Youth Beijing Scholars program”(No.PXM2021_014204_000023)the Beijing Natural Science Foundation(Nos.2222001 and KM202110005009).
文摘The cobalt-free Mn-based Li-rich layered oxide material has the advantages of low cost,high energy density,and good performance at low temperatures,and is the promising choice for energy storage batteries.However,the long-cycling stability of batteries needs to be improved.Herein,the Mn-based Li-rich cathode materials with small amounts of Li2 MnO3 crystal domains and gradient doping of Al and Ti elements from the surface to the bulk have been developed to improve the structure and interface stability.Then the batteries with a high energy density of 600 Wh kg^(-1),excellent capacity retention of 99.7%with low voltage decay of 0.03 mV cycle^(-1) after 800 cycles,and good rates performances can be achieved.Therefore,the structure and cycling stability of low voltage Mn-based Li-rich cathode materials can be significantly improved by the bulk structure design and interface regulation,and this work has paved the way for developing low-cost and high-energy Mn-based energy storage batteries with long lifetime.
基金supported by the National Natural Science Foundation of China(Grant No.W2412060,22325902 and 52171215)the State Key Laboratory of Clean Energy Utilization(Open Fund Project No.ZJUCEU2023002)。
文摘Sodium-ion batteries(SIBs)have attracted significant attention in large-scale energy storage system because of their abundant sodium resource and cost-effectiveness.Layered oxide materials are particularly promising as SIBs cathodes due to their high theoretical capacities and facile synthesis.However,their practical applications are hindered by the limitations in energy density and cycling stability.The comprehensive understanding of failure mechanisms within bulk structure and at the cathode/electrolyte interface of cathodes is still lacking.In this review,the issues related to bulk phase degradation and surface degradation,such as irreversible phase transitions,cation migration,transition metal dissolution,air/moisture instability,intergranular cracking,interfacial reactions,and reactive oxygen loss,are discussed.The latest advances and strategies to improve the stability of layered oxide cathodes and full cells are provided,as well as our perspectives on the future development of SIBs.
基金financially supported by the National Natural Science Foundation of China(NSFC)(52274295)the Natural Science Foundation of Hebei Province(E2021501029)+3 种基金the Fundamental Research Funds for the Central Universities(N2423051,N2423053,N2302016,N2423019,N2323013,N2423005)the Science and Technology Project of Hebei Education Department(QN2024238)the Basic Research Program Project of Shijiazhuang City for Universities Stationed in Hebei Province(241790937A)the Science and Technology Project of Qinhuangdao City in 2023.
文摘Mn-based layered oxides(KMO)have emerged as one of the promising low-cost cathodes for potassiumion batteries(PIBs).However,due to the multiple-phase transitions and the distortion in the MnO6structure induced by the Jahn-Teller(JT)effect associated with Mn-ion,the cathode exhibits poor structural stability.Herein,we propose a strategy to enhance structural stability by introducing robust metal-oxygen(M-O)bonds,which can realize the pinning effect to constrain the distortion in the transition metal(TM)layer.Concurrently,all the elements employed have exceptionally high crustal abundance.As a proof of concept,the designed K_(0.5)Mn_(0.9)Mg_(0.025)Ti_(0.025)Al_(0.05)O_(2)cathode exhibited a discharge capacity of approximately 100 mA h g^(-1)at 20 mA g^(-1)with 79%capacity retention over 50 cycles,and 73%capacity retention over 200 cycles at 200 mA g^(-1),showcased much better battery performance than the designed cathode with less robust M-O bonds.The properties of the formed M-O bonds were investigated using theoretical calculations.The enhanced dynamics,mitigated JT effect,and improved structural stability were elucidated through the in-situ X-ray diffractometer(XRD),in-situ electrochemical impedance spectroscopy(EIS)(and distribution of relaxation times(DRT)method),and ex-situ X-ray absorption fine structure(XAFS)tests.This study holds substantial reference value for the future design of costeffective Mn-based layered cathodes for PIBs.
基金financially supported by the National Natural Science Foundation of China(No.52202228,52402298)funded by the Science Research Project of Hebei Education Department(No.BJK2022011)+3 种基金the Central Funds Guiding the Local Science and Technology Development of Hebei Province(No.236Z4404G)the Beijing Tianjin Hebei Basic Research Cooperation Special Project(No.E2024202273)the Science and Technology Correspondent Project of Tianjin(24YDTPJC00240)supported by the U.S.Department of Energy’s Office of Science,Office of Basic Energy Science,Materials Sciences and Engineering Division。
文摘Nickel-rich(Ni≥90%)layered oxides materials have emerged as a promising candidate for nextgeneration high-energy-density lithium-ion batteries(LIBs).However,their widespread application is hindered by structural fatigue and lattice oxygen loss.In this work,an epitaxial surface rock-salt nanolayer is successfully developed on the LiNi_(0.9)Co_(0.1)O_(2)sub-surface via heteroatom anchoring utilizing high-valence element molybdenum modification.This in-situ formed conformal buffer phase with a thickness of 1.2 nm effectively suppresses the continuous interphase side-reactions,and thus maintains the excellent structure integrity at high voltage.Furthermore,theoretical calculations indicate that the lattice oxygen reversibility in the anion framework of the optimized sample is obviously enhanced due to the higher content of O 2p states near the Fermi level than that of the pristine one.Meanwhile,the stronger Mo-O bond further reduces cell volume alteration,which improves the bulk structure stability of modified materials.Besides,the detailed charge compensation mechanism suggests that the average oxidation state of Ni is reduced,which induces more active Li+participating in the redox reactions,boosting the cell energy density.As a result,the uniquely designed cathode materials exhibit an extraordinary discharge capacity of 245.4 mAh g^(-1)at 0.1 C,remarkable rate performance of 169.3 mAh g^(-1)at 10 C at 4.5 V,and a high capacity retention of 70.5% after 1000 cycles in full cells at a high cut-off voltage of 4.4 V.This strategy provides an valuable insight into constructing distinctive heterostructure on highperformance Ni-rich layered cathodes for LIBs.
基金financial support from the Natural Science Foundation of Shandong Province of China(ZR2023ME051,ZR2019MEM020)。
文摘Facilitating anion redox chemistry is an effective strategy to increase the capacity of layered oxides for sodium-ion batteries.Nevertheless,there remains a paucity of literature pertaining to the oxygen redox chemistry of O3-type layered oxide cathode materials.This work systematically investigates the effect of Fe doping on the anionic oxygen redox chemistry and electrochemical reactions in O3-NaNi_(0.4)Cu_(0.1)Mn_(0.4)Ti_(0.1)O_(2).The results of the density functional theory(DFT)calculations indicate that the electrons of the O 2p occupy a higher energy level.In the ex-situ X-ray photoelectron spectrometer(XPS)of O 1s,the addition of Fe facilitates the lattice oxygen(O^(n-))to exhibit enhanced activity at 4.45 V.The in-situ X-ray diffraction(XRD)demonstrates that the doping of Fe effectively suppresses the Y phase transition at high voltages.Furthermore,the Galvanostatic Intermittent Titration Technique(GITT)data indicate that Fe doping significantly increases the Na~+migration rate at high voltages.Consequently,the substitution of Fe can elevate the cut-off voltage to 4.45 V,thereby facilitating electron migration from O^(2-).The redox of O^(2-)/O^(n-)(n<2)contributes to the overall capacity.O3-Na(Ni_(0.4)Cu_(0.1)Mn_(0.4)Ti_(0.1))_(0.92)Fe_(0.08)O_(2)provides an initial discharge specific capacity of 180.55 mA h g^(-1)and71.6%capacity retention at 0.5 C(1 C=240 mA g^(-1)).This work not only demonstrates the beneficial impact of Fe substitution for promoting the redox activity and reversibility of O^(2-)in 03-type layered oxides,but also guarantees the structural integrity of the cathode materials at high voltages(>4.2 V).It offers a novel avenue for investigating the anionic redox reaction in O3-type layered oxides to design advanced cathode materials.
基金supported by the National Natural Science Foundation of China(no.52374301)the Open Project of Guangxi Key Laboratory of Electrochemical Energy Materials(no.GXUEEM2024001)+2 种基金the Hebei Provincial Natural Science Foundation(no.E2024501010)the Shijiazhuang Basic Research Project(no.241790667A)the Performance subsidy fund for Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province(no.22567627H)。
文摘Sodium-ion batteries(SIBs)have the advantages of environmental friendliness,cost-effectiveness,and high energy density,which are considered one of the most promising candidates for lithium-ion batteries(LIBs).The cathode materials influence the cost and energy output of SIBs.Therefore,the development of advanced cathode materials is crucial for the practical application of SIBs.Among various cathode materials,layered transition metal oxides(LTMOs)have received widespread attention owing to their straightforward preparation,abundant availability,and cost-competitiveness.Notably,layered Fe-based oxide cathodes are deemed to be one of the most promising candidates for the lowest price and easy-to-improve performance.Nevertheless,the challenges such as severe phase transitions,sluggish diffusion kinetics and interfacial degradation pose significant hurdles in achieving high-performance cathodes for SIBs.This review first briefly outlines the classification of layered structures and the working principle of layered oxides.Then,recent advances in modification strategies employed to address current issues with layered iron-based oxide cathodes are systematically reviewed,including ion doping,biphasic engineering and surface modification.Furthermore,the review not only outlines the prospects and development directions for layered Fe-based oxide cathodes but also provides novel insights and directions for future research endeavors for SIBs.
基金supported by the National Natural Science Foundation of China(22169002 and 22469003)the Chongzuo Key Research and Development Program of China(20241205 and 20231204)the Counterpart Aid Project for Discipline Construction from Guangxi University(2023M02)。
文摘Expanding the cutoff voltage of layered oxide cathodes for sodium-ion batteries(SIBs)is crucial for overcoming their existing energy density limitations.However,cationic/anodic redox-triggered multiple phase transitions and unfavorable interfacial side reactions accelerate capacity and voltage decay.Herein,we present a straightforward melting plus reactive wetting strategy using H_(3)BO_(3)for surface modification of O_(3)-type Na_(0.9)Cu_(0.12)Ni_(0.33)Mn_(0.4)Ti_(0.15)O_(2)(CNMT).The transformation of H_(3)BO_(3)from solid to liquid under mild heating facilitates the uniform dispersion and complete surface coverage of CNMT particles.By neutralizing the residual alkali and extracting Na^(+)from the CNMT lattice,H_(3)BO_(3)forms a multifunctional Na_(2)B_(2)O_(5)-dominated layer on the CNMT surface.This Na_(x)B_(y)O_(z)(NBO)layer plays a positive role in providing low-barrier Na^(+)transport channels,suppressing phase transitions,and minimizing the generation of O_(2)/CO_(2)gases and resistive byproducts.As a result,at a charge cutoff voltage of 4.5 V,the NBO-coated CNMT delivers a high discharge capacity of 149,1 mAh g^(-1)at 10 mA g^(-1)and exhibits excellent cycling stability at 100 mA g^(-1)over 200 cycles with a higher capacity retention than that of pristine CNMT(86,4%vs,62.1%).This study highlights the effectiveness of surface modification using lowmelting-point solid acids,with potential applications for other layered oxide cathode materials to achieve stable high-voltage cycling.This proposed strategy opens new avenues for the construction of highquality coatings for high-voltage layered oxide cathodes in SIBs.
基金supported by the National Natural Science Foundation of China(Nos.U2037601 and 51821001)Major Scientific and Technological Innovation Projects in Luoyang(No.2201029A)the Research Program of Joint Research Center of Advanced Spaceflight Technologies(Nos.USCAST2020–14 and USCAST2020–31).
文摘Surface oxide layers play a significant role in forming secondary oxidation inclusions during the casting process.In this study,three typical Mg-RE alloys(Mg-3Nd(NZ30K),Mg-3Nd-3Gd(EV33)and Mg-3Nd-4Y(WE43A))are selected.Their surface oxide layers formed during the solidification are characterized in detail,and the corresponding oxidation mechanisms are discussed.The results reveal that RE elements obviously influence the characteristics of surface oxide layers,which depends on their ability to purify the formed MgO in the melt via the reaction(2RE+3MgO=3Mg+RE_(2)O_(3)).On the one hand,as Nd and Gd do not easily displace MgO already formed in the melt,the loose oxide layers in NZ30K and EV33 alloys are mainly composed of MgO matrix with embedded RE-rich oxide particles.On the other hand,due to the strong ability of Y to purify MgO in the melt,the oxide layer of WE43A alloy becomes a denser and thinner Y_(2)O_(3) oxide layer.Note that the differences in surface oxide layers well explain the different secondary inclusions that occur in three typical Mg-RE alloys during the casting process.
基金supported by the National Research Foundation of Korea funded by the Ministry of Science and ICT of Korea(RS-2024-00408156)。
文摘Mn-based layered oxides are widely recognized as cathode materials for potassium-ion batteries(KIBs)due to their high specific capacity derived from their low molar mass.However,the structural instability caused by the Jahn-Teller effect of Mn^(3+)and the large ionic radius of K+results in poor electrochemical performance.Herein,we propose an effective structural stabilization strategy for P2-type Mn-based layered oxide cathodes of KIBs through Li-incorporation into the transition metal layer.Using the firstprinciples calculations and experiments,we demonstrate that the P2-K_(0.48)[Li_(0.1)Mn_(0.9)]O_(2)(P2-KLMO)delivers improved electrochemical performance,specific capacity and average discharge voltage of~124.4 m A h g^(-1)and~2.7 V(vs.K^(+)/K)at 0.05C(1C=260 mA g^(-1)),outperforming P2-K_(0.5)MnO_(2).Operando X-ray diffraction analysis confirms the P2-OP4 phase transition and Mn^(3+)-induced Jahn-Teller distortion are significantly suppressed in P2-KLMO.These improvements are attributed to the lithium introduction into transition metal layers,leading to strengthened structural stability and enhanced K+diffusion kinetics.Moreover,synthetic accessibility through the conventional solid-state method provides an additional advantage for practical application of Li-incorporated Mn-based P2-type cathodes in KIBs.We believe our study offers a simple yet effective strategy for designing highperformance and practical cathode materials for KIBs.
基金Korea Institute of Science and Technology,Grant/Award Number:2E33270National Research Foundation of Korea,Grant/Award Number:2020M3H4A3081889。
文摘Sodium-ion batteries(SIBs)employ P2-type layered transition metal oxides as promising cathode materials,primarily due to their abundant natural reserves and environmentally friendly characteristics.However,structural instability and complex phase transitions during electrochemical cycling pose significant challenges to their practical applications.Employing cation substitution serves as a straightforward yet effective strategy for stabilizing the structure and improving the kinetics of the active material.In this study,we introduce a Ni-rich honeycomb-layered Na_(2+x)Ni_(2)TeO_(6)(NNTO)cathode material with variable sodium content(x=0,0.03,0.05,0.10).Physicochemical characterizations reveal that excess sodium content at the atomic scale modifies the surface and suppresses phase transitions,while preserving the crystal structure.This results in enhanced cyclic performance and improved electrochemical kinetics at room temperature.Furthermore,we investigate the performance of the NNTO cathode material containing 10%excess sodium at a relatively high temperature of 60℃,where it exhibits 71.6%capacity retention compared to 60%for the pristine.Overall,our results confirm that a preconstructed surface layer(induced by excess sodium)effectively safeguards the Ni-based cathode material from surface degradation and phase transitions during the electrochemical processes,thus exhibiting superior capacity retention relative to the pristine NNTO cathode.This study of the correlation between structure and performance can potentially be applied to the commercialization of SIBs.
基金supported by the National Natural Science Foundation of China(52272295,52071137,51977071,51802040,and 21802020)the Science and Technology Innovation Program of Hunan Province(2021RC3066 and 2021RC3067)+2 种基金the Natural Science Foundation of Hunan Province(2020JJ3004 and 2020JJ4192)Graduate Research Innovation Project of Hunan Province(CX20240456 and CX20240405)N.Zhang and X.Xie also acknowledge the financial support of the Fundamental Research Funds for the Central。
文摘P2-type layered oxide Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)(NM)is a promising cathode material for sodium-ion batteries(SIBs).However,the severe irreversible phase transition,sluggish Na+diffusion kinetics,and interfacial side reactions at high-voltage result in grievous capacity degradation and inferior electrochemical performance.Herein,a dual-function strategy of entropy tuning and artificial cathode electrolyte interface(CEI)layer construction is reported to generate a novel P2-type medium-entropy Na_(0.75)Li_(0.1)Mg_(0.05)Ni_(0.18)Mn_(0.66)Ta_(0.01)O_(2)with NaTaO_(3)surface modification(LMNMT)to address the aforementioned issues.In situ X-ray diffraction reveals that LMNMT exhibits a near zero-strain phase transition with a volume change of only 1.4%,which is significantly lower than that of NM(20.9%),indicating that entropy tuning effectively suppresses irreversible phase transitions and enhances ion diffusion.Kinetic analysis and post-cycling interfacial characterization further confirm that the artificial CEI layer promotes the formation of a stable,thin NaF-rich CEI and reduces interfacial side reactions,thereby further enhancing ion transport kinetics and surface/interface stability.Consequently,the LMNMT electrode exhibits outstanding rate capability(46 mA h g^(−1)at 20 C)and cycling stability(89.5%capacity retention after 200 cycles at 2 C)within the voltage range of 2–4.35 V.The LMNMT also exhibits superior all-climate performance and air stability.This study provides a novel path for the design of high-voltage cathode materials for SIBs.
基金National Key Research and Development Program of China,Grant/Award Number:2023YFB2406100Yibin‘Jie Bang Gua Shuai’,Grant/Award Number:2022JB003National Natural Science Foundation of China,Grant/Award Number:52172234。
文摘The O3-type layered cathode with high Ni content has attracted much attention because of its high capacity and simple synthesis process.However,surface side reaction and O3-P3 phase transitions would occur during Na+insertion/extraction,resulting in unsatisfying electrochemical performance.Herein,O3-Na[Ni_(0.6)Co_(0.2)Mn_(0.2)]O_(2)(NNCM622)cathode is modified by a NaTiOx coating layer in a wet chemistry method,which reduces the parasitic reaction and facilitates Na+migration.Simultaneously,the partially doped Ti improves structural stability by restraining the irreversible multiple-phase transition.As a result,the modified NNCM622 cathode obtains a high specific capacity of 143.4 mAh g^(−1)and an improved capacity retention of 69%after 300 cycles.Our work offers new prospects for stabilizing the NNCM622 cathode with a feasible coating strategy.
基金financially supported by the National Natural Science Foundation of China(No.52071073,52177208,and 52171202)the Hebei Province“333 talent project”(No.C20221012)+2 种基金the Science and Technology Project of Hebei Education Department(BJK2023005)the Fundamental Research Funds for the Central Universities(2024GFZD002)the Natural Science Foundation of Hebei Province(E2024501015)。
文摘O3-type layered oxide cathodes for sodium-ion batteries are promising owing to high theoretical capacity and broad temperature adaptability,yet hindered by structural degradation and sluggish Na^(+)diffusion kinetics.Herein,we present a sodium-deficient high-entropy layered oxide cathode(Na_(0.85)Ni_(0.3)Mn_(0.3)Fe_(0.1)Co_(0.15)Ti_(0.1)Cu_(0.05)B_(0.02)O_(2),denoted as Na0.85-HEO),combining sodium content optimization and high-entropy composition design.Incorporating six transition metals and light element boron creates a unique high-entropy configuration,effectively mitigating local lattice distortion and internal strain through chemical disorder effects,thereby enabling highly reversible phase transitions(O3-P3-O3)and smaller volume change(0.6A^(3))during the initial cycle.The sodium-deficient high-entropy design effectively increases the sodium interlayer spacing to 0.322 nm,facilitating the Na^(+)diffusion kinetics.Moreover,this high-entropy strategy enables the cathode to have a completely solid solution charge curve and significantly reduces the proportion of(O_(2))^(n-),thereby suppressing gas release during the cycling process.The resultant cathode demonstrates exceptional cyclability(80% capacity retention after 400 cycles at 100 mA g^(-1)in a full cell),and remarkable low-temperature performance(108.6 mAh g^(-1)at -40℃).This work guides the design of high-entropy electrode materials with tailored ionic transport channels for extreme-temperature energy storage applications.
基金National Key Research and Development Program of China,Grant/Award Number:2022YFB2502000National Natural Science Foundation of China,Grant/Award Number:52207244。
文摘In the realm of sodium-ion batteries(SIBs),Mn-based layered oxide cathodes have garnered considerable attention owing to their anionic redox reactions(ARRs).Compared to other types of popular sodium-ion cathodes,Mn-based layered oxide cathodes with ARRs exhibit outstanding specific capacity and energy density,making them promising for SIB applications.However,these cathodes still face some scientific challenges that need to be addressed.This review systematically summarizes the composition,structure,oxygen-redox mechanism,and performance of various types of Mn-based cathodes with ARRs,as well as the main scientific challenges they face,including sluggish ion diffusion,cationic migration,O_(2) release,and element dissolution.Currently,to resolve these challenges,efforts mainly focus on six aspects:synthesis methods,structural design,doped modification,electrolyte design,and surface engineering.Finally,this review provides new insights for future direction,encompassing both fundamental research,such as novel cathode types,interface optimization,and interdisciplinary research,and considerations from an industrialization perspective,including scalability,stability,and safety.
基金supported by the State Grid Corporation Science and Technology Project(No.5419-202158503A-0-5-ZN)。
文摘The detrimental phase transformations of sodium layered transition metal oxides(Na_(x)TMO_(2))during desodiation/sodiation seriously suppress their practical applications for sodium ion batteries(SIBs).Undoubtedly,comprehensively investigating of the dynamic crystal structure evolutions of Na_(x)TMO_(2)associating with Na ions extraction/intercalation and then deeply understanding of the relationships between electrochemical performances and phase structures drawing support from advanced characterization techniques are indispensable.In-situ high-energy X-ray diffraction(HEXRD),a powerful technology to distinguish the crystal structure of electrode materials,has been widely used to identify the phase evolutions of Na_(x)TMO_(2)and then profoundly revealed the electrochemical reaction processes.In this review,we begin with the descriptions of synchrotron characterization techniques and then present the advantages of synchrotron X-ray diffraction(XRD)over conventional XRD in detail.The optimizations of structural stability and electrochemical properties for P2-,O3-,and P2/O3-type Na_(x)TMO_(2)cathodes through single/dual-site substitution,high-entropy design,phase composition regulation,and surface engineering are summarized.The dynamic crystal structure evolutions of Na_(x)TMO_(2)polytypes during Na ion extraction/intercalation as well as corresponding structural enhancement mechanisms characterizing by means of HEXRD are concluded.The interior relationships between structure/component of Na_(x)TMO_(2)polytypes and their electrochemical properties are discussed.Finally,we look forward the research directions and issues in the route to improve the electrochemical properties of Na_(x)TMO_(2)cathodes for SIBs in the future and the combined utilizations of multiple characterization techniques.This review will provide significant guidelines for rational designs of high-performance Na_(x)TMO_(2)cathodes.
基金supported partially by projects of National Natural Science Foundation of China (Nos. 52272200, 51972110, 52102245, 52102203 and 52072121)State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources (Nos. LAPS21004, LAPS202114)+5 种基金Beijing Natural Science Foundation (Nos. 2222076, 2222077)Hebei Natural Science Foundation (No. E2022502022)Huaneng Group Headquarters Science and Technology Project (No. HNKJ20-H88)2022 Strategic Research Key Project of Science and Technology Commission of the Ministry of Education, China Postdoctoral Science Foundation (No. 2022M721129)the Fundamental Research Funds for the Central Universities (Nos. 2022MS030, 2021MS028, 2020MS023, 2020MS028)the NCEPU "Double First-Class" Program。
文摘In the field of lithium-ion battery cathode materials, lithium-rich layered oxide materials have garnered significant attention due to their exceptional discharge specific capacity and high operating voltage. However, their limitations in terms of cycling stability and rate capability remain major impediments to their wider application. In this study, an innovative approach was employed by simultaneously utilizing the acidic and oxidative properties of phosphomolybdic acid to generate a spinel structure and in-situ coating of a conductive polymer(polypyrrole) on the surface of lithium-rich layered oxide materials. This strategy aimed to mitigate structural degradation during charge-discharge cycles, enhance the ionic/electronic conductivity, and suppress side reactions. Experimental results demonstrated that after 200 cycles at a current density of 1 C, the modified sample exhibited a discharge specific capacity of 193.4 m Ah/g, with an improved capacity retention rate of 83.3% and a minimal voltage decay of only 0.27 V. These findings provide compelling support for the development and application of next-generation high-performance lithium-ion batteries.
