In the development of Li-ion batteries(LIBs)with high energy/power density,long cycle-life,fast charging,and high safety,an insight into charge transfer reactions is required.Although electrochemical impedance spectro...In the development of Li-ion batteries(LIBs)with high energy/power density,long cycle-life,fast charging,and high safety,an insight into charge transfer reactions is required.Although electrochemical impedance spectroscopy(EIS)is regarded as a powerful diagnosis tool,it is not a direct but an indirect measurement.With respect to this,some critical questions need to be answered:(i)why EIS can reflect the kinetics of charge transfer reactions;(ii)what the inherent logical relationship between impedance models under different physical scenes is;(iii)how charge transfer reactions compete with each other at multiple scales.This work aims at answering these questions via developing a theory framework so as to mitigate the blindness and uncertainty in unveiling charge transfer reactions in LIBs.To systematically answer the above questions,this article is organized into a three-in-one(review,tutorial,and research)type and the following contributions are made:(i)a brief review is given for impedance model development of the LIBs over the past half century;(ii)an open source code toolbox is developed based on the unified impedance model;(iii)the competive mechanisms of charge transfer reactions are unveiled based on the developed EIS-Toolbox@LIB.This work not only clarifies theoretical fundamentals,but also provides an easy-to-use open source code for EIS-Toolbox@LIB to optimize fast charge/discharge,mitigate cycle aging,and improve energy/power density.展开更多
Fluorinated carbons CF_xhold the highest theoretical energy density(e.g.,2180 W h kg^(-1)when x=1)among all cathode materials of lithium primary batteries.However,the low conductivity and severe polarization limit it ...Fluorinated carbons CF_xhold the highest theoretical energy density(e.g.,2180 W h kg^(-1)when x=1)among all cathode materials of lithium primary batteries.However,the low conductivity and severe polarization limit it to achieve its theory.In this study,we design a new electrolyte,namely 1 M LiBF_(4)DMSO:DOL(1:9 vol.),achieving a high energy density in Li/CF_xprimary cells.The DMSO with a small molecular size and high donor number successfully solvates Li^(+)into a defined Li^(+)-solvation structure.Such solvated Li^(+)can intercalate into the large-spacing carbon layers and achieve an improved capacity.Consequently,when discharged to 1.0 V,the CF_(1.12)cathode demonstrates a specific capacity of 1944 m A h g^(-1)with a specific energy density of 3793 W h kg^(-1).This strategy demonstrates that designing the electrolyte is powerful in improving the electrochemical performance of CF_(x) cathode.展开更多
In application,lithium-ion cells undergo expansion during cycling.The mechanical behavior and the impact of external stress on lithium-ion battery are important in vehicle application.In this work,18 Ah high power com...In application,lithium-ion cells undergo expansion during cycling.The mechanical behavior and the impact of external stress on lithium-ion battery are important in vehicle application.In this work,18 Ah high power commercial cell with Li Ni_(0.5)Co_(0.2)Mn_(0.3)O_(2)/graphite electrode were adopted.A commercial compress machine was applied to monitor the mechanical characteristics under different stage of charge(SOC),lifetime and initial external force.The dynamic and steady force was obtained and the results show that the dynamic force increases as the SOC increasing,obviously.During the lifetime with high power driving mode,different external force is shown to have a great impact on the long-term cell performance,with higher stresses result in higher capacity decay rates and faster impedance increases.A proper initial external force(900 N)provides lower impedance increasing.Postmortem analysis of the cells with2000 N initial force suggests a close correlation between electrochemistry and mechanics in which higher initial force leads to higher direct current internal resistance(DCIR)increase rate.In addition,for the cell with higher external force,deformation of the cathode and thicker solid electrolyte interface(SEI)film on the surface of anode and separator are observed.Porosity reduction and closure was also verified after cycles which is an obstacle to the lithium ion transferring.The largest cause of the observed capacity decline was the loss of active lithium through autopsy analysis.In addition,for the cell with higher external force,deformation of the cathode and thicker SEI film on the surface of anode and separator are observed.Porosity reduction and closure was also verified after cycles which is an obstacle to the lithium ion transferring.The largest cause of the observed capacity decline was the loss of active lithium through autopsy analysis.展开更多
Layered cathode materials have been successfully commercialized and applied to electric vehicles.To further improve improve the energy density of these marterials is still the main efforts in the market.Therefore,deve...Layered cathode materials have been successfully commercialized and applied to electric vehicles.To further improve improve the energy density of these marterials is still the main efforts in the market.Therefore,developing high-voltage LiNi_(x)Co_(y)Mn_(z)O_(2)(x+y+z=1,NCM)to achieve high energy density is particularly important.However,under high voltage cycling,NCM often exhibits rapid capacity degradation,which can be attributed to oxygen release,structural phase transition and particle cracking.In this work,the representative single-crystal LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)(NCM523)was studied under various high charge cut-off voltages.Analysis by x-ray diffraction(XRD),transmission electron microscope(TEM)and electron back scatter diffraction(EBSD)measurements indicated that the rock-salt phase is formed on the surface of the particles after high voltage cycling,which is responsible for the increase of impedance and the rapid decay of capacity.Therefore,inhibiting the formation of rock-salt phase is believed an effective strategy to address the failure of NCM under high voltages.These findings provide effective guidance for the development of high-voltage NCM.展开更多
Li-rich layered oxide(LRLO)cathodes have been regarded as promising candidates for next-generation Li-ion batteries due to their exceptionally high energy density,which combines cationic and anionic redox activities.H...Li-rich layered oxide(LRLO)cathodes have been regarded as promising candidates for next-generation Li-ion batteries due to their exceptionally high energy density,which combines cationic and anionic redox activities.However,continuous voltage decay during cycling remains the primary obstacle for practical applications,which has yet to be fundamentally addressed.It is widely acknowledged that voltage decay originates from the irreversible migration of transition metal ions,which usually further exacerbates structural evolution and aggravates the irreversible oxygen redox reactions.Recently,constructing O2-type structure has been considered one of the most promising approaches for inhibiting voltage decay.In this review,the relationship between voltage decay and structural evolution is systematically elucidated.Strategies to suppress voltage decay are systematically summarized.Additionally,the design of O2-type structure and the corresponding mechanism of suppressing voltage decay are comprehensively discussed.Unfortunately,the reported O2-type LRLO cathodes still exhibit partially disordered structure with extended cycles.Herein,the factors that may cause the irreversible transition metal migrations in O2-type LRLO materials are also explored,while the perspectives and challenges for designing high-performance O2-type LRLO cathodes without voltage decay are proposed.展开更多
Lithium(Li)metal is the most potential anode material for the next-generation high-energy rechargeable batteries.However,intrinsic surface unevenness and‘hostless’nature of Li metal induces infinite volume effect an...Lithium(Li)metal is the most potential anode material for the next-generation high-energy rechargeable batteries.However,intrinsic surface unevenness and‘hostless’nature of Li metal induces infinite volume effect and uncontrollable dendrite growth.Herein,we design the in-situ grown lithiophilic Ni_(2)P nanoarrays inside nickel foam(PNF).Uniform Ni_(2)P nanoarrays coating presents a very low nucleation overpotential,which induces the homogeneous Li deposition in the entire spaces of three-dimensional(3D)metal framework.Specifically,the lithiophilic Ni_(2)P nanoarrays possess characteristics of electrical conductivity and structural stability,which have almost no expansion and damage during repeating Li plating/stripping.Therefore,they chronically inhibit the growth of Li dendrites.This results in an outstanding Coulombic efficiency(CE)of 98% at 3 mA cm^(-2) and an ultra long cycling life over 2000 cycles with a low overpotential.Consequently,the PNF-Li||LiFePO_(4) battery maintains a capacity retention of 95.3% with a stable CE of 99.9% over 500 cycles at 2 C.展开更多
The energy density of commercial lithium(Li)ion batteries with graphite anode is reaching the limit.It is believed that directly utilizing Li metal as anode without a host could enhance the battery’s energy density t...The energy density of commercial lithium(Li)ion batteries with graphite anode is reaching the limit.It is believed that directly utilizing Li metal as anode without a host could enhance the battery’s energy density to the maximum extent.However,the poor reversibility and infinite volume change of Li metal hinder the realistic implementation of Li metal in battery community.Herein,a commercially viable hybrid Li-ion/metal battery is realized by a coordinated strategy of symbiotic anode and prelithiated cathode.To be specific,a scalable template-removal method is developed to fabricate the porous graphite layer(PGL),which acts as a symbiotic host for Li ion intercalation and subsequent Li metal deposition due to the enhanced lithiophilicity and sufficient ion-conducting pathways.A continuous dissolution-deintercalation mechanism during delithiation process further ensures the elimination of dead Li.As a result,when the excess plating Li reaches 30%,the PGL could deliver an ultrahigh average Coulombic efficiency of 99.5% for 180 cycles with a capacity of 2.48 m Ah cm^(-2) in traditional carbonate electrolyte.Meanwhile,an air-stable recrystallized lithium oxalate with high specific capacity(514.3 m Ah g^(-1))and moderate operating potential(4.7-5.0 V)is introduced as a sacrificial cathode to compensate the initial loss and provide Li source for subsequent cycles.Based on the prelithiated cathode and initial Li-free symbiotic anode,under a practical-level3 m Ah capacity,the assembled hybrid Li-ion/metal full cell with a P/N ratio(capacity ratio of Li Ni_(0.8)Co_(0.1)Mn_(0.1)O_(2) to graphite)of 1.3exhibits significantly improved capacity retention after 300 cycles,indicating its great potential for high-energy-density Li batteries.展开更多
Energy storage is an ever-growing global concern due to increased energy needs and resource exhaustion.Sodium-ion batteries(SIBs)have called increasing attention and achieved substantial progress in recent years owing...Energy storage is an ever-growing global concern due to increased energy needs and resource exhaustion.Sodium-ion batteries(SIBs)have called increasing attention and achieved substantial progress in recent years owing to the abundance and even distribution of Na resources in the crust,and the predicted low cost of the technique.Nevertheless,SIBs still face challenges like lower energy density and inferior cycling stability compared to mature lithium-ion batteries(LIBs).Enhancing the electrochemical performance of SIBs requires an in-deep and comprehensive understanding of the improvement strategies and the underlying reaction mechanism elucidated by in situ techniques.In this review,commonly applied in situ techniques,for instance,transmission electron microscopy(TEM),Raman spectroscopy,X-ray diffraction(XRD),and X-ray absorption near-edge structure(XANES),and their applications on the representative cathode and anode materials with selected samples are summarized.We discuss the merits and demerits of each type of material,strategies to enhance their electrochemical performance,and the applications of in situ characterizations of them during the de/sodiation process to reveal the underlying reaction mechanism for performance improvement.We aim to elucidate the composition/structure-per formance relationship to provide guidelines for rational design and preparation of electrode materials toward high electrochemical performance.展开更多
Wandering on the shore of the Sandu Bay,looking at the blue ocean and the green mountains,a question comes to mind:How can we meet humans’energy demand while minimizing its effect on the environment?In other words,ho...Wandering on the shore of the Sandu Bay,looking at the blue ocean and the green mountains,a question comes to mind:How can we meet humans’energy demand while minimizing its effect on the environment?In other words,how can we ensure a carbon-neutral world in the near future?展开更多
During the last decade,the rapid development of lithium-ion battery(LIB)energy storage systems has provided significant support for the efficient operation of renewable energy stations.In the coming years,the service ...During the last decade,the rapid development of lithium-ion battery(LIB)energy storage systems has provided significant support for the efficient operation of renewable energy stations.In the coming years,the service life demand of energy storage systems will be further increased to 30 years from the current 20 years on the basis of the equivalent service life of renewable energy stations.However,the life of the present LIB is far from meeting such high demand.Therefore,research on the next-generation LIB with ultra-long service life is imminent.Prelithiation technology has been widely studied as an important means to compensate for the initial coulombic efficiency loss and improve the service life of LIBs.This review systematically summarized the different prelithiation methods from anode and cathode electrodes.Moreover,the large-scale industrialization challenge and the possibility of the existing prelithiation technology are analyzed,based on three key parameters:industry compatibility,prelithiation efficiency,and energy density.Finally,the future trends of improvement in LIB performance by other overlithiated cathode materials are presented,which gives a reference for subsequent research.展开更多
Fluorinated carbons(CFx)have been widely applied as lithium primary batteries due to their ultra-high energy density.It will be a great promise if CFx can be rechargeable.In this study,we rationally tune the C-F bond ...Fluorinated carbons(CFx)have been widely applied as lithium primary batteries due to their ultra-high energy density.It will be a great promise if CFx can be rechargeable.In this study,we rationally tune the C-F bond strength for the alkaline intercalated CFx via importing an electronegative weaker element K instead of Li.It forms a ternary phase K_(x)FC instead of two phases(LiF+C)in lithium-ion batteries.Meanwhile,we choose a large layer distance and more defects CFx,namely fluorinated soft carbon,to accommodate K.Thus,we enable CFx rechargeable as a potassium-ion battery cathode.In detail fluorinated soft carbon CF_(1.01) presents a reversible specific capacity of 339 mA h g^(-1)(797 Wh kg^(-1))in the 2nd cycle and maintains 330 mA h g^(-1)(726 Wh kg^(-1))in the 15th cycle.This study reveals the importance of tuning chemical bond stability using different alkaline ions to endow batteries with rechargeability.This work provides good references for focusing on developing reversible electrode materials from popular primary cell configurations.展开更多
The feasibility for natural graphite(NG)to replace artificial graphite(AG)in organic electrolytes with different additives are investigated.Although the strong film-forming additives contributes to form robust solid e...The feasibility for natural graphite(NG)to replace artificial graphite(AG)in organic electrolytes with different additives are investigated.Although the strong film-forming additives contributes to form robust solid electrolyte interphase(SEI)film on graphite particle surface,great differences in gas evolution,lithium inventory loss and other side reactions are observed.Lithium bis(oxalato)borate(Li BOB)and fluoroethylene carbonate(FEC)are found more effective and the combination shows to be more promising.In the optimized electrolyte,natural graphite anode exhibits excellent long-term cycling capability.After 800 cycles at high temperature,the capacity retention is comparable to that using artificial graphite.The mechanisms for the capacity-fading of the full cells with AG and NG anode are investigated by ICP,SEM and polarization studies.The results shows that NG electrode consumes more active lithium due to the rough surface and larger volume expansion.The rapid capacity-fading in the initial 100 cycles is related to the instability of the SEI film aroused from large volume expansion.The systematic analysis is inspiriting for the development of high performance lithium ion batteries with reduced cost.展开更多
A new size-dependent axially functionally graded(AFG) micro-beam model is established with the application of a reformulated strain gradient elasticity theory(RSGET). The new micro-beam model incorporates the strain g...A new size-dependent axially functionally graded(AFG) micro-beam model is established with the application of a reformulated strain gradient elasticity theory(RSGET). The new micro-beam model incorporates the strain gradient, velocity gradient,and couple stress effects, and accounts for the material variation along the axial direction of the two-component functionally graded beam. The governing equations and complete boundary conditions of the AFG beam are derived based on Hamilton's principle. The correctness of the current model is verified by comparing the static behavior results of the current model and the finite element model(FEM) at the micro-scale. The influence of material inhomogeneity and size effect on the static and dynamic responses of the AFG beam is studied. The numerical results show that the static and vibration responses predicted by the newly developed model are different from those based on the classical model at the micro-scale. The new model can be applied not only in the optimization of micro acoustic wave devices but also in the design of AFG micro-sensors and micro-actuators.展开更多
Severe lithium(Li)dendrite growth caused by the uneven overpotential deposition is a formidable challenge for high energy density Li metal batteries(LMBs).Herein,we investigate a synergetic interfacial kinetic to regu...Severe lithium(Li)dendrite growth caused by the uneven overpotential deposition is a formidable challenge for high energy density Li metal batteries(LMBs).Herein,we investigate a synergetic interfacial kinetic to regulate Li deposition behavior and stabilize Li metal anode.Through constructing Li alloying matrix with a bi-functional silver(Ag)-Li_(3)N blended interface,fast Li^(+)conductivity and high Li affinity can be achieved simultaneously,resulting in both decreased Li nucleation and mass transfercontrolled overpotentials.Beyond these properties,a more important feature is demonstrated herein;that is,the inward diffusion depth of the Li adatoms inside of the Ag site can be restricted by the Li^(+)solvation structure in a highly coordinating environment.The latter feature can ensure the durability of the operational Ag sites,thereby elongating the Li protection ability of the Ag-Li_(3)N interface greatly.This work provides a deep insight into the synergetic effect of functional alloying structure and Li^(+)solvation mediated interfacial kinetic on Li metal protection.展开更多
LiMn_(y)Fe_(1-y)PO_(4) is considered a promising cathode material for next-generation lithium-ion batteries(LIBs) due to its high energy density and low cost. Its energy density degradation is often ascribed to the ca...LiMn_(y)Fe_(1-y)PO_(4) is considered a promising cathode material for next-generation lithium-ion batteries(LIBs) due to its high energy density and low cost. Its energy density degradation is often ascribed to the capacity loss during cycling. However, in this study, we find that the energy density degradation mainly roots in voltage decay. We have synthesized a series of LiMn_(y)Fe_(1-y)PO_(4) /C(0.5 ≤ y ≤ 0.8) and find this voltage decay is correlated with the Mn content. A high amount Mn leads to a heavier voltage decay.In-situ X-ray diffraction(XRD) and high-resolution transmission electron microscopy(HRTEM) reveal the nature of this effect, which show a mismatch along the b-axis of-2.68%(charge) and +3.4%(discharge), a volume misfit of-4.41%(charge) and +4.54%(discharge) between Li_(x)Mn_(y)Fe_(1-y)PO_(4) and Mn_(y)Fe_(1-y)PO_(4) during phase transitions. The resultant misfit strains during Li+insertion compared to extraction result in structural degradations, such as amorphization and impurity(Mn F3) accumulation after cycling. The voltage decay can be alleviated by kinetic relaxations and recovered by a wild reannealing. This work demonstrates effective strategies to improve the energy density and cycling performance of LiMn_(y)Fe_(1-y)PO_(4) /C,providing good references for other LIB cathodes, such as the Li-rich cathodes.展开更多
Lithium (Li) metal is considered as one of the most promising anode materials to build next-generation high-energy–density batteries. Nonetheless, dendritic Li deposition has dramatically hindered the practical appli...Lithium (Li) metal is considered as one of the most promising anode materials to build next-generation high-energy–density batteries. Nonetheless, dendritic Li deposition has dramatically hindered the practical applications of Li metal batteries (LMBs). Uniformizing Li deposition is a prerequisite to achieve safe and practical LMBs. Herein, an underpotential deposition (UPD) process is first proposed to alter the kinetic and uniformity of Li deposition morphology. Based on the strong interaction between the Li adatoms and manganese (Mn) based substrate, a competition between the UPD and bulk Li deposition is observed, on which the predominance of the UPD scenario tends to uniformize Li nucleation and deposition by the surface coverage of Li monolayers at potentials that are more positive than the Nernst potential of Li metal. Inspired by this process, an advanced hybrid Mn-graphene oxide structure is developed for Li protection, not only enabling dendrite-free Li anodes for high-capacity and -current density cycling, but also improving the interfacial kinetic of Li metal anodes at subzero temperatures, showing potential applicability in low temperature conditions.展开更多
Rechargeable all-solid-state batteries(ASSBs)are considered to be the next generation of devices for electrochemical energy storage.The development of solid-state electrolytes(SSEs)is one of the most crucial subjects ...Rechargeable all-solid-state batteries(ASSBs)are considered to be the next generation of devices for electrochemical energy storage.The development of solid-state electrolytes(SSEs)is one of the most crucial subjects in the field of energy storage chemistry.The newly emerging halide SSEs have recently been intensively studied for application in ASSBs due to their favorable combination of high ionic conductivity,exceptional chemical and electrochemical stability,and superior mechanical deformability.In this review,a critical overview of the development,synthesis,chemical stability and remaining challenges of halide SSEs is given.The design strategies for optimizing the ionic conductivity of halide SSEs,such as element substitution and crystal structure design,are summarized in detail.Moreover,the associated chemical stability issues in terms of solvent compatibility,humid air stability and corresponding degradation mechanisms are discussed.In particular,advanced in situ/operando characterization techniques applied to halide-based ASSBs are highlighted.In addition,a comprehensive understanding of the interface issues,cost issues,and scalable processing challenges faced by halide-based ASSBs for practical application is provided.Finally,future perspectives on how to design high-performance electrode/electrolyte materials are given,which are instructive for guiding the development of halide-based ASSBs for energy conversion and storage.展开更多
Anti-perovskite solid-state electrolyte Li_(2)OHCl usually exhibits orthorhombic phase and low ionic conductivity at room temperature.However,its ionic conductivity increases greatly when the temperature is up to 40℃...Anti-perovskite solid-state electrolyte Li_(2)OHCl usually exhibits orthorhombic phase and low ionic conductivity at room temperature.However,its ionic conductivity increases greatly when the temperature is up to 40℃,while it goes through an orthorhombic-to-cubic phase transition.The cubic Li_(2)OHCl with high ionic conductivity is stabilized at room temperature and even lower temperature about 10℃ by a simple synthesis method of wet mechanical milling.The cubic Li_(2)OHCl prepared by this method performs an ionic conductivity of 4.27×10^(-6) S/cm at room temperature,about one order of magnitude higher than that of the orthorhombic Li_(2)OHCl.The phase-transition temperature is decreased to around 10℃.Moreover,it can still remain cubic phase after heat treatment at 210℃.This work delivers a huge potential of fabricating high ionic conductivity phase antiperovskite solid-state electrolyte materials by wet mechanical milling.展开更多
I first came to China for work in 2012 and now is the chief technology officer of Ningde Contemporary Amperex Technology Co.,Limited(hereinafter referred to as CATL).During my more than seven years of working in China...I first came to China for work in 2012 and now is the chief technology officer of Ningde Contemporary Amperex Technology Co.,Limited(hereinafter referred to as CATL).During my more than seven years of working in China,I have personally experienced the rapid development of China’s new energy vehicles,and witnessed the whole process of growing up as a wellknown supplier of power batteries of CATL.展开更多
Lithium carbonate （Li2CO3） is very common in various types of lithium （Li） batteries. As an insulating by-product of the oxygen reduction reaction on the cathode of a Li-air battery, it cannot be decomposed below ...Lithium carbonate （Li2CO3） is very common in various types of lithium （Li） batteries. As an insulating by-product of the oxygen reduction reaction on the cathode of a Li-air battery, it cannot be decomposed below 4.75 V （vs. Li＋/Li） during recharge and leads to a large polarization, low coulombic efficiency, and low energy conversion efficiency of the battery. On the other hand, more than 10% of the Li ions from the cathode material are consumed during chemical formation of a Li-ion battery, resulting in low coulombic efficiency and/or energy density. Consequently, lithium compensation becomes essential to realize Li-ion batteries with a higher energy density and longer cycle life. Therefore, reducing the oxidation potential of Li2CO3 is significantly important. To address these issues, we show that the addition of nanoscaled LiCoO2 can effectively lower this potential to 4.25 V. On the basis of physical characterization and electrochemical evaluation, we propose the oxidization mechanism of Li2CO3. These findings will help to decrease the polarization of Li-air batteries and provide an effective strategy for efficient Li compensation for Li-ion batteries, which can significantly improve their energy density and increase their energy conversion efficiency and cycle life.展开更多
基金the financial support from the National Science Foundation of China(22078190)the National Key R&D Plan of China(2020YFB1505802)。
文摘In the development of Li-ion batteries(LIBs)with high energy/power density,long cycle-life,fast charging,and high safety,an insight into charge transfer reactions is required.Although electrochemical impedance spectroscopy(EIS)is regarded as a powerful diagnosis tool,it is not a direct but an indirect measurement.With respect to this,some critical questions need to be answered:(i)why EIS can reflect the kinetics of charge transfer reactions;(ii)what the inherent logical relationship between impedance models under different physical scenes is;(iii)how charge transfer reactions compete with each other at multiple scales.This work aims at answering these questions via developing a theory framework so as to mitigate the blindness and uncertainty in unveiling charge transfer reactions in LIBs.To systematically answer the above questions,this article is organized into a three-in-one(review,tutorial,and research)type and the following contributions are made:(i)a brief review is given for impedance model development of the LIBs over the past half century;(ii)an open source code toolbox is developed based on the unified impedance model;(iii)the competive mechanisms of charge transfer reactions are unveiled based on the developed EIS-Toolbox@LIB.This work not only clarifies theoretical fundamentals,but also provides an easy-to-use open source code for EIS-Toolbox@LIB to optimize fast charge/discharge,mitigate cycle aging,and improve energy/power density.
基金supported by the National Natural Science Foundation of China(Nos.52072061,22322903,12174162)the Natural Science Foundation of Sichuan,China(No.2023NSFSC1914)21C Innovation Laboratory,Contemporary Amperex Technology Ltd.by project No.21C-OP-202103。
文摘Fluorinated carbons CF_xhold the highest theoretical energy density(e.g.,2180 W h kg^(-1)when x=1)among all cathode materials of lithium primary batteries.However,the low conductivity and severe polarization limit it to achieve its theory.In this study,we design a new electrolyte,namely 1 M LiBF_(4)DMSO:DOL(1:9 vol.),achieving a high energy density in Li/CF_xprimary cells.The DMSO with a small molecular size and high donor number successfully solvates Li^(+)into a defined Li^(+)-solvation structure.Such solvated Li^(+)can intercalate into the large-spacing carbon layers and achieve an improved capacity.Consequently,when discharged to 1.0 V,the CF_(1.12)cathode demonstrates a specific capacity of 1944 m A h g^(-1)with a specific energy density of 3793 W h kg^(-1).This strategy demonstrates that designing the electrolyte is powerful in improving the electrochemical performance of CF_(x) cathode.
基金financially supported by the National Key Research&Development Program of China(2016YFB0100400)the National Natural Science Foundation of China(21875154 and 22179090)。
文摘In application,lithium-ion cells undergo expansion during cycling.The mechanical behavior and the impact of external stress on lithium-ion battery are important in vehicle application.In this work,18 Ah high power commercial cell with Li Ni_(0.5)Co_(0.2)Mn_(0.3)O_(2)/graphite electrode were adopted.A commercial compress machine was applied to monitor the mechanical characteristics under different stage of charge(SOC),lifetime and initial external force.The dynamic and steady force was obtained and the results show that the dynamic force increases as the SOC increasing,obviously.During the lifetime with high power driving mode,different external force is shown to have a great impact on the long-term cell performance,with higher stresses result in higher capacity decay rates and faster impedance increases.A proper initial external force(900 N)provides lower impedance increasing.Postmortem analysis of the cells with2000 N initial force suggests a close correlation between electrochemistry and mechanics in which higher initial force leads to higher direct current internal resistance(DCIR)increase rate.In addition,for the cell with higher external force,deformation of the cathode and thicker solid electrolyte interface(SEI)film on the surface of anode and separator are observed.Porosity reduction and closure was also verified after cycles which is an obstacle to the lithium ion transferring.The largest cause of the observed capacity decline was the loss of active lithium through autopsy analysis.In addition,for the cell with higher external force,deformation of the cathode and thicker SEI film on the surface of anode and separator are observed.Porosity reduction and closure was also verified after cycles which is an obstacle to the lithium ion transferring.The largest cause of the observed capacity decline was the loss of active lithium through autopsy analysis.
文摘Layered cathode materials have been successfully commercialized and applied to electric vehicles.To further improve improve the energy density of these marterials is still the main efforts in the market.Therefore,developing high-voltage LiNi_(x)Co_(y)Mn_(z)O_(2)(x+y+z=1,NCM)to achieve high energy density is particularly important.However,under high voltage cycling,NCM often exhibits rapid capacity degradation,which can be attributed to oxygen release,structural phase transition and particle cracking.In this work,the representative single-crystal LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)(NCM523)was studied under various high charge cut-off voltages.Analysis by x-ray diffraction(XRD),transmission electron microscope(TEM)and electron back scatter diffraction(EBSD)measurements indicated that the rock-salt phase is formed on the surface of the particles after high voltage cycling,which is responsible for the increase of impedance and the rapid decay of capacity.Therefore,inhibiting the formation of rock-salt phase is believed an effective strategy to address the failure of NCM under high voltages.These findings provide effective guidance for the development of high-voltage NCM.
基金funded by the National Natural Science Foundation of China(Grant Nos.22279092 and 5202780089).
文摘Li-rich layered oxide(LRLO)cathodes have been regarded as promising candidates for next-generation Li-ion batteries due to their exceptionally high energy density,which combines cationic and anionic redox activities.However,continuous voltage decay during cycling remains the primary obstacle for practical applications,which has yet to be fundamentally addressed.It is widely acknowledged that voltage decay originates from the irreversible migration of transition metal ions,which usually further exacerbates structural evolution and aggravates the irreversible oxygen redox reactions.Recently,constructing O2-type structure has been considered one of the most promising approaches for inhibiting voltage decay.In this review,the relationship between voltage decay and structural evolution is systematically elucidated.Strategies to suppress voltage decay are systematically summarized.Additionally,the design of O2-type structure and the corresponding mechanism of suppressing voltage decay are comprehensively discussed.Unfortunately,the reported O2-type LRLO cathodes still exhibit partially disordered structure with extended cycles.Herein,the factors that may cause the irreversible transition metal migrations in O2-type LRLO materials are also explored,while the perspectives and challenges for designing high-performance O2-type LRLO cathodes without voltage decay are proposed.
基金financial supported by the National Natural Science Foundation of China(Grant Nos.51874361 and 51904343)the Science and technology program of Hunan Province(2019RS3002)。
文摘Lithium(Li)metal is the most potential anode material for the next-generation high-energy rechargeable batteries.However,intrinsic surface unevenness and‘hostless’nature of Li metal induces infinite volume effect and uncontrollable dendrite growth.Herein,we design the in-situ grown lithiophilic Ni_(2)P nanoarrays inside nickel foam(PNF).Uniform Ni_(2)P nanoarrays coating presents a very low nucleation overpotential,which induces the homogeneous Li deposition in the entire spaces of three-dimensional(3D)metal framework.Specifically,the lithiophilic Ni_(2)P nanoarrays possess characteristics of electrical conductivity and structural stability,which have almost no expansion and damage during repeating Li plating/stripping.Therefore,they chronically inhibit the growth of Li dendrites.This results in an outstanding Coulombic efficiency(CE)of 98% at 3 mA cm^(-2) and an ultra long cycling life over 2000 cycles with a low overpotential.Consequently,the PNF-Li||LiFePO_(4) battery maintains a capacity retention of 95.3% with a stable CE of 99.9% over 500 cycles at 2 C.
基金the support by the Key-Area Research and Development Program of Guangdong Province(No.2020B090919003)the National Nature Science Foundation of China(Nos.51872157 and 52072208)+4 种基金the Shenzhen Technical Plan Project(Nos.JCYJ20170817161753629 and JCYJ20170412170911187)the Special Fund Project for Strategic Emerging Industry Development of Shenzhen(No.20170428145209110)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(No.2017BT01N111)the Support Plan for Shenzhen Manufacturing Innovation Center(No.20200627215553988)the Key projects for core technology research of Dongguan(No.2019622119003)。
文摘The energy density of commercial lithium(Li)ion batteries with graphite anode is reaching the limit.It is believed that directly utilizing Li metal as anode without a host could enhance the battery’s energy density to the maximum extent.However,the poor reversibility and infinite volume change of Li metal hinder the realistic implementation of Li metal in battery community.Herein,a commercially viable hybrid Li-ion/metal battery is realized by a coordinated strategy of symbiotic anode and prelithiated cathode.To be specific,a scalable template-removal method is developed to fabricate the porous graphite layer(PGL),which acts as a symbiotic host for Li ion intercalation and subsequent Li metal deposition due to the enhanced lithiophilicity and sufficient ion-conducting pathways.A continuous dissolution-deintercalation mechanism during delithiation process further ensures the elimination of dead Li.As a result,when the excess plating Li reaches 30%,the PGL could deliver an ultrahigh average Coulombic efficiency of 99.5% for 180 cycles with a capacity of 2.48 m Ah cm^(-2) in traditional carbonate electrolyte.Meanwhile,an air-stable recrystallized lithium oxalate with high specific capacity(514.3 m Ah g^(-1))and moderate operating potential(4.7-5.0 V)is introduced as a sacrificial cathode to compensate the initial loss and provide Li source for subsequent cycles.Based on the prelithiated cathode and initial Li-free symbiotic anode,under a practical-level3 m Ah capacity,the assembled hybrid Li-ion/metal full cell with a P/N ratio(capacity ratio of Li Ni_(0.8)Co_(0.1)Mn_(0.1)O_(2) to graphite)of 1.3exhibits significantly improved capacity retention after 300 cycles,indicating its great potential for high-energy-density Li batteries.
基金supported by the National Natural Science Foundation of China(22005130,21925404,21902137,21991151,and 22021001)the National Key Research and Development Program of China(2019YFA0705400 and 2020YFB1505800)the Natural Science Foundation of Fujian Province of China(2021J01988)。
文摘Energy storage is an ever-growing global concern due to increased energy needs and resource exhaustion.Sodium-ion batteries(SIBs)have called increasing attention and achieved substantial progress in recent years owing to the abundance and even distribution of Na resources in the crust,and the predicted low cost of the technique.Nevertheless,SIBs still face challenges like lower energy density and inferior cycling stability compared to mature lithium-ion batteries(LIBs).Enhancing the electrochemical performance of SIBs requires an in-deep and comprehensive understanding of the improvement strategies and the underlying reaction mechanism elucidated by in situ techniques.In this review,commonly applied in situ techniques,for instance,transmission electron microscopy(TEM),Raman spectroscopy,X-ray diffraction(XRD),and X-ray absorption near-edge structure(XANES),and their applications on the representative cathode and anode materials with selected samples are summarized.We discuss the merits and demerits of each type of material,strategies to enhance their electrochemical performance,and the applications of in situ characterizations of them during the de/sodiation process to reveal the underlying reaction mechanism for performance improvement.We aim to elucidate the composition/structure-per formance relationship to provide guidelines for rational design and preparation of electrode materials toward high electrochemical performance.
基金supported by the National Natural Science Foundation of China(12174162 and 51962010)。
文摘Wandering on the shore of the Sandu Bay,looking at the blue ocean and the green mountains,a question comes to mind:How can we meet humans’energy demand while minimizing its effect on the environment?In other words,how can we ensure a carbon-neutral world in the near future?
基金funded by the National Natural Science Foundation of China(No.U21A20170(X.He))the Ministry of Science and Technology of China(No.2019YFE0100200(X.He)and 2019YFA0705703(L.Wang))the Tsinghua University Initiative Scientific Research Program(No.2019Z02UTY06(X.He)and 2019THFS0132(L.Wang)).The authors also thank Joint Work Plan for Research Projects under the Clean Vehicles Consortium at U.S.and China-Clean Energy Research Center(CERC-CVC2.0,2016-2020)
文摘During the last decade,the rapid development of lithium-ion battery(LIB)energy storage systems has provided significant support for the efficient operation of renewable energy stations.In the coming years,the service life demand of energy storage systems will be further increased to 30 years from the current 20 years on the basis of the equivalent service life of renewable energy stations.However,the life of the present LIB is far from meeting such high demand.Therefore,research on the next-generation LIB with ultra-long service life is imminent.Prelithiation technology has been widely studied as an important means to compensate for the initial coulombic efficiency loss and improve the service life of LIBs.This review systematically summarized the different prelithiation methods from anode and cathode electrodes.Moreover,the large-scale industrialization challenge and the possibility of the existing prelithiation technology are analyzed,based on three key parameters:industry compatibility,prelithiation efficiency,and energy density.Finally,the future trends of improvement in LIB performance by other overlithiated cathode materials are presented,which gives a reference for subsequent research.
基金supported by the National Natural Science Foundation of China(52072061)21C Innovation Laboratory,Contemporary Amperex Technology Ltd.by project No.21C–OP–202103。
文摘Fluorinated carbons(CFx)have been widely applied as lithium primary batteries due to their ultra-high energy density.It will be a great promise if CFx can be rechargeable.In this study,we rationally tune the C-F bond strength for the alkaline intercalated CFx via importing an electronegative weaker element K instead of Li.It forms a ternary phase K_(x)FC instead of two phases(LiF+C)in lithium-ion batteries.Meanwhile,we choose a large layer distance and more defects CFx,namely fluorinated soft carbon,to accommodate K.Thus,we enable CFx rechargeable as a potassium-ion battery cathode.In detail fluorinated soft carbon CF_(1.01) presents a reversible specific capacity of 339 mA h g^(-1)(797 Wh kg^(-1))in the 2nd cycle and maintains 330 mA h g^(-1)(726 Wh kg^(-1))in the 15th cycle.This study reveals the importance of tuning chemical bond stability using different alkaline ions to endow batteries with rechargeability.This work provides good references for focusing on developing reversible electrode materials from popular primary cell configurations.
基金financially supported by the National Key Research and Development Program of China(2016YFB0100400)the National Natural Science Foundation of China(21875154,22179090)。
文摘The feasibility for natural graphite(NG)to replace artificial graphite(AG)in organic electrolytes with different additives are investigated.Although the strong film-forming additives contributes to form robust solid electrolyte interphase(SEI)film on graphite particle surface,great differences in gas evolution,lithium inventory loss and other side reactions are observed.Lithium bis(oxalato)borate(Li BOB)and fluoroethylene carbonate(FEC)are found more effective and the combination shows to be more promising.In the optimized electrolyte,natural graphite anode exhibits excellent long-term cycling capability.After 800 cycles at high temperature,the capacity retention is comparable to that using artificial graphite.The mechanisms for the capacity-fading of the full cells with AG and NG anode are investigated by ICP,SEM and polarization studies.The results shows that NG electrode consumes more active lithium due to the rough surface and larger volume expansion.The rapid capacity-fading in the initial 100 cycles is related to the instability of the SEI film aroused from large volume expansion.The systematic analysis is inspiriting for the development of high performance lithium ion batteries with reduced cost.
基金Project supported by the National Natural Science Foundation of China (No. 12002086)the Fundamental Research Funds for the Central Universities of China (No. 2242022R40040)。
文摘A new size-dependent axially functionally graded(AFG) micro-beam model is established with the application of a reformulated strain gradient elasticity theory(RSGET). The new micro-beam model incorporates the strain gradient, velocity gradient,and couple stress effects, and accounts for the material variation along the axial direction of the two-component functionally graded beam. The governing equations and complete boundary conditions of the AFG beam are derived based on Hamilton's principle. The correctness of the current model is verified by comparing the static behavior results of the current model and the finite element model(FEM) at the micro-scale. The influence of material inhomogeneity and size effect on the static and dynamic responses of the AFG beam is studied. The numerical results show that the static and vibration responses predicted by the newly developed model are different from those based on the classical model at the micro-scale. The new model can be applied not only in the optimization of micro acoustic wave devices but also in the design of AFG micro-sensors and micro-actuators.
基金supported by the 21C Innovation Laboratory,Contemporary Amperex Technology Ltd by project No.21C-OP-202004,the Ningbo S&T Innovation 2025 Major Special Program(Grant No.2018B10061,2018B10087,2019B10044,and 2020Z101)the National Key R&D Program of China(Grant No.2018YFB0905400).
文摘Severe lithium(Li)dendrite growth caused by the uneven overpotential deposition is a formidable challenge for high energy density Li metal batteries(LMBs).Herein,we investigate a synergetic interfacial kinetic to regulate Li deposition behavior and stabilize Li metal anode.Through constructing Li alloying matrix with a bi-functional silver(Ag)-Li_(3)N blended interface,fast Li^(+)conductivity and high Li affinity can be achieved simultaneously,resulting in both decreased Li nucleation and mass transfercontrolled overpotentials.Beyond these properties,a more important feature is demonstrated herein;that is,the inward diffusion depth of the Li adatoms inside of the Ag site can be restricted by the Li^(+)solvation structure in a highly coordinating environment.The latter feature can ensure the durability of the operational Ag sites,thereby elongating the Li protection ability of the Ag-Li_(3)N interface greatly.This work provides a deep insight into the synergetic effect of functional alloying structure and Li^(+)solvation mediated interfacial kinetic on Li metal protection.
基金supported by the 21C Innovation Laboratory,Contemporary Amperex Technology Ltd. by project No. 21C-OP-202103the National Natural Science Foundation of China(52072061)。
文摘LiMn_(y)Fe_(1-y)PO_(4) is considered a promising cathode material for next-generation lithium-ion batteries(LIBs) due to its high energy density and low cost. Its energy density degradation is often ascribed to the capacity loss during cycling. However, in this study, we find that the energy density degradation mainly roots in voltage decay. We have synthesized a series of LiMn_(y)Fe_(1-y)PO_(4) /C(0.5 ≤ y ≤ 0.8) and find this voltage decay is correlated with the Mn content. A high amount Mn leads to a heavier voltage decay.In-situ X-ray diffraction(XRD) and high-resolution transmission electron microscopy(HRTEM) reveal the nature of this effect, which show a mismatch along the b-axis of-2.68%(charge) and +3.4%(discharge), a volume misfit of-4.41%(charge) and +4.54%(discharge) between Li_(x)Mn_(y)Fe_(1-y)PO_(4) and Mn_(y)Fe_(1-y)PO_(4) during phase transitions. The resultant misfit strains during Li+insertion compared to extraction result in structural degradations, such as amorphization and impurity(Mn F3) accumulation after cycling. The voltage decay can be alleviated by kinetic relaxations and recovered by a wild reannealing. This work demonstrates effective strategies to improve the energy density and cycling performance of LiMn_(y)Fe_(1-y)PO_(4) /C,providing good references for other LIB cathodes, such as the Li-rich cathodes.
基金This work was supported by the 21C Innovation Laboratory,Contemporary Amperex Technology Ltd by project No.21C-OP-202004the Ningbo 2025 Project(Grant No.2018B10061,2018B10087 and 2019B10044)+1 种基金the National Key R&D Program of China(Grant No.2018YFB0905400)the National Natural Science Foundation of China(Grant No.21805297).
文摘Lithium (Li) metal is considered as one of the most promising anode materials to build next-generation high-energy–density batteries. Nonetheless, dendritic Li deposition has dramatically hindered the practical applications of Li metal batteries (LMBs). Uniformizing Li deposition is a prerequisite to achieve safe and practical LMBs. Herein, an underpotential deposition (UPD) process is first proposed to alter the kinetic and uniformity of Li deposition morphology. Based on the strong interaction between the Li adatoms and manganese (Mn) based substrate, a competition between the UPD and bulk Li deposition is observed, on which the predominance of the UPD scenario tends to uniformize Li nucleation and deposition by the surface coverage of Li monolayers at potentials that are more positive than the Nernst potential of Li metal. Inspired by this process, an advanced hybrid Mn-graphene oxide structure is developed for Li protection, not only enabling dendrite-free Li anodes for high-capacity and -current density cycling, but also improving the interfacial kinetic of Li metal anodes at subzero temperatures, showing potential applicability in low temperature conditions.
基金the financial support of the Beijing National Laboratory for Condensed Matter Physics,21C Innovation Laboratory,Contemporary Amperex Technology Ltd.through project No.21C-OP-202212the Foundation of Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education),Nankai University+1 种基金the Foundation of State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering(Grant No.2022-K15),China University of Mining&Technology(Beijing)the National Natural Science Foundation of China(Nos.51672029,51372271).
文摘Rechargeable all-solid-state batteries(ASSBs)are considered to be the next generation of devices for electrochemical energy storage.The development of solid-state electrolytes(SSEs)is one of the most crucial subjects in the field of energy storage chemistry.The newly emerging halide SSEs have recently been intensively studied for application in ASSBs due to their favorable combination of high ionic conductivity,exceptional chemical and electrochemical stability,and superior mechanical deformability.In this review,a critical overview of the development,synthesis,chemical stability and remaining challenges of halide SSEs is given.The design strategies for optimizing the ionic conductivity of halide SSEs,such as element substitution and crystal structure design,are summarized in detail.Moreover,the associated chemical stability issues in terms of solvent compatibility,humid air stability and corresponding degradation mechanisms are discussed.In particular,advanced in situ/operando characterization techniques applied to halide-based ASSBs are highlighted.In addition,a comprehensive understanding of the interface issues,cost issues,and scalable processing challenges faced by halide-based ASSBs for practical application is provided.Finally,future perspectives on how to design high-performance electrode/electrolyte materials are given,which are instructive for guiding the development of halide-based ASSBs for energy conversion and storage.
基金supported by the Guangdong Basic and Applied Basic Research Foundation(Grant No.2021A1515011784)the Key Program of the National Natural Science Foundation of China(Grant No.51732005)+2 种基金the Shenzhen Science and Technology Program(Grant No.KQTD20200820113047086)21C Innovation Laboratory,Contemporary Amperex Technology Ltd(Grant No.C-ND-21C LAB-210044-1.0)the Guangdong-Hong Kong-Macao Joint Laboratory for Neutron Scattering Science and Technology。
文摘Anti-perovskite solid-state electrolyte Li_(2)OHCl usually exhibits orthorhombic phase and low ionic conductivity at room temperature.However,its ionic conductivity increases greatly when the temperature is up to 40℃,while it goes through an orthorhombic-to-cubic phase transition.The cubic Li_(2)OHCl with high ionic conductivity is stabilized at room temperature and even lower temperature about 10℃ by a simple synthesis method of wet mechanical milling.The cubic Li_(2)OHCl prepared by this method performs an ionic conductivity of 4.27×10^(-6) S/cm at room temperature,about one order of magnitude higher than that of the orthorhombic Li_(2)OHCl.The phase-transition temperature is decreased to around 10℃.Moreover,it can still remain cubic phase after heat treatment at 210℃.This work delivers a huge potential of fabricating high ionic conductivity phase antiperovskite solid-state electrolyte materials by wet mechanical milling.
文摘I first came to China for work in 2012 and now is the chief technology officer of Ningde Contemporary Amperex Technology Co.,Limited(hereinafter referred to as CATL).During my more than seven years of working in China,I have personally experienced the rapid development of China’s new energy vehicles,and witnessed the whole process of growing up as a wellknown supplier of power batteries of CATL.
基金This work was supported by the National Basic Research Program of China （No. 2015CB251100） and the National Natural Science Foundation of China （No. 51372268）.
文摘Lithium carbonate （Li2CO3） is very common in various types of lithium （Li） batteries. As an insulating by-product of the oxygen reduction reaction on the cathode of a Li-air battery, it cannot be decomposed below 4.75 V （vs. Li＋/Li） during recharge and leads to a large polarization, low coulombic efficiency, and low energy conversion efficiency of the battery. On the other hand, more than 10% of the Li ions from the cathode material are consumed during chemical formation of a Li-ion battery, resulting in low coulombic efficiency and/or energy density. Consequently, lithium compensation becomes essential to realize Li-ion batteries with a higher energy density and longer cycle life. Therefore, reducing the oxidation potential of Li2CO3 is significantly important. To address these issues, we show that the addition of nanoscaled LiCoO2 can effectively lower this potential to 4.25 V. On the basis of physical characterization and electrochemical evaluation, we propose the oxidization mechanism of Li2CO3. These findings will help to decrease the polarization of Li-air batteries and provide an effective strategy for efficient Li compensation for Li-ion batteries, which can significantly improve their energy density and increase their energy conversion efficiency and cycle life.
