查看更多>>摘要：Lithium-ion batteries(LIBs)play a pivotal role in today's society,with widespread applications in portable electronics,electric vehicles,and smart grids.Commercial LIBs predominantly utilize graphite anodes due to their high energy density and cost-effectiveness.Graphite anodes face challenges,however,in extreme safety-demanding situations,such as airplanes and passenger ships.The lithiation of graphite can potentially form lithium dendrites at low temperatures,causing short circuits.Additionally,the dissolution of the solid-electrolyte-interphase on graphite surfaces at high temperatures can lead to intense reactions with the electrolyte,initiating thermal runaway.This review introduces two promising high-safety anode materials,Li4Ti5O12 and TiNb2O7.Both materials exhibit low tendencies towards lithium dendrite formation and have high onset temperatures for reactions with the electrolyte,resulting in reduced heat generation and significantly lower probabilities of thermal runaway.Li4Ti5O12 and TiNb2O7 offer enhanced safety characteristics compared to graphite,making them suitable for applications with stringent safety requirements.This review provides a comprehensive overview of Li4Ti5O12 and TiNb2O7,focusing on their material properties and practical applicability.It aims to contribute to the understanding and development of high-safety anode materials for advanced LIBs,addressing the challenges and opportunities associated with their implementation in real-world applications.
查看更多>>摘要：The ideal composite electrolyte for the pursued safe and high-energy-density lithium metal batteries(LMBs)is expected to demonstrate peculiarity of superior bulk conductivity,low interfacial resistances,and good compatibility against both Li-metal anode and high-voltage cathode.There is no composite electrolyte to synchronously meet all these requirements yet,and the battery performance is inhibited by the absence of effective electrolyte design.Here we report a unique"concentrated ionogel-in-ceramic"silanization composite electrolyte(SCE)and validate an electrolyte design strategy based on the coupling of high-content silane-conditioning garnet and concentrated ionogel that builds well-percolated Li+transport pathways and tackles the interface issues to respond all the aforementioned requirements.It is revealed that the silane conditioning enables the uniform dispersion of garnet nanoparticles at high content(70 wt％)and forms mixed-lithiophobic-conductive LiF-Li3N solid electrolyte interphase.Notably,the yielding SCE delivers an ultrahigh ionic conductivity of 1.76 X 10-3 S cm-1 at 25 ℃,an extremely low Li-metal/electrolyte interfacial area-specific resistance of 13 Ω cm2,and a distinctly excellent long-term 1200 cycling without any capacity decay in 4.3 V Li‖LiNi0.5Co0.2Mn0.3O2(NCM523)quasi-solid-state LMB.This composite electrolyte design strategy can be extended to other quasi-/solid-state LMBs.
查看更多>>摘要：Metal-covalent organic frameworks(MCOF)as a bridge between covalent organic framework(COF)and metal organic framework(MOF)possess the characteristics of open metal sites,structure stability,crystallinity,tunability as well as porosity,but still in its infancy.In this work,a covalent organic framework DT-COF with a keto-enamine structure synthesized from the condensation of 3,3'-dihydroxybiphenyl diamine(DHBD)and triformylphloroglucinol(TFP)was coordinated with Cu2+by a simple post-modification method to a obtain a copper-coordinated metal-covalent organic framework of Cu-DT COF.The isomerization from a keto-enamine structure of DT-COF to a enol-imine structure of Cu-DT COF is induced due to the coordination interaction of Cu2+.The structure change of Cu-DT COF induces the change of the electron distribution in the Cu-DT COF,which greatly promotes the activation and deep Li-storage behavior of the COF skeleton.As anode material for lithium-ion batteries(LIBs),Cu-DT COF exhibits greatly improved electrochemical performance,retaining the specific capacities of 760 mAh g-1 after 200 cycles and 505 mAh g-1 after 500 cycles at a current density of 0.5 A g-1.The preliminary lithium storage mechanism studies indicate that Cu2+is also involved in the lithium storage process.A possible mechanism for Cu-DT COF was proposed on the basis of FT-IR,XPS,EPR characterization and electrochemical analysis.This work enlightens a novel strategy to improve the energy storage performance of COF and promotes the application of COF and MCOF in LIBs.
查看更多>>摘要：To achieve high-energy-density and safe lithium-metal batteries(LMBs),solid-state electrolytes(SSEs)that exhibit fast Li-ion conductivity and good stability against lithium metal are of great importance.This study presents a systematic exploration of selenide-based materials as potential SSE candidates.Initially,Li8SeN2 and Li7PSe6 were selected from 25 ternary selenides based on their ability to form stable interfaces with lithium metal.Subsequently,their favorable electronic insulation and mechanical properties were verified.Furthermore,extensive theoretical investigations were conducted to elucidate the fundamental mechanisms underlying Li-ion migration in Li8SeN2,Li7PSe6,and derived Li6PSe5X(X=Cl,Br,I).Notably,the highly favorable Li-ion conduction mechanism of vacancy diffusion was identified in Li6PSe5Cl and Li7PSe6,which exhibited remarkably low activation energies of 0.21 and 0.23 eV,and conductivity values of 3.85 × 10-2 and 2.47 × 10-2 S cm-1 at 300 K,respectively.In contrast,Li-ion migration in Li8SeN2 was found to occur via a substitution mechanism with a significant diffusion energy barrier,resulting in a high activation energy and low Li-ion conductivity of 0.54 eV and 3.6×10-6 S cm-1,respectively.Throughout this study,it was found that the ab initio molecular dynamics and nudged elastic band methods are complementary in revealing the Li-ion conduction mechanisms.Utilizing both methods proved to be efficient,as relying on only one of them would be insufficient.The discoveries made and methodology presented in this work lay a solid foundation and provide valuable insights for future research on SSEs for LMBs.
查看更多>>摘要：Developing anode materials with high specific capacity and cycling stability is vital for improving thin-film lithium-ion batteries.Thin-film zinc oxide(ZnO)holds promise due to its high specific capacity,but it suffers from volume changes and structural stress during cycling,leading to poor battery performance.In this research,we ingeniously combined polytetrafluoroethylene(PTFE)with ZnO using a radio frequency(RF)magnetron co-sputtering method,ensuring a strong bond in the thin-film composite electrode.PTFE effectively reduced stress on the active material and mitigated volume change effects during Li+ion intercalation and deintercalation.The composite thin films are thoroughly characterized using advanced techniques such as X-ray diffraction,scanning electron microscopy,and X-ray photoelectron spectroscopy for investigating correlations between material properties and electrochemical behaviors.Notably,the ZnO/PTFE thin-film electrode demonstrated an impressive specific capacity of 1305 mAh g1(=7116 mAh cm-3)at a 0.5C rate and a remarkable capacity retention of 82％from the 1st to the 100th cycle,surpassing the bare ZnO thin film(50％).This study provides valuable insights into using binders to stabilize active materials in thin-film batteries,enhancing battery performance.
查看更多>>摘要：The undesirable capacity loss after first cycle is universal among layered cathode materials,which results in the capacity and energy decay.The key to resolving this obstacle lies in understanding the effect and origin of specific active Li sites during discharge process.In this study,focusing on Ah-level pouch cells for reliability,an ultrahigh initial Coulombic efficiency(96.1％)is achieved in an archetypical Li-rich layered oxide material.Combining the structure and electrochemistry analysis,we demonstrate that the achievement of high-capacity reversibility is a kinetic effect,primarily related to the sluggish Li mobility during oxygen reduction.Activating oxygen reduction through small density would induce the oxygen framework contraction,which,according to Pauli repulsion,imposes a great repulsive force to hinder the transport of tetrahedral Li.The tetrahedral Li storage upon deep oxygen reduction is experimentally visualized and,more importantly,contributes to 6％Coulombic efficiency enhancement as well as 10％energy density improvement for pouch cells,which shows great potentials breaking through the capacity and energy limitation imposed by intercalation chemistry.
查看更多>>摘要：FeS2 cathode is promising for all-solid-state lithium batteries due to its ultra-high capacity,low cost,and environmental friendliness.However,the poor performances,induced by limited electrode-electrolyte interface,severe volume expansion,and polysulfide shuttle,hinder the application of FeS2 in all-solid-state lithium batteries.Herein,an integrated 3D FeS2 electrode with full infiltration of Li6PS5Cl sulfide electrolytes is designed to address these challenges.Such a 3D integrated design not only achieves intimate and maximized interfacial contact between electrode and sulfide electrolytes,but also effectively buffers the inner volume change of FeS2 and completely eliminates the polysulfide shuttle through direct solid-solid conversion of Li2S/S.Besides,the vertical 3D arrays guarantee direct electron transport channels and horizontally shortened ion diffusion paths,endowing the integrated electrode with a remarkably reduced interfacial impedance and enhanced reaction kinetics.Benefiting from these synergies,the integrated all-solid-state lithium battery exhibits the largest reversible capacity(667 mAh g-1),best rate performance,and highest capacity retention of 82％over 500 cycles at 0.1 C compared to both a liquid battery and non-integrated all-solid-state lithium battery.The cycling performance is among the best reported for FeS2-based all-solid-state lithium batteries.This work presents an innovative synergistic strategy for designing long-cycling high-energy all-solid-state lithium batteries,which can be readily applied to other battery systems,such as lithium-sulfur batteries.
查看更多>>摘要：The accurate representation of lithium plating and aging phenomena has posed a persistent challenge within the battery research community.Empirical evidence underscores the pivotal role of cell structure in influencing aging behaviors and lithium plating within lithium-ion batteries(LIBs).Available lithium-ion plating models often falter in detailed description when integrating the structural intricacies.To address this challenge,this study proposes an innovative hierarchical model that intricately incorporates the layered rolling structure in cells.Notably,our model demonstrates a remarkable capacity to predict the non-uniform distribution of current density and overpotential along the rolling direction of LIBs.Subsequently,we delve into an insightful exploration of the structural factors that influence lithium plating behavior,leveraging the foundation laid by our established model.Furthermore,we easily update the hierarchical model by considering aging factors.This aging model effectively anticipates capacity fatigue and lithium plating tendencies across individual layers of LIBs,all while maintaining computational efficiency.In light of our findings,this model yields novel perspectives on capacity fatigue dynamics and local lithium plating behaviors,offering a substantial advancement compared to existing models.This research paves the way for more efficient and tailored LIB design and operation,with broad implications for energy storage technologies.
查看更多>>摘要：Most organic electrode materials(OEMs)for rechargeable batteries employ n-type redox centers,whose redox potentials are intrinsically limited＜3.0 V versus Li+/Li.However,p-type materials possessing high redox potentials experience low specific capacities because they are capable of only a single redox reaction within the stable electrochemical window of typical electrolytes.Herein,we report 5,11-diethyl-5,11-dihydroindolo[3,2-b]carbazole(DEICZ)as a novel p-type OEM,exhibiting stable plateaus at high discharge potentials of 3.44 and 4.09 V versus Li+/Li.Notably,the second redox potential of DEICZ is within the stable electrochemical window.The mechanism of the double redox reaction is investigated using both theoretical calculations and experimental measurements,including density functional theory calculations,ex situ electron spin resonance,and X-ray photoelectron spectroscopy.Finally,hybridization with single-walled carbon nanotubes(SWCNT)improves the cycle stability and rate performance of DEICZ owing to the π-π interactions between the SWCNT and co-planar molecular structure of DEICZ,preventing the dissolution of active materials into the electrolyte.The DEICZ/SWCNT composite electrode maintains 70.4％of its initial specific capacity at 1-C rate and also exhibits high-rate capability,even performing well at 100-C rate.Furthermore,we demonstrate its potential for flexible batteries after applying 1000 bending stresses to the composite electrode.
查看更多>>摘要：Zn metal anodes are usually subject to grave dendrite growth during platting/stripping,which dramatically curtails the lifespan of aqueous Zn-ion batteries and capacitors.To address above problems,in our work,a novel phosphorus-functionalized multichannel carbon interlayer was designed and covered on Zn anodes.The results demonstrated that the multichannel structure combined with the three-dimensional meshy skeleton can provide more sufficient space for Zn deposition,thereby effectively inhibiting the growth of zinc dendrites.Meanwhile,theoretical calculations also confirmed that the P-C and P=O functional groups from phosphorus-functionalized multichannel carbon interlayer have the decisive influence in reducing the zinc nucleation potential and depositing uniformly zinc.Concretely,the symmetrical battery assembled with phosphorus-functionalized multichannel carbon interlayer-covered Zn anodes possessed a long lifetime of 3300 h at 2 mA cm-2 with 1 mAh cm-2.Furthermore,the full cell with activated carbon cathodes exhibited a high specific capacity of 80.5 mAh g-1 and outstanding cycling stability without capacity decay after 15 000 cycles at a high current density of 5 A g-1.The superior electrochemical performance exceeded that of most reported papers.Consequently,our synthesized zincophilic interlayer with the unique structure has superior prospects for application in stabilizing zinc anodes and prolonging the lifespan of batteries.
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