金属锂电池中力-电化学机制研究进展

Recent advances in mechano-electrochemistry in lithium metal batteries

以金属锂作为负极的金属锂电池具有极高的能量密度,有望成为下一代高比能量二次电池。然而,在充放电过程中,金属锂负极的相变转化机制、枝晶状形貌沉积特性使得电池具有巨大且极不均匀的内部体积变化。因此,相比于插层机制的锂离子电池,金属锂电池面临着锂枝晶生长、锂枝晶断裂与粉化、固体电解质(SEI)膜破裂、电解质/隔膜机械失效等更为严重的力-电化学相关问题。本文首先总结金属锂的弹性、塑性与黏性力学特性,并着重介绍了电沉积锂展现的尺寸效应,随后综述了金属锂电池环境中的力-电化学机制研究进展。针对液态电解质环境,介绍了应力驱动下的锂枝晶生长机制、界面(金属锂与SEI、负极与隔膜、金属锂与集流体)相互作用机制以及外压力调控机制。针对固态电解质环境,介绍了固-固界面接触带来的离子输运影响以及电解质体相/晶界/孔隙与金属锂之间的相互作用机制。最后,对当前金属锂电池中的力-电化学机制研究进行了总结并对未来发展方向进行了展望。

Lithium metal batteries are considered next-generation rechargeable batteries owing to their ultrahigh energy density.However,during the charging/discharging process,the conversion mechanism and dendritic morphology of lithium metal anodes lead to huge and uneven internal volume modifications.Thus,lithium metal batteries experience more serious mechano-electrochemical problems compared with lithium-ion batteries,including lithium dendrite growth,lithium dendrite fracture and pulverization,solid electrolyte interphase(SEI)rupture,and electrolyte/separator mechanical failure.This review introduces the mechanical properties of lithium metal first,including elasticity,plasticity,and viscosity.Especially,the size effect of electrodeposited lithium is highlighted.Next,recent advances in mechanoelectrochemical mechanisms in working lithium metal batteries are summarized.For the liquid electrolyte environment,the stress-driven lithium dendrite growth mechanism,interfacial(lithium metal and SEI,electrode and separator,and lithium metal and current collector)interaction mechanism,and external pressure regulation mechanism are presented.For the solid electrolyte environment,the ion transport impact from the solid-solid contact and interaction between the bulk/grain boundaries/voids of electrolytes and lithium metal are presented.Finally,the mechano-electrochemical mechanism in lithium metal batteries is summarized and the future development direction is prospected.