锂离子在三维骨架复合锂金属负极中的沉积规律

Plating of Li ions in 3D structured lithium metal anodes

锂金属具有极高的理论比容量和极低的氧化还原电极电势,成为了新一代高比能二次电池最理想的负极材料。然而,锂金属负极其走向大规模应用仍存在诸多问题与挑战。三维骨架复合负极可以控制金属锂均匀形核,低电流密度下均匀沉积,有望推动锂金属负极的实用化。为了更高效地指导锂金属负极设计和优化,采用相场理论,对三维骨架锂金属负极中比表面积对金属锂沉积过程的作用机制进行了定量分析和探究,发现了比表面积调控金属锂沉积的两阶段作用机理,并提出了基于比表面积参数的三维骨架负极设计与优化方向,从而最大程度发挥三维骨架在调控稳定金属锂负极上的积极作用。

Lithium metal has a very high theoretical specific capacity and a very low redox electrode potential,making it the most ideal anode material for a new generation of high specific energy secondary batteries.However,the large-scale practical applications of lithium metal batteries have been hindered by several issues on lithium metal anodes,such as uncontrollable lithium electroplating morphology and unstable solid electrolyte interphase(SEI)layer.Researchers have proposed plenty of strategies including three-dimensional(3D)structured lithium metal anodes to settle these challenges.The rational design of 3D structured lithium metal anodes requires a deep understanding of the mechanisms behind lithium metal batteries,which are extremely deficient at current initial stage.In this work,the mechanism of the areal surface area in 3D structured lithium metal anode on the electroplating process of lithium metal is quantitatively explored,and the two-stage mechanism of the areal surface area regulating lithium metal electroplating was revealed.At the early stage,higher areal surface area can provide more activated sites for electrochemical reactions,which can reduce the reaction resistance.While at the later stage,higher areal surface area may bring more narrow pores,which may hinder the lithium ion transport.In order to maximize the positive effect of 3D structured lithium metal anode in the early stage,the areal surface area and pore structure should be rational designed.