计算模拟在锂金属负极研究中的应用

锂金属以其高比容量和低电极电势,在高能量密度电池领域具有极大潜力,然而界面反应复杂、枝晶生长难以抑制等问题,导致电池易燃易爆、容易击穿短路,极大地限制了锂电池的应用。计算模拟有助于科研工作者认识反应机理、预测筛选电极材料以及优化电池设计,与实验相辅相成。本文对近年计算模拟在锂金属电极中的应用进行综述,重点在于利用分子动力学、第一性原理计算等计算方法,研究界面反应、固体电解质膜以及锂形核。此外,新开发的固态电解质很好地解决了传统锂电池易燃易爆等问题,提高了能量密度,但也存在界面阻力大、传导性能差以及枝晶生长等问题,对此,我们就计算模拟在固态电解质锂电池中锂负极的应用进行综述。最后,我们论述了该领域潜在研究方向。

Application of Computational Simulation on the Study of Lithium Metal Anodes

Lithium-metal anode batteries have the potential to serve as next-generation, high energy density batteries with high specific capacity and low electrode potential. However, due to the high reactivity of lithium, complex interfacial reactions and uncontrollable dendrite growth obstruct their application. These lithium-metal anode interfacial reactions are often accompanied by the organic electrolyte spontaneously decomposing and combustible gas subsequently escaping, which is a safety concern. It also affects the form of the solid electrolyte interphase (SEI), which is important for stabilizing the interface between the Li-metal anode and electrolyte. Uncontrollable Li dendrite growth could penetrate the separator or electrolyte, creating the risk of a short circuit. Therefore, it is necessary to optimize the lithium nucleation and deposition processes. Solid state electrolytes (SSEs) have also attracted attention for improving the energy density and safety of Li-ion batteries; however, problems such as poor ionic conductivity still exist. Computational simulations, such as molecular dynamics (MD) simulations and first-principles calculations based on density function theory (DFT), can help elucidate reaction mechanisms, explore electrode materials, and optimize battery design. In this review, we summarize the theoretical perspective gained from computational simulation studies of lithium-metal anodes. This review is organized into four sections: interfacial reactions, SEIs, lithium nucleation, and SSEs. We first explore organic-electrolyte interfacial reaction mechanisms that were revealed through MD simulations and how electrolyte additives, electrolyte concentration, operating temperature affect them. For SEI, DFT can provide an in-depth understanding of the surface chemical reaction, surface morphology, electrochemical properties, and kinetic characteristics of SEI. We review the developments in SEI transmission mechanisms and SEI materials' properties alteration by lithium metal. We further explore artificial SEI design requirements and compare the performances of artificial SEIs, including double-layer, fluorine-, and sulfur-SEIs. Lithium dendrite growth as a result of lithium nucleation and deposition is then discussed, focusing on computational studies that evaluated how doped graphene, 3D carbon fibers, porous metals, and other matrix materials regulated these processes and inhibited dendrite growth. Computational simulations evaluating transport phenomena and interface reactions between SSEs and lithium-metal anodes are then explored, followed by ideas for further design optimization. Finally, potential research directions and perspectives in this field are proposed and discussed.