摘要
金属锂具有极高的理论能量密度,是新一代锂电池中最有潜力的负极材料之一。金属锂沉积时容易形成枝晶,极大影响了锂金属电池的安全性与使用寿命。但由于金属锂性质活泼,缺乏锂电极/电解液界面原位表征方法,锂枝晶生长机制尚不明确。通过有限元方法,基于非线性电极过程动力学,以三次电流模型定量研究了电极/电解液界面行为,并分析不同过程参数对表面电流的影响。结果表明,电极/电解质界面的浓度、电场差异是枝晶生长的主要原因,更大的扩散系数有利于提高界面浓度均匀性,更小的交换电流密度有利于减弱界面反应的敏感性。存在电化学极化区间是均匀沉积的必要条件,电化学极化区间越宽,均匀沉积操作窗口越宽。通过极化曲线可以判断体系是否具有均匀沉积的倾向。加深了对锂电极/电解液界面的电沉积过程的理解,对锂负极保护研究具有指导性意义。
Lithium metal has a very high theoretical energy density and is one of the most promising anode materials for a new generation of lithium batteries.It is easy to form dendrites during the deposition of lithium metal,which greatly affects the safety and service life of lithium metal batteries.Mechanism of dendrite propagation in lithium metal batteries(LMB)is still to be fundamentally described.Herein,we studied the effects of electrochemical parameters on the behavior of lithium plating at the electrode/electrolyte interface using a tertiary current model by finite-element methods.The results show that dendrite growth is intrinsically influenced by differences in concentration and potential.A higher diffusion coefficient(De)of Li ion in electrolyte is effective to improve uniformity of local concentration and a smaller exchange current density(i^0)is essential for reducing sensitivity of interface reaction.Activation polarization is beneficial for uniform plating of lithium.Thus,the polarization curve is extremely important to determine whether lithium deposits uniformly or not.This work results in a new understanding of principles for dendrite growth,and is expected to lead to new insights on strategies for dendrite suppression.
作者
林振康
乔耀璇
王伟
袁洪
樊铖
孙克宁
LIN Zhenkang;QIAO Yaoxuan;WANG Wei;YUAN Hong;FAN Cheng;SUN Kening(School of Chemistry and Chemical Engineering,Beijing Institute of Technology,Beijing 100081,China;Advanced Research Institute for Multidisciplinary Science,Beijing Institute of Technology,Beijing 100081,China;Department of Chemical Engineering,Tsinghua University,Beijing 100084,China)
出处
《化工学报》
EI
CAS
CSCD
北大核心
2020年第9期4228-4237,共10页
CIESC Journal
关键词
锂金属电池
电化学
动力学
数值模拟
锂枝晶
Li metal batteries
electrochemistry
kinetics
numerical simulation
Li dendrite
