物理化学学报 >> 2021, Vol. 37 >> Issue (2): 2008013.doi: 10.3866/PKU.WHXB202008013

所属专题: 金属锂负极

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锂金属电池研究中对称电池的短路现象

康丹苗1,*(), NoamHart2, 肖沐野1,3, JohnP. Lemmon1   

  1. 1 北京低碳清洁能源研究院,北京 102209
    2 NICE北美中心,山景城 CA94043
    3 帝国理工学院,伦敦 SW72AZ
  • 收稿日期:2020-08-05 发布日期:2020-09-09
  • 通讯作者: 康丹苗 E-mail:kangdanmiao@nicenergy.com

Short Circuit of Symmetrical Li/Li Cell in Li Metal Anode Research

Danmiao Kang1,*(), Noam Hart2, Muye Xiao1,3, John P. Lemmon1   

  1. 1 National Institute of Clean and Low-Carbon Energy, Beijing 102209, China
    2 NICE America Research, Mountain View, CA 94043, USA
    3 Imperial College London, London, SW72AZ, UK
  • Received:2020-08-05 Published:2020-09-09
  • Contact: Danmiao Kang E-mail:kangdanmiao@nicenergy.com
  • About author:Danmiao Kang, Email: kangdanmiao@nicenergy.com; Tel.: +86-152-107-78965

摘要:

锂金属是具有高能量密度的负极材料,是下一代高能量密度电池研究的重点。在锂金属负极的改性研究中,锂对称电池是最常用的测试对象,但判断其短路的依据尚未统一,因此存在部分对短路数据的解析错误。本文利用原位电池对锂沉积过程中由于枝晶生长导致的短路现象进行了描述,对锂金属对称电池在充放电过程中的短路现象进行了分类和讨论。通过区分硬短路、软短路及电池活化过程,提出了判断锂对称电池中枝晶生长及电池短路的依据,为判定锂金属负极改性方法的有效性提供参考。

关键词: 锂金属负极, 短路, 原位电池, 枝晶, 诊断

Abstract:

Lithium is a promising anode material for next-generation high-energy-density rechargeable batteries owing to its high specific capacity, low density, and low electrochemical reduction potential. However, dendrite growth during cycling impedes its practical application and causes safety hazards. Extensive research has been conducted to obtain dendrite-free safe Li anodes with an extended cycle life by electrolyte or anode surface modification. In previous studies, the symmetrical Li/Li cell test was widely applied to evaluate the effect of various Li anode modification methods on the cycle stability and Li deposition overpotential. However, a general criterion has not yet been established to identify the short circuit in Li/Li cells. Some researchers have even made incorrect conclusions based on the Li/Li cycling data. The most common misjudgment is the ignorance of short circuit signals and mixing up of soft short circuit and normal potential decrease caused by electrode activation. In some studies, the fractal voltage signals were attributed to the unstable activation process of the symmetrical cell. Therefore, this study uses an in situ optical cell to demonstrate that a short circuit caused by the contact of dendrites from two opposite electrodes can cause a sudden drop in cell voltage to certain extent. According to the reversibility of the voltage, the short circuit induced by dendrite growth can be classified into unrecoverable hard short circuits and recoverable soft short circuits. Typical short circuit data were summarized and described to establish a rule to determine the different types of short circuits. The voltage profiles provide characteristic signals to distinguish between the soft short circuit, hard short circuit, and cell activation processes in symmetrical cells. Furthermore, this study provides a reference for identifying dendrite growth and cell short circuits, which is important for confirming the practical effect of different modification methods.

Key words: Li metal anode, Short-circuit, In situ cell, Dendrite, Diagnose

MSC2000: 

  • O646