In Situ Volume Change Studies of Lithium Metal Electrode under Different Pressure

Due to the high theoretical capacity density of 3680 mAh g(-1), lithium (Li) is considered as a promising anode for high-energy-density battery systems. However, its practical application is severely hampered by the invariable growth of Li dendrites and tremendous volume change during electrochemical plating-stripping process. Although real-time monitoring of the volume change is crucial for research and development of stable lithium anode, the studies are rare due to the lack of in-situ swelling equipment so far. Here, we report an in-situ volume change system to observe the thickness change of Li electrode at a resolution of micrometer during the electrochemical process. With a comprehensive design for this instrument, a continuously tunable pressure can be applied on the Li-Li symmetric cell to investigate the impact of pressure on the stability of Li electrode during cycling. We found that the higher pressure (similar to 850kPa) is beneficial for stabilizing Li electrode during plating/stripping process. Our results provide a perspective to investigate the electrochemical behavior of Li electrode. In addition, this instrument also shows great potential of in-situ volume change monitoring in other battery systems like silicon anode and solid-state batteries. (C) 2019 The Electrochemical Society.