In Situ Electrode Stress Monitoring: An Effective Approach to Study the Electrochemical Behavior of a Lithium Metal Anode

Abstract

The evolution of mechanical stress in lithium metal anodes has been suggested as a persistent challenge for large volume fluctuations, dendritic lithium deposition, and eventual failure of the electrodes. There is, however, only limited knowledge and probe methods regarding the stress generation of lithium metal anodes. Here, the stress evolution of a practical lithium metal anode during lithium plating/stripping was studied for the first time and in situ precise measurements were performed using a well-designed electrochemistry-mechanics-coupled cell device. A failure mechanism of the Li metal anode was proved by the observed Li morphology and the continuously increasing stress evolution of the Li metal over cycling. The Li metal anode suffers from a dramatic stress increase and irreversible volume expansion due to the formation of porous Li and "dead"Li after the continuous Li metal volume change during the electrochemical reaction. The real-time stress evolution of lithium could be probed with a variety of parameters, e.g., electrolytes, rates, cathode mass loadings, and even short circuits. This approach can be adopted for the in situ investigation of electrodes with large volume variations (Si and alloy anodes) to gain additional insights into the mechanical effects of energy storage, short circuit detection, and safe battery design.