Mechanism of Lithium Dendrites Formation and Suppression Strategies in Li Metal Batteries

This paper describes and summarizes the modifying progress established on Li metal anode in recent years. With the increasing demand for high-capacity batteries, Li-ion batteries, one of the most commercialized batteries, can no longer meet the demand. Thus, the high-energy-density lithium metal battery using lithium metal as anode is widely researched due to the lowest electrochemical potential (-3.04 V) of lithium and ultimate theoretical capacity (3860 mAh/g). However, the Li dendrites formation becomes the main obstacle for the commercialization as it will trigger thermal runaway and short circuit. In this paper, the growth process of Li dendrites was discussed, and various modifying solutions based on electrolytes, Li alloy and current collectors to suppress Li dendrites were summarized.

Phase-field investigation of lithium electrodeposition under different applied overpotentials and operating temperatures

Despite the high promise, the commercialization of Li-metal-based batteries has been hampered due to the formation of dendrites that lead to mechanical instability, energy loss and eventual internal short circuits. The mechanism of dendrite formation and the strategies to suppress their growth have been studied intensively. However, the effect of applied overpotential and operating temperature on dendrite growth remains to be fully understood. Here, we elucidate the correlation of overpotential and temperature with the surface modulation during electrodeposition using phase-field simulations. We identify an optimal operating temperature of half-cell consisting of a Li metal anode and 1M LiPF6 in EC:DMC(1:1), which increases gradually as the overpotential increases. The investigation reveals that the temperature dependence identified in the simulations and experiments often disagree because they are primarily conducted in galvanostatic and potentiostatic conditions, respectively. The temperature increase under potentiostatic conditions increases the induced current while it decreases the induced overpotential under galvanostatic conditions. Therefore, the analysis and comparison of temperature-dependent characteristics must be carried out with care.