Reveling the Influencing Factors of Electrochemical Behaviors of Lithium Metal Anodes: Electron Transfer and Li-ion Transport

Lithium metal anodes are considered to be the most promising anodes in the next generation of energy storage batteries. However, the inevitably serious dendrite growth and potential safety hazard hinder their practical applications. Despite improving the transport of Li-ions and reducing the velocity of transferring electrons have been proposed to protect Li metal anodes, it still needs better understanding to clarify the intrinsic electrochemical mechanism for their joint effect. Herein, we simulated and quantified the two crucial processes manipulating the Li-ion behavior, electron transfer and Li-ion transport factors, and visualized the local deposition rate, overpotential as well as the Li-ion concentration in a three-dimensional (3D) model via the finite element method (FEM). Our analysis revealed the competitive relationship between the speed of Li-ion transport and electron transfer. When the electron transfer is relatively slow, there are sufficient Li-ion available near the anode surface, in which the deposition behavior is controlled by electron transfer. However, in the condition of Li-ions are depleted due to the rate of Li-ions transport being unable to keep up with electron transfer, Li-ion transport would dominate the deposition process, leading to dendrite morphology. Therefore, reducing the reactivity of Li anode and accelerating the Li-ion transport are the keys to uniform the Li metal anode deposition morphology, particularly under fast charging condition and in practical application.