Gradient Design for Constructing Artificial Sei Layer Towards High-Performace Lithium Metal Batteries

Abstract

The construction of artificial protective interphase layer on Li anode is one of the most effective methods to block Li dendrite growth and volume expansion. The disparity in charge-transport and ion diffusion is deteriorated due to the variation of component gradients and diffusion kinetics at different depths. However, there are few researches which pay attention to the regulation of components’ distribution in artificial solid electrolyte interphase layer (SEI layer), which is of great significance for enhancing the electrochemical performance of Li anode. Here, a gradient-design SEI layer is constructed at different depths on the Li anode to regulate charge transport and ion diffusion kinetics, which and controlling the lithium deposition process. Based on this gradient structure, the combination and gradient distribution of inorganic and organic components in the as-constructed SEI can effectively regulate the Li+ configuration and hinder the volume change during Li plating/stripping progress. With this hybrid robust SEI layer, an improved stably cycle of Li-Li symmetric cell is been achieved over 1750 h with a low overpotential under an ultrahigh current density of 10 mA cm−2, and ultrahigh capacity of 10 mAh cm−2. Based on the gradient-design artificial SEI film, the pouch cells with hybrid SEI layer coated Li matching with high-loading LiFePO4 cathode (21 mg cm-2) demonstrates extremely long cycling life with almost no capacity fade, which is superior compared with previous reports.

Keywords: Lithium metal anode, Artificial SEI layer, Dendrites, High density current, Pouch cell