Thickness dependence of high volumetric energy density lithium ion battery based on Sn–Zn eutectic alloy foil anode

Lithium ion batteries (LIBs) with high volumetric energy density and intrinsic safety features are highly desirable for portable electronics. Herein, we report a Sn–Zn eutectic alloy foil as the additives and current collector free anode. The alloy’s superior plastic formation ability enables the easy production of foil anode. The foil exhibits high Zn–Sn interface densities and fine grain boundaries, which act as fast lithium ion diffusion sites, leading to its high volumetric specific capacity. The foil with the thinnest thickness shows a better volumetric specific capacity, whereas the foil with the thickest thickness maintains the best electrochemical–mechanical toleration due to the weakened lithiation driving force by its tougher mechanics. The LIB full-cell demonstrates strong thickness-dependent performances. This study gives insights into the engineered thickness issue for the alloy foil anode based LIBs and provides a direction guide towards low costs, high volumetric energy density, and intrinsic safety LIBs.