Stabilization of the Li metal anode through constructing a LiZn alloy/polymer hybrid protective layer towards uniform Li deposition

Abstract

Constructing an artificial solid electrolyte interphase (SEI) layer is an effective strategy for solving uncontrolled Li dendrite growth resulting from an unstable and heterogeneous Li/electrolyte interface. Herein, we develop a hybrid layer of a LiZn alloy and a polyethylene oxide (PEO) polymer to protect the Li metal anode for achieving a Li dendrite-free Li metal anode surface. The LiZn alloy is advantageous for fast Li⁺ transport, and is uniformly dispersed in the PEO matrix to regulate electronic and Li⁺ ion flux distributions homogeneously. Furthermore, the flexible PEO network can alleviate the volume change during cycling. The synergistic effect enables Li deposition underneath the hybrid film. Hence, the hybrid protection film results in significantly improved cycling stability with respect to the pristine Li metal anode. A symmetric Li/Li cell with a composite protective layer can be cycled for over 1000 h at a current density of 1 mA cm⁻² with a fixed capacity of 1 mA h cm⁻², and a full cell with a high areal capacity of the LiFePO₄ (2.45 mA h cm⁻²) cathode exhibits an outstanding cycling performance.