Expediting Lithium Electrochemistry via a Bilayer for High-Rate Lithium Metal Batteries

The intrinsic characteristics of the Li metal anode, particularly its ultra-high specific capacity (3860 mAh g^-1) and low redox potential (-3.04 V vs. SHE), theoretically make it ideal for high-rate charge/discharge operations. However, the high Li self-diffusion barrier causes uncontrolled plating/stripping dynamics and severe volume fluctuations, hindering stable performance at elevated current densities. In this study, we introduced an artificial solid-electrolyte interphase (ASEI) engineered with a bilayer that transcends conventional planar deposition, facilitating Li nucleation and growth along three-dimensional electronic percolation pathways. This spatially distributed, lateral plating morphology significantly reduced charge-transfer resistance, suppressed dendrite formation, and mitigated cell degradation under high charging currents. Consequently, the ASEI-enabled Li metal electrode maintained low overpotentials at an areal capacity of 10 mAh cm^-2 and a current density of 20 mA cm^-2 for over 300 h, while demonstrating outstanding rate capability and long-term cyclability in LiFePO₄(LFP)‖Li and LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811)‖Li full cells. By elucidating these intrinsic anode behaviors, our findings establish a fundamental design strategy for high-rate performance, potentially advancing the commercialization of Li metal batteries.