Ultra-thin anodes with controlled thickness modified using in situ Li3N for high-energy-density lithium metal batteries

Abstract

The employment of thin lithium metal anodes (LMAs) to regulate plating/stripping behaviour can achieve high energy density lithium batteries. However, the routinely used Li metal foils inevitably face significant challenges in commercial availability owing to their mechanical fragility and poor machinability. Herein, we proposed a simple process to synthesize thin, freestanding LMAs with controllable thickness (10–50 μm) using graphene oxide (GO) substrate and generated an in situ artificial interfacial layer of Li₃N on the electrode surface, which enhanced the Li wettability and enabled homogeneous deposition of Li. The well-designed 3D structure shortened the Li⁺ transport path, and the nitrogen-doped carbon nanofibres (NCFs) that were interspersed longitudinally between the graphene layers increased the electron transport efficiency and electrical conductivity. The ultrathin material with controllable thickness reduced the lithium wastage, which was conducive to the realization of high-energy-density batteries. The ultra-thin lithium metal anode (denoted as NCF/rGO/Li₃N) symmetric cell was capable of stable plating/stripping for more than 1500 h at 1 mA cm⁻². The NCF/rGO/Li₃N‖LFP full cell exhibited excellent performance in both liquid-based electrolytes and solid electrolytes. NCF/rGO/Li₃N‖NCM811 pouch cell, with a low negative/positive (N/P) ratio (2.3), offered an average energy density of 310 W h kg⁻¹ with 93.5% capacity retention after 60 cycles. The excellent electrochemical performance of the thin LMA provides a promising avenue for achieving high-energy-density batteries.