Cross-Linked Amine Interface Engineering Strategy for High Performance Anode-Free Lithium-Metal Batteries With High-Loading Cathodes

Anode-free lithium-metal batteries (AFLMBs), wherein Li is plated onto a bare Cu current collector during the initial charge, feature a simplified architecture and high energy density. However, in AFLMBs employing high-mass-loading cathodes, the intrinsically poor lithiophilicity of bare Cu induces uncontrolled dendrite growth, irreversible lithium loss, and an unstable solid electrolyte interphase (SEI), resulting in rapid capacity decay and a low Coulombic efficiency (CE). Herein, an ultrathin, cross-linked polyethylenimine (PEI) coating is proposed as a simple yet effective interfacial engineering strategy to stabilize the anode–electrolyte interface through dual mechanisms. Abundant amine groups coordinate strongly with Li⁺, promoting homogeneous nucleation and vertical deposition while restricting lateral diffusion. The flexible polymer matrix acts as a robust barrier against parasitic reactions and corrosion. Consequently, Cu||Li half-cells with PEI-coated Cu sustain 350 cycles at 0.5 mA cm⁻² and 0.5 mAh cm⁻², delivering an average CE of 95.29%. Full cells with high-loading LiFePO₄ cathodes (26.52 mg cm⁻²) retain 57.65% of their initial capacity (3.26 to 1.87 mAh cm⁻²) after 100 cycles. These findings highlight nanoscale polymer coatings as a promising strategy for constructing stable artificial SEI layers in AFLMBs, yielding high-energy and durable Li-ion batteries.