In situ coating of a lithiophilic interphase on a biporous Cu scaffold with vertical microchannels for dendrite-free Li metal batteries

Abstract

Severe dendrite growth, low coulombic efficiency and huge volume change have impeded the practical application of Li metal anodes, and the construction of porous scaffolds is an effective strategy to stabilize Li metal. Herein, copper oxide (CuO_x) is coated in situ on a unique biporous Cu scaffold (CuO_x@Cu) through direct thermal oxidation. CuO_x with strong lithiophilicity, confirmed by DFT calculations and experiments, can greatly decrease the nucleation barrier and increase the nucleation sites of Li metal. The reactions of CuO_x with Li form Li₂O, which can reinforce the SEI films and regulate ion distribution. Biporous Cu with vertical microchannels and interconnected pores, derived by the phase inversion method, can dissipate local current density and improve the uniformity of Li deposition. As a result, CuO_x@Cu demonstrates a nucleation overpotential of 5 mV and a high coulombic efficiency of 98.8% over 520 cycles at 1 mA cm⁻², outperforming most of the reported scaffolds. Symmetric cells with CuO_x@Cu exhibit much prolonged lifespans and reduced hysteresis in both ether-based and carbonate-based electrolytes. Furthermore, full cells with LiFePO₄ cathodes or LiNi_0.7Co_0.1Mn_0.2O₂ cathodes exhibit excellent long-term cycling stability and rate capability, demonstrating great compatibility with the current industry and promoting the practical application of Li metal batteries.