Alkaliphilic Cu2O nanowires on copper foam for hosting Li/Na as ultrastable alkali-metal anodes

Abstract

Alkali metals have been regarded as “holy-grail” anode materials for next-generation high-performance rechargeable batteries, but their prevailing implementation still requires solving some intrinsic issues, such as parasitic dendrite growth and infinite volume change. This work reports the fabrication of novel composite Li and Na anodes through the infusion of molten metals into a Cu-foam host, of which the surface was modified by Cu₂O nanowires that possess excellent affinity to the alkali metals. This nanostructured Cu₂O enabled reaction with Li/Na to produce a binary alloy layer which not only served as an enthalpic driver for quick infiltration of molten Li/Na into the Cu foam, but also effectively reduced the Li/Na nucleation barrier. The conductive skeleton of Cu foam with a high specific surface area effectively reduced local current density and heterogeneity, and further constrained volume expansion during repeated Li/Na stripping/plating. As a result, the obtained composite Li/Na@CF anodes were free of dendrite growth and exhibited near-zero volume expansion during repeated stripping/plating, leading to significantly improved cycling stability and coulombic efficiency. The Li/Na@CF anodes in symmetric cells demonstrated superior long-term stability over more than 500 cycles with overpotentials as small as 10 mV and when coupled with LiFePO₄ or Na₃V₂(PO₄)₃ achieved much higher capacity retention than their bare metal counterparts. By developing an effective solution for metal anode stabilization and providing insights into the enhancement mechanism, this work paves the way for the development of next-generation high-energy-density alkali-metal batteries.