Hierarchical coaxial heterostructure enabled by thermal annealing cobalt nanowires for stable lithium anodes

Abstract

Lithium metal batteries (LMBs) are regarded as ideal candidates for the next generation of batteries due to their exceptionally high energy density. However, the practical applications of LMBs face significant challenges, primarily due to dimensional changes and the growth of lithium (Li) dendrites during long-term cycling. Herein, hierarchical coaxial heterostructures based on lithiophilic Co₃O₄ nanosheets anchored on Co nanowires (CoNWs) were constructed via in-situ thermal annealing process, enabling efficient thermal Li infusion for stable Li anodes. The design of the CoNWs@Co₃O₄ coaxial heterostructure not only tunes the electronic structure and enhances electron and Li ion transfer via the heterostructure interface, but also improves the stability of the heterogeneous nanostructure via the in-situ growth of Co₃O₄ nanosheets. The hierarchical coaxial heterostructure of CoNWs@Co₃O₄ hybrids offers additional nucleation sites and abundant voids, which effectively accommodate the significant volumetric changes of Li and preserve the unique nano-micro structure. Various characterizations and density functional theory (DFT) simulations jointly validate that the unique hierarchical CoNWs@Co₃O₄ coaxial heterostructures enhances the adsorption of Li⁺ and inhibits the growth of Li dendrites. Benefiting from the distinctive hierarchical CoNWs@Co₃O₄ coaxial heterostructure, the CoNWs@Co₃O₄ symmetrical cell demonstrates a significantly extended and consistent lifespan of 2100 h at 1mA cm⁻² and 850 h at 5 mA cm⁻² with low overvoltage hysteresis. When paired with LiFePO₄ cathodes, the full cells exhibit excellent rate capacity, achieving a capacity retention of 88.5 % after 1000 cycles at 5C, holding promising potentials for practical applications. Overall, the design strategy for hierarchical coaxial heterostructures presented in this work offers new insight for the practical applications of LMBs in the future.