Synergistic effect of Cu-La0.96Sr0.04Cu0.3Mn0.7O3-δ heterostructure and oxygen vacancy engineering for high-performance Li-CO2 batteries

•Heterostructure interface consisting of exsolved Cu NPs and porous LSCM perovskite nanofibers is designed.•Synergistic effects of heterostructure and oxygen vacancy engineering are achieved.•Li-CO2 battery yields a high discharge capacity (11350 mAh g−1) and prolonged cycle lifespan (107 cycles). Li-CO2 battery is the most promising energy storage system to realize carbon-neutral energy circulation. Developing efficient, cost-effective and stable bifunctional electrocatalysts toward carbon dioxide reduction and carbon dioxide evolution reactions (CO2RR and CO2ER) is highly essential for the application of Li-CO2 battery. Herein, we explore the catalytic ability of Cu-LSCM (La0.96Sr0.04Cu0.3Mn0.7O3-δ) heterostructure in Li-CO2 battery. The LSCM perovskite substrate can provide abundant oxygen vacancies facilitating the movement of CO2 and ions. The in-situ exsolved Cu NPs ensure a strong intercalation with the perovskite and then deliver superiority catalytic activity, durability, and considerable conductivity. Accordingly, the catalyst exhibits excellent CO2RR and CO2ER activity (peak current densities: 0.4 mA cmcathodic−2, 0.22 mA cmanodic−2) in nonaqueous media. Benefiting from the mesoporous nanofiber architecture accelerating the deposition and decomposition of Li2CO3, the Li-CO2 battery with Cu-LSCM heterostructure delivers an ultrahigh discharge capacity of 11350 mAh g−1, low voltage gap of 1.35 V, and prolonged cycle lifespan of 107 cycles (restricted capacity of 1000 mAh g−1, 400 mA g−1) without obvious degradation. This work demonstrates the synergistic effect between the metal nanoparticles and perovskite oxide in the hybrid heterostructures, and exemplifies the bifunctional catalysts for Li-CO2 battery. [Display omitted]