Zn and Cl Coregulated MXene Catalyst Enhances Li-CO2 Battery Reversibility

MXenes are promising cathodes for Li–CO2 batteries owing to their high electrical conductivity and efficient CO2 activation function. However, the effects of adsorption and electronic structures of MXene on the full life cycle of Li–CO2 batteries have been rarely investigated. Here, we employ a coregulation approach to enhance the adsorption–decomposition of lithium carbonate (Li2CO3) by introducing Zn and Cl surface groups onto the Ti3C2 MXene (Zn–Ti3C2Cl2) catalyst. The incorporation of Cl surface groups enhances Li2CO3 adsorption on the MXene catalyst surface, resulting in the formation of small-sized and uniform Li2CO3. Additionally, the introduction of Zn shifts the d-band centers of titanium and promotes CO2 evolution reaction (CO2ER) activity, thereby facilitating the decomposition of discharge products. As a result, the Li–CO2 battery based on the Zn–Ti3C2Cl2 catalyst exhibits an ultralow overpotential (0.72 V) at 200 mA g–1 and stable cycling for up to 1500 h. This work validates the efficacy of promoting reversibility in Li–CO2 batteries by adjusting the adsorption-decomposition process.