Zn and Cl Coregulated\nMXene Catalyst Enhances Li-CO<sub>2</sub> Battery Reversibility

MXenes\nare promising cathodes for Li–CO<sub>2</sub> batteries\nowing to their high electrical conductivity and efficient CO<sub>2</sub> activation function. However, the effects of adsorption and electronic\nstructures of MXene on the full life cycle of Li–CO<sub>2</sub> batteries have been rarely investigated. Here, we employ a coregulation\napproach to enhance the adsorption–decomposition of lithium\ncarbonate (Li<sub>2</sub>CO<sub>3</sub>) by introducing Zn and Cl\nsurface groups onto the Ti<sub>3</sub>C<sub>2</sub> MXene (Zn–Ti<sub>3</sub>C<sub>2</sub>Cl<sub>2</sub>) catalyst. The incorporation of\nCl surface groups enhances Li<sub>2</sub>CO<sub>3</sub> adsorption\non the MXene catalyst surface, resulting in the formation of small-sized\nand uniform Li<sub>2</sub>CO<sub>3</sub>. Additionally, the introduction\nof Zn shifts the <i>d</i>-band centers of titanium and promotes\nCO<sub>2</sub> evolution reaction (CO<sub>2</sub>ER) activity, thereby\nfacilitating the decomposition of discharge products. As a result,\nthe Li–CO<sub>2</sub> battery based on the Zn–Ti<sub>3</sub>C<sub>2</sub>Cl<sub>2</sub> catalyst exhibits an ultralow\noverpotential (0.72 V) at 200 mA g<sup>–1</sup> and stable\ncycling for up to 1500 h. This work validates the efficacy of promoting\nreversibility in Li–CO<sub>2</sub> batteries by adjusting the\nadsorption-decomposition process.