Hansen Solubility\nParameter-Guided Solvent Selection\nfor Solution-Phase Discharge in Li-CO<sub>2</sub> Batteries

Surface\ndischarge mechanism-induced cathode passivation is a critical\nchallenge that blocks the full liberation of the ultrahigh theoretical\nenergy density of Li-CO<sub>2</sub> batteries. Herein, we propose\na novel concept based on Hansen solubility parameters (HSPs) to guide\nthe selection of solvents for inducing the dissolution of discharge\nproducts, facilitating the detachment of in situ-formed metastable\nLi<sub>2</sub>C<sub>2</sub>O<sub>4</sub> from the electrode surface\nand enabling a continuous Li<sub>2</sub>C<sub>2</sub>O<sub>4</sub>-dominated discharge process. Combining theoretical calculations\nwith HSP predictions, we identified Pd-OCNTs as an ideal catalyst,\nwith tetraethylene glycol dimethyl ether as the optimal solvent for\nLi<sub>2</sub>C<sub>2</sub>O<sub>4</sub> production and stabilization.\nThis combination facilitates the rapid diffusion of Li<sub>2</sub>C<sub>2</sub>O<sub>4</sub> generated in situ near the catalyst surface\nout of the inner Helmholtz layer. Consequently, the system exhibits\nhigh energy efficiency of 96.7% and remarkable stability over 3200\nh. This work provides critical insights into the solution-mediated\ndissolution process of Li<sub>2</sub>C<sub>2</sub>O<sub>4</sub>, informing\nstrategies for multiphase interfacial reactions in Li-CO<sub>2</sub> batteries.