Yujing Liu, Qi Liu, Chengyao Zhao, Liping Liu, Zhongqiu Liu, Anguo Ying*, Zhibin Pang *,Xuping Sun*, Pu Chen*, and Guang Chen*. Defect-driven Oxidation Enabled V₂CT_x MXene with Ultralong-Cycling and High-Rate Capability in Aqueous K⁺ Storage. Adv. Funct. Mater. 2024, accept.

Abstract: Owing to the adverse influences of irreversibleoxidation, the development of MXene-basedmaterials, especially those with satisfactory performance and longevity for aqueous energy storage, continues to suffer severe challenges.Herein, we conceived the strategy of targetedpassivation-supported defect-lock-oxygen, whereby engineered the V₂CT_x material for the controllable partial oxidation with enhanced regioselectivity. When the material works, inside the intrinsic defects, the outward diffusion of oxidation is confined by the Lewis bases around the defects, which allows for the controllable progress of oxidation. The defect-locked oxygen oxidizes the exposed carbon, thus forming the sufficient amorphous carbons for enhancing the capacitivetype adsorption of K-ions. Then the oxidized defects enabled the fast kinetics via the cross-layer transport of K-ions. Benefiting from the strategy, the electrode assembly V₂CT_x-RTIL (V₂CT_x equipped with room temperature ionic liquid) exhibits high capacity, good rate capability, and ultra-longevity compared with those of the MXene materials so far reported. This work presents the first strategy of targeted passivation-supported defect-lock-oxygen for high-Rate capability and super long-cycling aqueous K⁺ storage, and hopefully would provide the inspiration for the future design of novel electrodes.

Keywords: Defect lock oxygen, Confinement oxidation, Targeted passivation, Longevity lifespan