K+ alkalization promoted Ca2+ intercalation in V2CT MXene for enhanced Li storage

Although MXenes is highly attractive as anode materials of lithium ion batteries, it sets a bottleneck for higher capacity of the V2CTx MXene due to the limited interlayer space and the derived surface terminations. Herein, the cation intercalation and ion-exchange were well employed to achieve a K+ and Ca2+ intercalated V2CTx MXene. A larger interlayer distance and low F surface terminations were thereof obtained, which accelerates the ion transport and promotes the delicate surface of V2CTx MXene. As a result, a package of enhanced capacity, rate performance and cyclability can be achieved. Furthermore, the ion exchange approach can be extended to other 2D layered materials, and both the interlayer control and the surface modification will be achieved.