Homologous MXene-Derived Electrodes for Potassium-Ion Full Batteries

The development of potassium-ion battery (PIB) electrode materials is critical for promoting their use in next-generation energy storage systems. Although metal-organic frameworks (MOFs) are appealing electrode materials, their performance in PIBs remains unsatisfactory. The low K+ adsorption energy (Delta E-a) on the saturated coordination of MOFs can explain the limited capacity. Herein, MXene-derived MOF nodes (NMD-MOF) are unlocked and used as anodes in PIB. The NMD-MOF anode exhibits substantially increased capacity (250 mA h g(-1) at 0.05 A g(-1)), as well as good rate-performance and excellent capacity retention. Density functional theory calculations reveal that the Delta E-a at unlocked node sites is significantly higher than at intact node sites of the pristine MOF. Furthermore, the NMD-MOF anode and homologous MXene-derived K+-intercalated vanadium oxide (MD-KVO) cathode combine to assemble a PIB, which delivers an encouraging capacity of 63 mA h g(-1) at 50 mA g(-1) and high energy (143 Wh kg(-1)) and power density (440 W kg(-1)). The fabrication of MXene-derived electrode materials and the unlocking node strategy for binding site activation may spur further research into highly active electrode materials for energy storage devices.