Caged biomass carbon with anchoring MoO2/NC Nanospheres: Synergistic enhancement of potassium ion storage and electrochemical performance

Abstract

Due to its relatively high theoretical capacity and low cost, transition metal oxides are considered as candidate anodes for potassium ion batteries (KIB). However, poor recyclability due to inherently large volume changes hinders their application. Therefore, we use Ganoderma spores as the carbon matrix to synthesize MoO2/N/C composites through simple complexation reactions. It was found that the synergistic effect of cage-like biomass carbon and molybdenum oxide can promote the transfer and adsorption of potassium ions, thereby improving the storage capacity of potassium ions. On the one hand, the introduction of a small amount of MoO2 greatly enhances the potassium storage capacity of biomass carbon materials. On the other hand, the porous cage-like carbon structure effectively buffers the volume change during the MoO2 potassium storage process and provides more diffusion paths for K+. In addition, the stable double-walled cage structure provides the possibility for the composite material to achieve good long-cycle performance. Specifically, MoO2/N/C composites provided a high reversible specific capacity of 422 mAh g−1 (after 200 cycles) at 200 mA g−1, and coulombic efficiency was greater than 98%. The composites still provided a high capacity of 316 mAh g−1 after 500 cycles at 500 mA g−1. At the same time, after 1500 cycles at 2000 mA g−1, the capacity was maintained at 248 mAh g−1. Verify the possibility of its practical application by assembling a full battery, meanwhile, through first-principles calculations, the reasons for the excellent potassium storage performance of MoO2/N/C electrodes are discussed.