Reduced graphene oxide supported ZIF-67 derived CoP enables high-performance potassium ion storage

Abstract

Potassium-ion batteries (PIBs) are currently recognized as an emerging battery technology because of the rich resources and low cost of potassium. Nevertheless, investigations on exploiting suitable anode materials to meet stable potassium-ions storage remain to be a problem owing to the big radius size of potassium-ions. Herein, we designed N-doped carbon restricted CoP polyhedra embedded into reduced graphene oxide (rGO) sheet (CoP/NC@rGO) through coupling the function of ZIF-67 and rGO. For this composite, nano-scale CoP particles can be encapsulated by ZIF-67 derived carbon matrix, which significantly alleviates the volume change and promotes K+/e− transfer. Additionally, the combination of CoP/NC polyhedra and rGO nanosheets can build a fascinating 3D architecture to further improve the electronic conductivity of materials, as well as effectively preventing the aggregation of CoP/NC polyhedra. As a result, such composites can exhibit remarkable long-cycle performance, maintaining remarkable capacities of 177 mAh g−1 after 2800 cycles at 1 A g−1. This work provides a hopeful strategy that the combination of MOF-derived porous structures with rGO can effectively promote K+/e− transfer and improve the stability of electrode materials.