Modification of In-situ N-doped graphene coated ZnO composites as anode for high performance lithium-ion batteries

Abstract

The application of ZnO with high theoretical specific capacity as anode material for lithium-ion batteries is severely limited due to volume expansion during continuous cycling, slow lithium-ion diffusion, and poor conductivity. Here, ZnO nanoparticles were wrapped in N-doped multilayer graphene (ZnO@C) by chemical vapor deposition to improve specific capacity, rate performance, cycle stability, and conductivity. The thickness of the graphene layer and filling rate of ZnO in yolk-shell structure were investigated for the best electrochemical performance. The ZnO@C of yolk-shell structure with filling rate of 28% has a reversible specific capacity of 390 mAh/g after 200 cycles at 0.25 A/g, and achieves a capacity of 204.6 mAh/g at a high current of 1 A/g. The results show that N-doped porous graphene coated ZnO yolk-shell structure composites with etching treatment have good rate performance and cycle stability. The performance of electronic conductivity and lithium-ion diffusion is greatly improved, and the pseudocapacitive effect in the lithium storage mechanism is enhanced.