Hierarchical Co2VO4 yolk-shell microspheres confined by N-doped carbon layer as anode for high-rate lithium-ion batteries

Abstract

The design of high-performance anodes is crucial for the whole for lithium-ion batteries (LIBs). Binary transition metal oxides (bi-TMOs), especially cobalt vanadates featuring high theoretical lithium storage capacity endow them promising anode materials. However, low electric conductivity as well as tremendous volume change occurring during the process of de−/lithiation restrict their commercialization. Herein, the as-devised novel spinel Co2VO4 yolk-shell microspheres coated with nitrogen-doped carbon shell (Co2VO4@NC) were synthesized by the method of a self-templated solvothermal preparation and following in-situ pyrolysis of polydopamine (PDA) film, which demonstrates excellent properties as anode for LIBs by virtue of the unique spinel structural characteristics, mixed lithium storage mechanism, micro/nanolization of the yolk-shell structure and vital amorphous NC component. In detail, the unique Co2VO4@NC electrode displays the high Li ion storage capacity (1255 mAh g−1 at 0.2 A g−1), the superior cycling stability (1227 mAh g−1 at 0.5 A g−1 after 400 cycles) as well as outstanding reversible capability (remaining 862 mAh g−1 when return to 0.1 A g−1 from 5 A g−1, larger than initial 796 mAh g−1).