Three-dimensionally hierarchical Co3O4/Carbon composites with high pseudocapacitance contribution for enhancing lithium storage

Abstract

Transition metal oxides (TMDs) have large theoretical capacity as anode materials for lithium ion batteries (LIBs), but this merit is difficult to achieve in the process of practical application. Some researches demonstrated that increasing pseudocapacitive lithium storage is an effective method to improve the performance of TMDs. Herein, we reported a facile strategy to synthesize 3D porous carbon network (3DCN) encapsulating cobalt oxides (Co3O4) nanoparticles coated within N-doping carbon (NC) composites by pyrolysis followed oxidation process of ZIF/3DCN precursor. Benefiting from the synergistic effect of ultrasmall Co3O4 particles, hierarchical porosity, high specific surface area, mechanical integrity and high electrical conductivity, the Co3O4@NC/3DCN electrode exhibits a large discharge capacity of 1208 mAh g−1 after 100 cycles at 100 mA g−1 and superior high-rate performance (reached to 539 mAh g−1 at 10 A g−1), and the long cycling reversible capacities of 901 mAh g−1 and 516 mAh g−1 can be maintained after 400 cycles at 1000 and 5000 mA g−1, respectively. More importantly, the electrochemical kinetic analysis of Co3O4@NC/3DCN electrode indicates that the lithium storage is a dominant capacitive process. This method can be easily extended to prepare other transition-metal oxides/carbon composites for the application of excellent performance electrodes with high pseudocapacitive contribution in LIBs.