MOF-derived transition metal oxide encapsulated in carbon layer as stable lithium ion battery anodes

Abstract

Abstract Transition metal oxide (TMO) is an important type of conversion reaction anode for lithium ion batteries. Carbon encapsulated zinc oxide and cobalt oxide (ZnO@C, Co3O4@C) were prepared via a MOF-derived strategy. MOF precursors were firstly coated with polypyrrole (PPy) layer and then subjected to subsequent thermal treatment. Benefiting from the synergetic effect of conductive coating layer and 3D porous structure, both anodes showed attractive electrochemical performance. The ZnO@C and Co3O4@C delivered a reversible capacity of 526 and 721\u202fmAh∙g−1 after 500 cycles at 250\u202fmA\u202fg−1. With attractive rate performance, the ZnO@C and Co3O4@C have an average capacity of 301 and 306\u202fmAh∙g−1 at 2.0\u202fA\u202fg−1. Kinetic analysis revealed that lithium ion storage in both ZnO@C and Co3O4@C were dominated by a surface controlled pseudo-capacitive process. In addition, ZnO@C and Co3O4@C could even stably cycle for 1000 times at a high current density of 2.0\u202fA\u202fg−1.