Cobalt‐based metal organic framework ( Co‐MOFs )/graphene oxide composites as high‐performance anode active materials for lithium‐ion batteries

Conventional graphene oxide cannot be directly used as an anode active material for lithium-ion batteries owing to its surface state and lithium-ion steric hindrance effect. To solve these problems, Co-MOFs/graphene oxide composite active materials are synthesized by a facile solvothermal method. Through X-ray diffraction and Raman spectrum analysis, Co-MOFs and graphene oxide can interact with each other in the composite material and the structure, defect concentrations and graphitization degree of graphene oxide have been affected to a certain impact. Scanning electron microscopy observes that when the mass ratio of Co-MOFs and graphene oxide is 1:1, this composite material shows more ideal and ordinal layered morphology. As anode active materials, they display electrochemical reaction characteristics of typical soft carbon and create abundant active sites with wide energy distribution and ameliorate the steric effect of graphene oxide on lithium ion. It also can be illustrated that the initial discharge specific capacities can achieve to 873.13, 795.41, 694.91 and 569.50 mAh·g−1 at 100, 200, 300 and 500 mA·g−1 current densities. After 500 cycles, capacity retention rates are 79.28%, 76.82%, 87.35% and 96.82% at 100, 200, 500 and 1000 mA·g−1 current densities. Electrochemical mechanism analysis shows that this Co-MOFs/graphene oxide composite active material shows a similar electrochemical reaction process of graphene oxide and Co-MOFs mainly play the role of optimizing the surface structure of graphene oxide and also supply a little capacity due to high specific capacity. Highlights Co-MOFs/graphene oxide composites are synthesized by a facile solvothermal method. Co-MOFs mainly play the role of optimizing the surface structure of graphene oxide. Anode using this composite material has a very high initial discharge specific capacity. This composite active material can stably charge and discharge for 500 cycles.