RESUMO
Metal-organic frameworks (MOFs) with diverse structures have been projected as futuristic electrode materials for lithium-ion batteries (LIBs). In this work, two ternary Li-Co-MOFs of three-dimensional (3D) porous structures were synthesized, inspired by LiCoO2 inorganic metal salts, through a simple solvothermal method and further applied as active cathode materials for the first time in lithium-ion batteries. In these MOF structures, the lithium atoms are located at the same (SNNU-73) or different (SNNU-76) sites as cobalt atoms, and the four-coordinated tetrahedron mode is used to coordinate with the oxygen atoms. The 3D porous frameworks provide a good channel for the embedding and de-embedding of lithium ions. The experimental results suggest that porous Li-Co-MOF ternary composites show excellent cycling stability. Particularly, the discharge capacity and average coulombic efficiency of SNNU-73 reach 155.6 mA h g-1 and nearly 100% for 50 cycles at a rate of 50 mA g-1. This synergistic effect of mixed Li and Co sites demonstrates great potential of MOFs as advanced electrode materials, and provides a promising route to designing porous materials for lithium-ion batteries in the future.