Influence of ZIF-9 and ZIF-12 structure on the formation of a series of new Co/N-doped porous carbon composites as anode electrodes for high-performance lithium-ion batteries.

A series of new Co/N-doped porous carbon composites, denoted as Co/CZIF-9 and Co/CZIF-12, containing Co nanoparticles encapsulated in nitrogen-doped carbon matrices were prepared by annealing Co-based zeolite imidazolate framework materials, ZIF-9 and ZIF-12, as the efficient precursors at different temperatures. The structural features of the as-synthesized composites at 900 °C were determined by analytical methods with high reliability. Consequently, Co/CZIF-12_900 exhibits a high first specific discharge capacity of 971.0 mA h g at a current density of 0.1 A g. Notably, the specific discharge/charge capacity of Co/CZIF-12_900 reaches about 508.8 mA h g at 0.1 A g after 100 cycles. The outstanding behaviors can be accounted for by the efficient incorporation of hetero-nitrogen doping and the Co nanoparticles within the layered structure of porous carbon, enhancing electrical conductivity and structural stability and limiting volume change during the intercalation/deintercalation of Li ions. These findings suggest that the Co/CZIF-12_900 material could be employed as a promising anode electrode for energy storage products.