Abstract:
Over the past few decades, lithium-ion batteries (LIBs) have attracted extensive interests in energy storage devices due to their high energy density, long cycle life and environmental friendliness. However, the low specific capacity of conventional anode materials restricts the commercial applications of LIBs. Therefore, it is crucial to develop advanced electrodes for next-generation LIBs to meet the increasing energy requirements. Metal-organic frameworks (MOFs) are potential candidates for anode materials due to their high surface area, controlled pore size and structural diversity, but their poor conductivity and easy aggregation often result in the decline of electrochemical performances of LIBs. To further improve the overall performances of MOF as anode materials for lithium ion batteries, an approach involved electrostatic attraction and chemical liquid deposition was developed to fabricate CoNi-MOF/RGO composite nanoflakes using reduced graphene oxide (RGO) as substrate, cobalt chloride and nickel chloride as precursors, and benzenedicarboxylic acid as organic ligands. The addition of RGO not only induced the structural transformation of CoNi-MOF from cross-linked lamellae to two-dimensional nanoflakes, but also enhanced the conductivity of CoNi-MOF/RGO composite. Subsequently, the coin type lithium ion battery was assembled by using CoNi-MOF/RGO as anode materials. The electrochemical tests indicated that the obtained CoNi-MOF/RGO electrode possessed a high charge specific capacity of 747 mA·h/g at a current density of 0.2 A/g after 100 cycles. Even at a high current density of 5.0 A/g, a high capacity of 289 mA·h/g was still achieved, which is much higher than that of CoNi-MOF, demonstrating its excellent electrochemical performances.