Graphene-supported Ni-based polyoxometalate anode material and its electrochemical performance

The energy crisis is currently an important issue of global concern. Lithium-ion battery (LIB) has become the most popular new energy technology due to its high energy density, good cycle life, and environmental friendliness. Although the commercial carbon anode can effectively reduce the formation of lithium dendrites, it still fails to meet the increasing demand for energy storage density. Therefore, designing and synthesizing new electrode materials for LIB is one of the key issues to break the bottleneck of high-energy LIB. In this work, a graphene-supported polyoxometalate-organic framework material (Ni-POMs) was successfully synthesized and used for the anode of LIB. Scanning electron microscopy (SEM) analysis showed that Ni-POMs material has a regular hexagonal prism shape, and X-ray diffraction (XRD) test results showed that the diffraction peak of the experimental samples were consistent with computer simulated one. After the graphene was loaded, the morphology of its sample was partially damaged, but the hexagonal prism shape could still be observed. At a current density of 100 mA/g, the specific discharge capacity of Ni-POMs could reach 717 mAh/g after 50 cycles. At a current density of 800 mA/g, a capacity retention rate of 82.2% could be maintained after 500 cycles. After graphene loaded, the cycle performance and rate performance of Ni-POMs@GO materials further improved. The material cycle stability of Ni-POMs@GO electrode mainly attributes to its unique porous characteristics and high chemical stability. Loaded graphene provides an electron transport channel for the materials, which further improves its electrochemical performance.