Graphene-based nanomaterials are extremely promising anode materials for sodium-ion batteries due to the interesting properties of graphene itself and the synergistic effect between graphene and active materials. However, two-dimensional graphene sheets only allow sodium ions to diffuse rapidly in the parallel direction, and vertical diffusion is difficult, which limits the rate capability of graphene-based electrode materials. To solve this problem, the researchers used pore forming engineering to perforate graphene while achieving in situ growth of Co3Se4 nanoparticles. The generation of in-plane nanopores breaks through the physical barrier of graphene nanosheets, allowing electrolyte ions to diffuse rapidly in the longitudinal direction. In addition, due to the high affinity of Co3Se4 for graphene, this design limits the aggregation of Co3Se4 nanoparticles. Due to the high conductivity and fast ion transport imparted by the ingenious structure, Co3Se4/porous graphene exhibits significant rate performance and good cycle stability of 519.5 mAh g-1 at 5.0 a g-1. The results show that the migration of sodium in graphene-based composites is crucial for improving the rate performance, and this method can effectively modify graphene-based nanomaterials into potential anode materials.
Graphic introduction
(a) Schematic diagram of the synthesis process of Co3Se4/HG. FE-SEM images of (b, e) co-precursor/reduced graphene oxide, (c, f) Co/HG and (d, g) Co3Se4/HG
(a, b) TEM images, (c, d) HR-TEM images, (e) HAADF-STEM images and EDS distribution corresponding to Co3Se4/HG.
(a) CV curve at 0.2 mV s-1; (b) GCD curve for Co3Se4/HG. (c) Cyclic performance and (d) rate performance of Co3Se4/HG and Co3Se4/rGO. (e) GCD profiles at different current densities Co3Se4/HG. (f) Comparison chart. (g) Long cycle performance of Co3Se4/HG and Co3Se4/rGO electrodes.
(a) CV curve, (b) log(i) vs. log(v), (c) contribution of capacitive Co3Se4/HG electrode at 0.2 mV s-1. (d) Capacitance contribution ratio of Co3Se4/HG and Co3Se4/rGO. (e) Nyquist curve, (f) line plot between Z′ and ω-1/2, (g) ITT curve for Co3Se4/HG and Co3Se4/rGO. (f) A single current pulse of voltage response over time in the process. (g) Sodium ion diffusion coefficients of Co3Se4/HG and Co3Se4/rGO.
Dissertation information
Link to paper: https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.202207752
Communication unit: China University of Geosciences
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