Heterostructured Co3Se4/CoSe2@C nanoparticles attached on three-dimensional reduced graphene oxide as a promising anode towards Li-ion batteries

In situ carbon-coated Co₃Se₄/CoSe₂ (CO_xSe_y) nanoparticles (NPs) attached on three-dimensional (3D) reduced graphene oxide (rGO) sheets were skillfully developed in this work, which involved the environment-friendly hydrothermal method, freeze drying, and selenide calcination. Within the structure, the glucose-derived carbon layer exhibited significantly homogeneous dispersion under an argon environment. This structure not only has enhanced stability, but also can effectively mitigate the volume swell of Co_xSe_y particles. The resulted Co₃Se₄/CoSe₂@C/rGO (CSe@C/rGO) exhibited a specific surface area (SSA) of 240.9 m²·g⁻¹, offering more electrochemically active sites for the storage of energy related to lithium ions. The rGO matrix held exceptional flexibility and functional structural rigidity, facilitating the swift ion intercalation and ensuring the high conductivity and recyclability of the structure. When applied to anodes designed for lithium-ion batteries (LIBs), this material demonstrated distinguished rate and ultra-high reversible capacity (872.98 mA·h·g⁻¹ at 0.5 A·g⁻¹). Meanwhile, its capacity retention reached 119.5% after 500 cycles at 2 A·g⁻¹, with a coulombic efficiency of 100%. This work potentially paves the way for generating fast and powerful metal selenide anodes and initiating LIBs with good performance.