Carbon-coated CoSe2 nanoparticles confined in N-doped carbon microboxes with enhanced sodium storage properties

Abstract

Due to their high theoretical specific capacity, CoSe₂-based anode materials have attracted enormous attention for sodium storage. However, the poor cycling stability and rate capability still hinder their application. Herein, starting from Co₃[Co(CN)₆]₂ Prussian blue analogue microcubes, a facile template-engaged strategy is developed to design and synthesize nanostructured dual-carbon-confined CoSe₂ (denoted as DCC-CoSe₂) microcubes. In this unique nanostructure, N-doped carbon-coated CoSe₂ nanoparticles are confined in N-doped carbon microboxes. Benefiting from the desired structural features, the as-synthesized DCC-CoSe₂ microcubes exhibit enhanced sodium storage properties in terms of high specific capacity (480 mA h g⁻¹), excellent cycling stability (94.5% capacity retention over 2000 cycles), and superior rate capability (281 mA h g⁻¹ at 20 A g⁻¹). The assembled full cell with DCC-CoSe₂ microcubes as the anode material and Na₃V₂(PO₄)₃ as the cathode material can deliver a high initial capacity of 427 mA h g⁻¹. This work provides a new strategy for the rational design and synthesis of high performance metal selenide-based anode materials for sodium storage.