Nanoporous CoSe2 Polyhedron Imbedded Graphene as a Highperformance Sodium-ion Battery Anode Material

Sodium-ion batteries (SIBs) emerge as a promising candidate with the virtue of abundant sodium resources and low costs of sodium salts. CoSe₂ as the anode material has attracted much attention because of its high theoretical capacity. However, the low conductivity of CoSe₂ severely still hinder their application. Herein, we fabricated a graphenecrosslinked CoSe₂ polyhedron composite material (CoPG) by utilizing graphene as the conductive framework and MOFderived CoSe₂ as the active component for energy storage. The carbon layer derived from MOF can effectively inhibit polyselenide dissolution and, in combination with graphene, construct a double-carbon-layer conductive network that facilitates electron transport. As a result, the as-prepared CoPG3 can deliver a high reversible capacity of 565 mAh g^-1 at 0.05 C. After 100 cycles, its capacity is remained 87% at 0.5 C. This work provides a new insight to the relationship between the conductivity and performance of electrode materials for SIBs.