Sodium-based dual-ion batteries via coupling high-capacity selenium/graphene anode with high-voltage graphite cathode

Abstract Dual ion batteries (DIBs) exhibit broad application prospects in the field of electrical energy storage (EES) devices with excellent properties, such as high voltage, high energy density, and low cost. In the graphite-based DIBs, high voltage is needed to store enough anions with the formation of anion intercalation compound XCn (X = AlCl4-, PF6-, TFSI-, etc.). Hence, it is difficult for graphite-based DIBs to match proper anodes and electrolytes. Here, an Se/graphene composite is prepared via a convenient method, and assembled into a dual-ion full battery (DIFB) as anode with graphite cathode and 1 mol/L NaPF6 in EC:EMC (1:1, v:v). This DIFB has achieved a high discharge capacity of 75.9 mAh/g and high medium output voltage of 3.5 V at 0.1 A/g. Actually, the suitable anode materials, such as the present Se/graphene composite, are extremely important for the development and application of graphite-based DIBs. This study is enlightening for the design of future low-cost EES devices including graphite-based DIBs.