All‐Climate Long‐Life and Fast‐Charging Sodium‐Ion Battery using Co₃S₄@NiS₂ Heterostructures Encapsulated in Carbon Matrix as Anode

Abstract

Abstract Sodium‐ion (Na‐ion) battery is one of the research focuses because of high theoretical capacity and low cost. However, seeking for ideal anodes remains a big challenge. Here, a Co 3 S 4 @NiS 2 /C synthesized by in situ growing NiS 2 on CoS spheres then converting to Co 3 S 4 @NiS 2 heterostructures encapsulated by carbon matrix, is developed as a promising anode. Co 3 S 4 @NiS 2 /C as anode displays a high capacity of 654.1 mAh g −1 after 100 cycles. Even over 2000 cycles at a high rate of 10 A g −1 , capacity exceeds 143.2 mAh g −1 . Heterostructures between Co 3 S 4 and NiS 2 improve electron transfer as verified by density functional theory (DFT) calculations. In addition, when cycling at a high temperature of 50 °C, the Co 3 S 4 @NiS 2 /C anode displays 525.2 mAh g −1 , while it remains 340 mAh g −1 at −15 °C, indicating all‐climate potential for using under different temperatures.