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

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 Co3S4@NiS2/C synthesized by in situ growing NiS2 on CoS spheres then converting to Co3S4@NiS2 heterostructures encapsulated by carbon matrix, is developed as a promising anode. Co3S4@NiS2/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 Co3S4 and NiS2 improve electron transfer as verified by density functional theory (DFT) calculations. In addition, when cycling at a high temperature of 50 °C, the Co3S4@NiS2/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.