Fabrication and theoretical investigation of cobaltosic sulfide nanosheets for flexible aqueous Zn/Co batteries

ABSTRACT Flexible and recyclable zinc-based batteries have been hot research topics due to their high discharge platform, safety, and low cost. However, most research on zinc-based batteries put their attention on metal oxides as the cathode, such as manganese dioxide (MnO2), cobaltosic oxide (Co3O4), nickel oxide (NiO), etc. Very few studies use metal sulfides as electrode materials and focus on its mechanism based on theoretical analysis. Hence, in this work, we firstly used cobaltosic sulfide (Co3S4) nanosheets grown on Ni foam (CSNSs/NF) as an electrode material for zinc-based batteries. Both first-principles calculations and experimental results reveal that S plays a crucial role in the capacitive activity and electrical conductivity enhancement for Co-based materials. The Zn//CSNSs/NF battery provides a high specific capacity of 317 mAh g-1 at a current density of 1 A g-1. Furthermore, it also displays an impressive energy density of 507 Wh kg-1 and a long cycling performance. Impressively, the Zn//CSNSs/NF battery has high flexibility and can work well under different deformations. This work not only provides a new member of cathode materials in zinc-based batteries, but also opens new opportunities for powering portable and wearable electronics.