Self-Repairing Function of Ni3S2 Layer on Ni Particles in the Na/NiCl2 Cells with the Addition of Sulfur in the Catholyte.

The role of the Ni3S2 layer on Ni particles in the electrochemical performance of Na/NiCl2 cells with the addition of sulfur into the cathode is studied. It was found that the Ni3S2 layer could be in situ generated on nickel particles and exhibit a self-repairing function during cycling when sulfur exists in the cathode due to the reaction between the sulfur and nickel particles. The self-repairing function of the Ni3S2 layer could enhance the blocking effect and improve the battery cycle performance. The capacity of the cell with the optimum amount of sulfur (with self-repairing function) after 50 cycles is about 12% greater than that of the cell with the optimum level of Ni3S2 (without self-repairing function). The effect of the self-repairing function of the Ni3S2 layer is determined by the amount of sulfur in the cathode.