Electrochemical activation of MnS as an efficient conversion-type Cu2+ storage electrode

Electrochemical activation can turn inactive materials into active materials in situ for energy storage facilely, controllably and efficiently, which makes metal sulfides feasible for Cu²⁺ storage based on electrochemical activated into CuS. Among common heavy metal sulfides, MnS has the highest solubility product and high Cu²⁺ adsorption and exchange rate in the copper removal by vulcanization in nickel electrolytic anodic solution. Here, MnS is electrochemical activated in situ in aqueous Cu-ion battery, and the effects of crystal structure and particle size on the electrochemical activation of MnS were revealed. The results show that both α, γ-MnS can be electrochemical activated, and activation cycling number is related to the particle size of MnS. When the MnS particle size is ball-milled small enough (1–2 μm), MnS will be completely transformed into CuS during the first discharge process, and then CuS↔Cu₂S will participate in the reversible conversion reaction for copper storage. When the MnS particle size is larger (> 10 μm), the α-MnS electrode capacity gradually increases and becomes stable after 30 cycles, and the capacity remains at 458.6 mAh g^–1 after 300 cycles.