Copper Activation Enabling Reversible Aqueous Cu−ZnS Battery Chemistry
Chenqi Yao, Juanjuan Cheng, Chaoyong Ma, Zhiyong Tang, Yun Ou, Longfei Liu
Abstract
Abstract The aqueous metal‐sulfide batteries (AMSBs) have attracted research interest due to their high capacity, environmentally friendly qualities, and the accessibility of raw materials. However, the design strategies for metal‐sulfide cathode have rarely been reported. Here, the copper‐activated sphalerite in which Zn 2+ is substituted by Cu 2+ through ion exchange has been introduced for the first time as cathode for aqueous Cu/ZnS batteries. After sphalerite transformed to CuS, a two‐step conversion of CuS→Cu 7 S 4 →Cu 2 S storage mechanism has been proposed. At 0.7 A g −1 current density, the capacity can reach 532.4 mAh g −1 after 100 cycles. When cycled once at a current density of 35 mA g −1 , the initial reversible capacity can reach 461 mAh g −1 under 1 A g −1 . Furthermore, the assembled Zn//ZnS hybrid ion cell delivers an energy of up to 460 Wh kg −1 , which is better than for many AMSBs.