Promoting OH - Adsorption and Diffusion Enables Ultrahigh Capacity and Rate Capability of Nickel Sulfide Cathode for Aqueous Alkaline Zn-Based Batteries.

Aqueous alkaline Zn-based batteries (AAZBs) possess great promise for large-scale applications thanks to their higher discharging plateau and unique reaction mechanism. However, the capacity and rate capability of Ni-based cathodes are still unsatisfactory due to their insufficient OH - adsorption and diffusion ability. Herein, heterostructured Ni 3 S 2 /Ni(OH) 2 nanosheets with outstanding electrochemical performance are synthesized via a facile chemical etching strategy. The heterostructured Ni 3 S 2 /Ni(OH) 2 nanosheet cathode shows significantly increased capacity and rate capability due to its boosted OH - adsorption and diffusion ability compared to Ni 3 S 2 . Consequently, the assembled Zn//Ni 3 S 2 /Ni(OH) 2 cell can deliver an ultrahigh capacity of 2.26 mAh cm -2 , an excellent rate performance (0.91 mAh cm -2 at 100 mA cm -2 ) and a satisfying cycling stability (1.01 mAh cm -2 at 20 mA cm -2 after 500 cycles). Moreover, a prominent energy density of 3.86 mWh cm -2 is obtained, which exceeds the majority of recently reported AAZBs. This work is expected to provide a new modification direction for developing high-performance nickel sulfide cathode for AAZBs.