Converting commercial BiO particles into BiOSe@BiOSe nanosheets for "rocking chair" zinc-ion batteries.

The development of a low-cost, high-capacity, and insertion-type anode is key for promoting "rocking chair" zinc-ion batteries. Herein, commercial BiO (BiO) particles are transformed into BiOSe@BiOSe (BiOSe) nanosheets through a simple selenylation process. The change in morphology from commercial BiO particle to BiOSe nanosheet leads to an increased specific surface area of the material. The enhanced electronic/ionic conductivity results in its excellent electrochemical kinetics. Ex situ XRD and XPS tests prove the intercalation-type mechanism of BiO and BiOSe as well as the superior electrochemical reversibility of BiOSe compared to BiO. Furthermore, the H/Zn co-insertion mechanism of BiOSe is revealed. This makes BiOSe to have low discharge plateaus of 0.38/0.68 V, a high reversible capacity of 182 mA h g at 0.1 A g, and a long cyclic life of 500 cycles at 1 A g. Besides, the BiOSe//MnO "rocking chair" zinc-ion battery offers a high capacity of ≈90 mA h g at 0.2 A g. This work provides a reference for turning commercial material into high-performance anode for "rocking chair" zinc-ion batteries.