BiOIO<sub>3</sub>@Zn<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>·4H<sub>2</sub>O Heterojunction with Fast Ionic Diffusion Kinetics for Long-Life “Rocking-Chair” Zinc Ion Batteries
Yuzhu Qian, Xinni Li, Hongrui Wang, Ting Song, Yong Pei, Li Liu, Xianyou Wang, Qi Deng, Xiongwei Wu, Bei Long
Abstract
Increasing insertion host materials are developed as high-performance anodes of “rocking-chair” zinc ion batteries. However, most of them show unsatisfactory rate capabilities. Herein, layered BiOIO 3 is reported as an excellent insertion host and a zinc ion conductor, i.e., Zn 3 (PO 4 ) 2 ·4H 2 O (ZPO), is introduced to construct a BiOIO 3 @ZPO heterojunction with a built-in electric field (BEF). Both ZPO and a BEF obviously enhance Zn 2+ transfer and storage, which is proven by theoretical calculations and experimental studies. The conversion-type mechanism of BiOIO 3 is revealed through ex situ characterizations. The optimized electrode exhibits a high reversible capacity of 130 mAh g –1 at 0.1 A g –1, a low average discharge voltage of 0.58 V, an ultrahigh rate performance with 68 mAh g –1 at 5 A g –1 (52% of capacity at 0.1 A g –1 ), and an ultralong cyclic life of 6000 cycles at 5 A g –1 . Significantly, the BiOIO 3 @ZPO//Mn 3 O 4 full cell shows a good cyclic life of 67 mAh g –1 over 1000 cycles at 0.1 A g –1 . This work provides a new insight into the design of anodes with excellent rate capability.