Bioio3@Zn3(Po4)2·4h2o Heterojunction with Fast Ionic Diffusion Kinetics for Long-Life “Rocking-Chair” Zinc Ion Battery

Abstract

Increasing insertion host materials are developed as the high-performance anodes of “rocking-chair” zinc ion batteries. However, most of them show unsatisfactory rate capabilities. Herein, the layered BiOIO 3 is reported as an excellent insertion host and the zinc ion conductor i. e. Zn 3 (PO 4 ) 2 ·4H 2 O (ZPO) is introduced to construct BiOIO 3 @ZPO heterojunction with build-in electric field (BEF). Both ZPO and BEF enhance Zn 2+ transfer and storage obviously, which is proved 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 anode with excellent rate capability.

Keywords: BiOIO3@Zn3(PO4)2·4H2O heterojunction, build-in electric field, conversion-type anode, fast ionic diffusion, "rocking-chair" zinc ion battery