Entrapping polyiodide by using highly N, P co-doping porous carbon framework towards high performance zinc-iodine batteries

Rechargeable aqueous zinc-iodine batteries (ZIBs) with low environmental impact and abundant natural reserves have become promising electrochemical energy storage devices. However, the shuttle effect and low conductivity lead to poor electrochemical performance, hindering their practical applications. Herein, a (NH4)3PO4-activated ZIF-8-derived porous carbon (NPPC) is proposed for entrapping iodine species in ZIBs. Benefiting from its abundant porous structure and highly conductive framework, the iodine loading and electron transport of NPPC is greatly enhanced. In addition, the in-situ doping multiple heteroatoms (N, P and O) in the carbon framework can also establish chemical anchoring with iodine species and hence mitigate the shuttle effect. As a result, the ZIBs prepared by the NPPC-1.5/I2 electrode achieves an ultra-high specific capacity of 175 mAhg- 1 at 0.1 A g- 1, and a specific capacity of 95 mAh g- 1 at a high current density of 10 A g- 1. An extremely stable cycle performance of 97 % capacity retaining after 6000 cycles at 10 A g- 1 is also obtained. This study provides a new strategy for realizing aqueous ZIBs with high capacity and long cycling life.