Mediating iodine cathodes with robust directional halogen bond interactions for highly stable rechargeable Zn-I2 batteries

The ease of I-2 sublimation and dissolution into aqueous electrolyte media impedes the validity for the further utilization of rechargeable Zn-I-2 batteries. To overcome such constraints, we herein put forward a valid strategy by strengthening interactions between I and host reservoirs with -I center dot & nbsp;center dot & nbsp;center dot & nbsp;Y-halogen bonds (Y refers to O, S, N etc.). Distinct vibrational shifts in spectroscopy detections and markedly elevated thermostability have verified the presence of halogen bonds bridged between I-2 and biomass-evolved graphitic/porous carbon microtubes (GPCMTs). Notably, GP-CMTs exhibit far more robust I-2/I--anchoring ability than conventional carbon hosts, capable of preventing undesired actives dissolution. The derived I-2@GP-CMTs cathodes show an output capacity of 285 mAh g(-1), good Columbic efficiency, salient rate capabilities (101 mAh g(-1) at 12 A g(-1)) and cyclic durability (86.8% capacity retained after 10(3 )cycles). In-situ Raman detection affirms the cathode charge storage relies on direct reversible I -/I-2 transition, and operando microscope observations reveal there exist paralleled changes in electrolyte phase. Packed full cells also show excellent cyclic behaviors, suppressed self-discharge rate and impressive energy density. Our work offers a fresh/effective strategy to upgrade electrode systems, for not only metal-I batteries but also other prototype cells with similar kinetic issues.

Automated summary

This study proposes a strategy to enhance the interactions between I and host reservoirs in order to prevent the dissolution of I-2 into the electrolyte, thereby enabling the effective utilization of rechargeable Zn-I-2 batteries. The formation of halogen bonds between biomass-evolved graphitic/porous carbon microtubes (GPCMTs) and I-2 is shown to improve the performance of the batteries.