Solid Interhalogen Compounds with Effective Br0 Fixing for Stable High-energy Zinc Batteries

摘要

Though massive efforts have been devoted to exploring Br-based batteries, the highly soluble Br-2/Br-3(-) species causing rigorous "shuttle effect", leads to severe self-discharge and low Coulombic efficiency. Conventionally, quaternary ammonium salts such as methyl ethyl morpholinium bromide (MEMBr) and tetrapropylammonium bromide (TPABr) are used to fix Br-2 and Br-3(-), but they occupy the mass and volume of battery without capacity contribution. Here, we report an all-active solid interhalogen compound, IBr, as a cathode to address the above challenges, in which the oxidized Br-0 is fixed by iodine (I), thoroughly eliminating cross-diffusing Br-2/Br-3(-) species during the whole charging and discharging process. The Zn||IBr battery delivers remarkably high energy density of 385.8 Wh kg(-1), which is higher than those of I-2, MEMBr3, and TPABr(3) cathodes. Our work provides new approaches to achieve active solid interhalogen chemistry for high-energy electrochemical energy storage devices.

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