The composite electrode of Bi@carbon-texture derived from metal-organic frameworks for aqueous chloride ion battery

Aqueous rechargeable batteries have been a hot research topic due to their high conductivity, low cost, and operational safety. Bismuth is deemed as a kind of promising anode material owing to its suitable negative working window and highly reversible redox reaction in aqueous chloride ion battery; however, it exhibits poor stability and volume expansion when oxidized to BiOCl during electrochemical process. Herein, we present a novel synthesized method of bismuth metal nanoparticles through the thermal reduction of Bi-MOF under hydrogen atmosphere. The Bi-particles with ~ 100 nm size are uniformly coated with a layer of carbon film. The aqueous chloride ion battery system consists of the synthesized bismuth as the anode, AgCl as the cathode, and 1 M NaCl (pH = 2) as the electrolyte. After 200 cycles, the specific capacity is 87.9 mAh g⁻¹ at the current density of 400 mA g⁻¹. After 1000 cycles, a durable specific capacity of 51.8 mAh g⁻¹ was achieved under the current density of 1200 mA g⁻¹ and the coulombic efficiency is above 99%. The electrochemical mechanism was further investigated by X-ray diffraction. The current work will be significant for the chloride ion energy storage and battery desalination.