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Reverse Dual-Ion Battery via a ZnCl₂ Water-in-Salt Electrolyte
- Wu, Xianyong, Xu, Yunkai, Zhang, Chong, Leonard, Daniel P., Markir, Aaron, Lu, Jun, Ji, Xiulei
- Journal of the American Chemical Society 2019 v.141 no.15 pp. 6338-6344
- anions, anodes, batteries, carbon, cathodes, cations, electric potential difference, iron, nanocomposites, porous media, zinc chloride
- Dual-ion batteries are known for anion storage in the cathode coupled to cation incorporation in the anode. We flip the sequence of the anion/cation-storage chemistries of the anode and the cathode in dual-ion batteries (DIBs) by allowing the anode to take in anions and a cation-deficient cathode to host cations, thus operating as a reverse dual-ion battery (RDIB). The anion-insertion anode is a nanocomposite having ferrocene encapsulated inside a microporous carbon, and the cathode is a Zn-insertion Prussian blue, Zn₃[Fe(CN)₆]₂. This unique battery configuration benefits from the usage of a 30 m ZnCl₂ “water-in-salt” electrolyte. This electrolyte minimizes the dissolution of ferrocene; it raises the cation-insertion potential in the cathode, and it depresses the anion-insertion potential in the anode, thus widening the full cell’s voltage by 0.35 V compared with a dilute ZnCl₂ electrolyte. RDIBs provide a configuration-based solution to exploit the practicality of cation-deficient cathode materials in aqueous electrolytes.