1. An Electrochemically Prepared Mixed Phase of Cobalt Hydroxide/Oxyhydroxide as a Cathode for Aqueous Zinc Ion Batteries.
- Author
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Li, Fuwei, Zhu, Yunbo, Ueno, Hiroshi, and Deng, Ting
- Subjects
ZINC ions ,COBALT hydroxides ,ZINC electrodes ,CHARGE transfer ,CATHODES ,DENSITY functional theory ,ENERGY density - Abstract
Cobalt hydroxide is a widely studied electrode material for supercapacitor and alkaline zinc ion batteries. The large interlayer spacing of Co(OH)
2 is also attractive to store Zn ions. However, Co(OH)2 is quite unstable in the acidic ZnSO4 electrolyte due to its amphoteric nature. Herein, we synthesized a mixed phase of Co(OH)2 /CoOOH via a two-step electrochemical preparation. As the cathode material for an aqueous zinc ion battery (AZIB), Co(OH)2 /CoOOH delivered a maximum capacity of 164 mAh g−1 at 0.05 A g−1 and a high energy density of 275 Wh kg−1 . Benefiting from the low charge-transfer resistance, a capacity of 87 mAh g−1 was maintained at 1.6 A g−1 , showing a good rate performance of the mixed phase. Various spectroscopy analyses and simulations based on the density functional theory (DFT) suggested a higher thermal stability of the mixed phase than pure Co(OH)2 , due to its less local structural disorder. The reduced Co-Co and Co-O shells increased the mechanical strength of the mixed phase to accommodate Zn2+ ions and endure the electrostatic repulsion, resulting in an enhanced cycling stability. The mixed phased also delivered a good stability at the current density of 0.05 A g−1 . After 200 cycles, a capacity retention of 78% was retained, with high Coulombic efficiencies. These results provide a new route to synthesize high-performance LDH for aqueous zinc ion batteries. [ABSTRACT FROM AUTHOR]- Published
- 2023
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