<p>Aqueous zinc sulfur batteries promise low−cost and safe grid−scale energy storage, but face challenges due to sluggish interfacial Zn<sup>2+</sup> transfer and H<sub>2</sub>O−induced ZnS disproportionation reactions at the interface of sulfur positive electrode. Here, we develop a hybrid electrolyte by introducing ZnI<sub>2</sub> and organic N,N−dimethylformamide cosolvent, in which iodide species contribute to catalytic oxidation of ZnS, while N,N−dimethylformamide cosolvent can effectively facilitate sulfur reduction reaction. By combining operando Raman spectroscopy with non−destructive electrochemical impedance spectroscopy and theoretical calculations/simulations, it demonstrates that N,N−dimethylformamide molecules preferentially adsorb on sulfur electrode surface and strongly interact with Zn<sup>2+</sup>, thereby reconstructing interfacial electric double layer with H<sub>2</sub>O−poor inner Helmholtz plane and Zn<sup>2+</sup>−rich outer Helmholtz plane, which not only favors interfacial Zn<sup>2+</sup> transfer to promote sulfur conversion reaction, but also suppresses H<sub>2</sub>O−induced side reactions. Through an additional constant voltage charge procedure to avoid I<sup>−</sup>/I<sub>3</sub><sup>−</sup> redox shuttle, the assembled Zn||S batteries can exhibit a voltage hysteresis of 0.326 V and a long−term cycling stability with a capacity fading of 0.034% per cycle after 1000 cycles at 2 C (i.e., 3.34 A g<sup>−1</sup>), even enabling a high areal capacity of 7.68 mAh cm<sup>−2</sup> and a stable low−temperature performance with a specific capacity of 500 mAh g<sup>−1</sup> at −10 °C.</p>

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Reconstructing interfacial electric double layer for efficient sulfur conversion reaction in aqueous zinc sulfur batteries

  • Jie Lei,
  • Jiandong Lin,
  • Yinze Zuo,
  • Yong Yan,
  • Yue Lu,
  • Rongxin Gao,
  • Peining Lin,
  • Mingquan Liu,
  • Hao Yan,
  • Wei Yan,
  • Jiujun Zhang

摘要

Aqueous zinc sulfur batteries promise low−cost and safe grid−scale energy storage, but face challenges due to sluggish interfacial Zn2+ transfer and H2O−induced ZnS disproportionation reactions at the interface of sulfur positive electrode. Here, we develop a hybrid electrolyte by introducing ZnI2 and organic N,N−dimethylformamide cosolvent, in which iodide species contribute to catalytic oxidation of ZnS, while N,N−dimethylformamide cosolvent can effectively facilitate sulfur reduction reaction. By combining operando Raman spectroscopy with non−destructive electrochemical impedance spectroscopy and theoretical calculations/simulations, it demonstrates that N,N−dimethylformamide molecules preferentially adsorb on sulfur electrode surface and strongly interact with Zn2+, thereby reconstructing interfacial electric double layer with H2O−poor inner Helmholtz plane and Zn2+−rich outer Helmholtz plane, which not only favors interfacial Zn2+ transfer to promote sulfur conversion reaction, but also suppresses H2O−induced side reactions. Through an additional constant voltage charge procedure to avoid I/I3 redox shuttle, the assembled Zn||S batteries can exhibit a voltage hysteresis of 0.326 V and a long−term cycling stability with a capacity fading of 0.034% per cycle after 1000 cycles at 2 C (i.e., 3.34 A g−1), even enabling a high areal capacity of 7.68 mAh cm−2 and a stable low−temperature performance with a specific capacity of 500 mAh g−1 at −10 °C.