通过结构工程增强MnO2正极材料的双电子反应贡献，实现水系锌电池的稳定循环,ACS Nano

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通过结构工程增强MnO2正极材料的双电子反应贡献，实现水系锌电池的稳定循环
ACS Nano ( IF 15.8 ) Pub Date : 2023-07-17 , DOI: 10.1021/acsnano.3c02965
Yaozhi Liu ₁ , Kuo Wang ₁ , Xianpeng Yang ₁ , Jie Liu _{2,

3} , Xiao-Xia Liu _{1,

4,

5} , Xiaoqi Sun _{1,

4}

Affiliation

MnO ₂是一种有前途的水系锌电池正极。然而，活性材料溶解严重阻碍了循环稳定性，并且广泛需要在电解液中预添加Mn ^2+盐。_{在此，我们提出了MnO 2}的结构工程策略，以增强MnO ₂ /Mn ²⁺的可逆双电子转移反应的容量贡献，并实现无Mn ²⁺电解质中的稳定循环。通过与MoO ₃复合，MnO ₂表现出弱化的Mn-O键、更多的氧空位、自发产生结构水，从而降低了放电过程中Mn释放的能垒。同时，复合材料对溶解的Mn ²⁺表现出更强的静电吸引力，这确保了充电过程中高度可逆的再沉积。结果，进行可逆二电子和一电子转移反应的材料之间的质量比从MnO ₂中的0.85增加至MnO ₂ /MoO ₃复合材料中的1.68。在ZnSO ₄电解质中，MnO ₂ /MoO _{3正极在0.1 A g}^–1 (>1900 h)下循环300次后容量保持率达到92.6% ，优于MnO ₂的62.7% 。MnO ₂ /MoO ₃在 1 A g ^–1 (>3200 h) 下循环 16 000 次后仍保留 80.1% 的容量。这项工作为实现Zn电池中MnO ₂的稳定循环提供了一条有效途径。

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Enhancing Two-Electron Reaction Contribution in MnO2 Cathode Material by Structural Engineering for Stable Cycling in Aqueous Zn Batteries

MnO₂ is a promising cathode for aqueous Zn batteries. However, the cycling stability is seriously hindered by active material dissolution, and the pre-addition of Mn²⁺ salts in electrolytes is widely required. Herein, we propose a structural engineering strategy for MnO₂ to enhance the capacity contribution from the reversible two-electron transfer reaction of MnO₂/Mn²⁺ and realize stable cycling in Mn²⁺-free electrolytes. By compositing with MoO₃, MnO₂ exhibits weakened Mn–O bonds, more oxygen vacancies, spontaneous generation of structural water, and thus a lowered energy barrier for Mn release during discharge. Meanwhile, the composite material presents stronger electrostatic attractions for dissolved Mn²⁺, which ensures highly reversible re-deposition during charge. As a result, the mass ratios between materials undergoing reversible two-electron and one-electron transfer reactions increase from 0.85 in MnO₂ to 1.68 in the MnO₂/MoO₃ composite material. In the ZnSO₄ electrolyte, the MnO₂/MoO₃ cathode achieves 92.6% capacity retention after 300 cycles at 0.1 A g^–1 (>1900 h), superior to 62.7% for MnO₂. MnO₂/MoO₃ also retains 80.1% capacity after 16 000 cycles at 1 A g^–1 (>3200 h). This work presents an effective path to realize stable cycling of MnO₂ in Zn batteries.

更新日期：2023-07-17

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