Li Zhao, Li Yi, Ren Xiaochuan, Zhao Yuanxin, Ren Zhiguo, Yao Zeyin, Zhang Wei, Xu Hao, Wang Zhong, Zhang Nian, Gu Yueliang, Li Xiaolong, Zhu Daming, Zou Jianxin
National Engineering Research Center of Light Alloy Net Forming, State Key Laboratory of Metal Matrix Composite, Center of Hydrogen Science, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201204, China.
Small. 2023 Sep;19(38):e2301770. doi: 10.1002/smll.202301770. Epub 2023 May 24.
Aqueous zinc batteries (ZIBs) have attracted considerable attention in recent years because of their high safety and eco-friendly features. Numerous studies have shown that adding Mn salts to ZnSO electrolytes enhanced overall energy densities and extended the cycling life of Zn/MnO batteries. It is commonly believed that Mn additives in the electrolyte inhibit the dissolution of MnO cathode. To better understand the role of Mn electrolyte additives, the ZIB using a Co O cathode instead of MnO in 0.3 m MnSO + 3 m ZnSO electrolyte is built to avoid interference from MnO cathode. As expected, the Zn/Co O battery exhibits electrochemical characteristics nearly identical to those of Zn/MnO batteries. Operando synchrotron X-ray diffraction (XRD), ex situ X-ray absorption spectroscopy (XAS), and electrochemical analyses are carried out to determine the reaction mechanism and pathway. This work demonstrates that the electrochemical reaction occurring at cathode involves a reversible Mn /MnO deposition/dissolution process, while a chemical reaction of Zn /Zn SO (OH) ∙5H O deposition/dissolution is involved during part of the charge/discharge cycle due to the change in the electrolyte environment. The reversible Zn /Zn SO (OH) ∙5H O reaction contributes no capacity and lowers the diffusion kinetics of the Mn /MnO reaction, which prevents the operation of ZIBs at high current densities.
水系锌电池（ZIBs）近年来因其高安全性和环保特性而备受关注。大量研究表明，在硫酸锌电解质中添加锰盐可提高整体能量密度并延长锌/二氧化锰电池的循环寿命。人们普遍认为，电解质中的锰添加剂可抑制二氧化锰阴极的溶解。为了更好地理解锰电解质添加剂的作用，构建了在0.3 m硫酸锰+3 m硫酸锌电解质中使用氧化钴阴极而非二氧化锰的水系锌电池，以避免来自二氧化锰阴极的干扰。正如预期的那样，锌/氧化钴电池表现出与锌/二氧化锰电池几乎相同的电化学特性。进行了原位同步辐射X射线衍射（XRD）、非原位X射线吸收光谱（XAS）和电化学分析，以确定反应机理和途径。这项工作表明，阴极发生的电化学反应涉及可逆的锰/二氧化锰沉积/溶解过程，而由于电解质环境的变化，在部分充放电循环中涉及锌/碱式硫酸锌·5H₂O沉积/溶解的化学反应。可逆的锌/碱式硫酸锌·5H₂O反应不贡献容量，并降低了锰/二氧化锰反应的扩散动力学，这阻碍了水系锌电池在高电流密度下的运行。
