Yu Hongyuan, Long Yu, Chen Derong, Dong Ximan, Ye Xiaolin, Zhang Yibo, Li Fangbing, Xu Yue, Tao Ying, Yang Quan-Hong
Nanoyang Group, Tianjin Key Laboratory of Advanced Carbon and Electrochemical Energy Storage, School of Chemical Engineering and Technology, National Industry-Education Integration Platform of Energy Storage, Tianjin University and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300072, China.
Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou, 350207, China.
Small. 2024 Jan;20(1):e2303832. doi: 10.1002/smll.202303832. Epub 2023 Sep 5.
Protonation has been considered essential for the pseudocapacitive energy storage of polyaniline (PANI) for years, as proton doping in PANI chains not only activates electron transport pathways, but also promotes the proceeding of redox reactions. Rarely has the ability for PANI of storing energy without protonation been investigated, and it remains uncertain whether PANI has pseudocapacitive charge storage properties in an alkaline electrolyte. Here, this work first demonstrates the pseudocapacitive energy storage for PANI without protonation using a PANI/graphene composite as a model material in an alkaline electrolyte. Using in situ Raman spectroscopy coupled with electrochemical quartz crystal microbalance (EQCM) measurements, this work determines the formation of -N= group over potential on a PANI chain and demonstrates the direct contribution of OH in the nonprotonation type of oxidation reactions. This work finds that the PANI/graphene composite in an alkaline electrolyte has excellent cycling stability with a wider operation voltage of 1 V as well as a slightly higher specific capacitance than that in an acidic electrolyte. The findings provide a new perspective on pseudocapacitive energy storage of PANI-based composites, which will influence the selection of electrolytes for PANI materials and expand their application in energy storage fields.
多年来，质子化一直被认为是聚苯胺（PANI）赝电容储能所必需的，因为聚苯胺链中的质子掺杂不仅能激活电子传输途径，还能促进氧化还原反应的进行。聚苯胺在无质子化情况下的储能能力鲜有研究，并且在碱性电解质中聚苯胺是否具有赝电容电荷存储特性仍不确定。在此，这项工作首次以聚苯胺/石墨烯复合材料为模型材料，在碱性电解质中证明了聚苯胺无质子化时的赝电容储能。通过原位拉曼光谱结合电化学石英晶体微天平（EQCM）测量，这项工作确定了聚苯胺链上超电势下-N=基团的形成，并证明了OH在非质子化类型氧化反应中的直接贡献。这项工作发现，碱性电解质中的聚苯胺/石墨烯复合材料具有出色的循环稳定性，工作电压范围更宽，为1 V，且比酸性电解质中的比电容略高。这些发现为基于聚苯胺的复合材料的赝电容储能提供了新的视角，这将影响聚苯胺材料电解质的选择，并扩大其在储能领域的应用。
