Elucidation of the role of electrolyte nature on electrochemical performance of PANI in energy storage device
Abstract
To minimize the number of cells during the construction of a device, the working voltage of each cell must be as high as possible. Obtaining an aqueous electrolyte based electrochemical cell with high cell operating voltage is challenging due to the low standard reduction potential of water.
The current work shows the effect of the nature and concentration of the electrolyte on the structure of water and its electrochemical stability. A symmetrical PANI cell was constructed in the presence of different electrolytes.
It is demonstrated that utilizing ions with high solvation ability (chaotropic ions) and the formation of hydronium/Zundel ions enables the amount of free water to be reduced. As a result, there are no side reactions on the electrodes related to the electrolysis of water, and the main electrochemical reaction contributing to the cell capacity predominates.
Moreover, by choosing the appropriate electrolyte it is possible to control the battery or capacitance-like behavior of PANI. The electro-chemical performance of a symmetrical PANI cell shows a promising energy density of 7.5 Wh/kg at a power density of 150 kW/kg.
The superior electrochemical performance (capacity) is retained after 50 cycles in a potential window of 5 V. It is interesting to highlight that, according to Raman spectroscopy, PANI maintains its chemical stability in a 5 V potential window.