Polyacrylonitrile-Based Elastomeric Polymer Electrolyte for Aluminum Batteries

Rechargeable aluminum batteries represent one of the most promising postlithium energy storage technologies. Nevertheless, the state-of-the-art electrolyte system used in these batteries poses a significant challenge for large-scale implementation due to its highly aggressive chemical nature. To address the limitations of current ionic liquid electrolytes–including issues such as leakage-induced corrosion, and the necessity for separators–we have developed an elastomeric polymer electrolyte. This electrolyte is synthesized through the direct complexation of polyacrylonitrile (PAN) with aluminum chloride (AlCl3) and the organic salt 1-ethyl-3-methylimidazolium chloride (EMIC). The mechanisms of complexation and cross-linking within the polymer were thoroughly investigated using a combination of FTIR, UV–vis, NMR, and mass spectrometry. Furthermore, the electrochemical properties of the polymer were subjected to extensive investigation. This polymer electrolyte allows for the elimination of separators and exhibits a high ionic conductivity of up to 1.1 mS/cm. Furthermore, the shape stability of the polymer electrolyte mitigates corrosion issues associated with electrolyte leakage. Additionally, the electrolyte exhibits excellent cycling performance in batteries and can be used in the electrochemical stripping and plating of aluminum. The electrolyte reacts very slowly upon contact with water, greatly enhancing battery safety. Our findings suggest that this type of polymer electrolyte presents a viable strategy for developing stable, safe, and flexible aluminum batteries.