Starch Gel Electrolyte and its Interaction with Trivalent Aluminum for Aqueous Aluminum‐Ion Batteries: Enhanced Low Temperature Electrochemical Performance
Saraswathi Ramakrishnan, Sajan Raj Sasirajan Little Flower, Desai Prashant Hanamantrao, Kavibharathy Kasiviswanathan, Divya Catherin Sesu, Kesavan Muthu, Varathan Elumalai, Kumaran Vediappan
Abstract
Abstract This study explores trivalent Al interaction with aqueous starch gel in the presence of two different anions through salting effect. Salting‐out nature of Al 2 (SO 4 ) 3 ·18H 2 O with starch gel causes precipitation of starch; this happens due to competitive anion‐water complex formation over starch–water interaction, thereby reducing polymer solubility. Salting‐in effect of AlCl 3 with starch gel happens through Al 3+ cation interaction with hydroxyl group of starch and increases polymer solubility, making gel electrolyte viable for battery applications. Prepared gel electrolyte exhibits ionic conductivity of 1.59 mS cm −1 and a high t Al 3+ value of 0.77. The gel electrolyte's performance is studied using two different cathodes, the Al|MoO 3 cell employing starch gel electrolyte achieves discharge capacity of 193 mA h g −1 and Al|MnO 2 cell achieves discharge capacity of 140 mA h g −1 @0.1 A g −1 for first cycle. The diffusion coefficient of both cells using starch gel electrolyte is calculated and found to be 2.1 × 10 −11 cm 2 s −1 for Al|MoO 3 and 3.1 × 10 −11 cm 2 s −1 for Al|MnO 2 cells. The Al|MoO 3 cell at lower temperature shows improved electrochemical performance with a specific capacity retention of ≈87.8% over 90 cycles. This kind of aqueous gel electrolyte operating at low temperature broadens the application for next generation sustainable batteries.