Deep Eutectic Mn(NO3)2−H2O Binary System as a Safe, Cost‐Effective, and Efficient Electrolyte for Supercapacitor Applications

Abstract

Abstract Deep eutectic solvents (DESs) have proved to be an effective substitute for conventional electrolytes for energy storage applications because of their unique properties and ability to adapt them to specific applications. In this regard, this study examines an easy‐to‐produce, widely available and cheap manganese nitrate concentrated electrolyte that holds DES traits. The electrolyte (i. e., manganese nitrate; (Mn(NO3)2 ⋅ 6H2O with a weight composition of 42 %) revealed its eutectic behaviour by benchmarking the eutectic distance (53 °C), thermal expansion coefficient (3.9×10−4 K), activation energy for conductivity (∼2.45 kJ mol−1), and viscosity (14 kJ mol−1). What's more, it was successfully incorporated into a two‐electrode symmetric supercapacitor comprising activated carbon electrodes and demonstrated specific capacitance retention of 93 % (170 F g−1) through 2000 consecutive galvanostatic charge‐discharge cycles at 25 and −20 °C.

Keywords

• Deep eutectic solvent
• manganese (II) nitrate hydrate
• activated carbon
• supercapacitor