Opportunities and Limitations of Ionic Liquid- and Organic Carbonate Solvent-Based Electrolytes for Mg-Ion-Based Dual-Ion Batteries

Dual-ion batteries (DIBs) offer a great alternative to state-of-the-art lithium-ion batteries, based on their high promises due to the absence of transition metals and the use of low-cost materials, which could make them economically favorable targeting stationary energy storage applications. In addition, they are not limited by certain metal cations, and DIBs with a broad variety of utilized ions could be demonstrated over the last years. Herein, a systematic study of different electrolyte approaches for Mg-ion-based DIBs was conducted. A side-by-side comparison of Li- and Mg-ion-based electrolytes using activated carbon as negative electrode revealed the opportunities but also limitations of Mg-ion-based DIBs. Ethylene sulfite was successfully introduced as electrolyte additive and increased the specific discharge capacity significantly up to 93 +/- 2 mAh g(-1) with coulombic efficiencies over 99 % and an excellent capacity retention of 88 % after 400 cycles. In addition, and for the first time, highly concentrated carbonate-based electrolytes were employed for Mg-ion-based DIBs, showing adequate discharge capacities and high coulombic efficiencies.

Automated summary

Dual-ion batteries (DIBs) are considered as an economically advantageous alternative to lithium-ion batteries in stationary energy storage applications due to the absence of transition metals and the use of low-cost materials. A systematic study on different electrolyte approaches for Mg-ion-based DIBs revealed opportunities for improvement, with the successful introduction of ethylene sulfite as an electrolyte additive significantly increasing specific discharge capacity. Additionally, highly concentrated carbonate-based electrolytes showed promise in providing adequate discharge capacities and high coulombic efficiencies for Mg-ion-based DIBs.