On September 9th, it was reported that lithium-ion capacitors show immense promise for applications in low-temperature, high-power energy storage systems. Recently, a research team led by Ma Yanwei from the Institute of Electrical Engineering at the Chinese Academy of Sciences introduced an innovative design strategy for a 'solvation-unshielded electrolyte.' In this strategy, the team selected γ-valerolactone (GVL)—a solvent with moderate polarity, a low melting point, and moderate coordination ability—as the primary solvent. They also chose lithium difluoro(oxalato)borate (LiDFOB) as the functional lithium salt and incorporated weakly coordinating ethyl acetate (EA) as a component to regulate solvation.

This unique design minimizes the encapsulation and shielding effects of the solvent on lithium ions, encourages anions to participate in constructing local solvation structures, and ultimately forms a weakly bound, anion-inclusive solvation-unshielded environment. Research findings demonstrate that an all-carbon lithium-ion capacitor utilizing this electrolyte maintains outstanding energy output performance even at -40°C. Specifically, it achieves an energy density based on electrode material mass as high as 106.8Wh/kg, which is 8.9 times greater than that of traditional carbonate-based electrolytes.

This study successfully overcomes the bottleneck of sluggish interfacial reaction kinetics in low-temperature lithium-ion capacitors, which is typically caused by strong solvation shielding. As a result, it offers a fresh perspective and approach for the development of low-temperature, high-energy, and highly stable lithium-ion capacitors.