We report a carbon/carbon capacitor based on micro/mesoporous carbon electrodes with cost-effective and eco-friendly aqueous choline bis(trifluoromethylsulfonyl)imide (ChTFSI) electrolyte with a cosolvent enabling low-temperature operation down to −30 °C. For this purpose, a MgO-templated hierarchical carbon (MP98B) with an average mesopore diameter of 3.5 nm was prepared by pyrolysis of magnesium citrate hydrate at 900 °C. To reach lower temperatures, the melting point and viscosity of the aqueous electrolyte were reduced by mixing water (W) with an organic solvent (methanol, M, or isopropanol, I) of high dielectric constant and low viscosity. 5 mol kg⁻¹ (5 m) ChTFSI in an optimized volume fraction of cosolvent, M_0.75W_0.25, and I_0.75W_0.25, showed the highest conductivity; the higher conductivity in M_0.75W_0.25 (22.8 and 3.1 mS cm⁻¹ at 20 and −30 °C, respectively) than in I_0.75W_0.25 (8.5 and 0.5 mS cm⁻¹ at 20 and −30 °C, respectively) is attributed to the lower viscosity of the M_0.75W_0.25 solution. The electrochemical stability window (ESW) of 5 m ChTFSI in M_0.75W_0.25 and I_0.75W_0.25 (1.6 V) on an MP98B electrode was determined by applying the S-method. Meanwhile, by adjusting the mass ratio of the two electrodes, a MP98B/MP98B capacitor using the 5 m electrolyte in M_0.75W_0.25 could operate with a good life span up to 1.6 V while exhibiting a better charge propagation, greater specific capacitance, and higher specific energy than in I_0.75W_0.25.

我们报告了一种基于微/中孔碳电极的碳/碳电容器，该电容器具有成本效益高且环保的水性胆碱双（三氟甲基磺酰）亚胺 (ChTFSI) 电解质和助溶剂，可在低至 -30 °C 的低温下运行。为此，通过在 900 °C 下热解柠檬酸镁水合物，制备了平均中孔直径为 3.5 nm 的 MgO 模板分级碳 (MP98B)。为了达到较低的温度，通过将水 (W) 与具有高介电常数和低粘度的有机溶剂（甲醇，M 或异丙醇，I）混合来降低水性电解质的熔点和粘度。5 mol kg ^-1 (5 m) ChTFSI 在优化的助溶剂体积分数中，M _0.75 W _0.25和 I _0.75W _0.25，表现出最高的电导率；M _0.75 W _0.25（分别在 20 和 -30 °C 下为 22.8 和 3.1 mS cm ^-1）的电导率高于 I _0.75 W _0.25（分别在 20 和 -30 °C 下为 8.5 和 0.5 mS cm ^-1）归因于 M _0.75 W _0.25溶液的较低粘度。5 m ChTFSI 在 M _0.75 W _0.25和 I _0.75 W _{0.25中的电化学稳定性窗口 (ESW)}MP98B 电极上的 (1.6 V) 是通过应用 S 方法确定的。同时，通过调整两个电极的质量比，使用 M _0.75 W _0.25中 5 m 电解液的 MP98B/MP98B 电容器可以在高达 1.6 V 的良好寿命下运行，同时表现出更好的电荷传播、更大的比电容和比能量高于 I _0.75 W _0.25。