Supercapacitors are energy storage devices designed to operate at higher power densities than conventional batteries, but their energy density is still too low for many applications. Efforts are made to design new electrolytes with wider electrochemical windows than aqueous or conventional organic electrolytes in order to increase energy density. Ionic liquids (ILs) with wide electrochemical stability windows are excellent candidates to be employed as supercapacitor electrolytes. ILs containing tetracyanoborate anions [B(CN)₄] offer wider electrochemical stability than conventional electrolytes and maintain a high ionic conductivity (6.9 mS cm⁻¹). Herein, we report the use of ILs containing the [B(CN)₄] anion for such an application. They presented a high maximum operating voltage of 3.7 V, and two‐electrode devices demonstrate high specific capacitances even when operating at relatively high rates (ca. 20 F g⁻¹ @ 15 A g⁻¹). This supercapacitor stored more energy and operated at a higher power at all rates studied when compared with cells using a commonly studied ILs.

中文翻译：

---

使用四氰硼酸盐阴离子改善离子液体超级电容器的性能


超级电容器是一种能量存储设备，设计用于以比传统电池更高的功率密度运行，但其能量密度对于许多应用来说仍然太低。人们努力设计比水性或传统有机电解质具有更宽电化学窗口的新型电解质，以提高能量密度。具有宽电化学稳定性窗口的离子液体（IL）是用作超级电容器电解质的优秀候选者。含有四氰基硼酸阴离子[B(CN) ₄ ]的离子液体比传统电解质具有更广泛的电化学稳定性，并保持高离子电导率（6.9 mS cm ^-1 ）。在此，我们报告了含有 [B(CN) ₄ ] 阴离子的离子液体在此类应用中的使用。它们呈现出 3.7 V 的最高工作电压，并且双电极器件即使在相对较高的速率下工作（约 20 F g ⁻¹ @ 15 A g ⁻¹ ）也表现出高比电容。与使用常见研究的 IL 的电池相比，这种超级电容器在所有研究的速率下都存储了更多的能量并以更高的功率运行。