A novel electrolyte of electric double-layer capacitors (EDLCs) for ultra-low temperature applications based on spiro-(1,1')-bipyrolidinium tetrafluoroborate (SBP-BF4) dissolved in acetonitrile (AN) and AN + dibutyl carbonate (DBC) mixtures has been developed. The physic-chemical properties and electrochemical characterizations at low temperature have been demonstrated on pure AN and AN/DBC mixed electrolytes. From 20 to −50 °C, AN electrolyte shows a slight superiority of the capacitance, but the novel DBC-mixed electrolytes exhibit much higher ion conductivity and better electrochemical performance at −60 °C, while AN electrolyte does not cycle at all due to the crystallization of AN and precipitation of SBP-BF4. The specific discharge capacitance of DBC mixtures maintain 92 F g−1 even at a high current density of 5 A g−1. At −60 °C, from electrochemical impedance spectroscopy measurement, the whole resistance for AN electrolyte rapidly increased about 60 times higher than that of 20 °C, while those for DBC mixtures remain relatively low within the whole temperature range. The cycle performance test indicates the DBC mixtures exhibit extremely stable capacitance, especially at ultra-low temperature. The capacitance for DBC-20% electrolyte is 95 F g−1 even after 10000 cycles, which maintained 83% of the capacity of 20 °C.

中文翻译：

一种新型双电层电容器（EDLC）电解质，用于溶解在乙腈（AN）和AN +碳酸二丁酯（DBC ）中的螺-（1,1'）-双吡咯烷四氟硼酸酯（SBP-BF 4）。 ）混合物已经开发出来。已在纯AN和AN / DBC混合电解质上证明了其低温下的物理化学性质和电化学特性。在20至-50°C的温度下，AN电解质的电容稍有优势，但是新型的DBC混合电解质在-60°C时表现出更高的离子电导率和更好的电化学性能，而AN电解质由于以下原因根本不会循环AN的结晶和SBP-BF 4的沉淀。DBC混合物的比放电电容保持92 F g-1甚至在5 A g -1的高电流密度下也是如此。在-60°C下，通过电化学阻抗谱测量，AN电解质的整体电阻迅速增加，比20°C高60倍左右，而DBC混合物的电阻在整个温度范围内保持相对较低。循环性能测试表明，DBC混合物表现出极稳定的电容，尤其是在超低温下。即使经过10000次循环，DBC-20％电解质的电容仍为95 F g -1，保持了20°C容量的83％。