| Super-capacitor with ultra high power density and long cycle life have great potential application in electric cars, new rail transportation, solar and wind power generation, smart grids and other fields. Based on fundamental storage mechanisms of electric double-layer in porous carbon materials, this paper aim to study on preparation and electrochemical performance of organic electrolyte, which is the key parts of super-capacitors’ ultra-low temperature and high withstand voltage performance, and the ultra-low temperature and high withstand voltage performance of capacitors based on the prepared novel electrolytes were analyzed and discussed.The different concentration (0.5～1.5 mol L-1) with different DBC content (0%～33%) SBP-BF4/AN+DBC electrolytes were prepared by laboratory-made double spiro-quaternary ammonium salts dissolved in acetonitrile (AN) and dibutyl carbonate (DBC) mixed solvents. The 0.5 M pure AN electrolyte has a high electrical conductivity of 31.96 mS cm-1, while that of DBC-20% mixed electrolyte was up to 8.56 mS cm-1 even at a ultra-low temperature of -60 ℃. The capacitors combined with conventional activated carbon (YP-50F) and SBP-BF4/AN+DBC electrolytes showed excellent energy storage performance and cyclic stability under ultra-low temperature. The specific capacitance of the cell based on DBC-20% electrolyte was extremely stable with a high value of 95 F g-1 even after 10000 cycles at a high current density of 2.5 A g-1 at-60 ℃, exhibited excellent ultra-low temperature high rate discharge performance.Based on the results of ultra-low temperature measurements, the effect of electrolytes concentration on the performance of withstand voltage was discussed, and by improving the working voltage of capacitors to increase its energy density. At room temperature, the performance of its withstand voltage enhanced as the concentration of electrolytes increased. The capacitors filled with both 1.5 M pure AN and DBC mixed electrolytes showed the best withstand high voltage performance. At a high voltage of 3.5 V and high current density of 20000 mA g-1, the specific capacitance were 97 F g-1 and 98 F g-1,respectively. Meanwhile, the cell also had both high specific energy and power, with a value of 52 Wh kg-1 and 31.5 kW kg-1. At-60 ℃, however, the capacitors based on pure AN electrolyte showed poor electrochemical performance, while the capacitors filled with 1.0 M DBC-20% electrolyte exhibited much better working performance. With high voltage of 3.5 V and high current density of 5000 mA g-1, the specific capacitance was 92 F g-1 Meanwhile, the cell also had both high specific energy and power, with a value of 39 Wh kg-1 and 10.5 kW kg-1.The above results of electrochemical tests under ultra-low temperature and high voltage suggests that the introduction of DBC in AN effectively reduced the melting point of the mixed electrolyte system, so that it has a high electrical conductivity at ultra-low temperature, and the capacitors exhibited excellent electrochemical performance. In addition, by improving the operating voltage of the capacitor, the energy density significantly increased while its high power density was simultaneous retained, so that the capacitors could have both high specific energy and power.
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