Operation of supercapacitors at sub-zero temperatures with reasonable performance is of great importance for their outdoor applications. Herein, the sub-zero performance of supercapacitors assembled from nitrogen-doped porous carbon electrodes with interconnected tubular structure using ionic liquid as electrolyte is reported. The carbon-based electrode materials are synthesized by pyrolysis of poly(1-vinylimidazole) networks in the presence of titanate nanotubes and potassium nitrate, followed by removal of titanate nanotubes. Benefiting from the interconnected hierarchically porous structure and large surface area, the synthesized electrode materials exhibits a gravimetric capacitance of 333 F·g⁻¹ under 1 A·g⁻¹ in a three-electrode system in 6.0 mol·L⁻¹ KOH aqueous solution at room temperature. Symmetric supercapacitors assembled from the synthesized electrode deliver a specific energy of 32.7 Wh·kg⁻¹ under 1.30 W·kg⁻¹ using ionic liquid as electrolyte at room temperature. At −40 °C, the assembled device using ionic liquid as electrolyte possesses a specific energy of 48.3 Wh·kg⁻¹ under 1.75 kW·kg⁻¹ and 18.6 Wh·kg⁻¹ under 35.0 kW·kg⁻¹. In addition, the device retains 53.5% of its initial capacitance after 10,000 charge-discharge cycles at −40 °C under 10 A·g⁻¹.

超级电容器在低于零的温度下以合理的性能运行对于其户外应用非常重要。在本文中，报道了使用离子液体作为电解质由具有相互连接的管状结构的氮掺杂多孔碳电极组装而成的超级电容器的低于零性能。碳基电极材料是通过在钛酸酯纳米管和硝酸钾存在下热解聚（1-乙烯基咪唑）网络，然后去除钛酸酯纳米管而合成的。从互连分级多孔结构和大的表面积受益，合成的电极材料表现出333 F A重量电容·克^-1下1个A·克^-1在6.0莫尔三电极系统^-1室温下加入KOH水溶液。由合成电极组装而成的对称超级电容器在室温下使用离子液体作为电解质，在1.30 W·kg ^-1下可提供32.7 Wh·kg ^-1的比能。在-40℃下，采用离子液体作为电解质的组装装置具有48.3瓦·kg的比能量^-1下1.75千瓦公斤· ^-1和18.6瓦千克· ^-1下35.0千瓦公斤· ^-1。此外，在-40°C和10 A·g ^-1的条件下进行10,000次充放电循环后，器件保留其初始电容的53.5％。