Improving the energy density of supercapacitors without sacrificing their large charge storage capacity, high power density, and excellent cycle stability is extremely attractive for researchers. Herein, we develop a mixed alkaline aqueous (MAA) electrolyte with widened operation voltage. Meanwhile, a biomass-derived interconnected hierarchical porous carbon (IHPC) with controlled pore size distribution, ultra-large specific surface area (up to 3463 m² g⁻¹), and high conductivity (up to 8.7 S cm⁻¹) is prepared to match this electrolyte. The obtained IHPC can stably charge-discharge within 1.3 V and exhibit a high specific capacitance of up to 462 F g⁻¹ in the MAA electrolyte. The symmetrical supercapacitors based on the prepared IHPC and the MAA electrolyte deliver a high specific energy of up to 19.7 Wh kg⁻¹ at a specific power of 203 W kg⁻¹, while a specific energy of 14.5 Wh kg⁻¹ is recorded at a large specific power of 12.2 kW kg⁻¹. Meanwhile, the assembled devices based on the MAA electrolyte exhibit good rate capability and excellent cycle stability, up to 89% of initial specific capacitance is retained even at a large current density of 20 A g⁻¹, and more than 91.4% of initial specific capacitance is retained after 30,000 cycles.

在不牺牲超级电容器的大电荷存储容量，高功率密度和出色的循环稳定性的前提下，提高超级电容器的能量密度对研究人员极为有吸引力。本文中，我们开发了一种具有较宽工作电压的混合碱性水（MAA）电解质。同时，制备了具有受控的孔径分布，超大比表面积（高达3463 m ²  g ^-1）和高电导率（高达8.7 S cm ^-1）的生物质衍生的互连多孔碳（IHPC）。匹配这种电解质。所获得的IHPC可以在1.3 V范围内稳定地充放电，并具有高达462 F g ^-1的高比电容在MAA电解液中。基于制得的IHPC和MAA电解质的对称超级电容器在203 W kg ^-1的比功率下可提供高达19.7 Wh kg ^-1的高比能，而在1 kW下记录的14.5 Wh kg ^-1的比能则为12.2 kW kg ^-1的大比功率。同时，基于MAA电解质的组装器件表现出良好的倍率能力和出色的循环稳定性，即使在20 A g ^-1的大电流密度下，仍可保持高达89％的初始比电容，并且大于91.4％的初始比电容30,000次循环后仍保留电容。