Two-dimensional (2D) porous carbon materials have attracted great attentions as high-performance electrodes for supercapacitors due to their large aspect ratio and high surface area. Generally, micropore-dominant 2D carbon materials have higher densities than hierarchically porous 3D carbon materials, which can provide a new possibility of greatly enhancing the volumetric capacitance. Herein, we propose a facile and low-cost synthesis method of biomass-derived porous carbon nanosheets (PCNSs) with the assistance of the KOH derived potassium compounds using fish scale as precursor. The PCNS obtained at 600 °C possesses ultrathin nanosheet structure (with thickness of 3–5 nm), micropore-dominate porosity (with specific surface area of 962 m² g⁻¹), rich surface heteroatoms (14.64 at% for O, 5.05 at% for N and 0.92 at% for S) and high compacting density (1.06 g cm⁻³), which endow the electrodes with high gravimetric/volumetric capacitance performance in three-electrode and two-electrode systems.

二维（2D）多孔碳材料由于其高长宽比和高表面积而作为超级电容器的高性能电极备受关注。通常，以微孔为主的2D碳材料比分层多孔的3D碳材料具有更高的密度，这可以提供大大提高体积电容的新可能性。在本文中，我们提出了一种以鱼鳞为前体，借助KOH衍生的钾化合物，方便，低成本地合成生物质衍生的多孔碳纳米片（PCNS）的方法。在600°C下获得的PCNS具有超薄纳米片结构（厚度为3-5 nm），微孔为主的孔隙率（比表面积为962 m ² g ^-1），丰富的表面杂原子（O含量为14.64 at％，N含量为5.05 at％，S含量为0.92 at％）和高压实密度（1.06 g cm ^-3），使电极在三重态下具有较高的重量/体积电容性能电极和两电极系统。