Searching an appropriate biomass that is capable of absorbing microwave energy is significant to realize its rapid microwave-assisted conversion into porous carbons (PCs). Herein, the lignin derived from waste pulping black liquor via crude extraction is directly converted into high-performance PC for a very short duration of 10‒30 min by microwave heating. The inherent inorganic salts in crude lignin with a high content of 17.3% is innovatively used as initial microwave absorber to achieve rapid conversion from lignin into bio-char, and further as porogen combined with KOH to synergistically obtain well-developed porous texture. The resultant PC possesses a super high specific surface area of 3065 m² g⁻¹, hierarchical pore size distribution with abundant micropores (0.73 cm³ g⁻¹) and a remarkable meso-/macropores ratio of 64.4%, highly disordered and amorphous structure, as well as oxygen-enriched structure with a surface oxygen content up to 16.5%. These attractive characteristics contribute to excellent electrochemical properties of the resultant supercapacitor electrode which exhibits a high specific capacitance of 325 F g⁻¹ at 0.5 A g⁻¹ in 6 mol L⁻¹ KOH electrolyte, still maintaining a high value of 258 F g⁻¹ (79.4%) at 50 A g⁻¹. The prepared supercapacitor can remain 81.9% energy density when the power density was increased by 20 folds, suggesting its excellent energy-power synergetic outputting property. These attractive results pave a new way to utilize such a biomass waste, especially with high inorganic salts content, into value-added electrode material for advanced energy storage application.

寻找合适的能够吸收微波能量的生物质对于实现其快速的微波辅助转化为多孔碳（PC）具有重要意义。在此，通过微波加热，在短短的10-30分钟内，将废纸浆黑液中通过粗提得到的木质素直接转化为高性能PC。木质素含量高达17.3％的粗木质素中固有的无机盐被创新地用作初始微波吸收剂，以实现从木质素到生物炭的快速转化，并进一步作为致孔剂与KOH结合，协同获得发达的多孔质感。所得PC具有3065 m ² g ^-1的超高比表面积，具有丰富微孔（0.73 cm³ g ^-1）和显着的中孔/大孔比率为64.4％，高度无序和无定形结构，以及表面氧含量高达16.5％的富氧结构。这些吸引力的特征有助于其表现出的325 F G高的比电容所得超级电容器电极的优异的电化学性能^-1 0.5 A G ^-1在6摩尔大号^-1 KOH电解质，仍保持258 F G高值^{- 1}（79.4％）在50 A g ^-1。当功率密度提高20倍时，所制备的超级电容器可以保持81.9％的能量密度，这表明其具有优异的能量-能量协同输出性能。这些诱人的结果为利用这种生物质废料（尤其是无机盐含量高的废料）用于增值电极材料提供了新的途径，以用于先进的储能应用。