Fabricating N, P-Codoped Hierarchical Porous Carbons from Lignin via Assembled Templating and Activation Strategy for High-Performance Supercapacitors

The heteroatom-doped carbons are widely recognized as optimal electrode materials for energy storage yet challenges in their structural regulation. Here, an assembled templating and activation strategy is developed to synthesize N, P-codoped hierarchical porous carbons from lignin (NP-HPLCs) for supercapacitors. The synthesis process involved carbonizing a lignin/F127/Mg2(OH)2CO3 assembly with KOH and (NH4)2HPO4, wherein the generated MgO template and KOH activator facilitated the formation of micromesopores, while (NH4)2HPO4 served as an N/P dopant. The resultant NP-HPLCs exhibited a high accessible surface area of 1302 m2/g and N, P-codoped levels (N: 4.40 atom %, P: 1.47 atom %) with three-dimensional hierarchical porous structures, thereby promoting ion diffusion and transport. Upon these advantages, the carbon electrode achieved a remarkable specific capacitance of up to 358 F/g at 0.5 A/g. Moreover, the fabricated supercapacitor delivered a high energy density of 6.76 Wh/kg at 137 W/kg with excellent cyclic stability. This work offers a valuable reference for the structural design of heteroatom-doped porous carbons for advanced energy storage devices.