S/N co-doped hierarchical porous carbon from lignite as high-performance anode for potassium-ion batteries

Because of their lower prices and exceptional physicochemical features, hard carbon materials have received a lot of interest in potassium ion batteries (PIBs). However, the slow K+ transport kinetics and significant volume expansion make the use of carbonaceous materials in PIBs anodes difficult. Here, S/N co-doped hierarchical porous carbon composites are designed as anodes for PIBs using lignite as raw material. The S/N co-doped carbon composites produced feature a hierarchical porous structure, which ensures structural resilience and speeds up ion/electronic transport. S/N co-doping in the carbon matrix not only creates an abundance of defects and active sites for K+, but it also increases the distance between layers, allowing for more accessible K+ intercalation/ deintercalation. As a result, when used as anodes for PIBs, the obtained S/N co-doped hierarchical porous carbon composites have a large reversible capacity of 347.5 mAh g- 1 after 100 cycles at 0.1 A g- 1 with a capacity retention of up to 94 %, as well as excellent long cycle stability of 136 mAh g- 1 after 1500 cycles at 1.0 A g- 1.