Sulfur and phosphorus co-doped hard carbon for potassium ion storage

Due to the low cost, good chemical stability and structural diversity, hard carbon has been considered as an important anode material for potassium-ion batteries (PIBs). However, due to the large diameter of K+, PIBs with both excellent rate performance and long-life is still challenging. Herein, sulfur (S), phosphorus (P) co-doped hard carbon anode are synthesized via polymerization of thiophene and phytic acid and the following concise pyrolysis strategy. S in hard carbon can used as reactive sites for K+ storage and P doping will effectively improve wettability of electrolyte. After temperature regulation, the fabricated SP-700 with dual and abundant heteroatom doping exhibits high initial reversible capacity (412 mAh g-1 at 0.05 A g-1), excellent rate performance (130 mAh g-1 at 5 A g-1) and stable cyclic performance (94 mAh g-1 after 1500 cycles at 2 A g-1).