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

Abstract

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).