The effects of doped phosphorus on the electrochemical performance of hard carbon anode for lithium ion capacitors

Heteroatom is a practical tactic to improve the ability of carbon materials to store lithium ions. In this research, a series of hard carbon with different phosphorus species and contents were simply prepared by annealing the mixture of phytic acid and starch. By studying the phosphorus functional groups species and electrochemical performance of phosphorus-doped carbon, the relation of phosphorus species, phosphorus atoms contents and the Li-storage performance of samples have been closely related. In this context, the high content of phosphorus atoms not means a high specific capacity and the phosphorus-doped hard carbon will produce a higher specific capacity when the doping content of phosphorus atoms ranges around 1.8 %. As to the effect of phosphorus functional groups species on the electrochemical performance of hard carbon, the Li-ions may be stored more efficiently with the higher proportion of CP bonds in phosphorus functional groups species. In this regard, the understanding of how phosphorus functional groups species affect electrochemical performance on hard carbon will help better understand the effect of phosphorus doping on hard carbon anode for lithium ion storage. Meanwhile, it also will provide some insights and support for the application of phosphorus-doped electrodes.