Nitrogen and phosphorus co-doped hard carbon materials as high-performance anode for sodium ion batteries

Abstract The negative electrode of sodium ion batteries has always faced severe challenges in the commercialization process. To improve capacity, increase the first Coulomb efficiency, and enhance performance under high current density, we have prepared a nitrogen phosphorus co-doped hard carbon material. Phosphorus groups are doped in the material to achieve sodium storage, at the same time, coating phenolic resin for material modification. At the same time, nitrogen and carbon nanotube structures are added during the preparation process to make it have good conductivity. In order to solve the problem of low first Coulomb efficiency, adopted CMC binder and ether based electrolyte to solve the problem of excessive reaction between the negative electrode and the electrolyte during the first discharge process. In actual testing, this material has a capacity of 365 mAh g−1 and a capacity retention rate of 112% under long cycles.