Achieving a High-Performance Carbon Anode through the P–O Bond for Lithium-Ion Batteries

Carbon materials with high initial Coulombic efficiency (ICE) and specific capacity in lithium-ion batteries are highly attractive. Herein, P-doped carbon has been prepared, and as an anode for lithium-ion batteries, it exhibits remarkably improved ICE and reversible capacity. P atoms are apt for the formation of the P–O bond in carbon with oxygen-containing groups. The doped P content strongly depends on the O content in carbon. The high-doped P content of 5.79 at. % can be obtained through changing the O content in carbon. Carbon with high contents of P and O displays high ICE and capacity as an anode for lithium-ion batteries. The P–O bond in carbon changes the morphology and composition of the solid electrolyte interface (SEI) layer and is beneficial to the formation of a thin and dense SEI layer. The P–O bond in carbon prevents the permeation and decomposition of solvated PF6– in the interior of the electrode during cycling, resulting in the improved ICE, reversible capacity, and rate capability. As an anode for lithium-ion batteries, the ICE can be improved to 70.9% for carbon with the P–O bond from 36.9% for carbon without the P–O bond. Carbon with the P–O bond displays high specific capacities of 566 mA h g–1 after 100 cycles at 0.1 A g–1 and 432 mA h g–1 after 1000 cycles at 1 A g–1. This design offers a simple and efficient method to improve the ICE and reversible capacity of hard carbon.