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

Abstract

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.