Electron-deficient sites on boron-doped graphite enable air-stable and durable red phosphorus anode for lithium-ion batteries†

Abstract

Composing with various carbon matrices has been proposed to overcome the poor electrochemical performance of red phosphorus (RP) anode caused by its low electronic conductivity and huge volume changes during repeated lithiation/delithiation processes. However, the insufficient chemical affinity between RP and carbon matrices can rarely enable a superior cycling stability, and the strong air sensitivity of RP from the lone-pair electrons has not been solved. Herein, we demonstrate that boron doping into graphite can simultaneously address the abovementioned challenges of RP/carbon composite using a simple one-step ball milling method. The experimental data and theoretical calculations corroborate that electron-deficient boron doping into graphite can greatly facilitate the formation of P–C bonds at the interface of RP/carbon, which can maintain the structural stability of the composite and keep effective electrical contact between them during long-term cycling processes. Consequently, the as-prepared RP/boron-doped graphite composite (RP-BG) exhibits a high reversible capacity of 1388.2 mA h g⁻¹ at 0.1 A g⁻¹ and an outstanding long cycle life with a capacity retention of 87.9% after 1000 cycles at 10.0 A g⁻¹. Moreover, the electron-deficient boron doping causes the shift of lone-pair electrons of RP to graphite; therefore, the reactivity with water/oxygen is remarkably suppressed, and the air stability of RP-BG is dramatically increased. This work paves the way for the practical applications of RP-based anodes for lithium-ion batteries.