Ultrahigh Phosphorus Doping of Carbon for High-Rate Sodium Ion Batteries Anode

Phosphorus doped carbons are of particular interest as anode materials because of their large interlayer spacing and strong adsorption of Na+ ions. However, it remains challenging to achieve high phosphorus doping due to the limited choices of phosphorus sources and the difficulty in constructing oxygen-free synthesis system. Herein, a new synthesis strategy is proposed to prepare ultrahigh phosphorus-doped carbon (UPC) anodes for high performance sodium ion batteries (SIBs). By using two commonly available, miscible, evaporable liquids in PCl3 and C6H12, as phosphorus and carbon sources, an oxygen-free reaction system is successfully established by N-2 bubbling to simultaneously realize carbonization and in situ P doping. The P content can reach 30 wt%, much higher than most reported P-doping carbon-based materials. Furthermore, the doped P is dominated by substitutional P-(C-3) protrusions in the carbon lattice, which can significantly enlarge the interlayer spacing and enhance the adsorption energy of Na+. When serving as the SIBs anode, the UPC delivers an ultrahigh reversible capacity of 510.4 mAh g(-1) with a rational operating voltage of 0.54 V, and the best rate capability of 397.1 mAh g(-1) at 10 A g(-1). This new strategy will effectively promote the practical application of hard carbon.

Automated summary

A novel synthesis strategy was proposed to prepare ultrahigh phosphorus-doped carbon (UPC) anodes for high performance sodium ion batteries, achieving a high phosphorus content and substitutional phosphorus in the carbon lattice, leading to significant improvement in sodium ion storage performance.