Unlocking the Potential of Phosphorus Anodes for Sodium-Ion Batteries via Tailored Reversible Na/Polyphosphide Chemistry.

Abstract

To surmount the inherent limitations and fully harness the remarkable ultra-high specific capacity (2,596 mAh g-1) of phosphorus (P) anode for sodium-ion batteries (SIBs), we unveil an alternative fast and reversible electrochemical pathway based on Na2P16↔Na3P, which transcends the barriers posed by sluggish reaction kinetics in solid-state red P. It entails the immobilization of dissolved sodium polyphosphide (Na2P16) onto carbon cloth (CC) matrices via robust C─O─P bonding (Na2P16@CC), and the intrinsic superior malleability of Na2P16 effectively mitigates the issue of electrode pulverization caused by volumetric changes of red P during (de)sodiation. Additionally, the profound chemical adsorption of surface oxygen-doped CC toward phosphorus species and the utilization of weakly solvating cyclic carbonate solvents synergistically inhibit the vexing dissolution of high-order polyphosphides in the electrolyte. By capitalizing on the advances of the novel reaction mechanism, the Na2P16@CC composite anode material achieves improved sodium storage performance with a high initial reversible capacity of 1.75 mAh cm-2 at 0.1 mA cm-2 and a capacity retention of 81% over 600 cycles. This work opens an avenue toward the rational design of P-based anodes for high-energy SIBs.