An in situ derived alloy phase stabilizes the phosphorus/carbon interface for high-performance lithium-ion battery anodes†

Abstract

Phosphorus anodes are promising candidates for high-energy, fast-charging lithium-ion batteries, due to their impressive specific capacity of 2596 mA h g⁻¹ and suitable lithiation potential of 0.7 V versus Li⁺/Li. However, their inherent poor conductivity and large volume change during charging and discharging processes pose significant challenges. Although various phosphorus–carbon composites offer a partial solution to these issues, the weak interfacial bonding between phosphorus and carbon hinders further enhancement. To tackle these issues, Sn₄P₃, which is derived in situ at the surface of phosphorus particles, has been employed as a potent interface-strengthening agent, significantly bolstering the bonding strength between phosphorus and carbon materials, yielding the product of Sn–P@C. During the lithiation and delithiation processes, the interface interaction is enhanced and the derived Li₅SnP₃ and Li_4.4Sn exhibit exceptional ionic and electronic conductivity, drastically enhancing the electrochemical performance and reducing the volume expansion rate of the Sn–P@C anode. Additionally, Li_4.4Sn can prominently reduce the delithiation energy barrier. Therefore, the Sn–P@C anode exhibits outstanding electrochemical properties, with an initial discharge capacity of up to 2258.4 mA h g⁻¹ and a capacity retention of 92.2% after 140 cycles at a rate of 0.5C.