In-situ derived alloy phase stabilizes 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 mAh g-1 and suitable lithiation potential of 0.7 V versus Li+/Li. However, its 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 enhanced interface interaction and the derivation of Li5SnP3 and Li4.4Sn exhibit exceptional ionic and electronic conductivity, drastically enhancing the electrochemical performance and reducing the volume expansion rate of Sn-P@C anode. Additionally, Li4.4Sn 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 mAh g-1 and a capacity retention of 92.2% after 140 cycles at a rate of 0.5 C.