Multifunctional Phosphorus Doping: Integrating Enhanced Ionic/Electronic Transport and Interface Optimization for Silicon Oxycarbide Anodes

Polymer‐derived silicon oxycarbide (SiOC) is a promising anode material for lithium‐ion batteries due to its high specific capacity, low operating potential, structural stability, and tunable components. However, its practical application is hindered by poor intrinsic electronic/ionic conductivity and unstable solid‐electrolyte interphase (SEI). Herein, in this work, a phosphorus (P)‐doped SiOC material was successfully synthesized, and the P is incorporated into the SiOC network via P–O–Si bonding. This P‐doping strategy introduced additional free electrons and enhanced the ordering of free‐carbon phase. Also, it induced the formation of LiF and Li 3 PO 4 ‐rich SEI. These modifications collaboratively led to good rate performance and cycling stability. The optimized SiOC‐P electrode delivered a high reversible capacity of 860.1 mAh g −1 , an excellent capacity retention of 81.1% after 700 cycles at 1.0 A g −1 , and a good rate capacity of 383.4 mAh g −1 even at 5.0 A g −1 . Density functional theory calculations also reveal that Si–O–P promotes the ionic/electronic transport among the SiOC‐P bulk. This work offers valuable insights into heteroatom doping strategies for tailoring SiOC‐based materials and facilitates their practical application in high‐energy‐density batteries.