Gradient “Single‐Crystal” Li‐Rich Cathode Materials for High‐Stable Lithium‐Ion Batteries

Abstract As one of the high‐energy cathode materials of lithium‐ion batteries (LIBs), lithium‐rich‐layered oxide with “single‐crystal” characteristic (SC‐LLO) can effectively restrain side reactions and cracks due to the reduced inner boundaries and enhanced mechanical stabilities. However, there are still high challenges for SC‐LLO with diverse performance requirements, especially on their cycle stability improvement. Herein, a novel concentration gradient “single‐crystal” LLO (GSC‐LLO), with gradually decreasing Mn and increasing Ni contents from center to surface, is designed and prepared by combining co‐precipitation and molten‐salt sintering methods, yielding a capacity retention of 97.6% and an energy density retention of 95.8% within 100 cycles at 0.1 C. The enhanced performance is mostly attributed to the gradient‐induced stabilized structure, free of cracks and less spinel‐like structure formation after long‐term cycling. Furthermore, the gradient design is also beneficial to the safety of LLOs as suggested by the improved thermal stability and reduced gas release. This study provides an effective strategy to prepare high‐energy, high‐stability, and high‐safety LLOs for advanced LIBs.