Integrating Superlattice to Regulate P2‐O2 Phase Transition and Improve Cycling Stability in Sodium‐Ion Batteries

P2‐Na2/3Ni1/3Mn2/3O2 is a promising cathode material for sodium‐ion batteries (SIBs), but it faces the rapid capacity decay due to P2‐O2 phase transition. The superlattice is a stable structure, compositing it can effectively eliminate the P2‐O2 phase transition. Based on superlattice of NaLi1/3Mn2/3O2, a series of xNaLi1/3Mn2/3O2 ⋅ (1‐x)Na2/3Ni1/3Mn2/3O2 (x=0, 0.3, 0.4, 0.5) were first synthesized by compounding NaLi1/3Mn2/3O2 into Na2/3Ni1/3Mn2/3O2 in this article. The XRD and SAED show that special superlattice guarantees the structure stable of materials, resulting in a first order phase transformation to a solid solution reaction in high voltage. The composite cathode materials realize excellent cycle performance and discharge specific capacity. When x=0.4, the capacity retention rate is 82.64 % after 100 cycles, which is greatly improved compared with 30.60 % of Na2/3Ni1/3Mn2/3O2. This paper provides a new idea for using superlattice to stabilize the structure and improve the electrochemical performance for SIBs. Suppressing the P2‐O2 phase transition: This paper provides a new idea for using superlattice to stabilize the structure and improve the electrochemical performance for the sodium ion batteries. A special superlattice structure was introduced to act as a red light to block the path of the P2 phase transition to the O2 phase and improve the structural stability of the composite cathode materials.