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In recent years, secondary ion batteries have played crucial roles in various fields of production and daily life, among which sodium-ion batteries (SIBs) have shown their promising potential in the fields of energy storage and power generation due to their low cost and long lifespan. P-type layered oxide cathode materials are key components of SIBs, with advantages such as low cost and stable structure, but they also suffers from the problems of low capacity and a variety of structural types. In this research, through temperature-controlled synthesis, it was determined that lower-temperature calcination facilitated the formation of pure P3 phase, while higher-temperature calcination facilitated the formation of pure P2 phase, and intermediate-temperature calcination resulted in a coexistence state of P3 and P2 phases. The changes in P-type structure significantly affected the electrochemical behavior and performance of the materials, with the presence of P3 phase contributing to reduce the electrochemical polarization and enhance the anionic redox activity. Furthermore, through first-principle calculations, it was confirmed that the P3 structure caused changes in the electronic structure of O and Ni, and the electrons closer to the Fermi level increased, which induced an increase in redox activity and thereby improved charge-discharge capacity.
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