Manipulating Layered P2@P3 Integrated Spinel Structure Evolution for High-Performance Sodium-Ion Batteries.

Structural evolution of the cathode during cycling plays a vital role in the electrochemical performance of sodium-ion batteries. A strategy based on engineering the crystal structure coupled with chemical substitution led to the design of the layered P2@P3 integrated spinel oxide cathode Na0.5 Ni0.1 Co0.15 Mn0.65 Mg0.1 O2 , which shows excellent sodium-ion half/full battery performance. Combined analyses involving scanning transmission electron microscopy with atomic resolution as well as in situ synchrotron-based X-ray absorption spectra and in situ synchrotron-based X-ray diffraction patterns led to visualization of the inherent layered P2@P3 integrated spinel structure, charge compensation mechanism, structural evolution, and phase transition. This study provides an in-depth understanding of the structure-performance relationship in this structure and opens up a novel field based on manipulating structural evolution for the design of high-performance battery cathodes.