Mitigating the Jahn–Teller distortion and phase transition in the P2-Na<sub>0.67</sub>Ni<sub>0.33</sub>Mn<sub>0.67</sub>O<sub>2</sub> cathode through large Sr<sup>2+</sup> ion substitution for improved performance
Sr 2+ , the “pillar” in the P2 structure, suppresses the phase transition, inhibits the Jahn–Teller distortion, and improves the performance of layered oxide cathodes in SIBs.