“ <scp>Win‐Win</scp> ” Scenario of High Energy Density and Long Cycling Life in a Novel Na _3. <scp> ₉ MnCr ₀ </scp> _. <scp> ₉ Zr ₀ </scp> _.1 ( <scp> PO ₄ </scp> ) ₃ Cathode

The development of high-energy and long-lifespan NASICON-type cathode materials for sodium-ion batteries has always been a research hotspot but daunting challenge. Although Na4MnCr(PO4)3 emerged as one the most promising high-energy-density owing to its three-electron reactions, it still suffers from serious structural distortion upon repetitive charge/discharge processes caused by Jahn-Teller active Mn3+. Herein, selective substitution Cr Zr in was explored enhance stability, due pinning effect ions ≈2.9-electron as-prepared Na3.9MnCr0.9Zr0.1(PO4)3/C delivers high capacity retention 85.94% over 500 cycles at 5 C an ultrahigh 156.4 mAh g−1 0.1 C, enabling stable energy output 555.2 Wh kg−1. Moreover, during whole process, small volume change only 6.7% verified situ X-ray diffraction, reversible reactions Cr3+/Cr4+, Mn3+/Mn4+, Mn2+/Mn3+ redox couples were identified via ex photoelectron spectroscopy analyses. Galvanostatic intermittent titration technique tests density functional theory calculations further demonstrated fast reaction kinetics electrode. This work offers new opportunities designing high-stability NASICON cathodes ion doping.