Dual-site substitution enables high-voltage P2-Na 0.67 Ni 0.33 Mn 0.67 O 2 cathodes with superior wide-temperature performance and enhanced ambient stability for sodium-ion batteries

Synergistic Ca/Mg co-doping expands Na + interlayer spacing and suppresses structural degradation, enabling stable 4.5 V operation, excellent cycling stability and rate capability, and reliable performance across wide temperature and humidity ranges.