Suppressing the chromium disproportionation reaction in O3-type layered cathode materials for high capacity sodium-ion batteries

The reversible multi-electron oxidation/reduction process of Cr³⁺/Cr^4.2+ with a large reversible capacity can be achieved in a novel O3-type NaCr_1/3Fe_1/3Mn_1/3O₂. The disproportionation reaction of Cr⁴⁺ to Cr³⁺ and Cr⁶⁺ can be effectively suppressed by Fe³⁺ and Mn⁴⁺ substitution.