Composite Sodium Ferrous Sulfate Cathode Material, and Preparation Method and Application Thereof

The present disclosure belongs to the field of sodium batteries. Provided are a composite sodium ferrous sulfate cathode material, and a preparation method and application thereof. The composite sodium ferrous sulfate cathode material includes a core. A chemical formula of the core is NaMFe(PO)(SO)O, where M includes at least one of manganese, vanadium, or titanium, 16≤x≤17, y=1, 4≤z≤5, 2≤k≤2.6, and y+z−0.1x−1.5k≤t≤y+z+0.1x−1.5k. According to the present disclosure, sulfate decomposition is reduced, the material performance of the composite sodium ferrous sulfate cathode material is improved, and a secondary battery using the composite sodium ferrous sulfate cathode material is improved in terms of performance such as cycling performance.