Sodium-deficient nickel-manganese oxides with three-layered stacking exhibit the unique property of dual nickel-oxygen redox activity, which allows them to achieve enormous specific capacity. The challenge is how to stabilize the oxygen redox activity during cycling. This study demonstrates that oxygen redox activity of
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Sodium-deficient nickel-manganese oxides with three-layered stacking exhibit the unique property of dual nickel-oxygen redox activity, which allows them to achieve enormous specific capacity. The challenge is how to stabilize the oxygen redox activity during cycling. This study demonstrates that oxygen redox activity of
P3-Na
2/3Ni
1/2Mn
1/2O
2 during both Na
+ and Li
+ intercalation can be regulated by the design of oxide architecture that includes target metal substituents (such as Mg
2+ and Ti
4+) and oxygen storage modifiers (such as CeO
2). Although the substitution for nickel with Ti
4+ amplifies the oxygen redox activity and intensifies the interaction of oxides with NaPF
6- and LiPF
6-based electrolytes, the Mg
2+ substituents influence mainly the nickel redox activity and suppress the deposition of electrolyte decomposed products (such as MnF
2). The CeO
2-modifier has a much stronger effect on the oxygen redox activity than that of metal substituents; thus, the highest specific capacity is attained. In addition, the CeO
2-modifier tunes the electrode–electrode interaction by eliminating the deposition of MnF
2. As a result, the Mg-substituted oxide modified with CeO
2 displays high capacity, excellent cycling stability and exceptional rate capability when used as cathode in Na-ion cell, while in Li-ion cell, the best performance is achieved for Ti-substituted oxide modified by CeO
2.
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