Anionic redox reactions in the cathodes of lithium-ion batteries are enabling opportunities to double or even triple the energy density. However, it is still challenging to develop a cathode exploring the anionic redox for real-world applications using earth-abundant materials, due to the limited strategy to intercept the oxygenates from further irreversible oxidation to O2 gas. Here we report simultaneous iron and oxygen redox activity in a Li-rich anti-fluorite Li5FeO4 electrode. During the removal of the first two Li ions, the oxidation potential of O2- is lowered to approximately 3.5 V vs. Li+/Li0, at which potential the cationic oxidation occurs concurrently. These anionic and cationic redox reactions show high reversibility without any obvious O2 gas release. Moreover, this study provides an insightful guideline to design high-capacity cathode with reversible oxygen redox by simply introducing oxygen ions coordinated exclusively by Li+.

Enabling the high capacity of lithium-rich anti-fluorite lithium-iron oxide by simultaneous anionic and cationic redox

2019 Spring National Meeting

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