【摘 要】
：
Anionic redox reaction (ARR) in layered manganese-based oxide cathodes has been considered as an effective strategy to improve the energy density of sodium-ion batteries.Mn-vacancy layered oxides deli-ver a high ARR-related capacity with small voltage hys
【机 构】
：
Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education),Renewable Energy Conve
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Anionic redox reaction (ARR) in layered manganese-based oxide cathodes has been considered as an effective strategy to improve the energy density of sodium-ion batteries.Mn-vacancy layered oxides deli-ver a high ARR-related capacity with small voltage hysteresis,however,they are limited by rapid capacity degradation and poor rate capability,which arise from inferior structure changes due to repeated redox of lattice oxygen.Herein,redox-inactive Ti4+ is introduced to substitute partial Mn4+ to form Na2Ti0.5Mn2.5O7 (Na4/7[□1/7Ti1/7Mn5/7]O2,□ for Mn vacancies),which can effectively restrain unfavorable interlayer gliding of Na2Mn3O7 at high charge voltages,as reflected by an ultralow-strain volume varia-tion of 0.11％.There is no irreversible O2 evolution observed in Na2Tio.5Mn2.5O7 upon charging,which sta-bilizes the lattice oxygen and ensures the overall structural stability.It exhibits increased capacity retention of 79.1％ after 60 cycles in Na2Tio.5Mn2.5O7 (17.1％ in Na2Mn3O7) and good rate capability(92.1 mAh g-1 at 0.5 A g-1).This investigation provides new insights into designing high-performance cathode materials with reversible ARR and structural stability for SIBs.
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