Ultralow-strain Ti substituted Mn-vacancy layered oxides with enhanced stability for sodium-ion batteries

• 作者: Yanchen Liu Chenchen Wang Meng Ren Hengyi Fang Zhuoliang Jiang Fujun Li
• 来源期刊: 能源化学
• 年，卷（期）: 2021,（12）
• 页码范围: 351-357
• 页数: 7页
• 语种: 英文

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 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.