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Tuning Sodium Occupancy Sites in P2‐Layered Cathode Material for Enhancing Electrochemical Performance
Author(s) -
Wang QinChao,
Shadike Zulipiya,
Li XunLu,
Bao Jian,
Qiu QiQi,
Hu Enyuan,
Bak SeongMin,
Xiao Xianghui,
Ma Lu,
Wu XiaoJing,
Yang XiaoQing,
Zhou YongNing
Publication year - 2021
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.202003455
Subject(s) - materials science , electrochemistry , cathode , ion , transition metal , redox , vacancy defect , electrode , analytical chemistry (journal) , crystallography , chemistry , metallurgy , biochemistry , organic chemistry , chromatography , catalysis
Different sodium occupancy sites in P2‐layered cathode materials can reorganize Na‐ion distribution and modify the Na + /vacancy superstructure, which have a vital impact on the Na‐ion transport and Na storage behavior during charge and discharge processes, but have not been investigated specifically and are not yet well understood. Herein, the occupancy ratio of two different Na sites (sites below transition metal ions and sites below oxygen ions along the c direction) in P2‐Na 0.67 [Mn 0.66 Ni 0.33 ]O 2 cathode is tuned successfully by inducing Sb 5+ ions with strong repulsion toward Na sites right below transition metals. It is found that the decrease of Na occupancy right below transition metal ions is beneficial to the electrochemical performance of P2‐layered cathode materials, regarding cycle stability and rate capability. In situ X‐ray absorption spectroscopy reveals that the reversible Mn 3.3+ /Mn 4+ and Ni 2+ /Ni 3+ redox couples provide charge compensation in different voltage regions of 1.8–2.3 and 2.3–4.2 V, respectively. The transmission X‐ray microscopy confirms the uniform redox reaction over the whole electrode particle. In addition, Sb substitution can suppress the “P2‐O2” phase transition in high voltage region by preventing oxygen gliding in a – b planes, thus ensuring robust structure stability during cycling.