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Fluorinated Carbonate Electrolyte with Superior Oxidative Stability Enables Long‐Term Cycle Stability of Na 2/3 Ni 1/3 Mn 2/3 O 2 Cathodes in Sodium‐Ion Batteries
Author(s) -
Wu Shuilin,
Su Bizhe,
Ni Kun,
Pan Fei,
Wang Changlai,
Zhang Kaili,
Yu Denis Y. W.,
Zhu Yanwu,
Zhang Wenjun
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.202002737
Subject(s) - electrolyte , materials science , cathode , passivation , oxide , dissociation (chemistry) , chemical engineering , metal , energy storage , inorganic chemistry , electrode , nanotechnology , chemistry , thermodynamics , metallurgy , layer (electronics) , power (physics) , physics , engineering
Abstract Layered transition metal oxides are promising cathode materials for sodium‐ion batteries applicable for low‐cost energy storage systems. However, their cycle stability needs to be substantially improved to meet the requirements of practical applications. Specifically, the issues related to electrolyte stability and the formation of an unstable cathode–electrolyte interface (CEI) remain unsolved. Herein, it is shown that an electrolyte with high fluorine content may induce a robust fluorinated CEI on Na 2/3 Ni 1/3 Mn 2/3 O 2 cathode, a representative transitional metal oxide, which can efficiently passivate its surface and suppress continuous electrolyte decomposition during cycling. As a result, the cells deliver a remarkably improved rate capability and cycle stability. Density functional simulations further validate the superior stability of fluorinated electrolyte on cathodes with low highest occupied molecule orbital energy and high dissociation energy barriers. This finding demonstrates the favorable role of fluorinated electrolytes for improving the long‐term cycle stability of Na 2/3 Ni 1/3 Mn 2/3 O 2 cathode toward grid‐scale applications.