Fluorinated Carbonate Electrolyte with Superior Oxidative Stability Enables Long‐Term Cycle Stability of Na2/3Ni1/3Mn2/3O2 Cathodes in Sodium‐Ion Batteries. Issue 9 (28th December 2020)

• Record Type: Journal Article
• Authors: Wu, Shuilin; Su, Bizhe; Ni, Kun; Pan, Fei; Wang, Changlai; Zhang, Kaili; Yu, Denis Y. W.; Zhu, Yanwu; Zhang, Wenjun
• Is Part Of: Advanced energy materials. Volume 11:Issue 9(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-12-28
• Subjects: cathode–electrolyte interfaces -- density functional simulations -- fluoroethylene carbonate -- sodium‐ion batteries -- transitional metal oxides; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.202002737
• Languages: English
• ISSNs: 1614-6832

Abstract

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 Na2/3 Ni1/3 Mn2/3 O2 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 Na2/3 Ni1/3 Mn2/3 O2 cathode toward grid‐scale applications. Abstract : Na2/3 Ni1/3 Mn2/3 O2 is a promising cathode material for sodium‐ion batteries, but its cycle stability is far behind the practical requirements. This study shows that the continuous electrolyte decomposition of common carbonate‐based electrolytes accelerates the capacity decay of Na2/3 Ni1/3 Mn2/3 O2 . Using a fluoroethylene carbonate electrolyte can suppress the successive electrolyte decomposition, thus enabling remarkably improved cycle stability for Na2/3 Ni1/3 Mn2/3 O2 .