Hydrated alkali-B11H14 salts as potential solid-state electrolytes. Issue 26 (28th June 2021)

• Record Type: Journal Article
• Authors: H. P. Souza, Diego; Møller, Kasper T.; Moggach, Stephen A.; Humphries, Terry D.; D'Angelo, Anita M.; Buckley, Craig E.; Paskevicius, Mark
• Is Part Of: Journal of materials chemistry. Volume 9:Issue 26(2021)
• Page Start: 15027
• Page End: 15037
• Publication Date: 2021-06-28
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d1ta01551f
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : Synthesis and characterization of alkali boron–hydrogen compounds as solid-state electrolytes for battery applications. Hydrated LiB11 H14 and NaB11 H14 exhibit high ionic conductivity and stability against Li and Na metal anodes, respectively. Abstract : Metal boron–hydrogen compounds are considered as promising solid electrolyte candidates for the development of all-solid-state batteries (ASSB), owing to the high ionic conductivity exhibited by closo - and nido -boranes. In this study, an optimised low cost preparation method of MB11 H14 ·(H2 O) n, (M = Li and Na) and KB11 H14 is proposed and analysed. The formation of the B11 H14 − salt is pH-dependent, and H3 O + competes with small ionic radii cations, such as Li + and Na +, to produce a hydronium salt of B11 H14 −, which forms B11 H13 OH − upon heating. The use of diethyl ether to extract B11 H14 − salt from the aqueous medium during synthesis is an important step to avoid hydrolysis of the compound upon drying. The proposed method of synthesis results in LiB11 H14 and NaB11 H14 coordinated with water, whereas KB11 H14 is anhydrous. Hydrated LiB11 H14 ·(H2 O) n and NaB11 H14 ·(H2 O) n exhibit exceptional ionic conductivities at 25 °C, 1.8 × 10 −4 S cm −1 and 1.1 × 10 −3 S cm −1, respectively, which represent some of the highest solid-state Li + and Na + conductivities at room temperature. The salts also exhibit oxidative stability of 2.1 V vs. Li + /Li and 2.6 V vs. Na + /Na, respectively. KB11 H14 undergoes a reversible polymorphic structural transition to a metastable phase before decomposing. All synthesised nido -boranes decompose at temperatures greater than 200 °C.