Stable Interface Formation between TiS2 and LiBH4 in Bulk-Type All-Solid-State Lithium Batteries

Published

August 11, 2015

Author(s)

Atsushi Unemoto, Tamio Ikeshoji, Syun Yasaku, Motoaki Matsuo, Vitalie Stavila, Terrence J. Udovic, Shin-Ichi Orimo

Abstract

In this study, we assembled a bulk-type all-solid-state batter comprised of a TiS₂ positive electrode, LiBH₄ electrolyte, and Li negative electrode. Our battery retained high capacity over 300 discharge-charge cycles when operated at 393 K and 0.2 C. The 2nd discharge capacity was as high as 205 mAh b^-1, corresponding to a TiS₂ utilization ratio of 85%. The 300^th discharge capacity remained as high as 180 mAh g^-1 with nearly 100 % coulombic efficiency from the 2^nd cycle. Negligible impact of the exposure of LiBH₄ to atmospheric-pressure oxygen on battery cycle life was also confirmed. To investigate the origin of the cycle durability for this bulk-type all-solid-state TiS₂/Li battery, electrochemical measurements, powder X-ray diffraction measurements, thermogravimetry coupled with gas composition analysis, and first-principles molecular dynamics simulations were carried out. Chemical and/or during the initial charge. During this oxidation reaction of LiBH₄ with hydrogen (H₂) release just beneath the TiS₂ surface, a third phase, likely including Li₂B₁₂H₁₂, precipitated at the LiBH_4-TiSd2^ interface. Li₂B₁₂H₁₂ has a lithium ionic conductivity of log(ς/S cm⁰¹)= -4.4, charge transfer reactivity with Li electrodes, and superior oxidative stability to LiBH₄, and thereby can act as a stable interface that enables numerous discharge-charge cycles. Our results strongly suggest that the creation of such a stable inter-facial layer is due to the propensity of forming highly stable, hydrogen-deficient complex hydrides such as Li₂B₁₂H₁₂, which are thermodynamically available in the ternary Li-B-H system.

Citation

Chemistry of Materials

Volume

27

Issue

15

Pub Type

Journals

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Keywords

battery, ionic conductivity, lithium, lithium battery, lithium borohydride, solid electrolyte, solid-state battery, titanium disulfide, rechargeable battery

Citation

Unemoto, A. , Ikeshoji, T. , Yasaku, S. , Matsuo, M. , Stavila, V. , Udovic, T. and Orimo, S. (2015), Stable Interface Formation between TiS₂ and LiBH₄ in Bulk-Type All-Solid-State Lithium Batteries, Chemistry of Materials, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=918679 (Accessed June 18, 2024)