Journal
CHEMISTRY OF MATERIALS
Volume 27, Issue 15, Pages 5407-5416Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.chemmater.5b02110
Keywords
-
Funding
- WPI-AIMR, Tohoku University
- Integrated Materials Research Center for the Low-Carbon Society (LC-IMR), Tohoku University
- JSPS KAKENHI [25220911]
- Advanced Low Carbon Technology Research and Development Program (ALCA) from the Japan Science and Technology Agency
- U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy [DE-EE0002978]
Ask authors/readers for more resources
In this study, we assembled a bulk-type all-solid-state battery 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 second discharge capacity was as high as 205 mAh g(-1), corresponding to a TiS2 utilization ratio of 85%. The 300th discharge capacity remained as high as 180 mAh g(-1) with nearly 100% Coulombic efficiency from the second 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, thermogravimetry coupled with gas composition analysis, powder X-ray diffraction measurements, and first-principles molecular dynamics simulations were carried out. Chemical and/or electrochemical oxidation of LiBH4 occurred at the TiS2 surface at the battery operating temperature of 393 K and/or during the initial charge. During this oxidation reaction of LiBH4 with hydrogen (H-2) release just beneath the TiS2 surface, a third phase, likely including Li2B12H12, precipitated at the interface between LiBH4 and TiS2. Li2B12H12 has a lithium ionic conductivity of log(sigma / S cm(-1)) = -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 interfacial layer is due to the propensity of forming highly stable, hydrogen-deficient polyhydro-closo-polyborates such as Li2B12H12, which are thermodynamically available in the ternary Li-B-H system.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available