Stability and conductivity of cation- and anion-substituted LiBH 4 -based solid-state electrolytes
Journal Article
·
· Physical Review Materials
- Northwestern University, Evanston, IL (United States); DOE/OSTI
- Northwestern University, Evanston, IL (United States)
The high-temperature phase of LiBH4 (HT-LiBH4) exhibits a promisingly high lithium ion conductivity but is unstable at room temperature. We use density functional theory (DFT) calculations to investigate the stabilization effect of halogen and alkali cation/anion substitutions on HT-LiBH4 as well the underlying mechanism for the high lithium ion conductivity. We find that increasing the substituent concentration enhances the stabilization of HT-LiBH4 (i.e., the DFT energy difference between the low- and high-temperature forms of substituted LiBH4 is reduced). Cation/anion substitution also leads to a higher Li defect (vacancy, interstitial, and Frenkel) formation energy, thereby reducing the Li defect (vacancy, interstitial, and Frenkel) concentrations. Using DFT migration barriers input into kinetic Monte Carlo simulations and the Materials INTerface (MINT) framework, here we calculate the room-temperature lithium ion conductivities for Li(BH4)1-xIx (x = 0.25 and 0.5) and Li1-yKyBH4 (y = 0.25). Our calculations suggest that the lower I concentration leads to a higher lithium ion conductivity of 5.7 x10-3 S/cm compared with that of Li(BH4)0.5I0.5 (4.2 ×10-5 S/cm) because of the formation of more Li-related defects. Based on our findings, we suggest that the stabilization of HT-LiBH4-based lithium ion conductors can be controlled by carefully tuning the cation/anion substituent concentrations to maximize the lithium ionic conductivities of the specific system.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States); Northwestern University, Evanston, IL (United States)
- Sponsoring Organization:
- Dow Chemical Company; National Institute of Standards and Technology (NIST); USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC02-05CH11231; AC02-06CH11357; FG02-07ER46433
- OSTI ID:
- 1541391
- Alternate ID(s):
- OSTI ID: 1454898
- Journal Information:
- Physical Review Materials, Journal Name: Physical Review Materials Journal Issue: 6 Vol. 2; ISSN 2475-9953
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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