ChemInform Abstract: Phase Behavior in the LiBH<sub>4</sub>—LiBr System and Structure of the Anion‐Stabilized Fast Ionic, High Temperature Phase.

Cascallana-Matías, Irene; Keen, David A.; Cussen, Edmund J.; Gregory, Duncan H.

doi:10.1002/chin.201606011

Cited by 3 publications

(7 citation statements)

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“…Usually, both mechanical and thermal treatments are necessary to obtain a single lithium borohydride−halide hexagonal solid solution. 52,57,58 However, after 24 h of milling, a complete solid solution of h-Li(BH 4 ) 0.667 Br 0.333 was successfully obtained by Sveinbjornsson et al 35 In order to investigate the feasibility to form a three-anion hexagonal phase only by mechanochemistry, the same composition of sample s2 was BM for different times (sample s3). Figure S6 shows the effect of the increasing milling time on the formation of the hexagonal solid solution.…”

Section: Resultsmentioning

confidence: 70%

“…59 Indeed, for LiBH 4 −LiI and LiBH 4 −LiBr systems that have similar anionic radii, a significant miscibility is expected and confirmed experimentally, with the stability of the hexagonal phase at RT. 32,35,52,57 On the other hand, Cl − anions are miscible in h-LiBH 4 only at temperatures close to 100 °C. 60 In fact, the radii of BH 4 − and Cl − differ significantly.…”

Section: Resultsmentioning

confidence: 99%

“…34 Fast lithium ion conductivity is also retained in Li(BH 4 ) 1−x Br x (0.29 ≤ x ≤ 0.50) hexagonal solid solutions, although the conductivity is reduced as the bromide content increases above x = 0.29. 35 The two complex hydrides, Li 2 (BH 4 )(NH 2 ) and Li 4 (BH 4 )(NH 2 ) 3 , exhibit lithium-ion conductivities higher than 10 −4 S/cm at RT. 30,36 Another approach is to increase the ionic conductivity of LiBH 4 by mixing it with oxides or by means of nanoconfinement.…”

Section: Introductionmentioning

confidence: 99%

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Phase Stability and Fast Ion Conductivity in the Hexagonal LiBH₄–LiBr–LiCl Solid Solution

et al. 2019

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This study shows a flexible system that offers promising candidates for Li-based solid state electrolyte. The Brsubstitution for BH 4 stabilizes the hexagonal structure of LiBH 4 at room temperature, whereas Clis soluble only at higher temperatures. Incorporate chloride in hexagonal solid solution lead to increase the energy density of the system. For the first time, a stable hexagonal solid solution of LiBH 4 containing both Cland Br-halide anions has been obtained at room temperature (RT). The LiBH 4 -LiBr-LiCl ternary phase diagram has been determined at RT by X-ray diffraction coupled with a Rietveld refinement. A solubility of up to 30% of Clin the solid solution has been established. The effect of the halogenation on the Li-ion conductivity and electrochemical stability has been investigated by Electrochemical Impedance Spectroscopy and Cyclic Voltammetry. Considering the ternary samples, h-Li(BH 4 ) 0.7 (Br) 0.2 (Cl) 0.1 compositionshowed the highest value for conductivity (1.3 × 10 −5 S/cm at 30 °C), which is about three order of magnitude higher than that for pure LiBH 4 in the orthorhombic structure. The values of Li-ion conductivity at room temperature depend only on the BH 4 content in the solid solution, suggesting that the Br/Cl ratio does not affect the defect formation energy in the structure. The chloride anion substitution in the hexagonal structure increases the activation energy, moving from about 0.45 eV for samples without Clions in the structure, up to about 0.63 eV for h-Li(BH 4 ) 0.6 (Br) 0.2 (Cl) 0.2 compositions, according with the Meyer-Neldel rule. In addition to increasing Li ion conductivity, the halogenation increase also the thermal stability of the system.Unlike for the Li-ion conductivity, Br/Cl ratio influences the electrochemical stability: a wide oxidative window of 4.04 V vs. Li + /Li is reached in the Li-Br system, while further addition of Cl is a trade-off between oxidative stability and weight reduction. The halogenation allow both binary and ternary systems operating below 120 °C, thus suggesting possible applications of these fast ion conductors as solid-state electrolyte in Li-ion batteries. Graphical AbstractKeywords: complex hydride, solid state electrolyte, Li-ion batteries

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Section: Resultsmentioning

confidence: 70%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Phase Stability and Fast Ion Conductivity in the Hexagonal LiBH₄–LiBr–LiCl Solid Solution

et al. 2019

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“…16 High alkali conductivity was also achieved in the LiX−LiBH 4 system (X = Br, I), 15 through the stabilization, at room temperature, of the hexagonal polymorph with defect wurtzite structure showing a conductivity increase of 2 orders of magnitude. 17 Mixed anion chemistry can typically be used to optimize properties by combining advantages of more than one family of materials. While oxides often show better atmospheric and electrochemical stability, sulfide electrolytes present among the highest reported lithium conductivities, thanks to their high polarizability and increased cation−anion bond covalency compared to more electronegative anions.…”

Section: Introductionmentioning

confidence: 99%

Li_4.3AlS_3.3Cl_0.7: A Sulfide–Chloride Lithium Ion Conductor with Highly Disordered Structure and Increased Conductivity

et al. 2021

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Mixed anion materials and anion doping are very promising strategies to improve solid-state electrolyte properties by enabling an optimized balance between good electrochemical stability and high ionic conductivity. In this work, we present the discovery of a novel lithium aluminum sulfide–chloride phase, obtained by substitution of chloride for sulfur in Li3AlS3 and Li5AlS4 materials. The structure is strongly affected by the presence of chloride anions on the sulfur site, as the substitution was shown to be directly responsible for the stabilization of a higher symmetry phase presenting a large degree of cationic site disorder, as well as disordered octahedral lithium vacancies. The effect of disorder on the lithium conductivity properties was assessed by a combined experimental–theoretical approach. In particular, the conductivity is increased by a factor 103 compared to the pure sulfide phase. Although it remains moderate (10–6 S·cm–1), ab initio molecular dynamics and maximum entropy (applied to neutron diffraction data) methods show that disorder leads to a 3D diffusion pathway, where Li atoms move thanks to a concerted mechanism. An understanding of the structure–property relationships is developed to determine the limiting factor governing lithium ion conductivity. This analysis, added to the strong step forward obtained in the determination of the dimensionality of diffusion, paves the way for accessing even higher conductivity in materials comprising an hcp anion arrangement.

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“…The calculated lattice parameter of LiCeBr 3 Cl is 11.95 Å, being larger than 11.72 Å of LiCe(BH 4 ) 3 Cl. This is unexpected, since the ionic radius of Br − (1.96 Å) is smaller than that of [BH 4 ] − (2.05 Å) and the solid solution of LiBH 4 −LiBr has a smaller cell volume than pure LiBH 4 32,33. We repeated DFT optimization of the cell parameter employing a different exchange-correlation functional that includes van der Waals energy,34 but the trend is not affected, giving slightly reduced cell parameters of 11.89 and 11.67 Å for LiCeBr 3 Cl and LiCe(BH 4 ) 3 Cl, respectively.…”

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confidence: 99%

Lithium Ion Disorder and Conduction Mechanism in LiCe(BH₄)₃Cl

2016

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We investigate the diffusion mechanism of Li ions in LiCe(BH 4 ) 3 Cl, which exhibits fast Li ion conduction. It was previously shown that eight Li ions partially occupy the 12d Wyckoff sites in the I4̅ 3m structure and the Li ion diffusion takes place via jumping through the three-dimensional network of the 12d sites. In this study, we employ firstprinciples nudged elastic band simulation to elucidate the diffusion mechanism and discover that the Li ion does not directly jump to the neighboring 12d site, but instead passes through the closest 6b site. Moreover, the 6b site turns out to be another stable Li ion site, not just a transient point during a jump event. The occupation of the 6b site and the Li ion diffusion mechanism were assured by first-principles molecular dynamics simulations. The partial occupancy of the 12d site and 6b site at 500 K is approximately 1/2 and 1/3, respectively. The experimental diffraction data can be consistently interpreted. The peculiar crystal structure of LiCe(BH 4 ) 3 Cl allowing efficient and fast Li ion diffusion is again highlighted together with the role of [BH 4 ] − ion in thermodynamically stabilizing LiCe(BH 4 ) 3 Cl.

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ChemInform Abstract: Phase Behavior in the LiBH₄—LiBr System and Structure of the Anion‐Stabilized Fast Ionic, High Temperature Phase.

Cited by 3 publications

References 1 publication

Phase Stability and Fast Ion Conductivity in the Hexagonal LiBH₄–LiBr–LiCl Solid Solution

Phase Stability and Fast Ion Conductivity in the Hexagonal LiBH₄–LiBr–LiCl Solid Solution

Li_4.3AlS_3.3Cl_0.7: A Sulfide–Chloride Lithium Ion Conductor with Highly Disordered Structure and Increased Conductivity

Lithium Ion Disorder and Conduction Mechanism in LiCe(BH₄)₃Cl

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ChemInform Abstract: Phase Behavior in the LiBH4—LiBr System and Structure of the Anion‐Stabilized Fast Ionic, High Temperature Phase.

Cited by 3 publications

References 1 publication

Phase Stability and Fast Ion Conductivity in the Hexagonal LiBH4–LiBr–LiCl Solid Solution

Phase Stability and Fast Ion Conductivity in the Hexagonal LiBH4–LiBr–LiCl Solid Solution

Li4.3AlS3.3Cl0.7: A Sulfide–Chloride Lithium Ion Conductor with Highly Disordered Structure and Increased Conductivity

Lithium Ion Disorder and Conduction Mechanism in LiCe(BH4)3Cl

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ChemInform Abstract: Phase Behavior in the LiBH₄—LiBr System and Structure of the Anion‐Stabilized Fast Ionic, High Temperature Phase.

Phase Stability and Fast Ion Conductivity in the Hexagonal LiBH₄–LiBr–LiCl Solid Solution

Phase Stability and Fast Ion Conductivity in the Hexagonal LiBH₄–LiBr–LiCl Solid Solution

Li_4.3AlS_3.3Cl_0.7: A Sulfide–Chloride Lithium Ion Conductor with Highly Disordered Structure and Increased Conductivity

Lithium Ion Disorder and Conduction Mechanism in LiCe(BH₄)₃Cl