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On the way to transform lithium amide (LiNH2) into lithium imide (Li2NH) by releasing H2, the 1:1 molar mixture of LiNH2-LiH forms cubic (Fm3m)Fm3m) non-stoichiometric complex hydride phases (Li1+xNH2-x; 06wt.% H2 can offer high Li-ionic conductivity (>10-4 S.cm-1 at room temperature) having an electrochemical stability window >5V. The study suggests that the Li-N-H system may be a prospective electrolyte in the all-solid-state Li-ion battery, in addition to its use as a reversible hydrogen storage material. [ABSTRACT FROM AUTHOR]

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 dischargeâ€"charge cycles when operated at 393 K and 0.2 C. The second discharge capacity was as high as 205 mAh gâ€"1, corresponding to a TiS2 utilization ratio of 85%. The 300th discharge capacity remained as high as 180 mAh gâ€"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 (H2) 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(σ/S cmâ€"1) = â'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 dischargeâ€"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 Liâ€"Bâ€"H system. [ABSTRACT FROM AUTHOR]

Impedance measurements indicate that Na2B12H12 exhibits dramatic Na+ conductivity (on the order of 0.1 S cm-1) above its order-disorder phase-transition at ≈529 K, rivaling that of current, solid-state, ceramic-based, Na-battery electrolytes. Superionicity may be aided by the large size, quasispherical shape, and high rotational mobility of the B12H122- anions. [ABSTRACT FROM AUTHOR]

The ionic conduction and electrochemical and thermal stabilities of the LiBH4–LiCl solid-state electrolyte were investigated for use in bulk-type all-solid-state lithium-sulfur batteries. The LiBH4–LiCl solid-state electrolyte exhibiting a lithium ionic conductivity of at 373 K, forms a reversible interface with a lithium metal electrode and has a wide electrochemical potential window up to 5 V. By means of the high-energy mechanical ball-milling technique, we prepared a composite powder consisting of elemental sulfur and mixed conductive additive, i.e., Ketjen black and Maxsorb. In that composite powder, homogeneous dispersion of the materials is achieved on a nanometer scale, and thereby a high concentration of the interface among them is induced. Such nanometer-scale dispersals of both elemental sulfur and carbon materials play an important role in enhancing the electrochemical reaction of elemental sulfur. The highly deformable LiBH4–LiCl electrolyte assists in the formation of a high concentration of tight interfaces with the sulfur-carbon composite powder. The LiBH4–LiCl electrolyte also allows the formation of the interface between the positive electrode and the electrolyte layers, and thus the Li-ion transport paths are established at that interface. As a result, our battery exhibits high discharge capacities of 1377, 856, and 636 mAh g–1 for the 1st, 2nd, and 5th discharges, respectively, at 373 K. These results imply that complex hydride-based solid-state electrolytes that contain Cl-ions in the crystal would be integrated into rechargeable batteries. [ABSTRACT FROM AUTHOR]