Low-Temperature Ionothermal Synthesis of Li-Ion Conductive Li₄B₇O₁₂Cl Solid-State Electrolyte

Abstract

Li-ion conductive polycrystalline Li4B7O12Cl to be used as a solid-state electrolyte was successfully synthesized by an ionothermal route at a low temperature. The reaction of lithium acetate dihydrate, boric acid, and copper­(II) chloride dihydrate in trihexyltetradecylphosphonium chloride at 130 °C led to single-phase Li4B7O12Cl within 10 h. Li4B7O12Br was also successfully synthesized in a similar way. The ionic conductivity, activation energy, and electrochemical window of Li4B7O12Cl electrolyte were measured. A relatively high ionic conductivity of 3 × 10–4 S cm–1 at room temperature was detected. A linear sweep voltammogram of the Li4B7O12Cl electrolyte exhibited an electrochemical stability of up to 4.3 V vs. Li/Li+ under the measured conditions. The fabricated {Li ∥ Li4B7O12Cl ∥ Li} symmetrical cell exhibits a relatively low voltage hysteresis of 120 mV for 60 cycles.

Direct Recycling of Spent NCM Cathodes through Ionothermal Lithiation

“…Targeting a mild experimental condition for direct recycling of spent NCM, the ionothermal synthesis strategy stands out using ionic liquids (ILs) simultaneously as both the solvent and potential template or structure-directing agent in the formation of solids. [31][32][33][34] Our group have reported the first ionothermal synthesis of silica aerogel, in which ILs as the efficient solvents provided a long aging time for stable aerogel structures. [35] The ionicity of ILs supplies strong Coulombic interactions between the constituent ions and the intrinsic nonvolatility provides for the essentially null vapor pressure.…”

Inorganic Synthesis Based on Reactions of Ionic Liquids and Deep Eutectic Solvents

“…Reproducedwith permission. [123] Copyright 2019, American Chemical Society.b )The crystal structure of Sr 2 B 5 O 9 Cl. Reproducedwith permission.…”

“…Ruck and co‐workers investigated the ionothermal synthesis of several borate halide compounds using quaternary phosphonium halide ILs as both the solvent and halide source. The Li‐ion‐conductive polycrystalline Li 4 B 7 O 12 Cl can be obtained in [P 66614 ]Cl in the presence of lithium acetate dehydrate and boric acid at a temperature of 200 °C for 48 h. [123] The borate framework, constructed from [BO 4 ] tetrahedra and [BO 3 ] triangles, forms interpenetrating channels, within which Li + and Cl − are trapped (Figure 6 a ). Similarly, Li 4 B 7 O 12 Br can also be synthesized using [P 66614 ]Br as the bromide source.…”

Nanostructured Borate Halides for Optical Second Harmonic Generation at Surfaces

“…Previous works in our group reported the use of ILs as solvents in the resource‐efficient synthesis of inorganic crystalline materials. By using the ionothermal route, a variety of materials have been synthesized including some functional materials and chemically interesting materials . Moreover, mechanisms of some of these ionothermal reactions were investigated .…”

“…Phosphonium‐based ILs demonstrate excellent thermal stability among the commonly used ILs, and ionic liquids P 66614 X ( X = Cl, Br) were perfectly‐behaved in the synthesis of borate halides in our previous publication. [26a] Here we report the functional design of task‐specific ILs by adding lithium bis(trifluoromethylsulfonyl)amide (LiNTf 2 ) to phosphonium‐based ionic liquids, from which we crystallized nanostructured samples of Sr 2 B 5 O 9 X ( X = Cl, Br) and Ba 2 B 5 O 9 Cl at low temperature. The nonlinear optical response of the obtained borate halide powders was tested using confocal SHG microscopy.…”