Solid electrolytes are the key to realize future solid-state batteries that show the advantages of high energy density and intrinsic safety. However, most solid electrolytes require long time and energy-consuming synthesis conditions of either extended ball milling or high-temperature solid-state reactions, impeding practical applications of solid electrolytes for large-scale systems. Here, we report a new and rapid liquid-based synthetic method for preparing a high-purity Li7PS6 solid electrolyte through the stoichemical reaction of Li3PS4 and Li2S. This method relies on facile and low-cost solution-based soft chemistry to complete chemical reaction in extensively short time (2 h). The prepared Li7PS6 solid electrolyte shows a high phase purity, an impressive ionic conductivity (0.11 mS cm–1), and a reasonable electrochemical stability with a metallic lithium anode. Our results highlight the use of an economic and nontoxic solvent to quickly synthesize a Li7PS6 solid electrolyte, which would promote the development of solid-state batteries for next-generation energy storage systems.

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The ability to convert electrical energy into mechanical motion is of significant interest in many energy conversion technologies. Here, we demonstrate the first liquid phase exfoliated WS2-Nafion nanocomposite based electro-mechanical actuators. Highly exfoliated layers of WS2 mixed with Nafion solution, solution cast and doped with Li+ was studied as electromechanical actuators. Resonant Raman spectroscopy, X-ray photo-electron-spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, and AC impedance spectroscopy were used to study the structure, photoluminescence, water uptake, mechanical and electromechanical actuation properties of the exfoliated nanocomposites. A 114% increase in elastic modulus (dry condition), 160% increase in proton conductivity, 300% increase in water uptake, cyclic strain amplitudes of ~0.15% for 0.1 Hz excitation frequency, tip displacements greater than nanotube-Nafion and graphene-Nafion actuators and continuous operation for more than 5 hours is observed for TMD-Nafion actuators. The mechanism behind the increase in water uptake is a result of oxygen atoms occupying the vacancies in the hydrophilic exfoliated flakes and subsequently bonding with water, not possible in Nafion composites based on carbon nanotube and graphene.

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Parallel in situ TEM and XRD heating experiments of LiFePO4 precursors obtained by sol-gel method were conducted to study changes and to understand structural and morphological evolution during synthesis annealing, which is one of the most critical stages in preparing rechargeable cathodes based on these materials. Raman spectroscopy and electrochemical testing were also performed and a basic optimization of the final step of the sol-gel process was demonstrated by comparing in situ heating data with the electrochemical performance of materials annealed at different temperatures. The results obtained from these in situ measurements, at different length scales, provided a detailed picture of the structural and morphological changes and provided a better understanding of the electrochemical behavior of the final LiFePO4 material. The study showed a strong dependence between the electrochemical performance of LiFePO4 synthesized by sol-gel method and annealing temperature. The best performance was obtained with a material annealed at 800 °C.