Troubled minds: the lithium revolution

Ex-Changi prisoner of war, and psychiatrist, Dr John Cade, sought a pharmacological treatment for bipolar disorder in the 1940s ; and in so doing, marked the beginning of psychopharmacology.

Stoichiometric changes in lithium conducting materials based on Li1+xAlxTi2−x(PO4)3: impedance, X-ray and NMR studies

The lithium fast-ion conductor, Li_1+xAl_xTi_2−x(PO₄)₃ (LATP) has been modified via changes in stoichiometry during the processing steps. The resultant changes have been followed using ²⁷Al MAS NMR, X-ray powder diffraction and impedance spectroscopy. The most important changes were those of the form Li_1.3+4yAl_0.3Ti_1.7−y(PO₄)₃. It was possible to remove the AlPO₄ phase (both tridymite and berlinite polymorphs), as monitored by X-ray diffractograms and ²⁷Al NMR spectra. Consequently, these changes appear to result in increased grain boundary conductivity of the LATP material.

The enhancement of lithium ion dissociation in polyelectrolyte gels on the addition of ceramic nano-fillers

Nano-particle oxide fillers including TiO₂, SiO₂ and Al₂O₃ have previously been shown to have a significant affect on the properties of both polymer and polymer gel electrolytes. In some cases, conductivity increases of one order of magnitude have been reported in crystalline PEO–base complexes. In this work, we report the effects of TiO₂ and SiO₂ on a poly(Li-AMPS)-based gel polyelectrolyte. Impedance spectroscopy and pfg-NMR spectroscopy indicates an increase in the number of available charge carriers with the addition of filler. An ideal amount of ceramic filler has been identified, with additional filler only saturating the system and reducing the conductivity below that of the pristine polyelectrolyte system. SEM micrographs suggest a model whereby the filler interacts readily with the sulfonate group; the surface area of the filler being an important factor.

The zwitterion effect in ionic liquids : towards practical rechargeable lithium-metal batteries

Practical lithium-metal batteries are the ultimate goal of battery researchers. The addition of a zwitterionic compound (see Figure) to an ionic liquid electrolyte doped with a lithium salt results in a 100% enhancement of the current densities achieved in the cycling of a lithium-metal cell. This phenomenon arises due to increased lithium-ion mobility or a reduced solid electrolyte interphase layer resistance.

Ionic conductivity studies of polymeric electrolytes containing lithium salt with plasticizer

New plasticized polymer electrolytes were synthesized based on poly ethylene oxide (PEO), Poly (N,N-dimethylamino-ethyl-methacrylate) (PDMAEMA), LiN(CF₃SO₂)₂ (LITFSI) as the salt and tetraethylene glycol dimethyl ether(tetraglyme) and EC + PC as plasticizers. The preparation and characterization of the polymer electrolytes were investigated as a function of temperature and various concentrations of LITFSI. Impedance spectroscopy and differential scanning calorimeter (DSC) were used to characterize the effects of various temperature, lithium salt concentration and two plasticizers on conductivity. The complex of PDMAEMA/PEO/LiTFSI/tetraglyme (S2) exhibits higher conductivity (4.74 × 10⁻⁴ S cm⁻¹at 25 °C) than PDMAEMA/PEO/LiTFSI/EC + PC (S1).

Lithium-polymer battery based on an ionic liquid–polymer electrolyte composite for room temperature applications

A lithium-polymer battery based on an ionic liquid–polymer electrolyte (IL–PE) composite membrane operating at room temperature is described. Utilizing a polypyrrole coated LiV₃O₈ cathode material, the cell delivers >200 mAh g⁻¹ with respect to the mass of the cathode material. Discharge capacity is slightly higher than those observed for this cathode material in standard aprotic electrolytes; it is thought that this is the result of a lower solubility of the LiV₃O₈ material in the IL–PE composite membrane.