Li-rich Li₂TMCl₄ system (TM = V, Cr, Fe, Mn, and Co) was studied as an alternative to LiFePO₄ due to its high ionic conductivity (10^-5 S/cm for Li₂FeCl₄ at 60°C ^[1]), similar theoretical capacity (165 mAh/g for 1.2 Li⁺ out of Li₂FeCl₄ vs. 170 mAh/g for 1 Li⁺ out of LiFePO₄^[2]), and higher working voltage (3.7 V for Li₂FeCl₄ vs. 3.4 V for LiFePO₄ ^[1]). These cathode materials were successfully synthesized by ball milling and solid state reaction techniques, using LiCl and TMCl₂as the precursors. The phase compositions were determined by X-ray diffraction and confirmed with Rietveld refinements.

Swagelok devices were designed and built for electrochemically characterization. The cathode, a mixture of the active material, carbon black, and solid electrolyte, was consolidated with solid electrolyte using spark plasma sintering (SPS). The design of the devices and techniques were validated using standard materials, such as LiCoO₂ and LiFePO₄purpose., as well as EIS, CV, XRD, and galvanostatic cycling tests. The standard materials were also used to compare against the performance of the Li₂TMCl₄ cathode material system.

1. Wang, C. & Hong, J. Electrochem. Solid-State Lett. 10, A65 (2007).
2. Whittingham, M. S. Chem. Rev. 104, 4271–301 (2004).