Transition Metal Chlorides NiCl2, KNiCl3, Li6VCl8and Li2MnCl4as Alternative Cathode Materials in Primary Li Thermal Batteries

Transition metal chlorides KNiCl 3 , Li 6 VCl 8 and Li 2 MnCl 4 were synthesized by solid state reaction in sealed quartz tubes and investigated as candidate cathode materials along with NiCl 2 in Li thermal batteries. The structure and morphology were studied and electrochemical properties probed at high temperatures (400°C–500°C) against Li 13 Si 4 by galvanostatic discharge and galvanostatic intermittent titration technique (GITT). All the transition metal chlorides reduced to metal and the products of the discharge mechanism were confirmed by powder X-ray diffraction. NiCl 2 was tested at 500°C and a capacity of 360 mAhg −1 was achieved. KNiCl 3 was tested at different current densities from 15 mA/cm 2 to 75 mA/cm 2 and a high voltage profile 2.30V was achieved at 425°C with a capacity of 262 mAhg −1 . Li 6 VCl 8 was tested at 500°C and a 1.80V voltage plateau at a current density of 7.5 mA/cm 2 was achieved with a capacity of 145 mAhg −1 . Li 2 MnCl 4 was tested at the same current density at 400°C and a capacity of 254 mAhg −1 was achieved. These transition metal chlorides exhibit higher voltage against Li 13 Si 4 and, hence, provide more specific power compared to the well-known metal disulfides MS 2 (M = Fe, Co, Ni) and may be promising cathode materials for Li thermal batteries.