Synthesis and Electrochemical Study of CoNi2S4 as a Novel Cathode Material in a Primary Li Thermal Battery

In this work CoNi2S4 was investigated as a candidate cathode material for Li thermal batteries. The CoNi2S4 was synthesized by a solid state reaction at 550 degrees C in a sealed quartz tube. Neutron powder diffraction was utilized to confirm normal spinel structure up to 200 degrees C, however, there was cation disorder above this temperature. The electrochemical properties of the batteries were investigated at 500 degrees C by galvanostatic discharge to elucidate the mechanism and the products NiS, Co3S4 and Co9S8 of the discharge mechanism were confirmed using powder X-ray diffraction. CoNi2S4 exhibits two voltage plateaus vs Li13Si4 at 500 degrees C, one at 1.75 V and the second at 1.50 V. CoNi2S4 has an overall capacity of 318 mA h g(-1) from OCV 2.58 V to 1.25 V vs Li13Si4 which is comparable to that of the well-known metal disulfides. (C) The Author(s) 2017. Published by ECS. All rights reserved.