Preparation of high-performance copper fluoride cathode material for thermal batteries: effect of heat treatment temperature of precursor ammonium copper fluoride

A copper fluoride with small size and high purity is very important to present its ability as a cathode material for lithium thermal batteries (LTBs). In this paper, we investigate the effect of the heat treatment temperature of the precursor ammonium copper fluoride on the preparation of a high-performance copper fluoride cathode. The color of CuF2 gradually changes from white to dark brown as the heat treatment temperature of the ammonium copper fluoride precursor is increased due to the change in dimensions and morphology. The CuF2-250 prepared at the heat treatment temperature of 250 ℃ has a small D50 particle size of 1.838 µm (agglomeration of particles from 50 to 100 nm), high purity, large BET surface area of 16.3649 m2/g, and excellent working properties. Its operating voltage reached as high as 3.5 V in the initial activation stage at a discharge current density of 500 mA/g, which is attributed to the better conductivity caused by its small size favorable shortened Li+ diffusion path, and its specific capacity and discharge time at the cut-off voltage of 1.5 V were 498 mAh/g close to 94