FeF 3 /(Acetylene Black and Multi-Walled Carbon Nanotube) Composite for Cathode Active Material of Thermal Battery through Formation of Conductive Network Channels.

Considerable research is being conducted on the use of FeF 3 as a cathode replacement for FeS 2 in thermal batteries. However, FeF 3 alone is inefficient as a cathode active material because of its low electrical conductivity due to its wide bandgap (5.96 eV). Herein, acetylene black and multi-walled carbon nanotubes (MWCNTs) were combined with FeF 3 , and the ratio was optimized. When acetylene black and MWCNTs were added separately to FeF 3 , the electrical conductivity increased, but the mechanical strength decreased. When acetylene black and MWCNTs were both added to FeF 3 , the FeF 3 /M 1 AB 4 sample (with 1 wt.% MWCNTs and 4% AB) afforded a discharge capacity of approximately 74% of the theoretical capacity (712 mAh/g) of FeF 3 . Considering the electrical conductivity and mechanical strength, this composition was confirmed to be the most suitable.