Shortening activation time of thermal battery by hydrogen etching of NiCl2 cathode

Abstract For a high power thermal batteries cathode candidate material NiCl2, the low conductivity leads to low utilization and long activation time. In this case, Ni content and surface roughness are successfully modified for NiCl2 by a simple hydrogen etching technique. After hydrogenation, the activation time drastically shortens from 5.2 s to 1.6 s at high temperature. The discharge voltage and specific power still maintain 2.43 V and 7.59 kW·kg−1, respectively, besides the pulse resistance is reduced to 0.214 Ω due to increased electronic conductivity. This short activation time could be attributed to the more active sites from rough surface and doped metallic Ni. Hence, this work provides a beginning of the further research of NiCl2 as a promising cathode material for thermal batteries of high specific power.