Electrochemical Properties of Acetylene Black/Multi-walled Carbon Nanotube Cathodes for Lithium Thionyl Chloride Batteries at High Discharge Currents

Abstract

Lithium thionyl chloride (Li/SOCl 2) batteries exhibit the highest energy densities seen in commercially available primary batteries because of their high operating voltages and discharge capacities. They are widely used in various extreme environments; however, they show signs of degradation at high discharge currents. The discharge performance of Li/SOCl 2 is considered to be greatly dependent on the carbon materials used in the cathode. Therefore, suitable carbon materials must be chosen to improve discharge performances. In this work, we investigated the discharge properties of Li/SOCl 2 batteries in which the cathodes contained various ratios of acetylene black (AB) and multi-walled carbon nanotubes (MWCNTs) at high discharge currents. It was confirmed that the MWCNTs were effectively dispersed in the mixed AB/MWCNT cathodes. Moreover, the discharge capacity and operating voltage improved at high discharge currents in these mixed cathodes when compared with pure AB cathodes. It was found that the mesopores present in the cathodes have a strong impact on the discharge capacity, while the macropores present on the cathode surface influence the discharge properties at high discharge rates in Li/SOCl 2 batteries. These results indicate that the ratio of mesopores and macropores in the cathode is key to improving the discharge performance of Li/SOCl 2 batteries, as is the dispersion of the MWCNTs.

The Impact of Temperature on the Performance and Reliability of Li/SOCl2 Batteries

“…Song et al found that the mesopores in the cathode of Li/SOCl 2 batteries had a significant impact on the discharge capacity, while the large pores on the cathode surface affected the discharge performance at high discharge rates. The ratio of mesopores to large pores in the cathode was a key factor in improving the discharge performance of Li/SOCl 2 batteries [4]. Lee et al proposed that the crystalline deposition of lithium chloride on the carbon cathode formed a dense layer, which hindered the diffusion process of SOCl 2 and affected the battery's discharge capacity and voltage [5].…”