The internal resistance of high-temperature lithium thionyl chloride (LiSOCl2) batteries undergoes changes as they age. LiSOCl2 batteries are known for their high energy density and ability to operate in extreme temperatures, making them suitable for various applications such as industrial devices, medical instruments, and military equipment. However, over time, the internal resistance of these batteries can increase, affecting their performance and overall lifespan.

As LiSOCl2 batteries age, several factors contribute to the changes in internal resistance. One of the main causes is the degradation of the battery's electrolyte. LiSOCl2 batteries utilize a non-aqueous electrolyte composed of lithium tetrachloroaluminate (LiAlCl4) dissolved in thionyl chloride (SOCl2). Over time, the electrolyte can react with moisture or impurities, leading to the formation of passivation layers on the battery's electrodes. These layers increase the resistance within the battery, hindering the flow of ions and electrons.

As the battery undergoes multiple charge and discharge cycles, the active materials within the electrodes can undergo structural changes. The lithium metal anode and the cathode composed of porous carbon and sulfur can experience degradation, resulting in increased resistance. This degradation can be attributed to the formation of a solid-electrolyte interphase (SEI) layer on the anode, which limits the availability of lithium ions for the electrochemical reactions.

Furthermore, the gradual loss of electrolyte due to evaporation and the continuous diffusion of the active materials can also contribute to increased internal resistance. These processes reduce the ionic conductivity within the battery, impeding the efficient transfer of charge.

Overall, the internal resistance of high-temperature LiSOCl2 batteries tends to increase with aging due to electrolyte degradation, electrode structural changes, and electrolyte loss. This increase in resistance leads to reduced battery capacity, lower voltage output, and decreased overall performance. To mitigate the effects of aging, proper storage conditions, regular maintenance, and careful monitoring of battery parameters can be employed. Additionally, ongoing research and development aim to improve the longevity and performance of LiSOCl2 batteries by addressing the factors that contribute to internal resistance changes during aging.