Electrochemical Performance of Thionyl Chloride Batteries

Thionyl chloride batteries, typically employing a lithium anode and thionyl chloride (SOCl₂) catholyte, are distinguished by their exceptionally high specific energy, flat discharge profile and wide operating temperature range. During discharge, lithium oxidises to Li⁺, while SOCl₂ is reduced, forming LiCl and sulfur‐containing intermediates. A thin passivation layer of LiCl develops on the anode surface, modulating electron and ion transport and thereby governing capacity, rate performance and self-discharge. These cells deliver nominal voltages around 3.6 V and energy densities exceeding 400 Wh kg⁻¹, making them indispensable for long-lifetime applications such as remote sensors, medical devices and aerospace systems. Challenges remain in controlling passivation film morphology, mitigating overpotential under high current draw and improving safety during abuse or elevated temperatures. Advances in electrode architecture, catholyte formulation and diagnostic techniques continue to refine our understanding of the interfacial phenomena that underpin performance and reliability.

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Electrochemical Performance of Thionyl Chloride Batteries publication trend

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Technical terms

Catholyte: the liquid medium in a battery that contains the active cathodic reagent and dissolved salts, facilitating electron transfer reactions.

Passivation layer: an insulating film, often LiCl in thionyl chloride cells, that forms on the anode surface and regulates ion and electron flux.

Electrochemical impedance spectroscopy: a technique that applies small AC perturbations over a range of frequencies to measure cell resistance and capacitance, revealing interfacial kinetics.

Electrochemical noise: spontaneous fluctuations in voltage and current arising from microscopic processes at electrode surfaces, used for cell diagnostics.

References

1. The Effects of Pore Size on Electrical Performance in Lithium-Thionyl Chloride Batteries. Frontiers in Materials (2019).
2. Properties and Structure of the LiCl-films on Lithium Anodes in Liquid Cathodes. Acta Chimica Slovenica (2016).
3. Research and diagnostics of the lithium power sources by the method of electrochemical noise. II. Electrochemical Energetics (2009).