Voltage hysteresis phenomenon of lithium thionyl chloride battery and its elimination method

The phenomenon of voltage hysteresis occurs when lithium subbattery is discharged with high current after long-term small current or long-term static storage.

2SOCl2 +4Li → 4LiCl+SO2+ S

Lithium subbattery is a non-rechargeable lithium metal battery, its electrolyte and cathode material are thionyl chloride. When metal lithium and thionyl chloride reaction time, will generate lithium chloride oxide product, the product will be attached on the surface of metallic lithium oxide, we call it the oxide film (also called passivation film), the layer of oxide film can prevent the continued rapid reaction, in other words, this layer of oxide film on the cathode metal lithium played a protective role, this is why the battery has long time storage features.

After the formation of lithium chloride protective film, the internal stop reaction is only relative, not absolute, whether suitable for large current discharge power battery, or suitable for small current discharge energy battery, as long as the battery has been static, the internal very slow chemical reaction will make the passivation film gradually thickened. The appearance of passivation film makes the internal resistance of lithium subbattery change over time.

It is the generation of passivation film that makes the annual self-discharge rate of lithium subbattery very small at room temperature (energy type less than 1%, power type less than 2%). Coupled with the energy density of lithium subbattery up to 700Wh /kg, lithium thionyl chloride battery has become the absolute star product in the low-power and long-life application field of the Internet of Things.
At present, the lag phenomenon of lithium subbattery cannot be completely solved by internal formula, but it can be eliminated by some methods in practical application. The ER14505M, for example, can be activated by discharging with a 15-ω resistor for 10-20 minutes before use if stored for half a year.

Other types of lithium batteries for long time storage, eliminate lag corresponding safety resistance size and discharge time, please consult Langsheng for details.

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