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Why does Li-ion batteries self-discharge happen?

Discussion in 'XTAR (flashlights, battery chargers, batteries)' started by XTAR, Sep 2, 2022.

  1. XTAR
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    Self-discharge is a natural process that occurs with all batteries. And it may happen faster if the battery isn’t being used properly or stored in poor conditions. For example, if you store Li-ion batteries during summer after being fully charged, you may find even faster self-discharge with the batteries. And there are some factors affecting Li-ion batteries’ self-discharge.

    *Temperature
    High temperature will cause the positive electrode metal to dissolve faster. The activity of the electrolyte is enhanced, and the side reactions between the electrolyte and the electrode are intensified. The electrons are more active and easily participate in the side reactions of the negative electrode/electrolyte. All of these will lead to batteries’ self-discharge intensification.

    *SOC (State of Charge)
    At the same temperature, the battery capacity under high SOC conditions decays faster. It’s because under high SOC conditions, the negative electrode is in a lithium-rich state, which makes it easier to form an electron-ion-electrolyte complex, which exacerbates the reversible self-discharge of the battery.

    *Moisture
    The most common cause of Li-ion battery self discharge is moisture. The electrolyte solvent or water in the battery get dissolved by the moisture, creating an imbalance in the electrolyte of the battery. If this happens, it may cause an electric short or a leakage.

    You could see higher temperatures and humidity levels will speed up the self-discharge on Li-ion batteries. To prolong Li-ion batteries life, it’s suggested to store them in a cool, dry place. And for ling-time storage, you could charge your Li-ion batteries to around 40-50% of their capacity, to slow down the self-discharge rate.