Self-discharge

Self-discharge is a phenomenon in batteries in which internal chemical reactions reduce the stored charge of the battery without any connection between the electrodes or any external circuit.[1] Self-discharge decreases the shelf life of batteries and causes them to initially have less than a full charge when actually put to use.[1]

How fast self-discharge in a battery occurs is dependent on the type of battery, state of charge, charging current, ambient temperature and other factors.[2] Primary batteries aren't designed for recharging between manufacturing and use, thus have battery chemistry that has to have a much lower self-discharge rate than older types of Secondary cells, but they have lost that advantage with the development of rechargeable Secondary Cells with very low self discharge rates like Low Self Discharge NiMH cells.

Self-discharge is a chemical reaction, just as closed-circuit discharge is, and tends to occur more quickly at higher temperatures. Storing batteries at lower temperatures thus reduces the rate of self-discharge and preserves the initial energy stored in the battery. Self-discharge is also thought to be reduced as a passivation layer develops on the electrodes over time.

Typical self-discharge by battery type
Battery chemistryRechargeableTypical self-discharge or shelf life
Lithium metalNo10 years shelf life[3]
AlkalineNo5 years shelf life[3]
Zinc–carbonNo2–3 years shelf life[3]
Lithium-ionYes2–3% per month[3]; ca. 4% p.m.[4]
Lithium-polymerYes~5% per month[5]
Low self-discharge NiMHYesAs low as 0.25% per month[6]
Lead–acidYes4–6% per month[3]
Nickel–cadmiumYes15–20% per month[3]
Nickel–metal hydride (NiMH)Yes30% per month[3]

References
  1. Garche, Jurgen; Dyer, Chris K.; Moseley, Patrick T.; Ogumi, Zempachi; Rand, David A. J.; Scrosati, Bruno (2013). Encyclopedia of Electrochemical Power Sources. Newnes. p. 407. ISBN 978-0-444-52745-5.
  2. Moseley, Patrick T.; Garche, Jurgen (27 October 2014). Electrochemical Energy Storage for Renewable Sources and Grid Balancing. Newnes. pp. 440, 441. ISBN 9780444626103.
  3. Battery performance characteristics, MPower UK, 23 February 2007. Information on self-discharge characteristics of battery types
  4. Umweltbundesamt: "BATTERIEN UND AKKUS" (3,65 MB PDF), October 2012; visited 2018-02-14
  5. "Lithium Polymer Battery Technology" (PDF). Retrieved 14 March 2016.
  6. Panasonic:

Further reading

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