Physics: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 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 are not designed for recharging between manufacturing and use, and thus to be practical they must have much lower self-discharge rates than older types of secondary cells. Later, secondary cells with similar very low self-discharge rates were developed, like low-self-discharge nickel–metal hydride 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 chemistry | Rechargeable | Typical self-discharge or shelf life |
|---|---|---|
| Lithium metal | No | 10 years shelf life[3] |
| Alkaline | No | 5 years shelf life[3] |
| Zinc–carbon | No | 2–3 years shelf life[3] |
| Lithium-ion | Yes | 2–3% per month;[3] ca. 4% p.m.[4] |
| Lithium-polymer | Yes | ~5% per month[5][better source needed] |
| Low self-discharge NiMH | Yes | As low as 0.25% per month[6] |
| Lead–acid | Yes | 4–6% per month[3] |
| Nickel–cadmium | Yes | 15–20% per month[3] |
| Conventional nickel–metal hydride (NiMH) | Yes | 30% per month[3] |
References
- ↑ 1.0 1.1 Garche, Jurgen; Dyer, Chris K.; Moseley, Patrick T.; Ogumi, Zempachi; Rand, David A. J.; Scrosati, Bruno (2013). Encyclopedia of Electrochemical Power Sources. Newnes. pp. 407. ISBN 978-0-444-52745-5. https://books.google.com/books?id=TAi_QBsTz5UC&pg=PA407.
- ↑ Moseley, Patrick T.; Garche, Jurgen (2014-10-27) (in en). Electrochemical Energy Storage for Renewable Sources and Grid Balancing. Newnes. pp. 440, 441. ISBN 9780444626103. https://books.google.com/books?id=N0Z9AwAAQBAJ&dq=self+discharge+definition&pg=PA420.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Battery performance characteristics, MPower UK, 23 February 2007. Information on self-discharge characteristics of battery types
- ↑ Umweltbundesamt: "BATTERIEN UND AKKUS" (3,65 MB PDF), October 2012; visited 2018-02-14
- ↑ "Lithium Polymer Battery Technology". http://www.manoonpong.com/Other/main_page=page_2.pdf. Retrieved 14 March 2016.
- ↑ Panasonic
Further reading
- Wu and White, "Self-Discharge Model of a Nickel-Hydrogen Cell." Journal of the Electrochemical Society, 147 (3) 901-909 (2000)
External links
- Battery dischargers Description and treatment of sulphated batteries
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