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 edit
| 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 edit
- ^ a b 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.
- ^ Moseley, Patrick T.; Garche, Jurgen (27 October 2014). Electrochemical Energy Storage for Renewable Sources and Grid Balancing. Newnes. pp. 440, 441. ISBN 9780444626103.
- ^ a b c d e f g 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" (PDF). Retrieved 14 March 2016.
- ^ Panasonic
Further reading edit
- Wu and White, "Self-Discharge Model of a Nickel-Hydrogen Cell." Journal of the Electrochemical Society, 147 (3) 901-909 (2000)
External links edit
- Battery dischargers Description and treatment of sulphated batteries