Page | 002 Environmental Health & Radiation Safety
LITHIUM BATTERY SAFETY PROGRAM
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Rev. 9-17-js
3.0 BACKGROUND INFORMATION
Lithium-based batteries, especially lithium-ion and lithium-polymer rechargeable batteries, have become highly popular due to their favorable power to weight ratio and the fact that lithium-polymer batteries can be configured in various shapes and sizes. Generally speaking, lithium batteries are quite safe, however if damaged or used without proper care, can overheat, ignite and burn aggressively. Lithium battery users must be acquainted with their unique vulnerabilities.
The most important safety consideration for lithium-ion and lithium-polymer batteries is to treat the battery as if it will ignite at any time. Even though the odds are remote, if each battery is segregated from combustible materials during storage, charging and in use, in the rare possibility that a fire does occur, the odds are better that it will be limited to the battery itself.
3.1 Battery Categories - Batteries are classified into two categories: Primary and Secondary.
3.1.1 Primary batteries are not rechargeable. Examples of lithium-based primary batteries are button cells and camera/smoke detector batteries. Primary batteries contain metallic lithium which reacts violently with moisture. The lithium is hermetically sealed within the rigid battery container. Fires involving primary lithium metal batteries are extinguished by smothering with a material such as sand or a class D fire extinguisher that is rated for metal fires. Water is not an effective extinguishing material for primary lithium battery fires.
3.1.2 Secondary batteries are rechargeable. Unlike primary lithium batteries, secondary lithium batteries do not contain metallic lithium, they contain an intercalated lithium compound where lithium ions move back and forth between the battery anode and cathode during discharging and charging. Fires involving secondary lithium-ion or lithium-polymer secondary batteries can be extinguished with a traditional ABC- type fire extinguisher or smothered with a material such as sand.
3.2 Lithium-Ion (Li-Ion) vs. Lithium-Polymer Batteries (LiPo) - The difference between lithium-ion and lithium-polymer batteries is the type of electrolyte used. Lithium-polymer batteries contain a micro porous gel electrolyte instead of a porous separator as found in lithium-ion. Standard lithium-ion batteries require a rigid case to press the electrodes together whereas lithium-polymer batteries use laminated sheets that do not need compression.
3.3 Rechargeable Lithium Battery Voltage – Each individual battery cell has a working voltage range from 3.0 volts minimum recommended discharge, to 4.2 volts full charge. The battery manufacturers use 3.7 volts as the nominal voltage and this value is used to rate the battery. To increase the voltage, additional cells are added together in series, therefore a single cell rechargeable lithium battery will be listed as 3.7 volts and a two cell battery will be listed as 7.4 volts, etc.
3160 Chestnut Street, Suite 400 Philadelphia PA 19104
Tel. 215.898.4453. Fax 215.898.0140. http://www.ehrs.upenn.edu
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