Lithium batteries are generally safe as long as you don’t decide to drive nails with one or use it for juggling practice but only so long as there are no defects and the batteries are not damaged. When lithium batteries fail to operate safely, they may present a fire or explosion hazard. The NRTL testing and certification process, as well as product recalls, help identify defects in design, manufacturing, and material quality. Damage from improper use, storage, or charging may also cause lithium batteries to fail.
Hazards
Damage to lithium batteries can occur immediately or over a period of time, from physical impact, exposure to certain temperatures, and/or improperly charging lithium-ion batteries
- Physical impacts that can damage lithium batteries include dropping, knocking, crushing, vibrating, and puncturing
- Damage to all types of lithium batteries can occur when the temperatures are too high (e.g., above 100°F)
- External heat sources can also accelerate failure in cells with defects or damage from other causes
- Damage to lithium-ion batteries can occur when the batteries themselves or the environment around the batteries is below freezing (32°F) during charging
- Charging in temperatures below freezing can lead to permanent metallic lithium buildup (i.e., plating) on the anode, increasing the risk for failure
- Charging a device or battery without following manufacturer’s instructions may cause damage to rechargeable lithium-ion batteries
- For example, some manufacturer-authorized chargers will cycle the power to the battery on and off before it is fully charged to avoid overcharging
- Since ultra-fast chargers may not cycle power, do not use them unless the manufacturer’s instructions include them as an option
Both defects in, and damage to, lithium batteries can lead to battery failure. Heat released during cell failure can damage nearby cells, releasing more heat in a chain reaction (i.e., thermal runaway). The high energy density in lithium batteries makes them more susceptible to hazardous thermal runaway. Depending on the battery chemistry, size, design, component types, and amount of energy stored in the lithium cell, lithium cell failures can result in chemical reactions and/or combustion reactions, which can also result in heat releases and/or over-pressurization.
- In chemical reactions, by-products from the electrolyte solution and electrodes can increase the pressure in the cell to the point where the cell walls expand and by-products leak out. Chemical by-products usually include carbon monoxide, carbon dioxide, hydrogen, and hydrocarbons. In many cases, the by-products are also combustible and could ignite.
- In combustion reactions, a thermal runaway releases byproducts that may ignite to cause smoke, heat, fire, and/or explosion. The by-products from a lithium battery combustion reaction are usually carbon dioxide and water vapor. In some lithium batteries, combustion can separate fluorine from lithium salts in the battery. If mixed with water vapors, fluorine produces hydrofluoric acid, which is particularly hazardous because workers may not feel its effects until hours after skin exposure.
Prevention
Workplace injuries from lithium battery defects or damage are preventable and the following guidelines will assist in incorporating lithium battery safety into an employer’s Safety and Health Program:
- Ensure lithium batteries, chargers, and associated equipment are tested in accordance with an appropriate test standard (e.g., UL 2054) and certified by a Nationally Recognized Testing Laboratory (NRTL), and are rated for their intended uses
- Follow manufacturer’s instructions for storage, use, charging, and maintenance
- When replacing batteries and chargers for an electronic device, ensure they are specifically designed and approved for use with the device and they are purchased from the device’s manufacturer or a manufacturer authorized reseller
- Remove lithium-powered devices and batteries from the charger once they are fully charged
- Store lithium batteries and devices in dry, cool locations and in fire-resistant containers
- Avoid damaging lithium batteries and devices
- Inspect them for signs of damage, such as bulging/cracking, hissing, leaking, rising temperature, and smoking before use, especially if they are wearable. Immediately remove a device or battery from service and place it in an area away from flammable materials if any of these signs are present
- If batteries are damaged, remove from service and dispose in accordance with local, state, and federal regulations. Contact a local battery recycling center for disposal instructions
- Follow the employer’s policy or manufacturer’s guidance on how to extinguish small battery fires, which could include using CO2, foam, Class D fire extinguishers (for lithium-metal), ABC dry chemical extinguishers, dirt, or sandy
