Lithium Safety Brochure
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Safety Lithium Battery 06.13.18
IV. Chemical and Thermal Stability of Lithium Iron Phosphate (LiFePO
4
)
The LiFePO
4
technology that is built into every RELiON battery possesses superior chemical and thermal stability over other
lithium chemistries, which means better battery safety. LiFePO
4
is an intrinsically safer cathode material than cobalt oxide or
manganese oxide cathode. Technically speaking, the fully “lithiated” and “unlithiated” states of LiFePO
4
are physically similar,
which means it’s structurally stable. The iron phosphate oxide bond is stronger than the cobalt oxide bond, so when it is
subjected to overcharge it maintains its physical structure, while other lithium chemistries expand producing excessive heat,
which leads to thermal runaway.
LiFePO
4
chemistry is highly robust during the oxygen loss that accompanies the charge cycle, thereby significantly reducing
the exothermic reaction that is associated with other lithium chemistries. The heat produced by the chemical reaction in a
LiFePO
4
battery during overcharge is only 5.5% of the heat that is produced by a lithium cobalt chemistry. Unlike other lithium
chemistries, LiFePO
4
batteries can operate at temperatures up to 65°C (150°F) and thermal runaway temperature is at a high 270°C
(518°F).
2
When abuse does occur, the phosphate based cathode material will not burn and is not prone to thermal runaway. Lithium
phosphate cells are incombustible in the event of mishandling during charge or discharge, they are more stable under overcharge
or short circuit conditions and they can withstand high temperatures without decomposing.
3
From the viewpoint of safety
performance, a LiFePO
4
battery is similar to a lead-acid battery.
V. Cell Design for Ultimate Safety
RELiON’s cells are all designed with the following
safety features.
1. Explosion-proof stainless steel
2. Built-in Safety Fuse
3. High Pressure Safety Vent
4. Over-Temperature Protection
5. Strong Spot-Welded Connections
Note: While submerged in diesel fuel engulfed
in flames, these cells did not explode.
2
http://www.newcastlesys.com/blog/lithium-ion-vs-lithium-iron-batteries
3
http://www.powerstream.com/LLLF.htm