While higher energy li-ion chemistries are available, Lithium iron phosphate (LFP) is safest with the longest cycle life due to its stable chemical make-up. A demonstration of how much more stable the LFP chemistry is compared to the high energy Lithium Cobalt Oxide (LCO), used in consumer electronics, is to compare the thermal runaway temperatures – the high temperatures at which the chemistries begin to become unstable and volatile. LCO has a much lower thermal runaway temperature of 150°C (302°F) compared to LFP’s thermal runaway temperature of 270°C (518°F). This large difference shows LFP to be the much safer of the two lithium chemistries.

High energy density is important for battery systems which need to be smaller and lightweight. A more modern cathode chemistry than LCO is Nickel Manganese Cobalt (NMC). NMC is the result of an attempt to balance safety and performance. A version of NMC is the chemistry is utilized in automotive EV battery systems today. EV batteries utilize higher voltages and with the higher energy available, additional safety measures and control must be implemented. The cells heat up quicker, so proper charging is critical.

With larger industrial, motive power battery systems, space is available for the larger batteries, and weight is actually needed for the counterbalance systems. Fast charging is critical and LFP accommodating lead acid charging helps with systems safety. Cycle life and safety is prioritized. The lower voltage of LFP is good match for Lead Acid replacement. This and the tolerance of Lead Acid charging systems make LFP the safest backward compatible option for material handling batteries.

The physical construction of the cell also affects its safety. All lithium batteries contain a critical component called the separator, which is placed in between the anode and cathode layers in the electrode. The separator limits the chemical reaction of the electrode and helps to prevent thermal runaways by closing its porous structure at high temperatures. The safest Li-ion cells incorporate ceramic separators. The ceramic material is resilient at high temperatures and helps prevent the breakdown of the separator that occurs during a thermal runaway event.

The electronics of the Li-ion battery also provide protection against safety events, with incorporated fuses and protection against over-charge, over-discharge and high and low temperature charging. These battery “smarts,” combined with the long cycle life and short charge time seamlessly integrate with the material handling equipment. The fact that the battery is virtually maintenance free over the life-time of the truck, eliminates the possibility for user error and greatly reduces the risks in the workplace.