Lithium Iron Phosphate Battery (LFP)

Lithium ion batteries with lithium iron phosphate cathodes (LiFEPO4).

What is a Lithium Iron Phosphate (LFP) Battery?

Lithium Iron Phosphate (LFP) batteries are part of the large family of Lithium-Ion (Li-Ion) batteries. These rechargeable batteries work on the principle of reversible exchange of lithium ions (Li+) between an anode (negative electrode) and a cathode (positive electrode).

In Lithium Iron Phosphate batteries, the cathode is made of a lithium iron phosphate. We also speak of LiFe or LiFePO4 batteries, in reference to the 3 components used: lithium (Li), iron (Fe) and phosphate (P).

The specificities of a Lithium Iron Phosphate battery

Since they do not release oxygen or manganese, Lithium Iron Phosphate cathodes are more chemically stable than other Li-Ion technologies such as cobalt oxide batteries. LiFe batteries are therefore less prone to fire and explosion, and therefore safer to use.

With this type of battery, the number of possible cycles is also higher. Indeed, the stability of the positive electrode makes it possible to extend their life and to save up to 30% of energy compared to other Lithium-ion batteries.

In terms of cost, LFP batteries are not the cheapest on the market. But with the same performance, they offer a very good quality/price ratio given their longevity.

The big disadvantage of LFP batteries is their lower mass energy density compared to cobalt-based technologies.

Examples and practical application

In the vast field of lithium ion batteries, Lithium Iron Phosphate batteries stand out for their cobalt-free technology. Considering the toxicity of this component and its oxides, it is a great asset on the ecological level.

Offering a lower mass density than technologies incorporating cobalt oxides, this type of Li-Ion battery is sufficient to replace the old lead-acid batteries used to start internal combustion engines in thermal vehicles.

Lithium Iron Phosphate batteries are also suitable for many other mobile applications:

  • to store and exploit solar or wind energy in isolated sites ;
  • for the supply of stands in the field of events, for lighting or sound purposes ;
  • for the motorization of light vehicles with low mobility such as motorcycles, scooters or electric bikes...

Their great stability and durability over time due to a high number of charges/ discharges makes it a very reliable battery on the long term.

Lithium Iron Phosphate batteries in figures

The mass energy density of lithium iron phosphate (LFP) batteries was 90 to 120 Wh/kg in 2017.

For comparison, the mass density posted in the same year was:

  • from 200 to 260 Wh/kg for NCA (Nickel-Cobalt-Aluminium) batteries ;
  • from 150 to 200 Wh/kg for LCO (Cobalt Dioxide-Lithium) or NMC (Nickel-Manganese-Cobalt) batteries.

Thanks to the progress made with this technology, the mass energy density of LFP batteries was estimated at 200 Wh/kg in 2020. This led the manufacturer Tesla (in June 2020) to bet on the LFP technology to equip its future Model 3. These lithium iron phosphate batteries will be manufactured by the Chinese company CATL.

The number of cycles of a Lithium Iron Phosphate battery can go from 3000 to over 10, 000 depending on the conditions of use (depth of discharge, ambient temperature...), with an average life span of about 7 years.

Regulatory framework

Due to their less dangerous nature, there are far fewer restrictions on transport and storage for lithium iron phosphate batteries than for lithium cobalt batteries.