Lithium iron phosphate

The lithium iron phosphate accumulator (LiFeP04) is based on lithium ion technology. These two chemistries share many advantages and disadvantages however there are significant differences. The LiFePO4 chemistry came out in the early 2000s. It is being used more and more in electric vehicles and energy storage.

It offers a higher number of charge/discharge cycles, about 1,000 to 1,500 cycles at 100% DOD (depth of discharge).

Its energy density is about 14/15% lower than that of lithium ion cobalt.

One of the major advantages over other lithium ion chemistries is its thermal and chemical stability, which greatly improves the safety of the battery. The LiFePO4 cathode is intrinsically safer than the LiCoO2 or the manganese cathode. The Fe-PO bond is stronger than the Co-O bond, so that when it is misused, (short circuit, overheating, etc), the oxygen atoms are much more difficult to remove.

Consequently, lithium iron phosphate cells are much more difficult to inflame when mishandled (especially during charging). It is commonly accepted that LiFePO4 cells do not disintegrate at high temperatures. However, despite this, there is still a risk of thermal runaway in cases of continuous overcharging or incorrect charging procedures.

Advantages:

  • 3 times more cycles than lithium ion cobalt
  • A safer cell
  • Cheaper than lithium ion cobalt
  • Very high discharge current possible
  • A 3.2V nominal voltage which makes it a great alternative to sealed lead batteries. For instance, a 4S battery (12.8V) can be used in place of a traditional 12V lead battery.

Disadvantages:

  • Lower energy density than lithium ion cobalt
  • Performance sometimes not as good as lithium ion cobalt at low temperatures.

After several months of electrical and mechanical testing, we have selected a few 26650 and 18650 cells which cover almost 100% of our customers’ needs. These cells are high current and are more adapted to float charging. They are linked with our range of active or dissipative BMS’.