Lithium iron phosphate batteries are part of a group of batteries called lithium-ion batteries. REVOV Co-founder and Engineering Director, Felix von Borman says, “Specifying a battery as a lithium iron, or lithium iron phosphate, battery implies a host of characteristics which are important when choosing a battery type and provider.”
Revov, a leader in 2nd LiFe lithium iron storage batteries for UPS systems and renewable energy sources, uses lithium iron phosphate batteries, which are a specific subset of the larger group of batteries called lithium-ion batteries.
A lithium battery is formed by four main components: the cathode, anode, electrolyte, and separator.
Lithium iron phosphate batteries (LiFePO4, or LFP as they are referred to by some) have many advantages, says von Bormann. “Revov uses lithium iron phosphate batteries because they have a great energy density and lifecycle, plus a stable chemistry, all while maintaining high thermal runaway, factors which together result in a long life at low costs,” von Bormann explains.
How the batteries work
Lithium-ion batteries are secondary cells created from layers of lithium packed with an electrolyte. A lithium battery is formed by four main components: the cathode, anode, electrolyte, and separator.
The cathode, or positive electrode, determines the capacity and voltage of the battery and is the source of lithium ions. The anode, the negative electrode, stores the lithium ions when the battery is charged and enables the electric current to flow through an external circuit. The electrolyte solution is formed of salts, solvents and additives and serves as the channel to convey lithium ions between the cathode and anode, and the separator is the physical barrier that keeps the cathode and anode apart.
The cathode is a metal oxide, and the anode consists of porous carbon. During discharge the ions flow from the anode to the cathode through the electrolyte and the separator. When charging the battery, the reverse happens, the ions flow from the cathode to the anode.
There are various types of lithium-ion batteries. Although similar on the surface, the different batteries vary in performance and the selection of active materials gives them distinctive qualities.
There are six main types of lithium-ion batteries: Lithium Cobalt Oxide, Lithium Manganese Oxide, Lithium Nickel Manganese Cobalt Oxide, Lithium Iron Phosphate, Lithium Nickel Cobalt Aluminium Oxide and Lithium Titanate.
It is the cathode that differentiates each battery. For example, the lithium cobalt dioxide battery is made with a LiCoO2 cathode while the lithium iron phosphate battery is made with a LiFePO4 cathode. This highlights the technical difference between lithium-ion and lithium iron batteries. Lithium-ion references the mode of electrical transfer inside the battery, where ions travelling in the electrolyte are lithium.
Despite the characteristics they have in common, the different lithium-ion systems and lithium iron batteries differ in terms of their stability, lifespan and application. Lithium iron phosphate has a high current rating and long cycle life; it is more tolerant to full charge conditions and is less stressed than other lithium-ion systems. It has a specific energy of 90/120 watt-hours per kilogram, a nominal voltage of 3.20 V/3.30 Va, a charge rate of 1 C, and a discharge rate of 1-2.5 C.
Von Bormann says lithium iron phosphate loses some distance in terms of specific energy per kilogram but adds, “This is not important in a stationary application where weight is less significant. The lithium iron phosphate cell is superior to other lithium-ion battery chemistries in terms of safety and price, and typically has a higher life expectancy and a higher specific power,” he says.
For more information visit: www.revov.co.za
