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# A Closer Look at Lithium Iron Phosphate Batteries, Tesla’s New Choice of Battery

October 28, 2021 by Lianne Frith

## Tesla recently revealed its intent to adopt lithium iron phosphate (LFP) batteries in its standard range vehicles. What do LFP batteries have on Li-ion?

While lithium iron phosphate (LFP) batteries have previously been sidelined in favor of Li-ion batteries, this may be changing amongst EV makers. Tesla’s 2021 Q3 report announced that the company plans to transition to LFP batteries in all its standard range vehicles.

This news reflects a larger trend of LFP batteries becoming increasingly popular in next-generation electric vehicles (EVs).

### What Are LFP Batteries?

LFP batteries use lithium iron phosphate (LiFePO4) as the cathode material alongside a graphite carbon electrode with a metallic backing as the anode. Unlike many cathode materials, LFP is a polyanion compound composed of more than one negatively charged element. Its atoms are arranged in a crystalline structure forming a 3D network of lithium ions compared to the 2D slabs from nickel manganese cobalt.

##### Architecture of an LFP battery. Image used courtesy of Rebel Batteries

The LFP battery operates similarly to other lithium-ion (Li-ion) batteries, moving between positive and negative electrodes to charge and discharge. However, phosphate is a non-toxic material compared to cobalt oxide or manganese oxide. What’s more, LFP batteries are capable of delivering constant voltage at a higher charge cycle in the range of 2,000–3,000.

### What Is the Role of Battery Management Systems in LFP Batteries?

LFP batteries are made of more than just connected cells; they include a system that will ensure the battery remains within safe limits. A battery management system (BMS) protects, controls, and monitors the battery in all operating conditions to ensure safety and extend the lifetime of the battery.

##### Chart illustrating how charging metrics affect a battery's lifespan. Image from Illogicdictates and Wikimedia Commons [CC BY-SA 4.0]

While lithium iron phosphate cells are more tolerant than alternatives, they can still be affected by overvoltage during charging, which degrades performance. The cathode material can also oxidize and become less stable. The BMS works to limit each cell and ensures the battery itself is kept to a maximum voltage.

Undervoltage is a concern as the electrode materials break down. The BMS is able to disconnect a battery from the circuit if any cell drops too low. It will also act as a backstop against overcurrent conditions and will shut down operation in the event of a short circuit.

### Why Are LFP Batteries a Desirable Alternative to Li-ion?

The energy density of LFP batteries is lower than the alternative of lithium cobalt oxide (LiCoO2) and has a lower operating voltage. In spite of these challenges, it’s impossible to deny the benefits of LFP batteries in EV vehicles.

#### Low Cost and Low Impact

LFP is known for its low cost with some estimates putting it as much as 70 percent lower per kilogram than nickel-rich NMC. The cost advantage comes from its chemical composition. Iron and phosphorus are mined at enormous scales across the globe and are widely used in many industries.