An Explainer on 4th Gen LFP (High Compaction Density) Material

LFP (Lithium Iron Phosphate) cathode active material (CAM) has been gaining market share in the Lithium-ion battery industry thanks to its low cost, high cycle life and high safety. However, it has limitations, such as low energy density (gravimetric and volumetric) due to its lower material density (g/cm3). Lower material density leads to lower compaction density of an electrode.

The compaction density of an electrode is defined as the amount (grams) of material that can be loaded in a given volume (cm3). The volume of material is calculated by multiplying the areal density of the material by the thickness of the material coating on the current collector.

Higher compaction density allows for more material to be loaded in a given volume, leading to higher cell capacity. The launch of high-compaction-density LFP material is poised to give a tough fight to mid-nickel cathodes such as NMC 532, which is close to 200Wh/Kg gravimetric energy density. Today’s LFP cells are between 160Wh/Kg and 180Wh/Kg energy density.

What is 4th Gen LFP Material?

LFP material with a compaction density of 2.6g/cm3 and above is considered 4th generation. This is a high-compaction density LFP material.

When CAM particles of equal size are packed together, gaps can form between them. Therefore, the right amount of smaller-sized CAM particles is required to fill these gaps and increase the packing density of material loaded in a given volume. A high-compaction density material is engineered with the right ratio of large and small particles for maximum space management while making an electrode. This material will focus on the EV application LFP cells market. With the right design, the cell can achieve lower internal resistance and allow for fast charging.

Potential updated cell models – A fixed-dimension cell such as the 33140 cylindrical LFP cell is expected to increase in capacity from 15Ah to 17Ah. Prismatic cells used in EVs are also expected to have a higher capacity for the same dimensions or be reduced in size for the same capacity.

Disadvantages

• Expected to have a lower cycle life in the beginning since the product is not very mature.

• Decreasing the gaps/pores between the particles can reduce the cathode particle surface area interaction with the electrolyte and reduce the speed of ion movement.

• Higher compaction density can lead to polarization during discharge, leading to lower voltage and thereby reducing the discharge energy.

About the author

Rahul Bollini, Bollini Energy

Rahul is an R&D expert in Lithium-ion cells with 10 years of experience. He founded Bollini Energy to assist in deep understanding of the characteristics of Lithium-ion cells to EV, BESS, BMS and battery data analytics companies across the globe. Contact | +91-7204957389; bollinienergy@gmail.com.

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