UCSD Engineers Developed a Method to Upcycle LFP Batteries Into a Higher-Performing Component

Researchers at the University of California San Diego have developed a new battery recycling process that could transform used lithium iron phosphate (LFP) batteries into higher-performance battery materials instead of simply recovering their raw ingredients. The environmentally friendly technique converts spent LFP cathodes into lithium manganese iron phosphate (LMFP), a next-generation cathode material capable of storing more energy while maintaining the safety and durability that have made LFP batteries popular in electric vehicles and grid-scale energy storage.

The research, published in Joule, offers an alternative to conventional battery recycling methods, which often rely on energy-intensive furnaces or harsh chemical treatments to recover valuable materials. According to the researchers, those approaches generate significant waste, consume large amounts of energy, and produce unnecessary emissions.

LFP batteries have become one of the most widely used lithium-ion battery chemistries because they do not require expensive metals such as cobalt or nickel, making them both affordable and reliable. Today, they account for nearly half of the global lithium-ion battery market. As millions of these batteries approach the end of their service life, finding better ways to recycle them has become increasingly important.

LFP batteries accounted for over 55% of the global EV battery market by capacity deployed in 2025. Their growth is largely driven by cost-efficiency, safety, and widespread adoption in China, where LFP batteries supply approximately 79% of the passenger car and light vehicle market.

The UC San Diego team previously developed a sustainable process that regenerated worn LFP cathodes back into fresh LFP material. While successful, that method only restored the battery’s original chemistry. The new process goes a step further by upgrading the spent material into LMFP, creating a more valuable battery component with improved energy density.

The recycling process begins by opening used battery packs and unrolling the tightly wound internal layers, often referred to as a “jelly roll.” After cutting the layers into smaller sections, they are soaked in water while being gently stirred. This simple mechanical process separates the cathode coating from its aluminum foil backing, allowing the aluminum to be recycled independently.

The remaining cathode material forms a black slurry that is dried and ground into a fine powder. Researchers then introduce carefully selected lithium, manganese, and phosphate compounds needed to create LMFP.

Rather than mixing these ingredients directly, which would result in poor material performance because of incompatible crystal structures, the team developed an intermediate material known as lithium manganese phosphate (LMP). Since LMP has a crystal structure that closely matches LFP, the two materials blend together much more effectively.

The powder mixture is mechanically milled with zirconia balls to create finer particles and ensure the ingredients are evenly distributed. It is then heated in a furnace, where the chemistry takes place. During heating, the added compounds first form LMP, which gradually merges with the spent LFP. Manganese atoms slowly replace a portion of the iron atoms, producing a uniform LMFP crystal structure throughout the material.

During this heat treatment, a thin carbon coating naturally forms around each particle. This coating improves electrical conductivity while helping protect the cathode material during repeated charging and discharging cycles.

The final product delivers higher energy storage capacity than the original LFP while preserving its long cycle life and strong safety characteristics.

Researchers successfully demonstrated the process using spent LFP batteries from multiple manufacturers, showing that the approach works across different battery designs. They also scaled production to kilogram quantities and validated the recycled material in both laboratory coin cells and larger pouch cells similar to those used in commercial electric vehicles and stationary energy storage systems.

Looking ahead, the research team plans to improve the process efficiency and manufacturing yield to make the technology more commercially attractive. Future work will also focus on refining the material’s composition and microscopic structure to further enhance LMFP battery performance.

The study, titled Generating Isomorphous Intermediates Overcomes Synthesis Barriers for Scalable Direct Upcycling of LiFePO4 Battery Cathodes, was led by first author Wei Li, a postdoctoral researcher in the laboratory of Professor Zheng Chen at the UC San Diego Jacobs School of Engineering. The research was primarily supported through a faculty discretionary fund awarded to Chen.