Most of today’s electric vehicles (EVs) use lithium-ion batteries whose cathodes include nickel, manganese, and cobalt (N, M, and C). NMC batteries provide an energy density of around 270 Wh/kg, which allows an EV to travel upwards of 300 miles (480 km) on a charge, but they come with some baggage. First, nickel and cobalt are mined primarily in Russia and the Congo, respectively. Sanctions against Russia and questionable labor practices in the Congo are causing the industry to seek out alternatives. Second, NMC batteries are susceptible to thermal runaway, potentially leading to catastrophic fires. Finally, with a lifespan of around 1000 cycles, NMC batteries will need to be replaced every decade or so—roughly half of an EV’s expected lifetime.

Lithium-ion batteries that use iron and phosphorous in their cathodes, known as LFP batteries, are an alternative to NMC batteries. However, their higher weight per unit of energy (i.e., lower energy density) results in less EV range. This drawback has relegated LFPs to stationary applications, where weight isn’t an issue, and entry-level EVs, where price outweighs range. But with the war in Ukraine causing more volatility in the nickel market, the U.S. Inflation Reduction Act emphasizing domestic sources of battery materials, the short lifespan of NMC batteries, and recent improvements in LFP energy density, we’re approaching the point where LFP is poised to take over as the standard EV battery. Since the first three factors are straightforward, we’ll look at the engineering advancements that are making LFP more of a player in the EV market.

LFP vs NMC

Besides their lower energy density, LFPs have been known to suffer from poor charging performance at very low temperatures. Engineers are overcoming that by manipulating thermal regulation through the battery management system, but it does take longer to charge at temperatures below freezing. Keep in mind that the battery pack gets warm as the car is being driven, so the battery temperature is normally higher than the ambient temperature.

On the other hand, LFP batteries have many advantages over NMCs, including an abundance of domestically available materials, lower cost, higher ignition point, and longer lifespan. In 2020, the Journal of the Electrochemical Society published a report showing that LFP batteries outlast their NMC rivals under various real-world conditions. Authors Yuliya Preger et al. showed that LFPs deliver nearly five times as many charge cycles as NMCs and provide a higher round-trip efficiency. LFPs also suffer less degradation than NMCs at higher temperatures and at faster charging and discharging rates. That means LFPs are better suited to handle high-performance driving and quick charging.

Closing the Energy Density Gap

LFP batteries have a lower energy density than their NMC counterparts, but that fact can be a bit misleading, according to Dan Blondal, CEO of battery company Nano One. Blondal says that the energy density difference is largely at the cell level, but since LFP batteries are less prone to thermal runaway, they can be packed more tightly into a prismatic form factor rather than the more familiar cylindrical housing. That reduces the weight of the battery pack. Manufacturers are also moving to cell-to-frame or cell-to-pack technology, where the cell becomes part of the pack structure, lowering the weight of the whole battery. Even so, LFP batteries still weigh more than NMCs for the same amount of energy, but the energy density gap at the package level is less significant.

Blondal says Nano One is improving the quality and lowering the cost of cathode production for all types of Li-ion batteries, including LFP. The company’s one-pot process reduces the complexity of making cathode material, produces fewer toxic byproducts, and uses less water and energy. Blondal says that the process is less sensitive to the purity of the raw materials, lowering the cost and reducing the environmental footprint of battery manufacturing.

Another battery company, Advanced Cell Engineering, plans a 2023 release of its Advanced LFP cell in a Very Large Format (VLF) prismatic package, which is designed to be part of the battery’s structure.

Advanced Cell Engineering President Tim Poor explained the product to engineering.com: “With an energy density of 250 Wh/kg in our proprietary VLF prismatic format, our Advanced LFP’s energy density is 30 percent to 50 percent higher than other commercially available LFP cells, which translates to an equivalent increase in vehicle range. And, since it does not cost more to produce Advanced LFP cells, that added range comes without a higher price tag. Alternatively, in vehicles that use LFPs and get sufficient range, switching to Advanced LFPs will enable automakers to use fewer cells for the same range, passing along the savings to consumers."

Advanced Cell Engineering’s prismatic packaging isn’t the only factor in improving energy density. “Taking a holistic approach, we have re-engineered the full cell chemistry and cell design for LFP cells,” Poor said. “In addition to significant innovation in the anode, every part of the chemistry and formulation has been invented and/or optimized by our technical team. This includes the specific electrode formulations, material specifications, electrolyte chemistry, separator, conductive additives and/or dopants, etc.”

Tesla was one of the first EV makers to switch to LFP batteries. Thanks to a highly efficient powertrain and lightweight design, a Tesla needs less energy to drive the same distance as many other EVs in its class. The company’s standard-range vehicles are now equipped with LFPs, although its high-performance line will still use NMC batteries for the time being. As EV makers continue to trim vehicle weight and improve efficiency, the energy density in a standard LFP will provide plenty of range.

The Future of LFP 

In addition to passenger vehicles, LFPs are often employed in systems where batteries are frequently charged and discharged, such as grid-level and residential energy storage systems, where a little extra weight doesn’t matter. LFPs are also appropriate for buses, fleet vehicles, forklifts, golf carts, boats, and recreational vehicles since they’re depleted and recharged on a daily basis.  

Sometimes a blend of economics, politics, and technology converge into a perfect storm that leads to industry changes. We may be at that point with LFP batteries, as market forces, policy decisions, and engineering enhancements continue to make LFP batteries more attractive to EV manufacturers and buyers. With these factors in mind, LFP may be the fabled “million-mile battery” that we’ve been anticipating.