Unleashing the Power of NMC811: Pioneering Extreme Fast Charging for EV Batteries

The race to develop electric vehicle (EV) batteries that charge as swiftly as filling up a gas tank has been relentless. While the path to ultra-fast charging is paved with challenges, the key to revolutionizing the EV industry lies in the materials that make up these batteries.

High nickel layer oxide cathode materials, specifically NMC811 (comprising 80% nickel, 10% manganese, 10% cobalt), are at the forefront of this electrifying transformation.

NMC811 holds the potential to empower EV batteries with faster charging capabilities, extended range, and prolonged service life. To delve deeper into the world of NMC811, a research team led by the Idaho National Laboratory (INL) has embarked on a quest to uncover its attributes and unravel its potential.

EVs at a Turning Point

The automotive landscape is at a crossroads, with electric vehicles gaining substantial traction. In 2022, 5.8% of newly purchased vehicles in the U.S. were electric, a significant increase from 3.2% in 2021.

Moreover, the total sales of EVs surpassed 800,000 for the first time. Yet, one of the industry's most formidable challenges is to develop a battery that can be recharged within 10 to 15 minutes - the timeframe akin to refueling a traditional car.

Achieving this level of extreme fast charging exerts significant pressure on every component of the battery, with chemical, material, and electrode engineering playing pivotal roles in the pursuit of performance.

Uncovering the Mysteries of NMC811

Lithium-ion batteries, the heart of EVs, function by moving ions from the positive electrode to the negative electrode through their electrolytes. While researchers have delved into the complexities of lithium plating on the negative electrode, less has been explored regarding the impact of extremely fast charging on the positive electrode.

Now, INL researchers led by Tanvir Tanim have taken up the mantle, sharing their insights in the June 2022 publication titled "A Comprehensive Understanding of the Aging Effects of Extreme Fast Charging on High Ni NMC Cathode."

The research aims to provide a thorough understanding of how materials degrade during rapid charging, particularly in the context of NMC811. NMC811 outshines its counterparts by offering greater subsurface degradation coupled with superior cycle life performance compared to NMC532, a material more prevalent in batteries over five years ago.

Diving Into the Research

The research investigates the aging behavior of NMC811 under various fast charging conditions, with the most extreme scenario simulating over 200,000 miles of driving.

The team, under the stewardship of INL, assessed batteries ranging from 35% to 100% charge under different fast charging rates. Their focus revolved around uncovering the failure mechanisms, including the intricacies of mechanical fractures during the charging cycle.

Advanced scanning electron microscopy technology enabled the researchers to scrutinize particle structures, allowing for an understanding of crack formation under different cyclic conditions.

The Unexpected Advantage of NMC811

Comparing the two cathode materials, the research team discovered a rather unexpected revelation. While NMC811 exhibited greater subsurface degradation, it outperformed NMC532 in cycle life performance.

This phenomenon can be attributed to the molecular arrangement within NMC811, which creates a freer lithium-ion channel. NMC811 also boasts higher conductivity and ion mobility, resulting in increased charge storage capabilities for the battery.

Additionally, NMC811 exhibits slower impedance growth - a key indicator of internal resistance. Batteries with low impedance can deliver high current on demand, an essential feature for EVs.

Unlocking the Potential of NMC811

Overall, NMC811 presents higher specific energy and better conductivity compared to variants with lower nickel content.

Additionally, its reduced cobalt content translates to lower costs, making it an economically viable option for battery development. As the findings of this research conducted at the National Laboratory are shared with the U.S. Department of Energy, the scientific community, and the automotive industry, the potential applications of NMC811 are expected to evolve rapidly.

Several car manufacturers have already begun implementing NMC811 in their positive electrodes, reinforcing the significance of this study in reshaping the EV landscape.