MIT Pioneers Cost-Effective, High-Energy Batteries with Innovative Disordered Rock Salt Cathodes

A breakthrough in battery technology could soon revolutionize energy storage across multiple industries, from smartphones to electric vehicles. Researchers at MIT have developed a new class of battery cathodes that promises high energy density and improved stability, potentially making energy storage more affordable and efficient.

Led by Ju Li, the Tokyo Electric Power Company Professor in Nuclear Engineering and Materials Science and Engineering, the MIT team has introduced a partially disordered rock salt cathode integrated with polyanions, called disordered rock salt-polyanionic spinel (DRXPS). This innovation delivers superior energy density at high voltages while significantly enhancing cycling stability—a crucial factor in battery performance.

“This new material combines the best properties of rock salt and polyanionic olivine cathodes, pushing the boundaries of energy density and cycling stability,” explained Yimeng Huang, a postdoctoral researcher at MIT and lead author of the study published in Nature Energy.

Leveraging Earth-Abundant Manganese

A key advantage of this new cathode material is its composition, which primarily includes manganese, a widely available and much cheaper element compared to the nickel and cobalt commonly used in current battery technologies. “Manganese is not only abundant but also essential for achieving higher energy densities,” said Li. "It's about five times less expensive than nickel and thirty times cheaper than cobalt."

This cost efficiency is particularly crucial as the world transitions towards a low-carbon future. Batteries are essential for decarbonizing transportation through electric vehicles and managing the intermittent nature of renewable energy sources like wind and solar. Scaling up energy storage without relying on expensive, scarce materials is vital to avoid cost spikes and material shortages.

Addressing Challenges in Battery Design

One of the primary challenges with disordered rock salt cathodes has been oxygen mobility, which, while contributing to high capacity, also leads to instability over prolonged use. Traditional cathodes offer capacities of 190 to 200 milliampere-hours per gram, whereas disordered rock salt can reach up to 350 milliampere-hours per gram. However, this high capacity often comes at the cost of stability, as the oxygen's mobility can lead to material degradation.

To combat this, Huang introduced phosphorus into the cathode's structure, forming strong bonds with oxygen and preventing degradation. "By adding phosphorus, we can stabilize the oxygen, maintaining both high capacity and stability," Li explained.

The ability to charge these batteries to higher voltages is another significant benefit, as it simplifies the overall battery management system. "Higher voltage per cell means fewer cells need to be connected in series, making the battery system more efficient and easier to manage," added Li.

This pioneering work at MIT marks a significant step towards creating more scalable and reliable battery technologies, bringing us closer to a future where affordable, high-energy storage is accessible for all.