24M announced Eternalyte, a new electrolyte developed specifically for lithium-metal batteries. The proprietary, liquid electrolyte formula will enable significant improvements in the cycle life and rate capability of lithium-metal batteries for electric vehicle, energy storage and consumer applications, the company said.

This new innovation builds on recent technology breakthroughs from 24M including 24M ETOP, its electrode-to-pack battery technology (earlier post), and 24M Impervio, its new battery separator (earlier post).

Until now, solid-state electrolyte (SSE) technology has been the preferred choice for those trying to commercialize lithium-metal batteries, which have long offered the promise of significantly higher energy densities. However, safety concerns and short and inconsistent cycle life, caused by lithium or other metal dendrites, continue to limit the commercial viability of lithium-metal cells, including those using SSE-based technologies.

Challenges with SSE’s scalability, cost, fragility, and changes in electrical resistance with cycling are additional issues that need to be solved. 24M’s liquid electrolyte Eternalyte, combined with Impervio, solves these challenges, the company said.

The combination is a low-cost way to prevent all metal dendrites and achieve excellent cycle life with consistent and low electrical resistance to cathode active materials. Historically, liquid electrolytes used with lithium-metal anodes had poor cycle life, particularly, with rapid charging. Eternalyte, however, has demonstrated outstanding cycle life even under rapid charging conditions, paving the way for new lithium-metal solutions.

We are on a mission to deliver transformative battery solutions that overcome critical industry challenges. Eternalyte plays a key role in making that transformation happen by enabling high cycle life lithium-metal batteries. While our solutions can be individually integrated into conventional battery products, we believe the most significant benefits are achieved when they are combined. Together, they can deliver a cost-effective and safe 1,000-mile-per-charge battery pack — enabling electric vehicles to be fully competitive with combustion engine vehicles.

—Naoki Ota, 24M President and CEO

Early test results show that Eternalyte enables substantial improvements in cycle life and rate capability for lithium-metal batteries.

• Unmatched cycle stability: For a lithium-metal cell cycling at 1C discharge/1C charge, 24M Eternalyte allows the cell to retain 83% capacity over 500+ cycles, approximately 500,000+ miles of total range and 1,000 miles per charge.

• Significant rate improvements: Test results for lithium-lithium base cells suggested an equivalent of 3,000+ cycles with 4C continuous cycling without shorting or increasing resistance.

24M believes that Eternalyte has achieved the highest cycle stability among liquid electrolyte systems under 20mA/cm² plating/stripping current.

When combined the 24M suite of battery technologies fully addresses current lithium-metal challenges—safety, cycle life and rate capability—and enables a more efficient and lower-cost next-gen battery.

• 24M ETOP increases battery pack energy density by eliminating the cell and integrating electrodes directly into the pack.

• The Impervio separator technology prevents and suppresses dendrite growth for safer lithium-ion and lithium-metal batteries.

Together, 24M ETOP, Impervio and Eternalyte enable improved safety, cycle life and energy density to deliver a 1,000-mile battery pack powered by lithium-metal.

The 24M technology portfolio provides flexibility for cell manufacturers using conventional processes by enabling them to integrate individual technologies into their current manufacturing processes. While the benefits are not as pronounced, this can allow manufacturers to improve overall performance.

For conventional cell production, the fundamental manufacturing process hasn’t changed in more than three decades. We’ve reinvented both the manufacturing process and cell/pack design to create a complete suite of innovative battery solutions that make next-generation technologies, like lithium-metal possible.

—24M Chief Scientist and MIT Professor Yet-Ming Chiang