24M Technologies, a battery company spun out of A123 Systems in 2010, has finally emerged from a long stealth mode. While 24M presented its technology as a "semi-solid lithium rechargeable flow battery" in its early days, it is now working hard to dispel the association with flow batteries, instead positioning itself as a disruptor to the entrenched lithium-ion (Li-ion) cell design and manufacturing process. Lux Research spoke with founders Throop Wilder, CEO, and Yet-Ming Chiang, Chief Scientist, about the new technology and its potential impact on the Li-ion industry.
Standard Li-ion cells contain films of solid electrode materials in contact with liquid electrolytes. 24M's patented innovation replaces these films with semi-solid electrodes made of Li-ion cathode and anode materials suspended in conventional liquid electrolytes. The company claims this design is easier and cheaper to manufacture. Its pouch cell prototypes with lithium iron phosphate (LFP) cathodes and graphite anodes have reached 221 Wh per kg and 300 Wh per Liter. The company projects at least 3,000 cycles to 80% of initial capacity at C/4 and 100% depth of discharge, and a 20-year lifetime. 24M has received US$50 million thus far to develop the technology and establish its manufacturing facility in Cambridge, MA, and plans to raise an additional US$20 million to US$25 million from strategic partners in an upcoming Series C funding round for further development and manufacturing expansion.
Yet-Ming explained that 24M's battery design originated from a desire for "a more efficient Li-ion cell design with a more streamlined manufacturing approach". The company's design uses a traditional Li-ion chemistry while eliminating much of the complexity of traditional electrode creation, which includes mixing, coating, cleaning, pressing, and drying steps for each electrode. Yet-Ming said conventional electrode preparation is time-consuming, and also has a substantial footprint in terms of plant size and specialized equipment; up to 40% of land use in his estimation.
In contrast, 24M's slurry-like electrodes require only a one-step blending process, reducing the amount of equipment needed. Furthermore, he said the design allows 24M to eliminate many inactive materials and binders from the electrodes. In total, 24M estimates a 50% cost saving over conventional Li-ion via lower capital expenditures and a reduced bill of materials, targeting a cost of less than $100/kWh by 2020 at a GWh-scale of production. Yet-Ming said that while traditional Li-ion plants require a capacity of hundreds of megawatt hours and corresponding investment of hundreds of millions of dollars to be economically viable, 24M estimates that it can achieve similar economies of scale in manufacturing with an 85MWh facility costing US$11.5 million.
Yet-Ming Chiang of 24M claims lithium batteries are a "brilliant, enabling technology" that suffers presently from "flawed economics". Image: 24M facebook page.
The company will position itself as a cell supplier to stationary systems integrators for longer duration applications (around four hours). It is already working with four undisclosed companies for projects including demand charge management and transmission and distribution (T&D) deferral. Yet-Ming said that while the gravimetric and volumetric energy densities of the cells are adequate for automotive applications, the company will not attempt to supply the automotive market on its own. He said that, himself included, many members of 24M's team know from first-hand experience at companies such as A123 Systems and Ener1 that tackling the automotive industry as a start-up is immensely challenging. He said that 24M does have active electric vehicle programs in place today, but will look for a partner – perhaps an OEM or a tier-one supplier – if it were to enter the market sometime down the road.
Regardless of which applications it chooses to target, 24M must first demonstrate that the performance of its cells is reproducible in practice and at scale. In particular, it must substantiate its extrapolated cycle life of more than 3,000 cycles with real testing data, currently available only to 700 cycles.
…24M has proposed an intriguing approach that is infrequently addressed in the discussion surrounding Li-ion cost reduction: revamping design and manufacturing processes…"
Overall, we think 24M has proposed an intriguing approach that is infrequently addressed in the discussion surrounding Li-ion cost reduction: revamping design and manufacturing processes (see the Lux Research report "Crossing the line: Li-ion battery cost reduction and its effect on vehicles and stationary storage"). Developers of solid-state batteries such as Sakti3 and novel aqueous battery chemistries such as Aquion Energy have claimed their manufacturing techniques reduce their costs relative to Li-ion. Although players such as the Palo Alto Research Center have developed incremental process improvements, there have been few, if any, design and manufacturing innovations within Li-ion chemistries that have promised to bring the cost reductions 24M is targeting.
If its manufacturing process is truly scalable at low costs and the performance of its cells lives up to its claims, 24M's technology is potentially disruptive.
Potential customers should keep an eye on 24M's entrance onto the scene, as its scale-up could have an impact on many levels of the existing Li-ion value chain, from raw materials to components to manufacturing equipment. Its manufacturing model could create new opportunities for suppliers of suspension-processing equipment common in the food industry, for example. While 24M won't take away significant market share from incumbent Li-ion designs before 2020, its success could eventually limit growth prospects for existing electrode coating equipment, as well as binders and other inactive battery materials.
Those who are interested in exploring Li-ion manufacturing without stratospheric capital investments should inquire and carefully evaluate 24M's claims before engaging.
If its manufacturing process is truly scalable at low costs and the performance of its cells lives up to its claims, 24M's technology is potentially disruptive."
Enjoy 12 months of exclusive analysis
- Regular insight and analysis of the industry’s biggest developments
- In-depth interviews with the industry’s leading figures
- Annual digital subscription to the PV Tech Power journal
- Discounts on Solar Media’s portfolio of events, in-person and virtual