Where are we at with Li metal?
part 2 of 2
Making lithium metal at scale and putting it into cells is the key to unlocking lots of the next generation battery technologies. Today Roman Healy is back with part 2 of 2 focused on the companies tackling these challenges; Blue Solutions, Pure Lithium, Skellium, Elevated Materials & Sigma Lithium.
Why don’t we have commercially available cells with lithium metal anodes yet?
As we saw in Part 1, the production of lithium metal is a long and complex route, and crucially air sensitive and difficult to transport. To use commercially in batteries, further material processing and engineering are needed to meet industrial demands and to overcome the practical challenges.
Practical challenges
Lithium metal anodes present several fundamental challenges that appear at lab scale. Finding solutions to these issues requires fundamental understanding of their mechanisms.
Dendrite formation. These tend to occur due to uneven lithium plating/stripping arising from local current density inhomogeneity and electrode-electrolyte interface instability.
Loss of active lithium. An initial loss of lithium is unavoidable due to SEI formation, which is why cells are typically designed with a slightly higher N/P ratio. Other lithium inventory losses can occur through non-uniform plating/stripping, which leads to electronically isolated “dead lithium,” as well as through unstable electrode–electrolyte interfaces or lithium consumption at the cathode side.
Stable SEI. It is a key element in any cell key to enabling long cycling and preventing lithium inventory loss and something we explored in more depth in a previous article.
Mechanical degradation and void formation. During plating/stripping, voids can be created, which increase interface resistance and lead to dead lithium. Void formation is particularly harmful in solid-state batteries because gaps cannot be refilled by the electrolyte.
Industrial needs
Lithium metal anodes have to meet several criteria to be competitive against graphite anodes in performance, safety and cost.
Thickness and uniformity. Commercial cathodes typically deliver areal capacities in the range of 3–4 mAh/cm², which is why conventional graphite anodes require thicknesses of 70–100 µm. If lithium metal is to be paired with such cathodes, the active anode thickness must be reduced to roughly 15–25 µm (that is 1/4 the width of a human hair) to avoid excessive inactive mass. Although this would significantly boost both gravimetric and volumetric energy density, manufacturing lithium at scale at these thicknesses is a big engineering challenge. In addition, thickness uniformity of the lithium foil must be controlled, as local thickness variations can lead to non-uniform current distribution and promote dendrite formation.
N/P ratio. Graphite-containing cells typically use N/P ratios (negative to positive) above 1 (i.e 1.05 - 1.15) to compensate for irreversible losses. However, for lithium metal anodes, the aim is to go as close as possible to near-zero excess or bet for anode-free configurations.
Coulombic efficiency (CE). It is a critical metric for lithium metal anodes. The absence of a host structure makes lithium losses irreversible, meaning that even small inefficiencies can accumulate and lead to severe capacity fading. To achieve long cycle life, lithium metal batteries must operate at CE values of at least 99.9%, preferably 99.95%.
Current density. Considering the specs mentioned before, current densities should be above or equal to 3 mA/cm² to allow fast charging and overpotentials should remain low to reduce inefficiencies.
Stack pressure. This requirement is mainly related to solid-state batteries. In these systems, external pressure is often necessary to maintain intimate contact at cathode and anode interface. To successfully implement them, low stack pressure cycling should be possible, to reduce technical challenges in pack design as well as improve safety. Typical values should be below 5 MPa and 2 MPa for EVs.
Who is solving which problem?
Although many companies are working on integrating Li-metal anodes in cells, only a few are focusing on the metal itself and how to process it in order to meet the criteria mentioned. Hence, companies that source the metal from external providers will not be included.
To prepare Li metal foils, the main used routes are:
Extrusion + roll-to-roll, the most mature of all and comprises extruding lithium followed by thinning of the foil through rolling.
Molten lithium casting which involves heating lithium above its melting point and casting it onto a current collector.
Vapor deposition techniques include evaporating lithium in vacuum and condensing onto a substrate, ensuring very thin and uniform films.
Electrochemical deposition, where lithium is plated directly onto a current collector from an electrolyte containing lithium ions.
Blue Solutions
With over a decade of research in Li-metal polymer (LMP) batteries, it was founded in 2001 through its parent company Bolloré. Their bet on LMPs was based on the belief that this configuration offers increased safety and performance compared to other Li-ion configurations. Such a strong research background enabled mass production of LMPs in 2011 and to date they have powered over 600 million vehicle kilometers.
One of the differentiating aspects of Blue Solutions is that they manufacture Li-metal anodes and polymer electrolyte films as well as assemble batteries. Their Li-metal, produced via a proprietary roll-to-roll process advances are very promising as they moved from 60 micron Li foils for their Gen 3 batteries to below 20 microns for their Gen 4 batteries.
Pure Lithium
Based in Chicago, Emilie Bodoin and Prof. Donald Sadoway founded Pure Lithium in 2020 with the objective of vertically integrating the supply chain of Li-metal anodes, hence the name of their technology Brine-to-Battery.
Their core technology aims to obtain Li metal by electrochemical deposition while bypassing the use of Li-containing salts. The process begins with lithium brines, where Li+ are selectively isolated from other ions and water using a membrane. Once done, Li+ can be electrodeposited safely onto a substrate. It is essential to remove water before electrodeposition, because were it to be present, hydrogen gas would be generated first instead of lithium metal.
Performance has been demonstrated with Gen 1 and 2. The second, paired with a vanadium-containing cathode, achieved an energy density of 425 Wh/kg over 1,000 cycles at a 1C rate.
Skellium
Founded last year, this start-up is a spin-off from RWTH Aachen PEM Institute. They aim for scaling ultra-thin Li-metal production by using a coating process that was developed during the “LIMA” project.
Contrary to the other companies, they use a molten lithium process to coat Li-metal onto a copper current collector. This removes the need of vacuum, but requires higher temperatures to melt lithium. More notably, they state that a 3D skeleton aids in dendrite prevention hinting at a porous copper scaffold.
Elevated Materials
A spin-out from the semiconductor company Applied Materials, it was founded to commercialize and scale the production of ultra-thin Li metal foils produced through vapor deposition. Submicron thicknesses up to 20 microns are available with the lowest intended to be used for pre-lithiation.
I had the pleasure to interview Dean Frankel, Vice President of Product Marketing:
What are the major engineering challenges when producing ultra-thin Li metal at scale?
Historically, lithium metal has been produced through rolling processes. While this works for thicker foils, it becomes increasingly difficult to maintain tight thickness control and smooth surfaces as the material gets thinner. With rolled lithium metal foils, it is possible to produce relatively narrow (~150 mm) and relatively thin (~20 micron) material, but costs rise significantly as thickness decreases. The mechanical nature of rolling can also introduce defects, thickness variation, and handling challenges that ultimately affect electrochemical performance and manufacturing yield.
Lithium is also highly reactive with oxygen, moisture, and contaminants, so surface quality and contamination control are essential. Small surface defects or parasitic reactions can have a disproportionate impact on battery performance, particularly at very low lithium loadings.
Advanced manufacturing approaches such as roll-to-roll vapor deposition offer a different path forward. By depositing lithium as a thin film, it becomes possible to produce very uniform, smooth layers with precise thickness control across large areas. These methods are also not constrained by the same mechanical limitations as rolled foils, which creates the opportunity to produce ultra-wide lithium films. Today, we produce films approximately 700 mm wide, which is important for achieving the throughput and cost structure needed at gigawatt-hour scale.
Another benefit is material efficiency. Ultra-thin deposited films reduce the total amount of lithium required while still delivering the performance advantages associated with lithium metal anodes.
What are the main difficulties shipping Li metal from both product stability and regulatory perspectives?
Lithium metal is regulated as UN 1415 – Lithium, Hazard Class 4.3, meaning it is classified as a water-reactive material for transport. From a practical standpoint, this means lithium metal requires appropriate dangerous goods packaging, documentation, and handling. When shipped by air, it is generally restricted to cargo aircraft under applicable transport rules.
That said, we do not view shipping as an insurmountable barrier. When sealed properly, lithium metal films can have a shelf life of more than six months, and in some cases customers have used material beyond the recommended shelf life without adverse results. With the right packaging design and modest shipping volumes, the impact on cost and safety can be managed effectively.
Do you see Li metal anodes being produced centrally and shipped to customers, or manufactured onsite with cell production?
Today Elevated Materials supports more than 35 customers a year out of our facilities in Alzenau, Germany and Sunnyvale, California. This model makes sense as customers are doing both R&D and piloting lithium metal films for various applications (lithium metal batteries as well as prelithiation). We see localized production as an important step toward lowering cost and delivering GWh-scale films to a single customer. Elevated Materials has plans to produce up to 3 GWh per year at our facility in Alzenau, Germany. However, once a single customer begins consuming more than roughly 1–3 GWh per year, it becomes logical to consider localized production, typically adjacent to that customer’s gigafactory.
Elevated Materials shipped more than 100 km of material to a single customer last year. While that is not yet gigawatt-hour-scale volume, it represents a meaningful qualification volume and an important step toward full product qualification and in turn, Gigascale production.
Sigma Lithium Ltd
This UK company based in Oxford was founded in 2015 by a team of professionals with 25+ years of experience in Li battery development. Their objective is to expand their proprietary technology 3D-Li produced via low vacuum deposition by licensing it to other OEMs, enabling a broader industry use.
I had the pleasure to speak to the founder, Dr. Gleb Ivanov to get more insights into their product and these are some of the topics we discussed.
What is 3D-Li and how is it processed?
3D-Li is a Li-metal anode that uses a non-woven carbon scaffold where lithium is deposited through a dry and low-vacuum process. Gleb stressed: “using low vacuum is very important as it requires reduced pumping times, however, low vacuum makes it more challenging to fully remove moisture or oxygen”.
What are the key benefits of 3D-Li?
Owing to the 10-fold increase in surface area, it reduces current density and enables fast charging without dendrite formation. Also, having a metallised scaffold removes the need of a current collector, hence reducing the overall weight of the cell. Although these are great pros, Gleb emphasized one above others: “owing to the high aspect ratio of the carbon fibers, volume change is drastically reduced to around 2%”.
What are some of the recent milestones and which are the plans for the coming years?
The anode is being validated by several OEMs and labs in different European countries and so far it has been successfully tested with NMC, LFP, high voltage cathodes and electrolytes. Recently they had set a target of achieving 50 cycles with high power and energy, which was exceeded and reached 250 cycles.
The upcoming milestones include upgrading the current Gen 3 technology to Gen 3+, and ultimately reaching Gen 4. These final development stages are being carried out in collaboration with companies in the UK and Belgium. It should be noted that Gen 4 will represent the final upgrade and will serve as the platform for future licensing.
Final thoughts
Ashley Cooke once posted: “I once tried to bring lithium-sulfur batteries to the world, and didn’t succeed. Here’s how I’d approach it now, starting by turning the problem upside down”, meaning starting with solving Li-metal rather than the cathode. Having such a diverse landscape of companies aiming to solve the fundamental challenges of Li-metal at scale brings hope that soon technologies like solid-state, Li-sulfur or batteries of higher volumetric and energy densities will be a reality.
Having material suppliers already demonstrating shipment of ultra-thin foils or cell developers integrating them into cells proves that Li-metal batteries are no longer a concept. More importantly, the ambitions of companies to vertically integrate Li-metal production and cell development within the same umbrella ensures a future with less geopolitical strain.
Overall, there is still a long way to go and the main obstacle is scaling the production and shipment of ultra-thin Li-metal while ensuring high-volume cell manufacturing. With the interest of expanding battery performance limits, the demand on Li-metal anodes keeps increasing, making the future of Li-metal batteries appear promising.
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