By Kyle Proffitt
May 9, 2025 | One theme that emerged from the 42nd International Battery Seminar and Exhibit was that silicon anode technology is maturing fast. In the plenary keynotes, Jeff Dahn spoke on silicon-carbon anode materials; Shirley Meng said silicon is actively coming to the market. Amprius took home a Best of Show award for high-energy cylindrical cells. Coreshell, Nanograf, LeydenJar, GDI, Blue Current, Paraclete, Sionic, Enovix, and Anthro all presented advances pushing this anode technology forward.
Silicon has great promise as an anode material in lithium-ion batteries, where it could replace graphite and provide 10-fold increased energy storage for the same weight, using an abundant resource. However, the associated swelling has limited its use in batteries, and cycle life can be limited. Common solutions involve the growth of specialized silicon architecture, protection with polymers or other material, and the use of composite blends such as Si-C.
The Case for Silicon
Roger Basu, CTO of Coreshell, framed the importance of silicon anodes in terms of cost, pointing out that most EVs in the US exceed $40k, whereas most vehicles sales are in the $25-30k range. Electrification of transportation through battery electric vehicles is the fastest path for taking the biggest chunk out of emissions, he said, but cost is an obstacle, and batteries are largely responsible. The goal for Coreshell is to get this cost down using metallurgical silicon, which Basu says is half the cost and ten times the specific capacity of graphite.
To elaborate on his position, Basu provided a hypothetical scenario in which we electrify 10% of the U.S. vehicle fleet per year—an aggressive target, he says. At 70 kWh of batteries per vehicle, we need a little more than 2 TWh of battery production per year for these EVs. For graphite to shoulder this increase, “the scale of domestic production needs to increase by 10x to meet this demand,” he said, and added that most would need to be synthetic (2-3x cost) because very little natural graphite exists in North America. His calculations said lithium metal production would need to increase 200x to support its use as anode. “In our view, the only way that lithium metal batteries will be viable for mass-market EVs is by going anodeless, or in other words, having zero excess lithium at the anode,” he said.
In contrast, he said silicon is the only anode material with domestic production already exceeding demand and added that if SiO or silane is used, these materials would also require 200x increased production. Thus, Coreshell uses metallurgical silicon, which Basu says is minimally purified from 98% to about 99.9% through their partner, Ferroglobe, at “very, very little cost—a dollar per kg, in that realm.”
The key of Coreshell’s technology is a proprietary coating that they apply to the metallurgical silicon, which Basu stressed is only milled to micron scale, saying that further milling to nanoscale becomes cost prohibitive.
Coreshell currently targets an 80% silicon anode material with 10% graphite, and they aim to eliminate graphite by end of decade. They are pairing their anode primarily with LFP, because it delivers the lowest cost per kWh and improved domestic supply security compared with NMC. An independent cost analysis by Roland Berger estimated that cells made with this metallurgical silicon would be 17% cheaper than graphite-LFP prismatic automotive cells and 25% cheaper than graphite-NMC 4680 cells.
Coreshell intends to deliver sample 60 Ah silicon-LFP cells this year that will achieve about 250 Wh/kg—to Basu’s knowledge the highest energy density LFP worldwide. He showed cycling data with 5 Ah cells, retaining 92.4% original capacity after 470 cycles (symmetric C/2 charge/discharge) under less than 20 PSI created by 2 pieces of compressible foam.
GDI is also using pure silicon in their anode, but their technology involves depositing a continuous layer of porous, amorphous silicon using plasma-enhanced chemical vapor deposition (PECVD) on high tensile strength copper foil. CEO Robert Anstey said this produces a silicon layer of about 15 microns, and that “in 15 microns you can hit 7 mAh/cm2,” an energy density he says would require 35 microns of Li metal and couldn’t be reached even with 100 microns of graphite. Their technology for deposition was developed by Asahi Glass Company, a manufacturer that operates on skyscraper scale for coating architectural glass. Anstey’s slides indicated that they have patent protection around this porous lithium storage layer containing at least 40% amorphous silicon.
Anstey said that their method works because, during formation, the silicon expands and “sort of forms its own city”, with “roads and throughways” of pores. Then when it shrinks, “it creates its own spaces that now, it can breathe.” He said their anode supports 10C charge and discharge, and complete cells have energy density exceeding 300 Wh/kg and 900 Wh/L, which was independently confirmed by 3rd party labs under no applied pressure.
Their initial applications include medtech and drones, which typically don’t allow full depth of discharge, a benefit that enables cycling about 500 times before dropping to 80% capacity. Anstey also showed data with a 5.5 Ah, >270 Wh/kg cell repeatedly charging at 4C and discharging at C/3 for 300 cycles, which in his example worked out to a hypothetical 500-mile EV. “This shows you can have high energy and do rapid fast charging in the same cell,” Anstey said.
GDI is renting space from AGC and setting up equipment inside their factory, intending to scale to 25-100 MWh by 2027 and aiming for 1 GWh by 2028-2029. Anstey says the technology allows them to get below $15/kWh for the anode material at GWh scale, and he cited REC Silicon as having sufficient excess silane for the production of more than 50 GWh of their anode material.
LeydenJar, based in the Netherlands, champions pure silicon anodes with a focus on consumer electronics—cell phones, laptops, and wearables. They envision these devices having increasing levels of onboard AI, requiring more power. Their primary product is a foil anode that is created to intentionally contain pores, enabling it to function like a sponge as it accepts lithium ions, thereby avoiding swelling. Senior Business Developer Tim Aanhane claims that in a 5 Ah cell format, their solution enables 50% increased volumetric energy density above the current market standards, reaching 900 Wh/L. He said they can increase energy density further with other modifications to reach 1250 Wh/L, and cycling 500 times was shown before capacity fell to 80%. No external pressure is used.
LeydenJar is using the same PECVD method as GDI to deposit silicon particles directly on copper foil. However, they are developing the PECVD equipment for manufacture themselves. “We have columns of silicon with a porosity in there; within those columns and between those columns, there’s spacing for the silicon to expand,” Aanhane explained.
It’s a dry process, with “no coating, calendaring, heating, or drying.” They currently have a 1 MWh pilot production line, with plans to scale to 1 GWh by 2029. Although their current focus is on consumer electronics, Aanhane says that as they push beyond GWh production, they will look at automotive applications.
Paraclete VP of corporate strategy, Paul Jones, discussed their newest SILO anode technology. He made bold claims about how their anode would be truly disruptive— doubling range, allowing much faster charging, and doing it at lower cost. “This product will deliver finally on the promise of silicon anodes in lithium ion batteries, and by doing that will reinvigorate consumer adoption of EVs,” Jones said.
Paraclete starts with any number of widely available silicon sources, including metallurgical grade. Jones said that they mill the silicon to a median size of about 150 nm and then protect it with a bilayer polymer matrix. He described the first layer as being very flexible but inelastic. The next, surrounding polymer is flexible, porous, and elastic, and the SEI forms on the outside of this layer. Jones explained that the silicon nanoparticles expand during charging, 300-400%, as expected. However, this expansion is effectively absorbed by the polymer layers, causing negligible impact on the SEI. He said this design allows them to use up to 80% silicon content and to achieve energy density “240% that of graphite and more than 150% our nearest silicon anode competitor.” A graphic showed this energy density at 520 Wh/kg. However, no cycling data were shown to support this value. CEO Jeff Norris spoke previously at Florida Battery, in 2023, and showed their batteries cycling 1,000 times to 80% capacity. A prior version of their anode was also used in a published Argonne study showing that it improved fast-charge (8C) capacity retention.
Jones claims that SILO anode-based LFP batteries would price at $35/kWh, beating LFP-graphite’s $53/kWh significantly. That would come with two and a half times the range of the LFP-graphite battery and allow a 7.5-minute charge, he added.
Blue Current is focused on solid-state batteries and minimizing or removing the need for pressure. Senior Manager of Battery R&D Priyanka Bhattacharya said they use “fully dry, proprietary elastic composite electrolyte materials” in the anode and pivoted fully to silicon in 2018. These materials “enable the silicon anode to be composed of very high weight percents of silicon, which is typically ten times more than what traditional liquid lithium-ion based cells today have,” she explained.
They’re pairing this anode with a composite polymer, sulfide-inorganic electrolyte separator, and NMC622 (and other higher nickel) cathode material with additional fully dry composite electrolyte.
Bhattacharya showed data with a small pouch cell projected to reach 1500 cycles before dropping to 80% capacity (C/5 charge/discharge, 2.5 MPa pressure). These cells could also charge at 2C and retain 93% of C/5 capacity. She says they are on track to achieve 1,000-cycle-to-80% capacity cells under 1 MPa of pressure, and their modeling analyses suggest this is an acceptable pressure level in EV packs provided the energy density exceeds 650 Wh/L. Their graphics indicate that the energy density is currently about 950 Wh/L in a projected 10 Ah cell, and they intend to push this further past 1000 Wh/L using thinner separators.
Amprius CTO Ionel Stefan explained that they have two main product lines, SiMaxx, which uses pure silicon nanowire anode; and SiCore, which uses SiO. SiMaxx are their highest energy density cells, with commercially available versions up to 1100 Wh/L or 450 Wh/kg and development versions pushing 1300 Wh/L and 500 Wh/kg. These cells typically have limited lifetimes of about 150 cycles, and the silicon nanowire technology requires some specialized manufacturing equipment. Amprius adapted equipment from the photovoltaic industry for this purpose, but Stefan says it still must interface with other battery manufacture equipment.
Stefan explained that to really take a new battery technology to market and succeed, it needs to be low cost, high throughput, and usable with existing equipment. Each part of the journey from lab scale to pilot scale to MWh scale to GWh scale takes a few years. “That’s why solid state was always 10 years ahead, and it probably still is,” he quipped.
For some of these reasons, the SiCore approach offers several advantages. Stefan said that this nanostructured SiO material is a “protected, stabilized material that can be used directly in a graphite mixture.” The idea is that this is a drop-in for existing gigafactory lines; “it doesn’t need any new equipment.” Compared to the SiMaxx cells, these tend to be a little lower energy density—the highest commercially available is 400 Wh/kg or 875 Wh/L—but the cycle life is improved. Stefan showed that at a reduced 90% depth of discharge, cycling over 1,000 times was achievable.
Additionally, SiCore is going into cylindrical 18650 and 21700 cells, which Stefan says are in high demand for micromobility applications. SiCore enables higher power and rate capability; a prototype was shown that enables “10C continuous discharge, 15C with cooling” and higher power pulses. Cycle life in that case drops to 2-300 cycles, but this is suitable for drone applications.
They’ve also developed 70+ Ah prototype SiCore cells that could be used in EVs, although they are designed primarily for supercar or electric vertical takeoff and landing (eVTOL) applications. Their full battery portfolio includes about 20 designs in a range of options tailored for higher power, higher energy, or balanced solutions, and their technologies are particularly suited for aerial applications, including drones, pseudosatellites, and eVTOLs.
More SiO and Si-C Offerings
Nanograf is using a “lithiated proprietary metal-doped silicon monoxide” (SiO) anode. VP of Business Development Tim Porcelli highlighted their m38 3.8Ah 18650 cells, which are optimized for low-temperature performance. They meet U.S. national security directives and are commercially available for purchase.
“Right now, we’re the only large-scale producer of battery-grade silicon monoxide in the United States,” Porcelli said. He pointed to their $60 million award from the Department of Energy, under the bipartisan infrastructure law, to build a $175 million scale facility in Flint, Mich. for 2,500 tons per year of our silicon anode.” They plan to open this facility by Q4 2027 and eventually ramp to 11.5 GWh of raw anode supply.
They got into this project based on military needs, providing a higher energy, longer runtime 18650 cell, and their product outperformed other incumbent batteries with “23% lighter packs and 8 hours more runtime for tactical radio applications.” The volumetric energy density of this cell is 790 Wh/L. Porcelli highlighted the low-temperature performance; their cells maintained 71% discharge capacity at -30 °C, whereas competitor cells fell to 25% at this temperature.
Their newest anode material is referred to as Onyx. Metallurgical silicon is used as raw input, and sublimation, lithiation, surface coating, and spray drying is performed to obtain battery-ready anode material. Porcelli contrasted this with Si-C materials that require several steps just to prepare silane gas before performing a high temperature chemical vapor deposition. He said their material is truly drop-in ready for existing gigafactories, and he said that at scale, the material can be “the same relative price per kWh as graphite.”
He reported 92% first-cycle efficiency with this material, and translated to EV applications, Porcelli’s slide showed the potential for about 30% increased range.
Sionic is using a protective conductive coating on Group14 silicon-carbon composite materials and creating batteries with optimized blends of advanced electrolytes, binders, and additives. CTO Karthik Ramaswami explained that “our business model is licensing; we don’t plan to make gigawatt-hour factories.”
He said they are cathode-agnostic and Si-C material agnostic, and their cells do not require pressure. Results were compared between cells using polyacrylic acid-based electrolyte and those using Sionic electrolyte; their electrolyte resulted in 2-3x increased cycle life (to about 1200), 12% increased energy density, and 33% increased fast-charge (6C) capacity. Ramaswami also showed data with a 10 Ah cell, which expanded 10% during formation, but then experienced a less than 2% expansion in subsequent cycles. Their current Gen3 design was shown with 1000 Wh/L and 370 Wh/kg at the cell level. Their enhancements also show increased power. With 10 and 20 Ah cells, “we can comfortably do a 15-minute or a 10-minute charge to 80 or 90%,” Ramaswami said.
Enovix VP of Customer Applications Engineering Jerry Hallmark presented a compelling case for needing higher energy products for the wave of incoming AI-enabled, power-hungry consumer electronic devices. Their technology uses a laser patterning to create 3d architecture using Si-C or SiO electrodes. They then stack on the order of 50-200 anode-cathode pairs, horizontally, and enclose this sideways mega-sandwich with a stainless steel constraint system above and below. Hallmark says their EX-2M batteries, in a smartphone format, provide 30% more energy density compared to lithium-ion||graphite cells, last 1,000 cycles, and withstand fast-charge protocols. In an augmented reality glasses design, the same cells are calculated to have a 57% higher energy density advantage. Those cell samples are available now, he says.
One more notable silicon-adjacent technology was presented by Anthro Energy CEO David Mackanic. Anthro has developed a liquid electrolyte that undergoes a phase change to polymerize during formation, “allowing you to impart many of the advantages of conventional solid-state batteries.” It’s designed to be cathode- and anode-agnostic, but a use case was highlighted with silicon anode technologies. A comparison was shown between 2.5 Ah NMC811||Gr+SiC (silicon dominant, 1000 mAh/g at the electrode level) cells, using either conventional liquid electrolyte or Anthro’s Proteus electrolyte. With liquid electrolyte the cells fell to 80% capacity after about 400 cycles, but, with no pressure applied, Anthro electrolyte cells retained 93% capacity at this point. Another data slide showed that the Anthro electrolyte reduced overall cell “breathing” swell by about half.
Mackinac explained that the electrolyte adheres layers together and forms an elastic binder network around silicon particles. The electrolyte is also non-flammable and quite flexible and should thus increase safety and allow unique form factors for specialized applications.
