LeydenJar Technologies BV, a spin-out from Dutch energy research center ECN, has produced a pouch-cell prototype Li-ion cell using the pure silicon anode technology developed at ECN. ECN says that its technology can increase the storage capacity of rechargeable Li-ion batteries by 50%; LeydenJar was incorporated to bring the technology to the market.
The nanostructured silicon anode features a silicon pillar porous structure enabling mechanical stability. The prototype cell has achieved 100 cycles at a constant capacity of 1.000 mAh/g. LeydenJar has also developed Li-ion coin cells that cycle at high capacities (between 1.000 – 2.000 mAh/g) with 400+ (on going) cycles.
Silicon offer a theoretical ten-fold increase in energy densitiy over conventioanl graphite anodes; accordingly, a great deal of research is focused on how to developing commercially viable solutions. A major limiting factor, however, is that silicon expands some 300% in lithiation. The expansion and contraction leads to a brittled and useless anode material. A number of high tech ventures and some corporations have developed methods to include incremental silicon nanoparticles in composite structures, which can be included in a similar coating process as for graphite anodes.
LeydenJar Technologies is unique in using 100% silicon anodes, leading to superior anode capacity, created via depositioning directly on copper foil in one machine.
The advantage of pure silicon anode technology is that it can have a significant impact on the energy density of current-chemistry Lithium-ion batteries, while replacing only the graphite anode with a pure silicon version.
ECN invented the technology using a roll-to-roll plasma-enhanced chemical vapor deposition (PECVD) machine that has the potential to scale up to mass production. Alterations to the PECVD machine enable the control of the the morphology and porosity of nanostructured silicon pillars, directly on a copper foil—used as the anode current collector in the battery industry.
This approach differs from the traditional coating process of anodes, which requires a mixture of active material, binder, and other components in a capital intense process of slurry making, coating, baking, calendering and slitting. LeydenJar Technologies says that its competitors are primarily focused on adding silicon nanoparticles to the slurry, creating more complex chemistries and incremental capacity improvements, applied to the same coating process (“drop-in technology”).
LeydenJar Technologies will now develop the technology in two tracks: first as a pouch cell prototype with a targeted energy density of 1.200 Wh/l or 480 Wh/kg, and then as a faster PECVD tool to demonstrate semi-commercial production rates.
Paul Wyers, director of solar research at ECN observed that tremendous effort is put into research worldwide to improve lithium-ion batteries, and a “breakthrough” is claimed every few weeks.
These discoveries usually concern materials that can only be produced in a laboratory environment on a very small scale. What makes our invention so promising is that the technology for mass production of this material is already within reach due to its similarity to an existing production process for solar cells. We believe that this gives us a unique advantage. Through the founding of LeydenJar Technologies, we will transfer this technology to the market and create a fit between the battery industry and venture capital investors.—Paul Wyers
The pure silicon anode technology is increasingly being recognised by established industry players as a promising technology. Recently, LeydenJar won the BMW Startup Garage competition that was organized by BMW Group Nederland in partnership with the BMW Startup Garage in München. Other multinationals have started to test the pure silicon anodes in their R&D laboratories.