equipment to make batteries: 1) to mix chemical anode and cathode slurries, 2) to coat them onto metal foil current collectors, 3) to “calender” (flatten) the surface, 4) to slit the coated metal foil into electrode sheets and 5) to roll them up for packaging in cylindrical metal cans. While there have been process improvements over the years, electrodes for conventional
Li-ion
batteries are still fabricated using this standard method developed almost 30 years ago.
Li-ion
cells were initially assembled by winding electrodes and separators into a naturally cylindrical Jelly Roll configuration, packaged in a cylindrical metal can. While some
Li-ion
batteries still use cylindrical metal cans,
low-profile
portable electronic devices require thinner, flatter cell formats, like the flat Jelly Roll shown earlier.
Li-ion
cell assembly first addressed this need with a
process introduced in the early 1990s. Today, it is common to wind the Jelly Roll onto a flat–rather than round–metal form. In 1995,
cell assembly improved spatial efficiency, but it is slow, expensive and imprecise. We have developed a more precise
cell assembly process to enable a silicon anode that increases
Li-ion
cell energy density and maintains high cycle life.
cell assembly, introduced in the early 1990s, essentially flattens the cylindrical Jelly Roll into a thin, flat package for use in portable electronic devices such as laptop computers and mobile phones. The
electrode assembly can be packaged in a metal case, but it is most often packaged in a polymer pouch for portable electronic device applications. It can also be produced in larger formats, with welded aluminum housings for electric powertrains in EVs.
cell assembly was introduced in 1995. Instead of winding and flattening, electrodes and separators are cut (or punched) into sheets, which are stacked horizontally.
assembly provides better spatial efficiency than Jelly Roll
assembly because the volume lost from core is eliminated and space at the outside edges is reduced.
cells are used in consumer, military and EV applications.
We have designed proprietary tools, produced for us by precision automated equipment suppliers, which incorporate patented methods and processes to achieve precise laser patterning and high-speed
cell assembly. These tools are
“drop-in”
replacements for either the
tools or the
tools in standard
Li-ion
production processes.
Our precision
assembly has been designed to be a more precise, faster and less expensive version of standard
cell assembly. Instead of cutting or punching, electrodes and separators are laser patterned and stacked into 3D cell architecture. An
in-line
laser precisely patterns the electrodes and separators, which are then fed directly to a high-speed stacking tool. The laser patterning and high-speed stacking of electrodes and separators in our patented 3D cell architecture provides more precise and automatic layer alignment and better spatial efficiency than conventional
cell assembly that typically require slow, optical alignment of each layer.
Battery Packaging and Formation —
Our 3D Silicon
™
Lithium-ion
battery uses the same battery packaging and formation process as a conventional
Li-ion
battery–with one exception. The first cycle formation efficiency of a graphite anode is about
90%-95%.
The first cycle formation efficiency of a silicon anode is only about 50% to 60%. The
pre-lithiation
process of the 3D Silicon
TM
Lithium-ion
battery overcomes the first-cycle formation efficiency issue, while preserving all the other benefits of silicon over graphite for anodes.
The first technology node we will bring to market is called
EX-1,
which makes batteries sized for wearables and mobile communications devices with energy densities well above current market standards. As seen below, we have sampled a prototype version of
EX-1,
named
EX-0.9,
at energy densities just below the targeted spec of 722 Wh/l for wearables and 900 Wh/l for mobile communications devices. We believe this gap will be closed