Automotive Engineering - December 2022 - BET4

Silicon Anodes
enable silicon anode performance gains.
Tesla and Porsche currently have EV
batteries leveraging some degree of silicon-anode
technology, which helps to
explain both brands' leadership in certain
battery-performance qualities.
In a release announcing the joint-research
collaboration, GM reiterated that it
designed its Ultium battery platform for
flexibility, " so we can continuously improve
our cells as battery technology advances, "
said Kent Helfrich, GM's Chief Technology
Officer, VP of GM research and development,
and President of GM Ventures. The research,
the two companies said, will focus on
OneD's Sinanode platform, a novel process
for blending silicon onto the anode battery
cells by fusing silicon nanowires into the
" EV-grade " graphite already being supplied
to all major battery manufacturers.
Critically, said OneD CEO and CoFounder
Vincent Pluvinage in an interview
with SAE Media, one of Sinanode's
prime attractions is its ability to be efficiently
and cost-effectively incorporated
into today's established EV battery
graphite production process.
Advancing the Basics
Although graphite (carbon) has served
as the industry's stalwart anode material
during Li-ion batteries' early volume-production
phases, OneD and its
competitors know that silicon's unique
properties can greatly enhance the performance
of batteries with graphite-only
anodes. The challenge is how to incorporate
silicon with graphite to derive
the most performance benefit - and do
it within the constraints of a constantly
pressured cost structure that virtually
NANOWIRES INFUSE
THE SURFACE OF EACH
GRAPHITE PARTICLE
100 nm 0 n
H
very little. It's less than $2 per kilowatt-hour
variable cost. But you use far
less graphite. So, if you use two-thirds
less graphite, you end up with a total
[anode] cost that may be around $3 per
kilowatt-hour instead of $6.50 per kilowatt-hour, "
he added.
Sinanode is compatible with natural
and artificial graphite, Pluvinage said.
3µm
SINANODE ON
EV-GRADE
GRAPHITE POWER
NANOWIRES GROW
INSIDE EACH PORE
" We can work with suppliers of natural
graphite and suppliers
of
synthetic
OneD's silicon nanotubes enable highly efficient
Lithium-ion transfer but mitigate the
propensity of silicon to expand with rising
temperature. (Image: OneD)
demands battery prices are markedly
reduced if EVs are to sell in high volumes
in almost every world region.
OneD's Pluvinage insists that incorporating
the silicon-graphite matrix
material that is central to the company's
Sinanode platform and process will
reduce cost compared to a conventional
graphite-only anode because OneD's
less-expensive silicon nanowires displace
a considerable amount of the
costlier graphite. Reduced overall material
cost
and OneD's capital-friendly
Sinanode process are the company's
compelling advantages, Pluvinage said.
" If you take graphite today - if you
use artificial graphite - it costs about $8
per kilogram, which means that it costs
about $6.50 per [battery] kilowatt hour.
If you put the nanowires in it, the cost of
putting in the nanowires - the nanowires
can store a lot more in energy - is
graphite. We can process their graphite
so that the little silicon hairs are inside
the core of those commercial graphites.
And that's very good, because we don't
spend a penny making the substrate. It is
already in production and already qualified
with EV cell factories. "
The anode material-cost savings,
multiplied by the 75 kWh to 100 kWh
battery pack typical of most current EVs,
amounts to significant cost reduction,
Pluvinage said.
And crucially,
the
Sinanode process of getting the silicone
nanowires blended with graphite
and then into the battery cells also is
claimed to be a low-impact investment.
Pluvinage said to go from the current
projected pilot-manufacturing of
Sinanode-enhanced battery packs to
much higher volumes.
According to him, OneD plans to collaborate
with GM on a pilot-production
phase " that allows us to process large
enough quantities of the material so that
our customers can make 5,000 or 10,000
battery packs. And that's necessary. Once
you have optimized EV cell, you need to
make that many battery packs to do all
the safety qualifications, pre-production.
And so that takes a couple of years. "
SIH4
EV-GRADE GRAPHITE
COMMERCIAL SILANE GAS
CVD PROCESSING
SYSTEM
OneD's Sinanode process is claimed to be a comparatively inexpensive method for creating silicon-infused graphite material ready for use in
conventional battery-cell manufacturing processes. (Image: OneD)
4
Battery & Electrification Technology, December 2022
SILICON-ENHANCED EV GRAPHITE
EV ELECTRODE COATING

Automotive Engineering - December 2022

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