Automotive Engineering - November/December 2021 - 14

TECHNOLOGY REPORT
ELECTRIFICATION
3D graphene boosts new batteries beyond lithium-ion
Lyten is developing Li-S
battery technology for use in
various applications, including
automotive, aerospace,
defense, commercial vehicle
and off-highway markets.
Lyten, a Silicon Valley materials company,
aims to displace the incumbent
lithium-ion (Li-ion) cell chemistry from
mainstream electrified vehicle (EV) applications
using lithium-sulfur (Li-S)
technology. " Our current generation
materials perform at an almost 2.5X
rate over conventional Li-ion batteries, "
Dan Cook, Lyten's president and CEO,
told SAE Media.
The technology enabler is the San
Jose, California-based company's invention
of three-dimensional (3D) graphene
versus traditional two-dimensional
(2D) graphene, in which an allotrope
of carbon consisting of a single
layer of atoms is arranged in a flat, 2D
honeycomb lattice nanostructure.
" What we've done is create a carbon
scaffold to cage the sulfur within 'bars,' "
Cook explained. " We have a proprietary
way of putting the sulfur in between
the bars so that the sulfur will stay in
place. " The bars are small enough to
hold the sulfur, yet wide enough for the
Li-ion to enter and exit the scaffold
structure. Sulfur containment also
means that the chemical element
doesn't escape into the electrolyte,
which would destroy the battery.
Lyten's trademarked 3D Graphene is
a first-generation battery technology
14 November/December 2021
that Cook describes as " a leap-frog
technology " to today's Li-ion chemistry.
The firm has many patents relating to
the processes, tools, and material needed
to produce a Li-S battery. " By thirdparty
judgment, we have the largest 3D
graphene intellectual property portfolio
in the world, " Cook claimed.
The Li-S battery cells can be manufactured
in multiple formats: cylindrical,
pouch, or prismatic. Lyten intends to
produce the batteries in the U.S. using a
domestic supply chain. Unlike a Li-ion
battery in which the positive electrode
is typically a metal oxide via a layered
oxide (such as lithium cobalt oxide), or
a polyanion (such as lithium iron phosphate),
or a spinel (such as lithium manganese
oxide), Li-S is metal-oxide-free.
" The safety factor is compelling because
we don't have metal oxides, "
Cook noted. " Therefore, we don't have
oxygen to react with lithium metal during
thermal runaway, which can happen
when batteries overcharge. " Part of the
process for producing the Li-S battery
relies on methane gas. Carbon is captured
from the stream of methane and
a solid, nucleated material is created for
use in the battery, Cook said.
In-house lab testing has shown that
the Lyten's Li-S batteries' operating
Lyten's Dan Cook said the company has Li-S
batteries in development that from a gravimetric
energy density standpoint are outperforming the
theoretical limit of solid-state Li-ion batteries.
range is from -30º C to 60º C. " We've
demonstrated operation in this temperature
range with no warming or
cooling of the battery, and no loss in
performance, " said Gregory Deveson,
Lyten's president of automotive. Fast
charging time is less than 20 minutes
for an 80% charge. Current battery cycle
life is at 1000, he said, but the target
is 1800 cycles - which translates to
more than one million miles of driving.
Lyten executives are in discussion
with five global automakers, primarily
U.S. and European-based. At press time,
there were no signed contracts. " When
we get to production for an electric vehicle
application, it won't be with our
first-generation battery technology, "
Cook said. Targeted start of production
for Lyten's Li-S batteries is 2025-2026.
Kami Buchholz
AUTOMOTIVE ENGINEERING
BOTH IMAGES: LYTEN
Automotive Engineering - November/December 2021

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