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 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 third-party 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 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.Continue reading »