Enovix, based in Fremont, California, announced that it demonstrated in electric vehicle (EV) battery cells the ability to charge from 0% to 80% state-of-charge in as little as 5.2 minutes and to achieve a greater than 98% charge capacity in under 10 minutes. The cells also surpassed 1,000 cycles while retaining 93% of their capacity.
The achievement shattered the United States Advanced Battery Consortium (USABC) goal of achieving 80% charge in 15 minutes.
Other goals for USABC at the cell level include a usable energy density of 550 Wh/L, a survival temperature range of -40 to +66 degrees C, and a cost of $75/kWh at an annual output volume of 250,000 units. A full set of USABC targets can be found here.
The company demonstrated the fast-charge ability in its 0.27 Ah EV cells in its silicon lithium-ion batteries, which it said contain a novel 3D architecture and constraint system. The cells contain a 100% active silicon anode. Enovix said the material has long been heralded as an important technology in the next generation of battery anodes.
Silicon anodes can theoretically store more than twice as much lithium than the graphite anode that is used in nearly all Li-ion batteries today (1800mAh/cubic centimeter vs. 800mAh/cubic centimeter).
“Fast charge capability can accelerate mass adoption of EVs and we’ve been able to demonstrate a level of performance that meets and exceeds many OEM roadmaps,” said Harrold Rust, co-founder, CEO and president of Enovix. “EV manufacturers are in pursuit of batteries that support longer range, while the public and private sectors work to increase EV driver access to fast chargers. We’re proud to support these goals to help electrify the automotive industry and demonstrate our batteries are an exciting option to power long-range, fast-charging EVs.”
Silicon’s high energy density, however, creates four significant technical problems that Enovix has addressed with its technology:
First Charge Expansion: The cells have a stainless-steel constraint system surrounding it that limits the battery from swelling. Enovix reorients the electrodes to face a small side of the battery to decrease the required constraining force.
First Charge Efficiency: The battery uses a “pre-lithiation” process during manufacturing to insert additional lithium source to top-off lithium trapped at formation. The batteries can do this practically because the additional lithium only needs to travel a short distance in the 3D architecture to permeate the anode.
Cycle Swelling: Enovix manages swelling as a result of cycling with its integrated constraint, limiting swelling to as little as <2% cell thickness after 500 cycles.
Cycle Life: The integrated constraint keeps particles under constant stack pressure, limiting particles from electrically disconnecting and cracking.
“Our unique architecture enables a battery that not only charges in less than 10 minutes, but also maintains high cycle life,” said Ashok Lahiri, co-founder and CTO of Enovix. “We can improve battery performance today using the same chemistries, but more importantly, we can accelerate the industry’s roadmap.”
Lahiri will speak at the 12th International Advanced Automotive Battery Conference (AABC) Europe in Mainz, Germany. His presentation at 11:20 a.m. CEST (5:00 a.m. EST) titled “Silicon-Anode Lithium-Ion Batteries for EV Applications,” will provide an update on the company’s EV program. The slide deck can be found here.
