The next great advancement in battery tech has come from semiconductor experts. A small cadre of chip experts, some working together since the ‘80s, made a hard left when they realized the battery, not the chip, would enable the most important technological advancements of the 21st century.
To gain an understanding, Digital Journal interviewed Ashok Lahiri, Co-Founder and CTO of Enovix.
Digital Journal: What are the limitations with the current generation of batteries?
Ashok Lahiri: Energy density improvements in Lithium-ion batteries have not kept pace with the needs of mobile electronics, which can limit their use and functionality. Technologies of the future—Artificial Intelligence (AI), Edge computing, 5G, Electric Vehicles (EV), Augmented Reality (AR) and Virtual Reality (VR)—all require a battery with high energy density.
DJ: What types of batteries are needed for future state technology?
Lahiri: Future technologies need very high energy density batteries and, in some applications, such as EVs, very fast charge times. But as energy density increases, safety should be at the forefront.
Battery designers have found that when they try to increase energy density, they may compromise safety, and vice versa. The Enovix 3D Silicon Li-ion cell architecture upends the conventional paradigm and enables both an increase in energy density and a high level of abuse tolerance to reduce the risks of an internal short leading to thermal runaway or fire.
DJ: What is the project you have been working on?
Lahiri: Enovix is currently shipping commercial batteries to some of the world’s largest consumer electronics companies. We continue to grow our global reach and have active engagements across Asia, including with leading smartphone OEMs in China and major consumer brands in Japan and Korea, including Samsung. We also have an agreement with the U.S. Army to build and test custom cells for use within U.S. Army soldiers’ central power source.
DJ: What have been the main technological challenges?
Lahiri: The battery industry was entrenched in decades of experience building batteries essentially one way, innovating incrementally with better materials and chemistries. To break out of this paradigm, someone was going to have to do something very different, and it wouldn’t be easy. We felt our background in 3D semiconductor architectures could be such a game changer. However, we acknowledged that even with our decades of combined experience and expertise, designing, assembling and producing an entirely new Li-ion battery would be very challenging. Our passion for solving tough problems and a collective belief that the world desperately needed a better battery helped drive us to develop and produce the next generation Li-ion battery.
Historically, advancements in battery performance have come primarily from improvements in the active cathode and anode materials of the battery. While other companies focus on incrementally improving batteries through new chemistries, we’ve completely reimagined the battery architecture—throwing out the more than 100-year-old “jelly roll,” where long strips of anode, separator and cathode are wound together in a jelly roll form, and replaced it with a precise, laser cut design where short strips of anodes, separators and cathodes are stacked. This new design allows for more efficient use of the volume of the battery in contrast to the jelly roll, where significant volume is wasted at the corners and in gaps at the center of the battery given the lack of precision in the winding process.
Our novel 3D battery design improves the packing efficiency of the active material inside the battery, enables exceptional thermal performance and abuse tolerance, as well as accommodates the use of a 100%-active silicon anode. Silicon is a plentiful and sustainable ingredient that can theoretically store more than twice as many lithium ions as a graphite anode, which is used in most conventional Li-ion batteries today. The use of silicon within our battery architecture translates to a battery with high energy density in an efficient form factor
DJ: Challenges; how do you deal with safety?
Lahiri: In a commercial Li-ion cell produced for consumer electronics, external heat, overcharging, or an internal or external short circuit can lead to thermal runaway. There are many ways to reduce the risk of an internal short; the industry, however, has not been able to prevent all incidents.
The Enovix 3D cell architecture incorporates many features inside the cell to improve electrical, physical, and environmental abuse tolerance. These features reduce the potential of an internal short circuit. In the unlikely event that an internal short does occur, Enovix BrakeFlow™ technology adds an extra layer of protection to further reduce the risk of thermal runaway. With BrakeFlow incorporated, the battery is designed to discharge slowly and safely instead of a sudden catastrophic release of energy.
DJ: When will the batteries be available at a commercial scale?
Lahiri: We announced in June 2022 that we shipped our first commercial batteries from Fab-1 production line. Although we cannot predict our customers’ product release schedules, we announced in our Q3 2022 Shareholder Letter that we shipped production cells to 25 OEMs. Further, our Gen2 Autoline, which we view as the engine that will power our manufacturing scale-up in the future, is anticipated to be qualified first half of 2024 and ramping 2024.
DJ: What other innovations are you working on that you’re able to share?
Lahiri: We launched a new business unit to adapt our 3D battery architecture to the EV marketplace called Enovix Mobility. It’s early in our development but we’re pleased with the results so far with our EV test cells.
During the third quarter 2022, we continued to see excellent data in support of high cycle life and high calendar life – two attributes that have historically held back cells with silicon anodes. As part of our three-year Department of Energy grant program that is pairing a 100% active silicon anode with EV-class cathode materials, our test cells surpassed 1,500 cycles while retaining 88% of their capacity – well ahead of the Department of Energy’s program goal of 1,000 cycles with 80 percent capacity retention. Additionally, our test cells put to cycling under extreme temperatures have retained enough capacity for us to comfortably model over 10 years of calendar life, a key requirement for EVs.
In June 2022, we announced that we demonstrated the ability of our EV test cells (0.27 Ah cells) to charge from 0-80 percent state-of-charge in as little as 5.2 minutes and achieve a greater than 98 percent charge capacity in under 10 minutes.
