Enovix, based in California is manufacturing Silicon-anode lithium-ion batteries. In their early experiment, they found that a silicon-anode lithium EV battery can be fully charged in about 10 minutes. The entire Ev industry can get benefit from it.
The energy density of a typical Li-ion battery can be greatly increased by adding a silicon anode. Researchers have known it for a long time but now private organizations have started experimenting with this theory. Silicon anodes have a storage capacity of around 1800 mAh/cubic centimeter, compared to about 800 mAh/cubic centimeter for graphite anodes.
Do you know what is 3D Silicon?
A silicon-anode lithium-ion battery known as 3D Silicon has been created by Enovix. The term indicates the cells’ 100% active silicon anode, a proprietary 3D architecture, and constraint mechanism.
In 0.27-Ah test cells, Enovix claims that its 3D Silicon lithium-ion batteries have shown the ability to charge from 0 to 80 percent state-of-charge in as little as 5.2 minutes and to reach a charge capacity of more than 98 percent in less than 10 minutes. Due to this speedy charging, EV drivers just have to wait a short time to “fill up,” similar to what would happen at a typical gas station. Additionally, some EVs can use smaller batteries due to their quick charging times, which lowers their cost.
“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 Enovix CEO, president, and co-founder Harrold Rust.
Overcoming Silicon-Related Issues
Enovix is combining a 100% active silicon anode with EV-class cathode materials as part of the company’s three-year Department of Energy grant program. The company claims that batteries are constructed using patented technology. Using silicon as an anode has helped them to overcome many drawbacks such as, contrary to a graphite anode, a standard Li-ion cell can undergo a significant volume increase while charging when using a silicon anode.
The cell contracts as it discharges. As it does so, silicon particles discharge unevenly, leading to their electrical disconnection from current collectors, over-discharge, and pulverization. This results in the formation of new silicon surfaces as well as rapid Li-ion loss.
The company also created a “pre-lithiation” procedure during manufacturing to add extra lithium to top-off lithium trapped at formation as a preventative step. Its batteries can do this because, because of the 3D architecture design, the extra lithium only needs to travel a small distance to infiltrate the anode.
Enovix has made its advancements utilizing a 267-mAh test cell. To be fair, it’s crucial to emphasize that Enovix has made its advancements using a 267-mAh test cell. The low-capacity cell, according to the business, was only employed for chemistry testing. However, it believes that the idea may be expanded to a larger capacity—to the greater than 50-Ah capacities utilized in the automobile industry—without sacrificing any of its benefits.
Testing also showed that Enovix’s batteries only slightly lost capacity after six months of operation at high temperatures. According to the company, its cells have exceeded 1,000 cycles while still keeping 93% of their capacity, resulting in a predicted calendar life of more than 10 years.
Silicon Anode Lithium ion Fire Safety
A normal lithium-ion battery that has been punctured or severely damaged may experience a short, which might discharge the cell in microseconds and perhaps cause a destructive chain reaction known as thermal runaway.
Multiple parallel cell-to-busbar connections are made possible by Enovix’s BrakeFlow technology, an intra-cell device that contains a resistor with a predetermined value. Metal bars called busbars are used to transport enormous currents. In this instance, BrakeFlow controls the flow of current from other battery sections to the short, preventing thermal runaway and preventing the short area from overheating.
Other BrakeFlow features:
- thanks to a 100% active silicon anode, offers superior protection against lithium plating compared to graphite anode cells (140-mV higher lithiation potential).
- because of its thermal conductivity, helps cool hotspots and dissipate heat (nearly 5X cell thermal conductivity compared to similar pouch cells).
- Due to its mechanical internal restraint system, it offers improved protection against physical abuse, including crush, squeeze, and nail penetration.
- It is intended to prevent internal “pinning,” a recognized source of internal shorting in traditional Li-ion batteries, from causing excessive movement of the anode, cathode, and separator.
The company anticipates BrakeFlow will be available in its battery cells in 2023.
Other organizations working on the same technology
The use of silicon as an anode for EV batteries is being researched by several businesses besides Enovix. A similar initiative from Amprius, which is developing EV batteries with a low-cost, quick-charge silicon nanowire anode, received financing ($3 million) from the U.S. Advanced Battery Consortium (USABC).
A division of the U.S. Council for Automotive Research LLC is the USABC (USCAR). Ford Motor Company, General Motors, and Stellantis are some of its member businesses. The goal of USABC is to create electrochemical energy-storage technologies that enhance the commercialization of next-generation EV applications, which is made possible by a cooperative agreement with the U.S. Department of Energy (DoE). Mid- and long-term objectives have been set by USABC in support of its mission to direct its initiatives and track its advancement.
Enevate of Irvine, California, a different battery manufacturer, is creating a “5-Minute Extreme Fast Charge Battery Technology for Electric Vehicles” with a 240-mile driving range (390 km). To increase EV range in cold areas, Enevate’s HD-Energy battery technology is claimed to securely charge and discharge down to 40°C and capture more energy during regenerative braking.
Enevate claims that its porous silicon anode enables the production of large EV pouch cells for research and client sampling in addition to the industry-standard size 21700 cylindrical cells. Mitsubishi, Nissan, and Renault are all supporters of the business.
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