A short circuit from a lithium-ion battery can lead to fire.
If a lithium-ion battery is shorted, due to an overcharge or damage from an accident, the battery's energy is suddenly released, initiating an unstoppable chain reaction called "thermal runaway."
The runaway reaction causes an extreme temperature spike. By reaching a few hundred degrees within milliseconds, the battery bursts into flames.
A California-based company, which draws on the expertise of UCLA scientists, has turned to the strong, thin material of graphene to prevent thermal runaway and create a non-flammable battery.
The battery's graphene-made electrodes withstand the volume changes during charge and discharge, reducing the chances of an internal short circuit.
Headquartered in Los Angeles, Nanotech Energy Inc. was founded in 2014 by Jack Kavanaugh, who serves as the chairman and CEO, along with leading UCLA scientists Dr. Richard Kaner and Dr. Maher El-Kady, a professor at UCLA and co-founder and Chief Technology Officer of Nanotech Energy.
Sometimes referred to as a "wonder material," graphene is a one-atom thick layer of carbon atoms arranged in a hexagonal lattice structure. The single layer of graphite is an excellent conductor of electricity and one of the strongest materials ever known, says El-Kady.
"Graphene makes batteries with lower internal resistance, thus preventing the battery from overheating during charging," El-Kady told Tech Briefs. "This is critical because it eliminates the driving force for ‘thermal runaway’ in the first place."
In the Nanotech Energy electrodes, graphene is infused with standard battery materials. Graphene is also the main ingredient of the anode.
Additionally, traditional — and intrinsically flammable — carbonate electrolytes were replaced with Nanotech's thermally stable, proprietary electrolyte.
"Even if we intentionally induce a short-circuit, the battery would heat up but won't catch fire," said El-Kady. (See a demonstration of the intentional short circuit in the video below.)
In preparation for its graphene battery launch, Nanotech Energy has been working on the development of a high-performance, non-flammable battery for Daimler Mercedes hybrid and electric automobiles.
In a short Q&A with Tech Briefs below, El-Kady explains why he thinks his team's battery will be a game-changer for both electronics and electric cars.
Tech Briefs: What is the traditional structure of a battery, and how is your structure different?
Dr. Maher El-Kady: A battery is made up of two electrodes and a liquid electrolyte in which the two electrodes are immersed. The electrolyte provides medium for the movement of lithium ions between the two battery electrodes during operation. There are many reasons batteries catch fire, but in most cases it has to do with the battery design and electrolyte. If the cell is shorted due to an overcharge or during an accident, the energy stored in the battery is suddenly released in a fire.
So, the secret to a safer battery is to develop new battery designs that can prevent electrodes from touching at elevated temperatures, or even better, get rid of the flammable electrolyte that catches fire in case of a thermal runaway.
Tech Briefs: How come your battery doesn’t catch on fire?
El-Kady: While graphene plays an important role in our battery, there is another component in the battery that is critical to this challenge: the electrolyte.
The electrolyte is made by dissolving a lithium salt in the proper solvent, whereas additives are often used to improve the cycling stability of the battery. Unfortunately, standard lithium-ion batteries use a solvent based on a combination of linear and cyclic chain carbonates that are very flammable and would catch fire immediately with a short circuit or an overcharge.
It became clear to us that we need to replace this solvent entirely with something else that can afford the operation at high temperatures. After trying a large number of solvents and additive materials, we came up with a new electrolyte that not only is stable but also is made from cheap materials, easy to manufacture, and, of course, is non-flammable.
Tech Briefs: What was your responsibility on this project? Can you describe the team that made this happen?
El-Kady: The battery was developed under Nanotech Energy, a spinoff of the University of California, Los Angeles. We started Nanotech Energy six years ago with the goal of revolutionizing the energy storage market with more powerful batteries and supercapacitors utilizing the new wonder material "graphene." At Nanotech Energy, I am leading a team of scientists and engineers to design a battery that not only can last longer but also is safer to use.
Tech Briefs: What inspired the use of graphene? How come it hadn’t been used before?
El-Kady: With its extraordinary electronic and mechanical properties, graphene has garnered attention for use in batteries in academic research labs and industry. Despite the significant progress made over the last few years, the lack of feasible techniques for the mass production of high-quality graphene limits its potential.
Besides, there have been several issues for the precise control of the microstructure of graphene electrodes, something that defines the properties of the resulting batteries. With nearly 20 years of research experience in graphene, Nanotech Energy and UCLA scientists developed effective methods for the production of high-quality graphene.
Tech Briefs: The above video says this will “revolutionize your electronic devices” How so? Also, how will this achievement impact the automotive industry?
El-Kady: Lithium ion batteries have transformed the way society uses energy. They can hold a lot of charge in a small volume, allowing cell phones, laptop computers and even electric cars to exist. So, they are closely related to our daily lives but they have obvious safety issues. Remember what happened to the exploding Galaxy Note back in 2016, leading to many injuries? As a result, the Galaxy Note was banned from use in airports and all airlines flights. We learned how critical it is to have a safe battery. Now imagine what would happen to consumer electronics with our safe battery solution. We also believe it is going to be a game changer for the electric car market as well.
You will see many examples from research papers claiming a safe battery. However, they are usually very small cells meant for research purposes only, and no practical battery has been demonstrated so far.W have successfully demonstrated a practical battery using the actual 18650 cylindrical cells — standard in electric cars, flashlights, and laptop computers — that are ready for commercialization.
What do you think? Share your questions and comments below.