- The non-explosive lithium-ion battery is inspired by an interesting behavior of unique liquids that turn solid on sudden impact.
- They are made by dispersing spherical silica particles in battery liquid, which block the flow of ions on impact.
The lithium-ion batteries are the most energetic rechargeable batteries available in the market. You can find them in all consumer electronic devices. Lithium is the lightest of all metals, has high great electrochemical potential, small memory effect and low self-discharge.
However, they have also been in the news lately because of their ability to burst into flames occasionally. It’s not very common, but when they explode it can cause serious injuries or even death.
Now, researchers at Oak Ridge National Laboratory have developed a cheaper and practical method to help prevent these explosions. The design of non-explosive lithium-ion batteries is inspired by the interesting behavior of unique liquids that turn solid on sudden impact.
All lithium-ion batteries contain a tiny piece of plastic that isolates the 2 electrodes (anode and cathode) while allowing ions to pass through. If for any reason this thin layer of plastic gets damaged, the electrodes could come into contact, causing the battery to catch fire.
To avoid this scenario, some batteries come with a solid electrolyte that is nonflammable. However, the major negative point of solid-state batteries is their manufacturing process: they demand a significant amount of modifications to the existing productions model.
Alternative To Traditional Electrolyte
To build a safer battery, researchers mixed a special additive into the standard electrolyte. This additive solidifies upon impact, which prevents two electrodes from touching each other during a crash.
The lithium-ion battery won’t catch fire as long as their electrodes remain isolated. The best thing is this approach does not require any heavy changes to the existing battery manufacturing model.
This feature has been made possible by colloid — dispersion of very small particles in the battery liquid. In this study, researchers suspended silica in a conventional liquid electrolyte. Specifically, they used spherical silica that has particle-diameter of 200 nm.
Source: Oak Ridge National Laboratory
These tiny particles form a cluster upon impact, blocking the flow of ions and fluids. The advantage of having uniform sized particles is they disperse evenly in the electrolyte and works perfectly. Otherwise, the liquid becomes less viscous during impact (a shear-thinning fluid), making the battery more prone to explosion.
Silica in blue container/White sheet isolates electrodes/Test battery in Gold Bag | Credit: Gabriel Veith
This is not the first time someone has analyzed shear thickening to make safer batteries. Previously, a team of researchers investigated ‘fumed’ silica with irregular particles. Another team published the results of using cylindrical-shaped silica particles.
However, the authors believe that spherical particles have a quicker response time, greater stopping power upon impact, and are easier to manufacture than fumed or cylindrical particles.
Usually, when lithium-ion batteries are manufactured, the electrolyte is ejected into the battery at the final stage of the process, and then it is sealed. This is not possible if you’re building a shear thickening electrolyte. It turns into a solid state as soon as you try to inject it. That’s why researchers added silica in liquid before integrating the electrolyte.
The team plans to work on further improving the technology so the portion that is not damaged in the battery-crash would remain liquid and go on working, while the damaged part would turn into solid.
This type of batteries have a variety of applications, for example, they can be used in drone and electric vehicles. In fact, researchers are aiming to build a mega version of this battery that could stop a bullet. It would be greatly beneficial for soldiers who carry 25 pounds of batteries and 25 pounds of body armor when they are on a mission.