Last year, airline flights banned Samsung Galaxy Note 7s because of its battery-related fires and explosions. Scientists researching the source of the runway beat buildup found the culprit to be small dendrites forming between the anode and cathode of the battery. A materials specialist from the Drexel University at Philadelphia has proposed a low-cost easy solution to preclude dendrite formation.
According to Drexel professor Yury Gogotsi, this simply requires mixing nanodiamonds with the regular lithium-ion electrolyte at one percent concentration. Gogotsi discovered the method along with a doctoral candidate from Tsinghua University at Beijing. However, Gogotsi found it rather easier to confirm that the nanodiamond additive works, than getting Samsung and several other OEMs and Li-ion battery producers to follow the concept.
Gogotsi had to use internal financial support from Drexel for proving the concept. They are now trying to interest industrial partners for funding to characterize the process in more detail. Specifically, they have yet to determine the amount of nanodiamonds necessary to add to the electrolyte for particular applications.
As Li-ion battery technology is already expensive, it is possible that cost-conscious manufacturers are wary of increasing the cost of batteries because of the addition of diamonds of the nanodiamonds. However, according to Gogotsi, the concern is rather unfounded, as, contrary to popular belief, nanodiamonds are not expensive, but cheap to manufacture. Moreover, they can be easily created from waste materials.
Gogotsi suggests a very simple method of manufacturing nanodiamonds. According to him, this is possible using expired explosives—otherwise expensive to dispose of—and exploding them in a sealed chamber. The coating on the walls of the chamber will have more than 50% nanodiamonds with a typical size of 5 nanometers. This is similar to Superman making diamonds from coal in the popular comic books. The presence of nanodiamonds in the electrolyte of a Lithium-ion battery prevents the formation of dendrites that create shorts resulting in runaway heat build-up and subsequent fires.
Although Gogotsi uses nanodiamonds in his lab, the process for creating them came from Russia. Three separate laboratories in Russia independently perfected the technique, which was kept very secret.
A description of the process finally emerged from a publication from the Los Alamos National Lab, and worldwide people use the technique to turn waste into marketable products. These hard-to-dispose-of waste products include the expired C4. Several manufacturers use nanodiamonds widely in their products. These include medical coatings, industrial abrasives, and magnetic field measuring electronic sensors.
According to Gogotsi and his team, the nanodiamonds work as an additive to the electrolyte to co-deposit with lithium ions, and produces dendrite-free deposits of lithium. This is because lithium prefers to adsorb onto the nanodiamond surfaces leading to a uniform deposit of lithium arrays. This uniform deposition of lithium enhances the cycling performance of the electrolyte, leading to a stable cycling of lithium.
As the nanodiamond co-deposition significantly alters the plating behavior of lithium, the process offers a promising method of suppressing the growth of lithium dendrites in batteries using the lithium metal.
