Lithium-ion batteries with high energy density and high operating voltage are the first choice for energy storage. Smartphones, electric vehicles, and large-scale energy storage power plants will all have their presence. However, it's actually fatal to see batteries that can do everything. Lithium metal tends to generate dendrites after overcharge or repeated use, and then pierces the isolation layer and causes self-explosion.
In order to solve the risk of battery short circuit self-explosion, the family and major manufacturers are constantly looking for solutions. Reza Shahbazian-Yassar, assistant professor of mechanical and industrial engineering at the University of Illinois at Chicago (UCC), said that although organic electrolytes can increase the energy density of lithium-ion batteries, After heterogeneous lithium metal is repeatedly charged and discharged, lithium is easily deposited on the surface and grows dendrites. Therefore, a commercially available organic electrolyte lithium ion battery has not been successfully developed.
Therefore, UIC and the Texas A&M University (TAMU) team are looking forward to accelerating the search for solutions, and hope to learn the principles of chemistry and physics in the process of dendrite formation through supercomputers. Peralan Tamura, professor of chemical engineering at TAMU, stated that The purpose of the team is to develop coating materials that protect lithium metal and to slow the deposition of lithium by the paint.
The team developed graphene oxide nanosheets that can be sprayed on glass fiber separators. These materials allow lithium ions to flow smoothly, while also slowing down and controlling the rate at which ions and electrons combine to become neutral atoms. The coating allows the deposition of atoms not to be as uneven as the needles, but to form a flat surface at the bottom.
The researchers used computer models and simulations, combined with physical experiments and microscopy imaging. The results showed that lithium ions form a thin film on the graphene oxide layer, and then deposited through the material gap underneath the graphene oxide layer. The material gap effect is similar to nostalgic pinball table. The track can slow the deposition speed and guide direction.
Graphene oxide can also increase the cycle life of the battery. Compared with 120 cycles of other batteries, the battery can reach 160 stable cycles.
The graphene oxide can be achieved by inexpensive and cost-effective spraying. However, because the paint is very thin, to determine the location is a challenge, Balbuena said that the coating cannot be determined on the microscopic level. The paint is very thin, so Too precise positioning of its position.
They also explored the graphene oxide by spraying computer model To the current collector (current collector) is parallel or perpendicular better, both the final team found effective, but if you want lithium parallel deposition, material needs sufficient clearance Balbuena said that the computer simulation results let the team and collaborators know how the ions are transferred through the coating. Through these studies, the future may be toward different thicknesses and materials. The current results have been published in "Advanced Functional Materials".