The technological development of lithium batteries has not made breakthroughs for many years. The reason is that it is difficult to ensure the material safety, stability and rapid repetition of charge and discharge while increasing the capacity density. The main culprit of attenuation is microscopic structure. Lithium crystal branches. These sharp needle-like structures may pierce the diaphragm of the cell, causing a short circuit or even a fire. One way to limit its growth is to control the charging rate of the battery. But at a time when the pace of life is accelerating, Such compromise is unacceptable.
This breakthrough in battery technology is focused on a new anode material that is coated with carbon nanofilm.
The good news is that scientists at Rice University have found a good way to double the capacity of currently widely used lithium-ion batteries.
Previously, some laboratories used Kevlar fiber to limit the growth of crystal branches, or to use a new type of electrolyte (a chemical solution carrying a charge).
As early as last year, the same research team at Rice University has developed a lithium metal battery made of asphalt. It has a faster charging speed and is more resistant to the formation of crystal branches.
Now, the research team has taken a step further by introducing carbon nanofilms. It is used to coat lithium-metal anodes for batteries, which are used to more effectively immerse crystal branches, similar to holding heavy objects on lawns to suppress weeds.
Comparison chart: The right side is a metal anode without a carbon nanotube film to limit the lithium crystal branch.
This film absorbs lithium ions from the anode and distributes them during charging. But all of this does not affect the battery charging rate. Research coauthor Rodrigo Salvatierra said:
The role of the carbon nanotube film is to spread the deposited lithium metal to form a smooth layer without crystal branches.
Such improvements do not limit the charging rate of such batteries, and even use high-rate charge and discharge with confidence.
After deploying the new components to last year's asphalt-lithium batteries, the researchers found that after more than 580 cycles, they were able to prevent the growth of the crystal branches. In addition, the coulombic efficiency of the battery was maintained at 99.8%, and the finished product was easier to build.
The left is James University chemist James Tour, graduate Gladys López-Silva, and postdoctoral researcher Rodrigo Salvatierra.
However, Salvatierra explained: Compared to the earlier asphalt batteries, it has some different places.
First, we used a carbon nanotube film to modify the solid lithium metal foil. These two materials have already been prepared for use by batteries.
Secondly, in asphalt-derived electrodes, lithium metal must be electrochemically deposited in order to be used in a complete battery unit.
In the end, the battery with this new anode can store 3 to 5 times more electricity than commercially available products. Even if it is left for one month, its charge loss is negligible. In other words, it will be a reliable long-term storage. Can solution.