A team of researchers from Drexel University has come up with a new material that allows for extremely fast battery charging speeds.
Batteries composed of this class of materials, called MXenes, have the possibility of charging a laptop or cell phone in seconds. With regards to electric cars, the idea of charging your car in the same time it takes to fill a tank of gas is now a possibility with this new superconductive material.
Batteries have two main limiters in everyday use: charging speed and charge capacity. Charging speed is limited by something in the battery called “internal resistance.”
This internal resistance factor in a battery can be affected by multiple things including the material the battery is composed of, how much charge the battery currently has, and at what current the power block (what goes in the wall) can charge your battery.
If the internal resistance of a regular battery is compared to the internal resistance of the MXene material using the analogy of roads, a regular battery would be a traffic heavy city road while MXene would be a wide multiple lane highway.
“We demonstrate charging of thin MXene electrodes in tens of milliseconds,” Yury Gogotsi, founder and director of the A.J. Drexel Nanotechnology Institute, said in a comment to the Institution of Mechanical Engineers.
“This is enabled by the very high electronic conductivity of MXene. This paves the way to development of ultrafast energy storage devices [that] can be charged and discharged within seconds, but store much more energy than conventional supercapacitors,” he continued.
The charge capacity of a battery is limited by the number of areas within the material where energy can be stored. These sites are called “redox active sites.”
While batteries can be simply made larger to increase the redox active sites, the ability to charge the entire battery quickly is the major problem.
Some materials are better at charging faster and some materials are better at holding more charge. For example, supercapacitors (used in devices such as a camera’s flash) charge extremely quickly but the downside is that they cannot hold very much charge. On the flipside, lithium ion batteries (batteries used in cell phones and laptops) can hold a lot of charge but they take a significant amount of time to charge.
MXene technology allows for extremely quick charging, comparable to a supercapacitor, while also having enough redox active sites to hold a significant amount of energy (enough to make a battery for a phone, laptop or electric car).
One of main reasons that MXene material is able to store a significant amount of energy is because it is a flat material at the atomic level. Like stacking paper, MXene material is easily stacked layer by layer to create a dense structure that can hold a lot of energy. This same property also allows for MXene material to be charged very quickly.
“If we start using low-dimensional and electronically conducting materials as battery electrodes, we can make batteries working much, much faster than today,” Gogotsi said. “Eventually, appreciation of this fact will lead us to car, laptop and cell-phone batteries capable of charging at much higher rates — seconds or minutes rather than hours.”
MXene materials also have several other very important properties beyond their use for batteries such as their antibacterial and water purification properties.
One MXene material has been shown to kill more than 98 percent of bacterial colonies such as E. coli by damaging the cell membranes of the bacterial cells.
The same MXene material has also been shown to very quickly purify water of salts and charged particles.
As novel materials, MXenes have very useful properties. Dr. Gogotsi and his team have spearheaded many research projects towards studying these materials. Their practical ability to be used as batteries and energy storage devices has just started being studied in depth and much is still unknown about these materials.