A recent MIT invention could enhance the electricity storing ability of current lithium ion batteries by several times. Specifically, the batteries that were targeted were lithium-air, whose effectiveness has only recently been proven.
Basically, even the original versions of lithium air batteries are able to outperform classic lithium ion batteries by several times by using noble-metal-based catalysts. Replacing the heavy solid electrodes with a porous carbon electrode is the key to the performance enhancement. The latter combine oxygen from the air that flows through the system with lithium ions and form lithium oxides.
The carbon fiber-based electrodes invented by the MIT researchers can do a better job than the simple porous carbon used previously, because they have a higher porosity and can store the solid oxidized lithium that fills the pores as the battery discharges more efficiently.
To make the carbon fibers, the researchers grew vertically aligned arrays of nanofibers through a chemical vapor deposition process.
The carpet-like material they made contains 90 percent void space “that can be filled by the reactive material during battery operation,” says Yang Shao-Horn, the Gail E. Kendall Professor of Mechanical Engineering and Materials Science and Engineering and senior author of the paper. The old version of the battery only contained 70 percent void space, which obviously translated into a lower energy storing capacity.
The gravimetric energy stored by these electrodes Ã¢â‚¬â€ the amount of power they can store for a given weight Ã¢â‚¬â€ “is among the highest values reported to date, which shows that tuning the carbon structure is a promising route for increasing the energy density of lithium-air batteries,” Gallant says. The result is an electrode that can store four times as much energy for its weight as present lithium-ion battery electrodes.
Lithium air batteries have been designed with electric cars in mind. Currently, classic lithium ion storage devices are being tested in real life conditions, but placing them inside cars has been a tough decision to make. I guess that the next generation of lithium-based would enter the electric car market easier, since the first wave had already been tested.