Engineering

Chemical bonds can also store energy, new type of battery on the cards

Scientists have discovered that it is possible to store solar or other light-sourced energy in chemical bonds instead of electrons thereby paving way for a new type of battery.

Researchers published a paper in Scientific Reports wherein they have have solved one of the major hurdles in the field by developing a polymer-based system that has double the energy storage density than previous polymer system.

Previous high energy storage density achieved in a polymeric system was in the range of 200 Joules per gram, while their new system is able to reach an average of 510 Joules per gram, with a maximum of 690. Scientists behind the study say that theoretically it is possible to achieve 800 Joules per gram, but nobody could do it until now.

Authors of the new study say their work is based on an earlier theoretical work by Jeffrey Grossman at MIT who had suggested that higher energy density might be achieved if the commonly used compound, azobenzene molecules, were arranged along a rigid carbon nanotube. This frame would allow scientists to manipulate the molecular interactions, which determines how much energy is taken up and released.

Instead of using rigid tube for their work, they went about using flexible polymer as the structure of a polymer chain would let the azobenzene groups get closer to each other and interact, which is when they gain energy and become more stable. Scientists initially thought that distance between the lights in the string was the most important, but what turned out to be more important is the way that multiple strings and their lights are carefully arranged.

“It turns out that the processing solvent we used acts to arrange and regulate the architecture, so the azobenzene molecules attached to the polymer are arranged very neatly and compactly. It basically acts to ensure that there can be maximum packing density”, one of the researchers said.

They used the solvent tetrahydrofuran (THF) for this processing “simply because it’s good solvent for this polymer system,” not suspecting that it would influence how much energy is stored and later released when the team first started.

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