When it comes to the batteries that power much of our world today, two elements are of utmost importance: their longevity and their capacity. Researchers are constantly working on improving both those aspects.
Reduced storage capacity
Today we have lithium-ion and sodium batteries. Although both are powerful batteries, repeated cycles of charging and use can significantly mess with their longevity and reduce their storage capacity over time.
Now, engineers at the University of Tokyo have conceived of a way to avoid this problem by designing self-repairing batteries. Professor Atsuo Yamada and his team have come up with an innovation that not only extends the life of batteries but can also afford them higher capacities as well.
Batteries are normally composed of layers of metallic material. As batteries charge and discharge, these layers begin to be destroyed and develop cracks called stacking faults.
These flaws diminish the batteries' ability to store and deliver a charge. The reason behind this degradation stacking is because the material is held together by a weak force called the Van der Waals force.
This force is easily thwarted by the stress put on the batteries during charging and use. However, Yamada and his colleagues conceived of anew material that can withstand this stress.
The Van der Waals force
They demonstrated that if the battery is made with a model material - oxygen redox-layered oxide (Na2RuO3), not only does the degradation from charge and discharge cycles diminish, but the layers actually self-repair. This is because Na2RuO3 is held together by a force called coulombic attraction, which is far stronger than the Van der Waals force.
"This means batteries could have far longer life spans, but also they could be pushed beyond levels that currently damage them," said Yamada. "Increasing the energy density of batteries is of paramount importance to realize electrified transportation."