Researchers from the Massachusetts Institute of Technology (MIT), Cambridge, and Tsinghua University, China have come up with a possible solution to the problem with electrodes in rechargeable batteries. An electrode goes through repeated cycles of charging and discharging, which means that it shrinks and expands during each one of these cycles. This change in volume causes the skin layer to shed and reform, damaging the battery’s performance over time.
The researchers have an unlikely inspiration for their solution: the humble egg. They have created an electrode made of nanoparticles with a solid shell, and a yolk inside that can change size again and again without affecting the shell. The yolk is made from aluminium rather than the more commonly used graphite, with the nanoparticle shell made from titanium dioxide; this combination appears to be the most effective.
Aluminium is a low-cost solution with a high capacity, but it needs the shell because of the expansion and contraction of the aluminium particles. The shell remains stable, so the aluminium is protected from the electrolyte in the battery.
The most exciting aspect for the research team is that the manufacturing process appears simple and easily scalable, and they are confident that not only could battery cycle life be drastically improved, but the battery’s capacity and power can be dramatically increased.
To read a full report on this development see: ASM International.