Researchers are reporting they have developed a new material made from three-dimensional, highly porous nano-silicon that could give future lithium ion batteries a ten times higher capacity than they currently have.
The storage capacity of current generation lithium ion batteries remains a bottleneck for the widespread adoption of electric cars due to a perceived limited driving range. Although we could argue whether a 100-130 mile range really is that much of a limitation or not, perhaps the better solution is to be able to ignore that argument altogether by increasing battery capacity.
The main reason current lithium ion batteries have a relatively low storage capacity has to do with the type of anode the batteries use. A lithium ion battery consists of two main parts: a lithium metal oxide cathode and, currently, a graphite anode. During charging the lithium ions migrate from the metal oxide to the anode and get stored between the graphite sheets for later use. When power is needed, the lithium ions discharge back to the cathode.
The graphite anodes currently in use have a low capacity for storing lithium ions, and it is this problem that gives the batteries a low overall storage capacity. Researchers have realized for a while that if the graphite was replaced with a micro-porous silicon structure (somewhat like a nano-sponge made of silicon), the holding capacity of the anode could be increased by ten times.
The problem with this approach is that, up til now, the silicon has easily cracked and pulverized as it was loaded with lithium ions during the charge cycle.
But, as published in the current issue of the journal Angewandte Chemie International (1), a team of scientists from South Korea has discovered a way to bulk produce these nano-silicon sponges so that they can withstand repeated charging and discharging cycles. Not only does this new material have a much higher charge capacity, the nature of its nano-structure allows for rapid charging and discharging.
It’s not clear how long it might be for this material to reach commercialization, but this breakthrough certainly seems promising in the quest to develop higher and higher battery storage capacities.
(1) Angewandte Chemie International Edition, doi: 10.1002/anie.20080435
Image Credit: From the journal article in Angewandte Chemie International