Nanoscale Pillars Could Play a Role in Future Li-ion Batteries
Chemists have been trying to find a way to construct reliable batteries with tin or silicon electrodes because they both have the potential to store very large amounts of energy per kg of batteries. (People often confuse power with energy — you should understand the difference before continuing.)
Batteries with silicon electrodes have been demonstrated by Stanford University researchers to store 1,000 Wh/kg, which is ten times more than that of the average lithium-ion battery.
However, silicon and tin electrodes have a major drawback which must be addressed before they can become practical — they don’t last long. As they absorb lithium ions, they expand, and as they release lithium ions, they contract.
Expansion and contraction causes them to crack and, before long, they are no longer usable.
Tin electrodes actually absorb too many lithium ions and expand 2-3 times their size and then break. Silicon on the other hand is too brittle, so researchers developed an electrode made of silicon wires instead, but it also had a short lifespan.
Researchers have been trying alloys containing these materials with the hope that they can withstand more expansion and contraction, but this article pertains to the use of microscopic pillars (columns) made of tin that are sandwiched by sheets of graphene. This new type of battery is more expensive per watt-hour of energy than traditional batteries.
I should add that even though a higher performance battery constructed of advanced technology may cost more to manufacture per kg, fewer high-performance batteries are required to achieve the same level of performance and driving range as an electric vehicle equipped with traditional batteries, so it may not necessarily cost more than traditional batteries.
If you didn’t understand the paragraph above: An electric vehicle with lighter batteries that stores as much energy as traditional ones will drive farther per charge. A vehicle with batteries that produce more power for its weight is either faster or could achieve the same performance with fewer batteries, and fewer batteries means a cheaper vehicle.
If the lighter batteries are slightly more expensive per watt-hour of energy that they store, but they are much lighter than traditional ones, that would be a big help in achieving the same driving range and performance as a traditional vehicle.
As is the case with many new technologies, this new type of battery has to be improved significantly because it can be recharged more than 30 times.
Graphene image via Wikimedia Commons
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