Next-Gen Lithium-Ion Batteries – Combining Graphene + Silicon Could it be the Key?
Researchers have long been investigating the use of silicon in lithium-ion batteries, as it has the potential to greatly increase storage capacity compared to graphite, the material used in most conventional lithium-ion batteries. By some estimates, silicon could boast a lithium storage capacity of 4,200 mAh/g—11 times that of graphite.
However, despite its benefits, silicon comes with its own challenges.
“When you store a lot of lithium ion into your silicon you actually physically extend the volume of silicon to about 3 to 3.8 times its original volume—so that is a lot of expansion,” explained Bor Jang, PhD, in an exclusive interview with R&D Magazine. “That by itself is not a big problem, but when you discharge your battery—like when you open your smart phone—the silicon shrinks. Then when you recharge your battery the silicon expands again. This repeated expansion and shrinkage leads to the breakdown of the particles inside of your battery so it loses its capacity.”
Jang offers one solution—graphene, a single layer sheet of carbon atoms tightly bound in a hexagonal honeycomb lattice.
“We have found that graphene plays a critical role in protecting the silicon,” said Jang, the CEO and Chief Scientist of Global Graphene Group. The Ohio-based advanced materials organization has created GCA-II-N, a graphene and silicon composite anode for use in lithium-ion batteries.
The innovation—which was a 2018 R&D 100 Award winner—has the potential to make a significant impact in the energy storage space. Jang shared more about graphene, GCA-II-N and its potential applications in his …
Interview with R&D Magazine:
R&D Magazine: Why is graphene such a good material for energy storage?
Jang: From the early beginning when we invited graphene back in 2002 we realized that graphene has certain very unique properties. For example, it has very high electrical conductivity, very high thermal conductivity, it has very high strength—in fact it is probably the strongest material known to mankind naturally. We thought we would be able to make use of graphene to product the anode material than we can significantly improve not only the strength of the electrode itself, but we are also able to dissipate the heat faster, while also reducing the changes for the battery to catch fire or explode.
Also graphene is extremely thin—a single layer graphene is 0.34 nanometer (nm). You can imagine that if you had a fabric that was as thin as 0.34 nanometers in thickness, than you could use this material to wrap around just about anything. So it is a very good protection material in that sense. That is another reason for the flexibility of this graphene material.
Read More: Talga’s graphene silicon product extends capacity of Li-ion battery anode
Another interesting feature of graphene is that is a very high specific surface area. For instance if I give you 1.5 grams of single layer graphene it will be enough to cover an entire football stadium. There is a huge amount of surface area per unit weight with this material.
That translates into another interesting property in the storage area. In that field that is a device called supercapacitors or ultracapacitors. The operation of supercapacitors depends upon conducting surface areas, like graphene or activated carbon. These graphene sheets have, to be exact, 2630 meters squared per gram. That would give you, in principle, a very high capacity per unit gram of this material when you use it as an electron material for supercapacitors. There is are so many properties associated with graphene for energy applications, those are just examples, I could talk about this all day!
Link: genesisnanotech
