We live our lives through portable devices, and the race is on to create better energy storage for those devices. Could graphene supercapacitors be the holy grail?
So before I can explain how super capacitors will fix this, let’s back up and explain how batteries work in the first place.
To make it simple, batteries work by moving electrons from a negatively charged material called an anode to a positively charged material called the cathode, and the device siphons off those electrons to power the device.
For instance, nickel cadmium batteries use a nickel oxide cathode and a cadmium anode. Hence the name.
This is a chemical process called oxidation that involves an electrolyte layer sandwiched between the electrodes.
In the case of the nickel cadmium batteries, they use potassium hydroxide as the electrolyte.
But this is a one-shot deal. The chemical reaction releases the electrons, but there’s no way to re-introduce electrons into the equation.
So they’re not rechargeable. And for a world increasingly reliant on portable devices, that’s just not good enough.
Enter Lithium-Ion batteries, which were developed in the 1970’s by John B. Goodenough. That’s his real name. That’s not a joke.
Lithium ion batteries have a cathode made of lithium, duh, and an anode made of carbon, again with an electrolyte between the layers to facilitate the reaction.
The difference is lithium will absorb more electrons, so it can be recharged. But it is still a chemical reaction, so it can only reintroduce those electrons at a certain charge rate.
Super capacitors work differently. Instead of using a chemical reaction to make electrons flow, also called and electrochemical process, they use static electricity, or an electrostatic process.
Now, capacitors have been in our computers for decades, and they work by holding opposite charges between two metallic plates separated by a dielectric material.
Super capacitors, as you may have already figured out, are larger versions of capacitors that use a double layer to hold more energy. In fact they’re sometimes called double-layer capacitors.
And the cool thing about them is that since the electricity is static and not chemical, there’s far less resistance to the charge. In fact, it’s almost instantaneous.
The problem is, they don’t hold that much energy. You need a vast amount of surface area to hold enough energy to make them really useful.
So Lithium Ion batteries are very energy dense, meaning they hold a lot more stored energy, but super capacitors are very power dense, meaning the transfer the energy much faster.
If, theoretically, you could create super capacitors that could hold as much as a lithium ion battery, you’d have cell phones that could recharge in seconds and it would be good for the rest of the day.
And dare we dream it? An EV car that fully charges faster than it takes to pump gas.
There is one material that could make this dream a reality. It’s called graphene.
Graphene is basically a one-atom thick lattice of carbon atoms that has some ridiculous properties. It’s 200 times stronger than steel, but incredibly light, biodegradable, biocompatible, meaning it can be used in the human body.
They say it can be used to desalinate sea water, make space elevators, and form the basis for supercomputers, but for our purposes, it also happens to be one of the most electrically capacitive substances known to man.
It has the same energy density as lithium ion batteries with the power density of super capacitors. And since it’s only one atom thick, you can pack a ton of surface area into a small space.
With any luck, in the next 10-15 years, we’ll have super capacitor batteries that can handle energy densities at industrial scales giving us quick, plentiful electricity whenever we need it.