What are Super Capacitors? How are they Different from Normal Electrolytic Capacitors? How are they Different From Batteries? In What way are they gonna revolutionise the Today's Power Storage Systems?
- If these are the Questions that bother you, then this is the right place to be!!!
Before going into the debate if supercapacitors can really change the future of Energy Storage on their own, it is worth taking some time to look into What they are ? and How they are different from Normal Batteries or Capacitors!!
Lithium Ion batteries are the most common Storage Units used in the present market. The batteries are made up of a positive and negative side which are called Electrodes(Cathode and Anode). These two sides are submerged in a Liq. Electrolyte and are separated by a micro-perforated separator that allows only ion transfer. When a battery charges or discharges, these ions flow back and forth between the electrolytes. During this process, various changes are seen in the battery. It expands and contacts, heats up and cools down, all of which result in a slow degradation of the battery life, giving it a limited life span. But, on the contrary, Batteries have a very high Energy density, So it can store a lot of Energy for later use.
But capacitors are different, they don't rely on plates or electrolyte for storing Energy, they do it Electrostatically. They use a dielectric or Insulator between the plates to separate the collection of Positive and Negative Charges. It is this separation of charges between the plates that allows it to store Energy in the form of Electric fields and release it Quickly, basically capturing static electricity. Unlike batteries, that degrade in time and lose their threshold voltage over time, a 5V capacitor now would remain a 5V capacitor even after 20-30 years later. A capacitor has a much better power throughput than a battery, so we can charge in matter of minutes, but the specific energy is very low. It is good for small burst of energy, but not a long term use.
A brief History
Under these conditions of pros and cons, the Supercapacitor makes its way. They try to bridge the gap between a traditional capacitor and a super capacitor. The idea of a supercapacitor is not a new thing. In 1957 the first supercapacitor device was created by General Electric, but there aren't any known applications from that time. In 1966 the Standard Oil Corp. accidentally discover the double layer capacitor while working on fuel cells, but it wasn't till the late 1970s that the Japanese company, NEC, began commercially offering the first "supercapacitor" for computer memory backup. In 1990s, products such as ECOND's PSCap, a starter for diesel trains began hitting the market and pushing the boundaries of energy storage and capacitor applications. Companies like Maxwell Tech., Murata and Tecate generally dominate the supercapacitor field.
How a Supercapacitor works ?
How is a super conductor different from a regular capacitor ! Well a supercapacitor is something that is kind of starting to venture towards a battery from its traditional capacitive nature. It uses electrolytes on either side of an Insulator. When current is supplied, the ions build up on either side of the insulator, creating a double layer of charge. What makes a supercapacitor truly superior to normal capacitors or even a battery is the distance between the metal plates. In normal capacitors, the distance is around 10-100 microns, whereas in a supercapacitor the distance is narrowed to 1/100 th of a micron which leads to a stronger electric field i.e larger Energy. The additional carbon plated plates on supercapacitors increase the available surface area for storage capacity upto a 1 00 000 times with respect to a normal capacitor.
The Uses and Advantages
So what's these power hungry giants used for ? Tech. wise we are just at the beginning of supercapacitor applications. Well its has been found to have the biggest potential for application in hybrid-transportation. The modern green vehicles produced by various companies like Toyota, Lamborghini etc uses some form of supercapacitor in combination with Lithium ion battery. Although Tesla invested about $ 200 million in the purchase Maxwell Techs, Elon Musk has said his focus is not on expanding the use and the development of Maxwell's Supercapacitors for Tesla vehicles, but instead in their battery-manufacturing technology. However, Toyota's Hybrid-R concept car and Lamborghini's high power Sian are using supercapacitors for a very specific role of "Power Regeneration systems during degeneration". When a car slows down, the energy generated from the action is stored by super capacitors onboard and later used for acceleration - saving batteries from strenuous actions than acceleration and deceleration, taking advantage of a supercapacitor's superior power throughput.
In Switzerland, a fleet of busses will be exposed to charging stations at variety of stops along the route. Just 15 sec can stop the Energy charge off and only a few minutes would suffice for a full charge from nothing. With frequent top offs it makes up for the lack of energy density and storage. Since it can draw lower current over periods of few minutes at a time, it puts less stress on the grid.
Supercapacitors till can't compete with Li-ion batteries when it comes to the higher. energy density and long term storage. But despite this, some companies are making progress on projects that are poised to make supercapacitor more universally applicable.
Graphene as a breakthrough!
There have been recent development in Graphene based capacitors are once again pushing the growth of supercapacitors. Graphene and Nanotubes play a role in the future of supercapacitors. Companies like NAWA Tech. and Skeleton Tech have taken supercapacitors to the next level by incorporating graphene into the coating f metal plates, taking conventional use to the next level. Graphene provides the next Generation of supercapacitors with an interesting array of improvements. Graphene offers substantially more surface area, giving supercapacitors even more capacity for energy storage. But in addition to that, graphene is ultra light, and has unique elasticity and is incredibly strong.
Hybrid Techs-The transition begins
In fact NAWA Tech and Skeleton and other supercapacitor companies have already have already found major applications for their graphene based superconductors. It has developed an "e-motorcycle" that uses a supercapacitor - Lithium ion hybrid battery, making it extremely efficient. The regenerative braking power battery has a very slow charge rate. The supercapacitor combo allows it to recoup 80-90 % of the Energy from braking and immediately reuse that for acceleration. This Hybrid tech is used to create fast charging battery systems, e-motorbikes and e-scootors by ZapGo's management. The supercapacitor are not aiming at replacing since Li-ion batteries still have a far greater energy density. The most promising recent development would be seen in transitions system i.e. incorporation of Hybrid systems. Lithium batteries have a power capacity of 250 Wh/kg whereas Ultracapacitors have only about 20 Wh/kg. All the present applications of supercapacitors are some kind of combination of the both. It has been seen when these are placed in parallel to normal Li-ion batteries, their life span increases drastically since it decreases the workload and intensity a battery needs to experience. It is seen that this method can increase battery life upto 4 times!!
With the popularization of this hybridization method and application of graphene and new research going on...Supercapacitors will sure make its mark in the revolution of battery Technologies.
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