- Researchers built a flexible supercapacitor that delivers both high power density and high energy density.
- It shows no performance degradation, even when it is bent at 180 degrees.
- It can retain 97.8% of its capacity after 5,000 cycles.
Supercapacitors are promising electrochemical energy storage devices for mobile power supplies. They bridge the gap between rechargeable batteries and electrolytic capacitors.
Although they can deliver safe operations, high power density, and long cycling life, their practical applications are limited by their poor energy density.
Now, researchers at University College London and the Chinese Academy of Sciences have designed a flexible supercapacitor that charges rapidly and safely stores an incredible amount of energy for use over a long period.
Unlike existing high-powered capacitors, it can store a large volume of energy in a tiny space. Although the device is still in its initial stage of development, it has shown great potential as a portable power in numerous applications such as smartphones, wearable technology, and electric vehicles (EVs).
This newly developed supercapacitor can be used either alongside the existing battery technology or as a replacement for it, to provide more power.
It does not include any liquid electrolyte (which minimizes the explosion risk) and can bend to 180 degrees without degrading performance. These features make it a perfect candidate for integrating into wearable devices and bendy smartphones.
The Optimized Material
The research team built a new design that uses a specialized graphene electrode material with pores. The size of the pores can be altered to store the charge efficiently. They tested the material in multiple configurations and found that the device performs best when pore sizes are equal to the diameter of the ions in the electrolyte.
This tuning gives the new supercapacitor two characteristics:
- High power density: how quickly it can charge/discharge.
- High energy density: how long it can run for.
In contrast, existing supercapacitors exhibit only one of these characteristics.
The maximum energy density of the supercapacitor reaches 88.1 Watt-hour per liter (Wh/L) — the highest energy density achieved by a carbon-based supercapacitor to date.
The existing lead-acid batteries used in EVs have an energy density of 50-90 Wh/L, whereas the fast-charging commercial technology typically has 5-8 Wh/L.
While the energy density of the new supercapacitor is comparable to that of lead-acid batteries, its power density is 10,000 Watt per liter – two orders magnitude higher than standard lead-acid batteries.
The 6cm*6cm supercapacitor shows no performance degradation, even when it is bent at 180 degrees. Moreover, it can retain 97.8% of its capacity after 5,000 cycles.
The achievement of such compact energy storage represents a significant step towards the practical applications for supercapacitors. Quick charging capability, excellent flexibility, and durability make it a perfect candidate for portable power supply in miniaturized electronics and EVs. Imagine charging your phone [from 0 to 100 percent] in a couple of minutes or charging your electric car within ten minutes.
As of now, this supercapacitor is far away from commercialization. The team is working to further improve its design and efficiency.