3 Groups Take Aim at Greener, Smaller, and More Power Dense Supercapacitor Tech
Supercapacitors can offer high power density and a lifecycle exceeding 1M cycles. Though supercapacitors hold potential in working with or replacing Li-ion technology, what are some recent developments?
A supercapacitor is a technology with properties that are very similar to ‘normal’ capacitors. They share a capacitance value which is dependent on plate area and plate distance. However, they also contain significantly more power density and capacitance than multilayer ceramic capacitors (MLCC) and chemical batteries.
New developments this year are continuing to push supercapacitors into mainstream design applications. These applications are focused on high-power delivery for short periods of time, like braking or accelerating in electrified vehicles.
Comparing various energy source’s power vs energy densities. Image used courtesy of Kemet
With the recent trend in creating supercapacitor technology, this article will review three announcements and their technologies, including:
- Supercapacitor green research from Imperial College of London
- The continued growth for a supercapacitor startup Skeleton Technologies
- A new supercapacitor product class from AVX
By looking into each advancement, it should become clearer where supercapacitors may be heading in 2021.
Going Green With Supercapacitor Material Science
The search for greener and more eco-friendly alternatives to many technologies is at the forefront of much research, which leads to the first announcement from the Imperial College of London. The team's objective was to produce bio-derived carbon electrodes, which are said to be more sustainable. Their research showed that a potential replacement for graphene-based electrodes is possible with lignin, a byproduct of the paper industry.
Overall, their research focused on a fabrication process used to enhance the lignin fibers through a carbonization process, which resulted in a viable material for higher energy density at a lower cost.
The fabrication process for lignin-based carbon fibers from Researchers at the Imperial University London. Image used courtesy of Servann Hérou et al
Though green research into supercapacitors could play a large role in vehicle electrification; however, it is still in the research phase.
One group no longer in the research realm is Skeleton Technologies. This company has a marketable graphene-based product today and the financial backing to continue supercapacitor development. What can we expect from graphene-based supercapacitors?
Cutting-edge Supercapacitor Manufacturer Expands
Skeleton Technologies says that it is in the Megawatt per second [video] business. Founded in 2009, they specialize in graphene-based supercapacitor development and manufacturing. They also see supercapacitors as a complementary technology to lithium-ion battery storage technology.
The makeup of a supercapacitor. Image used courtesy of Skeleton Technologies
As part of 11 patent families, they have developed a "curved" graphene material, which is said to possess four times the power density with lower effective series resistance (ESR) than traditionally manufactured supercapacitors.
Their recent successful investment rounds have exceeded €120 million over the past twelve months, with investors such as Germany's Federal Ministry of Economic Affairs and Energy and the Marubeni Corporation.
Although the most popular size of capacitor for Skeleton Technologies is 'hand-sized cylindrical packaging, it may not always be the best for all applications.
Though Skeleton Technologies has the potential to become a more significant player in the world of supercapacitors, a more established company, AVX, recently released a low-profile package designed for smaller applications with SWaP in mind.
An Ultra-low Profile Supercapacitor
AVX's newest product family, the PrizmaCap supercapacitor, offers capacitances in the range of 3.5 farads to 15 farads in a thickness range from 0.8 mm to 2.0 mm.
The profile of this capacitor class makes it a potential contender for wearable or handheld applications, especially for applications concerned with SWaP design constraints.
This new supercap is small enough to go in a handheld design. Image used courtesy of AVX
These supercapacitors have several parameters which are very stable over temperature, unlike ‘normal’ class-2 capacitors, including capacitance value and ESR.
Supercapacitors have stable capacitance over more than 100 degrees. Image used courtesy of AVX
When considering the form factor, the AVX-SCP series of supercapacitors could work in many applications. The ability to function across a wide range of temperatures while remaining electrically stable is a crucial advantage for supercapacitors when designing a potential system.
Moving Forward with Supercapacitor Development
Whether biological byproducts, like lignin, will replace the current market for graphene-based supercapacitors is unknown. However, the idea of replacing carbon-based technologies for a 'greener' supercapacitor alternative is in line with the big picture: a cleaner environment.
Supercapacitors tend to partner well with existing chemical sources of energy that they are already offering environmental benefits. They could also reduce peak power demands on the Li-ion battery packs, which can increase their lifespans.
Supercapacitor green research, new market entrants in ultra-low-profile packages, and continued investment in an already proven startup will hopefully herald a future where supercapacitor technology will go further into the mainstream.