Microscale energy storage units for wearable and miniaturized electronic devices are improved using porous materials.
Energy storage units that can be integrated into wearable and flexible electronic systems are becoming increasingly important in today's world. A research team from KAUST has now developed a microsupercapacitor that exploits three-dimensional porous electrodes. These micropower units are expected to enable a new generation of "smart"products, such as self-powered sensors for wearables, security, structural health monitoring and "internet of things" applications.
However, for these units to be tiny yet still efficient, the highest energy density must go into the smallest area.
One approach to carrying this out is to construct microbatteries using films with a thickness of just a few micrometers or less and to replace traditional electrolytes with solid-state ones. Thin film batteries have demonstrated relatively high energy density, which is the amount of energy they can store in a given area. However, they are afflicted by limited cycle life and poor power density, meaning they are slow to charge and discharge.
Microsupercapacitors are a faster alternative, and these may prove suitable for applications requiring power pulsing and very long cycle life.
“Also, while batteries must be charged at a constant voltage, a supercapacitor charges most efficiently by drawing the maximum current that the source can supply, irrespective of voltage,” said KAUST Professor of Material Science and Engineering Husam Alshareef from the University's Functional Nanomaterials & Devices group.
This makes supercapacitors more appealing for self-powered system applications where the power source may be intermittent.
Alshareef’s team has now developed integrated microsupercapacitors with vertically-scaled three-dimensional porous current collectors made from nickel foams to improve microsupercapacitor performance. The pores in the foam work to increase the surface area.
“This three-dimensional porous architecture allows excellent electrolyte permeability, good conductivity and faster ion transportation with maximum mass-loading of active material, which increase energy and power density in a given area,” Alshareef said.
The microsupercapacitors were also asymmetric, using two different electrode materials for the cathode (nickel cobalt sulfide) and anode (carbon nanofiber), which nearly doubled the operating voltage. As a result, while delivering high power density (four milliwatts per square centimeter), the microsupercapacitors had an energy density of 200 microwatt-hours per square centimeter.
This is superior to state-of-the-art microsupercapacitors, which achieve between one and forty microwatt-hours per square centimeter, and is comparable to various types of thin film batteries. These high capacities were maintained even after 10,000 operating cycles.
“The high energy and power density achieve in these devices may meet the demand of on-chip storage for various types of integrated microsystems,” noted KAUST Ph.D. student Qiu Jiang, the lead author of the study.
Advanced Energy Materials
Carmen Cecile Denman | Research SEA
How cancer metastasis happens: Researchers reveal a key mechanism
19.01.2018 | Weill Cornell Medicine
Researchers identify new way to unmask melanoma cells to the immune system
17.01.2018 | Duke University Medical Center
On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.
We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
19.01.2018 | Materials Sciences
19.01.2018 | Health and Medicine
19.01.2018 | Physics and Astronomy