Solar cells that produce electricity 24/7, not just when the sun is shining. Mobile phones with built-in power cells that recharge in seconds and work for weeks between charges.
These are just two of the possibilities raised by a novel supercapacitor design invented by material scientists at Vanderbilt University that is described in a paper published in the Oct. 22 issue of the journal Scientific Reports.
It is the first supercapacitor that is made out of silicon so it can be built into a silicon chip along with the microelectronic circuitry that it powers. In fact, it should be possible to construct these power cells out of the excess silicon that exists in the current generation of solar cells, sensors, mobile phones and a variety of other electromechanical devices, providing a considerable cost savings.
“If you ask experts about making a supercapacitor out of silicon, they will tell you it is a crazy idea,” said Cary Pint, the assistant professor of mechanical engineering who headed the development. “But we’ve found an easy way to do it.”
Instead of storing energy in chemical reactions the way batteries do, “supercaps” store electricity by assembling ions on the surface of a porous material. As a result, they tend to charge and discharge in minutes, instead of hours, and operate for a few million cycles, instead of a few thousand cycles like batteries.
These properties have allowed commercial supercapacitors, which are made out of activated carbon, to capture a few niche markets, such as storing energy captured by regenerative braking systems on buses and electric vehicles and to provide the bursts of power required to adjust of the blades of giant wind turbines to changing wind conditions. Supercapacitors still lag behind the electrical energy storage capability of lithium-ion batteries, so they are too bulky to power most consumer devices. However, they have been catching up rapidly.
Research to improve the energy density of supercapacitors has focused on carbon-based nanomaterials like graphene and nanotubes. Because these devices store electrical charge on the surface of their electrodes, the way to increase their energy density is to increase the electrodes’ surface area, which means making surfaces filled with nanoscale ridges and pores.
“The big challenge for this approach is assembling the materials,” said Pint. “Constructing high-performance, functional devices out of nanoscale building blocks with any level of control has proven to be quite challenging, and when it is achieved it is difficult to repeat.”
So Pint and his research team – graduate students Landon Oakes, Andrew Westover and post-doctoral fellow Shahana Chatterjee – decided to take a radically different approach: using porous silicon, a material with a controllable and well-defined nanostructure made by electrochemically etching the surface of a silicon wafer.
This allowed them to create surfaces with optimal nanostructures for supercapacitor electrodes, but it left them with a major problem. Silicon is generally considered unsuitable for use in supercapacitors because it reacts readily with some of chemicals in the electrolytes that provide the ions that store the electrical charge.
With experience in growing carbon nanostructures, Pint’s group decided to try to coat the porous silicon surface with carbon. “We had no idea what would happen,” said Pint. “Typically, researchers grow graphene from silicon-carbide materials at temperatures in excess of 1400 degrees Celsius. But at lower temperatures – 600 to 700 degrees Celsius – we certainly didn’t expect graphene-like material growth.”
When the researchers pulled the porous silicon out of the furnace, they found that it had turned from orange to purple or black. When they inspected it under a powerful scanning electron microscope they found that it looked nearly identical to the original material but it was coated by a layer of graphene a few nanometers thick.
When the researchers tested the coated material they found that it had chemically stabilized the silicon surface. When they used it to make supercapacitors, they found that the graphene coating improved energy densities by over two orders of magnitude compared to those made from uncoated porous silicon and significantly better than commercial supercapacitors.
The graphene layer acts as an atomically thin protective coating. Pint and his group argue that this approach isn’t limited to graphene. “The ability to engineer surfaces with atomically thin layers of materials combined with the control achieved in designing porous materials opens opportunities for a number of different applications beyond energy storage,” he said.
Go deeper with Bing News on:
- Global Supercapacitor Market Insights (2020 to 2025) - by Manufacturers, Regions, Technology and Application - ResearchAndMarkets.comon April 16, 2021 at 8:01 am
The “Supercapacitor Global Market Insights 2020, Analysis and Forecast to 2025, by Manufacturers, Regions, Technology, Application” report has been added to ResearchAndMarkets.com’s offering. This ...
- Supercapacitor Materials Market Size is Expected to Grow with a CAGR of 16.7% Globally with Top Countries Data Analysis and Forecast 20212027on April 16, 2021 at 4:45 am
Supercapacitor Materials Market Size is Expected to Grow with a CAGR of 16.7% Globally with Top Countries Data Analysis and Forecast 2021–2027 Posted on Apr 16 2021 3:05 AM Supercapacitor Materials ...
- Supercapacitors For The Raspberry Pion April 14, 2021 at 5:00 pm
To solve this problem, [Pavol Sedlacek] has created a supercapacitor-based UPS specifically for the Raspberry Pi that gives it enough time to properly halt its processes and shut down if it ...
- Supercapacitor Market will Witness Consistent Growth; Driven by Rising Demand (2022-2031) | Says Market.uson April 13, 2021 at 11:17 pm
Apr 14, 2021 (WiredRelease via Comtex) -- Market.us adopted a multidisciplinary detain during the pandemic-era to focus on the revolutionary trends, growth and industry statistics along with ...
- Supercapacitor Market 2021 Emerging Technologies, Trends by Forecast 2024on April 13, 2021 at 9:45 am
Albany, NY -- (SBWIRE) -- 04/13/2021 -- Supercapacitor refers to a storage device of electrochemical energy that is capable of releasing as well as storing energy through desorption and reversible ...
Go deeper with Google Headlines on:
Go deeper with Bing News on:
- Why organic solar cells have low efficiencieson April 14, 2021 at 5:00 pm
Organic photovoltaics have several advantages over conventional silicon-based cells ... to deliver “low battery” status alerts. Supercapacitors are used in consumer electronics to store ...
- FAQs About Power Density: Back to Basicson April 9, 2021 at 7:05 am
Silicon devices can’t even come close to ... and climbing since it has higher power density and faster response. A supercapacitor, when compared to a battery, has much higher specific power.
- Goofy pronouncement on solar power from someone who should know betteron April 1, 2021 at 5:00 pm
Few people would argue with that statement particularly after a gunman damaged a transformer April 16, triggering power shortages in Silicon ... status alerts. Supercapacitors are used in consumer ...
- Energy Harvesting, Low Power Consumption Are the Way Forward for IoT, Wearableson March 22, 2021 at 5:00 pm
Brian Zahnstecher is principal of PowerRox LLC, a Silicon Valley-based power electronics consulting ... and storage, such as batteries or supercapacitors that store the harvested energy, he said.
- Future batteries, coming soon: Charge in seconds, last months and power over the airon March 21, 2021 at 4:59 pm
This alternative type of lithium-ion battery uses silicon to achieve three times ... at Rice University have made a breakthrough in micro-supercapacitors. Currently, they are expensive to make ...