Aqueous storage device needs only 20 seconds to go

March 1, 2018, The Korea Advanced Institute of Science and Technology (KAIST)
Aqueous storage device needs only 20 seconds to go
Switching a wearable LED kit with two AHCs in series charged by a flexible photovoltaic cell. Credit: KAIST

A KAIST research team has developed a new hybrid energy storage device that can be charged in less than a half-minute. It employs aqueous electrolytes instead of flammable organic solvents, so it is both environmentally friendly and safe. It also facilitates a boosting charge with high energy density, which makes it suitable for portable electronic devices.

Professor Jeung Ku Kang and his team from the Graduate School of Energy, Environment, Water, and Sustainability developed this hybrid storage with high energy and power densities along over a long cycle life by assembling fibre-like polymer chain anodes and sub-nanoscale metal oxide cathodes on graphene.

Conventional aqueous electrolyte-based energy storage devices have a limitation for boosting charges and high energy density due to low driving voltage and a shortage of anode materials. Energy storage device capacity is determined by the two electrodes, and the balance between cathode and anode leads to high stability. In general, two electrodes show differences in electrical properties and differ in ion storage mechanism processes, resulting in poor storage and stability from the imbalance.

The research team came up with new structures and materials to facilitate rapid speed in energy exchange on the surfaces of the electrodes and minimize the energy loss between the two electrodes.

The team made anodes with graphene-based polymer chain materials. The web-like structure of graphene leads to a high surface area, thereby allowing higher capacitance.

Schematic diagram for aqueous hybrid capacitors. Credit: KAIST

For cathode materials, the team used metal oxide in sub-nanoscale structures to elevate atom-by-ion redox reactions. This method realized higher energy density and faster energy exchange while minimizing energy loss.

The developed device can be charged within 20 to 30 seconds using a low-power charging system, such as a USB switching charger or a flexible photovoltaic cell. The developed aqueous hybrid energy device shows more than 100-fold higher power compared to conventional aqueous batteries and can be rapidly recharged. Further, the device showed high stability with its capacity maintained at 100% at a high charge/discharge current.

Professor Kang said, "This eco-friendly technology can be easily manufactured and is highly applicable. In particular, its high capacity and high stability, compared to existing technologies, could contribute to the commercialization of aqueous capacitors. The device can be rapidly charged using a low-power charging system, and thus can be applied to portable electronic device."

Aqueous storage device needs only 20 seconds to go
TEM images of an anode and cathode. Credit: KAIST

Explore further: Hybrid electrolyte enhances supercapacitance in vertical graphene nanosheets

More information: Il Woo Ock et al, Synthesis of Pseudocapacitive Polymer Chain Anode and Subnanoscale Metal Oxide Cathode for Aqueous Hybrid Capacitors Enabling High Energy and Power Densities along with Long Cycle Life, Advanced Energy Materials (2018). DOI: 10.1002/aenm.201702895

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rrwillsj
4 / 5 (4) Mar 01, 2018
As those gambling in looting carbon resources are discovering. All sorts of competitive technologies are being invented, to spoil their profit margins.

Your groveling worship at the altar of mammon is not returned by the pitiless lack of gratitude from the Wall Street casino.

The problem has never been producing or acquiring energy. The problem has always been, developing and constructing an infrastructure for efficient, low cost distribution and storage until needed.

The new tech described in this article is another well-deserved nail in the coffin of the Carbon Lobby.
Thorium Boy
1 / 5 (2) Mar 02, 2018
It'll never see the light of day.
Eikka
1 / 5 (2) Mar 02, 2018
The problem has never been producing or acquiring energy. The problem has always been, developing and constructing an infrastructure for efficient, low cost distribution and storage until needed.


Indeed.

For example, the process of making the graphene involves burning natural gas over a catalyst made of copper, itself refined and made using fossil fuels for their abundance and cheapness and ease of transport.

That's why, using the technology -as such- is not a nail in anyone's coffin because it is still fundamentally dependent on the fossil fuels industry. Otherwise it wouldn't be cheap or efficient, with all the necessary conversion steps to produce the materials out of sources like wind energy and atmospheric CO2.
rrwillsj
1 / 5 (1) Mar 02, 2018
Eikka, I must reluctantly agree with your assessment of current processes for manufacturing these devices.

However, I am hoping that Thorium Boy's prediction will not occur. I hope that continuous development of Aqueous Hybrid Capacitors will allow the production to gradually bootstrap it's way to low-cost efficiency.

Even if the route forward turns out to be a 'Drunkard's Walk'.
gkam
1 / 5 (1) Mar 03, 2018
Deniers can see the end of fossil fuels with these new developments in storage.
MR166
not rated yet Mar 03, 2018
I really doubt that fossil energy companies will be able to stop the widespread use of energy storage. More than likely they will be the ones selling and installing it. It just comes down to cost/Joule for the entire system cradle to grave. Applications that need high power to weight and volume will be the last to stop using fossil.
Eikka
5 / 5 (1) Mar 04, 2018
Besides. Everyone ranting and raving about how this device is yet another "nail in the coffin", overlook the obvious:

Any device that charges in "20-30 seconds" from USB doesn't hold more energy than a Watt-minute or so.

And indeed, had you actually read the article, it says it's a pseudocapacitor. The energy density isn't anywhere near useful for long term energy storage.

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