Researchers have devised the world's first energy-storage membrane

Sep 29, 2011

A team from the National University of Singapore's Nanoscience and Nanotechnology Initiative (NUSNNI), led by principle investigator Dr Xie Xian Ning, has developed the world's first energy-storage membrane.

Electrical storage and its management is becoming an urgent issue due to climate change and energy shortage. Existing technologies such as and are based on complicated configurations including liquid electrolytes, and suffer from difficulties in scaling-up and high fabrication costs. There is also growing public concern and awareness of the impact of traditional energy sources on the environment, spurring a continued search for alternative, green, sustainable energy sources.

Cost-effective and environmentally-friendly

Recognising the issue, Dr Xie and his team have developed a that not only promises greater cost-effectiveness in delivering energy, but also an environmentally-friendly solution. The researchers used a polystyrene-based polymer to deposit the soft, foldable membrane that, when sandwiched between and charged by two metal plates, could store charge at 0.2 farads per square centimeter. This is well above the typical upper limit of 1 microfarad per square centimetre for a standard capacitor.

The cost involved in energy storage is also drastically reduced. With existing technologies based on liquid electrolytes, it costs about US$7 to store each farad. With the advanced energy storage membrane, the cost to store each farad falls to an impressive US$0.62. This translates to an energy cost of 10-20 watt-hour per US dollar for the membrane, as compared to just 2.5 watt-hour per US dollar for lithium ion batteries.

Dr Xie said: "Compared to rechargeable batteries and supercapacitors, the proprietary membrane allows for very simple device configuration and low fabrication cost. Moreover, the performance of the membrane surpasses those of rechargeable batteries, such as lithium ion and lead-acid batteries, and supercapacitors."

The research is supported by grants from the Singapore-MIT Alliance for Research & Technology (SMART), and National Research Foundation. Dr Xie and his team started work on the membrane early last year and took about 1.5 years to reach their current status, and have successfully filed a US patent for this novel invention.

The discovery has also gained the attention of scientific journals worldwide, and was featured in Energy & Environmental Science and highlighted by journal Nature.

Potential applications: From hybrid vehicles to solar panels and wind turbines

The membrane could be used in hybrid vehicles for instant power storage and delivery, thus improving energy efficiency and reducing carbon emission. Potentially, hybrid cars with the membrane technology could be powered by the energy stored in the membranes in conjunction with the energy provided by fuel combustion, increasing the lifespan of car batteries and cutting down on waste.

The membrane could also be integrated into solar panels and wind turbines to store and manage the electricity generated. Energy provided through these sources is prone to instability due to their dependence on natural factors. By augmenting these energy sources with the membrane, the issue of instability could potentially be negated, as surplus energy generated can be instantly stored in the membranes, and delivered for use at a stable rate at times when natural factors are insufficient, such as a lack of solar power during night-time.

Next step

The research team has demonstrated the membrane's superior performance in energy storage using prototype devices. The team is currently exploring opportunities to work with venture capitalists to commercialise the membrane. To date, several venture capitalists have expressed strong interest in the technology.

"With the advent of our novel membrane, technology will be more accessible, affordable, and producible on a large scale. It is also environmentally-friendly and could change the current status of energy technology," Dr Xie said.

Explore further: Researchers achieve 'holy grail' of battery design: A stable lithium anode

Provided by National University of Singapore

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jalmy
not rated yet Sep 29, 2011
Nice article. It actually had some real numbers for once. In general I think capacitive storage will eventually be the energy storage device left standing. It's good that we are investing in such a wide spectrum of energy devices, but seriously one good cheap plastic solar cell, and one cheap scalable super capacitor and its game over for hydrogen and batteries, and biowhatever.
JamesThomas
4 / 5 (1) Sep 29, 2011
Am I reading this correctly, or is this not the battery breakthrough we've all been waiting for?
PinkElephant
5 / 5 (1) Sep 29, 2011
Am I reading this correctly, or is this not the battery breakthrough we've all been waiting for?
Not quite yet, at least not until they provide some more information. For instance, how long does the membrane retain the charge after the electrode potential is removed, how many charge/discharge cycles does the membrane tolerate before it degrades too much, and what are the operating conditions for the membrane (temperature, humidity -- does it need to be vacuum-sealed? -- etc.)

From the article, it appears the membrane is more of a (super)capacitor material than a battery material -- i.e. quick to charge/discharge, and can store a lot of energy, but only for relatively short periods of time.

Still, even if it's only a supercapacitor (rather than a battery) breakthrough, it will be of great benefit in many applications -- of course, still depending on how practical it can be in real-world conditions.
antialias_physorg
not rated yet Sep 30, 2011
...add to that the fact that such 'supercapacitors' have the problem of dropping voltage upon discharge (while a battery retains its voltage till near the end) - which makes running anything with supercapacitors extremely convoluted (almost all electric appliances need constant voltage)
jalmy
not rated yet Sep 30, 2011
Energy density is the key point. We have a vast array of electronic devices available to tailor the end voltage, current etc, and I'm not sure what you mean by short term storage of capacitors you can get shocked by one that was unplugged a year ago. They only discharge if they have built in circuits to discarge them for safety.
PinkElephant
not rated yet Sep 30, 2011
I'm not sure what you mean by short term storage of capacitors you can get shocked by one that was unplugged a year ago. They only discharge if they have built in circuits to discarge them for safety.
Again, not much info provided in the article. But by the sound of it -- "energy-storage membrane" -- a likely interpretation is that they have a semi-permeable membrane that selectively blocks certain ions while letting others pass through. If so, it would build up a potential across the membrane, for instance, if all the positive ions of the originally-neutral electrolyte ended up on one side of the membrane while all the negative on the other. But, such a configuration is unstable: as soon as the external voltage is removed, the ions would begin to cross back across the membrane -- basically, a process of internal discharge. Of course, that's just one possible interpretation, and it may be wrong.