Semiliquid battery competitive with both Li-ion batteries and supercapacitors

May 22, 2015 by Lisa Zyga feature
The new battery (pink star), in comparison with other energy-storage devices, exhibits a very high power density and a reasonably good energy density. Credit: Ding, et al. ©2015 American Chemical Society

(Phys.org)—A new semiliquid battery developed by researchers at The University of Texas at Austin has exhibited encouraging early results, encompassing many of the features desired in a state-of-the-art energy-storage device. In particular, the new battery has a working voltage similar to that of a lithium-ion battery, a power density comparable to that of a supercapacitor, and it can maintain its good performance even when being charged and discharged at very high rates.

The researchers, led by Assistant Professor Guihua Yu, along with Yu Ding and Yu Zhao, at UT Austin, have published their paper on the new membrane-free, semiliquid in a recent issue of Nano Letters. The researchers explain that the battery is considered "semiliquid" because it uses a liquid ferrocene electrolyte, a liquid cathode, and a solid lithium anode.

"The greatest significance of our work is that we have designed a semiliquid battery based on a new chemistry," Yu told Phys.org. "The battery shows excellent rate capability that can be fully charged or discharged almost within one minute while maintaining good energy efficiency and reasonable energy density, representing a promising prototype liquid redox battery with both high energy density and for energy storage."

The battery is designed for applications in two of the biggest areas of : hybrid electric vehicles and energy storage for renewable energy resources.

As shown in the figure above, the battery's high power density (1400 W/L) and good energy density (40 Wh/L) put it in the uniquely favorable position of combining a power density that is as high as that of current supercapacitors with an energy density on par with those of state-of-the-art redox flow batteries and lead-acid batteries, though slightly lower than that of lithium-ion batteries. This combination is especially attractive for electric vehicles, where the power density corresponds to top speed and the energy density to the vehicle's range per charge.

The researchers also report in their paper that the has a high capacity (137 mAh/g) and a high capacity retention of 80% for 500 cycles.

The structure and working principle of the new ferrocene-based, membrane-free semiliquid battery, along with an experimental demonstration showing that the battery’s power output can light a 9 x 9 LED array. Credit: Ding, et al. ©2015 American Chemical Society

The researchers attribute the battery's good performance in large part to its liquid electrode design that enables its high rate capability, which is basically a measure of how fast the battery operates. The ions can move through the liquid battery very rapidly compared to in a solid battery, and the redox reactions in which the electrons are transferred between electrodes also occur at very high rates in this particular battery. For comparison, the values used to measure these rates (the diffusion coefficient and the reaction constant) are orders of magnitude greater in the new battery than in most conventional flow batteries.

Although the battery looks very promising so far, the researchers note that more work still needs to be done, in particular regarding the lithium anode.

"The potential weakness of this battery is the lithium anode in terms of long-term stability and safety," Yu said. "More advanced lithium anode protection is required to fully suppress self-discharge. We suppose that other metals like zinc and magnesium may also function as the anode for such a battery as long as the electrolyte compatibility is resolved. We also expect that other organometallic compounds with multi-valence-state metal centers (redox centers) may also function as the anode, which eventually would make the battery fully liquid."

In the future, the researchers plan to test the long-term durability of the battery, especially its lithium anode, under realistic operating conditions. In addition, the researchers want to find a way to increase the solubility of ferrocene in order to further increase the to compete with current lithium-ion batteries while maintaining its very high power density.

Explore further: Battery development may extend range of electric cars

More information: Yu Ding, et al. "A Membrane-Free Ferrocene-Based High-Rate Semiliquid Battery." Nano Letters. DOI: 10.1021/acs.nanolett.5b01224

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16 comments

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gkam
2.7 / 5 (10) May 22, 2015
This can be a Golden Age of Renewables, with the plethora of advancing technologies. In a few years, we will wonder why we were stuck in the Age of Filthy Fuels.
MR166
5 / 5 (5) May 22, 2015
80% capacity retention after 500 cycles is not that impressive. Hopefully this can be improved upon.
tear88
3.6 / 5 (9) May 22, 2015
I didn't even bother to read the article. Seems like there's another one every day touting a wonderful advance in technology. It's like the boy who cried wolf. I am fascinated by the science behind such research, but I no longer have any expectations that I'll ever see them applied to real world products.

Call me when I can buy them at Home Depot.
Lischyn
5 / 5 (4) May 22, 2015
tear88, I agree with you.

But the researchers need to keep hammering away at this technology. They also need press exposure to keep the funds coming. Someday, with any luck, someone will hit on a winner technology.

This whole electrical storage technology, even after a 100yrs, is still in it's infancy. We need an energy density 1000;s of times greater than we have now.
jeremy_h
4.7 / 5 (3) May 22, 2015
Agreed with both tear88 and Lischyn.

Reminds me of the sodium-sulfur battery.
It was invented in the 60s and researched since the 80s, it even had government support but we still don't see it in real world applications after 50 years.
TheGhostofOtto1923
2.5 / 5 (8) May 22, 2015
This can be a Golden Age of Renewables, with the plethora of advancing technologies. In a few years, we will wonder why we were stuck in the Age of Filthy Fuels.
Or we can just buy t shirts.
http://www.handsa...-shirts/

I am sure they are biodegradable.
Eikka
3 / 5 (4) May 22, 2015
Agreed with both tear88 and Lischyn.

Reminds me of the sodium-sulfur battery.
It was invented in the 60s and researched since the 80s, it even had government support but we still don't see it in real world applications after 50 years.


The reason why you don't see them is because they're operating at 350 C temperatures, so you can't put one in a laptop of a cellphone. They've been tried in electric cars and grid storage though, and they work. The only issue is cost.
jeremy_h
5 / 5 (1) May 22, 2015
I already knew that, my point was that there is always a trick in battery technology that hinders them from reaching the market, be it cost, energy density or otherwise.
Eikka
4 / 5 (4) May 22, 2015
I already knew that, my point was that there is always a trick in battery technology that hinders them from reaching the market, be it cost, energy density or otherwise.


But sodium-sulfur batteries have reached the market. They're just not widely visible because they're such a niche market. Ford for example used them in electric cars in Europe in the 90's, which admittedly did end up a failure.

There's one huge sodium-sulfur battery in Presidio, Texas, manufactured by NGK-Locke. It's being used for grid load balancing and power quality management. At the time of building it wasn't the cheapest battery in today's terms, but the costs are coming down.
DonGateley
5 / 5 (2) May 22, 2015
This nut is not going to be adequately cracked without many independent efforts. Good on ya, guys, for yours. Keep them coming.
jeremy_h
not rated yet May 23, 2015
There's one huge sodium-sulfur battery in Presidio, Texas, manufactured by NGK-Locke. It's being used for grid load balancing and power quality management. At the time of building it wasn't the cheapest battery in today's terms, but the costs are coming down.


Ok, I wasn't aware they were used there. But my point was for all batteries in general (Na-S was just an example, I admit it was not the best) and when you look at every chemistry (and they are numerous), there is always something that restrain its widespread use.

An another example may be lithium-sulfur which suffers from poor kinetics because the formation of the polysulfide intermediate is a rather sluggish process and they react with the carbonate solvent.
Sodium-ion suffers from swelling of the graphite electrode when the sodium atom intercalates between two graphene sheets, reducing the number of cycles.

Finding solutions take time and money to do so and funding can disappear quickly.
EWH
not rated yet May 23, 2015
The Stanford aluminum ion battery: http://phys.org/n...ive.html has unlimited cycle life, cheap materials, safe operation, supercap-like charge rates, but about 1/4 the energy density of lithium-ion. This is already good enough for many applications where energy density isn't as important as quick recharging and long service life. The energy density may increase quite a bit in the future, particularly if magnesium can be used in place of aluminum.
jeremy_h
5 / 5 (1) May 23, 2015
cheap materials

This battery uses an ionic liquid as an electrolyte, most of those solvents are toxic and all are expensive at best (they are difficult to synthesize and need extreme purity).
They also use anhydrous aluminium chloride which is toxic, a pollutant, a strong Lewis acid (read corrosive) and hygroscopic (picks up moisture from the air).

supercap-like charge rates

It gets that from the graphite electrode used, which has a very big surface area and is very thin. However try to scale this up and the electrode will become thicker and ions will need to move farther into the electrode, slowing things down.

if magnesium can be used in place of aluminum

Aluminium moves through the electrolyte by complexing with aluminium chloride forming a mobile chloroaluminate ion that goes to the counter-electrode.
The trick here is that such magnesium ion is rare and exist only with specific counter-ion that you will not encounter in a regular battery
jackofshadows
not rated yet May 23, 2015
Hmm... DARPA has some vehicle-mounted laser systems that can really use this. [The drone is in the works. ] Just saying.
KBK
5 / 5 (1) May 24, 2015
tear88, I agree with you.

But the researchers need to keep hammering away at this technology. They also need press exposure to keep the funds coming. Someday, with any luck, someone will hit on a winner technology.

This whole electrical storage technology, even after a 100yrs, is still in it's infancy. We need an energy density 1000;s of times greater than we have now.


To get to higher energy densities, we'll need to put something akin to the the power of nuclear technologies in the hands of the 'average person', and I can tell you, that unless we stop killing each other, or having moments of being uncontrollably enraged, that is not about to happen.

Higher energy density also means potential for misuse ....basically, highly advanced weaponry, in the hands of every angst filled teenager.

Not happening. It isn't the technology, it is the people that would have it in their hands-that is the problem.
Eikka
5 / 5 (2) May 27, 2015
there is always something that restrain its widespread use.


That's rather an issue of marketing and expectations. It's perfectly obvious that you won't see e.g. a molten salt battery in cars and homes for the same reason your cellphone doesn't have a hydrogen fuel cell. That doesnt' mean the technologies won't be widely used where applicable.

Not every new technology has to be a panacea to be successful.

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