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Elastic wire-shaped lithium-ion batteries with high electrochemical performance

13 June 2014

Wire
Structure of the flexible wire-shaped lithium-ion battery. The aligned MWCNT/LTO and MWCNT/LMO composite yarns are paired as the anode and cathode, respectively. Ren et al. Click to enlarge.

A team led by Huisheng Peng from Fudan University in Shanghai has developed a stretchable wire-shaped lithium-ion battery produced from two aligned multi-walled carbon nanotube/lithium oxide composite yarns as the anode and cathode without extra current collectors and binders. As the researchers report in the journal Angewandte Chemie, they were able to weave their batteries into light, flexible, elastic, and safe textile batteries with a high energy density.

The two composite yarns can be well paired to obtain a safe battery with energy densities of 27 Wh kg−1 or 17.7 mWh cm−3 and power densities of 880 W kg−1 or 0.56 W cm−3, which are an order of magnitude higher than the densities reported for lithium thin-film batteries. These wire-shaped batteries are flexible and light, and 97% of their capacity was maintained after 1,000 bending cycles.

Ren
Capacity retention and coulombic efficiency of the wire-shaped full cell with a length of 1 cm after 100 charge–discharge cycles at 0.05 mA. Ren et al. Click to enlarge.

They are also very elastic as they are based on a modified spring structure; 84% of the capacity was maintained after stretching for 200 cycles at a strain of 100%. These novel wire-shaped batteries have been woven into lightweight, flexible, and stretchable battery textiles, which reveals possible large-scale applications.

Previous methods for producing wire-shaped electrochemical supercapacitors by twisting two fiber electrodes together resulted in systems with inferior performance that prevented them from being brought to the market.

Lithium-ion batteries can attain significantly higher energy density, but have not previously been produced in wire form. In addition to other barriers, the safety problems associated with lithium-ion batteries are a factor. The source of the safety problem is dendritic lithium, which can form during over-charging, “growing” out of the anode and causing a short circuit. This can cause the battery to ignite. This seems especially critical for wire-shaped batteries that can be stretched, twisted, and bent during use.

The Fudan team succeeded in producing wire-shaped lithium ion batteries that have a high energy density and are also safe. Their success results from the special structure as well as the materials used.

The anode and cathode are two fibers made of parallel multi-walled carbon nanotubes that contain either lithium titanium oxide (LTO) or lithium manganese oxide (LMO) particles, respectively. Because of the aligned nanostructure and high electrical conductivity, no current collector and binders are required during the fabrication.

When the battery is charging, lithium ions are transferred from the LMO lattice to the electrolyte and then into the LTO lattice of the anode. The reverse process occurs as the battery is being discharged. Because the Li insertion takes place at ~1.5 V (vs. Li/Li+) for the applied LTO composite electrode, the chance of short circuit caused by dendritic lithium would be small and therefore the batteries are safe.

The parallel arrangements of continuous carbon nanotubes hold the nanoparticles; they are also efficient pathways for charge transport and serve as current collectors. The two electrode yarns are arranged in parallel, separated by a layer of insulator, and enclosed in a heat-shrinkable tube. To make the wires elastic, they can be wrapped around an elastic fiber such as polydimethylsiloxane and coated with a thin-layer gel electrolyte. Neither repeated stretching to twice its original length nor thousands of deformation cycles reduces the battery capacity.

The wire-shaped batteries can be spun into long fibers and woven into a fabric that can be incorporated into textiles.

Resources

  • Jing Ren, Ye Zhang, Wenyu Bai, Xuli Chen, Zhitao Zhang, Xin Fang, Wei Weng, Dr. Yonggang Wang, and Prof. Huisheng Peng (2014) “Elastic and Wearable Wire-Shaped Lithium-Ion Battery with High Electrochemical Performance,” Angew. Chem. Int. Ed.. doi: 10.1002/anie.201402388

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Comments

So, is it better or worst, the article seam confusing. Will we see it on a commercial basis ? It'S been the 300th article about an improved battery but as of yet batteries are underperforming only adopted by a very small percentge of drivers and also they are subsidized to say the least, what would it be without so much goverment money.

Please bring hydrogen instead, anyway even with improved batteries we can fit them in hybrid hydrogen cars where the fuelcell is also a range extender.

I guess that all these subsidies and battery project and the ignorance of the benefit of hydrogen are because big oïl is giving money on the black markets to everyone that put this money in overseas fiscal paradise, it's impossible without that to see so much petrol high price, limp batteries and no efficient powerful hydrogen gas powering everything.

All these studies are related to the black money given by big oïl to scientifics, politicians, journalists, bloggers, car manufacturers executive, wall street dealers, investors, bankers, Greenpeace, military, syndicats, 10% is directly invested in black pr against hydrogen and another percentage is invested toward battery just to satisfy the public opinion because they know that it won't replace petrol never.

The purpose of Big Business in our Capitalist Economy is not to compete in the marketplace; but, to do anything to control the marketplace. The oil companies have done that for a hundred plus years, ever since John D. Rockefeller's Standard Oil Company fixed the market price of illuminating oil in the early 1900s. Currently their control of the American economy is accomplished mostly by campaign contributions and favors to Congressional and State politicians. This is accomplished through lobbying firms where money goes one way to the politicians from industry and money is returned back to the industries in the form of subsidies or favorable legislation.

Big Oil's biggest fear; a politician who can't be bought and "True Open Source Competition."

I forgot that June 13th was also National Wild Speculation Day. Hope all had a happy Friday imagining conspiracies that you cannot prove but must certainly be true.

At my house we just cooked some burgers and watched a little futbol. Bummer.

@And Bri, Please check your facts, your meds and leave the tin foil hat at the door.

Big Oil/Gas is the main provider of Hydrogen. They are the ones actually pushing for it.

Your meds need to be adjusted and the tin foil hat doesn't really do any good. Try copper mesh with a very tight weave instead.

Indeed, lace that hat with lithium. You're going to miss all that big oil in Iraq, next you'll blame the Bushies for not keeping any.

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