Posts Tagged ‘Batteries’

Making better batteries with metal oxide & graphene composites

This paper was one of the top cited articles in the journal ACS Nano in 2010. Learn how PNNL and Princeton scientists create better materials for batteries, materials that assemble on their own into durable nanocomposites.

How Batteries Grow Old

Preliminary results presented at the AVS 57th International Symposium & Exhibition, taking place this week at the Albuquerque Convention Center in New Mexico, suggest that the irreversible changes inside a dead battery start at the nanoscale.

Yann Guezennec and Giorgio Rizzoni of OSU developed new experimental facilities and procedures to charge and discharge commercially-available Li-ion batteries thousands of times over many months in a variety of conditions designed to mimic how these laptop battery such as dell Inspiron E1705 battery and Toshiba Tecra 9100 Battery are actually used by hybrid and all-electric vehicles. Some of the batteries were run in hot temperatures like those in Arizona; others in colder conditions similar to those in Alaska.

To understand the results of this testing, Bharat Bhushan, Suresh Babu, and Lei Raymond Cao studied the materials inside of the batteries to help determine how this aging manifests itself in the structure of the electrode materials.

When the batteries died, the scientists dissected them and used a technique called infrared thermal imaging to search for problem areas in each electrode, a 1.5-meter-long strip of metal tape coated with oxide and rolled up like a jelly roll. They then took a closer look at these problem areas using a variety of techniques with different length scale resolutions (e.g. scanning electron microscopy, atomic force microscope, scanning spreading resistance microscopy, Kelvin probe microscopy, transmission electron microscopy) and discovered that the finely-structured nanomaterials on these electrodes that allow the battery rapidly charge and discharge had coarsened in size.

Additional studies of the aged batteries, using neutron depth profiling, revealed that a fraction of the lithium that is responsible, in ion form, for shuttling electric charge between electrodes during charging and discharging, was no longer available for charge transfer, but was irreversibly lost from the cathode to the anode.

“We can clearly see that an aged sample versus and unaged sample has much lower lithium concentration in the cathode,” said Rizzoni, director of the Center for Automotive Research at OSU. “It has essentially combined with anode material in an irreversible way.”

This research is being performed by Center for Automotive Research at OSU in collaboration with Oak Ridge National Laboratory and the National Institute of Standards Technology.

The researchers suspect, but cannot yet prove, that the coarsening of the cathode may be behind this loss of lithium. If this theory turns out to be correct, it could point battery manufacturers in the right direction for making durable batteries with longer lifetimes.

Electric Automobile Batteries

An entirely new type of nanomaterial developed at Rensselaer Polytechnic Institute could enable the next generation of high-power rechargeable lithium (Li)-ion batteries for electric automobiles, as well as batteries for laptop computers, mobile phones, and other portable devices.
The new material, dubbed a “nanoscoop” because its shape resembles a cone with a scoop of ice cream on top, can withstand extremely high rates of charge and discharge that would cause conventional electrodes used in today’s Li-ion batteries to rapidly deteriorate and fail. The nanoscoop’s success lies in its unique material composition, structure, and size.

The Rensselaer research team, led by Professor Nikhil Koratkar, demonstrated how a nanoscoop electrode could be charged and discharged at a rate 40 to 60 times faster than conventional battery anodes, while maintaining a comparable energy density. This stellar performance, which was achieved over 100 continuous charge/discharge cycles, has the team confident that their new technology holds significant potential for the design and realization of high-power, high-capacity Li-ion rechargeable batteries.

“Charging my laptop or cell phone in a few minutes, rather than an hour, sounds pretty good to me,” said Koratkar, a professor in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer. “By using our nanoscoops as the anode architecture for Li-ion rechargeable Laptop Battery such as Sony PCGA-BP2S battery and Sony VGP-BPS2 battery, this is a very real prospect. Moreover, this technology could potentially be ramped up to suit the demanding needs of batteries for electric automobiles.”

Batteries for all-electric vehicles must deliver high power densities in addition to high energy densities, Koatkar said. These vehicles today use supercapacitors to perform power-intensive functions, such as starting the vehicle and rapid acceleration, in conjunction with conventional batteries that deliver high energy density for normal cruise driving and other operations. Koratkar said the invention of nanoscoops may enable these two separate systems to be combined into a single, more efficient battery unit.

Results of the study were detailed in the paper “Functionally Strain-Graded Nanoscoops for High Power Li-Ion Battery Anodes,” published Thursday by the journal Nano Letters.

The anode structure of a Li-ion battery physically grows and shrinks as the battery charges or discharges. When charging, the addition of Li ions increases the volume of the anode, while discharging has the opposite effect. These volume changes result in a buildup of stress in the anode. Too great a stress that builds up too quickly, as in the case of a battery charging or discharging at high speeds, can cause the battery to fail prematurely. This is why most batteries in today’s portable electronic devices like cell phones and laptops charge very slowly — the slow charge rate is intentional and designed to protect the battery from stress-induced damage.

The Rensselaer team’s nanoscoop, however, was engineered to withstand this buildup of stress. Made from a carbon (C) nanorod base topped with a thin layer of nanoscale aluminum (Al) and a “scoop” of nanoscale silicon (Si), the structures are flexible and able to quickly accept and discharge Li ions at extremely fast rates without sustaining significant damage. The segmented structure of the nanoscoop allows the strain to be gradually transferred from the C base to the Al layer, and finally to the Si scoop. This natural strain gradation provides for a less abrupt transition in stress across the material interfaces, leading to improved structural integrity of the electrode.

The nanoscale size of the scoop is also vital since nanostructures are less prone to cracking than bulk materials, according to Koratkar.

“Due to their nanoscale size, our nanoscoops can soak and release Li at high rates far more effectively than the macroscale anodes used in today’s Li-ion batteries,” he said. “This means our nanoscoop may be the solution to a critical problem facing auto companies and other battery manufacturers — how can you increase the power density of a battery while still keeping the energy density high?”

A limitation of the nanoscoop architecture is the relatively low total mass of the electrode, Koratkar said. To solve this, the team’s next steps are to try growing longer scoops with greater mass, or develop a method for stacking layers of nanoscoops on top of each other. Another possibility the team is exploring includes growing the nanoscoops on large flexible substrates that can be rolled or shaped to fit along the contours or chassis of the automobile.

Along with Koratkar, authors on the paper are Toh-Ming Lu, the R.P. Baker Distinguished Professor of Physics and associate director of the Center for Integrated Electronics at Rensselaer; and Rahul Krishnan, a graduate student in the Department of Materials Science and Engineering at Rensselaer.

New Lithium Batteries Could Last 10 Times Longer

The most consistent complaint I ever hear (or make) about smart phones is they eat up power like a fat kid eats candy. But a new development in how to manufacture rechargeable batteries for portable electronics could allow batteries to hold ten times more power than they do now.

Researchers at MIT found that using carbon nanotubes for one of the battery’s electrodes hold much more energy than the current breed of lithium-ion batteries. The experimental batteries use layered carbon nanotubes as the positive electrode and a lithium titanium oxide as the negative electrode. The batteries deliver power at the high-speed rates of capacitors while being able to store more energy than even the best lithium-ion batteries available today.

The carbon nanotube electrodes also proved their longevity. After 1,000 cycles of charging and discharging a test battery, there was no detectable change in the material’s performance.

That’s good news for anyone with an electric device that runs on batteries, your humble blogger included. I have to charge my Android phone each night just to get through the next day. If these batteries come to market, my little Droid Eris could last for days without a charge.

But that’s still a big if. The electrode material was produced by dipping a substrate into two different solutions, a pretty time-consuming process. One of the researchers leading the project, MIT professor of chemical engineering, Paula Hammond, says her team may have a solution. Hammond suggests that the process could be modified by spraying the alternate layers onto a moving ribbon of material, a technique now being developed in her lab.

Until then, I’m stuck charging my smart phone every night.

Australia largest laptop battery and laptop adapter supplier provide cheap laptop batteries: dell U4873 battery, dell latitude d610 battery, dell inspiron 6400 battery and so on.

Clothing power: the phone plugged into his hip pocket and can charge – cell phone charger, paper batteries – household appliances industry-hc360 HC

Recently, Stanford University, Stanford professor of material science and engineering Cui Yi (YuCui) led the team developed a paper battery less than a month later, he led one group of troops, introduction of further “clothing

Power supply

“The intention of the people who are all into the power of clothing, can carry anytime, anywhere mobile

Electronic

Equipment charge.

And paper battery similar, researchers using the “carbon nanotube ink” disseminated clothing fibers, it has the ability to grasp the charge. When the clothes to retain sufficient charge, it can be treated the jacket to charge for the laptop, with trousers for

Mobile

Charging more.

The same principle and paper battery

This fact is an extension of the concept paper battery. December 7 last year, Stanford University scientists in a report set, they have successfully coated with silver nano-materials, carbon paper into the “paper battery” may become a new light and efficient storage method. Help coating attached to the same characteristics of paper attached to it and the silver in the single-walled carbon nanotubes nanowires film. Preliminary study found that use of nanowires made of silicon cells, the efficiency is now used to power laptops and other devices lithium-ion batteries 10 times.

“This battery for hybrid electronic devices, or providing energy. Use of such batteries, electronic devices will become lighter, last longer, and may one day produce paper electronic products. Battery weight and life of the power cars and trucks in the commercial development of a major obstacle encountered. “Yi Cui said.

In this way through the fiber storage, in addition to portable electronic devices and wearable electronic devices you can use it outside, the researchers said some of the super capacitor paper can also be applied to all the energy needs of the instantaneous power equipment on. University of California, Berkeley, chemistry professor Yang Peidong expects the technology will soon be commercialized.

Solve high cost is a priority

But for the future of this new type of battery, in particular, will replace the current battery, there are different views on the industry. Harbin Institute of Technology School of Applied Chemistry Department Professor Sun Kening that the new paper battery batteries as a new concept, the use of outlook is definitely yes. However, the paper published the battery from the current methods of production point of view, the production of such paper batteries need high cost of production of carbon nanotubes, is not suitable for mass production, so its usefulness is limited. Due process and other reasons, it is not a substitute for extensive use of other types of batteries, and can not market share in a short time.

But be sure, the new batteries for laptop computers, mobile phones,

Digital

Camera and even

Car

Is an ideal drive. For example, because plasticity, such batteries can even be made into the shape of the door, with uncomparable advantages over other batteries.

Researchers most urgent task is how to reduce the cost of such batteries.