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Gizmorama - June 21, 2017

Good Morning,


Wireless charging seems to be the big "must-have" feature for every electric device. Now, a breakthrough has been made with electric vehicles! I know I'm charged up!

Learn about this and more interesting stories from the scientific community in today's issue.

Until Next Time,
Erin


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* Liquified gas electrolytes power new lower-temperature battery *

Scientists at the University of California, San Diego have developed new electrolytes capable of powering batteries at temperatures as low as negative 80 degrees Celsius.

The technology could help make lithium ion batteries safer and more efficient, as well as boost the range of electric vehicles during cold winter months. The new batteries could also power vehicles and instruments operating in extreme cold, like space rovers, satellites and high-alitiude weather baloons.

The electrolytes are composed of liquefied gas solvents. Many gases require extreme pressure to liquify. Gases that liquify at moderate pressures are less apt to freeze.

To create their battery's electrolyte, researchers liquified fluoromethane gas. For the capacitor electrolyte, scientists liquified difluoromethane gas.

"Better batteries are needed to make electric cars with improved performance-to-cost ratios," Shirley Meng, a nanoengineering professor at UCSD, said in a news release. "And once the temperature range for batteries, ultra-capacitors and their hybrids is widened, these electrochemical energy storage technologies can be adopted in many more emerging markets."

Electrolytes have been identified as one the main barriers inhibiting efficiency improvements in lithium ion battery technology. Many researchers have abandoned liquid electrolytes in favor of battery model using solid state electrolytes.

"We have taken the opposite, albeit risky, approach and explored the use of gas based electrolytes," said Cyrus Rustomji, a postdoctoral researcher at UCSD.

Aside from efficiency, one of the biggest problems with lithium ion batteries is their tendency to catch on fire. When electrolytes overheat, they can trigger a chemical chain reaction that generates extreme temperatures inside the battery. The liquified gas electrolytes limit this risk, ensuring internal temperatures remain moderate.

The electrolyte works like an emergency off switch.

"As soon as the battery gets too hot, it shuts down. But as it cools back down, it starts working again," Rustomji said. "That's uncommon in conventional batteries."

Additionally, the electrolyte's unique chemical makeup prevent the build up of lithium metal on the battery's electrodes. Inside commercial lithium ion batteries, lithium deposits called dendrites can grow like tiny stalagmites, eventually piercing battery components and causing the circuitry to short out.

Researchers hope to continue improving their battery's efficiency and low-temperature abilities. They detailed their most recent electrolyte breakthrough in the journal Science.



*-- Scientists inch closer to wirelessly charging moving electric vehicles --*

Stanford scientists have made a breakthrough in the quest to wirelessly charge a moving electric vehicle.

In 2007, MIT researchers wirelessly charged a stationary object a few feet away. In recent experiments, scientists were able to wirelessly transmit electricity to a moving LED lightbulb using a similar setup.

If researchers can find a way to charge electric vehicles while on the go, it would remove the cars' biggest drawbacks -- their limited range and lengthy charging times.

"In theory, one could drive for an unlimited amount of time without having to stop to recharge," lead researcher Shanhui Fan, a professor of electrical engineering at Stanford, said in a news release. "The hope is that you'll be able to charge your electric car while you're driving down the highway. A coil in the bottom of the vehicle could receive electricity from a series of coils connected to an electric current embedded in the road."

Wireless charging relies on a electromagnetic phenomenon known as magnetic resonance coupling. Electricity rotating around a tire can form an oscillating magnetic field. This push and pull can excite electrons in a nearby coil of wires, triggering a flow of electricity.

But in order to keep a continuous flow of electricity, the sets of coils must be manually tuned to maintain the resonant frequency as they move.

Stanford scientists worked around the problem by swapping out the transmitter's radio-frequency source and installing a voltage amplifier and feedback resistor. The duo can automatically calculate the proper frequency as the distance between the coils changes.

Researchers described their breakthrough in the journal Nature.

"Adding the amplifier allows power to be very efficiently transferred across most of the three-foot range and despite the changing orientation of the receiving coil," said lead study author Sid Assawaworrarit, a Stanford grad student. "This eliminates the need for automatic and continuous tuning of any aspect of the circuits."

The team of scientists used a relatively inefficient off-the-shelf amplifier. A custom amp could boost the transmitters efficiency. And research suggests further tweaks could boost the amount of electricity the technology can transmit.

"We can rethink how to deliver electricity not only to our cars, but to smaller devices on or in our bodies," Fan said. "For anything that could benefit from dynamic, wireless charging, this is potentially very important."

***

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