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Li-ion Batteries with Nanotube Anodes Charge Phones in Ten Minutes

Charge and discharge rates are 16 times faster than coventional Li-ion batteries

2 min read
Li-ion Batteries with Nanotube Anodes Charge Phones in Ten Minutes
Photo: University of California, Riverside

The introduction of portable electronics pretty much spelled the end for graphite as the anode material for lithium-ion (Li-ion) batteries. We could no longer get through a day of regular usage of some smart phones without having to recharge their batteries.

The hope had been that silicon could replace graphite. Silicon anode material has a theoretical capacity (i.e., Li storage capability) of 4000 milliamp-hours per gram (mAh/g). This represented an enormous increase over graphite that was coming in at 372mAh/g. However, there was a big problem: silicon would start to crack after a relatively small number of charge/discharge cycles, rendering the material useless.

As a result, the big push has been to develop nanomaterial solutions that would support silicon as an anode material by preventing it from cracking under repeated charge/discharge cycles and still maintain its high storage capability.

We’ve covered a variety of attempts to apply nanostructured silicon to the anodes of Li-ion batteries over the years,  but now researchers at the University of California (UC) Riverside have taken a little twist on this line of work and instead of supplying nanostructures to silicon, they have dispersed silicon particles onto the nanostructures. They claim that anodes using this architecture allow for a Li-ion battery used in portable electronics to be recharged in 10 minutes.

In research published in the journal Small, the UC Riverside researchers have developed a three-dimensional, cone-shaped cluster of carbon nanotubes that have silicon scattered on them that can serve as anodes for Li-ion batteries. The resulting anodes enable a Li-ion battery to have a capacity of 1954 mAh/g, which is five times more than Li-ion batteries with traditional graphite-based anodes.

The researchers believe that the high-rate at which the batteries can be recharged is the result of the seamless connection that exists between the graphene-covered copper foil that serves as the substrate for the anodes and the carbon nanotubes. This design improves the active material-current collector contact integrity, which in turn facilitates the charge and thermal transfer in the electrode system. The researchers estimate that the charge and discharge rates for this battery are nearly 16 times faster than conventionally used graphite-based anodes.

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Deep Learning Could Bring the Concert Experience Home

The century-old quest for truly realistic sound production is finally paying off

12 min read
Image containing multiple aspects such as instruments and left and right open hands.
Stuart Bradford

Now that recorded sound has become ubiquitous, we hardly think about it. From our smartphones, smart speakers, TVs, radios, disc players, and car sound systems, it’s an enduring and enjoyable presence in our lives. In 2017, a survey by the polling firm Nielsen suggested that some 90 percent of the U.S. population listens to music regularly and that, on average, they do so 32 hours per week.

Behind this free-flowing pleasure are enormous industries applying technology to the long-standing goal of reproducing sound with the greatest possible realism. From Edison’s phonograph and the horn speakers of the 1880s, successive generations of engineers in pursuit of this ideal invented and exploited countless technologies: triode vacuum tubes, dynamic loudspeakers, magnetic phonograph cartridges, solid-state amplifier circuits in scores of different topologies, electrostatic speakers, optical discs, stereo, and surround sound. And over the past five decades, digital technologies, like audio compression and streaming, have transformed the music industry.

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