中文 English

Power/Performance Bits: April 21

Focus-free lens; battery separator.


Focus-free lens
Researchers from the University of Utah developed a new lens that doesn’t require focusing. They present it as an alternative to the multiple lenses common in smartphone cameras.


The new flat lens can maintain focus for objects that are about 6 meters apart from each other. It uses nanostructures patterned on a flat surface rather than bulky glass or plastic to achieve the optical properties that control the way light travels.


Traditional lenses transform parallel light waves into spherical waves that converge into a focal spot. The researchers found that waves with other shapes could provide a similar effect, increasing the number of possible lens designs.



The researchers demonstrated the new lens using infrared light and relatively low numerical aperture, which characterizes the range of angles over which the lens can accept or emit light. They plan to extend the lens to larger numerical apertures and to use it with the full visible light spectrum. Work to ensure that the lenses could be mass manufactured is also needed before they could be commercialized.



Battery separator

The team’s work focused on the separator that serves as a barrier between the anode and cathode, so that it slows down the flow of energy (and thus heat) that builds up inside the battery when it short circuits.

“We’re not trying to stop battery failure from happening. We’re making it much safer so that when it does fail, the battery doesn’t catastrophically catch on fire or explode,” said Matthew Gonzalez, a Ph.D. student at UC San Diego.

In lithium metal batteries, needle-like dendrites can form and pierce the separator, causing a short circuit that can lead to the battery no longer working and, in extreme cases, fires.


To make the new separator, a slurry of polymer gel is casted onto a glass slide, followed by a layer of carbon nanotubes. (Credit: David Baillot/UC San Diego Jacobs School of Engineering)


In tests, lithium metal batteries equipped with the new separator showed signs of gradual failure over 20 to 30 cycles. Batteries with a normal, slightly thicker separator experienced abrupt failure in a single cycle.



Leave a Reply

(Note: This name will be displayed publicly)