Harvard Claims Breakthrough In Anode Behavior Of Solid State Lithium Batteries

One of the biggest issues facing the solid-state lithium-based batteries we all depend upon is of the performance of the anode; the transport of lithium ions and minimization of dendrite formation are critical problems and are responsible for charge/discharge rates and cell longevity. A team of researchers at Harvard have demonstrated a method for using a so-called constriction-susceptible structure on a silicon anode material in order to promote direct metal lithium deposition, as opposed to the predominant alloying reaction. After the initial silicon-lithium alloy layer is formed, subsequent layers are pure lithium. Micrometre-scale silicon particles at the anode constrain the lithiation process (i.e. during charging) where free lithium ions are pushed by the charge current towards the anode area. Because the silicon particles are so small, there is limited surface area for alloying to occur, so direct metal plating of lithium is preferred, but crucially it happens in a very uniform manner and thus does not tend to promote the formation of damaging metal dendrites.

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Harvard SETI Project Helps ID Mystery Sound

Last month, thousands of people in New Hampshire took to social media to report an explosion in the sky that was strong enough to rattle windows. Naturally aliens were blamed by some, while cooler heads theorized it may have been a sonic boom from a military aircraft. But without any evidence, who could say?

Luckily for concerned residents, this was precisely the sort of event Harvard’s Galileo Project was designed to investigate. Officially described as a way to search for “technological signatures of Extraterrestrial Technological Civilizations (ETCs)”, the project keeps a constant watch on the sky with a collection of cameras and microphones. With their gear, the team was able to back up the anecdotal reports with with hard data.

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A Flexible Sensor That Moves With You

If you have a project in mind that requires some sort of gesture input or precise movements, it might become a nettlesome problem to tackle. Fear this obstacle no longer: a team from the Wyss Institute for Biologically Inspired Engineering at Harvard have designed a novel way to make wearable sensors that can stretch and contort with the body’s natural movements.

The way they work is ingenious. Layers of silicone are sandwiched between two lengths of silver-plated conductive fabric forming — by some approximation — a capacitance sensor. While the total surface area doesn’t change when the sensor is stretched — how capacitance sensors normally work — it does bring the two layers of fabric closer together, changing the capacitance of the band in a proportional and measurable way, with the silicone pulling the sensor back into its original shape as tension relaxes. Wires can be attached to each end of the band with adhesive and a square of thermal film, making an ideal sensor to detect the subtlest of muscle movements.

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3D Printing Metal In Mid Air

Published only 3 days before our article on how it is high time for direct metal 3D printers, the folks at Harvard have mastered 3D metal printing in midair with no support (as well as time travel apparently). Because it hardens so quickly, support isn’t necessary, and curves, sharp angles, and sophisticated shapes are possible.

The material is silver nanoparticles extruded out of a nozzle, and shortly after leaving it is blasted with a carefully programmed laser that solidifies the material. The trick is that the laser can’t focus on the tip of the nozzle or else heat transfer would solidify the ink inside the nozzle and clog it. In the video you can see the flash from the laser following slightly behind. The extrusion diameter is thinner than a hair, so don’t expect to be building large structures with this yet.

If you want big metal 3D printing, you should probably stick to the welders attached to robotic arms.

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Demonstrating Science At Harvard University

What if there was a job where you built, serviced, and prepared science demonstrations? This means showing off everything from principles of physics, to electronic theory, to chemistry and biology. Would you grab onto that job with both hands and never let go? That was my reaction when I met [Dan Rosenberg] who is a Science Lecture Demonstrator at Harvard University. He gave me a tour of the Science Center, as well as a behind the scenes look at some of the apparatus he works with and has built.

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3D Printing Lithium Ion Cells

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[Jennifer Lewis] is a Harvard Materials Scientist, and she’s recently come up with a type of Lithium Ion “Ink” that allows her to 3D print battery cells.

You might remember our recent 3D Printering article on Pastestruders, but this research certainly takes it up a few notches. The ink is made up of nano-particles of Lithium Titanium in a solution of de-ionized water and ethylene glycol. When producing the ink, small ceramic balls are added to the mixture to help break up microscopic clumps of said particles. The mixture is then spun for 24 hours, after which the larger particles and ceramic balls are removed using a series of filters. The resulting ink is a solid when unperturbed, but flows under extreme pressures!

This means a conventional 3D printer can be used, with only the addition of a high pressure dispenser unit. We guess we can’t call it a hot-end any more…  The ink is forced out of a syringe tip as small as 1 micrometer across, allowing for extremely precise patterning. In her applications she uses a set up with many nozzles, allowing for the mass printing of the anodes and cathodes in a huge array. While still in the research phase, her micro-scale battery architectures can be as small as a square millimeter, but apparently compete with industry batteries that are much larger.

And here’s the exciting part:

Although she says the initial plan is to provide tools for manufacturers, she may eventually produce a low-end printer for hobbyists.

3D Printable electronics. The future is coming!

[Thanks Keith!]