Category Physics

100k Cycles and Beyond: Extraordinary Cycle Stability for MnO2 Nanowires Imparted by a Gel Electrolyte

Researchers have invented nanowire-based battery material that can be recharged hundreds of thousands of times, moving us closer to a battery that would never require replacement. The breakthrough work could lead to commercial batteries with greatly lengthened lifespans for computers, smartphones, appliances, cars and spacecraft.

Scientists have long sought to use nanowires in batteries. They’re highly conductive and feature a large surface area for the storage and transfer of electrons. However, these filaments are extremely fragile and don’t hold up well to repeated discharging and recharging, or cycling...

Geometric stabilization of polar NdNiO3 via octahedral tilt engineering.

Engineers and Physicists have created an entirely new material in which completely contradictory properties can coexist.”Polar metals should not be possible,” says Chang-Beom Eom, the professor of materials science and engineering. Undeterred by the laws of the universe, Eom et al created a compound that is a scientific oxymoron. Through a new synthesis approach supported by computational modeling, the group made a crystal with multiple personalities: part polar, part metallic.

Metals conduct electricity because electrons flow freely throughout them. Polar materials, by contrast, impede the free flow of electrons and work as electrical insulators. First, they separated the polar and metallic parts of the crystal...

3-D artistic depiction of multiple Quantum Cascade Lasers integrated above silicon waveguides. Credit: Alexander Spott

The advance will have many uses including chemical bond spectroscopy and gas sensing, to astronomy and free-space communications. Integrating lasers directly on silicon chips is challenging, but it is much more efficient and compact than coupling external laser light to the chips. The indirect bandgap of silicon makes it difficult to build a laser out of silicon, but diode lasers can be built with III-V materials such as InP or GaAs. By directly bonding an III-V layer on top of the silicon wafer and then using the III-V layers to generate gain for the laser, this same group has integrated a multiple quantum well laser on silicon that operates at 2 µm...