Cheap High Performance Li-ion Batteries

Li-ion batteries (LIBs) are one of the most used batteries that support modern ITC society, including smartphones and EVs. LIBs are repeatedly charged and discharged by Li-ions passing back and forth between the positive and negative electrodes, with the Li-ion electrolyte acting as a passageway for the ions.

Normally, organic electrolytes such as liquid ethylene carbonate (EC) and their gels have been used as the Li-ion electrolyte due to their voltage resistance and ionic conductivity. However, as liquids and gels are flammable, a switch to safer polymeric solid electrolytes is preferable.

Polymeric solid electrolytes such as polyethylene glycol (PEG) have been proposed as impact-resistant Li-ion electrolytes. However, PEG-based polymer electrolytes crystallize near room temperature, resulting in a significant drop in Li-ion conductivity to around 10-6 S/cm at room temperature. To solve this problem, a research group has invented a new type of polymeric solid electrolyte by combining a porous polymer membrane with several micron pores and a photo-cross-linkable polyethylene glycol PEG-based polymer electrolyte.

This polymeric solid electrolyte not only shows high performance as an electrolyte but is also expected to be effective in deterring the formation of Li dendrites (dendritic crystals), which can cause ignition, due to the inclusion of a porous membrane. Through the realization of safe, high-performance LIBs, this achievement will contribute to the realization of a sustainable energy supply, which is the seventh goal of the SDGs.

Source: https://www.tohoku.ac.jp/

How To Create Electricity From Heat

A University of Maryland-led team of researchers has created a heat-to-electricity device that runs on ions and which could someday harness the body’s heat to provide energy.

Led by UMD researchers Liangbing Hu, Robert Briber and Tian Li of the department of materials science, and Siddhartha Das of mechanical engineering, the team transformed a piece of wood into a flexible membrane that generates energy from the same type of electric current (ions) that the human body runs on. This energy is generated using charged channel walls and other unique properties of the wood’s natural nanostructures. With this new wood-based technology, they can use a small temperature differential to efficiently generate ionic voltage, as demonstrated in a paper published in the journal Nature Materials.

If you’ve ever been outside during a lightning storm, you’ve seen that generating charge between two very different temperatures is easy. But for small temperature differences, it is more difficult. However, the team says they have succesfully tackled this challenge.  Hu said they now have “demonstrated their proof-of-concept device, to harvest low-grade heat using nanoionic behavior of processed wood nanostructures”.

Trees grow channels that move water between the roots and the leaves. These are made up of fractally-smaller channels, and at the level of a single cell, channels just nanometers or less across. The team has harnessed these channels to regulate ions.

The researchers used basswood, which is a fast-growing tree with low environmental impact. They treated the wood and removed two components lignin, that makes the wood brown and adds strength, and hemicellulose, which winds around the layers of cells binding them together. This gives the remaining cellulose its signature flexibility.  This process also converts the structure of the cellulose from type I to type II which is a key to enhancing ion conductivity.

A membrane, made of a thin slice of wood, was bordered by platinum electrodes, with sodium-based electrolyte infiltrated into the cellulose. The regulate the ion flow inside the tiny channels and generate electrical signal. “The charged channel walls can establish an electrical field that appears on the nanofibers and thus help effectively regulate ion movement under a thermal gradient,” said Tian Li, first author of the paper.

Source: https://www.umdrightnow.umd.edu/

Plane Propelled Via Ionic Wind

MIT engineers fly first-ever plane with no moving parts. The silent, lightweight aircraft doesn’t depend on fossil fuels or batteries. Since the first airplane took flight over 100 years ago, virtually every aircraft in the sky has flown with the help of moving parts such as propellers, turbine blades, and fans, which are powered by the combustion of fossil fuels or by battery packs that produce a persistent, whining buzz.
Now MIT engineers have built and flown the first-ever plane with no moving parts. Instead of propellers or turbines, the light aircraft is powered by an “ionic wind” — a silent but mighty flow of ions that is produced aboard the plane, and that generates enough thrust to propel the plane over a sustained, steady flight.Unlike turbine-powered planes, the aircraft does not depend on fossil fuels to fly. And unlike propeller-driven drones, the new design is completely silent.
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A new MIT plane is propelled via ionic wind. Batteries in the fuselage (tan compartment in front of plane) supply voltage to electrodes (blue/white horizontal lines) strung along the length of the plane, generating a wind of ions that propels the plane forward.

This is the first-ever sustained flight of a plane with no moving parts in the propulsion system,” says Steven Barrett, associate professor of aeronautics and astronautics at MIT. “This has potentially opened new and unexplored possibilities for aircraft which are quieter, mechanically simpler, and do not emit combustion emissions.”
He expects that in the near-term, such ion wind propulsion systems could be used to fly less noisy drones. Further out, he envisions ion propulsion paired with more conventional combustion systems to create more fuel-efficient, hybrid passenger planes and other large aircraft.

Source: http://news.mit.edu/