New Battery Charges Ten Times Faster than a Lithium-ion Battery

It is difficult to imagine our daily life without lithium-ion batteries. They dominate the small format battery market for portable electronic devices, and are also commonly used in electric vehicles. At the same time, lithium-ion batteries have a number of serious issues, including: a potential fire hazard and performance loss at cold temperatures; as well as a considerable environmental impact of spent battery disposal.

According to the leader of the team of researchers, Professor in the Department of Electrochemistry at St Petersburg University Oleg Levin, the chemists have been exploring redox-active nitroxyl-containing polymers as materials for electrochemical energy storage. These polymers are characterised by a high energy density and fast charging and discharging speed due to fast redox kinetics. One challenge towards the implementation of such a technology is the insufficient electrical conductivity. This impedes the charge collection even with highly conductive additives, such as carbon.

Looking for solutions to overcome this problem, the researchers from St Petersburg University synthesised a polymer based on the nickel-salen complex (NiSalen). The molecules of this metallopolymer act as a molecular wire to which energy-intensive nitroxyl pendants are attached. The molecular architecture of the material enables high capacitance performance to be achieved over a wide temperature range.

We came up with the concept of this material in 2016. At that time, we began to develop a fundamental project “Electrode materials for lithium-ion batteries based on organometallic polymers”. It was supported by a grant from the Russian Science Foundation. When studying the charge transport mechanism in this class of compounds, we discovered that there are two keys directions of development. Firstly, these compounds can be used as a protective layer to cover the main conductor cable of the battery, which would be otherwise made of traditional lithium-ion battery materials. And secondly, they can be used as an active component of electrochemical energy storage materials,‘ explains Oleg Levin.

A battery manufactured using our polymer will charge in seconds — about ten times faster than a traditional lithium-ion battery. This has already been demonstrated through a series of experiments. However, at this stage, it is still lagging behind in terms of capacity — 30 to 40% lower than in lithium-ion batteries. We are currently working to improve this indicator while maintaining the charge-discharge rate,’ says Oleg Levin.

Source: https://english.spbu.ru/

 

 

How To Connect Neurons To Electrodes Using 3D Printing

Researchers at the National Institute of Standards and Technology (NIST) have developed a new method of 3D-printing gels and other soft materials. Published in a new paper, it has the potential to create complex structures with nanometer-scale precision. Because many gels are compatible with living cells, the new method could jump-start the production of soft tiny medical devices such as drug delivery systems or flexible electrodes that can be inserted into the human body.

A standard 3D printer makes solid structures by creating sheets of material — typically plastic or rubber — and building them up layer by layer, like a lasagna, until the entire object is created.

Using a 3D printer to fabricate an object made of gel is a “bit more of a delicate cooking process,” said NIST researcher Andrei Kolmakov. In the standard method, the 3D printer chamber is filled with a soup of long-chain polymers — long groups of molecules bonded togetherdissolved in water. Then “spices” are added — special molecules that are sensitive to light. When light from the 3D printer activates those special molecules, they stitch together the chains of polymers so that they form a fluffy weblike structure. This scaffolding, still surrounded by liquid water, is the gel.

Biocompatible interface shows that hydrogels (green tubing), which can be generated by an electron or X-ray beam 3D printing process, act as artificial synapses or junctions, connecting neurons (brown) to electrodes (yellow)

Typically, modern 3D gel printers have used ultraviolet or visible laser light to initiate formation of the gel scaffolding. However, Kolmakov and his colleagues have focused their attention on a different 3D-printing technique to fabricate gels, using beams of electrons or X-rays. Because these types of radiation have a higher energy, or shorter wavelength, than ultraviolet and visible light, these beams can be more tightly focused and therefore produce gels with finer structural detail. Such detail is exactly what is needed for tissue engineering and many other medical and biological applications. Electrons and X-rays offer a second advantage: They do not require a special set of molecules to initiate the formation of gels.

But at present, the sources of this tightly focused, short-wavelength radiation — scanning electron microscopes and X-ray microscopes — can only operate in a vacuum. That’s a problem because in a vacuum the liquid in each chamber evaporates instead of forming a gel.

Kolmakov and his colleagues at NIST and at the Elettra Sincrotrone Trieste in Italy, solved the issue and demonstrated 3D gel printing in liquids by placing an ultrathin barrier — a thin sheet of silicon nitridebetween the vacuum and the liquid chamber. The thin sheet protects the liquid from evaporating (as it would ordinarily do in vacuum) but allows X-rays and electrons to penetrate into the liquid. The method enabled the team to use the 3D-printing approach to create gels with structures as small as 100 nanometers (nm) — about 1,000 times thinner than a human hair. By refining their method, the researchers expect to imprint structures on the gels as small as 50 nm, the size of a small virus.

Source: https://www.nist.gov/

Laser Method Turns Any Metal Surface Into A Bacteria Killer

Bacterial pathogens can live on surfaces for days. What if frequently touched surfaces such as doorknobs could instantly kill them offPurdue University engineers have created a laser treatment method that could potentially turn any metal surface into a rapid bacteria killer – just by giving the metal’s surface a different texture. In a study published in the journal Advanced Materials Interfaces, the researchers demonstrated that this technique allows the surface of copper to immediately kill off superbugs such as MRSA.

A laser prepares to texture the surface of copper, enhancing its antimicrobial properties

Copper has been used as an antimicrobial material for centuries. But it typically takes hours for native copper surfaces to kill off bacteria,” said Rahim Rahimi, a Purdue assistant professor of materials engineering. “We developed a one-step laser-texturing technique that effectively enhances the bacteria-killing properties of copper’s surface.”

The technique is not yet tailored to killing viruses such as the one responsible for the COVID-19 pandemic, which are much smaller than bacteria. Since publishing this work, however, Rahimi’s team has begun testing this technology on the surfaces of other metals and polymers that are used to reduce risks of bacterial growth and biofilm formation on devices such as orthopedic implants or wearable patches for chronic wounds.

Source: https://www.purdue.edu/

Electric 3D-Printed Plastics

Rutgers engineers have embedded high performance electrical circuits inside 3D-printed plastics, which could lead to smaller and versatile drones and better-performing small satellites, biomedical implants and smart structures.

They used pulses of high-energy light to fuse tiny silver wires, resulting in circuits that conduct 10 times more electricity than the state of the art, according to a study in the journal Additive Manufacturing. By increasing conductivity 10-fold, the engineers can reduce energy use, extend the life of devices and increase their performance.

Our innovation shows considerable promise for developing an integrated unit – using 3D printing and intense pulses of light to fuse silver nanoparticles – for electronics,” said senior author Rajiv Malhotra, an assistant professor in the Department of Mechanical and Aerospace Engineering in the School of Engineering at Rutgers University–New Brunswick.

Embedding electrical interconnections inside 3D-printed structures made of polymers, or plastics, can create new paradigms for devices that are smaller and more energy-efficient. Such devices could include CubeSats (small satellites), drones, transmitters, light and motion sensors and Global Positioning Systems. Such interconnections are also often used in antennas, pressure sensors, electrical coils and electrical grids for electromagnetic shielding.

Source: https://news.rutgers.edu/

Portable Machine Harvests Water From Air

Driven by the scarcity of supply, climate change and ground watershed depletion, scientists present a design for a first of its kind portable harvester that mines freshwater from the atmosphere. For thousands of years, people in the Middle East and South America have extracted water from the air to help sustain their populations. Researchers and students from the University of Akron drew inspiration from those examples to develop a lightweight, battery-powered freshwater harvester that could someday take as much as 10 gallons (37,8 liters) per hour from the air, even in arid locations.

I was visiting China, which has a freshwater scarcity problem. There’s investment in wastewater treatment, but I thought that effort alone was inadequate,University of Akron professor Shing-Chung (Josh) Wong said.

Instead of relying on treated wastewater, Wong explained, it might be more prudent to develop a new type of water harvester that takes advantage of abundant water particles in the atmosphere. Freshwater makes up less than 3 percent of the earth’s water sources, and three quarters of that is locked up as ice in the north and south poles. Most water sustainability research is directed toward water supply, purification, wastewater treatment and desalination. Little attention has been paid to water harvesting from atmospheric particles.

Harvesting water from the air has a long history. Thousands of years ago, the Incas of the Andean region collected dew and channeled it into cisterns. More recently, some research groups have been developing massive mist and fog catchers in the Andean mountains and in Africa. Wong’s harvester is directed towards the most abundant atmospheric water sources and uses ground-breaking nanotechnology. If successful, it will produce an agile, lightweight, portable, freshwater harvester powered by a lithium-ion battery.

By experimenting with different combinations of polymers that were hydrophilic — which attracts water — and hydrophobic — which discharges water, the team concluded that a water harvesting system could indeed be fabricated using nanofiber technology. Unlike existing methods, Wong’s harvester could work in arid desert environments because of the membrane’s high surface-area-to-volume ratio. It also would have a minimal energy requirement. “We could confidently say that, with recent advances in lithium-ion batteries, we could eventually develop a smaller, backpack-sized device,” Wong said.

Source: https://www.uakron.edu/