Renewable Energy

Nanomaterial Help Batteries Store Renewable Energy

Want to know about latest updates in Renewable Energy? Northeastern researchers are looking for ways to create new sustainable materials from abundant natural resources—especially in the chemical structure of microfibers that form wood.

A group led by an assistant professor of mechanical and industrial engineering at Northeastern, Hongli (Julie) Zhu, is utilizing unique nanomaterials inherent from cellulose to enhance the large and costly batteries required to store renewable energy provided from sources such as wind and sunlight.

The richest natural polymer on Earth, cellulose, is also the most essential structural component of plants. It comprises basic structures to enhance batteries, reduce plastic pollution, and power the sort of grids that could support whole communities with renewable energy.

They try to utilize polymers from timber, from seeds, from bark, from flowers, green tea, bacteria. From these kinds of plants to replace plastic.

One of the difficulties in storing energy from the sun, the wind, and other forms of renewables, are that variation in the weather that leads to inconsistent sources of power.

That is where batteries with large capacity come in. But storing the massive amounts of electricity that the wind and sunlight can provide requires a special kind of device.

The most advanced batteries to do which are known as flow batteries, and are formed with vanadium ions dissolved in acid in two different tanks one with a material of negatively charged ions, and one with positive ones. The two mixtures are continuously pumped from the tank into a cell, which functions as an engine for the battery.

These materials are always isolated by a special membrane that assures that they interchange positive hydrogen ions without flowing together. That particular exchange of ions is the foundation for the ability of the battery to charge and discharge energy.

Flow batteries are devices in which solar and wind energy are stored because they can be changed to increase the amount of energy stored without compromising the level of energy that can be generated. The larger the tanks, the more energy the battery can save from non-polluting and inexhaustible resources.

But making them needs several moving pieces of hardware. Since the film dividing the two liquid substances decay, it may cause the vanadium ions from the solution to combine. That crossover decreases the stability of a battery, along with its capacity to save energy.

Image: researchgate.net

Zhu says that the membrane’s limited efficiency, combined with its high cost, is the crucial thing keeping flow batteries from being broadly used in large-scale grids.

In recent news, Zhu stated that a membrane formed with cellulose nanocrystals exhibits superior efficiency in comparison to other membranes used commonly in the market. The team analyzed several membranes formed by cellulose nanocrystals to make flow batteries cheaper.

“The price of our membrane is $147.68 per square meter,” Zhu says, adding that her estimates do not include expenses associated with marketing. “The cost of the advertised Nafion membrane is $1,321 per square meter.”

Their tests showed that the membranes formed can provide considerably higher battery life than other membranes.

The naturally obtained membrane of zhu is effective because its cellular structure comprises thousands of hydroxyl collections, which involve bonds of oxygen and hydrogen, which make it accessible for water to be transported in trees and plants.

Inflow batteries, that molecular makeup speeds the transportation of protons as they flow through the membrane.

The membrane also consists of another polymer called Poly(vinylidene fluoride-hexafluoropropylene), which restricts the positively and negatively charged acids from mixing with each other.

“For these substances, one of the difficulties is the fact that it is hard to get a proton conductive polymer, and that’s also a material that’s quite stable in the flowing acid,” Zhu says.

Because these materials are almost everywhere, membranes formed with it can be easily put collectively at large scales required for complex power grids.

Unlike other costly artificial materials that required to be concocted in a lab, cellulose can be derived from natural sources, including solid waste, algae, and bacteria.

“A great deal of material in nature is a composite, and when we disintegrate its parts, we can use it to obtain cellulose,” Zhu says. “Like waste from our lawn, and a lot of solid waste that people don’t always know what to do with.”

Nanomaterial Assists Store Solar Energy

Efficient storage technologies are required if solar and wind energy is to help meet increased energy requirements. One essential strategy is storage in the form of hydrogen obtained from water using wind or solar energy. This process executes in an electrolyzer. As a result of a new material produced by the researchers at Paul Scherrer Institute PSI and Empa, these materials will become cheaper and more efficient in the future. The material in question functions as a catalyst accelerating the splitting of water molecules: the initial step in the production of hydrogen.

Experts also revealed that this new material can be reliably produced in large amounts and proved its performance ability within a technical electrolysis cell — the central component of an electrolyzer. The results of their study have been issued in the newest edition of the scientific journal Nature Materials.

Since wind energy and solar is not always available, it will only contribute to fulfilling energy requirements once a reliable storage method has been built. One useful approach to this problem is storage in the form of hydrogen. This process requires an electrolyzer, which uses electricity generated by solar or wind energy to split water into oxygen and hydrogen. Hydrogen functions as an energy transmitter. It can be stored in tanks and later converted again into electrical energy using fuel cells. This procedure can be carried out in places where energy is required, such as domestic uses or fuel cell vehicles, allowing mobility without the CO2 emission.

Efficient And Inexpensive

Image: phys.org

Experts at the Paul Scherrer Institute PSI have now developed a new material that functions as a catalyst in an electrolyzer and thus accelerates the splitting of water molecules: the initial step in the production of hydrogen. “There are currently two different types of electrolyzers available on the market: one is efficient but costly as its catalysts comprise noble metals like iridium.

The others are more affordable but not so efficient,” explains Emiliana Fabbri, a researcher at the Paul Scherrer Institute. “We wanted to develop an efficient yet less costly catalyst that served without applying noble metals.”

Exploring this process, researchers were authorized to use a material that had been developed: a complex compound of the elements strontium barium, cobalt, iron, and oxygen — a perovskite. However, they were the first to create a technique allowing its production in the form of minuscule nanoparticles.

This is the form required to operate efficiently since a catalyst requires a large surface area on which many reactive centers are able to speed up the electrochemical process. Once particular catalyst particles have been made as small as possible, their specific surfaces combine to make a much larger surface area.

Experts used a simple flame-spray method to produce this nanopowder: a device operated by Empa that sends the material’s constituent components by a flame where they mix and instantly solidify into small particles once they leave the flame. “We needed to find a way of operating the device that reliably ensured that the solidifying of the atoms of the many elements in the perfect structure,” stated Fabbri. “We were also able to change the oxygen content where required, enabling the creation of different material variants.”

Successful Field Tests

Researchers were able to show that these processes work not only in the lab but also in practice. The production method provides large amounts of the catalyst powder and can be readily available for industrial use. “We were excited to test the catalyst in field conditions.

Surely, we have test arrangements at PSI capable of analyzing the material, but its value finally depends upon its effectiveness for industrial electrolysis cells, which are used in commercial electrolytes,” states Fabbri. Experts tested the catalyst in cooperation with an electrolyzer maker in the US and were able to show that the system worked more safely with the latest PSI-produced perovskite than with a standard iridium-oxide catalyst.

Testing in Milliseconds

Experts were also able to do specific experiments that provided precise information on what occurs in the new material when it’s active. This involved studying the substance with X-rays at the Swiss Light Source SLS of PSI.

This facility gives researchers a unique measuring channel capable of analyzing the condition of a material over timespans of only 200 milliseconds. “This allows us to monitor modifications in the catalyst during the reaction: we can detect changes in the arrangement or the electronic properties of atoms,” says Fabbri.

At other plants, each individual measurement needs about 15 minutes, providing only an averaged image at best.” These measurements also revealed how the structures of particle surfaces differ when active — parts of the material become amorphous, which indicated that the atoms in particular regions are no longer evenly arranged. Surprisingly, this makes the material a better catalyst.

Use from the ESI Platform

Working on the growth of technological solutions for Switzerland’s energy future is an essential aspect of the research at PSI. To this end, PSI advances its ESI (Energy System Integration) experimental Platform accessible to research and industry, enabling solutions to be tested in different complex contexts. The new catalyst gives an essential foundation for the development of a new generation of water electrolyzers.

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