Inexpensive rechargeable batteries are at the heart of virtually all portable electronic devices that have become ubiquitous in modern day life. In addition, rechargeable batteries are an integral part of many environmentally friendly technologies, such as: B. Electric cars and systems that generate renewable energies.
They are also important factors in various medical devices and facilitate research in various fields as a power source for electronic sensors and cameras. It should come as no surprise then that a lot of effort is being put into developing better, cheaper rechargeable batteries.
So far, rechargeable lithium-ion batteries have been number one thanks to their comprehensive performance in terms of capacity, stability, price and charging time. However, lithium and other smaller and expensive metals like cobalt and copper are not among the most abundant materials on the earth’s crust, and their ever-increasing demand will soon lead to supply problems around the world.
At Tokyo University of Science in Japan, Professor Shinichi Komaba and colleagues attempted to solve this worsening puzzle by developing rechargeable batteries using alternative, more common materials.
In a study recently published in Angewandte Chemie International Edition, the team found an energy-efficient method for producing a novel carbon-based material for sodium ion batteries. In addition to Prof. Komaba, Ms. Azusa Kamiyama and Associate Prof. Kei Kubota from Tokyo University of Science, Dr. Yong Youn and Dr. Yoshitaka Tateyama from the National Institute for Materials Science, Japan, and Associate Prof. Kazuma Gotoh on the team from Okayama University, Japan.
The study focused on the synthesis of hard carbon, a highly porous material that serves as a negative electrode for rechargeable batteries, using magnesium oxide (MgO) as an inorganic template from nano-sized pores in hard carbon.
Researchers investigated another technique for mixing the ingredients of the MgO template to precisely tune the nanostructure of the resulting hard carbon electrode. After several experimental and theoretical analyzes, they determined the optimal manufacturing conditions and ingredients for the production of hard carbon with a capacity of 478 mAh / g, the highest value ever reported for this type of material.
Prof. Komaba explains: “Until now, the capacity of carbon-based negative electrode materials for sodium ion batteries has mostly been 300 to 350 mAh / g. Although values close to 438 mAh / g have been reported, these materials must be treated at extremely high temperatures above 1900 ° C. In contrast, we used a heat treatment at only 1500 ° C, a relatively low temperature. “With a lower temperature, of course, goes hand in hand with lower energy consumption, which also means lower costs and lower environmental impact.
The capacity of this newly developed hard carbon electrode material is certainly remarkable and far exceeds that of graphite (372 mAh / g), which is currently used as the negative electrode material in lithium-ion batteries. Although a sodium ion battery with this carbon negative electrode would theoretically operate on a voltage differential of 0.3 volts lower than a standard lithium ion battery, the higher capacity of the former would result in a much greater energy density, resulting in weight (1600 Wh / kg versus 1430 Wh / kg) leads to an increase in energy density of + 19%.
Excited about the results and looking to the future, Prof. Komaba remarks: “Our study shows that it is possible to produce high-energy sodium ion batteries, which dispels the general assumption that lithium ion batteries have a higher energy density. The hard carbon we developed with extreme high capacity has opened a door for the design of new sodium storage materials. “
Further studies are needed to verify that the proposed material actually offers superior life, input / output properties, and low temperature operation in actual sodium ion batteries. With a bit of luck, we may be close to the next generation of rechargeable batteries!
Tokyo University of Science
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Mammalian bones inspire the design of a new sodium ion battery
Washington DC (UPI) December 8, 2020
In order to build a structurally more stable sodium ion battery, a team of researchers from South Korea and the United States took inspiration from mammalian bones and their multilayered geometry. Like mammalian bones, the new battery structure – described Tuesday in Applied Physics Review – combines a spongy inner material with a harder, more compact outer layer. In the past few years, scientists have looked at the sodium ion battery to get rid of the lithium ion battery for good … read more