02/11/2019
- Team from Dalian Institute of Chemical Physics says its goal is to ‘develop an all-season battery that is low cost but high safety for consumer products’
- Researchers make breakthrough by using hard carbon and lithium vanadium phosphate
Chinese researchers say they have made a breakthrough in the development of small lithium batteries that can withstand low temperatures. Photo: Xinhua
Chinese researchers say they have found a way to produce a tiny, lightweight lithium battery for use in mobile phones and electric cars that can hold up to 80 per cent of its charge in temperatures as low as minus 40 degrees Celsius.
The breakthrough came by using a combination of a new material called hard carbon along with lithium vanadium phosphate, the team from the Dalian Institute of Chemical Physics said in a paper published in this month’s edition of the scientific journal Nano Energy.
“Our goal is to develop an all-season battery that is low-cost but high-safety for consumer products,” said Song Zihan, its lead author.
It was an unprecedented approach, but “we proved it works”, he said.
The idea of a battery that can withstand extreme cold is not new. Photo: Shutterstock
The idea of a battery that can withstand extreme cold is not new, and they are already in use in space and in the Arctic and Antarctic.
But they tend to be very bulky because of the heating system and large amount of insulation they need to function properly at sub-zero temperatures.
Such measures are neither physically nor economically viable for applications like smartphones, cameras, laptops or electric cars. The trick, Song said, was replacing the soft graphite in normal lithium batteries with hard carbon.
Graphite is a good conductor and often used for the anode at the bottom of a battery, where electrons are generated. But the performance of graphite drops as the mercury slides.
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Song said that hard carbon was a new material that had attracted a lot of research interest in recent years, and compared with graphite, it had a much higher tolerance for the cold.
That was because of its highly irregular and “almost messy” structure, comprising layers of carbon atoms that are interconnected with each other, he said.
However, hard carbon also caused a rapid depletion of the lithium ions that served as an agent carrying the electric flow in battery, he said.
The researchers want to make battery suitable for use in consumer products. Photo: EPA-EFE
In the past, researchers have tried adding lithium powders or flakes to improve battery life, but the approach has proven costly and dangerous, mostly because pure lithium is highly reactive.
So Song and his colleagues used a composite material called lithium vanadium phosphate as the positive cathode on top of the battery.
The composite was capable of providing enough extra lithium ions for the hard carbon’s need without increasing the risk of fire or explosion, and it was cheap, he said.
“The pairing of hard carbon and lithium vanadium phosphate worked a charm,” Song said.
But the technology is still a long way from being commercially viable.
The battery Song’s team made is far too small for any real-life applications, and enlarging it would require some “innovative engineering solutions”, he said.
Another scientist involved in the project said the team was working with battery manufacturers to see if the technology could be commercialised.
Source: SCMP
Posted in Antarctica, Arctic, cameras, capable, Chinese scientists, create, Dalian Institute of Chemical Physics, electric cars, laptops, lithium batteries, low temperatures, Nano Energy, smartphones, Space, tiny battery, ultra-low temperatures, Uncategorized, withstand, working |
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14/08/2019
- Scientists’ large-scale conversion of agricultural waste into fuel offers savings up to 60 per cent, they say
- Discovery could slash military costs and bring civilian applications of hypersonic flight technology closer
Super-fuel for military aircraft costs nearly 10 times as much as ordinary jet fuel for commercial planes. Photo: Shutterstock
Chinese scientists say they have developed a technology to convert bio-waste into fuel for missiles and hypersonic planes, reducing fuel costs by as much as 60 per cent.
The existing JP-10 super-fuel for military aircraft has numerous advantages including high energy density, good thermal stability and low freezing point, but it costs more than US$7,000 per tonne – nearly 10 times as much as ordinary jet fuel for commercial aircraft.
It is used mainly in cruise missiles and ramjet or scramjet engines on new-generation aircraft travelling at hypersonic speed, or five times faster than sound.
Scientists from the Dalian Institute of Chemical Physics, at the Chinese Academy of Sciences in the northeastern province of Liaoning, predicted using the new technology in the near future could reduce the cost to as low as US$2,547 per tonne.
The secret, according to their paper, published in the latest issue of German chemistry journal Angewandte Chemie, lies in cheap bio-waste.
Using agricultural and forestry residues including bran, chaff and mill dust, Professor Zhang Tao, Li Ning and colleagues discovered new chemical processes that can turn the waste to JP-10 fuel on a large scale with unprecedented efficiency.
At present, the super-fuel comes from coal tar or naphtha, and the synthesis is extremely costly and unfriendly to the environment.
The bio-JP-10 fuel can be produced by two different methods, one involving six steps of chemical reactions and the other only four, according to the paper.
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Combining these methods with the latest technology in biomass conversion, the researchers said, the super-fuel can be mass-produced at a price equivalent to that of some of the bio-jet fuels already in commercial use, thanks to government subsidies provided for their environmental benefits.
“We believe that the future commercialisation of bio-JP-10 fuel is very promising, especially taking policy support and exemption from CO2 emission tax into consideration,” the authors wrote in the paper.
Liu Huoxing, professor at the school of energy and power engineering at Beijing University of Aeronautics and Astronautics, said civilian applications of hypersonic flight technology faced many challenges that remained to be solved, with the problem of high fuel prices being one of the headaches.
“No airline will buy a plane if the fuel costs too much, however fast it can fly,” he said.
Liu, who conducts research on engine technology for
hypersonic vehicles but was not involved in the Dalian study, said the reduction of production costs for jet fuel was usually incremental and it was quite rare to see a significant drop.
“This can be an important development,” he said of the Dalian findings.
China is developing various models of hypersonic speed aircraft for military and civilian use. Some are aimed at flying distances such as Shanghai to Los Angeles in a couple of hours.
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