Research advances lithium battery technology

Research by a team of academics from Duke Kunshan and other universities has advanced solid-state lithium battery technology and could have an impact on renewable energy.

Published in science journal Nature Materials, the study revealed changes in battery construction that improve safety and performance, making them a more viable replacement for fossil fuels across many industries.

“The research is a significant step forward in developing next generation energy devices,” said co-author of the paper Xinrong Lin, associate professor of chemistry at DKU. “It could help to make safe and high-energy batteries a reality, which would have an impact across the transportation and power industries,” she added.

Xinrong Lin, associate professor of chemistry at Duke Kunshan University

Lin worked with Professor Mao Chen from Fudan University and Professor Yang Shao-Horn from Massachusetts Institute of Technology on the research, along with their teams.

Their work focused on improving lithium batteries, energy storage devices that have had a profound impact on lifestyles since the technology’s commercialization in the 1990s, allowing the development of electric devices such as laptop computers, cell phones and electric cars.

“Now, lithium battery applications dominate the electric car market and are marching towards grid-scale storage, changing the energy structure by replacing fossil fuels with clean

and renewable electricity, significantly reducing their greenhouse gas emissions and contributing to the global fight against climate change,” said Lin.

However, current lithium batteries have failed to strike a balance between performance, including higher charge capacity, faster charge rate and a safer battery system, against longer device life, according to Lin.

“Current commercial batteries face safety issues such as self-ignition and explosion, because they mainly employ flammable and volatile liquid electrolytes,” she said.

“Solid-state-batteries have emerged as a promising next-generation lithium battery technology that could provide enhanced safety, energy density and cycle life at the system level,” she added.

Solid-state lithium batteries use thin layers of solid electrolytes that carry lithium ions between electrodes to create a charge. The research team designed their own solid electrolytes using different sequences of monomers, molecules that can react together to form larger polymer chains that are capable of ion conduction.

They then investigated the properties of these solid electrolytes using optical, thermodynamic, mechanical and electrochemical instruments, and employed molecular dynamic simulation to examine their ion conductivity. Following this they designed a prototype solid electrolyte based on their testing that offered improved performance and greater stability.

“Our research has lowered the operating temperature of all-solid-state batteries with dry polymer electrolytes to room temperature, while existing related batteries can only work at 60 to 80 degrees centigrade,” said Lin. “The distinctive polymer electrolyte design has created more homogeneous ion distribution and continuous ion transport pathways between the electrodes, considerably increasing ionic conductivity of state-of-the-art dry polymer electrolytes by one to three orders of magnitude.”

While the research was primarily aimed at improving solid-state battery technology, it could also have an impact in other fields where electrolyte conductivity is involved, including sodium/zinc batteries, flexible fiber batteries, solar cells, fuel cells and supercapacitors.

The team is now planning further research to improve their polymer structure and create still better solid-state lithium batteries.

“We will be dedicated to experimenting with their performance in bigger battery configurations and scales, and testing in more rigorous conditions,” said Lin.

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