Freezing Lithium Batteries May Make Them Safer and Bendable

Columbia Engineers use ice-templating to control electrolyte structure in lithium batteries; solid-state is non-flammable, non-toxic, and flexible with longer battery life

Newswise — New York, NY—April 24, 2017—Yuan Yang, assistant professor of materials science and engineering at Columbia Engineering, has developed a new method that could lead to lithium batteries that are safer, have longer battery life, and are bendable, providing new possibilities such as flexible smartphones. His new technique uses ice-templating to control the structure of the solid electrolyte for lithium batteries that are used in portable electronics, electric vehicles, and grid-level energy storage. The study (DOI 10.1021/acs.nanolett.7b00715) is published online April 24 in Nano Letters.

Liquid electrolyte is currently used in commercial lithium batteries, and, as everyone is now aware, it is highly flammable, causing safety issues with some laptops and other electronic devices. Yang’s team explored the idea of using solid electrolyte as a substitute for the liquid electrolyte to make all-solid-state lithium batteries. They were interested in using ice-templating to fabricate vertically aligned structures of ceramic solid electrolytes, which provide fast lithium ion pathways and are highly conductive. They cooled the aqueous solution with ceramic particles from the bottom and then let ice grow and push away and concentrate the ceramic particles. They then applied a vacuum to transition the solid ice to a gas, leaving a vertically aligned structure. Finally, they combined this ceramic structure with polymer to provide mechanical support and flexibility to the electrolyte. 

“In portable electronic devices, as well as electric vehicles, flexible all-solid-state lithium batteries not only solve the safety issues, but they may also increase battery energy density for transportation and storage. And they show great promise in creating bendable devices,” says Yang, whose research group is focused on electrochemical energy storage and conversion and thermal energy management. 

Researchers in earlier studies used either randomly dispersed ceramic particles in polymer electrolyte or fiber-like ceramic electrolytes that are not vertically aligned. “We thought that if we combined the vertically aligned structure of the ceramic electrolyte with the polymer electrolyte, we would be able to provide a fast highway for lithium ions and thus enhance the conductivity,” says Haowei Zhai, Yang’s PhD student and the paper’s lead author. “We believe this is the first time anyone has used the ice-templating method to make flexible solid electrolyte, which is nonflammable and nontoxic, in lithium batteries. This opens a new approach to optimize ion conduction for next-generation rechargeable batteries.” 

In addition, the researchers say, this technique could in principle improve the energy density of batteries: By using the solid electrolyte, the lithium battery’s negative electrode, currently a graphitelayer, could be replaced by lithium metal, and this couldimprovethe battery’s specific energyby 60% to 70%. Yangand Zhaiplan next to work on optimizing the qualities of the combined electrolyte and assembling the flexible solid electrolyte together with battery electrodes to construct a prototype of a full lithium battery. 

“This is a clever idea,” says Hailiang Wang, assistant professor of chemistry at Yale University. “The rationally designed structure really helps enhance the performance of composite electrolyte. I think that this is a promising approach.”  

The work is supported by the National Science Foundation MRSEC program through Columbia in the Center for Precision Assembly of Superstratic and Superatomic Solids (DMR-1420634). 

The study is titled “A Flexible Solid Composite Electrolyte with Vertically Aligned and Connected Ion-Conducting Nanoparticles for Lithium Batteries.” Authors are Haowei Zhai, Pengyu Xu, Mingqiang Ning, Qian Cheng, Jyotirmoy Mandal, and Yuan Yang. 

The authors declare no competing financial interests. 

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LINKS:

Paper:  http://pubs.acs.org/journal/nalefd   DOI 10.1021/acs.nanolett.7b00715

http://apam.columbia.edu/yuan-yang

http://www.engineering.columbia.edu/

http://pubs.acs.org/journal/nalefd 

Columbia Engineering

Columbia Engineering is one of the top engineering schools in the U.S. and one of the oldest in the nation. Based in New York City, the School offers programs to both undergraduate and graduate students who undertake a course of study leading to the bachelor's, master's, or doctoral degree in engineering and applied science. Columbia Engineering’s nine departments offer 16 majors and more than 30 minors in engineering and the liberal arts, including an interdisciplinary minor in entrepreneurship with Columbia Business School. With facilities specifically designed and equipped to meet the laboratory and research needs of faculty and students, Columbia Engineering is home to a broad array of basic and advanced research installations, from the Columbia Nano Initiative and Data Science Institute to the Columbia Genome Center. These interdisciplinary centers in science and engineering, big data, nanoscience, and genomic research are leading the way in their respective fields while our engineers and scientists collaborate across the University to solve theoretical and practical problems in many other significant areas.