Shaping the Future of Energy Storage With Conductive Clay

altIn the race to find materials of ever increasing thinness, surface area and conductivity to make better performing battery electrodes, a lump of clay might have just taken the lead. Materials scientists from Drexel University’s College of Engineering invented the clay, which is both highly conductive and can easily be molded into a variety of shapes and sizes. It represents a turn away from the rather complicated and costly processing—currently used to make materials for lithium-ion batteries and supercapacitors—and toward one that looks a bit like rolling out cookie dough with results that are even sweeter from an energy storage standpoint.

With the publication of their recipe for “conductive MXene clay” in the Dec. 4 edition of Nature, the researchers suggest a significant shift in the way electrodes for storage devices are produced.

Researchers at Drexel University have developed a way to make a highly conductive clay from MXene and water.

The clay, which already exhibits conductivity on par with that of metals, can be turned into a film—usable in an electrode—simply by rolling or pressing it.

“Both the physical properties of the clay, consisting of two-dimensional titanium carbide particles, as well as its performance characteristics, seem to make it an exceptionally viable candidate for use in energy storage devices like batteries and supercapacitors,” said Yury Gogotsi, PhD, Distinguished University and Trustee Chair professor in the College of Engineering, and director of the A.J. Drexel Nanomaterials Institute, who is a co-author of the paper. “The procedure to make the clay also uses much safer, readily available ingredients than the ones we used to produce MXene electrodes in the past.”

The key to the utility of this material, according to Michel Barsoum, PhD, Distinguished professor in the College of Engineering and one of the inventors of MXenes, is in its form.
“As anybody who has played with mud can attest, clay is hydrophilic –water-loving,” Barsoum said. “Clay is also layered and when hydrated, the water molecules slide between the layers and render it plastic that in turn can be readily shaped into complex shapes. The same happens here; when we add water to MXene, water penetrates between the layers and endows the resulting material with plasticity and moldability. Graphene—a material widely studied for use in electrodes- on the other hand, is conductive but does not like water—it is hydrophobic. What we discovered is a conductive two-dimensional layered material that also loves water. The fact that we can now roll our electrodes rapidly and efficiently, and not have to use binders and/or conductive additives renders this material quite attractive from a mass production point of view.”
A graphic illustration of the properties of MXene clay.The discovery came about while Michael Ghidiu, a doctoral student advised by Barsoum and Gogotsi in the Department of Materials Science and Engineering at Drexel, was testing a new method for making MXenes—two-dimensional materials invented at Drexel that are among the leading candidates for use in next-generation batteries and supercapacitors.

Straying slightly from the original chemical etching process pioneered at Drexel, which uses highly toxic hydrofluoric acid, Ghidiu instead used a fluoride salt and hydrochloric acid to etch aluminum out of a titanium-based, layered ceramic material called a MAX phase—also discovered at Drexel by Barsoum. These two ingredients, which are household names in chemistry class and are also much safer to handle than hydrofluoric acid, reduced the MAX phase to a pile of black particles. To stop the reaction and remove any residual chemicals, Ghidiu washed the material in water. But rather than finding the familiar layered MXene particles, he discovered that the etched sediment absorbed the water to form a clay-like material.

“We expected to find a slightly different material coming from the new process—but nothing like this,” Ghidiu said. “We were just hoping for a safer, less expensive way to make MXenes, when something even better landed on the table.”
clay rolling

One of the first tests the team performed on the clay was to see if it could be pressed into a thin layer while retaining its conductive properties—after all, its initial goal was to make a conductive film.

“Being able to roll clay into a film is quite a contrast in production time, safety and cost when compared to the two most common practices for making electrode materials,” Ghidiu said. “Both the etching and peeling process used to make MXenes and a flaking, filtration and deposition method—like paper making—employ strong acids and costly, less common materials. The clay-making process is much simpler, quicker and safer.”

MXene clay made by researchers at Drexel University can be rolled into any thickness while retaining its conductivity.  With the new discovery, all these steps are avoided, greatly simplifying the processing. Now the researchers can simply etch the MAX phase, wash the resulting material and roll the resultant clay into films of various thicknesses.

“I would say the most important benefit to the new method—besides its increased capacitance—is that we can now make an electrode ready-to-go in about 15 minutes, whereas the total process before from the same starting point would be on the order of a day,” Ghidiu said.

The availability of its ingredients also makes the clay rather appealing from a production standpoint.

“Being able to make a conductive clay, essentially out of titanium carbide with the help of a common fluoride salt and hydrochloric acid is the materials equivalent of making a chocolate chip cookie—everybody has these ingredients in the pantry,” said Barsoum.

But a question that resounds through most materials research of this nature is, of course: what can it do with an electrical charge?

Thorough investigation of the clay’s electrochemical performance, conducted by Maria Lukatskaya a doctoral student advised by Gogotsi and Barsoum, which was reported in the paper, indicated that the clay’s ability to store an electrical charge is three times that reported for MXenes produced by hydrofluoric acid etching. This means it could find uses in the batteries that power cell phones and start cars, or even in a supercapacitor that could one day help renewable energy sources fit into a regional power grid.
clay circuit

“Keep in mind this is the very first generation of the material that we’re testing,” Lukatskaya said. “We haven’t done a thing to augment its abilities, and at 900 F/cm3 it’s already showing a higher capacitance per unit of volume than most other materials. We’re also reporting that it does not lose any of its capacitance through more than 10,000 charge/discharge cycles, so we’re talking about quite a special lump of clay here.”

Changing materials scientists’ medium from film to clay presents a variety of new avenues for research and manufacturing. The clay can be molded into any shape. It could also be watered down into a conductive paint that hardens within a few minutes while still retaining its conductive properties. This means it could have applications in batteries, conductive transparent coatings and reinforcement for composites among others.
An electron microscopic study of the clay particles dispersed in water, conducted by co-author Mengqiang Zhao, PhD, a post-doctoral researcher in Gogotsi’s group, showed that the clay is made up of single layers of MXene about one nanometer—just a few atoms—thick. This atomically thin structure indicates that researchers are likely to find that the clay has many attractive electronic and optical properties as they continue to learn more about it.   

“We plan to keep pushing forward with our study of this new material in hopes of developing a truly scalable manufacturing process, improving quality and yield of MXene and exfoliating other MAX phases to produce new MXenes, which could not be synthesized using the previously used process—the possibilities seem endless. While it might look like just a bit of clay, I believe this discovery will reshape research in the field going forward.” Barsoum said.

This work was supported by the Ceramics Program of the National Science Foundation and by the U.S. Department of Energy’s FIRST Energy Frontier Research Center.


Related Articles:



Drexel Engineers Improve Strength, Flexibility of Atom-Thick Films - a conductive polymer MXene nanocomposite

A scanning electron microscopic image of MXene-polymer nanocomposite shows the polyvinyl alcohol filling in the layers of MXene to give the material its unique properties.Flexible new material, which the group has identified as a conductive polymer nanocomposite, is the latest expression of the ongoing research in Drexel’s Department of Materials Science and Engineering on a family of composite two-dimensional materials called MXenes


Flexible and conductive MXene films and nanocomposites with high capacitance

altTwo-dimensional transition metal carbides (MXenes) offer a quite unique combination of excellent mechanical properties, hydrophilic surfaces, and metallic conductivity.





News from MRC.ORG.UA


Researchers from the A.J. Drexel Nanomaterials Institute have been studying MXene for nearly half a decade. (L-R): Olekisy Gogotsi (Director of Materials Research Center, Ukraine), Gabriel Scull, Babak Anasori, Mohamed Alhabeb, Yury Gogotsi.

More than twenty 2D carbides, nitrides and carbonitrides of transition metals (MXenes) have been synthesized and studied, and dozens more predicted to exist. Highly electrically conductive MXenes show promise in electrical energy storage, electromagnetic interference shielding, electrocatalysis, plasmonics and other applications.

Prof. Gogotsi has been included in the list of ISI Highly Cited researchers for the 3rd year in the row

altProf. Gogotsi has been named among Highly Cited Researchers 2016, representing worlds most influential scientific minds

Appointment ceremony of Honorary professorship for prof. Yury Gogotsi, Jilin University, Changchun, China on October 20, 2016

Honorary professor of Jilin University Yury Gogotsi  and Li Yuanyuan, President of Jilin University, academician of the Chinese Academy of Engineering

The official appointment ceremony of Honorary professorship for Dr. Yury Gogotsi took place in a ceremonial atmosphere at Jilin University, Changchun, Jilin Province, China on October 20, 2016.

12th IUPAC International Conference on Novel Materials and their Synthesis (NMS-XII)

12th IUPAC International Conference on Novel Materials and their Synthesis (NMS-XII)12th IUPAC International Conference on Novel Materials and their Synthesis (NMS-XII), is held during 14-19 October, 2016 at Hunan Agriculture University together with Nanjing Tech University, Fudan University and University of Technology, Sydney.

Cleaning up electromagnetic pollution by containing the emissions with a thin coating of a nanomaterial called MXene

MXene is a nanomaterial that is both thin and light, but also has the unique ability to block and absorb electromagnetic radiation, which makes it the perfect for use as shielding in electronics devices.

 According to the authors, when electromagnetic waves come in contact with MXene, some are immediately reflected from its surface, while others pass through the surface but they lose energy amidst the material’s atomically thin layers.

Beijing University of Chemical Technology awarded prof. Yury Gogotsi, Drexel University (USA) the title of Honorary Professor

Honorary Professor appointment ceremony at the Beijing University of Chemical TechnologyBeijing University of Chemical Technology have decided to award prof. Yury Gogotsi, Drexel University (USA) the title of Honorary Professor based on his distinguished academic accomplishments. 

Prof. Yury Gogotsi became the winner of 2016 Nano Energy Award!

prof. Yury Gogotsi, Drexel UniversityNano Energy Award was presented to prof. Yury Gogotsi at 2016 Nanoenergy and Nanosystems Conference, which was held in Beijing on 13-15 July 2016.

Professor Yury Gogotsi, director of Drexel Nanomaterials Institute, Drexel University, USA, and director of Materials Research Centre Oleksiy Gogotsi visited Jilin University in Changchun, China

meeting at Jilin UniversityProfessor Yury Gogotsi, director of Drexel Nanomaterials Institute, Drexel University, USA, and director of Materials Research Centre Oleksiy Gogotsi visited Jilin University in Changchun, China, to meet research partners and discuss work questions and joint cooperation.

Yury Gogotsi gave a seminar lecture on Two-Dimensional Carbides and Nitrides (MXenes) and Their Applications in Energy Storage, Jilin University, China

Director of Materials Research Centre Oleksiy Gogotsi visited interesting seminar lecture of Prof. Yury Gogotsi on MXenes for the students of Jilin University.

June 16, 2016 prof. Yury Gogotsi gave a seminar lecture on Two-Dimensional Carbides and Nitrides (MXenes) and Their Applications in Energy Storage for the sudents and researchers of Jilin University, Changchun, China.

Nature Conference on Materials for Energy 2016

altProf.Yury Gogotsi at the Nature Journals’ Materials for Energy conference gave a talk on Synthesis, Properties And Energy Storage Applications of Two-Dimensional Carbides (Mxenes) in Wuhan University of Technology Conference Centre, Wuhan, China

Congratulations to Prof. Gogotsi on winning the 2016 Nano Energy Award

prof. Yury Gogotsi, Drexel UniversityThe award will be presented to prof. Yury Gogotsi at the Nanoenergy and Nanosystems 2016 conference, which will be held in Beijing between 13-15 July 2016.

Congratulations to professor Yury Gogotsi for being named a Thomson Reuters 2015 Highly Cited Researcher!

altProfessor Yury Gogotsi have been listed in the 2015 World’s Most Influential Scientific Minds. 

Prof. Yury Gogotsi has been admitted as Fellow of the Royal Society of Chemistry (FRSC)

Royal Society of ChemistryProf. Yury Gogotsi has been admitted as Fellow of the Royal Society of Chemistry (FRSC) on December 11, 2015 for his outstanding contribution to chemistry. 

Prof. Yury Gogotsi was awarded the Lee Hsun Award Lecture

Prof. Yury Gogotsi was awarded the Lee Hsun Award Lecture at the Institute of Metal Research (IMR) of the Chinese Academy of Sciences on Nov. 5.Prof. Yury Gogotsi was awarded the Lee Hsun Award Lecture at the Institute of Metal Research (IMR) of the Chinese Academy of Sciences on November 5, 2015.

Yury Gogotsi and Patrice Simon were announced as the laureates of RUSNANOPRIZE 2015 at the Open Innovations Forum in Moscow, October 28, 2015

Лауреаты премии RUSNANOPRIZE 2015 проф. Юрий Гогоци (Университет Дрекселя, США) и проф. Патрис Симон (Университет Тулузы им. Поля Сабатье, Франция), 28 октября 2015 г.

Winners of the international award RUSNANOPRIZE 2015 became Yury Gogotsi,  professor  of Drexel University (USA), Director of the Institute of nanomaterials Drexel University (USA), and professor of the University Paul Sabatier (France), Patrice Simon for the fundamental studies and development of carbon nanomaterials for electrochemical supercapacitors.