A few days ago, it was reported that researchers from Sweden are exploring the development of electrode materials for carbon fiber lithium batteries that can be used in electric vehicles, which have very high tensile strength. The carbon fiber lithium battery electrode material will be used for a multifunctional lithium ion structure battery of an electric vehicle. Among them, the multifunctional lithium ion structure battery can integrate the battery energy storage material into the automobile body. Since carbon fiber materials have very high tensile strength and ultimate tensile strength (UTS), they also have very strong lithium ion integration capabilities. Therefore, carbon fiber materials are often used as structural electrodes in lithium ion batteries.
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Mats Johansson from the Royal Institute of Technology (KTH) of Sweden said that the main research project of the above-mentioned electric vehicle carbon fiber lithium battery structure electrode material research project is to improve the mechanical characteristics of the battery, so that the battery can not only store energy but also be designed to be integrated into the structure. Part of the other features. Mats Johansson also exemplified that the hood of a car can be designed as part of a battery by utilizing the above-described electric vehicle carbon fiber lithium battery structure electrode material. The above multi-functional lithium-ion structure automotive battery has attracted a lot of project research, including:
Researchers from Imperial College London and Volvo Automotive Technology researchers formed a research team. The research team's research aims to develop a prototype of a multi-functional lithium-ion structure automotive battery using carbon fiber material and polymer resin, so that the battery can not only store and release electrical energy, but also has high structural strength and Light weight, so it can be used to design and manufacture integrated into automotive parts. The total funding for the research project is 3.4 million euros (about 4.7 million US dollars). Project developers plan to replace the metal floor in the spare tire compartment with composite materials. Volvo Cars is currently working on a design study to apply the spare tire compartment composite to a prototype vehicle for experimental research.
The Volvo Automotive Research Group has developed two versatile composite components and conducted experimental studies, which laid the foundation for subsequent research on the above technologies. Among them, the two multifunctional composite components that have been developed are the trunk cover and the inflatable cover, and the above two new components are all tested in the Volvo S80.
RANGE Research Program
The Advanced Research Projects Agency - Energy (ARPA-E) has launched a research program called RANGE, which aims to promote revolutionary advances in electric vehicle energy storage media. In 2013, the US Advanced Project Institute Energy Institute awarded a total of $8.75 million in project bonuses to four different research projects. The four research projects were led by Stanford University, UC San Diego, Arizona State University, and Penn State. Among them, the research objectives of the above four research projects are all for the development of multi-functional structure automotive batteries.
Emile Greenhalgh, coordinator of research and development at Imperial College London, said that the multi-functional structural battery composite can not only store and release electrical energy, but also carry mechanical loads. Its characteristics were confirmed in 2005 by researchers from the US Army Research Laboratory.
At the 2005 Materials Research Society Symposium, a technical article introduced three examples of multifunctional power generation materials and energy storage materials: lithium ion structured batteries, proton exchange membrane (PEM) fuel structures. Battery and structural capacitors. According to the researcher, the above new technology applications have been carefully designed, and the applied materials can not only store and release electrical energy, but also can carry structural loads. Therefore, the multi-purpose design is achieved and the overall weight is greatly reduced.
For this technology, the Royal Swedish Institute of Technology formed a research team composed of three professors from the Royal Institute of Technology in Sweden, including Göran Lindbergh, professor of chemical engineering, Mats Johansson, professor of fiber and polymer technology, and aviation and vehicles. Engineering professor Dan Zenkert. In addition, the research project also includes the Swedish Swerea SICOMP and the Luleå Institute of Technology.
Reversible capacity potential of polyacrylonitrile
Eric Jacques, a researcher in automotive and aerospace engineering from the Royal Institute of Technology in Sweden (the research direction of his doctoral thesis is on structural batteries), shows that there are two main functions of carbon fiber materials applied to automobiles. One is the lightness of the car body. A composite composite reinforcement material; another major application is as an electrode for automotive lithium-ion batteries.
Eric Jacques said: "Our main purpose of our research on carbon fiber lithium battery electrode materials is to develop a multi-functional structure battery that can not only have light material properties, but also can withstand mechanical loads and can store electrical energy. Significantly reduce the overall weight of electric vehicles."
Eric Jacques and colleagues published a technical paper on the study of electrode materials for carbon fiber lithium batteries in the journal Electrochemical Society in 2013. According to the paper, when the lithiation rate of lithium-ion batteries is maintained at a certain value of 100 mA/g, the reversible capacity of several grades of polyacrylonitrile (PAN)-based carbon fibers sold on the market is ten times. It can reach 100 mAh/g or even higher after the discharge cycle. Among them, the main factor affecting the measurement of capacitance of lithium ion batteries is the lithiation rate of lithium ion batteries. It has been found through experiments that reducing the current through one-tenth of all experimental carbon fiber materials can increase the battery capacity by 100%. Through the above experimental measurement studies, the Eric Jacques research team concluded that carbon fiber materials can be used not only as battery cathode materials but also as collectors in batteries in structural batteries.
Eric Jacques
Earlier this year, Eric Jacques and his colleagues published an article in Carbon magazine. This paper mainly introduces the relationship between the lithium content in lithium ion batteries and the tensile strength and ultimate tensile strength of polyacrylonitrile-based carbon fiber materials in batteries. The main findings of the paper also include:
After several cycles of electrochemical charge and discharge in a lithium-ion battery, the strength of the carbon fiber material in the battery did not decrease, and the measured capacitance of the battery was not affected.
The ultimate tensile strength of the lithiated carbon fiber material in the battery will be reduced during battery use, but it will partially recover during delithization of the battery and will be highest when the battery reaches its maximum measured capacitance. However, the ultimate tensile strength is still less than 40% of its own strength when the battery is fully charged.
The relationship between the reversibility of the ultimate tensile strength reduction of the lithiated carbon fiber material in the battery and the carbonization rate and the measured capacitance of the battery indicates that the carbon fiber is not affected during the use of the battery, and the lithium in the battery is in the process of delithiation of the carbon fiber. An irreversible reaction may occur. However, the reduction in the ultimate tensile strength of lithiated carbon fiber materials in batteries is not linearly related to the measured capacitance of the battery. At the same time, the ultimate tensile strain of the lithiated carbon fiber material in the battery is less than the longitudinal expansion of the carbon fiber material when the battery is fully charged.
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