In order to make electric vehicles (EVS) mainstream, they need cost-effective, safer and more durable batteries that will not explode or damage the environment during use. Researchers at Georgia Institute of technology may have found a promising alternative to traditional lithium-ion batteries: rubber.
Elastomer, or synthetic rubber, due to its superior mechanical properties, is widely used in consumer products and advanced technologies, such as wearable electronic devices and soft robots. The researchers found that when this material is prepared into a 3D structure, it has excellent mechanical toughness as a super highway for rapid lithium ion transportation, so that the battery can charge longer and go further. The study, carried out in collaboration with the Korean Institute of advanced science and technology, was published in the journal Nature on Wednesday.
In traditional lithium-ion batteries, ions are moved by liquid electrolyte. However, the battery itself is unstable: even the slightest damage can leak into the electrolyte, causing an explosion or fire. Safety issues have forced the industry to pay attention to solid-state batteries, which can be made of inorganic ceramic materials or organic polymers.
"Most industries are focused on building inorganic solid electrolytes. But they are difficult to manufacture, expensive and environmentally friendly," said Seung woo Lee, an associate professor at the George W. Woodruff School of mechanical engineering He was a member of a research team that found a rubber based organic polymer that was superior to other materials. Solid polymer electrolytes continue to attract great interest because of their low manufacturing cost, non-toxic and soft properties. However, traditional polymer electrolytes do not have enough ionic conductivity and mechanical stability to ensure the reliable operation of solid-state batteries.
The novel three-dimensional design brings a leap in energy density and performance
Georgia Tech engineers solved common problems (slow lithium ion transmission and poor mechanical properties) with rubber electrolytes. The key breakthrough is to make the material form three-dimensional (3D) interconnected plastic crystal phases in a solid rubber matrix. This unique structure brings high ionic conductivity, excellent mechanical properties and electrochemical stability.
The rubber electrolyte can be made by simple polymerization process at low temperature, producing a solid and smooth interface on the electrode surface. These unique characteristics of rubber electrolyte prevent the growth of lithium dendrites and allow faster movement of ions, enabling solid-state batteries to operate reliably even at room temperature.
"Rubber is used everywhere because of its high mechanical properties. It will enable us to make cheaper, more reliable and safer batteries. Higher ion conductivity means that you can move more ions at the same time. By increasing the specific energy and energy density of these batteries, you can increase the mileage of electric vehicles," Lee said
"Researchers are now studying how to improve the performance of the battery, increase its cycle time and reduce the charging time through better ionic conductivity. So far, their efforts have improved the performance / cycle time of the battery twice," said Michael Lee, a graduate researcher in mechanical engineering
This work can enhance Georgia's reputation as an electric vehicle innovation center. Sk innovation, a global energy and petrochemical company, is funding additional research on electrolyte materials as part of its ongoing cooperation with the Institute to build a safer and more energy intensive next-generation solid-state battery than traditional lithium-ion batteries. Sk innovation recently announced the construction of a new electric vehicle battery factory in business city, Georgia. It is expected that the annual output of lithium-ion batteries will reach 21.5 gigawatt hours by 2023.
Kyonghwan Choi, director of the next generation battery research center of SK innovation, said: "All solid state batteries can greatly improve the mileage and safety of electric vehicles. Fast growing battery companies, including SK innovation, believe that the commercialization of all solid state batteries will become a game changer in the electric vehicle market. Through the current project in cooperation with SK innovation and Professor Seung woo Lee of Georgia Institute of Technology, people have high hopes for the rapid application and commercialization of all solid state batteries."
