To take performances of lithium-ion (Li-ion) batteries to the next level, scientists continue to conduct research on new material technologies that can produce better electrolytes and electrodes. Recently, the University of Vienna in Austria has announced that its Faculty of Chemistry has developed a new nanostructured anode made of a mixed-metal oxide and graphene. The introduction of this high-efficiency technology could increase both capacity and cycle life of Li-ion batteries used by consumers.
Li-ion batteries offer several distinct advantages over other kinds of rechargeable batteries: higher energy density, longer cycle life, and no memory effect. And because of these advantages, Li-ion batteries are deployed not only in consumer electronics but also in energy storage systems that support renewable generation equipment as well as in powertrain systems for electric vehicles. To further enhance the capabilities of Li-ion batteries with respect to cycle life and overall performance, researchers have been searching for active electrode materials that provide greater efficiency and stability.
Currently, carbon-based materials such as graphite are preferred over metal oxide compounds as the anode materials for conventional Li-ion batteries because the latter are generally unstable and less conductive. However, metal oxides can also raise the battery capacity substantially. Freddy Kleitz, who works in the Department of Inorganic Chemistry in the University of Vienna, said that the new nanostructured anode combines the higher conductivity and better stability of a carbon-based material with the capacity advantage of a metal oxide. Kleitz is a member of the team that is responsible for the development of this nanostructured anode, the application of which could lead to batteries featuring higher capacity and efficiency. The team also includes researchers from the Polytechnic University of Turin in Italy.
The research team designed the material and created it in a lab environment. First, copper and nickel were mixed together. Then, a nanocasting process turned the mixed metal into mixed-metal oxide particles. The particles can significantly extend the anode’s area for exchanging lithium ions, as they have pores that serve as highly active zones for reaction. Finally, the research team used a spray drying process to encapsulate the graphene layers with the mixed-metal oxide.
The new anode material, which also called the 2D/3D nanocomposite, is expected to significantly improve the electrochemical performance of Li-ion batteries. Lab results have shown that the application of the nanostructured anode can sharply increase the specific capacity of the battery. Furthermore, the cycling stability has also been raised to a new level. Even at a high current of 1,280 milliamperes, the new anode allows for more than 3,000 reversible charge and discharge cycles. Existing Li-ion batteries, by contrast, generally cannot maintain their performance after 1,000 charging cycles.
Going forward, the research team at the University of Vienna will be working on the optimization of the whole manufacturing process. The team has stated that the “water-based” process that it has developed for the manufacturing of the material not only can meet industry-related needs but is also simpler and more environment-friendly than other existing engineering strategies.
Li-ion remains an indispensable battery technology due to its scalability, from small consumer electronics such as smartphones and notebook PCs to battery powertrain systems for electric vehicles, and to energy storage systems that are integrated with solar power equipment. As the support for energy-saving and carbon-reduction policies rises worldwide, Li-ion batteries are expected to have an even larger role to play in industries and the everyday life of consumers. And once the anode material developed by the team at the University of Vienna has moved from the lab to the market, it will probably bring immense benefits to many energy-related applications. The work of the research team was published in the academic journal Advanced Energy Materials this October.
(The above article is an English translation of a Chinese article written by Daisy Chuang. The credit of the top image goes to the University of Vienna.)