Scientists in the United States have studied the use of different conductive filler materials in lithium-ion battery electrodes and found that adding single-walled carbon nanotubes to the nickel-cobalt-manganese cathode can improve the overall battery's conductivity and higher rate capability. According to the research results of this group, new insights can be provided for the design of high-power and high-energy battery electrodes.
Among the many ways to improve today's energy storage technology, adding conductive "filler" materials to the electrode is expected to bring better rate capability, conductivity and overall battery performance.
A scientist led by the University of Texas at Austin (UTA) explained: “Although various conductive fillers have been extensively developed, how the geometry and size of these fillers affect the electrode conductivity, structure and ultimately the understanding of electrochemistry The performance of the storage system is still insufficient."
The team conducted experiments with three different conductive carbon materials to determine which material has the best performance. Different amounts of single-walled carbon nanotubes, graphene nanosheets, and "Super P" (a type of carbon black particles that have been commonly used as conductive fillers in lithium-ion batteries) are added to the nickel cobalt manganese (NCM) cathode.
These cathodes are then measured using various spectroscopic and electrochemical characterization techniques. A paper published in Applied Physics Review revealed the dimensional effect of conductive fillers in thick battery electrodes used in high-energy storage systems.
The application of lithium-ion batteries is limited because they cannot meet the requirements of high power output and reversible energy storage. The main challenge is to develop an electrode system that can generate both high energy and power. As one of the key components, conductive fillers play a vital role in battery electrodes, helping to form conductivity and shaping the electrode structure, thereby significantly determining the rate capability.
Single-walled carbon nanotubes (SWCNT) have proven to be the best performing additives. The team observed that the nanotubes formed a conductive coating around the NCM particles and also formed an interconnected network between the NCM particles. Graphene nanosheets have similar effects, but the structure formed is not uniform.
The best SWCNT electrode showed a charging rate of 142 milliampere-hours per gram (mAh/g) at 0.2 degrees Celsius, which dropped to 101 mAh/g. When the interest rate increased to 2 C group, it was also found that 0.16% of the body weight of SWCNTs was sufficient Ensure good conductivity. Guihua Yu of UTA explains: “When conductive fillers are added to an insulating matrix, once the first conductive path through the composite is formed, the conductivity increases significantly.”
The organization stated that its findings indicate that integrating SWCNT in this way can promote better ion and charge transfer, resulting in better-performing batteries, especially at high discharge rates. In general, a better understanding of the behavior of conductive fillers can open new doors for the design of high energy/power density electrodes.