Researchers Develop Higher Performance Li-Ion Electrode Materials Using Ultracentrifugal Processing

From Green Car Congress:

Researchers at the Naoi Laboratory at the Tokyo University of Agriculture and Technology have used an in situ sol-gel process induced by ultra-centrifugal mechanical agitation to add an active material inside carbon for use as electrode materials in lithium-ion batteries to improve performance.

The ultracentrifugal processing technology was developed by K&W, a venture firm spun off from the university. The Naoi Lab earlier used the ultracentrifugal (>75000 N) technology to develop a Li-ion capacitor with a negative electrode made from CNFs and lithium titanate (Li₄Ti₅O₁₂, LTO).

Researchers used the technique to add lithium iron phosphate (LiFePO₄) to hollow carbon and to carbon nanofibers—resulting in materials called the “ground cherry type” and “podded pea type” respectively.

In a discharge of 60C, the specific capacities of the ground cherry type and the podded pea type are 131 mAh/g and 113 mAh/g, respectively. The advantage of the ground cherry type is that it has a high performance at a high output and it can be made by using commercially-available carbon black. The podded pea type, on the other hand, has a high specific gravity, making it easy to enhance the energy density.

For an anode material, the researchers incorporated tin oxide (SnO₂) in carbon. Tin oxide is a promising anode material offering increased capacity, but suffers from a short lifecycle due to volumetric changes during charge and discharge.

When a cell was made by using the negative-electrode material and a positive-electrode material using lithium cobalt oxide (LiCoO₂), its specific capacity was 693 mAh/g after 800 cycles, showing no sign of capacity degradation, the university said.

“We found that the ultracentrifugal processing technology enables to add a variety of active materials inside carbon and enhance the performance,” said Kenji Tamamitsu, chief of the Functionality Materials Lab at the Basic Research Headquarters of Nippon Chemi-Con. “We would like to utilize it for battery materials in the future.”