No. 332: A solid solution cathode material for the next-generation lithium battery (October 20, 2011)

KRI (formerly, Kansai Research Institute) in Kyoto developed a solid solution cathode material that can realize a high capacity in the discharge and charge time of the practical level. The company wishes to put it into practical use as a material for the secondary lithium-ion battery of the next-generation by minimizing the crystal dimensions and optimizing the particle configuration. The solid solution has two times higher theoretical capacity than the existing cathode material, but it cannot secure a high capacity needed for the acceleration of a vehicle and start-up of a PC.

The newly developed product is a manganese composite oxide (solid solution of Li2MnO32 and LiMo2) 25 nanometers in diameter. The existing solid solution cathode materials are about 200 nanometers in diameter, but the new material is 25 nanometers in diameter. It is capillary and long needle-shaped several hundreds nanometers long. The new material creates a capacity of 250-300 milliamperes per gram, about two times more capacity of the existing secondary lithium-ion battery, in five hours. In addition, the company claims that the new materials can retain about 80% of the capacity in the 30 minute discharge and charge. The synthetic process of a solid solution material needs mixing and thermal treatment of such materials as manganese compound, cobalt salt, nickel salt, and lithium salt. The research team successfully controlled the figure by applying the molten salt method that adds lithium salt in large excess and the thermal process at a low temperature, in addition to changing the figure of the manganese compound.