Development of two type of Cobalt-free oxide for use in Lithium Ion Secondary Batteries
AIST (Advance Industrial Science and Technology) in Japan made an announcement on development of cobalt-free cathode materials to be used in Lithium Ion Secondary Batteries. Currently Nickel-Metal-Hydride batteries are the main power source for electrical vehicles, however use of lithium ion secondary batteries is gaining in popularity mostly due to their competitiveness in regard to their energy density which is the electrical energy charged and discharged per unit weight or volume. Although, lithium ion secondary batteries have been developed for use in such products as cellular phones and note-PCs their wider use in electrical vehicles solely rest in improving their performance and reducing their production cost as well as their safety. One way to achieve this cost reduction would be in replacing the costly existing constituent materials such as lithium oxide and Cobalt which used as cathodes, anodes and electrolytes with less expensive materials such as iron with minimum effect on overall performance of batteries. The current cost of iron oxide, manganese and titanium are approximately 1/10. 1/8 and 1/4 respectively in comparison to the cost of cobalt oxide. Based on this AIST has been studying use of lithium manganese oxide that contains iron and lithium in such batteries due to their abundance, low cost and low toxicity. This is not a first time that AIST has developed a complex oxide for cathode containing iron, manganese and titanium, but up to now the disadvantage of such materials is been on their low average discharge voltage (3.0 Volt) in comparison to average discharge voltage of existing materials which is 4.0 volts but AIST by addition of nickel to iron containing lithium manganate has managed in improving the average discharge voltage offering an inexpensive alternative to cobalt. The cathode materials have been manufacture through co-precipitation–hydrothermal reaction–calcination method developed at AIST. Through co-precipitation process, the aqueous solution of iron nitrate, nickel nitrate, and manganese chloride is cooled and then added in a drop wise fashion into the aqueous solution of lithium hydroxide. Ethanol was added to the lithium hydroxide solution as antifreeze liquid. Iron, nickel, and manganese containing co-precipitate were prepared through the wet air oxidation of the precipitate at room temperature. Through hydrothermal reaction process, the co-precipitate is put into distilled water containing lithium hydroxide, potassium hydroxide, and potassium chlorate, and is hydrothermally-processed for 48 hours in an autoclave (temperature: 220 °C, pressure: approximately 2 MPa). Finally, through calcination process, t he hydrothermally processed co-precipitate is dispersed in the solution of lithium hydroxide; it is crushed after drying. The material is calcined for 20 hours in air or in a nitrogen flow in an electric furnace at 700 or 750 °C. The product is crushed, washed with distilled water, filtrated, and dried to prepare a cathode material. The new technique enables effective utilization of iron because it requires a low calcination temperature, and ensures a uniform distribution of the transition metal ions. AIST is planning to work further on the fabrication process in order to supply sample of the batteries to battery manufacturers by early 2010.
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[...] use of rechargeable Lithium-ion batteries in such products as cellular phones and notebook PC is reaching commodity level, extensive research [...]