Preparation and characteristics of LiCoO2 paste electrodes for lithium ion micro-batteries

The thick film electrodes (cathode) have been developed via screen printing using LiCoO₂ paste to improve the discharge capacity of lithium ion micro-batteries. The LiCoO₂ pastes were formulated using the mixtures of LiCoO₂ powder as a functional material, carbon black as a conducting agent, ethyl cellulose and terpineol as a vehicle, and Emphos PS-21A as a dispersant. Depending on the amount of carbon black, the average and maximum surface roughnesses varied from 0.54 to 1.00 μm and 6.2 to 18.7 μm respectively. The internal resistance in the paste electrodes could also be controlled to 120 KΩcm⁻² by the addition of carbon black in the pastes. The thickness of the printed film is independent of the paste composition, but it decreased from 15 to 6 μm with the increase in screen mesh number from 250 to 500. The initial specific discharge capacity of the printed cathode which was prepared using the mixture Ag-coated LiCoO₂ powder improved to 180 μAhcm⁻².