Inks Development for 3D Printing Cathode of Li-Ion Microbatteries ^†

Due to the demand for wearable and implantable microelectronic devices (MED), there is growing interest in the development of thin-film lithium-ion microbatteries (LiBs) with high-energy density. The high cost of production is an issue restraining thin-film LiBs’ wide application. Inkjet printing is a method of applying materials to the substrate surface: ink droplets formed on piezoelectric nozzles fall on the substrate, whereafter evaporation of the solvent thin layer of film is formed. The proposed technology can simplify the production of LiBs for MED and reduce their cost. The present work reports the results of inkjet printing 3D cathode development for LiBs. The 3D printed cathodes were produced using synthesized Li-rich cathode material (Li_1.2+xMn_0.54Ni_0.13Co_0.13O₂, 0 < x < 0.05) which has a larger capacity (>250 mAh/g) in comparison with the materials used in modern lithium-ion cells. For LiB electrode printing, the non-aqueous solvent-based inks were used. The prepared cathode material was dispersed in N-methyl-2-pyrrolidone. The effect of various additives such as ethylene glycol, diethylene glycol, propylene glycol on the viscosity and stability of the ink was studied. Inkjet printing was performed with the use of a Dimatix Material Printer 2831. Substrate temperature, number of layers and other parameters were varied to determine the optimal printing conditions.