Invited
NANOMATERIALS FOR HIGH-ENERGY-DENSITY 3D-MICROBATTERIES

Improvements in microbatteries are closely linked to the development of novel battery designs and materials. Recent projects of our research group have had as their aim the development of 3D-microbatteries (3D-MB) on perforated silicon and glass microchannel plates. 3D-microbatteries comprise a nickel or gold current collector, a cathode, a composite-polymer electrolyte (CPE) and a lithiated or lithium-free graphite anode. All layers other than the anode are thin conformal films, formed by electrochemical means in such a way that they follow the contours of all available hollow surfaces. Thin-film nanosize-particle cathodes were electrodeposited on planar and 3D-substrates. The morphology and composition of the cathodes were controlled by varying the operating parameters, such as current density, pH and temperature of the electrolyte. The semi-3D-MBs with electrodeposited CuS_x cathodes deliver a pulse power of 125mW/cm² and have a capacity of 1.5-2.5mAh/cm². The power capability of electrophoretically deposited modified LiFePO₄ cathodes is 225mAh/cm². Composite solid polymer-in-ceramic electrolyte films prepared by EPD showed, at near-ambient temperatures, a value of s_bulk of about 0.5mS/cm, which almost does not change on being heated to 100°C. The values of both the specific energy and specific power obtained in this study are far greater than those achieved for other 3D-MB architectures. The experimental results of SEM, XRD, XPS and TOF-SIMS characterizations of nanoparticle cathode materials, polymer-in-ceramic electrolytes and electrochemical tests of 3D microbatteries will be presented.

A novel approach of using 3D-printing technology for the fabrication of 3D-MBs will be discussed.