GIANLUCA LONGONI
University of Milan – Bicocca 
Materials Science Department 

Battery printing: a thrilling opportunity paving the way for shape-conformable, flexible and miniaturized energy storage

Via R. Cozzi 55, 20125, Milan, Italy 

Abstract

Sensors, wearable electronics, internet of things, miniaturized electronic devices, low-maintenance medical implants, all these cutting-edge technologies have one thing in common: they need a reliable source of energy to work both properly and efficiently. Most likely, this source will be a rechargeable battery sufficiently small in order not to restrict portability and comfort during use. With the expected exponential diffusion of electronic apparatus embedded in everyday life objects wired together and exchanging information, power sources will be required to interfere the least with portability and miniaturization. This contribution intends to give an insight into most recent scientific advancements done in flexible and
shape-conformable electrodes manufacturing. Alternative and innovative ways of assembling small-volume lithium-ion batteries, based on screen-printing, ink-jet, spry-printing and 3D-printing, will be illustrated and a line of research aimed at solving challenges of a one-pot preparation of a composite solid-state electrochemical cell will be sketched as well.

TOWARDS BATTERIES MINIATURIZATION AND PRINTING

Technologic gizmos of daily use, such as smartphones, tablets, laptops, cameras and smart-watches, rely on prismatic or cylindrical lithium-ion cells of hundreds to thousands milliamperehour of stored capacity. Nevertheless, their low shape conformability, derived from roll-to-roll manufacturing process, imposes strict limits to integration in more sophisticated devices, for which miniaturization rather than extremely high capacities, is fostered. Owing this, a substantial change in how energy reserves are conceived has to be sought. An opportunity comes from the dead weight that every small electronic device carries, that is the electronics casing. Taking advantage from that, fully integrated cells provided with shape conformability, will state the new trend soon, overcoming conventional cell components and manufacturing processes. In particular, flexibility and stretch ability will be demanded to battery cells to adapt to smart watches straps, curved case surfaces, smart glasses frame (Figure 1) or implanted medical devices, just to cite few possibilities.

It is obvious that adaptation to exotic shapes will ...