High-areal capacity microbatteries from symmetrical interdigitated 3D nanowire network electrodes

Details

Supervisors

Piraux, Luc ; Vlad, Alexandru

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil en chimie et science des matériaux

Abstract

The inability of state-of-the-art microbatteries to simultaneously meet the performance and size requirements for modern-day, constantly miniaturizing microelectronic devices has created an impetus to finding better materials and designs capable of fulfilling these requirements. Thin film batteries are ubiquitous, but the presence of small active materials precludes their use in high-energy applications; on the other hand, while thick-film batteries are capable of providing adequate energy for many of these devices, long and tortuous ion diffusion pathways limit their use for high-power applications. This work explores a strategy of decoupling power and energy capabilities of microbatteries by using functionalized three-dimensional interconnected core-shell nanowire networks as the electrodes’ active material in a 3D microbattery. Specifically, it presents the foremost attempt at fabricating a symmetrical microbattery with interdigitated electrodes from polyaniline, a conducting polymer, whose electrochemistry allows its use in symmetrical batteries; the interdigitated architecture of the electrodes allows its compact integration on a single substrate, consistent with the requirements for microelectronics applications. The Pt nanowire network was prepared by template-assisted electrodeposition; the nanowires and thin films were functionalized with the active material, polyaniline, by electroless deposition, and the interdigitated architecture was effected by laser ablation of the as-grown Pt nanowire network. For the same thickness of active material, the thin-film microbattery presents an areal capacity of 0.09 μAh per square centimeter, while the 3D microbattery presents 2.7 μAh per square centimeter, 30 times higher than the thin film’s, consistent with the expectations of increased mass loading. The thick-film battery, despite having 40 times more material than the thin film, presents an areal capacity of only 0.45 μAh per square centimeter, evidence of limitations by longer ion diffusion pathways. The volumetric capacity of the 3D battery is compared with similar batteries in the literature, and it is found to compare favourably, with even better cycle characteristics. This work is a proof of concept of working symmetrical batteries with interdigitated electrodes based on a 3D core-shell nanowire network architecture.