3D Architected Solid-State Lithium-Ion Battery

Abstract

Lithium-ion batteries are more and more widely used in portable electric applications with high power demand. Most approaches to high-power batteries gain improvement in power density on the cost of energy density. The rapid development in additive manufacturing technique in the past decade has provided a promising pathway to achieve higher power density without sacrificing energy density, where the ion diffusion distance between electrodes is minimized by improving electrode architectures. Recent approaches in 3D lithium-ion batteries with interdigitated configuration demonstrated new electrode fabrication methods through direct ink-writing. Although the power densities were improved, the large portion of organic materials in electrode inks for adhesion purpose became the “dead weight” in batteries, and also decreased the electrical conductivity of electrodes. In this work, we demonstrate a new method to fabricate 3D interdigitated lithium-ion battery with architected carbon anode, lithium cobalt oxide (LCO) cathode, and gel polymer electrolyte. An oligo(ethylene glycol)-based gel polymer electrolyte was polymerized in-situ when the resin was in direct contact with the electrodes to achieve a highly adherent interface. Stereolithography (SLA) technique was used to 3D print an architected electrode structure with feature size less than 200 μm using an acrylate-based photoresin. The printed polymer structure went through a pyrolysis process, and 3D architected carbon anode was obtained. The architected LCO anode was also fabricated using an SLA system, but through a “swell-in” — calcination method, where lithium and cobalt ions were swelled into a 3D printed hydrogel, and after a calcination process the 3D architected LCO cathode was obtained. The electrodes fabricated in this work have overcome difficulties in reducing the portion of organic materials in 3D printed electrodes, resulting to a 3D interdigitated lithium-ion battery with large percentage of active materials, high electrical conductivity in electrodes, and small ion diffusion distance between electrodes.