MONOLITHICALLY INTEGRATED, PRINTED SOLID-STATE RECHARGEABLE BATTERIES WITH AESTHETIC VERSATILITY

Abstract

With the advent of flexible/wearable electronics and Internet of Things (IoT) which are expected to drastically change our daily lives, printed electronics has drawn much attention as a low cost, efficient, and scalable platform technology. The printed electronics requires so-called “printed batteries” as a monolithically integrated power source that can be prepared by the same printing processes. The printing technology is a facile and reproducible process in which slurries or inks are deposited to make pre-defined patterns. The slurries/inks should be designed to fulfill requirements (such as rheology and particle dispersion) of the printing process. Development of printed batteries involves the design and fabrication of battery component slurries/inks. Most studies of the printed batteries have been devoted to the development of printed electrodes. However, in order to reach an ultimate goal of so-called “all-printed-batteries”, printed separator membranes and printed electrolytes should be also developed along with the printed electrodes. The objective of the research presented in this dissertation is to develop materials and printing-based strategies to fabricate a new class of monolithically integrated, printed solid-state rechargeable batteries with aesthetic versatility to address the aforementioned formidable challenges, with particular attention to comprehensive understanding of colloidal microstructure and rheological/electrochemical properties of printable battery component slurries/inks. Colloidal microstructure of the battery component slurries/inks is expected to play a viable role in realizing the monolithically integrated printed batteries, as it can significantly affect fluidic characteristics of the slurries/inks and also electrochemical properties. In particular, our interest is devoted to concentrated colloidal gels that exhibit thixotropic fluid behavior (i.e., they readily flow upon being subjected to external stress and quickly return to a quiescent state). Driven by such unique viscoelastic response, the slurries/inks show good dimensional stability and shape diversity on various objects. In addition to the viscoelasticity control of the slurries/inks, the interaction between colloidal conductive particles should be carefully tuned in order to secure facile ion and electron transport pathways. When the attractive interaction is dominant, the colloidal particles tend to be aggregated in disordered and dynamically arrested forms, yielding the highly reticulated three-dimensional networks. In an electrochemical system, these interconnected conductive particle networks act as electron conduction channels while the interstitial voids formed between the particle networks allows ion transport. In this dissertation, as a proof-of-concept, lithium-ion batteries (LIBs), electric double layer capacitors (EDLCs), and Zn-air batteries are chosen to explore the feasibility of this approach. The resultant solid-state printed batteries are fabricated through various printing processes such as stencil printing, inkjet printing, and pen-based writing. Notably, the printed batteries can be seamlessly integrated with objects or electronic devices, thus offering unprecedented opportunities in battery design and form factors that lie far beyond those achievable with conventional battery technologies.