Flexible hybrid electrochromic zinc battery

• Main Author: Poh, Wei Church
• Other Authors: Lee Pooi See
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Materials::Energy materials; Engineering::Materials::Composite materials; Engineering::Materials::Organic/Polymer electronics
• Online Access: https://hdl.handle.net/10356/168635
• Institution: Nanyang Technological University

Electrochromic batteries, with simultaneous colour-changing and energy-storage capabilities, have great commercial interest, ranging from renewable energy systems, electric vehicles to consumer electronics. Recently, the development of these devices has skewed towards those that could conform to non-planar and curvature surfaces, as to cater to the rising demand for futuristic wearables such as energy-saving wearable displays and expressive garments. However, the current bottleneck in conformable devices lies in their poor mechanical durability due to limited availability of suitable materials. In this dissertation, efforts are invested in developing a flexible electrochromic zinc battery based on innovative designs and selection of materials. The undertaking was first approached by studying the prospect of chemically anchored electrochromic materials via electropolymerization process. Particularly, electropolymerizable iron-centred coordination polymer has been deployed, showing not only effective in manipulating thicknesses and surface morphologies, but also demonstrated robust electrochromic and cathodic performances. Despite these promising features, the construction of flexible devices is still limited by a lack of suitable electrolyte and substrate. Traditional liquid and gel electrolytes are not competent due to their poor environmental stability, leakage tendency and poor processability. Considering the low oxygen solubilities of poly(ionic liquid)s, solid-state ionogels were developed via facile in-situ photopolymerization approach, establishing electrolytes with high transparency, stretchability and excellent physicochemical stabilities (e.g., thermal, electrochemical and air stability). Benefitting from the versatility of the materials, they were modified to tailor for an electrochromic Zn battery. By coupling with zinc mesh anode, the compatibilized materials were readily assembled on an ultra-thin-ITO glass, realizing a flexible EC battery device that delivers a capacity of 19.3 mAh m-2 at 0.01 mA cm-2 which could be bent repeatedly with minimal damage and powering up a wireless portable device, paving the road towards the advancement of wearable electronics.