In this dissertation, diverse strategic designs of energy storage materials were explored. The main aims were: affordability and high-performances.
I) on eco-efficient synthesis of 1D intercalation compounds was described; a low-temperature aqueous solution synthesis of nanostructured 1D (molybdenum trioxide) MoO3 was developed. Subsequent self-assembly of the fibers to form large-scale freestanding films in paper-like structure was achieved without any assistance of organic compounds. Indeed, the whole processes, from synthesis to assembly of obtained materials, do not require toxic organic solvents. As an example of the application of our synthesized materials, 1D MoO3, having the width in 50−100 nm, with the length in micro scale, and with thickness in ~10 nm, and the macroscopic oxide papers consisting of 1D MoO3 and carbon materials were applied as the cathode and anode to lithium-ion batteries, respectively. As a cathode material, the 1D MoO3 showed a high rate capability with a stable cycle performance up to 20 A/g due to a short Li+ diffusion path along [101] and less grain boundaries which were achieved by the precise nanostructure control. As an anode material, the composite paper showed the first specific discharge capacity of 800 mAh/g. These findings above indicate not only an affordable, eco-efficient synthesis and assembly of nanomaterials but also show a new attractive strategy towards a possible whole aqueous process for a large-scale fabrication of freestanding oxide papers without any toxic organic solvent.
II) a new energy storage principle using polymeric frameworks was investigated. The new energy storage concept can deliver both high power and high energy. This is because of the novel energy storage nature of designed artificial polymeric frameworks which is different from classical energy storage mechanisms. The main novel discovery was as follows; since CTF-1 is linear stepwise p- and n-dopable polymer, therefore, this framework can store energy as a cathode in the wide working potential with both cation below 3 V versus Li/Li+ and anion above 3 V versus Li/Li+ by Faradaic reaction. Due to this feature, CTF-1 can store high specific capacity of 540 mAh/g. As the result the new energy storage concept which can deliver both high power and high energy was discovered by using a novel polymeric cathode. Unlike typical organic electrodes in sodium battery systems, the CTF-1 has a high specific power of 10 kW/kg, specific energy of 500 Wh/kg, and over 7,000 cycle life retaining 80 % of its initial capacity in half-cells. Indeed, all-organic energy storage devices based on CTF-1 suggested a possibility towards an extremely affordable energy storage device. Recent research on such artificial polymeric frameworks suggests their huge variability to utilize different functional structures which could even further increase power and energy even further when using different starting monomers. This would significantly extend the possibilities of electrical energy storage devices for a sustainable society based on our result. From this point of view, our research strategy which combined the experimental and theoretical study would be a model for further development of this field.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:27454 |
| Date | 19 December 2013 |
| Creators | Sakaushi, Ken |
| Contributors | Kaskel, Stefan, Eckert, Jürgen, Antonietti, Markus, Eychmüller, Alexander, Technische Universität Dresden |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
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