Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/89732
Title: Study on carbon fiber-based electrodes for composite structural batteries
Authors: Fu, Yu
Degree: Ph.D.
Issue Date: 2020
Abstract: Even though carbon fiber is a promising candidate for composite structural batteries due to its multifunction as both electrode and structural reinforcement, its application is limited due to a low capacity. The incorporation of other active materials onto carbon fiber has attracted enormous interest and the capacity of the carbon fiber-based electrodes has been intensively investigated. With composite structural batteries being a kind of multifunctional composites with both energy storage and load bearing capabilities, their successful application has a high requirement on the stability of the carbon fiber electrode/electrolyte interface. Generally, for active materials incorporated onto the carbon fiber electrodes, they are confronted with a serious issue of volume expansion at lithiation/delithiation, which is very likely to lead to the damage of the carbon fiber electrode/electrolyte interface of composite structural batteries. Due to this, care need to be taken with the design of carbon fiber-based electrodes to address the stability issue of active materials-incorporated carbon fiber electrode/electrolyte interface. In this work, various strategies have been developed, aiming to achieve the high-capacity carbon fiber-based electrodes which can also maintain high interfacial stability with polymer when used for fabrication of composite structural batteries. Among these strategies, two typical ones are listed here. (1) The electrode design strategy of "confining active materials within porous substrates" is demonstrated to have high potential to be used in the design of porous carbon cloth (CC)-based electrodes for composite structural batteries. This obtained porous CC not only demonstrates high potential as sulfur hosts for the achievement of high capacity sulfur electrodes, and the much higher discharge capacity of 570 mAh/g at the 100th cycle than the other two CC-based sulfur electrodes confirms the confinement effect of the porous CC on the volume expansion of sulfur. (2) The electrode design strategy of "porosification of two-dimensional active materials flakes" is also demonstrated to have high potential to be used in the design of carbon fiber-based metal oxide electrodes for composite structural batteries. Systematic analysis of temperature-microstructure-electrochemical property relationships leads to the findings that CC@Co3O4 obtained at 500°C (CC@Co3O4-500) demonstrates obvious advantages over CC@Co3O4-450, CC@Co3O4-550 and CC and delivers a capacity of 3.10 mAh/cm2. In situ TEM characterizations have also confirmed the small volume expansion of nanoflakes. Therefore, another strategy for the simultaneous capacity enhancement and volume expansion confinement of electrodes for structural batteries has also been confirmed. These strategies put forward in this thesis are aimed to simultaneously achieve high capacity and interfacial stability of composite structural batteries, which provide a clear guideline on the electrode design for high-capacity composite structural batteries. Therefore, this work provides a new perspective to enhance the performance of composite structural battery. Through the sophisticated electrode design, structural batteries are expected to not only have high capacities but high interfacial stabilities with polymer. Only when small volume expansion at the carbon fiber electrode/electrolyte interface is realized at the same time with high capacity of carbon fiber-based electrodes, the high-capacity and high-interfacial stability composite structural batteries can be constructed.
Subjects: Electric batteries -- Materials
Energy storage -- Materials
Hong Kong Polytechnic University -- Dissertations
Pages: ix, 195 pages : color illustrations
Appears in Collections:Thesis

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