| Author: | Shang, Jian |
| Title: | High-performance flexible and wearable energy storage fabrics |
| Advisors: | Zheng, Zijian (ITC) |
| Degree: | Ph.D. |
| Year: | 2020 |
| Subject: | Textile fibers -- Technological innovations Textile fabrics -- Technological innovations Wearable technology Hong Kong Polytechnic University -- Dissertations |
| Department: | Institute of Textiles and Clothing |
| Pages: | xix, 126 pages : color illustrations |
| Language: | English |
| Abstract: | Future wearable electronics need safe and high-energy-density wearable energy storage devices (ESDs). Commercial ESDs making use of metal foils as current collectors show high energy density, but the poor mechanical flexibility limits lifetime and raises discomfort in wearable applications. Fabric-based ESDs, on the other hand, are very flexible, but the energy density of entire device is low because of the large mass/volume ratio of fabric current collectors to active materials. As such, the key challenge in this area lies on developing effective strategies to simultaneously increase energy density and keep wearable properties. To address these challenges, three strategies/developments have been proposed in this thesis: Firstly, a new soft electrode fabrication method, soft hybrid scaffold (SHS) strategy, is developed. It addresses the critical challenge in fabricating ultrathick and high-mass hybrid electrodes, where the poor ionic and electrical conductivity significantly limits the energy density. As a proof-of-concept, the flexible, high-massloading and highly conductive hybrid electrodes made of three-dimensional (3D) porous pseudo-material-modified carbon networks are fabricated through SHS strategy. The carbon network provides excellent mechanical stability and electric conductivity, the hierarchically porous structures ensure rapid ionic transport. The wearable asymmetric SHS@SC fabric delivers remarkable areal, gravimetric, and volumetric energy densities of 1.05 mWh cm-2, 11.3 Wh kg-1, and 9.93 Wh L-1, respectively, which are the highest reported energy density of aqueous wearable SCs. This work reports an efficient thick electrode fabrication strategy to realize high energy and maintain mechanical flexibility, simultaneously. Secondly, the ultrathin and superlight conductive fabric with high flexibility is developed. It addresses the critical challenge in fabricating high flexible electrodes, where large volume/mass ratio of current to active materials limits the energy density of entire flexible device. These new Ag, Cu co-coated glass fibre fabric (AgCuGF) and Ni coated glass fibre fabric (NiGF) show mass density of ~4.0 mg, thickness of 30 µm, low sheets resistance of < 1.0 Ω sq-1, great tensile strength of 118 MPa, and excellent flexibility. Besides, the soft current collectors exhibit higher electrochemical stability. The Li/AgCuGF anode shows higher coulombic efficiency of 99.08% in FEC/DEC (3:7, v/v) electrolyte and longer cycle stability for more than 400 hrs striping/plating cycles. Due to the weight of AgCuGF is only 50% of commercial used Cu foil and the thickness of AgCuGF is one order thinner than commonly used CFs, the flexible Li/AgCuGF//NCM/NiGF fabrics show extortionary energy density (353 Wh kg-1, 716 Wh L-1) in the area of flexible ESDs. This work reports a new development of ultrathin and superlight textile current collectors to achieve high energy and flexibility. Thirdly, a new melting strategy for ultrafast and precise-control fabrication of soft zinc anode fabric is reported. It fills the gap between fast preparation and precisely control of zinc size and coating amount and address the challenge in fast fabrication soft zinc electrodes, where large amount of oversized zinc limits the energy density of the entire device. As a proof-of-concept, the fabricated soft zinc anode (Zn/NiGFs) shows nice electrochemical stability in new designed HAOE electrolyte. When pairing with commercially available lithium cathodes (LNMO), the entire hybrid zinc battery delivers highest voltage of 2.35V and high energy density of 98 Wh kg-1 of the entire device. This work presents a new fabrication strategy for precisely controlling of coating amount of zinc, which can obtain high energy and great flexibility. In conclusion, this thesis carries out three strategies/developments to simultaneously obtain high energy and great flexibility. To verify these strategies, three ESDs fabrics have been developed. These wearable energy storage fabrics show higher energy density, great flexibility, and great wearable performance. It is believed that these strategies and results may have significant impact on the fields of flexible and wearable electronics. Besides, it also can be applicable to other energy storage fabric design and development in future. |
| Rights: | All rights reserved |
| Access: | open access |
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