High-Performance Structural Supercapacitors Based on Aligned Discontinuous Carbon Fiber Electrodes and Solid Polymer Electrolytes.

This paper presents an investigation of the potential to use aligned discontinuous carbon fiber dry prepregs as electrodes in structural supercapacitors (SSCs). The high fiber-matrix interfacial bonding of the structural composite was achieved by adopting a solid polymer electrolyte, consisting of poly(vinylidene), lithium triflate, and epoxy. Processing of the SSC was carried out via dip-coating of the polymer electrolyte and then cured using a vacuum bag. The electrochemical performance of the SSCs was measured before and after mechanical loading. The microstructures of the SSCs as-fabricated and damaged under flexural loading were identified by µ-CT imaging. An SSC with a specific capacitance of 0.128 mF/cm2 (11.62 mF/g), a flexural strength of 47.49 MPa, and a flexural modulus of 8.48 GPa has been achieved, demonstrating significant improvements in mechanical properties over those of SSCs based on woven carbon fiber fabric-based electrodes. The mechanical behavior of the supercapacitors was evaluated by both quasi-static and cyclic flexural loading tests. The excellent electrochemical stability of the supercapacitors was validated by a capacitance retention of above 96% under galvanostatic charge-discharge cycling tests. The knowledge gained in this work will benefit future research in the optimization of SSC performance.

Low Tortuous, Highly Conductive, and High-Areal-Capacity Battery Electrodes Enabled by Through-thickness Aligned Carbon Fiber Framework.

Thick electrode with high-areal-capacity is a practical and promising strategy to increase the energy density of batteries, but development toward thick electrode is limited by the electrochemical performance, mechanical properties, and manufacturing approaches. In this work, we overcome these limitations and report an ultrathick electrode structure, called fiber-aligned thick or FAT electrode, which offers a novel electrode design and a scalable manufacturing strategy for high-areal-capacity battery electrodes. The FAT electrode uses aligned carbon fibers to construct a through-thickness fiber-aligned electrode structure with features of high electrode material loading, low tortuosity, high electrical and thermal conductivity, and good compression property. The low tortuosity of FAT electrode enables fast electrolyte infusion and rapid electron/ion transport, exhibiting a higher capacity retention and lower charge transfer resistance than conventional slurry-casted thick electrode design.

Continuous silica coatings on glass fibers via bioinspired approaches.

Simple methods for producing continuous inorganic coatings on fibers have application in multiple technologies. The application of bioinspired strategies for the formation of particulate inorganic materials has been widely investigated and provides routes to inorganic materials under environmentally benign conditions. In this work, we describe the formation of stable and continuous inorganic coatings on glass fibers via the polymerization of silica in the presence of biopolymers. The formation of both organic and inorganic coatings was investigated via X-ray photoelectron spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray analysis. The simple route to silica coatings presented herein could be interesting for the development of functional hybrid fibrous materials suitable for catalytic and sensor applications, given the homogeneous nature of the silica films and the benign conditions employed for film formation.