Multiscale simulation and experimental investigation of a spark plasma sintered mxene-polypyrrole electrode for sodium-ion battery.
Chidi, Ezika, Anthony
Chidi, Ezika, Anthony
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Abstract
The study of nanotechnology has produced several high-performance conductive polymers and nanomaterials, including MXene (MX) and Polypyrrole (PPy), which have significant potential for applications in energy storage. Consequently, the emphasis of this thesis is on the utilization of high-performance conductive polymers and nanomaterials, particularly MX and PPy, for energy storage applications. Spark plasma sintered (SPS) MX-Ti3C2Tx-PPy (MX-PPy) nanocomposites are the subject of the investigation through multiscale modeling, fabrication, and characterization. The particle size, thermal stability, specific capacity, structural analysis, surface morphology, mechanical properties, electrical conductivity, and chemical characteristics of the SPS MX-PPy nanocomposites were investigated. The first step in the investigation of the energy storage potential of MX-PPy nanocomposites is density functional theory (DFT) modeling. Based on its chemical stability, metallicity, and capability to absorb Na-ions with low adsorption energy, which can lead to effective sodium-ion discharge, the results show that the Ti3C2Tx-MX-PPy nanocomposite is a viable sodium-ion anodic hybrid electrode material for battery usage. The elastic strength and the electrical conductivity of the MX-PPy electrode were calculated by using a Finite Element model. The calculated results from the finite element simulations, representing the electrical conductivity and the elastic modulus response variables were then optimized by using the Response Surface Methodology (RSM), based on the results of the Finite Element simulations. The results of the optimization analysis show that the elastic modulus and the electrical conductivity might be modified with maximum optimum values. The fabricated electrode with MX of 0.5 mass fraction, exhibits the preferred ductility, total loss in weight of ~ 0.9% at 450oC, optimum specific capacity of 271 mAh/g at 50 mV/s scan rate, and best electrical conductivity of approximately 352.69 S/m. According to the TEM study, the particle sizes of each fabricated electrode range between 50 to 200 nm. Meanwhile, for the morphological analyses of the nanocomposites, PPy and MX nanosheets combined to give a nanoarchitechtured porous structure with a significant surface area. The thesis concludes by highlighting the enormous potential of hybridized MX and PPy for energy storage applications, notably in the creation of metal-ion batteries. Besides, it underscores the use of response surface methods for finding the optimal properties of MX-PPy nanocomposites.
Description
This research dissertation has been submitted to partially fulfil the degree requirements, Doctor of Engineering: Polymer Technology in the Department of Chemical, Metallurgical and Materials Engineering within the Faculty of Engineering and the Built Environment at the Tshwane University Of Technology.
Date
2023-08-01
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Tshwane University of Technology
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Keywords
DFT, DOE, Electrode, Energy storage, Finite element, MX, Nanoarchitectonics, PPY, RSM