Processing of Composite Carbon Materials and Solid Electrolytes for Supercapicitor Energy Storage

Orisekeh, Kingsley (2022-02-02)

Main Theses


These research works presents the results of a combined theoretical, experimental and statistical study of processing of composite carbon materials and solid electrolytes for supercapacitor energy storage The need for flexible energy storage devices has stimulated the interest in the development of nanostructures in supercapacitors for energy storage. A hydrothermal method is used to optimize the growth of α-Fe2O3 nanoparticles on carbon cloth (CC) and activated carbon cloth (ACC). The resulting composition, morphologies and microstructures displayed interesting features that are suitable as electrodes material for electrochemical capacitors. These are integrated as binder-free, symmetric device, which were then assembled and tested. The device assembled with the activated carbon cloth exhibited higher electrochemical performance (specific capacity of 295.56 mAhg-1, specific energy of 37 WhKg-1and specific power of 0.5 kWKg-1 in a 3 M KOH electrolyte at 1 A g-1. The device also had good capacitance retention of 96.6 % after 10000 charge-discharge cycles. The implications of the results are discussed for potential applications of the α-Fe2O3-ACC in supercapacitors for energy storage systems that address global energy needs. Similarly, the conventional lithium ion batteries use liquid electrolytes that are chemically unstable due to the presence of carbonates, which are highly volatile and flammable, creating a significant safety risk. Therefore, the need for the development of solid state electrolytes (SSEs) that are safe, environmentally friendly, with robust mechanical properties. In this work, the solid polymer blend is explored using a mixture of a polymer matrix of polyvinyl pyrrolidone (PVP)/polyvinyl alcohol (PVA) and lithium perchlorate salt (LiClO4). The produced films are characterized using a Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Fourier Transform Infra-Red (FTIR). The mechanical properties of the flexible films are also measured using nanoindentation techniques, statistical deconvolution mapping, tensile tests and fracture toughness measurements. (Young’s modulus of 6.87 GPa, Hardness of 1.3 GPa, Tensile strength of 4.3 MPa and Fracture toughness of 0.81 MPa.m0.5) The implications of the results are then discussed for potential applications of robust solid polymer blends-based electrolytes.