Author : Marianna Uceda
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (119 download)
Book Synopsis Highly Homogeneously Structured Lithium-ion Storage Electrodes Via Electrophoretic Deposition by : Marianna Uceda
Download or read book Highly Homogeneously Structured Lithium-ion Storage Electrodes Via Electrophoretic Deposition written by Marianna Uceda and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Improving lithium-ion battery performance is key in facilitating a green sustainable future. This has led to nanosizing of active materials as means to improve their conductivity by reducing the lithium-ion diffusion length. However, nanomaterials introduce a new challenge during the casting stage of lithium-ion battery electrode fabrication. This technique is unsuited for handling both nanosized and 2D-shaped materials as they introduce rheological challenges. Additionally, the current commercially available casting technique requires the use of a toxic and expensive organic solvent. Thus, the focus of this work was to investigate and design an alternative coating process using electrophoretic deposition (EPD). The work comprises three studies.In the first study, carbon-coated lithium titanate (LTO) nanoparticles and acetylene black were successfully made into highly-conductive composite anodes via EPD employing styrene butadiene rubber (SBR) as binder in an appropriately selected acetonitrile/water medium. The investigation characterized and optimized the effect of current density on particle movement and deposit growth producing thick mesoporous films on aluminum substrate. The EPD electrode performance was compared to electrodes prepared via the conventional tape-casting. For EPD electrodes, SEM imaging and EDS mapping showed excellent intermixing of carbon components and the active material. Via photoemission electron microscopy (PEEM) coupled with X-ray absorption near edge structure (XANES) it was revealed the SBR binder to be well dispersed within the coating, which translated to the electrode achieving superior rate cycling performance thanks to enhanced conductivity enabled by the hetero-assembling power of electrophoretic deposition.In the second study, EPD was innovatively applied to fabricate binder-less nanolayered lithium titanate and reduced graphene oxide (rGO) composite coatings as high-performance Li-ion anodes. This was accomplished by electrophoretically depositing 2D shaped lithium titanate hydrate (LTH) and graphene oxide (GO) precursors and subsequent high temperature reducing annealing to induce the topotactic transformation of LTH into LTO and GO into the so-called rGO. As graphene is difficult to successfully suspend, using the functionalized precursor circumvented this problem. The EPD electrodes are compared to conventionally prepared electrodes with rGO and carbon black. Cross-sectional imaging and EDS mapping showed the EPD electrodes contained a homogeneous coating with the rGO acting as a conductive medium and binder which helped organize the LTO nanosheets into a well built and adherent film. As a result, the EPD nanolayered electrode was found to exhibit superior electrochemical performance in terms of power capability, cyclability and impedance when compared to conventionally prepared electrode. The final study featured titanium niobate (TNO, TiNb2O7), this material is a promising replacement anode material for LTO with the potential to deliver higher capacities. Binder-less TNO/rGO electrodes were made through adapting the EPD method developed for the second study – co-depositing TNO and GO followed by high temperature annealing to induce GO to rGO transformation. The final composition of EPD coatings contained 18 wt% rGO which was compared to conventionally prepared electrodes containing 18 wt% rGO and 10 wt% rGO. The rGO was determined in addition to acting as binder and conductive component to have pseudocapacitive contributions to lithium-ion storage. The improved homogeneity in the EPD electrodes allowed better performance in terms of capacity level and retention, i.e. reduced capacity fade in comparison to PVDF-built electrodes of similar composition. Overall, through these integrated electrode construction and electrochemical performance analysis studies, EPD is shown to be a superior coating technology with great application potential in manufacturing advanced LIB electrodes"--