Matching Items (7)
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- All Subjects: Lithium ion batteries
- All Subjects: Lithium
- Creators: Sieradzki, Karl
- Member of: Theses and Dissertations
- Member of: Barrett, The Honors College Thesis/Creative Project Collection
Description
This work investigates in-situ stress evolution of interfacial and bulk processes in electrochemical systems, and is divided into two projects. The first project examines the electrocapillarity of clean and CO-covered electrodes. It also investigates surface stress evolution during electro-oxidation of CO at Pt{111}, Ru/Pt{111} and Ru{0001} electrodes. The second project explores the evolution of bulk stress that occurs during intercalation (extraction) of lithium (Li) and formation of a solid electrolyte interphase during electrochemical reduction (oxidation) of Li at graphitic electrodes. Electrocapillarity measurements have shown that hydrogen and hydroxide adsorption are compressive on Pt{111}, Ru/Pt{111}, and Ru{0001}. The adsorption-induced surface stresses correlate strongly with adsorption charge. Electrocatalytic oxidation of CO on Pt{111} and Ru/Pt{111} gives a tensile surface stress. A numerical method was developed to separate both current and stress into background and active components. Applying this model to the CO oxidation signal on Ru{0001} gives a tensile surface stress and elucidates the rate limiting steps on all three electrodes. The enhanced catalysis of Ru/Pt{111} is confirmed to be bi-functional in nature: Ru provides adsorbed hydroxide to Pt allowing for rapid CO oxidation. The majority of Li-ion batteries have anodes consisting of graphite particles with polyvinylidene fluoride (PVDF) as binder. Intercalation of Li into graphite occurs in stages and produces anisotropic strains. As batteries have a fixed size and shape these strains are converted into mechanical stresses. Conventionally staging phenomena has been observed with X-ray diffraction and collaborated electrochemically with the potential. Work herein shows that staging is also clearly observed in stress. The Li staging potentials as measured by differential chronopotentiometry and stress are nearly identical. Relative peak heights of Li staging, as measured by these two techniques, are similar during reduction, but differ during oxidation due to non-linear stress relaxation phenomena. This stress relaxation appears to be due to homogenization of Li within graphite particles rather than viscous flow of the binder. The first Li reduction wave occurs simultaneously with formation of a passivating layer known as the solid electrolyte interphase (SEI). Preliminary experiments have shown the stress of SEI formation to be tensile (~+1.5 MPa).
ContributorsMickelson, Lawrence (Author) / Friesen, Cody (Thesis advisor) / Sieradzki, Karl (Committee member) / Buttry, Daniel (Committee member) / Venables, John (Committee member) / Arizona State University (Publisher)
Created2011
Description
Lithium-ion batteries can fail and catch fire when overcharged, exposed to high temperatures or short-circuited due to the highly flammable organic liquid used in the electrolyte. Using inorganic solid electrolyte materials can potentially improve the safety factor. Additionally, nanostructured electrolyte materials may further enhanced performance by taking advantage of their large aspect ratio. In this work, the synthesis of two promising nanostructured solid electrolyte materials was explored. Amorphous lithium niobate nanowires were synthesized through the decomposition of a niobium-containing complex in a structure-directing solvent using a reflux method. Lithium lanthanum titanate was obtained via solid state reaction with titanium oxide nanowires as the titanium precursor, but the nanowire morphology could not be preserved due to high temperature sintering. Hyperbranched potassium lanthanum titanate was synthesized through hydrothermal route. This was the first time that hyperbranched nanowires with perovskite structure were made without any catalyst or substrate. This result has the potential to be applied to other perovskite materials.
ContributorsYang, Ting (Author) / Chan, Candace K. (Thesis advisor) / Crozier, Peter A. (Committee member) / Sieradzki, Karl (Committee member) / Arizona State University (Publisher)
Created2012
Description
There is a fundamental attractiveness about harnessing renewable energy in an age when sustainability is an ethical norm. Lithium ion batteries and hydrogen fuels are considered the most promising energy source instead of fossil fuels. This work describes the investigation of new cathode materials and devices architectures for lithium ion batteries, and photocatalysts for their usage in water splitting and waste water treatment.
LiCoO2 and LiNi1/3Mn1/3Co1/3O2 were exfoliated into nanosheets using electrochemical oxidation followed by intercalation of tetraethylammonium cations. The nanosheets were purified using dialysis and electrophoresis. The nanosheets were successfully restacked into functional cathode materials with microwave hydrothermal assistance, indicating that new cathodes can be obtained by reassembling nanosheets. This method can pave the way for the synthesis of materials with novel structures and electrochemical properties, as well as facilitate the fabrication of hybrid and composite structures from different nanosheets as building blocks.
Paper folding techniques are used in order to compact a Li-ion battery and increase its energy per footprint area. Full cells were prepared using Li4Ti5O12 and LiCoO2 powders deposited onto current collectors consisting of paper coated with carbon nanotubes. Folded cells showed higher areal capacities compared to the planar versions. Origami lithium-ion battery made in this method that can be deformed at an unprecedented high level, including folding, bending and twisting.
Spray pyrolysis was used to prepare films of AgInS2 with and without Sn as an extrinsic dopant. The photoelectrochemical performance of these films was evaluated after annealing under a N2 or S atmosphere with different amounts of the Sn dopant. Density Function Theory (DFT) was used to calculate the band structure of AgInS2 and understand the role of Sn doping in the observed properties.
Cr(VI) removal was investigated using multiple oxide photocatalyst and additives. The efficiency for Cr(VI) removal using these photocatalysts was investigated in synthetic neutral and alkaline water, as well as in cooling tower blowdown water. While sulfite alone can chemically reduce Cr(VI), sulfite in combination with a photocatalyst resulted in faster and complete removal of Cr(VI) in 10 min using a SO32−/Cr(VI) ratio >35 in pH ∼ 8 solutions.
LiCoO2 and LiNi1/3Mn1/3Co1/3O2 were exfoliated into nanosheets using electrochemical oxidation followed by intercalation of tetraethylammonium cations. The nanosheets were purified using dialysis and electrophoresis. The nanosheets were successfully restacked into functional cathode materials with microwave hydrothermal assistance, indicating that new cathodes can be obtained by reassembling nanosheets. This method can pave the way for the synthesis of materials with novel structures and electrochemical properties, as well as facilitate the fabrication of hybrid and composite structures from different nanosheets as building blocks.
Paper folding techniques are used in order to compact a Li-ion battery and increase its energy per footprint area. Full cells were prepared using Li4Ti5O12 and LiCoO2 powders deposited onto current collectors consisting of paper coated with carbon nanotubes. Folded cells showed higher areal capacities compared to the planar versions. Origami lithium-ion battery made in this method that can be deformed at an unprecedented high level, including folding, bending and twisting.
Spray pyrolysis was used to prepare films of AgInS2 with and without Sn as an extrinsic dopant. The photoelectrochemical performance of these films was evaluated after annealing under a N2 or S atmosphere with different amounts of the Sn dopant. Density Function Theory (DFT) was used to calculate the band structure of AgInS2 and understand the role of Sn doping in the observed properties.
Cr(VI) removal was investigated using multiple oxide photocatalyst and additives. The efficiency for Cr(VI) removal using these photocatalysts was investigated in synthetic neutral and alkaline water, as well as in cooling tower blowdown water. While sulfite alone can chemically reduce Cr(VI), sulfite in combination with a photocatalyst resulted in faster and complete removal of Cr(VI) in 10 min using a SO32−/Cr(VI) ratio >35 in pH ∼ 8 solutions.
ContributorsCheng, Qian (Author) / Chan, Candace Kay (Thesis advisor) / Sieradzki, Karl (Committee member) / Crozier, Peter (Committee member) / He, Ximin (Committee member) / Arizona State University (Publisher)
Created2016
Description
Lithium ion batteries are quintessential components of modern life. They are used to power smart devices — phones, tablets, laptops, and are rapidly becoming major elements in the automotive industry. Demand projections for lithium are skyrocketing with production struggling to keep up pace. This drive is due mostly to the rapid adoption of electric vehicles; sales of electric vehicles in 2020 are more than double what they were only a year prior. With such staggering growth it is important to understand how lithium is sourced and what that means for the environment. Will production even be capable of meeting the demand as more industries make use of this valuable element? How will the environmental impact of lithium affect growth? This thesis attempts to answer these questions as the world looks to a decade of rapid growth for lithium ion batteries.
ContributorsMelton, John (Author) / Brian, Jennifer (Thesis director) / Karwat, Darshawn (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
Lithium conducting garnets in the family of Li7La3Zr2O12 (LLZO) are promising lithium conductors for solid-state batteries, due to their high ionic conductivity, thermal stability, and electrochemical stability with metallic lithium. Despite these advantages, LLZO requires a large energy input to synthesize and process. Generally, LLZO is synthesized using solid-state reaction (SSR) from oxide precursors, requiring high reaction temperatures (900-1000 °C) and producing powder with large particle sizes, necessitating high energy milling to improve sinterability. In this dissertation, two classes of advanced synthesis methods – sol-gel polymer-combustion and molten salt synthesis (MSS) – are employed to obtain LLZO submicron powders at lower temperatures. In the first case, nanopowders of LLZO are obtained in a few hours at 700 °C via a novel polymer combustion process, which can be sintered to dense electrolytes possessing ionic conductivity up to 0.67 mS cm-1 at room temperature. However, the limited throughput of this combustion process motivated the use of molten salt synthesis, wherein a salt mixture is used as a high temperature solvent, allowing faster interdiffusion of atomic species than solid-state reactions. A eutectic mixture of LiCl-KCl allows formation of submicrometer undoped, Al-doped, Ga-doped, and Ta-doped LLZO at 900 °C in 4 h, with total ionic conductivities between 0.23-0.46 mS cm-1. By using a highly basic molten salt medium, Ta-doped LLZO (LLZTO) can be obtained at temperatures as low as 550 °C, with an ionic conductivity of 0.61 mS cm-1. The formation temperature can be further reduced by using Ta-doped, La-excess pyrochlore-type lanthanum zirconate (La2Zr2O7, LZO) as a quasi-single-source precursor, which convert to LLZTO as low as 400 °C upon addition of a Li-source. Further, doped pyrochlores can be blended with a Li-source and directly sintered to a relative density up to 94.7% with high conductivity (0.53 mS cm-1). Finally, a propensity for compositional variation in LLZTO powders and sintered ceramics was observed and for the first time explored in detail. By comparing LLZTO obtained from combustion, MSS, and SSR, a correlation between increased elemental inhomogeneity and reduced ionic conductivity is observed. Implications for garnet-based solid-state batteries and strategies to mitigate elemental inhomogeneity are discussed.
ContributorsWeller, Jon Mark (Author) / Chan, Candace K (Thesis advisor) / Crozier, Peter (Committee member) / Sieradzki, Karl (Committee member) / Arizona State University (Publisher)
Created2021
Description
Current Li-ion battery technologies are limited by the low capacities of theelectrode materials and require developments to meet stringent performance demands for
future energy storage devices. Electrode materials that alloy with Li, such as Si, are one
of the most promising alternatives for Li-ion battery anodes due to their high capacities.
Tetrel (Si, Ge, Sn) clathrates are a class of host-guest crystalline structures in which
Tetrel elements form a cage framework and encapsulate metal guest atoms. These
structures can form with defects such as framework/guest atom substitutions and
vacancies which result in a wide design space for tuning materials properties. The goal of
this work is to establish structure property relationships within the context of Li-ion
battery anode applications. The type I Ba 8 Al y Ge 46-y clathrates are investigated for their
electrochemical reactions with Li and show high capacities indicative of alloying
reactions. DFT calculations show that Li insertion into the framework vacancies is
favorable, but the migration barriers are too high for room temperature diffusion. Then,
guest free type I clathrates are investigated for their Li and Na migration barriers. The
results show that Li migration in the clathrate frameworks have low energy barriers (0.1-
0.4 eV) which suggest the possibility for room temperature diffusion. Then, the guest
free, type II Si clathrate (Na 1 Si 136 ) is synthesized and reversible Li insertion into the type
II Si clathrate structure is demonstrated. Based on the reasonable capacity (230 mAh/g),
low reaction voltage (0.30 V) and low volume expansion (0.21 %), the Si clathrate could
be a promising insertion anode for Li-ion batteries. Next, synchrotron X-ray
measurements and pair distribution function (PDF) analysis are used to investigate the
lithiation pathways of Ba 8 Ge 43 , Ba 8 Al 16 Ge 30 , Ba 8 Ga 15 Sn 31 and Na 0.3 Si 136 . The results
show that the Ba-clathrates undergo amorphous phase transformations which is distinct
from their elemental analogues (Ge, Sn) which feature crystalline lithiation pathways.
Based on the high capacities and solid-solution reaction mechanism, guest-filled
clathrates could be promising precursors to form alloying anodes with novel
electrochemical properties. Finally, several high temperature (300-550 °C)
electrochemical synthesis methods for Na-Si and Na-Ge clathrates are demonstrated in a
cell using a Na β’’-alumina solid electrolyte.
ContributorsDopilka, Andrew (Author) / Chan, Candace K (Thesis advisor) / Zhuang, Houlong (Committee member) / Peng, Xihong (Committee member) / Sieradzki, Karl (Committee member) / Arizona State University (Publisher)
Created2021
Description
Tin (Sn) has a high-specific capacity (993 mAhg-1) as an anode material for Li-ion batteries. To overcome the poor cycling performance issue caused by its large volume expansion and pulverization during the charging and discharging process, many researchers put efforts into it. Most of the strategies are through nanostructured material design and introducing conductive polymer binders that serve as matrix of the active material in anode. This thesis aims for developing a novel method for preparing the anode to improve the capacity retention rate. This would require the anode to have high electrical conductivity, high ionic conductivity, and good mechanical properties, especially elasticity. Here the incorporation of a conducting polymer and a conductive hydrogel in Sn-based anodes using a one-step electrochemical deposition via a 3-electrode cell method is reported: the Sn particles and conductive component can be electrochemically synthesized and simultaneously deposited into a hybrid thin film onto the working electrode directly forming the anode. A well-defined three dimensional network structure consisting of Sn nanoparticles coated by conducting polymers is achieved. Such a conductive polymer-hydrogel network has multiple advantageous features: meshporous polymeric structure can offer the pathway for lithium ion transfer between the anode and electrolyte; the continuous electrically conductive polypyrrole network, with the electrostatic interaction with elastic, porous hydrogel, poly (2-acrylamido-2-methyl-1-propanesulfonic acid-co-acrylonitrile) (PAMPS) as both the crosslinker and doping anion for polypyrrole (PPy) can decrease the volume expansion by creating porous scaffold and softening the system itself. Furthermore, by increasing the amount of PAMPS and creating an interval can improve the cycling performance, resulting in improved capacity retention about 80% after 20 cycles, compared with only 54% of that of the control sample without PAMPS. The cycle is performed under current of 0.1 C.
ContributorsGao, Tianxiang (Author) / He, Ximin (Thesis advisor) / Sieradzki, Karl (Committee member) / Chan, Candace (Committee member) / Arizona State University (Publisher)
Created2015