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    Halide and Sulfide Solid Electrolytes for All Solid-State Batteries: Structure and Interface Engineering
    (University of Waterloo, 2026-05-28) Qian, Lanting
    All-solid-state batteries (ASSBs) are widely regarded as a promising next-generation energy-storage technology due to their potential to deliver enhanced safety, higher energy density, and improved compatibility with high-voltage electrode materials. Central to the advancement of ASSBs is the development of solid electrolyte (SE) that simultaneously exhibit high ionic conductivity, wide electrochemical stability windows, good processability, and robust interfacial compatibility with both lithium anodes and high-energy cathodes. Among the various classes of SEs, halides and sulfides have emerged as leading candidates owing to their unique advantages. Nevertheless, their electrochemical performance is strongly governed by crystallographic disorder, synthesis-dependent defect chemistry, and complex interfacial reactions, many of which remain incompletely understood. This thesis focuses on the design, structural elucidation, and interfacial engineering of halide and sulfide solid electrolytes for high-voltage ASSBs, with particular emphasis on understanding how crystallographic disorder and chemical modification influence lithium-ion transport and interfacial stability. A comprehensive suite of experimental and computational techniques—including synchrotron and neutron diffraction, total scattering and pair distribution function analysis, electron microscopy, X-ray spectroscopies, time-of-flight secondary ion mass spectrometry (ToF-SIMS), electrochemical characterization, and first-principles calculations—is employed to establish robust structure–property–interface relationships. Chapter 3 examines the nature of structural disorder in layered Li₃InCl₆, revealing the critical role of stacking faults and local structural deviations in governing ionic conduction. Solid-state–synthesized Li₃InCl₆ (SS-LIC) exhibits a stacking-fault fraction of approximately 20%, compared to ~2% in water-mediated Li₃InCl₆ (WM-LIC). Despite this pronounced difference in stacking-fault density, both materials display comparable room-temperature ionic conductivities (1.6 vs. 1.4 mS·cm⁻¹) and nearly identical activation energies (0.37 vs. 0.36 eV). Bond valence site energy analysis confirms that the dominant Li⁺ diffusion pathways remain largely unaffected by stacking faults. These findings underscore the structural complexity of layered halide solid electrolytes and demonstrate that stacking faults exert only a limited influence on Li⁺ transport in Li₃InCl₆. Building on this foundation, Chapter 4 explores lithium metal fluorides as an emerging class of solid electrolytes, demonstrating that mechanochemical synthesis and disorder engineering can unlock unexpectedly high lithium-ion conductivity. By probing both amorphous-like and crystalline forms across multiple length scales, this chapter reveals that the introduction of structural disorder—from short-range to long-range—is essential for facilitating Li⁺ transport. Furthermore, the incorporation of LiF into Li₂TiF₆ induces strong local interactions that disrupt long-range order and enhance ionic mobility. As a result, the Li₂TiF₆–LiF composite achieves an ionic conductivity of 2.5 × 10⁻³ mS·cm⁻¹, representing the highest conductivity reported for fluoride-based solid electrolytes and approaching values typical of LiPON and LiNbO₃. In Chapter 5, a dual-halogen substitution strategy is introduced in Li2HfCl6-xF, illustrating how targeted fluorination can simultaneously tune lattice disorder, electrochemical stability, and interfacial chemistry. This chapter systematically investigates the interplay between ionic and electronic conductivity, voltage stability, and overall battery performance in this new family of dual-halogen solid electrolytes. All-solid-state cells employing Li₂HfCl₅.₅F₀.₅ exhibit markedly enhanced electrochemical performance compared to Li₂HfCl₆. This improvement is primarily attributed to the formation of a kinetically stable, LiF-rich cathode–electrolyte interphase (CEI), which suppresses deleterious interfacial reactions, as revealed by ToF-SIMS analysis. Chapters 6 and 7 address cathode–electrolyte interfacial instability in high-voltage ASSBs through surface-engineering strategies designed to suppress parasitic reactions and enable stable cycling under practical operating conditions. In Chapter 6, guided by density functional theory calculations, a conformal and nanometric coating is developed for nickel-rich NMC85 cathodes, effectively suppressing the oxidative decomposition of Li₆PS₅Cl. Cells employing coated NMC85 achieve 82% capacity retention after 200 cycles (2.8–4.3 V vs. Li⁺/Li), compared to only 56% for cells with uncoated cathodes. The coated systems also exhibit superior rate capability and higher reversible capacity. Chapter 7 presents a simple, cost-effective organic coating strategy for Li6PS5Cl that significantly enhances its air stability while preserving high ionic conductivity. The coated electrolyte (DA-LPSCl) withstands exposure to 39% relative humidity for up to 2 hours with minimal structural degradation and maintains an ionic conductivity exceeding 1 mS·cm⁻¹. All-solid-state cells employing DA-LPSCl as the catholyte and a Li–In anode deliver a discharge capacity of 175 mAh·g⁻¹ with 96% capacity retention over 150 cycles at 0.2 C, whereas cells using bare LPSCl retain only 61% under identical conditions. Symmetric Li|DA-LPSCl|Li cells demonstrate stable cycling for over 1000 hours, in sharp contrast to bare LPSCl cells, which short-circuit after approximately 230 hours. Moreover, full cells pairing DA-LPSCl with a lithium metal anode retain 81% of their capacity after 300 cycles at 0.2 C, highlighting performance metrics competitive with state-of-the-art solid-state batteries. Collectively, the studies presented in this thesis demonstrate that disorder engineering and interfacial protection constitute unifying design principles for advancing both halide and sulfide solid electrolytes. The insights gained provide fundamental guidance for the rational design of chemically stable, high-performance solid electrolytes and outline viable pathways toward durable, high-energy all-solid-state battery systems.
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    Motor unit characteristics after targeted muscle reinnervation
    (Public Library of Science, 2016-02-22) Kapelner, Tamas; Jiang, Ning; Holobar, Ales; Vujaklija, Ivan; Roche, Aidan D.; Farina, Dario; Aszmann, Oskar C.
    Targeted muscle reinnervation (TMR) is a surgical procedure used to redirect nerves originally controlling muscles of the amputated limb into remaining muscles above the amputation, to treat phantom limb pain and facilitate prosthetic control. While this procedure effectively establishes robust prosthetic control, there is little knowledge on the behavior and characteristics of the reinnervated motor units. In this study we compared the m. pectoralis of five TMR patients to nine able-bodied controls with respect to motor unit action potential (MUAP) characteristics. We recorded and decomposed high-density surface EMG signals into individual spike trains of motor unit action potentials. In the TMR patients the MUAP surface area normalized to the electrode grid surface (0.25 ± 0.17 and 0.81 ± 0.46, p < 0.001) and the MUAP duration (10.92 ± 3.89 ms and 14.03 ± 3.91 ms, p < 0.01) were smaller for the TMR group than for the controls. The mean MUAP amplitude (0.19 ± 0.11 mV and 0.14 ± 0.06 mV, p = 0.07) was not significantly different between the two groups. Finally, we observed that MUAP surface representation in TMR generally overlapped, and the surface occupied by motor units corresponding to only one motor task was on average smaller than 12% of the electrode surface. These results suggest that smaller MUAP surface areas in TMR patients do not necessarily facilitate prosthetic control due to a high degree of overlap between these areas, and a neural information—based control could lead to improved performance. Based on the results we also infer that the size of the motor units after reinnervation is influenced by the size of the innervating motor neuron.
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    Effect of copper and zinc on the single molecule self-affinity of Alzheimer's amyloid-β peptides
    (Public Library of Science, 2016-01-25) Hane, Francis T.; Hayes, Reid; Lee, Brenda Y.; Leonenko, Zoya
    The presence of trace concentrations of metallic ions, such as copper and zinc, has previously been shown to drastically increase the aggregation rate and neurotoxicity of amyloid-β (Aβ), the peptide implicated in Alzheimer’s disease (AD). The mechanism of why copper and zinc accelerate Aβ aggregation is poorly understood. In this work, we use single molecule force spectroscopy (SMFS) to probe the kinetic and thermodynamic parameters (dissociation constant, Kd, kinetic dissociation rate, koff, and free energy, ΔG) of the dissociation of an Aβ dimer, the amyloid species which initiates the amyloid cascade. Our results show that nanomolar concentrations of copper do not change the single molecule affinity of Aβ to another Aβ peptide in a statistically significant way, while nanomolar concentrations of zinc decrease the affinity of Aβ-Aβ by an order of magnitude. This suggests that the binding of zinc ion to Aβ may interfere with the binding of Aβ-Aβ, leading to a lower self-affinity.
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    Bridging organizations drive effective governance outcomes for conservation of Indonesia's marine systems
    (Public Library of Science, 2016-01-21) Berdej, Samantha M.; Armitage, Derek R.
    This study empirically investigates the influence of bridging organizations on governance outcomes for marine conservation in Indonesia. Conservation challenges require ways of governing that are collaborative and adaptive across boundaries, and where conservation actions are better coordinated, information flows improved, and knowledge better integrated and mobilized. We combine quantitative social network analysis and qualitative data to analyze bridging organizations and their networks, and to understand their contributions and constraints in two case studies in Bali, Indonesia. The analysis shows 1) bridging organizations help to navigate the ‘messiness’ inherent in conservation settings by compensating for sparse linkages, 2) the particular structure and function of bridging organizations influence governing processes (i.e., collaboration, knowledge sharing) and subsequent conservation outcomes, 3) ‘bridging’ is accomplished using different strategies and platforms for collaboration and social learning, and 4) bridging organizations enhance flexibility to adjust to changing marine conservation contexts and needs. Understanding the organizations that occupy bridging positions, and how they utilize their positionality in a governance network is emerging as an important determinant of successful conservation outcomes. Our findings contribute to a relatively new body of literature on bridging organizations in marine conservation contexts, and add needed empirical investigation into their value to governance and conservation in Coral Triangle nations and beyond.
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    Freezing of gait in Parkinson's disease: An overload problem?
    (Public Library of Science, 2015-12-17) Beck, Eric N.; Martens, Kaylena A. Ehgoetz; Almeida, Quincy J.
    Freezing of gait (FOG) is arguably the most severe symptom associated with Parkinson's disease (PD), and often occurs while performing dual tasks or approaching narrowed and cluttered spaces. While it is well known that visual cues alleviate FOG, it is not clear if this effect may be the result of cognitive or sensorimotor mechanisms. Nevertheless, the role of vision may be a critical link that might allow us to disentangle this question. Gaze behaviour has yet to be carefully investigated while freezers approach narrow spaces, thus the overall objective of this study was to explore the interaction between cognitive and sensory-perceptual influences on FOG. In experiment #1, if cognitive load is the underlying factor leading to FOG, then one might expect that a dual-task would elicit FOG episodes even in the presence of visual cues, since the load on attention would interfere with utilization of visual cues. Alternatively, if visual cues alleviate gait despite performance of a dual-task, then it may be more probable that sensory mechanisms are at play. In compliment to this, the aim of experiment#2 was to further challenge the sensory systems, by removing vision of the lower-limbs and thereby forcing participants to rely on other forms of sensory feedback rather than vision while walking toward the narrow space. Spatiotemporal aspects of gait, percentage of gaze fixation frequency and duration, as well as skin conductance levels were measured in freezers and non-freezers across both experiments. Results from experiment#1 indicated that although freezers and non-freezers both walked with worse gait while performing the dual-task, in freezers, gait was relieved by visual cues regardless of whether the cognitive demands of the dual-task were present. At baseline and while dual-tasking, freezers demonstrated a gaze behaviour that neglected the doorway and instead focused primarily on the pathway, a strategy that non-freezers adopted only when performing the dual-task. Interestingly, with the combination of visual cues and dual-task, freezers increased the frequency and duration of fixations toward the doorway, compared to non-freezers. These results suggest that although increasing demand on attention does significantly deteriorate gait in freezers, an increase in cognitive demand is not exclusively responsible for freezing (since visual cues were able to overcome any interference elicited by the dual-task). When vision of the lower limbs was removed in experiment#2, only the freezers' gait was affected. However, when visual cues were present, freezers' gait improved regardless of the dual-task. This gait behaviour was accompanied by greater amount of time spent looking at the visual cues irrespective of the dual-task. Since removing vision of the lower-limbs hindered gait even under low attentional demand, restricted sensory feedback may be an important factor to the mechanisms underlying FOG.