Synergistic Effect of 3D Current Collectors and ALD Surface Modification for High Coulombic Efficiency Lithium Metal Anodes

Improving the performance of Li metal anodes is a critical bottleneck to enable nextâ generation battery systems beyond Liâ ion. However, stability issues originating from undesirable electrode/electrolyte interactions and Li dendrite formation have impaired longâ term cycling of Li metal anodes. Herein, a bottomâ up fabrication process is demonstrated for a current collector for Li metal electrodeposition and dissolution composed of highly uniform vertically aligned Cu pillars. By rationally controlling geometric parameters of the 3D current collector architecture, including pillar diameter, spacing, and length, the morphology of Li plating/stripping upon cycling can be controlled and optimal cycling performance can be achieved. In addition, it is demonstrated that deposition of an ultrathin layer of ZnO by atomic layer deposition on the current collector surface can facilitate the initial Li nucleation, which dictates the morphology and reversibility of subsequent cycling. This coreâ shell pillar architecture allows for the effects of geometry and surface chemistry to be decoupled and individually controlled to optimize the electrode performance in a synergistic manner. Using this platform, Li metal anodes are demonstrated with Coulombic efficiency up to 99.5%, providing a pathway toward highâ efficiency and longâ cycle life Li metal batteries with reduced excess Li loading.A 3D current collector architecture based on vertically aligned Cu for Li metal anodes is reported. By rationally tuning geometric parameters and surface chemistry of the 3D architecture, the morphology of Li plating/stripping can be controlled. Leveraging the synergistic effects of the optimized geometry and interface modification, cycling of Li metal anodes is demonstrated with Coulombic efficiency up to 99.5%.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147805/1/aenm201802534-sup-0001-S1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147805/2/aenm201802534_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147805/3/aenm201802534.pd

Evaluating Alternative Nutrient Sources in Subsistence-Level Aquaponic Systems

Many food production methods are both economically and environmentally unsustainable. Our project investigated aquaponics, an alternative method of agriculture that could address these issues. Aquaponics combines fish and plant crop production in a symbiotic, closed-loop system. We aimed to reduce the initial and operating costs of current aquaponic systems by utilizing alternative feeds. These improvements may allow for sustainable implementation of the system in rural or developing regions. We conducted a multi-phase process to determine the most affordable and effective feed alternatives for use in an aquaponic system. At the end of two preliminary phases, soybean meal was identified as the most effective potential feed supplement. In our final phase, we constructed and tested six full-scale aquaponic systems of our own design. Data showed that soybean meal can be used to reduce operating costs and reliance on fishmeal. However, a more targeted investigation is needed to identify the optimal formulation of alternative feed blends

Operando Visualization and Interfacial Engineering of Li Metal Anodes

The grand challenge of climate change has created an enormous need for superior battery technologies that deliver higher energy/power densities at low cost without sacrificing safety and cycle life. Such batteries would enable widespread vehicle electrification, increased use of renewable energy sources, and dramatic improvements for myriad other energy storage applications. One of the most promising approaches to offer a step-increase in energy density, lithium (Li) metal anodes, boast 10x higher specific capacity than graphite anodes. Unfortunately, implementation has been limited by capacity fade and safety concerns that stem from interfacial instability and morphology evolution during cycling. The primary goal of this thesis is to better understand the interfaces and interphases between Li metal electrodes and electrolytes, and thus enable enhanced performance through interfacial engineering. The work has two thrusts: 1) characterization of liquid and solid-state electrolyte (SSE) interfaces with Li metal to observe, correlate, and understand coupled electro-chemo-mechanical phenomena; and 2) development of atomic layer deposition (ALD) films for SSEs, interfacial coatings, and interlayers. In thrust one, operando video microscopy is developed to characterize the dynamic changes occurring at Li metal interfaces and correlate them with their electrochemical signatures. This technique is used to develop a comprehensive model of reaction pathways on Li metal electrodes. This model explains how transitions between these reaction pathways, driven by spatially varying kinetics and morphology evolution on the electrode surface, result in distinct electrochemical signatures. To better understand the Li/electrolyte interface in lithium metal solid-state battery (LMSSB)s, the correlation between surface chemistry, wettability, and interfacial impedance of LLZO SSEs is explored with x-ray photoelectron spectroscopy (XPS) and sessile drop tests. This demonstrates the coupled behavior at Li/SSE interfaces and that control of surface chemistry can enable higher rate capability. Operando video microscopy is adapted to SSE systems. Four distinct morphologies of Li penetration are identified in SSEs, and studied under a range of plating and stripping conditions. The voltage signatures of Li penetration in SSEs are compared with those of liquid electrolytes, to better understand the reaction pathways at the Li/SSE interface. The rate of propagation of Li penetration is quantified as a function of applied current to gain insight into the coupled electro-chemo-mechanical behavior of the system. Void formation in the Li electrode at the Li/SSE interface is observed during deep discharge, demonstrating the importance of morphology evolution during both plating and stripping. In thrust two, ALD of Al2O3 is used to improve the homogeneity of Li flux across the electrode/electrolyte interface. Cycle life and deep discharge performance are doubled. Subsequently, ALD processes are developed for two SSEs, Al-doped LLZO and glassy Li3BO3-Li2CO3 (LBCO). Challenges with low ionic conductivity and post-annealing of the LLZO films are overcome with the LBCO films, which do not require crystallization to obtain high ionic conductivities. ALD LBCO films demonstrated to have approximately 6x higher ionic conductivity (2.2*10-6 S cm-1) than other reported ALD films. The films also have good electrochemical stability at both high and low potentials, and are incorporated into a Li metal battery with high Coulombic efficiency and good cycle life. In summary, this thesis furthered the understanding and performance of Li metal anodes through the development and use of novel methods of characterization and means of interfacial modification. The implications of this work could aid in the development of next-generation Li metal batteries.PHDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/155323/1/kazyak_1.pdfDescription of kazyak_1.pdf : Restricted to UM users only

Improved Cycle Life and Stability of Lithium Metal Anodes through Ultrathin Atomic Layer Deposition Surface Treatments

Improving the cycle life and failure resistance of lithium metal anodes is critical for next-generation rechargeable batteries. Here, we show that treating Li metal foil electrodes with ultrathin (∼2 nm) Al₂O₃ layers using atomic layer deposition (ALD) without air exposure can prevent dendrite formation upon cycling at a current density of 1 mA/cm². This has the effect of doubling the lifetime of the anode before failure both under galvanostatic deep discharge conditions and cyclic plating/stripping of symmetric Li–Li cells. The ALD treated electrodes can be cycled for 1259 cycles before failure occurs, which is attributed to improved electrode morphology resulting from homogeneous Li ion flux across the electrode/electrolyte interface

Enabling 4C Fast Charging of Lithium- Ion Batteries by Coating Graphite with a Solid- State Electrolyte

Enabling fast- charging (- ¥4C) of lithium- ion batteries is an important challenge to accelerate the adoption of electric vehicles. However, the desire to maximize energy density has driven the use of increasingly thick electrodes, which hinders rate capability. Herein, atomic layer deposition is used to coat a single- ion conducting solid electrolyte (Li3BO3- Li2CO3) onto postcalendered graphite electrodes, forming an artificial solid- electrolyte interphase (SEI). When compared to uncoated control electrodes, the solid electrolyte coating: 1) eliminates natural SEI formation during preconditioning; 2) decreases interphase impedance by >75% compared to the natural SEI; and 3) extends cycle life under 4C charging conditions, enabling retention of 80% capacity after 500 cycles (compared to 12 cycles in the uncoated control) in pouch cells with >3 mAh cm- 2 loading. This work demonstrates that 4C charging without Li plating can be achieved through purely interfacial modification without sacrificing energy density and sheds new light on the role of the SEI in Li plating and fast- charge performance.An artificial solid- electrolyte interphase (SEI) coating with 75% lower impedance is demonstrated compared to the natural SEI. This coating enables stable cycling under 4C (15 min) charging conditions, retaining 80% capacity over 500 cycles. This challenges the prevailing assumption that mass transport limitations must be addressed to enable fast charging.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/171610/1/aenm202102618.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/171610/2/aenm202102618-sup-0001-SuppMat.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/171610/3/aenm202102618_am.pd

Lithium Metal Anodes: Synergistic Effect of 3D Current Collectors and ALD Surface Modification for High Coulombic Efficiency Lithium Metal Anodes (Adv. Energy Mater. 4/2019)

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147823/1/aenm201970010.pd

Dendrites and Pits: Untangling the Complex Behavior of Lithium Metal Anodes through Operando Video Microscopy

Enabling ultra-high energy density rechargeable Li batteries would have widespread impact on society. However the critical challenges of Li metal anodes (most notably cycle life and safety) remain unsolved. This is attributed to the evolution of Li metal morphology during cycling, which leads to dendrite growth and surface pitting. Herein, we present a comprehensive understanding of the voltage variations observed during Li metal cycling, which is directly correlated to morphology evolution through the use of operando video microscopy. A custom-designed visualization cell was developed to enable operando synchronized observation of Li metal electrode morphology and electrochemical behavior during cycling. A mechanistic understanding of the complex behavior of these electrodes is gained through correlation with continuum-scale modeling, which provides insight into the dominant surface kinetics. This work provides a detailed explanation of (1) when dendrite nucleation occurs, (2) how those dendrites evolve as a function of time, (3) when surface pitting occurs during Li electrodissolution, (4) kinetic parameters that dictate overpotential as the electrode morphology evolves, and (5) how this understanding can be applied to evaluate electrode performance in a variety of electrolytes. The results provide detailed insight into the interplay between morphology and the dominant electrochemical processes occurring on the Li electrode surface through an improved understanding of changes in cell voltage, which represents a powerful new platform for analysis

Dendrites and Pits: Untangling the Complex Behavior of Lithium Metal Anodes through Operando Video Microscopy

Enabling ultra-high energy density rechargeable Li batteries would have widespread impact on society. However the critical challenges of Li metal anodes (most notably cycle life and safety) remain unsolved. This is attributed to the evolution of Li metal morphology during cycling, which leads to dendrite growth and surface pitting. Herein, we present a comprehensive understanding of the voltage variations observed during Li metal cycling, which is directly correlated to morphology evolution through the use of operando video microscopy. A custom-designed visualization cell was developed to enable operando synchronized observation of Li metal electrode morphology and electrochemical behavior during cycling. A mechanistic understanding of the complex behavior of these electrodes is gained through correlation with continuum-scale modeling, which provides insight into the dominant surface kinetics. This work provides a detailed explanation of (1) when dendrite nucleation occurs, (2) how those dendrites evolve as a function of time, (3) when surface pitting occurs during Li electrodissolution, (4) kinetic parameters that dictate overpotential as the electrode morphology evolves, and (5) how this understanding can be applied to evaluate electrode performance in a variety of electrolytes. The results provide detailed insight into the interplay between morphology and the dominant electrochemical processes occurring on the Li electrode surface through an improved understanding of changes in cell voltage, which represents a powerful new platform for analysis

Hierarchical ZnO Nanowire Growth with Tunable Orientations on Versatile Substrates Using Atomic Layer Deposition Seeding

The ability to synthesize semiconductor nanowires with deterministic and tunable control of orientation and morphology on a wide range of substrates, while high precision and repeatability are maintained, is a challenge currently faced for the development of many nanoscale material systems. Here we show that atomic layer deposition (ALD) presents a reliable method of surface and interfacial modification to guide nanowire orientation on a variety of substrate materials and geometries, including high-aspect-ratio, three-dimensional templates. We demonstrate control of the orientation and geometric properties of hydrothermally grown single crystalline ZnO nanowires via the deposition of a ZnO seed layer by ALD. The crystallographic texture and roughness of the seed layer result in tunable preferred nanowire orientations and densities for identical hydrothermal growth conditions. The structural and chemical relationship between the ALD layers and nanowires was investigated with synchrotron X-ray diffraction, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy to elucidate the underlying mechanisms of orientation and morphology control. The resulting control parameters were utilized to produce hierarchical nanostructures with tunable properties on a wide range of substrates, including vertical micropillars, paper fibers, porous polymer membranes, and biological substrates. This illustrates the power of ALD for interfacial engineering of heterogeneous material systems at the nanoscale, to provide a highly controlled and scalable seeding method for bottom-up synthesis of integrated nanosystems

Correlation between mechanical properties and ionic conductivity of sodium superionic conductors: a relative density-dominant relationship

Sodium superionic conductors (NASICON) are pivotal for the functionality and safety of solid-state sodium batteries. Their mechanical properties and ionic conductivity are key performance metrics, yet their correlation remains inadequately understood. Addressing this gap is vital for concurrent enhancements in both properties. This study summarizes recent literature on the sintered polycrystalline NASICON solid electrolyte Na1+xZr2SixP3-xO12 (NZSP, 0≤x≤3), focusing on its mechanical properties and ionic conductivity, and identifies a positive correlation between these properties at ambient temperatures. Microstructural analysis reveals that a range of factors, including relative density, grain size, secondary phases, and crystal structures, significantly influence the properties of NZSP. Notably, an increase in relative density uniquely contributes to simultaneous enhancements in both hardness and ionic conductivity. Consequently, future research should prioritize enhancing the relative density of NZSP, potentially by employing advanced sintering techniques such as spark plasma sintering (SPS) and microwave-assisted sintering. The correlation between mechanical properties and ionic conductivity observed in NZSP is also evident in other oxide solid electrolytes, such as garnet Li7La3Zr2O12 (LLZO). This investigation not only suggests a potential linkage between these crucial properties but also guides subsequent strategies for refining polycrystalline oxide solid electrolytes for advanced battery technologies