Due to climate change, the energy system needs to change from traditional fossil fuels to be dominated by renewable energy sources. Not only the energy system, but the increasing number of vehicles and emissions from the transport sector are a problem for climate change and that need to be solved. Both can be solved with batteries, to handle climate change issue. The lithium-ion batteries (LIBs) have a high energy density which is important due to the less needed materials for the batteries. LIBs can be used in a battery energy storage system (BESS) to store the excess energy for later usage, and as an electric vehicle (EV) battery. For these high energy density batteries, there comes drawbacks such as safety issues by deviating temperatures which have effects on the capacity, lifetime, performance, and in worst case a thermal runaway can occur which may lead to fire and explosions. These temperature issues can be solved with a battery thermal management system (BTMS), which can manage temperature deviation. Cylindrical battery cells with the dimension 18650 with the cell chemistry Lithium-Nickel-Cobalt-Aluminum-Oxide (NCA) will be investigated with different discharge rates, how the heat generation increases, and how it can be handled by cooling systems. A battery pack will be built up in computational fluid dynamics (CFD) software called Ansys Fluent, to be simulated and see how the influence of cooling methods affect the energy density of the 18650 batteries. Air-cooling and liquid-cooling with fan as air-cooling and plate cooling as liquid cooling will be used in this work. 20 cells were investigated with air and liquid cooling, with two different cases with air-cooling. 100 cells with just liquid cooling during 0,5C was investigated on how the number of cells impacted on the energy density. It was seen that the different discharge rates (C-rate) had an impact on the amount of cooling, with air cooling being not as good as liquid cooling for cooling the battery pack and more flow was needed. The energy density in relation to weight showed that 20 cells with less spacing using air-cooling had the best energy density at 196,68 Wh/kg. It was also seen that the number of cells had an impact on the energy density in relation to volume. With the best energy density with 100 cells using liquid cooling at 279,96 Wh/L.

The aim of this bachelor’s thesis is to design theelectronics for an autonomous glider to be used in a soundingrocket experiment with return to launch site functionality. Theelectronics includes a battery solution, servos and a hardwareplatform for communication and control software. All of theseparts need to be suited for a specified form factor and someextreme environments such as low temperature and vacuum. Theelectronics have been designed based on calculations for powerconsumption and temperature dependency. The system had to bepower efficient since the space for batteries is limited. Servos werecustom designed with motors and drivers to optimize both spaceand efficiency. Based on testing, simulations and calculations ofthe design the following can be concluded. The proposed systemhas the capability to meet the requirements to control and flythe glider all the way back to launch site even in a worstcasescenario. Thus an electronics system for the autonomousglider solution is feasible even with the strict requirements andconditions. / Syftet med detta kandidatexamensarbete äratt designa elektroniken till en autonom glidflygare vars uppgiftär att återföra experiment uppskjutna med en sondraket. Elektronikeninnefattar en batterilösning, servos för styrning samten hårdvaruplattform för kommunikation och kontrollsystemet.Alla dessa delar ska implementeras i ett begränsat utrymmeoch klara av låga temperaturer samt vakuum. Beräkningar avenergiförbrukning och temperaturberoende hos de olika komponenternahar gjorts för att designen ska klara förhållandena.Elsystemet måste vara effektivt nog för att kunna drivas medett batteri kompatibelt med det givna utrymmet. Egendesignadeservon är framtagna med motorer och drivare för optimeradeffektivitet och storlek. Tester, simulationer och beräkningarvisar att det föreslagna systemet är kapabelt att för de angivnakraven flyga glidflygaren tillbaka till basen. Elsystemet haräven marginaler nog att klara detta under de mest påfrestandeförutsättningarna. / Kandidatexjobb i elektroteknik 2021, KTH, Stockholm

Många batteriers användningsområden kräver att batterierna har hög upp- och urladdningshastighet samt låg kostnad. För dessa användningsområden är vattenbaserade laddningsbara batterier (ARB) ett möjligt alternativ i och med att de är svårantändliga, har god jonledningsförmåga, lägre inre resistans, billigare elektrolytlösning och tillverkning och har potentiellt högre upp- och urladdningshastigheter.  Genom att utgå från en cell med LiMn2O4 och V2O5 som katod respektive anod, utvecklades en cell med en spänning på 1 V och prestanda för 2 mol/L LiTSFI i organisk respektive vattenlöslig lösning jämfördes i ett SEI-fritt system. Prestandan kvantifierades med avseende på urladdningskapaciteten vid olika urladdningshastigheter samt fördelningen av de interna överpotentialerna. Vid C/4 behöll den organiska elektrolyten 88,3% av den initiala kapaciteten efter 10 cykler medan den vattenlösliga behöll 98,8%. En gräns på 20 °C påvisades för den organiska elektrolyten och vid försök att gå över denna hastighet svällde pouch cellen upp. Den vattenlösliga elektrolyten, å andra sidan, bevarade 37 mAh/g vid 50 °C.  Skillnaden i potentialfördelning i de två systemen analyserades även genom att använda tunnare elektroder. Den organiska elektrolyten visade då en förbättring av prestandan vid höga hastigheter, med en urladdningskapacitet på 8,8 mAh/g vid 50 °C, jämfört med 30 mAh/g för den vattenlösliga elektrolyten. IR-fallet var 7 gånger högre för den organiska elektrolyten. Eventuell skillnad i laddningsöverföring och por-resistans kunde inte analyseras då flera processer ägde rum på samma gång i systemen, vilket gav ett impedansspektrum med en komplex associerad ekvivalent krets. / For several battery applications, high dis-/charge rate and low cost are imperatives. It is for these applications that aqueous rechargeable batteries (ARB) rise as potential candidates given the non-flammability, potentially higher ionic conductivity and dis-/charge rates, lower internal resistances and lower price of the electrolyte solvents and manufacture. By benchmarking a cell with LiMn2O4 and V2O5 as cathode and anode, respectively, a cell with an operating voltage window of 1 V was developed and the performance of 2 mol/L LiTFSI in organic and aqueous solvent compared in a SEI-free system. This performance was quantified in terms of discharge capacity at different rates of discharge and the distribution of internal overpotentials. At C/4, the organic electrolyte held 88.3% of the initial capacity after 10 cycles while the aqueous, 98.8%. A limit of 20 °C for the organic electrolyte was seen, and at the attempt of cycling above this rate, swelling of the pouch cell took place. The aqueous electrolyte, on the other hand, conserved 37 mAh/g at 50 °C. The difference of overpotentials distribution in both systems was also assessed by employing thinner electrodes. The organic electrolyte showed then an improvement on high-rate performance, reaching 50 °C, but with a discharge capacity of 8.8 mAh/g, against 30 mAh/g for the aqueous electrolyte. The IR-drop was 7 times higher for the organic electrolyte. The differentiation between charge-transfer and pore resistance, however, was not possible, because of the presence of several processes taking place at similar time-scales in both systems, yielding an impedance spectra with a complex associated equivalent circuit.

To create more sustainable power systems, as well as achieve environmental goals, further integration of Renewable Energy Sources (RES) is essential. However, this may result in a power system more vulnerable to disturbances, since RES do not contribute to the system’s inertia. A power system’s ability to counteract disturbances is highly dependant on inertia. This is because the power system uses the kinetic energy of rotating machines, i.e. inertia, to restore the power balance after a disturbance. This causes a deviation of the system’s frequency, which must be contained within certain limits or, in the worst case scenario, a blackout could follow. Frequency Containment Reserves (FCR) stabilizes the frequency first dozens of seconds after a disturbance, therefore, it is the inertia that plays the major role in controlling the initial frequency deviation. One possibility to counter disturbances in a power system with less inertia is to use electrical batteries as fast power support, by injecting power into the system when needed. This project aims to investigate the dynamics of the FCR as well as the possibility to use batteries as fast power support. Different parameters of the batteries are also analyzed. The project is conducted through a case study of a power system model in Simulink and Matlab. Additional aspects, such as sustainability, cost-effectiveness, and future research, are discussed. / För att skapa mer hållbara kraftsystem, men även uppnå miljömål, är fortsatt integrering av förnyelsebara energikällor viktigt. Dock kan detta resultera i ett kraftsystem som är mer sårbart mot störningar, då förnyelsebara energikällor inte bidrar till systemets svängmassa. Ett kraftsystems förmåga att möta störningar är direkt relaterad till svängmassan i systemet. Detta är på grund av att systemet använder kinetisk energi från roterande maskiner, deras svängmassa, för att återställa balans mellan produktion och konsumtion efter en störning. Dock orsakar detta en avvikelse hos systemets frekvens, som måste hållas inom vissa gränser, annars kan det i värsta fall leda till strömavbrott. Primärreglering stabiliserar frekvensen först dussin sekunder efter en störning, därför är det svängmassan som spelar den avgörande rollen för att kontollera den initiella avvikelsen. En möjlig lösning för att möta störningar i ett kraftsystem med mindre svängmassa är att använda elektriska batterier som snabbt kraftstöd, genom att tillföra effekt till systemet vid behov. Detta projekt syftar till att undersöka dynamiken hos primärregleringen men även huruvida batterier kan användas som snabbt kraftstöd. Olika parametrar hos batterierna analyseras även. Projektet görs genom en fallstudie av en model av ett kraftsystem i Simulink och Matlab. Andra aspekter, så som hållbarhet, kostnadseffektivitet samt framtida forskning diskuteras.

<p>This thesis evaluates several solid-state NMR spectroscopy approaches to studying lithium ion dynamics in solid-state electrolytes. With the goal of reducing the risks associated with current liquid electrolytes, solid-state electrolytes provide non-flammable materials that are also stable against attack by cathode and anode materials. Solid-state NMR spectroscopy offers a versatile method to determine structural details and can also provide information about ion mobility in solid-state electrolytes. Challenges involved in the study of solid-state electrolytes include the difficulty in distinguishing between ^6,7Li resonances due to the small chemical shift range of diamagnetic lithium species. The NMR methods selected in this thesis aim to circumvent some of these issues in order to determine structural and dynamic properties in solid-state electrolytes. Several different electrolytes have been examined including LaLi_0.5Fe_0.2O_2.09 and related materials, which exhibit intricate structural properties. ¹³⁹La NMR spectroscopy, in combination with ⁷Li MAS NMR spectroscopy, was used to determine the nature of this disorder. In addition, studies of the quadrupolar framework ⁸⁷Rb nucleus, which take advantage of its large electric field gradient, have been used to indirectly probe the activation energy for Ag⁺ ion hopping in the solid-state silver ion electrolyte RbAg₄I₅. Alternatively, dipolar coupling between ⁶Li and ⁷Li has been used to compare lithium ion hopping rates in Li₆BaLa₂M₂O₁₂ (M = Ta, Nb) using ⁶Li{⁷Li}-REDOR NMR studies. Finally, T₂ relaxation studies have been used to probe ion dynamics in Li₃V₂(PO₄)₃ and LiVO₃ in order to determine if this is a viable method to study dynamics in these materials.</p> / Doctor of Philosophy (PhD)

Li-ion batteries (LIB) are used in many applications because of their high-power/energy density, long life cycling, and low self-discharge rate. The use of LIB continues to grow every day, and the necessity for proper safety standards grows as well. A key aspect for safe utilization of LIB is determining their safety and remaining useful life (RUL). Battery characteristics degrade over time under normal and extreme operating conditions and modeling the electrochemical processes can improve RUL estimations. Extreme operating conditions such as abnormal temperatures and charge/discharge rates are believed to exacerbate the rate of degradation. Li-ion batteries are also susceptible to mechanical damage, which may lead to an electrical short. In severe cases, mechanical damage causes a thermal run away, and possibly explosions or fires. In the event of a car accident, battery packs can be damage without an electrical short or immediate thermal run away. Currently, there is no reliable batt / Mechanical Engineering

An investigation of electrochemical storage device materials has been undertaken in four parts. The bulk and interfacial resistance of Na+ beta-alumina tubes were separated using a galvanostatic charge-discharge method. Sodium silicide was characterized to better understand its synthesis. BiMn2O5 was produced using a sol-gel method and tested for pseudocapacity. Different lithium ion anode and cathode materials were deposited using a new electrophoretic deposition method. A novel galvanostatic charge-discharge method was developed for the determination of bulk and interface resistance in Na+ beta-alumina solid electrolytes [BASE]. Dense and duplex BASE tubes were tested by varying the exposed surface area. The results of dense BASE tube pairs were used to determine the bulk and interfacial resistance components, while duplex BASE tubes were tested to determine the reduction in interfacial resistance. It was found that duplex tubes had reduced the interfacial resistance by 75%, when compared to a uniformly dense electrolyte. Sodium silicide was characterized using various methods to better understand the phase and the Na-Si phase diagram. EMF experiments using Na+ BASE tubes was used to determine the activity in the silicon rich region of the phase diagram, which showed a sodium activity of 0.5 at 550°C. TGA/DSC was used to determine phase transformation temperatures, as well as the heat of formation for NaSi, which was recorded to be below 1 kJ mol-1. A sol-gel precipitation method was used to produce fine BiMn2O5 powders used for supercapacitors. The powders resulting from a consistent method were tested for pseudocapacitance using bulk and thin film electrodes. Bulk electrodes had a gravimetric capacitance of 10 F g-1, while thin film electrodes only reached 2.6 F g-1. Lithium ion battery anode (Li4Ti5O12) and cathode (LiFePO4, LiMn2O4, LiMn1.5Ni0.5O4) materials were electrophoretically deposited with the assistance of PAZO-Na and CMC-Na. Cathodes were successfully deposited on aluminium substrates, and were tested in the potential window 2 – 4.3 V. The LiFePO4 cathodes showed capacity of 146.7 mAh g-1 at C/10, while showing capacity retention of 103% after 50 cycles. / Thesis / Doctor of Philosophy (PhD) / The goal of this work is to examine materials used in different types of electrochemical storage devices. The modification of resistive properties of β-alumina electrolytes are examined for use in high temperature sodium batteries. Electrophoretic deposition methods are used to rapidly make thin electrodes for lithium ion batteries and supercapacitors. The stoichiometric compound NaSi, a potentially safer and greener method of producing hydrogen gas, is characterized for a better understanding of its properties, and therefore production.

The study started with the requirement that a photovoltaic (PV) power source should be integrated with other supplementary power sources whether it operates in a stand-alone or grid-connected mode. First, fuel cells for a backup of varying PV power were compared in detail with batteries and were found to have more operational benefits. Next, maximizing performance of a grid-connected PV-fuel cell hybrid system by use of a two-loop controller was discussed. One loop is a neural network controller for maximum power point tracking, which extracts maximum available solar power from PV arrays under varying conditions of insolation, temperature, and system load. A real/reactive power controller (RRPC) is the other loop. The RRPC meets the system's requirement for real and reactive powers by controlling incoming fuel to fuel cell stacks as well as switching control signals to a power conditioning subsystem. The RRPC is able to achieve more versatile control of real/reactive powers than the conventional power sources since the hybrid power plant does not contain any rotating mass. Results of time-domain simulations prove not only effectiveness of the proposed computer models of the two-loop controller, but also their applicability for use in transient stability analysis of the hybrid power plant. Finally, environmental evaluation of the proposed hybrid plant was made in terms of plant's land requirement and lifetime CO2 emissions, and then compared with that of the conventional fossil-fuel power generating forms. / Ph. D.

As Lithium-ion batteries (LiBs) emerge as pivotal energy storage solutions for automotive applications, maintaining their performance and longevity presents challenges due to power and capacity fade influenced by environmental and usage conditions. Thus, to estimate battery degradation, estimating the state of health (SOH) or predicting remaining useful life (RUL) without considering future operational loads, can limit accurate SOH forecasting. Meanwhile, machine learning (ML) models including deep neural networks (DNNs), have become effective techniques for SOH forecasting of LiBs due to their capability to handle various regression problems without relying on physics-based models. The methodology used in this study, helps battery developers link different operational strategies to battery aging. We use inputs such as temperature (T), current (I), and state of charge (SOC) and utilize a feature transformation technique which generates histogram-based stressor features representing the time that the battery cells spend under operational conditions, then investigate the performance of DNN models along with explainable machine learning (XML) techniques (e.g., SHapley Additive exPlanations) in predicting LiB SOH. The comparative analysis leverages an extensive open-source dataset to evaluate the performance of deep learning models such as LSTM, GRU, and FNN. The forecasting is executed in two distinct modes: one capping the forecasted cycles at 520, and another extending the predictions to the end of the battery’s first life (SOH=80%).Furthermore, this study explores the practicality of a lightweight model, e.g., support vector regression (SVR) model, to compare against DNN models for scenarios with constrained computational and memory resources. The results show that utilizing a feature refinement to ensure the coverage of critical features can lead to performance comparable with the DNN (e.g., LSTM) for the SVR model.

The global energy transition, involving the widespread adoption of electric vehicles and grid-scale energy storage, demands energy storage devices made up of abundant, inexpensive minerals. For this to be achieved, the large Co content in conventional Li-ion battery cathodes (e.g., LiCoO₂) must be replaced while also maintaining or improving the energy density of the battery. Alternative low-Co and Co-free materials (e.g., layered LiNixMnyCozO₂, spinel LiNi₀.₅Mn₁.₅O₄, and olivine LiFePO₄) are promising alternatives due to their theoretically higher energy densities or improved safety properties from the industry standards. However, in practice, these materials exhibit both bulk and interfacial instabilities that limit their practical energy density and cycle lifetime. It is well known that reactions between the delithiated (charged) cathode surface with the electrolyte generates electrolyte decomposition species that form an interphase layer called the cathode electrolyte interphase (CEI), where such reactions are concomitant with a crystallographic reconstruction of the surface of the bulk material. The CEI is air sensitive, disordered, nanometers thick and evolves as a function of state of charge and cycle number, making it difficult to fully understand its composition and effect on device performance. The dynamic nature of the CEI necessitates development of chemical characterization tools that can analyze surface reactivity during battery operation. Commercial cathode films are also composites including not just the electrochemically active material but also conductive carbon additive and polymer binder, meaning we need spatially resolved tools to study CEI composition across the film to isolate reactivity by film component. In this thesis, we have developed and applied spatially resolved and operando characterization tools to study the CEI of low-Co and Co-free cathode materials and use these data to pinpoint the degradation reactions at play during battery operation. In the first chapter, we introduce the three most prevalent types of cathode materials (layered, spinels, and olivines) used in Li-ion batteries. We then highlight recent progress in the analytical characterization tools that have been developed to elucidate CEI composition, spatial arrangement, and formation pathways during battery operation while discussing the difference in surface reactivity between each cathode active material as revealed by these techniques. Major findings from my own thesis work, detailed in following chapters, are discussed in parallel within this broader context. Finally, equipped with a deeper understanding of the CEI and the processes that lead to its formation, we discuss what remains to be discovered and enabled by optimizing these complex interfaces. The second chapter investigates the composition of the CEI formed by the Li-rich layered cathode material, Li₂RuO₃, to better understand performance decline in this class of materials. To bridge this gap in understanding, we use solid-state NMR (SSNMR) and surface-sensitive dynamic nuclear polarization (DNP) NMR to achieve high resolution compositional assignment of the CEI. We show that the CEI that forms on Li₂RuO₃, when cycled in carbonate-containing electrolytes, is similar to the solid electrolyte interphase (SEI) that has been observed on anode materials, containing components such as polyethylene oxide (PEO) structures, Li acetate, carbonates, and LiF. The CEI composition deposited on the cathode surface on charge is chemically distinct from that observed upon discharge, supporting the notion of crosstalk between the SEI and the CEI, with Li+-coordinating species leaving the CEI during delithiation. We use electrochemical impedance spectroscopy (EIS) to assess the impedance of the CEI on Li₂RuO₃ as a function of state of charge in connection with the migration of CEI species as identified with NMR. Migration of the outer CEI combined with the accumulation of poor ionic conducting components on the static inner CEI may contribute to the loss of performance over time in Li-excess cathode materials. This work demonstrates the utility of SSNMR for studying electrolyte decomposition at the cathode-electrolyte interface which is then applied in the following chapter to more commercially relevant materials. In the third chapter, we study the CEI and surface reactivity of the Ni-rich layered material LiNi₀.₈Mn₀.₁Co₀.₁O₂ (NMC811). The high specific capacities of Ni-rich transition-metal oxides have garnered immense interest for improving the energy density of Li-ion batteries. However, Ni-rich cathodes suffer from interfacial instabilities that lead to formation of electrochemically inactive phases at the cathode particle surface as well as the formation of a CEI layer on the composite surface during electrochemical cycling. We use a combination of ex situ SSNMR spectroscopy and X-ray photoemission electron microscopy (XPEEM) to provide chemical and spatial information, on the nanometer length scale, on the CEI deposited on NMC811 composite cathode films. XPEEM elemental maps offer insight into the lateral arrangement of the electrolyte decomposition products that comprise the CEI and paramagnetic interactions (assessed with electron paramagnetic resonance (EPR) and relaxation measurements) in 13C SSNMR provide information on the radial arrangement of the CEI from the NMC811 particles outward. Using this approach, we find that LiF, Li₂CO₃, and carboxy-containing structures are directly appended to NMC811 active particles, whereas soluble species detected during in situ 1H and 19F solution NMR experiments (e.g., alkyl carbonates, HF, and vinyl compounds) are randomly deposited on the composite surface. We show that the combined approach of ex situ SSNMR and XPEEM, in conjunction with in situ solution NMR, allows spatially resolved, molecular-level characterization of paramagnetic surfaces and new insights into electrolyte oxidation mechanisms in porous electrode films. The in situ solution NMR cell developed here is one of the first of its kind developed specifically for studying electrolyte decomposition products during or directly after battery operation, which is further developed in the next chapter. The fourth chapter focuses on studying the surface reactivity of the high-voltage LiNi₀.₅Mn₁.₅O₄ (LNMO) spinel cathode material. Unfortunately, LNMO-containing batteries suffer from poor cycling performance because of the intrinsically coupled processes of electrolyte oxidation and transition metal dissolution that occurs at high voltage. In this work, we use operando EPR and NMR spectroscopies to study these high voltage reactions, applying the in situ cell design from the previous chapter to operando conditions (characterization during battery charging). We demonstrate that transition metal dissolution in LNMO is tightly coupled to HF formation (and thus, electrolyte oxidation reactions as detected with operando and in situ solution NMR), indicative of an acid-driven disproportionation reaction that occurs during delithiation (battery charging). Leveraging the temporal resolution (s-min) of magnetic resonance, we find that the LNMO particles accelerate the rate of LiPF6 decomposition and subsequent Mn²⁺ dissolution, possibly due to the acidic nature of terminal Mn-OH groups and protic species generated upon oxidizing the solvents. X-ray photoemission electron microscopy (XPEEM) provides surface-sensitive and localized X-ray absorption spectroscopy (XAS) measurements, in addition to X-ray photoelectron spectroscopy (XPS), that indicate disproportionation is enabled by surface reconstruction upon charging, which leads to surface Mn³⁺ sites on the LNMO particle surface that can disproportionate into Mn²⁺(dissolved) and Mn⁴⁺(s). During discharge of the battery, we observe high quantities of metal fluorides (in particular, MnF₂) in the cathode electrolyte interphase (CEI) on LNMO as well as the conductive carbon additives in the composite. Electronic conductivity measurements indicate that the MnF₂ decreases film conductivity by threefold compared to LiF, suggesting that this CEI component may impede both the ionic and electronic properties of the cathode. Ultimately, to prevent transition metal dissolution and the associated side reactions in spinel-type cathodes (particularly those that operate at high voltages like LNMO), the use of electrolytes that offer improved anodic stability and prevent acid byproducts will likely be necessary. In the fifth chapter, we conduct an in situ X-ray spectroscopy, electron microscopy, and electron diffraction experiment to study the oxidation of the surface of Li metal, which is of critical importance for next generation Li metal batteries. Elemental Li is one of the most promising anode materials for high energy density Li batteries if it can replace graphite because it increases the specific capacity by an order of magnitude. However, Li metal is extremely reactive and is easily oxidized by air and moisture, even under inert conditions (e.g., in argon-filled gloveboxes, ultrahigh vacuum chambers). The industrial production of Li metal anodes, their surface evolution upon contact with the electrolyte, and electrodeposition behavior upon battery cycling all rely on the initial oxidative processes that take place prior to cell assembly. To better understand Li metal oxidation, we deposit pure Li on a Cu substrate and dose the Li deposit with various amounts of oxygen gas. During this experiment, we monitor the surface composition in situ using low-energy electron microscopy (LEEM), low-energy electron diffraction (LEED), and XPS measurements. We show that by evaporating Li onto Cu substrates, we can bypass long sputtering times needed to study commercial Li foils that usually exhibit alkali metal impurities and thick contamination layers from their external environment. Combined insights from LEED, LEEM and DFT calculations indicate that upon oxygen dosing of this ultrapure Li film, oxygen adsorbs to Li, forming a disordered layer, followed by (111) oriented polycrystalline Li₂O growth. DFT was particularly instrumental in elucidating the precise work function of the surface for the intermediate oxide phases (timescale of seconds) to correlate with trends observed via in situ LEEM imaging experiments. To conclude, we reflect on the overarching insight on cathode degradation that we have learned from these studies and discuss remaining knowledge gaps in the field. We highlight promising future avenues to study for stabilizing the cathode-electrolyte interface of these materials, such as adapting the characterization methods developed here for more high throughput study of next generation electrolyte formulations.