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Interfacial mechanics are a significant contributor to the performance and degradation of solid-state batteries. Spatially resolved measurements of interfacial properties are extremely important to effectively model and understand the electrochemical behavior. Herein, we report the interfacial properties of thiophosphate (Li

Today, the burgeoning drive towards global urbanization with over half the earth’s population living in cities, has created major challenges with regards to intracity and intercity transit and mobility. This problem is compounded due to the fact that almost always urbanization and increase in standard of living drives individual automobile ownerships. Over 95% of automobiles are presently powered by some form of fossil fuel and as an unintended consequence, urban centers have also been centers for peak greenhouse gas emissions, a major contributor to global climate change. A revolutionary solution to this conundrum is flight capable electric automobiles or electric aerial vehicles that can tackle both urban mobility and climate change challenges. For such advanced electric platforms, energy storage and delivery component is the vital component towards achieving takeoff, flight, cruise, and landing. The requirements and duty cycle demands on the energy storage system is drastically different when compared to the performance metrics required for terrestrial electric vehicles. As the widely deployed lithium ion-based battery systems are often the primary go-to energy storage choice in electric vehicle related applications, it is imperative that performance metrics and specifications for such batteries towards areal electric vehicles need to be established. In this nascent field, there exists ample opportunities for battery material innovations, understanding degradation mechanism, battery design, development and deployment of battery control and management systems. Thus, this chapter comprehensively discusses battery requirements and identifies battery material chemistries suitable for handling aerial electric automobile duty cycles. The chapter also discusses the battery cell-level metrics pertaining to electrochemical, chemical, mechanical, and structural parameters. Furthermore, specific models for battery degradation, state of health (SOH), capacity and models for full cell performance and degradation are also discussed here. Finally, the chapter also discusses battery safety and future directions of batteries that would power these next generation urban electric aircrafts.

Solid-state battery (SSB) is the new avenue for achieving safe and high energy density energy storage in both conventional but also niche applications. Such batteries employ a solid electrolyte unlike the modern-day liquid electrolyte-based lithium-ion batteries and thus facilitate the use of high-capacity lithium metal anodes thereby achieving high energy densities. Despite this promise, practical realization and commercial adoption of solid-state batteries remain a challenge due to the underlying material and cell level issues that needs to be overcome. This chapter thus covers the specific challenges, design principles and performance improvement strategies pertaining to the cathode, solid electrolyte and anode used in solid state batteries. Perspectives and outlook on specific applications that can benefit from the successful implementation of solid-state battery systems are also discussed. Overall, this chapter highlights the potential of solid-state batteries for successful commercial deployment in next generation energy storage systems.

The major challenges for the development of all solid-state batteries (ASSBs), that would be cheaper and can be charged and discharged faster, are stable solid electrolytes and robust interfacial design. We report the dual ion conduction capability of Na-based NASICON type super ion conductor materials using Na1+xMnx/2Zr2-x/2(PO4)3 (NMZP) as a candidate system [1]. This method enables the use of Na-based NASICON material family in both Na as well as Li all solid-state batteries (Figure 1a). The ionic conductivity NZMPs increased as the x value increased and x = 2 showed the highest room temperature conductivities. Crystallographic analysis using neutron diffraction revealed that conductivities observed in these materials are related to the variations in the Na-O bond length and the concentration of mobile sodium content. Using Galvano static plating and stripping tests, we show that these NMZPs boast good cycling stability against both Na and Li metals which also reveals dual ion conduction. Mechanistic investigations through postmortem SEM/EDS and XPS characterizations of the alkali metal and the cycled NMZPs confirm that the Na-Li ion exchange occurs readily in these materials when electrochemically cycled. ASSBs have several interfaces and the interface properties vary depending on the contact condition, energy states, type defects, and chemical/electrochemical stability. ASSB life and performance rely largely on these interfaces since dendrite formation, Li-depleted space-charge layer generation, and spatial variation in interfacial adhesion originate at the interfaces, which leads to battery failure. Stabilizing Li | SE interface is crucial for the development of high-energy-density solid-state batteries. Current approaches in Li metal stabilization employ energy and cost-intensive protocols that have a detrimental impact on the techno-economic feasibility of the ASSBs. This presentation will focus on the facile, electrochemical protocol for improving the interfacial impedance and contact at the Li | Li6.25Al0.25La3Zr2O12 (LALZO) interface. Implementation of a fraction of second short duration high voltage pulse to a poorly formed interface leads to a sustained improvement in contact impedance and lower overpotentials for electrodeposition and electro-dissolution [2] (Figure 1b). This high pulse protocol does not induce the formation of dendrites on the symmetric cells. This electrochemical protocol has direct application in battery formation cycles as well as online management systems for ASSBs. Reference [1]. A. Parejiya, R. Essehli, R. Amin, J. Liu, N. Muralidharan, H. M. Meyer, III, D. L. Wood, III, and I. Belharouak, ACS Energy Letters 6 (2021) 429. [2]. A. Parejiya, R. Amin, M.B. Dixit, R. Essehli, C. Jafta, D.L. Wood, and I. Belharouak., ACS Energy Lett. 6 (2021) 3669. Figure 1

Solid-state batteries are pivotal technologies for next-generation energy storage needs. However, they are plagued with various challenges from materials and interfaces all the way out to integration into devices. Herein, we discuss several new pathways that our team has evaluated to drive the research towards practical solid-state batteries. Initially, we highlight SolidPAC, which is an interactive experimental toolkit developed at Oak Ridge National Laboratory to enable the design of a solid-state battery for user-specified application requirements. The toolkit is flexible enough to assist the battery community in quantifying the impact of materials chemistry and fractions, electrode thicknesses and loadings, and electron flows on cell energy density and cost. The toolkit allows users to assess and extrapolate the impact of battery design and choice of cell components on cell-level energy density of a solid-state battery. Subsequently, we will discuss some key experimental strategies that leverage cheap and scalable electrochemical approaches towards the integration and on-line management of solid-state batteries. Specifically, these approaches are aimed to alleviate high interfacial resistances typically observed in some SSB configurations as well as to mitigate the growth of filaments within the solid electrolyte.

Solid-state batteries are promising alternatives for high-energy and -power-density rechargeable battery applications. It is vital to design and engineer SSB cells that can compete and improve on the current Li-ion battery counterparts. However, limited approaches exist today to assess and extrapolate the impact of battery designs and choices of cell components on the cell-level energy density of a solid-state battery. Herein, we introduce the Solid-State Battery Performance Analyzer and Calculator (SolidPAC), an interactive experimental toolkit to enable the design of a solid-state battery for user-specified application requirements. The toolkit is flexible enough to assist the battery community in quantifying the impact of materials chemistry and fractions, electrode thicknesses and loadings, and electron flows on cell energy density and costs and in utilizing inverse engineering concepts to correlate the cell energy density output to materials and cell design inputs. In addition to this, we will discuss a geometric modeling of composite cathode architectures to assess its impact on cell-level energy densities. Impact of packing architecture on processing parameters of a given cathode composition and thickness, as well as on achievable energy density is evaluated for a range of commonly used solid electrolyte and cathode materials. Overall, the proposed framework offers a facile exploratory methodology for establishing initial metrics for scalable processing of practical and competent SSBs.