Current Status and Prospects of Solid-State Batteries as the Future of Energy Storage

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

Design and Performance of lithium-Ion Batteries for Achieving Electric Vehicle Takeoff, Flight, and Landing

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

Managing fuel variability in LPG-based PEM fuel cell systems-I: Thermodynamic simulations

Hydrocarbon-based polymer electrolyte membrane fuel cell systems are promising solutions for auxiliary power units and remote systems. The sequence of steam reforming, water–gas shift and preferential oxidation reactors is a common fuel processing methodology. The heat released by burning the hydrogen-depleted anode waste gas is utilized to drive the endothermic reforming reaction and to generate steam, while the other two sub-processes are exothermic. Balancing these heat fluxes, while maintaining the narrow temperature windows required for each of these reactions, is a key system control challenge. Strategies based on a priori knowledge of fuel composition result in instability, reduction in system efficiency or transgression of safe limits in critical parameters when fuel composition varies. To address this, we have developed and implemented a control strategy that uses more readily measurable quantities to perform control actions, and is independent of knowledge about exact fuel composition or flow rate. In this paper, we analyze the effectiveness of the new control strategy by quantifying its effects on liquefied petroleum gas based polymer electrolyte membrane fuel cell systems. Results indicate that even in extreme cases of fuel composition variation, this control strategy enables the determination of set points such that the system efficiency and other critical parameters are held in a narrow range around optimal values.by Atul Bhargav, Maxim Lyubovsky and Marm Dixi

Modelling non-catalytic autothermal reforming for diesel based systems

by Vikas Sharma, Dixit Marm and Bhargav Atu

Oxidative activation of methane on lanthanum oxide and nickel-lanthanum oxide catalysts

In this work, lanthanum oxide (La2O3) has been studied for the methane partial oxidation reaction. We report long term experimental studies on La2O3, prepared by the solution combustion method with 5 wt% of Ni being added using chemical reduction method. Thorough characterization is done using XRD, SEM and FTIR. The activity is measured in terms of methane conversion and hydrogen and carbon monoxide selectivity. Methane oxidation is also carried out by varying the residence time, which changes the product distribution. Furthermore, methane activity is studied in the absence of oxygen and effect of pretreatment is also disused in detail. It is observed that the addition of nickel on the La2O3 catalyst (5 % Ni/La2O3) increases the catalytic activity significantly. Long term tests at isothermal conditions on both La2O3 and 5 % Ni/La2O3 catalysts are carried out to study the deteriorating effect of carbon (coke) deposition. Hydrogen production with 5 % Ni/La2O3 is significantly enhanced compared to La2O3, and it is experimentally observed that both the catalysts show excellent coking resistance capabilities.by Marm Dixit, Aparna Menon, Renika Baruah, Atul Bhargav and Sudhanshu Sharm

Oxidative steam reforming of ethanol on rhodium catalyst – I: Spatially resolved steady-state experiments and micro kinetic modeling

Oxidative steam reforming of ethanol is an important process for on board production of hydrogen in fuel cell based auxiliary power systems. Although the process has been extensively studied from a catalyst perspective, accurate models that capture species and temperature information required by model-based control algorithms during operation have not yet been developed adequately. In this work, we develop a reduced micro-kinetic model for ethanol oxidative steam reforming, which can be used in computational fluid dynamics (CFD) studies and subsequently to develop model-based control strategies. We experimentally study cordierite monolith based reactors in which Rh/CeO2 catalysts are prepared by the solution-combustion method. The catalyst system is characterized by X-ray diffraction (XRD), Scanning Electron Microscope (SEM), temperature programmed reduction and temperature programmed desorption analyses. The experimental reformer design enables measurement of species concentrations at various points along the reactor length, along with radial temperature profiles. A micro-kinetic model is adapted from the literature and validated against these experiments, with good agreement. The model results suggest a linear activation pathway for ethanol over rhodium catalysts by forming ethoxide, acetyl and acetate intermediates. After formation of single carbon species, the methane reforming pathway is followed. We expect that these studies, when coupled with transient studies will help in formulating model-based control strategies for ethanol reformers in complex fuel cell systems.by Renika Baruah, Marm Dixit, Anand Parejiya, Pratik Basarkar, Atul Bhargav and Sudhanshu Sharm

Understanding inks for porous-electrode formation

Scalable manufacturing of high-aspect-ratio multi-material electrodes are important for advanced energy storage and conversion systems. Such technologies often rely on solution-based processing methods where the active material is dispersed in a colloidal ink. To date, ink formulation has primarily focused on macro-scale process-specific optimization (i.e. viscosity and surface/interfacial tension), and been optimized mainly empirically. Thus, there is a further need to understand nano- and mesoscale interactions and how they can be engineered for controlled macroscale properties and structures related to performance, durability, and material utilization in electrochemical systems

Design of fuel cell systems laboratory for hydrogen, carbon monoxide and hydrocarbon safety

As research and development efforts in the area of fuel cells and hydrogen based energy accelerate, a large number of accidents have occurred in research laboratories. In this context, a design methodology for a simple, scaleable, modular and human-independent system for hydrogen, carbon monoxide and hydrocarbon safety in research laboratories is valuable. We have designed, developed and operationalized such a system in a pre-existing generic laboratory space. In this paper, we provide details of the mechanical, electrical and control aspects of this laboratory. We use CFD analysis to design a ventilation system, and to locate gas detectors for optimum detection time. The gas detectors, actuators, a real-time controller and other electrical components are part of a safety monitoring system that continuously gathers information, processes this information and takes appropriate action to safeguard personnel and equipment in real time. This fully operational safety laboratory is now a University-level research hub for all fuel cell (and other energy related) research activities, and is also one of a kind in the region. We also expect that the experience gained in this endeavor will be useful to other researchers in building a safe workplace.by Marm Dixit et al

Effect of Pore Connectivity on Li Dendrite Propagation within LLZO Electrolytes Observed with Synchrotron X‑ray Tomography

Li₇La₃Zr₂O₁₂ (LLZO) is a garnet-type material that demonstrates promising characteristics for all-solid-state battery applications due to its high Li-ion conductivity and its compatibility with Li metal. The primary limitation of LLZO is the propensity for short-circuiting at low current densities. Microstructure features such as grain boundaries, pore character, and density all contribute to this shorting phenomenon. Toward the goal of understanding processing-structure relationships for practical design of solid electrolytes, the present study tracks structural transformations in solid electrolytes processed at three different temperatures (1050, 1100, and 1150 °C) using synchrotron X-ray tomography. A subvolume of 300 μm³ captures the heterogeneity of the solid electrolyte microstructure while minimizing the computational intensity associated with 3D reconstructions. While the porosity decreases with increasing temperature, the underlying connectivity of the pore region increases. Solid electrolytes with interconnected pores short circuit at lower critical current densities than samples with less connected pores

In Situ Investigation of Interphase and Microstructure Effects on the Chemo-Mechanics of Thiophosphate Solid Electrolytes

Lithium thiophosphates (Li3PS4, LPS) are promising solid electrolytes for safe, energy dense solid-state batteries. However, chemo-mechanical transformations within the bulk solid electrolyte and at solidjsolid interfaces can lead to lithium filament formation and fracture-induced failure. The interdependent role of kinetically stable interphases and electrolyte microstructures on the onset and propagation of fracture is not clearly understood. Here, we investigate the effect of interphase chemistry and microstructure on the chemo-mechanical performance of LPS electrolytes. Kinetically metastable interphases are engineered with iodine doping and microstructural control is achieved using milling and annealing processing techniques. In situ transmission electron microscopy reveals how iodine diffuses to the interphase and upon electrochemical cycling pores are formed in the interphase region. Pores/voids formed in the interphase are chemo-mechanically driven via directed ion transport. In situ synchrotron tomography reveals that interphase pore formation drives edge fracture events which are the origin of through-plane fracture failure. Active Li metal has a tendency to fill the fracture region. Cycling lithium in fracture sites leads to localized stress within the solid electrolyte which accumulates and ultimately leads to catastrophic failure. Fractures in thiophosphate electrolytes actively grow toward regions of higher porosity and are impacted by heterogenity in solid electrolyte microstructure (e.g. porosity factor).</p