Energy Materials

Electroceramics are functional materials with a complex interplay between structural, chemical and electrophysical properties. Significant reliability over energy storage and conversion devices has outgrown over the years in search of sustainability. The advent of eco-friendly continuous energy extraction with liberty over fuel flexibility at intermediate temperatures (400–700 °C) reveals the monopoly of proton conductors (PCs) as an effective electrolyte for proton-conducting solid oxide fuel cells (PC-SOFC). They illustrate high operation efficiency (60–80%) and energy density over existing energy storage devices (capacitors, batteries and combustion engines) with a compromise over power density. The electrochemical activity of PCs is in principle different from distinct fuel cells which are categorized on the nature of electrolyte and diffusing charge carriers alongside operating temperature regimes. PC-SOFC thus bridges the research gap between high-temperature (SOFC) and low-temperature (PEMFC) applications. The intermediate operation devoid the use of catalysts for requisite electrochemical kinetics across the electrode–electrolyte interface with simultaneous compatibility of fuel cell’s components. Unlike key limitations in SOFC owing to high operating temperatures, PC-SOFC forbids major limitations. The anti-phase consistency between chemical and electrophysical parameters obstructs the commercialization of PCs for technological advancements. The fundaments of which lie with the physics of structural perturbations and inflexions in charge chemistry. Lower symmetry shifts (distorted structures) although assist unimpeded charge dynamics, yet lag in cooperative chemical compatibility. Attempts of material engineering via heterogeneous impurity substitutions in terms of acceptor dopants at the B-site of perovskite PCs have been executed to pacify the existing trade-off. Compositional-induced charge trapping effect constituted by increasing impurities presents novel material engineering limitations. Thus, preserving the host characteristics with additional improvement in thermal, chemical and electrical properties has recently become the principal motive of research with PCs. Since the charge kinetics is determined at the electrode–electrolyte interface, suitable sealant and blend of composite electrodes with thin epitaxially grown film electrolytes have cultivated a unique research perspective. The chapter encloses the backbone of energy materials for energy conversion devices (fuel cells) with a detailed emphasis on the physics of electrochemistry in perovskite-type PCs (BaCeO₃ and BaZrO₃). The miscellaneous motive also associates compiled outcomes and a summary of novel constraints (proton trapping effect) associated with material processing and architecture.

Electrochemical energy storage is based on two factors that are systems with high energy densities (batteries) or power densities (electrochemical condensers). Electrochemical energy storage devices are required to develop portable electronics, to electrify the transport sector and power our society. EES takes the form of batteries, electrochemical condensers and supercapacitors. Other EES applications include renewable energy sources such as solar and wind to empower the electricity grid in many developed countries. Nowadays, researchers are more focused on developing high-performance electrodes for electrochemical energy storage and conversion devices. Transition Metal Nitrides (TMNs) are appropriate electrode materials because of their good catalytic properties and better electrical conductivity than oxides. This chapter mainly focuses on the fundamental properties and synthesis processes of TMNs as electrode materials in EES devices like lithium-ion batteries, sodium-ion batteries and supercapacitors and also describes their capacitive characteristics.

Various combinations of Cathode materials like LFP, NCM, LCA, and LMO are used in Lithium-Ion Batteries (LIBs) based on the type of applications. Modification of electrodes by lattice doping and coatings may play a critical role in improving their electrochemical properties, cycle life, and thermal behavior doping with metal ions like Al⁺³ and Zr⁺⁴ and surface coating can enhance the properties of these materials. Increased thermal stability in charged states, stabilized cycling with reduced capacity fading, and minimal side reactions are desirable for good battery performance. The Li- and Mn-rich layered composites are used which have two layered structures as well as the Ni-rich lithiated transition metal oxide of Ni, Mn, and Co are used for improved performance.

Dye-Sensitized Solar Cells (DSSC) have evolved as an aspiration for economical solar cells in the era of expensive silicon and thin film-based solar cells. DSSC features low-cost, low-toxic materials, easy fabrication processes, and mainly indoor applications, thus overall escalating its potential and establishing it as efficient, eco-friendly low-weighted solar cells. DSSC includes photoanode, sensitizer (dye), electrolyte, and counter electrode, each having particular challenges and countering its growth in a commercialized way. Untangling those issues, we have reached a maximum efficiency value of 14.3% for DSSC at the laboratory scale. To eliminate the challenge of DSSC parts and enhance the efficiency of DSSC, we have to examine the research that has contributed to current and future advancements. Therefore in this book chapter, the historical overview, working and importance of constitutional parts, and mainly the state-of-the-art of each part of DSSC have been thoroughly discussed. Along with this, future prospects like graphene-based electrodes, inkjet printer dyes, advanced catalysts, sealants etc., could greet towards green commercialized DSSC.

With the rising population and simultaneous increasing demand for energy to run the current lifestyle, there is an immense requirement to develop a method to sustain the non-renewable source of energy, solar cell is one of them. In the current book chapter, we aim to study the fabrication and characterization of SiNW’s hybrid solar cells. A hybrid solar cell consists of both organic and inorganic materials. In this book chapter, we have studied the methods to prepare SiNWs, reduced graphene oxide and reduced graphene oxide P Poly (3,4-ethylene dioxythiophene) Polystyrene Sulfonate composite for their application in the SiNWs hybrid solar cell. The morphological analysis of the samples has been done using scanning electron microscopy, and structural characterization of the samples was done using X-ray diffraction and Raman spectroscopy. Finally, the electrical characterization of the solar cells has been studied using the current-density voltage characteristic curves. This book chapter also provides the readers to understand of the fundamentals of a basic solar cell and the way to fabricate a hybrid solar cell most efficiently.

Fuel cells are devices that allow for the direct conversion of the enthalpy of combustion, or chemical energy, of fuels into electricity. A high ionic mobility suggests that the ions have relatively small ionic radii and just one charge. This is due to the fact that ions that have double or triple charges frequently display significant Coulomb interactions (O²⁻ is an exception). Ions have to originate from one of the reactants, which might be either the fuel or the oxygen. This is another condition. Therefore, the ions H⁺, OH⁻, and O²⁻ are necessary for fuel cells to function properly. There is often just one type of ion that can move about freely. This chapter will focus on protons since they are the most mobile charged particles. There is a connection between proton mobility and proton diffusion. Experimentally, proton diffusion cannot be measured by looking at macroscopic properties that depend on the concentration of protons because that would break the electro-neutrality condition. So, we cannot start from a situation that is not in equilibrium or from a difference in the chemical potential. However, it is conceivable for the electric field to have gradients. This indicates that the proton conductivity may be measured by the use of an electric field, and after that, the proton conductivity diffusion coefficient can be determined through the application of the Nernst-Einstein relation. The macroscopic proton conductivity is the most vital physical parameter that represents the efficient quality of the ceramic electrolyte. This is because macroscopic proton conductivity has an effect on how fuel cells are manufactured as well as how well they perform. However, from a more basic point of view, knowing merely the “proton conductivity” value at the macroscopic level is not sufficient. Additionally, one must have an understanding of how the proton can move about, how atoms can leap, and how molecules move on atomic sizes of space and time. Atoms or molecules on well-defined lattice sites are responsible for the series of site changes that make up solid-state diffusion. These site changes are referred to as “hops.” The nature of the lone event, or its underlying mechanism, is one component. How does an atom go from the lattice site it is now occupying to a site that is adjacent to it, and how does it do a site exchange? This is accomplished, in the case of a heavy atom, by a classical leap over the barrier that is produced by the interaction potential, which is triggered by heat. On the other hand, the interaction potential does not remain constant because of the vibrations of the lattice. Certain vibrational modes unlock the door between two locations, therefore reducing the possibility for a barrier in this direction to a far greater extent. Therefore, there is a significant connection between diffusion and the movement of the lattice (vibrates). Diffusion is a process that is governed by quantum mechanics and involves tunneling, often known as “hopping,” for light atoms, like the different forms of hydrogen. Numerous studies have been conducted, and researchers have come up with two primary explanations for the phenomenon of proton transfer. The first mechanism is known as the Grotthuss mechanism, while the second mechanism is known as the vehicle mechanism. The Grotthuss mechanism, which is also known as “structure diffusion,” has a step that causes the process to move more slowly than the others. This step is the diffusion of the structure, which refers to the pattern of hydrogen bonds. This step is brought about by the back-and-forth tunneling of the extra proton. During the process known as the vehicle mechanism, a proton and the water molecules that accompany it, also known as the “vehicle,” travel in huge quantities across a cation species.

In the current scenario, the materials research activity plays a crucial role in the areas such as multiphase composite cathodes, ceramics anodes and electrolyte for solid oxide fuel cell (SOFC) applications. With the recent trends towards the lowering of SOFCs operating temperature, recent research activities have been focusing on developing new electrodes, electrolyte and metallic interconnects; this presents a whole new matrix of possible material interactions. The engineering of novel materials has been much more complicated than simply optimizing the electrochemical performance of a known one. Particularly, the cathode materials for SOFC applications have a challenging task. The noble metals, which had been used in the early days, have fallen out of favour on cost basis. Hence, multiphase composite cathode materials have much more importance in recent days. The key role of the cathode is to make the maximum number of available reaction sites for the electrochemical reduction of the oxidant. In this chapter, we have discussed perovskite manganite metal oxides, particularly lanthanum manganite materials for the recent advancements as well as its challenges. An overview of the other type of perovskite cathode materials and effect of porosity for SOFC applications has also been discussed.

This chapter presents the application of graphene oxide/silicon nanowires in photovoltaics. The current scenario of energy in the world shows the requirement for renewable energy for meeting the energy requirements of the people without harming the environment. Solar energy is an important source of sustainable energy. The sunlight is converted into electrical energy using the principle of photovoltaics. Silicon nanowires and graphene oxide serve as promising candidates for application in photovoltaics due to their excellent properties which are discussed in this chapter. Furthermore, recent studies in the silicon nanowire/graphene heterojunction are discussed.

Oxide-ion conductor solid electrolytes are useful for intermediate-solid oxide fuel cell (IT-SOFCs) applications. SOFCs are electrochemical devices, i.e., it converts chemical energy into electrical energy based on fuel supply. SOFCs are known for clean, green, environmentally friendly, and high-efficiency energy conversion devices. Fossil and oil resources are vanishing rapidly, so looking into alternative energy conversion devices is essential. The high operating temperature made SOFCs more attractive over the other fuel cells. The operating temperature puts constraints on large-scale industry applications. Existing commercial electrolytes YSZ required more than 800 °C operating temperature. To bring down the operating temperatures below 600 °C, CeO₂ is the alternate material, which shows much-improved oxide-ion conductivity of less than 700 °C. SOFC is a three-component device, i.e., it consists of an anode, electrolyte, and cathode. Single-component SOFC is more advantageous than the three-component device. The present chapter focuses on recent developments of solid electrolytes, single components (composite electrolytes), and three-component SOFCs concerning the structure and electrical properties.

Sustainable methods of harvesting energy are becoming increasingly important for the growing world. Improvements in the energy sector, such as the exploration and evaluation of materials that are both abundant on Earth and relatively inexpensive, are urgently needed to meet the twin goals of efficient energy use and environmental protection. Graphene is certainly one of the revolutionary materials of the twenty-first century. With its unusual two-dimensional porous structure and many desirable properties, graphene has the potential to improve the energy and power density of electrochemical energy storage devices such as lithium-ion batteries, supercapacitors, fuel cells, and solar cells. As graphene use in energy storage and conversion applications continues to rise, it is becoming important to discuss the most recent developments in these areas. Recent developments in energy harvesting and storage using graphene-based materials are the emphasis of this chapter, specifically in the areas of supercapacitors, batteries, fuel cells, and solar cell devices.

New and improved cathode materials for better energy storage are the urgent need of the century to replace our finite resources of fossil fuels and intermittent renewable energy sources. In this chapter, an attempt is made to focus on the progress made in the field of cathode materials for lithium ion batteries (LiBs) in recent years in terms of achieving high energy and power density, and good capacity retention over multiple cycles and safety. Six classes of intercalation compounds including layered and spinel oxides and compounds belonging to olivine, tavorite, silicate and borate class are discussed in detail. Different aspects of improving the overall performance of cathode materials, for instance, improving the conductivity by coating with carbon/increasing the surface area by decreasing the size of particles are found to be advantageous. This chapter will provide the researchers with ample input for further findings and the improvisation of sustainable power output.