Engineered Protein-Based Ionic Conductors for Sustainable Energy Storage Applications.

Ion-conducting membranes are crucial in electrochemical storage and energy conversion technologies such as fuel cells, alkaline ion batteries, and redox-flow batteries. The purpose of the membrane is to prevent direct contact between the electrodes while allowing selective ions to pass through. The characteristics of the ion-conducting membranes include excellent mechanical and thermal stability, chemical resistance, high ionic conductivity, and selectivity. Polymers and polymer-based precursors make up the majority of the materials that have been used as ion-conducting membranes. However, most polymer-based membranes have issues related to poor chemical resistance, recyclability, and thermal and mechanical stability. In addition, as more sustainable materials are being sought to create a sustainable society, new environmentally friendly and economically viable materials are in high demand. The clay-based material could be an alternative for ion-conducting applications due to its porous structure, high surface area, tunable interlayer spacing, excellent thermal and mechanical stability, and high ion conductivity. Clay minerals are primarily used in water treatment, pharmaceutics, ceramics, paints, and coating industries. Furthermore, clay minerals have been used as a filler material in energy storage and conversion system to improve the thermal stability and ion conductivity in electrodes, electrolytes, and separators.Herein, we report a novel approach to making non-polymeric hybrid clay membranes using environmentally benign materials such as clay and zwitterion (i.e., sulfobetaine). These membranes with improved ionic conductivity will find immense potential in applications in energy storage and conversion systems. Such membranes have been synthesized by intercalating sulfobetaine molecules into the interlayer spacing of the bentonite clay matrix. Sulfobetaine is a zwitterion composed of quaternary ammonium cations and sulfonate anions. Leveraging the unique structure-property features that exist in zwitterions helps to alter the interlayer spacings in the clay matrix, thereby enabling ion diffusion through the silicate layers. Furthermore, it helps in the formation of a self-supporting membrane. The functionalized membrane's crystal structure and chemical composition were investigated using XRD, XPS, and ATR-FTIR. XRD was used to identify the layered structure of the silicates in clay and the increased interlayer spacing (1.15 nm to 1.8 nm) of the hybrid clay membrane. Data from XPS and ATR-FTIR confirmed the successful functionalization of clay with sulfobetaine. Furthermore, the ionic conductivity of the hybrid clay membrane was characterized using a non-aqueous lithium electrolyte solution, and found a conductivity of . This is one of the first reports showcasing how zwitterions can impart conductivity in clay silicate motifs. It suggests an easy and novel approach to transport lithium-ion through silicate layers, thereby making it suitable for use as membranes in batteries and supercapacitors. The current study demonstrates an easy and versatile approach to developing cost-effective and eco-friendly membranes from sustainable materials such as clay, which, when functionalized, has the potential to be a highly efficient ion-conducting material with applications in energy storage, devices, and technologies.

Our team has explored redox cycles of doped CaMnO3-δ between air and low O2 partial pressures (~10-4 bar) for high-temperature thermochemical energy storage (TCES) applications. In this study, we have explored both A-site and B-site doped compositions using earth-abundant cations to identify perovskites for cost-effective TCES in concentrated solar and other high-temperature, thermal storage applications. Reduction of doped CaMnO3-δ above 800 °C in the low P O2 requires some amount of dopant to avoid irreversible decomposition of the perovskite structure observed for reduction of undoped CaMnO3-δ [1]. This study shows that small amounts (5%) of A-site or B-site dopant can stabilize the CaMnO3-δ perovskite structure during reduction at temperatures up to 1100 °C and P O2 = 10-4 bar. For selected, stable doped CaMnO3-δ compositions, total specific TCES (Δh tot) was defined by the sum of specific sensible energy (Δh sens) and chemical energy (Δh chem) captured during heating and reduction from air at a cool temperature (T C fixed at 500 °C in this study) to low P O2 at varying high temperatures ( T H). B-site doping with 5% Cr and A-site doping with 5% Sr provided thermodynamic limits of Δh tot over 720 kJ kg-1 and 790 kJ kg-1 respectively for T H = 1000 °C. These materials were also tested kientically to assess the rates at which energy storage is captured during reduction and released during oxidation as relevant for concentrated solar energy storage applications. The results indicate that the doped CaMnO3-δ and in particular A-site doped Ca0.95Sr0.05MnO3-δ have promise as a TCES storage media with Δh chem providing just under half of the total energy stored during the combined heating and reduction. For the perovskite redox cycles, the heat of oxide reduction -ΔH O can vary with non-stoichometry δ [2]. To find the integrated Δh chem, the functional dependence of ΔH O with δ must be detemined. Two methods have been undertaken to explore this functional dependence: 1) combined TGA-DSC calorimetry measurements with incremental changes in δ, and 2) point-defect model fitting to equilibrium δ vs. P O2 data from TGA measurements [3,4]. The DSC measurements showed that the magnitude of ΔH O decreases to a near constant value for δ > 0.1 as illustrated for Ca0.95Sr0.05MnO3-δ in Figure 1. Similar trends were observed for the other perovskite compositions. The alternative method for finding ΔH O as a function of δ by fitting the equilibrium δ vs. P O2 involved modeling the perovskite reduction with two reversible point-defect reactions -- oxide-ion vacancy formation and Mn cation disproportionation from 4+ to 3+ and 5+ states [4]. The model fits originally assumed that these two reactions had enthalpies independent of δ but the contribution of the disproportionation reaction increased with δ thereby causing the combined ΔH O to have a minor dependence on δ as also shown in Figure 1. The point defect modeling did not show the same trends for ΔH O vs. δ but provided very similar values at high δ > 0.1. The integration of ΔH O over a change in δ (i.e. Δδ as in Table 1) provides a basis for calculating the integrated Δh chem as a function of T H. Integrated Δh chem values for CaCr0.05Mn0.95O3-δ, Ca0.95Sr0.05MnO3-δ, and Ca0.9Sr0.1MnO3-δ are shown in Table 1 along with the total energy stored which includes Δh sens derived from integration of CP with respect to T over the redox cycle heating. The higher Δh chem and associated Δh tot for Ca0.95Sr0.05MnO3-δ stems from its increase reducibility without a loss in heat of reaction and makes it a more promising material for TCES applications in these temperature ranges.For thermal storage application, kinetic rates of TCES capture are important, particularly for concentrated solar applications where solar receiver residence times are limited. To explore kinetics, reduction and oxidation rates of porous perovskite particle beds were measured for fitting thermodynamically consistent kinetic models to the observed rates. Kinetic testing and model fitting for the Ca0.95Sr0.05MnO3-δ indicates that it achieves approximately 80% of its Δh chem thermodynamic limit in 60 s exposure of low P O2 gas for reduction at T H = 900 °C. On the other hand, at the same temperature reoxidation occurs rapidly and releases over 90% of the Δh chem limit in 30 s. The thermodynamic consistent model involving surface kinetics and ionic bulk diffusion in the perovskite particles for Ca0.95Sr0.05MnO3-δ and for CaCr0.05Mn0.95O3-δ provide a basis for designing reactors for redox cycles to be used in TCES for concentrated solar and other potential thermal energy storage applications.

The dramatic environmental pollution and energy shortages have spurred internationally unprecedented interest in developing new energy technologies. Supercapacitors have emerged as a new class of green electrochemical devices for energy conversion and storage and are promising candidates for extensive applications. As a key component of supercapacitors, electrode materials are a crucial factor to the electrochemical performance based on its properties including surface area, pore structure, conductivity and surface functionalization. The well-designed synthesis strategies and conditions are usually fatal to tailor four mentioned properties. Due to the advantages of low cost, high specific surface area and conductivity, controllable microstructure, easy surface functionalization, remarkable chemical stability and outstanding electrolyte ion accessibility, porous carbon materials tailored through well-designed synthesis strategies and conditions, exhibit high energy density and power density as well as superb electrochemical cycling stability. In this review, we firstly provide a brief description of energy storage mechanisms for different types of electrode materials, followed by a comprehensive overview of recent advances in development of different carbon-based materials with activated carbon, carbon aerogels, carbon fiber, mesoporous carbon, carbon nanotube and graphene. Then we state the key parameters to evaluate the electrochemical properties, such as specific capacitance, energy density and power density, and also discuss the relationship between the influence parameters (e.g. surface area, pore structure, conductivity, and surface properties) and enhanced performances. Further, according to the research work of our group, we present a summary on the design, synthesis and applications in energy conversion and storage based on porous carbon materials, including carbons with different pore distributions (hierarchical porous carbon, porous carbon sphere, ultramicroporous carbon), functionalized porous carbon and porous carbon composite materials. In terms of carbons with different pore distributions, we list some characteristic synthetic methods (e.g. the self-template strategy for banana-peel-derived hierarchical porous carbon foams, the seeded synthetic strategy for phenolic-resin-derived porous carbon nanospheres and the solvothermal method for phloroglucinol-terephthaldehyde-derived ultramicroporous carbon nanoparticles), which can be concluded that micropores (especially ultramicropores) are electrochemically available for electrolyte ions because the solvation shell is squeezed through the pores less than the solvated ion size and such distortion reduces distance between the electrode surface and the ion center, while mesopores offer highly efficient pore channels for ion penetration and transport. In terms of functionalized porous carbon, we adopt the in situ synthesis approach to prepare nitrogen-doped carbons ( e.g. poly(1, 5-diaminonapthalene)-derived nitrogen-containing carbon microspheres and phenylenediamine-terephthalaldehyde-derived nitrogen-functionalized microporous carbon nanoparticles), which demonstrate that heteroatom doping, on the one hand, increases the surface wettability in the aqueous electrolyte to improve the mass transfer efficiency, and on the other hand, endows additional psedocapacitance for the electrode. In terms of porous carbon composite materials, we combine carbon-based materials with pseudocapacitive metal oxides (e.g. NiO and MnO2) for achieving high-performance supercapacitors, which is a wise choice to increase the energy density without sacrificing the high power capability. These strategies and methods provide new ideas to simple and highly efficient design of porous carbon materials and may be extendable to other systems such as metal or metal oxide materials. Additionally, the future trend of carbon based electrode materials for energy conversion and storage device is discussed. There are extensive applications outside the area of high-rate electrochemical energy storage, such as drug delivery, photonic crystals, adsorption and separation, and catalysis.

Nanoscale material designis crucial to the development of efficient renewable energy and storage technologies. While conventional research paradigms have emphasized material morphology, crystal polymorphs, and defect engineering, recent years have witnessed an emerging research interest in crystal orientation engineering since it can exploit anisotropic material properties to significantly enhance emerging energy storage and conversion applications. Herein, a comprehensive review of engineering the crystal orientation of materials to improve various energy conversion and storage technologies is provided. First, we discuss the effect of crystal orientation on material properties, including electrical conductivity, dielectric constant, surface energy, surface electronic structure, atom/molecule adsorption ability, and ionic conductivity. Then, the techniques to characterize the crystal orientation, including X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, and optical microscopy, are reviewed. After that, effectivestrategies to engineer crystal orientation using both bottom-up and top-down approaches are summarized. The advances in crystal orientation engineering in energy conversion (electrocatalysis, solar cells, and nanogenerators) and storage (metal anodes, non-metal-based electrode materials, and solid electrolytes) applications are subsequently discussed. Finally, future perspectives on the potential of crystal orientation engineering and its impact on emerging energy transition technologies are summarized.

The performance of energy storage devices is highly related to the properties of electrode materials, such as components, morphology, configurations and so on. As a typical hierarchical carbon material, three-dimensional ordered porous carbon (3D-OPC) has unique characteristics of low cost, large specific surface area, highly ordered channels, and high electronic and ionic conductivity, which shows great potential in energy storage and conversion applications. In this minireview, we summarize various template-assisted preparation methods for 3D-OPC, including hard-, ice- and self-templated approaches, and their applications in electrocatalysis, batteries and supercapacitors. Additionally, the critical roles of vertical channels in 3D-OPC when used as electrodes are also discussed. Finally, the current challenges and future research outlook of 3D-OPC are proposed.

Recent advances in the synthesis and modification of carbon-based 2D materials for application in energy conversion and storage

This review article discusses the recent advances of ionic liquid-based polymer electrolytes (ILPEs) to create innovative polymer electrolytes (PEs) and their applications in energy generation and storage. Ionic liquids (ILs) possess high ionic conductivity and are thermally, chemically, and electrochemically stable which enables their uses in electrochemical gadgets. Despite of these above-mentioned advantages, liquidus nature of ILs is the major curse for their practical application because of spillage and compactness issues. Thus, there is ever increasing need to immobilize ILs into some organic/inorganic frameworks that furnish great mechanical steadiness alongside saving the fundamental properties of ILs that can altogether give a huge scope of utilization to these materials. The ILPEs thus formed have been reported to have advantageous properties (such as high ionic conductivity, thermal, chemical, and electrochemical stability) as compared to conventionally used PEs. In this review, we have not only discussed the key advancement in the field of ILPEs but also exemplified how the adaptability of these technologically important materials especially in energy storage (rechargeable batteries) has shown momentous past and is riding toward a promising future.

Recent advances and perspectives of 2D silicon: Synthesis and application for energy storage and conversion

Novel 2D sulfur-doped V2O5 flakes and their applications in photoelectrochemical water oxidation and high-performance energy storage supercapacitors

Nanomaterials are materials with cross-sectional dimensions varying from one to hundreds of nanometers and lengths ranging from hundreds of nanometers to millimeters. Nanomaterials either occur naturally or can be produced purposefully by performing a specialized function. Until recently, most nanomaterials have been made from carbon (carbon nanotubes), transition metals, and metal oxides such as titanium dioxide and zinc oxide. In a few cases, nanoparticles may exist in the form of nanocrystals comprising a number of compounds, including but not limited to silicon and metals. The discovery of nanomaterials has played a vital role in the emerging field of research and technology. Recently, a large amount of research efforts has been dedicated to developing nanomaterials and their applications, ranging from space to electronics applications. In this chapter, we describe the role of nanoparticles in electronics and energy storage applications, with examples including chips, displays, enhanced batteries, and thermoelectric, gas sensing, lead-free soldering, humidity sensing, and super capacitor devices. The chapter also attempts to provide an exhaustive description of the developed advanced nanomaterials and different conventional and advanced techniques adopted by researchers to synthesize the nanoparticles via bottom-up techniques (pyrolysis, chemical vapor deposition, sol-gel, and biosynthesis) and top-bottom approaches (mechanical milling, nanolithography, laser ablation, and thermal decomposition).

Recently, ZnV2O4 gained a great attention of the researchers in the field of energy storage applications. The main reason is that both zinc and vanadium are economical, earth abundant and have a variety of electrochemistry to offer. The different oxidation states of vanadium deliver a vast range of redox reactions which are favorable for energy (electrochemical) storage applications. In this chapter facile and template free methods are presented for the synthesis of novel hierarchical nanospheres (NHNs), glomerulus nano/microspheres and spinel oxide nanosheets of ZnV2O4 to be used in different energy storage applications including Lithium ion batteries (LIBs), hydrogen storage and supercapacitors. Also, ZnV2O4 is studied for the thermoelectric properties to be used in thermoelectric devices. These studies overlay the way to consider ZnV2O4 as a potential candidate for energy storage applications in future. This comprehensive review will boost the relevant research with a view to work on further performance enhancement of ZnV2O4 materials.

Recent progress in emerging hybrid nanomaterials towards the energy storage and heat transfer applications: A review

The promising frontier for next-generation energy storage and clean energy production: A review on synthesis and applications of MXenes

The Renaissance of Liquid Metal Batteries

Two-dimensional MXenes have emerged as exceptional electrode materials for supercapacitors (SCs), making them highly attractive for energy storage and conversion applications. However, their electrochemical performance is strongly influenced by surface terminal groups and interlayer spacing. In this study, we introduce an ultraviolet(UV)-induced nitrogen-doping method that employs UV radiation to promote the thermal decomposition of ammonium oxalate while inducing nitrogen-doping. The resulting UV-induced nitrogen-doped Ti3C2Tx (I-Ti3C2Tx-N) exhibits a high N doping level of 1.46 at. % and an expanded lattice spacing of 1.43 nm. As a result, I-Ti3C2Tx-N demonstrates exceptional pseudocapacitance performance, achieving a remarkable specific capacitance of 466.28 F g-1, significantly exceeding that of raw Ti3C2Tx (367.96 F g-1). Furthermore, when integrated into a quasi-solid-state SC device, it delivers an impressive energy density of 12.58 Wh kg-1 at a power density of 250.00 W kg-1. The enhanced electrochemical performance of I-Ti3C2Tx-N is attributed to the effects of UV radiation, which introduces N terminal groups, eliminates detrimental -F and -OH terminals, and increases interlayer spacing. This study highlights a simple yet effective UV-induced nitrogen-doping method for modifying MXene materials, offering another way for optimizing their electrochemical properties in energy storage applications.