Energy Conversion And Storage Research Articles

Engineered Two-Dimensional Transition Metal Dichalcogenides for Energy Conversion and Storage.

Designing efficient and cost-effective materials is pivotal to solving the key scientific and technological challenges at the interface of energy, environment, and sustainability for achieving NetZero. Two-dimensional transition metal dichalcogenides (2D TMDs) represent a unique class of materials that have catered to a myriad of energy conversion and storage (ECS) applications. Their uniqueness arises from their ultra-thin nature, high fractions of atoms residing on surfaces, rich chemical compositions featuring diverse metals and chalcogens, and remarkable tunability across multiple length scales. Specifically, the rich electronic/electrical, optical, and thermal properties of 2D TMDs have been widely exploited for electrochemical energy conversion (e.g., electrocatalytic water splitting), and storage (e.g., anodes in alkali ion batteries and supercapacitors), photocatalysis, photovoltaic devices, and thermoelectric applications. Furthermore, their properties and performances can be greatly boosted by judicious structural and chemical tuning through phase, size, composition, defect, dopant, topological, and heterostructure engineering. The challenge, however, is to design and control such engineering levers, optimally and specifically, to maximize performance outcomes for targeted applications. In this review we discuss, highlight, and provide insights on the significant advancements and ongoing research directions in the design and engineering approaches of 2D TMDs for improving their performance and potential in ECS applications.

Pseudocapacitance behavior enables efficient and stable electrochemical energy conversion and storage in glucose/air enzymatic biofuel cells

Constructing an integrated system with high-efficiency and stable energy conversion and storage (ECS) is of great significance but remains challenges. Herein, we report a biodevice consisting of a bioanode of tetrathiafulvalene/glucose oxidase (TTF/GOx) immobilized on asphalt-derived porous carbon (APC) for catalyzing glucose oxidation and a biocathode of 2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonate)/bilirubin oxidase (ABTS/BOD) immobilized on APC for catalyzing oxygen reduction, to achieve ECS with high-efficiency and excellent stability. The redox mediators, TTF and ABTS, used at the bioanode and biocathode, respectively, simultaneously mediate electron transfer to release electric current on discharging and serve as pseudocapacitors to achieve charge storage at open-circuit conditions, enabling high power density and self-charge capability. The biodevice of the above configuration delivers a peak power output of 5.01 mW cm−2 in the pulse discharge mode with cell voltage remaining 93.7 % of its initial value after 100 pulse discharge/self-charge cycles. This work provides a highly efficient solution to address the low power density and poor stability of the conventional enzymatic biofuel cells, showing great implications for small, implantable and wearable electronics.

Preparation of MXene and its application and research progress in supercapacitors

As a new type of two-dimensional nanomaterial, two-dimensional transition metal carbon/nitride (MXene) has attracted much attention because of its high specific surface area, high conductivity and solvability. MXene is often used as a basic material to construct macroscopic composites. In recent years, it has been used to manufacture MXene structural-functional integrated fiber materials and mqd derivatives of MXene, which has a wide application prospect in multifunctional fibers, energy conversion and storage (ECS), sensors, catalysis and lubrication, electromagnetic shielding (EMI), supercapacitors (SCs) and so on. And has achieved some results. In this paper, the international research progress of MXene materials in recent years is reviewed, and its structure, properties and preparation methods are summarized. On this basis, its development in the field of energy storage (such as supercapacitors) is summarized, the shortcomings in this field are pointed out, and the future development trend is prospected.

Galvanically Displaced Noble Metal Nanoparticles Onto Electrosprayed Graphene-CNT Electrodes for Lithium-Ion and Fuel Cell Applications

Advanced lithium-ion batteries (LIB) and Fuel Cells demonstrate promise as the next generation energy storage and conversion (ESC) technology especially as it pertains to wearable technology and electric vehicles. Although LIB dominate the battery market (>90%) due its reliability, long cycle life, and market maturity, different and more innovative ways to improve the chemistry of the electrode structure must be discovered in order to reduce the cost of materials, dendritic issues at the solid-electrolyte interphase (SEI) layer, and improve upon the limited anode capacity (graphite theoretical capacity 372 mAh g-1). Fuel cells are also promising renewable energy sources due to their high energy densities and scalability. However, both LIB and Fuel Cells are limited by the 3D materials that enable their enhanced electrochemical and catalytic performance. We propose a platform methodology for the synthesis of 3D electrodes with carbon nanomaterials and noble metals. The enhanced electrical, thermal, chemical, and mechanical stability of graphene and carbon nanotubes (CNTs) offer an ideal platform for electrode design for energy storage applications. Here we utilize spontaneous galvanic displacement driven by reduction potential difference to produce three-dimensional (3D) graphene-CNT-noble metal nanoparticle 3D electrode without the use of any harsh chemical reducing agents. A graphene-CNT slurry with a poly(acrylic acid) (PAA) binder is air-controlled electrosprayed onto copper foil to create 3D composite thin film electrodes. Although noble metals are expensive materials to be used in LIB, we propose a new approach for synthesizing conductive electrochemically stable electrodes. We demonstrate a spontaneous technique to reduce the noble metal salts by galvanically displacement with the copper substrate to deposit noble metal nanoparticles onto the graphene-CNT electrode. The noble metal salt solutions (HAuCl4, K2PtCl4, and Na2PdCl4) are drop casted onto the resulting copper supported graphene-CNT electrodes to enable electroless noble metal nanoparticle deposition. Scanning electron microscopy (SEM) imaging confirms that the carbon nanomaterials are integrated with noble metal nanoparticles forming an overall 3D electrode structure. Raman spectroscopy verifies the characteristic D-band, G-band, and 2D-band peaks from the graphitic structure within the 3D carbon and noble metal nanostructure. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) are used to characterize the electrochemical properties of the electrodes. We demonstrate that the use of an energy-free and spontaneous process based on the difference in thermodynamic reduction potentials as the driving force for producing carbon nanomaterial/noble metal nanostructured electrodes for batteries and fuel cells. This process is a more simple, scalable, and cost-efficient alternative to current methods for developing lightweight and catalytic electrodes for energy storage applications, such as lithium-ion batteries, lithium-air batteries, and fuel cells. Raman Spectroscopy is used to confirm the presence defects on the oxidized carbon nanotube and graphene oxide surface. Scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), and x-ray diffraction (XRD) were used to characterize the morphology of the 3D carbon-noble metal structure and the surface elemental composition. Electrochemical characterization techniques such as electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), performance testing for oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), and potentiostatic measurements are used to characterize the areal specific resistance (ASR), areal capacitance, electrochemical surface area, initial Coulombic efficiency (ICE), rate capability and cycling performance, and electrochemical stability, respectively.

Three‐dimensional printing of graphene‐based materials for energy storage and conversion

AbstractDeveloping high‐performance energy storage and conversion (ESC) device relies on both the utilization of good constituent materials and rational design of assembly structure. Graphene‐based materials, due to their superior properties like high electrical/thermal conductivity, large surface area, and unique optical properties, have been extensively reported for ESC applications. The emerging three‐dimensional (3D) printing techniques, especially extrusion‐based direct ink writing technique, have brought a revolutionary improvement in structure control accuracy and designing capability to graphene‐based macro‐assemblies, triggering a boost in functionalities and performances of graphene‐based ESC devices. In these circumstances, understanding the very recent progress of 3D‐printed graphene materials and their design philosophy to bring new concepts for material designs and address the requirements for high‐performance ESC devices are urgently important. In this review, we aim to outline recent developments in 3D printing of graphene‐based materials and their applications in ESC applications. Basic requirements and theoretical analysis for preparation printable inks are discussed, as well as feasible GO ink preparation strategies in existing literatures. The representative explorations of 3D‐printed graphene materials in ESC applications like batteries, supercapacitors, solar steam generators, and electro‐thermal conversion are also reviewed. This study attempts to provide a comprehensive overview of the progresses and limitations of present 3D printed graphene materials, and seeks to enlighten the opportunities and orientations of future research in this field.

Fe‐Based Mesoporous Nanostructures for Electrochemical Conversion and Storage of Energy

AbstractDecarbonization of the global energy system requires a coordinated effort towards disruptive technology of renewable energy conversion and storage (ECS) that can be potential to secure and diversify energy systems by increasing efficiency of conversion and storage of intermittent energy sources. Porous nanostructures have been newly reported as a promising class of most effective materials for this purpose because of their unique advantages in terms of large surface‐to‐volume ratios, surface permeability, and void spaces. These offer abundant active sites for ultimate electrochemical activities by the shortening pathway of mass/charge transport. Particularly, Fe‐based mesoporous nanostructures (mp‐FeNSs) have been recently fascinating. Iron is a principal active center in nanocomposites and has high industrial suitability for next‐generation technology owing to its environment friendliness, abundance, and low cost. In this review, crucial technical advances related to mp‐FeNSs that have occurred during 2016–2020 are summarized in terms of synthesis, structural design strategy, and ECS applications such as water electrocatalysis, Li‐ion batteries, and supercapacitors. This review is supportive for potential readers to obtain general and professional information in this field since Fe‐based energy materials are exclusively introduced in the article including a fundamental understanding of electrochemistry and related technologies in detail.

Mesostructured carbon-based nanocages: an advanced platform for energy chemistry

The electrochemistry in energy conversion and storage (ECS) not only relies on the active species in catalysts or energy-storage materials, but also involves mass/ion transport around the active species and electron transfer to the external circuit. To realize high-rate ECS process, new architectures for catalysts or energy-storage electrodes are required to ensure more efficient mass/charge transport. 3D porous mesostructured materials constructed by nanoscale functional units can form a continuous conductive network for electron transfer and an interconnected multiscale pores for mass/ion transport while maintaining the high surface area, showing great promise in boosting the ECS process. In this review, we summarize the recent progress on the design, construction and applications of 3D mesostructured carbon-based nanocages for ECS. The role of the hierarchical architectures to the high rate performance is discussed to highlight the merits of the mesostructured materials. The perspective on future opportunities and challenges is also outlined for deepening and extending the related studies and applications.

Membraneless energy conversion and storage using immiscible electrolyte solutions

Breakthrough alternative technologies are urgently required to alleviate the critical need to decarbonise our energy supply. We showcase non-conventional approaches to battery and solar energy conversion and storage (ECS) system designs that harness key attributes of immiscible electrolyte solutions, especially the membraneless separation of redox active species and ability to electrify certain liquid–liquid interfaces. We critically evaluate the recent development of membraneless redox flow batteries based on biphasic systems, where one redox couple is confined to an immiscible ionic liquid or organic solvent phase, and the other couple to an aqueous phase. Common to all solar ECS devices are the abilities to harvest light, leading to photo-induced charge carrier separation, and separate the products of the photo-reaction, minimising recombination. We summarise recent progress towards achieving this accepted solar ECS design using immiscible electrolyte solutions in photo-ionic cells, to generate redox fuels, and biphasic “batch” water splitting, to generate solar fuels.

Metal–Organic Framework-Based Materials for Energy Conversion and Storage

Metal–organic frameworks (MOFs) have emerged as desirable cross-functional platforms for electrochemical and photochemical energy conversion and storage (ECS) systems owing to their highly ordered ...

Tuning the Selectivity and Activity of Electrochemical Interfaces with Defective Graphene Oxide and Reduced Graphene Oxide.

Engineered solid–liquid interfaces will play an important role in the development of future energy storage and conversion (ESC) devices. In the present study, defective graphene oxide (GO) and reduced graphene oxide (rGO) structures were used as engineered interfaces to tune the selectivity and activity of Pt disk electrodes. GO was deposited on Pt electrodes via the Langmuir–Blodgett technique, which provided compact and uniform GO films, and these films were subsequently converted to rGO by thermal reduction. Electrochemical measurements revealed that both GO and rGO interfaces on Pt electrodes exhibit selectivity toward the oxygen reduction reaction (ORR), but they do not have an impact on the activity of the hydrogen oxidation reaction in acidic environments. Scanning transmission electron microscopy at atomic resolution, along with Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM), revealed possible diffusion sites for H2 and O2 gas molecules and functional groups relevant to the selectivity and activity of these surfaces. Based on these insights, rGO interfaces are further demonstrated to exhibit enhanced activity for the ORR in nonaqueous environments and demonstrate the power of our ex situ engineering approach for the development of next-generation ESC devices.

Surface Modified MXene-Based Nanocomposites for Electrochemical Energy Conversion and Storage.

In recent years, the rapidly growing attention on MXenes makes the material a rising star in the 2D materials family. Although most researchers' interests are still focused on the properties of bare MXenes, little attention has been paid to the surface chemistry of MXenes and MXene-based nanocomposites. To this end, this Review offers a comprehensive discussion on surface modified MXene-based nanocomposites for energy conversion and storage (ECS) applications. Based on the structure and reaction mechanism, the related synthesis methods toward MXenes are briefly summarized. After the discussion of existing surface modification techniques, the surface modified MXene-based nanocomposites and their inherent chemical principles are presented. Finally, the application of these surface modified nanocomposites for supercapacitors (SCs), lithium/sodium-ion batteries (LIBs/SIBs), and electrocatalytic water splitting is discussed. The challenges and prospects of MXene-based nanocomposites for future ECS applications are also presented.

Multifunctionality of Carbon-based Frameworks in Lithium Sulfur Batteries

Compared with conventional lithium ion batteries (LIBs), lithium sulfur (Li–S) batteries possess advantages such as higher theoretical energy densities and better cost efficiencies, making them promising next-generation energy storage systems. However, the commercialization of Li–S batteries is impeded by several drawbacks, including low cycling stabilities, limited sulfur utilizations, existing shuttle effects of polysulfide intermediates, serious safety concerns, as well as inferior cycling performances of lithium metal anodes. To address these issues, researchers have achieved rapid developments for sulfur cathodes and increased their attention to lithium metal anodes to facilitate the widespread application of Li–S batteries. And among the substrate materials for electrodes in Li–S batteries being developed, carbon-based materials have been especially promising because of their multifunctionality, demonstrating great potential for application in advanced energy storage and conversion systems. In this review, recent advancements of carbon-based frameworks applied to Li–S batteries will be summarized and diverse utilization methods of these carbon-based materials for both sulfur cathodes and lithium metal anodes will be provided. Future research directions and the prospects of Li–S batteries with high performance and practicability will also be discussed.

MoS2 Nanosheets Vertically Aligned on Carbon Paper: A Freestanding Electrode for Highly Reversible Sodium Ion Batteries

The renaissance of sodium-ion batteries (SIBs) in the last few years provides a promising environmentally friendly alternative for energy storage and conversion (ESC).1 , 2 MoS2, a layered material with a large interlayer spacing along the c-axis (0.62 nm), has been attracting extraordinary attention as anode materials for SIBs. However, pure MoS2 exhibited poor rate capability and fast capacity decay upon cycling. Nanostructuring and hierarchical electrode architectures are required to facilitate transport of Na-ions within electrodes.3 Herein, we report on a rational design of freestanding anode materials for sodium-ion batteries, consisting of MoS2 nanosheets aligned vertically on carbon paper derived from paper towel.4 The hierarchical structure enables sufficient electrode/electrolyte interaction and fast electron transportation. Meanwhile, the unique architecture can minimize the excessive interface between carbon and electrolyte, enabling high ICE. When employed as freestanding electrodes for SIBs, the as-prepared MoS2@carbon paper composites delivered a high reversible capacity of 446 mA h g-1 at 20 mA g-1, high ICE (79.5%), and promising rate capability. Even at a high current density of 1000 mA g-1, a reversible capacity of 205 mA h g-1 was maintained.By exploiting in situ Raman spectroscopy, we observed the reversibility of the phase transition from 2H-MoS2 to 1T-MoS2 during the sodium-ion intercalation/de-intercalation process.

Superior cycle stability of nitrogen-doped graphene nanosheets for Na-ion batteries

Sodium ion battery (SIB) is a promising power storage system for sustainable energy storage and conversion (ESC) due to the abundant worldwide Na resources and its much lower cost. In this paper, the electrochemical performance of Na+ intercalation/extraction in nitrogen-doped graphene nanosheets (N-GNS) were studied. The experimental results showed that the N-GNS exhibited high Na+ storage capacity (260mAhg−1 at 50mAg−1), good rate capability and excellent cycle performance even at a very high current density (90mAhg−1 at 500mAg−1 for 600 cycles). The superior electrochemical performance of N-GNS is due to the N-doping-induced defects structure, which makes the N-GNS suitable for the fast diffusion of the relatively large-sized Na+ with low ion-transport resistance and effective storage of Na+ during discharge–charge processes.

Carbon Nanotube Thin Films and Hybrid Structures for Supercapacitor and Fuel Cell Applications

The development of low cost and environmentally friendly energy conversion andstorage systems is currently of the utmost priority. Here we discuss the impact of chemical design of carbon nanomaterials on their performance as active materials for supercapacitor and catalyst support for fuel cell applications.Chemical modification of single-walled carbon nanotubes (SWNTs) and graphene, is a powerful means to improve the charge capacitance of the materials. By introducing oxygen-containing groups the gravimetric capacity of SWNTs and graphene can be doubled. Furthermore, the combination of 1D SWNTs and 2D graphene affords hybrid structures with enhanced synergistic electrochemical performance.We also demonstrate the advantages of functionalized SWNTs for the fabrication of SWNT thin film catalyst support layers in polymer electrolyte membrane fuel cells (PEMFCs). Introducing an optimum level of carboxylic groups in the SWNTs allows the fabrication of SWNT-based PEMFC with efficient Pt catalyst utilization. This offers an attractive route to the manufacture of highly efficient fuel cells that meet some of the US DOE 2017 technical targets.

ChemInform Abstract: Nanostructured Metal Chalcogenides: Synthesis, Modification, and Applications in Energy Conversion and Storage Devices

AbstractReview: 403 refs.

Nanostructured metal chalcogenides: synthesis, modification, and applications in energy conversion and storage devices

Advanced energy conversion and storage (ECS) devices (including fuel cells, photoelectrochemical water splitting cells, solar cells, Li-ion batteries and supercapacitors) are expected to play a major role in the development of sustainable technologies that alleviate the energy and environmental challenges we are currently facing. The successful utilization of ECS devices depends critically on synthesizing new nanomaterials with merits of low cost, high efficiency, and outstanding properties. Recent progress has demonstrated that nanostructured metal chalcogenides (MCs) are very promising candidates for efficient ECS systems based on their unique physical and chemical properties, such as conductivity, mechanical and thermal stability and cyclability. In this review, we aim to provide a summary on the liquid-phase synthesis, modifications, and energy-related applications of nanostructured metal chalcogenide (MC) materials. The liquid-phase syntheses of various MC nanomaterials are primarily categorized with the preparation method (mainly 15 kinds of methods). To obtain optimized, enhanced or even new properties, the nanostructured MC materials can be modified by other functional nanomaterials such as carbon-based materials, noble metals, metal oxides, or MCs themselves. Thus, this review will then be focused on the recent strategies used to realize the modifications of MC nanomaterials. After that, the ECS applications of the MC/modified-MC nanomaterials have been systematically summarized based on a great number of successful cases. Moreover, remarks on the challenges and perspectives for future MC research are proposed (403 references).

Editorial - Nanostructured Materials for Rechargeable Lithium Batteries

Energy and environment are two most challenging issues faced by our society today. With an ever increasing demand for oil, depletion of renewable fuel source, and dramatic climate change caused by CO2 emission, there is an urgent need for alternative energy source that is not based on fossil fuel. Consequently, wind, solar and wave generated energy has become heavily pursued; but to work with the grid, these forms of energy have to be stored and converted according to the electricity demand and scheduling. Batteries, especially rechargeable ones, are one of the primary energy storage and conversion systems. Research in batteries has gained tremendous speed recently, not only for large scale energy storage but also for power demand in a variety of electronic devices, such as cell phones, laptops, and all kinds of power tools. It is necessary to develop renewable, low-cost, and environmentally friendly energy conversion and storage systems, to replace much of the existing technology. Among many forms of batteries, the rechargeable lithium battery has become favorite because of its features in high energy density, long cycle life, and abuse-tolerant characteristic. Still there is much to be learnt and to improve. The performance of rechargeable lithium batteries strongly depends on the structures and properties of battery materials used, especially in their specific capacity, electrochemical potential, energy and power density, and cyclability. Structural improvements include size and shape modification by employing various physical and chemical approaches. In particular, nanostructured materials represent one of the most promising as this approach can effectively contribute to a decrease in the path length for lithium ion transport, reduction in internal transfer resistance, and an increase in surface area for electrochemical reactions. The design and engineering of novel nanostructured materials for rechargeable lithium batteries have become one of the most sought after strategies for the battery research and development. The objective of this special issue is to survey the current research and development of rechargeable lithium batteries and in particular, the materials used in preparing the cathode and anode for enhanced battery performance.

Thin Solid Films and Nanomaterials for Solar Energy Conversion and Energy Saving Applications

Important new applications are possible today in the fields of energy conversion and storage by the application of thin and nanostructured solid films on surfaces. These special films, or multiple films, will be integral parts of the energy systems in the near future for the production of useful thermal and electrical energy and for energy saving applications, especially in buildings. We review the research in this direction. As we are facing the threats of insufficient energy supply and the greenhouse gas emissions from the intense use of fossil sources, we realize that the impacts as well as the future of the solar energy systems have been greatly underestimated. We review the work on solar thermal systems and energy saving applications. The efficient use of solar thermal technologies is very important for the introduction of a sizeable share of environmentally friendly renewable energy sources. New and nano structured materials along with the design and the geometry of advanced systems, capable of achieving high temperatures, as well as on integrated collection and storage systems have been proposed. Recent progress in high-vacuum technology and new materials had a remarkable effect in thin-film quality and cost. As a result new thermal absorbers have appeared along with new evaluation methods. We also present work on low-e coatings and electrochromic thin films that are very important for thermal energy savings in buildings and increase the efficiency of devices. For the photovoltaic solar energy conversion we present results on thin film solar cells and the efforts on dye sensitized nanostructured and organic solar cells.

Liquid Gallium Electrode Confined in Porous Carbon Matrix as Anode for Lithium Secondary Batteries

This work was supported by the Korean Science and Engineering Foundation via the Research Centre for Energy Conversion and Storage.