Advanced Electrode Materials for Energy Storage Devices

Dear Colleagues,

With the advent of advanced technology, various portable and large-scale applications, such as consumer electronics, smart grids, electric vehicles, and potentially aircraft, have been developed to ease our livelihoods. Consequently, this has caused a jump in energy consumption of fossil fuels, leading to depletion of energy resources and environmental issues. In 1991, alternative renewable energy resources were proposed to replace traditional energy with the first commercialization of lithium-ion batteries (LIBs). Since then, a variety of inorganic materials have been tailored into advanced electrode materials to develop different energy storage devices with high performance, safety, lifespan, and cost-effective batteries.

Advanced electrode materials are key to the advancement of energy storage devices. Numerous of synthesis and fabrication techniques have been attuned to augment and produce novel electrode materials by exploring the composition of materials, doping, shape, morphology, nanostructures, surface modification, and design of electrode materials, such as graphene/carbon-inorganic materials and 3D structures. Through advanced characterization (in situ and ex situ techniques), it has been discovered that the macro- and microstructures of electrode materials can be tailored to enhance charge transfer kinetics, accelerate redox reaction rates, improve electron transport and ion diffusion kinetics, increase activity, and improve structural stability while studying their reaction mechanisms and addressing problems to establish fundamental studies.

In this Special Issue, original research articles and reviews are welcome. The papers presented in this Special Issue will provide insights into the topics related to (but are not limited by) electrode material design, synthesis, characterization, reaction mechanisms, electrode–electrolyte interfaces, and electrochemical properties and performance investigation. Both experimental and computational studies are welcome in this Special Issue. We aim to give a platform to multidisciplinary approaches to build a comprehensive fundamental understanding of advanced electrode materials for various energy storage devices.

Dr. Chek Hai Lim
Guest Editor

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• synthesis
• characterization
• electrode materials
• electrolyte
• reaction mechanism
• electrochemical properties
• nanostructure
• supercapacitors
• energy storage devices
• batteries

Title: Designing of Electrode Nanomaterials for Energy Storage Devices
Authors: Chek Hai Lim
Affiliation: Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
Abstract: Global efforts to shift from non-renewable to renewable resources are one of the strategies used to reduce greenhouse gas emissions. Emerging electrochemical energy storage devices, such as metal-alkali batteries, metal batteries, supercapacitors, and other devices, have been developed to transform renewable resources between electricity and chemical energy to power electronics, electric vehicles, and other applications. Since the introduction of lithium-ion batteries in 1991, scientists have discovered various active materials and other component materials for energy storage devices, including metal oxides and non-metal oxides, such as anode, cathode, separator, and electrolyte. Most bulk active materials are poor in electronic or ionic conductivities and tend to crack after reaching a threshold of ion storage. Thus, numerous efforts have been dedicated to developing electrode materials that could contribute to high power and energy densities in energy storage devices with long-term cycling stability. Nanomaterials have recently received tremendous attention due to their unique properties when reduced from bulk micron-sized to nano-sized materials. Owing to their small size, nanomaterials possess a large surface area to provide more active sites for electrochemical reactions. Another advantage of nanomaterials is the short ion diffusion path, which induces fast ionic transportation and electrochemical kinetics. Although nanomaterials can improve the conductivities of the electrodes, the instability of nanometer-sized materials has deteriorated the electrochemical performance, especially the degradation of cycling and rate-capability performances. The major drawback of the large active surface area of nanomaterials is their high contact area with electrolytes, leading to the decomposition of electrolytes to form an electrolyte interphase layer due to parasitic reactions. Another problem of the large surface area is their high surface energy, and the open surface structure tends to agglomerate into secondary particles due to thermodynamically metastable, which is not beneficial in electronic and ionic transportation and poses a difficulty in shape or morphology-controlled synthesis. Scientists have recently devoted their efforts to overcome the limitations of nanomaterials. Tuning and designing of material structures and composition could potentially produce thermodynamically stable nanostructured materials through various techniques such as structure modification, coating, spatial arrangement, and assembly of nanostructured materials into micro/nanostructure (3D structures). We, therefore, reviewed the fundamental aspects of mitigating the side effects of various dimensional nanomaterials for energy storage devices. Surface modification and structural design of heterogeneous nanostructures with synergetic properties are also presented to explore the contemporary state-of-the-art rational design of various dimensional nanomaterials with different complexity in structure for energy storage devices. Further improving the power and energy density of electrode nanomaterials requires assembling nanostructured materials into densely packed hierarchical complex 3D interconnected networks (nanoarchitecture) to eliminate unused spaces or dead areas. Some examples of nanoarchitecture in constructing 3D active materials or electrodes will be provided in this review as an extension to the advancement and utilization of nanomaterials in energy storage devices.

Title: Hierarchical manganese-doped nickel–cobalt oxide electrodes with graphene for asymmetric supercapacitor with high energy density
Authors: Guan-Ting pan; Chao-Ming Huang
Affiliation: College of Science, Health, Engineering & Education, Murdoch University, 90 South Street, Murdoch WA 6150, Australia; Green Energy Technology Research Center and Department of Advanced Applied Materials Engineering, Kun Shan University, No. 195, Kunda Rd., Yongkang Dist., Tainan 710303, Taiwan
Abstract: Thin films of manganese-nickel-cobalt oxide were deposited onto copper foam using electrochemical deposition. The samples showed that NiCo2O4 was the main phase among these films. As the molar ratio of manganese in the solution increased, the concentration of oxygen vacancies in the samples also increased. The microstructure of the samples changed from ball-like structures to a hierarchical-vertical growth. At a potential window of 1.5 V, the device showed a significant capacity of electrodes (~472 F/g) and excellent cycling stability of 95.0% of the initial capacity retention over 10,000 cycles. The exceptional electrochemical performances of the manganese-doped nickel-cobalt oxide electrodes with graphene were due to the synergistic effect of hierarchical manganese-doped nickel-cobalt oxide electrodes with graphene, mesoporous structure, three-dimensional Cu foam collector, and binder-free preparation. These factors facilitated faster diffusion of the electrolyte ion into the electrode material and provided a stronger adhesion of active materials with the current collector.

Title: The improvement of low-temperature lithium-ion batteries.
Authors: Chong Yan
Affiliation: Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing, 100081 P.R. China
Abstract: The improvement of low-temperature lithium-ion batteries.

Title: Multicomponent (Fe, Co, Ni) metal selenide Nanoparticles Derived from Fe X (X = Co,Ni,) MOF as anode materials for Na-ion batteries
Authors: Xiongwu Kang
Affiliation: New Energy Research Institute, School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006, China
Abstract: Transition metal selenides (TMSs) have been utilized as promising anodes for sodium-ion batteries (SIBs) due to their high energy capacity. In comparison to single metal selenides, multiple metal selenides have been investigated in recent studies due to their excellent electrical conductivity and richer active sites. It is believed that the incorporation of multiple metal selenides with carbon could enhance both the ion transfer rate and the stability of the material. Here, a simple hydrothermal method was employed to synthesize the MOF-derived selenization strategy for the in-situ synthesis of carbon-doped selenide as the anode material for a sodium-ion battery. In this study, two types of binary transition metal selenides (BTMSs), namely iron-cobalt selenide (Fe2CoSe4@NC) and iron-nickel selenide (Fe2NiSe4@NC) nanoparticles, were synthesized and utilized in SIBs. These two materials exhibit excellent long-term cycling and rate performance, retaining a capacity of 352 and 282.2 mAh g−1 after 2100 cycles at 1.0 A g−1, with outstanding rate capabilities of 270 and 270 mAh g−1 at 10 A g−1, respectively. This straightforward strategy could be extended to the synthesis of various other transition metal selenides, serving as a reference for the development of novel materials for sodium-ion batteries. Keywords: transition metal selenides; sodium-ion batteries; Fe2CoSe4@NC; Fe2NiSe4@NC; nanoparticles; simple strategy

Title: An Overview of the Ionic Liquids and Their Hybrids Operating in Electrochemical Cells and Capacitors
Authors: José Pereira1, Reinaldo Souza1, António Moreira1 and Ana Moita 1,2,*
Affiliation: 1. IN+ Center for Innovation, Technology and Policy Research, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisboa, Portugal; 2. CINAMIL – Military Academy Research Center, Dep. of Exact Sciences and Engineering, Portuguese Military Academy, Amadora, Portugal
Abstract: The present work of review is focused on the recent advancements regarding the exploration of the ionic liquids, ionic liquids with the incorporation of nanoparticles of several materials, and ionic liquids-grafted nanoparticles operating as liquid electrodes in electrochemical cells and capacitors. The ionic liquids are generally synthesized at room temperature and by adding a solution, which can be an acid, a base, or a salt in water, and are composed of organic cations and a great number of charge-delocalized organic/inorganic anions. The electrochemical features such as the electrical conductivity and capacitance of the promising ionic liquids and their hybrids is addressed thor-oughly, together with their influencing factors like the nature, concentration, and functionaliza-tion of the nanoparticles, type of base fluids, working temperature, and addition of surfactants. Moreover, this overview identifies and discusses the main applications of the ionic liquids and their hybrids with nanoparticles in various possible electrochemical devices configurations, along with a brief evaluation of the associated feasibility issues. Additionally, this survey of the pub-lished scientific papers on the subject enabled the listing and evaluation of the beneficial features related to the usage of these fluids including an enhanced electrical conductivity and improved capacitance in comparison with the commonly employed solvents and electrolytes. Finally, it addresses the main problems associated with such types of fluids and outlines the primary pro-spects for further research and use of the ionic liquids and their nanocomposites in different electrochemical technological applications.

Title: synthesis and characterization of a new kind of functionalized hexagonal boron nitride which has potential for battery and other applications.
Authors: Karoly Nemeth
Affiliation: Physics Department, Illinois Institute of Technology, 3101 South Dearborn St., Chicago, IL 60616, USA