The Emerging Strategy of Symmetry Breaking for Enhancing Energy Conversion and Storage Performance.

Advances in nano sensors for monitoring and optimal performance enhancement in photovoltaic cells

As global energy consumption accelerates at an alarming rate, the development of clean and renewable energy conversion and storage systems has become more important than ever. Although the efficiency of energy conversion and storage devices depends on a variety of factors, their overall performance strongly relies on the structure and properties of the component materials. Nanotechnology has opened up new frontiers in materials science and engineering to meet this challenge by creating new materials, particularly carbon nanomaterials, for efficient energy conversion and storage. As a building block for carbon materials of all other dimensionalities (such as 0D buckyball, 1D nanotube, 3D graphite), the two-dimensional (2D) single atomic carbon sheet of graphene has emerged as an attractive candidate for energy applications due to its unique structure and properties. Like other materials, however, a graphene-based material that possesses desirable bulk properties rarely features the surface characteristics required for certain specific applications. Therefore, surface functionalization is essential, and researchers have devised various covalent and noncovalent chemistries for making graphene materials with the bulk and surface properties needed for efficient energy conversion and storage. In this Account, I summarize some of our new ideas and strategies for the controlled functionalization of graphene for the development of efficient energy conversion and storage devices, such as solar cells, fuel cells, supercapacitors, and batteries. The dangling bonds at the edge of graphene can be used for the covalent attachment of various chemical moieties while the graphene basal plane can be modified via either covalent or noncovalent functionalization. The asymmetric functionalization of the two opposite surfaces of individual graphene sheets with different moieties can lead to the self-assembly of graphene sheets into hierarchically structured materials. Judicious application of these site-selective reactions to graphene sheets has opened up a rich field of graphene-based energy materials with enhanced performance in energy conversion and storage. These results reveal the versatility of surface functionalization for making sophisticated graphene materials for energy applications. Even though many covalent and noncovalent functionalization methods have already been reported, vast opportunities remain for developing novel graphene materials for highly efficient energy conversion and storage systems.

Efficient electrocatalysts play a pivotal role in renewable energy technologies and numerous essential industrial processes. Currently, inorganic materials, especially noble metals or their oxides, are the most widely used catalysts. However, these catalysts often face several drawbacks, such as limited flexibility, high costs, and low efficiency. Recently, gel materials have gained attention in many fields including advanced energy conversion and storage owing to their unique physicochemical properties. This review offers a concise yet comprehensive and critical examination of recent advancements in the field of gel-based electrocatalysts. Additionally, it systematically summarizes the unique characteristics of the latest synthetic strategies for preparing gel materials as well as the relationship between the structure of gel materials and their performance in energy conversion and storage. An overview of various reactions involved in renewable energy conversion and storage, including water electrolysis, oxygen reduction, carbon dioxide reduction, and energy devices, is presented, along with the challenges and opportunities in this domain.

With the ever-growing global energy demands and environmental pollution issues, developing high-performance energy storage and conversion materials has become a hot topic in the material science community. In this regard, substantial progress has been made in theoretically predicting new materials for energy-related fields, experimentally synthesizing these materials, and further improving their properties for high performance in energy storage and conversion devices. In particular, two-dimensional (2D) materials have shown great potential in the field of energy storage and conversion. However, it remains challenging to explore 2D materials that render high efficiency of energy storage and conversion while guarantee long-term stability and safety. Over the past decades, theoretical calculations based on density functional theory (DFT) have become a practical toolkit to address this issue by revealing the reaction mechanism at an atomic scale and screening high-performance energy storage and conversion materials on a large scale. In particular, DFT calculations enable us to establish the relationships between the intrinsic properties of materials and their performance for energy storage and conversion, and provide theoretical guidance for screening and experimentally synthesizing the promising materials. In this review, we summarize the DFT calculations’ applications in recent studies of developing high-performance and reliable energy-related 2D materials for Li-ion battery (LIB), water splitting, fuel cells, and electrochemical carbon dioxide reduction (CRR). First, we introduce the reaction mechanism of LIB, hydrogen evolution reaction (HER), oxygen evolution reaction/oxygen reduction reaction (OER/ORR), and CRR in detail and the application of 2D material in these fields. Then, we highlight the role of DFT calculations in unveiling the intrinsic relationships between the electronic structure and the performance of 2D materials by comprehensively discussing the descriptors in predicting the performance of 2D materials. For example, the occupancy of d orbital and energy required to fill empty states serve as descriptors to predict the electrochemical performance of the electrode in ion intercalation battery. The d orbital center, lowest unoccupied states, and oxygen vacancy formation energy serve as descriptors to predict the catalytic performance of electrode in HER. The energy difference between the lowest valance electron orbital center and Fermi level, occupancy of p z orbital, and the energy difference between p z and p x /p y orbital center serve as descriptors to predict the catalytic performance of electrode in ORR. Even though these descriptors can help to further understand the relationships between the electronic structure and the performance of the electrochemical electrode, they are only reliable to specific materials and inapplicable to the electrode with a complex structure or complex reaction path, such as the electrode in CRR. Newly developed machine learning methods may bring a breakthrough to the exploration of a universal descriptor, which is a key factor in the large-scale screening of potential electrode materials with excellent performance and the dependable guidance to experimental synthesis. Finally, we summarize the disadvantage of DFT calculation, such as the underestimation of bandgap and incorrect description of van der Waals interaction, and give a perspective of DFT calculations in the study of new energy-related materials. The method to simulate the ambient environment of the electrode (including the electrolyte, external electric field, and non-cooperative transfer of proton and electron) based on DFT calculation is needed to be developed, which is vital to reflect the actual working condition of the electrode. The universal descriptor applicable to the electrode with a complex structure is also needed to explore to overcome the poor versatility of single intrinsic property of the material in predicting the performance of the electrochemical electrode.

A binary metal phosphide (NiCoP) has been synthesized in a single-step hydrothermal method, and its energy conversion (hydrogen evolution reaction; HER) and energy storage (supercapacitor) performances have been explored. The physicochemical characterization of the NiCoP nanostructures show that they have a highly crystalline phase and are formed uniformly with a sphere-like surface morphology. In acidic electrolytic conditions, the NiCoP shows excellent HER performance, requiring only 160 and 300 mV overpotential to deliver 10 and 300 mA cm−2 current density, respectively. Interestingly, it follows the Volmer–Heyrovsky reaction pathway to execute the HER with robust durability (∼15 mV increase in overpotential even after 18 h of electrolysis). In an alkaline medium (5 M KOH), NiCoP shows specific capacitance of 960 F g−1 with higher energy density (33.3 W h kg−1) and power density (11.8 kW kg−1). Moreover, it shows better reversibility (∼97% coulombic efficiency) and long cycle life (∼95% capacitance retention after 10 000 repeated cycles). The unique surface morphology and phase purity of the binary metal phosphide avails more electroactive surface/redox centers, thereby showing better electrocatalytic as well as energy storage performances. Therefore, we presume that the NiCoP would be a suitable material for future energy conversion and storage systems.

The increasing depletion of fossil fuel inspires the demand for renewable energy and energy-efficient devices. GO-based materials emerge in applications of energy storage and conversion with superior advantages. Especially, the composition of GO with specified materials not only retains the inherent characteristics of GO but also induces various characters for improving the performance in energy conversion and storage. Due to the large surface area and ample oxygen containing functional groups, GO can bind many active materials or catalysts for hydrogen storage and generation. Moreover, the functional groups enable GO to further couple with other species and thus form various porous or hierarchical architectures as electrodes, electrolyte or current collector in the lithium batteries and supercapacitors.

Core-shell nanomaterials: Applications in energy storage and conversion

The electrostatic spray method is a promising nonvacuum technique for efficient deposition of thin films from solutions or dispersions. The multitude of electrostatic spray process parameters, including surface tension, viscosity, and conductivity of the liquid, applied voltage, nozzle size, and flow rate, make electrostatic spray deposition very versatile for the morphological engineering of nanostructured films. The current state‐of‐the‐art in electrostatic spraying can produce exceptional morphologies. Such tailoring of morphologies is notably useful in electrochemical applications where high electrolyte‐accessible surface area often improves performance. Interesting morphologies of metal oxides and their composites are highlighted, including nanopillars, nanoferns, and porous microspheres produced by electrostatic spraying to enhance energy conversion and storage performance. The physics associated with the electrostatic spray process and morphology control using it are also presented. The manuscript highlights the potential of electrospray processing for producing thin films of controlled microstructure, from ultrasmooth layers in organic photovoltaics and perovskite photovoltaics to hierarchical nanostructured films for anodes and photoanodes. It aims to help researchers appreciate essential aspects of electrostatic spray deposition efficiency, process control, and morphology engineering for energy conversion (e.g., solar cell, fuel cell, and photoelectrochemical cell) and energy storage (e.g., lithium‐ion battery and supercapacitor) electrodes.

Morphology/phase-dependent MoS2 nanostructures for high-efficiency electrochemical activity

One of the greatest challenges facing our world today is climate change, brought about by the emission of greenhouse gases into the atmosphere in large part due to the massive use of fossil fuels to satisfy our society's ever-increasing energy demands. The transition to clean energy resources requires the development of new, efficient, and sustainable technologies for energy conversion and storage. Several low carbon energy resources will contribute to tomorrow's energy supply landscape, including solar, wind, and tidal power, yet rechargeable batteries will likely remain the dominant technology for storing this energy and using it in an economic and efficient manner for decades to come. For instance, the gradual replacement of internal combustion engine vehicles powered by petroleum or diesel by electric vehicles and photovoltaic power charging stations is one way we can lessen our reliance on fossil fuels. Improving the performance of energy storage and conversion devices toward higher energy and power density, and greater efficiency, durability, and safety, hinges on the development of new materials and processes, specifically, on tuning the properties of the component materials by modulating their crystal structure and microstructure, and on optimizing materials processing and device assembly protocols. Today, there is a clear need for a dedicated publication platform to cover high-impact and multidisciplinary scientific contributions that will pave the way to the next generation of energy conversion and storage devices. We expect this journal to grow in the coming years, as part of the fourth industrial revolution featuring the efficient use of renewable energies, in addition to navigating a digital world and accelerated by the current pandemic. Battery Energy is co-published by Wiley and Xijing University, China. Battery Energy covers diverse scientific topics related to the development of high-performance energy conversion/storage devices, including the physical and chemical properties of component materials, and device-level electrochemical properties. Battery Energy is a high-quality, interdisciplinary, and rapid-publication journal aimed at disseminating scholarly work on a wide range of topics from different disciplines that share a focus on advanced energy materials, with an emphasis on batteries, energy storage and conversion more broadly, photocatalysis, electrocatalysis, photoelectrocatalysis, heterocatalysis, and so on. The journal features cutting-edge research covering many forms of electrochemical and photochemical energy, including battery processes, and spanning from conventional electrical energy to the type that catalyzes chemical and biological transformations. This journal is also interested in work that prompts new technologies and processes leading to the green production of battery materials. Upcoming issues of Battery Energy will be composed of research papers, review articles, editorials, and research highlights. We recommend contributors to read through the authors' guidelines (https://onlinelibrary.wiley.com/page/journal/27681696/homepage/author-guidelines). This journal adopts an open-access publishing model, and so all published articles are freely accessed through the Wiley Online Library. The editorial team of Battery Energy is composed of world-renowned scientists in the field of energy materials. The Editor-in-Chief is Prof. Yong-Mook Kang from Korea University, Republic of Korea, who has been tackling various important issues for battery technologies. Prof. Anmin Cao (Institute of Chemistry, Chinese Academy of Sciences, Beijing, China), Prof. Raphaële Clément (University of California, Santa Barbara, USA), Prof. Shu-Lei Chou (Wenzhou University, Wenzhou, China), Prof. Sang-Young Lee (Yonsei University, Seoul, Republic of Korea), Prof. Zongcheng Miao (Northwestern Polytechnical University, Xi'an, China) are all invested in the successful launch of the journal and in ensuring the publication of research works of the highest quality in Battery Energy. The editorial board is composed of prominent scientists from academia and industry, to consolidate the ties between fundamental understanding and large-scale implementation of energy devices within this journal. We firmly believe that our diverse insights and viewpoints will provide our authors and reviewers a smooth peer review and publication processes. Yong-Mook Kang (Editor-in-Chief) Korea University, Seoul, Republic of Korea. Anmin Cao (Associate Editor) Institute of Chemistry, Chinese Academy of Sciences, Beijing, China. Raphaële Clément (Associate Editor) University of California Santa Barbara, Santa Barbara, USA. Shu-Lei Chou (Associate Editor) Wenzhou University, Wenzhou, China. Sang-Young Lee (Associate Editor) Yonsei University, Seoul, Republic of Korea. Zongcheng Miao (Associate Editor) Northwestern Polytechnical University, Xi'an, China.

The focus of this talk will be on fabrication of high performance anode electrode for energy storage (Li/Na ion batteries) and conversion (Hydrogen/Oxygen Evolution Reactions) devices using low-temperature carbon/nitrogen plasmas as an alternative novel method which is a cost-, time-and energy-efficient. The electrode materials, in particular the anode materials, are the keystone and bottleneck of the ever-expanding market for energy conversion and storage devices. Currently, the research and development in wet chemistry dominates the synthesis and processing of anode electrode as energy materials. Low-temperature non-thermal plasma-based synthesis and processing strategy are becoming promising tool for the preparation of advanced porous 3-D nanoassemblies that provide electrode materials with excellent capacity, capacity retention, cycling, charge transport, low overpotential, and high-stability. In this proposed talk I will present our work on using low temperature nitrogen and carbon plasma in RF-PECVD system to process, dope and synthesize energy storage and conversion materials. The plasma parameter characterization and detailed physical characterization, and performance evaluation of these plasma processed/synthesized nanostructured electrode materials show superior energy storage and conversion performances will be discussed in the talk.

Interlayer engineering of layered double hydroxides for advanced energy storage and conversion

Electrical energy and chemical energy play an important role in developing the emerging intelligent vehicle and artificial intelligence. Essentially, in well‐designed energy devices, they can be converted with each other and stored based on electrochemical reactions. Since the eventual performance relates closely with the physiochemical properties of the electrode catalysts, it is crucial to tune their microstructure to enhance the reaction kinetics and performance of energy devices. Benefitted from its superb spatial distribution of exsolved nanoparticles and uniquely anchored architecture, exsolution is a robust technique to improve performance for energy conversion and storage. Here, we review the characteristics and mechanisms of exsolution to provide solid knowledge on rationally designing and fabricating of novel exsolution‐derived energy products with excellent properties. Moreover, to trigger inspirations to create new types of energy devices and widen the application window, the recent advances in the exsolution application in energy areas covering fuel cells, electrolysers and batteries, and the fundamental principles of the exsolution effect on tuning their performance are comprehensively reviewed and analyzed. Lastly, the potential directions to further improve the energy devices' performance are discussed.

MXenes have attracted increasing attention due to their unique advantages, excellent electronic conductivity, tunable layer structure, and controllable interfacial chemistry. However, the practical applications of MXenes in energy storage devices are severely limited by the issues of torpid reaction kinetics, limited active sites, and poor material utilization efficiency. Herein, the most‐up‐to date advances in the rational microstructure design to enhance electrochemical reaction kinetics and energy storage performance of MXene‐based materials are comprehensively summarized. This review begins with the preparation and properties of MXenes, classified into fluorine‐containing acid etching and fluoride‐free etching approaches. Afterwards, the interlayer structure design and interfacial functionalization of MXenes with respect to interlayer spacing and porous structure, terminal groups, and surface defects are summarized. Then the focus turns to the construction of advanced MXene‐based heterojunctions based on in situ derivation and surface self‐assembly. Based on these microstructure modulating strategies, the state‐of‐the‐art progress of MXene‐based applications with respect to supercapacitors, alkali metal‐ion batteries, metal–sulfur batteries, and photo/electrocatalysis are highlighted. Finally, the critical challenges and perspectives for the future research of 2D MXene‐based nanostructures are highlighted, aiming to present a comprehensive reference for the design of MXene‐based electrodes for electrochemical energy storage.

Montmorillonite/PVDF-HFP-based energy conversion and storage films with enhanced piezoelectric and dielectric properties