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Showing papers in "Advanced Energy Materials in 2020"



Journal ArticleDOI
TL;DR: In this article, the recent progress and remaining challenges of conversion reactions for Li-ion batteries and SIBs are discussed, covering an overview about the different synthesis methods, morphological characteristics, as well as their electrochemical performance.
Abstract: Lithium-ion batteries (LIBs) with outstanding energy and power density have been extensively investigated in recent years, rendering them the most suitable energy storage technology for application in emerging markets such as electric vehicles and stationary storage. More recently, sodium, one of the most abundant elements on earth, exhibiting similar physicochemical properties as lithium, has been gaining increasing attention for the development of sodium-ion batteries (SIBs) in order to address the concern about Li availability and cost—especially with regard to stationary applications for which size and volume of the battery are of less importance. Compared with traditional intercalation reactions, conversion reaction-based transition metal oxides (TMOs) are prospective anode materials for rechargeable batteries thanks to their low cost and high gravimetric specific capacities. In this review, the recent progress and remaining challenges of conversion reactions for LIBs and SIBs are discussed, covering an overview about the different synthesis methods, morphological characteristics, as well as their electrochemical performance. Potential future research directions and a perspective toward the practical application of TMOs for electrochemical energy storage are also provided.

480 citations





Journal ArticleDOI
TL;DR: In this article, a convolution of two processes between tribology and CE is proposed, and TE is defined as a quantum mechanical electron transfer process that occurs for any materials, in any states (solid, liquid, gas), in any application environment, and in a wide range of temperature up to ≈400 °C.
Abstract: DOI: 10.1002/aenm.202000137 different materials that would be electrically charged after being separated. But TE and CE have significant differences. CE occurs just by physical contact of the two materials without rubbing one against the other, but TE is usually inseparably involving friction by rubbing two materials one on the other. Therefore, TE is a “convolution” of two processes between tribology and CE, so that they are inseparable in conventional understanding. We have recently pointed out that CE is a physical effect in science, while TE is an engineering practice that may involve friction and debris.[3] As for the case of solid–solid, CE is defined as a quantum mechanical electron transfer process that occurs for any materials, in any states (solid, liquid, gas), in any application environment, and in a wide range of temperature up to ≈400 °C. Such an effect is universal and is fundamentally unique in nature.

386 citations














Journal ArticleDOI
TL;DR: In this article, the authors provide an in-depth, critical review of ML-guided design and discovery of energy materials, a field where a novel material with superior performance (e.g., higher energy density, higher energy conversion efficiency, etc.) can have a transformative impact on the urgent global problem of climate change.
Abstract: DOI: 10.1002/aenm.201903242 materials in silico,[19–22] high computational costs and poor scaling still limit their effectiveness in exploring unconstrained chemical spaces and/or complex real-world materials. For instance, highthroughput DFT screening works typically limit the search space to hundreds or, at best, thousands of materials, while DFT simulations of materials are mostly limited to typically less than 1000 atoms, i.e., bulk crystals and isolated molecules. ML therefore offers a solution to the materials exploration problem, making predictions of new materials or properties from existing data, which in turn can drive the generation of more data that can be used to further refine the ML models. Here, we will provide an in-depth, critical review of MLguided design and discovery of energy materials, a field where a novel material with superior performance (e.g., higher energy density, higher energy conversion efficiency, etc.) can have a transformative impact on the urgent global problem of climate change. This review is structured along the steps in a typical workflow for materials ML model building, as shown in Figure 1. The next four sections will provide a concise overview of ML concepts designed to give the reader an appreciation of state-of-the-art techniques as well as resources for building ML models for materials. Section 6 reviews the actual application of ML techniques to the discovery and design of various classes of energy materials, from energy storage (e.g., batteries, fuel cells, etc.) to energy conversion (e.g., thermoelectrics, catalysis, etc.). The final section outlines our perspectives on various challenges and opportunities in ML for energy materials design.

Journal ArticleDOI
TL;DR: In this paper, the performance enhancement of carbon-based supercapacitors by doping other elements (heteroatoms) into the nanostructured carbon electrodes is discussed, where the effects of heteroatom doping by boron, nitrogen, sulfur, phosphorus, fluorine, chlorine, silicon and functionalizing with oxygen on the elemental composition, structure, property, and performance relationships of nanocarbon electrodes are critically examined.
Abstract: Electrochemical capacitors (best known as supercapacitors) are high‐performance energy storage devices featuring higher capacity than conventional capacitors and higher power densities than batteries, and are among the key enabling technologies of the clean energy future. This review focuses on performance enhancement of carbon‐based supercapacitors by doping other elements (heteroatoms) into the nanostructured carbon electrodes. The nanocarbon materials currently exist in all dimensionalities (from 0D quantum dots to 3D bulk materials) and show good stability and other properties in diverse electrode architectures. However, relatively low energy density and high manufacturing cost impede widespread commercial applications of nanocarbon‐based supercapacitors. Heteroatom doping into the carbon matrix is one of the most promising and versatile ways to enhance the device performance, yet the mechanisms of the doping effects still remain poorly understood. Here the effects of heteroatom doping by boron, nitrogen, sulfur, phosphorus, fluorine, chlorine, silicon, and functionalizing with oxygen on the elemental composition, structure, property, and performance relationships of nanocarbon electrodes are critically examined. The limitations of doping approaches are further discussed and guidelines for reporting the performance of heteroatom doped nanocarbon electrode‐based electrochemical capacitors are proposed. The current challenges and promising future directions for clean energy applications are discussed as well.

Journal ArticleDOI
TL;DR: In this article, a review focusing on the trends and impacts of research based on piezo-enhanced photocatalytic reactions is presented, and the fundamental mechanisms of piezo phototronics modulated band bending and charge migration are highlighted.
Abstract: The storage/utilization of solar energy is a promising strategy to alleviate current disparities in energy shortage Direct conversion of solar light into chemical energy by means of photocatalysis or photoelectrocatalysis is currently a point of focus for sustainable energy development and environmental remediation. However, its current efficiency is still far from satisfying, suffering especially from severe charge recombination. To solve this problem, the piezo-phototronic effect has emerged as one of the most effective strategies for photo(electro)catalysis. Through the integration of piezoelectricity, photoexcitation, and semiconductor properties, the built-in electric field by mechanical stimulation induced polarization can serve as a flexible autovalve to modulate the charge-transfer pathway and facilitate carrier separation both in the bulk phase and at the surfaces of semiconductors. This review focuses on illustrating the trends and impacts of research based on piezo-enhanced photocatalytic reactions. The fundamental mechanisms of piezo-phototronics modulated band bending and charge migration are highlighted. Through comparing and classifying different categories of piezo-photocatalysts (like the typical ZnO, MoS2, and BaTiO3), the recent advances in polarization-promoted photo(electro)catalytic processes involving water splitting and pollutant degradation are overviewed. Meanwhile the optimization methods to promote their catalytic activities are described. Finally, the outlook for future development of polarization-enhanced strategies is presented.






Journal ArticleDOI
TL;DR: In this paper, the authors present a historical and up-to-date account of the energy-related applications of magnetocaloric materials and information about their processing and magnetic fields, thermodynamics, heat transfer, and other relevant characteristics.
Abstract: The need for energy-efficient and environmentally friendly refrigeration, heat pumping, air conditioning, and thermal energy harvesting systems is currently more urgent than ever. Magnetocaloric energy conversion is among the best available alternatives for achieving these technological goals and has been the subject of substantial basic and applied research over the last two decades. The subject is strongly interdisciplinary, requiring proper understanding and efficient integration of knowledge in different specialized fields. This review article presents a historical and up-to-date account of the energy-related applications of magnetocaloric materials and information about their processing and magnetic fields, thermodynamics, heat transfer, and other relevant characteristics. The article also discusses the conceptual design of magnetocaloric refrigeration and power generation systems and some guidelines for future research in the field.