Materials and Sustainable Development: Materials for Clean Energy Utilization

Effects of Temperature and CO₂ on Pore Structure and Surface Fractal Dimension of Pyrolytic Carbonized Biochar Briquettes Article

LIU Zewei, YAN Sijia, XIA Zihao, TIAN Lin, LIU Yukang, WANG Jingcheng, HU Jianhang

Materials Reports 2018,32(17 ):2925 -2931. DOI:10.11896/j.issn.1005-023X.2018.17.005

Abstract （1031）

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Preparation and Electrochemical Performance of SiO_x/C/CNTs Composite Anode for Lithium Ion Batteries Article

LI Wenchao, TANG Renheng, WANG Ying, WANG Huakun, XIAO Fangming, HUANG Ling

Materials Reports 2018,32(17 ):2920 -2924. DOI:10.11896/j.issn.1005-023X.2018.17.004

Abstract （803）

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Flexibility and Microminiaturization of Electrode Materials and Devices for Supercapacitor Article

DONG Wenju, KONG Lingbin, KANG Long, RAN Fen

Materials Reports 2018,32(17 ):2912 -2919. DOI:10.11896/j.issn.1005-023X.2018.17.003

Abstract （960）

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Synthesis of Three-dimensional Polyacrylamide/Poly(vinyl alcohol) Hydrogel and Its Application in Supercapacitor Article

WANG Dexuan, WANG Lei, YU Liangmin

Materials Reports 2018,32(17 ):2907 -2911. DOI:10.11896/j.issn.1005-023X.2018.17.002

Abstract （1099）

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A Review on the Development of the Structural Materials of the Fusion Blanket Article

XU Yuping, LYU Yiming, ZHOU Haishan, LUO Guangnan

Materials Reports 2018,32(17 ):2897 -2906. DOI:10.11896/j.issn.1005-023X.2018.17.001

Abstract （1929）

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Save With the advance of ITER and CFETR, issues concerning materials become a serious problem which limits the development of fusion energy. Blanket is an important components for energy transform, tritium sustain and radiation shielding. The development of structural materials which fit the requirement of the harsh service environment has become a research focus worldwide.
   Various blanket structural materials such as reduced activation ferritic/martensitic steels (RAFMs) have been developed for decades. Based on the Roadmap of Fusion Energy of China, the neutron irradiation dose in the structural materials can reach 10 dpa in Phase 1, and 50 dpa in Phase 2. Until now, there are no materials that can satisfy both the harsh working environment requirement and engineering building requirement.
   RAFM steels are the main candidate for the blanket structural materials. Several specification of RAFM steels have been deve-loped worldwide, and the database has been established. However, limited by the narrow working temperature range and the low creep strength at high temperature, RAFM steels cannot reach the requirement of the CFETR Phase 2 and future fusion reactor. Two method have been proposed, one is adding oxide dispersion phase into the steel to promote the high creep performance, the steels obtained by this method is called oxide dispersion strengthened steels (ODSs). This method can be further classified into two kinds depending on if the mechanical alloyed (MA) is needed in the manufacture process. The other method is based on computational thermodynamics modelling. The density of MX phase can be increased by modifying chemical composition and thermomechanical treatments. The ODSs obtained by MA have the best performance at high temperature and under irradiation, but it should be noted that the MA process is of high cost and low efficiency. The none-MA ODSs and modified RAFM steels have the properties close to those of the MA ODSs, and they are much cheaper than the MA ODSs with potential for large-scale manufacture. Except for structural materials based on iron, vanadium alloys and SiC composite materials are all candidates for blanket structural materials with some good properties over the steels. For vanadium alloys, their working upper temperature is low and they are not compatible with hydrogen isotopes, which limits the application of vanadium in fusion reactor. For SiC composite materials, the joint technology and large-scale manufacture remain as problems. For future fusion reactor, the irradiation dose of the structural materials is larger, thus the current candidate materials may not fully satisfy the requirement. In the future, two aspects should be attached great attention to, one is exploring the performance potential of existing materials with the help of new ideas and new methods of material design and preparation, the other one is development of new materials like the metallic glass composites and high-entropy alloys.
   According to the Roadmap of Fusion Reactor Materials of China, we review the development of the structural materials of the fusion blanket in this article. The development of RAFM steel, mechanical alloyed (MA)oxide dispersion strengthened steels (ODSs), vanadium alloys and SiCf/SiC has been introduced. In recent years, new types of structural materials emerge, such as mo-dified RAFMs and none-MA ODSs, which have also been described in this article. Finally, the authors look ahead the development of advanced structural materials with better performance.

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Permeability of Hydrogen and Deuterium in Niobium Film Article

ZHOU Yanyan, ZHOU Xin, CHEN Chang’an, WANG Wei, WANG Zhanlei, RAO Yongchu, LIANG Chuanhui, ZHOU Yuanlin

Materials Reports 2018,32(15 ):2596 -2600. DOI:10.11896/j.issn.1005-023X.2018.15.009

Abstract （771）

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Research Progress of Bipolar Plate Material for Proton Exchange Membrane Fuel Cells Article

LI Junchao, WANG Qing, JIANG Rui, WU Aimin, LIN Guoqiang, DONG Chuang

Materials Reports 2018,32(15 ):2584 -2595. DOI:10.11896/j.issn.1005-023X.2018.15.008

Abstract （1198）

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Save Fuel cells, a kind of efficient and environmentally friendly power generation system which can continuously convert chemical energy into electricity directly, are the fourth power generation devices since hydropower, thermal power and nuclear power. Among them, proton exchange membrane fuel cells show prominent advantages of long life, high specific power and specific energy, fast start-up at room temperature, etc. They have displayed promising application potential in both portable power and immobile power with military, transportation and telecommunication uses, and are considered as one of the ideal power sources with high adaptability to future energy and environment situation.
The bipolar plate, which is one of the core components of a proton exchange membrane fuel cell, occupies a large part of the quality and cost of the whole battery pack and has the functions of uniformly distributing the reactant gas, conducting current, and concatenating monocells, etc. In order to realize these functions, a qualified bipolar plate should have the characteristics of high thermal conductivity, high electrical conductivity, corrosion resistance, low density, favorable mechanical properties, low cost, easy processing and so on. However, the contemporary bipolar plate products suffer poor matching between corrosion resistance and poor conductivity, also high production cost and short service life. Accordingly, it is crucial for commercial applications of fuel cells to achieve a reasonable matching of the conductivity and corrosion resistance of the bipolar plate materials, in other words, to ensure high corrosion and service life of the entire system resistance in the case of reasonable conductivity.
Currently, the commonly used substrate materials of proton exchange membrane fuel cell bipolar plates include graphite mate-rials, metal materials and composites, all of which have different advantages and disadvantages but are nonetheless unsatisfactory. This in recent years has urged intensive and fruitful research efforts to improve bipolar plates’ performance by means of material doping or surface modification, and a majority of modified materials have shown acceptable performance according to the criteria of the United States Department of Energy.
This paper systematically summarizes the above three types of bipolar plate materials, with an emphasis on the performances of the combinations of a diverse variety coating materials and substrates (including stainless steel, aluminum alloy, titanium alloy substrates). Finally, the development trend of bipolar plate materials, especially metallic bipolar plates are further discussed.

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A State-of-Art Review on Preparation Methodology of Nano-copper and Propertiesof Copper Nanofluids Used in Solar Radiation Absorbing Materials Article

ZHOU Lu, MA Honghe, MA Suxia, DU Huijuan

Materials Reports 2018,32(15 ):2576 -2583. DOI:10.11896/j.issn.1005-023X.2018.15.007

Abstract （771）

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Impact of Annealing on Germanium Thin Film Prepared by Aluminum-inducedCrystallization and the Corresponding Mechanism Article

HE Kai, CHEN Nuofu, WEI Lishuai, WANG Congjie, CHEN Jikun

Materials Reports 2018,32(15 ):2571 -2575. DOI:10.11896/j.issn.1005-023X.2018.15.006

Abstract （727）

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Effect of Annealing Treatment on the Phase Structure and ElectrochemicalPropertiesof La_0.63(Pr_0.1Nd_0.1Y_0.6Sm_0.1Gd_0.1)_0.2Mg_0.17Ni_3.1Co_0.3Al_0.1 A₂B₇-type Hydrogen Storage Alloys Article

DENG Anqiang, LUO Yongchun, WANG Hao, ZHAO Lei, LUO Yuankui

Materials Reports 2018,32(15 ):2565 -2570. DOI:10.11896/j.issn.1005-023X.2018.15.005

Abstract （549）

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Research Progress on Manganese Dioxide Based Supercapacitors Article

HUANG Wenxin, LI Jun, XU Yunhe

Materials Reports 2018,32(15 ):2555 -2564. DOI:10.11896/j.issn.1005-023X.2018.15.004

Abstract （1448）

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Save Nowadays, the energy issue has increasingly become a hot spot of social attention, and the supercapacitor as a new type of energy storage device attracts much attention due to its long service life, high power and environmental friendliness. MnO₂ based supercapacitors not only assume the characteristics of high power density, long cycle life, fast charge and discharge, but also have the advantages of low cost, broad source and environmental friendliness. Thus they have displayed a very broad application prospects and economic value in various fields. However, the specific capacitance of the MnO₂ based supercapacitor is considerably lower than the theoretical value due to its poor conductivity and limited specific surface area. Moreover, its unstable structure also results in poor cycling stability. To resolve the above mentioned problems, the current researches about the MnO₂ based supercapacitor mainly focus on finding facile and controllable preparation methods to improve the electrochemical properties like conductivity, specific capacitance, cycling stability, etc., and trying to magnify the advantages and realize synergistic effect of various electrode materials.
Searching a simple and controllable electrode preparation method has become a primary task for high quality MnO₂ based supercapacitors. The common methods include sol-gel method, hydrothermal synthesis method, chemical precipitation method, low temperature solid phase method and electrochemical deposition method. The resultant powders prepared by sol-gel method have high purity, agglomerate easily due to the drying conditions. Through the chemical precipitation method can obtain uniformly distributed powders with even chemical compositions, and still, ease of agglomerat owing to high synthesis temperature. The low temperature solid phase method can efficiently overcome the shortcomings mentioned above involving the rapid growth and agglomeration of particles at high temperature, but nevertheless suffers low reaction conversion rate which is attributed to the inadequate contact among the reactants. The hydrothermal synthesis is a simple and low cost method which has been applied to prepare the powder widely at pre-sent. The powders prepared by the above methods need certain pre-treatment for the fabrication of electrode, which extends the process and is detrimental to energy saving and environmental protection. On the contrary, the electrodeposition method can directly deposit manganese dioxide on different substrates with flexible operation and controllable operating parameters. The modification of manganese dioxide electrode material has converged intensive research endeavors, the doping and composing methods are still used commonly at present, for example, a small amount of metal elements doped in manganese dioxide can improve the conductivity of the electrode, and some conductive polymers added into manganese dioxide can effectively solve the unstable structure of manganese dioxide which results in its easy dissolution in the electrolyte. In order to obtain the high-quality electrode, it is very essential to select the species of the doped materials and composited materials, their proportions, and the doping and composing methods. Now, the MnO₂ based supercapacitor is not barely composed of MnO₂, but a combination of MnO₂and other substances, such as a variety of carbon materials, composite materials or metal oxides. The combination of multiple composite materials can adequately make use of the characteristics of each component, which contributes to optimizing the performance of the capacitor. In addition, some scholars also found that the selection of electrolyte has great influence on expanding the electrochemical window of supercapacitors, improving the energy density and power density of capacitors.
This paper briefly introduces the energy storage mechanism and summarizes the research status of capacitor electrolyte, electrode preparation and modification method. The fabrication and performance characteristics of MnO₂based supercapacitors device are introduced, and the future research trends are also presented.

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The Evolvement of Hole-transporting Materials in Highly Efficient Perovskite Solar Cells Article

ZOU Jinlong, LUO Yufeng, XIAO Zonghu, HU Yu, RAO Senlin, LIU Shaohuan

Materials Reports 2018,32(15 ):2542 -2554. DOI:10.11896/j.issn.1005-023X.2018.15.003

Abstract （997）

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Phenothiazine and Phenoxazine Sensitizer Donor Units: a Comparative Analysis with an Application to Dye-sensitized Solar Cells Article

TAN Haijun, HE Jingwen, PEI Hairui, LI Heping, ZHANG Shufen, ZHANG Shuhua

Materials Reports 2018,32(15 ):2538 -2541. DOI:10.11896/j.issn.1005-023X.2018.15.002

Abstract （837）

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Energy Storage and Application for 2D Nano-material MXenes Article

ZHENG Wei, YANG Li, ZHANG Peigen, CHEN Jian, TIAN Wubian, ZHANG Yamei, SUN Zhengming

Materials Reports 2018,32(15 ):2513 -2537. DOI:10.11896/j.issn.1005-023X.2018.15.001

Abstract （1812）

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Save Energy storage and conversion devices are one of the indispensable bases for the modern society. The demands for high performance energy storage and conversion devices are becoming more and more urgent with the rapid development of portable electronic devices and electric vehicles. The performance of energy storage and conversion devices strongly depends on the development and utilization of energy storage materials. Generally, the requirements for energy storage materials are as follows: being capable of reversible redox reactions; having excellent ionic accessibility; providing plenty of redox active sites; having high electronic conductivity.
Recently, two dimensional materials have shown great advantages in energy storage area for their large surface area and short ion transmission path. Two dimensional materials, possessing only atomic layer thickness and large number of surface active sites, good mechanical properties, exactly fit the role of energy storage and conversion devices. MXenes are a new type of two-dimensional materials, generally represented as M_n+1X_nT_x, where M is the transition metal elements, X is carbon and/or nitrogen, T represents functional groups (-F,-OH,-O, etc.) produced in the MXenes preparation process, and n is usually 1—4. Since being discovered in 2011, they have been highly expected for energy-related technology applications. MXenes exhibit good conductivity, fast charge response, pseudocapacitance and stable cycle life. The carbon layers in MXenes lead to good conductivity; the transition metal (M) layers render MXenes similar properties of transition metal oxides; whereas the functional groups enable MXenes hydrophilic surface. Such unique structure and properties perfectly match the requirements for energy storage materials and thus drive the research on MXenes a hot topic. In addition, portable energy storage and conversion devices demand high volumetric capacity and volumetric energy density. Compared with carbon-based electrode materials, MXenes have high accumulation density, which can effectively reduce the volume of energy storage devices and thus widen its application spectrum.
MXenes and their composites have already shown practical application in supercapacitors, lithium/sodium/magnesium ion se-condary batteries, lithium-sulphur batteries, zinc-air batteries, hydrogen storage and other energy storages. However, pristine MXenes are prone to collapse and restack during preparation and service, compromising their performance as electrode material. Much work, such as intercalating, modification, doping, compositing with other materials, has been done to reduce the ion diffusion resistance and increase the ion adsorption sites, resulting in the prevention of MXene restacking and electrochemical properties improvement. Moreover, different energy storage and conversion devices have different requirements for the synthesis processes and structural features of MXenes. Given that the research papers on MXene-related energy materials exponentially expand, it is necessary to comprehensively summarize and analyze it in order to promote their development in the field of energy storage and conversion.
This article reviews the latest progress on the synthesis, structure, properties and energy storage applications of MXenes and also discusses the research directions and challenges for MXenes for the years to come.

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A State-of-the-art Review of Chemical Component Study of theCandidate Steel for 650 ℃ Ultra-supercritical Boiler Tube Article

WEN Xinli, ZHANG Qingquan, CHEN Lie

Materials Reports 2018,32(13 ):2167 -2175. DOI:10.11896/j.issn.1005-023X.2018.13.005

Abstract （787）

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Save According to the latest statistics, by the end of 2016, 71.60% of total power generation capacity in China was produced by thermal power, 64.04% of the total installed capacity in China was contributed by thermal power. Water power in China accounted less than 20% of total power production; nuclear power, wind power and solar power accounted less than 10%. Apparently, thermal power is the backbone of electrical energy in China. Nevertheless, owing to the increasing appeal for environment protection, the traditional power generation technology with low efficiency, high emission and high pollution can’t meet the healthy and sustainable development of power generation industry. While as a new technology with high efficiency, low emission and low pollution, ultra-supercritical power generation technology has aroused great attention and been widely studied. In engineering thermodynamics, the critical parameters of water is 22.115 MPa and 374.15 ℃. Above this parameter, water presents single-phase fluid which is called super critical state. Super critical generator is thermal power generator which serves under the condition of above 22.115 MPa and 374.15 ℃. There is no specific parameter in physics for ultra-supercri-tical state, and there is also no unified definition for ultra-supercritical generator. It is universally recognized the generator can be called ultra-super critical generator when it served under the steam pressure of above 27 MPa or the steam temperature of above 580 ℃. 650 ℃ ultra-supercri-tical technology is an advanced coal-fired power generation technology which has been competitively studied worldwide. The working condition are steam temperature of 650 ℃ and pressure of 35 MPa. The core technology of 650 ℃ ultra-supercritical power generator is the steel used for main steam boiler tube, which is required to suffer the 650 ℃, 35 MPa steam. The researches of this kind of steel mainly focus on the chemical component design. Up to now, Japan and China has developed their own chemical component system and produced their original steel independently. The steel deve-loped by National Institute for Materials Science of Japan is named MARBN(9Cr-3W-3CoVNbBN), the steel developed by Nippon Steel & Sumitomo Metal Corporation is named SAVE12AD(9Cr-3W-3CoNdVNbBN), and the steel developed by Iron and Steel Research Institute is named G115(9Cr-2.8W-3CoCuVNbBN). However, the processing property and working perfor-mance of the three kinds of steels are still under experimental evaluation, and the matched welding material and welding technique are in development as well. Currently, there are several candidate steels with different chemical components for 650 ℃ ultra-supercritical boiler tube. Different developers have different understandings of the effects caused by various elements, and there is no consensus yet on the best chemical components. The research progress in chemical components of the candidate steel used for 650 ℃ ultra-supercritical boiler tube is summarized in this article. The action mechanisms of chemical elements such as B, N, C, W, Ta, Nd, Co are analyzed, and the effects of the elements on the matrix structure, carbides, creep property and so forth are elaborated. In view of welding property, it is pointed out that the chemical component of the welding materials should be matched with the tube steel, the welding property degeneration should be avoided. The problems which should be paid attention to during welding materials development are clarified.

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SiC_f/SiC Composites and Molybdenum Alloys: the Promising Candidate Materialsfor Typical Accident Tolerant Fuel Cladding of Light Water Reactors Article

CHENG Liang, ZHANG Pengcheng

Materials Reports 2018,32(13 ):2161 -2166. DOI:10.11896/j.issn.1005-023X.2018.13.004

Abstract （849）

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A Brief Survey on the Stability Study of Organometal Halide Perovskite Solar Cells Article

CHEN Jian, MIU Weifeng, WANG Jilin, ZHENG Guoyuan, LONG Fei

Materials Reports 2018,32(13 ):2151 -2160. DOI:10.11896/j.issn.1005-023X.2018.13.003

Abstract （870）

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Save The organicmetal halide perovskite solar cells has been developing rapidly in recent years, and the cells’ certified photoelectric conversion efficiency has reached 22.1%. Simultaneously, low cost, short energy payback time and other merits have made the commercial application of organicmetal halide perovskite solar cells into reality. Nevertheless, the perovskite itself is not stable in the circumstances of high humidity, high temperature or light. Especially, the instability of perovskite will be more serious when assembled with other functional layers into the device, because electrode corrosion or deep defects will be easily initiated in this situation. More and more literature has reported various methods to improve the stability of the device, which mainly focuses on two aspects: Ⅰ. controlling the composition of the perovskite material to enhance the stability; Ⅱ. optimizing the device structure of the solar cells to enhance the stability. As for the component optimization, researchers put efforts in modifying ABX₃ structure, controlling structural dimension and the use of protective layer to improve the stability of perovskite materials themselves. Ⅰ. With the satisfaction of the requirements of Goldschmidt tolerance factor t or octahedral factor μ, the introduction of hydrophobic or temperature-resistant groups like formamidinium or cesium cation into the A site of ABX₃, while incorporation of bromide anion or thiocyanate ion into X site will increase the moisture resistance of perovskite material. What’s more, a combination sites of perovskite Cs_x(MA_0.17FA_0.83)_(100-x)Pb(I_0.83Br_0.17)₃ could not only improve the thermal stability but also enhance the device’s conversion efficiency to 21.1%. Ⅱ. Low-dimensional (mainly two-dimensional) perovskite materials have also been comprehensively studied. For instance, BA_0.05(FA_0.83Cs_0.17)_0.95Pb(I_0.8-Br_0.2)₃displays excellent stability in high humidity and light circumstances. Ⅲ. Protective layers with favorable hydrophobic properties, excellent charge transport ability such as butylphosphonic acid 4-ammonium chloride or benzylamine can also enhance the stabi-lity of the perovskite material. As for the device structure optimization, researchers have tried to strengthen the stability of the device through changing electron transporting material (SnO₂, La-doped BaSnO₃, etc.), hole transporting material (CuGaO₂, CuPC etc.) and counter electrode (carbon, copper etc.), respectively. For example, La-doped BaSO₃ has weak UV photocatalytic activity, excellent electron mobility and suitable energy band structure, the device with La-doped BaSO₃ as electron transporting material show unexceptionable light stability. In addition, taking chemical and thermal stable CuPC as the hole transporting material of the device could not only achieve favorable thermal stability but also obtain a conversion efficiency of 17.5%. Considering the counter electrode, carbon electrode shows excellent stability under high humidity and light conditions when it applies to large area devices. Moreover, when copper electrode replace gold or silver electrode, the device acquired a conversion efficiency of more than 20%, and presented an admirable heat and light stability as well. This review mainly summarizes the current status of the stability study of organometallic halide perovskite solar cells in view of the perovskite absorbing material compositions and device structure. Researches about optimizing the stability of the device from the perovskite composition of ABX₃, structural dimension of perovskite material and the use of other functional layers are summarized. Finally, the development trends of organometallic halide perovskite solar cells are proposed based on the available research.

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A Review on Cathode Interfacial Layers of Organic Solar Cells Article

ZHOU Dan, QIN Yuancheng, XU Haitao, LI Mingjun

Materials Reports 2018,32(13 ):2143 -2150. DOI:10.11896/j.issn.1005-023X.2018.13.002

Abstract （1033）

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Metal-Organic Framework-derived Materials and Their Applications in EnergyStorage Devices and Electrocatalysis Article

YE Shaofeng, LIU Wenxian, XU Xilian, SHA Dongyong, SHI Wenhui, CAO Xiehong

Materials Reports 2018,32(13 ):2129 -2142. DOI:10.11896/j.issn.1005-023X.2018.13.001

Abstract （2157）

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Save Metal-organic frameworks (MOFs), a kind of porous materials constructed from metal ion/cluster and organic li-gands, have been a major focus of materials science over the past decades. MOFs possess high specific surface area and uniform cavities, as well as structural tunability, which are promising for a variety of applications. However, the poor conductivity and low stability of MOFs restrict their further development of applications. In recent years, MOF-derived materials, obtained by hydrothermal and/or calcining process, which possess relatively higher conductivity and better stability while maintaining the structural advantages of MOFs, have become a research hotspot. However, the single composition and structure of MOF-derived materials, which can provide limited performance (such as capacitive properties, catalytic properties), greatly limit the development of its related applications. Therefore, in addition to research and preparation of a variety of different MOF-derived materials in recent years, researchers mainly foucs on the composition and structure of MOF-derived materials to prepare a variety of materials with excellent performance in various applications (such as energy storage and conversion, catalysis). As applied materials with excellent performance, composition and structure of MOF-derived materials have been studied maturely, mainly include porous carbon, metal oxides, metal phosphides, metal hydroxides, and fibrous structures, hollow structures, core-shell structures, etc. MOF-derived materials with large specific surface area, uniformly distributed cavities, always combine the porous carbon with high conductivity and other derived materials (metal compounds or doped metal atoms and heteroatoms such as N, P, S, etc.) with excellent performance (such as capacitance, catalytic properties), to play a rather excellent performance. Among them, MOF-derived metal compounds have porous structure, which can provide excellent capacity and catalytic properties, and the properties are usually superior to the same materials prepared by other methods. In terms of structure, in recent years, the resear-chers have prepared a variety of MOF-derived materials with different structures by controlling the precursor structure or the reaction conditions. On the one hand, partially prepared structures (such as the core shell structure and the hollow structure) of MOF-derived materials can alleviate the impact in the process of use, thus it can show excellent cycling performance. On the other hand, by regulating the structure of MOF-derived materials, the active sites are fully exposed, so that their performance can be maximized. In this review,we summarizes the recent progress of MOF-derived materials, including its composition, structural regulation, as well as their applications in energy storage, catalysis and other fields. Finally, the future direction and challenge of MOF-derived materials are discussed.

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A Review of Numerical Simulation for Impurity Control in the Directional Solidification Process of Multicrystalline Silicon Article

SU Wenjia, NIU Wenqing, QI Xiaofang, LI Chen, WANG Junfeng

Materials Reports 2018,32(11 ):1795 -1805. DOI:10.11896/j.issn.1005-023X.2018.11.005

Abstract （621）

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Save The continuous consumption of traditional energy sources is exaggerating the prominence of renewable energy production and utilization, and solar photovoltaic power generation has gradually been regarded as one of the most promising renewable energy techniques. Multicrystalline silicon, owing to high efficiency and low cost, has now become the most important photovoltaic material, and quality and cost of its ingot will directly affect the cost of solar cells and the efficiency of photoelectric conversion. Directional solidification (DS) method is an important way to obtain multicrystalline silicon ingot, but suffers many problems in the growth of crystalline silicon, including melt flow, impurities transfer, shape and structure of solid-liquid(S-L) interface, and defects. Harmful impurities introduced during the directional solidification process will seriously affect the ingot’s mechanical and electrical properties, and thus are the key factor limiting the photoelectric conversion efficiency of multicrystalline silicon.
    The heat and mass transfer in the DS furnace under high temperatures during the crystal growth process is extremely complica-ted and shows no single linear relationship, no inferentiality, and difficulty for experimental measurements. So the numerical simulation is considered as an important way to study the heat and mass transfer in the DS process. There have been two useful aspects for the reduction of impurities: I. the source of impurities — impurities in the raw materials and impurities generated during the crystal growth process; II. transport of impurities — finding the transport rule of impurities in melts and argon, and using this rule to control the segregation and transport of impurities.
    In recent years, from the perspective of controlling the impurity generation and transport, most of the research works which intend to reduce the harmful impurities in multicrystalline silicon involve the following methods: I. controlling the source of impurities, including inhibiting the chemical reaction between crucible and baffle, optimizing top crucible cover plate, and introducing silicon carbide coating, etc.; II. improving argon flow by adopting argon guidance system, regulating furnace pressure and argon flow rate; III. optimizing melt convection, including controlling melt flow and segregation, adjusting the power and arrangement of heaters, adopting rotatable crucible, adjusting the position of graphite carbon felt and so on.
    The intention to cut the cost of DS multicrystalline silicon ingot gives rise to increasingly bigger crucible and larger feeding amount, which make the melt convection, impurity transport and interface shape more difficult to control. The external magnetic field has been proved to be powerful in controlling melt convection and further controlling impurity transport, and the relevant research is still in its infancy. As the electromagnetic field (EMF) and traveling magnetic field (TMF) display great potential in controlling the stirring melt convection, they have gradually found application in the crystal growth process.
    On the basis of an analysis over impurity sources and transport mechanism, this review provides a comprehensive description of the generation, distribution, transport and removal of harmful impurities in the directional solidification process, as well as a summary of the effects of argon guidance system, heaters and magnetic field on impurities with respect to numerical simulation optimization.

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Synthesis of Hollow Si Nanospheres and Its Electrochemical Performances as Anode Material for Lithium-ion Batteries Article

DING Ang, ZHANG Zhongyuan, CHENG Ting, DONG Xinglong

Materials Reports 2018,32(11 ):1791 -1794. DOI:10.11896/j.issn.1005-023X.2018.11.004

Abstract （669）

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Influences of the Selenization Temperature on the Microstructures and Chemical Compositions of CIGS/Mo Interface Article

YUAN Qi, CHA Limei, MING Wenquan, YANG Xiubo, LI Shiyong, HAN Junfeng

Materials Reports 2018,32(11 ):1787 -1790. DOI:10.11896/j.issn.1005-023X.2018.11.003

Abstract （740）

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Dendrite Growth of Lithium Metal Anode for Rechargeable Batteries: Theoretical Basis, Influencing Factors and Inhibition Methods Article

LIANG Jiege, LUO Zheng, YAN Yu, YUAN Bin

Materials Reports 2018,32(11 ):1779 -1786. DOI:10.11896/j.issn.1005-023X.2018.11.002

Abstract （1387）

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Save The worldwide increasingly tough circumstance of energy and environment urges the continuous and intensive inte-rest both in industry and in science upon the utilization of renewable energy sources and the development of efficient and safe energy storage techniques. Lithium-ion secondary batteries are a kind of high-specific-capacity and long-cycle-life energy storage devices which over the past decade have acquired considerable and fruitful research attentions and found wide applications in a rich variety of portable electronic devices and electric vehicles. On the other hand, the fast emergence of high-performance electronics has exaggera-ted the requirements of energy density, cycle stability and safety to a remotely high level for the commercialized lithium ion batteries.
    For the sake of increasing Li-ion batteries’ energy density, anode materials with high capacity, e.g. silicon, tin, lithium, have been developed to substitute for the conventional graphite anode. Either silicon or tin anode stores and releases Li ions by reacting with them and forming lithium-containing compounds within a charge-discharge process, which generally accompanies huge volume change of the anode. This will cause these anode materials to be pulverized or even stripped from the current collector after expe-rienced relatively long time usage, and in consequence, the rapid fading of battery capacity and even failure. By contrast, Li metal anode’s charge-discharge process is based on dissolution/deposition of lithium on the current collector, and this process involves no reaction-phase-transition-induced volume change. Furthermore, lithium metal is regarded as an ideal candidate material for rechar-geable batteries due to its high theoretical specific capacity (3 860 mAh/g), low density (0.59 g/cm³) and the lowest electrochemical potential (-3.04 V vs RHE) within all anodes. Unfortunately, some key issues, such as Li dendrite growth, low columbic efficiency and uncontrolled-deposition-induced volume expansion, have restrained the commercialization of Li metal anodes.
    Each time of lithium deposition will cause the growth of dendrites, and thus the Li dendrites will lead to internal short circuits and even battery explosion, which is considered as a serious safety problem. In addition, lithium dendrites will also increase the anode surface area, enabling the reaction between newly exposed lithium and electrolyte to form solid electrolyte interphase (SEI) that causes low columbic efficiency. In order to solve these problems, researchers have done a lot of studies on the lithium metal anodes, especially on the mechanism and inhibition methodology of dendrite growth. There have been proposed several theoretical models which describe the formation and growth behavior of Li dendrites, including diffusion model, SEI protection model, charge-induced growth model and film growth model, and furthermore, the corresponding inhibition solutions, such as uniform lithium ion flux method, SEI protection method, host-assisted stable deposition and electrostatic shielding method. By adopting these methods, the growth of lithium dendrites can be alleviated to a certain extent, but still the Li metal anodes are unsatisfactory for commercialization.
    Herein, we summarize the global research works of lithium metal anode in recent years, introduce systematically several gene-rally recognized Li dendritic growth models and the corresponding influencing factors, and emphatically clarify the inhibition methods of dendrite growth and their effectiveness. Finally, we also put forward some suggestions for the future research direction of lithium metal anodes.

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A Complete Review and a Prospect on the Candidate Materials for Accident-tolerant Fuel Claddings Article

LIU Junkai, ZHANG Xinhu, YUN Di

Materials Reports 2018,32(11 ):1757 -1778. DOI:10.11896/j.issn.1005-023X.2018.11.001

Abstract （1735）

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Save In the 2011 Fukushima nuclear power plant accident, the zirconium alloy claddings in the reactor fuel were oxidized violently by high temperature water vapor generated under accident conditions, resulting in a large amount of hydrogen and heat, which eventually led to reactor core melt down and hydrogen explosion. The event delivered severe impacts on the human society and the environment. From then on, the development programs of accident-tolerant fuels (ATF) have been initiated worldwide. Compared with the traditional UO₂-Zr system, ATF can sustain or improve the fuel performance at normal operating conditions, as well as maintain the core integrity for an extended time after accidents to provide temporal safety margins for the accident management.
  The environment of the reactor core is very harsh, as the claddings are exposed lastingly to high temperature and high pressure corrosion medium, and moreover, neutron irradiation. As a result, if any new materials were to qualify as cladding materials, they would need excellent radiation stability and corrosion resistance. According to the research and evaluation of different researchers, the accident-tolerant fuel cladding materials which has displayed the potential of substituting for Zr alloy can be classified into ceramic materials and metallic materials, in which the ceramic materials are mainly represented by SiC/SiC composite materials, and the metallic materials mainly include Fe-based alloy exemplified by FeCrAl and refractory metals exemplified by Mo/Mo alloy.
  Each of the three materials has its own advantages and disadvantages, and still needs improvements to attain the requirement of engineering application, and all of them have some unresolved key issues. The research and development of the FeCrAl alloy has reached the second generation model alloy. The thermophysical and mechanical properties, corrosion resistance and radiation resis-tance of FeCrAl alloy are outstanding, while the research on hydrogen permeability and industrial processing and welding are still in progress. In the case of SiC/SiC composites, the high brittleness of SiC material leads to inadequate mechanical strength. Hence researchers have proposed various structural design schemes to reduce the failure probability of cladding tubes, but the final structural design of the cladding remains undetermined. The sharp reduction of thermal conductivity of SiC/SiC composites caused by irradiation and the joining and fabrication are still under investigation. Mo and Mo alloys possesses excellent mechanical properties and radiation resistance, but exhibits poor corrosion resistance. The present countermeasures are mainly focused on improving the purity of molybdenum, adjusting the elemental composition of the alloys and adopting surface coating techniques. The processability of these three kinds of cladding tube materials has not reached the level of industrial manufacturing of thin-wall long tubes. For these candidate materials, a property database and an integrated series of standards are of great necessity to evaluate the quality of the materials. In addition, the requirement of in-core behavior assessment also necessitates the development of the corresponding fuel performance code.
  This paper summarizes the latest research progress on the candidate ATF cladding materials, including their physical properties, corrosion resistance, mechanical behaviors, radiation resistance, pellet-cladding mechanical and chemical interactions, behaviors under accident conditions and engineering applications. It also gives critical discussions about the current research situation and the potential key issues of each candidate material.

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Core-Shell Structured Catalysts with Platinum Skin for Fuel Cells: the State-of-the-art Methodological Advances in Fabrication and Nanostructure Control Article

SUN Peichuan, WEI Qingmao, ZHANG Yuzhen, YANG Xikun, WANG Jianhua

Materials Reports 2018,32(9 ):1427 -1434. DOI:10.11896/j.issn.1005-023X.2018.09.006

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Synthesis and Photovoltaic Performance of the Asymmetric Polymer of a Thiophene-Benzene Unit-contained Diketopyrrolopyrrole (DPP)Derivative Used for Donor Material of Organic Solar Cells Article

ZENG Xianghua, LI Zhanfeng, REN Jingkun, LIU Weipeng, CHEN Jinbo, WANG Xiangkun, HAO Yuying

Materials Reports 2018,32(9 ):1423 -1426. DOI:10.11896/j.issn.1005-023X.2018.09.005

Abstract （769）

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Improved Electrocatalytic Hydrogen-evolution Performance of Metal-Organic Framework MOF(Ni)-74 by Using Graphene Oxide Decorations Article

CHU Mei, LI Xi, LI Na, HOU Meijing, LI Xiaozheng, DONG Yongzhi, WANG Lu

Materials Reports 2018,32(9 ):1417 -1422. DOI:10.11896/j.issn.1005-023X.2018.09.004

Abstract （888）

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Photovoltaic Characteristics of Cu₂ZnSn(S_xSe_1-x)₄ Thin Films Synthesizedvia the Process of Cu-Zn-Sn Presputtering and SubsequentSulfurization (Selenization) Annealing Article

LIU Yike, TANG Yaqin, JIANG Liangxing, LIU Fangyang, QIN Qin, ZHANG Kun

Materials Reports 2018,32(9 ):1412 -1416. DOI:10.11896/j.issn.1005-023X.2018.09.003

Abstract （763）

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Recent Progress in Sulfur Cathode for Li-S Batteries Article

CHEN Zichong, FANG Ruyi, LIANG Chu, GAN Yongping, ZHANG Wenkui

Materials Reports 2018,32(9 ):1401 -1411. DOI:10.11896/j.issn.1005-023X.2018.09.002

Abstract （1574）

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Save The global energy and environmental problems caused by the extensive use of fossil fuels have significantly impac-ted on the human’s production and livelihoods, which can be expected to well address via developing and utilizing various clean energy sources, such as solar energy, water energy and wind energy, etc. Efficient energy conversion and storage technologies are the key and basics of the large-scale use of clean energy due to their regional and intermittent characteristics. Lithium-ion batteries, as green energy storage devices, are widely used in mobile phones, laptops, cameras and other portable electronic devices. In recent years, lithium-ion batteries have begun to be applied in the field of power batteries such as electric vehicles. However, the electric vehicles suffer from inferior cruise-ability, frequent charging and high cost because of their relatively low energy density. The energy density (2 600 Wh·kg^-1) of lithium-sulfur batteries, composed of lithium metal as anode and sulfur as cathode, is much higher than that of state-of-the-art lithium-ion batteries. Additionally, the sulfur cathode material is abundant, nontoxic, cost effectiveness and environmental friendliness. Hence, lithium-sulfur batteries are considered as one of the most promising secondary batteries. However, the poor CE and limited cycle life, caused by the fundamental defects of sulfur cathode such as low ionic/electronic conductivities, large volumetric expansion and shuttle effect, hamper the widespread application of Li-S battery. So far, considerable studies have focused on enhancing the conductivity, inhibiting or eliminating the shuttle effect and stabilizing the microstructure of electrode material during repeated cycles. It has been demonstrated that the S/C composite cathode materials with special microstructure, prepared by compositing sulfur and carbon with different morphology, exhibit significantly improved conductivity, decreased shuttle effect of lithium polysulfide and less volume change during lithium intercalation/deintercalation. These improvements lead to better rate performance, cycling stability and charge-discharge efficiency. Moreover, the introduction of heterogeneous element-doped carbon materials, metal oxides and conductive polymers in the sulfur cathode material can achieve effective chemical adsorption of lithium polysulfide. Excellent electrochemical lithium storage performance of sulfur cathode can also be achieved by the combination of these various modification me-thods. In this review, the main problems and recent research progress in sulfur cathode materials are summarized and commented upon based on the principle of lithium-sulfur batteries. Meanwhile, it also gives brief suggestions and outlooks on the future research directions in lithium-sulfur batteries.

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A Review on the Fabrication of Perovskite Solar Cells via Printing Techniques Article

LI Hengyue, GONG Chendi, HUANG Keqing, YANG Junliang

Materials Reports 2018,32(9 ):1385 -1400. DOI:10.11896/j.issn.1005-023X.2018.09.001

Abstract （1188）

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Save Perovskite solar cells (PSCs) have attracted much attention during the past years due to their excellent photovoltaic properties and low-cost solution processing. The power conversion efficiency (PCE) has been rapidly increased to 22.7% since the first report of 3.8% in 2009, which approaches the levels of commercial polycrystalline silicon solar cells, CdTe solar cells and CIGS solar cells. Spin-coating is commonly used to fabricate PSCs in the labs, but it can’t meet the requirements for large-scale and low-cost process. It is simple to operate the spin-coating process with good repeatability. However, spin-coating still possesses some shortcomings, including serious waste of materials, only producing film without patterns, incapable of continuous fabrication. Therefore, it cannot match with the production of industrialization with large area and high throughout. It is still a big challenge to transfer the fabrication from lab-scale to large-scale industrialization with low cost and high throughout. Printing techniques show many advantages, e.g. high material utilization, low cost, large area, high throughout and matching with flexible substrate, and they have been used to fabricate PSCs. The PCE approaching 20% was achieved in printed, small-area PSCs, and numerous efforts have been made to improve printed large-area PSCs with PCE between 10% and 16%. Furthermore, it has already achieved printed, flexible PSCs with PCE of about 10%. There are still many issues to be solved for accelerating the industrialization. Ⅰ. Solvent engineering and gas-assisted treatment, commonly used in spin-coating process for producing high-quality perovskite films, are not matchable with printing process, resulting in the poor morphology and the low reproducibility in printed perovskite film. Ⅱ. The high-temperature annealing process would restrict the use of flexible substrate and the choice of interfacial materials. Ⅲ. Perovskite materials are sensitive to humidity, and it is necessary to improve their environment adaptability and reduce the cost. Hence, it is very important to optimize printing techniques for fabricating large-area PSCs with high efficiency, high throughout and low cost. In this review, we summarize the research progress on PSCs fabricated via printing techniques, including inkjet-printing, spray-coating, slot-die coating, doctor-blading. Furthermore, we also discuss the challenges and prospects of potential commercial PSCs.

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Preparation of Walnut Shell Activated Carbons via Combination of Hydrothermal Carbonization and KOH Activation Article

ZHANG Chuantao, XING Baolin, HUANG Guangxu, ZHANG Shuangjie, ZHANG Chuanxiang, SHI Changliang, ZHU Ahui, YAO Youheng, ZHANG Qingshan

Materials Reports 2018,32(7 ):1088 -1093. DOI:10.11896/j.issn.1005-023X.2018.07.007

Abstract （881）

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Effects of Structural Tuning on the Dehydrogenation Temperatures of Mg/Nb Composite Films Article

HUANG Wencheng, ZHANG Jinguo, YUAN Jun, LIU Jiangwen

Materials Reports 2018,32(7 ):1084 -1087. DOI:10.11896/j.issn.1005-023X.2018.07.006

Abstract （585）

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Inhibiting the Shuttle Effect of Lithium-Sulfur Batteries by Introducing a Dithiothreitol Interlayer Article

WANG Jie, SUN Xiaogang, CHEN Long, QIU Zhiwen, CAI Manyuan, LI Xu, CHEN Wei

Materials Reports 2018,32(7 ):1079 -1083. DOI:10.11896/j.issn.1005-023X.2018.07.005

Abstract （660）

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Latest Research Progress of Modifying the Separators Used for Lithium-Sulfur Batteries Article

GUO Yafang, XIAO Jianrong, HOU Yongxuan, QI Meng, JIANG Aihua

Materials Reports 2018,32(7 ):1073 -1078. DOI:10.11896/j.issn.1005-023X.2018.07.004

Abstract （1362）

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Research Progress in Separator Materials for Microbial Fuel Cells Article

LI Wenlong, XUE Ping

Materials Reports 2018,32(7 ):1065 -1072. DOI:10.11896/j.issn.1005-023X.2018.07.003

Abstract （779）

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Progress of Co-catalysts in the Systems of Photocatalytic Hydrogen Evolution Article

LI Xuli, WANG Xiaojing, ZHAO Jun, LI Yupei, LI Fatang, CHEN Xuemin

Materials Reports 2018,32(7 ):1057 -1064. DOI:10.11896/j.issn.1005-023X.2018.07.002

Abstract （879）

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Stable and High-efficient α-Fe₂O₃ Based Photoelectrochemical Water Splitting: Rational Materials Design and Charge Carrier Dynamics Article

XIE Jiale, YANG Pingping, LI Chang Ming

Materials Reports 2018,32(7 ):1037 -1056. DOI:10.11896/j.issn.1005-023X.2018.07.001

Abstract （777）

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Construction of a Hydrogen Permeation Model and with an Application to Nb-based Hydrogen Permeable Alloy Article

YAN Erhu, HUANG Haoran, LIU Guizhong, BAN Yufeng, XU Fen, SUN Lixian

Materials Reports 2018,32(5 ):725 -729. DOI:10.11896/j.issn.1005-023X.2018.05.006

Abstract （660）

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Iron Electrode Derived from Fe/Co-MOF and Its Electrochemical Performance for Nickel-Iron Batteries Article

ZHANG Hehe, LI Fangfang, WANG Haiyan, PENG Zhiguang, TANG Yougen

Materials Reports 2018,32(5 ):719 -724. DOI:10.11896/j.issn.1005-023X.2018.05.005

Abstract （792）

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Preparation of Cellulose Matrix Porous Carbon Film by a Facile Process and Its Electrochemical Performance Article

WU Yage, RAN Fen

Materials Reports 2018,32(5 ):715 -718. DOI:10.11896/j.issn.1005-023X.2018.05.004

Abstract （757）

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