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Exploration of the oxygen transport behavior in non-precious metal catalyst-based cathode catalyst layer

Shiqu CHEN, Silei XIANG, Zehao TAN, Huiyuan LI, Xiaohui YAN, Jiewei YIN, Shuiyun SHEN, Junliang ZHANG

《能源前沿(英文)》 2023年 第17卷 第1期   页码 123-133 doi: 10.1007/s11708-022-0849-1

摘要: High cost has undoubtedly become the biggest obstacle to the commercialization of proton exchange membrane fuel cells (PEMFCs), in which Pt-based catalysts employed in the cathodic catalyst layer (CCL) account for the major portion of the cost. Although non-precious metal catalysts (NPMCs) show appreciable activity and stability in the oxygen reduction reaction (ORR), the performance of fuel cells based on NPMCs remains unsatisfactory compared to those using Pt-based CCL. Therefore, most studies on NPMC-based fuel cells focus on developing highly active catalysts rather than facilitating oxygen transport. In this work, the oxygen transport behavior in CCLs based on highly active Fe-N-C catalysts is comprehensively explored through the elaborate design of two types of membrane electrode structures, one containing low-Pt-based CCL and NPMC-based dummy catalyst layer (DCL) and the other containing only the NPMC-based CCL. Using Zn-N-C based DCLs of different thickness, the bulk oxygen transport resistance at the unit thickness in NPMC-based CCL was quantified via the limiting current method combined with linear fitting analysis. Then, the local and bulk resistances in NPMC-based CCLs were quantified via the limiting current method and scanning electron microscopy, respectively. Results show that the ratios of local and bulk oxygen transport resistances in NPMC-based CCL are 80% and 20%, respectively, and that an enhancement of local oxygen transport is critical to greatly improve the performance of NPMC-based PEMFCs. Furthermore, the activity of active sites per unit in NPMC-based CCLs was determined to be lower than that in the Pt-based CCL, thus explaining worse cell performance of NPMC-based membrane electrode assemblys (MEAs). It is believed that the development of NPMC-based PEMFCs should proceed not only through the design of catalysts with higher activity but also through the improvement of oxygen transport in the CCL.

关键词: proton exchange membrane fuel cells (PEMFCs)     non-precious metal catalyst (NPMC)     cathode catalyst layer (CCL)     local and bulk oxygen transport resistance    

Modeling nanostructured catalyst layer in PEMFC and catalyst utilization

Jiejing ZHANG, Pengzhen CAO, Li XU, Yuxin WANG

《化学科学与工程前沿(英文)》 2011年 第5卷 第3期   页码 297-302 doi: 10.1007/s11705-011-1201-1

摘要: A lattice model of the nanoscaled catalyst layer structure in proton exchange membrane fuel cells (PEMFC) was established by Monte Carlo method. The model takes into account all the four components in a typical PEMFC catalyst layer: platinum (Pt), carbon, ionomer and pore. The elemental voxels in the lattice were set fine enough so that each average sized Pt particulate in Pt/C catalyst can be represented. Catalyst utilization in the modeled catalyst layer was calculated by counting up the number of facets of Pt voxels where “three phase contact” are met. The effects of some factors, including porosity, ionomer content, Pt/C particle size and Pt weight percentage in the Pt/C catalyst, on catalyst utilization were investigated and discussed.

关键词: catalyst layer     PEM fuel cell     lattice model     Monte Carlo method     catalyst utilization    

Chemical composition and formation mechanisms in the cathode-electrolyte interface layer of lithium manganese

Sahithya REDDIVARI, Christian LASTOSKIE, Ruofei WU, Junliang ZHANG

《能源前沿(英文)》 2017年 第11卷 第3期   页码 365-373 doi: 10.1007/s11708-017-0500-8

摘要: Lithium manganese oxide (LiMn O ) is a principal cathode material for high power and high energy density electrochemical storage on account of its low cost, non-toxicity, and ease of preparation relative to other cathode materials. However, there are well-documented problems with capacity fade of lithium ion batteries containing LiMn O . Experimental observations indicate that the manganese content of the electrolyte increases as an electrochemical cell containing LiMn O ages, suggesting that active material loss by dissolution of divalent manganese from the LiMn O surface is the primary reason for reduced cell life in LiMn O batteries. To improve the retention of manganese in the active material, it is key to understand the reactions that occur at the cathode surface. Although a thin layer of electrolyte decomposition products is known to form at the cathode surface, the speciation and reaction mechanisms of Mn in this interface layer are not yet well understood. To bridge this knowledge gap, reactive force field (ReaxFF) based molecular dynamics was applied to investigate the reactions occurring at the LiMn O cathode surface and the mechanisms that lead to manganese dissolution. The ReaxFFMD simulations reveal that the cathode-electrolyte interface layer is composed of oxidation products of electrolyte solvent molecules including aldehydes, esters, alcohols, polycarbonates, and organic radicals. The oxidation reaction pathways for the electrolyte solvent molecules involve the formation of surface hydroxyl species that react with exposed manganese atoms on the cathode surface. The presence of hydrogen fluoride (HF) induces formation of inorganic metal fluorides and surface hydroxyl species. Reaction products predicted by ReaxFF-based MD are in agreement with experimentally identified cathode-electrolyte interface compounds. An overall cathode-electrolyte interface reaction scheme is proposed based on the molecular simulation results.

关键词: lithium manganese oxide batteries     reactive force field (ReaxFF)     cathode-electrolyte interface layer     molecular dynamics    

Review of characterization and modeling of polymer electrolyte fuel cell catalyst layer: The blessing

Jun HUANG, Zhe LI, Jianbo ZHANG

《能源前沿(英文)》 2017年 第11卷 第3期   页码 334-364 doi: 10.1007/s11708-017-0490-6

摘要: Ionomer impregnation represents a milestone in the evolution of polymer electrolyte fuel cell (PEFC) catalyst layers. Ionomer acts as the binder, facilitates proton transport, and thereby drastically improves catalyst utilization and effectiveness. However, advanced morphological and functional characterizations have revealed that up to 60% of Pt nanoparticles can be trapped in the micropores of carbon support particles. Ionomer clusters and oxygen molecules can hardly enter into micropores, leading to low Pt utilization and effectiveness. Moreover, the ionomer thin-films covering Pt nanoparticles can cause significant mass transport loss especially at high current densities. Ionomer-free ultra-thin catalyst layers (UTCLs) emerge as a promising alternative to reduce Pt loading by improving catalyst utilization and effectiveness, while theoretical issues such as the proton conduction mechanism remain puzzling and practical issues such as the rather narrow operation window remain unsettled. At present, the development of PEFC catalyst layer has come to a crossroads: staying ionomer-impregnated or going ionomer-free. It is always beneficial to look back into the past when coming to a crossroads. This paper addresses the characterization and modeling of both the conventional ionomer-impregnated catalyst layer and the emerging ionomer-free UTCLs, featuring advances in characterizing microscale distributions of Pt particles, ionomer, support particles and unraveling their interactions; advances in fundamental understandings of proton conduction and flooding behaviors in ionomer-free UTCLs; advances in modeling of conventional catalyst layers and especially UTCLs; and discussions on high-impact research topics in characterizing and modeling of catalyst layers.

关键词: polymer electrolyte fuel cell     ultra-thin catalyst layer     electrostatic interactions     characterization and modeling     structure-property-performance relation     water management    

Effect of catalyst layer mesoscopic pore-morphology on cold start process of PEM fuel cells

Ahmed Mohmed DAFALLA, Fangming JIANG

《能源前沿(英文)》 2021年 第15卷 第2期   页码 460-472 doi: 10.1007/s11708-021-0733-4

摘要: Water transport is of paramount importance to the cold start of proton exchange membrane fuel cells (PEMFCs). Analysis of water transport in cathode catalyst layer (CCL) during cold start reveals the distinct characteristics from the normal temperature operation. This work studies the effect of CCL mesoscopic pore-morphology on PEMFC cold start. The CCL mesoscale morphology is characterized by two tortuosity factors of the ionomer network and pore structure, respectively. The simulation results demonstrate that the mesoscale morphology of CCL has a significant influence on the performance of PEMFC cold start. It was found that cold-starting of a cell with a CCL of less tortuous mesoscale morphology can succeed, whereas starting up a cell with a CCL of more tortuous mesoscale morphology may fail. The CCL of less tortuous pore structure reduces the water back diffusion resistance from the CCL to proton exchange membrane (PEM), thus enhancing the water storage in PEM, while reducing the tortuosity in ionomer network of CCL is found to enhance the water transport in and the water removal from CCL. For the sake of better cold start performance, novel preparation methods, which can create catalyst layers of larger size primary pores and less tortuous pore structure and ionomer network, are desirable.

关键词: cold start     energy conversion     fuel cells     mesoscale morphology     tortuosity     water management    

DOW CORNING 1-2577 Conformal Coating as an efficient diffusion material for cathode in the microbial

Yanping HOU, Haiping LUO, Guangli LIU, Renduo ZHANG, Yong LUO, Bangyu QIN, Shanshan CHEN

《环境科学与工程前沿(英文)》 2013年 第7卷 第4期   页码 526-530 doi: 10.1007/s11783-013-0532-1

摘要: In this study, DOW CORNING 1-2577 Conformal Coating was proposed for the cathode diffusion layer of the microbial fuel cell (MFC). In MFCs, stainless steel mesh cathodes using DOW CORNING 1-2577 Conformal Coating/carbon as the diffusion layer and two poly (dimethylsiloxane) (PDMS)/carbon diffusion layers and carbon cloth cathode with four poly (tetrafluoroethylene) (PTFE) diffusion layers were constructed for comparison. Under the same operational condition, the MFCs with the DOW CORNING 1-2577 Conformal Coating/carbon diffusion layer produced the maximum power density of 1585±52 mW·m , compared with those using poly (tetrafluoroethylene) (PTFE) diffusion layers (1421±45 mW·m ) and poly (dimethylsiloxane) (PDMS)/carbon diffusion layers (1353±49 mW·m ). The DOW CORNING 1-2577 Conformal Coating could be an alternative for the diffusion layer construction in the MFC due to its remarkable performance and much simple construction procedure.

关键词: microbial fuel cell     diffusion layer     power density     DOW CORNING1-2577 Conformal Coating    

Mapping the trends and prospects of battery cathode materials based on patent landscape

《能源前沿(英文)》   页码 822-832 doi: 10.1007/s11708-023-0900-x

摘要: Advancing portable electronics and electric vehicles is heavily dependent on the cutting-edge lithium-ion (Li-ion) battery technology, which is closely linked to the properties of cathode materials. Identifying trends and prospects of cathode materials based on patent analysis is considered a kernel to optimize and refine battery related markets. In this paper, a patent analysis is performed on 6 popular cathode materials by comprehensively considering performance comparison, development trend, annual installed capacity, technology life cycle, and distribution among regions and patent assignees. In the technology life cycle, the cathode materials majorly used in electric vehicle have entered maturity stage, while the lithium cobalt oxide (LCO) cathode that is widely used in portable electronics is still in the growth stage. In global patent distributions, China holds more than 50% of total patents. In the top 10 patent assignees of 6 cathode materials, 2 institutes are from China with the rest being Japan (6) and Republic of Korea (2), indicating that the technology of cathode materials in China is relatively scattered while cathode research is highly concentrated in Japan and Republic of Korea. Moreover, the patent distribution has to consider practical issues as well as the impacts of core patents. For example, the high cost discourages the intention of applying international patents. This paper is expected to stimulate battery research, understand technical layout of various countries, and probably forecast innovative technology breakthroughs.

关键词: patent analysis     cathode     batteries     technology life cycle    

Fabrication of layered structure VS anchor in 3D graphene aerogels as a new cathode material for lithium

《能源前沿(英文)》 2019年 第13卷 第3期   页码 597-602 doi: doi:10.1007/s11708-018-0576-9

摘要: VS4 has gained more and more attention for its high theoretical capacity (449 mAh/g with 3e transfer) in lithium ion batteries (LIBs). Herein, a layered structure VS4 anchored in graphene aerogels is prepared and first reported as cathode material for LIBs. VS4@GAs composite exhibits an exceptional high initial reversible capacity (511 mAh/g), an excellent high-rate capability (191 mAh/g at the 5 C), and an excellent cyclic stability (239 mAh/g after 15 cycles).

关键词: VS4     graphene aerogels     cathode     lithium storage    

Recent advances in cathode electrocatalysts for PEM fuel cells

Junliang ZHANG

《能源前沿(英文)》 2011年 第5卷 第2期   页码 137-148 doi: 10.1007/s11708-011-0153-y

摘要: Great progress has been made in the past two decades in the development of the electrocatalysts for proton exchange membrane fuel cells (PEMFCs). This review article is focused on recent advances made in the kinetic-activity improvement on platinum- (Pt-) based cathode electrocatalysts for the oxygen reduction reaction (ORR). The origin of the limited ORR activity of Pt catalysts is discussed, followed by a review on the development of Pt alloy catalysts, Pt monolayer catalysts, and shape- and facet-controlled Pt-alloy nanocrystal catalysts. Mechanistic understanding is reviewed as well on the factors contributing to the enhanced ORR activity of these catalysts. Finally, future directions for PEMFC catalyst research are proposed.

关键词: proton exchange membrane fuel cells (PEMFCs)     cathode electrocatalysts     platinum     oxygen reduction reaction (ORR)    

Current challenge and perspective of PGM-free cathode catalysts for PEM fuel cells

Gang WU

《能源前沿(英文)》 2017年 第11卷 第3期   页码 286-298 doi: 10.1007/s11708-017-0477-3

摘要: To significantly reduce the cost of proton exchange membrane fuel cells, platinum-group metal (PGM)-free cathode catalysts are highly desirable. Current M-N-C (M: Fe, Co or Mn) catalysts are considered the most promising due to their encouraging performance. The challenge thus has been their stability under acidic conditions, which has hindered their use for any practical applications. In this review, based on the author’s research experience in the field for more than 10 years, current challenges and possible solutions to overcome these problems were discussed. The current Edisonian approach (i.e., trial and error) to developing PGM-free catalysts has been ineffective in achieving revolutionary breakthroughs. Novel synthesis techniques based on a more methodological approach will enable atomic control and allow us to achieve optimal electronic and geometric structures for active sites uniformly dispersed within the 3D architectures. Structural and chemical controlled precursors such as metal-organic frameworks are highly desirable for making catalysts with an increased density of active sites and strengthening local bonding structures among N, C and metals. Advanced electrochemical and physical characterization, such as electron microscopy and X-ray absorption spectroscopy should be combined with first principle density functional theory (DFT) calculations to fully elucidate the active site structures.

关键词: oxygen reduction     fuel cells     cathode     nonprecious metal catalysts     carbon nanocomposites    

Effects of bicarbonate and cathode potential on hydrogen production in a biocathode electrolysis cell

Dawei LIANG,Yanyan LIU,Sikan PENG,Fei LAN,Shanfu LU,Yan XIANG

《环境科学与工程前沿(英文)》 2014年 第8卷 第4期   页码 624-630 doi: 10.1007/s11783-013-0584-2

摘要: A biocathode with microbial catalyst in place of a noble metal was successfully developed for hydrogen evolution in a microbial electrolysis cell (MEC). The strategy for fast biocathode cultivation was demonstrated. An exoelectrogenic reaction was initially extended with an H -full atmosphere to enrich H -utilizing bacteria in a MEC bioanode. This bioanode was then inversely polarized with an applied voltage in a half-cell to enrich the hydrogen-evolving biocathode. The electrocatalytic hydrogen evolution reaction (HER) kinetics of the biocathode MEC could be enhanced by increasing the bicarbonate buffer concentration from 0.05 mol·L to 0.5 mol·L and/or by decreasing the cathode potential from -0.9 V to -1.3 V vs. a saturated calomel electrode (SCE). Within the tested potential region in this study, the HER rate of the biocathode MEC was primarily influenced by the microbial catalytic capability. In addition, increasing bicarbonate concentration enhances the electric migration rate of proton carriers. As a consequence, more mass H can be released to accelerate the biocathode-catalyzed HER rate. A hydrogen production rate of 8.44 m ·m ·d with a current density of 951.6 A·m was obtained using the biocathode MEC under a cathode potential of -1.3 V vs. SCE and 0.4 mol·L bicarbonate. This study provided information on the optimization of hydrogen production in biocathode MEC and expanded the practical applications thereof.

关键词: microbial electrolysis cell (MEC)     biocathode     hydrogen production     bicarbonate     cathode potential    

A comprehensive assessment on the durability of gas diffusion electrode materials in PEM fuel cell stack

Arunkumar JAYAKUMAR

《能源前沿(英文)》 2019年 第13卷 第2期   页码 325-338 doi: 10.1007/s11708-019-0618-y

摘要: Polymer electrolyte membrane (PEM) fuel cell is the most promising among the various types of fuel cells. Though it has found its applications in numerous fields, the cost and durability are key barriers impeding the commercialization of PEM fuel cell stack. The crucial and expensive component involved in it is the gas diffusion electrode (GDE) and its degradation, which limits the performance and life of the fuel cell stack. A critical analysis and comprehensive understanding of the structural and functional properties of various materials involved in the GDE can help us to address the related durability and cost issues. This paper reviews the key GDE components, and in specific, the root causes influencing the durability. It also envisages the role of novel materials and provides a critical recommendation to improve the GDE durability.

关键词: PEM fuel cell     gas diffusion electrode(GDE)     gas diffusion layer(GDL)     membrane electrode assembly     durability     fuel cell catalyst    

Effect of current density on groundwater arsenite removal performance using air cathode electrocoagulation

《环境科学与工程前沿(英文)》 2021年 第15卷 第6期 doi: 10.1007/s11783-021-1399-1

摘要:

• With the same charge, current density had little effect on As(III) removal in ACEC.

关键词: Electrocoagulation     Air cathode     Arsenic     Current density     Energy consumption    

Block copolymers as efficient cathode interlayer materials for organic solar cells

Dingqin Hu, Jiehao Fu, Shanshan Chen, Jun Li, Qianguang Yang, Jie Gao, Hua Tang, Zhipeng Kan, Tainan Duan, Shirong Lu, Kuan Sun, Zeyun Xiao

《化学科学与工程前沿(英文)》 2021年 第15卷 第3期   页码 571-578 doi: 10.1007/s11705-020-2010-1

摘要: Emerging needs for the large-scale industrialization of organic solar cells require high performance cathode interlayers to facilitate the charge extraction from organic semiconductors. In addition to improving the efficiency, stability and processability issues are major challenges. Herein, we design block copolymers with well controlled chemical composition and molecular weight for cathode interlayer applications. The block copolymer coated cathodes display high optical transmittance and low work function. Conductivity studies reveal that the block copolymer thin film has abundant conductive channels and excellent longitudinal electron conductivity due to the interpenetrating networks formed by the polymer blocks. Applications of the cathode interlayers in organic solar cells provide higher power conversion efficiency and better stability compared to the most widely-applied ZnO counterparts. Furthermore, no post-treatment is needed which enables excellent processability of the block copolymer based cathode interlayer.

关键词: organic solar cell     block copolymer     cathode interlayer    

Alumina modified sodium vanadate cathode for aqueous zinc-ion batteries

《能源前沿(英文)》   页码 775-781 doi: 10.1007/s11708-023-0902-8

摘要: Aqueous zinc-ion batteries (ZIBs) have great prospects for widespread application in massive scale energy storage. By virtue of the multivalent state, open frame structure and high theoretical specific capacity, vanadium (V)-based compounds are a kind of the most developmental potential cathode materials for ZIBs. However, the slow kinetics caused by low conductivity and the capacity degradation caused by material dissolution still need to be addressed for large-scale applications. Therefore, sodium vanadate Na2V6O16·3H2O (NVO) was chosen as a model material, and was modified with alumina coating through simple mixing and stirring methods. After Al2O3 coating modification, the rate capability and long-cycle stability of Zn//NVO@Al2O3 battery have been significantly improved. The discharge specific capacity of NVO@Al2O3 reach up to 228 mAh/g (at 4 A/g), with a capacity reservation rate of approximately 68% after 1000 cycles, and the Coulombic efficiency (CE) is close to 100%. As a comparison, the capacity reservation rate of Zn//NVO battery is only 27.7%. Its superior electrochemical performance is mainly attributed to the Al2O3 coating layer, which can increase zinc-ion conductivity of the material surface, and to some extent inhibit the dissolution of NVO, making the structure stable and improving the cyclic stability of the material. This paper offers new prospects for the development of cathode coating materials for ZIBs.

关键词: cathodes     aqueous zinc-ion batteries     sodium vanadate     alumina     coating    

标题 作者 时间 类型 操作

Exploration of the oxygen transport behavior in non-precious metal catalyst-based cathode catalyst layer

Shiqu CHEN, Silei XIANG, Zehao TAN, Huiyuan LI, Xiaohui YAN, Jiewei YIN, Shuiyun SHEN, Junliang ZHANG

期刊论文

Modeling nanostructured catalyst layer in PEMFC and catalyst utilization

Jiejing ZHANG, Pengzhen CAO, Li XU, Yuxin WANG

期刊论文

Chemical composition and formation mechanisms in the cathode-electrolyte interface layer of lithium manganese

Sahithya REDDIVARI, Christian LASTOSKIE, Ruofei WU, Junliang ZHANG

期刊论文

Review of characterization and modeling of polymer electrolyte fuel cell catalyst layer: The blessing

Jun HUANG, Zhe LI, Jianbo ZHANG

期刊论文

Effect of catalyst layer mesoscopic pore-morphology on cold start process of PEM fuel cells

Ahmed Mohmed DAFALLA, Fangming JIANG

期刊论文

DOW CORNING 1-2577 Conformal Coating as an efficient diffusion material for cathode in the microbial

Yanping HOU, Haiping LUO, Guangli LIU, Renduo ZHANG, Yong LUO, Bangyu QIN, Shanshan CHEN

期刊论文

Mapping the trends and prospects of battery cathode materials based on patent landscape

期刊论文

Fabrication of layered structure VS anchor in 3D graphene aerogels as a new cathode material for lithium

期刊论文

Recent advances in cathode electrocatalysts for PEM fuel cells

Junliang ZHANG

期刊论文

Current challenge and perspective of PGM-free cathode catalysts for PEM fuel cells

Gang WU

期刊论文

Effects of bicarbonate and cathode potential on hydrogen production in a biocathode electrolysis cell

Dawei LIANG,Yanyan LIU,Sikan PENG,Fei LAN,Shanfu LU,Yan XIANG

期刊论文

A comprehensive assessment on the durability of gas diffusion electrode materials in PEM fuel cell stack

Arunkumar JAYAKUMAR

期刊论文

Effect of current density on groundwater arsenite removal performance using air cathode electrocoagulation

期刊论文

Block copolymers as efficient cathode interlayer materials for organic solar cells

Dingqin Hu, Jiehao Fu, Shanshan Chen, Jun Li, Qianguang Yang, Jie Gao, Hua Tang, Zhipeng Kan, Tainan Duan, Shirong Lu, Kuan Sun, Zeyun Xiao

期刊论文

Alumina modified sodium vanadate cathode for aqueous zinc-ion batteries

期刊论文