Macrocell sensor systems for monitoring of the corrosion risk of the reinforcement in concrete structures

Since 1990, a special macrocell system, the so-called anode-ladder-system, has been used world-wide to monitor the corrosion risk of new concrete structures, besides other systems. This sensor-system indicates the depth of the critical chloride content initiating corrosion, i.e. the critical depth of the reinforcement with respect to corrosion. Subsequently, the time-to-corrosion can be determined, enabling the owners of buildings to initiate preventive protection measures before cracks and spalling occur. By measurement of the potentials and the electrical resistance of the concrete around the sensors, an estimation of the humidity, the availability of oxygen and the corrosion behaviour after depassivation is possible.To be able to monitor the corrosion risk for existing structures as well, a new sensor-system has been developed called expansion-ring-system. It consists of six measuring rings (‘anodes’) separated by sealing rings as parts of the main sensor and a ‘cathode-bar’, which are installed in small holes, to be drilled into the concrete.     

Passive cathodic water/air management device for micro-direct methanol fuel cells

A high efficient passive water/air management device (WAMD) is proposed and successfully demonstrated in this paper. The apparatus consists of cornered micro-channels and air-breathing windows with hydrophobicity arrangement to regulate liquids and gases to flow on their predetermined pathways. A high performance water/air separation with water removal rate of about 5.1 μl s⁻¹ cm⁻² is demonstrated. The performance of the proposed WAMD is sufficient to manage a cathode-generated water flux of 0.26 μl s⁻¹ cm⁻² in the micro-direct methanol fuel cells (μDMFCs) which are operated at 100 mW cm⁻² or 400 mA cm⁻². Furthermore, the condensed vapors can also be collected and recirculated with the existing micro-channels which act as a passive water recycling system for μDMFCs. The durability testing shows that the fuel cells equipped with WAMD exhibit improved stability and higher current density.     

Poly(ethene-1,1,2,2-tetrathiol): Novel cathode material with high specific capacity for rechargeable lithium batteries

Novel thioether compound poly(ethene-1,1,2,2-tetrathiol) was synthesized, characterized and tested as cathode active material. The polymer was synthesized by facile one-step procedure and its chemical structure was confirmed by FT-IR, FT-Raman, element analysis, and XPS spectral analysis. The polymer had good electrochemical activity as cathode material for rechargeable lithium battery. It showed stable discharge specific capacity about 300 mAh g⁻¹ and discharge voltage above 2 V. The thioether bond was deduced as the functional group. It was proposed that thioether bonds were oxidized to form thioether cations with the help of ether solvent, which offered energy storage.     

Selection of cathode contact materials for solid oxide fuel cells

The goal of this work is to identify suitable cathode contact materials (CCM) to bond and electrically connect LSCF cathode to Mn_1.5Co_1.5O₄-coated 441 stainless steel after sintering at the relatively low temperature of 900-1000 °C. A wide variety of CCM candidates are synthesized and characterized. For each, the conductivity, coefficient of thermal expansion, sintering behavior, and tendency to react with LSCF or Mn_1.5Co_1.5O₄ are determined. From this screening, LSCF, LSCuF, LSC, and SSC are selected as the most promising candidates. These compositions are applied to LSCF and Mn_1.5Co_1.5O₄-coated 441 stainless steel coupons and subjected to 200 h ASR testing at 800 °C. After area-specific resistance testing, the specimens are cross-sectioned and analyzed for interdiffusion across the CCM/LSCF or CCM/Mn_1.5Co_1.5O₄ interfaces. A relatively narrow band of interdiffusion is observed.     

固定转化器泄漏原因分析

采用化学、金相分析方法，结合腐蚀的基本原理，对热交换器的泄漏进行了综合分析，认为造成泄漏的主要原因是循环水中存在大量的氯离子，破坏了蚀剂的保护作用。致使管子产生曜慢穿洞泄漏。     

On the role of ultra-thin oxide cathode synthesis on the functionality of micro-solid oxide fuel cells: Structure, stress engineering and in situ observation of fuel cell membranes during operation

Microstructure and stresses in dense La_0.6Sr_0.4Co_0.8Fe_0.2O₃ (LSCF) ultra-thin films have been investigated to increase the physical thickness of crack-free cathodes and active area of thermo-mechanically robust micro-solid oxide fuel cell (μSOFC) membranes. Processing protocols employ low deposition rates to create a highly granular nanocrystalline microstructure in LSCF thin films and high substrate temperatures to produce linear temperature-dependent stress evolution that is dominated by compressive stresses in μSOFC membranes. Insight and trade-off on the synthesis are revealed by probing microstructure evolution and electrical conductivity in LSCF thin films, in addition to in situ monitoring of membrane deformation while measuring μSOFC performance at varying temperatures. From these studies, we were able to successfully fabricate failure-resistant square μSOFC (LSCF/YSZ/Pt) membranes with width of 250 μm and crack-free cathodes with thickness of ∼70 nm. Peak power density of ∼120 mW cm⁻² and open circuit voltage of ∼0.6 V at 560 °C were achieved on a μSOFC array chip containing ten such membranes. Mechanisms affecting fuel cell performance are discussed. Our results provide fundamental insight to pathways of microstructure and stress engineering of ultra-thin, dense oxide cathodes and μSOFC membranes.     

Al-doped Ni-rich cathode powders prepared from the precursor powders with fine size and spherical shape

LiNi_0.8Co_0.15Al_0.05O₂ cathode powders with fine size and spherical shape were prepared by solid-state reaction method using the Ni-Co-Al-O precursor powders with fine size and spherical shape. The Ni-Co-Al-O precursor powders with fine size and filled inner structure were prepared by spray pyrolysis from the spray solution with drying control chemical additive (DCCA), citric acid and ethylene glycol. The one LiNi_0.8Co_0.15Al_0.05O₂ cathode powder with fine size and spherical shape was formed from the one precursor powder with spherical shape and filled morphology. The mean size of the spherical shape LiNi_0.8Co_0.15Al_0.05O₂ cathode powders was 1.1 μm. The initial discharge capacity of the LiNi_0.8Co_0.15Al_0.05O₂ cathode powders prepared from the spray solution with citric acid, ethylene glycol and DCCA was 200 mAh g⁻¹. The cycle properties of the cathode powders prepared from the spray solution with and without additives were compared.     

PEDOT: Cathode active material with high specific capacity in novel electrolyte system

Poly(3,4-ethylenedioxythiophene) (PEDOT) was chemically synthesized and characterized by FT-IR, XRD, XPS, TGA and organic elemental analysis (EA). The polymer was tested as cathode active material for rechargeable lithium batteries. The cyclic voltammetry (CV) and charge–discharge tests of PEDOT as the cathode active material was investigated in an electrolyte system of LiN(CF₃SO₂)₂/1,2-dimethoxyethane/1,3-dioxopentane (1:2 by weight). The peak discharge capacity of up to 691 mAh/g was obtained during the 1st cycle, and remained above 330 mAh/g after 44 cycles. These results indicate that PEDOT can afford a high specific capacity as a cathode active material. A redox mechanism is tentatively proposed.     

A double-layer composite electrode based on SrSc0.2Co0.8O3−δ perovskite with improved performance in intermediate temperature solid oxide fuel cells

Dual-layer composite electrodes consisting of a layer adjoining to an Sm_0.2Ce_0.8O_1.9 (SDC) electrolyte composed of 70 wt.% SrSc_0.2Co_0.8O_3−δ + 30 wt.% Sm_0.2Ce_0.8O_1.9 (SScC + SDC composite) and a second layer composed of 70 wt.% SrSc_0.2Co_0.8O_3−δ + 30 wt.% Sm_0.5Sr_0.5CoO_3−δ (SScC + SmSC composite) were fabricated and investigated as potential cathodes in intermediate temperature solid-oxide fuel cells. Thermo-mechanical compatibility between the two electrode layers and between the electrode and the electrolyte were examined by SEM, XRD and EIS. After sintering, no clear boundary between SScC + SDC and SScC + SmSC layers was observable by SEM. The repeated thermal cycling didn’t induce the delamination of the electrode from the electrolyte nor the formation of cracks within the electrode. As a result, stable electrode performance was achieved during thermal cycling and long-term operation. Symmetric cell tests demonstrated that the dual-layer electrode with a ∼10-μm SScC + SDC layer and a ∼50-μm SScC + SmSC layer (SScC + SDC/SScC + SmSC (1:5)) had the lowest electrode-polarization resistance among those tested. Anode-supported fuel cells with an SDC electrolyte and SScC + SDC/SScC + SmSC (1:5) cathode were fabricated. Peak power density as high as 1326 mW cm⁻² was achieved at 650 °C, which was higher than for similar fuel cells with a single-layer SScC + SDC or an SScC + SmSC composite electrode.     

Chromium doping as a new approach to improve the cycling performance at high temperature of 5 V LiNi0.5Mn1.5O4-based positive electrode

LiCr_2YNi_0.5−YMn_1.5−YO₄ (0 < Y ≤ 0.2) spinels have been synthesized by a sucrose-aided combustion method. Two sets of Cr-doped samples have been obtained by heating the “as-prepared” samples at 700 and 900 °C for 1 h. X-ray diffraction and thermogravimetric data show that pure and single phase spinels with similar lattice parameter have been synthesized. The homogeneity and the sub-micrometric particle size of the spinels have been shown by SEM and TEM. The main effect of the temperature is to increase the particle size from ≈50 to ≈500 nm, on heating from 700 to 900 °C. The study of the influence of Cr-dopant content and thermal treatment on the electrochemical properties at 25 °C and at 55 °C has been carried out by galvanostatic cycling in Li-cells. The discharge capacity (≈130 mAh g⁻¹) does not noticeably change with the synthesis conditions; but the cycling performances are strongly modified. Key factors that control the cycling performances have been determined. The most highlighted result is that spinels heated at 900 °C with Y ≤ 0.1 have very high capacity retention at 55 °C (>96% after 40 cycles, cyclability >99.9% by cycle) indicating that metal doping is a new approach to prepare 5 V LiNi_0.5Mn_1.5O₅-based cathodes with excellent cycling performances at high temperature.