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排序方式: 共有1471条查询结果,搜索用时 15 毫秒
11.
Jian Zhou 《Electrochimica acta》2003,48(18):2571-2582
The effect on cycle capacity is reported of cathode material (metal oxide, carbon, and current collector) in lithium/metal oxide cells cycled with fumed silica-based composite electrolytes. Three types of electrolytes are compared: filler-free electrolyte consisting of methyl-terminated poly(ethylene glycol) oligomer (PEGdm, Mw=250)+lithium bis(trifluromethylsufonyl)imide (LiTFSI) (Li:O=1:20), and two composite systems of the above baseline liquid electrolyte containing 10-wt% A200 (hydrophilic fumed silica) or R805 (hydrophobic fumed silica with octyl surface group). The composite electrolytes are solid-like gels. Three cathode active materials (LiCoO2, V6O13, and LixMnO2), four conducting carbons (graphite Timrex® SFG 15, SFG 44, carbon black Vulcan XC72R, and Ketjenblack EC-600JD), and three current collector materials (Al, Ni, and carbon fiber) were studied. Cells with composite electrolytes show higher capacity, reduced capacity fade, and less cell polarization than those with filler-free electrolyte. Among the three active materials studied, V6O13 cathodes deliver the highest capacity and LixMnO2 cathodes render the best capacity retention. Discharge capacity of Li/LiCoO2 cells is affected greatly by cathode carbon type, and the capacity decreases in the order of Ketjenblack>SFG 15>SFG 44>Vulcan. Current collector material also plays a significant role in cell cycling performance. Lithium/vanadium oxide (V6O13) cells deliver increased capacity using Ni foil and carbon fiber current collectors in comparison to an Al foil current collector. 相似文献
12.
Binder effect on cycling performance of silicon/carbon composite anodes for lithium ion batteries 总被引:1,自引:0,他引:1
Libao Chen Xiaohua Xie Jingying Xie Ke Wang Jun Yang 《Journal of Applied Electrochemistry》2006,36(10):1099-1104
The cycling performance of a silicon/carbon composite anode has been significantly enhanced by using acrylic adhesive and modified acrylic adhesive as binder to fabricate the electrodes for lithium ion batteries. The capacity retentions of Si/C composite electrodes bound by acrylic adhesive and modified acrylic adhesive are 79% and 90% after 50 cycles, respectively. These two binders are electrochemically stable in the organic electrolyte in the working window. They also show larger adhesion strength between the coating and the Cu current collector as well as smaller solvent absorption in the electrolyte solvent than polyvinylidene fluoride (PVDF). Furthermore, sodium carboxyl methyl cellulose (CMC) plays an important role on improving the properties of acrylic adhesive, which increases the adhesive strength of acrylic adhesive and improves the activation of the electrodes. 相似文献
13.
Bo He Fei Li Hong Zhou Yongbing Dai Baode Sun 《Journal of Coatings Technology and Research》2007,4(3):335-340
Two kinds of thermal barrier coatings (TBCs), consisting of NiCoCrAlY bond coats (BCs) deposited by electron beam-physical
vapor deposition (EB-PVD) and high velocity oxy-fuel (HVOF) thermal spraying, respectively, and top 8 wt%Y2O3–ZrO2 (8YSZ) ceramic layers deposited by EB-PVD were prepared on near-α titanium alloys. The field emission scanning electronic
microscopy and microhardness indentation are used to study the microstructure and microhardness. Different failure features
including cracking patterns and the delamination degree of these two TBCs are discussed according to the thermal cycling tests
in the atmosphere. It is found that the morphology of the two BCs deposited by different methods (EB-PVD and HVOF) determines
the microstructure and microhardness of their corresponding top 8YSZ layers. The BC prepared by EB-PVD is dense and homogeneous,
which leads to a dense and hard 8YSZ with clustered slim columnar grains. The BC prepared by HVOF, however, is porous and
inhomogeneous in microstructure and, as a result, the top ceramic layer is loose with low microhardness and clustered coarse
columnar grains. 相似文献
14.
15.
何庆复 《武汉理工大学学报(材料科学英文版)》2009,24(3):428-431
Behaviour of hardening and serration yield of a Fe-Ni-Cr alloy under isothermal cycling (ISC) and out-phase TMF was studied
on the basis of varied hysteresis loops. Cycling hardening and serrated yielding for ISC depend on the temperature and the
total strain range, stronger hardening with serrated yielding at higher strain range under ISC at 600 °C, but no hardening
and serrated yielding occurred under ISC at 800 °C. Stronger hardening with stress serration occurred at the thermal path
going to the lowest temperature, no stress serration occurred at the highest temperature under the out-phase. The hardening
also depends on the total strain range, higher total strain range with lower cycling temperature resulted in a stronger hardening
and remarkable serration yielding behavior. Weaker hardening without serrated yielding occurred at near 800 °C may due to
an obvious cycling stress drop under out-phase TMF. Change in the shape of the hysteresis loops also expresses the degree
of the damage of the tested alloy under out-phase and ISC. 相似文献
16.
我国煤炭企业发展循环经济研究 总被引:1,自引:0,他引:1
首先分析了煤炭企业发展循环经济的必要性,在此基础上对煤炭企业发展循环经济的主要内容进行了具体阐释,最后着重探讨了煤炭企业发展循环经济的基本原则。 相似文献
17.
提出了对金属材料在无负载条件下进行尺寸稳定性评定的热循环在线检测法。实验证明:这种方法能对试样在热循环过程中的尺寸变化进行实时检测,可同时获得材料在每次热循环之后的尺寸变化规律和多次循环之后的尺寸变化总量,用它来评价不同材料或同一材料经不同工艺处理之后的尺寸稳定性非常直观和方便,具有测试周期短、精度高的特点。 相似文献
18.
YU Zemin ZHAO Liancheng 《稀有金属(英文版)》2007,26(1):62-67
The preparation process and electrochemical properties of LiMn2O4 and LiMnl.95M0.05O4 (M = Cr, Ni) were studied. The results show that the decomposition temperature range of xerogel prepared with lithium acetate and manganese acetate as raw rnaterials is large and the decomposition speed is slow. Oxygen consumed is apt to get a prompt supplement during the preparation of LiMn2O4, and carbonization of the organic matter can be reduced or avoided, which is favorable to the combination of lithium and manganese. Using lithium acetate, manganese acetate, chromium nitrate, and nickel nitrate as raw materials and adopting the citric acid complexing method, it has been found that the prepared powders have high purity, high quality stability, and even doping characters. With the increase of sintering temperature, the particle size and crystal lattice constant of LiMn1.95M0.05O4 (M = Cr, Ni) enhance. However, the purity of the product is relatively high and has no obvious change, which is advantageous to the control of the quality of LiMn1.95M0.0504 (M = Cr, Ni). Doping with a small amount of Cr3. and Ni^2+ can stabilize the spinel structure of LiMn2O4, suppress the Jahn-Teller effect, and improve the cycling properties but reduce the initial capacity. 相似文献
19.
The mechanical properties of B/Al composite were measured at room temperature in the as-fabricated condition and after thermal-mechanical cycling(TMC). The effects of TMC on microstructure and tensile fracture behavior of B/Al composite were studied using transmission electron microscope(TEM) and scanning electron microscope(SEM). The fibers/matrix interfaces are degraded during TMC, the extent of which is enhanced with increasing the cycles, causing a measurable decrease of stage I modulus of the B/Al composite. The TMC induces the dislocation generation in the aluminum matrix and the dislocation density increases with the cycles. The synergistic effect of the matrix strengthening and the interracial degradation during TMC is found to play an important role in controlling the changes of tensile strengths and fracture behavior of the composite. The ultimate tensile strength of the composite increases with the cycles increasing. The interfaces in the B/Al composite change from the stronglybonded states toward the appropriately-bonded ones with increasing the cycles. TMC will provide an approach of improving the strength of B/Al composites. 相似文献
20.
Thermal barrier coatings (TBCs) consisting of two layers with various yttria contents (ZrO
2- YO1.5/Ni-22Cr-10Al- lY) were plasma sprayed, and parts of the various specimens were glazed by using a pulsed CO2 laser. All the specimens were then subjected to furnace thermal cycling tests at 1100 °C; the effect of laser glazing on
the durability and failure mechanism of the TBCs was then evaluated. From these results, two models were developed to show
the failure mechanism of as- sprayed and laser- glazed TBCs: model A, which is thermal-stress dominant, and model V, which
is oxidation-stress dominant. For top coats containing cubic phase, cubic and monoclinic phases, or tetragonal and a relatively
larger amount of monoclinic phases, whose degradation is thermal- stress dominant, laser glazing improved the durability of
TBCs by a factor of about two to six. Segmented cracks that occurred during glazing proved beneficial for accommodating thermal
stress and raising the tolerance to oxidation, which resulted in a higher durability. Thermal barrier coatings with top coats
containing tetragonal phase had the highest durability. Degradation of such TBCs resulted mainly from oxidation of the bond
coats. For top coats with a greater amount of monoclinic phase, thermal mismatch stress occurred during cooling and detrimentally
affected durability. 相似文献