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锂离子蓄电池正极材料LiMn2O4--包覆LiCoO2对LiMn2O4循环性能的影响 总被引:7,自引:0,他引:7
将LiMn2O4置于LiAc和CoAc2的混合溶液中,缓慢蒸干溶液,煅烧后获得了包覆LiCoO2的LiMn2O4材料。通过电化学测试研究了钴的包覆量、煅烧温度、煅烧时间对包覆LiCoO2的LiMn2O4材料循环性能的影响,并比较了包覆Li CoO2前后,LiMn2O4材料分别在常温和高温环境下循环性能的差异。实验结果表明,在LiMn2O4的表面包覆LiCoO2,可以使LiMn2O4在常温和高温环境下获得良好的循环性能。 相似文献
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采用溶胶-凝胶法合成了LiCoO2包覆改性的尖晶石型LiMn2-xCrxO4(x=0,0.05,0.1)正极材料.XRD表征改性材料均具有良好的尖晶石型结构;扫描电子显微镜(SEM)显示改性样品具有更好的颗粒分散度和表面形貌;充放电表明改性样品的循环性能均具有不同程度的提高,其中样品5%LiCoO2-LiMn1.95Cr0.05O4与未改性或仅掺杂Cr的材料相比较,更好地抑制了可逆容量在循环充放电中的衰减,50次循环充放电容量(122.3~112.4 mAh/g)仍保持在91.9%以上.循环伏安和电化学阻抗测试也表明该材料具有良好的充放电可逆性和较小的阻抗. 相似文献
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尖晶石LiMn2O4高温电化学性能研究 总被引:1,自引:0,他引:1
利用高温固相反应合成了锂离子蓄电池正极材料尖晶石LiMn2 O4 ,研究了在高温 5 5℃下LiMn2 O4 循环容量的衰减和贮存后电化学性能的变化。与常温下相比较 ,5 5℃下尖晶石的容量衰减显著加快 ,贮存后的LiMn2 O4 循环性能变差。改变合成工艺条件如合成温度、n(Li)∶n(Mn)比 ,LiMn2 O4 的高温电化学性能有所改善 ,掺杂金属Co元素合成尖晶石掺Co化合物也能够提高LiMn2 O4 在高温下的循环性能 ,通过测量LiMn2 O4 在高温下电解液中的溶解 ,分析了容量衰减的机理。 相似文献
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氢氧等离子体合成过氧化氢过程的能效研究 总被引:1,自引:1,他引:0
为提高氢氧等离子体合成H2O2技术的能量效率,通过分析放电过程的反应器能效及电源能量注入效率,确定了影响合成总能效的主要因素。考察了反应器电极间距、电源放电频率及注入功率对反应器能效和电源能量注入效率的影响。发现减小电极间距、提高放电频率和注入功率有利于提高反应器能效,但不利于提高电源能量注入效率。本研究中可以得到150 gH2O2/kWh的反应器能效,但由于较低的电源能量注入效率,致使合成H2O2的总能效不超过9 gH2O2/kWh。因此,提高等离子体法合成H2O2过程的总能效,不仅需要设计高能效的等离子体反应器,还需为反应器负载开发适配的电源,而后者是提升该技术能量效率的关键。 相似文献
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Simultaneous conduction of oxide ions and electrons in solid ceramic systems provides the capability for oxygen transport under a concentration gradient without the need for an externally applied electric field. In the present study, ionic transference numbers have been measured in the ZrO2-5.8%Y2O3-10%CeO2 system by open circuit Emf measurements involving different metal/metal oxide electrodes. In order to correlate the ionic transference number with grain size, high-density ceramic discs of different grain sizes (50 nm–5 m) were prepared by sintering pressed powders at various temperatures and times. Hydrothermal synthesis was used to prepare nanocrystalline powders of the above material with uniform crystallite size (10 nm) and chemistry. Emf measurements on the samples suggested both ionic and electronic transport, the ionic transference number decreasing with increase in the grain size. This observation was attributed to an increase in the amount of continuous crystalline grain boundary phase in the ceramics as the grain size increased. The presence of crystalline silicate and zirconate phases in the grain boundary region was confirmed by electron microscopic imaging combined with microanalysis. In the large grain (5 m) ceramics, the ionic transference number decreased linearly with temperature. As the grain size decreased, a maximum occurred in the ionic transference number vs. temperature curve. This maximum became more pronounced at smaller grain sizes. Better grain-grain contact and the doping effect of trivalent Ce in the grain boundary core are proposed to explain this observation. 相似文献
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以Ti N、RuCl3和H2IrCl6为原料,用真空浸渍-热分解法制备了RuO2-IrO2-Ti O2,研究了煅烧温度和n(Ru+Ir)∶n(Ti)对产物的影响。XRD分析表明:Ti N在高温煅烧时氧化生成金红石型Ti O2,RuO2、IrO2和Ti O2以固溶体的形式存在。CV、阳极极化曲线和EIS测试表明:RuO2-IrO2-Ti O2的最佳煅烧温度为400℃,随着n(Ru+Ir)∶n(Ti)的提高,催化剂的活性增强;在相同电位下,RuO2-IrO2-Ti O2的电流密度大于IrO2,可用作固体聚合物电解质(SPE)水电解催化剂。 相似文献
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采用富氧火焰 (Air—C2 H2 —O2 )原子吸收光谱法直接测定铅钙锡合金中 0 1%以上的锡。对仪器工作条件、测定体系酸度、共存离子干扰等作了研究。方法准确度高 ,结果重现性好 相似文献
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Weerasak Somkhunthot Watcharin Detkunthong Areerat Dawongsa Kitsana Lamsombat Chartchai Bunyattrakoon Sasima Kongmongkol 《Integrated ferroelectrics》2015,165(1):31-44
Thermoelectric minerals have been found at Loei Province, in the northeastern part of Thailand. Local mineral specimens were prepared in the powders and bulk solids form by crushing, calcination and annealing, pressure and sintering, cutting and polishing. Mineral samples were used to analyze the composition and phase, determine the thermoelectric property and efficiency, design and construct a thermoelectric generator. Chemical composition and phase identification of powder samples were analyzed by the x-ray fluorescence (XRF) and x-ray diffraction (XRD), respectively. XRF and XRD results indicated that the mineral samples comprised the SO3-CaO-SiO2-others, Fe2O3-SO3-SiO2-others, Fe2O3-SiO2-others and Fe2O3-SiO2-CuO-others. From the thermoelectric property and efficiency determinations, the p-SO3-CaO-SiO2-others, p-Fe2O3-SO3-SiO2-others, n-Fe2O3-SiO2-others and n-Fe2O3-SiO2-CuO-others bulks were found to exhibit the thermoelectric figure of merit in orders of 10?14, 10?11, 10?14 and 10?13 K?1, respectively. A fabricated thermoelectric generator made from ten pairs of p-Fe2O3-SO3-SiO2-others and n-Fe2O3-SiO2-CuO-others legs that can be provided the open circuit voltage and short circuit current up to 48.30 mV and 0.14 μA for a temperature difference of 39.80 K at room temperature, respectively. While the internal resistance decreased and reached a value of 665 kΩ. 相似文献
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Feasibility of formation of stoichiometric precursors of either M2 (TiO)2(C2O4)5 4H2O (M = La and Nd) or coprecipitated hydroxides of M(OH)3+TiO(OH)2 was investigated by two solution routes at different pH values. Composition of precipitates obtained at pH = 7.0 by coprecipitation method starting from La or Nd nitrates and potassium titanyl oxalate corresponded to a physical mixture of La or Nd(C2O4)3 9.5H2O and TiO(OH)27·H2O which on thermal decomposition did not yield phase pure M2Ti2O7. However, precipitation from La or Nd nitrates and titanium tertrachloride by urea hydrolysis yielded homogeneous mixture of hydroxides of La or Nd and Ti, which on pyrolysis at 950°C yielded phase pure La2Ti2O7 and Nd2Ti2O7. Use of potassium titanyl oxalate as precursor for Ti, led to selective precipitation of La or Nd oxalate even at pH as low as 0.1 leading to sequential precipitation of La or Nd oxalate followed by Ti hydroxide at pH = 3.0. The resultant precipitate on pyrolysis underwent typical solid-state reaction. 相似文献
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J. A. Cho S. E. Park T. K. Song M. H. Kim H. S. Lee S. S. Kim 《Journal of Electroceramics》2004,13(1-3):515-518
Nonstoichiometric SrBi2Ta2O9 (SBT) and SrBi2Nb2O9 (SBN) ceramics were prepared by a solid state reaction method. X-ray diffraction analysis showed that single-phase of Bi-layered perovskite was obtained. With different Sr/Bi content ratios of SBT and SBN, Curie temperature (TC), electromechanical factor (Kp) and mechanical quality factor (Qm) were measured. TC of SBN (SBT) rose from 414C (314C) to 494C (426C) when Sr/Bi content ratio was increased from 0.55/2.3 to 1.2/1.8. In the most Sr-deficient/Bi-excess ratio of 0.55/2.3, the maximum values of Qm were obtained approximately 1013 and 3325 for SBT and SBN, respectively. 相似文献
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CO2和H2合成CO是CO2化学利用的重要过程,然而,传统的催化转化难以实现高效转化。在室温和大气压下,通过非平衡等离子体对H2和CO2的活化作用,考察了等离子体反应器结构、极间距、放电功率和氢碳比等对CO2转化率、CO选择性和CO2转化的能量效率影响。实验结果表明,在室温和大气压下,用等离子体法可将CO2高效的还原为CO,适当调节上述各参数可提高CO2的转化率。采用管管式等离子体反应器,在放电频率为10kHz、H2与CO2体积进料比为2:1、放电功率为80W、CO2气体体积流量为120mL/min的条件下,CO2转化率为88.2%,CO选择性为100%。 相似文献
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采用雾化工艺制备含有多种添加元素的AgSnBi合金粉。合金粉氧化后经过扩散处理、压制、烧结、挤压、轧制或拉丝得到AgSnO2_Bi2Sn2O7系列银复合氧化锡材料。丝材加工制作成铆钉触头,在ZWP-1型电性能模拟试验机上与AgNi(10)、AgCdO(12)进行直流、灯负载条件模拟电寿命对比试验。结果表明,银复合氧化锡材料、AgNi(10)、AgCdO(12)的电寿命分别为132358~148153次、15930~17300次、6054~8038次。将银复合氧化锡材料装在商用开关上进行电性能型式试验,常规操作寿命试验和荧光灯负载开关试验后端子的最高温升分别为42.5K和17.1K。 相似文献