Fabrication and characterization of In doped Li13.9Sr0.1Zn(GeO4+δ)4 electrolytes for proton-conducting solid oxide fuel cells

Li_13.9Sr_0.1Zn(GeO_4+δ)₄ (LSZG) materials can exhibit proton conduction by Li⁺/H⁺ ion exchange in hydrogen atmosphere. It can be used in solid oxide fuel cells (SOFCs) as an electrolyte. In this study, In³⁺ doped LSZG powders are synthesized by sol-gel method. X-ray diffraction, scanning electron microscopy, thermal gravimetric analyzer, and electrochemical impedance spectroscopy are used to investigate the effects of In doping on LSZG. All Li_13.9-xIn_xSr_0.1Zn(GeO_4+δ)₄ (LISZG, 0 ≤ x ≤ 0.3) ceramics exhibit the same phase with LSZG. The dopant of In promotes the sintering activity and Li⁺/H⁺ ion exchange rate of LSZG. The optimum doping of In is x = 0.2. At 600 °C, Li_13.7In_0.2Sr_0.1Zn(GeO_4+δ)₄ (0.2LISZG) shows a proton conductivity of 0.094 S/cm under 0.9 V direct current bias voltage. In addition, the single cell based on 0.2LISZG electrolyte is prepared, and it has been demonstrated that the practical utilization of 0.2LISZG in IT-SOFCs is feasible.     

Structural properties and sensing performance of CeTiO3 ceramic films as a solid-state pH sensor

In this paper, we have studied the impact of postannealing treatment on the structural properties and sensing characteristics of CeTiO₃ ceramic membranes deposited on Si substrate by sputtering for solid-state electrolyte-insulator-semiconductor (EIS) pH sensors. X-ray photoelectron spectroscopy, Auger electron spectroscopy, X-ray diffraction, and atomic force microscopy were used to study the chemical compositions, elemental depth profiles, film structures, and surface morphologies of CeTiO₃ ceramic membranes treated at three rapid thermal annealing (RTA) temperatures of 700, 800 and 900?°C. The sensing performance of the CeTiO₃ ceramic membranes annealed at three different RTA temperatures is strongly correlated to their structural properties. The CeTiO₃ EIS device after RTA at 800?°C exhibited the best sensing characteristics (pH sensitivity, hysteresis voltage and drift rate) among these RTA temperatures. We attribute this behavior to the optimal RTA temperature enhancing the Ce³⁺/Ce⁴⁺ ratio of CeTiO₃ ceramic membrane, reducing an interfacial layer at the CeTiO₃-Si interface, and increasing its surface roughness.     

An investigation on the microstructural and electrical properties of La0.85DxSr0.15–xGa0.8Mg0.2O2.825 (D = Ba and Ca) electrolytes in solid oxide fuel cells

La_0.85D_xSr_0.15–xGa_0.8Mg_0.2O_2.825 (D = Ba and Ca, x?=?0, 0.01, 0.03, 0.05, and 0.07) electrolytes were synthesized using a solid-state reaction method, calcined at 1400?°C for 5?h, and sintered at 1400?°C for 5?h. The microstructures, electrical properties, and cell performances of the electrolytes and fuel cells were analyzed by X-ray diffraction, scanning electron microscopy, impedance analysis, and electrochemical analysis. La_0.85Ba_xSr_0.15–xGa_0.8Mg_0.2O_2.825 (LBSGM) and La_0.85Ca_xSr_0.15–xGa_0.8Mg_0.2O_2.825 (LCSGM) exhibit a dense structure and a cubic perovskite phase. Further, they contain small amounts of a secondary phase. The lattice constants of LBSGM and LCSGM are 0.3913–0.3914?nm and 0.3906–0.3909?nm, respectively. The average grain size of the sample increases with increasing Ba²⁺ or Ca²⁺ content. The conductivity of LCSGM (0.197–0.174?S/cm) is usually higher than that of LBSGM (0.181–0.162?S/cm) at 800?°C. The cells with La_0.85Sr_0.15Ga_0.8Mg_0.2O_2.825 and La_0.85Ca_0.03Sr_0.12Ga_0.8Mg_0.2O_2.825 electrolytes exhibit high open-circuit voltages and maximum power densities of 0.96?V and 542?mW/cm² and 0.94?V and 567?mW/cm², respectively, at 800?°C.     

Structural,electrochemical and catalytic activity of Prussian blue analogues embedded with functionalized carbon for solid state battery applications

The nanoparticles of Mn_1.5[Cr(CN)₆]∙mH₂O@Ni_1.5[Cr(CN)₆]∙nH₂O core-shell prussian blue analogues (PBA) embedded with carbon additives (PBA-C) were synthesized and characterized as electrode material for solid state battery application. The impedance spectroscopy and cyclic voltametry were used to study the electrochemical properties by adding functionalized carbon in 1:1 proportion to improve the electrical performance. The value of room temperature electrical conductivity of core-shell PBA and core-shell nanoparticles mixed with vulcan carbon (PBA-C) are found to be 1.574 × 10⁻³ and 1.92 × 10⁻³ Scm⁻¹_, respectively. Using Li₇La₃Zr₂O₁₂ (LZZO) electrolyte, single cell was fabricated with PBA-C material, and studied its charging-discharging cycles, which exhibits higher current density with stable performance for 400 cycles for time slots of 400 min. The study reveals that the PBA core-shell nanoparticles mixed with carbon (PBA-C) may be a potential candidate as an electrode material in the form of a single cell using LZZO electrolyte.     

Influence of sintering temperature on ion dynamics of Na0.5Bi0.5TiO3-δ: Suitability as an electrolyte material for SOFC

Sodium bismuth titanate samples with different morphology were synthesized via varying the sintering temperature from 1000 to 1150 °C. The conductivity was significantly affected with the morphology of the system. The dynamics of ions was understood from the conductivity spectra. The dc conductivity, hopping frequency and exponent values were extracted from the conductivity spectra analysis. The impedance and modulus spectroscopy along with exponent behaviour suggested short range hopping for the sample sintered at 1000 °C and followed Ghosh scaling instead of Summerfield scaling. While long-range hopping was observed for the samples sintered at 1150 °C and it followed both the Summerfield scaling and Ghosh scaling. Moreover, the stability of the sample is checked in reducing atmosphere.     

Electrolyte flow optimization and performance metrics analysis of vanadium redox flow battery for large-scale stationary energy storage

Vanadium redox flow battery (VRFB) is the best choice for large-scale stationary energy storage, but its low energy density affects its overall performance and restricts its development. In order to improve the performance of VRFB, a new type of spiral flow field is proposed, and a multi-physics coupling model and performance metrics evaluation system are established to explore the electrolyte distribution characteristics. The results show that the new spiral flow field can effectively improve the uniformity of electrolyte flow and alleviate the phenomenon of local concentration polarization as compared with the traditional serpentine flow field and parallel flow field. Due to the long flow channel and large pressure drop, the system efficiency is low. However, coulombic efficiency, voltage efficiency and energy efficiency are significantly better than the traditional flow fields. Therefore, the novel flow field has obvious advantages in the application of small stacks.     

Construction of CO3O4 derived ZIF/GO electrode for outstanding stability in supercapacitors devices

The growing global demand for energy supply and environmental protection has led to the use of high-efficiency energy storage devices, which supercapacitors are used as one of these devices with high storage capacity and exceptional stability. To be used for this purpose, an easy and rapid synthetically method was used to produce the CO₃O₄/GO nanocomposite, and its electrochemical performance as the electrode material in hybrid-supercapacitors was further investigated. In this nanocomposite, the CO₃O₄ crystals with less than 500 nm particle size are uniformly in contact with the wrinkled GO sheets, that their structure and morphology were investigated by surface analyzes. In addition, the functional groups, crystallographic properties, and elemental composition were investigated using the FTIR, XRD, and EDX analyzes. To confirm the supercapacitive effectiveness of the prepared samples, the electrochemical measurements (EIS, CV, and GCD) were done. The results have shown that the values of specific capacity, energy and power densities of Co₃O₄/GO hybrid nanocomposite are 234 mAh g^?1, 16.075 W h kg^?1 and 251 W kg^?1, respectively. Also, the Co₃O₄/GO has the lowest amount of resistance compared to other electrodes. Nearly constant efficiency at 104% after 1000 cycles indicates that the nanocomposite has excellent cyclic stability. The proper electrochemical efficiency of the nanocomposite corresponds to the synergistic effect on the composition.     

Multi-criteria decision-making approach assisting to select materials for low-temperature solid oxide fuel cell: Electrolyte,cathode& anode

Solid Oxide Fuel Cells (SOFCs) have been emerged as a viable technology to convert chemical energy of fuels to electrical energy efficiently and environmentally friendly. However, some issues hinder the successful implementation of SOFC in industrial scales, such as elevated operating temperature, electrochemical stability, high costs associated with materials and interconnectors. To facilitate SOFCs commercialization, Low Temperature-SOFC (LT-SOFC) technology has been introduced. Various materials for core components of the LT-SOFC have been suggested and their performances are investigated. However, operating LT-SOFC faces challenges such as low ionic conductivity of electrolytes and slow rate of the oxygen reduction reaction. These obstacles can be overcome by selecting appropriate alternative materials that can conduct tasks preferably. Since assessing choices demands multiple measures, conducting a multi-criteria decision-making approach is inevitable. In this study, the Analytical Hierarchy Process is used to evaluate criteria and different options as alternatives for the main constituents of an LT-SOFC.     

涡轮叶片气膜冷却孔电解加工气液两相流场特性分析

以高温镍基合金Inconel718为基材进行气膜冷却孔电解加工基础试验,在电解加工过程中,阴极反应界面析出氢气,导致电解液的电导率不再是一个常数,从而影响冷却孔的加工成型精度。结合前期基础试验,建立冷却孔电解加工流道二维模型,基于COMSOL Multiphysics软件对冷却孔端面间隙内气液两相流场进行仿真,研究加工电压、电解液入口压力及管电极进给速度对氢气析出量的影响,并定性地分析电解加工过程中气泡率与电导率之间的关系。由仿真结果可知:氢气的体积分数随加工电压和电极进给速度的增大而增大,随电解液入口压力的增大而减小,且氢气体积分数越大,电解液的电导率越小。     

等离子喷涂-物理气相沉积制备7YSZ纳米结构固体氧化物燃料电池电解质层

氧化钇稳定的氧化锆（YSZ）因其高热稳定性和良好的氧离子电导率被广泛地作为电解质材料应用于固体氧化物燃料电池（SOFC）。常规的平面SOFC电解质制备技术,如带式流延或丝网印刷,需要在1300℃以上的温度下进行烧结,因此采用传统制备技术获得纳米结构电解质层是一个挑战。等离子喷涂-物理气相沉积（PS-PVD）作为一种新技术由于可以实现气相沉积可以提供快速、低成本的方法来制备纳米致密结构电解质层,可避免传统技术在长时间高温烧结引起的材料晶体结构变化以及相邻电极材料间的化学反应。PS-PVD技术具有与传统大气等离子喷涂（APS）完全不同的沉积机制。本研究采用该技术成功地制备了致密的纳米结构7YSZ薄电解质层。当电解质层厚度为8.7～12.3 μm时,其泄露率为2.24～2.29 10-8 cm4gf-1s-1.