Influences of Nd~（3＋） doping on structure and electrochemical performance of layered Li_（1.05）V_3O_8

Nd3+-doped Li1.05V3O8 was synthesized by liquid-state reactions combined calcination.The influences of Nd3+ doping on physical and electrochemical performances of Li1.05V3O8 were investigated using X-ray diffraction (XRD),cyclic voltammograms,a.c.impedance and galvanostatic charge-discharge tests,etc.Results indicated that Nd3+-doped products had well developed crystal structure of layered LiV3O8 and uniform particle size distribution.Nd3+ doping with a proper amount improved the initial discharge capacity,discharge voltage and ion conductivity of the cathode material to some extent.Nd3+ did not participate in the electrochemical reactions and was beneficial to stability of the crystal structure during cycling.     

Influence of Sc^3＋ on LiMn2O4 cathode materials at elevated temperature

Sc^3＋-doped lithium manganese oxides were synthesized by solid-state reaction. The influences of doping element on structure, mean valence of manganese, and electrochemical performances were studied by X-ray diffraction （XRD）, galvanostatic charge-discharge and cyclic voltammetric tests, and also electrochemical impedance spectroscopy （EIS）. XRD tests showed that doped lithium manganese oxides were pure spinel structure without other phases. Redox titration and visible spectrophotometry tests indicated that the mean valence of manganese in doped lithium manganese oxides was higher than that of pure one. LiSc0.02Mn1.9804 remained 92.9% of the initial specific discharge capacity after 50th cycle at a constant current of 50 m/g, and the reversibility of LiSc0.02Mn1.98O4 was improved in comparison with pure LiMn2O4 at 50 ℃. EIS indicated that film deposition on spinel particles was suppressed because of Sc^3＋ doping, and the charge transfer between the surface film and spinel particles with increasing temperature for Sc^3＋-doped materials became easier as compared with undoped one.     

Study on structure and electrochemical properties of the （LaGdMg）Ni3.35-xCoxAl0.15（x=0-2.0） hydrogen storage alloys

Hydrogen storage alloys(LaGdMg)Ni3.35-xCoxAl0.15(x=0,0.1,0.3,0.5,1.0,1.5,2.0) were prepared by induction melting followed by annealing treatment in argon atmosphere.The effects of partly replacing Ni by Co element in(LaGdMg)Ni3.35Al0.15 on the phase structure and electrochemical properties of(LaGdMg)Ni3.35-xCoxAl0.15 alloys were investigated.Structure analysis showed that the alloys consisted of Ce2Ni7-type(Gd2Co7-type),CaCu5-type,Pr5Co19-type,PuNi3-type phase structure.The addition of Co element obviously reduced the contents of CaCu5-type phase and increased the contents of Ce2Ni7-type phase.However,Pr5Co19-type and CaCu5-type phase obviously increased with the high content of Co.Rietveld analysis showed that the c-axis lattice parameters and cell volumes of the component phases increased with increasing Co content.The electrochemical measurements showed that as the Co content increased,the maximum discharge capacity and the cyclic stability of the annealed alloys both first increased then decreased.The(LaGdMg)Ni3.05Co0.3Al0.15 alloy electrode exhibited the maximum discharge capacity(392.92 mAh/g),and the(LaGdMg)Ni1.85Co1.0Al0.15 alloy electrode showed the best cyclic stability(S100=96.1%).     

Effect of rare earth ions doping on properties of LiFePO4/C cathode material

LiFe0.99RE0.01PO4/C cathode material was synthesized by solid-state reaction method using FeC2O4·2H2O, Li2CO3, NH4H2PO4, RE(NO3)3·nH2O as raw materials and glucose as a carbon source. The doping effects of rare earth ions, such as La3+, Ce3+, Nd3+, on the structure and electrochemical properties of LiFePO4/C cathode material were systematically investigated. The as-prepared samples were characterized by means of X-ray diffraction(XRD), scanning electron microscopy(SEM) and particle size analysis. The electrochemical properties were investigated in terms of constant-current charge/discharge cycling tests. The XRD results showed that the rare earth ions doping did not change the olivine structure of LiFePO4, and all the doped samples were of single-phase with high crystallinity. SEM and particle size analysis results showed that the doping of La3+, Ce3+ and Nd3+led to the decrease of particle size. The electrochemical results exhibited that the doping of La3+ and Ce3+ could improve the high-rate capability of LiFePO4/C cathode material, among which, the material doped with 1% Ce3+ exhibited the optimal electrochemical properties, whose specific discharge capacities could reach 128.9, 119.5 and 104.4 mAh/g at 1C, 2C and 5C rates, respectively.     

Synthesis and characterization of the structural and electrochemical properties of Nd-Al codoped amorphous nickel hydroxide

Nd-Al codoped amorphous nickel hydroxide powders were synthesized by microemulsion precipitation method combined with rapid freezing technique.The microstructure of the prepared samples was analyzed with X-ray diffractometer(XRD),scanning electron microscopy(SEM),and Raman spectroscopy.The electrochemical performances of the prepared samples were characterized with charge/discharge test,cyclic voltammetry,and electrochemical impedance spectra.The results showed that the codoping of Nd-Al resulted in more st...     

Electrochemical performance of Gd-Co-Mn alloys

The Gd-Co-Mn alloys with compositions of Gd33.3Co66.7,Gd33.3Mn66.7,Gd22.2Co74.8Mn3 and Gd25Co70Mn5 were prepared and examined by X-ray diffractometer.The electrochemical properties of these alloys such as discharge capacity,cycling performance and high rate dischargeability were investigated by battery testing instruments in alkaline electrolyte.The discharge capacity of Gd22.2Co74.8Mn3 was the highest among these alloys at the same discharge current density,and the maximum value was 376.7 mAh/g discharged at 150 mA/g.The discharge capacities of the alloys Gd33.3Co66.7 and Gd33.3Mn66.7 reached their maxima(about 225 and 325 mAh/g)at discharge current density of 150 mA/g.A comparison of the electrochemical performance of the Gd-Co-Mn alloys revealed that the alloy Gd22.2Co74.8Mn3 possessed better electrochemical performance and had better discharge capacity,cycle stability,while the alloy Gd25Co70Mn5 had a better high rate discharge ability.In general,the electrochemical performance of ternary alloys was better than binary alloys in this case.     

Influence of magnesium on electrochemical properties of RE3-xMgx(Ni0.7Co0.2Mn0.1)9（x=0.5-1.25） alloy electrodes

RE3-xMgx(Ni0.7Co0.2Mn0.1)9 (x=0.5-1.25) alloys were prepared by induction melting and the influence of the partial substitution of RE (where RE stands for La-rich mischmetal) by Mg on the hydrogen storage and electrochemical properties of the alloys were investigated systematically. These alloys mainly consisted of three phases, La(Ni,Mn,Co)5 phase, La2Ni7 phase and Mg2Ni phase. The P-C-T isotherms showed that with Mg content increasing in the alloys, the hydrogen storage capacity first increased and reached the maximum capacity of 1.36 wt.% when x=1.0, and then decreased with x increasing further. Electrochemical studies revealed that the discharge capacity reached the maximum value of 380 mAh/g and the alloy electrode presented better cyclic stability when RE/Mg=2. The high rate discharge ability of the alloy electrodes was also improved by the substitution of Mg for RE. The RE2Mg(Ni0.7Co0.2Mn0.1)9 alloy exhibited better hydrogen absorption kinetics (x=1.0).)     

Effect of cobalt content on electrochemical performance of La-Mg-Ni system （Ce2Ni7-type） electrode alloys

In order to improve the cyclic stability of La-Mg-Ni system （Ce2Ni7-type） alloy electrode, small amount of Co was added in La0.75Mg0.25Ni3.5 alloy. The effect of Co on electrochemical performance and microstructure of the alloys were investigated in detail. XRD results showed that the alloys had multiphase structure composed of （La, Mg）2Ni7, LaNi5 and small amount of LaNi2 phases. The discharge capacity of the alloys first increased and then decreased with increasing Co content. At a discharge current density of 900 mA/g, the HRD of the alloy electrodes increased from 81.3% （x=0） to 89.2 % （x=0.2）, and then reduced to 87.8 % （x=0.6）. After 60 charge/discharge cycles, the capacity retention rate of the alloys enhanced from 52.67% to 61.32%, and the capacity decay rate of the alloys decreased from 2.60 to 2.05 mAh/g per cycle with increasing Co content. The obtained results by XPS and XRD showed that the fundamental reasons for the capacity decay of the La-Mg-Ni system （Ce2Ni7-type） alloy electrodes were corrosion and oxidation as well as passivation of Mg and Lain alkaline solution.     

Long-lasting phosphorescence study on Y_3Al_5O_（12） doped with different concentrations of Ce~（3＋）

Long-lasting phosphorescence (LLP) was observed in Ce-doped Y3Al5O12 phosphors synthesized in reducing atmosphere. The characteristic emission of the 2D-2F5/2 and 2D-2F7/2 transition of Ce3+ in photoluminescence (PL) and LLP spectra was studied. It was interesting that the ratio between the peak areas of 2D-2F5/2 and 2D-2F 7/2 transitions in the PL spectrum was different from the ratio of that in LLP emission spectrum. And the ratios had different change regularities with increased Ce3+ concentration. The p...     

Influence of cerium doping on structure and electrochemical properties of LiNi_(0.5)Mn_(1.5)O_4 cathode materials

Pristine LiNi_(0.5)Mn_(1.5)O_4 and cerium doped LiCe_xNi_(0.5–x)Mn_(1.5)O_4(x=0.005, 0.01, 0.02) cathode materials were synthesized by solid-state method. The effect of Ce doping content on structure and electrochemical properties of LiNi_(0.5)Mn_(1.5)O_4 cathode material was systematically investigated. The samples were characterized by X-ray diffraction(XRD), Fourier transformation infrared spectrometer(FT-IR), scanning electron microscopy(SEM), electrochemical impedance spectroscopy(EIS), cyclic voltammetry(CV) and constant-current charge/discharge tests. The results showed that Ce doping did not change the cubic spinel structure with Fd3m space group, but effectively restrained the formation of Li_xNi_(1–x)O impurity phase. Appropriate Ce doping(x=0.005) could decrease the extent of confusion between lithium ions and transition metal ions, increase the lattice parameter and Ni/Mn disordering degree(Mn~(3+) content). The synergic effects of the above factors led to the optimal electrochemical performance of LiCe_(0.005)Ni_(0.495)Mn_(1.5)O_4 sample. The discharge capacity at 10 C rate could reach 115.4 mAh/g, 94.82% of that at 0.2C rate, and the capacity retention rate after 100 cycles at 1C rate could reach 94.51%. However, heavier Ce doping had an adverse effect on the electrochemical properties, which might be due to the lower disordering degree and existence of more CeO_2 secondary phase.     

Effect of Metal Oxide Doping into Ce0.5Zr0.5O2 on Catalytic Activity of MnOx/γ-Al2O3/Ce0.45Zro.45M0.1Ox （M = Y, La, Mn） Honeycomb Catalysts

This article showed that the catalytic activity of MnOx/γ-Al2O3/Ce0.5Zr0.5O2 monolithic catalyst toward the catalytic combustion of ethanol in a fixed bed reactor could be greatly improved by doping three metal oxides into Ce0.5Zr0.5O2. The catalytic activity of MnOx/γ-Al2O3/Ce0.45Zr0.45M0.1 Ox （M = Y, La, Mn） is better than that of MnOx/γ-Al2O3/Ce0.5 Zr0.5O2. The order of activity of the catalysts is as follows： MnOx/γ-Al2O3/Ce0.45Zr0.45Y0.1Ox 〉 MnOc/γ-Al2O3/Ce0.45 Zr0.45La0.1Ox 〉 MnOx/γT-Al2O3/Ce0.45Zr0.45Mn0.1Ox 〉 MnOx/y-Al2O3/Ce0.5Zr0.5O2. The influence of the loading amount of manganese oxide in enhancing the catalytic activity of MnOx/γ-Al2O3/Ce0.45Zr0.45Y0.1 Ox was investigated. The results showed that when MnO2 loading amount was 10% （mass fraction）, the MnOx/Al2O3/Ce0.45Zr0.45Y0.1Ox catalyst recorded the highest activity.     

Y2O3 modification on nickel-rich LiNi0.8Co0.1Mn0.1O2 with improved electrochemical performance in lithium-ion batteries

Doping and coating are frequently employed for the improvement of the properties of Ni-rich NCM materials.In this work,we prepared stable LiNi_0.8Co_0.1Mn_0.1O₂(NCM811)materials modified withY₂O₃via a wet chemical method.In order to investigate the action mechanism ofY₂O₃on NCM811,we analyzed the micro structures using X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),and transmission electron microscopy(TEM).Also,to study the electrochemical performances,we conducted a charge/discharge test and cyclic voltammetry.Our results show thatY₂O₃modified NCM811 materials have good thermal stability,and proper content ofY₂O₃can effectively prevent the materials from damaging and significantly improve the electrochemical properties of the materials.Particularly,1%Y2 O3 modified NCM811 material show much better cycling performance than other samples.During cycling at 1.0 C the 1%Y2 O3 modified NCM811 shows capacity retention of 90.1%after 100 cycles,which is higher than 69.4%for pristine NMC811.We examined the microstructures of the materials before and after circulation.Using the SEM results,we conclude that structural changes are among the key factors that lead to the degradation of the electrochemical properties of materials.     

Effect of metal doping into Ce0.5Zr0.5O2 on catalytic activity of MnOx/Ce0.5–xZr0.5–xM0.2xOy/Al2O3 for benzene combustion

The research investigated the effect of doping two metals separately or together into Ce0.5Zr0.5O2 on the catalytic activity of MnOx/Ce0.5-xZr0.5-xM0.2xOy/Al2O3 （M=Y, Mn, Y and Mn） for catalytic combustion of benzene. The prepared catalysts were characterized by X-ray diffraction （XRD）, surface area analysis, oxygen storage capacity （OSC）, and H2-temperature programmed reduction （H2-TPR）. Catalytic test was performed on a conventional fixed bed flow reactor. The characterization results revealed that Y and Mn ions entered into the ceria-zirconia mixed oxides framework, which improved the textural properties and greatly promoted the MnOx dispersion on the support surface. The complete conversion temperature of benzene on MnOx/Ce0.4Zr0.4Y0.1Mn0.1Oy/Al2O3 was 563 K, and the selectivity of carbon dioxides was 99%. This catalyst could be applied in a wide range of GHSV and wide concentration condition, showing great potential for application.     

Luminescence properties of a single-host phosphor Bal.8-wSrwLi0.4SiO4： cea＋,Eu2＋,Mn2＋ for WLED

In order to obtain a single-host-white-light phosphor,a series of Ba1.8-w-x-y-zSrwLi0.4-xCexEuyMnzSiO4(BSLS:Ce3+,Eu2+,Mn2+)powder samples were synthesized via high temperature solid-state reaction.The structure and photoluminescence properties were investigated.Under ultraviolet excitation,the emission spectra contained three bands:the 370-470 nm blue band,the 470-570 nm green band and the 570-700 nm red band,which arose from the 5d→4f transitions of Ce3+ and Eu2+,and the 4T1→6A1 transition of Mn2+,respectively.The excitation spectra of the emissions of Ce3+ and Mn2+ ions showed the energy transfer from Ce3+ to Mn2+.White light emission was obtained from the tri-doped samples of appropriate doping concentration under 310-360 nm excitation.     

Effects of annealing on microstructures and electrochemical properties of La0.8Mg0.2Ni2.4Mn0.10Co0.55Al0.10 alloy

The La0.8Mg0.2Ni2.4Mn0.10Co0.55Al0.10 alloy was prepared by induction melting. The structural and morphological characterizations were performed by means of X-ray powder diffraction （XRD） and scanning electron microscopy （SEM）. The electrochemical measurements were performed using LAND and CH/660b electrochemical workstation. The main phases of the alloy were LaNi5 and （La,Mg）Ni3. After annealing, the maximum discharge capacity, cycle stability and high rate dischargeability （HRD） were improved obviously. The maximum discharge capacity reached 373.80 mAh/g （T=1173 K）, the C100/Cmax（%） was 72.63% （T=1173 K）, and the value of HRD reached 51.8% at a discharge current density of 1150 mA/g （T=1173 K）. The cyclic voltammetry （CV） and potentiodynamic polarization were also studied.     

Influence of manganese rate on structural,optical and electrochemical properties of CeO2 thin films deposited by spray pyrolysis: Supercapacitor applications

The present work aimed to investigate the electrochemical properties of ITO substrates in propylene carbonate (PC) with 0.5 mol/L lithium perchlorate (LiClO₄) medium in the presence of elaborated thin films of cerium dioxide pure and doped with manganese at varying percentages. Ce_1–xMn_xO₂ (x = 0 wt%, 2 wt%, 4 wt% and 6 wt%) were successfully deposited by the spray pyrolysis (SP) technique on the glass substrate and ITO at 450 °C. The effects of manganese (Mn) doped thin films Ce_1–xMn_xO₂ were studied and investigated by using different analyses namely X-ray diffraction (XRD) analysis, Raman spectroscopy method, UV–Vis spectrophotometer technique, atomic force microscopy (AFM) analysis and electrochemical properties. XRD data obtained present a polycrystalline with a face-centred cubic structure of fluorite type. Raman results of undoped and Mn doped thin films show two peaks at 465 and 600 cm^?1, due to the formation of extrinsic oxygen vacancies by the incorporation of Mn into Ce_1–xMn_xO₂ matrix. Energy dispersive spectroscopy (EDS) data show the presence of Ce, O, and Mn elements in the elaborated films. The AFM results reveal that the surface roughness decreases with increasing Mn rate. Further, band gap energy of thin films decreases with increasing in Mn rate due to the formation of defect state between valence and conduction band. The storage capacity of the elaborated Ce_1–xMn_xO₂/ITO/PC + LiClO₄ electrode reaches a maximum of 1.997 mF in the presence of 6 wt% of Mn.     

正极材料LiNi1/3Co1/3Mn1/3O2的Mg掺杂及电化学性能

为提高正极材料LiNi_1/3Co_1/3Mn_1/3O₂的循环性能, 采用氢氧化物共沉淀法对前驱体进行Mg掺杂, 再经过混锂、球磨、高温煅烧后, 分别对掺杂与未掺杂的正极材料进行了XRD、SEM及电化学性能的比较.研究结果表明:掺杂与未掺杂的正极材料都为标准的α-NaFeO₂型层状结构, 粒度大小无明显变化; 对于掺杂量为0.03与未掺杂的正极材料, 首轮放电比容量分别为138.2 mAh/g和145.3 mAh/g; 而循环50轮的放电比容量则分别为131.1 mAh/g和119.5 mAh/g.由此可见, 通过Mg掺杂, 正极材料的首轮放电比容量虽有少量降低, 而循环性能却有明显增强.      

Crystal structure,thermal expansion and electrical conductivity of Pr（Ga1-xCox）0.9Mg0.1O3-δ （x=0, 0.1, 0.2, 0.3）

Pr（Ga1-xCox）0.9Mg0.1O3-δ （x=0, 0.1, 0.2, 0.3） was synthesized using solid-state reaction technique to study the effects of Co doping on their structure and properties. Room and high temperature XRD, DSC and electrical conductivity measurement with D.C. four-probe technique were adopted in the study. The results indicated its orthorhombic-distorted perovskite structure at room temperature. PrGa0.9Mg0.1O3-δ maintained its orthorhombic-distorted structure between 298 and 1173 K. For Pr（Ga0.7Co0.3）0.9Mg0.1O3-δ, such structure existed below 873 K. From 873 to 1173 K, it possessed tetragonal structure. The transformation from orthorhombic to tetragonal structure at 873 K was of second order. The intrinsic volume thermal expansion of tetragonal structured Pr（Ga0.7Co0.3）0.9Mg0.1O3-δ Was about 50% higher than those of PrGa0.9Mg0.1O3-δ. The electrical conductivity increased with Co content. The activation energies of conduction for Pr（Ga1-xCox）0.9Mg0.1O3-δ are in range from 0.197 to 0.246 eV, much lower than 1.543 eV for PrGaO3.     

Phase structure and electrochemical properties of non-stoichiometric La0.7Ce0.3(Ni3.65Cu0.75Mn0.35Al0.15(Fe0.43B0.57)0.10)x hydrogen storage alloys

Phase structure and electrochemical characteristics of Co-free La0.7Ce0.3(Ni3.65Cu0.75Mn0.35Al0.15(Fe0.43B0.57)0.10)x (0.90≤x≤1.10) al-loys were investigated. When x was 0.90, the alloy was composed of LaNi5, La3Ni13B2 and Ce2Ni7 phases. The Ce2Ni7 phase disappeared, and the abundant of La3Ni13B2 phase decreased when x increased to 0.95. When x was 1.00 or higher the alloys consisted of LaNi5 phase. The lat-tice parameter a and the cell volume V of the LaNi5 phase decreased, and the c/a ratio of the LaNi5 phase increased with x value increasing. Maximum discharge capacity of the alloy electrodes first increased and then decreased with x value increasing from 0.90 to 1.10, and the highest value was obtained when x was 1.00. High-rate dischargeability at the discharge current density of 1200 mA/g increased from 50.7% (x= 0.90) to 64.1% (x=1.10). Both the charge-transfer reaction at the electrode/electrolyte interface and the hydrogen diffusion in the alloy were responsible for the high-rate dischargeability. Cycling capacity retention rate at 100th cycle (S100) gradually increased from 77.3% (x= 0.90) to 84.6% (x=1.10), which resulted from the increase in Ni content and the c/a ratio of the LaNi5 phase with x value increasing.     

Characterization and electrochemical performance of CeO2 and Eu-doped CeO2 films as a manganese redox flow battery component

Hexagonal CeO_2 and Eu-doped CeO_2 nanoparticles were obtained using a facile microwave-hydro thermal method under mild conditions and their application towards manganese redox flow battery component were studied. The structural properties were studied by X-ray diffraction and indicate that samples present a fluorite structure. Raman spectroscopy shows Eu3+ ions substitute Ce~(4+) and generate oxygen vacancies. Electrochemical properties of pure and Eu-doped CeO_2 films deposited at graphite substrates investigated by cyclic voltammetry and galvanostatic charge—discharge indicate that dopant concentration affects the electrochemical properties of CeO_2. The increase in the reversibility redox of electrochemical systems observed is attributed to coexistence of Ce~(4+)/Ce~(3+) redox couple confirmed by XPS.Charge—discharge tests display coulombic and voltage efficiency values of above 80% and 90%, respectively. The obtained specific capacity for Ce_(0.99)Eu_(0.01)O_2(372.49 mAh/g) and pure oxide(334.84 mAh/g)indicates that both samples are promising for application in Mn-batteries.