共查询到20条相似文献,搜索用时 31 毫秒
1.
《Electrochemistry communications》2003,5(7):579-583
We have developed a novel electrochemical route to fabricate highly ordered stoichiometric Ag2Se nanowire arrays by electrodeposition from non-aqueous dimethyl sulfoxide (DMSO) solutions. Cyclic voltammetry technique was used to study this cathodic deposition process. X-ray energy dispersion analysis shows that stoichiometric Ag2Se nanowires can be obtained in a wide range of deposition condition. X-ray diffraction and electron diffraction patterns demonstrate that the as-deposited nanowires are [0 0 2] oriented orthorhombic β-Ag2Se. Furthermore, ternary Ag2Se1 − xTex nanowires have been electrodeposited in mixed SeCl4–TeCl4 DMSO solutions. 相似文献
2.
《Electrochemistry communications》2008,10(11):1724-1727
MnO2 nanowires were electrodeposited onto carbon nanotube (CNT) paper by a cyclic voltammetric technique. The as-prepared MnO2 nanowire/CNT composite paper (MNCCP) can be used as a flexible electrode for electrochemical supercapacitors. Electrochemical measurements showed that the MNCCP electrode displayed specific capacitances as high as 167.5 F g−1 at a current density of 77 mA g−1. After 3000 cycles, the composite paper can retain more than 88% of initial capacitance, showing good cyclability. The CNT paper in the composite acted as a good conductive and active substrate for flexible electrodes in supercapacitors, and the nanowire structure of the MnO2 could facilitate the contact of the electrolyte with the active materials, and thus increase the capacitance. 相似文献
3.
《Electrochemistry communications》2007,9(4):787-795
Transition metal oxides with composite xLi2MnO3 · (1 − x)LiMO2 rocksalt structures (M = Mn, Ni, Co) are of interest as a new generation of cathode materials for high energy density lithium-ion batteries. After electrochemical activation to 4.6 or 4.8 V (vs. Li0) at 50 °C, xLi2MnO3 · (1 − x)LiMn0.33Ni0.33Co0.33O2 (x = 0.5, 0.7) electrodes deliver initial discharge capacities (>300 mAh/g) at a low current rate (0.05 mA/cm2) that exceed the theoretical values for lithiation back to the rocksalt stoichiometry (240–260 mAh/g), at least during the early charge/discharge cycles of the cells. Attention is drawn to previous reports of similar, but unaccounted and unexplained anomalous behavior of these types of electrode materials. Possible reasons for this anomalous capacity are suggested. Indications are that electrodes in which M = Mn, Ni and Co do not cycle with the same stability at 50 °C as those without cobalt. 相似文献
4.
The galvanic exchange between Mn2 + ions and electrodeposited porous PbO2 was studied to produce a porous oxide whose lower conductivity prevented its direct oxygen bubble-templated anodic deposition. Immersion of PbO2 layers in acid acetate solutions of Mn2 + led to the formation of amorphous MnOx shell onto PbO2. Due to its amorphous nature, MnOx could not be proved to be MnO2 by XRD. However, MnOx was cathodically stripped at the same potential as MnO2. The deposition of the MnOx shell onto PbO2 enhanced the capacity of the porous electrodes. 相似文献
5.
Layered perovskite-structure oxides LaBaCuFeO5+x (LBCFO) and LaBaCuCoO5+x (LBCCO) were prepared and the electrical conductivity and electrochemical performance were investigated as potential cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The electrical conductivity of LBCCO is much higher than that of LBCFO. Area specific resistances of LBCFO and LBCCO cathode materials on Ce0.8Sm0.2O1.9 (SDC) electrolyte are as low as 0.21 Ω cm2 and 0.11 Ω cm2 at 700 °C, respectively. The maximum power density of the LBCFO/SDC/Ni-SDC and LBCCO/SDC/Ni-SDC cells with 300 μm thick electrolytes attains 557 mW cm?2 and 603 mW cm?2 at 800 oC, respectively. Preliminary results demonstrated that the layered perovskite-structure oxides LBCFO and LBCCO are very promising cathode materials for application in IT-SOFCs. 相似文献
6.
《Electrochemistry communications》2007,9(10):2596-2600
Poly (neutral red) nanowires (PNRNWs) have been synthesized for the first time by the method of cyclic voltammetric electrodeposition using porous anodic aluminum oxide (AAO) template and were examined by scanning electron microscopy (SEM) and transmission electron microscope (TEM). Moreover, horseradish peroxidase (HRP) was encapsulated in situ in PNRNWs (denoted as PNRNWs–HRP) by electrochemical copolymerization for potential biosensor applications. The PNRNWs showed excellent efficiency of electron transfer between the HRP and the glassy carbon (GC) electrode for the reduction of H2O2 and the PNRNWs–HRP modified GC electrode showed to be excellent amperometric sensors for H2O2 at −0.1 V with a linear response range of 1 μM to 8 mM with a correlation coefficient of 0.996. The detection limit (S/N = 3) and the response time were determined to be 1 μM and <5 s and the high sensitivity is up to 318 μA mM−1 cm−2. 相似文献
7.
《Electrochemistry communications》2007,9(2):262-268
A series of lithium–manganese–nickel-oxide compositions that can be represented in three-component notation, xLi[Mn1.5Ni0.5]O4 · (1 − x){Li2MnO3 · Li(Mn0.5Ni0.5)O2}, in which a spinel component, Li[Mn1.5Ni0.5]O4, and two layered components, Li2MnO3 and Li(Mn0.5Ni0.5)O2, are structurally integrated in a highly complex manner, have been evaluated as electrodes in lithium cells for x = 1, 0.75, 0.50, 0.25 and 0. In this series of compounds, which is defined by the Li[Mn1.5Ni0.5]O4–{Li2MnO3 · Li(Mn0.5Ni0.5)O2} tie-line in the Li[Mn1.5Ni0.5]O4–Li2MnO3–Li(Mn0.5Ni0.5)O2 phase diagram, the Mn:Ni ratio in the spinel and the combined layered Li2MnO3 · Li(Mn0.5Ni0.5)O2 components is always 3:1. Powder X-ray diffraction patterns of the end members and the electrochemical profiles of cells with these electrodes are consistent with those expected for the spinel Li[Mn1.5Ni0.5]O4 (x = 1) and for ‘composite’ Li2MnO3 · Li(Mn0.5Ni0.5)O2 layered electrode structures (x = 0). Electrodes with intermediate values of x exhibit both spinel and layered character and yield extremely high capacities, reaching more than 250 mA h/g with good cycling stability between 2.0 V and 4.95 V vs. Li° at a current rate of 0.1 mA/cm2. 相似文献
8.
Ti@MoOx core–shell nanorod arrays with diameters within 100 nm were fabricated by electrodepositing MoOx on a Ti nanorod array prepared by oblique angle deposition. A high areal capacitance of 27 mF cm− 2 and satisfactory cycling stability were obtained. After post-annealing, MoO2 grains were introduced to enhance the rate capability, suggesting a potential pseudocapacitive micro-electrode. 相似文献
9.
In the series La2/3?xTbxCa1/3MnO3, it is known that the compositions are ferromagnetic for smaller values of x and show spin glass characteristics at larger values of x. Our studies on the magnetic properties of various compositions in the La2/3?xTbxCa1/3MnO3 series show that the cross over from ferromagnetic to spin glass region takes place above x ≈ 1/8. Also, a low temperature anomaly at 30 K, observed in the ac susceptibility curves, disappears for compositions above this critical value of x. A mixed phase region coexists in the narrow compositional range 0.1 ≤ x ≤ 0.125, indicating that the ferromagnetic to spin glass cross over is not abrupt. 相似文献
10.
Kuang-Tsin Lee Chung-Bo Tsai Wen-Hsien Ho Nae-Lih Wu 《Electrochemistry communications》2010,12(7):886-889
One common dilemma encountered in designing a supercapacitor electrode is that the specific capacitance (Cs) of the active material decreases significantly as the active-material loading (mass area? 1) increases. As a result, the geometric capacitance density (GCD; Farad area? 1) of the electrode does not scale up linearly but gradually levels off with increasing loading. For MnO2 supercapacitors, this problem has been solved to a great extent by introducing a superabsorbent polymer (SAP) binder, namely polyacrylic acid (PAA), to form composite particles with MnO2. Other than acting as a binder to bound together MnO2 particles, the SAP is believed to facilitate distribution of electrolyte throughout the active layer owing to its electrolyte-absorbing and swelling behaviors. The Cs of MnO2 remains almost unchanged as the oxide loading varies over a wide range (1.5–6.5 mg cm? 2) of heavy active-material loading. In addition, putting PAA throughout the entire active layer helps to magnify the specific interaction between PAA and MnO2 that is known to enhance the capacitance of individual MnO2 particles. The success in combining both high Cs and high active-material loading results in GCD of ca. 1.8–1.4 F cm? 2 even under very high current densities (ca. 35–260 mA cm? 2 or 5–40 A g? 1-MnO2). 相似文献
11.
Chunhua Zhao Renzhu Liu Shaorong Wang Tinglian Wen 《Electrochemistry communications》2009,11(4):842-845
A large area cathode-supported electrolyte film, comprising porous (La0.8Sr0.2)0.95MnO3 (LSM95) cathode substrate, LSM95/Zr0.89Sc0.1Ce0.01O2?x (SSZ) cathode active layer, and SSZ electrolyte, has been successfully fabricated by tape casting and co-sintering techniques. The interface reaction between cathode and electrolyte was inhibited by using A-site deficient LSM. A dense enough SSZ thin film with a thickness of ~26 μm was obtained at 1250 °C. By using Pt as anode, the obtained single cell reached the maximum power density of 0.54 W cm?2 at 800 °C in O2/humidified H2, with open circuit voltage (OCV) value of 1.08 V. 相似文献
12.
《Electrochemistry communications》2007,9(6):1282-1287
High capacitance at a high charge–discharge current density of 50 mA/cm2 for a new type of electrochemical supercapacitor cobalt sulfide (CoSx) have been studied for the first time. The CoSx was prepared by a very simply chemical precipitation method. The electrochemical capacitance performance of this compound was investigated by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge–discharge tests with a three-electrode system. The results show that CoSx has excellent electrochemical capacitive characteristic with potential range −0.3 ∼ 0.35 V (versus SCE) in 6 M KOH solution. Charge–discharge behaviors have been observed with the highest specific capacitance values of 475 F/g at the current density of 5 mA/cm2, even at the high current density of 50 mA/cm2, CoSx also shows the high specific capacitance values of 369 F/g. 相似文献
13.
We observed the Raman spectra of carriers, positive polarons and bipolarons, generated in a poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT-C14) film by FeCl3 vapor doping. Electrical conductivity and Raman measurements indicate that the dominant carriers in the conducting state were bipolarons. We identified positive polarons and bipolarons generated in an ionic-liquid-gated transistor (ILGT) fabricated with PBTTT-C14 as an active semiconductor and an ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [BMIM][TFSI] as a gate dielectric using Raman spectroscopy. The relationship between the source−drain current (ID) at a constant source−drain voltage (VD) and the gate voltage (VG) was measured. ID increased above −VG = 1.1 V and showed a maximum at −VG = 2.0 V. Positive polarons were formed at the initial stage of electrochemical doping (−VG = 0.8 V). As ID increased, positive bipolarons were formed. Above VG = −2.0 V, bipolarons were dominant. The charge density (n), the doping level (x), and the mobility of the bipolarons were calculated from the electrochemical measurements. The highest mobility (μ) of bipolarons was 0.72 cm2 V−1 s−1 at x = 110 mol%/repeating unit (−VG = 2.0 V), whereas the highest μ of polarons was 4.6 × 10−4 cm2 V−1 s−1 at x = 10 mol%. 相似文献
14.
C.H. Zhao R.Z. Liu L. Shao S.R. Wang T.L. Wen 《Electrochemistry communications》2009,11(12):2300-2303
A cathode-supported electrolyte film was fabricated by tape casting and co-sintering techniques. (La0.8Sr0.2)0.95MnO3 (LSM95), LSM95/Zr0.89Sc0.1Ce0.01O2?x (SSZ), and SSZ were used as materials of cathode substrate, cathode active layer, and electrolyte, respectively. CuO–NiO–SSZ composite anode was deposited on SSZ surface by screen-printing and sintered at 1250 °C for 2 h. The effects of CuO addition to NiO–SSZ anode on the performance of cathode-supported SOFCs were investigated. CuO can effectively improve the sintering activity of NiO–SSZ. The assembled cells were electrochemically characterized with humidified H2 as fuel and O2 as oxidant. With 4 wt.% CuO addition, the ohmic resistance decreased from 3 to 0.46 Ω cm2, and at the same time the polarization resistance decreased from 3.4 to 0.74 Ω cm2. In comparison with the cell without CuO, the maximum power density at 850 °C increased from 0.054 to 0.446 W cm?2 with 4 wt.% CuO addition. 相似文献
15.
An electrochemical study of structurally-integrated xLi2MnO3•(1 −x)LiMn0.5Ni0.5O2 ‘composite’ materials has been undertaken to investigate the stability of electrochemically-activated electrodes at the Li2MnO3-rich end of the Li2MnO3–LiMn0.5Ni0.5O2 tie-line, i.e., for 0.7 ≤ x ≤ 0.95. Excellent performance was observed for x = 0.7 in lithium half-cells; comparable to activated electrodes that have significantly lower values of x and are traditionally the preferred materials of choice. Electrodes with higher manganese content (x ≥ 0.8) showed significantly reduced performance. Implications for stabilizing low-cost, manganese-rich, layered lithium-metal-oxide electrode materials are discussed. 相似文献
16.
Polycrystalline ceramics of 1 ? x[Na0.5Bi0.5TiO3] ? x[BiFeO3] (NBT–BFO) were synthesized by the modified Pechini's method to study their magnetic and magnetoelectric properties. A series of solid solutions exhibiting magnetoelectric output were formed when two iso-structural compounds Na0.5Bi0.5TiO3 (NBT) and BiFeO3 (BFO) were combined. Polarization-electric field hysteresis loops revealed that the maximum polarization (~23 μC/cm2 for x = 0.1) decreased continuously with the increase of BFO content, following a hard doped effect. Piezoelectric charge coefficient (d33) = 41 pC/N was obtained for the ceramics with x = 0.1 and the value continues to decrease with the composition. Magnetic hysteresis loops represent the canted antiferromagnetic nature for x ≤ 0.6 and ferromagnetic-like behavior for the BFO-rich compositions. Magnetoelectric coupling was determined by measuring the magnetoelectric voltage coefficient which is ~12.4 mV/cm-Oe at an ac magnetic field of 10 Oe (1 kHz), for x = 0.1 sample. 相似文献
17.
《Electrochemistry communications》2007,9(1):103-108
The whole range of solid solutions Li(Li(1−x)/3CoxMn(2−2x)/3)O2 (0 ⩽ x ⩽ 1) was firstly synthesized by an aqueous solution method using poly-vinyl alcohol as a synthetic agent to investigate their structure and electrochemical properties. X-ray diffraction results indicated that the synthesized solid solutions showed a single phase without any detectable impurity phase and have a hexagonal structure with some additional peaks caused by monoclinic distortion, especially in the solid solutions with a low Co amount. In the electrochemical examination, the solid solutions in the range between 0.2 ⩽ x ⩽ 0.9 showed higher discharge capacity and better cyclability than LiCoO2 (x = 1) on cycling between 2.0 and 4.6 V with 100 mA g−1 at 25 °C. For example, Li(Li0.2Co0.4Mn0.4)O2 (x = 0.4) exhibited a high discharge capacity of 180 mA h g−1 at the 50th cycle. By synthesizing the solid solution between Li2MnO3 and LiCoO2, the electrochemical properties of the end members were improved. 相似文献
18.
《Electrochemistry communications》2007,9(7):1508-1512
High performance La2−xSrxCuO4−δ (x = 0.1, 0.3, 0.5) cathode materials for intermediate temperature solid oxide fuel cell (IT-SOFCs) were prepared and characterized. The investigation of electrical properties indicated that La1.7Sr0.3CuO4 cathode has low area specific resistance (ASR) of 0.16 Ω cm2 at 700 °C and 1.2 Ω cm2 at 500 °C in air. The rate-limiting step for oxygen reduction reaction on La1.7Sr0.3CuO4 electrode changed with oxygen partial pressure and measurement temperature. La1.7Sr0.3CuO4 cathode exhibits the lowest overpotential of about 100 mV at a current density of 150 mA cm−2 at 700 °C in air. 相似文献
19.
James R. Wilson Anh T. Duong Marcio Gameiro Hsun-Yi Chen Katsuyo Thornton Daniel R. Mumm Scott A. Barnett 《Electrochemistry communications》2009,11(5):1052-1056
Solid oxide fuel cells (SOFCs) are being actively developed world wide for clean and efficient electrical generation from fuels such as natural gas, hydrogen, coal, and gasoline. The cathode in state of the art SOFCs is typically a porous composite of electronically-conducting La1?xSrxMnO3 (LSM) and ionically-conducting Y2O3-stabilized ZrO2 (YSZ) that facilitates the critical oxygen reduction reaction. Here we describe the three-dimensional characterization and quantification of key structural parameters from an LSM-YSZ cathode, using imaging and volume reconstruction based on focused ion beam – scanning electron microscopy. LSM-YSZ-pore three-phase boundaries (TPBs) were identified. Approximately 1/3 of the TPBs were found to be electrochemically inactive, as they were on isolated LSM particles, yielding an active TPB density of 4.9 μm?2. Cathode electrochemical modeling, which included a measured YSZ tortuosity of 3.4, yielded an effective TPB resistance of ≈2.5 × 105 Ω cm at 800 °C. 相似文献
20.
The rate capability of high capacity xLi2MnO3 · (1 ? x)LiMO2 (M = Mn, Ni, Co) electrodes for lithium-ion batteries has been significantly enhanced by stabilizing the electrode surface by reaction with a Li–Ni–PO4 solution, followed by a heat-treatment step. Reversible capacities of 250 mAh/g at a C/11 rate, 225 mAh/g at C/2 and 200 mAh/g at C/1 have been obtained from 0.5Li2MnO3 · 0.5LiNi0.44Co0.25Mn0.31O2 electrodes between 4.6 and 2.0 V. The data bode well for their implementation in batteries that meet the 40-mile range requirement for plug-in hybrid vehicles. 相似文献