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Developing highly efficient, environmentally friendly and cost-effective electrocatalysts for oxygen reduction reactions is crucial for electrochemical energy conversion devices such as metal/air batteries and fuel cells. In this regard, metal-free porous carbons with their high activity, good stability and low cost show promising properties as a candidate for replacing expensive Pt-based electrocatalysts. However, it remains a major challenge to establish a template-free and green method for the synthesis of highly active metal-free carbon materials with outstanding performance over a wide pH range. In this paper, a controllable and scalable method to synthesize porous N-doped carbon nano-foams with interconnected bubble-like structures is presented. These as-prepared N-doped carbon catalysts, which were obtained by spray pyrolization and the subsequent heat treatment in the presence of NH3, possess activities which are well comparable to the commercial Pt/C. In addition, systematic electrochemical analyses were performed with a detailed explanation of the pore formation induced by the activation of Zn and NH3. In brief, this work is of great importance for the development of relevant electrochemical energy devices, particularly fuel cells and metal–air batteries.

Lithium-sulfur (Li S) batteries have been considering as a very promising energy storage system since their high theoretical specific capacity and energy density. Nevertheless, the practical commercialization of Li S batteries is hindered by their poor cycle stability and fast capacity fading. Herein, a carbonized bacterial cellulose/titania (CBC/TiO 2 ) modified separator is designed to restrain the shuttle effect of Li S cells with its strong physical and chemical adsorption of polysulfides. Cells with CBC/TiO 2 modified separator show an initial discharge capacity of 1314 mAh g − 1 at 0.2C, and the capacity retention is 1048.5 mAh g − 1 after 50 cycles. A discharge capacity of 475 mAh g − 1 is obtained after 250 cycles at 2C. And during the rate test, Li S cells can deliver a discharge capacity of 537.1 mAh g − 1 at 2C. The outstanding electrochemical performance of Li S cells with CBC/TiO 2 modified separator shows a new approach for the application of Li S batteries.

Nitrogen-containing hollow carbon microspheres (NHCSs) are prepared by a modified template method in the presence of resorcinol/formaldehyde as carbon precursors and ethylenediamine (EDA) as both a base catalyst and nitrogen precursor. The NHCSs are used as anode materials for sodium-ion batteries, showing a superior reversible discharge capacity of 334 mAh g−1 after 100 cycles at 50 mA g−1. A high reversible discharge capacity of 114 mAh g−1 can also be obtained even at an extremely high current density of 10 A g−1. Moreover, excellent long-term cycling stability (>1200 cycles) is also observed even at 500 mA g−1. The results show that the NHCS electrode exhibits excellent electrochemical performance (superior reversible capacity, high rate capability, and long-term cycling stability). The excellent performance of NHCS electrode is most likely attributed to the unique nitrogen-containing hollow carbon structure. Furthermore, this study provides a novel route to produce NHCSs, which may find application in other fields.

Primary and rechargeable zinc/air batteries could be the next generation of energy storage devices because of their high power density and safety. The activity and durability of the catalyst play an important role in enhancing the electrochemical performance of the battery. Herein, Ni–Co@N-doped porous carbon (NC@NPC) core–shell microspheres are proposed as a bifunctional catalyst which exhibits significantly enhanced onset oxygen reduction reaction (ORR) potential (−0.19 V vs. Ag/AgCl) and oxygen evolution reaction (OER) current density (16.2 mA cm−2 at 0.8 V vs. Ag/AgCl) due to the synergy of metallic Ni and Co. Namely, practical rechargeable NC@NPC loaded zinc/air battery testing using oxygen in air demonstrates desirable discharge voltages at current densities up to 80 mA cm−2. Besides, steady charge and discharge voltages at the current density of 10 mA cm−2 are obtained over 60 cycles.

The corrosion and oxygen evolution behaviors of cast and rolled Pb–Ag–Nd anodes were investigated by metalloscopy, environmental scanning electron microscopy, X-ray diffraction analysis, and various electrochemical measurements. The rolled anode exhibits fewer interdendritic boundaries and a dispersed distribution of Pb–Ag eutectic mixtures and Nd-rich phases in its cross-section. This feature inhibits rapid interdendritic corrosion into the metallic substrate along the interdendritic boundary network. In addition, the anodic layer formed on the rolled anode is more stable toward the electrolyte than that formed on the cast anode, reducing the corrosion of the metallic substrate during current interruption. Hence, the rolled anode has a higher corrosion resistance than the cast anode. However, the rolled anode exhibits a slightly higher anodic potential than the cast anode after 72 h of galvanostatic polarization, consistent with the larger charge transfer resistance. This larger charge transfer resistance may result from the oxygen-evolution reactive sites being blocked by the adsorption of more intermediates and oxygen species at the anodic layer/electrolyte interfaces of the rolled anode than at the interfaces of cast anode.

A novel bimodal porous carbon (BPC) with high surface area was prepared by a simple hydrothermal route and KOH activation process, and the Se–BPC composite was synthesized for lithium–selenium batteries by the melt-diffusion method. It is found that the elemental selenium was dispersed inside the pores of BPC based on the analyses. Electrochemical tests reveal that the Se–BPC composite has a large reversible capacity and high rate performance as cathode materials. The Se–BPC (45.1 wt.% Se) composite displays an initial discharge capacity of 552 mAh g − 1 and a reversible discharge capacity of 264 mAh g − 1 after 80 cycles at 1 C charge/discharge rate. In particular, the Se–BPC composite presents a durable cycling performance at high rate of 2 C. These outstanding electrochemical features of Se–BPC composite cathode should be attributed to the uniform BPC with high surface area and bimodal porous structure. The bimodal porous carbon would be a promising carbon matrix to develop high performance lithium–selenium batteries.

The anodic layer and oxygen evolution behavior of Pb–Ag–Nd alloy during pulse current polarization and constant current polarization in 160 g/L H 2 SO 4 solution was comparatively investigated by chronopotentiometry, SEM, XRD, EIS and Tafel techniques. The results show that the anodic layer on Pb–Ag–Nd alloy formed through pulse current polarization is more intact and presents fewer micro-holes than that formed through constant current polarization. This could be attributed to the low current density period, which works as a ‘recovery period’. During this period, the oxygen evolution reaction is less intense, which benefits the recovery of porous anodic layer. Pb–Ag–Nd anode also shows a lower anodic potential during pulse current polarization, which is in accordance with its smaller charge transfer resistance and smaller Tafel slope coefficient at high over-potential region. The lower anodic potential could be ascribed to the higher concentration of PbO 2 in the anodic layer, which promotes the formation of more reactive sites for the oxygen evolution reaction.

A novel highly ordered nitrogen-rich mesoporous carbon (HNMC) was prepared by pyrolysis of biomass waste (gelatin) and a simple template process, and sulfur–HNMC composite based on HNMC was synthesized for lithium–sulfur batteries by a melt-diffusion method. It is found that the elemental sulfur was homogeneously dispersed inside the meso-pores of HNMC based on the analyses. Electrochemical tests reveal that the sulfur–HNMC (53.3 wt% sulfur) composite shows high rate capability and long cycling stability as cathode materials. The sulfur–HNMC (53.3 wt% sulfur) composite cathode exhibits a high initial discharge capacity of 1209 mAh g −1 and retains as high as 600 mAh g −1 after 200 cycles at 1 C. Moreover, the cathode also presents a long term cycling stability up to 300 cycles even at 3 C. The results illustrate that the high rate capability and long term cycling stability of sulfur cathode can be enhanced significantly by encapsulating sulfur into the highly ordered nitrogen-rich mesoporous carbon nanostructure, and the HNMC nanostructure would be a promising carbon matrix for high-performance lithium–sulfur batteries.

Fluorinated ether of ethyl 1,1,2,2-tetrafluoroethyl ether (ETFE) was selected as electrolyte solvent for lithium/sulfur battery, and the influence of ETFE in electrolyte on cell properties was first investigated. The enhanced stability of electrolyte/anode interface and improved electrochemical performances (cycling, rate and self-discharging) of the Li/S cell are presented by using ETFE-containing electrolyte, especially for complete replacement of tetraethylene glycol dimethyl ether (TEGDME) by ETFE in combine with 1,3-dioxolane (DOL). It is found that ETFE plays a key role in modifying the surface composition and structure of the metallic Li, forming a strengthened protective film on the anode during cycling. Besides, ETFE is considered to decrease the dissolution of polysulfides in the electrolyte. These factors together restrict the contact and reaction between polysulfides and Li anode.

In this paper, nano-lead-doped active carbon (nano-Pb/AC) composite with low hydrogen evolution current for lead-acid battery was prepared by ultrasonic-absorption and chemical-precipitate method. The nano-Pb/AC composite was characterized by SEM, EDS and TEM. The electrochemical characterizations are performed by linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) in a three-electrode system. Since intermediate adsorption is the rate-determining step, the hydrogen evolution reaction (HER) is markedly inhibited as the intermediate adsorption impedance of nano-Pb/AC increased. Meanwhile, the working potential of nano-Pb/AC is widened to the whole potential region of Pb negative plate (from −1.36 V to −0.86 V vs. Hg/HgSO4) in lead-acid battery. In addition, nano-Pb can improve the interfacial compatibility between AC and Pb paste, accordingly relieve the symptoms of carbon floatation. Finally, 2.0 V single-cell flooded lead-acid batteries with 1.0 wt.% nano-Pb/AC or 1.0 wt.% AC addition in negative active materials are assembled. The cell performances test results show that the 3 h rate capacity, quick charging performance, high current discharging performance and cycling performance of nano-Pb/AC modified battery are all improved compared with regular lead-acid battery and AC modified lead-acid battery.

The enhancement of Ga incorporation into the CIGS thin film by electrodeposition has been realized. One-step electrodeposition Cu(In,Ga)Se 2 thin films under different hydrogen peroxide (H 2 O 2 ) concentrations was investigated. The ratio Ga/(In + Ga) and characteristics of thin films were further modulated by adding H 2 O 2 into electrolyte. The mechanism of the effects of H 2 O 2 on electrodeposition Cu(In,Ga)Se 2 thin films was illustrated using a schematic diagram. And this mechanism was proved by cyclic voltammograms, potentiostatic polarization, energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and Raman spectra. The films were found to have the same basic chalcopyrite structure of CuInSe 2 , and have the widen band gap (UV-VIS-NIR spectrophotometer) after adding H 2 O 2 into the electrolyte. The evidence of Ga incorporation increment can be observed from the peak shift of Raman spectra and widen band gap.

Sulfur has a high specific capacity of 1675 mAh g −1 as lithium battery cathode, but its rapid capacity fading due to polysulfides dissolution presents a significant challenge for practical applications. Here we report a novel hierarchical porous honeycomb carbon (HPHC) for lithium-sulfur battery cathode with effective trapping of polysulfides. The HPHC was prepared by a simple template process, and a sulfur-carbon composite based on HPHC was synthesized for lithium-sulfur batteries by a melt-diffusion method. It is found that the elemental sulfur was dispersed inside the three-dimensionally hierarchical pores of HPHC based on the analyses. Electrochemical tests reveal that the sulfur-HPHC composite shows high rate capability and long cycling stability as cathode materials. The sulfur-HPHC composite with sulfur content of 66.3 wt% displays an initial discharge capacity of 923 mAh g −1 and a reversible discharge capacity of 564 mAh g −1 after 100 cycles at 2 C charge-discharge rate. In particular, the sulfur-HPHC composite presents a long term cycling stability up to 300 cycles at 1.5 C. The results illustrate that the electrochemical reaction constrained inside the interconnected macro/meso/micropores of HPHC would be the dominant factor for the excellent high rate capability and long cycling stability of the sulfur cathode, and the three-dimensionally honeycomb carbon network would be a promising carbon matrix structure for lithium-sulfur battery cathode.

In this paper, a lightweight Pb plated Al (Al/Pb) grid was prepared by molten salt electroless plating. The SEM and bonding strength test show that the lead coating is deposited with a smooth surface and firm combination. CV test shows that the electrochemical properties of Al/Pb electrodes are stable. 2.0 V single-cell flooded lead-acid batteries with Al/Pb grids as negative collectors are assembled and the performances including 20 h capacity, rate capacity, cycle life, internal resistance are investigated. The results show that the cycle life of Al/Pb-grid cells is about 475 cycles and can meet the requirement of lead-acid batteries. Al/Pb grids are conducive to the refinement of PbSO 4 grain, and thereby reduce the internal resistance of battery and advance the utilization of active mass. Moreover, weight of Al/Pb grid is only 55.4% of the conventional-grid. In this way, mass specific capacity of Al/Pb-grid negatives is 17.8% higher and the utilization of active mass is 6.5% higher than conventional-grid negatives.

Based on the basic principles of kinetics and some reasonable assumptions about the electrodeposition process, a dynamic model for metal selenide electrodeposition (kink site selected model) was constructed. This model is of universal significance in realizing the compositional prediction and dynamic behavior analysis of deposited films for different main salt concentration ratios and was applied to the ternary Cu–In–Se system. For CuInSe2 electrodeposition, in the Cu–Se system, the co-deposition of Cu and Se can be carried out within a large range of main salt concentration ratio; in the Cu–In system, the mole fraction of Cu in deposited thin films is always higher than that of Cu2+ in electrolyte, while in the In–Se system, the co-deposition of In and Se can be achieved only when the In3+ concentration is much higher than the H2SeO3 concentration. As for the compositional estimation of CuInSe2, the predictive results of our dynamic model agree well with the experimental data. It is then found that by correcting the difference of kink site selectivity constants caused by the change of deposition potential, the error of the predictive results can be reduced.

A novel idea to inhibit the hydrogen evolution in activated carbon (AC) application in a lead-acid battery has been presented in this paper. Nitrogen group-enriched AC (NAC, mainly exists as pyrrole N) was prepared. Electrochemical measurements demonstrate that the hydrogen evolution reaction (HER) is markedly inhibited as the HER impedance increases significantly. What's more, the specific capacitance value of NAC is 142.5% higher than AC since the working window is extended. The use of NAC, instead of AC in an UltraBattery, can inhibit hydrogen evolution, and improve the battery's charge acceptance and charge retention ability.

The reaction current density is an important process parameter of lithium-ion battery, significantly influencing its electrochemical performance. In this study, aimed at the discharge process of lithium-ion power battery, an electrochemical-thermal model was established to analyze the distribution of the reaction current density at various parts of the cathode and its evolution with the time of discharge, and to probe into the causes of distribution and evolution. The investigation revealed that the electrochemical-thermal coupled model showed more accurate compared to the single electrochemical model, which was more obvious in high rate discharge. The results demonstrated that the conductivity of solid and liquid-phases was an important factor affecting the distribution of the reaction current density. Moreover, the uniformity of the distribution of the current density was related to the rate of utilization of the active materials in the electrodes. By optimizing the porosity and thickness of the electrode, not only the distribution of the current density was improved, but also the rate of utilization of the active materials in the electrodes and the energy density of batteries were significantly enhanced. © 2014 The Electrochemical Society. [DOI: 10.1149/2.004408jes] All rights reserved.

18650-type lithium iron phosphate/graphite cells are cycled at 25 and 55 °C in order to investigate cycle performance and diagnostics for capacity fading. The cell losses more than 30 % of its initial capacity after 600 cycles when cycled at 55 °C compared to a 5 % loss for the cell cycled at 25 °C. There is no evident difference appeared between cathode and anode capacities before and after cycling, but only part of the cathode capacity could be recovered on the first charge after cycling. The loss of cycleable lithium is supposed to be the reason for the capacity fade. And both catalytic reaction of iron deposited on graphite surface and damage of solid–electrolyte interface layer by volume change play important roles in capacity fade.

CuSbSe 2 thin films have been prepared by electrodeposition followed by rapid thermal annealing. Cyclic voltammetry tests were firstly used to investigate the electrodeposition mechanism. The most suitable deposition potential for films preparation was determined to be about −0.40 V vs. SCE combining with cyclic voltammetry, composition and morphology analysis. Polycrystalline films with the main phase of CuSbSe 2 and secondary phase Sb 2 Se 3 were obtained after rapid thermal annealing for both Cu-rich and Cu-poor thin films. Both films show an optical band gap value of about 1.09 eV. Photoelectrochemical (PEC) characterizations indicate that Cu-poor thin film has the better photoelectrical properties than those of Cu-rich thin film.

Antimony selenide thin films have been prepared onto tin oxide coated glass substrates by potentiostatic electrodeposition from an aqueous acid bath containing K(SbO)C4H4O6⋅0.5H2O and H2SeO3 at 25 °C. The electrodeposition mechanism was investigated by cyclic voltammetry. The compositional, morphological, structural, optical, and electrical properties of the deposited films have been studied using energy-dispersive X-ray spectroscopy (EDS), environmental scanning electron microscopy (ESEM), Raman spectroscopy (RS), UV–VIS spectra, and photoelectrochemical tests (PEC), respectively. The formation of antimony selenide was confirmed to proceed via an induced codeposition mechanism: Se deposition occurs first, inducing the deposition of Sb, then, the deposited Sb would further promote the deposition of Se. The influence of deposition potential on the composition, morphology, and structure of the antimony selenide thin films was also explored. Sb2Se3 thin films with homogeneous morphology and near stoichiometric composition can be obtained, and exhibit good optical properties with absorption coefficient of higher than 105 cm−1 and band gap of 1.07 ± 0.01 eV, as well as electrical properties with p-type conductivity and excellent photoelectrochemical activity.

The oxygen evolution kinetics and anodic layer properties of Pb/Pb–MnO 2 composite anode during the 72 h galvanostatic electrolysis in H 2 SO 4 solution were investigated with Quasi-stationary polarization (Tafel) and Electrochemical Impedance Spectroscopy (EIS) techniques. The results revealed that the anodic activity and reaction kinetics varied a lot during the electrolysis for it is a process indicating the formation and stabilization of anodic layer. At the very beginning of electrolysis, the composite anode exhibited very high oxygen evolution activity since the reaction was controlled by the transformation step of intermediates. Then, its oxygen evolution activity was largely diminished and the rate determination step ( rds ) became the formation and adsorption of first intermediate, S–OH ads . In the prolonged electrolysis, the anodic potential gradually decreased and the final stable value was comparable to industrial Pb–Ag (1.0%) anode. On the stable anodic layer after 72 h, the oxygen evolution reaction (OER) was still controlled by the formation and adsorption of intermediate, and the adsorption resistance took a dominant part in the whole impedance. Besides, compared with Pb–Ag and Pb anode, although OER at the stable state were all controlled by the intermediate adsorption process, the adsorption resistance of Pb/Pb–MnO 2 anode was much smaller than the other two due to the existence of MnO 2 particles and large amount of β-PbO 2 in the stable anodic layer.

The influence of Mn2+ on oxygen evolution kinetics and corrosion behaviour of Pb/Pb-MnO2 composite anode in sulfuric acid electrolyte was investigated using SEM, XRD, and several electrochemical methods. The results indicate that a high concentration of Mn2+ (e.g. 3.0 g L− 1) in the electrolyte resulted in the formation of a MnO2 layer on the surface of the anode. This layer decreased the oxygen evolution activity of the anode, but at the same time made the underlying PbO2 layer more compact and flat, effectively improving the anodic corrosion resistance. When the Mn2+ concentration was low (e.g. 0.1 g L− 1), no MnO2 layer was formed but the structure of the PbO2 anodic layer was modified. As a result, the oxygen evolution activity and corrosion resistance were both significantly improved. In addition, Mn2+ in the electrolyte did not change the kinetic mechanism of oxygen evolution reaction. The reaction was exclusively controlled by the formation and adsorption of first intermediate, and the adsorption resistance played a dominant part in the whole reaction resistance.

Bi-doped antimony selenide (Sb 2− x Bi x Se 3 ) thin films have been prepared by potentiostatical electrodeposition and post annealing treatment. Cyclic voltammetry (CV) was used to investigate the electrochemical behaviors of electrodeposition. The suitable deposition potential for film preparation was determined to be about −0.40 V vs. SCE combining with CV, energy dispersive X-ray spectroscopy (EDS), environmental scanning electron microscope (ESEM) studies. After annealing, film shows improved crystallinity and a basic orthorhombic Sb 2 Se 3 structure but having a larger d-spacing due to the substitution of Bi for Sb in Sb 2 Se 3 lattice. The annealed film exhibits an absorption coefficient of larger than 10 5 cm −1 in the visible region, an direct optical band gap of 1.12 ± 0.01 eV, the n-type conductivity, an carrier concentration of 1.1 × 10 19 cm −3 and an flat band potential of −0.40 ± 0.03 V vs. SCE.

Difluoro(oxalato)borate (ODFB − ) is a less symmetric borate anion, which makes it possible to increase the solubility of tetraethylammonium (TEA + ) salt in propylene carbonate (PC) and improve the capacitance of electrochemical double-layer capacitors (EDLCs). The use of TEAODFB with PC solvent in EDLCs was investigated in the paper. The results show that TEAODFB has good solubility in PC, and the conductivity is comparable to TEABF 4 /PC electrolyte. When the molar concentration of TEAODFB reaches to 1.6 M, the TEAODFB/PC electrolyte has superior conductivity of 14.46 mS cm −1 and good capacitor characteristics. Despite the less accessible to the electrode and low energy density was achieved, the specific capacitance of 1.6 M TEAODFB/PC electrolyte is 21.4 F g −1 at 1 A g −1 , and the energy density and power density were comparable to 1 M TEABF 4 /PC electrolyte at 1–5 A g −1 . Temperature characteristic was also tested by 3.3 F circular capacitors from −40 to 60 °C, the result demonstrates that capacitors using 1.6 M TEAODFB/PC electrolyte show much higher capacitance and energy density at the investigated temperatures, and the discharge capacitance of capacitors using 1.6 M TEAODFB/PC electrolyte varies with the temperature less than that of 1 M TEABF 4 /PC electrolyte.

Highly ordered α-Fe2O3 nanotube arrays have been fabricated by a simple and cost-effective anodization method on iron foils. The α-Fe2O3 nanotube arrays exhibit high specific capacitance (138 F·g−1 at 1.3 A·g−1), remarkable rate capability (91 F·g−1 at 12.8 A·g−1) and good cycling stability (the capacitance retention close to 89% after 500 cycles), due to the unique nanostructures of the α-Fe2O3 nanotube arrays, which providing high surface area, fast ion transport pathways and robust structures. These features made the α-Fe2O3 nanotube array electrode very attractive for supercapacitor applications. Keywords: Iron oxide, Anodization, Nanotube array, Supercapacitors

The electrodeposition of Bi 2 Se 3 nanowires on an anodic aluminum oxide template was investigated by cyclic voltammetry in a tartaric acid aqueous solution. The electrochemical behavior of the Bi 2 Se 3 nanowires in the electrolytic solution was also investigated using cyclic voltammetry, and the underpotential deposition mechanism of the Bi 2 Se 3 nanowires was determined. According to the cyclic voltammetric curves, −0.20 V vs. SCE (saturated calomel electrode) was chosen as the deposition potential of the Bi 2 Se 3 nanowires. The ratio of Bi to Se is nearly 2:3, verified by energy-dispersive X-ray spectroscopy and with the addition of surfactant. X-ray diffraction, scanning electron microscopy, selected-area electron diffraction and high-resolution transmission electron microscopy indicate that annealing can improve the crystallinity and chemical composition of Bi 2 Se 3 nanowires. Surfactant can also improve the surface morphology and composition of the Bi 2 Se 3 nanowires.

TiO2-B was synthesized by solid-state reaction. The structures, surface morphologies and electrochemical performances of TiO2-B were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and electrochemical measurement, respectively. The effects of calcining temperature, molar ratio of K2O to TiO2 and calcining time on the characteristics of TiO2-B were investigated. The results show that the calcining time exerts a significant influence on the electrochemical performances of TiO2-B. The TiO2-B is obtained with good crystal structure and suitable size by using K2Ti4O9, which is prepared at 950°C for 24 h under the condition of x(K2O)/x(TiO2)=1:3.5. The TiO2-B delivers all initial discharge capacity of 231.6 mA·h/g. And the rate capacity is 73.2 mA·h/g at 1 675 mA/g, which suggests that TiO2-B is a promising anode material for the lithium ion batteries.

The electrolytes based on lithium oxalyldifluoroborate (LiODFB) and carbonates have been systematically investigated for LiFePO 4 /artificial graphite (AG) cells, by ionic conductivity test and various electrochemical tests, such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge–discharge test. The conductivity of nine electrolytes as a function of solvent composition and LiODFB salt concentration has been studied. The coulombic efficiency of LiFePO 4 /Li and AG/Li half cells with these electrolytes have also been compared. The results show that 1 M LiODFB EC/PC/DMC (1:1:3, v/v) electrolyte has a relatively higher conductivity (8.25 mS cm −1 ) at 25 °C, with high coulombic efficiency, good kinetics characteristics and low interface resistance. With 1 M LiODFB EC/PC/DMC (1:1:3, v/v) electrolyte, LiFePO 4 /AG cells exhibit excellent capacity retention ∼92% and ∼88% after 100 cycles at 25 °C and at elevated temperatures up to 65 °C, respectively; The LiFePO 4 /AG cells also have good rate capability, the discharge capacity is 324.8 mAh at 4 C, which is about 89% of the discharge capacity at 0.5 C. However, at −10 °C, the capacity is relatively lower. Compared with 1 M LiPF 6 EC/PC/DMC (1:1:3, v/v), LiFePO 4 /AG cells with 1 M LiODFB EC/PC/DMC (1:1:3, v/v) exhibited better capacity utilization at both room temperature and 65 °C. The capacity retention of the cells with LiODFB-based electrolyte was much higher than that of LiPF 6 -based electrolyte at 65 °C, while the capacity retention and the rate capacity of the cells is closed to that of LiPF 6 -based electrolyte at 25 °C. In summary, 1 M LiODFB EC/PC/DMC (1:1:3, v/v) is a promising electrolyte for LiFePO 4 /AG cells.

A novel porous Pb–Ag (0.8wt.%) anode was investigated for zinc electro-winning and six kinds of porous anodes with different controlled pore size and homogeneous pore structure were prepared by negative pressure infiltration. Their electrochemical properties were studied by chrono-potentiometry in the electrolyte of ZnSO4–H2SO4 and ZnSO4–MnSO4–H2SO4, respectively, and the results compared with the traditional flat plate anode. The results show that with the decrease of pore size, the anodic potential first decreases and then increases in ZnSO4–H2SO4 electrolyte. The lowest value was 1.729 V when the pore size was 1.25–1.60 mm, which is 106 mV lower than that of the flat plate anode. The anodic corrosion rate reaches the lowest value at the pore size of 1.60–2.00 mm. In the electrolyte of ZnSO4–MnSO4–H2SO4, the formation of dense PbO2/MnO2 protective layer leads to a further decrease of the anodic potential and corrosion rate while manganese impurity has little effect on cathode current efficiency. Furthermore, the porous anode is beneficial in decreasing the precipitation of Mn2+ from solution as MnO2. Compared with the flat plate anode, the behavior of the porous anode is similar to a flat plate anode operating under a lower current density.

The initial stages of selenium electrodeposition onto SnO2 coated glass substrates are studied using cyclic voltammetry and chronoamperometry. At low overpotential, the deposition of Se proceeds by a four-electron reduction of Se(IV) to Se(0) and a 2D growth under instantaneous nucleation followed by a multilayer spiral growth mode. At high overpotential, the deposition of Se occurs through a comproportionation reaction between Se(IV) and Se(-II) generated from a six-electron reduction of Se(IV), and a 3D growth under progressive nucleation.

Magnesium hydroxide thin films were electrodeposited on SnO2 coated glass substrates from aqueous magnesium nitrate solution at room temperature. The electrochemical process and mechanism were characterized by cyclic voltammetry(CV) and chronoampero-metry. CV curves confirm three main cathodic reactions, including reduction of oxygen, nitrate and evolution of hydrogen. With the applied potential increasing, cathodic current density increased. FESEM observation shows porous films grew densely and flower-like secondary grains tended to generate on the film surface. Mg(OH)2 film electrodeposited at linear sweep voltage(LSV) exhibits dense morphology different with porous morphology by potentiostatic method. This morphology difference is attributed to Hydrogen evolution reaction (HER). Hydroxyl ion or accumulation of electrons at the cathode surface may hinder the evolution of hydrogen. GAXRD result indicates the film by LSV method exhibits preferred orientation along (001) plane of Brucite Mg(OH)2 structure.

The activated carbon wound supercapacitors with TEABF4/propylene carbonate (PC) and TEABF4/acetonitrile (AN) electrolytes were prepared. The effects of the electrolyte and temperature on the capacitance behavior were investigated by cyclic voltammetry (CV) and constant current charge-discharge. Compared with the PC-based supercapacitor, the AN-based supercapacitor has higher capacitance and lower equivalent serial resistance (RES) at discharge currents ranging from 5 to 1 000 mA and 25 °C. Moreover, temperature effects are more prominent for PC-based supercapacitor than for AN-based supercapacitor. When the measurement temperature ranges from 60 °C to −40 °C the capacitance changes from 5.1 to 2.5 F and RES changes from 135 to 876 mΩ for the PC-based supercapacior, while the AN-based supercapacitor shows less change in capacitance and RES. Thus AN-based supercapacitor exhibits excellent power characteristics and temperature property.

The electrodeposition of Cu(In,Ga)Se 2 has been investigated by cyclic voltammetry (CV) in a DMF-aqueous solution that contained citrate as a complexing agent. The effects of the citrate ion on the reduction potentials of Cu 2+ , In 3+ , Ga 3+ and H 2 SeO 3 were examined for a unitary system. Furthermore, a cyclic voltammetry study was performed in a ternary Cu–In–Se system, a quaternary Cu–In–Ga–Se system, and binary Cu–Se, In–Se and Ga–Se systems. The insertion of In and Ga into the solid phase may proceed by an underpotential deposition mechanism, which involves two different routes: In 3+ and Ga 3+ reduction by a surface-induced effect from Cu 3 Se 2 and/or reaction with H 2 Se.

A process was proposed based on the combination of chemical and physical activation for the production of activated carbons used as the electrode material for electric double layer capacitor (EDLC). By material characterization and electrochemical methods, the influences of the activitation process on the specific surface area, pore structure and electrochemical properties of the activated carbons were investigated. The results show that specific surface area, the mesopore volume, and the specific capacitance increase with the increase of the mass ratio of KOH to char (m(KOH)/m(char)) and the activation time, respectively. When m(KOH)/m(char) is 4.0, the specific surface area and the mesopore volume reach the maximum values, i.e. 1 960 m2/g and 0.308 4 cm3/g, and the specific capacitance is 120.7 F/g synchronously. Compared with the chemical activation, the activated carbons prepared by chemical-physical activation show a larger mesopore volume, a higher ratio of mesopore and a larger specific capacitance.

Lithium difluoro(axalato)borate (LiODFB) was synthesized in dimethyl carbonate (DMC) solvent and purified by the method of solventing-out crystallization. The structure characterization of the purified LiODFB was performed by Fourier transform infrared (FTIR) spectrometry and nuclear magnetic resonance (NMR) spectrometry. The electrochemical properties of the cells using 1 mol/L LiPF6 and 1 mol/L LiODFB in ethylene carbonate (EC)/DMC were investigated, respectively. The results indicate that LiODFB can be reduced at about 1.5 V and form a robust protective solid electrolyte interface (SEI) film on the graphite surface in the first cycle. The graphite/LiNi1/3Mn1/3Co1/3O2 cells with LiODFB-based electrolyte have very good capacity retention at 55 °C, and show very good rate capability at 0.5C and 1C charge/discharge rate. Therefore, as a new salt, LiODFB is a most promising alternative lithium salt to replace LiPF6 for lithium ion battery electrolytes in the future.

Alumina coated LiNi1/3Mn1/3Co1/3O2 particles were obtained by a simple method of solid state reaction at room temperature. The reaction mechanism of solid state reaction at room temperature was investigated. The structure and morphology of the coating materials were investigated by XRD, SEM and TEM. The electrochemical performances of uncoated and Al2O3-coated LiNi1/3Co1/3Mn1/3O2 cathode materials were studied within a voltage window of 3.00–4.35 V at current density of 30 mA/g. SEM, TEM and EDS analytical results indicate that the surface of LiNi1/3Mn1/3Co1/3O2 particles is coated with very fine Al2O3 composite, which leads to the improved cycle ability though a slight decrease in the first discharge capacity is observed. It is proposed that surface treatment by solid state reaction at room temperature is a simple and effective method to improve the cycle performance of LiNi1/3Co1/3Mn1/3O2 particles.

With citric acid as a polymeric agent layered LiNi0.8Co0.2O2 materials were synthesized by a spray pyrolysis method. The LiNi0.8Co0.2O2 particles were characterized by means of XRD, SEM and TEM. The electrochemical performances of LiNi0.8Co0.2O2 particles were studied in a voltage window of 3.00–4.35 V and at a current density of 30 mA/g. The results show that in the pilot-scale spray pyrolysis process, the morphology of particles is dependent upon the precursor concentration and flux of carrier gas. The initial discharge capacity of the LiNi0.8Co0.2O2 particles at 720 °C for 12 h °C is 187.3 mA·h/g, and the capacity remains 96.8 % with excellent cycleability after 30 cycles. The LiNi0.8Co0.2O2 samples synthesized under the optimized conditions by the spray pyrolysis method shows a good electrochemical performance.

Mn/Ni composite oxides as active electrode materials for supercapacitors were prepared by solid-state reaction through the reduction of KMnO4 with manganese acetate and nickel acetate at low temperature. The products were characterized by X-ray diffractometry(XRD) and transmission electron microscopy(TEM). The electrochemical characterizations were performed by cyclic voltammetry (CV) and constant current charge-discharge in a three-electrode system. The effects of different potential windows, scan rates, and cycle numbers on the capacitance behavior of Mn0.8Ni0.2Ox composite oxide were also investigated. The results show that the composite oxides are of nano-size and amorphous structure. With increasing the molar ratio of Ni, the specific capacitance goes through a maximum at molar fraction of Ni of 20%. The specific capacitance of Mn0.8Ni0.2Ox composite oxide is 194.5 F/g at constant current discharge of 5 mA.

LiFePO4 was prepared by heating the pre-decomposed precursor mixtures sealed in vacuum quartz-tube. Three kinds of cooling modes including nature cooling, air quenching, and water quenching were applied to comparing the effects of cooling modes on the microstructure and electrochemical characteristics of the material. The results indicate that the water quenching mode can control overgrowth of the grain size of final product and improve its electrochemical performance compared with nature cooling mode and air quenching mode. The sample synthesized by using water quenching mode is of the highest reversible discharge specific capacity and the best cyclic electrochemical performance, demonstrating the first discharge capacity of 138.1 mA·h/g at 0.1C rate and the total loss of capacity of 3.11% after 20 cycles.

The influences of molar ratio of KOH to C and activated temperature on the pore structure and electrochemical property of porous activated carbon from mesophase pitch activated by KOH were investigated. The surface areas and the pore structures of activated carbons were analyzed by nitrogen adsorption, and the electrochemical properties of the activated carbons were studied using two-electrode capacitors in organic electrolyte. The results indicate that the maximum surface area of 3 190 m2/g is obtained at molar ratio of KOH to C of 5:1, the maximum specific capacitance of 122 F/g is attained at molar ratio of KOH to C of 4:1, and 800 °C is the proper temperature to obtain the maximum surface area and capacitance.

A technique of combination of vacuum firing and water quenching was applied to the synthesis of LiFePO4 powder. The sample was prepared by heating the pre-decomposed precursor mixtures sealed in vacuum quartz-tube, followed by water quenching at the sintering temperature. The synthetic conditions were optimized by orthogonal experiment. The results indicate that the fast quenching treatment can avoid the overgrowth of single crystal and improve its availability ratio of active material. The sintering temperature has the greatest effect on the electrochemical performance of sample. Next is the molar ratio of Li to Fe and the sintering time, respectively. The samples prepared in the optimized technical condition has the highest reversible discharge specific capacity of 149.8 mA·h/g.

Spherical Li(Ni(subscript 1/3)Mn(subscript 1/3)Co(subscript 1/3))O2 was prepared via the homogenous precursors produced by solution spray-drying method. The precursors were sintered at different temperatures between 600 and 1000℃ for 10h. The impacts of different sintering temperatures on the structure and electrochemical performances of Li(Ni(subscript 1/3)Mn(subscript 1/3)Co(subscript 1/3))O2 were compared by means of X-ray diffractometry(XRD), scanning electron microscopy(SEM), and charge/discharge test as cathode materials for lithium ion batteries. The experimental results show that the spherical morphology of the spray-dried powers maintains during the subsequent heat treatment and the specific capacity increases with rising sintering temperature. When the sintering temperature rises up to 900℃, Li(Ni(subscript 1/3)Mn(subscript 1/3)Co(subscript 1/3))O2 attains a reversible capacity of 153 mA•h/g between 3.00 and 4.35V at 0.2C rate with excellent cyclability.

Taking the selection of coal-tar pitch as precursor and KOH as activated agent, the activated carbon electrode material was fabricated for supercapacitor. The surface area and the pore structure of activated carbon were analyzed by Nitro adsorption method. The electrochemical properties of the activated carbons were determined using two-electrode capacitors in 6 mol/L KOH aqueous electrolytes. The influences of activated temperature and mass ratio of KOH to C on the pore structure and electrochemical property of porous activated carbon were investigated in detail. The reasons for the changes of pore structure and electrochemical performance of activated carbon prepared under different conditions were also discussed theoretically. The results indicate that the maximum specific capacitance of 240 F/g can be obtained in alkaline medium, and the surface area, the pore structure and the specific capacitance of activated carbon depend on the treatment methods; the capacitance variation of activated carbon cannot be interpreted only by the change of surface area and pore structure, the lattice order and the electrolyte wetting effect of the activated carbon should also be taken into account.

The spinel LiMn2O4 used as cathode materials for lithium-ion batteries was synthesized by mechano-chemistry fluid activation process, and modified by doping rare-earth Sm. Thesting of X-ray diffraction, cyclic voltammograms, charge-discharge and SEM was carried out for LiMn2O4 cathode materials and the modified materials. The results show that the cathode materials doped rare earth LixMn2−ySmzO4 (0.95⩽x⩽1.2, 0⩽y⩽0.3, 0⩽z⩽0.2) exhibit standard spinel structure, high reversibility of electrochemistry and excellent properties of charge-discharge. In EC: DMC(1 : 1)+1 mol/L LiPF6 electrolyte with discharge capacity more than 130 mA · h/g, and its capacity is deteriorated less than 15% after 300 cycles at room temperature and less than 20% after 200 cycles at 55°C. At the same time, Crystal Field Theory was applied to explain the function and mechanism of doped rare earth element.