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A novel redox flow battery–single flow Zn/NiOOH battery is proposed. The electrolyte of this battery for both negative electrode and positive electrode is high concentration solutions of ZnO in aqueous KOH, the negative electrode is inert metal such as nickel foil, and the positive electrode is nickel oxide for secondary alkaline batteries. Typically, there is no requirement for a membrane in the battery. Ni(OH)2 is oxidized to NiOOH at positive electrode and the zincate ions is reduced to zinc and electroplated onto the negative electrode during charge. The reverse occurs during discharge. Results obtained with a small laboratory cell show that high efficiencies can be achieved with an average coulombic efficiency of 96% and energy efficiency of 86% over 1000 cycles. High performance obtained indicates that the single flow zinc/nickel battery is a promising battery. Keywords: Redox flow battery, Zinc–nickel battery, Secondary alkaline battery, Zinc anode

For double-layer capacitors in alkaline electrolyte, the specific capacitance of the positive electrode is not equal to that of the negative one. Thus, capacitor performance cannot be optimal with a positive/negative electrode matching ratio of 1. In this study nanoporous glassy carbons (NPGCs) were employed as the electrodes of capacitors, and the influence of matching ratio between positive and negative electrode on capacitor performance was systematically investigated. In aqueous KOH, the specific capacitance of the positive electrode is lower than that of the negative electrode. The matching ratio at which a maximum capacitance is obtained is dependent on the values of the positive and negative electrode capacitance. At low current rate, the highest specific capacitance is achieved at a matching ratio slightly higher than 1. At high current rate, a capacitor has the highest specific capacitance with the lowest resistance at a matching ratio of 1.5. This indicates that an optimum matching relationship between positive and negative electrodes is attained.

the kinetic characteristics of the concentrated v(iv)/v(v) couple have been studied at a glassy carbon electrode in sulfuric acid using rotating-disc electrode and cyclic voltammetry. the kinetics of the v(iv)/v(v) redox couple reaction was found to be electrochemically quasi-reversible with the slower kinetics for the v(v) reduction than that for the v(iv) oxidation. and, dependence of diffusion coefficients and kinetic parameters of v(iv) species on the v(iv) and h2so4 concentration was investigated. it is shown that the concentration of active species v(iv) should be over 1 mol(.)l(-1) for the redox flow battery application. further, with increasing the v(iv) and h2so4 concentration, the diffusion coefficients of v(iv) were gradually reduced whereas its kinetics was improved considerably, especially in the case of v(iv) and h2so4 up to 2 and 4 mol(.)l(-1).

The electrochemical behavior of the Fe(III)/Fe(II)–triethanolamine(TEA) complex redox couple in alkaline medium and influence of the concentration of TEA were investigated. A change of the concentration of TEA mainly produces the following two results. (1) With an increase of the concentration of TEA, the solubility of the Fe(III)–TEA can be increased to 0.6 M, and the solubility of the Fe(II)–TEA is up to 0.4 M. (2) In high concentration of TEA with the ratio of TEA to NaOH ranging from 1 to 6, side reaction peaks on the cathodic main reaction of the Fe(III)–TEA complex at low scan rate can be minimized. The electrode process of Fe(III)–TEA/Fe(II)–TEA is electrochemically reversible with higher reaction rate constant than the uncomplexed species. Constant current charge–discharge shows that applying anodic active materials of relatively high concentrations facilitates the improvement of cell performance. The open-circuit voltage of the Fe–TEA/Br2 cell with the Fe(III)–TEA of 0.4 M, after full charging, is nearly 2.0 V and is about 32% higher than that of the all-vanadium batteries, together with the energy efficiency of approximately 70%. The preliminary exploration shows that the Fe(III)–TEA/Fe(II)–TEA couple is electrochemically promising as negative redox couple for redox flow battery (RFB) application. © 2005 Elsevier Ltd. All rights reserved.

The electrode process of concentrated V(IV)/V(V) species has been studied at a graphite electrode by using cyclic voltammetry, low speed linear polarization, and impedance techniques. The results have revealed that in H 2SO4 solution below 2 mol·L -1 containing 2.0 mol·L -1 V(IV), the electrode process of V(IV)/V(V) is controlled by the electrochemical polarization and diffusion with poor reversibility. When the concentration of H2SO4 is above 2 mol·L -1 , the electrode process of V(IV)/V(V) turns to diffusion control with improvement of the reversibility. An increase in concentration of H 2SO4 solution facilitates a decrease in impedance, whereas too high concentration of H 2SO4 solution (>3 mol·L -1 ) results in a remarkable increase in the viscosity of solution leading to a large mass transportation polarization, and thus the impedance starts to increase a little. In 3 mol·L -1 H 2SO4 solution, the reversibility and kinetics of V(IV)/V(V) are improved gradually and the characteristics of impedance also improves with an increase in concentration of V(IV) solution. But, when the concentration of V(IV) solution exceeds 2.0 mol·L -1 , the viscosity of the solution is so high that the mass transportation polarization increases considerably, resulting in the deterioration of electrochemical performance of V(IV)/V(V) species and an increase in impedance. Therefore, by considering from the standpoint of increasing energy density and electrode kinetics comprehensively, the optimal concentration of H 2SO4 is 3 mol ·L -1 containing 1.5-2.0 mol·L -1 of V(IV).

A nanoporous glassy carbon (NPGC) used as a new electrochemical capacitor material has been developed and prepared from a novolac phenolic resin. This new porous carbon has a high specific capacity due to its large surface area and a high power density due to its nice bulk conductivity and nanoporous structure. In this paper, main factors that influence the pore structure and electrochemical performance of NPGCs were systematically investigated. The results showed that the porosity of carbonized resin increased with curing temperature up to 225 °C at which the resin can be cross-linked fully, facilitating activation agent molecules to diffuse inward. It was also found that high carbonization temperature helped crystallization of carbonized products, but the shrinkage of carbon skeleton made the extent of activation decrease. Meantime, increasing activation temperature may accelerate reaction rate and prolonging activation time may increase the extent of activation. However, too high activation temperature and too long activation time can make the carbon matrix cracked and distorted. Therefore, a maximum capacity of 203 F g−1 and a conductivity of about 10 S cm−1 was obtained for the NPGC sample prepared under suitable conditions, resulting in high power densities (6.5 kW kg−1 carbon).

This paper describes a novel redox flow battery–single flow acid Cd–chloranil battery. The electrolyte of this battery for both negative electrode and positive electrode is the aqueous intermixture of H2SO4–(NH4)2SO4–CdSO4, the negative electrode is inert metal such as copper foil, and the positive electrode is an insoluble organic material, tetrachloro-p-benzoquinone (chloranil). Typically, the electrolyte is continuously circulated to pass though the cells by means of a single pump as the battery is on duty. There is no requirement for a membrane. Tetrachloro-p-benzo-hydroquinone is oxidized to chloranil at positive electrode and the cadmium ions is reduced to cadmium and electroplated onto the negative electrode during charge. The reverse occurs during discharge. Results obtained with a small laboratory cell show that high efficiencies can be achieved with an average coulombic efficiency of 99% and energy efficiency of 82% over 100 cycles at the current density of 10 mA cm−2. Keywords: Redox flow battery, Single flow acid battery, Chloranil, Cadmium

According to walking requirements, combining modularization and reconfigurable ideas, a quadruped/biped reconfigurable walking robot with parallel leg mechanism has been proposed. In this paper, considering the dimension optimization and structural constraints of the walking chair robot, the walking step length is obtained firstly. After that, based on walking requirements and stability of body mechanism, the translational gait is planned. Furthermore, the walking chair's static stability is analyzed through the stability margin of the parallel robot. Finally the workspaces of the swing leg and the whole mechanism are calculated to verify the correctness and effectiveness of gait planning. The gait planning research on quadruped walking chair robot lays a theoretical foundation for experiment of the prototype.

Flow acid Cu-PbO 2 battery (CPB) is a new type of single flow energy storage battery. The effect of the concentration of CuSO 4 in electrolyte on electrochemical performance of negative electrode of CPB and electrolyte was investigated by using cyclic voltammetry(CV), linear sweep voltammetry(LSV) and electrochemical impedance spectroscopy(EIS). The results revealed that the reversibility of Cu2+/Cu couple, dissolution-electrodeposition performance of Cu and conductivity of electrolyte reach a relatively high level at an electrolyte concentration of 0.6M CuSO 4 in 1.225M H 2 SO 4 .

An uninterruptible flow power system (UFPS) is proposed, which is comprised of a positive electrode for catalyzing the organic electro-oxidation, a communal negative electrode, and an air electrode for catalyzing the oxygen reduction and flow electrolytes. During electrolysis of the electro-synthesis reactor, the electrical capacity passed through the communal negative electrode is extracted by the zinc-air cell in order to deliver energy. Under the operation condition of successive organic electro-synthesis, this electrochemical system can be applied as an uninterrupted power source. Thus, the UFPS can be used for the organic electro-synthesis and discharge as power supply simultaneously or asynchronously. This paper demonstrates that the uninterruptible flow power system is feasible by utilizing the equilibrium of zinc deposition/dissolution on a perforated nickel-plated steel electrode with a propanol-oxidation electrode and an air electrode. Such combined electrochemical systems are capable of uninterrupted and stable operation with an energy efficiency of around 66%.

Novel organic redox flow battery is proposed based on 4, 5- dihydroxy-1, 3-benzenedisulfonate and 2, 5 dihydroxy-benzenedisulfonate as positive materials and PbSO 4 /Pb as negative electrode in aqueous H 2 SO 4 solution with an ion-exchange membranes between the positive and negative electrolyte. 4, 5-dihydroxy-1, 3-benzenedisulfonate oxide and 2, 5-dihydroxybenzenedisulfonate oxide have good reversibility and relatively high potentials in acidic solutions although the two hydroquinones have different electrochemical mechanism. Hydroquinones are oxidized to quinones at positive electrode during charge and quinones are reduced to hydroquinones during discharge. Results obtained with a small laboratory cell show that high efficiencies can be achieved with an average coulombic efficiency of 99% and energy efficiency of 70% over 100 cycles. High performance obtained indicates that soluble quinones are promising positive materials of novel organic redox flow batteries.

Monolithic porous carbon (MPC) was synthesized by a templating method using Na2CO3 as template, novolac-type phenolic resin as carbon precursor and hexamethylenetetramine as hardening agent. The template, carbon precursor and hardening agent were mechanically mixed in a grinding machine, hardened at 150 °C, crushed into fine particles, compacted into a disc, carbonized at 800 °C and finally washed with deionized water to form MPC. MPC–Ni(OH)2 electrodes were prepared by loading Ni(OH)2 into the MPC by cathodic deposition. The MPC is hierarchically porous, has an electric conductivity of 20.40 S cm−1 and a specific surface area of 576 m2 g−1. Charge-discharge characterization of the MPC–Ni(OH)2 electrodes shows that the specific capacities based on active material and the whole electrode are 230 mAh g−1 and 131 mAh g−1, respectively. This suggests that the MPC is a promising lightweight matrix to host nickel hydroxide to achieve a high specific energy in nickel-based alkaline batteries. [New Carbon Materials 2013, 28(2): 115–120]

The formal potential of the Fe(III)/Fe(II) couple shifts markedly in the negative direction by complexation with ethylenediamine tetraacetate (EDTA), oxalate, and citrate. The potentials of the complexes with EDTA and oxalate are less pH-dependent than with citrate. But, the relatively high pH of around 6.0 is favorable electrochemically due to high corresponding currents. Complexation of Fe(III)/Fe(II) couple can provide fast electrode kinetics except for the complex with citrate. But, the solubility of the complex with citrate is up to 0.8 M. Charge-discharge measurements were conducted with the iron-complex/Br-2 redox cells. The results show that performance of the cells with 0.1 M Fe(III)/Fe(II)-oxalate or Fe(III)/Fe(II)-citrate is relatively poor due to slow kinetics for the Fe(III)/Fe(II)-citrate and the unstability of the ferric form for the Fe(III)/Fe(II)-oxalate, whereas performance of the iron-citrate/Br-2 cell is improved considerably by increasing concentration of the Fe(III)-citrate complex. Also, energy efficiencies of up to approximately 80 and 70% could be obtained for the cell with 0.1 M Fe(III)/Fe(II)-EDTA and 0.8 M Fe(III)/Fe(II)-citrate, respectively. The preliminary study shows that novel Br-2/iron-complex cells are technically feasible in redox flow batteries but need further investigation. (c) 2006 The Electrochemical Society.

The correlation between the pore structure of monolithic nanoporous glassy carbons (NPGCs) and their double-layer capacitance in KOH-aqueous electrolyte was investigated. The results obtained show that, in general, capacitance increases with surface area. However, the capacitance for NPGCs with high conductivity strongly depends on pore structure. At a low current rate, the double-layer capacitance (DLC) comes mostly from the contribution of micropores with the properties of a metal conductor, while the contribution of external pores with the properties of a semiconductor is very limited. As current densities increase, micropores contribute less to the DLC due to the existence of too narrow micropores, while external pores contribute more to the DLC due to a decrease in the effect of semiconductor behaviors. In addition, it is determined that with the charge-discharge rate increasing, minimum pore sizes that contribute to the DLC increase but are still in the microporous range. It has also been observed that for samples with mesopore or wider micropore size distribution, resistance is low and capacitance becomes insensitive to the charge-discharge rate. Therefore, carbon materials with a wider micropore size distribution have higher surface areas and larger capacity than those with a mesoporosity, being more suitable electrodes for electrochemical capacitor applications.