Nickel Positive Electrode Research Articles

An Application of Electron Energy Loss Spectroscopy to a Cycled Nickel Positive Electrode of a Nickel Metal Hydride Battery

An Application of Electron Energy Loss Spectroscopy to a Cycled Nickel Positive Electrode of a Nickel Metal Hydride Battery

Impact of LiTi2(PO4)3 coating on the electrochemical performance of Li1.2Ni0.13Mn0.54Co0.13O2 using a wet chemical method

NASICON-type solid-state electrolyte has been reported to improve the structural and electrochemical stability of high nickel positive electrode materials; however, the impact of NASICON-type solid-state electrolyte on the performance of lithium-rich cathode has been barely studied. In this work, various contents of LiTi2(PO4)3 (LTP)-coated Li1.2Ni0.13Mn0.54Co0.13O2 have been made via a wet chemical method followed by sintering at 550 °C for 3 h. Those modified materials failed to show improvement in electrochemical properties including specific capacity, coulombic efficiency (CE), rate capability, and cycle life compared with uncoated material. Thick LTP coating even decreases the average discharge voltage and increases the impedance and voltage hysteresis of cells. XRD, TEM, and SAED images revealed non-uniform coating with multiple components including LiTi2(PO4)3, TiP2O7, and TiO2. This work suggests LTP coating on Li1.2Ni0.13Mn0.54Co0.13O2 using a wet chemical method might be challenging and need to be carefully carried out.

The influence of copper and carbon black on electrochemical behavior of nickel positive electrode

Nickel hydroxide is used as an active material in positive electrodes of secondary alkaline batteries. In alkaline batteries, the capacity of the negative electrode is greater than that of the positive electrode, hence the cell capacity is limited by the positive electrode. The practical capacity of the Ni(OH) 2 positive electrode depends on the efficiency of the conductive network connecting the Ni(OH) 2 particles with the current collector. In this study, hot-pressed-type electrodes were prepared using fiber-like β-Ni(OH) 2 powder as the active material on a nickel mesh as a current collector. The effect of carbon black as a conductive network for Ni(OH) 2 active material and the partial substitution of Cu(OH) 2 for β-Ni(OH) 2 material on the electrode performance, are examined. The carbon black powder addition improves the utilization of the active material; however it lead to a decrease in stability of the electrode. The partial substitution of Cu(OH) 2 for β-Ni(OH) 2 significantly improves the coulombic efficiency of the β-Ni(OH) 2 active material and it also increases the specific discharge capacity and enhance the stability of the electrode. These findings showed that the copper modified β-Ni(OH) 2 electrodes possessed an improved specific capacity and stability and thus may be recognized as a promising hybrid material for battery electrode applications. • The β-phase Ni(OH) 2 is formed when hydrothermal treatment is applied. • Carbon black improves specific discharge capacity but not stability. • Cu 2+ substitution improves both capacity and stability.

Water-Organic Electrolyte for Rechargeable Zinc Electrode Having Positive Electrode Compatibility

Summary Cycle performance of the zinc oxide electrode improves by mixing the organic solvent in the electrolyte. However, the organic solvent is concerned to be decomposed at the positive electrode. In order to solve the problem, the zinc oxide negative and the positive electrodes are separated by a membrane, and the organic solvent is added only in the negative electrode side. As a result, the organic solvent decomposition at the positive electrode is avoided and thus the cell shows good cycle performance. 1. Introduction Zinc is widely used as a negative electrode material for primary batteries with its strong reducing power and a high capacity. However, its use as a rechargeable electrode has been limited due to insufficient cycle life. We have shown that water-organic co-solvent electrolytes are effective for restricting the dissolution of the zinc species and thus improving the cycle performance [1]. On the other hand, organic solvents are generally vulnerable to oxidation and hence such water-organic co-solvent electrolytes can be incompatible with positive electrodes such as Ni(OH)2and air electrodes. This study describes a cell setup that is effective for both zinc electrode rechargeability and positive electrode compatibility. Here a membrane that suppresses the transfer of the organic molecules was employed in the cell to show the Ni(OH)2electrode compatibility. 2. Experimental Zinc composite electrodes consisted of ZnO, PbO, carbon and a binder, pasted on a copper current collector. The potential of the zinc negative electrode was measured versus an Hg/HgO reference electrode. The positive electrode was a sintered nickel (Ni(OH)2) electrode. The electrolyte consisted of a 4 M KOH aqueous solution. In the negative electrode side, organic molecules such as alcohol were added to the KOH solution. A hydrophilic membrane was used as a separator to suppress the transfer of the organics to the positive electrode. 3. Results and Discussion The membrane was permeable to small organics (MW<100) but can suppress the transfer of large molecules (i.e. oligomers or polymers). Accordingly, when this membrane is used as a separator between the negative and positive electrodes, the organic can be maintained at the negative electrode side while hydroxide ions are transferred through the membrane for charge neutrality during charging-discharging. A large organic was selected and their effect on the cycle performance was examined. As shown in Fig. 1(a), the use of the organic is effective for improving the cycle life of the zinc electrode. The sintered nickel positive electrode was degraded when tested without a membrane, indicating the reactivity of the organic at the positive electrode. In contrast, when a proper membrane was used as the separator, the nickel electrode functioned without any problem, showing that the organic transfer through the membrane can be disregarded. Small organics were detrimental to the nickel electrode even if a membrane was set between the positive and negative electrodes. The porous structure of the zinc electrode was observed by SEM analysis. Figure 1(b) shows that there are many pores in the composite electrode prior to the cycling test. After 40 charge-discharge cycles, the porous structure were maintained when the organic was used whereas the pores were mostly clogged without using the organic, as shown in Figs. 1 (b) and (c). These results show that the densification [2], which is a typical deterioration mode of the zinc electrode, was suppressed and there were on-site zinc dissolution and deposition with the addition of the organic. It is deduced that the water activity in the electrolyte was reduced in the presence of the organic species and thus the zincate dissolution was suppressed. The shape change behavior [2], another typical deterioration mode of the zinc electrode, was observed by synchrotron X-ray diffraction mapping. The measurement using the zinc-nickel cells demonstrates the effect of the organic also on the shape change behavior. 4. Acknowledgment This work was supported by RISING project of NEDO. 5.

Simulation of Ni-MH Batteries via an Equivalent Circuit Model for Energy Storage Applications

Impedance measurement was conducted at the entire cell level for studying of the Ni-MH rechargeable batteries. An improved equivalent circuit model considering diffusion process is proposed for simulation of battery impedance data at different charge input levels. The cell capacity decay was diagnosed by analyzing the ohmic resistance, activation resistance, and mass transfer resistance of the Ni-MH cells with degraded capacity. The capacity deterioration of this type, Ni-MH cell, is considered in relation to the change of activation resistance of the nickel positive electrodes. Based on the report and surface analysis obtained from the energy dispersive X-ray spectroscopy, the composition formula of metal-hydride electrodes can be closely documented as the AB5 type alloy and the “A” elements are recognized as lanthanum (La) and cerium (Ce). The capacity decay of the Ni-MH cell is potentially initiated due to starved electrolyte for the electrochemical reaction of active materials inside the Ni-MH battery, and the discharge product of Ni(OH)2 at low state-of-charge level is anticipated to have more impeding effects on electrode kinetic process for higher power output and efficient energy delivery.

Improvement of basic performances of a nickel-metal hydride battery

To develop a sealed-type nickel-metal hydride battery for use in portable equipment or in electric vehicles, investigations were conducted on negative electrodes using AB5-type hydrogen storage alloy and positive electrodes. For the cycle life performance of the battery, alkaline treatment of the alloy and the substitution of more than 50% to the alloy with Co were effective. For the positive electrode, zinc as a solid solution in the nickel positive electrode obviously prevented γ-NiOOH from being formed in the charging process of β-Ni(OH)2 and suppressed the migration of the electrolyte solution in the separator to the active material of the positive electrode. Also, hydrophobic treatment of the surface of the alloy was effective to prevent the elevation of the battery internal pressure of the battery in high rate charge.

Charge-Discharge and Capacity Retention Characteristics of New Type Ni/MH Batteries Using Polymer Hydrogel Electrolyte

Positive electrode capacity-controlled nickel/metal hydride (Ni/MH) batteries were assembled using the polymer hydrogel electrolyte and their charge/discharge and capacity retention characteristics were investigated compared to those using a 7.3 M KOH aqueous solution. The interface between the polymer hydrogel electrolyte and nickel positive electrode worked very well and the experimental cell with the polymer hydrogel electrolyte exhibited charge/discharge characteristics such as discharge capacity, cycle performance and high rate capability almost comparable to the cell with a 7.3 M KOH aqueous solution. Moreover, the capacity retention characteristics were markedly improved by using the polymer hydrogel electrolyte. The effects of the polymer hydrogel electrolyte on the capacity retention characteristics were more remarkable at relatively high temperature. These results strongly suggest that the polymer hydrogel electrolyte has a potential applicability to the commercial Ni/MH batteries. © 2003 The Electrochemical Society. All rights reserved.

Bismuth‐Enhanced Electrochemical Stability of Cobalt Hydroxide Used as an Additive in Ni/Cd and Ni/Metal Hydride Batteries

For performance purposes, the electrochemically active positive electrode in Ni‐based rechargeable alkaline batteries consists of particles coated with CoOOH. The positive attributes of the CoOOH coating, however, vanish upon cycling because it transforms into or even through dissolution‐crystallization processes. The benefit of adding Bi‐based salts or bismuth oxide to prevent these phase transformations is presented. From chemical and electrochemical studies, coupled with potentiometric titration and ultraviolet‐visible spectroscopy, we demonstrate that the positive effect of Bi additives is twofold. First, Bi adsorption onto the Co surface modifies the CoOOH chemical reactivity and thereby its dissolution. Second, since bismuth forms Bi‐Co‐oxohydroxo complexes in solution, as experimentally proved, it delays precipitation of the and phases during cycling. Finally, an implementation of these findings toward the most efficient use of nickel positive electrodes containing Co‐based additives is shown. © 2000 The Electrochemical Society. All rights reserved.

Bismuth Contribution to the Improvement of the Positive Electrode Performances in Ni/Cd and Ni/MH Batteries

ABSTRACTIn this study we investigated the evolution of nickel hydroxide, which acts at the positive electrode of the Ni/Cd, Ni/MH and Ni/H2 alkaline batteries. We found that the addition of bismuth oxide in the course of the active material preparation prevents the dissolution-re-crystallization processes of the nickel hydroxide that are harmful to the electrode efficiency. From XRD and SEM studies, it is shown that treatment of the bismuth doped-nickel hydroxide by hydrogen in 5 N KOH electrolyte prevents metallic nickel formation. Moreover, it appears to stabilize the α-type nickel hydroxide structure, preventing its transformation into the β-Ni(OH)2 phase. Finally, an implementation of these findings towards the most efficient use of nickel positive electrodes is shown.

Degradation behavior of foamed nickel positive electrodes of Ni–MH batteries

The extrusion mechanism has been demonstrated to be the major cause for the capacity decay of the positive electrodes during cycling. However, based on our SEM and EPMA observations on cycled electrodes we found that some active material on the foamed nickel electrodes came off into scales especially as the electrodes cycled at 1C rate of discharge. This phenomena is suggested as another important cause for the capacity decay of positive electrodes and may be explained by the internal stress induced by the different volume change at the outer layer and the core due to phase and structure transformation during cycling.

99/02051 Electrochemical investigation of CrO 2.65 doped LiMn 2O 4 as a cathode material for lithium-ion batteries : Zhang, D. et al. J. of Power Sources, 1998, 76, (1), 81–90

The performance of a commercial-grade 1.2-V/6-Ah nickel/metal hydride cell is reported in terms of discharge characteristics and cycle life. The cell is comprised of compacted, metal hydride negative electrodes, made out of a stoichiometric AB2-Laves phase with nominal composition Zr0.5Ti0.5V0.6Cr0.2Ni1.2, and sintered nickel positive electrodes. The cell can withstand prolonged charge–discharge schedules with little deterioration in performance. The effect of varying discharge rate and temperature is also examined.

A commercial-grade 1.2-V/6-Ah nickel/metal hydride cell

The performance of a commercial-grade 1.2-V/6-Ah nickel/metal hydride cell is reported in terms of discharge characteristics and cycle life. The cell is comprised of compacted, metal hydride negative electrodes, made out of a stoichiometric $AB_2$ -Laves phase with nominal composition $Zr_{0.5} Ti_{0.5} V_{0.6} Cr_{0.2} Ni_{1.2}$ , and sintered nickel positive electrodes. The cell can withstand prolonged charge–discharge schedules with little deterioration in performance. The effect of varying discharge rate and temperature is also examined.

Mechanisms Causing Capacity Loss on Long Term Storage in NiMH System

ABSTRACTCapacity recovery after long term storage and loaded storage is a critical issue with the NiMH system since its inception. A measurable loss in capacity is observed when cells are stored for long periods of time or discharged deeply to zero volts. The different mechanisms that are known to cause self discharge and capacity loss after storage and loaded storage will be the focus of this paper. Capacity loss after long term storage involves two main events. One is self discharge which causes the open circuit voltage(OCV) of the cell to drop. Self discharge is caused by decomposition of NiOOH, migration of metal ions and possible degradation of separator. Self discharge can be prevented by using separators which are stable at high temperatures and pH and have good ion trapping capability. Various separator types and treatments can play an important role in inhibiting metal ions from migrating thus reducing self discharge. Self discharge during storage causes a severe suppression in the voltage of the foam positive electrode. This drop in voltage causes a breakdown of the cobalt conductive network in the nickel positive electrode. Reduction of high valence cobalt(III) which forms the electrode's conductive network takes place at these low voltages. A permanent breakdown in the conductive network results in low efficiency of the cell on consecutive charge and discharge cycles. In addition, the cobalt in its lower valence states can migrate away from the electrode into the separator causing shorts. These events effect the charge and discharge efficiency of these cells thereby resulting in capacity loss. Various mechanisms causing self discharge which affect capacity recovery after long term storage and loaded storage are discussed in this paper.

Performance characterization of sintered iron electrodes in nickel/iron alkaline batteries

A nickel/iron storage battery with a porous, sintered, iron negative electrode and a nickel positive electrode is a high power system by virtue of its low internal resistance. A dry-powder sintering procedure is used to fabricate negative and positive electrodes. Negative iron electrodes are activated with various salt solutions such as CdSO 4, BaCl 2, HgCl 2 and sulfur. Positive electrodes are impregnated with nickel hydroxide by a chemical method. Tests are performed in 10 Ah capacity nickel/iron cells and two types of activated iron electrodes are used. The present work deals with electrode fabrication, charge/discharge studies, self-discharge, temperature performance and cycle life. Finally, the best iron electrodes are coupled with nickel electrodes to obtain a 1.37 V, 75 Ah nickel/iron cell. The performance of this cell is discussed.

Development of the High Capacity Sintered Type Nickel positive Electrode

Development of the High Capacity Sintered Type Nickel positive Electrode

Alkaline poly(ethylene oxide) solid polymer electrolytes. Application to nickel secondary batteries

Water-containing and anhydrous alkaline PEO-based solid polymer electrolytes have been prepared, involving two different technologies. They exhibit a high ionic conductivity, and values up to 10 −3 S cm −1 are obtained for some compositions at room temperature. Conductivity studies and thermal analysis are presented, and the conductivity vs. temperature behaviour of each type of solid polymer electrolyte studied is discussed. Preliminary results are reported concerning the cyclability of cells involving a nickel positive electrode, and a cadmium or a zinc negative electrode.

On the performance of stabilized α-nickel hydroxide as a nickel-positive electrode in alkaline storage batteries

The internal resistance of a stabilized α-nickel hydroxide electrode is found to be lower than that of a β-nickel hydroxide electrode as shown from studies of the open-circuit potential-time transients at all states-of-charge. Nevertheless, the self-discharge rates of the former is higher. Gasometric studies reveal that the charging efficiency of the α-nickel hydroxide electrode is higher than that of the β-nickel hydroxide electrode.

On the performance of stabilized α-nickel hydroxide as a nickel-positive electrode in alkaline storage batteries

On the performance of stabilized α-nickel hydroxide as a nickel-positive electrode in alkaline storage batteries

Distribution of Nickel Hydroxide in Sintered Nickel Plaques Measured by Radiotracer Method during Electroimpregnation

Sintered nickel positive electrodes were prepared by electroimpregnating nickel hydroxide inside a porous nickel plaque in a nickel nitrate solution. The distribution of nickel hydroxide inside the plaque was measured using a radiotracer method with 63Ni as the radioactivity source. Autoradiography and β counting were used to follow qualitative and quantitative distributions, respectively, of the pore filling process. Relatively uniform distribution was observed at low current density, and the precipitation of extends to the center of the plaque. At high current density, most of the aggregated in the region just underneath the plaque surface, causing a somewhat nonuniform distribution. Nickel hydroxide also precipitates heavily on the surface of the plaque at high current density, reducing the penetration of electrolyte to the inside of the plaque.

Impedance of the sintered nickel positive electrode

Impedance measurements have been made on a mini electrode disposed between two large (identical) counter electrodes. A general mechanism is obtained for the electrode behaviour from the experimental data. The electrode reaction is two step and complex. Where comparison is possible agreement is obtained with earlier work.