Electrodes Of Alkaline Batteries Research Articles

Revitalizing Iron Redox by Anion-Insertion-Assisted Ferro- and Ferri-Hydroxides Conversion at Low Alkalinity.

Iron hydroxides are desirable alkaline battery electrodes for low cost and environmental beneficence. However, hydrogen evolution on charging and Fe3O4 formation on discharging cause low storage capacity and poor cycling life. We report that green rust (GR) (Fe2+4Fe3+2 (HO-)12SO4), formed via sulfate insertion, promotes Fe(OH)2/FeOOH conversion and shows a discharge capacity of ∼211 mAh g-1 in half-cells and Coulombic efficiency of 93% after 300 cycles in full-cells. Theoretical calculations show that Fe(OH)2/FeOOH conversion is facilitated by intercalated sulfate anions. Classical molecular dynamics simulations reveal that electrolyte alkalinity strongly impacts the energetics of sulfate solvation, and low alkalinity ensures fast transport of sulfate ions. Anion-insertion-assisted Fe(OH)2/FeOOH conversion, also achieved with Cl- ion, paves a pathway toward efficient utilization of Fe-based electrodes for sustainable applications.

Research of Nanomaterials as Electrodes for Electrochemical Energy Storage.

This paper has experimentally proved that hydrogen accumulates in large quantities in metal-ceramic and pocket electrodes of alkaline batteries during their operation. Hydrogen accumulates in the electrodes in an atomic form. After the release of hydrogen from the electrodes, a powerful exothermic reaction of atomic hydrogen recombination with a large energy release occurs. This exothermic reaction is the cause of thermal runaway in alkaline batteries. For the KSL-15 battery, the gravimetric capacity of sintered nickel matrix of the oxide-nickel electrode, as hydrogen storage, is 20.2 wt%, and cadmium electrode is 11.5 wt%. The stored energy density in the metal-ceramic matrix of the oxide-nickel electrode of the battery KSL-15 is 44 kJ/g, and in the cadmium electrode it is 25 kJ/g. The similar values for the KPL-14 battery are as follows. The gravimetric capacity of the active substance of the pocket oxide-nickel electrode, as a hydrogen storage, is 22 wt%, and the cadmium electrode is 16.9 wt%. The density of the stored energy in the active substance oxide-nickel electrode is 48 kJ/g, and in the active substance of the cadmium electrode it is 36.8 kJ/g. The obtained results of the accumulation of hydrogen energy in the electrodes by the electrochemical method are three times higher than any previously obtained results using the traditional thermochemical method.

Breakdown and Reformation of Birnessite in Rechargeable, Bismuth Modified MnO2 Alkaline Batteries

Rechargeable Zn-MnO2 alkaline batteries have been identified as a viable option for the modernization of grid scale energy storage due to their projected cost (<$100/kWh), scalability, and safer components when compared to non-aqueous alternatives.1 For this system to reach its maximum capability, the full Mn4+/2+ redox couple must be reversible over thousands of cycles with high mass loading. This was successfully demonstrated with the incorporation of various electrode constituents which alter the fundamental discharge and charge process of MnO2 to Mn(OH)2.1 Using non-destructive, synchrotron diffraction techniques, we detail the effect of Bi on the breakdown and reformation of birnessite (\U0001d6ff-MnO2) during cycling. Further spectroscopic evidence including Raman and X-ray absorption spectroscopy during cycling also provides crucial insights into amorphous phases and variations in redox activity, with and without additives.Early demonstrations of Bi3+ containing constituents with MnO2 in alkaline batteries increased the cyclability of these systems up to hundreds of cycles with low mass loading.2,3 Later investigations followed up by hypothesizing the presence of Bi3+ could potentially catalyze the reduction of Mn3+ to Mn2+ and that upon subsequent charge promotes the formation of a layered, birnessite, MnO2 structure.4 The quick reduction of Mn3+/2+ is critical because the presence of Mn3+ is associated with the irreversible phase change to the Mn3O4 spinel structure.5 Figure 1 shows the birnessite (001) reflection at ~7.1 Å rapidly shift to lower d-spacings upon discharge until ~6.9 Å then directly convert to Mn(OH)2 where the corresponding ~4.8 Å reflection appears. Notably, no crystalline intermediates such as MnOOH or Mn3O4 form during cycling. Also, upon charge the birnessite (001) reflection does not appear until the third potential plateau even though the Mn(OH)2 (001) reflection fades linearly until the end of charge. Due to these observations, further spectroscopic techniques were used to probe these reactions. Using operando Raman spectroscopy we observed a limited formation of an amorphous Mn3O4 during discharge and a disordered birnessite phase formation occurring on the second plateau of charge in the presence of Bi3+. These investigations provide new insight into the intermediates and formation mechanisms of Mn-based alkaline battery electrodes in the presence of Bi2O3.The presence of both Cu and Bi additives are necessary to stabilize the reversible processes occurring during electrochemical cycling. However, the synergistic relationship between Cu and Bi is not extensively investigated. Previous synchrotron XANES and XRF mapping showed that the Cu2+/0 redox couple was occurring during the Mn3+/2+ reduction. It was hypothesized that the Cu acts as a redox mediator and rapidly forms the Mn2+ species during discharge.6 Here we use a X-ray absorption spectroscopy quick scanning to monitor the Mn, Bi, and Cu redox activity which are all relating to the possible mediation of Mn reduction and oxidation. Using multiple techniques, we provide a complete understanding of the role of both bismuth and copper containing constituents on the redox transitions of MnO2 in alkaline electrolyte. Wholistic investigations combining multiple operando techniques are critical to the development of rechargeable alkaline batteries by advancing the fundamental design of these systems. Figure 1 (a) Operando X-ray diffraction data between 3-7.5 Å of the first cycle of Bi2O3-modified birnessite electrode in KOH electrolyte. (b) Corresponding galvanostatic discharge and charge at a rate of C/3. (c) Lattice parameter ‘c’, the interlayer spacing, of the birnessite phase during the first cycle. (d) The relative peak intensities of the birnessite and Mn(OH)2 (001) reflection during the first cycle.

A Low-Cost Iron-Based Current Collector for Alkaline Battery Electrodes

The use of three-dimensional porous nickel foam as the current collector of the nickel hydroxide electrode adds significantly to the cost of the nickel-based alkaline rechargeable batteries. Although iron is considerably less expensive than nickel, iron corrodes at the operating potential of the nickel hydroxide electrode. We have found that a 70–100 nm thick thermal coating of cobalt ferrite spinel protects the iron from corrosion. Such a coated iron substrate was found to be stable against corrosion even when polarized anodically at 10 mA cm−2 in 30% potassium hydroxide electrolyte for 1000 h. While the thermal coating of cobalt ferrite protected iron against corrosion, incorporation of lithium ions into the coating was found to enhance the electrical conductivity of the coating. XPS and EXAFS studies confirmed that the enhanced conductivity resulted from an increase in the population of Co3+ in the ferrite spinel lattice. An inexpensive iron (steel) substrate protected by such a coating when used as a nickel hydroxide battery electrode exhibited a specific capacity of 0.25 Ah g−1 at C/5 discharge rate, comparable to a nickel hydroxide electrode based on a relatively expensive nickel foam substrate. The steel-based electrode also exhibited no noticeable degradation over 150 cycles at C/2 rate. This demonstration of a robust and economical steel substrate presents a unique opportunity for reducing the cost of the nickel hydroxide battery electrode in alkaline batteries.

Al2O3 Coatings on Zinc for Anti-Corrosion in Alkaline Solution by Electrospinning

The severe corrosion accompanied with hydrogen evolution reaction has become the main obstacle restricting the utilization of zinc as an electrode in alkaline batteries. Al2O3 coating helps control the corrosion of zinc in alkaline solution. Herein, a stable Al2O3 coating is fabricated through facile electrospinning from Al(NO3)3 as an efficient anti-corrosion film on zinc. The electrospinning technique facilitates uniform dispersion of Al2O3 particles, therefore the corrosion inhibition efficiency could be up to 88.5% in this work. The Al2O3 coating prevents direct contact between zinc and the alkaline solution and minimize hydrogen evolution. Further, the effects of the thickness of Al2O3 coating on corrosion behavior of zinc are investigated through hydrogen evolution reaction, Tafel polarization, and impedance test. The results show that the thicker Al2O3 coating possessed better corrosion inhibition efficiency due to the higher corrosion resistance and lower porosity. The 18 μm Al2O3 coating on zinc provides corrosion current density of 60.6 mA/cm2, while the bare zinc substrate delivers as much as 526.3 mA/cm2.This study presents a promising approach for fabricating Al2O3 coating for corrosion-resistant applications.

Exploring highly porous Co2P nanowire arrays for electrochemical energy storage

Abstract Controllable synthesis of mesoporous conductive metal phosphide nanowire arrays is critical for developing highly-active electrodes of alkaline batteries. Herein we develop a simple combined strategy for rational synthesis of mesoporous Co 2 P nanowire arrays by hydrothermal-phosphorization method. Free-standing mesoporous Co 2 P nanowires consisting of interconnected nanoparticles of 10–20 nm grow vertically to the substrate forming arrays. High electrical conductivity and large porosity are obtained in the arrays architecture. When characterized as the cathode of high-rate alkaline batteries, the designed Co 2 P nanowire arrays are proven with good electrochemical performance with a large capacity (133 mAh g −1 at 1 A g −1 ), stable cycling life with a capacity retention of almost 100% after 5000 cycles at 10 A g −1 owing to the mesoporous nanowire structure with short ion/electron transport path. Our synthetic approach can be useful for construction of other porous metal phosphide arrays for energy storage and conversion.

S, N-Co-Doped Graphene-Nickel Cobalt Sulfide Aerogel: Improved Energy Storage and Electrocatalytic Performance.

Metal sulfides are commonly used in energy storage and electrocatalysts due to their redox centers and active sites. Most literature reports show that their performance decreases significantly caused by oxidation in alkaline electrolyte during electrochemical testing. Herein, S and N co‐doped graphene‐based nickel cobalt sulfide aerogels are synthesized for use as rechargeable alkaline battery electrodes and oxygen reduction reaction (ORR) catalysts. Notably, this system shows improved cyclability due to the stabilization effect of the S and N co‐doped graphene aerogel (SNGA). This reduces the rate of oxidation and the decay of electronic conductivity of the metal sulfides materials in alkaline electrolyte, i.e., the capacity decrease of CoNi2S4/SNGA is 4.2% for 10 000 cycles in a three‐electrode test; the current retention of 88.6% for Co—S/SNGA after 12 000 s current–time chronoamperometric response in the ORR test is higher than corresponding Co—S nanoparticles and Co—S/non‐doped graphene aerogels. Importantly, the results here confirm that the Ni—Co—S ternary materials behave as an electrode for rechargeable alkaline batteries rather than supercapacitors electrodes in three‐electrode test as commonly described and accepted in the literature. Furthermore, formulas to evaluate the performance of hybrid battery devices are specified.

Effect of Sulfide Additives on the Discharge Characteristics of Iron Electrodes in Alkaline Batteries

Iron-based rechargeable alkaline batteries such as nickel-iron and iron-air are attractive candidates for large-scale energy storage applications because of the low cost and robustness of the iron electrode. [1] We have recently reported significant advancements in the charging efficiency and discharge rate capability of iron-based alkaline battery electrodes. [2, 3] By using carbonyl iron as the electrode active material and by including additives such as bismuth sulfide and bismuth oxide, charging efficiencies greater than 90% have been demonstrated. To improve the utilization of the iron electrode and achieve high-discharge-rate capability, sulfide additives are necessary. The importance of sulfide additives in de-passivating the iron electrode during discharge has been reported in the literature. [4-6] Various sulfide-based additives such as sodium sulfide, bismuth sulfide, lead sulfide, and iron sulfide have been successfully employed as de-passivating agents. However, a mechanistic understanding of the effect of different sulfide additives on the polarization characteristics of the iron electrode during discharge is not available. The goal of the present study is to understand the effect of different sulfide additives on the anodic polarization, impedance response, and discharge characteristics of the iron electrode. Iron electrodes were prepared by mixing carbonyl iron powder with polyethylene binder and hot-pressing the mixture onto a nickel grid. In some cases, additives such as bismuth sulfide, bismuth oxide or iron sulfide in the concentration range of 1-10 wt.% were added to the powder mixture prior to pressing. Electrochemical testing was performed in a three-electrode configuration with a mercury/mercuric oxide (MMO) reference electrode and nickel oxide counter electrodes. The capacity of carbonyl iron electrodes with various sulfide additives at different discharge rates is shown in Figure 1. In the presence of bismuth sulfide additive, the discharge capacity of the iron electrode at the 1C rate was 0.2 Ah/g – significantly higher compared to that of the ‘sulfide-free’ iron electrode. With iron sulfide additive, the iron electrode was able to sustain discharge rates as high as 3C for similar levels of electrode utilization. (Figure 1) The results from the discharge rate capability experiments are consistent with the polarization behavior of the iron electrodes with different additives (Figure 2). When a ‘sulfide-free’ iron electrode is polarized positive to -0.85 V, the discharge current decreased signifying the onset of passivation (Figure 2). However, when sulfide additives are present, the polarization curves do not show any current limitation due to electrode passivation. The amount of charge required for the iron electrode to undergo passivation has been measured at various states of charge. Analysis of this data is anticipated to provide insight into the process of passivation. An understanding of the effectiveness of various sulfide additives in de-passivating the iron electrode and improving the discharge rate capability will also be presented. Acknowledgement: The research reported here was supported by the U.S. Department of Energy ARPA-E (GRIDS program, DE-AR0000136), the Loker Hydrocarbon Research Institute, and the University of Southern California.

Enhancing the Performance of the Rechargeable Iron Electrode in Alkaline Batteries with Bismuth Oxide and Iron Sulfide Additives

Iron-based alkaline rechargeable batteries have the potential of meeting the needs of large-scale electrical energy storage because of their low-cost, robustness and eco-friendliness. However, the widespread commercial deployment of iron-based batteries has been limited by the low charging efficiency and the poor discharge rate capability of the iron electrode. In this study, we have demonstrated iron electrodes containing bismuth oxide and iron sulfide with a charging efficiency of 92% and capable of being discharged at the 3C rate. Such a high value of charging efficiency combined with the ability to discharge at high rates is being reported for the first time. The bismuth oxide additive led to the in situ formation of elemental bismuth and a consequent increase in the overpotential for the hydrogen evolution reaction leading to an increase in the charging efficiency. We observed that the sulfide ions added to the electrolyte and iron sulfide added to the electrode mitigated electrode passivation and allowed for continuous discharge at high rates. At the 3C discharge rate, a utilization of 0.2 Ah/g was achieved. The performance level of the rechargeable iron electrode demonstrated here is attractive for designing economically-viable large-scale energy storage systems based on alkaline nickel-iron and iron-air batteries.

Production of nickel sulfate single crystals in processing of nickel oxide electrodes of alkaline batteries

[NiSO4(H2O)n] single crystals were grown by slow cooling and evaporation of a solution for sulfuric acid leaching of the active paste of a nickel oxide electrode from a spent alkaline battery. The crystals were studied by X-ray phase analysis in two measurement configurations (transmission and Bragg-Brentano focusing).

Effect of synthesis conditions on characteristics of the precursor material used in NiO·OH/Ni(OH) 2 electrodes of alkaline batteries

The synthesis of nickel hydroxide occurs by many stages. When the precipitating reagent is NH 4OH solution, the precipitation of nickel hydroxide occurs between pH 8.0 and 8.6. For pH between 8.6 and 10.0, a soluble complex such as [Ni(NH 3) 6] 2+ is formed. The precipitation of nickel hydroxide happens again after the pH equals 10.0. Finally, there occurs the ageing of α-Ni(OH) 2. A mixture of α-Ni(OH) 2 and β-Ni(OH) 2 phases is formed when the solid state reaction is not totally completed. One adsorbed layer becomes very hard with the exit of the water intercalated in the α-Ni(OH) 2. In presence of KOH solution occurs the formation and the ageing of α-Ni(OH) 2. Synthesis was characterized by the following techniques: X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), differential thermal analysis (DTA) and gravimetric thermal analysis (GTA), and specific surface area and UV–vis spectroscopy.

Features of impregnation of nickel metal-ceramic porous supports for electrodes of alkaline batteries

The features of nickel oxidation in impregnation of nickel metal-ceramic porous supports for electrodes of alkaline batteries, which ensure their fabrication in a shorter time, were determined.

A Conductive Additive for Positive Electrodes of Alkaline Batteries: Structural, Physicochemical, and Electrochemical Evaluation of

For the first time, materials were synthesized at a very low temperature, below . The influence of synthesis parameters, such as temperature and time of reaction, on the structure and conductivity of the material was investigated. It was shown that these materials contain structural defects, such as stacking faults and lithium vacancies, which lead to a good electronic conductivity of these materials as compared to classical high-temperature materials. The time and temperature of reaction decrease the amounts of stacking faults in the materials. However, lithium intercalation can occur during a long-time synthesis, leading to a decrease in conductivity of the material. If process parameters are conveniently chosen, a material with a conductivity of around can be obtained and used with success as a conductive additive in positive electrodes of alkaline batteries. The major advantage of this new additive is that prevents the loss of capacity of alkaline cells at low voltage, in the whole potential window of the positive electrode in alkaline batteries.

The Outcome of Cobalt in the Nickel–Cobalt Oxyhydroxide Electrodes of Alkaline Batteries

The evolution of cobalt hydroxide used as a coating for nickel hydroxide electrodes has been studied as a function of the redox potential window and upon cycling. From both chemical and electrochemical studies, it is shown that (i) upon deep discharges cobalt tends to migrate from the coating to the current collector and (ii) upon heavy cycling in the limited 1–1.4V potential range a complete reorganization of the active material occurs. In the latter case, using X-ray diffraction, electron microscopy, and potentiodynamic intermittent technique, we identified the formation of a Ni1−xCox(OH)2(CO3)z·rH2O-type phase through dissolution reprecipitation processes involving both cobalt and nickel species. From these findings, the conditions required to preserve the benefits of cobalt additives are given.

Nickel hydroxide powder for NiO·OH/Ni(OH) 2 electrodes of the alkaline batteries

In the nickel hydroxide synthesis, the β-Ni(OH) 2 phase grows after total α-Ni(OH) 2 aging. A mixture of α-Ni(OH) 2 and β-Ni(OH) 2 phases is formed when a part of α-Ni(OH) 2 suffers aging. Galvanostatic oxidation of the α/β-Ni(OH) 2 produced by chemical synthesis formed a new type of active material. On discharge, it presented higher capacity than active material produced from β-Ni(OH) 2. Therefore, α/β-Ni(OH) 2 is a promising material for β-Ni(OH) 2 substitution, as a alternative precursor material used in the positive electrodes of alkaline batteries. Anions of the solution and water molecules are present in the nickel hydroxide powder. This is result of the synthesis method developed here. The characterization of the precursor material is determined with help of: X-ray diffraction, thermal analyses, Fourier transformation infrared spectroscopy, specific superficial area and electron scanning microscopy.

An electrochemical and morphological study of the effect of temperature on the restructuring and loss of capacity of alkaline battery electrodes

An electrochemical and morphological study of the effect of temperature on the restructuring and loss of capacity of alkaline battery electrodes

Temperature limitations of primary and secondary alkaline battery electrodes

Temperature limitations of primary and secondary alkaline battery electrodes

Temperature Limitations of Alkaline Battery Electrodes

The study described here is concerned with possible temperature limitations in Ni-Fe and Ni-Zn aqueous alkaline battery systems in the temperature range -20°C to 120°C. Thermodynamic studies involved the calculation of potential/concentration relationships for concentrated solutions. Kinetic studies have employed potential step and sweep, rotating ring disk and ac impedance methods. The principal temperature limitation of Ni appears to be reduced coulombic efficiency at high temperature as a result of the coevolution of oxygen at a high state of charge. The irreversible component of charging also increases immediately following prolonged discharge of Ni. The temperature limitation of the negative electrode materials, Fe and Zn, are more serious and more complex than those for Ni. In addition to the effects of increased hydrogen evolution, oxidative and reductive dissolution processes may substantially reduce the coulombic efficiency of Fe electrodes at 7>80°C. At r^O°C, charge/discharge kinetics of Fe become limited by the resistance of a residual surface oxide film. Discharge of Zn electrodes also is severely curtailed at reduced temperatures by reduced dissolution current and the premature onset of passivation. Under potentiostatic or high load conditions, zinc electrodes undergo an oscillatory activation/passivation process within a defined region of potential. This potential region increases with increasing temperature.