Active Material Of Positive Electrode Research Articles

Effect of cupric oxide addition on the performance of nickel electrode

Nickel hydroxide is widely used as the active material in positive electrodes of rechargeable alkaline batteries. In this paper, the effects of cupric oxide additive on the characteristics of the nickel electrode have been investigated. The results indicate that the addition of cupric oxide in the nickel electrode can prevent swelling of the nickel electrode during charging and thus prolong the cycle-life of rechargeable batteries. Cupric oxide additive can also promote the transformation from cobalt powder to β-CoOOH and make cobalt additive be well-spread on nickel hydroxide particles, thus facilitate the charging process in the initial stage.

Surface modification and electrochemical studies of spherical nickel hydroxide

Electroless cobalt on the surface of spherical nickel hydroxide has been used as a surface modifying method of active material for positive electrodes of rechargeable alkaline batteries. Cyclic voltammetric studies show that the electrodes exhibit higher oxygen overpotential and much more reversibility than ones of pure nickel hydroxide or nickel hydroxide with 5 wt.% cobalt added as a conductor. The discharge behaviour of the electrodes is also similar.

Stability enhancement of the CoOOH conductive network of nickel hydroxide electrodes

Nickel hydroxide is used as the electrochemically active material in positive electrodes of rechargeable alkaline batteries. Well-spread CoOOH is used as the conductive network to enhance the utilization of the nickel hydroxide. If the nickel hydroxide electrode is subjected to a negative potential it may display an enduring capacity loss due to an irreversible electrochemical reduction of CoOOH. In this paper it has been demonstrated that the addition of MnO 2 to nickel hydroxide pressed powder electrodes ensures 100% capacity retention after imposing reducing conditions.

Vanadium oxides in electrodes for rechargeable lithium cells

In principle, vanadium pentoxide can be used as an active material for positive electrodes in rechargeable lithium cells. Cyclability is possible when the discharge is limited to a value of y = 2.35 (in Li y V 2O 5). The cycling behaviour is comparatively good up to a discharge level of y = 1.

Li|LiI|iodine primary galvanic cell and Zn|ZnI 2|iodine secondary galvanic cell using poly(2,5-thienylene), poly(2,5-pyrrolylene), and their analogues as positive electrodes

Iodine adducts of chemically prepared poly(2,5- thienylene) show good electrical conductivity over a range of iodine content of 10–90 wt.%. The adducts serve as good active materials of positive electrodes of Li|LiI|iodine galvanic cells. Discharge curves of the galvanic cell at 500 kgω load show stable voltage (2.8–2.3 V) until about 85% of added iodine is consumed in the cell reaction. Poly(2,5-thienylene), poly(2,5-pyrrolylene), and their derivatives prepared both chemically and electrochemically are useful as materials for positive electrodes of Zn|ZnI 2|cation- exchange membrane|ZnI 2|iodine secondary cells. The cells using the polymers show about 100% current efficiency and 85% energy efficiency, and are rechargeable more than 200 times. Utilization of electric conducting π-conjugated polymers as electrodes of primary and secondary cells is a subject of recent interest [1–7]. Among the electric conducting polymers, those constituted of recurring 5-membered heterocycles have high stabilities against air and heat. They show good electric conductivity when doped with electron acceptor or donor ▪ and are suitable as electrodes of the cells. Two methods have been developed for the preparation of the polymers. Method 1: Transition metal catalyzed dehalogenation polycondensation of dihalo-compounds with magnesium or zinc [8–13]. e.g., ▪ Method 2: Anodic oxidation of thiophene, pyrrole, or their derivatives [14–21]. e.g., ▪ We now report utilization of the polymer as positive electrodes of Li|LiI|iodine primary and Zn|ZnI 2|- cation-exchange membrane|ZnI 2|iodine (abbreviated as Zn|ZnI 2|iodine) secondary cells.

Lithium-iodine solid electrolyte galvanic cells using iodine adducts of nylon-6 as active materials of positive electrodes

Iodine and nylon-6 form adducts containing 70–90 wt-% of iodine on heating at 115–145°C. The adducts have electrical conductivities ranging from 10 −7 to 10 −3 S cm −1 at 25°C, and the electrical conductivity increases with increasing content of iodine of the adduct. The activation energies of the electrical conduction for the adducts prepared at 115°C and containing 69.2, 81.8, 87.1, and 90.0 wt-% of iodine are 94.6, 67.0, 52.9, and 46.1 kJ/mol, respectively. Polyamides other than nylon-6 also form similar semiconducting adducts with iodine. IR and NMR spectroscopic analyses of the iodine—nylon-6 adducts indicate profound changes in the structure of nylon-6 on adduct formation and suggest the formation of a −CN +H species. The iodine-nylon-6 adducts prepared at 115°C and containing more than 82 wt-% of iodine serve as good active materials of positive electrodes in lithium-iodine solid electrolyte galvanic cells (outer diameter = 11.6 mm; outer thickness = 2.0 mm). The current efficiencies of the galvanic cells at 500 kΩ load are about 50% based on the iodine added. Discharge at 100 kΩ load gives lower current efficiencies. The galvanic cell has an internal resistance of about 5 kΩ at 25°C before discharge, and the internal resistance increases to about 100 kΩ at about 40% discharge. The dependence of the internal resistance during discharge have been determined.

Li|LiI|IODINE GALVANIC CELLS USING IODINE-POLY(2,5-THIENYLENE) ADDUCTS AS ACTIVE MATERIALS OF POSITIVE ELECTRODES

Abstract Iodine adducts of poly(2,5-thienylene) serve as good active materials of positive electrodes of Li|LiI| iodine galvanic cells. Discharge curves of the galvanic cells at 500 kΩ load show stable voltage (2.8–2.3 V) until about 85% of iodine added is consumed in the cell reaction.

Nb<sub>2</sub>O<sub>5</sub> as an Active Material of Positive Electrode for Nonaqueous Lithium Secondary Cells

Nb<sub>2</sub>O<sub>5</sub> as an Active Material of Positive Electrode for Nonaqueous Lithium Secondary Cells

Optimisation of active material for positive electrodes of NiCd accumulators

The conditions for the preparation of the active material for positive plastic-bonded electrodes of NiCd alkaline accumulators were investigated in order to obtain the maximum discharge capacity. It was shown that nickel hydroxide precipitated from a neutral medium is superior to that precipitated from a strongly alkaline medium. This, together with the choice of a conducting component and other conditions of preparation served as a basis for obtaining an active material which does not require an additional doping, e.g., with cobalt, its discharge capacity being comparable with the “classical” active materials doped with cobalt.

Properties of Mercury Oxide as an Active Material of Positive Electrode in Alkaline Storage Cell

Abstract (1) Mercury oxide (both red and yellow) can be used into the electrode plate of the alkaline accumulator in the pasted form by mixing silver oxide. (2) Its discharge characteristic curve varies in two stages, the first stage being caused by the discharge of silver oxide and the terminal voltage of about 0.95 volt, and the second stage being caused by mercury oxide. (3) Mercury oxide seems to be a considerably poor substance in the electrical conductivity and the mixing of silver oxide raises its electrical conductivity.