Tubular negative electrode

Tubular Cells. Although the tubular nickel electrode invented by Edison is almost always combined with an iron negative electrode, a small quantity of cells is produced in which nickel in the tubular form is used with a pocket cadmium electrode. This type of cell construction is used for low operating temperature environments, where iron electrodes do not perform well or where charging current must be limited. 

Figure 3.26. Modelled main cell-potential loss terms. Ohmic bulk losses in electrolyte Act. an activation losses at negative electrode Act. cat activation losses at positive electrode. (Reprinted from S. Campanari and P. lora (2004). Definition and sensitivity analysis of a finite volume SOFC model for a tubular cell geometry. /. Power Sources 132,113-126. Used by permission from Elsevier.)...

The grids of both flat-plate and tubular batteries should not contain antimony or any other additive that may decrease the hydrogen overpotential of the negative electrode. Indeed, it is recommended that ultra-pure lead be used to manufacture both the grids and the active material in order to avoid the possibility of excessive self-discharge at either the positive or the negative plates. 

Both the positive and negative tubular and pocket current collectors are made of perforated nickel-plated steel. They are very robust and are virtually indestructible. The low energy density, poor charge retention, and poor low temperature performance, along with high cost of manufacture, have led to a decUne in use of the nickel-iron battery system. The negative electrode, or anode, is iron and the positive... 

The Ni-Fe batteries range in size from 5 Ah to over 1,200 Ah. The cell open circuit voltage of the Ni-Fe cell is 1.4 which drops quickly to 1.2 V during discharge. Tubular or pocket plate COTistructiOTis are used. Active materials of high purity are contained inside the perforated nickel-plated steel tubes or rectangular pockets. The active materials are irrm for the negative electrode and nickel oxide for the cathode and a KOH electrolyte. 

A similar experiment with a tubular pNa electrode at different depth of immersion was carried out in a pH 10.5 buffer (ethylenediamine) with different concentrations of sodium nitrate. For dilute sodium solutions, the potentials decreased to more negative values with increasing depths of immersion, at higher sodium ion concentrations in the same buffer solutions (above 1 M) (Figure 4), the slope changed to positive values. 

The lithium-copper oxide cells used in this investigation were made by SAFT and had a type specification LCOl. Each cell has a negative electrode of lithium metal, an electrolyte of lithium perchlorate in an organic solvent and a positive electrode of copper oxide and carbon. The cell is constructed in the form of a hollow tubular lithium central cylinder which is separated by a thin annular synthetic material from a concentric tubular copper oxide-carbon ring matrix enclosed by an outer steel can. Current collectors are attached to the lithium and steel cylinders. 

The positive and negative plates are separated by hard rubber or plastic pins called hair pins or hook pins, which fit into spaces formed by the tubular positive and flat negative electrodes. 

Energy densities currently being achieved are 20-30 Wh/kg (tubular plate electrodes) and 40-60Wh/kg (sintered plate electrodes). The positive plate comprises thick sintered nickel plates on a nickel plated substrate. The negative plate comprises a mixture of powdered iron and Fe30a. The electrolyte contains 1.2 to 1.3g/cm potassium hydrioxide containing 1-2% lithium hydroxide. The cells are vented. Synthetic fibres are used for separators. 

The negative current collector is a perforated nickel-plated steel pocket plate assembly. The tubes are produced from perforated nickel-plated strips that are wound to produce a tube. The tubular construction has one end crimped and the active material is poured into the open end in layers with nickel flakes. Alternatively, a machine automatically introduces the active material and tamps it into the pockets. After filling, the tubes/pockets are crimped and pressed into openings in the nickel-plated steel electrode frame. A similar process is used for the positive electrode. 

Jungner,in 1896, had developed the pocket electrodes to hold the finely divided electrode powders, while Edison used tubular electrodes for the positive and flat plates for the negative. The cell reaction is given below ... 

Tubular precipitators (Figure 3.4.24) have a discharge electrode placed in the center of the tube. The dust loaded air flows through the tube, becomes negatively charged and collects on the inside wall of the collecting tube. The dust is cleaned from the bottom of the tube. 

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