Two-pole electrode unit

<td>POLAND RZECZPOSPOLIIA CHINA</td><td>PATENT DESCRIPTION</td><td colspan="2"> 116452</td>

<td></td><td>Additional patent to patent no</td><td></td><td></td>

<td></td><td></td><td colspan="2">Int. Cl.</td>

<td></td><td>Reported: 22.02.78 (P. 204822)</td><td></td><td>H01M 4/00</td>

<td></td><td>Priority: 22.02.77 United States</td><td></td><td></td>

<td rowspan="3">OFFICE PATENT HALF-</td><td>America</td><td></td><td>READING ROOM</td>

<td>The application was announced: 23.10.78</td><td></td><td>Pałent Office tztcmpF et i</td>

<td>Patent description published: 28.02.1983</td><td></td><td> - -</td>

Inventor: Peter Carr

Patent Holder: Energy Development Associates, Madison Heights - (United States of America)

Bipolar electrode assembly and

The present invention relates to a bipolar electrode assembly.

Known batteries with high energy density allow to obtain 25 W from 1 kilogram. It is known, for example, from US Patent No. 3,713,888 a battery that has a metal halide halogen hydrate system. The use of such a system is associated with the use of corrosive material such as chlorine and aqueous chlorine and electrolyte. metal-halide. Such a system is known from US Patent Nos. 3813301 and 3909298.

In the bipolar electrodes disclosed in the aforementioned patents, the faces of two separate electrodes are joined together to form the desired bipolar electrode assembly.

A number of cells containing bipolar electrode assemblies can be connected in series to a battery. The batteries can be connected in series to increase the voltage, in parallel to increase the current value or in series in parallel to increase both parameters. However, the distance between the links is very small (e.g. 3.54 cm for 4 links), and causes losses due to eddy currents and / or dendritic effect.

The problem associated with short distance between links can be in most cases. 2 solved by the use of a new set of bipolar electrodes in which electrical conduction occurs in the width direction rather than through thickness. The use of such₅ assembly can increase the effective distance between links from 0.75 cm to about 8.35 cm or more. In known links, the distance between the opposite faces is approximately 0.2 cm.

. ₁₀ The object of the invention is to develop a construction of a bipolar electrode assembly in which the effective distance between the cells allows limiting the losses due to eddy currents and the dendritic effect.

₁₅ The object of the invention is achieved by the fact that the bipolar electrode assembly comprises an electrically conductive, chemically inert, substantially flat wall having first and second opposing faces and each surface₂₀ frontal chni has more appropriate parallel channels,. wherein the channels in the first surface are displaced relative to the channels in the second face, substantially parallel electrodes having edges located inside the corresponding channels of the face, and extended substantially perpendicular to the plane of the chemically inert wall and a third electrode having a first edge located inside the channel

H face and extended basically

116 452

116 452 perpendicular to the plane of the chemically inert wall.

The channels in the first and second face are symmetrical.

The third electrode is a porous electrode.

The porous electrode has an internal cavity adapted to be supplied with electrolyte from outside the electrode.

The electrolyte supply tube connects the space outside the porous electrode to the bottom of the internal cavity.

The assembly may also include a greater number of first porous electrodes, each electrode having a first edge located within the corresponding channel in the second face and extended substantially perpendicular to the surface of the chemically inert wall.

The assembly further includes a greater number of second porous electrodes, each porous electrode having a first edge disposed within the corresponding channel in the first face and extended substantially perpendicularly to the surface of the chemically inert wall. .

For convenience, the present invention will be described with reference to the zinc chloride electrolyte system described in detail in U.S. Patent No. 713838, although the present invention is not limited to such a system.

The object of the invention is shown in the embodiment of the drawing in which Fig. 1 is a perspective view of a bipolar electrode assembly according to the invention in Fig. 2 - a battery consisting of more bipolar electrode assemblies according to the invention in perspective and Fig. 3 a battery according to the invention in cross section.

Figure 1 shows a bipolar electrode assembly according to the invention. Each electrode has an electrically conductive, chemically inert, substantially flat wall 1 which has opposite faces 2, 3, The face plane 2 is usually parallel to the face 3. The face 2 has a series of channels 4 which are essentially parallel and preferably symmetrically arranged along the face 2. Similarly, the face 3 comprises a series of channels 5 which are substantially parallel and preferably symmetrically located along the face 3. The channels 4 on the face 2 are displaced relative to the channels 5 on the face 3 * Preferably, each channel 5 is arranged symmetrically between a pair of adjacent channels 4 and vice versa.

Wall 1 can be made of any suitable electrically conductive material that is chemically inert, i.e. inert to electrolyte and other chemical activities. anyone he comes into contact with. In this way, the wall 1 can be made of graphite, a valve metal such as titanium and similar materials. Ścia-₍ na 1 is preferably impermeable to electrolyte and gas.

The bipolar electrode assembly includes at least two electrodes 6, which are made of from₅ appropriate material such as fine graphite. In the zinc / chlorine / zinc system, the chloride electrodes 6 are zinc electrodes. The electrodes 6 are substantially rectangular. One edge of the electrode 6 is located inside corresponding to J '^ej a channel 4 of the face 2 of the wall 1 such that the electrode 6 is electrically connected to the wall 1.

The assembly comprises at least one substantially rectangular electrode 7, of which one edge is ₁₅ located inside the corresponding channel 5 in the face 3 of the wall 1. In the metal halide battery the electrode 7 is preferably porous and is a chlorine electrode. The electrode 7 can be made of any suitable material such as porous graphite, such as UCC PG-60 and Airco Speer 37-G or porous noble metal, catalyzed valve metal such as ruthenised titanium.

The edges of the electrodes 6 inside the corresponding channels 5 are held by suitable means. For example, the edges can be held in their corresponding channels by means of glue, plasma spray at the point of contact or weld. It is advantageous if the thickness of the electrode 30 is slightly greater than the width of the corresponding channel. As a result of pressing the electrode into the channel, the pressure generated holds the electrode in position.

Adequate pressure on the electrodes to the corresponding channels is a simple and reliable method of connection that results in low contact resistance.

In the preferred embodiment shown in Fig. 1, the electrode 7 comprises a cavity 8 * Kon40, this structure can be made in a variety of ways, for example by making two suitable electrode halves that are connected along the edge with a non-conductive permanent mask or by shaping and joining the halves. electrodes with each other. The cavity 8 is an electrolyte fed space. The electrodes 7 contain equals ventilation holes for gas (not shown).

To achieve uniform electrolyte separation 50 between the individual electrodes 7, each electrode comprises a small diameter tube 9, which is connected by a collector, acting as a flow control hole. Tubes 9 allow electrolyte to flow from the upper conduit 10 down to the bottom 55 of the cavity 8, since the cell bottom is preferably fed at this point. This assembly minimizes eddy current losses. · Electrolyte is supplied to conduit 10 from tank 11.

The bipolar electrode assemblies are connected into eo batteries as shown in FIG. 2. The chemically inert wall 1 of each bipolar electrode assembly is parallel to the wall Γ of the adjacent bipolar electrode assembly. With the exception of the last electrode in each cell, each electrode 7 that extends from the face 3 'substantially perpendicular to the wall surface is located between, a pair of adjacent zinc electrodes 6' that are located substantially perpendicular to the plane of the face 2 'of the adjacent 1 'walls and vice versa. In other words, the electrodes 7 of one bipolar electrode assembly intertwine with the zinc electrodes of adjacent bipolar electrode assemblies.

Each electrode is extended almost to the chemically inert wall of the adjacent bipolar electrode assembly, such that a small gap is formed between the end of the electrode and the wall 1 of the adjacent assembly. ¹

The number of bipolar electrode assemblies used to form the battery can vary. The furthest bipolar electrode assembly only contains the zinc electrode 6 protruding from the channel 4 in the frontal surface 2 or only the electrode 7 from the channel 5 in the frontal surface 3. The outer face of the end chemically inert wall i.e. the surface that does not support the electrodes may have channels, but preferably it is flat, which allows convenient placement of the clamps 12 on it.

The electrodes between each pair of walls 1 are cells. The capacity of the cell can easily be increased by extending the wall 1 and attaching more electrode assemblies. Preferably, all the electrodes at the ends of each cell are zinc electrodes 6 or electrodes 7. This assembly limits the possibility of a short circuit between the outer parts of the electrodes.

As shown in Fig. 3, individual bipolar electrode assemblies are disposed on the corresponding nonconductive cell bottom 13. The chemically inert walls 1 are connected to the bottom 13 by suitable means such as titanium staples and dowels on glass plates. A porous Teflon sealing material is placed between the glass plate and the electrode to form a good seal. A small gap is formed between the end of each electrode and the chemically inert wall adjacent to it. A suitable chemically inert sealant 14 is supplied to the gap adjacent to the outer electrode. Each electrode in the stack is essentially open to the space in which the gas released from the cells collects. If the battery is a closed battery, there should be adequate space inside the housing for the released gas. Alternatively, when joining individual bipolar electrode assemblies on a base plate, individual components can be formed by vacuum to form an open box with a seal made between the bottom and two sides of the walls 1.

In the long battery life it is necessary to combine individual cells. As shown in Fig. 1, this can be done by connecting the electrodes so that a small gap exists between the lower edges of the electrodes and the lower edge of the wall 1.

However, to retain the electrolyte in the cell, the outer electrodes must necessarily reach the bottom along their entire length and be sealed to a non-conductive base for example with a porous Teflon sealant.

During operation, the electrolyte flows in space ₅ between the electrodes above the entire electrode width. As a result, gas is released from the internal electrode gap and minimal electrolyte agitation. In cells without separators, excitation of electrolyte inside the space₁₀ between the electrodes clearly reduces the efficiency of the cell.

In each battery cell, all electrolyte fluxes flowing from the interconnected spaces between the electrodes flow above the electrode ends ₁₅ or the tank wall links into a common tank (not shown).

One way of separating the electrolyte between the cells is shown in Fig. 1 where the chemically inert walls 1, which are the cell walls, ₂₀ have a slightly higher height than the electrodes.

The electrical insulation between the cells is protected by high resistance of the electrolyte layer flowing over the end of the electrode or the inner wall or set in a different way.

A typical battery constructed in accordance with Figs. 2 and 3 may contain 10-12 bipolar comb-type electrode assemblies. Each unit has a chemically inert wall 1 about 10 cm high and about 12 cm long. Each first face 2 may have 14 tangential electrodes 6 extended about 8 cm from the face 2, whose top edge is located about 2.54 cm below the top edge of the wall L Each second face b 3 has 12 chlorine electrodes 7 extended about 8 cm from · face 3, where the upper edge of each is located about 2.54 ctn 'below the top of wall 1 and the bottom edge of each electrode is located about 0.3 cm above the bottom edge of wall 1. The bottom edge of each zinc electrode 6 except for the outer electrodes 6 is located about 0.3 cm above the lower edge of a chemical inert wall 1.

₄₅ It is understood that various changes and modifications may be made to both types of bipolar comb electrodes and the battery described herein. The above examples are provided for the purpose of illustrating the invention only.