IL101401A - Apparatus for generating direct current - Google Patents

Description

METHOD AND- APPARATUS FOR GENERATING DIRECT CURRENT THE APPLICANTS :- 1. Lou ROZEANU 6, Harakafot St. 6 niapin aim Haifa. .na>n 2. Jacob HERBST oo:nn -ip " .2 115 , Sweden St . 115 n ·» i n? mm Haifa . . na > n 3. Ilan HERBST 115, Sweden St. 115 ,Ό*τ..«> mm Haifa . .na>n 4. Ophir HERBST Domn ~i 3iN .4 115, Sweden St. 115 mi:.© mm Haifa. .na">n METHOD AMD APPARATUS FOR GENERATING DIRECT CURRENT BACKGROUND OF THE INV5NTIOW The invention relates to - *—BM:. Lh^el rrnd a light-weight, chemo-mechanical apparatus for generating direct current. It relates particularly to a D-C generator having an adjustable, continuous output, contrary to the electrochemical cell wherein the initial EMF is reduced during supply of current due to polarization of the electrodes.

One of the urgent technical problems is development of an electro-chemical cell or battery of low weight and relatively high discharge for use in vehicles, which should replace the internal combustion engines used up to date. It is a fact that combustion of fuel in motor vehicles and in all other ways not only makes life insupportable in towns, but causes an increase of carbon dioxyde in the atmosphere, while destroying the protective ozone layer in the stratosphere. This is the reason for trying to find ways for reducing fuel consumption to a minimum by supplying alternative power sources, at least for motor vehicles which are a major source of air pollution, especially in large cities. Even, if an electro-chemical low-weight, rechargeable battery could be developed as a replacement for a combustion engine, it would require electric: current supplied by a power station which, again, burns fossil fuel and thereby emits air polluting chemicals. On the other hand, there already exist battery-driven vehicles, but they are generally limited to a travel distance of about 50 km per charge, since the heavy weight of the batteries allows only a limited number to be installed in each vehicle.

It is, therefore, the main object of the present invention to provide a source of electric current which is not dependent on fuel combustion, but generates direct current by electro-chemical reaction.

It is another object to provide a D-C generating device of low weight suitable for installation in a motor vehicle allowing it to travel a considerable distance without recharging or exchange of the device.

The device should provide electric current by electrochemical reaction without the effect of polarization of electrodes as in conventional batteries, thereby permitting a higher EMF to be obtained from each unit.

It is still another object to provide a D-C generating device of simple design and with means for controlling its output in accordance with the power requirements of the vehicle at each moment.

It is an additional object to provide a current generating device of large output per weight unit, which will produce the required energy at low cost, possibly at lower cost than a combustion engine at present fuel prices.

And it is a final object to provide such device at low cost so as not to raise the total price of a motor vehicle beyond its present cost.

SUMMARY OF THE INVENTION The D-C generating device of the present invention essentially comprises two strips of a conductive material representing a respective anode and cathode moving at substantially identical velocity from non-contacting alignment into contact along a predetermined stretch of travel with an electrolyte continuously supplied between the two strips, these strips together with the electrolyte constituting an electro-chemical cell. Current collectors or brushes are provided in the contact stretch area on the outside of the two strips and serve to conduct the current to an electric motor or other consumer.

The two strips which are thin and of a chemically passive material are wound off two first reels ahead of the contact stretch and are wound up on two second reels beyond the contact stretch, while a number of rollers support the strips on both sides of the contact stretch. The strips are coated on their respective contact sides with an anode and cathode material respectively which is consumed during the passage through the contact stretch, permitting the re-use of the strips after cleaning and re-coating. A preferred strip material is stainless steel which may be initially coated with a non-corroding metal such as a noble metal, and both strips are coated with a very thin layer of anode a'nd cathode material. Any two materials generally used in commercial battery systems may be employed as long as they can be applied to the steel strips in the form of a very thin layer as expressed in a few microns. An electrolyte of liquid or easily flowing, pasty constitution is applied inbetween the two strips, which is then squeezed into a very thin layer and reacts with the cathode and anode material.

A preferred chemical coating is lithium as anode and thionyl chloride (SOC^) as elecrolyte for interaction, the latter being supplied in easily flowing paste form from a container and poured between the two strips prior to their entering the contact zone.

Simultaneous linear velocity of the two strips is obtained by means of an electric motor driving the second reels at identical rotational speed, whereby the strips are wound off the first reels and pulled through the contact area.

The strips should be as thin as possible, without danger of their tearing, and it is . proposed to use stainless steel of 10 micron thickness and a width of between 50 and 300 mm, moving at a velocity of between 1 to 50 mm/s in accordance with the required output.

SHORT DESCRIPTION OF THE DRAWINGS Figure 1 is a characteristic curve illustrating the output voltage of a conventional electrochemical cell, Figure 2 is a schematical side view of an apparatus according to the present invention, and Figure 3 is a characteristic curve illustrating the output voltage of a point of the strip while moving through the current generating apparatus.

DETAILED DESCRIPTION OF THE DRAWINGS The curve of Figure 1 is that of a conventional electrochemical cell, showing the output voltage, as a function of time in three separate regions. In region I the anode-electrolyte interface is built up and the cell voltage starts rising. In region II the voltage rise slows down and, eventually, reaches its maximum level at the given intensity of discharge. Beyond this region the voltage drops due to polarization to a level and at a rate which depend on the intensity of the current drawn, as shown in region III. Due to the fact that in the present apparatus fresh anode, cathode and elecrolyte material is continuously fed into the current-generating zone and that the cell is disassembled at the end of region II, polarization is practically eliminated, as indicated in the curve of Figure 3.

The apparatus illustrated in Figure 2 comprises essentially a current generation station I, a electrolyte-supplying station II and a strip supplying and moving device III. The current generation station includes a housing 10 provided with two pairs of opposite rollers 11 and 11' serving to guide two conductive strips 30 ad 30' in close relationship between two graphite current collectors or brushes 12 and 12". The lower brush 12' is supported by the base .13 of the housing 10, while the upper brush is urged in downward direction by means of a platen 14 and a prestressed screw 15. The strips 30 and 30' are initially stored on two reels 31 and 31 'on the upstream side of the static/n I and are moved through this station and transferred to two downstream reels 32 and 32' which are rotated in the direction of the arrows F. Rotation is obtained by. means of a motor (not shown) coupled to one of the reels while ,the other reel is rotated in the same sense of rotation by a chain drive 33. Guide pullleys 34 and 34 ' direct the strips onto the reels.

Electrolyte is supplied to the strips out of a container 21 by means of a supply pipe through a flat spout in contact with the strip 30'. The spout is flat thus covering substantially the entire width of the strip while this moves into the station I, where the electrolyte is - - squeezed between the two strips and carried forward towards the reels 32 and 32' . The chemical process takes place between the roller pair 11 and 11' and the obtained current is collected from the conductive strips by the brushes 12 and 12 'and transferred to the user by conductor means not shown in the drawing.

A preferred anode material is Lithium which is uniformly applied to one of the strips on the side in contact with ( the second strip which serves as cathode. The electrolyte in this case is Thionyl Chloride (S0C1,,) in easily flowing paste form which is contained in the container 21. and supplied to the strip through the. spout 23.

Tests have been carried out with a layer of Lithium of a thickness of 10 micron on a strip of 100 mm width which was moved through the station at a velocity of 10 mm/s.

The current supplied at 3.4 V was 34 W.s per 10 mm strip.

The contact length between the roller pairs was 340 mm, therefore the theoretically obtainable current is 1156 W. or 1.156 kW.

Referring now to the curve shown in Figure 3, section I is equivlent to the stretch occupied by the rollers 11, wherein the electro-chemical reaction increases rapidly, until it reaches the maximum voltage at the end of section I. A substantially constant voltage level is maintained during the passage of each point through the section II which corresponds to the contact stretch extending between the rollers 11 and 11" , approximately in the area covered by the current collectors 12 and 12' (v. Figure 2). At the end of the stretch the anode material should be consumed, the strips are separated from each other and the action of the cell ceases.

The following is an example of a calculation of a battery supplying lkWh = 3.6x10 joule, or lJ/s. 1 g.atom Li (6.1g) yields 96500 coulombs x 3.4 V = 3.281x10s J. 1 g Li yields 328100/6.1 = 53790 J. 3 Since the volume of 1 g LI = 1.887cm , therefore 1 cm3 Li yields 53790/1.887 = 28510 J, therefore reeuired for 1 kWh:- 3600000/28518 = 126.3 cm3 Li; or for 1000 J/s ( 126.3/3600 = 0.0351 cm3 of lithium. 2 2 Provided current intensity per cm is 1 A/cm at V = 3.4, then the contact area required for 1 kWh = 1000 J/s = 1000/3.4 = 294 cm2.

Thickness of the layer of Li evenly spread over the 2 contact area of 294 cm :- D = 0.0351/294 = 1.2 microns.

Assuming that the width of the strip is 10 cm, then the length of the contact area is about 30 cm, and assuming that the output remains reasonably high and even for a period of 15 seconds, the velocity of the strip must be 2 cm/s. At this velocity the layer of Li required must be 15 times as thick, i.e. 15 x 1.2 = 18 microns.

At a strip speed of 2cm/s the total length for 1 kWh must be 2 x 3600 = 7200 cm = 72 m.

Taking into account various losses, as well as driving power, a suitable length will be at least 80 m of steel strips per hour. Since it is desired to use the battery for a longer period, it is evident that a multiple length should be employed.

Energy required for driving a standard car is about 25 kWh and it is intended to instal 8 units each weighing about 3 kg each. The steel strips are of a thickness of 10 micron having a width of 27 cm and a length of 122 m each per kWh , when the theoretical layer thickness is about 15 micron. The strip speed should be about 3.5 cm/s at a contact length of 35 cm. The units have to be exchanged, depending on the length of the steel strips and the average power consumed.

It is intended to re-use the steel strips after the lithium has been partly or completely consumed, by cleaning them and re-applying the layer of lithium. Since the maximum power is rarely required in a car, it is proposed to provide electronic control means, either for controlling the speed of the strips or by closing down one or more of the eight units.

It will be understood that the use of lithium and of the chosen electrolyte has been chosen as an example only, and that other electrochemically reacting materials ' may be used, as employed in known battery systems as well as with materials discovered as useful in future. It can be shown that the system can price-wise compete with internal combustion engines, with the enormous advantage of non-pollution and no-noise produced by motor vehicles provided with the apparatus according to the invention.

Claims (17)

C L A I M S :-

1. An electro-chemical device for generating direct current comprises two strips of a conductive material, each strip having an inside and an outside surface, said strips representing respective anode and cathode means and are moved through said device at substantially identical velocity from non-contacting alignment into contact of their inside surfaces along a predetermined stretch of travel with a suitable electrolyte continuously supplied between the two inside surfaces ahead of said contact stretch, the thus electro-chemicaily generated current being collected by current collectors in contact with said two strips and conducted to a current consumer.

2. The device as defined in Claim 1, wherein said strips are flat and thin metal strips of subst ntially identical active width.

3. The device of Claim 2 wherein said metal strips are stainless steel strips.

4. The device of Claim 2 wherein said metal strips are of a chemically passive material.

5. The device of Claim 3, wherein said stainless steel strips are 10 micron thick.

6. The device of Claim 1 wherein the inside surface of at least one of said metal strips is covered with an anode material to be consumed during passage through said contact stretch by an electrolyte suitable for reaction with said anode material.

7. The device of Claim 1 wherein the inside surface of one of ' said metal strips is covered with an anode material, and wherein the inside surface of the second of said strips is covered with a cathode material, an electrolyte being continously supplied onto the inside surfaces of said strips ahead of said contact stretch, the electrolyte, the cathode material and the anode material to be chosen from materials used in electrochemical cells or batteries.

8. The device of Claim 1, wherein said strips are wound off two first reels mounted ahead of said contact stretch and are wound up on two second reels mounted beyond said contact stretch, said second reels being rotated at. substantially identical velocity by motor means and transmission means.

9. The device of Claim 7 wherein said strips are urged onto each other by pressure on their outside surfaces by rollers mounted in the space of said contact stretch.

10. The device of Claim 7, wherein the surfaces of said strips during their passage through said contact stretch are substantially horizontal.

11. The device of Claim 10 wherein said electrolyte is stored in a container and poured onto the inside surface of the lower positioned strip by means of a spout of a width coextensive with the width of said strip.

12. The device of Claim 1, wherein said current collectors are graphite blocks urged onto the outside of said strips in said contact stretch.

13. The device of Claim 6, wherein the anode material covering the inside of one of said strips is lithium, and wherein said electrolyte is Thionyl Chloride in easily flow ing paste form.

14. The device of Claim 7, wherein said two strips are guided onto said second reels by guide pulleys.

15. The device of any of the preceding claims, delivering 25 kWh in the form of eight identical units, each unit containing two strips of stainless steel of a width of 270 mm one of which is covered by a layer of lithium, the linear velocity of said strips being 35 mm/s moving through a contact stretch of a length of 350 mm, and wherein the electrolyte is thionyl chloride in easily flowing paste form.

16. The device of Claim 15, wherein said layer of lithium on the inside of one of said strips is 15 micron thick.

17. The electro-chemical device for generating direct current substantially as hereinbefore described and illustrated in the accompanying drawings. FOR THE APPLICANTS,