Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/64—Carriers or collectors
  • H01M4/70—Carriers or collectors characterised by shape or form
  • H01M4/76—Containers for holding the active material, e.g. tubes, capsules
  • H01M4/765—Tubular type or pencil type electrodes; tubular or multitubular sheaths or covers of insulating material for said tubular-type electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/34—Gastight accumulators
  • H01M10/342—Gastight lead accumulators
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the present invention relates to an electric accumulator, par ⁇ ticularly lead accumulator, with an electrolyte and gas tight contai ⁇ ner and a positive porous electrode, at least two porous negative electrodes and electrolyte to an amount enough for the discharge degree which is desired .
• the positive electrode consists of at least two parts, each shaped as tube plates with a common upper frame. Furthermore, it relates to a method for the manufacturing of parts to the same, more exactly such parts manufactured from a porous material.
• accumulators designed for low discharge rates require substantially more electrolyte than cells designed for high discharge rates, but they are due to lack of electrolyte not very suitable for longer discharge periods . More commonly it can be said that in or ⁇ der to receive a good capacity at low discharge current intensity the volume of electrolyte required to get a good utilization of the positive and negative plates is about three times as great as the vo ⁇ lume of the positive plate (grid plus active material) .
• the volume of electrolyte outside of the electrodes varies depending on porosity of the active paste as the electrodes also containe considerable amounts of electrolyte.
• cells designed for low current intensities commonly include positive plates ranging from appro ⁇ ximately 4 mm to approximately 10 mm in thickness . If cells designed according to the teachings of U . S . patent No . 3 ,862,861 were designed for low current intensities an acid layer of 12-30 mm would be needed, i.e. 6-15 mm on each side of the positive electrode.
• the electrolyte In open cells where the electrolyte is not intended to be com ⁇ pletely absorbed in the separators it is usual to have a considerable amount of acid over the plate set. There are two reasons to keep the electrolyte layers thin, i.e. the distance between the electrodes shall be small. First, the electrical resistance of the electrolyte layers will be relatively high in comparison to other parts of the electrode package. A cell with an electrode distance of for instance 6 mm will have a lower discharge than a cell with for instance 1 mm distance. This decreased voltage or waste capacity is particularly noticable at high discharges .
• the second reason to keep a small electrode distance in a cell with oxygen recombination is that the rate of recombination is inversely related to the distance between the positive and negative electrodes .
• oxygen gas will be produced at the positive plate before it is full charged and is transported via the separator to the negative plate which is oxidized .
• Oxygen will con ⁇ tinue to be produced at the positive plate as long as the cell is being charged and continues to oxidize the negative plate at the same rate as it is being charged . It is this feature that enables an oxygen recombination cell to operate over its lifetime without any loss of water.
• the degree of recombination determines the current intensity by charging during full-charging and for several reasons it should be as high as possible. Therefore the electrodes should be as close together as possible in order to provide a very thin electrolyte layer.
• the distance can vary from 0 , 1 mm to 3 mm . Above 3 mm the recom ⁇ bination is prohibitively low.
• oxygen is soluted in the electrolyte and is carried to the negative plate by means of ordinary acid diffusion, which oc ⁇ curs within the cell.
• gaseous oxygen passes from the positive plate to the negative plate where it reacts and oxi ⁇ dizes the same . In this case it is necessary to provide openings in the separator without electrolyte to permit the gas to flow.
• the separator must be very absorbant and act as a wick and not completely saturated with liquid for ion transport and at the same time have a pore structure with openings for gas transport between the electrodes .
• the solu ⁇ tion of oxygen in acid is small, the latter form of oxygen transport is dominated, but the two ways are dependent on the distance between the electrodes . It is , however, possible to get a gas recombination with a short distance and a very controlled charge, *but the com ⁇ bination degree is less and the time of charging is longer.
• Open lead accumulators are known having two relatively thin positive electrodes placed opposite each other in order to act to- gether as a single thick electrode. But these constructions have had an abundance of acid relative to the electrodes and full saturation of acid in all the cell.
• the positive electrode consists of triangle shaped tubes with a flat side of every two tubes close to the negative electrode and a flat side of every two tubes close to the other negative electrode.
• a micro porous material consisting of an acid reservoir.
• the method according to the invention implies that those glass fibres forming the micro porous material, before forming takes place, are supplied with a substance such as a metal salt, which gives a stabilizing effect of the glass fibre bodj-' .
• the substance should be such that it will be saturated from the glass fibre body by the elec ⁇ trolyte so that the requisite pores are formed. The requirement is that the saturated substance can be received in the electrolyte with ⁇ out a damaging effect.
• an electric accumulator with a cell structure having ample electrolyte quantity even at a discharge with a low current strength for high capacity and excellent capacity at high discharge rate performance, due to the low internal resistance, long life and complete recombination of gas and furthermore a porous material is produced, suitable to be used in the accumulator.
• Fig. 1 is a view of a typical cell according to the invention
• Fig. 2 is a section on the line II-II of Fig. 1 where two parts of the positive plate have a com ⁇ mon upper frame and manufactured by triangle shaped tubes
• Fig. 3 shows likewise as in Fig. 2 a similar embodiment according to examp ⁇ le two with the difference that the cell also has separators
• Fig . 4 shows in a corresponding section as in Figs . 2 and 3 a further examp ⁇ le with separators
• Fig. 5 shows a section along the line V-V in Fig. 2 at the type of cell according to Fig. 2 with positive tube plates .
• the two parts of the positive plate are connected to a common upper frame by using a so called tube plate with every two tubes placed close to the negative electrode and every two tubes close to the other negative electrode.
• the tubes are triangle shaped, where every two tubes have one side of the triangle close to the negative electrode and eve ⁇ ry two tubes close to the other negative electrode. Totally for instan ⁇ ce eight tubes can be close to the one negative electrode and eight tubes close to the other negative electrode .
• the tube plate has like many other tube plates separate outer plates which are approximately half as large as the remaining tubes .
• Fig. 1 shows a prismatic lead " cell with a jar body 2 and a lid 4 hermetically connected to the jar body . These two parts form a vessel, non-permeable for acid and gas .
• a positive pole 6 and a nega ⁇ tive pole 8 and a safety valve 10 are placed on the "upper side" of the vessel. (As the cell can work in all positions there is only one upper side during assembling . )
• the reason for having a safety valve is that if the cell should be over charged with too high current strength or that the recombination of any other reason should not function , the safety valve must open in order to prevent the vessel from exp ⁇ losion .
• a first negative plate is designated 12. This is a normal greased plate with a metallic lead bar carrying the active lead quantity .
• a separa ⁇ tor 14 (see Fig. 3) respectively 38 (se Fig. 4) is made from absor ⁇ bing material, which will be described in the following.
• a first part of the positive electrode is designated 16. Also this one is partly of conventional kind with a grid and positive material (PbO 2 ) .
• the side wall of the tube of the positive plate which is not facing the negative electrode is part of a side of an electrolyte reservoir 18.
• the inner wall of the next part 26 of the positive electrode forms the next wall in the acid reservoir together with vessels and lid walls .
• the reservoir 18 with the positive plates on each side forms the total positive electro ⁇ de. Outside this one is the next separator 24 (Fig. 3) and the other negative - electrode 22, which are identical to 14 and 12 respectively.
• the reservoir 18 is suitably filled with an absorbing material which can also be present above and under the electrodes .
• the absorbing material can be of the same kind as the separators 14, 24 consists of or even identical.
• the oxidation potential is highest at the separa ⁇ tors and less in the reservoir and the demand on oxidation permanen ⁇ ce is therefore highest for the separators .
• the tubes have an acid reserve in the thick felted tube walls which are situated on the one hand between the tubes and on the other hand between the positive and the negative electrode.
• the thickness of the tube walls is suited for the amount of acid that is desired with consideration taken that the absorbing tube walls due to the oxygen transport should not be entirely saturated with elec ⁇ trolyte .
• the absorbing material between the two positive single plates serves to keep the electrolyte in the reservoir 18 in place at diffe ⁇ rent positions of the cell, even when it is in an upside-down position.
• the capillary forces in the separators 14 and 24 which are bal ⁇ anced with the corresponding capillary forces in the absorbing material in the reservoir makes it possible to have these separators non-satura- ' ted with electrolyte in order to give the gas from the positive electrode possibility to reach the negative electrode in gaseous form , at the same time as there is enough electrolyte for ion transport .
• the absorbing material in the reservoir must have approximately the same degree of non- saturation .
• the thickness of the reservoir can be made sufficent in order to provide the cell with all the acid that is necessary for very long discharges .
• the most suitable way to establish separators of absorbing material with a degree of saturation which gives openings for the gas can be not to fill the cell with electrolyte to the brim of the plates .
• Another way is to charge the cells in upside-down position with a high current strength . The hydrogen and acid gases formed will drive away the electrolyte which leaks out.
• the degree of saturation desired can depend on the working manner of the cell and the separators and the porosity of the absorbing material. It can vary from 98% to 80% with 90% till 95% as the best values of the full amount at saturated material.
• Fig. 2 numeral 2 is as stated earlier the vessel; 12 and 22 are the negative electrodes ; 16 the positive electrodes and their parts
• electric conductive lead cross bars and 36 is an isolated plastic foil on the rear side of the conductor to let the current pass through the positive substance and not directly through the tube walls to the negative electrode.
• Fig. 3 shows a similar embodiment with a somewhat thinner tube walls and where said micro porous separator 14 and 24 has been pla ⁇ ced between the positive and the negative electrode. Nor this one is completely saturated with elecgrolyte, 90-95% saturation is usually suitable .
• Fig. 4 shows the third embodiment.
• the tube walls in the positive electrodes 16 are still thinner.
• As a reservoir for the electrolyte not only the separators 14, 24 will be used but also an additional separator 38 between the parts 25,
• Fig. 5 shows a section along the line IV-IV in Fig. 2 of a cell with triangle shaped tubes and a common upper frame designated 19 in Fig. 5 for the negative electrodes 14, 24 and 20 for the parts 25, 26 for the positive electrodes 16.
• the upper frames are connec ⁇ ted with the poles 6, 8 and can alternatively be placed outside the lid 4.
• the tube plate well known in the accumulator industry, con ⁇ sists of a number of vertical lead cross bars , where every cross bar is surrounded by a cylinder of lead dioxide. This one in turn is kept in place of a chemically resistant porous tube. Excellent tu ⁇ bes are made from braided glass fibre. At compressed micro glass separators macro spaces are avoided in which gas bubbles can be collected.
• the absorbing material in the reservoir 18 between the positive half plates can be of similar fiber material.
• the tubes are suitably manufactured from filted micro fibres of glass , and aforementioned, with a wall thickness so that the tubes can support each other and so that the total demand of acid in addition to what is inside the porous electrodes is stored in the tube walls , which naturally in spite of this should not be satura ⁇ ted with liquid in order to make oxygen transport possible.
• Tube shaped electrodes can also be raised of pleated pla ⁇ tes of felted micro fibres combinated with separators of the same material.
• the electrolyte shall be absorbed in a porous material as aforemen ⁇ tioned.
• three different embodiments of the positive electrode have been mentioned in such a way that it will contain an electrolyte reservoir.
• the triangle shaped tubes, which form the parts of the positive electrode are made with so large wall thickness that they form the pore volume which constitutes the reservoir.
• the tu ⁇ bes meet each other a double wall thickness is established relative to the sides opposite to the negative electrodes , if the tubes have unchanged wall thickness .
• the demand on requisite mecha ⁇ nical resistance and adequate reservoir volume for the electrolyte is met by the uniform walls made with suitable resistance and porosity .
• the tube walls are as mentioned somewhat thinner. Instead a separate electrolyte reservoir has been established by means of the separators 14 and 24, which complete the outer walls of the tubes at that side which faces the negative electrodes 12, 22.
• the total wall thickness around the tubes will be approximately uniform by means of the total thickness of the separators and the tube wall at the outerside and of the total thickness of the two connected tube walls at the inside .
• the wall thickness in the tubes is very insignificant and one can say that their main object is to meet with the demand that a sufficiently firm cover for the ac ⁇ tive substance while the electrolyte reservoir mainly is enclosed in porous separators , on the one hand the aforementioned between the positive and the negative electrodes and designed 14, 24 and on the other hand the pleated separator 38 which forms the inner reservoir 18.
• a cell can also have a smaller acid supply 32 situated inside the negative electrode, by the fact that this has been made from two half plates with separators placed between the halves .
• SO . ions manage to be transported to the negative electrode from the reservoir between the positive single electrodes . But at very high discharge current strength there might be a lack of SO. ions at the negative electrode and a reservoir can therefore be suitable. At extremely high discharges only so little of the active material in the acid in the separators is used and the pores of the negative electrodes are sufficient.
• the material must be micro porous in the separator and absorb with the largest possible effect in order to get an * even density in the cell. It must be inert to oxygen in "statu nascendi" and the sulphuric acid and must not contain any damagable impurities .
• the most suitable material is glass fibre, avail ⁇ able in the market as 100% glass fibre with a fibre diameter less than 2 ⁇ in certain cases l ⁇ . It looks like cotton and has a porosity over 95% even at hard compression. It is easily lyophiled by sulphoric acid and with good effect. In the reservoir, however, even certain permanent organic felt material can be used.
• the reservoir of micro porous glass for the electrolyte has been described with a number of different forms .
• the reservoir consists of a plane parallel plate between the two electrodes, on the other hand as a material in the triangle shaped tubes and finally as an interlayer between two parts of a tube plate between the tubes arranged in two lines in said plate.
• the micro porous material can be present also in other separators .
• the micro porous material is in its initial condition of felted glass fibres a soft material with low mechanical stability. According to the invention, however, a better mechanical strength in a forming phase can be obtained . This is made by impregnating the micro porous glass , felt with solutions of unorganic salts or oxides . After the impregnation the glass felt is dried and a hard and rigid plate or a block is ob ⁇ tained which can be worked mechanically .
• the micro porous material can be mixed with longer and thicker non-micro fine glass fibres which will thereby act as an armament.
• Such fibres or braided nets of such fibres can also be placed to the below described compression of the surface layer of the blocks or plates . This can be considered especially suitable when the plates shall be profiled by folding or bending of the salt impreg ⁇ nated material.
• Another essential characteristic beside the increased mechanical strength which is obtained by means of a salt impregnation is the armament in compressed condition which can be obtained if the im ⁇ pregnated micro porous felt is allowed to dry in compressed condition .
• the salt will namely be dissolved by the acid and the micro porous material will swell and fill all spaces so that no freely movable acid is present but all acid is present in a bound form.
• Fur ⁇ thermore the expanding felt will exercise a holding against pressure on those parts which during the charging of the accumulator and discharging will swell, for example the positive substance (PbO 2 ) .
• Sulphates and silicates with cations comprising Na- , K- , Al- or MG-ions or mixtures of these can be used.
• these salts can be made to crystallize with water of crystallization they are to be preferred as these crystals seem to give an additional strength to the armament.
• Said sulphates have a good solubility in sulphuric acid of the concentration that is used in lead batteries and will therefore be completely dissolved.
• the manufacture of impregnated micro porous glass block or plates can take place by means of fibres of C-glass , which are the most resistant to acid, and with a fibre diameter not larger than lO ⁇ , being disperged in water. This water is sucked off through a net, in which the slurry of the glass fibres is collected.
• the felt obtained in this manner can have a thickness of 1 mm to 5 cm .
• the felt will now dry at a suitable temperature after which it is stretched between plane or profiled perforated plates. After that the pores in the micro porous material with the salt solution will be filled, which can be a 10-70% solution of any of the salts mentioned above.
• the impregnated material After the impregnated material has been dried, it is loosened from its stretched condition and is now well suited for mechanical manipulation or further processing. If such a salt is used which crys ⁇ tallizes with water of crystallization , the drying should take place at a temperature which is lower than the one at which the salt melts in its water of crystallization.
• V-shaped grooves can be formed as early as at this assembling.
• the grids are placed in the grooves on the one side and said compound is greased into the V-shaped grooves on this side, after which the side is sealed by means of an impregnated plate of micro porous glass .
• the method is repeated with the other side . It is natu ⁇ rally necessary to seal the open ends which takes place for instance by means of preshaped plugs of inert material.
• the mechanical working is not limited to slicing, but can also take place by cutting or sawing.
• the manufacture of the profiles of micro porous glass can also take place by folding or bending of the glass felt either so that the profiles are formed before the impregnation whereby compression takes place in mandrels made for this purpose, or so that the impregnated plates are softened before shaping and then drying again .
• Such a softening can take place locally, for in ⁇ stance along a folding line by adding water in a narrow zone . By this procedure the drying time can be shortened.
• 50 grammes of glass fibres ⁇ 6 ⁇ m thick is disperged in 2,5 litres of water by vigorous stirring.
• the suspension is poured into a tube shaped container 50 cm high and with a diameter of 16,5 cm and in the bottompart of which is a wire cloth No . 100 mesh.
• the container contains 2,5 litres of water.
• the felt cake is removed from the wire and is removed from water by compression and brought to a heating chamber for drying at 80°C during 24 hours . After that the fibre substance is placed between two plane double walled and perforated plastic plates with a thin cloth of poly- prop ylen as interlayer.
• the plastic plates are pressed together with pairwise attached U-profiles of aluminum to a thickness of 10,5 mm.
• a solution of 100 g/1 sodium sulphate with water of crystallization and lOOg/1 aluminum sulphate with water of crystallization is added to the glass block till all the pores are filled with the solution .
• Dry ⁇ ing takes place during 48 hours at 80°C, after which a rigid and hard block is obtained from which V-shaped grooves can be cut to a depth of 6 mm and an angle of 45 degrees on both sides of the block.
• the method has been described at a laboratory level but can easily be adjusted for mass production by the man skilled in the art.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Secondary Cells (AREA)
• Cell Separators (AREA)

Applications Claiming Priority (4)

Publications (1)

Family

ID=26658714

Family Applications (1)

Country Status (3)

Families Citing this family (2)

Family Cites Families (6)

• 1985
  • 1985-05-07 EP EP85902700A patent/EP0214981A1/de not_active Withdrawn
  • 1985-05-07 WO PCT/SE1985/000200 patent/WO1985005227A1/en not_active Application Discontinuation
• 1986
  • 1986-11-06 FI FI864511A patent/FI864511A/fi not_active Application Discontinuation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events