SE460442B - ELECTRODES INCLUDING COAL MATERIALS AND SECONDARY ENERGY STORAGE DEVICE PROVIDED WITH THE ELECTRODES - Google Patents

Description

460 422 devices can be categorized as: primary batteries, exemplary as disclosed by Coleman et al in U.S. Patent 2,597,451, lithium battery literature by Panasonic, and U.S. Pat. 4,271,242, 3,700,502 and 4,224,389; fuel cells, for example Japanese publication no. 54-082043; and secondary fuel cells with limited rechargeability, for example as described by Dey et al in U.S. Pat. 4,037,025, a charging fuel cell using an activated graphite (large specific surface, rechargeable secondary batteries (accumulators), as stated by hart, U.S. Pat. 4,251,568 in use of graphite as a current collector, and Bennion, U.S. Pat. 3,844,837 and 4,009,323 as well as capacitors, for example of Butherus et al., U.S. Pat. 3,700,975 or the German patent 'no. 3 231 243 using large surface area carbon (graphite) Vfång. Some of these devices also utilize ionizable salts dissolved in a non-conductive solvent.

The carbonaceous materials described in the patents and in the literature the tour is material that has been graphitized or carbonized until the materials become electrically conductive. These materials are derived from polyacetylenes, polyphenylenes, polyacrylonitriles and petroleum leumbeck which has been heated for "carbonation and / or gra- "fit" of the precursor material to provide some degree of electrical conductivity. Some of the graphites used according to prior art literature, graphites, such as RPG (Rein- forces Pyrolytic Graphite), R-1 nuclear reactor quality graphite, PGCP (Pyrolytic Graphite Carbon Paper) and GRAFOlL (a regi- registered trademark of Union Carbide Corporation) an expanded and compressed graphite, and the like.

Doping of analogous carbonaceous materials has also been reported in Chemical and Engineering News, Volume 60, no. 16, p. 29-33, April 19, 1982, in an article entitled "Conducting Polymners R&D Continues to Grow ", Journak Electrochem Society, Electrochemical Science, 118, no. l2, p. 1886-1890, decem- ber 1971, and Chemical & Engineering News, 52, no. 41, p. 34-35, October 12, 1981, entitled "Polymer Cell Offers More Power, Less Weight ". 460 442 The problems associated with these reported cells are that they do not have a long service life due to the electrode made of such carbonaceous material is sensitive to when exposed to repeated electric charges and discharge cycles.

By way of example, U.S. Patent 3,844,837 (Bennion et al) a battery that uses nuclear grade graphite impregnated covered with Li2O flakes such as the positive electrode and copper as the negative electrode in a LiCF 3 SO 3 dimethyl- sulfite (DMSU) electrolyte. The graphite electrode was made of nuclear R-1 nuclear graphite (sold by Great Lakes Carbon Company) and was reported to be flaky or flaky shaped after nine cycles of electric charge and discharge.

The patent holders also tried a graphite fabric and agreed to it was unsatisfactory. Several other graphites were used equally unsatisfactory results, and the best results was obtained with pyrolytic graphite which was destroyed after 33 cycles. Dey et al use carbon or graphite materials with a large surface area, i whose pores a chemical reaction takes place, but this material is generally assumed to have low conductivity due to lack of continuity of the carbon surface. Furthermore, it is assumed that such materials does not maintain dimensional stability and structural integrity required for the reversible formation of carbon complexes, required for the long charging cycle life of the secondary there batteries.

Experiments performed during the development of the present invention finning included the use of GRAFOIL which was destroyed at the first electric charge, and RPG (Super Temp) graphite electrodes that were also destroyed. It turned out that one amount greater than 20% of the positive electrode produced of RPG graphite was lost such as flakes, chips and powder after only 27 electric charge and discharge bicycles.

It should be noted that prior art identifies the breakdown and damage to the electrode as a result of 460 442 a swelling and shrinkage of the electrode body and that this' Swelling and shrinkage increase with each electric charge. and discharge cycle that deforms the flaking graphite flakes off due to the tension during swelling and shrinkage. At implementation of these experiments during the development of The present invention confirmed that such flaking of grains fit flakes occur when the aforementioned graphite materials repeated electrical charging and discharging cycles were smiles.

In a first aspect, the present invention relates to a electrode for use in an electrical secondary energy storage ring comprising an electrode body of electric conductive carbonaceous material with a skeletal orientation, at least stone at or near the surface, as well as a current collector that is electrically connected thereto, the carbonaceous material has a Young module of more than 6.9 GPa to 330 GPB, a specific surface area of from 1,1 to 50 m * / g and a "relative length / diameter of more than 100 to l.

In another aspect, the invention relates to an electrical secondary there-energy storage device comprising a housing with a electrically non-conductive inner surface and a moisture impermeable outer surface or laminar body and with at least one cell arranged in this housing, each cell comprising at least a pair of electrically conductive electrodes that are electrically isolated from contact with each other, the housing containing an essential non-aqueous electrolyte, with at least one of the electrodes in each cell is an electrode according to the invention.

According to a further aspect, the invention relates to an electric secondary energy storage device comprising a housing with a electrically non-conductive inner surface and a moisture impermeable outer surface or laminated body and with at least one cell arranged in the housing, each cell comprising at least one pair of electrical conductive electrodes that are electrically isolated from contact with each other, and the housing contains a substantially non-aqueous containing electrolyte, each of the electrodes in 46Û 442 each cell is an electrode according to claim 1, 2 or 3, and wherein each of the electrodes is free to choose polarity when charging and ability to be partial and / or completely reverse polarized without damage.

The electrodes can be separated from each other by distance or with an electrically non-conductive ion permeable material.

Physical properties A A Preferably, the electrically conductive carbon material in the have the following physical criteria: (l) A Young modulus of more than 6.9 GPa, preferably from 69 GPa to 380 GPa, and especially from 138 GPa to 311 GPa. (2) An aspect ratio of more than 100: 1 defined as the ratio length to diameter l / d of a fibrous or filamentous strand of the carbonaceous material or as a length-to-depth the ratio when the carbonaceous material is formed as one flat disc. (3) Structural and mechanical integrity of the kel-containing the material regardless of the form of manufacture (woven, knitted or non-woven from continuous fiber or thread or staple fibers or a film; should be such that it does not requires the presence of a support, such as a pressure plate (surface fllmer or näs) to maintain ael xolhalllga material in the desired layer- or sheet-like forms for at least l00 charge / discharge cycles. (4) A surface area of at least 0.1 / m2 / g but less than that of associates with activated absorbent carbon, namely less than 50 m2 / g, preferably less than -10 m2 / g and especially less than 5 m2 / g. (5) Sufficient integrity of the form of the carbonaceous material material to enable the carbonaceous material to be retained 460 442 keeps its disc- or layer-like shape when it has one size larger than 6.45 cm2 to larger than 930 cmz without other support than a metal current collector frame forming the edge portion of the electrode. (6) The electrical secondary energy storage device, i which electrode according to the invention is used should be free from water to a degree of less than 100 ppm. Before- stepwise, the water content should be less than 20 ppm and especially less than 10 ppm. The device according to the invention can work with a water content of up to 300 ppm but will have one slightly reduced cycle life. It should further be understood that if the water content level becomes troublesome, the device can be disassembled, dried and assembled in this dry state without significant damage to its continued usefulness.

Usage property criteria (7) The carbonaceous material of an electrode must be capable of cure more than 100 electric charge and discharge cycles without significant damage due to flaking of the carbon containing material. There should be no significant damage to the floor trunk appear after more than 500 electric charging and discharging cycles, at a discharge capacity exceeding 150 columns per gram of carbonaceous material in the electrode. (8) The coulometric (Coulumbian) efficiency of carbon the material of the electrode should be more than 70%, preferably more than 80% and especially more than 90%. (9) The carbonaceous material of the electrode should be able to withstand deep electrical discharges of more than 70% of its electricity additive capacity for at least 100 cycles of electric charge and discharge, and preferably more than 80% below more than 500 electric charge and discharge cycles.

The carbonaceous material in an electrode with those in the present currently described physical properties should thus be preferred be able to withstand electrical discharges and recharging 460 442 more than l00 cycles at a discharge capacity of more than 150 coulumbs per gram of carbonaceous material in an electrode and at a coulometric efficiency of more than 70% without any significant irreversible change in the dimensions (dimensions change of less than about 5%).

Usually the carbonaceous material is obtained by heating of a precursor material to a temperature above 850 ° C until it becomes electrically conductive. Carbonated precursor starting material that can form the electrically conductive oriented carbon The containing material part of the electrode can be made of pitch (petroleum or coal tar), polyacetylene, polyacrylonitrile, polyphenylene, SARA§É) and the like. The carbonaceous precursor the starting material should have a certain degree of skeletal orientation, ie. many of these materials have either significant concentrations oriented benzenoid structuring units or units which can be converted, on heating, to benzenoid or equine valent skeletal orientation at or near the surface due to the light orientation of the starting material.

Examples of preferred carbonaceous precursor materials shows such skeletal orientation when heated is settings or units of multi- or mono-wire strands or fibers made from petroleum pitch or polyacrylic nitrile. Such multi- or monofilament strands or fibers may easily converted into threads or yarns which can then be work into a fabric-like product. A_technical for position of suitable filament fibers is disclosed in U.S. Pat. 4,005,183, wherein the fibers are made into a yarn which then woven into a fabric. The fabric is then subjected to effect of a temperature, usually above 100 ° C, which is sufficient to char the fabric and to make it charcoal containing the material electrically conductive and so that the material obtains the physical characteristics of the described in paragraphs (l) to (6). Such a fabric, in combination with an electron collector, is particularly suitable for use as an electrode in the electrical secondary the energy storage device of the present invention. 460 442 It is appropriate that the carbonaceous precursor material be is in the form of a continuous fiber thread, thread or threads Consisting of continuous fiber or fibers or non-continuous continuous fibrous yarn which can be formed into such compositions woven, non-woven or knitted products, or also the staple fibers can per se be layered to form fabric, paper-like or felt-like flat product. Acceptable results are obtained, however, when yarns made from short fibers, from 1 to 10 cm in length, are woven into a fabric similar product (provided that such short fibers, at heat treatment, has the required physical properties as mentioned above under (1) to (6)). It should of course, although it is advantageous to place the precursor material preferably in a stabilized state (as obtained by oxidation) to the desired one the shape (knitted, woven or felted) before the charcoal can such construction is performed after the charring if the module is below about 380 GPa and preferably below about 269 GPa for machine manufacturing. It should, of course, be understood that the the containing material can be produced or consist of a film precursor.

The degree of charring and / or graphitization does not appear to be a regulating factor for the use properties of the material such as electrode element in an electrical storage device except that it must be sufficient to do the material sufficiently electrically conductive and also be sufficient to provide the aforementioned physical and mechanical properties under the intended conditions of use the things. Carbonaceous materials with about 90% carbonization referred to in the literature as partially charred. Carbonated rial with from 91 to 98% charring is referred to in the literature charred_materials (carbonized materials) while materials with a charring of more than 98% "are called graffiti serade. It has quite surprisingly turned out that the carbonaceous materials having a degree of charring or carbonization degree of from 90 to 99% have been insufficient such as material other than the carbonaceous material has the '460 442 dimensional stability during cyclic electric charging and discharging; Examples include RPG graphite and GRAFOIL, which has the required degree of charring or carbonization, electrical conductivity and specific surface area, not the required physical properties Young module and tip ratio and have thus shown insufficient.

In accordance with the invention, a rechargeable and polarity reversible electric energy storage device of the carbonaceous material described above. material and its associated electron collector (which is electrically conductive) in a house. The house has a non-conductive inner surface and is impermeable to moisture. The electrodes are immersed in a non-aqueous (water is present in an amount of less than about 100 ppm) of liquid present in the housing. the liquid itself must be able to form, or contain dissolved \ therein, at least one ionizable metal salt. Each electrode contains the carbonaceous heat-treated material, according to present invention, associated or in combination with a electron collector which is preferably insulated against contact with the electrolyte liquid.

The electrical secondary energy storage device according to the finding can be constructed without polarity reversibility by aligning it in the aforementioned electrically conductive composition of carbonaceous fibers, such as fabric, ' and its electron collector as the positive electrode alternating with a negative electrode, which may be fabricated of a metal, for example lithium, or a metal alloy and immerses the electrodes in a substantially non-aqueous liquid, which liquid itself may form or contain at least an ionizable soluble metal salt dissolved therein for formation of electrolytes.

In constructing a preferred embodiment of the electrical secondary secondary energy storage device according to the invention conventional porous glass fiber, polymeric separators 'r flfi ü fl f fi mfvïfr flfi wnwwwwwr,;: fl ü: iQQ “fi® tuuruw-" Hur 460 442 10 materials or composites of polymeric materials, used and was preferably used to separate the positive and negative electrodes apart. In particular, one was used non-woven polypropylene layer as a separator because it has it desired degree of porosity and yet has a sufficient distorted web to prevent carbonaceous fibers material to penetrate this, thus preventing electricity tric short circuit. The porous separators also appear to be suitable. as a stiffener or support for the electrodes.

Energy storage devices enclosed in fluid-tight housings are generally known in the art. Such houses can be suitably used according to the present invention provided that the housing material is electrically non-conductive and impermeable to gases and / or or moisture (water or water vapor).

The materials that have proven chemically compatible such as materials include polyvinyl chloride, polyethylene, polypropylene, polytrifluoroethylene and related perfluorinated polymers, instant set polymer (ISP), a rapidly solidifying reactive urethane mixture, aramids, metal coated with a non-conductive polymeric material, for example epoxy, e.g. DE 331 (The Dow Chemical Compan ~) or med DERAKAN (The Dow Chemical Company), ZETABO (The Dow Chemical cal Company) and / or glass or a metal oxide, fluoride or similar. Housing materials that have not been shown to be suitable in the preferred propylene carbonate system includes acrylic, carbonate and nylon. Acrylic material cracks and polycarbonates both cracks and becomes extremely brittle while nylon (with excluding aramids) is chemically reactive.

In addition to being compatible, a house material must also offer an absolute barrier with less than 2.15 g H 2 O / year / m2 against transmission of water vapor from the external environment of the house. No currently known thermoplastic materials alone offers this absolute barrier to moisture at a thickness that would be useful for a battery case. Currently offers only metals, such as aluminum or mild steel, 460 442 ll an absolute barrier to moisture at foil thickness. Aluminum foil with a thickness of more than 0.038 mm has been shown to be impermeable to hydrogen vapor transmission. It has too It has been shown that when laminating to other materials, aluminum foil that is as thin as 0.009 mm provide adequate protection against transmission of water vapor. Suitable housing materials of metal plastic laminate, CED-epoxy-coated metal (cathodic electro depo- sited, cathode electrodeposited) or metal with an inner lining of plastic or glass currently meets the requirements both in terms of chemical compatibility and ability to barrier against moisture. Most of the cells and batteries that built so far have been tried in either a dry box with one H20 content of 4.5 ppm, a glass cell or a double-walled housing with the space between the walls filled with an activated molecular sieve, for example zeolite SA.

The electrolyte liquid is preferably a non-conductive, chemically stable, non-aqueous solvent for ionic serviceable salt or salts wherein the ionizable salt is dissolved in the solvent. Min can be used as a solvent. use the compounds well known in the art such as such, e.g. compounds with oxygen, sulfur and / or nitrogen atoms attached to carbon atoms in an electrochemically non-reactive active condition. pelvis acetonitrile, amides such as dimethylformamide, ethers, such as tetrahydrofuran, sulfur compounds such as dimethyl sulfite and other compounds, such as propylene carbonate. It should of course Preferably, nitriles, e.g. It is understood that the solvent itself may be ionizable under the conditions of use sufficient to provide the required ions in the solvent. The ionizable the salt must thus be at least partially soluble and ionic either when dissolved and in solution in solution. or when transferred in the liquid state.

It should be understood that sparingly soluble salts are useful, however it is obvious that the speed of the electric charge in w IN in f r < charging and discharging may be adversely affected by the low ' the concentration of such salterni solution. - phosphate (PF , - ~ «Ww-w; -I wwy = ~ wwwwq 460 442 12 Ionizable salts that can be used in the implementation of the findings are those specified in the prior art and includes salts of the more active metals, e.g. alkali- metal salts, preferably lithium, sodium or potassium, or mixtures thereof, containing stable anions, such as perchlorate ~ (ClO4 =), tetrafluoroborate (BF4 =), hexafluoroarso- (AsF6 =), hexafluoroantimonate (SbFë = $ or hexafluoro- 6: * The electrolyte (solvent and salt) must be substantial anhydrous, i.e. it should contain less than 100 ppm water, preferably less than 20 ppm water and especially less than > 10 ppm water. The electrolyte can of course be prepared with more than the desired amount of water and dried, for example over active verad molecular silzeolite 5A. Such agents can also be combined in the finished battery to ensure that the low water content required is maintained. The electrolyte should also be such that it allows ions (anions and cations) of it the ionizable salt moves freely through the solvent when it the electrical potential of charging and discharging for ion to and from their respective poles (electrodes).

When the electrode is made as a fabric or a layer or a disk comprises an electron collector which is conductive joined to at least one of the edges of the carbonaceous fibers or the layer or disc, the edge or edges are protected preferably also of a material for insulating the collector and to substantially protect the electron collector against contact with the liquid and its electrolyte ions. The the protective material must of course be unaffected by the liquid or the electrolytes.

The current collector is in intimate contact with the carbonaceous material. the material of the electrode at least along an edge and preferably: at all four edges of this when the carbonaceous material ¿ exists in the form of such a composition as a plant - fabric, board, layer or blanket. It is also anticipated that the electrode can be made with other shapes, for example in the form of a cylinder 460 442 13 risk_or tubular bundle of fibers, threads or yarn, wherein the ends of the bundles are provided with a current collector. It is also obvious that an electrode in the form of a flat body or a flat fabric, sheet, layer or blanket can be rolled up but one porous separator between the layers of the carbonaceous material, and with the opposite edges of the wound material connected to a current collector. Copper metal has been used such as current collector, but any electroconductive metal or alloy can be used, for example silver, gold, platinum, cobalt, palladium, and alloys thereof. Electrical deposition has used in bonding a metal or metal alloy to it The carbonaceous material, but other coatings are also used. methods (including smelting applications) or electrical free deposition methods provided the edges or ends of the electrode, including a major portion of the fiber ends at the edges of the carbonaceous material are wetted by metal in a degree sufficient to provide an electrical contact and current path with substantially low resistance.

Collectors made of a base metal, such as copper, nickel, silver or alloys of such metals, must is protected against the electrolyte and is therefore preferably coated with a synthetic resin material or an oxide, fluoride or the like which is not attacked by the electrolyte or undergoes any significant deterioration in the working conditions of the cell.

Electrodes of the present invention made therefrom electrically conductive carbonaceous material and its current tor can be used as the positive electrode in an electric secondary energy storage device. No significant damage the electrode or electrolyte itself, i.e. the solvent and ionizable salt, observed in the performance of repeated charges at a capacity exceeding 150 columns per gram of activated carbonaceous material, and deep discharges with an I depth of more than 80% of the total capacity of the electrode in at fast or slow charging / discharging speeds.

Alternatively, electrodes according to the invention may be made of 4eø 442 14 the electrically conductive carbonaceous material and its current collector can also be used as both the positive and negative the electrodes in an accumulator (secondary battery) with similar favorable working characteristics such as those described above.

A surface area of at least 0.5 m2 / g and a low resistivity of less than 0.05 ohm / cm of the carbonaceous material used to the electrode according to the invention are desirable properties.

A battery constructed with electrodes of the carbonaceous material The material according to the invention thus has extremely low internal resistance. able and very high corresponding to the colometric efficiency which usually greater than 80%.

During the investigations regarding the limits of the present invention, it was found that initial current densities at charging greater than 15.5 to 3l mA / cmz can cause damage to the carbonaceous material in the electrode.

Example 1 2 A pair of electrodes, each of which had an area of 71 cm was made from a PancÅÉ> PwB-6 fabric (a fabric that had heat treated at a temperature above 100 ° C by the manufacturer which made the fabric electrically conductive), which is sold by pole Fibers Industry Company. The fabric was woven from a polyacrylic nitrile (PAN) precursor in which the yarn is made of non- * continuous fibers (staple fibers) having an average length of approx 2 cm and a diameter of 7-8 μm and an elongation ratio holding about 700: l. The fabric was heat treated by the manufacturer. clean after weaving. The edges of the heat-treated fabric are was coated with copper by electroplating to provide a current collector. A wire was soldered to one end of the copper plated the edges. All four edges of each electrode (current collector) and wire connectors) were coated with an amine curable epoxy resin, DE 331, manufactured by The Dow Chemical Company, for isolating the metal from the corrosive effects of the electrolyte under the conditions of use. The pair of elec- was immersed in an electrolyte of a 15% solution of LiClO in propylene carbonate kept in a polyvinyl chloride 4 460 442 l5 (PVC) -house. The electrodes were kept at a mutual distance of ' less than 0.6 cm. The assembly of the electrodes in the housing is carried out carried in a dry box. The house was locked in the dry box with the wires extending out from the house. The water content in it assembled house was less than l0 ppm. The fibers had one Young module of about 230 GPa and a ratio area to weight of 0.6 to 1.0 m 2 / g. The total electrical capacity of the activated carbon material in the electrode was determined to be approx 250 coulumb / g.

The cell thus prepared was electrically charged a maximum voltage of 5.3 volts with the prevention of the intensity exceeded 5.4 milliamp./cmz electrode surface. The cell is charging was electrically charged and discharged 1250 cycles over a period of ll months and showed a colometric efficiency of more than 90%, carried out at a discharge capacity of more than 85%.

The cell was then disassembled and the fibers from each of the fabric electrodes were examined under a microscope with 1000 times magnification. To the extent that it was measurable, the same diameter as the fibers from the same batch as not used in the cell. The cell is reassembled and tested. continued in the same manner as described in the previous walking. The cell has so far undergone more than 2800 charging and discharge cycles for a period of 23 months without reduction of the coulometric efficiency and has continued having a coulometric efficiency of more than 90%. * Å Example 2 Six electrodes similar to the electrodes of Example 1 was prepared and connected in three cell units in such a way that each of the three pairs of electrodes was sealed in separate polyethylene pockets (sacks). The electrodes were connected series. The three cell units were operated in the same manner as in Example 1 except that the voltage was about 16 volts. Oh The original voltage in the open circuit was about 13.5 volts. After 228 electric charge and discharge cycles, under É which the discharge was carried out with a deep discharge of more than 78% of the total capacity, the cells and elec-Å were disassembled 460 442 l6 the fibers were removed from their pockets and the fibers was sought regarding signs of deterioration, ie. flaking and excessive swelling and shrinkage of the fibers. During- the search did not show any appreciable change in fiber diameter compared to fibers measured in the same batch of fabric as had not been used to make the electrode accordingly example. Measurements were performed with a laser inferometer.

K Example 3 A plurality of flat layers are cut from a fabric woven from yarn set by a substantially continuous single-wire precursor fiber made from petroleum pitch. The fibers were made by Union Carbide Corporation and sold under the trademark Thornefgz Precursor fiber yarn (tow yarn) with an elongation ratio of about 800: l had been woven into a fabric and thereafter heat treated at a temperature of more than 2000 ° C. The plan the disks each had a dimension of about 930 cmz area.

The fibers had a Young's modulus of 315 GPa and a surface area of about 1 m2 / g after heat treatment. The discs were coated with copper metal along their four edges so that all the fibers were electrically connected and formed an electron collector frame. One insulated copper wire is attached to one edge of the collector near one corners by soldering and the solder joint as well as the copper collector were coated with DERAKANL (Dow) which is a type of curable vinyl ester resin.

Each pair of disks was arranged parallel to each other with them soldered wires at opposite ends of the opposite edges and separated by a perforated, nonwoven, fibrous polypropylene lens composite board with a thickness of 0.1 mm. A polyethylene pocket (bag) with a size of about 930 cm container. Three or were assembled in a dry box by using bringing a pair of the carbon fiber sheets and their separator in each of the three pockets and filling each pocket with about 500 g of an electrolyte of 15% by weight solution of LiClO4 in propylene carbonate. The electrolyte level in the pocket is determined to give 21 g of active fiber per electrode (the area of the electrode exposed to the electrolyte). The remainder of the carbon fibers in each electrode extended out of solution or was covered with the DERAKANL resin / copper metal frame. 1, 460 442 Assembling the cells in a dry box maintained the water content less than 20 ppm in the electrolyte solution. Each pocket was closed while it was in the dry box in such a way that they soldered wire ends could extend through the closure at opposite ends of the sealed edge. The three cells that prepared in this way was placed in a clear plastic box and the wires were connected in series. A quantity of activated zeolite 5A molecular sieve (for absorption of moisture) was added on top the top of the cells and the assembled unit were removed from the dry box. The end wires from the two end plates in the three series-connected cells were connected to the terminal means extending through a lid for the box and the lid quickly connected to the drawer.

The unit was charged with a potential of 15 to 16 volts and at a current of 1.8 to 2 A for 45 minutes. Thereafter, the the device was charged by a 12 volt car headlight which drew an average current of from 2.0 to 2.5 A.

The device was discharged to 90% of its capacity within 30 minutes. The electric charge and discharge cycles carried out more than 850 times. The cell was then disassembled and the fibers were examined under a microscope 1000 times disturbance and showed no visible signs of swelling or deterioration due to flaking. The device accepted a electric charge and deep discharge to 90% of capacity at each cycle.

Example 4 A PAN base (precursor fiber) fabric was obtained from R.K. Textile, Ltd., Heaton Moor, UK. The fabric was sold under trade PanoÅß) and was a non-conductive carbon fiber with a long stretch ratio of more than 250: l made into yarn and woven fabric, and was not stated to have been heated to a temperature turn over 400 ° C. The fabric was then heat treated at one temperature of about 1000 ° C for a period of time sufficient to make the fabric electrically conductive. The heating the treated fabric had a Young's modulus of 160 GPa and a surface range of about 1 m2 / g. Two samples of fabric each having one 460 442 18 width of 5 cm on one side and an area of 26 cm2 was cut off heat treated fabric and the four edges of each fabric was plated with copper metal to form a current collector. tor for the electrode. A wire was led to a corner of the the collector in each electrode. The solder and copper current the collector was coated with a vinyl ester resin coating composition. tion of the type DERAKAN. A nonwoven polypropylene composite layer, Celgar 5511, was arranged between the two electrodes and the electrodes were inserted into a plastic pocket (housing). This con- mounted unit was inserted into a dry box in which the water content was kept at less than 20 ppm by the electrolyte solution. A l0 weight- percent solution of LiClO4 in a propylene carbonate solution used was turned to fill the casing until the two electrodes were immersed in the electrolyte solution. The wires from each electrode connected to a dual pole reversing switch, at which a pole was connected to an electrical voltage source of 5.3 volts. The other pole was connected to one electrical load resistance of l0 ohm. Cells deep- was charged to more than 80% of its total charge and operated more than 800 electric charge and discharge cycles with one coulometric efficiency of more than 80%. The capacity of this cell was about 70% of the capacity of the PAN example (Example 1) on a total electrode weight basis.

Cells constructed in accordance with the present invention have been shown have an internal resistance that is on average less than 0.41 ohm / m2 electrode area in a cell with 6 electrodes. This value, initially measured as less than 1 ohm, includes the lead wires to the charging system with a length of about 6 m. When measuring the resistance of the wires and then re-measurement of the total resistance of the system From the charge, the resistance was calculated by themselves the accumulator (secondary battery) to 0.41 ohm / m2.

A confirmation of the values for the above examples was performed _ by another experimenter in a cell with two electrodes set by "Thornel" -tY9, VCE-45, with a Young module of 315 GPa, a surface area of 1 m2 / g and an elongation ratio “Ohm: in about 0.7 Ohm. 1.9 ÅÖÛ 442 of more than 10.000: 1, in which each piece of cloth had a dimension sion of 15.2 cm x 15.2 cm. Copper edges were plated around all four edges of the pieces of cloth to form the current collector.

The current collector was then coated with DERAKAN 470-36. Current- the collector edges had a width of about 2.6 cm and left surface areas with activated carbon material with a size of about 10 cm x 10 cm. The area l00 cm2 of each electrode comprised approx 6 g of carbon fiber.

The electrodes were separated by arranging an electrode in a heat sealed bag of "Celgard '5511 microporous polypropylene penfilm.

The assembled unit of electrodes and separator was introduced in a polyethylene bag, the bag was filled with a dry electrolyte mned % by weight LiClO4 in propylene carbonate (about 100 cm3) and the unit was clamped between two plastic edge pressure plates as supports the sides of the bag containing the electrolyte. The thickness of the DERAKANE-coated copper current lecturer prevented that the fiber portion of the two electrodes was pressed into the minimum the separation distance from each other. Later attempts were introduced » a shim with the dimensions l0 cm x 10 cm between the the press plates for compressing the electrode-separator-com- bination closer. This lowered the cell resistance from about 0.9 Discharge values at different discharge rates were determined for two of the above-described embodiments of the cell. IN one case (0.9 ohm cell) the electrode separation was limited by; the epoxy coating on the current collector to about 4 mm. In it in the second case (0.7 ohm cells) the electrodes were compressed at the center with only the porous polypropylene separator between in in these (less than 1 mm). , IN F .In the diagram of the figure, the curves show the pole voltage towards i the discharge, coulomb per gram of fiber, for a 0.9 ohm cell at; multiple discharge rates from 6 hours to 3/4 hour. These discharges correspond to a so-called first plateau (2 460 442 20 volt cut-off). If one takes that the total capacity of the first plateau is 180 coulombs per gram to 2 volts final voltage, the values of the abscissa can be replaced by "percent charge ", whereby" 180 coulomb / g "is equivalent to" 10% charge".

The total amount of energy recovered in a three hour period speed with constant load is almost the same as at 6 hours discharge rate. At the fast 3/4 hour the discharge rate occurs efficiency degradation due to cell resistance and electrode polarization.

Electrode current density values corresponding to these discharge speeds are: Speed (hours) Average current density at constant load (ma / cmz) IN IN O 1, 2 4 CDP-'b-JGN ~ \ IU1 U: COOL !! IN The value of "coulomb per gram of fiber" is based on its weight activated carbon material of only one electrode.

The curves in Fig. 2 show the values of the cell with 0.7 ohms stand. It is obvious that a larger amount of energy is available equal to the cell with the lower resistance. The curves in Fig. 2 shows comparison of the two cells at the higher discharge level the speed (3/4 hour speed).

A lithium metal reference electrode was inserted into the cell to determine which electrode was polarized. The voltage drop between each electrode and the reference electrode was determined below charging and discharging and when breaking the circuit. ¿ When breaking (opening) the circuit, the voltages were between it the negative electrode and the reference electrode are generally less 460 442 21 than 100 mv and changed only slightly over time. The excitement, measured between the positive electrode and the reference electrode, changed over time and decreased after each charge as well increased after each discharge.

The maximum power capacity of a battery cell at different stages of charge were determined by pulse discharge of the cell at loads that gave pole voltages of half the voltage at open circuit. The "pulses" had a duration of l0 seconds and the effect was calculated as the mean power over 10 seconds.

The cell was first charged to 344 Coulomb per gram of activated carbon rial in an electrode. This was considered as 100% charge. state. Maximum current taken from the ce with l0 cm x 10 cm electrode at 100% charge state was 2.5 more 3.0 A. Subsequent power determinations were performed at levels 247 Coulomb per gram (72% charge) and 224 coulomb per gram (65% charge). The curves in Fig. 4 show the results.

Maximum power from this cell was about 0.48 watts per gram fibers at 100 t charge state and dropped to Approx. 0.31 watts per gram of fiber at 72% charge state. Effect- the capacity dropped rapidly after this as the voltage decreases and polarization sets in. A pulse discharge of longer than 10 seconds does not necessarily lower the final § effect avg @ värt_ The curves in Fig. 6 show the voltage profileš for a 40 second discharge with maximum power. After the the first 10 seconds the voltage drop is small.

Example 5 A three-cell battery was constructed of 12 plates, 4 per cell, of Thornel type fibers described in Example 3.

Each plate had a dimension of about 30 x 30 cm or 930 cm2 and was copper-plated on each edge. The copper plating along the edges were coated with curable vinyl ester resin of the type § DERAKAN. The tiles had an active area of about 852 cm2. The four plates in each cell were assembled with a perforated polypropylene staple gas separator between each plate. Pair of tiles 460 442 22 in each cell were connected in parallel so that the plates at charge / discharge alternating was +, -, +, -. The four the plates and their separators were enclosed in a polypropylene pen bag with a dimension of 33 x% 3 cm which contained about 600 cm of an electrolyte solution of 15% by weight of LiClO4 in propylene lnncarbonate. This amount of electrolyte in each bag was sufficient to give about 37 g of active fibers per electrode plate.

The battery was first charged for an additional 1000 minutes a capacity of 7.9 ampere hours at a potential of 14-16 volt. The cell was then discharged for a period of 200 minutes through a 12 volt car headlight and had one average capacity of 6.2 ampere hours, which represents more than 80% discharge depth. Upload performed for a period of 800 minutes. An average coulometric efficiency of about 90% at the cyclic charge / discharge the charge measuredš.

Claims (14)

gb 460 442 PATENT REQUIREMENTS An electrode for use in an electrical secondary energy storage device comprising an electrode body of an electrically conductive carbon material having skeletal orientation of bone-like structural groups, at least at or near the surface of the carbon material, and a current collector electrically connected thereto, characterized from the fact that the carbon material has a Young's modulus of more than 6.9 GPa to 380 GPa, a specific surface area of from 0.1 to 50 m * / g and a length / diameter ratio of more than 100 to 1. 2. An electrode according to claim 1, characterized in that the carbon material has a Young's modulus of from 69 to 380 GPa and in particular from 138 to 311 GPa. 3. An electrode according to claim 1 or 2, characterized in that the carbon material has a specific surface area of from 0.1 to 10 m 2 / g and especially from 0.1 to 5 m 2 / g. 4. An electrode according to any one of claims 1-3, characterized in that the electrode body has self-supporting structural integrity in dimensions from 6.45 to more than 930 cm ”. 5. An electrode according to any one of claims 1-4, characterized in that the carbon material is in the form of woven or knitted fabric, film, paper, paper-like or felt-like flat layer or other compositions. 6. An electrode according to any one of the preceding claims, characterized in that the carbon material is a composition of yarn strands of fibers or staple fiber yarns. 7. An electrode according to any one of the preceding claims, characterized in that the current collector is an electrically conductive metal intimately attached to at least one edge of 460 442 an electrode body, the current collector being coated with a non-conductive, non-reactive protective material. 8. An electrode according to any one of the preceding claims, characterized in that the precursor material is a fiber made of petroleum pitch, polyacrylonitrile or the like. 9. An electrode according to claim 8, characterized in that the carbon material is obtained from a precursor polyacrylonitrile fiber, which is heated to a temperature above 850 ° C, so that the carbon material is made electrically conductive. Q 'GV A secondary electrical energy storage device comprising a housing having an electrically non-conductive inner surface and a moisture impermeable outer surface or laminated body and at least one cell disposed therein, each cell comprising a pair of electrically conductive electrodes electrically insulated from contact with each other. and the housing contains a substantially non-aqueous electrolyte, at least one of the electrodes in each cell comprising a electrode body of an electrically conductive carbon material having skeletal orientation of benzene-like structural groups, at least at or near the surface of the carbon material, and a current collector which is electrically associated therewith, characterized in that the carbon material has a Young's modulus of more than 6.9 GPa to 380 GPa, a specific surface area of from 0.1 to 50 m 2 / g and a length / diameter ratio of more than 100 to 1. Device according to claim 10, characterized in that the carbon material is in the form of a composition of ropes or threads or staple fiber yarn, woven or knitted fabric, film, paper, paper-like or felt-like flat layer or other compositions, wherein the carbon material has a Young's modulus of from 138 GPa to 310 GPa and a specific surface area of 0.1 to 10 m 2 / g. 12. A device according to claim 10 or 11, characterized in that the electrolyte comprises a non-conductive, chemically stable, non-aqueous solvent and an ionizable salt dissolved therein, the electrolyte containing less than 100 ppm water. Device according to any one of claims 10-12, characterized in that the electrolyte solvent is selected from compounds having oxygen, sulfur and / or nitrogen atoms bonded to carbon atoms in an electrochemical, non-reactive state, preferably propylene carbonate, wherein the salt is an alkali metal salt, preferably lithium perchlorate. 14. A device according to any one of claims 10 to 11, characterized in that all electrodes in each cell comprise one electrode body of the electrically conductive carbon material.