NL8403682A - SECONDARY DEVICE FOR STORING ELECTRICAL ENERGY AND ELECTRODE THEREFOR. - Google Patents

Description

* *% VO 6666

Secondary device for the storage of electrical energy and electrode therefor.

The invention relates to the use of a carbonaceous material in conjunction with an electron collector as an electrode for secondary devices for the storage of electric energy. The carbonaceous material of the electrode is stable in the presence of an electrolyte system containing anions, such as perchlorates, hexafluoroarsenates, and the like, at ambient temperature or before the use of the electrode at normal operating temperatures. That is, the carbonaceous material does not substantially swell or shrink irreversibly during cycles of strong electric charge and discharge, such as can be accomplished in operation of a secondary electric energy storage device.

Numerous patents and technical literature have disclosed electrical energy storage devices using a carbonaceous material, such as carbon or graphite, as the electrode material. Of course, one of the earliest of these devices was the 1866 Laclanche accumulator, in which carbon was used as an electron collector in a primary Zn / NH 2 Cl / MnO 2 accumulator. Since then, carbon has been widely used as a component for the electrode in primary accumulators, primary fuel cells, secondary fuel cells, secondary accumulators and capacitors. The function of the carbon or graphite in these aforementioned devices has primarily been that of a current collector or of a reactive material, with fluorine forming new compounds having different structures and properties than the original carbon / the original graphite, and recently that of semiconductor materials, which form salts with ions of the electrolyte. These prior art devices can be categorized as: primary accumulators as disclosed in U.S. Patent No. 2,597,451, Panasonic literature on lithium accumulators, and U.S. Patents 4,271,242, 3,700,502 and 4,224,389? fuel cells, 3403682/21 2 as per Japanese Publication No. 54-082043; and. limited rechargeable fuel cells, as described in U.S. Pat. No. 4,037,025, a rechargeable fuel cell employing an activated graphite (large surface area); rechargeable secondary accumulators, such as those described in U.S. Pat. No. 4,251,568 using graphite as a current collector, and in. U.S. Pat. Nos. 3,844,83T and 4..009,323, and capacitors as disclosed in U.S. Pat. No. 3,700,975 or in German Pat. No. 3,231,243, p. · The use of a carbon with a large specific surface (graphite). Some of these devices also use ionizable salts, which are · dissolved in a non-conductive solvent. "

The carbonaceous materials described in the patent and literature are materials which are graphitized or carbonized. have become electrically conductive to the materials. These materials have been obtained from polyacetylenes, polyphenylenes, polyacrylonitriles and petroleum pitch which has been heated to. "carbonized and / or graphitized" precursor material, whereby some degree of electrical conductivity is obtained. Some of the graphites used in the prior art literature are EPG (Reinforced Pyrolytic Graphite), nuclear reactor grade RG graphite, PGCP (Pyrolytic Graphite Carbon Paper) and GRAFOXL (a trademark of the Union Carbide Corporation ), which contains an expanded and compressed graphite, and the like.

Doping of analogous carbonaceous materials is also reported in Chemical and Engineering News, Volume 60, No. 16, p.

29-33, Apr 19, 982 in an article entitled "Conducting Polymers R&D Continues to Grow" '; Journal Electrochem Society, Electrochemical 30 Science, 118, No. 12, pp. 1886-1890, December 1971; and Chemical & Engineering News, 59, No. 41, pp. 34-35, 12 October 1981, entitled "Polymer Cell Offers More Power, Less Weight".

The problems which arise with these cells mentioned are that they do not have a long life since the electrode made of such a carbonaceous material is subject to deterioration when it is subjected to repeated cycles of electric charge and discharge.

For example, U.S. Pat. No. 3,844,837 discloses an accumulator using a nuclear grade graphite impregnated with chips Li 2 O as the positive electrode and copper as the negative electrode in an output. LiCF 2 -S SO 2 -dimethylsulfite (DMSU) existing electrolyte. The graphite electrode was made from a R-1 grade nuclear graphite (sold by Great Lakes Carbon Company) and was reported to be flaky after 9 cycles of electric charge and discharge. The patent holder also tested a graphite cloth and concluded that it was unsatisfactory. Several other graphites have been used with equally unsatisfactory results, the best results being obtained with pyrolytic graphite which failed after 33 cycles. According to United States Patent Specification 4,037,025, which describes the use of carbon or graphite material having a large specific surface area, within the pores of which the chemical reaction takes place, it is generally believed that this is the case. material has a low conductivity due to the lack of continuity of the carbon surface. Furthermore, it is believed that such materials do not maintain the dimensional stability and structural integrity required for the reversible formation of carbon complexes required for a long life of rechargeable cycles of secondary accumulators.

Experiments conducted in the course of the development of the present invention included the use of GRAFOIL (trademark), which failed at the first electric charge, and of electrodes of RPG (Super Temp) graphite, which also failed. It was found that an amount of more than 20% of the positive electrode made from RPG graphite was lost as chips, chips and powder after only 27 cycles of electric charge and discharge.

Remember that, in the prior art, the rear exit from and damage to the electrode is referred to as the result of a swelling and shrinkage of the electrode body and that this swelling and shrinkage increases with each cycle of electric charge and discharge, which deform the graphite platelets which flake off due to swelling and shrinkage stress. In carrying out these experiments in the course of the development of the present invention, it was found that such exfoliation of the 8403682 4 graphite platelets occurred. occurs when the aforementioned graphite materials are subject to repeated cycles of. electric charge and discharge were subjected.

According to a first object / the present invention provides an electrode for use in a secondary storage device. electric energy, the electrode comprising: an electrode body of electrically conductive carbonaceous material with a skeletal orientation, at least at or near the surface, and a current collector, electrically connected thereto, said carbonaceous material a Young's modulus of greater than (6y., 9 GPa) and during, repeated cycles of. electric charge and discharge undergoes a physical dimensional change of less than 5%.

According to a; Another aspect of the invention is provided by the invention: - a secondary electrical energy storage device comprising device: a housing having an electrically non-conductive internal surface and, a moisture-impermeable external surface or laminar body and in which said housing contains at least one cell, each cell containing at least: a pair of electrically conductive electrodes electrically insulated from contact with each other, said housing containing a substantially non-aqueous electrolyte, and at least one of the electrodes of each cell is an electrode according to the invention.

According to yet another aspect, the invention lies in a secondary electric energy storage device, which device comprises: a. housing having an electrically non-conductive internal surface and a moisture-impermeable external surface or laminated body and wherein at least one cell is located in said housing, each cell containing at least a pair of electrically conductive electrodes electrically insulated from contact with each other, wherein said housing contains a substantially non-aqueous electrolyte and wherein each of the electrodes of each cell is an electrode according to claim 1, 2 or 3, and wherein each of said electrodes has a freedom of choice with respect to polarity when recharged and the ability to be partially and / or completely opposite polarized without damage 35.

The electrodes can be separated by distance or by an 8403682 * 5.

ion-permeable material which is not electrically conductive are separated.

i

Physical characteristics

Preferably, the electroconductive carbon-containing material of the electrode should have the following physical property criteria: i (1) a Young's modulus of greater than 6.9 GPa, preferably from 69 PGa to 380 GPa, in especially from 138 PGa to 311 GPa.

(2) An aspect ratio greater than 100: 1. The aspect ratio here is understood to be the ratio of length to diameter 1 / d of a fiber or strand of yarn. carbonaceous material or the length to height ratio when the carbonaceous material is formed as a flat sheet.

(3) The structural and mechanical integrity of the carbonaceous material, regardless of its manufacturing form (woven, knitted or knotted or non-woven from continuous thread or staple fibers or a film), must be such that the presence of. a bottom member, such as a printing plate (outer films or wire mesh), to maintain the carbonaceous material over the entire period of at least 100 charge / discharge cycles in the desired sheet-like or plate-like shape is not required.

(4) A fibrous material specific surface area of at least 0.1 ma / g, but less than one is attached to activated absorbent carbon, an appropriate value being less than 50 m2 / g, and the value preferably less than 10 m2 / g and in particular less than 5 m2 / g.

(5} Sufficient integrity, of the shape of the carbonaceous material, to allow the carbonaceous material to retain its plate-like or leaf-like shape when said material has a size of more than 6.45 cm2 to more than 930 cm2 without support other than the metal current collector assembly, which forms the edge portion of the electrode.

(6} The secondary electric energy storage device using the electrode of this invention should be substantially free of water to a degree less than 100 ppm Preferably the water content should be less than 20 8403682 C f 6 ppm, with most preferred being less than 10 ppm.

The device of the invention can operate with a water content of up to 300 ppm, but will have a slightly reduced cycle life. Furthermore, it should be understood that if the level 5 of the water content should become an objection, the device can be disassembled, dried and reassembled in such a dry state without significant damage to it, without significant damage.

Performance / Criteria 10 (7). The carbonaceous material of an electrode should be able to sustain more than 100 cycles of electric charge and discharge without any significant damage from flaking of the carbonaceous material. Preferably · belongs after more than. 500 cycles of electric charge and discharge, with a discharge capacity of an electrode of more than 150 coulomb per gram of no significant damage, to occur. (8) The coulometric (coulombic) efficiency of the carbonaceous material of the electrode should be greater than 70%, preferably greater than SO% and especially greater than 90%.

(9) The carbonaceous material of the electrode should have powerful electric discharges of more than 70% of its electric charge capacity during at least 100 cycles of electric charge and discharge, and preferably more than 80% of more than 500 cycles of electric charge. and maintain discharge. The carbonaceous material of an electrode with the physical properties previously described therefore preferably serves electrical discharge and recharge of more than 100 cycles at a discharge capacity of more than 150 coulombs per gram of carbonaceous material in an electrode and at a coulometric efficiency. of more than 30% without sustaining any significant irreversible change in size (dimensional change of less than about 5%).

Usually it becomes carbonaceous. material obtained by heating a starting material to a temperature of above 850 ° C until it is electrically conductive. Carbonaceous precursor output material which converts the electrically conductive, oriented carbon 8403682

* A

7 * * dust-containing material portion of the electrode can be formed from pitch (petroleum or coal tar pitch), polyacetylene, polyacrylonitrile, polyphenylene, SARSN (trademark), and the like. The starting material serving as carbonaceous precursor should have some degree of backbone orientations. that is, many of these materials have either significant concentration of oriented benzenoid structural portions or portions capable of effecting heat conversion to. benzenoid or equivalent skeletal orientation at or near the surface because of the skeletal orientation of the starting material.

As an example of preferred carbonaceous precursor materials which exhibit such skeletal orientation when heated. may be referred to as assemblies of multi- or mono or lament strands or fibers, which are of petroleum pitch or polyacrylonitrile. prepared. Similar multi or monofilament strands or fibers; 15 are easily converted into threads or yarns, which can then be processed into a clothy product. One of the techniques for producing suitable monofilament fibers is described in U.S. Pat. No. 4,005,183, according to which the fibers are processed into a yarn which is then woven into a cloth. The fabric is then subjected to a temperature, usually above 1000 ° C, which is sufficient to carbonize the fabric, thereby making the carbonaceous material electrically conductive and providing the material with the above in paragraphs (1) to (6) described physical property characteristics. Such a cloth in cooperation with an electron collector is particularly suitable for use as an electrode in the secondary electric energy storage device according to the present invention.

It is advantageous that the carbonaceous precursor material be in the form. is of a continuous filament fiber, thread (threads), which consist of continuous filament (continuous filaments) or non-continuous fiber (yarn), which can be processed into assemblies such as woven, non-woven, or knotted or knitted assemblies, or the staple fibers, as such, can be "laid off" to form a cloth, a paper-like or a felt-like flat body. However, acceptable results are obtained when yarns made of short fibers of 1 to 10 cm in length are woven into an 8 4 0 3 6 8 2 I? a cloth-like product (provided that such short fibers, when heat-treated, still have the physical properties previously mentioned under (1) to (6)). Obviously, while it is advantageous to have the precursor material, preferably in a stabilized state (such as, it is obtained by oxidation), prior to charring in the desired shape (knotted or knitted, woven or felted) Such a post-carbonization machine construction may be made if the modulus is less than about 380 GPa and preferably less than. about 269 GPa. Obviously, the carbonaceous material can be formed from a film precursor.

The. degree of carbonization and / or graphitisation does not appear to be a controlling factor. regarding the behavior of the material 15 as an electrode element in an electrical energy storage device, except that they are. large, should be sufficient to measure the material electrically conductive and also large enough to provide the aforementioned physical and mechanical properties under the specified application conditions. In the literature, carbonaceous materials having a degree of carbonization of about 90% are referred to as partially carbonized. To carbonaceous materials with a carbonization degree of. 91 to 98% are referred to in the literature as carbonized material, while materials which are more than 98% carbonized are referred to as graphitized materials. Surprisingly, it has been found that carbonaceous materials having a carbonization degree of 90 to -9% as materials for. have failed an electrode, unless the carbonaceous material is used repeatedly during the cycle of. electric charge and discharge has the required dimensional stability. For example, while RPG graphite and GRftEQIL 30 have the required degree of carbonization, the electrical conductivity required, and the specific surface area required, they do not have the required physical properties in terms of Young's modulus and aspect ratio, so that they are in default.

According to the invention, a rechargeable and polarity-reversible electrical energy storage device can be manufactured by at least a pair of electrons made from 8403682 0 * 9 the previously described carbonaceous material and the associated electron collector (which electrically conductive) in a house. The housing has a non-conductive internal surface and is impermeable to moisture. The electrodes are immersed in a non-aqueous fluid contained in said housing (in which water is present in an amount of less than about 100 ppm). The fluid itself must be capable of forming "at least one ionizable" metal salt or it contains it in dissolved form. Hike electrode contains the carbonaceous heat-treated material of the present invention, connected to an electron collector, which is preferably insulated against contact with the electrolyte fluid.

The secondary electric energy storage device of the present invention can be constructed without the ability to reverse polarity by the aforementioned electrically conductive carbonaceous fiber assembly, such as a cloth, and its electron collector as the positive electrode. alternates with a negative electrode, which may be made of a metal, such as lithium, or a metal alloy, to coordinate and by immersing the electrodes in a fluid, which is substantially non-aqueous, which fluid itself is capable of forming at least one ionizable soluble metal salt. which is dissolved therein, or which contains at least such a salt dissolved therein, thereby providing electrolytic ion.

In the construction of a. preferred embodiment of the secondary electric energy storage device of the present invention, to separate the positive and negative electrodes from each other, conventional porous separators of glass fiber, polymeric materials or polymeric compositions. materials are used and these are preferably used. Most preferred is the use of a non-woven polypropylene sheet as a separator, since it has the desired degree of porosity and yet has a sufficiently tortuous path to prevent carbonaceous fibers from penetrating, thus preventing electrical short circuit . (The porous separators also work as stiffeners or supports for the electrodes).

Energy storage devices, which are contained in fluid enclosures, are generally known from the prior art 8403682. Such housings may suitably be used in the present invention as long as the housing material is electrically non-conductive and impermeable to gases and / or moisture (water or water vapor).

The materials which have been found chemically compatible as house material include polyvinyl chloride, polyethylene, polypropylene ,. polytrifluoroethylene and related perfluorinated polymers, "instant set polymer" (ISP), a fast-setting reactive urethane mixture, dearamides, a metal coated with a non-conductive polymer material, such as an epoxy resin, for example, DER (trademark of. The Dow Chemical. Company) 331 or with DEAKAKANE (trademark of The Dow Chemical Company), ZETABON (trademark of The. Dow Chemical Company) and / or glass or a metal oxide, fluoride or the like. House materials which have been found unsuitable in the preferred propylene carbonate system include acrylic resins, polycarbonate and nylon.

Acrylic resins form hairline cracks and polycarbonates form hairline cracks and, moreover, become extremely brittle, while nylon (with the exception of aramids) is chemically reactive.

In addition to being compatible, a housing material must also provide an absolute barrier of less than. 0.02 grams HjO / year / m * against the. permeability of water vapor from the outside environment of the house .. None of the currently known thermoplastic materials alone offers this absolute moisture barrier at a thickness that is desirable for an accumulator house. Currently, only metals, for example aluminum or mild steel, form one. absolute moisture barrier at a film thickness. It has been found that aluminum foil with a thickness of more than 0.038 mm is substantially impermeable to water vapor.

It has also been found that when aluminum foil with a thickness of 0.009 pn. is laminated with other materials, providing adequate protection. 30 ming against water vapor transmission. Suitable metal-plastic laminate, metal coated by cathodic electro-deposition with epoxy resin or. Houses made of plastic or glass interior cladding today meet the requirements of both chemical compatibility and the ability to form a barrier to moisture. Most of the cells and accumulators built today have been tested in either a dry container with a H ^ O-8403632 m * u level of less than 5 ppm, or a glass cell or a double-walled housing, where the space between the walls is filled with an activated molecular sieve, for example 5 A zeolite.

The electrolyte fluid preferably consists of a non-conductive, r-hom-t stable, non-aqueous solvent for an ionizable salt or ionizable salts, in which the ionizable salt is dissolved in the solvent. As a solvent, those compounds which are generally known as such in the art can be used, for example compounds in which oxygen, sulfur and / or nitrogen atoms are attached to carbon atoms in an electrochemically non-reactive state. Preferably nitriles such as acetonitrile? amides, such as dimethylformannide? ethers, such as tetrahydrofuran; sulfur compounds, such as dimethyl sulfite; and other compounds, goals propylene carbonate. are applied. Obviously, the solvent itself is sufficient under conditions of use. ionis can be honorable to. provide the necessary ions in the solvent. The ionizable salt must therefore be at least partially soluble and ionizable, either when dissolved and in the solvent. solution, either by liquefaction. While it should be understood that low solubility salts can be used, it will be appreciated. recognize that the rate of electric charge and discharge can be adversely affected by the low concentration of such salts in solution.

Ionizable salts which can be used in the practice of the invention are those which are in the prior art. technique are recommended and include salts of the more active metals, such as: for example, the alkali metal salts, preferably of lithium, sodium or potassium, or mixtures thereof containing stable anions, such as perchlorate (C104 *), tetrafluoroborate (BF. ^ -), hexa-30 fluoroarsenate (AsFg =), hexafluoroantimonate (SbFg *) or hexafluorophosphate (PFg “).

The electrolyte (solvent and salt) must be substantially free of water, i.e., it must contain less than 100 ppm water, preferably less than 20 ppm water and especially less than 10 ppm water. Of course, the electrolyte can be prepared to contain more than the desired amount of water and then dried 8403682 t 12, for example with activated sieves 5A molecular sieves. Such means may also be combined into the finished accumulator to ensure that the low water level requirement is maintained. The electrolyte should also be such that it allows ions (anions and cations) of the ionizable salt to move freely through the solvent as the electrical potential of charge and discharge ions moves to and from their respective poles (electrodes) makes you move.

When the electrode is manufactured as a cloth or sheet, it comprises an electron collector conductively connected to at least one. of the sands of the carbonaceous fibers or carbonaceous sheet. The rim (s) is preferably further protected by a material, the collector being insulated and the electron collector being substantially protected from contact with the fluid, and its electrolyte ions. The protective material must of course not be affected by the fluid or the electrolyte ions.

The current collector is in intimate contact with the carbonaceous material of the electrode at least along an edge 20, and preferably at all four edges thereof, when the carbonaceous material is in the form of an assembly, such as a flat cloth, blade . or felt. It is also envisaged that the electrode can be made in other shapes, such as in the form of a cylindrical or tubular bundle of fibers, threads, or yarns, the ends of which are of the same type. the bundle is equipped with a current collector. It is also clear that an electrode in the form of a flat body or cloth, which can be rolled up on felt with a porous separator between the layers of the carbonaceous material, and with the opposite edges of the rolled-up material connected to a current collector.

While copper metal has been used as a current collector, any electrically conductive metal, or alloy, may be used, such as, for example, silver, gold, platinum, cobalt, palladium, and alloys thereof. While electrode position is employed in bonding a metal or metal alloy to the carbonaceous material, other coating techniques may also be employed. (including melting applications) or electroless deposition methods are used as long as the edges or ends of the electrode, including most of the fiber ends at the edges of the carbonaceous material, are wetted by the metal to an extent sufficient to provide an electrical contact in a current path of substantially low resistance.

Collectors made of a non-noble metal, such as copper, nickel, silver or alloys of such metals, must be protected from the electrolyte and are therefore preferably coated with a synthetic resin material or an oxide, fluoride or the like, that in the working conditions of a cell the electrolyte is not affected and does not suffer any significant deterioration »

Electrodes of the present invention made from the electrically conductive carbonaceous material and its current collector can be used in a secondary energy storage device as the positive electrode. No significant damage to the electrode itself or the electrolyte, ie the solvent and the ionic zoit, is observed when it has repeated charges at a capacity of more than 150 coulombs per gram of active carbonaceous material and powerful discharges to a depth greater than 80% of 20 undergoes total electrode capacity at large or small charge / discharge rates.

Alternatively, in an accumulator (secondary battery) electrodes according to the invention, made of electrically conductive carbonaceous material, and the associated current collector 25 may also be of the same type. favorable operating characteristics as previously described are used, such as for the positive or negative electrode.

A specific surface area of at least 0.5 m2 per gram and a low resistivity of less than 0.05 ohm / cm of the carbonaceous material used for the electrode according to the invention are desirable properties. An accumulator made with the carbonaceous material. Material-containing electrodes according to the invention thus have an extremely low internal resistance and a very high corresponding coulometric efficiency, which is usually greater than 80%.

During the period of research into the limits of the present invention, it has been found that initial charge densities at 8403682 5 14 can restore a charge of greater than 15.5 to 3.1 mA / cm 3 in damage to it. carbonaceous material of the electrode.

Example i

A few. electrodes, each. surface area S of 72 cm 3, were fabricated from a Panex (trade mark) PWB-6 cloth (a cloth that had been heat treated by the manufacturer at a temperature of more than 100 ° C, making this cloth electroconductive ), marketed by Stackpole Fibers Industry Company. The fabric was woven from polyacrylonitrile (PAN) -10 precursor, in which the yarn was produced from non-continuous filaments. (staple fibers) with an average length of about 5 cm and a diameter of 7 to 8 micrometers and an aspect ratio of about 700: 1 o The fabric was subjected to a heat treatment by the manufacturer after weaving. The edges of the heat treated fabric. were electrodepositioned with copper to provide a current collector. A thread was tied to one. end of: the copper-coated, soldered edges. All four edges of each electrode (current collector and wire connector) were coated with an amine curable epoxy resin, DER (trademark). 331, manufactured by The Dow 20 Chemical Company, to insulate the metal from the electrolyte's corrosive effects under the conditions of use. The pair of electrodes were immersed in an electrolyte containing a 15% solution of LiClO 4 in propylene carbonate contained in a polyvinyl chloride (PVC) housing. The electrodes were spaced less than 0.6 cm apart. The electrodes in the housing were mounted in a dry container. The housing was sealed while it was in the dry tray, with the wires protruding from the housing. The water content in the assembled housing was less than 10 ppm. The fibers had a Young 30 modulus of about 230 GPa and one. area to weight ratio of 0.6 to 1.0 m3 / g. The total electrical capacity of the active carbonaceous material of the electrode was found to be approximately 250 col / g.

The cell thus manufactured was charged electrically to a maximum voltage of 5.3 volts, limiting the current to a maximum of 5.4 milliamps / cm 3 electrode outer surface. The cell was electrically charged and discharged in 1250 cycles over a period of 11 months in 1150 cycles and exhibited a coulometric efficiency of more than 90% performed at a discharge capacity of more than 85%. The cell was then disassembled and the fibers of each of the cloth electrodes were examined under a microscope with an ability to magnify 1000 times. The fibers, as far as measurable, had the same diameter as the fibers from the same batch, which had not been used in the cell. The cell was reassembled and testing continued in the same manner as previously described. The cell has so far completed more than 2800 10 charge and discharge cycles * over a 23 month period without a decrease in coulometric efficiency; it still * has a coulometric efficiency of more than 90%.

Example IX

Six electrodes equal to the electrodes of Example 1 were prepared and connected in a three-cell unit such that each of the three pairs of electrodes were sealed in separate bags made of polyethylene.

The electrodes were connected in series. The three cell unit was recruited in the same manner as described in Example 1, except that the voltage was about 16 volts. The initial open circuit voltage was approximately 13.5 volts. After 228 cycles of. electric charge and discharge, where the discharge was performed to a powerful discharge of more than 78% of the total capacity, the cells were disassembled and the electrodes removed from their pockets and the fibers examined for signs of deterioration, ie flakiness , and · excessive swelling and shrinkage of the fibers. The examination showed that there was no detectable change in fiber diameter judging by the fibers measured in the same batch of cloth which were not used for the manufacture of the electrode of this Example. The measurements were made with a laser interferometer.

Example XII

Several planar threads were cut from a cloth woven from yarn made from an essentially continuous mono-filament precursor fiber made from petroleum pitch. The fibers were manufactured by The Union Carbide Company and marketed under the trade name Thomel (trade mark). The precursor fiber working yarn with an aspect ratio of about 800: 1 was woven from a cloth and then subjected to a heat treatment at a temperature of more than 200 ° C. The flat blades each have a size of about 930 cm * in area. After the heat treatment, the fiber had a Young's modulus of 310 GPa and a specific area of about 1-m 2 / g. The blades were plated along their four edges with copper metal so that all fibers were electrically joined to form. an electron collector device. An insulated copper-10 wire was cut on one edge. from. the collector at a how k confirmed by soldering and. solder joint and copper collector were coated with a curable vinyl ester resin of the DER & KANE brand (trademark of The Dow Chemical Company). Each pair of blades was connected parallel to each other with the soldered wires at the opposite ends of the mating edges and separated by a small, nonwoven, perforated. fibrous propylene composite sheet with a thickness of 0.1 mm. A bag made of polyethylene with a. size of 930 cm2 was used as a cell. holder applied. The three cells were mounted in a dry tray by a pair of carbon fiber sheets and. place the separator in each of the three pockets, and. every bag. to be filled with about 500 grams of an electrolyte, consisting of a 15% by weight solution of LiC104 in propylene carbonate. The electrolyte level in the bag was found to provide 21 grams of active fiber per electrode (the surface of the electrode exposed to the electrolyte). The remainder of the carbon fiber of each electrode protruded. outside the solution or was covered by the frame of Derakane (trademark) resin / copper metal.

By mounting the cells in a dry container, the water content was reduced to less than 20 ppm. the electrolyte solution.

Each bag was sealed in the dry tray in such a way that. the soldered wire ends extended through the seal at opposite ends of the sealed edge. The three cells thus prepared were in. a tray made of translucent plastic · placed, and the wires connected in series. An amount of activated zeolite 5A molecular sieves (to absorb moisture) was added over the top of the cells, and the combination was removed from the dry tray. The end wires of the two end plates of. the series of three cells were connected to the terminals, which are located. extended through a hood or lid in front of the container and the hood was fastened to the cabinet quickly.

The assembly was charged for 45 minutes at a potential of 15 to 16 volts and a current of 1.3 to 2 amps. Thereafter, the Device * was discharged through a 12 volt car headlight, drawing an average current of 2.0 to 2.5 amps. The device was discharged to 90% of its capacity in 30 minutes. The electric charge and discharge cycles were performed more than 350 times. The cell was then disassembled and the fibers examined under a microscope at IQOQ-solid magnification and showed no evidence of swelling or deterioration due to scaling.

The device accepted an electric charge and a powerful discharge at a capacity of 90% for each cycle.

Example IV

A target based on PAN (precursor fiber) was obtained from R.K. Textile, Ltd. , Heaton Moor, O.K. The cloth was marketed under the trade name Panex (trade mark) and consisted of 20 non-conductive carbon fibers with an aspect ratio. over 250 tl, made into yarn and woven cloth and, as reported, had not been heated above 400 ° C. The cloth was subjected to a heat treatment at a temperature of about 1000 ° C for a time sufficient to make the cloth electrically conductive. The heat-treated fabric had a Young's modulus of about 160 GPa and a specific surface area of about 1 m2 / g. Two cloth samples, each with a width of 5 cm on one side and a surface of 26 cm 2, were cut from the heat-treated cloth and the four edges of each cloth 30 were plated with copper metal, forming a current collector for the electrode . A wire was soldered at one corner of the current collector from each electrode. The solder and the. The current collector was coated with a vinyl composition resin of the Derakane brand (trademark). A polypropylene nonwoven composite sheet, Celgard (Trademark) 5511, was placed between the two electrodes and the electrodes were placed in a plastic bag (sheath Ung). This combination was placed in an 18403682 dry container, in which the water content was kept at less than 20 ppm of the electrolyte solution. A 10 wt% solution of LiClO4 in a solution of propylene carbonate was used to coat the coating. until the two electrodes were immersed in the electrolyte solution. The wires of each electrode were connected to a two-pole two-way circuit, one terminal of which was connected to a 5.3 volt electrical voltage source. The other terminal was connected to a 10 ohm load consisting of an electrical resistor.

The cell was discharged vigorously to over 80% of its total charge 10 and over. 800 cycles of electric charge and discharge with a coulometric efficiency of more than 80%. The capacity of this cell was about 70% of that of the PAN example (Example I) based on the total electrode weight.

Cells manufactured in accordance with the present invention have been found to have an internal resistance which is less than 0.41 ohm / m 2 electrode outer surface on average in a cell containing electrodes. This value, .. originally as less than. ohm was measured, the input wires to the charge system included that. had a length of. about 6 meters. When measuring the resistance of the pipes and. then measure the total resistance of the system from the. charging, the resistance of the actual accumulator (secondary battery) was calculated to be 0.41 ohm / m2.

Confirmation of the data from the above examples was performed by a worker in a -2 electrode-containing cell made of "Thomel" cloth, VCB-45 with a Young's modulus of 310 GPa), a specific surface area of 1 m2 / g and an aspect ratio of more than 10,000 tl, each cloth having a size of 15.2 cm x: 15.2 cm. Copper edges were plated around all four edges of the fabric to form the current collector 30. The current collector was then coated with DEKAKANE (trademark) 470-36. The current collector edges had a width of about 2.6 cm, leaving surfaces of carbonaceous material of about 10 cm × 10 cm. The 100 cm2 area of each electrode contained about 6 grams of carbon fiber.

The electrodes were separated by placing an electrode in a fusion-sealed bag made of microporous 8403682 1 polypropylene film of the "Celgard" brand (trademark 5511).

The assembly of electrodes and separator was placed in a polyethylene bag, then the bag was skinned with a dry electrolyte of 15 wt% LiClO 2 in propylene carbonate (about 100 ml) and the combination was compressed between two plastic edges provided with plastic edges, covering the sides of the bag, including. in itself. the electrolyte. The thickness of the DERAKANE-clad copper current collector prevented the fibrous portions 10 of the two electrodes from being pressed to the minimum separation distance. In later trials, a 10 cm x 10 cm spacer plate was inserted between the edge printing plates to more firmly compress the electrode and separator combination. This decreased the cell resistance from about 0.9 ohms to about 0.7 ohms.

Discharge data at various discharge rates were provided. two of the cell configurations described above were determined, in a case (a 0.9 ohm cell), the electrode separation was limited by an epoxy fence of about 4 mm on the current collector. Otherwise (0.7 ohm cells), the electrodes in the center were compressed with only the porous polypropylene separator (less than 1 mm) in between.

The graph of FIG. 1 shows the final voltage versus discharge in coulombs per gram of fiber for the 0.9 ohm cell at various discharge rates from 6 hours to 3/4 hours. These 25 discharges correspond to a so-called first plateau (2 volt pinch-off voltage). If it is assumed that the total capacity of the first plateau to the voltage of 2 volt pinch-off voltage is 180 coulombs per gram, the values on the abscissa can be replaced by "% discharge"; wherein "180 coulomb / g" is equivalent. to "100% 30 discharge".

The total energy generated at a constant load at a rate of. 3 hours are recovered, xs approximately the same as at the 6 hours rate. In the rapid discharge of 3/4 hours, inefficiencies are caused, which occur due to the 35 .. cell resistance and electrode polarization. --The electrode beam densities corresponding to these discharge rates are: 8403682 m ______ r * »20

Speed (hours) Average current density at constant load _ (ma / cm *) _ 6 0.5 5 3 '1.0 lrS 2.0 0.75 4.0. The designation "coulomb per gram of fiber" is based on the weight of. the active carbonaceous material of only a .10 electrode ..

The curve of Figure 2 shows the data for a cell of. 0.7 ohms. It's clear that. more energy, is available to the cell with. the lower resistance. The curve of. Figure 3 shows the comparison of the two cells at the higher discharge rate (rate of 3 / 4-15 hours).

A comparative electrode made of lithium metal was inserted into the cell to determine which electrode was polarizing. The voltage drops between all the electrode and the comparative electrode were determined during charge and discharge and upon opening of the circuit.

Bee. opening of the circuit were the voltages between the negative, electrode and the. comparative electrode generally less than 1QΩ mv and only slightly changed with time. When the voltage between the positive electrode and the comparator electrode 25 was measured, it changed over time, decreasing after each charge and. after. every discharge got bigger ..

The maximum energy powers. of an accumulator cell at different stages of charge, were determined by impulse discharge, of the cell at loads, giving terminal voltages of half, of the open circuit voltages. The "bumps" lasted 10 seconds and the power was calculated as. the average power over 10 seconds.

The cell was first charged to. 344 coulombs per gram v active carbonaceous. material. a. electrode. This was considered to be a 100% charge state. The maximum current withdrawn from the cell with the 10 cm x 10 cm electrode at 100% charge state was 8403682 * * 21, 2.5 to 3.0 amps. Subsequent power measurements were made, at levels of 247 coulomb per gram (72% load) and 224 coulomb per gram (65% load). The curve of Fig. 4 indicates the results.

The maximum power from this cell was about 0.48 watts per gram of fiber at 100% charge state, decreasing to about 0.31 watts per gram of fiber at 72% charge state. Thereafter, the energy powers drop rapidly, as the voltage drops and polarization begin to occur. A discharge burst of longer than 10 seconds does not necessarily greatly reduce the power output. The curve of Figure 5 indicates the voltage progression of a 40 second maximum rate energy discharge. After the first 10 seconds, the voltage drop is small.

Example V

A three-cell accumulator was made from 12 plates, four per cell, of the Thoznel brand fiber described in Example III. Each plate was about 30.5 cm x 30.5 cm (930 cm2) in size and plated with copper on each edge. The copper plating along the edges was coated with a curable vinyl ester resin of the Derakane brand (The plates had an active surface of about 852 cm 2 - The four plates of each cell were combined with one of small holes, made of thin polypropylene textile ("-scrim1 *), separator between each of the plates. In each cell, the plates were connected in pairs in parallel, so that the plates alternate +, -, during loading / unloading. The four plates and their separators were contained in a polypropylene bag measuring 33 cm x 33 cm, which bag contained approximately 600 ml of an electrolyte solution of 15 wt% LiClO 4 in propylene carbonate. This electrolyte level in each bag was sufficient to provide about 37 grams of active fiber per electrode plate.

The accumulator was initially charged over a period of 1000 minutes to a capacity of 7.9 amperes per hour at a potential of 14-16 volts. The cell became. then discharge over a period of 200 minutes using a. 12 volt car headlamp, depriving an average capacity of 6.2 amp hours, representing a discharge depth of more than 80%. Recharge was performed in 8403682 <* 22 over a period of 800 minutes. An average coulometric efficiency of about 90% was observed upon charge and discharge repetition.

8403682

Claims (22)

1. An electrode for use in a secondary device for the. storing electric energy, comprising: an electro body of an electrically conductive copper-containing material with a skeletal orientation, at least at or near the surface, and a current collector electrically connected thereto, said carbon-containing material having a modulus according to Young of greater than 6.9 GPa and during repeated cycles of electric charge and discharge has a physical dimensional change of less than. 5% undergo .. 2. The electrode of claim 1, wherein said carbonaceous material joining has a Young's modults of 6.9 GPa to 330 GPa and wherein said carbonaceous material is obtained from a polyacrylonitrile or pitch as precursor material. The electrode of claim 2, wherein the tool-containing material has a Young's modulus of 6 9 GPa to 380 The electrode of claim 2 or 3-, wherein the carbonaceous material has a Young's modulus of from 138 GPa to 311 PGa. The electrode of any one of claims 1 to 4, wherein said carbonaceous material is a. self-contained structural integrity with dimensions from greater than 6.45 cm2 to greater than 30 cm2. 6. An electrode according to any one of claims 1 to 5, wherein said carbonaceous material is in the form of a cloth, film, paper-paper or felt-like flat sheet or other assemblies. * s Electrode according to any one of claims 1 to 5, wherein said carbonaceous material is in the form of a cloth or felt-like cloth or felt-like plate, comprising an aggregation of at least one yarn-based continuous filament or staple fiber work with a length of 1 to 10 cm. The electrode according to any one of claims 1 to 5, wherein said carbonaceous material is a woven or knotted or knitted fabric 8403682 * V * 24 - made from a combination of a work of continuous filament yarn or staple fiber length 1 to 10 cm. Electrode according to any one of claims 1 to 5, wherein said carbonaceous material is a cloth or a felt-like cloth or felt-like plate, which is manufactured by depositing continuous fibers or staple fibers from an assembly. An electrode according to any one of claims 1 to 9, wherein said carbonaceous material has a fibrous material specific surface area of from 0.1 to 50 m 2 / g. The electrode of claim 10, wherein the carbonaceous material has a surface specific to fibrous materials of. 0.1 to 10 m3 / g. 12. The electrode of claim 10, wherein the carbonaceous material has a fibrous material specific surface area of 0.1. up to 5 m2 / g. The electrode according to any one of claims 1 to 12, wherein said carbonaceous material has an aspect ratio (1 / d) or equivalent ratio of. more than 100 to 1. · The electrode according to any one of claims 1 to 13, wherein 2Q said electron collector is an electrically conductive metal plated on at least one edge of said carbonaceous material and wherein said plated edge is coated with a non-conductive, non-conductive -reactive protective material. Electrode according to one of the claims. 1 to 14, wherein 25 said carbonaceous material is capable of sustaining more than 100 electric discharge cycles with a depth of discharge of more than 70% and a coulometric efficiency of more than 70% without significant damage to structural integrity of the material. 16. A secondary electrical energy storage device, comprising: a housing having an electrically non-conductive internal surface and an outer impermeable moisture surface or laminar body and at least one cell being located in said housing and each cell contains a pair of electroconductive electrodes electrically insulated from contact with electricity and said housing contains a substantially non-hydrous electrolyte and in which device at least one of the electrodes of each cell has an electrode according to 8403682 * one of claims 1 to 15. 15 PGa. The device of claim 16, wherein the electrolyte contains a non-conductive, chemically stable, non-aqueous solvent and an ionizable salt dissolved therein. The device of claim 16 or 17, wherein the electrolyte solvent is selected from compounds having oxygen, sulfur and / or nitrogen atoms, which are bonded to carbon atoms in an electrochemical, non-reactive state, and wherein said so-called alkali metal salt. The device of claim 18, wherein the electrolyte solvent is propylene carbonate and the alkali metal salt lithium perchlorate. 20. A secondary electric energy storage device, comprising: a shell having an electrically non-conductive inner surface and an outer moisture-impermeable outer surface or laminated body and wherein at least one cell is located in said housing, and each cell at least at least one pair of electroconductive electrodes which are electrically insulated from contact with each other and wherein said housing contains a substantially non-aqueous electrolyte and in which device each of the electrodes of each cell is an electrode according to any one of claims 1 to 15 . The device of claim 20, wherein each electrode of a. cell when reloading a. freedom of choice of polarity and the ability to without damage. partially and / or completely opposite polarized. to be. 22. The device of claim 20 or 21 having a maximum power density of greater than 0.31 watts per gram of active positive tanning electrode during a pulse period of 40 seconds at full charge. 8403682 ƒ i