DE1496358A1 - Electrode for accumulators - Google Patents

Description

, Patent attorney '

Dr.-lnq. Ackmqflfl
DUISBURG
2iegter.trae.32 1496358

Yardney International Corp »in New York (UBA)

Dr.

Electrode for accumulators

The invention "relates to an electrode for electrochemical '" Devices, in particular for accumulators, and a method for the production of this electrode © It is also directed to an electrochemical device which

these electrodes contain · ^

In the manufacture of electrodes for electrochemical devices it has already been proposed that the electrochemically active metal or a compound thereof, for example an oxide, hydroxide or the like, be pressed in powder form in a stream to form an electrode plate. play has also been proposed to use a binder which die'metallischen parts of the electrode zV & - sammenhälte

Electrodes produced by this known method las- ä

Much to be desired in terms of their mechanical strength

See also They are essentially very brittle and .t difficult to transport and with the various ".»

Operations to which they are subjected difficult to J handle »In addition, the application of these procedures is · '

very important due to the thinness of the electrodes to be produced

borders »j

The object of the present invention is the development of -. Electrodes of the type mentioned above with good mechanical

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see strength o It should be possible to produce thin-pressed electrodes with good mechanical strength, with the electrodes having a thickness of less than 3®P kaben · The object of the present invention is to develop a: Method for producing electrodes of this type Development of an electrochemical device in which the new electrodes are embedded.

It has now been found that the mechanical strength of such electrodes can be increased by incorporating organic or inorganic threads ^. \ also includes all types of thread-like structures independent of the individual length _β

When performing the method of the present invention the threads are preferably indiscriminately in the metallic oxide powder or other metal compounds, the to form the electrochemically active material of Electrode used are ^ randomly distributed »these threads are used in the production of a moist pulp from the Powder and the filaments distributed with or without the aid of a binder »In one embodiment of this invention, the obtained mixture of threads and powders dried, ground and then pressed into a mold. In another embodiment of the invention, the mixture is poured into a Brackets attached, stripped, cut into panels and then dried · When this powder is squeezed.

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is, has made a plate -mechanical stability and high strength due to the mechanical storage of the threads _o This process allows the preparation of a fibrous sheet by conventional manufacturing methods such as pressing, rolling _or the like u "If the threads of metallic nature, .If an additional "advantage was achieved through an increase in conductivity

In the production of the electrodes according to the present invention, different types of threads can be used · »They include natural," processed natural and s ^ rn- • defective organic threads, natural "and man-made mineral threads as well as metallic threads, Z ₀ B ₀ small wire threads, Tinsel and metallic wool «These threads can be used either alone or in combination with other types of thread Wise threads are impregnated with metals, especially electrically conductive metals © For example, metallic silver can be deposited in the interstices of cellulose thread, just as plastic or silver can be chemically combined with the thread material in the form of a silver cellulose.

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The following examples name typical threads that are in conformity Can be used with this invention: rayon, cotton, nylon, acrylonitrile, cadmium, nickel, Zinc, silver, glass thread, etc. "

The amount of threads that are stored in a provided electrode depends on the metal, metal oxide or other compounds used and on the technical conditions of the electrochemical device. Essentially, however, these will be about 0.1 to 3 percent by weight, based on the "weight of the electrochemically active material"

As already stated, according to one embodiment of this invention, a binder can also be incorporated into the electrode. "Many types of binders known from the prior art can be used for this purpose." Carboxylmethyl cellulose, _t polyvinyl alcohol or a combination of the two in different proportions «The amount of the binder can also vary and is preferably between 0.1 to 5 percent by weight of the binder, based on the active material«

The method of this invention is for manufacture suitable for numerous metal electrodes «For example for the production of cadmium, silver, zinc, nickel, iron, mercury electrodes etc. are used, whereby the material used to form the electrode is in the form of powdered metals or powdered metal powder

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bindings is applied · However, it is particularly suitable for the production of cadmium electrodes, the cadmium used in the form of oadmium oxide will·

In the manufacture of electrodes of the type mentioned, conventional additives can also be used, which are incorporated in order to improve or increase the electrode properties, · For example, material can be added

which improves the conductivity of the electrode * Furthermore, material can be added which reduces the degassing properties of the battery or protects the battery from turning over

The following examples further show the nature of the

; . themselves

go to invention. It goes without saying, however, that / the Invention not limited to this

Example 1;

5OO g of gadmium oxide powder, which contains 5% kickel powder, became a paste with 125 cm * of a 0.5% aqueous solution of polyvinyl alcohol (viscosity 4-6 cps, hydrolysis 98.5 to 100%), 125 da? a 0.5% aqueous solution of carboxymethyl cellulose (viscosity 7 ° cps) and 0.5 g of rayon threads (6.55 mm long, 1.5 denier). The paste was dried in air at room temperature until a solid product · This was crushed until it passed through an 80-mesh sieve (AS (EM) · The powder was placed in a mold that was approximately 4.45 cm. wide and 6.67 cm. long, and was then allowed to stand at room temperature at

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ο pressed at a pressure of around 1.5 to 2.3 t per cm. the

Leaf thickness ranged from 0.38 ms to 0.5 mm.

A silver plate was added to complete the electrode which was made of rolled silver plate material, cut to the approximate size of the sheet and a syllable rs tat "was welded onto a corner of the sheet" It was then sandwiched between a hair of the above-described sheets and the above-mentioned arrangement was compressed to form the final electrode

Example 2:

The procedure according to Example 1 was repeated with the difference, that cotton threads were used instead of rayon threads · ■

Example 5i

The procedure according to Example 1 was repeated with the difference, that metallic cadmium filaments about 0.0127 mm thick and from 1.6 to 6.4 mm. have been used for a long time,

Example 4:

A solution was prepared by mixing 60 car of a 0.5% aqueous solution of -igei Bolyvinylalkohol and 240 oar of a 0.5% aqueous solution of carboxymethyl cellulose · The Bolyvinylalkohol was "hydrolyzed from 98.5 to 100% and had a Viscosity between 4 · to 6.eps »The carboxymethyl cellulose had a viscosity of 70 cps»

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1/2 g rayon threads about 6.4 mm long and 1.5 denier was made into the "prepared" above Solution immersed ο The mixture was in a blender filled and kept in motion until an equal thixotropic suspension is obtained «

300 g powdered cadmium, which is 5% powdered: Hiekel contained, was added to 300 car the suspension, so that a pulp was formed · The pulp became between two Layers of a backing paper (Aidex_Papier) filled and underneath an oscillating scraper blade, so that long strips of electrode material were formed The strips formed were air-dried at room temperature and the electrode plates of the appropriate size cut out »The electrode plates were then at

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Pressures from about 0.3 to 2.3 t per cm to a density of. about 20 to 50% as cadmium of the theoretical density of the Metal cadmium compacted The thickness of the plates was about between 0.3 to 0.5 mm *

A piece of a rolled one was used to manufacture the electrodes Cut the silver material to the size of the electrode plate. A silver tongue was welded or otherwise on one Corner of the battery plate attached «The now formed plate was then between two electrode plates made after the above described processes were produced between

■ ■ - i "*

and the whole facility was put in a press pressed together with suitable pressures, so that a uniform Structure was obtained

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Example 5:

The.procedure according to. Example 1 was repeated with the. Exception that silver oxide powder instead of gadmium oxide was used"

Example 6s

The "procedure according to Example 1 was repeated with the difference that zinc oxide powder was used instead of cadmium oxide powder," was _o

_Ä The electrodes prepared according to Examples 1 to 6 'may in suitable silver-cadmium, nickel-cadmium or silver-zinc batteries known type are used _e · Electrode according to "Examples 1 to 4 have, for example, in the batteries using They were used in place of the cadmium electrodes mentioned there. The positive electrodes used were "sintered silver electrodes" which are known from the prior art (cf. © IIS -Patent 2 818 462), with or without embedded metallic

W · Plates »where the silver in the charged state is in the form of silver oxide and / or silver peroxide ·

The electrolyte used was a 30 to 50% aqueous KOH solution and was preferably 40 # _e -ig The time application of separator system is the same as that mentioned in the. Patents is shown, namely a Π-shaped envelope made of a semipermeable !! Material such as gellophane, polyvinyl alcohol. The separator system can also contain ion exchangers

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The invention "does not remain limited to the embodiment limited, but numerous changes can be made without exceeding the scope of the invention

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Claims (1)

-IQ patent claims: 1498358 le electrode for an electrochemical gate direction, in particular for accumulators, characterized in that that the electrode material is interspersed with charges 2β electrode according to claim 1, characterized in that that they are made of cellulose " 3ο electrode according to claim 1, characterized in that that the shops are metallic « 4. Electrode according to claims 1 Ms 3 »characterized in that that the electrode material consists of a material containing cadmium "· 5 · Electrode according to claims 1 "to 4 ·, characterized in that that the electrode material is made of EadmiumoxydL "consists· 6β electrode according to claims 1 "to 5, characterized in that that the load in the active electrode material are irregularly distributed " 7. Electrode according to claims 1 "to 6, characterized in that that the load "up to about 5 percent by weight of the Make electrode " 8 · Electrode according to claims 1 Ms 7 »characterized in that that this contains a binding agent " 9 · Electrode according to claims 1 Ms 8 _9, characterized in that the drawers are made of rayon "· 10, method of making an electrode according to claims 1 Ms 9 »characterized in that the Electrode mass and the load are mixed and the mixture is then formed into an electrode » -11- 909820/0554 U96358 Ho method of making an electrode according to Claim, 10, characterized in that the mixture on A carrier is applied to the required height scraped off and then shaped into an electrode » Method for producing an electrode according to Claim 11, characterized in that the electrode is pressed will", 13 “Process for the production of an electrode according to claims: 10 to = 12, characterized by the production of a wet mixture of electrode material and threads, by drying and grinding this mixture to form a powder and by processing this powder into an electrode _{or the like} 9Ö9820 / 0SS4