DE1948646A1 - Secondary element - Google Patents

Description

The invention relates to secondary elements and, more particularly, to secondary elements in which a solid cathode and a Hydrogen gas diffusion anode are in contact with an electrolyte.

Secondary elements use a fixed cathode and a fixed anode or a gas diffusion cathode and a fixed one Anodes that are held at a distance from one another and are in contact with an electrolyte. An example for the latter cell type, which is a gas diffusion cathode and has a solid anode, is as a metal-air element

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known. This element uses oxygen or atmospheric oxygen as the oxidizing agent, which is the reactive material consumed on the gas diffusion cathode.

The present invention is directed to a novel secondary element comprising a solid cathode and a gas diffusion anode, which uses hydrogen as the reactive material depleted at the anode. A procedure· for generating electrical energy from such an fc element is also described.

According to the invention, a secondary has learn n-t at least a fixed cathode and at least one hydrogen gas diffusion anode spaced from the cathode.

The properties and advantages of the invention will improve understandably based on the following description with the figure, which shows a section through an inventive Represents secondary element.

The figure generally shows a secondary element 10 according to the invention, which is assembled, for example, in the uncharged state and a pair of electrically insulating end plates 11 and 12, as well as intermediate upper and lower seals 13 containing die.ein cell housing or a container form which defines a chamber 14. In the chamber is adjacent to the inner surface of the end plate 12 a solid cathode 15, for example made of nickel (II) hydroxide, arranged., From the cell 10 protrudes through the upper Gasket 13 an electrical attached to the cathode 15 Feed line 16 .. Adjacent to the other surface of the cathode 15 is a chemically inert absorbent separator; 17 arranged. The separator 17 is prior to being inserted into the Cell 10 soaked with an aqueous electrolyte - If desired, the separator can be inserted into the cell '

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and the upper seal 13 may be provided with an opening, to then provide the separator with electrolyte. After such an addition of electrolyte, the opening would then locked. A hydrogen gas diffusion anode 18 is on attached to the other surface of the separator 17, whereby both electrodes are in contact with the electrolyte. An electrical lead is attached to the anode 18 and extends outward through the upper seal 13 the cell 10 extends out. The remaining space of the chamber 14 is intended for the storage of hydrogen gas, which is generated and stored therein when the assembled uncharged cell is charged for the first time.

The electrically insulating end plates and the seal are held together by a plurality of clamping bolts 20, each including a threaded end 21 and a screwed nut 22. If end plates or Seals are used that are electrically conductive, then know the clamping bolts 20 with insulating sleeves in each of the end plates and fitted with an insulating washer at each end point to 'sioh-against each Possibility of an internal short circuit of the cell electrodes to secure.

Surprisingly, it was found that a new secondary element could be constructed which contained at least one fixed cathode and at least one hydrogen gas diffusion anode arranged at a distance from it. It has been found that such a cell can be operated with a wide variety of cathodes, anodes and electrolytes. Although a wide variety of gas diffusion anodes are used to diffuse Kassersteffgas through them from a hydrogen gas treasure, a network has been found to be a particularly suitable anode on which you can use a suitable one

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Binders such as polytetrafluoroethylene Precious metal like platinum or platinum-palladium was set. This type of electrode and its structure are described in an article entitled "A New High Performance Fuel Cell Using Porous Electrodes conductive Teflon in liquid electrolytes "by L.W. Niederach and H.R. Alford, which in the" February 1965 issue of the "Journal of the Electro-Chemical Society" was published. For the production of electrodes is therefore on refer to this description for the manufacture and operation φ of a gas diffusion electrode. Another very suitable gas diffusion electrode is a plate made of sintered Nickel in which platinum or platinum-palladium has been dispersed and those with polytetrafluoroethylene to connect the precious metal with the plate was provided. Such an electrode can be provided with a water-repellent layer on the gas-side surface. Other satisfactory materials as a support for one Porous anodes are carbon, platinum, platinum alloys, tantalum coated with platinum, gold, a 2-part palladium coating on titanium etc.

It was found that although a wide variety of electrolytes are suitable for this type of elec- trolyte, certain electrolytes with certain types of cathode structure operated in a particularly preferred manner. It can therefore be the various alkaline electrolytes such as potassium hydroxide, Sodium hydroxide, lithium hydroxide or cesium hydroxide with Satisfactory results can be used with solid cathodes., - Those made of a sintered carrier with applied - Nickel (II) hydroxide or silver are produced. In addition, you know pressed cathodes or cathodes from a network with an applied paste can be used very satisfactorily with this kind of electrolyte ^ which is the active one

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_ ~ EC _

Material nickel (II) hydroxide, "silver, mercury, Contain cobalt (II) oxide or manganese (II) hydroxide. if the assembled uncharged member is originally charged with hydrogen gas generation, then the above become Cathode materials in nickel (III) oxide or silver (I) or - (II) oxide or mercury (II) oxide or cobalt (III) oxide or manganese dioxide converted.

The most varied of neutral or salt electrolytes are usable in the element according to the invention, including Ammonium chloride, ammonium bromide, magnesium bromide, magnesium perchlorate, Potassium chloride etc. These neutral or salt electrolytes are very suitable with paste cathodes Manganese (II) hydroxide, or sheet-like or pressed material made of silver or thallium. At the original The above cathode materials become the charge of the element in manganese dioxide, silver chloride and thallium (I) chloride converted.

A wide variety of acidic electrolytes are suitable in the element of the invention, including sulfuric acid, Hydrochloric acid, hydrogen bromide, etc. In the case of acidic electrolytes suitable cathodes are made from materials such as lead. It can be seen from this that the most diverse solid cathodes are used in a wide variety of electrolytes together with a hydrogen gas diffusion anode, to form the new secondary element according to the invention ·.

It was also found that one improved Method for generating electrical energy results when an element according to the invention is assembled, charged and is then discharged by applying a load via the anode and the cathode.

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In an exemplary embodiment of the invention, a secondary element was built up, as explained in connection with the description, in which the solid cathode was formed by nickel (II) hydroxide on a porous Iicke It rager. The electrolyte consisted of 31 wt -.% Potassium hydroxide. A Niederach-Alford gas diffusion anode of the type described above, comprising a platinum metal in an amount of about 1.0 mg / cm2, was also built into a housing with leads to each of the electrodes.

m - ■ After the element was assembled, it was charged for the first ϊ time, generating hydrogen gas in the chamber of the case. The element is charged according to the following formula:

(1) 2 Ni (OH) _2. + 20H ~ --—) 2 NiOOH -I- 2H ₂ O + 2e ~

(2) 2H ₂ O + 2e ~ } H ₂ + 20H ~

. The element was discharged characterized in that a "consumer is connected across the anode and the cathode, and thereby electrical power was generated, the discharge of the element, which is the inverse of the charge of the element f is done as follows:..

(3) H ₂ + 20H ~ - ^ 2H ₂ O + · 2e ~ / ''

(4) 2 NiOOH + 2H ₂ O + 2e ~ 2 Ni (OH ₂ ) + 20H ~

In the following some examples are according to the invention manufactured secondary elements listed ".

example 1

A secondary element was built up according to the illustration. The cathode consisted of nickel (II) hydroxide on a porous nickel support. The electrolyte consisted of 31 % by weight

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; BATH ORIGINARY

Potassium hydroxide. The anode was a nickel mesh on which a paste of carbonyl nickel powder, platinum black and palladium black in a ratio of 5: 1 · -Λ parts by weight was applied by a binder made of polytetrafluoroethylene.

This cell was initially charged, thereby generating hydrogen gas for the chamber adjacent to the anode and converting the nickel (11) hydroxide cathode material to nickel (III) hydroxide. It was charged to a total charge of 30.0 ampere minutes over a period of 150 minutes at 200 mA. The element was then discharged through a resistor of 100 ohms to a cut-off voltage of 1.0 volts. The discharge totaled 27.5 amminutes; More than 80 % of it was withdrawn at a voltage above 1.2 volts. The element therefore showed a high output power.

Example 2

A secondary element was produced to benefit from the illustration. The ri at node was silver on one. Silver net as a carrier. The electrolyte consisted of. 31 3e% potassium hydroxide. The anode was a nickel net on which; ir.with the help of a polytetrafluoro-; "t hy lonb inaers ei: .e reschichtur.t of 1.2 rr.g / ^ rr. flatin black was applied as a fast. Table I shows the results of this element. The end of the discharge is listed after the original charge.

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BATH

Table I. Current density tension (mA / cm ^) (Volt) 0 1.36 15th 1.32 30th 1.27 45 ■ 1.21 60 1.20 75 1.16 90 1.12 ■ 120 1.02 135 0.98 Example 3

A secondary element was built up according to the illustration. The cathode consisted of lead sulfate on a support in Form of a cast lead grid. The electrolyte was one 18 molar solution of sulfuric acid. A liickel net on which a polytetrafluoroethylene binder served as the anode

2 a paste-like coating of about I ₃ O mg / cm platinum · black was applied. Table II below contains the results of the operation of this cell during discharge after an initial charge and shows the voltages in volts and the current density based on the

2
Electrode surface in mA / cm

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BATH ORIGINAL

Table II Current density
/ - -Λ / ? Λ tension (itiA / em ^) (.Volt) 0 1.70 16 1.56 31 1.54 47 1.52 62 1.50 78 1.48 94 1.46 109 1.44 125 1.42 14O 1.39 156 1.36 172 1.31

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Claims (6)

1948846 claims 1. Secondary element j. characterized in that there is at least one fixed cathode (15) and ' contains at least one spaced apart hydrogen gas diffusion anode (18). 2.Sekundärelement I according to claim ₃ characterized GEK e η η ζ η calibration et ₃ that it includes a in contact with 'the anode and the cathode electrolyte. 3. Secondary element according to claim 2 _3, characterized in that the uncharged cathode (15) contains nickel (II) hydroxide and the electrolyte is aqueous potassium hydroxide. 4. Secondary element according to claim 2, characterized in that g e .- ke η η ζ e ic h η et _s that the uncharged cathode (15) is silver and the electrolyte is aqueous potassium hydroxide. 5. Secondary element according to claim 2, characterized. marked that the uncharged cathode (15) is lead sulfate and the electrolyte is sulfuric acid. 6. Process for generating electrical energy from a \ Secondary element, characterized in that that at least one fixed cathode (15) and spaced therefrom at least one hydrogen gas diffusion anode (18) is provided that an electrolyte is in contact with the anode (18) and the cathode (15) is entered, the secondary element initially for generating hydrogen gas for consumption at the anode (l8) and then an electrical load on the The anode (1.8) and the cathode (15) are switched and electrical energy is generated as a result. 0098 15/1378