US917875A - Method of making electrodes. - Google Patents

Description

E. W. JUNGNER.

METHOD OF MAKING ELECTRODES.

APPLICATION FILED JUNE 23, 1906.

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ERNST WALDEMAR JUNGNER, OF KYEIPPBADER, SWEDEN, ASSlGhOR- TO NYA ACLUMU- LATOR 'AKTIEBOLAGET .lU-NGNER, OF STOCliHOLM, SWEDILN.

METHOD OF MAKING ELECTRODES.

Amlication filed June 23 To all whom it may concern:

Be it known that I, Ennsr eJALDEMAR.

of electrolytically producing electrodes of magnetic metals, especially electrodes of nickel, designed and intended for the speedy storing and dischargin of electrical energy.

If a nickel plate 0.5 mm. thickness, after having been first treated or cleaned with emery, is immersed as an anode in a dilute solution of caustic potash (about 3 to 4 grams of KOH per liter of water) with or without traces or a small quantity of a suitable salt, for example sodium chlorid as indicated in United States Patent 731,308,

a light greenish hydrate is formed at the.

commencement of the electrolysis. This hydrate does not however, adhere to the surface of the electrodes but is precipitated as a liocculent precipitate at the bottom of the vessel. lf'the e ectrolysis be continued the hydrate formed becomes heavier and at last adheres, although very loosely, to the electrode. After an electrolysis of' from a to 7 hours according to the strength of the current the electrode is covered with a layer of nickel hydrate about one. centimeter thick. If this precipitatebe examined it will be found that the outermost layer consists.

of a more or less gelatinous like, green hydrate but that the density of the hydrate E as well as the firmness of the layer increases inward where the' layer by degrees passes over from the greenish to the greenish-black and finally to the black hydrate. an electrode is used as anode in a stronger solution of alkali say 25%, only the inner most layer is oxidized to the higher electrolytically active hydrate that is bound to the nickel skeleton by molecular power while the rest of the mass will be peeled oil by the gases and fall down. If this plate be'now cleaned from hydrate by means of any suitable acid and weighedit will be found that it has lost from 50 to per .cont'of its weight according to the strength of the Specification of Letters Patent.

If such.

'Eatented April 13, 1909.

, 1906. Serial No. 323,132.

-current employed. It will also be seen that the plate is not evenly corroded and that in replace it artificially and this is elected by surrounding the electrode during its for tion by a porous substance moistened n the fluid required for the preparation of the plate. .I'thcreby avoid the hirmation of any flaky, 'flooculent or gelatinous, as well as any loosely bound hydrate and alter a few mins utes of'preparation a blac k even and closely adhering layer is formed on the plate. The advantages of such a formation in the dry way over those in the wet way are very iinportant. may be used of 0.10 mm. or less and the electrodes produced will be very thin, and after a little more than half an. hour will have an even and closely adhering layer of nickel hydi'ate without entailing any loss of crude material or electric current worth mentionmg. Many diilerent porous substan .re more or less suited for this purpose but l profor to use slaked lime which 1 have found to be the best. Limo is finely divided and miXGlllLO-EL pasty-or dough like consistency with a suitable electrolyte. But this hydrate plays also a chemical role, the passage of the current causing a thinning of the electrolyte at the electrode and the hydrate of calcium which is somewhat soluble aids to keep the electrolyte at nearly constant concentration at the surfaces which are being prepared. Thus hydrates of the other alka- 1 line earth metals may be used in place of cal cium hydrate such as the hydrates of barium, magnesium and, generally all hydrates that are but slightly soluble in the electrolyte.

Referring to the drawings in which like parts are similarly designated, Figure 1 is a transverse section of the electrode and vessel ready to be subjected to electrolysis. Fig. 2 is a section taken on line AB of Fig. 1.

some places it is thicker than in others,

By this method very thin plates tected from chemical corrosion by being covered with a suitable insulating material e as shellac or paraffin, The iron vessel a forms the negative electrode andthe plate 0 the positive electrode. The vessel is now filled with a substance f rendered semi-solid by a suitable electrolyte, referably a hydrate of a metal of the alka ine earths or gelatin, rendered semi-solid by an alkaline electrolyte. This semi-solid substance is conveniently hydrate of calcium or slaked lime, which is kneaded to a still dough'con sisting of 100 parts of hydrate of calcium ahd 72 parts of a solution of caustic potash said solution containing 6 grams of potash to a liter of water, to which has been added a few cubic centimetersof ammonia of 0.85 specific gravity. An electric current of about 5 amperes per s uare centimeter is passed from the nickel p ate to the vessel for about one hour. When the plate is taken out and the lime is removed, it will be found to-be coated with an even well adhering layerof nickel hydrate principally NiOH After-about 2 hours charging with a current of about one am ere per square centimeter in an electrolyte of 25 per cent. alkali the electrode is ready for use.

The addition of ammonia to the alkaline.

solution as well as the. variation of the percent of alkali, is intended to compensate the effects of impurities of any kind which may be found in the lime. Some of these impurities facilitate the formation of the nickel iydrate and if they are found in sufficient or co .-;;.=aratively large quantities, the addition of ammonia is unnecessa1y. If on the contrary the impurities act to retard the oxidation by having a reducing effect it is advantageous to add ammonia in greater uantities. The ammonia acts as a solvent or the nickel hydrate and facilitates the reaction; some organic substances also act thus.

Instead of absorbin the electrolyte in a porous substance as lime, said electrolyte may be combined with a gelatin, for example by boiling with starch or both methods ma be combined.

f the; nickel hydrate be removed from an electrode made in this manner it will be found, if the formation has been carried far enough, that the plate at a loss of about 40 per cent. of its weight, has been uniformly perforated with fine close holes some of them microscopic and in reality the plate so perforated is very much "like an exceedingly porous nickel sponge, the ores of which are .lled with active nickel ydratc, said hydrate being combined with the metal-by a molecularadhesion 'i. e. the hydrate being formed in place or in situ adheres to a very great de ree more strongly to ,the metal carrier on w iich it is formed than if it were first made and then forced into or on the. carrier, even if done so under great pressure. The metal particles of the plate itselfare hydrated and stick very tightly.

When the erforations are sufficiently large it is evi ent that two or more plates may be united to form a nickel'electrode. Such compound electrodes may be readily assembled with any suitable negative electrodes to accumulators with unchangeable alkaline electrolyte, provided the mutual ca pacities of the electrodes by election of the number of combined nickel-plates be brought to correspond to one another. In like manner wire nets or nickel skeletons of any shape whatsoever-may be prepared and the capacity of electrodes produced by means of the nickel hydrate cement according to the method described by me in a prior ap lication may be considerably increased by licing treated in the manner above described inasmuch as the nickel grains will thus be finally coated all over with a strongly adhesive elec-- troactive hydrate. This method of producing electrodes is also applicable to other magnetic metals as iron and cobalt. An electrode produced in this manner can in 5 minutes store up to per cent. of its normal ca acity.

claim 1. The method of making electrodes which comprises subjecting a carrier composed of a magnetic metal to electrolysis in a suitable electrolyte, While surrounded by a semi-solid substance in close contact with the surface of the carrier to be treated during the electrolysis, removing the semi-solid substance and then subjectin the plate to a charging current in a suitabTe electrolyte. 1

- 2. The method of making electrodes,which comprises subjecting a metallic carrier to electrolysis in a suitable electrolyte while surrounded by asubstance that is but slightly soluble in the electrolyte and thus rendered semi-solid, removing said substance and subjecting the electrode to a charging current in a suitable electrolyte.

3. The method of making electrodes which comprises subjecting a metallic carrier to electrolysis while surrounded by a suitable substance rendered semi-solid by admixture with an alkaline electrolyte, said substance being slightly soluble in the electrolyte, removing said substance and subjecting the electrode to a charging current-in an alkaline electrolyte. v

4; The method of making electrodes which comprises subjecting a carrier composed of magnetic metal to electrolysis while surrounded by a substance rendered semi-solid by an alkaline electrolyte containing an agent counteracting the reducing action of impurities in the semi-solid substance, said semi-solid substance sli htly soluble in the electrolyte, removing t e semi-solid substance and subjecting the electrode to a charging current in an alkaline electrolyte.

5. The method of making electrodes which comprises subjecting a carriercomposed of a magnetic metal to electrolysis While surrounded by an alkaline earth metal'hydrate rendered semi-solid by an alkaline electrolyte, thereby forming oxygen compounds of the magnetic metal on the carrier, removing the alkaline earth metal hydrate and subjecting the electrode so formed to a charging current in an alkaline electrolyte.

6. The method of making electrodes which comprises subjecting a carrier composed of a magnetic metal to electrolysis While surrounded-by an alkaline earth metal hydrate rendered semi-solid by an alkaline electrolyte containing ammonia, thereby forming oxygen compounds of the magnetic metal on the carrier, removin the alkaline earth metal and subjectin t e electrodetoacharging'current in an alkaline electrolyte.

' 7. The method of making electrodes which comprises subjecting a carrier composed of a magnetic metal to electrolysis while surrounded by slakedlime rendered semi-solid by an electrolyte containing a hydrate of a metal of the alkalies and ammonia and removing the lime.

In testimony that I claim the foregoing as my invention, I have signed my name in presence of two subscribing witnesses.

ERNST WALDEMAR JUNGNER.

Witnesses E. RKBERG, K. ErWIBERG

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