DE742509C - Increasing the effectiveness of manganese dioxide as a depolarizer in galvanic elements - Google Patents

Description

Increasing the effectiveness of manganese dioxide as a depolarizer in galvanic Elements It is known that brown stones are more powerful in terms of battery technology to make them hydrated chemically, mostly with them at the same time a larger surface is given. Such activation procedures are based on acidic or alkaline digestion. The achievable in these ways Increasing the oxidizing power has two fundamental disadvantages. First become with an increase in the superoxide solubility (hydration) in the Existing brownstone existing harmful impurities are also broken down, J. h. brought into an easily electrolyte-soluble form. Second is hydration nothing more than an increase in the superoxide solubility, thereby reducing the chemical The oxidative power of the manganese dioxide treated in this way grows in the desired manner, at the same time but naturally the self-disintegration of the brownstone in the batteries accelerates will.

It has now been shown that the effectiveness of brown stones in terms of battery technology small volume can be very good if the material has a high catalytic effectiveness. It may be necessary with very low chemical oxidative power, -der depolarization mixture in addition to the catalytically very effective manganese dioxide, adsorbent substances such. B. activated charcoal, but the need for such an addition depends on the remaining degree of chemical oxidative power of the manganese dioxide.

In any case, the shelf life of the batteries increases with decreasing Volume and falling degree of hydration of the brownstone are significantly increased.

So one comes to the realization that the brown pigment ineffectiveness In terms of battery technology, it can also be influenced by the fine structure of the brownstone leaves, since the catalytic effectiveness depends on the fine structure.

To: the catalytic effectiveness of a given brownstone artificially To increase it, it is necessary to change the structure of the superoxide dither or even just artificial to control, e.g. > ;. a modification conversion einyuleiteri, to cause a lattice stretching or else sharp crystal lattice edges to produce. "The easiest way to do this is by tempering the material, (I.e. by an annealing treatment under 400 'without pressure.

The tempering of the brownstone is different for each raw material to be treated specifically with regard to the most favorable temperature and the time to be spent. In order to avoid unbearably high losses of active oxygen during tempering suffer, the tempering temperature may generally not exceed @ oo °. The duration of the tempering can be between; up to 48 hours depending on the temperature and the sensitivity of the brown stone to be processed to decay.

At times it has also proven beneficial to the starting material Mix in small amounts of such foreign substances before tempering. of which some relatively few atoms enter the actual Mn O @ lattice and lattice disturbances cause. 2 # The heavy metal salts (oxides, oxyhydrates) are mainly used here iron (as salt, oxide, or hydrated oxide) can also be considered. Naturally, only such can Foreign substances are used that are not harmful to the battery during tempering Skip shape.

. Example A brown stone (in the following tables as brown stone i) with the crystal lattice given in table i (D e b y e - S c h e r r e r: Fe-a, the simple numbers indicate the, line positions, the bracketed ones Counting the corresponding intensities) was annealed for 12 hours at about 33o °.

The product thus obtained, labeled brownstone o, and the untreated brownstone were used to manufacture batteries, the performance of which is shown in Table 2. Table i Deby e-Scherrer lines Brownstone i: i5 (8) T8 (3) 21 (8) 24 (8) 27 (s) 3z (2) 36 (8) 425 (4) - o: 152) IS (s) 2i (4) 2.4 (R) 27 (t) - 36.5 (.) 38 (2) 425 (4) 465 (2) 47.5 (4) 66 (2) Tabel Total time it takes to discharge a battery across a resistor of 15 S2 and one with 4.5 volts nominal voltage with discharge daily discharge duration of 10 minutes. until it reaches 3.0 volts 2.5 volts 2.25 volts Braunstein = as a depolarizer: 120 minutes 250 minutes 320 minutes - 0 - - 2.40 - 300 - 36o - Table 2 shows that batteries with a brownstone treated according to the invention have a significantly longer discharge time than batteries whose brownstone polarizer has not been tempered.

Claims (2)

PATE \ TANSPRL CHE i. Process for increasing the effectiveness of manganese dioxide as a depolarizer in galvanic dry elements, characterized in that (let the manganese dioxide is tempered without pressure in such a way that chemical decomposition is practically possible does not occur. 2. A method for increasing the effectiveness of manganese dioxide according to claim i, characterized. that the starting brownstone to be tempered does not have an effect on it: oxides, oxyhydrates or salts of heavy metals are added in small quantities, which during tempering change into a form that is harmless to the battery. To distinguish the subject of the application from the state of the art, the following publications were taken into account in the granting procedure: German patents ... No. 570 939. 63 0 024., 283 o69; French patent specification 494 071: USA.- 1216451--, Chemikerzeitung (1938), p.216, right column, second paragraph; H. : @. Hofmann: "Textbook of Inorganic Chemistry", 2nd edition (1919), p. 595, lines 4 and 5 from the bottom; Ost: "Textbook of chemical technology ((, 17th edition (1939), p.734,;>Tempereisen"; Wüst and Borchers: "Metallhüttenkunde ((1900), p. 4.35, lines 23 to 25.