FI113417B - Water-activatable battery - Google Patents

Description

113417

Water-activated battery

The present invention relates to water-activated batteries. In particular, the invention relates to water-activated primary batteries, which contain at least one metal anode and 5 cathodes comprising a conductive component and an active cathode material in contact with the closely conductive component.

Water-activated batteries are storage batteries that are topped up with water before use. This allows the use of highly reactive materials without the problem of self-discharge.

Water forms an electrolyte with ions formed in electrode reactions.

Water-activated batteries are used as power sources in radiosondes, air rescue equipment, life jackets and lifeboats, emergency rockets, missiles, torpedoes and underwater research equipment. The batteries in question must withstand a long storage period of 15 without self-discharge. They are used in a variety of temperature conditions, especially at very low temperatures. They should have a high current density, but on the other hand they do not have to have a long life.

Radiosondes are the main purpose of water-activated batteries. The radiosonde is a measuring device used for meteorological research in the upper atmosphere. During the sounding, the radiosonde is lifted with a weather observation ball to a height of about 20 to 40 km. At the same time, it measures and sends information on temperature, pressure and humidity.

; The conditions in the upper atmosphere during radiosonde probing are extreme: the temperature drops to about -60 ... -90 ° C and the pressure drops to about 10 mbar. At low pressures, the boiling point of water drops to almost 0 ° C, which results in a very narrow temperature range where the battery does not boil or freeze. The temperature remains low and the cold slows down the cell's reactions.

.,.,: Copper (I) chloride / magnesium battery is a standard and conventional water-activated battery. "·. 30 type. It comprises a mixture of magnesium anode and a cathode comprising graphite, copper (I) chloride, and sulfur (cf. U.S. Patent 3,205,096). Related to this type of battery is- * *] [. gelma is a solubility of copper ions which causes corrosion and overheating of the magnesium anode. In addition, the voltage rises quite slowly to the required level.

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In order to reduce the solubility of copper ions, it has also been proposed in the art to replace copper (I) chloride with copper (I) bromide [Vuorilehto, K. and Rajantie, H., A water-activated cuprous bromide battery, Journal of Applied Electrochemistry 29 (1999). 903 -910]. CuBr sulfur was found to be very suitable for use as a cathode material. Although the maximum voltage provided by it 5 is lower than that of a conventional CuCl sulfur battery, the voltage is more stable. A particular disadvantage of a CuBr battery is the high price of the raw material, which makes it economically unattractive.

The use of manganese dioxide as an active cathode material in batteries is known per se from conventional batteries including alkaline batteries. However, manganese dioxide has also been tested on some delayed batteries. For example, U.S. Patent 3,433,678 discloses the use of a seawater battery having a magnesium or zinc anode and a cathode comprising manganese dioxide deposited by an electrolytic process on a graphite substrate. Nicholas T. Wilburn discloses a similar battery-15 structure in a journal article (Proc. 21st Annual Power Sources Conference, 16-18 May 1967, 113-116). In the structure described, magnesium perchlorate is used as the electrolyte instead of the seawater mentioned in the above-cited U.S. Patent.

Neither of the two previous structures is really "water activated". US; The battery disclosed in 20 Patent 3,433,678 only works in seawater with poor conductivity.

Therefore, the current and power densities produced are low. Battery usage is limited to the sea; : lake water does not contain enough salt to ensure sufficient conductivity of the electrolyte. Core; ! a nasium perchlorate battery causes handling and storage problems because the electrolyte ';' : is harmful and must be transported and stored separately.

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As the above statement shows, there is a need for a storage battery which can be activated with normal water (tap water) and does not contain any soluble

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"... * metals that can cause corrosion and overheating. In addition, there is a need for batteries that are immediately active. There is also a need for economically 't _ t' · 30 competitive alternatives to conventional CuCl sulfur batteries.

• · •; It is an object of the present invention to provide a novel cell for a primary battery based on non-toxic active cathode materials. A further object is to provide a cell which provides a uniform output voltage for long periods of time.

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A third object of the present invention is to provide a new primary battery and the use of such a battery.

These and other objects, as well as their advantages over known products, which are intended to be apparent from the following description, are accomplished by the invention as further described in the claims.

The invention is based on the use of a cathode 10 comprising manganese dioxide as an active cathode material in a water-activated battery. In order to increase the conductivity of the electrolyte, the cathode further comprises an ionizable component mixed with a conductive component and an active cathode material. Surprisingly, it has been found that the use of reasonable amounts of neutral salts, in particular alkali metal halides, can provide a battery having the same electrochemical reactions as manganese dioxide, but with the difference that the electrolyte it contains is alkaline only during discharge. Both new and used batteries are neutral.

The cathode further comprises a mildly alkaline alkaline agent capable of raising the pH of the aqueous phase within the cathode when water is added to the cell to at least 9 inactive anodes.

By installing several of these types of battery cells in a housing or holder, a spare can be obtained. \: a high-performance, water-activated battery capable of providing at least 150 • current; : mA, and for a voltage equal to or greater than 15 V for a period of at least 135 minutes; "'25 even under harsh conditions. The voltage change is slight during the first 10 minutes of operation.

More particularly, the battery cell according to the present invention is characterized by what is stated in the characterizing part of claim 1.

The primary battery according to the invention is characterized by what is shown above; 15.

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The use of the present invention is characterized in what is set forth in claim 19.

The invention provides considerable advantages. For example, raw materials are non-toxic to the environment, the user, and the battery manufacturing personnel. The battery is easily and immediately activated by the addition of normal tap water. No additional addition of ionizable salts to the electrolyte is required. Activation water and water running off the battery after use are neither toxic nor contaminated. Compared to other alternatives to conventional CuCl-S batteries, the raw materials are also quite cheap. During the first 10 to 10 minutes of operation, the voltage variation is less than 25% and there are no major voltage peaks, which would be detrimental to the operation of any battery-related electronic component.

The cell voltage is up to 1.95 V at the time of discharge and 1.25 V at 135 mi-15 noodle.

In the following, the invention will be further explored by means of a detailed description and several embodiments.

Figure 1 is a perspective view of a battery of the present type, * 'J Figure 2 is a simplified side view of a battery cell of the present invention, showing the basic structure of the cell, and. Fig. 3 illustrates voltage curves in atmospheric simulations of (a) a battery of ... of the present invention, (b) a battery of FI patent application 20000947, and (c) a. * * '. For 25 conventional CuCl batteries. In the latter battery, the copper (I) halide: sulfur to molar ratio was 1: 1.5. The discharge current was 150 mA (10 mA cm-2). The dry weight of each battery was 115 g.

...; For the purposes of the present invention, the following definitions are used: 30 »» .. \ "Battery cell" is an electrochemical (galvanic) cell comprising at least one '. an anode and at least one cathode which form an electrospun when both are in contact with the aqueous solution which forms the electrolyte.

113417 5 A "water-activated battery" comprises at least one cell unit mounted in a holder or housing provided with openings for water inlet. The cell unit usually comprises a cavity which separates the one unit anode from the cathode of the same unit, which cavity is connected to the water inlets.

5 "Active cathode material" means a cathode component containing a reactive material that generates electricity when the battery is discharged.

"Ionizable component" means a compound or substance that dissociates partially or completely in an aqueous solution to produce cations and anions that increase the conductivity of the electrolyte.

The battery of the present invention is shown in perspective view in Figure 1. Figure 2 shows in more detail the structure of a single cell. The following 15 reference numerals are used in the figures: 1. Battery 2. Cell 3. Connector 20 4. Holder t 5. End plate! ' 6. Aperture i '': 7. Tinplate plate ,,,: 8. Flowing conductive, dense film. · · ·. 9. Magnesium anode »> 10. Cavity filled with absorbent material 11. MnO2 cathode.

. The battery 1 according to the present invention consists of a plurality of cells 2 which are connected to form a cell cascade between two end plates 5. Individual ken-,. *. between the terminals, there are conductive, substantially dense membranes separating and bonding (as explained below) the cell anode with the cathode of the adjacent cell. Such a battery, comprising 12 cells connected in series, produces a minimum voltage of 15 V, preferably at least 18 V at the start of operation.

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The cells are assembled together by two adhesive tapes 4 which peripherally surround the upper and lower parts of the cells, holding the cells in place. Each endplate 5, preferably made of a non-conductive material, such as a plastic sheet, has an opening that extends through the plate and allows contact with the first and last conductive membranes 8 of the cascade 5. Between the end plates and the conductive membranes there is a thin film or thin plate 7 of electrically conductive material, such as a copper plate or a tinplate, which is in contact with the conductive membranes and provides a suitable substrate to which the ends of the electrical connector 3

As shown in more detail in Figure 2, each cell contains at least one anode 9, at least one cathode 11 spaced from the anode to define a space or cavity 10 between the electrodes, and current-conducting membranes 8 which on the other hand separate adjacent cells from each other migration and, on the other hand, electrically interconnect the cells by providing an electrical current flow through the cell cascade.

The conductive films may comprise a carbon film or a thermoplastic film made by conducting an alloy. A particularly preferred film comprises a graphite doped poly (isobutylene) film. The thickness of the film 8 is not critical, usually between 50 and 500 µm. Although it is advantageous to provide one anode, it is possible to construct a cell having two or more anodes.

20 '; Intermediate space 10 is filled with an absorbent material which absorbs (absorbs) the aqueous. · *. of the liquid used as water and electrolyte for Akti. Absorbent material. ·,: Should be highly porous and inert to electrolytes. Suitable materials include:. I ..: based on natural or synthetic fibers. Particularly preferred are cellulose fillers: loose fibers, regenerated cellulose fibers and synthetic polymers such as cotton wool, viscose, polyester or polypropylene fillings.

: '' ': The material which fills the cavity may be in the form of a rigid porous material. As shown in the drawing, the cavity is open on both lateral sides, with the inlet opening forming the upper part. Said opening leads into the cavity and allows the electrolyte to form an aqueous liquid into the cavity. The lower part is preferably closed by a seal, e.g. It is also possible to partially or completely seal open sides with a water-impermeable film, such as a polymeric film layer such as an adhesive tape, to form a "microclimate" within the cell, such sealing improves cell performance.

The cathode may be formed into an integrated rigid laminar layer which forms a electrode layer. However, when the absorbent is a porous material with a hard texture, it is also possible to shape the cathode material into a single pellet or multiple pellets (i.e., multiple cathodes). For example, Figure 2 shows a cell comprising two cathode pellets. Generally, the area of the cathode is at least slightly less than the area of the anode. In particular, direct contact between the electrodes 10 at the edge of the conductive film should be avoided. Such contact may cause corrosion of the anode.

Thus, it is preferable to provide the cathode with a surface area of at least about 5%, preferably about 10%, smaller than the surface area of the anode. In the embodiment shown in Figures 1 and 2 with the top of the battery open, it is preferred that the height of the cathode is less than the height of the anode to avoid contact between the cathode and the anode at the top of the battery.

15

According to a preferred embodiment, the anode material comprises magnesium or magnesium alloy. Generally, such material comprises a minimum of 93 weight percent magnesium, 0 to 7 weight percent aluminum, 0 to 3 weight percent zinc, and 0 to 2 weight percent manganese. As examples of particularly suitable magnesium alloys, the following may be mentioned: an alloy containing at least 93% by weight of magnesium, 1-7% by weight of aluminum and 0-2% by weight of zinc, such as alloys, commercially available under headings AZ-31 and AZ-61; and alloys containing at least 98% by weight of magnesium, *. and 0.1 to 2% by weight, preferably 0.5 to 1.5% by weight of manganese (Mnl50; ASTM Specification B-843-93).

"·. 25

Cathode 11 comprises manganese dioxide mixed with an alkali metal chloride * selected from the group consisting of sodium chloride and potassium chloride and mixtures thereof. Potassium chloride; and sodium chloride increase to about 6-25% by weight of the cathode. The conductive component of the cathode generally comprises graphite, for example expanded graphite, or; ". Other forms of carbon, such as carbon black or activated carbon. The carbon component, such as graphite, is preferably used in powder form and mixed with the active cathode material and ion. with the pulp formed by the volatile component so that it is uniformly distributed. The mixture is compressed either by cold pressing or by thermal pressing into a strong electrode layer. Manganese dioxide is preferably used in the γ form.

8 112417

The cathode also contains a slightly alkaline alkaline substance. By "slightly alkaline" is meant that the alkaline substance dissolved in water forms an aqueous solution having a pH of about 9 to 13. Such substances generally have a pKb of 1-5. Usually the alkaline agent is a salt, such as an alkali metal carbonate, an alkaline earth metal carbonate or an alkaline earth metal hydroxide. Corresponding salts having a phosphate anion may also be used. Similarly, various metal oxides can be used. Organic bases such as amines are also possible. It is generally required that the alkaline agent be capable of raising the pH of the aqueous phase within the cathode to a sufficiently high level when water is added to the battery. It would appear that initially a slightly alkaline pH inside the cathode is advantageous for cell operation and especially for reducing or even eliminating voltage peaks in the beginning. But the above is only one possible explanation.

The alkaline agent should be selected so as to avoid passivation of the magnesium anode.

Therefore, strong alkaline substances such as sodium or potassium hydroxide cannot be used. Usually, the passivating agents cause strong alkaline conditions (at pH above 14) in the aqueous phase. Passivation is manifested by the degraded cell performance, which is reflected by the lower maximum voltage and uneven operation.

The slightly basic alkaline agent is preferably selected from the group consisting of magnesium *! > hydroxide, potassium carbonate and sodium carbonate. It has a concentration of about 0.1 to 10%, preferably 0.2 to 5.0%, by weight of the cathode.

In a particularly preferred embodiment, the cathode comprises manganese dioxide, potassium. 25 or sodium chloride and graphite powder. The chemical composition of the cathode is such that it contains about 70 to 85% by weight of manganese dioxide, 6 to 25% by weight of potassium or sodium chloride, 0.2 to 5.0% by weight of magnesium hydroxide and about 4 to 8% by weight graphite.

..,: In order to increase the strength properties of the cathode material, it is possible to mix the components with a binder. Particularly preferred binders comprise polymers such as chlorinated or

Polished polymers.

It has been found that the cell of the present invention can provide a voltage of 1.55 V to 1.95 V for a period of at least 10 minutes, calculated from point 9 of discharge, at a voltage variation of less than 25%, preferably less than 20%. , within the first 10 minutes. The variation is calculated from the initial voltage produced by the cell. During a 125 minute period, from 10 minutes after activation to 135 minutes after activation, the voltage does not decrease by more than about 30%, preferably not more than 25%. The voltage is usually 1.5 to 1.95 V for a period of at least 30 minutes.

Battery dimensions may vary. However, for a particularly interesting application in radiosondes, it is preferable to limit the dry weight of the battery to less than 150 g, usually about 80 to 120 g. The primary battery for this application comprises electrodes each having a thickness of about 0.1 to about 3 mm. The width of the cavity between the electrodes is usually about 1-4 mm.

The electrochemical reactions in the Mg / modified MnO 2 15 battery of the present invention are as follows:

The cathode reaction is 2 MnO 2 + 2H 2 O + 2e '- 2 MnOOH + 20H' (1) 20 ''! The anode reaction is *

Mg - »Mg2 + + 2 e '. (2) I · i · »'· <·'. In an aqueous solution, a passivating hydroxide layer is formed on the surface of the magnesium.

The passive layer can cause delay by preventing the electrode reaction and slowing the reaction speed. The delay is defined as the time it takes for the battery to be inserted until the battery: "'; the voltage reaches the required minimum voltage. At the beginning of the discharge into the passive layer, ..: punctate edges are formed and the layer is no longer completely repaired. Because metal is capable, '*. In order to be in contact with the electrolyte through pitting, the passivation gradually decreases.

,. \ Chloride enhances the formation of pitting edges. This passive layer decomposition 'I is mandatory for the battery.

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Magnesium as an electropositive metal, that is to say corrosion, is very easily oxidized. In addition to the desired electrode reaction (2), the anode undergoes a hydrogen-forming corrosion reaction: 5 Mg + 2 H2O -> Mg (OH) 2 + H2 ΔΗ = -353 kJ / mol (3) This corrosion reaction is strongly exothermic. In cold conditions, during radiosonde probing, the corrosion of the magnesium anode produces the heat needed to keep the battery temperature above 0 ° C. However, if too much corrosion catalysts such as ku-10 pairs, iron, chloride or bromide are present, the corrosion can produce excessive amounts of heat. As a result, the water evaporates, the electrolyte is reduced and the battery voltage drops. Copper and iron cause galvanic corrosion, whereas aggressive ions chloride and bromide cause pitting corrosion.

A battery of the type described above, comprising 12 cells, provides an average voltage of approximately 18 V. Under atmospheric conditions such as those encountered during radio sonication, a 12-cell battery delivers a current of 150 mA and a voltage of at least 15 V for a period of at least 135 minutes. . During the initial phase, which comprises the first 30 minutes of operation, the 12 cells connected to the earth produce a minimum voltage of 18 V, said · · *, 20 with a voltage variation of less than 25% during the first 10 minutes. ton with water after activation and discharge. Compared to a battery that does not contain a slightly alkaline alkaline material in the cathode material of the cell, the present battery does not have peak voltage peaks above 23.5V.

The present invention can be used in air rescue equipment, life jackets and lifeboats, emergency rockets, missiles, torpedoes and underwater research equipment.

_ *: * According to a preferred embodiment, the present battery is used as a power source for radio

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:: in probes.

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11 113417

Example A. Battery Construction 5 A battery having the structure shown in Figure 1 was prepared. The anode was AZ-31 magnesium alloy containing 3 wt% aluminum and 1 wt% zinc and manufactured by Spectrulite Consortium Inc. (USA).

The reactive cathode material was electrochemically precipitated manganese dioxide (EMD) from Tosoh Hellas (Greece). The amount of reactive material was sufficient for approximately 5 hours of operation. The cathode contained 79.5 wt% manganese dioxide, 11 wt% KCl and 0.5 wt% Mg (OH) 2. In addition, the cathodes contained 7% by weight of graphite as an electron conductor and 2% by weight of poly (tetrafluoroethylene) as a binder. The cathode alloys were milled for 30 seconds in Age M20 Universal. The powder was compressed into cathode pellets using a pressure of about 15,150 MPa.

The geometric cathode area of each cell was 15 cm 2. The cathode pellets had a thickness of about 0.14 cm. The electrodes were separated by a synthetic non-woven pad that was able to absorb Akti ointment.

20 »', the battery consisted of 12 cells connected in series with an inert film comprising graphite. accounts of doped poly (isobutylene). Short-circuit currents between the cells were eliminated by applying. with adhesive tape to the edge of the absorbent layer. The bottom of the battery was waxed and the sides closed. : with a sealing layer of impermeable plastic film.

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The battery was packed in an airtight film to prevent self-discharge. Before use; * to was activated by immersing it in tap water for three minutes. Absorbent layer: was able to absorb about 40 g water (3.3 g per cell). The electrolyte consisted of water and dissolved ions at the electrodes. The dry weight of the battery was 115 g. The dimensions of the battery were -30 inches: length: 60 mm, width: 29 mm and height: 64 mm.

12 113417 B. Simulations in the Atmospheric Chamber

Battery properties were studied in an atmospheric simulation chamber (Weiss, Germany) where temperature and pressure were adjusted to values similar to those of normal radioson-5 probes. Airflow during radiosonde probes was simulated with ventilation and the computer controlled temperature and pressure in the chamber and recorded their values. The duration of the simulation program was 135 minutes. During the first 30 minutes of the discharge, the temperature was 25 ° C and the pressure was 1015 mbar, since 30 minutes is the expected time required for the preparation of the sludge. The batteries were discharged using a 150 mA (10 mA cm ') DC 10 and were required to provide a minimum voltage of at least 15 V, which are typical values that a modern radiosonde needs. Battery voltage was measured during the simulation and plotted against time. The time that the battery voltage remained above the cut-off voltage was determined.

Voltage curves for the Mg / MnCh + KCl battery of the present invention, the FI patent application No. 20000947 and the Mg / CuCl battery in atmospheric simulations are plotted against time in Figure 3. The average voltage of the Mg / MnCh + KCl battery was over 17 V. Battery voltage slowly dropped and remained above minimum voltage (15 V) for the required 135 minutes.

20 As will be apparent from the results, the battery voltage of the batteries of the present invention »· • 1; rises to the minimum value (15 V) without the very high initial voltage of the reference battery; ; tehuippua. The slightly alkaline alkaline component cuts the initial battery voltage (peak * · • ·; ", pu) by about 2 to 3 V. The voltage remains above 15 V for an extended period.

t 1 «* · 1111 1 1 25 MnO2 cathode modified with ionizable alkali metal chloride and a slightly basic alkaline cathode component is well suited for use as a cathode material in water-activated form:. batteries. It should be emphasized that the risk of overheating is lower with the present invention; . non-standard batteries. Also, the new battery does not have '. the initial delay. Although the present battery delivers a slightly lower voltage than the · · · 30 Mg / CuCl battery, the raw material is cheaper and there is no problem with soluble metal ions. Since the components are non-toxic, the new cathode material is environmentally friendly.

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Claims (19)

A water-activated battery cell, characterized in that it comprises in combination - at least one anode (9) selected from the group consisting of magnesium and 5 aluminum and their alloys; and - at least one cathode (11) having a conductive component and an active cathode material consisting of manganese dioxide in close contact with the conductive component, an ionizable component which is an alkali metal chloride or an alkali metal chloride alloy which in the presence of water releases said chloride. aqueous solution, and a slightly alkaline alkaline agent capable of raising the pH of the aqueous phase inside the cathode when water is added to the cell, to at least 9 without inactivating the anode. Cell according to Claim 1, characterized in that the mildly basic alkaline agent comprises an alkaline agent which forms an aqueous solution having a pH of about 9 to about 13. A cell according to claim 1 or 2, characterized in that the mildly basic alkaline substance is selected from the group consisting of alkali metal carbonates, alkaline earth metal carbonates and alkaline earth metal hydroxides. . '. A cell according to claim 3, characterized in that the mildly basic alkali material is selected from the group consisting of magnesium hydroxide, potassium carbonate: '' and sodium carbonate. 25 Cell according to one of Claims 1 to 4, characterized in that the concentration of the slightly basic alkaline agent is 0.1 to 10%, preferably 0.2 to 5.0%, by weight of the cathode. : "'30 Cell according to one of Claims 1 to 5, characterized in that the anode (9) ': ·'. contains a minimum of 93% by weight of magnesium, 0-7% by weight of aluminum, 0-3% by weight. ' zinc and 0-2 mass% manganese. 14, 112417 Cell according to one of Claims 1 to 6, characterized in that the cathode (11) comprises potassium chloride or sodium chloride in an amount of 6 to 25% by weight, based on the weight of the cathode. Cell according to one of the preceding claims, characterized in that the conductive component of the cathode 5 comprises graphite, expanded graphite, activated carbon or carbon black. Cell according to Claim 5, characterized in that the graphite is mixed with an active cathode material, an ionizable component and a slightly alkaline alkaline material. 10 Cell according to claim 9, characterized in that the cathode (11) comprises a compressed, strong electrode layer consisting of manganese dioxide, potassium or sodium chloride, magnesium hydroxide and graphite powder. A cell according to claim 10, characterized in that the cathode (11) comprises from about 70 to 85% by weight of manganese dioxide, from 6 to 25% by weight of potassium or sodium chloride, from 0.2 to 5% by weight of magnesium hydroxide and from 4 to 8% by weight. mass% graphite. A cell according to any one of the preceding claims, characterized in that the anode i 20 (9) is disposed apart from the cathode (11) to define an intermediate space (10) therebetween which can be filled with an aqueous liquid forming an electrolyte. Cell according to Claim 12, characterized in that the intermediate space (10) contains absorbent material. 25 A cell according to claim 1, characterized in that it produces a voltage of 1.55 V to 1.95 V for an initial period of 10 minutes, calculated from the start of discharge, said voltage having a variation of less than 25% during this period. 30 * ·· '. A water-activated, delayed-acting primary battery (1) having a holder (4) which; . The battery contains at least two cells each comprising - at least one anode (9) which is magnesium, aluminum or their alloy, 15 113417 - at least one cathode (11) comprising a conductive component and an active cathode material in communication with the closely conductive component consisting of manganese dioxide, - an intermediate space (10) separating the anode cathode and a 5 inlet (6) leading to said intermediate space for introducing an electrolyte-forming liquid into the intermediate space, characterized in that the cathode (11) further comprises an ionizable component consisting of sodium chloride, potassium chloride or mixtures thereof, which releases the chloride compound in an electrolyte-forming aqueous fluid filled with cavity, and a slightly basic alkaline agent capable of raising the pH of the aqueous phase within the cathode, water is added to the noon, at least 9 without passivating the anode. Battery according to Claim 15, characterized in that it comprises a plurality of cells 15 connected in series with conductive membranes (8) mounted between the anode (9) of the cell and the cathode (11) of the adjacent cell, Battery according to Claim 15 or 16, characterized in that it comprises 12 cells connected in series to a minimum voltage of 18 V, said voltage having a variation of less than 25% during the first 10 minutes when the battery is activated with water. Battery according to one of Claims 15 to 17, characterized in that it comprises: This plate-shaped cells are connected in series with the anode of the cell abutting the cathode of the adjacent cells, the lateral sides of the battery being provided with a water-impermeable membrane. Use of a primary battery according to any one of claims 15 to 18 as a source of power in a radiosonde. »« I «»> »30 i * t t t» t t I> I ► • 113417 16 Paten tkrav: