JPS6210860A - Silver oxide battery - Google Patents

Abstract

PURPOSE:To increase the capacity of a battery by using a positive mix comprising AgO particles covered with Ag2O fine particles and a complex oxide of Ag-Ni. CONSTITUTION:AgO particles 1 covered with Ag2O fine particles 2 are used as a positive active material. In order to completely cover the surfaces of particles 1, the amount of fine particles 2 is desired to limit to 20-70wt% of the total weight of the particles 1 and the fine particles 2. A complex oxide of Ag-Ni indicated in AgNiOX (1.0<X<=2.0) is used as conductive material of the positive mix. By using this positive mix, a battery having low internal resistance and large capacity can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application 1] The present invention relates to a silver oxide battery, and more particularly to a silver oxide battery having a large electric capacity and excellent storage stability.

[Prior Art] A silver oxide battery using silver oxide (AgO1Ag2o) as a positive electrode active material has a stable operating voltage, good reactivity,
In addition, because they have a high energy density, they are used extensively as batteries for wristwatches, for example.

By the way, silver oxide batteries for wristwatches are commonly used with a button-shaped structure and an operating voltage of 1.5V.
In recent years, as the demand for miniaturization of power supplies has increased, various attempts have been made to increase the electrical capacity of positive electrode active materials.

As such a method, first, one stroke of silver oxide (
There is a method of increasing the packing density of Ag20) to increase the substantial amount filled into the battery. However, Ag2O
Since the true density of 7.14 g/cnl is the theoretical limit, the amount of filling is limited and a significant increase in capacitance cannot be expected.

Therefore, approximately 1% of monovalent silver oxide (Ag20) is used as an active substance.
．． Silver divalent oxide (Age) with 11 times the theoretical capacity
was used, and AgNi0. (1,0<w≦2.
A silver oxide battery using a mixture of 0) as a positive electrode mixture has been proposed (Japanese Unexamined Patent Publication No. 78758/1983). However, in this silver oxide battery, Age is AgNi0!
There is a problem in that 02 gas is generated and blistering of the battery occurs.

Therefore, as an alternative to this, silver divalent oxide (Ago
) is discharged at the operating potential of Ag2O. In other words, as mentioned above, AgO is approximately
This is because it has a theoretical electric capacity of 1.9 times and is expected to be a powerful active substance. As a means to maintain the working potential of Ag2O using AgO as described in 1-1, for example, (a) the surface of a pellet obtained by pressure molding AgO is soaked in a reducing solution such as hydrazine or methanol; There are methods such as forming an Ag2O layer on the surface of the pellet by treatment, and (2) forming an Ag2O layer on the surface of AgO powder and press-molding it to form a positive electrode mixture. As described above, in order to maintain the potential of Ag2o using Ago, it is necessary to uniformly form the ag2o layer. In that case, the electrical resistance of the 4g2o layer is 108Ω・C11
, and this value is Ago's electrical resistance 1.2X10-2 ~
Since it is extremely large compared to 15 Ωψcm, the resistance value of the surface increases and the function as a battery deteriorates.

Therefore, in order to increase the overall conductivity of the IE electrode active material using Ag2o, it is necessary to perform some kind of treatment. Specifically, conventional methods include adding a conductive substance that does not decompose Ag2O, or forming a layer made of such a conductive substance to form a positive electrode mixture. is common.

For example, if there is an electric current on the surface of the 4g2o layer or Ag0 layer,
``It has been proposed to uniformly form a layer of metallic silver (Ag) with a very low resistance of 1.8XIO-6Ωcm.However, since the Ag layer is not an active substance, the electrical capacity of the entire battery is In addition, the thickness of this Ag layer may decrease or even disappear during the storage period after battery manufacture. This phenomenon occurs when the Ag layer is oxidized and converted to Ag2o due to ionic contact between the Ag layer on the surface and the Ag0 layer inside.
With this method, it was difficult to significantly increase and maintain the capacitance, since the reduction or disappearance of the layers would again increase the internal resistance of the cell.

[Means for Solving the Problems] The present invention aims to solve the conventional problems and provide a silver oxide battery that has a large electric capacity, a low internal resistance, and has excellent storage stability. do.

In order to achieve the above object, the present inventors discovered AgO and AgO.
As a result of extensive research into silver oxide batteries that include both AgO and AgO as cathode active materials, as will be described later, we found that AgO
One whose particle surface was coated with 4g2o fine particles, and one whose particle surface was coated with 4g2o fine particles, and Ag-N
The present invention was completed by confirming that excellent effects can be achieved when a positive electrode mixture consisting of a composite oxide and an i-complex oxide is used.

That is, the silver oxide battery of the present invention comprises divalent silver oxide particles whose surfaces are coated with fine particles made of monovalent silver oxide;
It is characterized by comprising a positive electrode mixture consisting of a silver/nickel composite oxide represented by AgNi0x (1,0<x≦2.0).

[Specific Description] The silver oxide battery of the present invention is characterized by comprising a novel positive electrode mixture as described above. This positive electrode mixture will be described in detail below.

That is, the positive electrode mixture used in the present invention is Ag2
Ag0 particles whose surfaces are coated with 0w1 particles are used as the first component, that is, for ilE polar crops. First, Ag0 particles have a particle size of 5 to 200 μm,
Furthermore, those with a particle size of 20 to 150 μm, 4g2o fine particles with a particle size of 0.05 to 8 μm, and even 0.1
It is preferable to use those having a diameter of 5 μm.

The surface of these 4g2o fine AgO particles is coated with an optimal film thickness, that is, the surface of the AgO particle is completely coated with Ag20.
For coating with WI particles, Ag20 used for coating
It is preferable to set the amount of fin particles to be 20 to 70% relative to the total weight of Ag0 particles and 4g2o fine particles. If the coating amount of the 4g2o fine particles is less than 20% by weight of ag2゜+AgO, the AgO
does not exhibit the unipolar potential of Ag2o, and on the other hand, even if 4g2o fine particles with more than 70 superpositions are blended, there is not much benefit in terms of capacitance. More preferably, it is about 30 to 60% by weight.

``One of the methods for producing AgO described in ``t'',
An example is the ozone oxidation method. This method is a method in which Ag2o particles are oxidized in a highly concentrated alkaline aqueous solution such as KOH or NaOH while passing ozone through the solution. At this time,
By introducing ozone into the solution, AgO precipitates and grain growth occurs, but during this grain growth, Ag
Due to the phase bud contact between the O particles and the stirring effect, the crystal grain surface becomes a high-density crystal grain while maintaining a curved surface.

In addition to such methods, e.g. sodium beroxonisulfate (Na2
A method of adding an oxidizing agent such as S20B) to oxidize the silver salt can also be applied.

The method of coating the Ag2° fine particles on the surface of the Ag0 particles thus obtained is not particularly limited, but for example, first, by immersing the Ag0 particles in an aqueous solution such as sodium polyacrylate. Surface treatment is performed, and then, before the aqueous solution dries, the above-mentioned Ag2° fine particles of the specified star are blended and mixed.
A preferred method is to adsorb 2O fine particles onto the entire surface of Ag0 particles and then dry them.

Next, Ag-N which is the second component of the positive electrode mixture of the present invention
The i-composite oxide has the formula as described above: AgNi0. (1,
0x≦2.0), and is a component that contributes to improving the conductivity of the entire positive electrode mixture. This Agi+o,
1 is Ag, a mixture of metals such as old nitrates, or Ag, N obtained by an alkali coprecipitation method.
A method in which a mixture of the hydroxides of i is calcined at high temperatures; a wet oxidation method in which both salts or hydroxides are similarly oxidized with an oxidizing agent solution such as hypochlorite chloride sulfate or hydrogen peroxide; It can be produced by applying a dry oxidation method or the like in which a coprecipitate obtained by alkalizing a mixed solution of Ag salt and monosalt is dried and then oxidized with ozone or the like.

The positive electrode mixture of the silver oxide battery of the present invention comprises Ag0 particles coated with the Ag2° fine particles described in -1- and the AgN io
, for example, by mechanically mixing the mixture and then press-molding it into a predetermined shape. AgN at this time
i0. The blending amount is 5 to 30% based on the total weight of the positive electrode mixture.
It is preferable to set the amount to be % by weight.

FIG. 1 schematically shows the phase structure of the positive electrode mixture thus obtained. That is, in the figure, Ag
The entire particle surface of the O particles is covered with Ag2O fine particles 2, and the Ag2O particles 2 are coated with Ag2O fine particles 2.
Ag-Ni composite oxide particles 3 are present at the grain boundaries of the O particles.

In such a positive electrode mixture, AgO operates at the electrode potential of Ag2O coated on its surface, and moreover, AgN
i0. Although it contacts Ag2O, it does not directly contact Ag0 particles, so there is no decomposition of Ago by AgNiOx, and it is possible to prevent blistering of the battery due to O2 gas during long-term storage. On the other hand, since AgaiO greatly contributes to the conductivity and also functions as a positive electrode active material, it has two excellent effects: reducing the internal resistance of the battery and increasing the electric capacity.

[Example] Example and Comparative Example A 5R821SW type silver oxide battery having the structure shown in FIG. 2 was manufactured. That is, a cathode mixture 12 is filled under pressure into a cathode container 11 made of Fe plated with Ni, and an electrolytic solution made of a porous fibrous material impregnated with an ion-permeable separator 13 and an alkaline electrolyte is placed in the cathode mixture 12. After storing the holding material 14, a metal negative electrode container 15 containing a gel electrode 16 is fitted into the positive electrode container 11 via an insulating gasket 17, and then the opening periphery of the positive electrode container 11 is fitted. The battery was sealed by bending the parts inward to complete a silver oxide battery.

In this battery, a mixture of a gelling agent powder such as sodium polyacrylate and an alkaline electrolyte such as potassium hydroxide was used as the gelled negative electrode 1B. On the other hand, as the positive electrode mixture 12 which is a feature of the present invention, the following was used.

That is, the average particle size 1 produced by applying the ozone oxidation method
00. , an apparent density of 3.2 g/cnl and 0.5 g/cnl of AgO.
Immersion treatment in 5% sodium polyacrylate aqueous solution,
Afterwards, Ag2011 with an average particle size of 0.8-
The particles were coated with the indicated coverage (Ag20/AgO+Ag20).

Further, AgNi0X used was one with x=2 obtained by drying a coprecipitate obtained by alkalizing a mixed solution of Ag salt and Ni salt and then performing dry oxidation with ozone. After that, this AgNi0! (x=2.0) was blended in an amount of 15% by weight of the entire positive electrode mixture to obtain positive electrode mixture 12.

The 60 silver oxide cells thus obtained were heated to 60°C.
The samples were stored for 40 days and the following evaluation tests were conducted.

(1) Change in internal resistance before and after storage Under IKHz alternating current, the internal resistance (Ω) before and after storage was determined by Δ1σ.

(2) Change in capacitance before and after storage When 58 was subjected to continuous discharge with a load resistance of Ω, the average value of the capacitance before and after storage was measured.

(3) Blistering of the battery after storage The amount of blistering (m-peng) of the battery after storage due to gas generation was measured.

The above results are summarized in the table.

For comparison, 1. Same as Example 1-2 using the positive electrode mixture composed only of AgO+Ag2O and not containing 0 AgNi and the positive electrode mixture containing AgNi0□ but having Ag2O-covered mIA outside the range 1-. 5R621SW type silver oxide batteries were manufactured, and 60 of each were subjected to the same evaluation test as above, and the results are shown in the table.
I wrote it as fit.

[Effects of the Invention] As is clear from the explanation below, the silver oxide battery of the present invention has a small internal resistance and a large electric current<Kt*M, and these values hardly change even after storage. It has excellent characteristics such as: Furthermore, there is no blistering after storage due to the generation of 02 gas. Therefore, the industrial value of the battery of the present invention is extremely large.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the constituent phases of the positive electrode mixture used in the silver oxide battery of the present invention, and FIG. 2 is a longitudinal sectional view showing the structure of the silver oxide battery.

Claims (1)

[Claims] 1. Divalent silver oxide particles whose surfaces are coated with fine particles made of monovalent silver oxide, and AgNiOx (1.0<x≦2
．． A silver oxide battery comprising a positive electrode mixture consisting of a silver/nickel composite oxide represented by 0). 2. The coating amount of the monovalent silver oxide fine particles is 20 to 70% based on the total weight of the monovalent silver oxide fine particles and the divalent silver oxide particles.
% by weight of the silver oxide battery according to claim 1.