JP3474721B2 - Non-melonized air battery - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-calorinized air battery, and more particularly, to a negative electrode active battery by regulating the bulk density and non-aqueous electrolyte ratio of non-melted zinc powder. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-caloric air cell having improved material flowability, discharge utilization rate, and liquid leakage resistance. [0002] Mercury is contained in zinc powder of a conventional air battery. However, in recent years, low-pollution has been demanded, and therefore, research and development of an air battery with a reduced mercury content have been started. As a result, the development of inhibitors, zinc alloys, and the like can provide an air battery with a reduced mercury content that is approximately the same as that of a mercury-containing air battery in terms of hydrogen gas generation, discharge deterioration, and other problems. It became so. [0003] However, when the negative electrode active material is filled, problems concerning the flowability of the negative electrode active material, such as failure to fill the negative electrode active material, and problems relating to the discharge utilization rate and the leakage resistance characteristics have been newly raised. FIG. 1 is a cross-sectional view showing the structure of a main part of an air battery. Reference numeral 1 denotes a positive electrode case having an air hole 2 on a bottom wall and having an open end at one end. Diffusion paper 3, water-repellent film 4, catalyst layer 5, and separator 6 on bottom wall
Are sequentially laminated to form the positive electrode assembly 7. The catalyst layer 5 is generally a mixture of activated carbon, manganese oxide (co-catalyst), carbon black and the like (conductive material), and is formed in a sheet shape. Reference numeral 8 denotes a gelled negative electrode active material layer containing a non-melting zinc powder and an electrolytic solution, which are laminated on the separator 6 of the positive electrode assembly 7. This gelled negative electrode active material layer is prepared, for example, by adding 40% by weight of an aqueous solution of potassium hydroxide (containing 2% by weight of zinc oxide) and 2% by weight (to the electrolyte) of sodium polyacrylate in a weight ratio (to the electrolyte). This is a kneaded body containing about 5 times the amount of non-melted zinc powder or non-melted zinc alloy powder. Further, reference numeral 9 denotes a negative electrode case whose inner wall surface electrically contacts the negative electrode active material layer 8 to seal the opening of the positive electrode case 1, and 10 denotes a space between the positive electrode case 9 and the sealed portion of the positive electrode case 1. The insulating gasket 11 interposed therebetween is a seal tape attached to the outer wall surface of the positive electrode case to seal the air hole 2 provided in the bottom wall surface of the positive electrode case 1. However, in recent years, with the growing interest in living environments, it has been a problem that harmful mercury is contained in batteries even though it is in a small amount. Further development of such batteries has been desired. However, there has been a problem that the flowability of the negative electrode active material using non-melonized zinc is deteriorated, or that the mercury-free battery has a problem such as deterioration of the discharge utilization rate and generation of liquid leakage. A first aspect of the present invention has been made in view of the above circumstances, and is an excellent battery which suppresses deterioration of the flowability of the negative electrode active material, the discharge utilization rate, and the deterioration of the liquid leakage resistance due to the mercury-free treatment. It is an object of the present invention to provide a non-melonized air battery having characteristics. [0010] In order to achieve the above object, a first aspect of the present invention is to provide a positive electrode case having an air hole in a bottom wall surface and having an open end at one end; A positive electrode assembly comprising a diffusion paper, a water-repellent film, a catalyst layer and a separator laminated on an inner wall surface, and a gelled negative electrode active material containing an electrolytic solution and a non-melonized zinc powder disposed in contact with the separator. Layer, and an insulating gasket interposed between the sealed portions of the negative electrode case and the positive electrode case, wherein the non-calorinized zinc powder of the negative electrode active material has a bulk density of non-calorinized zinc powder. 2.6 to 3.1 g / ml and an electrolyte solution ratio of 20 to 100
% Or a bulk density of 3.1 to 3.5 g / m
l, and the electrolyte ratio is 60 to 100%, or the bulk density is 3.5 to 3.8 g / ml and the electrolyte ratio is 80 to 100%.
It is characterized by being 100%. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a main part of a button type air battery (JIS standard PR44 type) according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a positive electrode case having an air hole 2 on a bottom wall and having an open end at one end, which is made of nickel-plated iron. Inside the positive electrode case 1, diffusion paper 3, water repellent film 4, catalyst layer 5, and separator 6
Are sequentially laminated to form the positive electrode assembly 7. Here, the diffusion paper 3 is kraft paper having a thickness of 50 μm,
Is a 100 μm thick polytetrafluoroethylene (PTF
E) The film and catalyst layer 5 are formed by mixing activated carbon with polytetrafluoroethylene powder to form a sheet having a thickness of 300 μm, and the separator 6 is a microporous polypropylene membrane having a thickness of 150 μm. Reference numeral 8 denotes a gelled negative electrode active material layer containing a non-melting zinc powder and an electrolytic solution, which are laminated on the separator 6 of the positive electrode assembly 7. This gelled negative electrode active material layer
10 to 120% by weight (based on zinc) of potassium hydroxide aqueous solution (containing about 2% by weight of zinc oxide), 1 to 3% by weight of sodium polyacrylate and non-melting of bulk density of 2.6 to 3.8 g / ml It is a gel-like mixture prepared by adding and blending about 500 g of zinc powder. The electrolytic solution may be an aqueous solution of an alkali metal such as sodium hydroxide in addition to the aqueous solution of potassium hydroxide. Further, reference numeral 9 denotes a negative electrode case in which the inner wall surface electrically contacts the negative electrode active material layer 8 while sealing the opening of the positive electrode case 1, and 10 denotes a space between the negative electrode case 9 and the sealed portion of the positive electrode case 1. An insulating gasket 11 is interposed between the sealing gasket 11 and a sealing tape attached to the outer wall surface of the positive electrode case 1 for sealing the air hole 2 of the positive electrode case 1. Here, the negative electrode case 9 is made of, for example, a three-layer clad of nickel, stainless steel and copper, and the insulating gasket 10 is made of nylon. As described above, the negative electrode active material layer 8 has a bulk density of 2.6 to 3.1 g / ml and an electrolytic solution ratio of 20 to 10 g / ml.
0% (mass% ratio of electrolyte to zinc powder 100), bulk density of 3.1 to 3.5 g / ml and electrolyte ratio of 60 to 100%, bulk density of 3.5 to 3.5 3.8
g / ml with an electrolyte ratio of 80 to 100%.
Fifty (5) Examples (Examples 1 to 15) of 50 non-molten air cells were assembled and produced. Further, as a comparative example, the bulk density is 2.6 to 3.
8 g / ml of non-melonized zinc powder, electrolyte ratio 20 to 100
% Of non-calorinized air batteries using 5% anode active material (Comparative Example 1)
-Comparative Example 5), with a bulk density of 2.6 g / ml or more and 3.8 g / ml
Twenty-two 50 non-melonized air batteries (Comparative Examples 6 to 27) each using a negative electrode active material having an electrolyte solution ratio of 10 to 120% in a volume of not more than 50 ml were prepared. In addition, the measuring method of the bulk density was performed based on "JIS Z2504". With respect to each of the air batteries of the embodiment and the comparative example having the above-described configurations, the following evaluations were made, that is, the utilization rate of zinc in 250Ω continuous discharge and the high-temperature storage leakage test (45 ° C.
93% RH, 60 days) and overdischarge resistance test (20
° C-60% RH · 620Ω / 360hrs. ),
The results are summarized in Tables 1 and 2. [Table 1] [Table 2] As is clear from Tables 1 and 2, in the air batteries according to the present invention (Examples 1 to 15), neither over-discharge leakage nor high-temperature storage leakage occurred. The flowability and utilization of the negative electrode active material were also good. On the other hand, in Comparative Examples 1 to 5, since the zinc utilization was low, over-discharge leakage occurred. In Comparative Examples 6 to 9, the flow rate of the negative electrode active material was poor due to the low ratio of the electrolytic solution, and the utilization rate was poor and over-discharge leakage occurred (Comparative Examples 7 to 9). There was also. Further, in Comparative Examples 10 to 13, since the electrolytic solution ratio was 120%, which was excessive with respect to the amount of zinc, liquid leakage occurred during high-temperature storage. Comparative Examples 14 to 19
However, since the bulk density is low, the flowability of the negative electrode active material is poor. In Comparative Example 20, since the electrolytic solution ratio was 120%, which was excessive with respect to the amount of zinc, liquid leakage occurred during high-temperature storage. In Comparative Examples 21 to 27, the utilization rate was poor because the bulk density was too high, and there were also those in which the electrolyte ratio was low and the flowability was poor (Comparative Example 21). The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the invention. For example, the type of air battery is JI
It may be other than the S standard PR44. The above Examples and Comparative Examples are briefly shown in Table 3 below. [Table 3] As can be seen from Table 3, according to the non-calorinized air battery of the present embodiment, the bulk density of the non-calorinized zinc powder as the negative electrode active material is 2.6 to 3.8 g / ml, and the electrolytic solution ratio is 20 ~
100% (mass% ratio of electrolyte to zinc powder 100)
, A bulk density of 3.1 to 3.5 g / ml and an electrolyte ratio of 60 to 100%, a bulk density of 3.5 to
Whatever 3.8 g / ml and 80% to 100% of the electrolytic solution ratio can be used, it is possible to suppress the deterioration of the flowability, discharge utilization factor, and leakage resistance when filling the negative electrode active material. it can. As described above, the present invention controls the flow rate of the negative electrode active material generated when the bulk density of the non-melonized zinc powder is too small by controlling the bulk density of the non-melted zinc powder and the electrolyte ratio. It is possible to improve the problems such as the deterioration of the electrolyte, the leakage during high temperature storage that occurs when the electrolyte ratio is too large, and the poor combination of the bulk density of the non-melonized zinc powder and the electrolyte ratio and the decrease in the discharge utilization rate. It becomes possible. The action mechanism in this case is considered as follows. First, when the bulk density of the zinc powder decreases, the particle shape becomes a needle shape having a large surface area per weight, and conversely, when the bulk density increases, the particle shape becomes a spherical shape having a small surface area per weight. In the present invention, since non-melted zinc powder is used, the surface is rougher than the conventional zinc-melted powder.
When filling the negative electrode active material, fluidity is lacking. Therefore, in order to obtain the same level of fluidity as before, it is necessary to use spherical zinc powder, that is, non-melted zinc powder having a large bulk density. However, since the spherical zinc powder has a small surface area, the diffusion of reaction products around the zinc powder during discharge becomes poor, which causes a decrease in discharge utilization. In addition, the decrease in the discharge utilization rate is caused by the generation of gas between the unreacted zinc and the discharge products (zinc oxide, zinc hydroxide, etc.) after the discharge, causing an increase in the internal pressure, and through the blisters and air holes of the battery. Electrolyte leakage. However, in the present invention, the diffusion of the reaction product can be relatively improved by increasing the amount of the electrolytic solution.
At the same time, leakage due to gas generation can be improved. The amount of the electrolytic solution to be increased has an optimum value depending on the shape of the zinc powder to be mixed, that is, the bulk density, for the above-mentioned reason. In the present invention, the range is determined by experiments. As described above, according to the first aspect of the present invention,
According to the method, it is possible to provide a non-aqueous air battery having excellent battery characteristics by suppressing deterioration in flowability, discharge utilization rate, and liquid leakage resistance when filling the negative electrode active material.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of an essential part of an air battery according to an embodiment of the present invention. [Description of Signs] 1 ... Positive electrode case, 2 ... Air holes, 3 ... Diffusion paper, 4 ... Water repellent film, 5 ... Catalyst layer, 6 ... Separator, 7 ... Positive electrode assembly, 8
... negative electrode active material layer, 9 ... negative electrode case, 10 ... insulating gasket, 11 ... seal tape.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01M 12/06 H01M 4/42 H01M 4/06

Claims (1)

(57) [Claim 1] A positive electrode case having an air hole on the bottom wall surface and one end open, and a diffusion paper, a water-repellent film, a catalyst layer and A positive electrode assembly formed by stacking separators, a gelled negative electrode active material layer containing an electrolytic solution and a non-melonized zinc powder disposed opposite to the separator, and sealing the negative electrode case and the positive electrode case. A non-melting air cell having an insulating gasket interposed between the parts,
The bulk density of the non-melonized zinc powder of the negative electrode active material is 2.6 to
An electrolyte solution ratio (mass% ratio of electrolyte solution to zinc powder 100) of 3.1 g / ml to 20 to 100%, or a bulk density of 3.1 to 3.5 g / ml and electrolyte solution ratio of 6
0 to 100%, or a bulk density of 3.5 to
A non-melting air battery characterized in that the electrolyte solution ratio is 3.8 to 100% at 3.8 g / ml.