A dry cell comprising a zinc anode, a depolarizing mix and a separator which functions to separate the anode from the depolarizing mix, said depolarizing mix containing manganese dioxide as its main component and acetylene black immersed in an electrolyte having zinc chloride as its main ingredient, said depolarizing mix containing water and chlorine in an amount of about 50 to 90 parts by weight and about 5.5 to 14.5 parts by weight, respectively, per 100 parts by weight of manganese dioxide, the chlorine being present in the form of said zinc chloride or zinc chloride with added hydrochloric acid; said depolarizing mix also containing said electrolyte in an amount in millimeters determined by multiplying the BET total surface area of manganese dioxide and acetylene black in m2 /gram by a value of about 0.008 to 0.015, and said depolarizing mix further containing the electrolyte in an amount of about 2 to 4 ml. per gram of acetylene black.
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16. A depolarizing mix for use in a dry cell comprising a mixture of manganese dioxide, acetylene black, and an electrolyte having zinc chloride as its main ingredient, said depolarizing mix containing water and chlorine in an amount of about 50 to 90 parts by weight and about 5.5 to 14.5 parts by weight, respectively, per 100 parts by weight of manganese dioxide, the electrolyte being present in said depolarizing mix in an amount in milliliters determined by multiplying the BET total surface area of manganese dioxide and acetylene black in m2
/gram by a value of about 0.008 to 0.015. 17. A depolarizing mix for use in a dry cell comprising a mixture of manganese dioxide, acetylene black, and an electrolyte containing about 2 to 3.4 percent by weight of ammonium chloride and having zinc chloride as its main ingredient, said depolarizing mix containing the electrolyte in an amount of about 2 to 4 ml. per gram of acetylene black, the content of water and chlorine in said depolarizing mix being about 50 to 90 parts by weight and about 5.5 to 14.5 parts by weight, respectively, per 100 parts by weight of manganese dioxide, the chlorine being present in the form of said zinc chloride or zinc chloride with added hydrochloric acid.
1. A dry cell comprising a zinc anode, a depolarizing mix and a separator which functions to separate the anode from the depolarizing mix, said depolarizing mix containing manganese dioxide as its main component and acetylene black immersed in an electrolyte containing about 2 to 3.4 percent by weight of ammonium chloride and having zinc chloride as its main ingredient, said depolarizing mix containing water and chlorine in an amount of about 50 to 90 parts by weight and about 5.5 to 14.5 parts by weight, respectively, per 100 parts by weight of manganese dioxide, the chlorine being present in the form of said zinc chloride or zinc chloride with added hydrochloric acid.
2. A dry cell having a zinc anode, an electrolyte containing zinc chloride as its main ingredient, and a depolarizing mix containing a mixture of manganese dioxide, acetylene black, and said electrolyte, said depolarizing mix containing water and chlorine in an amount of about 50 to 90 parts by weight and about 5.5 to 14.5 parts by weight, respectively, per 100 parts by weight of manganese dioxide, the electrolyte being present in said depolarizing mix in an amount in milliliters determined by multiplying the BET total surface area of manganese dioxide and acetylene black in m2 /gram by a value of
about 0.008 to 0.015. 3. A dry cell having a zinc anode, an electrolyte containing about 2 to 3.4 percent by weight of ammonium chloride and having zinc chloride as its main component, and a depolarizing mix containing a mixture of manganese dioxide, acetylene black, and said electrolyte, said depolarizing mix containing the electrolyte in an amount of about 2 to 4 ml. per gram of acetylene black, the content of water and chlorine in said depolarizing mix being about 50 to 90 parts by weight and about 5.5 to 14.5 parts by weight, respectively, per 100 parts by weight of manganese dioxide, the chlorine being present in the form of said zinc chloride or zinc chloride with added hydrochloric acid. 4. The dry cell of 5. The dry cell of
chloride in the electrolyte is about 13 to 27 parts by weight. 6. The dry cell of claim 3, wherein the concentration of zinc chloride in the electrolyte is about 13 to 27 parts percent by weight. 7. The dry cell of
8. The dry cell of
9. The dry cell of
weight. 10. The dry cell of claim 1, wherein the separator is coated with a paste material in an amount of about 8 to 70 g./m2. 11. The dry cell of claim 10, wherein the paste material is starch or methyl cellulose. 12. The dry cell of claim 1, wherein the weight ratio of manganese dioxide to acetylene black is about 4/1 to 7/1. 13. The dry cell of
acetylene black is about 4/1 to 7/1. 14. The dry cell of claim 3, wherein the weight ratio of manganese dioxide to acetylene black is about 4/1 to 7/1. 15. A depolarizing mix for use in a dry cell comprising manganese dioxide as its main component and acetylene black immersed in an electrolyte containing about 2 to 3.4 percent by weight of ammonium chloride and having zinc chloride as its main ingredient, said depolarizing mix containing water and chlorine in an amount of about 50 to 90 parts be by weight and about 5.5 to 14.5 parts by weight, respectively, per 100 parts by weight of manganese dioxide, the chlorine being present in the form of said zinc chloride or zinc chloride with added hydrochloric acid. 18. The depolarizing mix of
19. The depolarizing mix of
20. The depolarizing mix of
21. The depolarizing mix of
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The present invention relates to a dry cell. More particularly, it relates to improvements in a dry cell containing a zinc anode and a depolarizing mix, the depolarizing mix containing as its main component manganese dioxide immersed in an electrolyte. The electrolyte has zinc chloride as its main ingredient. The improved dry cell of the present invention possesses an increased cell efficiency.
In conventional Leclanche-type dry cells, ammonium chloride has been used as the main electrolyte. A generally accepted cell reaction is as follows:
2MnO2 +Zn+2NH4 Cl→Mn2 O3 +H2 O+Zn(NH3)2 Cl2
As calculated from the above cell reaction, the amount of ammonium chloride necessary is about 61 parts by weight per 100 parts by weight of manganese dioxide. Such a large amount of ammonium chloride cannot be added as a liquid electroyte. Thus the additional amount thereof should be added in the solid form by tempering the depolarizing mix with the solid ammonium chloride and molding it into a shape. The addition of such a large amount of the ammonium chloride to conventionally employed dry cells naturally results in limiting the amount of active material of the cathode or manganese dioxide and the conductive adjunct or acetylene black to be added. During discharge it also causes the formation of zinc diamine chloride, Zn(NH3)2 Cl2, etc., in and around the depolarizer mix. The zinc diamine chloride thus formed prevents the diffusion of ions and electronic conduction in the depolarizing mix, resulting in an increase in the internal resistance of the dry cells. Thus the cell efficiency is adversely affected.
In order to diminish these defects, it has been proposed to limit the amount of the water in the depolarizing mix within a ratio of 23 to 39 percent by weight by tempering the depolarizing mix with an electrolyte of a water solution of zinc chloride to an extent of 15 to 40 percent by weight. Another proposed improvement restricts the amount of electrolyte in the depolarizer mix to about 60 to 71 percent by A 6 parts by weight per one part by weight 4 ml per gram of acetylene black. An insufficient amount of electrolyte may impair the reaction of manganese dioxide and diminish the ionic conductivity of the depolarizing mix as a whole. On the contrary, an excessive amount of electrolyte is not desirable for the electronic conductivity of the dry cells. A surplus of the electrolyte may be impregnated into the contact surfaces between the depolarizer mix particles which increases the contact resistance between the particles.
The following examples serve to be illustrative of the present invention, but are not to be considered as limiting.
A mixture of 82 g. of manganese dioxide, 18 g. of acetylene black and 1.3 g. of zinc flowers was gradually added, while stirring, to 45 g. of an electrolyte containing 20 parts by weight of zinc chloride and 5 parts by weight of ammonium chloride. After the manganese dioxide and acetylene black were fully immersed, a depolarizing mix was prepared by taking 18 g. from such a mixture and molding it into a cylindrical shape having a diameter of 19 mm. and a length of 30 mm.
A piece of kraft paper was coated on its one side with a paste material such as starch or methyl cellulose in an amount of 40 g. per square meter to form a paste layer. A separator made of this material was inserted into the zinc can with the paste material layer facing the inner wall of the can and being in contact with said can.
The cylindrically shaped depolarizing mix was then put into the can. Then, 4.7 g. of said electrolyte was poured onto the depolarizing mix and at the same time, immersed into the separator, functioning to solidify the paste material. A carbon rod was then forced upright into the center of the depolarizer mix, and a dry cell was assembled by conventional procedures.
The UM-2 dry cell in the depolarizing mix, manganese dioxide and acetylene black in a ratio of 4.5/1 by weight of manganese dioxide to acetylene black, water in an amount of about 74 parts by weight and chlorine present as zinc chloride in an amount of about 10 parts by weight per 100 parts by weight of manganese dioxide. The electrolyte is present in an amount of about 4.5 parts by weight per one part by weight of acetylene black.
The UM-2 dry cell possesses the following advantageous cell characteristics:
| TABLE 6 |
| ______________________________________ |
| Discharge Duration |
| Discharge Conditions of Time |
| ______________________________________ |
| Continuous Discharge at 2 ohms |
| 130 minutes |
| Intermittent Discharge at 2 ohms |
| 180 minutes |
| Continuous Discharge at 75 ohms |
| 170 hours |
| Intermittent Discharge at 75 ohms |
| 170 hours |
| ______________________________________ |
A depolarizing mix was prepared with 19 g. of the same mixture as produced in Example 1. A UM-2 dry cell was assembled by the same procedures as mentioned above.
The dry cell contains manganese dioxide and acetylene black in a ratio, by weight, (manganese dioxide/acetylene black) of 82/18 and about 3.3 ml. of the electrolyte per gram of acetylene black.
The dry cell possessed the same cell characteristics as those obtained in Example 1 and shown in Table 6.
11 g. of manganese dioxide having a BET surface area of 50 m2 /g. was mixed with 2 g. of acetylene black having a BET surface area of 70 m2 /g. The total surface of this mixture is 50×11+70×2=690 (m2). The amount of electrolyte was 8.28 ml. which was determined by multiplying the total surface area thereof by 0.012. Of the 8.28 ml. of the electrolyte to be added, 5.0 ml. was added to said mixture to immerse the manganese dioxide and acetylene black. Then, the depolarizer mix was molded into a cylindrical shape having a 19 mm. diameter and a 30 mm. length.
The depolarizing mix was placed in a zinc can containing a separator prepared by the same procedures as in Example 1. Onto the depolarizing mix placed in the can, was poured an additional 3.28 ml. of the electrolyte. The dry cell was then assembled in the same manner as stated above.
The UM-2 dry cell also exhibited the same characteristics as those produced in Example 1 and shown in Table 6.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included herein.
Uetani, Yoshio, Ikebata, Rokurou, Togo, Takayuki, Iwamaru, Tugiyasu
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