JPH022270B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a non-aqueous solvent battery, and particularly to a non-aqueous solvent battery in which the composition of the positive electrode is improved. [Technical background of the invention] Nonaqueous solvent batteries using lithium and sodium as negative electrode active materials have high energy density, excellent storage characteristics, and a wide operating temperature range, and are useful for backup of calculators, watches, and memories. It is widely used as a power source. Such batteries are composed of a negative electrode, an electrolyte, and a positive electrode, and generally, the negative electrode is lithium or sodium, and the electrolyte is lithium perchlorate, lithium perchlorate, etc. in a nonaqueous solvent such as propylene carbonate, γ-butyrolactone, or dimethoxyethane.
A solution prepared by dissolving an electrolyte such as lithium borofluoride is used, and manganese dioxide and graphite fluoride are used as the positive electrode, respectively. Among the batteries mentioned above, lithium is used for the negative electrode,
With thionyl chloride (SOCl ₂ ) as the main positive electrode active material,
So-called lithium-thionyl chloride batteries are attracting attention because of their particularly high energy density. This battery has a positive electrode made of a porous carbon body and a metal current collector, and generally uses thionyl chloride (SOCl ₂ ) in which lithium chloride (LiCl) and aluminum chloride (AlCl ₃ ) are dissolved as an electrolyte. Therefore, SOCl ₂ serves both as a positive electrode active material and as an electrolyte. In batteries using SOCl ₂ as the positive electrode active material, the negative electrode reaction is a reaction in which the negative electrode metal dissolves in the electrolyte as metal ions, while the positive electrode reaction is a reaction in which the negative electrode metal dissolves on the porous carbon material that is one of the constituent materials of the positive electrode. This is a reaction in which a reaction product is generated on the surface of the porous carbon body. By the way, the positive electrode used in the above-mentioned lithium thionyl chloride battery is made by mixing acetylene black with a polymer binder such as polytetrafluoroethylene, molding it into a predetermined shape, and drying it to obtain a porous carbon body and this porous carbon material. It consists of a metal current collector crimped onto a carbon body. [Problems with Background Art] However, in batteries equipped with conventional positive electrodes made of porous carbon bodies, electrode reactions are significantly inhibited and discharge capacity is reduced. In addition, large current discharge has the disadvantage that the discharge efficiency is significantly lower than that in low current discharge. Further, since the porous carbon body expands during drying of the molded body in its manufacturing process, it becomes difficult to insert the positive electrode into the battery case. [Object of the Invention] The present invention aims to provide a nonaqueous solvent battery equipped with a positive electrode made of a porous carbon material that has excellent discharge capacity and discharge efficiency during large current discharge, and has excellent dimensional stability. be. [Summary of the Invention] Among various types of carbon materials, the present inventors have discovered that carbon black, which has a structure in which a thin graphite crystal layer is formed on the circumferential surface of chain-shaped particles, has extremely high conductivity and specific surface area. By focusing on this, we have already developed a non-aqueous solvent battery with extremely excellent discharge characteristics by using a positive electrode consisting of a porous carbon body mainly composed of carbon black and a metal current collector crimped onto the carbon body. Proposed. However, subsequent research has shown that
It has been found that when the carbon black is kneaded with a polymer binder, molded, and then dried, the molded product shrinks, cracks, and breaks during drying. Therefore, the inventors of the present invention conducted further intensive research in view of the above-mentioned drawbacks, and as a result, by forming a porous carbon body mainly composed of a mixture of carbon black with the above-mentioned special structure and acetylene black, While taking advantage of the excellent properties of carbon black, the shrinkage of the molded product during drying can be offset by the addition of acetylene black, and the carbon black has excellent discharge capacity, discharge efficiency during large current discharge, and excellent dimensional stability. We discovered a water-solvent battery. The blending ratio of carbon black with a chain structure in which a thin graphite crystal layer is formed around the particles and acetylene black is 20 to 80% by weight of the carbon black;
It is desirable that the acetylene black be 80 to 20% by weight. The reason for this is that the amount of carbon black
If it is less than 20% by weight, not only will it be impossible to take full advantage of the excellent properties of carbon black, but also the amount of acetylene black, the other compounding material, will increase, causing the porous carbon body to expand and resulting in a decrease in dimensional stability. There is a risk of inviting On the other hand, if the amount of carbon black exceeds 80% by weight, shrinkage during drying due to the carbon black becomes obvious, making it difficult to obtain a porous carbon body free of defects. Moreover, the above-mentioned positive electrode is manufactured, for example, by the method shown below. First, acetylene black is blended with the above-mentioned carbon black with a special structure, and after adding and mixing a polymer binder such as polytetrafluoroethylene to this mixture, an organic solvent such as ethyl alcohol is further added and thoroughly stirred and kneaded. do. Next, this kneaded material is pressed onto a metal current collector such as a wire mesh, punched metal, expanded metal, etc., and dried to produce a positive electrode. [Embodiments of the Invention] Hereinafter, an example in which the present invention is applied to a lithium thionyl chloride battery will be described with reference to FIG. Embodiment 1 Reference numeral 1 in the figure is a can body made of stainless steel, for example, whose top surface is open and also serves as a negative electrode terminal. A cylindrical negative electrode 2 made of metallic lithium is pressure-bonded to the inner surface of the can 1. A positive electrode 3 is provided inside the can body 1 inside the negative electrode 2 with a separator 4 made of a non-woven glass fiber fabric disposed on the inner surface of the negative electrode 2 . Note that an insulating paper 5 is interposed between the positive electrode 3 and the bottom surface of the can body 1. The positive electrode 3 was manufactured by the following method. First, 45% by weight of carbon black (Ketchen Black; a product name manufactured by Lion Agzo Co., Ltd.), which has a chain structure in which a thin layer of graphite crystals is formed around the particles.
After mixing 45% by weight of acetylene black and 10 parts by weight of polytetrafluoroethylene powder, ethanol was added to the mixture at a rate of 8 ml per 1 g of the mixture and thoroughly kneaded. Subsequently, this kneaded product was formed into a cylindrical shape together with a metal current collector 6 made of a nickel mesh so that the current collector 6 was placed on the inner peripheral surface, and dried under vacuum at 200°C. Metal current collector 6
A cylindrical porous carbon body 7 was pressed onto the outer periphery of the positive electrode 3 to produce a positive electrode 3. Further, an insulating paper 8 having holes supported by the separator 4 is disposed inside the can body 1 above the positive electrode 3 . A metal top 9 is sealed to the opening of the can body 1 by laser welding or the like. A hole 10 is made in the center of this metal top 9. In the can body 1, 1.8 mol of LiAlCl ₄ was dissolved.
An electrolyte consisting of a concentrated thionyl chloride (SOCl ₂ ) solution is injected through the hole 10 in the metal top 9;
It is accommodated. Further, a positive electrode terminal 11 is electrically insulated and fixed in the hole 10 of the metal top 9 by a metal-glass sealing material 12. The lower end of this positive electrode terminal 11 is connected to the metal current collector 6 of the positive electrode 3 . Example 2 Butt chain black (manufactured by Lion Agzo) 25
A positive electrode was prepared in the same manner as in Example 1, except that a mixture consisting of 65% by weight of acetylene black and 10% by weight of polytetrafluoroethylene powder was used, and a lithium thionyl chloride battery having the same configuration was assembled. Comparative Example 1 A positive electrode was produced in the same manner as in Example 1, except that a mixture of 90% by weight acetylene black and 10% by weight polytetrafluoroethylene powder was used, and a lithium thionyl chloride battery having the same configuration was assembled. Comparative example 2 Butt chain black (manufactured by Lion Agzo) 90
A positive electrode was produced in the same manner as in Example 1, except that a mixture of 10% by weight and 10% by weight of polytetrafluoroethylene powder was used, and a lithium thionyl chloride battery having the same configuration was assembled. When 100 battery positive electrodes of Examples 1 and 2 and Comparative Examples 1 and 2 were each manufactured, and the diameters were measured before and after drying, the results shown in the table below were obtained. The table also includes the number of positive electrodes whose porous carbon body peeled off from the metal current collector after drying, or which were missing, as well as the number of positive electrodes that could not be inserted into the can due to expansion. [Table] As is clear from the table above, the positive electrodes used in the batteries of Examples 1 and 2 had little dimensional change, and there were no defects in the porous carbon body or defects in the can due to expansion of the carbon body. It can be seen that there is almost no problem of not being able to insert. In contrast, the positive electrode used in the battery of Comparative Example 1 had large dimensional variations after drying.
There are many items that cannot be inserted into the can body. In the positive electrode used in the battery of Comparative Example 2, many cracks occurred in the porous carbon body after drying, and many of the positive electrodes fell off from the metal current collector during the insertion process into the can. Further, when the constant load discharge characteristics of the batteries of Examples 1 and 2 and Comparative Examples 1 and 2 at room temperature of 300Ω were investigated, the characteristic diagram shown in FIG. 2 was obtained. In addition, in FIG. 2, A is the discharge characteristic curve of the battery of Example 1, B is the same curve of the battery of Example 2, and C is the discharge characteristic curve of the battery of Example 1.
is the same curve for the battery of Comparative Example 1, and D is the same curve for the battery of Comparative Example 2.
This is the same curve for the battery. As is clear from FIG. 2, the batteries of Examples 1 and 2 had longer discharge times than the battery (Comparative Example 1) equipped with a positive electrode made of a porous carbon body containing only acetylene black as a main component. Furthermore, it can be seen that the discharge voltage is high. In addition, although the batteries of Examples 1 and 2 had slightly inferior discharge characteristics compared to the battery (Comparative Example 2) equipped with a positive electrode made of a porous carbon body containing only Ketschen Black (manufactured by Lion Agzo) as a main component, , Comprehensively evaluated along with the table mentioned above, this Example 1,
It can be seen that 2 is superior. Note that in the above embodiments, a cylindrical positive electrode was used, but the positive electrode is not limited to this. For example, a spiral positive electrode may be used, in which a kneaded mixture of carbon black, acetylene black, and a polymer binder is pressed onto a metal current collector to form a belt, which is spirally wound and dried. [Effects of the Invention] As detailed above, according to the present invention, the discharge capacity is greatly improved, the discharge efficiency is also excellent, and a high-yield cathode comprising a porous carbon material with excellent dimensional stability is provided. A non-aqueous solvent battery that can be manufactured can be provided.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a lithium thionyl chloride battery showing an example of the present invention, and FIG. 2 is a characteristic diagram showing the relationship between discharge time and terminal voltage in batteries of this example and a comparative example. 1...Can body, 2...Negative electrode, 3 ...Positive electrode, 4...
Separator, 6... Metal current collector, 7... Porous carbon body, 9... Metal top, 11... Positive electrode terminal.

Claims (1)

[Claims] 1 A negative electrode made of a light metal selected from lithium, sodium, and aluminum and a positive electrode made of a porous carbon body and a metal current collector are provided in a can body with a separator interposed therebetween, and oxyhalogen of sulfur is provided in the can body. A mixture of carbon black and acetylene black having a chain structure in which a thin graphite crystal layer is formed around the particles as the porous carbon body in a non-aqueous solvent battery containing an electrolyte containing a compound as the main positive electrode active material. A non-aqueous solvent battery characterized by using a battery containing as a main component.