JPH077669B2 - Method for manufacturing non-aqueous electrolyte battery - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a non-aqueous electrolyte battery in which an oxyhalide is used as a solvent of an electrolytic solution and a positive electrode active material, and an alkali metal such as lithium metal is used as a negative electrode active material.

[Background technology]

In this type of battery, for example, as shown in FIG.
A carbonaceous molded positive electrode and other battery elements that are made by closely adhering a negative electrode made of a plate of an alkali metal such as lithium metal to a negative electrode can such as stainless steel and facing the negative electrode with a glass fiber separator inside A hermetic seal in which an electrolyte solution in which an electrolyte such as lithium aluminum chloride is dissolved in an oxyhalide such as thionyl chloride or sulfuryl chloride that also serves as a positive electrode active material is injected, and then a metal lid is welded to the can opening. The inside of the battery has a sealed structure.

The above-mentioned carbonaceous molded positive electrode is made of a carbon material such as acetylene black or graphite and a resin vanida such as polytetrafluoroethylene, and generally has a void of about 70% by volume or more, and the electrolysis is performed in the void. A liquid is impregnated to cause a discharge reaction. This discharge reaction is a reaction between an oxyhalide as a positive electrode active material and a negative electrode ion such as lithium ion, and produces a reaction product insoluble in an electrolytic solution such as lithium chloride.

Therefore, it is desired that the positive electrode has a void that can sufficiently impregnate and hold the electrolytic solution and that the reaction product can be easily accumulated and the discharge reaction can smoothly proceed. However, it cannot be said that the conventional molded positive electrode of this type always satisfies the above-mentioned required characteristics.

That is, a conventional molded positive electrode of the related art is obtained by kneading the carbon material and the resin binder as described above with water containing alcohol, granulating the same by a suitable means to a predetermined particle size, and then drying the dried granulated product. Was weighed in a predetermined amount and compression-molded in a mold. FIG. 3 schematically shows a result of observing a cross section of the conventional positive electrode with a microscope.

As is clear from this figure, this type of positive electrode is
Generally, small voids 40, 40, ... Formed between the particles of the carbon material particles and the resin binder particles used,
And has the above-mentioned voids 40 between the granules 30, 30 ,.
.. are present, which are larger and more non-uniform, and the two voids 40, 50 have a predetermined porosity.

Here, the products of the discharge reaction are easily accumulated in the voids 40. This is because the discharge reaction proceeds smoothly because the carbon material is present in the vicinity of the void 40. On the other hand, since the void 50 does not have a carbon material in its immediate vicinity, it hardly participates in the place of the discharge reaction even if the electrolytic solution is sufficiently impregnated and held in the void 50. Does not contribute as much.

That is, the conventional molded positive electrode has a small void portion in which the product of the discharge reaction can be easily accumulated and a large void portion in which the product is hard to be accumulated, and the large void portion is hard to be accumulated. The size and shape of 50 are not always constant. For this reason, the discharge reaction does not proceed smoothly as a whole, and as a result, there arises a problem that the discharge voltage decreases and a stable discharge voltage cannot be obtained.

[Object of the Invention]

An object of the present invention is to provide a non-aqueous electrolyte battery which can solve the above-mentioned conventional problems and can obtain a high and stable discharge voltage.

[Outline of Invention]

When the method of granulating the carbon material and the resin binder and compressing and molding the carbon material and the resin binder as described above when molding the carbonaceous positive electrode, the present inventors have found that the size of the voids in the granulated material and between the granulated material is large. Since it is unavoidable that there is a difference in size, porosity is 70% without using this granulation method.
A method for obtaining a highly porous molded positive electrode having a volume percentage of more than 100% was examined.

As a result, when a water-containing kneaded material containing a carbon material and a resin binder is molded into an appropriate shape by extrusion molding and water and other volatile components are dried and removed after the molding, the molded body has a high porosity and is spread over the entire molded body. Then, a porous molded positive electrode having substantially constant voids was obtained, and it was found that a non-aqueous electrolyte battery using this positive electrode has a high discharge voltage and is stable, and thus completed the present invention.

That is, in this invention, after extruding a water-containing kneaded product containing carbon particles, resin binder particles and a low boiling point water-soluble organic solvent, the low boiling point volatile matter consisting of the solvent and water is dried by heating to be removed. According to the method for producing a carbonaceous molded positive electrode, the carbonaceous molded positive electrode produced by this method, the size of the voids between particles composed of carbon particles and resin binder particles is 0.1 mm or less and the positive electrode Consisting of non-granulated particle binders that are substantially uniform throughout
Moreover, this positive electrode is characterized by having a porosity of 70 to 90% by volume. Thus, a molded positive electrode having such a high porosity and a constant size of voids among particles has never been known. It has a novel and extremely useful constitution as a positive electrode of a non-aqueous electrolyte battery which has never been used.

Hereinafter, the present invention will be described in detail with reference to the drawings.

In FIG. 1, 1 is a negative electrode can such as a stainless steel deep-drawing can also serving as a negative electrode terminal, 2 is a negative electrode made of an alkali metal plate such as a lithium metal plate, 3 is a separator such as glass fiber nonwoven fabric, 4 Is a carbonaceous molded positive electrode facing the negative electrode 2 with the separator 3 interposed therebetween, 5 is a positive electrode current collector made of stainless steel or the like, 6 is a metal lid made of stainless steel or the like, and the outer periphery of the metal lid 6 is Side is negative electrode can 1
After the glass seal 7 is welded to the inner peripheral surface of the opening of the metal lid 6 and the glass seal 7 is formed on the inner peripheral side of the metal lid 6, the electrolytic solution 9 is injected from the metal pipe 8 previously welded to the seal 7, and then the positive electrode current collector. 5 and the metal pipe 8 are welded together to form a sealed structure inside the battery.

The electrolytic solution 9 contains an electrolyte such as lithium aluminum chloride and thionyl chloride (SOCl ₂ ) or sulfuryl chloride (SO ₂ C).
The compound is dissolved in an oxyhalide such as l), and the oxyhalide functions as a positive electrode active material together with the role of the solvent of the electrolytic solution.

In this configuration, the carbonaceous molded positive electrode 4 has voids 41, 41 between particles composed of carbon particles and resin binder particles, as shown in FIG. The size of ,, ... is substantially uniform throughout the positive electrode and is composed of a non-granulated particle-bonded body having a porosity of 70-90.
The volume% is set, particularly preferably 80 to 90% by volume.
That is, this positive electrode 4 is characterized by not having the granules 30 as shown in FIG. 3, and thus not having the voids 50 between the granules. The size of voids between particles is not necessarily the same due to the difference in size of the particles themselves from the above-mentioned substantially, but since there is no granulated substance, voids between particles as in the conventional structure. It means that there is no big difference in the above and that they are almost the same as a whole.

The size of the voids 41 between the particles is usually 0.1 mm or less,
This is fundamentally different from the conventional configuration shown in FIG. 3 in which there are generally 0.3 mm to 1.0 mm of voids, and in particular, there are many voids of 0.8 mm or more. The positive electrode 4 forming the void 41.
The carbon particles, which are one of the constituent materials, are usually 70 to 100% by weight of carbon black such as acetylene black, which has a large surface area and is effective for discharge reaction, and 30 to 0% by weight of graphite, which contributes to the improvement of the mechanical strength of the positive electrode 4. %, The average particle size of the carbon black is 40 to 70 mμ, and the average particle size of the graphite is about 10 to 30 μm. As the resin binder particles, which is another constituent material of the positive electrode 4, fluorine resin powder such as polytetrafluoroethylene powder is preferably used because it is stable to oxyhalides and does not adversely affect the discharge reaction. , The average particle size of this powder is 0.1 ~ 1.0μ
m, the amount used is 5 with respect to 100 parts by weight of the carbon particles
It is about 15 parts by weight.

The carbonaceous molded positive electrode 4 having such a structure is easily manufactured by an extrusion molding method. That is, water containing a water-soluble organic solvent having a low boiling point for improving the wettability of carbon black such as lower alcohols such as methyl alcohol and ethyl alcohol, the carbon particles and the resin binder particles having the above-mentioned constitution and use ratio. Then, the kneaded product is directly subjected to an extrusion molding machine to be extruded into a column of the size (diameter) of the positive electrode 4 and then cut into a predetermined size (height), followed by heating and drying, if necessary vacuum. The molded positive electrode 4 having a high porosity can be obtained by heating and drying below to remove the low boiling point volatile matter composed of the solvent and water.

In the extrusion molding, the volatile components contained in the kneaded product during the molding are not separated, and the state of the kneaded product before being subjected to the molding is suppressed by suppressing the entrainment of air etc. It is important to mold with. That is, it is possible to manufacture the molded positive electrode 4 having the above-mentioned void ratio and having a uniform size of voids only by heating and drying to remove the volatile matter after performing such shaping.

As the extruder, a hydraulic type is preferably used, but a screw type can also be used. The extrusion pressure well to the ^{1~6kg / cm 2, 1kg / cm} 2 less than the extrusion difficult, whereas volatiles consisting becomes greater than 6 kg / cm ² with an organic solvent and water in an extrusion opening pressure Out,
Both are unsuitable because the porosity becomes small. In addition, in the screw extruder, it is desirable that the shapes of the extrusion nozzle and the screw and the rotation speed of the screw are appropriately set so that entrapment of air and separation of volatile components are eliminated.

The amount of the volatile component composed of the organic solvent and water is an important factor that determines the porosity and the size of the void, and thus needs to be set in an appropriate range. Generally, 110 to 20 per 100 parts by weight of the total amount of carbon particles and resin binder particles is used.
It is recommended to use 0 part by weight. The proportion of organic solvent in the volatile matter is preferably about 30 to 80% by weight. When a water dispersion such as polytetrafluoroethylene powder is used as the resin binder particles, the water contained therein may be used as one kind of volatile matter, and the total amount of volatile matter may be set within the above range. If the volatile content is too large, the size of the voids between the particles generally becomes large, and if it is too small, the mechanical strength of the molded product is impaired.

In FIG. 1, reference numeral 10 denotes a bottom paper made of the same material as the separator 3 for separating the bottom surface of the negative electrode can 1 from the positive electrode 4, and 11 a material made of the same material as the separator 3. The top paper is placed on the upper surface of the positive electrode 4.

〔The invention's effect〕

As is clear from the above description, the non-aqueous electrolyte battery of the present invention uses a high porosity carbonaceous molded positive electrode in which the voids between particles produced by an extrusion molding method are substantially uniform throughout the positive electrode. Therefore, the discharge reaction can proceed smoothly in the positive electrode, and the reaction product can be easily accumulated in the void. Therefore, it is possible to provide a non-aqueous electrolyte battery which is higher than the conventional one and can obtain a stable discharge voltage.

〔Example〕

Hereinafter, examples of the present invention will be described to more specifically describe.

90% by weight of acetylene black (average particle size: about 50 mμ) and 10% by weight of graphite (average particle size: about 15 μm) were well dry-mixed in advance. To 100 parts by weight of this mixture, an aqueous dispersion of polytetrafluoroethylene (solid content 60% by weight) 20
By weight, 120 parts by weight of methyl alcohol and 40 parts by weight of water were added and kneaded. This kneaded product was extruded into a column with a diameter of 10 mm by a hydraulic extrusion molding machine (extrusion pressure 4 kg / cm ² ), then cut into a size of 30 mm in height, and then vacuum dried at 130 ° C. A carbonaceous molded positive electrode having a rate of 88% by volume was obtained. The results of observing the cross section of this positive electrode with a microscope at a magnification of 20 times are shown in FIG. 2 in a simulated manner, and the size of the voids between the particles was 0.1 mm or less. The particles of polytetrafluoroethylene had a diameter of about 0.
It cannot be seen in the figure because it becomes 1 μm fibrous.

A non-aqueous electrolyte battery according to the present invention was obtained using the above-mentioned carbonaceous molded positive electrode in the following manner. That is, can diameter made of SUS304
0.8mm thick, 37mm wide, high on the inner surface of a 14mm, 47mm high negative electrode can
A 37 mm lithium metal plate was brought into close contact, a glass fiber nonwoven fabric was inserted as a separator inside the plate, and the carbonaceous molded positive electrode was inserted inside the separator. Next, while the metal lid welded metal pipe through the glass seal on the inner peripheral side is press-fitted into the opening of the negative electrode can to weld the press-fitted portion,
After injecting thionyl chloride in which lithium aluminum chloride was dissolved from a metal pipe, the injection port was sealed by welding to prepare a non-aqueous electrolyte battery of the present invention as shown in FIG.

When the relationship between the closed circuit voltage and the discharge time when the battery was discharged at a current of 10 mA was examined, the curve -A in FIG.
It was as shown in. The curve in FIG.
B is the result of the battery manufactured in the same manner as in the above-mentioned example except that the conventional carbonaceous molded positive electrode molded by the following method was used.

The above-mentioned conventional carbonaceous molded positive electrode is a mixture of 90% by weight of acetylene black and 10% by weight of graphite, which is the same as the example.
20 parts by weight of an aqueous dispersion of polytetrafluoroethylene (solid content 60% by weight), 60 parts by weight of methyl alcohol to 100 parts by weight
Parts by weight and 20 parts by weight of water were added and kneaded, and this was made into granules having a diameter of about 0.8 mm by a granulator. After vacuum-drying the granular material, a predetermined amount of the granular material was put into a mold and compression-molded to obtain a molded body having a diameter of 10 mm. This molded product was inserted into the negative electrode can in the same manner as described above, and pressed in this can to obtain a porosity of 85% by volume.
Of the molded positive electrode. The result of observing the cross section of the positive electrode with a microscope having a magnification of 10 is shown in FIG. 3, and the size of the voids between the particles of the positive electrode is 0.3 to 1.0 mm.
It was big and scattered.

As is clear from the results shown in FIG. 4, the battery of the embodiment of the present invention has a closed circuit voltage of 2.1 mV as compared with the battery of the conventional configuration.
It is understood that the battery has a stable discharge characteristic in which the voltage drop is not observed at all in the middle of discharge.

[Brief description of drawings]

FIG. 1 is a half cross-sectional view showing an example of the non-aqueous electrolyte battery of the present invention, and FIG. 2 is a diagram schematically showing a result of observing a cross-section of a carbonaceous molded positive electrode used in the battery with a microscope, FIG. Shows a conventional carbonaceous molded positive electrode, and FIG. 4 is a discharge characteristic diagram showing the non-aqueous electrolyte battery of the present invention in comparison with a conventional non-aqueous electrolyte battery. 2 ... Negative electrode, 3 ... Separator, 4 ... Carbonaceous molded positive electrode, 41 ...
Void, 9 ... Electrolyte

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Tomio Kitamura 1-188, Tora, Ibaraki-shi, Osaka Prefecture Hitachi Maxel Co., Ltd. (72) Inventor Yoshio Uetani 1-1-88, Tora, Ibaraki-shi, Osaka Hitachi Maxel Co., Ltd. (56) Reference JP-A-59-128772 (JP, A)

Claims (1)

[Claims] 1. A carbonaceous molded positive electrode comprising an oxyhalide as a solvent of an electrolytic solution and a positive electrode active material, and having a void which is impregnated with and holds an electrolytic solution which is opposed to a negative electrode made of an alkali metal via a separator. In a non-aqueous electrolyte battery consisting of, the above-mentioned carbonaceous molded positive electrode is extruded with a water-containing kneaded product containing carbon particles, resin binder particles and a low boiling point water-soluble organic solvent, and then low boiling point volatilization consisting of the solvent and water is carried out. By removing by heating and drying minutes, the carbonaceous molded positive electrode produced by this method, the size of the voids between the particles composed of carbon particles and resin binder particles is 0.1 mm. Manufacture of a non-aqueous electrolyte battery comprising a non-granulated particle binder in the following range and being substantially uniform throughout the positive electrode, and having a porosity of 70 to 90% by volume of the positive electrode. Law.