JPS62188175A - Inorganic nonaqueous electrolyte battery - Google Patents

Abstract

PURPOSE:To increase discharge performance in high rate discharge by widening the surface area of acetylene black by crushing. CONSTITUTION:A molded porous carbon positive electrode is mainly comprised with acetylene black whose surface area is widened by crushing. Acetylene black has highly developed chain structure and the secondary particles formed by continuously bonding the primary particles compared with other carbon black. When acetylen black is crushed, the chain structure is broken to form the primary particles, and the surface area of acetylene black is widened. Since the fresh surfaces are developed by crushing, active sites are increased. Thereby, the catalytic function of acetylene black is enhanced, and reaction of positive active material is efficiently advanced even in high rate discharge, and discharge performance is increased. The crushing of acetylene black is performed with a vibration ball mill.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a carbon porous molded material in which an oxyhalide is used as a positive electrode active material and a solvent for an electrolytic solution, and is opposed to a negative electrode made of an alkali metal with a separator interposed therebetween. The present invention relates to an inorganic non-aqueous electrolyte battery equipped with a body positive electrode, and more specifically to improvements in the carbon porous molded positive electrode.

[Conventional technology]

In inorganic non-aqueous electrolyte batteries, in which oxyhalides that are liquid at room temperature such as thionyl chloride, sulfuryl chloride, and phosphoryl chloride are used as the positive electrode active material and the electrolyte solvent, and alkali metals such as lithium and sodium are used as the negative electrode, the positive electrode A carbon porous molded body made of acetylene black as a main component is used, and the positive electrode is placed opposite to the negative electrode with a separator in between (for example, Japanese Patent Laid-Open No. 58-121
Publication No. 563).

Acetylene black, which is the main component of the above carbon porous molded positive electrode, acts as a catalyst to reduce the oxyhalide, which is the positive electrode active material. Acetylene black is used as a component because it contains few impurities and is less likely to react with active materials such as oxyhalides to reduce discharge capacity.

However, acetylene black has a surface area of about 60r.
Since the tr/g is small, the activity is low, and therefore, concentration polarization becomes large in large current discharge, leading to problems such as unstable operating voltage and a significant decrease in discharge capacity.

[Problem that the invention seeks to solve]

The present invention solves the problem that conventional inorganic non-aqueous electrolyte batteries have insufficient activity due to the small surface area of acetylene black and are not suitable for large current discharge, and the operating voltage is stable even during large current discharge. An object of the present invention is to provide an inorganic non-aqueous electrolyte battery that exhibits excellent discharge characteristics such as a high discharge capacity and a large discharge capacity.

Means for Solving Problems c] The present invention destroys the aqueous structure of acetylene black by pulverizing the acetylene black, increases the surface area of acetylene black, increases its activity, and makes it excellent even in large current discharge. The present invention provides an inorganic non-aqueous electrolyte battery that exhibits excellent discharge characteristics.

In other words, acetylene black has a highly developed chain structure compared to other carbon blanks, and missing particles are linked in a chain to form secondary particles, but when acetylene black is pulverized, the chains are broken down. The spherical structure is destroyed and becomes primary particles, the surface area of acetylene black increases, and parts that did not appear on the surface before pulverization appear on the surface, and by the generation of this fresh surface, the number of active points increases. occurs, and the catalytic function of acetylene black increases,
Even during high-current discharge, the reaction of the positive electrode active material proceeds efficiently and the discharge characteristics are improved.

Acetylene black is usually ground in a vibrating ball mill. However, pulverization treatment may be carried out by other means. By this pulverization treatment, acetylene black had a nitrogen adsorption surface area of approximately 60rd/g and an iodine adsorption amount indicating activity of approximately 105mg/g before treatment. The nitrogen adsorption surface area is up to 200d/g and the iodine adsorption amount is up to 170e.
The degree of improvement in the zero surface area and the degree of improvement in the amount of iodine adsorption, which improves to about Adsorption amount is 110mg/g
As mentioned above, when the amount is preferably 125 mg/g or more, a noticeable difference in discharge characteristics occurs in large current discharge compared to acetylene black before pulverization treatment.

The carbon porous molded positive electrode is formed by using, for example, acetylene black as a main component which has been pulverized to increase the surface area as described above, and adding a binder such as polytetrafluoroethylene and preferably a strength-imparting agent to the acetylene black. Add graphite for the purpose, and then add liquid ingredients such as water and alcohol.
This is done by kneading, molding the mixture into a desired shape using an extruder or the like, and drying it to evaporate the liquid component to make it porous. When graphite is added to impart strength, the ratio of acetylene black and graphite used is usually preferably 95 to 85:5 to 15 by weight. Furthermore, forming a carbon porous molded positive electrode Whether or not the acetylene black used in the process has been pulverized can be determined by examining the presence or absence of a chain structure in the acetylene black using an electron microscope. Of course,
This confirmation using an electron microscope can be performed by collecting acetylene black from the molded product after molding.

〔Example〕

Next, the present invention will be explained in more detail by giving examples.

Example 1 Nitrogen adsorption surface [60n'r/g, iodine adsorption amount 105
An acetylene blank of 10 g/g was milled using a vibrating ball mill.
Pulverized for hours. As a result of this pulverization, the nitrogen adsorption surface area of acetylene black increased to 85 mT2/g, and the iodine adsorption amount increased to 120 mg/g.

An aqueous dispersion of polytetrafluoroethylene (solid content concentration 60i% by weight), 120ffi parts of methyl alcohol, and 250 parts by weight of water were added and kneaded, and the kneaded product was molded using a hydraulic extruder into a diameter of 1.
0, extruded into a 6mm cylindrical shape, length 33nu++
After cutting, it was vacuum dried at 130°C for 5 hours. A lithium-thionyl chloride type AA inorganic non-aqueous electrolyte battery having the structure shown in FIG. 1 was prepared using the thus obtained carbon porous molded body having a porosity of 85% by volume as a positive electrode.

In FIG. 1, 1 is a stainless steel battery case which also serves as a negative electrode terminal, 2 is a negative electrode made of metallic lithium, and 3 is a separator made of glass fiber nonwoven fabric. Reference numeral 4 denotes a carbon porous molded positive electrode arranged to face the negative electrode 2 with a separator 3 interposed therebetween, the main component of which is pulverized as described above to increase the surface area and increase the activity. Increased acetylene black. Reference numeral 5 indicates a current collector rod made of stainless steel, and reference numeral 6 indicates a battery cover. The main body of the battery cover 6 is made of stainless steel, and its outer circumference is welded to the open end of the battery case. A positive terminal 8 is provided in the center of the battery lid 6 through a glass seal 7. This positive terminal 8 is made by sealing the upper end of a stainless steel pipe, and when assembling the battery, it is shaped like a pipe. The pipe is used as an electrolyte injection port, and after the electrolyte is injected, the current collector rod 5 is inserted and the upper end of the pipe is welded to the upper end of the current collector rod 5 to seal it. 9 is an electrolytic solution containing thionyl chloride and lithium tetrachloroaluminate (L) as a supporting electrolyte.
1.2 mol/l of iAlCl4) is dissolved therein, and thionyl chloride is not only the solvent of the electrolyte but also the positive electrode active material in this battery. 10 is a bottom paper, and 11 is a top paper, which, like the separator 3, are made of glass fiber nonwoven fabric.

Example 2 Acetylene black having a nitrogen adsorption surface area of 60 mT2/g and an iodine adsorption amount of 105 mg/g as in Example 1 was pulverized in a vibrating ball mill for 15 hours. Through this crushing process,
The nitrogen adsorption surface area of acetylene black increased to 140 i/g, and the iodine adsorption amount increased to 135 mg/g.

Example 1 except that acetylene black which had been pulverized to increase its surface area and increase its activity as described above was used.
In the same manner as above, a lithium-thionyl chloride type AA battery having the structure shown in FIG. 1 was prepared.

Example 3 Acetylene black having a nitrogen adsorption surface area of 60 nf/g and an iodine adsorption amount of 105 mg/H as in Example 1 was pulverized in a vibrating ball mill for 20 hours. Through this pulverization treatment, the nitrogen adsorption surface area of the acetylene blank was 180rrf/g.
The amount of iodine adsorbed increased to 155 mg/g.

Example 1 except that acetylene black which had been pulverized to increase its surface area and increase its activity as described above was used.
In the same manner as above, a lithium-thionyl chloride type AA battery having the structure shown in FIG. 1 was prepared.

Example 4 Acetylene black with a nitrogen adsorption surface area of 60 n (/g, legal adsorption of 11,105 mg/g) as in Example 1 was pulverized in a vibrating ball mill for 25 hours. Through this pulverization treatment,
The nitrogen adsorption surface area of acetylene black is 200rrf/
g, and the iodine adsorption amount increased to 170 mg/g.

Example 1 except that acetylene black which had been pulverized to increase its surface area and increase its activity as described above was used.
In the same manner as above, a lithium-thionyl chloride type AA battery having the structure shown in FIG. 1 was prepared.

Comparative Example 1 Aqueous dispersion of polytetrafluoroethylene in 100 parts by weight of a mixture of 90% by weight of acetylene black and 10% by weight of graphite having a nitrogen adsorption surface area of 60 nf/g and an iodine adsorption amount of 105 mg/g as in Example 1. 20 parts by weight of solids (solid content concentration 60% by weight), 120 parts by weight of methyl alcohol and 250 parts by weight of water were added and kneaded, and the kneaded product was molded into a cylindrical shape with a diameter of 10.6 mm using a hydraulic extruder. 33m
After cutting into pieces of m, vacuum drying was performed at 130°C for 5 hours. A lithium-thionyl chloride type AA battery having the structure shown in FIG. Created.

The batteries of Examples 1 to 4 and the battery of Comparative Example 1 obtained as described above were continuously discharged and their discharge characteristics were examined. All of the batteries of Examples 1 to 4 of the present invention exhibited flat discharge characteristics,
No voltage drop was observed during discharge. Among the batteries of Examples 1 to 4 of the present invention, the battery of Example 1 was taken as a representative, and its discharge characteristics were compared to the discharge characteristics of the battery of Comparative Example 1, which is a conventional battery. In comparison with the characteristics, the 2.5V of the batteries of Examples 1 to 4 and the battery of Comparative Example 1 at the time of discharge are shown in FIG.
Table 1 shows the discharge duration at the end.

Table 1 As shown in Table 1, the batteries of Examples 1 to 4 of the present invention all had longer discharge durations (,
The discharge capacity was large even when discharging a large current under a heavy load of 10Ω.

In addition, as shown in FIG. 2, the battery of Example 1 of the present invention does not have a voltage drop during discharge unlike the battery of Comparative Example 1, which is a conventional battery, and has a stable operating voltage. The discharge duration was also long.

Note that although a cylindrical positive electrode was used in the above embodiment, the present invention is not limited thereto, and the same effects as described above can be obtained even with a spiral positive electrode.

〔Effect of the invention〕

As explained above, in the present invention, by pulverizing acetylene black to increase its surface area, it was possible to improve the discharge characteristics in large current discharge.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of an inorganic/aqueous electrolyte battery according to the present invention, and FIG. 2 is a 10Ω discharge characteristic diagram of the battery of Example 1 of the present invention and the battery of Comparative Example 1, which is a conventional battery. It is. 2... Negative electrode, 3... Separator, 4... Carbon porous molded body, 9... Electrolyte solution Fig. 1

Claims (2)

[Claims] (1) An inorganic non-aqueous electrolyte that uses an oxyhalide that is liquid at room temperature as a positive electrode active material and as a solvent for the electrolyte, and has a carbon porous molded positive electrode that faces an alkali metal negative electrode with a separator interposed therebetween. An inorganic non-aqueous electrolyte battery, characterized in that the carbon porous molded positive electrode is formed mainly of acetylene black whose surface area has been increased by pulverization. (2) Nitrogen adsorption surface area of pulverized acetylene black is 70 mT^2/g or more, and iodine adsorption amount is 110 mg/g.
The inorganic non-aqueous electrolyte battery according to claim 1, wherein the inorganic non-aqueous electrolyte battery has an electrolyte of at least 100 g.