JPS5987771A - Nonaqueous solvent battery - Google Patents

Abstract

PURPOSE:To prevent voltage drop in an initial stage of high rate discharge by electrically connecting a higher resistance compared with a conventional discharge load resistance between a negative electrode and a positive electrode. CONSTITUTION:A negative electrode 2 such as lithium is press-bonded on the inner surface of a can 1 and a positive electrode obtained by press-bonding a porous carbon layer 4 on the outer side of a metal current collector 3 is arranged inside the negative electrode 2 with a separator 6 interposed. Electrolyte prepared by dissolving LiAlCl4 in SOCl2 is poured in the can to form a nonaqueous solvent battery. The negative electrode and positive electrode are electrically connected through a resistance 13 having high resistance value to flow extremely small amount of current. Thereby, LiCl film formed on the surface of the negative electrode 2 during storage is kept thin. Therefore, the LiCl film on the surface of the negative electrode is immediately broken in high rate discharge, and voltage drop is prevented and desired voltage is obtained from an initial stage of discharge.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to improvements in non-aqueous solvent batteries.

[Technical background of the invention and its problems]

Nonaqueous solvent batteries that use lithium and sodium as negative electrode active materials have high energy density, excellent storage characteristics, and a wide operating temperature range.
Memory is often used as a backup power source. Such batteries are composed of a negative electrode, an electrolyte, and a positive electrode. Generally, lithium or sodium is used as the negative electrode, and lithium perchlorate A is used as the electrolyte in a nonaqueous solvent such as propylene cardenate, r-butyrolactone, or seamethoxyethane. A solution made by dissolving an electrolyte such as lithium fluoride,
Manganese dioxide and graphite fluoride are used as positive electrodes, respectively.

Among the above-mentioned batteries, so-called lithium-thionyl chloride batteries, in which lithium is used as the negative electrode and thionyl chloride 5OC62 is used as the main positive electrode active material, are attracting attention because of their particularly high energy density. These batteries have positive electrodes consisting of carbon and metal current collectors and are typically lithium chloride (LiCt).
) and 5O in which aluminum chloride (AlCl2) was dissolved
Ct2 is used as the electrolyte. For this reason, 5OC4
No. 2 serves as both a positive electrode active material and an electrolyte, and by using a positive electrode with an appropriate shape, a battery with excellent high rate discharge characteristics can be expected.

By the way, in the lithium-thionyl chloride-based battery, since 5OC42, which is the positive electrode active material, is in direct contact with the negative electrode lithium, a LICT film, which is the main reaction product, is generated on the surface of the negative electrode lithium. This generated LICT film has the function of preventing direct contact between the negative electrode lithium and 5oct2, and plays the role of preventing battery capacity deterioration during storage)J
';' During discharge, it acts as a resistance component and causes a voltage drop at the beginning of discharge. The degree of this voltage drop is negligible when the discharge current is minute on the order of phycloamperes, but it can be ignored in the case of large current discharge, especially when stored at high temperatures for a long time, the LiCt film grows. However, when discharging occurs at low temperatures or after the discharge has started, there is a drawback that a large voltage drop occurs at the start of discharging, and it takes a long time for the voltage to recover to a predetermined level.

[Purpose of the invention]

The present invention aims to provide a nonaqueous solvent battery that does not cause a voltage drop even during the initial stage of large current discharge.

[Summary of the invention]

In the present invention, a negative electrode such as lithium and a positive electrode mainly composed of porous carbon are provided in a can via a separator, and thionyl chloride (socz), which also serves as a positive electrode active material, is provided in the can.
In a battery containing an electrolyte containing 2) as the main component, by electrically connecting the negative electrode and the positive electrode with a resistor having a higher resistance value than a normal discharge load resistance, a The main idea is to constantly flow a small current to prevent the large growth of LiCt film on the negative electrode lithium surface, and to facilitate the destruction of the LiCt film during large current discharge to prevent a significant voltage drop. shall be. In addition, in the battery structure of the present invention, since the battery is in a state where the battery is discharging through the resistor, the resistor has a sufficiently large resistance value so that only the minimum current necessary to reach the target I] flows. This is very important.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIG.

1 in the figure is a stainless steel 1 whose top surface is open and which also serves as a chair guard.
A cylindrical f1 electrode 2 made of metallic lithium is crimped on the inner surface of the can body 1 made of steel. A positive electrode 5 having a structure in which a cylindrical porous carbon layer 4 is crimped onto the outside of a fully bent current collector 3 made of a mesh made of stainless steel is provided via a cage-shaped gloss layer 6 made of a glass fiber non-woven fabric. For the positive electrode 5, for example, a commercially available 7' cetylene blank and polytetrafluoroethylene are mixed, and this mixture is placed on the current collector 3 and 41 made of a stainless steel net.
The porous carbon layer 4 is produced by forming the kneaded material into a cylindrical shape so that the inner side faces the inside, and then drying it under vacuum at 150°C.

Further, a metal top 7 is sealed to the upper opening of the can body 1 by laser welding or the like, and a positive electrode terminal 9 is attached to a hole 8 at the center of the metal top 7 using a sealing material made of glass.
□ is electrically insulated and fixed via 10. The lower end of the positive electrode terminal 9 is connected to the gold-end electric body 3 of the positive electrode 5 via a lead wire 11. Furthermore, L injected into the can body 1 from the injection port 12 of the metal top 7 is
A 5oct2 solution (electrolytic solution) in which iAtCt4 is dissolved by, for example, 1 molar amount is stored. 1=-1 inlet 12
After the electrolyte is injected, it is pierced by Rede welding or the like. The metal top 7 and the positive 4't terminal 9, which are wound around the front negative A small terminal, are arranged in the can body 1, (
For example, they are electrically connected by a resistor 13 of IMΩ.

In the nonaqueous solvent battery of the present invention, the negative electrode 2 and the positive electrode 5 are connected to each other via the resistor 13, so that a small current constantly flows. As a result, during long-term storage, etc., thick LiC due to contact of 5OCt2 on the two sides of the lithium negative electrode
The growth of the T film can be prevented by passing the minute current.

Therefore, during long-term storage, the lithium negative electrode 2
Since the LiCt film on the surface is maintained in a thin state, the LiC6 film on the surface of the lithium negative electrode 2 is immediately destroyed during large current discharge, preventing a significant voltage drop from occurring.
As a result, a predetermined voltage can be obtained from the initial stage of large current discharge.

In fact, the R14 type lithium-thionyl chloride battery of the previous example and the conventional one having the same configuration as the five examples except that no resistor was used)
Regarding the T14 type lithium-thionyl chloride battery, it was stored at 60℃ for 10 days after fabrication, and then subjected to 300 constant resistance discharge at 25℃.The voltage at the initial stage of discharge was investigated.
The characteristic diagram shown in the figure was obtained. Note that A in FIG. 2 is a discharge characteristic line for the battery of this embodiment, and B is a discharge characteristic line for a conventional battery. As is clear from FIG. 2, the battery of the present invention has almost no initial voltage drop compared to the conventional iT1 battery.

In the above embodiment, a cylindrical structure in which a porous carbon layer was bonded to the outside of a metal current collector was used as the positive electrode, but the present invention is not limited to this. For example, a porous carbon layer is pressure-bonded to a metal current collector to form a band, and this can be similarly applied by winding the band in a spiral to form a positive electrode. The metal current collector used here is not limited to a net shape, and may be an expanded metal or a nine sided metal.

In the above embodiment, the positive and negative electrodes were connected while the resistor was placed inside the can, but the positive and negative electrodes may be connected while being placed on the can (on the metal top). The resistance value of the resistor used here is as in the above example < (i MOyf
- It may be selected appropriately depending on the type and capacity of the battery (not limited to cases where the battery is used).

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to prevent a voltage drop even in the initial stage of large current discharge and provide a non-aqueous solvent battery with excellent initial discharge characteristics.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a non-aqueous solvent battery showing an embodiment of the present invention, and FIG. 2 is a diagram showing discharge characteristics at the initial stage of large current discharge in the battery of the present invention and a conventional battery. 1... Can body, 2... Negative electrode, 3... Metal current collector) 4
... Porous carbon layer, mutually... Positive electrode, 6... Separator, 7... Metal top, 9... Positive electrode terminal, 13...
...Resistor. Fig. 1 6x2 Fig. 1 Power attack time (minutes) Toshiba Battery Co., Ltd., 10-3-4, Minamishinagawa, Tokyo Parts Ward, Toshiba Battery Co., Ltd., applicant: Toshiba Battery Co., Ltd., 3-4, Minamishinagawa, Parts-ku, Tokyo No. 10

Claims (1)

[Claims] A negative electrode made of at least one of lithium, sodium, and aluminum and a positive electrode mainly composed of porous carbon are provided in the can with a separator interposed therebetween, and thionyl chloride, which also serves as a positive electrode active material, is provided in the can. In a non-aqueous solvent battery containing an electrolyte as a component, the negative electrode and the positive 4+i
1. A non-aqueous solvent battery, characterized in that the battery is electrically connected to the battery by a resistor having a higher resistance value than a normal discharge load resistance.