JPS6023954A - Nonaqueous electrolyte battery - Google Patents

Abstract

PURPOSE:To improve the safety of a nonaqueous electrolyte battery still more by using synthetic resin film with fine pores as the separator. CONSTITUTION:Synthetic resin film with fine pores is used as the separator 3. For example, polypropylene film with the thickness of 0.025mm., the Metsuke weight of 11.74g/cm<2>, and the pore diameter of approximately 0.1mu is used as the separator 3 that uses a lithium negative electrode 2, a manganese dioxide positive electrode 1, and a nonaqueous electrolyte. As a result, even if a battery is externally strapped, the battery temperature is raised by Joule heat caused by jumpering current, the fine pores of film are closed by fused substances and the transfer of ions is prevented. Consequently, since current does not flow and the battery rise is also suppressed, the safety of the battery is improved.

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a negative electrode using a light metal such as lithium or sodium as an active material, and a metal oxide, sulfide, or halide. A non-aqueous electrolyte battery comprising an IIE electrode as an active material, a separator inserted between positive and negative electrodes, and a non-aqueous electrolyte.

(b) Prior art This type of battery has attracted particular attention in recent years due to its high energy density and low self-discharge.In fact, it uses lithium as the negative electrode active material and carbon dioxide as the positive electrode active material. Batteries using mankan, fluorinated charcoal, silver chromate, etc. have been put into practical use.

In this type of battery, a polypropylene nonwoven fabric is generally used as the separation part from the viewpoint of non-aqueous electrolyte resistance.

However, as the uses of this type of battery expand, there is a need for further improvement in its safety.The inventors' experiments (=
According to this report, when a battery is short-circuited externally, the internal temperature of the battery rises due to Joule heat caused by the short-circuit current (2), and the polypropylene nonwoven fabric used as the separator part softens and melts, causing an internal short circuit in which the positive and negative electrodes come into contact with each other. As a result, the internal temperature of the battery further rose and gas was generated due to the decomposition of the electrolyte, creating a risk of fire or explosion of the battery.

OBJECTS OF THE INVENTION (1) It is an object of the present invention to further enhance the safety of non-aqueous electrolyte batteries by using an improved separator member.

B) Structure of the Invention The present invention has achieved the above-mentioned object. The device is equipped with a positive electrode containing sulfur-1 arsenic or halogen-1 arsenic as an active material, a separator A inserted between the positive and negative phases, and a non-aqueous electrolyte. B) A non-aqueous electrolyte battery characterized by using a synthetic resin film 2.

Typical examples of synthetic 4ffl resin films having micropores include polypropylene films and polyethylene films.

Kui) Example Examples of the present invention will be described below.

Example 1 The positive electrode consisted of manganese dioxide as an active material, acetylene black as a conductive agent, and fluororesin as a binder.
A mixture mixed at a weight ratio of 5:10:5 was applied to a current collecting grid and heat-treated.

The negative electrode is a rolled lithium plate punched out at a specified monthly rate, and the electrolyte is lithium perchlorate dissolved in a mixed solvent of propylene carbonate and dimethyl ethylene glycol ether. Using.

As a separator member, a polypropylene film (manufactured by Polyplastig Co., Ltd., trade name: Duraguard) having a thickness of 0.025 sa, a basis weight of mfm of 11.74 g/i, and a pore diameter of about 0.1 μm was used.

Fig. 1 shows a vertical cross-sectional view of the battery. When assembling the battery, the spiral electrode body, which is formed by winding the positive and negative electrodes (1) and (2) through the separator (3), is attached to the battery container (4) which also serves as the positive terminal. ), and then insert the negative electrode lead plate (2), which can be exposed from the lithium negative electrode (2) into the battery container (4
) opening (2) After installing the battery container (4), open the opening edge (
Tighten to the 4F insulation bassogging (6) to obtain complete oil resistance. Note that (71(8) is an insulator 777 arranged on the upper and lower surfaces of the spiral electrode body.The battery dimensions were approximately 55 wa in height and approximately 2 Jm in diameter. A) and T.

Example 2 As a separator member, thickness 0.040 fin, basis weight type IIT
8-45 g/wt, pore size approximately 0.6-0. A battery was prepared in the same manner as in Example 1, except that a '7 p noboriethelene film (manufactured by Asahi Kasei Co., Ltd., trade name: Hibore) was used. This electric i'l! Let J ”x fBl.

As a comparative example separator member, 0.120, m, point E, j' x M 40. A battery was prepared in the same manner as in Example 1, except that a polypropylene nonwoven fabric (manufactured by Toto Oil Co., Ltd.) was used.

Let this battery be [01].

FIG. 2 and FIG. 6 compare the short circuit test characteristics of each of the above batteries.

First, Fig. 2 shows two batteries fAl[Bl and (C1) each connected in series and kept at a constant temperature of 25°C for a long time. Figure 2 (A) shows the relationship between the current A11 and the measurement time. Figure 2 to+ shows the relationship between battery container temperature and measurement time.The curves in Figure 2 are based on the values of the battery with the higher current value and discharge of two identical batteries. be.

The following can be seen from 1 in this second case.

In other words, the battery of the present invention) (In B1, the current value decreased rapidly about 5 minutes after the short circuit2.)QJp;'J0'
) The temperature of the battery container is approximately 105°C when the battery is Al, and approximately 90°C when the battery is fBl. Thereafter, as time passes, the current value hardly increases and the battery container temperature decreases.

At the point f (approximately 5 minutes after the short circuit for the two-pair battery to+), the double current value once decreases, and the double current value immediately increases, so the battery container temperature continues to rise. After about 7 minutes, the battery's internal pressure rose and the lid flew off, making further training impossible.

Let's consider the reason for this (2. In batteries (A, l (in the case of Bl)), a synthetic resin film with micropores used as a separator member at °C will cause a short circuit current (2). When the melting point of each film material (2Al'J-) is reached, the holes for micro-X are blocked by the melt, and the movement of ions is blocked.In other words, the separator member is not only electrically insulated but also Since it becomes an insulator that also blocks the movement of ions, current no longer flows.

As a result, the battery temperature does not rise any further and inconveniences such as ignition and explosion are suppressed (Second).

On the other hand, in battery (0) using polypropylene nonwoven fabric 7 as a separator member, when the oil temperature rises, the amount of ion transfer decreases because the polypropylene nonwoven fabric shrinks slightly by 14y. Either the current value decreases, or fundamentally the polypropylene nonwoven fabric has larger pores than Film C, so it is impossible to stop the movement of ions, and the current value increases again and the battery temperature increases accordingly. As the temperature rises, the polypropylene nonwoven fabric itself softens and melts, causing a short circuit within the battery (1).

The synthetic resin film having micropores is not limited to the polypropylene film and polyethylene film mentioned in the examples, and for example, a copolymer filter of polypropylene and polyethylene can also be used.

Next (-1) Even if a synthetic resin film is used as a separator member, there are some differences depending on the material of the film (2).

Figure 6 shows two batteries (Al and (Ell) connected in series f.
Characteristics measured by short-circuiting each group of batteries, which are connected in series (two batteries each), after being acclimatized and held in a constant temperature oven at 70℃ (-). Figure 3 (a) shows the relationship between the current value and the 11th regular intercostal space, and Figure 6 (b) shows the relationship between the battery container temperature and the opening during measurement. The curve adopts the value of the battery with higher current value and temperature among two identical batteries.

As is clear from α53 tg (-polyethylene film Z battery used as separator assembly + Bl or battery using polypropylene film as separator member?
Compared to +AI, as shown in Figure 3 (a), the current value hardly increases after being drastically reduced, and as shown in Figure 3 (b), the maximum battery temperature is lower and the characteristic C1 is superior. I understand that.

The reason for this is thought to be C1 as follows. In other words, when we dismantled the short-circuit test characteristics, the polyethylene film was still film-like! However, the polypropylene film had a slight impact (2); It is presumed that ions move and current flows.Also, since polyethylene has a lower melting point, the rise in battery temperature can be suppressed.

In this way, when comparing niboribrobylene film and polyethylene film, it can be said that polyethylene film is superior.

(f) Effects of the Invention As mentioned above, according to the non-aqueous electrolyte battery according to the present invention (second aspect), a synthetic resin film having micropores is used as a separator member, so even if an external short circuit is caused, Joule heat due to the short circuit current is generated. When the battery temperature rises, the fine pores of the film are blocked by the molten material, preventing the movement of ions, which prevents current from flowing. It can be completely improved and its industrial value is extremely large.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a battery of the present invention according to Example C2, and FIG.
6 and 6 show the short-circuit test characteristics of the battery of the present invention, respectively (a) shows the relationship between current value and measurement time, and (x) shows the relationship between battery container temperature and measurement time. (1)... Positive electrode, (2)... Negative electrode, (3)... Fine pores! A separator made of a synthetic resin film with (
4)...Battery container, (5)...Sealing lid, (6)...
- Insulating packing, (7) (8) - Insulating wire, prisoner + Bl -, one invention battery, (C1... comparison battery. -278- Between the stop and :ti (ltT)

Claims (1)

[Claims] ■ A negative electrode whose active material is a light metal such as lithium or sodium, a king whose active material is an oxide, sulfide, or halide of group 9, and a fill material between the positive and negative electrodes. 5. A non-aqueous electrolyte battery comprising a separator and a non-aqueous electrolyte, wherein a synthetic resin film having micropores is used as the separator. (2) The non-aqueous electrolyte battery according to claim 0, wherein the synthetic resin film is a polypropylene film. (2) The non-aqueous electrolyte battery according to claim 0, wherein the synthetic resin film is a polyethylene film.