JP2874529B2 - Lithium battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium battery.

[0002]

2. Description of the Related Art A conventional lithium battery is composed of a positive electrode plate in which a positive electrode active material obtained by mixing acetylene black or the like as a conductive agent with manganese dioxide is bonded to a current collector, and a negative electrode plate mainly composed of lithium metal. They are laminated via a microporous film as a separator.

[0003] In such a lithium battery, when an internal short circuit occurs, the micropores of the separator are closed by the rise in temperature, and an increase in short circuit current can be suppressed.

[0004]

In the above-mentioned conventional lithium battery, there is a problem that since the strength of the separator is small, the separator is damaged at the time of manufacturing and an internal short circuit is likely to occur.

Further, in the above-mentioned conventional lithium battery,
Since the capacity of the separator for holding the electrolytic solution is small, there is a problem that the discharge capacity is reduced in a sealed battery in which the amount of the electrolytic solution is limited.

[0006]

In order to solve the above-mentioned problems, the present invention provides a method in which a positive electrode plate surrounded by a separator composed of a microporous membrane is surrounded by a separator composed of a nonwoven fabric, and is surrounded by these two layers of separators. The positive electrode plate and the negative electrode plate mainly composed of lithium are alternately laminated.

[0007]

According to the present invention, the electrolyte can be held by the non-woven fabric separator, and the increase in short-circuit current can be suppressed by the microporous membrane separator.

Further, in the present invention, since the positive electrode plate having a high internal resistance is surrounded by the separator made of the microporous film, the temperature of the positive electrode plate rapidly rises when an internal short circuit occurs. Are closed, and the rise in battery temperature can be reduced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.

FIG. 1 is a sectional view of a lithium battery according to the present invention.

In FIG. 1, reference numeral 1 denotes a positive electrode plate in which a positive electrode active material in which acetylene black is mixed with manganese dioxide is pressed against a current collector, 2 denotes a negative electrode plate made of a metal lithium sheet, and the positive electrode plate 1 Separator 3 consisting of porous membrane
, And the outside is surrounded by a separator 4 made of a nonwoven fabric.

Then, the positive electrode plate 1 and the negative electrode plate 2 surrounded by the two-layer separator are alternately laminated and accommodated in a stainless steel container 5 together with an electrolyte mainly composed of propylene carbonate. Become. In FIG. 1, 6 is a positive terminal and 7 is a negative terminal.

The positive electrode plate 1 is first surrounded by a separator 3 made of a microporous film and then surrounded by a separator 4 made of a nonwoven fabric. The separator 4 may be overlapped so as to be on the outside, and then the periphery may be heat-welded to form a bag, into which the positive electrode plate 1 may be inserted.

In the lithium battery having the above-described structure, when an internal short circuit occurs for some reason, the temperature of the positive electrode plate 1 having a high internal resistance first rises, thereby closing the micropores of the separator 3 made of a microporous film. As a result, a rise in battery temperature can be suppressed.

In the lithium battery having the above structure,
Since the electrolytic solution can be held by the nonwoven fabric, the problem that the discharge capacity is reduced does not occur even in a sealed battery in which the amount of the electrolytic solution is limited.

Next, 50 batteries each of the above-mentioned battery of the present invention and a conventional battery provided with only the microporous membrane as a separator were manufactured, and the surface temperature was compared for each of 25 batteries by short-circuiting the terminals. The maximum temperature of the battery of the present invention was 80 ° C to 85 ° C, whereas the maximum temperature of the conventional battery was 85 ° C to 90 ° C.

The capacity of each of the above-mentioned batteries was 10 AH. The remaining 25 batteries were discharged at a discharge current of 10 mA and their discharge capacities were compared. It was found that the discharge capacity increased by 20%.

[0018]

As described above, the battery of the present invention can reduce the rise in battery temperature when an internal short circuit occurs, and prolong the discharge time by holding the electrolyte in a non-woven fabric separator. Therefore, the performance of the battery can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a lithium battery of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Negative electrode plate 3 Separator consisting of a microporous membrane 4 Separator consisting of a nonwoven fabric 5 Battery case

Claims (1)

(57) [Claims] 1. A positive electrode plate surrounded by a separator composed of a microporous membrane is surrounded by a separator composed of a nonwoven fabric, and the positive electrode plate surrounded by the two-layer separator and a negative electrode plate mainly composed of lithium are alternately laminated. A lithium battery characterized in that: