JPH01283770A - Manufacture of lithium cell - Google Patents

Abstract

PURPOSE:To reduce the pre-discharge time and to decrease the loss of the cell capacity so as to make it possible to obtain a high capacity lithium cell by pre-discharging the cell through a metallic lithium foil or porous lithium placed between the separator and the positive electrode mixture. CONSTITUTION:A separator 5 is inserted in an aperture sealing plate 2 press contacted with lithium, and metallic lithium 7, positive electrode mixture 3 and a positive electrode can 1 are piled up successively on the separator 5, and after sealing the cell airtightly aging and pre-discharge processes are carried out. Thereby the quantity of electricity in the pre-discharge and the time required for the discharge needed for respective cell systems (BR system, CR system) can be reduced to less than 1/10, and the simplification of the manufacture of the cell is made possible. And even when the pre-discharge treating time is reduced to 1/12 of the conventional time, a cell of stabilized open-circuit voltage and internal resistance can be obtained to minimize the capacity loss of the cell due to the pre-discharge and to increase the cell capacity.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to improvements in the manufacturing method of lithium batteries, which are organic electrolyte batteries.

BACKGROUND OF THE INVENTION A lithium battery using an organic electrolyte has a better self-discharge rate, leakage resistance, etc. than an alkaline battery, and has excellent long-term reliability.

Currently, many 3V type lithium batteries have been developed as this type of lithium battery, and there are BR type batteries and OR type batteries that use fluorinated graphite or manganese dioxide as a positive electrode active material.

Normally, the above-mentioned BR type batteries and OR type batteries are used to reduce the open circuit voltage of the battery by 1 operating voltage by performing a preliminary discharge in which a constant amount of electricity is discharged at a constant current after the battery is sealed.

The long-term reliability of such lithium batteries is ensured by stabilizing internal resistance and improving storage characteristics.

The technical effects of pre-discharging are slightly different between BR and OR batteries; without pre-discharging, BR batteries have a lower maintenance voltage performance (CaW) during intermittent high-rate discharge.
becomes worse. Further, in OR type batteries, problems occur such that the initial operating voltage during low-rate discharge is too high, causing smudges on the liquid crystal display of the equipment used, and the battery swells during high-temperature storage, resulting in an increase in internal resistance. Pre-discharge is currently an essential process for both battery types, but in the case of lithium batteries,
This method cannot be used because if it is not processed in a short time with a large current value, the battery will reverse polarity and the organic electrolyte will decompose. This has the disadvantage of causing a loss of battery capacity.

Problems to be Solved by the Invention As described above, in the conventional battery manufacturing method, there were problems in that the preliminary discharge treatment after sealing the cell required time and that the battery capacity was lost by 3 to 10%. .

Therefore, the present invention aims to solve the problems of the conventional lithium battery manufacturing method, and to provide a high capacity lithium battery manufacturing method that shortens the pre-discharge time and reduces the loss of battery capacity.

A means to solve problems The present invention relates to a negative electrode made of lithium and a positive electrode mixture.

In a method for manufacturing a lithium battery using a separator and an organic electrolyte, a metal lithium foil or a porous body is interposed between the separator and the positive electrode mixture, and the lithium battery is pre-discharged.

As the negative electrode, the positive electrode mixture and positive electrode can constituting the positive electrode body, and the organic electrolyte used in the production of the lithium battery of the present invention, those used in conventional lithium batteries can be used.

In the present invention, the lithium metal interposed between the separator and the positive electrode mixture is a foil or a porous body, and is configured to be in contact with a part or the entire surface of the positive electrode mixture.

Effect By adopting the manufacturing method described above, each battery system (BR
The amount of electricity required for pre-discharge and the time required for discharging, which were required in the conventional system and OR system, can be reduced to less than 100%, and battery manufacturing can be simplified.

Example The present invention will be explained below with reference to all the drawings.

FIG. 1 is an explanatory diagram showing the manufacturing process of the lithium battery of the present invention, in which a flat separator 6' is drawn on a component in which metallic lithium 4 is crimped and fixed to the inner bottom surface of a sealing plate 2, and
Insert it in the same skin condition (see country in Figure 1). Inject the necessary amount of electrolyte into this separator, place a lithium plate 7 punched out to a predetermined size approximately in the center of the inner bottom of the separator holding this electrolyte (see Figure 1), and place the lithium plate 7 on top of it in advance. The molded and dried positive electrode mixture 3 is placed, and finally the sealing plate is covered with the positive electrode can 1 and then sealed with a sealing mold (see FIG. 2).

After the battery is sealed, the structure shown in FIG. 2 is assumed for a while, but the positive electrode mixture 3 and the lithium plate 7 react to form an electrode battery).
Lithium is reduced to 3 tl of the positive electrode mixture.

The battery structure when this reaction is completed is shown in FIG. 3, which is apparently the same as the conventional battery structure. but.

The open-circuit voltage of the battery is 2.9 to 3.1 V, which is the same as that obtained by normal pre-discharge, and a battery with better shelf life is produced by performing a short-time pre-discharge at a constant current.

Figure 2 shows a longitudinal cross-sectional view of the lithium manganese battery of the present invention, in which 1 is a positive electrode can made of 8US430, and 2 is a 5t
The sealing plate %3 made of IS403 is a mixture of 97 parts by weight of calcined manganese dioxide powder and 3 parts by weight of Ketchen Black. Add 460XIIl of water, stir and knead and dry.
This dry mixture 0.369 is 161RM in diameter and 0.7 in thickness.
4 is a lithium negative electrode crimped and fixed to the inner surface of the sealing plate, 5 is a separator made of synthetic fiber nonwoven fabric, and 6 is a propylene gasket, which connects the cathode can 1 and the sealing plate through this gasket. 2 are pressure-welded and sealed. 7 is lithium made by punching 0.08 Jll lithium foil into a diameter of 8 m1. The maximum outer diameter of this lithium battery was 20 Jl'l, and the maximum total height was 1.6 MM.

A lithium battery having the above configuration 'i) A battery pre-discharged for 1 minute at 16 mA is referred to as 'mu'.

For comparison, 15 without using the lithium foil 7 mentioned above.
A battery that has been pre-discharged for 12 minutes in an III mode is designated as B.

The initial open circuit voltage of these lithium batteries.

Internal resistance and battery capacity were investigated. The results are shown in Table 1.

The above data in Table 1 are the average values of 60 samples each. Note that the battery capacity was calculated from the discharge results at 15Ω.

Effects of the Invention As described above, according to the present invention, a battery with stable open circuit voltage and internal resistance can be obtained even if the pre-discharge treatment time of a lithium battery is set to 1712, which is the conventional value, and the capacity loss of the battery due to pre-discharge can be minimized. As a result, it has an excellent effect of increasing battery capacity.

Although the examples have been described using a manganese lithium battery, it has been confirmed that similar effects can be obtained with a fluorinated graphite lithium battery.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the manufacturing process of a lithium battery according to the present invention, FIG. 2 is a longitudinal cross-sectional view of an embodiment of a lithium battery according to the present invention, and FIG. 3 is a final battery configuration of an embodiment of the present invention. FIG. 1...Positive electrode can, 2...Sealing plate, 3...
...Positive electrode, 4...Negative electrode, 6...Separator, 6...Gasket, 7...
lithium. Agent's name: Patent attorney Toshio Nakao and one other person: I-Kazumasa, a laborer. Figure 3

Claims (1)

[Claims] A method for manufacturing a lithium battery using a negative electrode made of lithium, a positive electrode mixture, and an organic electrolyte, in which a separator 5 is inserted into a sealing plate 2 to which lithium is crimped, and then a lithium metal 7, a positive electrode mixture 3, and a positive electrode are inserted. A method for manufacturing a lithium battery, which comprises stacking cans 1 one after the other, sealing the battery, and then aging and performing preliminary discharge.