JP2948277B2 - How to make a lithium battery - Google Patents

Description

The present invention relates to a method for producing a lithium battery.

[Conventional technology and its problems]

 FIG. 5 shows a general structure of a lithium battery.

A lithium negative electrode (44) and a positive electrode (43) mainly composed of manganese dioxide are stacked via an electrolytic layer (45), and a negative electrode terminal plate (42) made of stainless steel or the like and a positive electrode terminal plate (41) Are further stacked, and the outer peripheral portion is sealed with a sealing material (46). As the electrolytic layer (45), a nonwoven fabric made of a polymer impregnated with a non-aqueous electrolyte is used.

Conventionally, as the lithium negative electrode (44), a rolled lithium plate obtained by further pressing a rolled lithium plate on stainless steel to be the negative electrode terminal plate (42) has been used. The positive electrode (43) mainly composed of manganese dioxide has a particle size of about 1 to 2 μm.
manganese dioxide powder and graphite powder mixed with a binder,
After kneading, a material coated or pressed on a stainless steel serving as a positive electrode terminal plate (41) has been used.

However, since the conventional lithium anode (44) is produced by rolling as described above, the surface contributing to the reaction is only the surface of the rolled plate, and the ratio of the lithium surface area to the lithium weight (specific surface area) does not increase so much. . When the specific surface area contributing to the reaction is so small, a large current cannot be obtained from the battery.

On the other hand, when the positive electrode (43) is manufactured, a binder is required to use the coating method or the pressure molding method as described above, but since the binder is contained, the active material is used. Manganese dioxide cannot be increased in density, and therefore the discharge capacity of the battery cannot be increased. The graphite powder or the like added to the positive electrode (43) is used to enhance the conductivity, but it is difficult to uniformly disperse the graphite powder into the manganese dioxide powder by kneading.

Furthermore, it is difficult to form a thin film having a thickness of 0.3 mm or less uniformly by the above-described conventional method for both the negative electrode (44) and the positive electrode (43). There was a problem.

[Problems to be solved by the invention]

The present invention has been made in view of the above problems, and has as its object to provide a method for manufacturing a lithium battery which is ultra-thin, can extract a large current, and has a high discharge capacity.

[Means for solving the problem]

The above object is to dispose a negative electrode having a lithium thin film formed on a substrate and a positive electrode having a thin film mainly composed of manganese dioxide formed on another substrate opposed to each other with an electrolytic layer interposed therebetween. In the method for producing a lithium battery that seals the periphery of the lithium battery, the lithium thin film and the manganese dioxide-based thin film are formed on the substrate by a pressure difference with ultrafine lithium particles or ultrafine particles mainly containing manganese dioxide, respectively, together with a gas. Or a method for manufacturing a lithium battery, which is formed by spraying on the other substrate.

[Action]

In the lithium battery fabrication method described above, both the negative electrode and the positive electrode are formed as ultrafine particle compact films by spraying the ultrafine particles, which are active materials, uniformly on a substrate in an aerosol state. Therefore, the formed film has a thickness of 0.3 mm or less, and has a high density and uniform composition. In addition, since it is an ultrafine-particle green compact, its non-surface area becomes very large. Therefore, it is possible to obtain a lithium battery which is ultra-thin, can take out a large current and has a high discharge capacity.

〔Example〕

 Next, examples will be described with reference to the drawings.

First, in the first embodiment, the lithium anode (4
A method of forming a negative electrode corresponding to 4) will be described with reference to the schematic diagram of the lithium thin film forming apparatus shown in FIG.

In FIG. 1, the crucible (2) provided inside the ultrafine particle generation chamber ( 1 ) is configured to be heated by resistance heating. The ultrafine particle generation chamber ( 1 ) is provided with a gas introduction pipe (3) for introducing a gas (15) through a valve (4). The film forming chamber ( 6 ) is provided with an exhaust pipe (10) connected to a vacuum exhaust system (not shown) through a valve (9).

The ultrafine particle generation chamber ( 1 ) and the film formation chamber ( 6 ) are connected via a valve (11) by a transfer pipe (5), and a tip of the transfer pipe (5) has a width of 100 mm and a slit width of 200 μm ( 7). A stage (8) movable in the horizontal direction by a moving mechanism (not shown) is disposed in the film forming chamber ( 6 ) so as to face the nozzle (7). (12) and (13) are pressure gauges, respectively.

In the apparatus configured as described above, the crucible (2)
Lithium (Li) (16) was put therein, and a stainless plate (14) serving as a negative electrode terminal plate (42) (see FIG. 5) was disposed as a substrate on the stage (8).

First, the inside of the ultrafine particle generation chamber ( 1 ) and the inside of the film formation chamber ( 6 ) were once evacuated to 1 × 10 ⁻⁶ Torr while the valve (11) was opened to exhaust air from the exhaust pipe (10). After that, the valve (4) is opened and the helium gas (1
5) is introduced, and the pressure inside the ultrafine particle generation chamber ( 1 ) is increased to 9 kg / c.
and m ^2, and then holding film forming chamber the pressure in the (6) to 1 × 10 ^-2 Torr by adjusting the valve (9) for exhaust at the same time.

The crucible (2) was heated to evaporate and condense lithium (16) to generate ultrafine lithium particles (17). The generated ultrafine particles (17) were sprayed from the nozzle (7) onto the stainless steel plate (14) placed on the stage (8) through the transfer pipe (5) by a pressure difference at the same time as the generation, forming a film. .
At this time, the stage (8) was moved at a constant speed at right angles to the width direction of the nozzle (7) to form a 100 mm square lithium ultrafine particle compact film (18). The thickness was 30 μm.

Next, a method of forming a positive electrode corresponding to the positive electrode (43) mainly containing manganese dioxide in FIG. 5 will be described with reference to a schematic diagram of a thin film forming apparatus shown in FIG.

In FIG. 2, a cassette ( 20 ) for storing ultrafine particles, which is rotated by a motor (21), is provided inside an aerosolization chamber ( 19 ), and a gas (24) is introduced through a valve (22). A gas introduction pipe (23) for opening the cassette (20) is opened near the bottom of the cassette (20). On the other hand, the film forming chamber ( 25 ) is provided with an exhaust pipe (27) connected to a vacuum exhaust system (not shown) through a valve (26). The aerosolization chamber ( 19 ) and the film formation chamber ( 25 ) are connected by a transfer pipe (29) via a valve (28). The tip of the transfer pipe (29) has a width of 100 mm and a slit width of 200 μm (30). It is connected to the. A stage (31) movable in a horizontal direction by a moving mechanism (not shown) is disposed in the film forming chamber ( 25 ) so as to face the nozzle (30). (32) and (33) are pressure gauges.

In the apparatus configured as described above, ultra-fine particles of manganese dioxide (average particle diameter: 200 mm) 85 w
t% and 15 wt% of graphite ultra-fine particles (average particle size 100 mm) were dry-mixed by a vibrating mill (35) and placed in the cassette (20) of the aerosolization chamber ( 19 ), and the film was formed in the film formation chamber ( 25 ). A stainless steel plate (3) as a positive electrode terminal plate corresponding to the positive electrode terminal plate (41) of the conventional example (FIG. 5) is placed on the stage (31).
4) was arranged as a substrate.

First, the gas was exhausted from the exhaust pipe (27) with the valve (28) opened, and the inside of the aerosolization chamber ( 19 ) and the film formation chamber ( 25 ) was once exhausted to 1 × 10 ^-6 Torr. Then, while rotating the cassette (20) by the motor (21), the valve (22) is opened, and the helium gas (2
4) was introduced and blown into the bottom of the cassette (20). At the same time, the pressure in the aerosolization chamber ( 19 ) is adjusted to 9 kg / cm ² by adjusting the exhaust valve (26), and the film formation chamber ( 25 )
The internal pressure was 1 × 10 ^-2 Torr. Rotating cassette (2
The mixed ultrafine particles (35) mainly composed of manganese dioxide are uniformly dispersed in the helium gas (24) by the helium gas (24) injected into the bottom of (0).
Then, the film was sprayed from the nozzle (30) onto the stainless steel plate (34) placed on the stage (31) through the transfer pipe (29) due to the pressure difference, thereby forming a film. At this time, as in the case of FIG. 1, the stage (31) is moved at a constant speed with the nozzle (30).
Was moved at right angles to the width direction to form a 100 mm-square ultrafine particulate compact film (37) mainly composed of manganese dioxide. The thickness was 30 μm.

The negative electrode and the positive electrode manufactured as described above were cut into 10 mm squares together with the stainless steel plates (14) and (34), and 1 mol of lithium perchlorate was used as an electrolytic layer corresponding to the electrolytic layer (45) in FIG. Using a non-woven polypropylene fabric impregnated with a propylene carbonate electrolyte dissolved at a concentration of /, a lithium compact green film (18) for the negative electrode and a green compact film mainly composed of manganese dioxide for the positive electrode ( 37) were placed facing each other, and the peripheral opening was sealed with resin to produce a battery. The battery is about 10mm square, 0.3mm thick and very thin.

Regarding the lithium battery (A) manufactured according to the present example and the lithium battery (B) manufactured according to the conventional method,
FIG. 3 shows a diagram comparing and examining the discharge characteristics paying attention to manganese dioxide. As is clear from FIG. 3, the lithium battery (A) of the present example has a larger discharge capacity per unit weight of manganese dioxide as the positive electrode active material than the conventional battery (B).

That is, assuming that the discharge voltage practically used in the figure is 2.4 V, the corresponding discharge capacity of (A) is 270 mAh / g. Since the amount of manganese dioxide formed as a thin film on the 100 mm square positive electrode obtained in this example is 1.2 g, the discharge capacity is 324 mAh as a whole and 648 hours (27 days) at a current of 0.5 mA.
During this time, the discharge current can be continuously taken out.

Further, with respect to lithium, the lithium amount was 1.4 mg and the discharge capacity was 5.3 mAh for a 10 mm square and 30 μm thickness. This corresponds to 98% of the theoretical value, and the discharge efficiency is very good. 0.
A discharge current can be continuously taken out at a current of 5 mA for 10.6 hours.

 Next, a second embodiment will be described.

In this embodiment, the formation of the lithium negative electrode was performed by the same method as in the first embodiment, and the formation of the positive electrode mainly composed of manganese dioxide was performed by a thin film forming apparatus schematically shown in FIG.

In the apparatus of FIG. 4, two aerosolization chambers ( 19
a ) ( 19b ) is provided. Inside them, cassettes (20a) (20b) rotated by motors (21a) (21b) are provided, respectively, and valves (22a) (22
b) Gas introduction pipe (2) for introducing gas (24) through
3a) and (23b) open near the bottom of the cassettes (20a) and (20b). The aerosolization chambers ( 19a ) and ( 19b ) are connected to the aerosol mixer (38) by the transfer pipes (29a) and (29b), and further connected to the film formation chamber ( 25 ) by the transfer pipe (29). (33a) and (33b) are pressure gauges.

Other configurations are the same as those in FIG. 2, and thus the same reference numerals are given and the description is omitted.

In the apparatus configured as described above, manganese dioxide ultra-fine particles (average particle size 200 mm) previously manufactured (3
5a) One cassette of aerosolization chamber ( 19a ) (20a)
, And similarly ultrafine graphite particles (average particle size 100 mm) (35b)
Was placed in the cassette (20b) of the other aerosolization chamber ( 19b ). Further, a stainless plate (34) was disposed as a substrate on the stage (31) in the film forming chamber ( 25 ).

First, the air is exhausted from the exhaust pipe (27) with the valve (28) open, and the aerosolization chambers ( 19a ) ( 19b ) and the film formation chamber ( 2 ) are exhausted.
The inside of 5 ) was once evacuated to 1 × 10 ⁻⁶ Torr. afterwards,
The cassette (20) is driven by the motor (21a) (21b)
a) Open the valves (22a) and (22b) while rotating the (20b), and open the helium gas (24) through the gas inlet pipes (23a) and (23b).
And blown into the bottom of the cassette (20a) (20b). The pressure in each aerosolization chamber ( 19a ) ( 19b ) is adjusted to 9 kg / cm ² by adjusting the helium gas introduction amount with the valves (22a) and (22b) and simultaneously adjusting the exhaust valve (26). The pressure in the film forming chamber ( 25 ) was set to 1 × 10 ^-2 Torr.

The cassette (2) rotating in the aerosolization chamber ( 19a )
0a) helium gas (24) blown into the bottom of the manganese dioxide ultra-fine particles (35a) helium gas (2
The aerosol (36a) uniformly dispersed in 4) is generated, and is transported to the mixer (38) via the transport pipe (29a) by a pressure difference.

Similarly, in the aerosolization chamber ( 19b ), an aerosol (36a) of graphite ultrafine particles (35b) is generated and transported to the mixer (38) via the transport pipe (29b) by a pressure difference. Both aerosols (36a) (36b) in the mixer (38)
Was uniformly mixed, but the proportion was adjusted by the conductance of the conveying pipes (29a) and (29b) to obtain an aerosol (36) mainly composed of manganese dioxide of 85% by weight of manganese dioxide and 15% by weight of graphite. The aerosol (36) was ejected from the nozzle (30) via a transfer pipe (29) onto a stainless steel plate (34) placed on a stage (31).

At this time, the stage (31) is moved in the same manner as in the first embodiment to form the same ultrafine particulate compact film (37) having a film pressure of 30 μm mainly composed of manganese dioxide of 100 mm square as in the first embodiment. did.

Using the positive electrode and the negative electrode manufactured as described above, a first
When a battery was manufactured in the same manner as in the example, good characteristics similar to those of the first example were obtained.

As described above, each embodiment of the present invention has been described.
The present invention is not limited to these, and various modifications are possible based on the technical idea of the present invention.

For example, in each of the embodiments, the lithium compacted film (18) and the compacted film mainly composed of manganese dioxide (37) were separately manufactured to produce a battery. May be formed on the electrolytic layer while forming the battery, and the process can be simplified.

That is, two transport pipes (5) and (29) are connected to one film formation chamber ( 6 ), and lithium is placed on a plurality of stainless steel plates (14) and (34) by switching valves (11) and (28). The film (18) and the film (37) mainly composed of manganese dioxide may be formed alternately. In this case, the same gas (15) to be introduced into the ultrafine particle generation chamber ( 1 ) and the same gas (24) to be introduced into the aerosolization chamber ( 19 ) are used. Then, a battery manufacturing chamber is preferably provided following the film forming chamber ( 6 ).

In such a continuous process, the oxidation of lithium is particularly prevented because the film formation chamber ( 6 ) is completely shut off from the outside air. Oxidation is also prevented, and a good battery is obtained.

In the second embodiment, a manganese dioxide aerosol (36a) and a graphite aerosol (36b) are mixed in a mixer (38).
The aerosol (36) mixed in the above was sprayed onto a stainless steel plate (34) to obtain a green compact film (37) mainly composed of manganese dioxide, but instead the aerosols (36a) and (36b) were not mixed. Alternatively, they may be separately transported to the film forming chamber ( 25 ), and sprayed simultaneously from different nozzles onto the stainless steel plate (34).

〔The invention's effect〕

According to the method for manufacturing a lithium battery according to the present invention, both the negative electrode and the positive electrode are formed as very uniform and high-density ultrafine particle compact films having a thickness of 0.3 mm or less. Also, oxidation of lithium on the negative electrode is prevented.

Therefore, it is possible to obtain a lithium battery that is ultra-thin, can take out a large current, and has a high discharge capacity.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an apparatus for forming a lithium thin film according to a first embodiment of the present invention, FIG. 2 is a schematic view showing an apparatus for forming a thin film mainly containing manganese dioxide, and FIG. FIG. 4 is a graph comparing the discharge characteristics of the lithium batteries obtained by the first embodiment and the conventional method, FIG. 4 is a schematic diagram showing an apparatus for forming a thin film mainly composed of manganese dioxide of the second embodiment, and FIG. FIG. 1 is a schematic sectional view showing a general configuration of a battery. In the figure, (14) (34) ... stainless steel plate (15) (24) ... gas (17) ... lithium ultrafine particles (18) ... lithium compacted film (35) ... mainly manganese dioxide Ultrafine particles (35a): Ultrafine manganese dioxide particles (35b): Ultrafine graphite particles (36): Aerosol mainly composed of manganese dioxide (36a): Aerosol of manganese dioxide (36b): Aerosol of graphite (37)… Green compacted film mainly composed of manganese dioxide (38)… Mixer (43)… Positive electrode (44)… Negative electrode (45)… Electrolytic layer

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01M 4/08 H01M 4/12 C23C 14/24 C23C 14/08 C23C 14/14-14/18

Claims (5)

(57) [Claims] A negative electrode having a lithium thin film formed on a substrate;
A positive electrode, on which a thin film mainly composed of manganese dioxide is formed on another substrate, is disposed to face through an electrolytic layer, and the method for manufacturing a lithium battery that seals around the negative electrode and the positive electrode includes the lithium thin film and the lithium thin film. The manganese dioxide-based thin film is formed by injecting ultrafine particles of lithium or ultrafine particles mainly containing manganese dioxide onto the substrate or the other substrate by a pressure difference together with a gas. A method for producing a lithium battery. 2. The lithium thin film is formed by injecting lithium ultrafine particles generated in a high-pressure first gas atmosphere together with the first gas onto the substrate provided in a low-pressure atmosphere. The method for producing a lithium battery according to claim 1. 3. The thin film mainly composed of manganese dioxide is obtained by disposing an aerosol obtained by uniformly dispersing ultrafine particles mainly composed of manganese dioxide in a high-pressure second gas in another atmosphere provided in a low-pressure atmosphere. The method for producing a lithium battery according to claim 1, wherein the lithium battery is formed by spraying on a substrate. 4. The lithium battery according to claim 3, wherein the aerosol is produced by blowing the high-pressure second gas near the bottom of a rotary tank containing the ultrafine particles mainly composed of manganese dioxide. Method of manufacturing. 5. The first aerosol produced by blowing the high-pressure second gas into the vicinity of the bottom of the first rotary tank containing the ultrafine particles of manganese dioxide, and the other ultrafine particles. The method for producing a lithium battery according to claim 3, wherein the second aerosol is produced by blowing the high-pressure second gas into the vicinity of the bottom of the second rotary tank containing the gas.