JPH07262986A - Non-aqueous electrolyte battery and manufacture thereof - Google Patents

Abstract

PURPOSE:To stabilize the discharging performance at the time of heavy load discharge without increasing the number of part items in a coin type, bobbin type or spiral type non-aqueous electrolyte battery. CONSTITUTION:The sublimable material is added to the positive electrode active material at 1-5% in relation to the positive electrode active material, and they are mixed for granulation, and formed into a predetermined shape. Thereafter, the porous positive electrode mix 5 of 34-40% pore ratio and of 80% or more pore utilization factor is obtained by a method for heating the mixture of the positive electrode active material and the subliming material for drying to vaporize the subliming material. Furthermore, a negative electrode 7 is faced to the positive electrode mix 5 through a separator 6 to assemble a power generating element 8, and the power generating element 8 is filled with the electrolyte. The subliming material included at the time of forming is vaporized by the heating for drying, and the porous positive electrode mix 5 quickly absorbs the non-aqueous electrolyte to stably hold a large quantity of the non-aqueous electrode (0.18g or more for 1g of the positive electrode mix).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coin-shaped, bobbin-shaped or spiral-shaped non-aqueous electrolyte constructed by injecting a non-aqueous electrolyte into a power-generating element in which a positive electrode mixture and a negative electrode are opposed to each other with a separator interposed therebetween. The present invention relates to a water electrolyte battery and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, when manufacturing a positive electrode mixture for a non-aqueous electrolyte battery of this type (for example, a lithium battery), manganese dioxide is used as a main agent, graphite or carbon black is used as a conductive material, and polytetrafluorocarbon is used. A positive electrode active material using ethylene as a binder is mixed and granulated by a wet or dry method, molded into a pellet shape or a bobbin shape under a predetermined molding pressure, and vacuum dried to manufacture a positive electrode mixture.

At this time, if the molding pressure of the positive electrode mixture is too low, the strength required as the positive electrode mixture is insufficient and cracks and chips are likely to occur, which is not practical and, conversely, the molding pressure of the positive electrode mixture. When the value is too high, the porosity of the positive electrode mixture becomes insufficient and the amount of the non-aqueous electrolyte retained becomes small, so that the discharge performance becomes unstable. Therefore, the molding pressure of the positive electrode mixture is usually within the range of 3 to 4 tons.

[0004]

However, in this case, the molding density of the positive electrode mixture after vacuum drying is 2.90 to 3.05 g.
/ Cc, the porosity is 32 to 34%, and the vacancy utilization rate (that is, the ratio of the liquid absorption space in which the non-aqueous electrolyte is actually held) does not reach 80%. The retained amount of the non-aqueous electrolyte solution is less than 0.18 g per 1 g of the positive electrode mixture.
As a result, the normal discharge performance is stable, but there is a high risk that the discharge performance will become unstable during heavy load discharge such as pulse discharge.

Further, in order to avoid such a situation, by using a ring or the like for restricting the expansion of the positive electrode mixture due to discharge to the negative electrode side, the amount of the non-aqueous electrolyte retained per 1 g of the positive electrode mixture is increased. There is a method of stabilizing the discharge performance at the time of heavy load discharge even with about 0.16 g, but in this case, there is a disadvantage that the number of parts increases because it is necessary to use the ring or the like.

In view of the above circumstances, it is an object of the present invention to provide a non-aqueous electrolyte battery capable of stabilizing discharge performance during heavy load discharge without increasing the number of parts, and a method for manufacturing the same. .

[0007]

That is, in the invention of the non-aqueous electrolyte battery of the present invention, the porous positive electrode mixture (5) and the negative electrode (7) are opposed to each other via the separator (6). In the non-aqueous electrolyte battery (1) configured by injecting the non-aqueous electrolyte into the power generation element (8), the positive electrode mixture has a porosity of 34 to 40% and a porosity of 80% or more. It is configured to have a hole utilization rate. In the invention of the method for producing a non-aqueous electrolyte battery of the present invention, the sublimable substance is added to the positive electrode active material in an amount of 1 to 5% based on the positive electrode active material, and then the mixture is mixed and granulated. It is molded into a predetermined shape, and then heated and dried to vaporize the sublimable substance to prepare a porous positive electrode mixture (5), and further to the positive electrode mixture through a separator (6). Power generating element (8) with the negative electrode (7) facing each other
Is assembled and the non-aqueous electrolytic solution is injected into the power generating element. Furthermore, it decomposes into a positive electrode active material.
An evaporative substance is added to the positive electrode active material in an amount of 1 to 5%, and then the mixture is mixed and granulated to form a predetermined shape, which is then vacuum dried to obtain the decomposable and evaporative substance. A porous positive electrode mixture (5) is prepared by decomposing or evaporating, and a negative electrode (7) is made to face the positive electrode mixture through a separator (6) to assemble a power generating element (8). It is configured to inject a non-aqueous electrolyte into the power generation element.

Here, the "decomposable / evaporable substance" means an inorganic or organic substance which is decomposed or evaporated by vacuum drying.

The numbers in parentheses are for convenience of showing the corresponding elements in the drawings, and the present invention is not limited to the description in the drawings. This also applies to the “claims” and “action” columns.

[0010]

According to the present invention, the sublimable substance and the decomposable / evaporable substance contained during molding are vaporized, decomposed or evaporated by drying, and the nonaqueous electrolytic solution is used as the porous positive electrode mixture (5). It absorbs liquid rapidly and acts so that a large amount (0.18 g or more per 1 g of the positive electrode mixture) of non-aqueous electrolyte can be stably held.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing an embodiment of the non-aqueous electrolyte battery according to the present invention, and FIG. 2 is a graph showing heavy load discharge characteristics of the non-aqueous electrolyte battery.

A coin-shaped lithium battery 1 which is a non-aqueous electrolyte battery according to the present invention has a positive electrode can 2 as shown in FIG. 1, and a current collector 3 and a positive electrode are provided in the positive electrode can 2. Mixture 5,
A power generation element 8 including a separator 6 and a lithium negative electrode 7 is placed. That is, in the center of the inner surface of the positive electrode can 2, a porous positive electrode mixture 5 formed in a pellet shape is placed via the current collector 3, and on the upper side of the positive electrode mixture 5, a polypropylene nonwoven fabric is placed. A disk-shaped lithium negative electrode 7 is placed via a separator 6 made of. A negative electrode terminal 9 is placed on the upper side of the lithium negative electrode 7,
The peripheral portion of is held by the rising portion of the positive electrode can 2 via a ring-shaped gasket 10 made of polypropylene. The positive electrode mixture 5, the separator 6 and the positive electrode mixture 5
A non-aqueous electrolyte solution in which LiClO ₄ is dissolved in a mixed solution of propylene carbonate and dimethoxyethane is held in the space around the.

Here, the positive electrode mixture 5 has a porosity of 34 to 40% and a porosity utilization rate of 80% or more.
Therefore, the amount of the non-aqueous electrolyte retained is 0.1% per 1 g of the positive electrode mixture.
Since 18 g or more is secured, not only normal discharge performance but also discharge performance during heavy load discharge such as pulse discharge is stabilized.

When manufacturing the coin-shaped lithium battery 1, the positive electrode mixture 5 is first prepared. It has
A powdery camphor, a sublimable substance such as naphthalene is added to a positive electrode active material composed of manganese dioxide (main ingredient), graphite or carbon black (conductive material), and polytetrafluoroethylene (binder). The sublimable substance is added in an amount of 1 to 5% with respect to the positive electrode active material. Next, this is mixed and granulated to form a pellet, and then dried by heating.
Then, the sublimable substance is vaporized, resulting in a porosity of 34
A porous positive electrode mixture 5 having a porosity utilization rate of 80% or more is prepared at -40%.

When the porous positive electrode mixture 5 is prepared in this way, the positive electrode mixture 5 is used to assemble the coin-shaped lithium battery 1 by a known method. That is, the current collector 3 is welded to the center of the inner surface of the positive electrode can 2, and the positive electrode mixture 5 is pressure-bonded to the current collector 3. Next, the separator 6 is placed on the upper side of the positive electrode mixture 5, and the nonaqueous electrolytic solution is injected from above. On the other hand, the lithium negative electrode 7 stamped into a disc shape is pressed onto the center of the inner surface of the negative electrode terminal 9, and the gasket 10 is fitted onto the peripheral edge of the negative electrode terminal 9. Then, after covering the positive electrode can 2 with the negative electrode terminal 9 so that the lithium negative electrode 7 faces the positive electrode mixture 5 with the separator 6 in between, the rising part of the positive electrode can 2 is caulked inward to seal it. At this point, the assembly of the coin-shaped lithium battery 1 is completed.

In the above-mentioned embodiment, the case where a sublimable substance is used for preparing the porous positive electrode mixture 5 having a porosity of 34 to 40% and a porosity utilization rate of 80% or more. As described above, a decomposable / evaporable substance (an inorganic or organic substance that decomposes or evaporates by vacuum drying, such as ice, polyvinylpyrrolidone, or polyvinyl butyral) can be used instead of the sublimable substance. Hereinafter, a case of preparing the porous positive electrode mixture 5 using a decomposable / evaporable substance will be described.

That is, when ice is used as the decomposable / evaporable substance, a positive electrode active material composed of manganese dioxide (main agent), graphite or carbon black (conductive material), and polytetrafluoroethylene (binder) is added. After adding water, it is cooled to −10 ° C. to solidify the water into an ice state. The amount of water added is 1 to the positive electrode active material.
5%. Next, this is mixed and granulated to form a pellet, and then vacuum dried. Then, the ice evaporates, and as a result, a porous positive electrode mixture 5 having a porosity of 34 to 40% and a porosity utilization rate of 80% or more is prepared.

When polyvinylpyrrolidone (hereinafter abbreviated as "PVP") or polyvinyl butyral (hereinafter abbreviated as "PVB") is used as the decomposable / evaporable substance, manganese dioxide (main agent), graphite or carbon is used. PVP or P is added to the positive electrode active material composed of black (conductive material) and polytetrafluoroethylene (binder).
Add VB. The addition amount of PVP or PVB is 1 to 5% with respect to the positive electrode active material. Next, this is mixed and granulated to form a pellet, and then vacuum dried. Then,
PVP or PVB is decomposed or evaporated, and as a result, a porous positive electrode mixture 5 having a porosity of 34 to 40% and a porosity utilization rate of 80% or more is prepared.

In order to confirm the above effects, camphor, ice, P
VP was added to the positive electrode active material in an amount of 1, 3 and 5%, respectively, and the mixture was molded with a molding pressure of 4 and 6 tons to prepare a porous positive electrode mixture (Example). When the amounts of camphor, ice and PVP added exceeded 5%, a phenomenon was observed in which the positive electrode mixture stuck to the mold during molding. In addition, as a comparative example, a conventional positive electrode mixture formed by using a mold without adding a sublimable substance or a decomposable / evaporable substance to a positive electrode active material and molding with a molding pressure of 2, 3, 4, 5, or 6 tons. (Conventional example) was prepared. The molding density and porosity of these positive electrode mixtures were determined. The porosity is
It was calculated from the true specific gravity and the molding density of the positive electrode mixture obtained by evacuation of the mixture particles in the components of the non-aqueous electrolyte (propylene carbonate and dimethoxyethane containing no solute) using the mathematical formula shown in Formula 1. . In addition, the pores that can be absorbed, that is, the absorption space, obtained from the absorption amount when the positive electrode mixture is immersed in the non-aqueous electrolyte (assuming the absorption state of the non-aqueous electrolyte during normal battery assembly). Then, the void utilization rate was calculated from the liquid absorption space and the void rate using the mathematical formula shown in Formula 2.

[0020]

## EQU1 ## Porosity (%) = 100 × (1-molding density ÷ true specific gravity)

[0021]

## EQU00002 ## Porosity utilization rate (%) = 100 × (liquid absorption space / porosity)

The results are summarized in Table 1.

[0023]

[Table 1]

As is apparent from Table 1, in the conventional example, as the molding pressure increases, the molding density tends to increase and the porosity tends to decrease. Further, it can be seen that the difference between the porosity and the liquid absorption space is increasing, and the higher the pressure is, the larger the number of pores in which the non-aqueous electrolyte is not held. On the other hand, in the examples, even if the molding pressure is high, the number of pores (concealed space) not filled with the non-aqueous electrolyte is reduced due to the addition of the sublimable substance or the decomposable / evaporable substance. It can be said that it is being used.

Further, heavy load discharge characteristics (2.7 kΩ) were compared between the above embodiment and the conventional example. The result is shown in Figure 2.
Shown in. In Fig. 2, is camphor, is ice, and is PVP
Is a discharge curve when is used, and is a discharge curve of a conventional example. It can be seen from FIG. 2 that the discharge performance at the time of heavy load discharge is stabilized in the embodiment (FIG. 2) compared to the conventional example (FIG. 2).

Although the coin type lithium battery 1 has been described in the above embodiment, the present invention can be applied to a bobbin type or spiral type lithium battery.

[0027]

As described above, according to the present invention,
The sublimable substance and the decomposable / evaporable substance contained in the molding are vaporized, decomposed or evaporated by drying, and the porous positive electrode mixture 5
Quickly absorbs non-aqueous electrolyte as a large amount (1 g of positive electrode mixture)
Since 0.18 g or more) of non-aqueous electrolyte can be stably held, it is possible to stabilize the discharge performance during heavy load discharge without increasing the number of parts.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a non-aqueous electrolyte battery according to the present invention.

FIG. 2 is a graph showing heavy load discharge characteristics of a non-aqueous electrolyte battery.

[Explanation of symbols]

 1 ... Non-aqueous electrolyte battery 5 ... Porous positive electrode mixture 6 ... Separator 7 ... Negative electrode 8 ... Power generation element

Claims (3)

[Claims] 1. A power generation element (8) in which a porous positive electrode mixture (5) and a negative electrode (7) are opposed to each other through a separator (6).
In the non-aqueous electrolyte battery (1) configured by injecting a non-aqueous electrolyte into the positive electrode mixture, the positive electrode mixture has a porosity of 34 to 40%, and 8
A non-aqueous electrolyte battery having a pore utilization rate of 0% or more. 2. A sublimable substance is added to the positive electrode active material in an amount of 1 to 5% with respect to the positive electrode active material, which is then mixed and granulated to form a predetermined shape, which is then dried by heating. Then, the sublimable substance is vaporized to prepare a porous positive electrode mixture (5), and further, the negative electrode (7) is opposed to the positive electrode mixture through the separator (6) to generate a power generating element (8). And a method for manufacturing a non-aqueous electrolyte battery, in which the non-aqueous electrolyte solution is configured to be injected into the power generation element. 3. A decomposable / evaporable substance is added to the positive electrode active material in an amount of 1 to 5% with respect to the positive electrode active material, and this is mixed / granulated to form a predetermined shape, and then this is formed. Vacuum decomposition is performed to decompose or evaporate the decomposable / evaporable substance to prepare a porous positive electrode mixture (5), and the negative electrode (7) is opposed to the positive electrode mixture via a separator (6). A method for manufacturing a non-aqueous electrolyte battery, in which the power generating element (8) is assembled and the non-aqueous electrolyte is injected into the power generating element.