JPH02211970A - Lithium thin-film material and production thereof - Google Patents

Abstract

PURPOSE:To continuously produce the extremely thin lithium thin-film having uniform quality and exact size by depositing lithium metals in the aperture parts of a thin-film-like porous carrier consisting of a metal, etc. CONSTITUTION:The strip-shaped thin-film-like porous carrier 1 is un-wound and the lithium metals 5 in a supply container 4 are deposited in the aperture parts 13 of the porous carrier 1 on a roller 8. Metal lithium, metal contg. lithium, or metal lithium incorporated with a different material, etc., are used for the lithium metals 5. The thin-film-like porous carrier 1 is made of a metal or heat resistant inorg. material. The lithium thin-film of the desired thickness regulated by the size of the aperture parts 13 is produced. A battery having an excellent cathode characteristic is provided in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lithium thin film material that can be used, for example, as a lithium electrode, and a method for producing the same.

[Prior Art] Conventional lithium thin films are manufactured by mechanical processing such as extrusion and rolling. For example, Japanese Patent Publication No. 55-122 discloses a method for manufacturing a relatively thin lithium strip of about 40 microns by cold rolling lithium metal between the surfaces of a solid polymer composition to reduce its thickness. Japanese Patent Publication No. 55-41841 discloses a method of rolling a metal foil by passing it together with a plastic belt through a gap between a pair of rollers.

[Problem to be solved] However, according to conventional manufacturing methods such as rolling and extrusion, a very thin lithium film of, for example, 100 μm or less can be obtained, but the obtained thin film has mechanical characteristics unique to lithium metal. It is extremely difficult to handle because it is easily deformed, and because it does not have sufficient tensile strength, it is easily torn. In addition, in metals containing lithium or metal lithium mixed with foreign substances, for example, L
In alloys such as i-Al and Li-Mg, AI
, Mg content of 30w%, 40w%, etc. is thought to be able to extend the lifespan of secondary batteries. Despite the desire to provide alloys with such content, it is virtually impossible to process them into the desired dimensions and shapes due to increases in hardness, viscosity, and brittleness. In particular, this was an impediment to the research, development, and commercialization of lithium secondary batteries.

The purpose of this invention is to provide a material that is easy to work with, has accurate dimensions, and is inexpensive, while taking into account the mechanical properties unique to lithium metals such as metallic lithium, metals containing lithium, or metallic lithium mixed with foreign substances. The object of the present invention is to provide a manufacturing method and a product by which a lithium thin film can be obtained, particularly for lithium metals, which have conventionally been virtually impossible to process.

[Means for solving the problem] As a result of intensive studies to achieve the above objective, the viscosity and fluidity at high temperatures of lithium metals such as metallic lithium, metals containing lithium, or metallic lithium mixed with foreign substances was determined. Using the wetting properties, lithium metals are supported in the pores of a thin film-like porous carrier made of a metal or a heat-resistant inorganic material, and a lithium thin film with a desired thickness regulated by the size of the pores is formed into a lithium thin film material. We have developed a manufacturing method to obtain it. That is, we have developed a lithium thin film material consisting of a thin film-like porous carrier made of a metal or a heat-resistant inorganic material, and a thin film of lithium metal supported within the pores of this porous carrier.

[Function] Therefore, according to the present invention, since lithium metals are supported within the pores of the thin film-like porous carrier, there is no need to perform mechanical processing such as rolling as in the past to make the lithium film thin. It does not cause deformation or tearing, has extremely good workability, and can be easily formed into thin films even for lithium metals with high content such as AI and Mg, which were previously considered difficult or impossible to form. There are particularly significant advantages. Furthermore, the dimensions of the supported lithium thin film are regulated by the pore dimensions of the thin film-like porous carrier, so by appropriately selecting the pore dimensions, it is possible to obtain a lithium thin film of desired thickness with accurate dimensions. can.

Furthermore, in order to support lithium metals in the openings of the thin film porous carrier, a molten metal of lithium metals is fed into the openings of the thin film porous carrier at a low temperature.
Since the whole solidifies uniformly within a short period of time, especially in the case of metals containing lithium or metallic lithium mixed with foreign substances, the molten metal is poured into a mold and gradually cooled to solidify as in the conventional method. It is possible to prevent the imbalance of components called segregation, which occurs due to the difference in specific gravity between lithium and other metals in the boundary, which often occurs when processing such as rolling or extrusion, and create a homogeneous lithium metal throughout. It is also possible to obtain similar thin films.

Since the lithium thin film is supported within the pores of a thin porous carrier and obtained as a lithium thin film material, it is possible to easily increase the size of the product by appropriately selecting the size of the thin porous carrier. Since this lithium thin film material can be used as it is as a current collector, in that case there is an advantage that steps can be omitted during battery manufacturing.

Further, according to the present invention, since a rolling device or an extrusion device is not required, a large-scale device is not required even in mass production or manufacturing of large products, and the initial investment and running costs are low.

[Example] FIG. 1 is a schematic diagram illustrating an embodiment of the present invention.

Reference numeral 1 denotes a strip-like thin film-like porous carrier made of a metal material, and is arranged so as to be fed from an unwinding roller 2 and wound up by a winding roller 3 as shown in the figure. Reference numeral 4 denotes a supply container for lithium metals 5 placed at an intermediate position. The supply container 4 is equipped with a heater 6 in order to supply lithium metals onto the thin film porous carrier 1 in a molten state, and is also equipped with a heating heater 6 to supply lithium metals into the pores of the thin film porous carrier 1 while avoiding excessive melting. In order to facilitate supply, the lithium metals 5 are configured to be pressurized with an inert gas 7 such as Ar as necessary. A roller 8 is disposed on the opposite side of the supply container 4 across the thin film-like porous carrier 1 to ensure that the lithium metals 5 are supported within the openings in the porous carrier 1. Note that 9 is a roller 10.11
1 is a spatula, and 12 is a stirring propeller provided in the supply container.

Therefore, the thin film-like porous carrier 1 fed from the unwinding roller 2 is supplied with lithium metals 5 in a molten state on the roller 8, and the lithium metals 5 enter the openings of the thin film-like porous carrier 1. It is uniformly solidified by the thin film-like porous carrier 1 at a low temperature, and is supported within the openings of the thin film-like porous carrier 1. Then, it passes through roller 9 and spatulas 10 and 11, and is then wound up by winding roller 3.

FIG. 2 shows a lithium thin film material obtained by this method, consisting of a thin film-like porous carrier 1 made of a metal material and a thin film-like lithium metal 14 supported in the openings 13 of this porous carrier 1. FIG.

FIG. 3 is a schematic diagram illustrating another embodiment of the invention.

In this example, unlike the previous example, a strip-shaped thin film porous carrier 1 is passed through a bath 15 containing lithium metals 5 heated and melted by a heating heater 6, and lithium metals 5 are applied to the porous carrier 1. A method is adopted in which the material is fed into the opening in a so-called impregnated state.

Therefore, the thin film-like porous carrier 1 fed from the unwinding roller 2 passes through the tank 15 of the lithium metals 5 and receives the lithium metals 5 in a molten state on the roller 8 into the openings thereof. , lithium metals 5 are fed into the openings of the thin film-like porous carrier 1, solidify uniformly outside the tank 15, and are supported within the openings of the thin film-like porous carrier 1. In addition, as in the above embodiment, numeral 9 is a roller, 10.11 is a spatula, 1
2 is a stirring propeller provided in the tank 15.

However, the present invention is not limited to the above embodiments. For example, in the above embodiment, a strip-shaped thin film porous carrier 1 is used to enable continuous production, but a single thin film porous carrier may also be used discontinuously. Further, the material thereof is not limited to metals such as stainless steel, nickel, and copper, and a thin film-like porous carrier made of a heat-resistant inorganic material such as a ceramic material may also be used. As the thin film-like porous carrier, it is easy to use a so-called screen material such as a net or expanded metal, but it is not particularly limited to the screen material itself. In short, any thin film-like porous carrier in which a molten lithium metal is introduced into the openings and supported thereon can be used.

When supporting lithium metals within the pores of a thin film-like porous carrier, it is not preferable to heat and melt the lithium metals to too high a temperature, or conversely, to melt them at too low a temperature. This is because if the temperature is too high, the solidification rate in the pores of the lithium metal will not be able to keep up, and the hot water of the lithium metal will tend to fall out through the pores of the porous carrier.On the other hand, if the temperature is too low, This is because it becomes difficult to feed the lithium into the openings and solidifies immediately, making it impossible to obtain a uniform lithium thin film. Therefore, a viscosity that can be supplied into the opening and has a holding power to the extent that it does not flow out in the opening,
It is desirable to have a molten state that exhibits fluidity and wetting properties. In this sense, in addition to these, it is preferable to adjust the temperature of the porous carrier to lower it in order to suitably support it within the pores. It is also important to consider the size of the pores, etc., and it is desirable to consider the characteristics such as viscosity of various lithium metals while considering the expected properties and uses of the lithium thin film material when making a selection. .

Note that in order to promote the feeding of the porous carrier into the pores, forcible vibration may be separately applied.

Furthermore, when using a continuous strip method as in the above embodiment, it is also important to consider the traveling speed of the porous carrier. In any case, there is no problem as long as various factors are taken into consideration and conditions are appropriately set depending on the characteristics of the lithium metals used.

Note that the lithium thin film material is preferably obtained by the manufacturing method according to the above embodiment, but the manufacturing method is not particularly limited. In short, instead of using a lithium thin film itself as in the past, it is a lithium thin film material consisting of a thin film-like porous carrier made of a metal or heat-resistant inorganic material, and a thin film-like lithium metal supported within the pores of this porous carrier. All can be applied. Further, in the present invention, when supporting lithium metals on the thin film-like porous carrier, it is preferable to carry the lithium metals only in the open pores, but it is also possible to make them adhere to the surface of the porous carrier itself.

[Effects of the Invention] As described above, the present invention has a structure in which a lithium thin film is obtained as a lithium thin film material by supporting lithium metals in the openings of a thin film-like porous carrier such as a metal.
Lithium metals can be made into thin films without mechanical processing such as direct rolling, and ultra-thin lithium films with uniform and accurate dimensions can be produced without deforming or tearing like in the past, and with no raw material loss. Can be manufactured continuously in large quantities with good reproducibility. Therefore, for example, when manufacturing batteries, it is easy to handle and work.
It also demonstrates economic efficiency. Moreover, it is noteworthy that lithium thin films can be obtained even for lithium metals such as A1, Mg-rich lithium-containing metals, or metallic lithium mixed with foreign substances, which were previously considered virtually impossible to mechanically process. As a result, it is possible to provide a battery with extremely superior cathode properties that have never been seen before, which greatly contributes to the technical field.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram explaining one embodiment of the present invention, FIG. 2 is a partial cross-sectional view of a lithium thin film material obtained by the same manufacturing method, and FIG.
The figure is a schematic diagram illustrating another embodiment of the invention.

Claims (2)

[Claims] (1) Lithium metals such as metallic lithium, metals containing lithium, or metallic lithium mixed with foreign substances are supported in the pores of a thin film-like porous carrier made of a metal or a heat-resistant inorganic material, and the pores are A method for producing a lithium thin film material, characterized by obtaining a lithium thin film with a desired thickness regulated by part dimensions. (2) A lithium thin film material consisting of a thin film-like porous carrier made of a metal or a heat-resistant inorganic material, and a thin film-like lithium metal supported within the pores of the porous carrier.