JP2015050004A - Manufacturing method of all solid state battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an all-solid-state battery in which the resin layer on both sides of the battery in the thickness direction can be made thin by suppressing the lack of wraparound of resin in the insert molding.SOLUTION: A method of manufacturing an all-solid-state battery where a resin coating layer is formed by insert molding on an electrode body for the all-solid-state battery where a solid electrolyte is arranged between a positive electrode body and a negative electrode body includes a step for arranging a resin film, in advance, on the front and back of the electrode body for the all-solid-state battery in the thickness direction, and a step for sealing the side face of the electrode body for the all-solid-state battery by using an insert resin.

Description

  The present invention relates to a method for manufacturing an all-solid battery, and more particularly, to a method for manufacturing an all-solid battery that can suppress the shortage of resin wrapping in insert molding and can thin the resin layers on both sides in the thickness direction of the battery. .

In recent years, lithium batteries have been put into practical use as batteries having high voltage and high energy density. Due to the expansion of the use of lithium batteries in a wide range of fields and the demand for high performance, various studies have been conducted to further improve the performance of lithium batteries.
Among them, since the electrolyte is not used compared to the conventional non-aqueous electrolyte lithium battery, the system required for improving the safety when using the non-aqueous electrolyte can be simplified. Therefore, it is expected that the all-solid-state battery will be put to practical use because it can have many advantages such as an increased degree of freedom and a reduced number of auxiliary devices.

However, in order to realize the practical application of all-solid-state batteries, various improvements such as the creation of a solid electrolyte capable of providing high capacity and high output and / or the creation of electrodes capable of realizing high electrode utilization efficiency are required. It is.
In addition, all-solid batteries are expected to simplify the exterior because no injection or degassing steps are required. For example, a structure that covers the periphery of the electrode body with a resin insert of an all-solid battery is expected to simplify the exterior. Is done.

  On the other hand, reducing the resin thickness in the electrode thickness direction is the most effective for improving the energy density of all-solid-state batteries, but a thin-wall formation method has been established to secure a flow path for resin injection. It was difficult to improve the energy density.

For this reason, various studies have been made on the exterior technology of all solid state batteries.
For example, in Patent Document 1, an all-solid battery element is loaded into a resin-sealing mold, a resin softened at a melting portion is injected and sealed, and a resin is applied under pressure by pressing with a pressurizing punch. Although an all-solid battery obtained by curing and a method for producing the same are described, the thinning of the resin layer is not shown.

  Patent Document 2 discloses an electrode laminate formed by providing an insulating layer on a current collector or a positive electrode active material layer when laminating a gel electrolyte layer between a plurality of sheet-like electrodes. A method of manufacturing a laminated battery is described in which a side surface of the battery is inserted into a mold, a molten resin is injected into the mold, and the injected resin is cured to form a seal member. It has not been.

According to the all-solid-state battery described in Patent Document 1, the thinning of the resin layer is not recognized, and when the coating resin layer of the all-solid battery is thinned by applying the technique described in Patent Document 1. Insufficient rounding of the resin may occur.
In Patent Document 2, a structure using an insulating layer and a seal member is shown, but a specific molding method is hardly mentioned.
As described above, it is difficult to obtain an all-solid battery capable of thinning the resin coating layer by insert molding of the all-solid battery according to a known technique.

JP 2000-106154 A JP 2004-193006 A

  Accordingly, an object of the present invention is to provide a method for producing an all-solid battery capable of suppressing the shortage of resin wraparound in insert molding and thinning the resin layers on both sides in the thickness direction of the battery.

The present invention provides an all-solid battery manufacturing method in which a resin coating layer is formed by insert molding on an all-solid battery electrode body in which a solid electrolyte is disposed between a positive electrode body and a negative electrode body.
A step of previously arranging resin films on both front and back surfaces in the thickness direction of the all solid state battery electrode body, and a step of sealing a side surface of the all solid state battery electrode body using an insert resin. It relates to a manufacturing method.

  In the insert molding, an all-solid-state battery element electrode body, which is a molded product, is mounted in advance in a mold, the mold is closed, and a resin is injected around the molded product to integrate the molded product and the resin. A forming method for forming an object is called.

  ADVANTAGE OF THE INVENTION According to this invention, the all-solid-state battery which can suppress the shortage of the resin rounding in insert molding and can thin the resin layer of both surfaces of the thickness direction of a battery can be obtained easily.

FIG. 1 is a schematic view collectively showing a plan view, a front view, a right side view, and a partial enlarged view of a right side view of a known all solid state battery. FIG. 2 is a schematic view partially showing the steps of the method for producing an all-solid battery outside the scope of the present invention. FIG. 3 is a schematic view partially showing the steps of another method for manufacturing an all-solid battery outside the scope of the present invention. FIG. 4 is a copy of a sample photograph obtained in the comparative example. FIG. 5 is a copy of a sample photograph obtained in another comparative example. FIG. 6 is a schematic diagram partially showing the steps of the all-solid-state battery manufacturing method in another comparative example. FIG. 7 is a schematic view partially showing the steps of the method for manufacturing an all solid state battery according to one embodiment of the present invention. FIG. 8 is a schematic view partially showing the steps of the method for producing an all solid state battery according to another embodiment of the present invention. FIG. 9 is a copy of a sample photograph obtained in the example. FIG. 10 is a schematic diagram partially showing the steps of the all-solid-state battery manufacturing method in another comparative example. FIG. 11 is a copy of a sample photograph obtained in another comparative example. FIG. 12 is a copy of a photograph of the all-solid-state battery obtained in the example (left figure) and a copy of an enlarged cross-sectional photograph (right figure). FIG. 13 is a copy of a photograph of an all-solid battery obtained in another example. FIG. 14 is a copy of an enlarged cross-sectional photograph of an all-solid battery obtained in another example.

In particular, in the present invention, the following embodiments can be mentioned.
1) The method for producing an all-solid battery as described above, wherein the solid battery electrode body is formed by laminating a plurality of the positive electrode body and the negative electrode body via a solid electrolyte.
2) The step of arranging the resin film in advance includes a step of laminating a plurality of the positive electrode body and the negative electrode body through a solid electrolyte, and laminating with the resin film at the time of positive electrode lamination. A method for producing a solid state battery.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the method for producing an all-solid battery according to an embodiment of the present invention, an all-solid battery in which a resin coating layer is formed by insert molding on an all-solid battery electrode body in which a solid electrolyte is disposed between a positive electrode body and a negative electrode body. In the battery manufacturing method,
The step of disposing a resin film in advance on both front and back surfaces in the thickness direction of the all solid state battery electrode body, and then the step of sealing the side surface of the all solid state battery electrode body using an insert resin, By placing resin films on both sides of the battery electrode body in the thickness direction in advance, it is possible to suppress the shortage of the resin from flowing, the coating resin layer can be made thinner, and the resin is injected into the end of the battery electrode body It is considered that foil breakage due to resin concentration can be suppressed.

As shown in FIG. 1, a conventional all-solid battery is formed by forming a resin coating layer on an all-solid battery element in which a solid electrolyte is disposed between a positive electrode body and a negative electrode body. For example, the thickness is 4.4 mm, and the thickness of the positive electrode side and the negative electrode side of the resin coating layer made of one resin layer is 1 mm each.
As shown in FIGS. 2 and 3, when an all-solid battery is molded by resin coating by insert molding, the thickness of the coated resin layer is reduced by 1 mm to increase the energy density of the all-solid battery. It is necessary to flow molten resin (or resin solution) using a very narrow gap as a resin flow path. For this reason, the resin wraparound becomes insufficient, and as shown in FIGS. On the other hand, if it flows through the resin flow path of the gap widened in order to perform uniform resin coating, the thickness of the resin coating layer related to the energy density becomes large, and the energy density of the all-solid battery is remarkably lowered.

A method for producing an all-solid battery according to an embodiment of the present invention includes:
(1) A step of arranging resin films in advance on both sides of the thickness direction of the all-solid battery electrode body in which a solid electrolyte is arranged between the positive electrode body and the negative electrode body,
(2) The method includes a step of sealing the side surface of the all solid state battery electrode body using an insert resin.
In the above step, the resin film previously disposed on both the front and back surfaces in the thickness direction of the all-solid-state battery electrode body may be a thermoplastic resin or a thermosetting resin precursor film, and the resin film has a thickness of 25 to 25. It may be in the range of about 500 μm, for example, about 50 to 200 μm.
In the above, in the case of a thermoplastic resin, it can be cooled, and in the case of a thermosetting precursor resin, it can be cured by heating under known heating conditions to obtain a resin film.
In the above step, the thickness of the resin mold may be about 0.1 to 5 mm, for example, about 0.5 to 5 mm.

In an embodiment of the present invention, the solid battery electrode body may be formed by laminating a plurality of the positive electrode body and the negative electrode body via a solid electrolyte.
In another embodiment of the present invention, the step of previously arranging the resin film includes a step of laminating a plurality of the positive electrode body and the negative electrode body via a solid electrolyte, and attaching the resin film during the positive electrode lamination. And laminating.
After the injection step, by removing the molded product, the resin film on both the upper and lower surfaces (front and back) of the battery prevents the resin from wrapping around, and the resin coating layer is thinned. It is possible to obtain an all-solid battery in which foil breakage due to resin concentration when the resin is injected is suppressed.
In particular, in the embodiment of the present invention, as shown in FIG. 8, a step of laminating a plurality of the positive electrode body and the negative electrode body through a solid electrolyte, and laminating the resin film together with the positive electrode is laminated. By including it, as shown in FIGS. 13 and 14, the electrode body is wrapped with resin, and an all-solid battery in which the end portion of the foil does not break can be obtained.

In the above production method, the resin constituting the resin mold is preferably a thermoplastic resin such as polypropylene, polyethylene, polyamide, or a thermosetting resin such as epoxy resin, phenol resin, or unsaturated polyester resin. A plastic resin is mentioned.
In addition, as the resin of the resin film and the injection resin, thermoplastic resins such as polypropylene, polyethylene, polyamide, etc., and thermosetting resins such as epoxy resin, phenol resin, unsaturated polyester resin, etc., preferably thermoplastic resins Is mentioned.
In the present invention, the resin film, the resin-type resin material, and the resin material to be injected are preferably the same, and polypropylene is preferable from the viewpoint of molding temperature and battery durability.
Said resin, preferably a thermoplastic resin, for example polypropylene, can contain additives or fillers known per se.

The all solid state battery electrode body can be obtained as follows. For example, a positive electrode slurry containing an active material, a solid electrolyte such as a sulfide solid electrolyte material, a binder, and a solvent is applied onto a positive electrode current collector to obtain a positive electrode. On the other hand, a negative electrode slurry containing an active material, a solid electrolyte, a binder, and a solvent is applied onto a negative electrode current collector to obtain a negative electrode. An electrode body can be obtained by stacking a plurality of, typically 20, positive electrodes and negative electrodes through a solid electrolyte.
A metal foil such as SUS foil or Al foil can be used as the current collector for the positive electrode, and a metal foil such as SUS foil or Cu foil can be used as the current collector for the negative electrode.

In an embodiment of the present invention, the active material includes lithium cobaltate (Li _x CoO ₂ ), lithium nickelate (Li _x NiO ₂ ), nickel manganese lithium cobaltate (Li _{1 + x} Ni _1/3 Mn _1/3). Co _1/3 O ₂ ), nickel lithium cobaltate (LiCo _0.3 Ni _0.7 O ₂ ), lithium manganate (Li _x Mn ₂ O ₄ ), lithium titanate (Li _4/3 Ti _5/3 O) _4), lithium manganese oxide compound _{(Li 1 + x M y Mn} 2-x-y O 4; M = Al, Mg, Fe, Cr, Co, Ni, Zn), lithium titanate _(Li x _TiO y), phosphoric acid metallic lithium _{(LiMPO 4, M = Fe,} Mn, Co, Ni), vanadium oxide _{(V 2 O} 5), molybdenum oxide (MoO3), titanium sulfide ( iS _2), lithium cobalt nitride (LiCoN), lithium silicon nitride (LiCoN), lithium metal, lithium alloy (LiM, M = Sn, Si , Al, Ge, Sb, P), lithium storage intermetallic compound ( (MgxM, M = Sn, Ge, Sb, or XySb, X = In, Cu, Mn) and their derivatives, carbon materials (C) such as graphite and hard carbon. Here, there is no clear distinction between the positive electrode active material and the negative electrode active material, and the positive and negative potentials are compared for the positive electrode and the negative potential is used for the negative electrode by comparing the charge and discharge potentials of the two types of compounds. Thus, an electrode having an arbitrary voltage can be formed.
For example, Li _x CoO ₂ , Li _x NiO ₂ , Li _x Mn ₂ O ₄ , Li _x Ni _1/2 Mn _1/2 O ₂ , Li _x Ni _1/3 Co _1/3 Mn _1/3 O ₂ , Li _x [Ni _y Li _{1 / 3-2y / 3} ] O ₃ (0 ≦ x ≦ 1, 0 <y <1/2) and lithium or transition metal of these lithium transition metal oxides were substituted with other elements Lithium transition metals such as LiNiMnCoO ₂ can be mentioned as the positive electrode active material.
Moreover, carbon materials (C), such as graphite and hard carbon, are preferably used as the negative electrode active material.

Examples of the solid electrolyte include Li ₂ S—SiS ₂ , LiI—Li ₂ S—SiS ₂ , liI-li ₂ S—P ₂ S ₅ , LiI—Li ₂ S—B ₂ S ₃ , Li ₃ PO ₄ —. _{Li 2 S-Si 2 S,} Li 3 PO 4 -Li 2 S-SiS 2, LiPO 4 -Li 2 S-SiS, LiI-Li 2 S-P 2 O 5, LiI-Li 3 PO 4 -P 2 S ₅ , sulfide-type amorphous solid electrolytes such as Li ₃ PS ₄ and Li ₂ S—P ₂ S ₅ .

The Li ₂ S—P ₂ S ₅ can be obtained from lithium sulfide and diphosphorus pentasulfide and / or simple phosphorus and simple sulfur. For example, these raw materials are melt-reacted and then rapidly cooled or the raw materials are used. It can be obtained by heat-treating sulfide glass obtained by processing by a mechanical milling method. The mixing molar ratio of lithium sulfide to diphosphorus pentasulfide or simple phosphorus and simple sulfur is usually 50:50 to 80:20, preferably 60:40 to 75:25, and preferably Li ₂ S: P _2. S ₅ = 70: 30~75: is about 25 (mole ratio).

In the embodiment of the present invention, the active material, the solid electrolyte, and a commonly used conductive agent can be used.
Examples of the conductive agent include carbon materials and metals that are difficult to be alloyed with lithium, such as aluminum and conductive polymer materials, and aluminum and carbon materials are preferable. As the carbon material, graphite, carbon black, carbon nanotube, carbon nanofiber, fullerene and the like can be used alone or in combination of two or more.
Examples of the binder include polybutadiene rubber (BR rubber), styrene butadiene rubber (SBR), polyacrylate, and polyvinylidene fluoride (PVdF).
The proportion of each component in the total solid content in the positive electrode and the negative electrode material is 60% by mass or more and 98.5% by mass or less, the solid electrolyte is 10 to 35% by mass, and the binder is 1% by mass or more and 20% by mass. % Or less, and the conductive agent may be 0 to 30% by mass or less.

  According to the manufacturing method of the embodiment of the present invention, insufficient resin wrapping is suppressed by the resin films on both the upper and lower surfaces (front and back) of the battery, the resin coating layer is thinned, and the resin is injected into the end of the battery. Thus, it is possible to obtain an all-solid battery in which foil breakage due to resin concentration is suppressed.

Examples of the present invention will be described below.
The following examples are for illustrative purposes only and are not intended to limit the invention.

Comparative Example 1
1. Production of Electrode Body 8Li ₂ O · 67Li ₂ S · 25P ₂ S ₅ glass was used as the solid electrolyte.
LiNi (1/3) Co (1/3) Mn (1/3) O ₂ coated with LiNbO ₃ having a thickness of 7 nm on the surface, the above solid electrolyte, and BR rubber as a binder at 65: 30: 5 (mass% ) To obtain a positive electrode slurry using heptane as a solvent. The positive electrode was obtained by applying on an aluminum foil.
Carbon, the above-mentioned solid electrolyte, and BR rubber as a binder were mixed at a ratio of 65: 30: 5 (mass%) to obtain a negative electrode slurry using heptane as a solvent. This was coated on a copper foil to obtain a negative electrode.
Twenty layers of the positive electrode and the negative electrode were laminated via the solid electrolyte to obtain an electrode body (50 × 50 × ³ mm ³ ).
The positive electrode current collector foils were bonded to a tab having a thickness of 200 μm using ultrasonic bonding.
On the other hand, the negative electrode current collector foils were bonded to a tab having a thickness of 200 μm using ultrasonic bonding.

2. Resin Molding As shown schematically in FIG. 2, an electrode body was placed in a resin mold, and PP resin was injected from the tab side of the electrode body.
A photograph of the obtained sample is shown in FIG.
From FIG. 4, the wraparound of the resin was insufficient particularly on the side opposite to the tab.

Comparative Example 2
The electrode body was produced in the same manner as in Comparative Example 1, and at the time of resin molding, PP resin was injected from the thickness side as shown in the schematic diagram of FIG.
A photograph of the obtained sample is shown in FIG.
From FIG. 5, the wraparound of the resin was insufficient particularly at the center on the back side.

Comparative Example 3
The electrode body was produced in the same manner as in Comparative Example 1, and at the time of resin molding, PP resin was injected from the ends of the four sides as shown in the schematic diagram of FIG.
A photograph of the obtained sample is shown in FIG.
From FIG. 11, the wraparound of the resin was not sufficient on the side opposite to the tab, and contraction toward the center of the electrode was observed.

Example 1
After the electrode body was manufactured in the same manner as in Comparative Example 1, the electrode body was sandwiched vertically from the thickness direction with a film made of PP resin tree. Thereafter, as shown schematically in FIG. 7, PP resin was injected from the end portions of the four sides.
A photograph of the obtained sample is shown in FIG.
From FIG. 12, a battery in which the electrode body was wrapped with resin was obtained.
Although the wraparound of the resin was achieved on the opposite side of the tab, the foil cut due to the resin concentration was observed depending on the part.

Example 2
The electrode body was prepared in the same manner as in Example 1 except that the lamination was performed with the PP resin film as shown in FIG. PP resin was injected from the end side.
A photograph of the obtained sample is shown in FIG.
Moreover, a cross-sectional enlarged photograph is shown in FIG.
From FIG. 14, the wraparound of the resin was achieved on the side opposite to the tab, and a battery in which the electrode body was wrapped with the resin was obtained. As a result of cross-sectional observation, no edge breakage was observed.

  According to the present invention, it is possible to easily obtain an all-solid battery capable of suppressing the shortage of resin wrapping in insert molding and thinning the resin layers on both sides in the thickness direction of the battery.

Claims (3)

In the method for producing an all-solid battery in which a resin coating layer is formed by insert molding on an all-solid battery electrode body in which a solid electrolyte is disposed between a positive electrode body and a negative electrode body,
A step of previously arranging resin films on both front and back surfaces in the thickness direction of the all solid state battery electrode body, and a step of sealing a side surface of the all solid state battery electrode body using an insert resin. Production method.   The method for producing an all-solid-state battery according to claim 1, wherein the solid-state battery electrode body is formed by laminating a plurality of the positive-electrode body and the negative-electrode body via a solid electrolyte.   The step of arranging the resin film in advance includes a step of laminating a plurality of the positive electrode body and the negative electrode body via a solid electrolyte and laminating the resin film together with the positive electrode layer. Of manufacturing all solid state battery.