WO2018110067A1

WO2018110067A1 - Secondary cell, cell pack, electric vehicle, power storage system, electric tool, and electronic device

Info

Publication number: WO2018110067A1
Application number: PCT/JP2017/037361
Authority: WO
Inventors: 貴正小野; 宮木　幸夫; 真樹倉塚; 崇弘白井; 隆尚石松; 翔高橋; 田中　俊
Original assignee: 株式会社村田製作所
Priority date: 2016-12-16
Filing date: 2017-10-16
Publication date: 2018-06-21
Also published as: JPWO2018110067A1; JP6801722B2

Abstract

A secondary cell is provided with: a cell element containing a positive electrode, a negative electrode, and an electrolyte; and a film-type exterior member that stores that cell element, and which has a window part containing a non-porous melted fluororesin.

Description

Secondary battery, battery pack, electric vehicle, power storage system, electric tool and electronic device

The present technology relates to a secondary battery using a film-shaped exterior member, and a battery pack, an electric vehicle, an electric power storage system, an electric tool, and an electronic device using the secondary battery.

Various electronic devices such as mobile phones and personal digital assistants (PDAs) are widely used, and there is a demand for downsizing, weight reduction, and long life of the electronic devices. Therefore, development of a battery, particularly a secondary battery that is small and lightweight and capable of obtaining a high energy density is underway as a power source.

Secondary batteries are not limited to the electronic devices described above, but are also being considered for other uses. For example, a battery pack detachably mounted on an electronic device, an electric vehicle such as an electric vehicle, an electric power storage system such as a household electric power server, and an electric tool such as an electric drill.

The laminated film type secondary battery is a secondary battery using a film-shaped exterior member. In a laminated film type secondary battery, a battery element is housed inside a film-shaped exterior member, and the battery element includes a positive electrode, a negative electrode, an electrolytic solution, and the like.

Since the film-shaped exterior member has flexibility, it has a property of being easily deformed according to an external force. For this reason, in a laminated film type secondary battery, when gas is generated inside the secondary battery, the secondary battery tends to swell due to deformation of the film-shaped exterior member.

Various studies have been made to prevent the secondary battery from expanding in this way. Specifically, in order to release the gas generated inside the secondary battery to the outside, a safety valve or the like is provided on the film-shaped exterior member (see, for example, Patent Documents 1 to 4).

JP 2007-087922 A JP 2007-157678 A JP 2007-265725 A JP 2014-211994 A

Electronic devices are becoming more sophisticated and multifunctional. For this reason, the use frequency of electronic devices and the like is increasing, and the use environment of the electronic devices and the like is expanding. Therefore, there is still room for improvement regarding battery characteristics including the swelling characteristics of the secondary battery.

Therefore, it is desirable to provide a secondary battery, a battery pack, an electric vehicle, an electric power storage system, an electric tool, and an electronic device that can obtain excellent battery characteristics.

A secondary battery according to an embodiment of the present technology includes a battery element including a positive electrode, a negative electrode, and an electrolyte, and a film-shaped exterior member that houses the battery element and includes a window portion that includes a non-porous molten fluororesin. It is equipped with.

Each of the battery pack, the electric vehicle, the power storage system, the electric tool, and the electronic device according to the embodiment of the present technology includes a secondary battery, and the secondary battery includes the secondary battery according to the embodiment of the present technology described above. It has the same configuration.

Here, the “window” is a part of the film-shaped exterior member, and is exposed to each of the internal environment in which the battery element is accommodated and the external environment in which the battery element is not accommodated. The internal environment is an environment inside the film-shaped exterior member, and the external environment is an environment outside the film-shaped exterior member.

According to the secondary battery of one embodiment of the present technology, the battery element is housed in the film-shaped exterior member, and the window portion including the non-porous molten fluororesin is provided in the exterior member. Excellent battery characteristics can be obtained. The same effect can also be obtained in the battery pack, the electric vehicle, the power storage system, the electric tool, or the electronic device according to the embodiment of the present technology.

In addition, the effect described here is not necessarily limited, and may be any effect described in the present technology.

It is a perspective view showing the structure (state before bonding of an exterior member) of the secondary battery of 1st Embodiment of this technique. It is a perspective view showing the other structure (state after bonding of an exterior member) of the secondary battery shown in FIG. FIG. 2 is a cross-sectional view illustrating a configuration of an exterior member along line AA illustrated in FIG. 1. FIG. 2 is a cross-sectional view illustrating a configuration of a wound electrode body taken along line BB illustrated in FIG. 1. It is a perspective view for demonstrating the 1st modification regarding the structure of a secondary battery. It is a perspective view for demonstrating the 2nd modification regarding the structure of a secondary battery. It is a perspective view for demonstrating the 3rd modification regarding the structure of a secondary battery. It is a perspective view showing the structure (state after bonding of an exterior member) of the secondary battery of 2nd Embodiment of this technique. FIG. 9 is a cross-sectional view illustrating a configuration of an exterior member along the line CC illustrated in FIG. 8. FIG. 9 is a cross-sectional view illustrating a configuration of an exterior member along the line DD illustrated in FIG. 8. It is a perspective view showing the structure of the application example (battery pack: single cell) of a secondary battery. It is a block diagram showing the structure of the battery pack shown in FIG. It is a block diagram showing the structure of the application example (battery pack: assembled battery) of a secondary battery. It is a block diagram showing the structure of the application example (electric vehicle) of a secondary battery. It is a block diagram showing the structure of the application example (electric power storage system) of a secondary battery. It is a block diagram showing the structure of the application example (electric tool) of a secondary battery.

Hereinafter, an embodiment of the present technology will be described in detail with reference to the drawings. The order of explanation is as follows.

1. Secondary battery (first embodiment)
1-1. Lithium ion secondary battery 1-2. Lithium metal secondary battery 1-3. Modification 2 Secondary battery (second embodiment)
2-1. Lithium ion secondary battery 2-2. Lithium metal secondary battery 2-3. Modified example 3. Applications of secondary batteries 3-1. Battery pack (single cell)
3-2. Battery pack (assembled battery)
3-3. Electric vehicle 3-4. Electric power storage system 3-5. Electric tool

<1. Secondary Battery (First Embodiment)>
First, the secondary battery of the first embodiment will be described.

<1-1. Lithium ion secondary battery>
The secondary battery described here is, for example, a lithium ion secondary battery in which the capacity of the negative electrode is obtained by occlusion and release of lithium, which is an electrode reactant.

FIG. 1 and FIG. 2 each show a perspective configuration of the secondary battery of the present embodiment. However, FIG. 1 shows a state before the exterior member 40 is bonded, and the wound electrode body 30 and the exterior member 40 are separated from each other. FIG. 2 shows a state after the exterior member 40 is bonded.

FIG. 3 shows a cross-sectional configuration of the exterior member 40 along the line AA shown in FIG. FIG. 4 shows a cross-sectional configuration of the spirally wound electrode body 30 along the line BB shown in FIG.

[overall structure]
This secondary battery is a laminated film type secondary battery using a film-like exterior member 40. In a laminated film type secondary battery, for example, as shown in FIGS. 1 to 3, a wound electrode body 30 as a battery element is housed inside an exterior member 40 having a window portion 42. Details of the window 42 will be described later.

In the wound electrode body 30, for example, as shown in FIG. 4, after the positive electrode 33 and the negative electrode 34 are laminated via the separator 35 and the electrolyte layer 36, the positive electrode 33, the negative electrode 34, the separator 35, and the electrolyte layer 36 are stacked. Is wound. That is, the spirally wound electrode body 30 housed inside the exterior member 40 includes a positive electrode 33, a negative electrode 34, and an electrolyte layer 36, and the electrolyte layer 36 includes an electrolyte solution described later. The outermost peripheral part of the wound electrode body 30 is protected by a protective tape 37, for example.

The positive electrode lead 31 is attached to the positive electrode 33, and the positive electrode lead 31 is led out from the inside of the exterior member 40 to the outside. The positive electrode lead 31 includes, for example, any one type or two or more types of conductive materials such as aluminum (Al). The shape of the conductive material is not particularly limited, and is, for example, a thin plate shape or a mesh shape.

The negative electrode lead 32 is attached to the negative electrode 34, and the negative electrode lead 32 is led out from the inside of the exterior member 40 to the outside. The negative electrode lead 32 includes any one type or two or more types of conductive materials such as copper (Cu), nickel (Ni), and stainless steel. The shape of the conductive material is the same as that described for the positive electrode lead 31, for example.

In FIG. 2, the positive electrode lead 31 and the negative electrode lead 32 are not shown. Each of the positive electrode lead 31 and the negative electrode lead 32 is led out in the same direction from the inside of the exterior member 40 to the outside, as is apparent from FIG. 1, for example.

[Exterior material]
The exterior member 40 houses the wound electrode body 30 as described above. Since the exterior member 40 is in the form of a film, it has flexibility.

In particular, the exterior member 40 includes an exterior body 41 provided with the window portion 42 as described above, for example, as shown in FIGS.

(External body)
The exterior body 41 is a body of the exterior member 40 and is a film-like member. The configuration of the exterior body 41 is not particularly limited, but the exterior body 41 is, for example, a multilayer film (laminate film) including an adhesive layer.

Specifically, the exterior body 41 is, for example, a laminate film in which an adhesive layer, a metal layer, and a surface protective layer are laminated in this order from the inside. In this case, for example, the wound electrode body 30 is accommodated in the exterior member 40 by bonding the adhesive layers of the exterior body 41 to each other via the wound electrode body 30.

When the heat fusion method is used as the adhesion method, the adhesion layer is, for example, a fusion layer. This fusion layer is, for example, a film containing one or more of polymer compounds such as polyethylene and polypropylene. A metal layer is metal foil containing any 1 type or 2 types or more of metal materials, such as aluminum, for example. The surface protective layer is, for example, a film containing any one or more of polymer compounds such as nylon and polyethylene terephthalate.

Especially, it is preferable that the exterior body 41 is an aluminum laminated film in which, for example, a polyethylene film, an aluminum foil, and a nylon film are laminated in this order from the inside. This is because sufficient adhesiveness and sufficient airtightness can be obtained.

As shown in FIGS. 1 to 3, for example, the exterior body 41 includes an exterior portion 41A that is a first exterior member that covers the wound electrode body 30 from one side (here, the upper side), and the wound electrode body. The exterior part 41B which is the 2nd exterior member which coat | covers 30 from the other (here below) is included. The forming material of the exterior portion 41A and the forming material of the exterior portion 41B may be the same as each other or different from each other.

In this case, for example, in a state where the wound electrode body 30 is sandwiched between the

exterior parts

41A and 41B, a part of the exterior part 41A and a part of the exterior part 41B are bonded to each other, The wound electrode body 30 is housed inside the exterior member 40. A part of the exterior part 41A is, for example, an outer edge part of the exterior part 41A, and a part of the exterior part 41B is, for example, an outer edge part of the exterior part 41B.

Accordingly, the exterior body 41 seals the exterior member 40 and the non-adhesive region 41X where the

exterior portions

41A and 41B are not bonded to each other in order to accommodate the wound electrode body 30 inside the exterior member 40. For this reason, the

exterior portions

41A and 41B include an adhesion region 41Y where the

exterior portions

41A and 41B are adhered to each other. For example, as shown in FIG. 1 and FIG. 2, the adhesion region 41Y is an outer edge region of each of the

exterior portions

41A and 41B, and the non-adhesion region 41X is one of the

exterior portions

41A and 41B. It is an area other than the outer edge area (a central area surrounded by the outer edge area).

The

exterior parts

41A and 41B may be separated from each other or may be connected (integrated) to each other. The exterior body 41 when the

exterior portions

41A and 41B are separated from each other is, for example, two films. On the other hand, the exterior body 41 when the

exterior portions

41A and 41B are connected to each other is, for example, a single film.

Here, for example, since the

exterior portions

41A and 41B are connected to each other, the exterior body 41 is a single film. The single film may be originally a single film or a composite film in which two films are connected. Accordingly, the exterior body 41 can be folded, for example, in the direction of the arrow R shown in FIG. In this case, since the exterior body 41 is folded, as described above, the exterior portion 41A covers the wound electrode body 30 from above and the exterior portion 41B covers the wound electrode body 30 from below. The wound electrode body 30 is housed inside the exterior member 40.

Note that the exterior portion 41A is provided with, for example, a recessed portion 41P for accommodating the wound electrode body 30. Accordingly, the exterior portion 41A partially protrudes outward, for example, at a location where the recessed portion 41P is provided. The recess 41P is provided in the exterior part 41A, so that the wound electrode body 30 can be easily positioned with respect to the exterior body 41 and the wound electrode body 30 can be easily housed inside the exterior member 40. Because.

In the state where the wound electrode body 30 is housed inside the exterior member 40, for example, an adhesive film 50 is used to seal the exterior member 40. Specifically, for example, the adhesion film 50 is inserted between the exterior body 41 (the

exterior portions

41A and 41B) and the positive electrode lead 31, and the adhesion film is similarly disposed between the exterior body 41 and the negative electrode lead 32. 50 is inserted.

The adhesive film 50 includes one or more of the adhesive materials in order to prevent outside air from entering the exterior member 40. The adhesive material is a material having adhesiveness to each of the positive electrode lead 31 and the negative electrode lead 32, and is, for example, a polyolefin resin. The type of polyolefin resin is not particularly limited, and examples thereof include polyethylene, polypropylene, modified polyethylene, and modified polypropylene.

(Window)
The window portion 42 mainly functions to prevent water from entering the inside of the exterior member 40 from the outside (waterproof function) and also releases the gas generated inside the exterior member 40 to the outside ( Exhaust function). The water described here is, for example, water and water vapor existing outside the secondary battery. The gas is, for example, carbon dioxide gas (carbon dioxide) generated due to a side reaction such as a decomposition reaction of the electrolytic solution.

As described above, the window portion 42 is a part of the exterior member 40 and is exposed to each of the internal environment E1 and the external environment E2 as shown in FIG.

The internal environment E1 is an environment in which the wound electrode body 30 is housed (an environment inside the exterior member 40). For this reason, the internal environment E 1 is formed by housing the wound electrode body 30 inside the exterior member 40. On the other hand, the external environment E2 is an environment in which the wound electrode body 30 is not housed (an environment outside the exterior member 40). That is, the window 42 releases gas from the internal environment E1 to the external environment E2 while suppressing water from entering the internal environment E1 from the external environment E2.

The exterior member 40 (exterior body 41) has the window portion 42 by using the waterproof function of the window portion 42 and suppressing deterioration of cycle characteristics and the like caused by water while the window portion 42 This is to suppress the swelling of the secondary battery by utilizing the exhaust function of the secondary battery. In this case, since it is not necessary to use a machine such as a safety valve, an instrument, and an apparatus, it is possible to easily suppress the deterioration of the cycle characteristics and the like, and it is also possible to easily suppress the swelling of the secondary battery.

As long as the waterproof function and the exhaust function described above can be exhibited, the number, position, and configuration of the window 42 are not particularly limited.

Specifically, the number of window portions 42 may be only one, or two or more. Here, the number of the window parts 42 is one, for example.

Further, the position of the window 42 may be arbitrary. Here, the window part 42 is provided in the hollow part 41P of the exterior main body 41 (exterior part 41A), for example. More specifically, for example, in the case where the depression 41P has one upper surface 41PT and four side surfaces 41PS, the window 42 is provided on the upper surface 41PT.

That is, the window part 42 is provided in the non-adhesion area | region 41X of the exterior main body 41, for example.

Further, for example, an opening 41K is provided in the exterior body 41, and the window 42 is formed by covering (closing) the opening 41K with a window film 43 that is a film-like window member. That is, the window part 42 contains the window film 43 which obstruct | occludes the opening part 41K while containing the window functional material (non-porous molten fluororesin) mentioned later, for example. In each of FIG. 1 and FIG. 2, the window 43 is shaded to make it easy to identify the window film 43.

The opening 41K is a through hole that allows the internal environment E1 and the external environment E2 to communicate with each other. The opening shape of the opening 41K is not particularly limited, and may be, for example, a circle, an ellipse, a rectangle, or other shapes. Here, the opening shape of the opening 41K is, for example, an ellipse. The size (area) of the opening 41K is not particularly limited and can be arbitrarily set.

The window film 43 is a film having the above waterproof function and exhaust function. Accordingly, the window film 43 includes a window functional material. The “window functional material” is a material that can suppress the intrusion of water from the outside of the exterior member 40 to the inside and can release gas from the interior of the exterior member 40 to the outside. More specifically, the window functional material is a material that functions as a barrier film that does not allow water to sufficiently permeate in order to ensure a waterproof function, and sufficient gas such as carbon dioxide is sufficient to ensure an exhaust function. It is a gas-permeable material that can be permeated through the glass. That is, the window functional material is a material having selective permeability with respect to water and gas.

This window functional material contains any one kind or two or more kinds of non-porous molten fluororesins. This non-porous molten fluororesin is a general term for fluororesins that do not have one or two or more pores and that have a meltability enough to be melt processed and melt molded. .

The kind of the non-porous molten fluororesin is not particularly limited. For example, non-porous tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), non-porous tetrafluoroethylene / hexafluoropropylene copolymer ( FEP) and non-porous tetrafluoroethylene / ethylene copolymer (ETFE). This is because these specific types of fluorine-based polymer compounds can sufficiently exhibit the waterproof function and the exhaust function described above.

It should be noted that non-fluorine polymer compounds such as polyethylene terephthalate (PET) and polypropylene (PP) have too low permselectivity with respect to water and gas as described above compared to molten fluororesin, so that the non-fluorine-based high molecular compound. Molecular compounds cannot exhibit both the waterproof function and the exhaust function described above. Moreover, even if porous PFA, porous FEP, porous ETFE, etc. correspond to a molten fluororesin, they are porous and thus cannot exhibit both the waterproof function and the exhaust function described above.

Here, whether or not the polymer compound is non-porous can be confirmed, for example, by the following procedure. Specifically, after obtaining a polymer film, the cross section of the film is observed using an electron microscope or the like. The magnification at the time of observation can be set arbitrarily. As a result, when one or more pores are observed inside the film, the polymer compound forming the film is porous. Since the state of the pore is not particularly limited, for example, it may be a substantially circular gap or a tubular path extending in a predetermined direction. On the other hand, when one or more pores are not observed inside the film, the polymer compound forming the film is non-porous.

The planar shape of the window film 43 is not particularly limited, and may be, for example, a circle, an ellipse, a rectangle, or other shapes. That is, the planar shape of the window film 43 may be the same as the opening shape of the opening 41K, or may be a shape different from the opening shape of the opening 41K. Here, the planar shape of the window film 43 is the same as the opening shape of the opening 41K, for example. For this reason, the planar shape of the window film 43 is an ellipse, for example.

As long as the window film 43 can block the opening 41K, the size (area) of the window film 43 is not particularly limited. That is, the area of the window film 43 may be the same as the opening area of the opening 41K or may be larger than the opening area of the opening 41K.

Especially, it is preferable that the area of the window film 43 is larger than the area of the opening 41K because the window film 43 contains the window functional material (non-porous molten fluororesin). This is because the window film 43 can be attached to the exterior body 41 using an adhesive in order to fix the window film 43 to the exterior body 41.

Specifically, for example, as shown in FIG. 3, since the area of the window film 43 is larger than the area of the opening 41K, the window film 43 is adhesive so as to close the opening 41K. 44 is affixed to the exterior body 41 via 44. The window film 43 containing a non-porous molten fluororesin generally has another object (here, the exterior main body 41) due to the adhesion resistance unique to the non-porous molten fluororesin. It has a property that it is difficult to adhere to. However, by selecting the adhesive 44 excellent in compatibility (adhesiveness) with the non-porous molten fluororesin, the window film 43 can be sufficiently adhered to the exterior body 41 using the adhesive 44. .

The installation position of the window film 43 is not particularly limited. For this reason, the window film 43 may be disposed inside the exterior body 41 (internal environment E1), or may be disposed outside the exterior body 41 (external environment E2).

In particular, as shown in FIG. 3, the window film 43 is preferably disposed inside the exterior body 41. This is because, even if gas is generated inside the secondary battery, the window film 43 is prevented from unintentionally peeling and dropping. The window film 43 is bonded to the inner surface of the exterior body 41 through an adhesive 44, for example.

Specifically, when gas is generated inside the secondary battery, the window film 43 is pushed from the internal environment E1 toward the external environment E2 due to an increase in internal pressure. In this case, for example, as will be described later, when the window film 43 is disposed outside the exterior body 41 (see FIG. 6), the window film 43 is positioned in the external environment E2 from the beginning, and the window There is nothing on the outside of the film 43. Therefore, depending on how the internal pressure increases, when the adhesive 44 peels from one or both of the exterior body 41 and the window film 43, the window film 43 may peel from the exterior body 41. Moreover, if the window film 43 peels from the exterior body 41, the window film 43 may fall off from the secondary battery.

On the other hand, when the window film 43 is disposed inside the exterior body 41 (see FIG. 3), the window film 43 is located in the internal environment E1, and the exterior body 41 is located outside the window film 43. Existing. In this case, the window film 43 is pressed by the exterior body 41 so as to remain in the internal environment E 1 at a place where the window film 43 and the exterior body 41 overlap each other. Therefore, the adhesive 44 is difficult to peel from each of the exterior body 41 and the window film 43, and thus the window film 43 is difficult to peel from the exterior body 41. In addition, even if the window film 43 is peeled off from the exterior body 41 due to an increase in internal pressure, the window film 43 still tends to be present in the internal environment E1, and thus the window film 43 is difficult to drop off from the secondary battery. Become.

The thickness of the window film 43 is not particularly limited, but is, for example, 10 μm to 500 μm, and preferably 10 μm to 200 μm. By using the window film 43 containing a window functional material (non-porous molten fluororesin), a sufficient waterproof function and a sufficient exhaust function can be obtained while ensuring the physical durability of the window film 43. is there.

Specifically, if the thickness of the window film 43 is smaller than 10 μm, the window film 43 is too thin, so that the window film 43 tends to release the gas when the gas is generated. The window film 43 may be easily deformed, broken, and peeled when the internal pressure is increased. On the other hand, if the thickness of the window film 43 is larger than 500 μm, the window film 43 is too thick, so that the window film 43 is difficult to be deformed, broken and peeled even when the internal pressure is increased. While it is difficult for water to pass through, the window film 43 may be difficult to release gas.

The adhesive 44 contains any one kind or two or more kinds of polymer compounds (adhesive material) such as polyolefin resin, epoxy resin, urethane resin, cyanoacrylate and styrene butadiene rubber, for example. The polyolefin resin is, for example, polypropylene (PP).

Since the state of the adhesive 44 before bonding is not particularly limited, it may be powder, liquid, film, or a mixture of two or more of them. However, in order to make the thickness of the adhesive 44 uniform and to suppress the occurrence of pinholes in the adhesive 44, the state of the adhesive 44 before bonding is liquid or film-like. One or both are preferred.

In addition, when the adhesiveness of the adhesive agent 44 and the window film 43 is not enough, in order to improve the adhesiveness, for example, in order to improve the adhesiveness, any one kind or two or more kinds of the pre-treatment is applied to the surface of the window film 43. May be given. Although the kind of this pre-processing is not specifically limited, For example, they are a chemical | medical agent process, a corona treatment, and an ultraviolet irradiation (UV) process. Among these, chemical treatment is preferable. This is because the adhesion between the window film 43 and the adhesive 44 can be easily improved without using equipment such as a heat source and a light source.

Of course, even when the adhesiveness between the adhesive 44 and the exterior body 41 is not sufficient, for example, in order to improve the adhesiveness as in the case where the adhesiveness between the adhesive 44 and the window film 43 is not sufficient. Further, any one type or two or more types of pretreatments may be applied to the surface of the exterior body 41. Details regarding the preprocessing are as described above, for example.

[Positive electrode]
For example, as shown in FIG. 4, the positive electrode 33 includes a positive electrode current collector 33A and positive electrode active material layers 33B provided on both surfaces of the positive electrode current collector 33A. However, the positive electrode active material layer 33B may be provided only on one surface of the positive electrode current collector 33A.

The positive electrode current collector 33A includes, for example, any one type or two or more types of conductive materials. Although the kind of conductive material is not specifically limited, For example, they are metal materials, such as aluminum, nickel, and stainless steel. The positive electrode current collector 33A may be a single layer or a multilayer.

The positive electrode active material layer 33B contains any one or more of positive electrode materials capable of occluding and releasing lithium as a positive electrode active material. However, the positive electrode active material layer 33B may further include any one type or two or more types of other materials such as a positive electrode binder and a positive electrode conductive agent.

The positive electrode material is preferably a lithium-containing compound, and more specifically, preferably one or both of a lithium-containing composite oxide and a lithium-containing phosphate compound. This is because a high energy density can be obtained.

The lithium-containing composite oxide is an oxide containing lithium and one or more kinds of other elements (elements other than lithium) as constituent elements. For example, any one of a layered rock salt type and a spinel type It has a crystal structure. The lithium-containing phosphate compound is a phosphate compound containing lithium and one or more other elements as constituent elements, and has, for example, an olivine type crystal structure.

The type of other element is not particularly limited as long as it is any one or more of arbitrary elements. Among them, the other elements are preferably any one or more of elements belonging to Groups 2 to 15 in the long-period periodic table. More specifically, it is more preferable that the other elements include one or more metal elements of nickel (Ni), cobalt (Co), manganese (Mn), and iron (Fe). preferable. This is because a high voltage can be obtained.

Examples of the lithium-containing composite oxide having a layered rock salt type crystal structure include compounds represented by the following formulas (21) to (23).

_{_{Li a Mn (1-bc)}} Ni b M11 c O (2-d) F e ··· (21)
(M11 is cobalt (Co), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), zirconium (Zr), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), and tungsten (W), a to e being 0.8 ≦ a ≦ 1.2, 0 <b <0.5, 0 ≦ c ≦ 0.5, (b + c) <1, −0.1 ≦ d ≦ 0.2 and 0 ≦ e ≦ 0.1 are satisfied. However, the composition of lithium varies depending on the charge / discharge state, and a is the value of the fully discharged state.)

Li _a Ni _(1-b) M12 _b O _(2-c) F _d (22)
(M12 is cobalt (Co), manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), and tungsten (W), and a to d are 0.8. ≦ a ≦ 1.2, 0.005 ≦ b ≦ 0.5, −0.1 ≦ c ≦ 0.2 and 0 ≦ d ≦ 0.1, provided that the composition of lithium depends on the charge / discharge state Unlikely, a is the value of the fully discharged state.)

Li _a Co _(1-b) M13 _b O _(2-c) F _d (23)
(M13 is nickel (Ni), manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), and tungsten (W), and a to d are 0.8. ≦ a ≦ 1.2, 0 ≦ b <0.5, −0.1 ≦ c ≦ 0.2 and 0 ≦ d ≦ 0.1, provided that the composition of lithium varies depending on the charge / discharge state, a is the value of the fully discharged state.)

The lithium-containing composite oxide having a layered rock salt type crystal structure may be, for example, a compound represented by the following formula (24). This compound is a lithium nickel-containing composite oxide containing nickel as a constituent element and having a relatively high nickel content.

_{_{_{_{Li x Co y Ni z M 1}}}} -yz O ba X e ··· (24)
(M is boron (B), magnesium (Mg), aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), gallium (Ga), yttrium (Y), zirconium (Zr), molybdenum (Mo), strontium (Sr), cesium (Cs), barium (Ba), indium (In), and antimony (Sb), and X is a halogen element, x, y, z , A and b are 0.8 <x ≦ 1.2, 0 ≦ y ≦ 1.0, 0.5 ≦ z ≦ 1.0, 0 ≦ a ≦ 1.0, 1.8 ≦ b ≦ 2. 2 and y <z are satisfied.)

Specific examples of the lithium-containing composite oxide having a layered rock salt type crystal structure are LiNiO ₂ , LiCoO ₂ , LiCo _0.98 Al _0.01 Mg _0.01 O ₂ , LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , LiNi _0.8 Co _0.15 Al _0.05 O _2. LiNi _0.33 Co _0.33 Mn _0.33 O ₂ , Li _1.2 Mn _0.52 Co _0.175 Ni _0.1 O ₂ and Li _1.15 (Mn _0.65 Ni _0.22 Co _0.13 ) O ₂ .

When the lithium-containing composite oxide having a layered rock salt type crystal structure contains nickel, cobalt, manganese, and aluminum as constituent elements, the atomic ratio of nickel is preferably 50 atomic% or more. This is because a high energy density can be obtained.

The lithium-containing composite oxide having a spinel crystal structure is, for example, a compound represented by the following formula (25).

Li _a Mn _(2-b) M14 _b O _c F _d (25)
(M14 is cobalt (Co), nickel (Ni), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper At least one of (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), and tungsten (W), wherein a to d are 0.9. ≦ a ≦ 1.1, 0 ≦ b ≦ 0.6, 3.7 ≦ c ≦ 4.1 and 0 ≦ d ≦ 0.1, provided that the composition of lithium differs depending on the charge / discharge state, and a Is the value of the fully discharged state.)

Specific examples of the lithium-containing composite oxide having a spinel crystal structure include LiMn ₂ O ₄ .

Examples of the lithium-containing phosphate compound having an olivine type crystal structure include a compound represented by the following formula (26).

Li _a M15PO ₄ (26)
(M15 is cobalt (Co), manganese (Mn), iron (Fe), nickel (Ni), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), niobium It is at least one of (Nb), copper (Cu), zinc (Zn), molybdenum (Mo), calcium (Ca), strontium (Sr), tungsten (W), and zirconium (Zr). 0.9 ≦ a ≦ 1.1, where the composition of lithium varies depending on the charge / discharge state, and a is the value of the complete discharge state.)

Specific examples of the lithium-containing phosphate compound having an olivine type crystal structure include LiFePO ₄ , LiMnPO ₄ , LiFe _0.5 Mn _0.5 PO _4, and LiFe _0.3 Mn _0.7 PO ₄ .

The lithium-containing composite oxide may be a compound represented by the following formula (27).

(Li ₂ MnO ₃ ) _x (LiMnO ₂ ) _1-x (27)
(X satisfies 0 ≦ x ≦ 1, where the composition of lithium varies depending on the charge / discharge state, and x is the value of the complete discharge state.)

In addition, the positive electrode material may be any one kind or two or more kinds of oxides, disulfides, chalcogenides, conductive polymers, and the like. Examples of the oxide include titanium oxide, vanadium oxide, and manganese dioxide. Examples of the disulfide include titanium disulfide and molybdenum sulfide. An example of the chalcogenide is niobium selenide. Examples of the conductive polymer include sulfur, polyaniline, and polythiophene. However, the positive electrode material may be a material other than the above.

The positive electrode binder contains, for example, any one or more of synthetic rubber and polymer compound. Examples of the synthetic rubber include styrene butadiene rubber, fluorine rubber, and ethylene propylene diene. Examples of the polymer compound include polyvinylidene fluoride and polyimide.

The positive electrode conductive agent includes, for example, one or more of carbon materials. Examples of the carbon material include graphite, carbon black, acetylene black, and ketjen black. However, the positive electrode conductive agent may be a metal material or a conductive polymer as long as it is a conductive material.

[Negative electrode]
For example, as shown in FIG. 4, the negative electrode 22 includes a negative electrode current collector 34A and negative electrode active material layers 34B provided on both surfaces of the negative electrode current collector 34A. However, the negative electrode active material layer 34B may be provided only on one surface of the negative electrode current collector 34A.

The negative electrode current collector 34A includes, for example, any one type or two or more types of conductive materials. Although the kind of electrically conductive material is not specifically limited, For example, they are metal materials, such as copper, aluminum, nickel, and stainless steel. The negative electrode current collector 34A may be a single layer or a multilayer.

The surface of the negative electrode current collector 34A is preferably roughened. This is because the adhesion of the negative electrode active material layer 34B to the negative electrode current collector 34A is improved by a so-called anchor effect. In this case, the surface of the negative electrode current collector 34A only needs to be roughened at least in a region facing the negative electrode active material layer 34B. The roughening method is, for example, a method of forming fine particles using electrolytic treatment. In the electrolytic treatment, fine particles are formed on the surface of the negative electrode current collector 34A by an electrolysis method in an electrolytic bath, so that the surface of the negative electrode current collector 34A is provided with irregularities. A copper foil produced by an electrolytic method is generally called an electrolytic copper foil.

The negative electrode active material layer 34B contains any one or more of negative electrode materials capable of occluding and releasing lithium as a negative electrode active material. However, the negative electrode active material layer 34B may further include any one kind or two or more kinds of other materials such as a negative electrode binder and a negative electrode conductive agent.

In order to prevent unintentional deposition of lithium metal on the negative electrode 34 during charging, the chargeable capacity of the negative electrode material is preferably larger than the discharge capacity of the positive electrode 33. That is, the electrochemical equivalent of the negative electrode material capable of occluding and releasing lithium is preferably larger than the electrochemical equivalent of the positive electrode 33.

The negative electrode material is, for example, one or more of carbon materials. This is because the change in crystal structure at the time of occlusion and release of lithium is very small, so that a high energy density can be obtained stably. Moreover, since the carbon material also functions as a negative electrode conductive agent, the conductivity of the negative electrode active material layer 34B is improved.

Examples of the carbon material include graphitizable carbon, non-graphitizable carbon, and graphite. However, the interplanar spacing of the (002) plane in non-graphitizable carbon is preferably 0.37 nm or more, and the interplanar spacing of the (002) plane in graphite is preferably 0.34 nm or less. More specifically, examples of the carbon material include pyrolytic carbons, cokes, glassy carbon fibers, organic polymer compound fired bodies, activated carbon, and carbon blacks. The cokes include pitch coke, needle coke, petroleum coke and the like. The organic polymer compound fired body is obtained by firing (carbonizing) a polymer compound such as a phenol resin and a furan resin at an appropriate temperature. In addition, the carbon material may be low crystalline carbon heat-treated at a temperature of about 1000 ° C. or less, or may be amorphous carbon. The shape of the carbon material may be any of a fibrous shape, a spherical shape, a granular shape, and a scale shape.

Further, the negative electrode material is, for example, a material (metal material) containing any one or more of metal elements and metalloid elements as constituent elements. This is because a high energy density can be obtained.

The metal-based material may be any of a simple substance, an alloy, and a compound, or may be two or more of them, or may be a material having at least a part of one or two or more of them. . However, the alloy includes a material including one or more metal elements and one or more metalloid elements in addition to a material composed of two or more metal elements. The alloy may contain a nonmetallic element. The structure of the metal-based material is, for example, a solid solution, a eutectic (eutectic mixture), an intermetallic compound, and two or more kinds of coexisting materials.

The metal element and metalloid element described above are, for example, any one or more metal elements and metalloid elements capable of forming an alloy with lithium. Specifically, for example, magnesium (Mg), boron (B), aluminum (Al), gallium (Ga), indium (In), silicon (Si), germanium (Ge), tin (Sn), lead (Pb) ), Bismuth (Bi), cadmium (Cd), silver (Ag), zinc, hafnium (Hf), zirconium, yttrium (Y), palladium (Pd) and platinum (Pt).

Among these, one or both of silicon and tin is preferable. This is because the ability to occlude and release lithium is excellent, so that a significantly high energy density can be obtained.

The material containing one or both of silicon and tin as a constituent element may be any of a simple substance, an alloy, and a compound of silicon, or any of a simple substance, an alloy, and a compound of tin. These may be two or more types, or may be a material having at least a part of one or two or more of them. The simple substance described here means a simple substance (which may contain a small amount of impurities) in a general sense, and does not necessarily mean 100% purity.

The alloy of silicon is, for example, any one of tin, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony, chromium and the like as a constituent element other than silicon or Includes two or more. The compound of silicon contains, for example, one or more of carbon and oxygen as constituent elements other than silicon. In addition, the compound of silicon may contain any 1 type or 2 types or more of the series of elements demonstrated regarding the alloy of silicon as structural elements other than silicon, for example.

Specific examples of silicon alloys and silicon compounds are SiB ₄ , SiB ₆ , Mg ₂ Si, Ni ₂ Si, TiSi ₂ , MoSi ₂ , CoSi ₂ , NiSi ₂ , CaSi ₂ , CrSi ₂ , Cu ₅ Si, FeSi ₂ , MnSi ₂ , NbSi ₂ , TaSi ₂ , VSi ₂ , WSi ₂ , ZnSi ₂ , SiC, Si ₃ N ₄ , Si ₂ N ₂ O, SiO _v (0 <v ≦ 2), and LiSiO. Note that _v in SiO _v may be 0.2 <v <1.4.

The alloy of tin, for example, as a constituent element other than tin, any one of silicon, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony, chromium, etc. Includes two or more. The tin compound contains, for example, one or more of carbon and oxygen as constituent elements other than tin. In addition, the compound of tin may contain any 1 type in the series of elements demonstrated regarding the alloy of tin, or 2 or more types as structural elements other than tin, for example.

Specific examples of the tin alloy and the tin compound include SnO _w (0 <w ≦ 2), SnSiO ₃ , LiSnO, and Mg ₂ Sn.

Particularly, the material containing tin as a constituent element is preferably, for example, a material (Sn-containing material) containing a second constituent element and a third constituent element together with tin which is the first constituent element. The second constituent element is, for example, cobalt, iron, magnesium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, gallium, zirconium, niobium, molybdenum, silver, indium, cesium (Ce), hafnium (Hf), Any one or more of tantalum, tungsten, bismuth, silicon and the like are included. The third constituent element includes, for example, one or more of boron, carbon, aluminum, phosphorus, and the like. This is because, when the Sn-containing material contains the second and third constituent elements, a high battery capacity and excellent cycle characteristics can be obtained.

In particular, the Sn-containing material is preferably a material (SnCoC-containing material) containing tin, cobalt, and carbon as constituent elements. In this SnCoC-containing material, for example, the carbon content is 9.9 mass% to 29.7 mass%, and the ratio of the content of tin and cobalt (Co / (Sn + Co)) is 20 mass% to 70 mass%. . This is because a high energy density can be obtained.

The SnCoC-containing material has a phase containing tin, cobalt, and carbon, and the phase is preferably low crystalline or amorphous. Since this phase is a reaction phase capable of reacting with lithium, excellent characteristics can be obtained based on the presence of the reaction phase. The half-width (diffraction angle 2θ) of the diffraction peak obtained by X-ray diffraction of this reaction phase is 1 ° or more when CuKα ray is used as the specific X-ray and the insertion speed is 1 ° / min. Is preferred. This is because lithium is occluded and released more smoothly and the reactivity with the electrolytic solution is reduced. In addition, the SnCoC-containing material may include a phase containing a simple substance or a part of each constituent element in addition to the low crystalline or amorphous phase.

Whether or not the diffraction peak obtained by X-ray diffraction corresponds to a reaction phase capable of reacting with lithium can be easily determined by comparing X-ray diffraction charts before and after electrochemical reaction with lithium. For example, if the position of the diffraction peak changes before and after the electrochemical reaction with lithium, it corresponds to a reaction phase capable of reacting with lithium. In this case, for example, a diffraction peak of a low crystalline or amorphous reaction phase is observed between 2θ = 20 ° and 50 °. Such a reaction phase contains, for example, each of the above-described constituent elements, and is considered to be low crystallized or amorphous mainly due to the presence of carbon.

In the SnCoC-containing material, it is preferable that at least a part of carbon as a constituent element is bonded to a metal element or a metalloid element as another constituent element. This is because aggregation or crystallization of tin or the like is suppressed. The bonding state of the elements can be confirmed using, for example, X-ray photoelectron spectroscopy (XPS). In a commercially available apparatus, for example, Al—Kα ray or Mg—Kα ray is used as the soft X-ray. When at least a part of carbon is bonded to a metal element, a metalloid element, or the like, the peak of the synthetic wave of carbon 1s orbital (C1s) appears in a region lower than 284.5 eV. It is assumed that the energy calibration is performed so that the peak of the 4f orbit (Au4f) of the gold atom is obtained at 84.0 eV. At this time, since surface-contaminated carbon is usually present on the surface of the substance, the C1s peak of the surface-contaminated carbon is set to 284.8 eV, and the peak is used as an energy reference. In the XPS measurement, the waveform of the C1s peak is obtained in a form including the surface contamination carbon peak and the carbon peak in the SnCoC-containing material. For this reason, for example, both peaks are separated by analyzing using commercially available software. In the waveform analysis, the position of the main peak existing on the lowest bound energy side is used as the energy reference (284.8 eV).

This SnCoC-containing material is not limited to a material (SnCoC) whose constituent elements are only tin, cobalt and carbon. This SnCoC-containing material is, for example, any one of silicon, iron, nickel, chromium, indium, niobium, germanium, titanium, molybdenum, aluminum, phosphorus, gallium, and bismuth in addition to tin, cobalt, and carbon One kind or two or more kinds may be included as constituent elements.

In addition to SnCoC-containing materials, materials containing tin, cobalt, iron and carbon as constituent elements (SnCoFeC-containing materials) are also preferable. The composition of the SnCoFeC-containing material is arbitrary. For example, when the iron content is set to be small, the carbon content is 9.9 mass% to 29.7 mass%, and the iron content is 0.3 mass% to 5.9 mass%. The content ratio of tin and cobalt (Co / (Sn + Co)) is 30% by mass to 70% by mass. Further, when the iron content is set to be large, the carbon content is 11.9% to 29.7% by mass, and the ratio of the content of tin, cobalt and iron ((Co + Fe) / (Sn + Co + Fe)) Is 26.4% by mass to 48.5% by mass, and the content ratio of cobalt and iron (Co / (Co + Fe)) is 9.9% by mass to 79.5% by mass. This is because a high energy density can be obtained in such a composition range. Note that the physical properties (half-value width, etc.) of the SnCoFeC-containing material are the same as the above-described physical properties of the SnCoC-containing material.

In addition, the negative electrode material may be any one kind or two or more kinds of metal oxides and polymer compounds, for example. Examples of the metal oxide include iron oxide, ruthenium oxide, and molybdenum oxide. Examples of the polymer compound include polyacetylene, polyaniline, and polypyrrole.

Among these, the negative electrode material preferably contains both a carbon material and a metal-based material for the following reasons.

Metal materials, in particular, materials containing one or both of silicon and tin as constituent elements have the advantage of high theoretical capacity, but they have a concern that they tend to violently expand and contract during charging and discharging. On the other hand, the carbon material has a concern that the theoretical capacity is low, but has an advantage that it is difficult to expand and contract during charging and discharging. Therefore, by using both a carbon material and a metal-based material, expansion and contraction during charging and discharging are suppressed while obtaining a high theoretical capacity (in other words, battery capacity).

The negative electrode active material layer 34B is formed by any one method or two or more methods among, for example, a coating method, a gas phase method, a liquid phase method, a thermal spray method, and a firing method (sintering method). The coating method is, for example, a method in which a particle (powder) negative electrode active material is mixed with a negative electrode binder and the mixture is dispersed in an organic solvent and then applied to the negative electrode current collector 34A. Examples of the vapor phase method include a physical deposition method and a chemical deposition method. More specifically, for example, a vacuum deposition method, a sputtering method, an ion plating method, a laser ablation method, a thermal chemical vapor deposition, a chemical vapor deposition (CVD) method, and a plasma chemical vapor deposition method. Examples of the liquid phase method include an electrolytic plating method and an electroless plating method. The thermal spraying method is a method of spraying a molten or semi-molten negative electrode active material onto the negative electrode current collector 34A. The firing method is, for example, a method in which a mixture dispersed in an organic solvent or the like is applied to the negative electrode current collector 34A using a coating method, and then heat-treated at a temperature higher than the melting point of the negative electrode binder or the like. As the firing method, for example, an atmosphere firing method, a reaction firing method, a hot press firing method, or the like can be used.

In this secondary battery, as described above, in order to prevent unintentional precipitation of lithium on the negative electrode 34 during charging, the electrochemical equivalent of the negative electrode material capable of inserting and extracting lithium is , Greater than the electrochemical equivalent of the positive electrode. In addition, when the open circuit voltage at the time of full charge (that is, the battery voltage) is 4.25 V or higher, the same positive electrode active material is used compared to the case where the open circuit voltage at the time of full charge is 4.20 V. However, since the amount of lithium released per unit mass increases, the amounts of the positive electrode active material and the negative electrode active material are adjusted accordingly. Thereby, a high energy density is obtained.

The open circuit voltage (charge end voltage) at the time of full charge is not particularly limited, but is preferably 4.2 V or more as described above. Especially, it is preferable that it is 4.25V or more at the time of complete charge, and it is more preferable that it is 4.35V or more. This is because even if the open circuit voltage at the time of full charge is remarkably increased, an advantage based on the optimization of the mixing ratio of the electrolyte salt and ethylene carbonate can be obtained, so that excellent battery characteristics can be obtained. In addition, although the discharge end voltage is not specifically limited, For example, it is 3.0 V or less.

[Separator]
For example, as illustrated in FIG. 4, the separator 35 is disposed between the positive electrode 33 and the negative electrode 34. Thereby, the separator 35 mainly separates the positive electrode 33 and the negative electrode 34 and allows lithium ions to pass through while preventing a short circuit of current due to contact between the two electrodes.

The separator 35 is, for example, one kind or two or more kinds of porous films such as synthetic resin and ceramic, and may be a laminated film of two or more kinds of porous films. Examples of the synthetic resin include polytetrafluoroethylene, polypropylene, and polyethylene.

In particular, the separator 35 may include, for example, the above-described porous film (base material layer) and a polymer compound layer provided on one or both surfaces of the base material layer. This is because the adhesion of the separator 35 to each of the positive electrode 33 and the negative electrode 34 is improved, so that the distortion of the wound electrode body 30 is suppressed. As a result, the decomposition reaction of the electrolytic solution is suppressed, and the leakage of the electrolytic solution impregnated in the base material layer is also suppressed. Swelling is suppressed.

The polymer compound layer contains any one kind or two or more kinds of polymer compounds such as polyvinylidene fluoride. This is because it has excellent physical strength and is electrochemically stable. However, the polymer compound is not limited to polyvinylidene fluoride. When forming this polymer compound layer, for example, after applying a solution in which the polymer compound is dissolved in an organic solvent or the like to the substrate layer, the substrate layer is dried. Moreover, when forming a polymeric compound layer, after immersing a base material layer in a solution, you may dry the base material layer, for example. This polymer compound layer may contain any one kind or two or more kinds of insulating particles such as inorganic particles. Examples of the inorganic particles include aluminum oxide, aluminum nitride, boehmite, and talc.

[Electrolyte layer]
The electrolyte layer 36 contains an electrolytic solution and a polymer compound. The electrolyte layer 36 described here is a so-called gel electrolyte, and an electrolyte solution is held in the electrolyte layer 36 by a polymer compound. This is because high ionic conductivity (for example, 1 mS / cm or more at room temperature) is obtained and leakage of the electrolytic solution is prevented. The electrolyte layer 36 may further include any one kind or two or more kinds of other materials such as additives.

The electrolytic solution contains a solvent and an electrolyte salt. However, the electrolytic solution may further include any one or more of other materials such as additives.

(solvent)
The solvent contains any one or more of nonaqueous solvents such as organic solvents. The electrolytic solution containing the nonaqueous solvent is a so-called nonaqueous electrolytic solution.

Examples of the non-aqueous solvent include cyclic carbonate ester, chain carbonate ester, lactone, chain carboxylate ester, and nitrile (mononitrile). This is because excellent battery capacity, cycle characteristics, storage characteristics, and the like can be obtained.

The cyclic carbonate is, for example, ethylene carbonate, propylene carbonate, butylene carbonate, or the like. Examples of the chain ester carbonate include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and methyl propyl carbonate. Examples of the lactone include γ-butyrolactone and γ-valerolactone. Examples of the chain carboxylic acid ester include methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethyl acetate, and ethyl trimethyl acetate. Nitriles are, for example, acetonitrile, methoxyacetonitrile, 3-methoxypropionitrile and the like.

Other non-aqueous solvents include, for example, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1 , 4-dioxane, N, N-dimethylformamide, N-methylpyrrolidinone, N-methyloxazolidinone, N, N′-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane, trimethyl phosphate and dimethyl sulfoxide. This is because similar advantages can be obtained.

Among them, the solvent preferably contains one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. This is because high battery capacity, excellent cycle characteristics, and excellent storage characteristics can be obtained. In this case, high viscosity (high dielectric constant) solvents such as ethylene carbonate and propylene carbonate (for example, dielectric constant ε ≧ 30) and low viscosity solvents such as dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate (for example, viscosity ≦ 1 mPas). -A combination with s) is more preferred. This is because the dissociation property of the electrolyte salt and the ion mobility are improved.

In particular, the solvent includes unsaturated cyclic carbonates, halogenated carbonates, sulfonate esters, acid anhydrides, dicyano compounds (dinitrile compounds), diisocyanate compounds, phosphate esters, and chain compounds having a carbon-carbon triple bond. Any one kind or two kinds or more may be included. This is because the chemical stability of the electrolytic solution is improved.

The unsaturated cyclic carbonate is a cyclic carbonate containing one or more unsaturated bonds (carbon-carbon double bond or carbon-carbon triple bond). Examples of the unsaturated cyclic carbonate include vinylene carbonate, vinyl ethylene carbonate, and methylene ethylene carbonate. The content of the unsaturated cyclic carbonate in the solvent is not particularly limited, but is, for example, 0.01% by weight to 10% by weight.

The halogenated carbonate is a cyclic or chain carbonate containing one or more halogens as a constituent element. When the halogenated carbonate contains two or more halogens as constituent elements, the number of the two or more halogens may be only one or two or more. Examples of cyclic halogenated carbonates include 4-fluoro-1,3-dioxolan-2-one and 4,5-difluoro-1,3-dioxolan-2-one. Examples of the chain halogenated carbonate include fluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, and difluoromethyl methyl carbonate. The content of the halogenated carbonate in the solvent is not particularly limited, but is, for example, 0.01% by weight to 50% by weight.

Examples of the sulfonate ester include a monosulfonate ester and a disulfonate ester. The content of the sulfonic acid ester in the solvent is not particularly limited, but is, for example, 0.01% by weight to 10% by weight.

The monosulfonic acid ester may be a cyclic monosulfonic acid ester or a chain monosulfonic acid ester. Cyclic monosulfonates are, for example, sultone such as 1,3-propane sultone and 1,3-propene sultone. The chain monosulfonic acid ester is, for example, a compound in which a cyclic monosulfonic acid ester is cleaved on the way. The disulfonic acid ester may be a cyclic disulfonic acid ester or a chain disulfonic acid ester.

Examples of the acid anhydride include carboxylic acid anhydride, disulfonic acid anhydride, and carboxylic acid sulfonic acid anhydride. Examples of the carboxylic acid anhydride include succinic anhydride, glutaric anhydride, and maleic anhydride. Examples of the disulfonic anhydride include ethanedisulfonic anhydride and propanedisulfonic anhydride. Examples of the carboxylic acid sulfonic acid anhydride include anhydrous sulfobenzoic acid, anhydrous sulfopropionic acid, and anhydrous sulfobutyric acid. The content of the acid anhydride in the solvent is not particularly limited, but is, for example, 0.5% by weight to 5% by weight.

The dinitrile compound is, for example, a compound represented by NC—C _m H _2m —CN (m is an integer of 1 or more). This dinitrile compound includes, for example, succinonitrile (NC-C ₂ H ₄ -CN), glutaronitrile (NC-C ₃ H ₆ -CN), adiponitrile (NC-C ₄ H ₈ -CN) and phthalonitrile ( NC-C ₆ H ₄ -CN). The content of the dinitrile compound in the solvent is not particularly limited, but is, for example, 0.5% by weight to 5% by weight.

The diisocyanate compound is, for example, a compound represented by OCN—C _n H _2n —NCO (n is an integer of 1 or more). This diisocyanate compound is, for example, hexamethylene diisocyanate (OCN—C ₆ H ₁₂ —NCO). The content of the diisocyanate compound in the solvent is not particularly limited and is, for example, 0.5% by weight to 5% by weight.

Examples of the phosphate ester include trimethyl phosphate and triethyl phosphate. The content of the phosphate ester in the solvent is not particularly limited, and is, for example, 0.5% by weight to 5% by weight.

A chain compound having a carbon-carbon triple bond is a chain compound having one or more carbon-carbon triple bonds (—C≡C—). Examples of the chain compound having a carbon-carbon triple bond include propargylmethyl carbonate (CH≡C—CH ₂ —O—C (═O) —O—CH ₃ ) and propargyl methylsulfonate (CH≡C—CH _2). _{-O-S (= O) 2} -CH 3) , and the like. The content of the chain compound having a carbon-carbon triple bond in the solvent is not particularly limited, but is, for example, 0.5% by weight to 5% by weight.

(Electrolyte salt)
The electrolyte salt includes, for example, any one kind or two or more kinds of salts such as a lithium salt. However, the electrolyte salt may contain a salt other than the lithium salt, for example. Examples of the salt other than lithium include salts of light metals other than lithium.

Examples of the lithium salt include lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), and tetraphenyl. Lithium borate (LiB (C ₆ H ₅ ) ₄ ), lithium methanesulfonate (LiCH ₃ SO ₃ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ), lithium tetrachloroaluminate (LiAlCl ₄ ), hexafluoride Examples include dilithium silicate (Li ₂ SiF ₆ ), lithium chloride (LiCl), and lithium bromide (LiBr). This is because excellent battery capacity, cycle characteristics, storage characteristics, and the like can be obtained.

Among them, one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate and lithium hexafluoroarsenate are preferable, and lithium hexafluorophosphate is more preferable. . This is because a higher effect can be obtained because the internal resistance is lowered.

The content of the electrolyte salt is not particularly limited, but is preferably 0.3 mol / kg to 3.0 mol / kg with respect to the solvent. This is because high ionic conductivity is obtained.

However, in the electrolyte layer 36 which is a gel electrolyte, the solvent contained in the electrolytic solution is a wide concept including not only a liquid material but also a material having ion conductivity capable of dissociating the electrolyte salt. . Therefore, when using a polymer compound having ion conductivity, the polymer compound is also included in the non-aqueous solvent.

Examples of the polymer compound include polyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, polysiloxane, polyvinyl fluoride, polyvinyl acetate, polyvinyl alcohol, polymethacryl. It includes any one or more of methyl acid, polyacrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene and polycarbonate. In addition, the polymer compound may be a copolymer. This copolymer is, for example, a copolymer of vinylidene fluoride and hexafluoropyrene. Among these, as the homopolymer, polyvinylidene fluoride is preferable, and as the copolymer, a copolymer of vinylidene fluoride and hexafluoropyrene is preferable. This is because it is electrochemically stable.

In addition, it may replace with the electrolyte layer 36 and electrolyte solution may be used as it is. In this case, the wound electrode body 30 is impregnated with the electrolytic solution.

[Operation]
This secondary battery operates as follows, for example.

At the time of charging, lithium ions are released from the positive electrode 33 and the lithium ions are occluded in the negative electrode 34 through the electrolyte layer 36. On the other hand, during discharge, lithium ions are released from the negative electrode 34 and the lithium ions are occluded in the positive electrode 33 through the electrolyte layer 36.

[Production method]
The secondary battery provided with the gel electrolyte layer 36 is manufactured, for example, by the following three types of procedures.

(First procedure)
When the positive electrode 33 is produced, first, a positive electrode active material and, if necessary, a positive electrode binder and a positive electrode conductive agent are mixed to obtain a positive electrode mixture. Subsequently, a positive electrode mixture slurry is obtained by dispersing the positive electrode mixture in an organic solvent or the like. Subsequently, after the positive electrode mixture slurry is applied to both surfaces of the positive electrode current collector 33A, the positive electrode mixture slurry is dried to form the positive electrode active material layer 33B. Finally, the positive electrode active material layer 33B is compression molded using a roll press or the like while heating the positive electrode active material layer 33B as necessary. In this case, compression molding may be repeated a plurality of times.

When producing the negative electrode 34, the negative electrode active material layer 34B is formed on both surfaces of the negative electrode current collector 34A by the same procedure as that of the positive electrode 33 described above. Specifically, first, by mixing a negative electrode active material, a negative positive electrode binder, a negative electrode conductive agent, and the like to form a negative electrode mixture, by dispersing the negative electrode mixture in an organic solvent, A paste-like negative electrode mixture slurry is obtained. Subsequently, after applying the negative electrode mixture slurry to both surfaces of the negative electrode current collector 34A, the negative electrode mixture slurry is dried to form the negative electrode active material layer 34B. Finally, the negative electrode active material layer 34B is compression molded using a roll press or the like.

When forming the gel electrolyte layer 36, first, a precursor solution is prepared by mixing an electrolyte solution, a polymer compound, an organic solvent, and the like. Then, after apply | coating a precursor solution to the positive electrode 33, the precursor solution is dried, and the gel electrolyte layer 36 is formed. Moreover, after apply | coating a precursor solution to the negative electrode 34, the precursor solution is dried, and the gel electrolyte layer 36 is formed.

When assembling the secondary battery, first, the positive electrode lead 31 is attached to the positive electrode current collector 33A using a welding method or the like, and the negative electrode lead 32 is attached to the negative electrode current collector 34A using a welding method or the like. Subsequently, after the positive electrode 33 and the negative electrode 34 are laminated via the separator 35, the positive electrode 33, the negative electrode 34 and the separator 35 are wound to form the wound electrode body 30. Subsequently, the protective tape 37 is attached to the outermost peripheral portion of the wound electrode body 30. Finally, after folding the exterior member 40 so as to sandwich the wound electrode body 30 using the exterior member 40 provided with the window portion 42, the outer edge portions of the exterior member 40 are bonded to each other using a heat fusion method or the like. The wound electrode body 30 is sealed inside the exterior member 40 by bonding. In this case, the adhesion film 50 is inserted between the positive electrode lead 31 and the exterior member 40, and the adhesion film 50 is inserted between the negative electrode lead 32 and the exterior member 40.

Thereby, a laminated film type secondary battery provided with the gel electrolyte layer 36 is completed.

(Second procedure)
When each of the positive electrode 33 and the negative electrode 34 is manufactured by the same procedure as the first procedure and then the secondary battery is assembled, first, the positive electrode lead 31 is attached to the positive electrode 33 and the negative electrode lead 32 is attached to the negative electrode 34. .

Subsequently, the positive electrode 33 and the negative electrode 34 are laminated via the separator 35 and then wound to produce a wound body that is a precursor of the wound electrode body 30, and then the outermost periphery of the wound body A protective tape 37 is affixed to the part. Subsequently, after folding the exterior member 40 so as to sandwich the wound electrode body 30 using the exterior member 40 provided with the window portion 42, one side of the exterior member 40 using the heat fusion method or the like is used. The wound body is housed inside the bag-shaped exterior member 40 by pasting the remaining outer edge parts excluding the outer edge part.

Subsequently, an electrolyte composition is prepared by mixing an electrolytic solution, a monomer that is a raw material of the polymer compound, a polymerization initiator, and other materials such as a polymerization inhibitor as necessary. Subsequently, after the electrolyte composition is injected into the bag-shaped exterior member 40, the exterior member 40 is sealed using a heat fusion method or the like. Finally, the polymer is formed by thermally polymerizing the monomer. Since the electrolytic solution is held by the polymer compound, the gel electrolyte layer 36 is formed. Therefore, a laminated film type secondary battery is completed.

(Third procedure)
In the case of assembling a secondary battery, first, a wound body is produced by the same procedure as the second procedure described above, except that the separator 35 on which the polymer compound layer is formed is used. The wound body is accommodated in the bag-shaped exterior member 40 provided with 42.

Subsequently, after injecting an electrolyte into the exterior member 40, the exterior member 40 is sealed using a heat fusion method or the like. Subsequently, by heating the exterior member 40 while applying a load, the separator 35 is brought into close contact with the positive electrode 33 through the polymer compound layer, and the separator 35 is brought into close contact with the negative electrode 34 through the polymer compound layer. Thereby, each of the polymer compound layers is impregnated with the electrolytic solution, and each of the polymer compound layers is gelled, so that the electrolyte layer 36 is formed. Therefore, a laminated film type secondary battery is completed.

In the third procedure, the swollenness of the secondary battery is suppressed as compared with the first procedure. Further, in the third procedure, compared with the second procedure, the solvent, the monomer (the raw material of the polymer compound) and the like are less likely to remain in the electrolyte layer 36, and thus the formation process of the polymer compound is well controlled. . For this reason, each of the positive electrode 33, the negative electrode 34, and the separator 35 and the electrolyte layer 36 are easily adhered to each other.

[Action and effect]
According to this laminated film type lithium ion secondary battery, the wound electrode body 30 is housed inside the film-shaped exterior member 40, and the window portion includes a window functional material (non-porous molten fluororesin). 42 (window film 43) is provided on the exterior member 40 (exterior body 41). Therefore, excellent battery characteristics can be obtained for the reason described below.

When the exterior member 40 is not provided with the window 42, when a gas such as carbon dioxide is generated inside the secondary battery due to a side reaction such as a decomposition reaction of the electrolytic solution, there is no escape space for the gas. Therefore, gas is accumulated inside the secondary battery. In this case, as the internal pressure increases, the exterior member 40 is deformed so as to protrude from the internal environment E1 toward the external environment E2, so that the secondary battery swells.

On the other hand, in the case where the exterior member 40 is provided with the window 42, as described above, even if gas is generated inside the secondary battery, the gas is generated by utilizing the exhaust function of the window 42. Is discharged to the outside, so that the secondary battery is prevented from swelling. In addition, when the opening 41K is provided in the exterior member (the exterior body 41), there is a concern that water may enter the inside of the secondary battery through the opening 41K, but the waterproof function of the window 42 is used. Thus, since the intrusion of water is suppressed, the deterioration of cycle characteristics and the like due to the water is also suppressed. Therefore, without using machines such as safety valves, equipment such as equipment and devices, the use of the window portion 42 suppresses swelling of the secondary battery and suppresses deterioration of cycle characteristics, etc., and thus excellent battery characteristics. Is obtained.

In particular, if the window functional material (non-porous molten fluororesin) contains any one or more of non-porous PFA, non-porous FEP, non-porous ETFE, etc., the window 42 However, since it becomes easier to suppress the intrusion of water and the window portion 42 more easily releases the gas, a higher effect can be obtained.

Moreover, if the opening part 41K is provided in the exterior main body 41 and the window part 42 is formed by the window film 43 containing a window functional material covering the opening part 41K, the opening part 41K (the window film 43). ), The gas is sufficiently released, so that a higher effect can be obtained.

In this case, if the window film 43 has an area larger than the area of the opening 41 K and the window film 43 is attached to the exterior body 41 via the adhesive 44, the exterior body 41. The window film 43 is firmly fixed to the screen. Therefore, since the waterproof function and the exhaust function of the window part 42 are stably exhibited, a higher effect can be obtained.

Further, if the thickness of the window film 43 is 10 μm to 500 μm, a sufficient waterproof function and a sufficient exhaust function can be obtained while ensuring the physical durability of the window film 43, so that a higher effect can be obtained. Can do.

<1-2. Lithium metal secondary battery>
The secondary battery described here is a laminated film type lithium metal secondary battery in which the capacity of the negative electrode 34 is obtained by precipitation and dissolution of lithium metal. This secondary battery has the same configuration as the above-described laminate film type lithium ion secondary battery except that the negative electrode active material layer 34B is formed of lithium metal, and the same procedure is followed. Manufactured.

In this secondary battery, since lithium metal is used as the negative electrode active material, a high energy density can be obtained. The negative electrode active material layer 34B may already exist from the time of assembly, but does not exist at the time of assembly, and may be formed of lithium metal deposited at the time of charging. Further, the negative electrode current collector 34A may be omitted by using the negative electrode active material layer 34B as a current collector.

This secondary battery operates as follows, for example. At the time of charging, lithium ions are released from the positive electrode 33 and the lithium ions are deposited as lithium metal on the surface of the negative electrode current collector 34A through the electrolyte layer 36. On the other hand, at the time of discharge, lithium metal is converted into lithium ions from the negative electrode active material layer 34 B and eluted into the electrolyte layer 36, and the lithium ions are occluded in the positive electrode 21 through the electrolyte layer 36.

According to this laminated film type lithium metal secondary battery, the wound electrode body 30 is housed inside the film-shaped exterior member 40, and the window portion 42 (window film 43) containing the window functional material is the exterior member. 40 (exterior body 41). Therefore, excellent battery characteristics can be obtained for the same reason as the above-described lithium ion secondary battery. Other operations and effects relating to the lithium metal secondary battery are the same as those relating to the lithium ion secondary battery.

<1-3. Modification>
The configuration of the secondary battery of the present embodiment can be changed as appropriate.

(Modification 1)
Specifically, the window film 43 may be bonded to the exterior body 41 using, for example, any one type or two or more types of methods that do not use the adhesive 44. Examples of methods that do not use the adhesive 44 include a heat fusion method and an ultrasonic welding method. Even in this case, since the window film 43 is fixed to the exterior body 41, the same effect can be obtained.

(Modification 2)
Further, for example, as shown in FIG. 5 corresponding to FIG. 2, a window portion 42 may be provided on the side surface 41PS instead of the upper surface 41PT of the recessed portion 41P. The opening shape and opening area of the opening 41K can be arbitrarily set, and the planar shape and area of the window film 43 can be arbitrarily set. Here, for example, each of the opening shape of the opening 41K and the planar shape of the window film 43 is substantially rectangular (a rectangle with four corners rounded), and the area of the window film 43 is the opening of the opening 41K. It is larger than the area. Even in this case, the same effect can be obtained by the window portion 24 exhibiting a waterproof function and an exhaust function.

(Modification 3)
Further, for example, as shown in FIG. 6 corresponding to FIG. 3, a window film 43 is arranged on the outside (external environment E2) of the exterior body 41 instead of the inside (internal environment E1) of the exterior body 41. May be. The window film 43 is bonded to the outer surface of the exterior body 41 via an adhesive 44, for example. Even in this case, the same effect can be obtained by the window portion 24 exhibiting a waterproof function and an exhaust function.

However, as described above, when the window film 43 is disposed outside the exterior body 41, the window film 43 may be peeled off due to generation of gas (increase in internal pressure), and the window film. 43 may fall out of the secondary battery. Therefore, in order to suppress the window film 43 from peeling and dropping, the window film 43 is preferably disposed inside the exterior body 41 (internal environment E1).

(Modification 4)
Further, for example, as shown in FIG. 7 corresponding to FIG. 3, a protective layer 46 may be provided on the window film 43. This “on the window film 43” means the outside of the window film 43.

The protective layer 46 mainly functions to physically protect the surface of the window film 43. The protective layer 46 includes, for example, any one kind or two or more kinds of materials having air permeability. The type of material having air permeability is not particularly limited, and examples thereof include porous resins, ceramics, and mesh filters. The kind of the porous resin is not particularly limited. For example, porous polytetrafluoroethylene (PTFE), nylon, polypropylene (PP), polyethylene (PE), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC) ) And zeolite. The thickness of the protective layer 46 is not particularly limited and can be arbitrarily set.

If the protective layer 46 can protect the window film 43, the size (area) of the protective layer 46 is not particularly limited. That is, the area of the protective layer 46 may be the same as the exposed area of the window film 43 (the area of the window film 43 exposed at the opening 41K) or may be larger than the exposed area of the window film 43.

Here, the protective layer 46 has an area larger than the exposed area of the window film 43, for example, and is bonded to the exterior body 41 via the adhesive 45. For example, the adhesive 45 is preferably provided so as not to block the opening 41K in order to ensure air permeability using the window film 43. In FIG. 7, for example, a case where the protective layer 46 is prevented from being bonded to the window film 43 via the adhesive 45 is shown. The details regarding the adhesive 45 are the same as the details regarding the adhesive 44, for example.

In this case, since the window film 43 is physically protected by the protective layer 46, the window film 43 is prevented from being deformed, damaged and peeled off due to an external force. Moreover, since the air-permeable material has the property of allowing gas to pass therethrough, even if the protective layer 46 is provided on the window film 43, the gas is released to the outside through the protective layer 46. Is done. Therefore, since the physical durability of the window film 43 is improved while the exhaust function of the window portion 42 is ensured, a higher effect can be obtained.

Although not specifically shown here, for example, as shown in FIG. 6, when the window film 43 is disposed outside the exterior body 41, a protective layer 46 is provided on the window film 43. May be. The protective layer 46 is bonded to the exterior body 41 or the like via an adhesive 45, for example. In this case, the same effect can be obtained.

<2. Secondary Battery (Second Embodiment)>
Next, the secondary battery of the second embodiment will be described. Below, the component of the secondary battery of 1st Embodiment is quoted at any time.

<2-1. Lithium ion secondary battery>
The secondary battery described here is a lithium ion secondary battery. This secondary battery is the secondary battery according to the first embodiment, except that the exterior body 41 is not provided with the opening 41K and the exterior member 40 has a window 47 instead of the window 42. It has the same configuration as the battery and is manufactured by the same procedure.

[Constitution]
FIG. 8 illustrates a perspective configuration (a state after bonding) of the secondary battery of the present embodiment, and corresponds to each of FIGS. 1 and 2. However, in FIG. 8, as in FIG. 2, the positive electrode lead 31 and the negative electrode lead 32 are not shown.

FIG. 9 shows a cross-sectional configuration of the exterior member 40 along the line CC shown in FIG. FIG. 10 shows a cross-sectional configuration of the exterior member 40 along the line DD shown in FIG.

The window portion 47 mainly performs the same functions (waterproof function and exhaust function) as the window portion 42. For example, as shown in FIG. 8, the window portion 47 is provided in the adhesion region 41 Y instead of the non-adhesion region 41 X of the exterior body 41, and includes the window film 48 instead of the window film 43. Yes.

Specifically, for example, in a state in which the window film 48 is sandwiched between the

exterior portions

41A and 41B, the

exterior portions

41A and 41B are bonded to each other, whereby the window portion 47 is formed. That is, the window part 47 includes, for example, a window functional material (non-porous molten fluororesin) and a window film 48 interposed between the

exterior parts

41A and 41B. In FIG. 8, in order to make it easy to identify the window 47 (window film 48), the window 47 is shaded.

The window 47 is exposed to each of the internal environment E1 and the external environment E2, as shown in FIGS. The reason why the window portion 47 is provided in the exterior member 40 is the same as the case where the window portion 42 is provided in the exterior member 40. That is, by using the waterproof function and exhaust function of the window 47, deterioration of cycle characteristics and the like are suppressed without using machinery, equipment and devices such as safety valves, and secondary battery swelling is also suppressed. Is done.

As long as the waterproof function and the exhaust function described above can be exhibited, the number, position, and configuration of the window portion 47 are not particularly limited.

The number of window portions 47 may be only one, or two or more. Here, the number of window parts 47 is one, for example.

Further, the position of the window 47 may be arbitrary as long as it is any position in the adhesion region 41Y. Here, the window part 47 is provided in a part of the adhesion region 41Y on the side where each of the positive electrode lead 31 and the negative electrode lead 32 is introduced from the inside of the exterior member 40 to the outside, for example.

The window film 48 includes, for example, any one type or two or more types of window functional materials in the same manner as the window film 43. Since the planar shape of the window film 48 is not particularly limited, it may be, for example, a circle, an ellipse, a rectangle, or other shapes. Here, the planar shape of the window film 48 is, for example, a rectangle.

For example, the window film 48 is adhered to the exterior main body 41 (exterior portion 41A) via an adhesive 49, and is similarly adhered to the exterior main body 41 (exterior portion 41B) via the adhesive 49. . The details regarding the adhesive 49 are the same as the details regarding the adhesive 44, for example.

In the region where the window film 48 does not exist, as described above, the adhesive layer of the exterior part 41A and the adhesive layer of the outer layer part 41B are adhered to each other. Thereby, the exterior member 40 is sealed.

The thickness of the window film 48 is not particularly limited, but is, for example, 10 μm to 500 μm, preferably 10 μm to 200 μm. This is because, as in the case where the thickness of the window film 43 is defined, a sufficient waterproof function and a sufficient exhaust function can be obtained while ensuring the physical durability of the window film 48 and the like.

In addition, when the adhesiveness between the adhesive 49 and the window film 48 is not sufficient, for example, in order to improve the adhesiveness as in the case where the adhesiveness between the adhesive 44 and the window film 43 is not sufficient. In addition, any one kind or two or more kinds of pretreatments may be applied to the surface of the window film 48. Details regarding the preprocessing are as described above, for example.

Of course, when the adhesiveness between the adhesive 49 and the exterior body 41 is not sufficient, for example, in order to improve the adhesiveness as in the case where the adhesiveness between the adhesive 44 and the exterior body 41 is not sufficient. In addition, any one type or two or more types of pretreatments may be applied to the surface of the exterior body 41.

[Production method]
This secondary battery, for example, except that the exterior member 40 provided with the window portion 48 is used by attaching the window film 48 to the exterior body 41 (the

exterior portions

41A and 41B) using the adhesive 49. It is manufactured by the same procedure as the secondary battery of the first embodiment.

[Action and effect]
According to this laminated film type lithium ion secondary battery, the wound electrode body 30 is housed inside the film-shaped exterior member 40, and the window portion 47 (window film 48) containing the window functional material is the exterior member. 40. In this case, for the same reason as the secondary battery of the first embodiment, the waterproof function of the window film 48 is used to suppress deterioration of cycle characteristics and the like caused by water, and the window film 48 By using the exhaust function, swelling of the secondary battery is suppressed. Therefore, excellent battery characteristics can be obtained.

In particular, if the window part 48 is formed by bonding the

exterior parts

41A and 41B to each other via the window film 48 containing a window functional material, the window part 48 can be provided without providing the exterior body 41 with an opening or the like. Therefore, a higher effect can be obtained.

Further, if the thickness of the window film 48 is 10 μm to 500 μm, a sufficient waterproof function and a sufficient exhaust function can be obtained while ensuring the physical durability of the window film 48, so that a higher effect can be obtained. Can do.

Other actions and effects related to the secondary battery of the present embodiment are the same as the actions and effects related to the secondary battery of the first embodiment.

<2-2. Lithium metal secondary battery>
The secondary battery described here is a laminated film type lithium metal secondary battery. This secondary battery has the same configuration as the above laminated film type lithium ion secondary battery except that lithium metal is used as the negative electrode active material, and is manufactured by the same procedure. The

According to this laminated film type lithium metal secondary battery, the wound electrode body 30 is housed inside the film-like exterior member 40, and the window portion 47 (window film 48) containing the window functional material is the exterior member. 40. Therefore, excellent battery characteristics can be obtained for the same reason as the above-described lithium ion secondary battery. Other operations and effects relating to the lithium metal secondary battery are the same as those relating to the lithium ion secondary battery.

<2-3. Modification>
The configuration of the secondary battery of the present embodiment can be changed as appropriate. Specifically, the window film 48 may be attached to the exterior body 41 using any one type or two or more types of methods that do not use the adhesive 49, for example, as with the window film 43. Good. The details regarding the method not using the adhesive 49 are as described above, for example. Also in this case, since the window film 48 is fixed to the exterior body 41, the same effect can be obtained.

<3. Applications of secondary batteries>
Next, application examples of the above-described secondary battery will be described.

Secondary batteries can be used in machines, equipment, instruments, devices and systems (aggregates of multiple equipment) that can be used as a power source for driving or a power storage source for power storage. If there is, it will not be specifically limited. The secondary battery used as a power source may be a main power source or an auxiliary power source. The main power source is a power source that is preferentially used regardless of the presence or absence of other power sources. The auxiliary power supply may be, for example, a power supply used instead of the main power supply, or a power supply that can be switched from the main power supply as necessary. When a secondary battery is used as an auxiliary power source, the type of main power source is not limited to the secondary battery.

The usage of the secondary battery is, for example, as follows. Electronic devices (including portable electronic devices) such as video cameras, digital still cameras, mobile phones, notebook computers, cordless phones, headphone stereos, portable radios, portable televisions, and portable information terminals. It is a portable living device such as an electric shaver. Storage devices such as backup power supplies and memory cards. Electric tools such as electric drills and electric saws. It is a battery pack that is mounted on a notebook computer as a detachable power source. Medical electronic devices such as pacemakers and hearing aids. An electric vehicle such as an electric vehicle (including a hybrid vehicle). It is an electric power storage system such as a home battery system that stores electric power in case of an emergency. Of course, the secondary battery may be used for other purposes.

Among them, it is effective that the secondary battery is applied to a battery pack, an electric vehicle, an electric power storage system, an electric tool, an electronic device, and the like. This is because excellent battery characteristics are required for these applications, and therefore the performance can be effectively improved by using the secondary battery of the present technology. The battery pack is a power source using a secondary battery. As will be described later, this battery pack may use a single battery or an assembled battery. An electric vehicle is a vehicle that operates (runs) using a secondary battery as a driving power source, and may be an automobile (such as a hybrid automobile) that includes a drive source other than the secondary battery as described above. The power storage system is a system that uses a secondary battery as a power storage source. For example, in a household power storage system, power is stored in a secondary battery, which is a power storage source, and thus it is possible to use household electrical appliances or the like using the power. An electric power tool is a tool in which a movable part (for example, a drill etc.) moves, using a secondary battery as a driving power source. An electronic device is a device that exhibits various functions using a secondary battery as a driving power source (power supply source).

Here, some application examples of the secondary battery will be specifically described. In addition, since the structure of the application example demonstrated below is an example to the last, the structure of the application example can be changed suitably.

<3-1. Battery pack (single cell)>
FIG. 11 shows a perspective configuration of a battery pack using single cells. FIG. 12 shows a block configuration of the battery pack shown in FIG. FIG. 11 shows a state where the battery pack is disassembled.

The battery pack described here is a simple battery pack (so-called soft pack) using one secondary battery of the present technology, and is mounted on, for example, an electronic device typified by a smartphone. For example, as shown in FIG. 11, the battery pack includes a power supply 111 that is a laminate film type secondary battery, and a circuit board 116 connected to the power supply 111. A positive electrode lead 112 and a negative electrode lead 113 are attached to the power source 111.

A pair of

adhesive tapes

118 and 119 are attached to both side surfaces of the power source 111. A protection circuit (PCM: Protection Circuit Circuit Module) is formed on the circuit board 116. The circuit board 116 is connected to the positive electrode 112 through the tab 114 and is connected to the negative electrode lead 113 through the tab 115. The circuit board 116 is connected to a lead wire 117 with a connector for external connection. In the state where the circuit board 116 is connected to the power source 111, the circuit board 116 is protected by the label 120 and the insulating sheet 121. By attaching the label 120, the circuit board 116, the insulating sheet 121, and the like are fixed.

Further, the battery pack includes, for example, a power supply 111 and a circuit board 116 as shown in FIG. The circuit board 116 includes, for example, a control unit 121, a switch unit 122, a PTC element 123, and a temperature detection unit 124. Since the power source 111 can be connected to the outside via the positive electrode terminal 125 and the negative electrode terminal 127, the power source 111 is charged / discharged via the positive electrode terminal 125 and the negative electrode terminal 127. The temperature detector 124 detects the temperature using a temperature detection terminal (so-called T terminal) 126.

The controller 121 controls the operation of the entire battery pack (including the usage state of the power supply 111). The control unit 121 includes, for example, a central processing unit (CPU) and a memory.

For example, when the battery voltage reaches the overcharge detection voltage, the control unit 121 disconnects the switch unit 122 so that the charging current does not flow in the current path of the power supply 111. For example, when a large current flows during charging, the control unit 121 cuts off the charging current by cutting the switch unit 122.

On the other hand, for example, when the battery voltage reaches the overdischarge detection voltage, the control unit 121 disconnects the switch unit 122 so that no discharge current flows in the current path of the power supply 111. For example, when a large current flows during discharge, the control unit 121 cuts off the discharge current by cutting the switch unit 122.

The overcharge detection voltage is, for example, 4.2V ± 0.05V, and the overdischarge detection voltage is, for example, 2.4V ± 0.1V.

The switch unit 122 switches the usage state of the power source 111, that is, whether or not the power source 111 is connected to an external device, in accordance with an instruction from the control unit 121. The switch unit 122 includes, for example, a charge control switch and a discharge control switch. Each of the charge control switch and the discharge control switch is, for example, a semiconductor switch such as a field effect transistor (MOSFET) using a metal oxide semiconductor. The charge / discharge current is detected based on, for example, the ON resistance of the switch unit 122.

The temperature detection unit 124 measures the temperature of the power supply 111 and outputs the temperature measurement result to the control unit 121. The temperature detection unit 124 includes a temperature detection element such as a thermistor, for example. The temperature measurement result measured by the temperature detection unit 124 is used when the control unit 121 performs charge / discharge control during abnormal heat generation, or when the control unit 121 performs correction processing when calculating the remaining capacity. .

Note that the circuit board 116 may not include the PTC element 123. In this case, a PTC element may be attached to the circuit board 116 separately.

<3-2. Battery Pack (Battery)>
FIG. 13 shows a block configuration of a battery pack using an assembled battery.

This battery pack includes, for example, a control unit 61, a power source 62, a switch unit 63, a current measurement unit 64, a temperature detection unit 65, a voltage detection unit 66, and a switch control unit 67 inside the housing 60. A memory 68, a temperature detection element 69, a current detection resistor 70, and a positive terminal 71 and a negative terminal 72. The housing 60 includes, for example, a plastic material.

The control unit 61 controls the operation of the entire battery pack (including the usage state of the power supply 62). The control unit 61 includes, for example, a CPU. The power source 62 is an assembled battery including two or more types of secondary batteries of the present technology, and the connection type of the two or more types of secondary batteries may be in series, in parallel, or a mixture of both. . For example, the power source 62 includes six secondary batteries connected in two parallel three series.

The switch unit 63 switches the usage state of the power source 62, that is, whether or not the power source 62 is connected to an external device, in accordance with an instruction from the control unit 61. The switch unit 63 includes, for example, a charge control switch, a discharge control switch, a charging diode, a discharging diode, and the like. Each of the charge control switch and the discharge control switch is, for example, a semiconductor switch such as a field effect transistor (MOSFET) using a metal oxide semiconductor.

The current measurement unit 64 measures the current using the current detection resistor 70 and outputs the measurement result of the current to the control unit 61. The temperature detection unit 65 measures the temperature using the temperature detection element 69 and outputs the temperature measurement result to the control unit 61. This temperature measurement result is used, for example, when the control unit 61 performs charge / discharge control during abnormal heat generation, or when the control unit 61 performs correction processing when calculating the remaining capacity. The voltage detection unit 66 measures the voltage of the secondary battery in the power source 62 and supplies the control unit 61 with the measurement result of the analog-digital converted voltage.

The switch control unit 67 controls the operation of the switch unit 63 according to signals input from the current measurement unit 64 and the voltage detection unit 66, respectively.

For example, when the battery voltage reaches the overcharge detection voltage, the switch control unit 67 disconnects the switch unit 63 (charge control switch) so that the charging current does not flow in the current path of the power source 62. As a result, the power source 62 can only discharge through the discharging diode. For example, when a large current flows during charging, the switch control unit 67 cuts off the charging current.

Further, for example, when the battery voltage reaches the overdischarge detection voltage, the switch control unit 67 disconnects the switch unit 63 (discharge control switch) so that the discharge current does not flow in the current path of the power source 62. As a result, the power source 62 can only be charged via the charging diode. For example, when a large current flows during discharge, the switch control unit 67 interrupts the discharge current.

The memory 68 includes, for example, an EEPROM which is a nonvolatile memory. The memory 68 stores, for example, numerical values calculated by the control unit 61, information on the secondary battery measured in the manufacturing process stage (for example, internal resistance in an initial state), and the like. If the full charge capacity of the secondary battery is stored in the memory 68, the control unit 61 can grasp information such as the remaining capacity.

The temperature detection element 69 measures the temperature of the power supply 62 and outputs the temperature measurement result to the control unit 61. The temperature detection element 69 includes, for example, a thermistor.

Each of the positive electrode terminal 71 and the negative electrode terminal 72 is used for an external device (eg, a notebook personal computer) that is operated using a battery pack, an external device (eg, a charger) that is used to charge the battery pack, and the like. It is a terminal to be connected. The power source 62 is charged and discharged via the positive terminal 71 and the negative terminal 72.

<3-3. Electric vehicle>
FIG. 14 shows a block configuration of a hybrid vehicle which is an example of an electric vehicle.

This electric vehicle includes, for example, a control unit 74, an engine 75, a power source 76, a driving motor 77, a differential device 78, a generator 79, and a transmission 80 inside a metal casing 73. And a clutch 81,

inverters

82 and 83, and various sensors 84. In addition, the electric vehicle includes, for example, a front wheel drive shaft 85 and a front wheel 86 connected to the differential device 78 and the transmission 80, and a rear wheel drive shaft 87 and a rear wheel 88.

This electric vehicle can travel using, for example, one of the engine 75 and the motor 77 as a drive source. The engine 75 is a main power source, such as a gasoline engine. When the engine 75 is used as a power source, for example, the driving force (rotational force) of the engine 75 is transmitted to the front wheels 86 and the rear wheels 88 via the differential device 78, the transmission 80, and the clutch 81 which are driving units. The Since the rotational force of engine 75 is transmitted to generator 79, generator 79 generates AC power using the rotational force, and the AC power is converted to DC power via inverter 83. Therefore, the DC power is accumulated in the power source 76. On the other hand, in the case where the motor 77 serving as the conversion unit is used as a power source, the power (DC power) supplied from the power source 76 is converted into AC power via the inverter 82, and therefore the motor is utilized using the AC power. 77 is driven. The driving force (rotational force) converted from the electric power by the motor 77 is transmitted to the front wheels 86 and the rear wheels 88 via, for example, a differential device 78 that is a driving unit, a transmission 80, and a clutch 81.

When the electric vehicle decelerates via the braking mechanism, the resistance force at the time of deceleration is transmitted as a rotational force to the motor 77. Therefore, the motor 77 may generate AC power using the rotational force. Good. Since this AC power is converted into DC power via the inverter 82, the DC regenerative power is preferably stored in the power source 76.

The control unit 74 controls the operation of the entire electric vehicle. The control unit 74 includes, for example, a CPU. The power source 76 includes one or more types of secondary batteries of the present technology. The power source 76 may be connected to an external power source, and may store power by receiving power supply from the external power source. The various sensors 84 are used, for example, to control the rotational speed of the engine 75 and to control the throttle valve opening (throttle opening). The various sensors 84 include, for example, any one or more of speed sensors, acceleration sensors, engine speed sensors, and the like.

Although the case where the electric vehicle is a hybrid vehicle has been described as an example, the electric vehicle may be a vehicle (electric vehicle) that operates using only the power source 76 and the motor 77 without using the engine 75.

<3-4. Power storage system>
FIG. 15 shows a block configuration of the power storage system.

This power storage system includes, for example, a control unit 90, a power source 91, a smart meter 92, and a power hub 93 in a house 89 such as a general house or a commercial building.

Here, for example, the power source 91 is connected to an electric device 94 installed in the house 89 and can be connected to an electric vehicle 96 stopped outside the house 89. The power source 91 is connected to, for example, a private generator 95 installed in a house 89 via a power hub 93 and also connected to an external centralized power system 97 via a smart meter 92 and the power hub 93. It is possible.

Note that the electric device 94 includes, for example, one or more kinds of home appliances, and the home appliances are, for example, a refrigerator, an air conditioner, a television, and a water heater. The private power generator 95 includes, for example, any one type or two or more types among a solar power generator and a wind power generator. The electric vehicle 96 includes, for example, any one or more of an electric vehicle, an electric motorcycle, and a hybrid vehicle. The centralized power system 97 includes, for example, any one or more of a thermal power plant, a nuclear power plant, a hydroelectric power plant, and a wind power plant.

The control unit 90 controls the operation of the entire power storage system (including the usage state of the power supply 91). The control unit 90 includes, for example, a CPU. The power source 91 includes one or more types of secondary batteries of the present technology. The smart meter 92 is, for example, a network-compatible power meter installed in the house 89 on the power demand side, and can communicate with the power supply side. Accordingly, the smart meter 92 enables highly efficient and stable energy supply, for example, by controlling the balance between the demand and supply of power in the house 89 while communicating with the outside.

In this power storage system, for example, power is accumulated in the power source 91 from the centralized power system 97 that is an external power source via the smart meter 92 and the power hub 93, and from the private power generator 95 that is an independent power source via the power hub 93. Thus, electric power is accumulated in the power source 91. The electric power stored in the power supply 91 is supplied to the electric device 94 and the electric vehicle 96 in accordance with an instruction from the control unit 90, so that the electric device 94 can be operated and the electric vehicle 96 can be charged. Become. In other words, the power storage system is a system that makes it possible to store and supply power in the house 89 using the power source 91.

The power stored in the power source 91 can be used as necessary. For this reason, for example, power is stored in the power source 91 from the centralized power system 97 at midnight when the electricity usage fee is low, and the power stored in the power source 91 is used during the day when the electricity usage fee is high. it can.

The power storage system described above may be installed for each house (one household), or may be installed for each of a plurality of houses (multiple households).

<3-5. Electric tool>
FIG. 16 shows a block configuration of the electric power tool.

The electric tool described here is, for example, an electric drill. This electric tool includes, for example, a control unit 99 and a power source 100 inside a tool body 98. For example, a drill portion 101 which is a movable portion is attached to the tool body 98 so as to be operable (rotatable).

The tool main body 98 includes, for example, a plastic material. The control unit 99 controls the operation of the entire power tool (including the usage state of the power supply 100). The control unit 99 includes, for example, a CPU. The power supply 100 includes one or more types of secondary batteries of the present technology. The control unit 99 supplies power from the power supply 100 to the drill unit 101 in accordance with the operation of the operation switch.

An example of this technology will be described.

(Experimental Examples 1-1 to 1-15)
By providing the window 42 (opening 41K and window film 43) in the non-adhesive region 41X of the exterior body 41 by the following procedure, the laminated film type lithium ion shown in FIGS. 1 to 5 and FIG. A secondary battery was produced.

When producing the positive electrode 33, first, 97 parts by mass of a positive electrode active material (LiNi _0.5 Co _0.2 Mn _0.3 O ₂ ), ₂ parts by mass of a positive electrode binder (polyvinylidene fluoride), and a positive electrode conductive agent (carbon black) ) 1 part by mass was mixed to obtain a positive electrode mixture. Subsequently, the positive electrode mixture was charged into an organic solvent (N-methyl-2-pyrrolidone), and then the organic solvent was stirred to obtain a paste-like positive electrode mixture slurry. Subsequently, the positive electrode mixture slurry was applied to both surfaces of the positive electrode current collector 33A (12 μm-thick striped aluminum foil) using a coating apparatus, and then the positive electrode mixture slurry was dried, whereby the positive electrode active material layer 33B was formed. Formed. Finally, the positive electrode active material layer 33B was compression molded using a roll press.

In preparing the negative electrode 34, first, 95 parts by mass of a negative electrode active material (granular graphite powder, median diameter D50 = 20 μm) and a negative electrode binder (acrylic modified product of styrene-butadiene rubber copolymer) 1.5 By mixing 2 parts by mass of a negative electrode binder (particulate polyvinylidene fluoride, median diameter D50 = 0.3 μm) with 1.5 parts by mass of a thickener (carboxymethylcellulose), did. Subsequently, after putting the negative electrode mixture into pure water, the pure water was stirred to obtain a paste-like negative electrode mixture slurry. Subsequently, the negative electrode mixture slurry was applied to both surfaces of the negative electrode current collector 34A (15 μm thick strip copper foil) using a coating apparatus, and then the negative electrode mixture slurry was dried, whereby the negative electrode active material layer 34B was formed. Formed. Finally, the negative electrode active material layer 34B was compression molded using a roll press.

When preparing an electrolytic solution, an electrolyte salt (LiPF ₆ ) is added to a solvent (ethylene carbonate, ethyl methyl carbonate and vinylene carbonate), and then the solvent is stirred to dissolve the electrolyte salt in the solvent. It was. In this case, the mixing ratio (mass ratio) of the solvent was ethylene carbonate: ethyl methyl carbonate: vinylene carbonate = 30: 69: 1. The content of the electrolyte salt was 1 mol / dm ³ (= 1 mol / l) with respect to the solvent.

When assembling the secondary battery, first, the positive electrode lead 31 made of aluminum was welded to the positive electrode current collector 33A, and the negative electrode lead 32 made of copper was welded to the negative electrode current collector 34A.

Subsequently, a polymer compound (polyvinylidene fluoride) is dissolved in an organic solvent (N-methyl-2-pyrrolidone) to obtain a solution in which the polymer compound is dissolved in the organic solvent. The solution was applied on both sides of a (12 μm thick microporous polyethylene film). Subsequently, the substrate layer was immersed in a water bath to phase-separate the solution, and then the substrate layer was dried with warm air. Thereby, since the high molecular compound layer was formed on both surfaces of the base material layer, the separator 35 was obtained.

Subsequently, the positive electrode 33 and the negative electrode 34 were laminated through the separator 35 to obtain a laminate. Then, after winding a laminated body to a longitudinal direction, the wound electrode body 30 was produced by affixing the protective tape 37 on the outermost peripheral part of the laminated body.

Subsequently, after the film-shaped exterior member 40 was folded so as to sandwich the wound electrode body 30, the outer peripheral edge portions on three sides of the exterior member 40 were heat-sealed. The exterior member 40 is an aluminum laminated film in which a 25 μm thick nylon film, a 40 μm thick aluminum foil, and a 30 μm thick polypropylene film are laminated in this order from the outside. When heat-sealing the exterior member 40, the adhesion film 50 was inserted between the positive electrode lead 31 and the exterior member 40, and the adhesion film 50 was inserted between the negative electrode lead 32 and the exterior member 40.

In this case, a window film 43 containing a window functional material is attached to the exterior body 41 via the adhesive 44 so as to cover the opening 41K provided in the non-adhesion region 41X of the exterior body 41. Thus, the exterior member 40 provided with the window portion 42 was used. Moreover, the exterior member 40 provided with the protective layer 46 by sticking the protective layer 46 to the window film 43 via the adhesive 46 was used.

For comparison, an exterior member 40 not provided with a window portion 42 was used. Moreover, the exterior member 40 in which the window film 43 contains materials other than a window functional material was used for the comparison.

The presence / absence of the window 42, the configuration of the opening 41K (position and dimensions (cm × cm)), the configuration of the window film 43 (material and thickness (μm)), and the configuration of the protective layer 46 (presence and material) As shown in FIG.

The material of the window film 43 is as follows. Non-porous PFA, non-porous FEP and non-porous ETFE were used as the window functional material (non-porous molten fluororesin). As materials other than the window functional material, porous PFA, polypropylene (PP) and polyethylene terephthalate (PET) were used.

As the forming material (porous resin) of the protective layer 46, porous polytetrafluoroethylene (PTFE) was used.

When the window film 43 containing the window functional material is attached to the exterior body 41 via the adhesive 44, first, the surface of the window film 43 was pretreated. In this case, the surface of the window film 43 is reformed (so-called fluorobonder treatment) by spraying the surface of the window film 43 with a pretreatment agent (a fluororesin surface treatment agent fluorobonder E manufactured by Technos Co., Ltd.). did. Subsequently, the surface of the exterior body 41 was pretreated. In this case, an undercoat (PPX primer manufactured by Cemedine Co., Ltd.) was applied to the surface of the exterior body 41. Finally, the pretreatment surface of the window film 43 and the pretreatment surface of the exterior main body 41 were bonded via an adhesive 44 (PPX manufactured by Cemedine Co., Ltd.).

When the window film 43 containing a material other than the window functional material is attached to the exterior main body 41 via the adhesive 44, the window film 43 containing the window functional material is attached to the exterior main body 41 via the adhesive 44. A similar procedure was used.

Finally, by injecting the electrolyte into the exterior member 40 to impregnate the separator 35 with the electrolyte, the outer peripheral edge portions of the remaining one side of the exterior member 40 are heat-sealed in a reduced pressure environment. did. As a result, since the wound electrode body 30 was enclosed in the exterior member 40, a laminated film type lithium ion secondary battery (battery size = 80 mm × 60 mm × 40 mm, battery capacity = 3000 mAh) was completed.

In order to evaluate the battery characteristics of the secondary battery, the capacity maintenance characteristics, swelling characteristics, physical durability characteristics and adhesion characteristics of the secondary battery were examined. The results shown in Table 1 were obtained.

When examining the capacity maintenance characteristics, first, the secondary battery was stored (storage period = 7 days) in a high temperature environment (temperature = 60 ° C., humidity = 90%) using a thermostatic chamber. Then, after taking out a secondary battery from a thermostat, the discharge capacity (mAh) was measured by charging / discharging the secondary battery. Finally, capacity retention rate (%) = (discharge capacity / battery capacity (= 3000 mAr)) × 100 was calculated.

At the time of charging, constant current charging was performed until the voltage reached 4.2 V at a current of 0.2 A. At the time of discharging, constant current discharging was performed at a current of 0.6 A until the voltage reached 2.5V.

When investigating the swelling characteristics, first, the secondary battery is charged in a normal temperature environment (temperature = 23 ° C.), and then the thickness of the charged secondary battery (thickness before storage) is measured using a micrometer. ) Was measured. Subsequently, after storing the secondary battery in a charged state in a high-temperature environment (temperature = 60 ° C., humidity = 90%) in a thermostatic chamber (storage period = 7 days), the secondary battery in a charged state using a micrometer is stored. The thickness of the battery (thickness after storage) was measured. Finally, thickness change rate (%) = [(thickness after storage−thickness before storage) / thickness before storage] × 100 was calculated.

In addition, at the time of charge, constant current charge was performed until the voltage reached 4.2 V with a current of 1 A.

When examining the physical durability characteristics, the scratching state on the outermost surface of the window portion 42 was visually confirmed by performing a scratch test in accordance with JIS K5400-5-4. As a result, “A” indicates that no scratch is generated on the outermost surface of the window portion 42, “B” indicates that the scratch is generated on the outermost surface of the window portion 42, and scratches occur on the outermost surface of the window portion 42. In addition, the case where the window portion 42 was damaged was evaluated as “C”. The outermost surface of the window portion 42 is the surface of the window film 43 when the protective layer 46 is not provided, and the surface of the protective layer 46 when the protective layer 46 is provided.

When examining the adhesion characteristics, the adhesion strength of the window film 43 was confirmed by performing an adhesion test based on JIS K7127: 1999. As a result, the case where the window film 43 did not peel was evaluated as “A”, and the case where the window film 43 peeled was evaluated as “C”.

When the window portion 42 was not provided (Experimental Example 1-12), a high capacity retention rate was obtained, but the thickness change rate increased. This result indicates that the secondary battery swelled as the internal pressure increased because gas resulting from the decomposition reaction of the electrolytic solution was generated inside the secondary battery. Below, the result when the window part 42 is not provided is used as a comparison reference.

On the other hand, when the window portion 42 was provided, each of the capacity maintenance rate and the thickness change rate varied greatly depending on the material of the window film 43.

Specifically, when materials other than the window functional material (porous PFA and PP) were used as the material for forming the window film 43 (Experimental Examples 1-13 and 1-14), the thickness change rate was significantly reduced. However, the capacity maintenance rate also decreased significantly. When a material other than the window functional material (PET) was used (Experimental Example 1-15), a high capacity retention rate was maintained, but the thickness change rate was almost the same.

However, when window functional materials (non-porous PFA, non-porous FEP, and non-porous ETFE) are used as the material for forming the window film 43 (Experimental Examples 1-1 to 1-11), Regardless of the position, the type of window functional material, the thickness of the window film 43, and the like, the rate of change in thickness was significantly reduced while the capacity maintenance rate was substantially maintained. As a result, when the window portion 42 (window film 43 including a window functional material) is used, the gas generated inside the secondary battery is released to the outside. This indicates that it is difficult for water to enter the inside of the battery, so that the discharge capacity is hardly reduced.

In addition, when window functional materials are used (Experimental Examples 1-1 to 1-11), the same level of abrasion as when materials other than the window functional materials are used (Experimental Examples 1-13 to 1-15). The condition was obtained and the same degree of adhesive strength was obtained. That is, even when a window functional material was used as the forming material of the window film 43, neither the scratched state nor the adhesive strength was deteriorated.

In particular, when window functional materials were used (Experimental Examples 1-1 to 1-11), the following tendencies were obtained. First, when the thickness of the window film 43 is 10 μm to 500 μm, the thickness change rate is sufficiently reduced. In this case, when the thickness of the window film 43 was 200 μm or less, the thickness change rate was further reduced. Second, when the protective layer 46 is used, the rubbing state of the outermost surface of the window portion 42 is remarkably improved.

(Experimental examples 2-1 to 2-4)
As shown in Table 2, Experimental Examples 1-1 to 1-15 except that a window portion 47 (window film 48) is provided in the adhesion region 41Y instead of the non-adhesion region 41X of the exterior body 41. The laminate film type lithium ion secondary battery shown in FIG. 8 to FIG. 10 was produced by the same procedure as described above, and the battery characteristics of the secondary battery were evaluated.

When the window film 48 including the window functional material is attached to the exterior body 41 (the

exterior portions

41A and 41B) via the adhesive 49, first, pretreatment was performed on both surfaces of the window film 48. In this case, both surfaces of the window film 48 were modified (fluorobonder treatment) by spraying a pretreatment agent (a fluororesin surface treatment agent fluorobonder E manufactured by Technos Co., Ltd.) on both surfaces of the window film 48. . Subsequently, each of the surface of the exterior part 41A and the surface of the exterior part 41B was pretreated. In this case, an undercoat (PPX primer manufactured by Cemedine Co., Ltd.) was applied to the surface of the exterior portion 41A, and a similar undercoat was applied to the surface of the exterior portion 41B. Finally, the pretreatment surface of the window film 48 and the pretreatment surface of the exterior portion 41A are bonded to each other via an adhesive 49 (PPX manufactured by Cemedine Co., Ltd.), and the window film is attached via the same adhesive 49. The 48 pretreatment surfaces and the pretreatment surface of the exterior portion 41B were adhered to each other.

In the case where the window 47 is provided in the bonded area 41Y (Table 2), the same result as in the case where the window 42 is provided in the non-bonded area 41X (Table 1) was obtained. That is, when the window 47 is provided and a window functional material is used as a material for forming the window film 48 (Experimental Examples 2-1 to 2-41), the window 47 is not provided (Experimental Example 1). −12) and a case where a material other than the window functional material is used as a material for forming the window film 48 (Experimental Examples 1-13 to 1-15), a high capacity retention rate is obtained, and a thickness change rate is obtained. Decreased significantly. Of course, when the window portion 47 is provided and the window functional material is used (Experimental Examples 2-1 to 2-4), the case where the window portion 47 is not provided (Experimental Example 1-12) and other than the window functional material The same rubbing state and adhesive strength as in the case of using these materials (Experimental Examples 1-13 to 1-15) were also obtained.

From the results shown in Table 1 and Table 2, the wound electrode body is accommodated in the film-shaped exterior member, and the window portion containing the window functional material (non-porous molten fluororesin) is included in the exterior member. When provided, the capacity maintenance characteristic and the swollenness characteristic of the secondary battery were improved while ensuring the physical durability characteristic and adhesion characteristic of the exterior member. Therefore, excellent battery characteristics were obtained in the secondary battery.

As mentioned above, although this technique was demonstrated, giving some embodiment and an Example, this technique is not limited to the aspect demonstrated in one Embodiment and an Example, A various deformation | transformation is possible.

Specifically, for example, the case where the battery element has a winding structure has been described, but the structure of the battery element in the secondary battery of the present technology is not particularly limited. Specifically, the battery element may have another structure such as a laminated structure.

In addition, the secondary battery (lithium ion secondary battery) in which the capacity of the negative electrode can be obtained by occlusion and release of lithium and the secondary battery (lithium metal secondary battery) in which the capacity of the negative electrode can be obtained by precipitation dissolution of lithium have been described. The principle of obtaining the capacity of the negative electrode in the secondary battery of the present technology is not particularly limited. Specifically, for example, by making the capacity of the negative electrode material capable of occluding and releasing lithium smaller than the capacity of the positive electrode, the secondary battery can be obtained by the sum of the capacity due to the occlusion and release of lithium and the capacity due to the precipitation dissolution of lithium. A secondary battery or the like that can obtain the capacity of the negative electrode may be used.

Further, although the case where lithium is used as the electrode reactant has been described, the present invention is not limited to this. The electrode reactant may be another group 1 element in the long-period periodic table such as sodium (Na) and potassium (K), or may be a long-period periodic table such as magnesium (Mg) and calcium (Ca). Group 2 elements may be used, or other light metals such as aluminum (Al) may be used. The electrode reactant may be an alloy containing any one or more of the series of elements described above.

In addition, the effect described in this specification is an illustration to the last, and is not limited, Moreover, there may exist another effect.

In addition, this technique can also take the following structures.
(1)
A battery element comprising a positive electrode, a negative electrode and an electrolyte;
A secondary battery comprising the battery element and a film-shaped exterior member having a window portion containing a non-porous molten fluororesin.
(2)
The non-porous molten fluororesin includes non-porous tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), non-porous tetrafluoroethylene / hexafluoropropylene copolymer (FEP), and non-porous tetrafluoro. Including at least one ethylene / ethylene copolymer (ETFE),
The secondary battery as described in said (1).
(3)
The exterior member has an opening,
The window portion is formed by covering at least the opening with a film-like window member containing the non-porous molten fluororesin,
The secondary battery according to (1) or (2) above.
(4)
The window member has an area larger than the area of the opening, and is attached to the exterior member via an adhesive.
The secondary battery as described in (3) above.
(5)
A protective layer containing a material having air permeability is provided on the window member.
The secondary battery according to (3) or (4) above.
(6)
The window member has a thickness of 10 μm or more and 500 μm or less,
The secondary battery according to any one of (3) to (5) above.
(7)
The exterior member is
A first exterior member that covers the battery element from one side;
A second exterior member that covers the battery element from the other side,
The window portion is formed by bonding a part of the first exterior member and a part of the second exterior member to each other via a film-like window member containing the non-porous molten fluororesin. Being
The secondary battery according to (1) or (2) above.
(8)
The window member is attached to each of the first exterior member and the second exterior member via an adhesive.
The secondary battery according to (7) above.
(9)
The window member has a thickness of 10 μm or more and 500 μm or less,
The secondary battery according to (7) or (8) above.
(10)
A lithium ion secondary battery,
The secondary battery according to any one of (1) to (9).
(11)
The secondary battery according to any one of (1) to (10) above;
A control unit for controlling the operation of the secondary battery;
A battery pack comprising: a switch unit that switches the operation of the secondary battery in accordance with an instruction from the control unit.
(12)
The secondary battery according to any one of (1) to (10) above;
A conversion unit that converts electric power supplied from the secondary battery into driving force;
A drive unit that is driven according to the drive force;
An electric vehicle comprising: a control unit that controls the operation of the secondary battery.
(13)
The secondary battery according to any one of (1) to (10) above;
One or more electric devices supplied with electric power from the secondary battery;
And a control unit that controls power supply from the secondary battery to the electrical device.
(14)
The secondary battery according to any one of (1) to (10) above;
A power tool comprising: a movable part to which electric power is supplied from the secondary battery.
(15)
An electronic device comprising the secondary battery according to any one of (1) to (10) as a power supply source.

This application claims priority on the basis of Japanese Patent Application No. 2016-244512 filed on December 16, 2016 at the Japan Patent Office. The entire contents of this application are hereby incorporated by reference. Incorporated into.

Those skilled in the art will envision various modifications, combinations, sub-combinations, and changes, depending on design requirements and other factors, which are within the scope of the appended claims and their equivalents. Is understood to be included.

Claims

A battery element comprising a positive electrode, a negative electrode and an electrolyte;
A secondary battery comprising the battery element and a film-shaped exterior member having a window portion containing a non-porous molten fluororesin.
The non-porous molten fluororesin includes non-porous tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), non-porous tetrafluoroethylene / hexafluoropropylene copolymer (FEP), and non-porous tetrafluoro. Including at least one ethylene / ethylene copolymer (ETFE),
The secondary battery according to claim 1.
The exterior member has an opening,
The window portion is formed by covering at least the opening with a film-like window member containing the non-porous molten fluororesin,
The secondary battery according to claim 1.
The window member has an area larger than the area of the opening, and is attached to the exterior member via an adhesive.
The secondary battery according to claim 3.
A protective layer containing a material having air permeability is provided on the window member.
The secondary battery according to claim 3.
The window member has a thickness of 10 μm or more and 500 μm or less,
The secondary battery according to claim 3.
The exterior member is
A first exterior member that covers the battery element from one side;
A second exterior member that covers the battery element from the other side,
The window portion is formed by bonding a part of the first exterior member and a part of the second exterior member to each other through a film-like window member containing the non-porous molten fluororesin. Being
The secondary battery according to claim 1.
The window member is attached to each of the first exterior member and the second exterior member via an adhesive.
The secondary battery according to claim 7.
The window member has a thickness of 10 μm or more and 500 μm or less,
The secondary battery according to claim 7.
A lithium ion secondary battery,
The secondary battery according to claim 1.
A secondary battery,
A control unit for controlling the operation of the secondary battery;
A switch unit for switching the operation of the secondary battery according to an instruction from the control unit,
The secondary battery is
A battery element comprising a positive electrode, a negative electrode and an electrolyte;
A battery pack including the battery element and a film-shaped exterior member having a window portion containing a non-porous molten fluororesin.
A secondary battery,
A conversion unit that converts electric power supplied from the secondary battery into driving force;
A drive unit that is driven according to the drive force;
A control unit for controlling the operation of the secondary battery,
The secondary battery is
A battery element comprising a positive electrode, a negative electrode and an electrolyte;
An electric vehicle including the battery element and a film-shaped exterior member having a window portion containing a non-porous molten fluororesin.
A secondary battery,
One or more electric devices supplied with electric power from the secondary battery;
A control unit for controlling power supply from the secondary battery to the electrical device,
The secondary battery is
A battery element comprising a positive electrode, a negative electrode and an electrolyte;
A power storage system comprising: the battery element; and a film-shaped exterior member having a window portion containing a non-porous molten fluororesin.
A secondary battery,
A movable part to which power is supplied from the secondary battery,
The secondary battery is
A battery element comprising a positive electrode, a negative electrode and an electrolyte;
A power tool including the battery element and a film-shaped exterior member having a window portion containing a non-porous molten fluororesin.
A secondary battery is provided as a power supply source,
The secondary battery is
A battery element comprising a positive electrode, a negative electrode and an electrolyte;
An electronic device comprising the battery element and a film-shaped exterior member having a window portion containing a non-porous molten fluororesin.