JP4465578B2 - Negative electrode for lithium ion secondary battery, lithium ion secondary battery, and production method thereof - Google Patents

Description

【００９７】
表１から分かるように、実施例１〜３によれば、圧延銅箔を用いた比較例１よりも高い容量維持率が得られた。これは従来の圧延箔とは異なり、表面粗さの小さい鏡面研磨ガラスまたはアラミドよりなる成膜用基体２１Ａの上に負極集電体層２１Ｃを形成したことで、良好なリチウム析出溶解面が得られたためであると考えらえる。
【００９８】
また、実施例１〜３によれば、拡散防止層をクロムにより構成した比較例２，３よりも高い容量維持率が得られた。比較例２，３では、リチウムが銅よりなる負極集電体層、更にクロムよりなる拡散防止層を透過し、成膜用基体または負極集電体の破壊が起こるので、集電機能が低下してしまい、サイクル中に急激な容量劣化が観察された。サイクル後に実施例１〜３および比較例２，３の負極２１を解体したところ、比較例２，３では負極の破壊が観察されたが，実施例１〜３では観察されなかった。
【００９９】
すなわち、成膜用基体２１Ａに負極集電体層２１Ｃを形成し、その間にチタンまたはタンタルよりなる拡散防止層２１Ｂを設けるようにすれば、負極２１の長期安定性を向上させることができ、電池の長期安定性を向上させ、サイクル特性を向上させることができることが分かった。
【０１００】
（参考例４）
第３の実施の形態において説明した二次電池を作製した（図３参照）。その際、拡散防止層２１Ｂおよび負極集電体層２１Ｃに代えて、チタンよりなる厚み５００ｎｍの負極集電体層３１Ｃを形成したことを除き、他は実施例１と同様とした。作製した参考例４の二次電池についても、実施例１〜３と同様にして充放電を行い、３０サイクル目の容量維持率を調べた。その結果を実施例１および比較例１，２の結果と共に表２に示す。
【０１０１】
【表２】

【０１０２】
表２から分かるように、参考例４の容量維持率は実施例１とほぼ同じであり、比較例１，２よりも高い値が得られた。参考例４についてもサイクル後に負極３１を解体したところ、負極３１の破壊は観察されなかった。すなわち、負極集電体層３１Ｃをチタンまたはタンタルにより構成し、拡散防止機能を持たせるようにしても、負極３１の長期安定性を向上させることができ、電池の長期安定性を向上させ、サイクル特性を向上させることができることが分かった。
【０１０３】
（実施例５）
第４の実施の形態において説明した二次電池を作製した（図５参照）。その際、負極活物質層２１Ｄの上に、リン酸リチウムを原材料として用い、窒素ガス雰囲気中において高周波反応性スパッタ法を行うことにより、窒化ホスホリルリチウム（ＬｉＰＯＮ）よりなる厚み１μｍのリチウムイオン伝導性を有する無機化合物層４１Ｆを形成した。他は実施例１と同様とした。また、本実施例に対する比較例４として、拡散防止層２１Ｂをクロムにより形成したことを除き、実施例５と同様にして二次電池を作製した。作製した実施例５および比較例４の二次電池についても、実施例１〜３と同様にして充放電を行い、３０サイクル目の容量維持率を調べた。その結果を実施例１および比較例２の結果と共に表３に示す。
【０１０４】
【表３】

【０１０５】
表３から分かるように、無機化合物層４１Ｆを形成した実施例５によれば、実施例１よりも更に容量維持率を向上させることができた。これに対して、拡散防止層にクロムを用いた比較例４では、無機化合物層を形成したことによる容量維持率の向上は見られるものの、比較例２と同様に、負極の破壊に起因する容量維持率の大きな劣化が見られた。すなわち、成膜用基体２１Ａにチタンまたはタンタルよりなる拡散防止層２１Ｂおよび負極集電体層２１Ｃを形成し、更に無機化合物層４１Ｆを設けるようにすれば、サイクル特性をより向上させることができることが分かった。
【０１０６】
以上、実施の形態および実施例を挙げて本発明を説明したが、本発明は上記実施の形態および実施例に限定されるものではなく、種々変形可能である。例えば、上記実施の形態および実施例では、負極２１，３１，４１，５１，７１と正極２２，６２とを積層した単層型の二次電池について説明したが、負極と正極とを積層し、巻回した巻回型の二次電池、あるいは負極と正極とを複数積層した積層型の二次電池についても同様に適用することができる。
【０１０７】
また、上記実施の形態および実施例では、フィルム状の外装部材に電池素子を封入した二次電池について説明したが、他の形状、例えばいわゆる円筒型、角型、コイン型、ボタン型あるいはカード型などの二次電池についても適用することができる。
【０１０９】
【発明の効果】
以上説明したように、本発明のリチウムイオン二次電池用負極、またはリチウムイオン二次電池によれば、チタンあるいはタンタルよりなる拡散防止層を備えるようにしたので、リチウムが成膜用基体に拡散することを抑制することができ、リチウムの拡散による成膜用基体の破壊および負極集電体層の脱落を防止することができる。よって、長期安定性を向上させることができ、長寿命化を図ることができる。
【０１１０】
特に、本発明のリチウムイオン二次電池用負極、またはリチウムイオン二次電池、またはリチウムイオン二次電池用負極の製造方法、またはリチウムイオン二次電池の製造方法では、成膜用基体の上に乾式成膜法あるいは湿式成膜法により負極集電体層を形成すれば、負極の薄膜化および表面の平坦性向上を図ることができる。よって、薄膜化により電池のエネルギー密度を向上させることができると共に、平坦性向上により電極反応を促進させることができ、特性を向上させることができる。
【０１１１】
また、リチウムイオン二次電池用負極、またはリチウムイオン二次電池では、無機化合物層を更に備えれば、均一な電極反応をより促進させ、充放電効率を向上させることができる。また、負極と電解質との反応を抑制することができ、電解質の選択肢が広がることにより、電池の性能を高めることができると共に、反応による容量劣化を防止することができる。
【０１１２】
更に、リチウムイオン二次電池、またはリチウムイオン二次電池の製造方法では、正極および電解質を乾式成膜法あるいは湿式成膜法により形成すれば、均一な電極反応をより促進させ、充放電効率を向上させることができると共に、電池をより薄膜化することができ、エネルギー密度をより向上させることができる。また、正極にバインダーを用いないので、良好な負荷特性を得ることができる。更に、他のデバイスとの併用も可能となり、リチウムイオン二次電池の形成基体の選択肢を広げることができる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態に係る二次電池の構成を表す断面図である。
【図２】本発明の第２の実施の形態に係る二次電池の組み立て時の構成を表す断面図である。
【図３】本発明の第３の実施の形態に係る二次電池の構成を表す断面図である。
【図４】本発明の第３の実施の形態に係る二次電池の変形例を表す組み立て時の断面図である。
【図５】本発明の第４の実施の形態に係る二次電池の構成を表す断面図である。
【図６】本発明の第４の実施の形態に係る二次電池の変形例を表す組み立て時の断面図である。
【図７】本発明の第４の実施の形態に係る二次電池の他の変形例を表す断面図である。
【図８】本発明の第４の実施の形態に係る二次電池の他の変形例を表す組み立て時の断面図である。
【図９】本発明の第５の実施の形態に係る二次電池の構成を表す断面図である。
【図１０】本発明の第５の実施の形態に係る二次電池の変形例を表す組み立て時の断面図である。
【図１１】本発明の第５の実施の形態に係る二次電池の他の変形例を表す断面図である。
【図１２】本発明の第５の実施の形態に係る二次電池の他の変形例を表す組み立て時の断面図である。
【符号の説明】
１０…外装部材、２０，３０，４０，５０，６０，７０…電池素子、２１，３１，４１，５１，７１…負極、２１Ａ…成膜用基体、２１Ｂ…拡散防止層，２１Ｃ，３１Ｃ…負極集電体層、２１Ｄ…負極活物質層、２１Ｅ…負極端子、２２，６２…正極、２２Ａ…正極集電体、２２Ｂ，６２Ｂ…正極活物質層、２２Ｃ…正極端子、２３，６３…電解質、４１Ｆ…無機化合物層、６２Ａ…正極集電体層。[0001]
BACKGROUND OF THE INVENTION
  In the present invention, a negative electrode current collector layer is provided on a film forming substrate.For lithium ion secondary batteryNegative electrode, and thisThisUsedLithium ion secondaryThe present invention relates to batteries and methods for manufacturing them.
[0002]
[Prior art]
In recent years, there has been an increasing demand for high-performance secondary batteries that are small and have high energy density as power sources for portable devices such as mobile phones, notebook PCs, handy cams, and PDAs. Currently, high-performance secondary batteries that are generally used include lithium ion secondary batteries that use a lithium transition metal oxide capable of removing and inserting lithium ions for the positive electrode and carbon for the negative electrode. However, since this lithium ion secondary battery uses carbon for the negative electrode, the high energy density inherent in lithium (Li) cannot be sufficiently achieved, and there is a need for an alternative high capacity energy device. It is getting bigger.
[0003]
On the other hand, even in the same lithium-based secondary battery, it is possible to obtain a higher energy density than a lithium ion secondary battery using carbon for the negative electrode, and an alloy that uses lithium and an intermetallic compound is used for the negative electrode In addition, those using metallic lithium for the negative electrode and utilizing the precipitation / dissolution reaction of lithium have attracted attention. If such a secondary battery can be put to practical use, the negative electrode can be made thinner and the energy density can be further improved as compared with a negative electrode using carbon.
[0004]
However, for example, in a secondary battery using a high-capacity alloy for the negative electrode, the active material undergoes severe expansion / contraction during charging / discharging, so the negative electrode becomes finer due to pulverization, resulting in lower current collection and increased surface area. The decomposition reaction of the electrolyte solution caused by this is accelerated, and the cycle characteristics are extremely poor.
[0005]
In addition, despite the fact that lithium secondary batteries with metal lithium precipitation / dissolution reactions have been studied for a long time, various problems still remain and it is difficult to put them into practical use. One reason for this is that non-uniform lithium deposition occurs with charge / discharge cycles, resulting in the formation of needle-like crystals of metallic lithium. When this acicular crystal is formed, the grown acicular crystal falls off, and not only the battery life is remarkably reduced, but also the possibility of causing an internal short circuit is increased, which is a major problem in terms of performance and safety. In addition, metal lithium is very reactive, and problems such as reaction with the electrolyte and safety of deposited metal lithium occur.
[0006]
In addition, negative electrodes using metallic lithium generally use a lithium foil formed by rolling, but it is difficult to reduce the thickness of the lithium foil by rolling, and when using a rolled lithium foil, a high energy density is required. The merit of becoming smaller becomes smaller. In addition, since the rolled lithium foil often has irregularities formed on the surface due to rolling marks, there is a problem that an unreproducible oxide film is formed on the surface of the rolled lithium foil. Furthermore, recently, lithium secondary batteries using polymer electrolytes have been studied from the viewpoint of safety and the like. However, when such a rolled lithium foil is used, there are problems such as contact between the negative electrode and the electrolyte. It will occur.
[0007]
Therefore, in order to solve these problems, a metal lithium layer is formed by a dry film forming method, and further, an inorganic compound layer having lithium ion conductivity is formed on the metal lithium layer by a dry film forming method. Attempts have been made (see, for example, Patent Document 1). Further, when the metal lithium layer is formed on the rolled metal current collector foil, the surface property of the rolled metal current collector foil is inherited by the metal lithium layer, a smooth surface cannot be obtained, and the coating effect by the inorganic compound layer is small. Therefore, it has been studied to form a negative electrode current collector layer on a film-forming substrate having excellent surface properties by a thin film deposition method (see, for example, Patent Document 2). For example, in Patent Document 2, a negative electrode current collector layer is formed on a plastic film by using copper (Cu), stainless steel, nickel (Ni), zinc (Zn), chromium (Cr), or an alloy thereof. A metal lithium layer is formed on the substrate.
[0008]
[Patent Document 1]
JP 2002-141058 A
[Patent Document 2]
US Pat. No. 6,025,094
[0009]
[Problems to be solved by the invention]
However, since copper and stainless steel have poor adhesion to plastic, when the negative electrode current collector layer is formed by them, there is a problem that the negative electrode current collector layer is easily peeled off. In addition, since zinc forms an alloy with lithium and chromium permeates or diffuses lithium, when these are formed as a negative electrode current collector layer, the negative electrode current collector layer expands due to the reaction with lithium, peels off, or is formed. There was a problem that the membrane substrate was destroyed. Therefore, the negative electrode in which the negative electrode current collector layer is formed on the substrate for film formation has a problem that long-term stability is low and cycle characteristics are greatly deteriorated.
[0010]
  The present invention has been made in view of such problems, and the object thereof is to improve long-term stability.For lithium ion secondary batteryNegative electrode and using thisLithium ion secondaryIt is in providing a battery and a manufacturing method thereof.
[0011]
[Means for Solving the Problems]
  According to the inventionFor lithium ion secondary batteryThe negative electrode is a film-forming substrate, a negative-electrode current collector layer provided on the film-forming substrate, and a diffusion made of titanium or tantalum provided between the negative-electrode current collector layer and the film-forming substrate. And a prevention layer.
[0013]
  According to the inventionLithium ion secondaryThe battery includes an electrolyte along with a positive electrode and a negative electrode,The negative electrode is a film-forming substrate, a negative-electrode current collector layer provided on the film-forming substrate, and a diffusion made of titanium or tantalum provided between the negative-electrode current collector layer and the film-forming substrate. And a prevention layer.
[0015]
  According to the inventionFor lithium ion secondary batteryThe negative electrode manufacturing method includes a step of forming a diffusion prevention layer made of titanium or tantalum on a substrate for film formation by a dry film formation method or a wet film formation method, and a dry film formation on the diffusion prevention layer. And a step of forming a negative electrode current collector layer by a wet film forming method.
[0017]
  According to the inventionLithium ion secondaryThe battery manufacturing method includes an electrolyte together with a positive electrode and a negative electrodeLithium ion secondarybatteryofManufacturingThe process isA step of forming a diffusion prevention layer made of titanium or tantalum on a substrate for film formation by a dry film formation method or a wet film formation method, and a dry film formation method or a wet film formation method on the diffusion prevention layer And a step of forming a negative electrode current collector layer.
[0019]
  According to the inventionFor lithium ion secondary batteryNegative electrode,And lithium ion secondaryIn batteries, diffusion prevention made of titanium or tantalumIn layersThan,lithiumDiffusion is suppressed, and peeling of the negative electrode current collector layer or destruction of the substrate for film formation is prevented. Therefore, stability is improved.
[0020]
  According to the inventionFor lithium ion secondary batteryNegative electrode manufacturing method andLithium ion secondaryIn the battery manufacturing method, a diffusion prevention layer and a negative electrode current collector layer are formed on a film forming substrate by a dry film forming method or a wet film forming method.. YoOf the present inventionFor lithium ion secondary batteryNegative electrode andLithium ion secondaryThe battery can be easily obtained, the smoothness of the negative electrode surface is improved, and the characteristics are improved.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0022]
[First Embodiment]
FIG. 1 shows the configuration of the secondary battery according to the first embodiment of the present invention. In this secondary battery, a battery element 20 is enclosed in a film-like exterior member 10. The exterior member 10 is made of, for example, a laminate film in which a nylon film, an aluminum (Al) foil, and a polyethylene film are bonded together in this order. The exterior member 10 is disposed, for example, so that the polyethylene film side faces the battery element 20, and the outer edge portion is closely attached by fusion or an adhesive. In addition, the exterior member 10 may be configured by a laminate film having another structure or a polymer film such as polypropylene instead of the above-described laminate film.
[0023]
In the battery element 20, a negative electrode 21 and a positive electrode 22 are arranged to face each other with an electrolyte 23 interposed therebetween. In the negative electrode 21, a diffusion prevention layer 21B, a negative electrode current collector layer 21C, and a negative electrode active material layer 21D are laminated in this order on a film formation base 21A. A negative electrode terminal 21E is formed on the negative electrode current collector layer 21C. It has an attached structure.
[0024]
The film-forming substrate 21A is used for forming the diffusion preventing layer 21B, the negative electrode current collector layer 21C, and the negative electrode active material layer 21D, and the better the film forming property, the smaller the surface roughness of the film forming surface. Is preferable. Examples of the material constituting the film formation base 21A include a semiconductor such as silicon (Si), aluminum oxide (Al₂O_Three), Altic (Al₂O_Three-TiC) or ceramics such as magnesium oxide (MgO), glass, or plastic is preferred.
[0025]
Among these, plastics can easily form a thin film-forming substrate 21A, can provide high flexibility, and can have a negative electrode active surface that has a better surface than a rolled metal foil by reducing the surface roughness. The material layer 21D is preferable because it can be easily formed. Specific examples include polypropylene, polyethylene, polyethylene terephthalate, polyimide, aramid, polyethylene-2,6-naphthol, polycarbonate, or polyvinyl chloride, but other conditions may be used depending on conditions such as thinness or surface properties. A plastic material may be used.
[0026]
In the case where the film forming substrate 21A is made of a plastic film, although not shown, the film forming substrate 21A may be used as an exterior member.
[0027]
The diffusion preventing layer 21B is made of titanium (Ti) or tantalum (Ta), and is for preventing lithium from diffusing into the film forming base 21A. The diffusion prevention layer 21B is only required to be provided between the film forming substrate 21A and the negative electrode current collector layer 21C, and although not shown, other diffusion layers 21B are provided between the film forming substrate 21A or the negative electrode current collector layer 21C. A layer may be inserted. However, since titanium and tantalum have good adhesion to glass or plastic, and also have low reactivity and permeability with metallic lithium, as shown in FIG. 1, the film-forming substrate 21A and the negative electrode current collector layer It may be in contact with 21C.
[0028]
Since the negative electrode current collector layer 21C has a current collecting function, it is not preferable to have a violent reaction with lithium. This is because if a metal that is highly reactive with lithium and easily alloyed is used, the volume expands and contracts with charge and discharge, and the anode current collector layer 21C is destroyed. However, since the secondary battery includes the diffusion preventing layer 21B, a material that causes some reaction or permeation may be used. As a material constituting the anode current collector layer 21C, for example, copper, nickel, molybdenum (Mo), titanium, tantalum, an alloy containing at least one of them, or stainless steel is preferable. Among these, copper is preferable because it is inexpensive and easy to form a film, although it has been confirmed that diffusion and permeation of lithium can occur.
[0029]
The negative electrode active material layer 21 </ b> D is made of metallic lithium or a material capable of inserting and extracting lithium. Examples of materials capable of inserting and extracting lithium include magnesium (Mg), aluminum, silicon (Si), calcium (Ca), zinc, gallium (Ga), silver (Ag), indium (In), and tin (Sn). ), Barium (Ba), lead (Pb), bismuth (Bi), and those containing at least one of the group consisting of compounds containing at least one of these.
[0030]
The negative electrode terminal 21 </ b> E is made of, for example, a metal material such as aluminum, copper, or nickel, and one end thereof is led out from the exterior member 10.
[0031]
The positive electrode 22 has a configuration in which, for example, a positive electrode current collector 22A and a positive electrode active material layer 22B are stacked, and a positive electrode terminal 22C is attached to the positive electrode current collector 22A. The positive electrode current collector 22A is made of, for example, a metal foil such as an aluminum foil. The positive electrode active material layer 22B includes, for example, a positive electrode active material, a conductive agent such as carbon black or graphite, and a binder such as polyvinylidene fluoride. Further, the positive electrode active material layer 22B may be constituted by, for example, a thin film of a positive electrode active material formed on the positive electrode current collector 22A.
[0032]
As the positive electrode active material, for example, a lithium-containing compound such as a lithium transition metal composite oxide or a lithium-containing phosphate compound is preferable. Among these, a lithium transition metal composite oxide and a lithium-containing phosphate compound are preferable because a high energy density can be obtained. Examples of the lithium transition metal composite oxide include the chemical formula Li_xMO₂The thing represented by is mentioned. In the formula, M represents one or more transition metal elements, and particularly preferably includes at least one selected from the group consisting of cobalt (Co), nickel, and manganese (Mn). The value of x varies depending on the charge / discharge state of the battery, and is generally 0.05 ≦ x ≦ 1.12. Specific examples of such lithium transition metal oxides include LiCoO.₂, LiNiO₂, Li_yNi_zCo_1-zO₂(Y and z differ depending on the charge / discharge state of the battery, and usually 0 <y <1, 0.7 <z <1.02) or LiMn having a spinel structure₂O_FourEtc.
[0033]
The positive electrode terminal 22 </ b> C is made of, for example, a metal material such as aluminum, copper, or nickel, and one end thereof is led out from the exterior member 10. In FIG. 1, the positive electrode terminal 22C and the negative electrode terminal 21E are drawn so as to be positioned up and down on the paper surface.
[0034]
Examples of the electrolyte 23 include an electrolyte that is a liquid electrolyte, a so-called gel electrolyte in which an electrolyte is held in a polymer compound, a polymer electrolyte in which an electrolyte salt is dispersed in a polymer compound having ion conductivity, or And a mixture of these and an inorganic solid electrolyte. Thus, by including an electrolytic solution, a gel electrolyte, or a polymer electrolyte, the contact between the negative electrode 21 and the positive electrode 22 and the electrolyte 23 can be improved, and the flexibility of the battery itself is increased. This is preferable.
[0035]
As the electrolytic solution, for example, a solution obtained by dissolving a lithium salt as an electrolyte salt in a nonaqueous solvent such as an organic solvent is preferable. Examples of the solvent include propylene carbonate, ethylene carbonate, diethyl carbonate, methyl ethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4 -Methyl-1,3-dioxolane, diethyl ether, sulfolane, methyl sulfolane, acetonitrile, propyl nitrile, anisole, acetate or propionate. Any one of the solvents may be used alone, or two or more may be mixed and used.
[0036]
Examples of the lithium salt include LiClO._Four, LiAsF₆, LiPF₆, LiBF_Four, LiB (C₆H_Five)_Four, LiCH_ThreeSO_Three, LiCF_ThreeSO_Three, LiCl or LiBr, any one of which may be used alone, or two or more of them may be mixed and used.
[0037]
Examples of the polymer compound of the gel electrolyte include polyvinylidene fluoride, polyethylene oxide, polypropylene oxide, polyacrylonitrile, polymethacrylonitrile, and those containing these in a repeating unit. In particular, a fluorine-based polymer compound is desirable from the viewpoint of redox stability.
[0038]
Examples of the polymer compound of the polymer electrolyte include those having an ether bond represented by polyethylene oxide. Examples of the electrolyte salt include the lithium salts described above.
[0039]
Examples of the inorganic solid electrolyte include lithium fluoride (LiF), lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI), and lithium nitride (Li_ThreeN), lithium oxide (Li₂O), lithium phosphate (Li_ThreePO_Four), Lithium silicate (Li_FourSiO_Four), Lithium sulfide (Li₂S), lithium phosphide (Li_ThreeP), lithium carbonate (Li₂CO_Three), Lithium sulfate (Li₂SO_Four) Or phosphoryllithium nitride (LiPON).
[0040]
Although not shown, a separator may be provided between the negative electrode 21 and the positive electrode 22 as necessary. For example, when the electrolyte 23 is composed of an electrolytic solution or a gel electrolyte, it is preferable to provide a separator. In this case, for example, the separator is impregnated with the electrolyte 23.
[0041]
The secondary battery having such a configuration can be manufactured, for example, as follows.
[0042]
First, a dry film forming method such as a sputtering method, a vacuum evaporation method, a laser ablation method, an ion plating method, or a CVD (Chemical Vapor Deposition) method is formed on the film forming substrate 21A whose surface has been polished and cleaned. Alternatively, the diffusion prevention layer 21B is formed by a wet film formation method such as an electrolytic plating method or an electroless plating method. This is preferable because a diffusion preventing layer 21B having high flatness can be easily obtained. When the electrolytic plating method is used, a plating base having electron conductivity may be formed in advance on the film forming base 21A.
[0043]
Next, for example, the negative electrode current collector layer 21C is formed on the diffusion prevention layer 21B by the dry film formation method or the wet film formation method described above. This is preferable because a thin negative electrode current collector layer 21C having high flatness can be easily obtained. The negative electrode current collector layer 21C is preferably formed continuously after the diffusion prevention layer 21B is formed, without being exposed to the atmosphere. It is not necessary to form a film. When the electrolytic plating method is used, a plating base may be formed in advance on the film formation base 21A, but the diffusion prevention layer 21B may be used as the plating base. The wet film formation method, particularly the electrolytic plating method, has a high film formation rate, and is advantageous when forming the negative electrode current collector layer 21C in a film thickness of μm. Therefore, after the negative electrode current collector layer 21C is continuously thinly formed on the diffusion prevention layer 21B by a dry film forming method, the negative electrode current collector layer 21C may be thickened by an electrolytic plating method. In this case, the material of the negative electrode current collector layer 21C may be the same or different between the dry film formation method and the wet film formation method.
[0044]
Subsequently, the negative electrode active material layer 21D is formed on the negative electrode current collector layer 21C. For example, when the anode active material layer 21D is formed of metallic lithium, it is preferably formed by a dry film forming method, and in particular, a vacuum evaporation method or an ion plating method is preferable. This is because the activity of metallic lithium is very high. For example, when the anode active material layer 21D is formed of a material capable of inserting and extracting lithium, the anode active material layer 21D is formed by the dry film forming method or the wet film forming method described above. This is preferable because it can be made thinner than the conventional rolled lithium foil and the flatness of the surface can be increased.
[0045]
After that, the negative electrode terminal 21E is attached to the negative electrode current collector layer 21C to form the negative electrode 21.
[0046]
Further, for example, a positive electrode active material, a conductive agent, and a binder are mixed to prepare a positive electrode mixture, which is applied to the positive electrode current collector 22A to form the positive electrode active material layer 22B. Alternatively, the positive electrode active material layer 22B is formed on the positive electrode current collector 22A by the dry film formation method described above. Next, the positive electrode terminal 22C is attached to the positive electrode current collector 22A, and the positive electrode 22 is formed.
[0047]
After that, the negative electrode 21 and the positive electrode 22 are stacked with the negative electrode active material layer 21 </ b> D side and the positive electrode active material layer 22 </ b> B side facing each other via the electrolyte 23, and enclosed in the exterior member 10. The electrolyte 23 may be impregnated in a separator (not shown) interposed between the negative electrode 21 and the positive electrode 22, or may be formed by applying to at least one of the negative electrode 21 and the positive electrode 22. Alternatively, the negative electrode 21 and the positive electrode 22 may be formed on a substrate (not shown). Further, as described above, the film forming substrate 21A may be used as the exterior member 10 by forming the film forming substrate 21A from a plastic film. Thereby, the secondary battery shown in FIG. 1 is completed.
[0048]
This secondary battery works as follows, for example.
[0049]
In the secondary battery, when charged, for example, lithium ions are released from the positive electrode 22 and are deposited or occluded in the negative electrode 21 through the electrolyte 23. For example, when the negative electrode active material layer 21D is composed of metallic lithium, the negative electrode active material layer 21D is deposited on the negative electrode active material layer 21D as metallic lithium, and the negative electrode active material layer 21D is composed of a material capable of inserting and extracting lithium. In this case, the negative electrode active material layer 21D is occluded. When discharging is performed, for example, metallic lithium is eluted from the negative electrode 21 as ions, or lithium ions are released and inserted into the positive electrode 22 through the electrolyte 23.
[0050]
In this secondary battery, metallic lithium or a lithium compound that is highly active in a charged state is present on the anode current collector layer 21C, but has a diffusion prevention layer 21B made of titanium or tantalum, so that lithium is not formed. Diffusion to the film substrate 21A is suppressed. Therefore, the film-forming substrate 21A is prevented from being destroyed by the diffusion of lithium, or the negative electrode current collector layer 21C is prevented from falling off. Further, since the flatness of the surface of the negative electrode active material layer 21D is high, uniform precipitation / dissolution reaction of metallic lithium is promoted or lithium occlusion / desorption reaction is promoted as compared with the case of using a rolled metal foil. Promoted.
[0051]
As described above, in the present embodiment, since the negative electrode 21 is provided with the diffusion preventing layer 21B made of titanium or tantalum, it is possible to suppress the diffusion of lithium into the film forming base 21A. It is possible to prevent the film-forming substrate 21A from being broken and the negative electrode current collector layer 21C from falling off. Therefore, long-term stability can be improved and a long life can be achieved.
[0052]
In particular, if the diffusion prevention layer 21B, the negative electrode current collector layer 21C, and the negative electrode active material layer 21D are formed on the film formation base 21A by a dry film formation method or a wet film formation method, Thinning and surface flatness can be improved. Therefore, the energy density of the battery can be improved by reducing the thickness, the electrode reaction can be promoted by improving the flatness, and the characteristics can be improved.
[0053]
Further, if the film forming base 21A is made of plastic, it can be easily thinned, and high flexibility can be obtained, and the film forming base 21A can be used as an exterior member. . Therefore, the battery design options can be expanded.
[0054]
[Second Embodiment]
FIG. 2 shows a configuration when the secondary battery according to the second embodiment of the present invention is assembled. This secondary battery does not include the negative electrode active material layer 21D at the time of assembly, and metal lithium is deposited on the negative electrode current collector layer 21C at the time of charging, so that the negative electrode active material layer 21D made of metal lithium is formed. Except for this, it has the same configuration, operation, and effect as the first embodiment. Further, it can be manufactured in the same manner as in the first embodiment. Therefore, here, the same reference numerals are given to the same components, and detailed description thereof is omitted.
[0055]
[Third Embodiment]
FIG. 3 shows a configuration of a secondary battery according to the third embodiment of the present invention. This secondary battery has the same configuration, operation, and effect as in the first embodiment, except that the battery element 30 having a different configuration of the negative electrode 31 is provided instead of the battery element 20 in the first embodiment. have. Further, it can be manufactured in the same manner as in the first embodiment. Therefore, here, the same reference numerals are given to the same components, and detailed description thereof is omitted.
[0056]
The negative electrode 31 includes a negative electrode current collector layer 31C made of titanium or tantalum, instead of the diffusion prevention layer 21B and the negative electrode current collector layer 21C in the first embodiment. Others are the same as those of the negative electrode 21 of the first embodiment. That is, the present embodiment corresponds to the case where the diffusion prevention layer 21B and the negative electrode current collector layer 21C in the first embodiment are made of the same material, and the negative electrode current collector layer 31C also has a diffusion prevention function. It is what you have.
[0057]
Note that in the secondary battery according to the second embodiment, as shown in FIG. 4, a negative electrode current collector layer 31C made of titanium or tantalum is used instead of the diffusion prevention layer 21B and the negative electrode current collector layer 21C. You may make it provide.
[0058]
[Fourth Embodiment]
FIG. 5 shows the structure of a secondary battery according to the fourth embodiment of the present invention. This secondary battery has the same configuration, operation, and effects as those of the first embodiment except that the battery element 20 in the first embodiment is replaced by a battery element 40 having a different configuration of the negative electrode 41. And can be manufactured in the same manner as in the first embodiment. Therefore, here, the same reference numerals are given to the same components, and detailed description thereof is omitted.
[0059]
The negative electrode 41 includes an inorganic compound layer 41F having ion conductivity on the electrolyte 23 side of the negative electrode active material layer 21D. Others are the same as those of the negative electrode 21 in the first embodiment. The inorganic compound layer 41F promotes the uniform precipitation / dissolution reaction of metallic lithium or the uniform storage / release reaction of lithium in the negative electrode active material layer 21D, and prevents the metallic lithium from growing in a needle shape. Is. Further, by covering the surface of the negative electrode active material layer 21D, the reaction between the electrolyte 23 and the negative electrode active material layer 21D is suppressed. In particular, in this embodiment, since the surface of the negative electrode active material layer 21D is flattened, the surface coating effect by the inorganic compound layer 41F and the leveling effect of the lithium deposition interface are large.
[0060]
The inorganic compound layer 41F preferably has a good film quality with few cracks and pinholes, and preferably has a certain degree of flexibility. As a material constituting the inorganic compound layer 41F, for example, a material that can be thinned and has as high an ionic conductivity as possible is preferable. For example, the lithium ion conductivity is 1 × 10^-8S / cm or more is preferable. However, as long as the coating effect is high, a lithium ion conductivity smaller than this may be used. In addition, since the inorganic compound layer 41F is in direct contact with the highly active negative electrode active material layer 21D, it is preferable that the inorganic compound layer 41F does not react with metallic lithium, or the reaction product with metallic lithium does not have electronic conductivity. In addition, since the inorganic compound layer 41F is not in direct contact with the positive electrode 22, unlike the case where an ion conductive inorganic compound is used as the electrolyte 23, it is not necessary to have a high decomposition voltage.
[0061]
As a preferable material constituting the inorganic compound layer 41F, for example, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium nitride, lithium oxide, lithium phosphate, lithium silicate, lithium sulfide, lithium phosphide, Examples include those containing at least one member selected from the group consisting of lithium carbonate, lithium sulfate, and phosphoryl lithium nitride. For example, any one or two or more of these may be used, and silicon sulfide (SiS) may be used to improve ion conductivity.₂), Silicon dioxide (SiO2)₂), Phosphorus sulfide (P₂S_Five) Or phosphorus oxide (P₂O_Five) And other compounds may be added. As those containing two or more of these, a solid solution of lithium phosphate and lithium silicate (Li_ThreePO_Four-Li_FourSiO_Four) And the like, and those containing other compounds include solid solutions of lithium sulfide and phosphorus sulfide (Li₂SP₂S_Five) Or a solid solution of lithium sulfide and silicon sulfide (Li₂S-SiS₂) And the like.
[0062]
A preferable material constituting the inorganic compound layer 41F also includes a material containing a lithium compound containing at least one of the above-described lithium compounds as a raw material. An example of such a lithium compound is phosphoryllithium nitride obtained by performing reactive sputtering in a nitrogen gas atmosphere using lithium phosphate as a raw material.
[0063]
The material constituting the inorganic compound layer 41F is preferably amorphous, but may be crystalline. In addition, these materials are not limited to stoichiometric compositions, and may be non-stoichiometric compositions.
[0064]
This inorganic compound layer 41F can be formed as follows, for example. For example, when the negative electrode active material layer 21D is metallic lithium, it is formed on the negative electrode active material layer 21D by a dry film forming method such as sputtering, vacuum deposition, laser ablation, ion plating, or CVD. Film. By using such a dry film forming method, a dense and level compound thin film can be formed with good control, so that the interface between the anode active material layer 21D and the inorganic compound layer 41F, that is, the deposition surface of metallic lithium is It is controlled to a uniform state.
[0065]
For example, when the anode active material layer 21D is made of a material capable of inserting and extracting lithium, the film may be formed by a wet film forming method such as a sol-gel method in addition to the dry film forming method described above. Good. Note that this negative electrode active material layer 21D is greatly affected by moisture and a solvent when operated as a battery, so care must be taken when using a wet film formation method. However, when baking at a relatively high temperature as in the sol-gel method, it is preferable because moisture and solvent can be sufficiently removed.
[0066]
The raw material of the inorganic compound layer 41F includes lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium nitride, lithium oxide, lithium phosphate, lithium silicate, lithium sulfide, lithium phosphide, lithium carbonate and lithium sulfate. It is preferable to use at least one member selected from the group consisting of: That is, any one or more of these may be used, or at least one of these and other materials may be used. Further, at least one of these may be used as a raw material and reacted with a reactive gas during film formation. The inorganic compound layer 41F may be formed by a film forming apparatus different from the negative electrode active material layer 21D, but may be continuously formed by the same or connected film forming apparatus.
[0067]
In this secondary battery, similarly to the first embodiment, metallic lithium is deposited on the negative electrode active material layer 21D by charging and eluted by discharging. Alternatively, lithium is occluded in the negative electrode active material layer 21D by charging and is released by discharging. At that time, the surface of the negative electrode active material layer 21D is flattened as compared with the case of using a rolled metal foil, and the inorganic compound layer 41F has a lithium ion transport number of 1 and has no concentration polarization. The uniform deposition / dissolution reaction of metallic lithium or the uniform storage / release reaction of lithium in the active material layer 21D is further promoted. Further, the inorganic compound layer 41F prevents metallic lithium from growing in a needle shape and prevents the reaction between the negative electrode active material layer 21D and the electrolyte 23.
[0068]
As described above, in this embodiment, since the negative electrode 41 further includes the inorganic compound layer 41F, in addition to the effects of the first embodiment, uniform precipitation and dissolution of metallic lithium in the negative electrode active material layer 21D. It is possible to further promote the reaction or the uniform occlusion / release reaction of lithium and improve the charge / discharge efficiency. In addition, needle-like growth of metallic lithium can be suppressed, the risk of short-circuiting can be reduced, metallic lithium can be prevented from falling off, and capacity deterioration can be reduced. In addition, the reaction between the negative electrode active material layer 21D and the electrolyte 23 can be suppressed, whereby the choice of the composition of the electrolyte 23 can be expanded, the battery performance can be improved, and the capacity deterioration due to the reaction can be prevented. it can.
[0069]
In particular, if the inorganic compound layer 41F is formed by a dry film forming method, the interface between the negative electrode active material layer 21D and the inorganic compound layer 41F can be easily controlled to be uniform, and the metallic lithium can be made uniform. It can be deposited. Therefore, it is possible to suppress the deterioration of the capacity accompanying the cycle.
[0070]
As in the second embodiment, the present embodiment also does not include the negative electrode active material layer 21D at the time of assembly, as shown in FIG. 6, for example. You may comprise so that negative electrode active material layer 21D which consists of metallic lithium may be formed by depositing metallic lithium on it.
[0071]
Similarly to the third embodiment, as shown in FIG. 7, for example, a negative electrode having a negative electrode current collector layer 31C made of titanium or tantalum instead of the diffusion prevention layer 21B and the negative electrode current collector layer 21C. A battery element 50 including 51 may be used. This is obtained by providing the secondary battery shown in FIG. 3 with the inorganic compound layer 41F of the present embodiment.
[0072]
Further, as shown in FIG. 8, for example, the negative electrode active material layer 21D is not provided at the time of assembly, and metal lithium is deposited on the negative electrode current collector layer 21C at the time of charging. While the layer 21D is formed, the battery element 50 including the negative electrode 51 having the negative electrode current collector layer 31C made of titanium or tantalum is used instead of the diffusion prevention layer 21B and the negative electrode current collector layer 21C. Good. This is obtained by providing the secondary battery shown in FIG. 4 with the inorganic compound layer 41F of the present embodiment.
[0073]
[Fifth Embodiment]
FIG. 9 shows a configuration of a secondary battery according to the fifth embodiment of the present invention. The secondary battery has the same configuration as that of the first embodiment except that the battery element 60 in the first embodiment is replaced with a battery element 60 having different configurations of the positive electrode 62 and the electrolyte 63. Have. Therefore, here, the same reference numerals are given to the same components, and detailed description thereof is omitted.
[0074]
The positive electrode 62 and the electrolyte 63 are formed on the film forming substrate 21A by a dry film forming method or a wet film forming method. That is, in the secondary battery according to the present embodiment, the negative electrode current collector layer 21B, the negative electrode active material layer 21C, the electrolyte 63, the positive electrode active material layer 62B, and the positive electrode current collector layer 62A are formed on the film formation base 21A. Is formed by depositing all of the film. As a result, the film thickness can be further reduced, the bonding between the electrolyte 63 and the positive electrode 62 can be made favorable, and furthermore, since no binder is used for the positive electrode 62, good load characteristics can be obtained. It has become.
[0075]
The positive electrode current collector layer 62A is preferably made of a metal having a noble oxidation-reduction potential, such as platinum (Pt) or gold (Au). As in the first embodiment, the positive electrode active material layer 62B is composed of a lithium-containing compound such as a lithium transition metal composite oxide or a lithium-containing phosphate compound that can be formed by a dry film formation method or a wet film formation method. It is preferable. Among these, a lithium transition metal composite oxide and a lithium-containing phosphate compound are preferable because a high energy density can be obtained.
[0076]
The electrolyte 63 is composed of, for example, an inorganic solid electrolyte. The constituent material of the inorganic solid electrolyte is the same as that of the inorganic solid electrolyte described in the first embodiment or the inorganic compound layer 41F in the fourth embodiment.
[0077]
In this secondary battery, although not shown, the battery element 60 may be covered with a polymer layer or an inorganic compound layer that functions as a moisture / oxygen barrier layer and an insulating layer. For example, the diffusion preventing layer 21B, the negative electrode current collector layer 21C, the negative electrode active material layer 21D, the electrolyte 63, the positive electrode active material layer 62B, and the positive electrode current collector layer 62A may be covered with these, or the film formation base 21A You may make it cover the whole including these. In this case, as in the first embodiment, the battery element 60 may be enclosed in a film-shaped exterior member 10 such as a laminate film. However, these polymer layer or inorganic compound layer is used as an exterior member. The film-shaped exterior member 10 may not be enclosed. Alternatively, the film formation base 21A may be used as an exterior member.
[0078]
For example, the secondary battery can be manufactured as follows.
[0079]
First, similarly to the first embodiment, the diffusion prevention layer 21B, the negative electrode current collector layer 21C, and the negative electrode active material layer 21D are sequentially formed on the film formation base 21A. Next, the electrolyte is formed on the anode active material layer 21D by, for example, a dry film formation method such as a sputtering method, a vacuum evaporation method, a laser ablation method, an ion plating method or a CVD method, or a wet film formation method such as a sol-gel method. 63 is formed.
[0080]
Subsequently, the positive electrode is formed on the electrolyte 63 by, for example, a sputtering method, a vacuum deposition method, a laser ablation method, a dry film formation method such as an ion plating method or a CVD method, or a wet film formation method such as a sol-gel method. An active material layer 62B is formed. For example, the film may be formed by sputtering using a lithium-containing compound that is a positive electrode active material as a raw material, or may be formed by reactive sputtering in which oxygen gas is introduced to control the composition. Further, in order to control the crystal structure, the substrate may be heated during film formation, or annealing may be performed after film formation. When the negative electrode active material layer 21D is made of metallic lithium, the melting point of metallic lithium is 197 ° C., so heat treatment at a temperature higher than that cannot be performed. When the negative electrode active material layer 21D is made of a material capable of inserting and extracting lithium, heat treatment at a higher temperature is possible.
[0081]
After that, the positive electrode current collector layer 62A is formed on the positive electrode active material layer 62B by, for example, a dry film forming method. Next, patterning is performed using a mask, and the negative electrode terminal 21E and the positive electrode terminal 22C may be formed by, for example, a dry film forming method, or the negative electrode terminal 21E and the positive electrode terminal 22C are formed by attaching a metal foil. You may do it. Subsequently, the battery element 60 is covered with a polymer layer or an inorganic compound layer as necessary, and sealed in the exterior member 10. Thereby, the secondary battery shown in FIG. 9 is obtained.
[0082]
In this secondary battery, as in the first embodiment, lithium ions are released from the positive electrode active material layer 62B by charging, and are deposited or occluded in the negative electrode active material layer 21D through the electrolyte 63. In addition, lithium ions are eluted or separated from the negative electrode active material layer 21 </ b> D by discharge, and are inserted in the positive electrode active material layer 62 </ b> B through the electrolyte 63. At that time, since the electrolyte 63 is composed of an inorganic compound, similarly to the fourth embodiment in which the inorganic compound layer 41F is provided, a uniform precipitation / dissolution reaction of metallic lithium in the negative electrode active material layer 21D, or lithium Thus, the uniform occlusion / release reaction is promoted, and metallic lithium is prevented from growing in a needle shape. Further, since no binder is used for the positive electrode active material layer 62B, good load characteristics can be obtained.
[0083]
As described above, in the present embodiment, the electrolyte 63 and the positive electrode 62 are further formed by the dry film forming method or the wet film forming method. Therefore, in addition to the effects of the first embodiment, the fourth embodiment is implemented. Similarly to the embodiment, it is possible to further promote the precipitation / dissolution reaction of lithium metal or the occlusion / release reaction of lithium in the anode active material layer 21D, and to suppress the needle-like growth of the lithium metal.
[0084]
In addition, the battery can be made thinner and the energy density can be further improved as compared with the case where an electrolytic solution, a gel electrolyte, or a polymer electrolyte is used. Furthermore, since no binder is used for the positive electrode 62, good load characteristics can be obtained. In addition, since the negative electrode active material layer 21D is formed on the film forming substrate 21A and the positive electrode 62 is formed on the negative electrode active material layer 21D, the lithium deposition interface is formed as compared with the case where the negative electrode is formed on the positive electrode. The flatness of the lithium can be increased, and the lithium precipitation / dissolution reaction can be made more uniform. Furthermore, it can be used in combination with other devices sensitive to lithium, and the choice of a battery forming substrate can be expanded.
[0085]
As in the second embodiment, the present embodiment also does not include the negative electrode active material layer 21D at the time of assembly, as shown in FIG. 10, for example. You may comprise so that negative electrode active material layer 21D which consists of metallic lithium may be formed by depositing metallic lithium on it.
[0086]
Similarly to the third embodiment, for example, as shown in FIG. 11, a negative electrode having a negative electrode current collector layer 31C made of titanium or tantalum instead of the diffusion prevention layer 21B and the negative electrode current collector layer 21C. A battery element 70 provided with 71 may be used. This is obtained by replacing the positive electrode 22 and the electrolyte 23 of the secondary battery shown in FIG. 3 with the positive electrode 62 and the electrolyte 63 of the present embodiment.
[0087]
Furthermore, for example, as shown in FIG. 12, the negative electrode active material layer 21D is not provided at the time of assembly, and metal lithium is deposited on the negative electrode current collector layer 21C at the time of charging, whereby a negative electrode active material made of metal lithium. While the layer 21D is formed, the battery element 70 including the negative electrode 71 having the negative electrode current collector layer 31C made of titanium or tantalum is used instead of the diffusion prevention layer 21B and the negative electrode current collector layer 21C. Good. This is obtained by replacing the positive electrode 22 and the electrolyte 23 of the secondary battery shown in FIG. 4 with the positive electrode 52 and the electrolyte 63 of the present embodiment.
[0088]
【Example】
Further, specific embodiments of the present invention will be described in detail with reference to the drawings.
[0089]
(Examples 1-3)
The secondary battery described in the first embodiment was manufactured (see FIG. 1). At that time, the negative electrode 21 was produced as follows. First, in Examples 1 and 3, a film-forming substrate 21A made of mirror-polished glass having a surface roughness (Ra) of about 0.003 μm was prepared, and the surface was sufficiently washed with acetone and isopropyl alcohol. In Example 2, a film-forming substrate 21A made of aramid (aromatic polyamide) having a surface roughness (Ra) of 0.003 μm or less was prepared.
[0090]
Next, a diffusion prevention layer 21B having a thickness of 50 nm was formed on the substrate 21A for film formation using a DC magnetron sputtering apparatus, and then a negative electrode current collector layer 21C made of copper and having a thickness of 500 nm was continuously formed. . At that time, in Examples 1 and 2, the diffusion prevention layer 21B was formed of titanium, and in Example 3, the diffusion prevention layer 21B was formed of tantalum. After that, on the negative electrode current collector layer 21C, a chamber internal pressure of 5 × 10^-FourA negative electrode active material layer 21D made of metallic lithium and having a thickness of 10 μm was formed by a vacuum vapor deposition method with a pressure of Pa or less. After forming the negative electrode active material layer 21D, the negative electrode terminal 21E was attached to the negative electrode current collector layer 21C.
[0091]
Moreover, the positive electrode 22 was produced as follows. First, a lithium cobalt composite oxide (LiCoO) which is a positive electrode active material₂), Acetylene black as a conductive agent, and polyvinylidene fluoride as a binder were mixed using N-methylpyrrolidone as a dispersion medium to prepare a positive electrode mixture. Next, this positive electrode mixture was applied onto a positive electrode current collector 22A made of an aluminum foil, dried by heating overnight, and then heat-pressed to form a positive electrode active material layer 22B. Subsequently, the positive electrode terminal 22C was attached to the positive electrode current collector 22A.
[0092]
Furthermore, the electrolyte 23 was produced as follows. First, LiBF as an electrolyte salt in the monomer solution_FourAfter dissolving, the monomer was crosslinked with ultraviolet rays. Next, vacuum heating and drying for 24 hours or more was performed to obtain a polymer electrolyte having a thickness of about 40 μm.
[0093]
The produced negative electrode 21, electrolyte 23, and positive electrode 22 were laminated in this order, and then sealed in the exterior member 10 made of an aluminum laminate film to obtain secondary batteries of Examples 1 to 3.
[0094]
As Comparative Example 1 with respect to Examples 1 to 3, a negative electrode active material layer made of lithium metal by vacuum deposition in the same manner as in Examples 1 to 3 on a rolled copper foil that had been sufficiently washed with acetone and isopropyl alcohol A secondary battery was fabricated in the same manner as in Examples 1 to 3, except that 21D was formed. Further, as Comparative Examples 2 and 3 with respect to Examples 1 to 3, secondary batteries were fabricated in the same manner as Examples 1 to 3 except that the diffusion prevention layer 21B was formed of chromium. In Comparative Example 2, a film-forming substrate 21 made of glass was used as in Examples 1 and 3, and in Comparative Example 3, a film-forming substrate 21 made of aramid was used as in Example 2.
[0095]
The produced secondary batteries of Examples 1 to 3 and Comparative Examples 1 to 3 were charged and discharged, and the capacity retention rate at the 30th cycle when the initial discharge capacity was 100% was examined. Charge the battery with a constant current until the battery voltage reaches 4.2V at a current value that can discharge the design capacity in 5 hours, and then charge at a constant voltage until the current value reaches 4.2% at 4.2V. The discharge was carried out at a constant current until the battery voltage reached 3.0 V at the current value during constant current charging. Table 1 shows the results.
[0096]
[Table 1]

[0097]
As can be seen from Table 1, according to Examples 1 to 3, a capacity retention rate higher than that of Comparative Example 1 using a rolled copper foil was obtained. Unlike the conventional rolled foil, the negative electrode current collector layer 21C is formed on the film-forming substrate 21A made of mirror-polished glass or aramid having a small surface roughness, so that a good lithium precipitation dissolved surface can be obtained. It is thought that this is because
[0098]
Moreover, according to Examples 1-3, the capacity | capacitance maintenance factor higher than the comparative examples 2 and 3 which comprised the diffusion prevention layer with chromium was obtained. In Comparative Examples 2 and 3, since lithium penetrates the negative electrode current collector layer made of copper and further the diffusion prevention layer made of chromium, the substrate for film formation or the negative electrode current collector is broken, so that the current collecting function is lowered. As a result, rapid capacity deterioration was observed during the cycle. When the negative electrodes 21 of Examples 1 to 3 and Comparative Examples 2 and 3 were disassembled after the cycle, destruction of the negative electrode was observed in Comparative Examples 2 and 3, but not in Examples 1 to 3.
[0099]
That is, if the anode current collector layer 21C is formed on the film forming substrate 21A and the diffusion preventing layer 21B made of titanium or tantalum is provided between them, the long-term stability of the anode 21 can be improved, and the battery It has been found that the long-term stability of can be improved and the cycle characteristics can be improved.
[0100]
(referenceExample 4)
  The secondary battery described in the third embodiment was manufactured (see FIG. 3). In that case, it replaced with the diffusion prevention layer 21B and the negative electrode collector layer 21C, and was the same as that of Example 1 except having formed the negative electrode collector layer 31C with a thickness of 500 nm which consists of titanium. MadereferenceThe secondary battery of Example 4 was charged and discharged in the same manner as in Examples 1 to 3, and the capacity retention rate at the 30th cycle was examined. The results are shown in Table 2 together with the results of Example 1 and Comparative Examples 1 and 2.
[0101]
[Table 2]

[0102]
  As can be seen from Table 2,referenceThe capacity retention rate of Example 4 was almost the same as that of Example 1, and higher values than those of Comparative Examples 1 and 2 were obtained.referenceAlso in Example 4, when the negative electrode 31 was disassembled after the cycle, destruction of the negative electrode 31 was not observed. That is, even if the negative electrode current collector layer 31C is made of titanium or tantalum and has a diffusion preventing function, the long-term stability of the negative electrode 31 can be improved, and the long-term stability of the battery can be improved. It was found that the characteristics can be improved.
[0103]
(Example 5)
The secondary battery described in the fourth embodiment was manufactured (see FIG. 5). At that time, lithium ion conductivity having a thickness of 1 μm made of phosphoryllithium nitride (LiPON) is formed on the negative electrode active material layer 21D by performing high frequency reactive sputtering in a nitrogen gas atmosphere using lithium phosphate as a raw material. An inorganic compound layer 41 </ b> F having was formed. Others were the same as in Example 1. Further, as Comparative Example 4 for the present example, a secondary battery was fabricated in the same manner as Example 5 except that the diffusion preventing layer 21B was formed of chromium. For the fabricated secondary batteries of Example 5 and Comparative Example 4, charge and discharge were performed in the same manner as in Examples 1 to 3, and the capacity retention rate at the 30th cycle was examined. The results are shown in Table 3 together with the results of Example 1 and Comparative Example 2.
[0104]
[Table 3]

[0105]
As can be seen from Table 3, according to Example 5 in which the inorganic compound layer 41F was formed, the capacity retention rate could be further improved than in Example 1. On the other hand, in Comparative Example 4 in which chromium was used for the diffusion preventing layer, the capacity retention rate was improved due to the formation of the inorganic compound layer. A large deterioration of the maintenance rate was observed. That is, if the diffusion preventing layer 21B and the negative electrode current collector layer 21C made of titanium or tantalum are formed on the film forming base 21A and further provided with the inorganic compound layer 41F, the cycle characteristics can be further improved. I understood.
[0106]
Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the above embodiments and examples, and various modifications can be made. For example, in the above embodiments and examples, a single-layer type secondary battery in which the negative electrodes 21, 31, 41, 51, 71 and the positive electrodes 22, 62 are stacked has been described, but the negative electrode and the positive electrode are stacked, The present invention can be similarly applied to a wound secondary battery that is wound, or a stacked secondary battery in which a plurality of negative electrodes and positive electrodes are stacked.
[0107]
  In the above-described embodiments and examples, the secondary battery in which the battery element is sealed in the film-shaped exterior member has been described. However, other shapes such as a so-called cylindrical shape, square shape, coin shape, button shape, or card shape have been described. It can also be applied to secondary batteries such as.
[0109]
【The invention's effect】
  As explained above, The present inventionofFor lithium ion secondary batteryNegative electrode, orLithium ion secondaryAccording to the battery, diffusion prevention made of titanium or tantalumLayerSo I preparedlithiumCan be prevented from diffusing into the substrate for film formation,lithiumIt is possible to prevent the film-forming substrate from being broken and the negative electrode current collector layer from falling off due to the diffusion of. Therefore, long-term stability can be improved and a long life can be achieved.
[0110]
  In particular,The present inventionofFor lithium ion secondary batteryNegative electrode, orLithium ion secondaryBattery, orFor lithium ion secondary batteryNegative electrode manufacturing method, orLithium ion secondaryBattery manufacturing methodThenAnd forming a negative electrode current collector layer on the film forming substrate by a dry film forming method or a wet film forming method.IfFurther, it is possible to reduce the thickness of the negative electrode and improve the flatness of the surface. Therefore, the energy density of the battery can be improved by reducing the thickness, the electrode reaction can be promoted by improving the flatness, and the characteristics can be improved.
[0111]
  Also,For lithium ion secondary batteryNegative electrode, orLithium ion secondarybatteryThenFurther comprising an inorganic compound layerIfThe uniform electrode reaction can be further promoted, and the charge / discharge efficiency can be improved. In addition, the reaction between the negative electrode and the electrolyte can be suppressed, and the choices of the electrolyte can be expanded, whereby the performance of the battery can be improved and the capacity deterioration due to the reaction can be prevented.
[0112]
  Furthermore,Lithium ion secondaryBattery, orLithium ion secondaryBattery manufacturing methodThenThe positive electrode and the electrolyte are formed by a dry film forming method or a wet film forming method.IfFurther, the uniform electrode reaction can be further promoted, the charge / discharge efficiency can be improved, the battery can be made thinner, and the energy density can be further improved. In addition, since no binder is used for the positive electrode, good load characteristics can be obtained. In addition, it can be used with other devices.Lithium ion secondaryIt is possible to broaden the options of the battery forming substrate.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of a secondary battery according to a first embodiment of the invention.
FIG. 2 is a cross-sectional view illustrating a configuration at the time of assembling a secondary battery according to a second embodiment of the present invention.
FIG. 3 is a cross-sectional view illustrating a configuration of a secondary battery according to a third embodiment of the invention.
FIG. 4 is a cross-sectional view of the secondary battery according to the third embodiment of the present invention when assembled, illustrating a modification.
FIG. 5 is a cross-sectional view showing a configuration of a secondary battery according to a fourth embodiment of the invention.
FIG. 6 is a cross-sectional view of the secondary battery according to the fourth embodiment of the present invention when assembled, illustrating a modification.
FIG. 7 is a cross-sectional view showing another modification of the secondary battery according to the fourth embodiment of the invention.
FIG. 8 is a cross-sectional view at the time of assembly showing another modification of the secondary battery according to the fourth embodiment of the invention.
FIG. 9 is a cross-sectional view showing a configuration of a secondary battery according to a fifth embodiment of the invention.
FIG. 10 is a cross-sectional view of the secondary battery according to the fifth embodiment of the present invention when assembled, illustrating a modification.
FIG. 11 is a cross-sectional view showing another modification of the secondary battery according to the fifth embodiment of the invention.
FIG. 12 is a cross-sectional view at the time of assembly showing another modification of the secondary battery according to the fifth embodiment of the invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Exterior member, 20, 30, 40, 50, 60, 70 ... Battery element, 21, 31, 41, 51, 71 ... Negative electrode, 21A ... Film-forming substrate, 21B ... Diffusion prevention layer, 21C, 31C ... Negative electrode Current collector layer, 21D ... negative electrode active material layer, 21E ... negative electrode terminal, 22, 62 ... positive electrode, 22A ... positive electrode current collector, 22B, 62B ... positive electrode active material layer, 22C ... positive electrode terminal, 23, 63 ... electrolyte, 41F: inorganic compound layer, 62A: positive electrode current collector layer.

Claims (37)

A substrate for film formation;
A negative electrode current collector layer provided on the substrate for film formation;
A negative electrode for a lithium ion secondary battery , comprising: a negative electrode current collector layer and a diffusion prevention layer made of titanium or tantalum provided between the film forming substrate. The film forming substrate, a semiconductor, ceramics, made of glass or plastic, claim 1 Symbol placement for a lithium ion secondary battery negative electrode. The anode current collector layer has been formed by a dry film forming method or a wet film formation method, according to claim 1 Symbol placement for a lithium ion secondary battery negative electrode. The diffusion barrier layer was formed by a dry deposition method or a wet film formation method, according to claim 1 for a lithium ion secondary battery negative electrode according. Further, the with an inorganic compound layer with ion conductivity which is provided on the anode current collector layer, claim 1 Symbol placement for a lithium ion secondary battery negative electrode. The negative electrode for a lithium ion secondary battery according to claim 5 , wherein the inorganic compound layer is formed by a dry film forming method or a wet film forming method. The inorganic compound layer includes lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium nitride, lithium oxide, lithium phosphate, lithium silicate, lithium sulfide, lithium phosphide, lithium carbonate, lithium sulfate, and phosphoryl nitride. The negative electrode for a lithium ion secondary battery according to claim 5 , comprising at least one selected from the group consisting of lithium or a lithium compound containing at least one selected from among the raw materials. Furthermore, the comprising a negative electrode active material layer provided on the anode current collector layer, claim 1 Symbol placement for a lithium ion secondary battery negative electrode. The negative electrode for a lithium ion secondary battery according to claim 8 , wherein the negative electrode active material layer is formed by a dry film forming method or a wet film forming method. The negative electrode active material layer is made of metallic lithium, or magnesium, aluminum, silicon, calcium, zinc, gallium, silver, indium, tin, barium, lead, bismuth, and a compound containing at least one of these. at least it made of a material comprising one or a lithium ion secondary battery negative electrode according to claim 8 of the group consisting of. Furthermore, the negative active with an inorganic compound layer having been ion conductivity provided material layer, lithium-ion secondary battery negative electrode of claim 8. The negative electrode for a lithium ion secondary battery according to claim 11 , wherein the inorganic compound layer is formed by a dry film forming method or a wet film forming method. The inorganic compound layer includes lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium nitride, lithium oxide, lithium phosphate, lithium silicate, lithium sulfide, lithium phosphide, lithium carbonate, lithium sulfate, and phosphoryl nitride. The negative electrode for a lithium ion secondary battery according to claim 11 , comprising at least one member selected from the group consisting of lithium or a lithium compound containing at least one member selected from the group consisting of raw materials. An electrolyte is provided with a positive electrode and a negative electrode ,
The negative electrode is provided with a film forming substrate, a negative electrode current collector layer provided on the film forming substrate, and provided between the negative electrode current collector layer and the film forming substrate, and is made of titanium or tantalum. A lithium ion secondary battery having a diffusion prevention layer. The lithium ion secondary battery according to claim 14 , wherein the film forming substrate is made of a semiconductor, ceramics, glass, or plastic. The lithium ion secondary battery according to claim 14 , wherein the negative electrode current collector layer is formed by a dry film forming method or a wet film forming method. The lithium ion secondary battery according to claim 14 , wherein the diffusion preventing layer is formed by a dry film forming method or a wet film forming method. The negative electrode, further wherein a negative electrode current collector inorganic compound layer having been ion conductivity provided on the body layer, claim 14 lithium ion secondary battery according. The lithium ion secondary battery according to claim 18 , wherein the inorganic compound layer is formed by a dry film forming method or a wet film forming method. The inorganic compound layer includes lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium nitride, lithium oxide, lithium phosphate, lithium silicate, lithium sulfide, lithium phosphide, lithium carbonate, lithium sulfate, and phosphoryl nitride. 19. The lithium ion secondary battery according to claim 18 , comprising at least one member selected from the group consisting of lithium or a lithium compound containing at least one member selected from the group consisting of raw materials. The negative electrode, further comprising a negative electrode active material layer provided on the anode current collector layer, claim 14 lithium ion secondary battery according. The lithium ion secondary battery according to claim 21 , wherein the negative electrode active material layer is formed by a dry film forming method or a wet film forming method. The negative electrode active material layer is made of metallic lithium, or magnesium, aluminum, silicon, calcium, zinc, gallium, silver, indium, tin, barium, lead, bismuth, and a compound containing at least one of these. at least made of a material comprising one or a lithium ion secondary battery according to claim 21, wherein one of the group consisting of. The negative electrode further the anode active material layer comprising an inorganic compound layer having been ion conductivity provided in a lithium ion secondary battery according to claim 21, wherein. 25. The lithium ion secondary battery according to claim 24 , wherein the inorganic compound layer is formed by a dry film forming method or a wet film forming method. The inorganic compound layer includes lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium nitride, lithium oxide, lithium phosphate, lithium silicate, lithium sulfide, lithium phosphide, lithium carbonate, lithium sulfate, and phosphoryl nitride. at least one, or containing a lithium compound comprising at least one of these raw materials, the lithium ion secondary battery according to claim 24, wherein one of the group consisting of lithium. The lithium ion secondary battery according to claim 14 , wherein the electrolyte includes an electrolytic solution, a gel electrolyte, or a polymer electrolyte. The lithium ion secondary battery according to claim 14 , wherein the electrolyte and the positive electrode are formed by a dry film forming method or a wet film forming method. Forming a diffusion prevention layer made of titanium or tantalum on a substrate for film formation by a dry film formation method or a wet film formation method;
Forming a negative electrode current collector layer on the diffusion prevention layer by a dry film forming method or a wet film forming method. A method for producing a negative electrode for a lithium ion secondary battery . Further, on the negative electrode collector layer, a dry film formation method or a wet film-forming method, comprising the step of forming an inorganic compound layer with ion conductivity, claim 29 of the lithium-ion secondary battery negative electrode of Production method. Further, negatively on the electrode collector layer, comprising the step of forming the anode active material layer by a dry film forming method or a wet film formation method, according to claim 29 for a lithium ion secondary battery negative electrode manufacturing method according. Further, on the negative electrode active material layer, by a dry film forming method or a wet film-forming method, comprising the step of forming an inorganic compound layer having ion conductivity, manufacturing of claim 31 negative electrode for a lithium ion secondary battery according Method. A manufacturing process of a lithium ion secondary battery including an electrolyte together with a positive electrode and a negative electrode
Forming a diffusion prevention layer made of titanium or tantalum on a substrate for film formation by a dry film formation method or a wet film formation method;
Over the diffusion preventing layer, and forming a negative electrode current collector layer by a dry film forming method or a wet film formation method, method for manufacturing a lithium ion secondary battery. Further, on the negative electrode collector layer, a dry film formation method or a wet film-forming method, comprising the step of forming an inorganic compound layer having ion conductivity, a manufacturing method of a lithium ion secondary battery of claim 33 . Further, on the negative electrode collector layer, comprising the step of forming the anode active material layer by a dry film forming method or a wet film formation method, a manufacturing method of a lithium ion secondary battery of claim 33. Further, on the negative electrode active material layer, by a dry film forming method or a wet film-forming method, comprising the step of forming an inorganic compound layer having ion conductivity, a manufacturing method of a lithium ion secondary battery according to claim 35, wherein. Further, the dry deposition method or a wet film formation method, electrolyte and comprising the step of forming a positive electrode, a manufacturing method of a lithium ion secondary battery of claim 33.

Images