TW201939798A - Positive electrode material for lithium ion secondary battery, positive electrode active material layer, and lithium ion secondary battery - Google Patents
Positive electrode material for lithium ion secondary battery, positive electrode active material layer, and lithium ion secondary battery Download PDFInfo
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
- H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
Description
本發明係關於一種鋰離子二次電池用正極材料、由該鋰離子二次電池用正極材料所構成之正極活性物質層、及鋰離子二次電池。The present invention relates to a positive electrode material for a lithium ion secondary battery, a positive electrode active material layer composed of the positive electrode material for a lithium ion secondary battery, and a lithium ion secondary battery.
鋰離子二次電池用作蓄電用之大型定置用電源、電動汽車用等之電源，近年來正發展電池之小型化及薄型化之研究。鋰離子二次電池一般具備於金屬箔之表面形成有電極活性物質層之兩電極（正極及負極）、及配置於兩電極之間之分隔件。分隔件發揮防止兩電極間之短路或保持電解液之作用。Lithium-ion secondary batteries are used as power sources for large-scale stationary power storage, electric vehicles, and the like. In recent years, research into miniaturization and thinning of batteries is being developed. Lithium-ion secondary batteries generally include two electrodes (positive electrodes and negative electrodes) in which an electrode active material layer is formed on a surface of a metal foil, and a separator disposed between the two electrodes. The separator plays a role of preventing a short circuit between the two electrodes or maintaining an electrolyte.
作為鋰離子二次電池之正極所使用之正極活性物質，一般使用鋰金屬氧化物，例如，已知顯示高之充放電電容之鋰鎳鈷鋁系氧化物。
一般來說，氫氧化鋰作為製造鋰金屬氧化物之起始原料而使用。因此，於上述之鋰鎳鈷鋁系氧化物等正極活性物質中，殘存有一定量之氫氧化鋰，已知因此會由充放電循環導致放電減少等，電池性能會降低（專利文獻1）。又，氫氧化鋰之鹼性高，由此，於將正極活性物質、黏合劑、導電助劑、溶劑等混合而製作漿料時，該漿料會凝膠化，因此，就防止凝膠化之觀點而言，揭示一種摻合酸之技術（專利文獻2）。
先前技術文獻
專利文獻As a positive electrode active material used for a positive electrode of a lithium ion secondary battery, a lithium metal oxide is generally used, and for example, a lithium nickel cobalt aluminum oxide having a high charge-discharge capacitance is known.
Generally, lithium hydroxide is used as a starting material for producing lithium metal oxides. Therefore, a certain amount of lithium hydroxide remains in the above-mentioned positive electrode active materials such as lithium nickel cobalt aluminum oxide, and it is known that the battery performance is reduced due to a reduction in discharge caused by the charge and discharge cycle (Patent Document 1). In addition, lithium hydroxide has a high basicity. Therefore, when a positive electrode active material, a binder, a conductive aid, a solvent, and the like are mixed to prepare a slurry, the slurry gels, and therefore, gelation is prevented. From the viewpoint, a technique for blending an acid is disclosed (Patent Document 2).
Prior art literature patent literature
專利文獻1：日本特開2001-283849號公報
專利文獻2：日本特開平10-79244號公報Patent Document 1: Japanese Patent Application Laid-Open No. 2001-283849 Patent Document 2: Japanese Patent Application Laid-Open No. 10-79244
[發明所欲解決之課題][Problems to be Solved by the Invention]
然而，若為了中和鋰鎳鈷鋁系氧化物中所含有之氫氧化鋰而摻合酸，則凝膠化雖然受到抑制，但正極之電阻變高，作為鋰離子二次電池之輸出特性降低。
於是，本發明之課題在於提供一種於使用鋰鎳鈷鋁系氧化物作為正極活性物質之情形時，輸出特性良好且密度高之正極材料、由該正極材料所構成之正極活性物質層、及具備該正極活性物質層之鋰離子二次電池。
[解決課題之技術手段]However, if an acid is blended to neutralize lithium hydroxide contained in the lithium nickel cobalt aluminum oxide, the gelation is suppressed, but the resistance of the positive electrode is increased, and the output characteristics of the lithium ion secondary battery are reduced. .
Then, an object of the present invention is to provide a positive electrode material with good output characteristics and high density when a lithium nickel cobalt aluminum oxide is used as a positive electrode active material, a positive electrode active material layer composed of the positive electrode material, and The lithium ion secondary battery of the positive electrode active material layer.
[Technical means to solve the problem]
本發明者們進行苦心研究，其結果，發現含有作為正極活性物質之鋰鎳鈷鋁系氧化物、及長度與縱橫比為特定範圍內之奈米碳管的正極材料可解決上述課題，從而完成以下之本發明。本發明之主旨係以下[1]〜[11]。
[1]一種鋰離子二次電池用正極材料，其係包含鋰鎳鈷鋁系氧化物及奈米碳管之正極材料，上述奈米碳管之長度為1〜20 μm，縱橫比（長度/粗度比）為80〜5000，且以正極材料總量為基準之奈米碳管之含量為0.1〜10質量%。
[2]如上述[1]所述之鋰離子二次電池用正極材料，其進而包含黏合劑。
[3]如上述[1]或[2]所述之鋰離子二次電池用正極材料，其係藉由摻合鋰鎳鈷鋁系氧化物、奈米碳管、黏合劑、及酸而形成之正極材料用組成物所形成。
[4]如上述[3]所述之鋰離子二次電池用正極材料，其中，上述酸係有機酸。
[5]如上述[4]所述之鋰離子二次電池用正極材料，其中，上述有機酸係二價之有機酸。
[6]如上述[3]至[5]中任一項所述之鋰離子二次電池用正極材料，其中，以上述正極材料用組成物總量為基準，上述酸之摻合量為0.1〜10質量%。
[7]如上述[2]至[6]中任一項所述之鋰離子二次電池用正極材料，其中，上述黏合劑為含氟樹脂。
[8]如上述[7]所述之鋰離子二次電池用正極材料，其中，上述含氟樹脂為聚偏二氟乙烯。
[9]一種正極活性物質層，其由上述[1]至[8]中任一項所述之鋰離子二次電池用正極材料所構成。
[10]一種鋰離子二次電池，其具備具有上述[9]所述之正極活性物質層之正極。
[11]如上述[10]所述之鋰離子二次電池，其具備上述正極、以與正極對向之方式配置之負極、及配置於正極與負極之間之分隔件。
[發明之效果]The present inventors carried out painstaking research, and as a result, they found that a cathode material containing lithium nickel cobalt aluminum oxide as a positive electrode active material and a nano carbon tube having a length and an aspect ratio within a specific range can solve the above-mentioned problems, thereby completing The present invention is as follows. The gist of the present invention is the following [1] to [11].
[1] A positive electrode material for a lithium ion secondary battery, which is a positive electrode material containing lithium nickel cobalt aluminum oxide and a carbon nanotube. The length of the carbon nanotube is 1 to 20 μm, and the aspect ratio (length / The thickness ratio) is 80 to 5000, and the content of the nano carbon tube based on the total amount of the positive electrode material is 0.1 to 10% by mass.
[2] The positive electrode material for a lithium ion secondary battery according to the above [1], further comprising a binder.
[3] The positive electrode material for a lithium ion secondary battery according to the above [1] or [2], which is formed by blending a lithium nickel cobalt aluminum oxide, a carbon nanotube, a binder, and an acid. A composition for a positive electrode material.
[4] The positive electrode material for a lithium ion secondary battery according to the above [3], wherein the acid-based organic acid.
[5] The positive electrode material for a lithium ion secondary battery according to the above [4], wherein the organic acid is a divalent organic acid.
[6] The positive electrode material for a lithium ion secondary battery according to any one of the above [3] to [5], wherein a content of the acid is 0.1 based on a total amount of the composition for the positive electrode material ~ 10% by mass.
[7] The positive electrode material for a lithium ion secondary battery according to any one of the above [2] to [6], wherein the binder is a fluorine-containing resin.
[8] The positive electrode material for a lithium ion secondary battery according to the above [7], wherein the fluorine-containing resin is polyvinylidene fluoride.
[9] A positive electrode active material layer composed of the positive electrode material for a lithium ion secondary battery according to any one of the above [1] to [8].
[10] A lithium ion secondary battery comprising a positive electrode having the positive electrode active material layer according to the above [9].
[11] The lithium ion secondary battery according to the above [10], comprising the positive electrode, a negative electrode arranged to face the positive electrode, and a separator arranged between the positive electrode and the negative electrode.
[Effect of the invention]
根據本發明，可提供一種輸出特性良好且密度高之正極材料、使用該正極材料而得之正極活性物質層、及具備該正極活性物質層之鋰離子二次電池。According to the present invention, a positive electrode material with good output characteristics and high density, a positive electrode active material layer obtained using the positive electrode material, and a lithium ion secondary battery including the positive electrode active material layer can be provided.
＜鋰離子二次電池用正極材料＞
本發明之鋰二次電池用正極材料（以下，亦稱為正極材料）係含有鋰鎳鈷鋁系氧化物及特定之奈米碳管者，該正極材料較佳為構成鋰離子二次電池之正極中之正極活性物質層。<Positive electrode material for lithium ion secondary batteries>
The positive electrode material (hereinafter, also referred to as a positive electrode material) for a lithium secondary battery of the present invention is a lithium nickel cobalt aluminum oxide and a specific nano carbon tube, and the positive electrode material is preferably one constituting a lithium ion secondary battery. The positive electrode active material layer in the positive electrode.
（鋰鎳鈷鋁系氧化物）
本發明之正極材料含有鋰鎳鈷鋁系氧化物。該鋰鎳鈷鋁系氧化物用作正極活性物質。藉由使用鋰鎳鈷鋁系氧化物，可提高鋰離子二次電池之充放電電容。
鋰鎳鈷鋁系氧化物係藉由鋁及鈷取代鎳酸鋰之鎳之一部分而得者。鋰鎳鈷鋁系氧化物以通式表示為Lit
Ni1 － x － y
Cox
Aly
O2
（其中，滿足0.95≦t≦1.15、0＜x≦0.3、0＜y≦0.2、x＋y≦0.5）。
鋰鎳鈷鋁系氧化物之平均粒徑較佳為0.5〜50 μm，更佳為1〜30 μm。鋰鎳鈷鋁系氧化物之平均粒徑意指於藉由雷射繞射-散射法求出之鋰鎳鈷鋁系氧化物之粒度分布中，體積累計為50%之粒徑（D50）。
正極材料中之鋰鎳鈷鋁系氧化物之含量以正極材料總量為基準，較佳為50〜98.5質量%，更佳為60〜98質量%，進而較佳為70〜96.5重量%。(Lithium nickel cobalt aluminum oxide)
The positive electrode material of the present invention contains a lithium nickel cobalt aluminum oxide. This lithium nickel cobalt aluminum oxide is used as a positive electrode active material. By using a lithium nickel cobalt aluminum oxide, the charge-discharge capacitance of a lithium ion secondary battery can be increased.
Lithium nickel cobalt aluminum oxide is obtained by replacing a part of nickel of lithium nickelate with aluminum and cobalt. The lithium-nickel-cobalt-aluminum oxide is represented by the general formula Li t Ni 1 - x - y Co x Al y O 2 (where 0.95 ≦ t ≦ 1.15, 0 <x ≦ 0.3, 0 <y ≦ 0.2, x + y ≦ 0.5).
The average particle diameter of the lithium nickel cobalt aluminum oxide is preferably 0.5 to 50 μm, and more preferably 1 to 30 μm. The average particle diameter of the lithium-nickel-cobalt-aluminum-based oxide means a particle size distribution (D50) of 50% by volume in the particle size distribution of the lithium-nickel-cobalt-aluminum-based oxide obtained by the laser diffraction-scattering method.
The content of the lithium nickel cobalt aluminum oxide in the positive electrode material is based on the total amount of the positive electrode material, preferably 50 to 98.5% by mass, more preferably 60 to 98% by mass, and still more preferably 70 to 96.5% by weight.
於本發明中，使用鋰鎳鈷鋁系氧化物作為正極活性物質，但於不妨礙本發明之效果之範圍內，亦可併用除鋰鎳鈷鋁系氧化物以外之正極活性物質。作為除鋰鎳鈷鋁系氧化物以外之正極活性物質，可列舉鈷酸鋰（LiCoO2
）、鎳酸鋰（LiNiO2
）、錳酸鋰（LiMn2
O4
）、橄欖石型磷酸鐵鋰（LiFePO4
）、NCM（鎳鈷錳）系氧化物等。
以正極活性物質總量為基準之鋰鎳鈷鋁系氧化物之含量較佳為80質量%以上，更佳為95質量%以上，進而較佳為100質量%。In the present invention, a lithium nickel cobalt aluminum oxide is used as the positive electrode active material, but a positive electrode active material other than a lithium nickel cobalt aluminum oxide may be used in combination as long as the effect of the present invention is not hindered. Examples of positive electrode active materials other than lithium nickel cobalt aluminum oxides include lithium cobaltate (LiCoO 2 ), lithium nickelate (LiNiO 2 ), lithium manganate (LiMn 2 O 4 ), and olivine-type lithium iron phosphate ( LiFePO 4 ), NCM (nickel-cobalt-manganese) oxides, and the like.
The content of the lithium nickel cobalt aluminum oxide based on the total amount of the positive electrode active material is preferably 80% by mass or more, more preferably 95% by mass or more, and even more preferably 100% by mass.
（奈米碳管）
本發明之正極材料含有長度為1〜20 μm、縱橫比（長度/粗度比）為80〜5000之奈米碳管。該奈米碳管係發揮作為導電助劑之功能者，藉有含有其而電阻值降低，藉此，輸出特性提高，且正極密度變高。認為其原因在於，由於具有特定之形狀之奈米碳管容易填埋作為正極活性物質之鋰鎳鈷鋁系氧化物間之空隙，故容易使正極活性物質彼此導通，且容易減少正極材料中之空隙，從而容易提高密度。
若本發明之正極材料所使用之奈米碳管之長度未達1 μm，則存在變得難以填埋正極活性物質間之空隙、正極密度容易降低之傾向。若奈米碳管之長度超過20 μm，則存在容易產生正極材料中之奈米碳管之分散不良、正極密度及輸出特性降低之傾向。奈米碳管之長度較佳為3〜10 μm，更佳為4〜8 μm。再者，奈米碳管之長度係多個奈米碳管之各者之長度之平均值，具體而言，根據藉由掃描式電子顯微鏡所觀察到之圖像求出20個奈米碳管之各者之長度，作為其平均值獲得。(Nano carbon tube)
The positive electrode material of the present invention contains a carbon nanotube having a length of 1 to 20 μm and an aspect ratio (length / roughness ratio) of 80 to 5000. The nano-carbon tube has a function as a conductive additive, and by including it, the resistance value is reduced, thereby improving output characteristics and increasing the density of the positive electrode. The reason is considered to be that the carbon nanotubes having a specific shape can easily fill the gaps between the lithium nickel cobalt aluminum oxides as the positive electrode active material, so that the positive electrode active materials can be easily conducted to each other, and the amount of Voids, making it easy to increase density.
If the length of the nano-carbon tube used in the positive electrode material of the present invention is less than 1 μm, it tends to become difficult to fill the gaps between the positive electrode active materials, and the positive electrode density tends to decrease. If the length of the nano carbon tube exceeds 20 μm, there is a tendency that poor dispersion of the nano carbon tube in the positive electrode material tends to occur, and the positive electrode density and output characteristics tend to decrease. The length of the carbon nanotube is preferably 3 to 10 μm, and more preferably 4 to 8 μm. In addition, the length of the carbon nanotubes is an average of the lengths of each of the plurality of carbon nanotubes. Specifically, 20 carbon nanotubes were obtained based on an image observed with a scanning electron microscope. The length of each of them is obtained as its average value.
本發明之正極材料所使用之奈米碳管之縱橫比（長度/粗度比）為80〜5000。若奈米碳管之縱橫比未達80，則存在變得難以填埋正極活性物質間之空隙、正極密度容易降低之傾向。若奈米碳管之縱橫比超過5000，則存在容易產生正極材料中之奈米碳管之分散不良、正極密度及輸出特性降低之傾向。
奈米碳管之縱橫比較佳為1000〜4000，更佳為2000〜3000。再者，縱橫比係奈米碳管之長度相對於粗度（直徑）之比。再者，縱橫比係多個奈米碳管之縱橫比之平均值，具體而言，根據藉由掃描式電子顯微鏡所觀察到之圖像求出20個奈米碳管之縱橫比，作為其平均值獲得。
正極材料中之奈米碳管之含量以正極材料總量為基準，為0.1〜10質量%。若奈米碳管之含量超過10質量%，則正極活性物質之含量相對降低，輸出特性變差。若奈米碳管之含量未達0.1質量%，則正極材料之電阻容易變高，輸出特性變差。正極材料中之奈米碳管之含量以正極材料總量為基準，較佳為0.5〜5質量%，更佳為1〜4質量%。The aspect ratio (length / roughness ratio) of the nano carbon tube used in the cathode material of the present invention is 80 to 5000. If the aspect ratio of the nano carbon tube is less than 80, it tends to become difficult to fill the gaps between the positive electrode active materials, and the density of the positive electrode tends to decrease. If the aspect ratio of the nano carbon tube exceeds 5000, there is a tendency that poor dispersion of the nano carbon tube in the positive electrode material tends to occur, and the positive electrode density and output characteristics tend to decrease.
The aspect ratio of the nano carbon tube is preferably 1000 to 4000, and more preferably 2000 to 3000. The aspect ratio is the ratio of the length of the carbon nanotube to the thickness (diameter). The aspect ratio is an average value of the aspect ratios of a plurality of carbon nanotubes. Specifically, the aspect ratio of 20 carbon nanotubes was obtained from an image observed with a scanning electron microscope, and was taken as the The average is obtained.
The content of the nano carbon tube in the positive electrode material is 0.1 to 10% by mass based on the total amount of the positive electrode material. When the content of the nano carbon tube exceeds 10% by mass, the content of the positive electrode active material is relatively reduced, and output characteristics are deteriorated. If the content of the nano carbon tube is less than 0.1% by mass, the resistance of the positive electrode material tends to be high, and the output characteristics are deteriorated. The content of the nano carbon tube in the positive electrode material is based on the total amount of the positive electrode material, preferably 0.5 to 5% by mass, and more preferably 1 to 4% by mass.
本發明使用奈米碳管作為導電助劑，但於不妨礙本發明之效果之範圍內，亦可併用除奈米碳管以外之導電助劑。作為除奈米碳管以外之導電助劑，可列舉科琴黑、乙炔黑、棒狀碳等。
以導電助劑總量為基準之奈米碳管之含量較佳為80質量%以上，更佳為95質量%以上，進而較佳為100質量%。In the present invention, a nano carbon tube is used as a conductive auxiliary agent. However, as long as the effect of the present invention is not hindered, a conductive auxiliary other than a nano carbon tube may be used in combination. Examples of the conductive aid other than the carbon nanotube include Ketjen Black, acetylene black, and rod-shaped carbon.
The content of the nano carbon tube based on the total amount of the conductive additive is preferably 80% by mass or more, more preferably 95% by mass or more, and even more preferably 100% by mass.
本發明之正極材料較佳為含有黏合劑。藉此，正極材料係鋰鎳鈷鋁系氧化物及奈米碳管被黏合劑黏結而構成。
作為黏合劑，例如，可列舉聚偏二氟乙烯（PVDF）、聚偏二氟乙烯－六氟丙烯共聚物（PVDF-HFP）、聚四氟乙烯（PTFE）等含氟樹脂、聚丙烯酸甲酯（PMA）、聚甲基丙烯酸甲酯（PMMA）等丙烯酸樹脂、聚乙酸乙烯酯、聚醯亞胺（PI）、聚醯胺（PA）、聚氯乙烯（PVC）、聚醚腈（PEN）、聚乙烯（PE）、聚丙烯（PP）、聚丙烯腈（PAN）、丙烯腈－丁二烯橡膠、苯乙烯丁二烯橡膠、聚(甲基)丙烯酸、羧甲基纖維素、羥乙基纖維素、及聚乙烯醇等。該等黏合劑可單獨使用1種，亦可併用2種以上。又，羧甲基纖維素等可以鈉鹽等鹽之態樣使用。該等之中，較佳為含氟樹脂，含氟樹脂之中較佳為使用聚偏二氟乙烯（PVDF）。
正極材料中之黏合劑之含量以正極材料總量為基準，較佳為0.1〜10質量%，更佳為0.5〜5質量%，進而較佳為2〜4質量%。The positive electrode material of the present invention preferably contains a binder. As a result, the lithium-nickel-cobalt-aluminum oxide based cathode material and the carbon nanotube are bonded together with a binder to form a structure.
Examples of the binder include fluorine-containing resins such as polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), and polytetrafluoroethylene (PTFE), and polymethyl acrylate. (PMA), polymethyl methacrylate (PMMA) and other acrylic resins, polyvinyl acetate, polyimide (PI), polyimide (PA), polyvinyl chloride (PVC), polyethernitrile (PEN) , Polyethylene (PE), polypropylene (PP), polyacrylonitrile (PAN), acrylonitrile-butadiene rubber, styrene butadiene rubber, poly (meth) acrylic acid, carboxymethyl cellulose, hydroxyethyl Cellulose and polyvinyl alcohol. These adhesives may be used individually by 1 type, and may use 2 or more types together. In addition, carboxymethyl cellulose and the like can be used in the form of a salt such as a sodium salt. Among these, a fluorine-containing resin is preferable, and among the fluorine-containing resins, polyvinylidene fluoride (PVDF) is preferably used.
The content of the binder in the positive electrode material is based on the total amount of the positive electrode material, preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, and even more preferably 2 to 4% by mass.
正極材料較佳為由下述之正極材料用組成物所形成。該正極材料用組成物為了中和鋰鎳鈷鋁系氧化物中所含之氫氧化鋰等鹼，較佳為含有酸。因此，由含有酸之正極材料用組成物所形成之正極材料中，不可避免地含有伴隨組成物中所含之酸與鹼之反應而產生之中和鹽。正極材料中之中和鹽以正極材料總量為基準，通常為0.01〜10質量%，較佳為0.3〜2質量%，更佳為0.5〜1.5質量%。The positive electrode material is preferably formed of a composition for a positive electrode material described below. The composition for a positive electrode material preferably contains an acid in order to neutralize a base such as lithium hydroxide contained in a lithium nickel cobalt aluminum oxide. Therefore, a positive electrode material formed from a composition for a positive electrode material containing an acid inevitably contains a neutralizing salt generated by a reaction between an acid and an alkali contained in the composition. The neutralization salt in the positive electrode material is based on the total amount of the positive electrode material, and is usually 0.01 to 10% by mass, preferably 0.3 to 2% by mass, and more preferably 0.5 to 1.5% by mass.
＜鋰離子二次電池＞
本發明之正極材料可構成鋰離子二次電池之正極活性物質層。本發明之鋰離子二次電池係具備由該正極材料所構成之正極活性物質層者。
圖1係表示本發明之鋰離子二次電池之一實施形態之概略剖視圖。鋰離子二次電池10具備正極12、以與正極12對向之方式配置之負極11、及配置於正極12與負極11之間之分隔件13。
負極11具備負極集電體11a、及積層於負極集電體11a之上之負極活性物質層11b，正極12亦相同地具備正極集電體12a、及積層於正極集電體12a之上之由本發明之正極材料所構成之正極活性物質層12b。由於由本發明之正極材料所構成之正極活性物質層12b含有特定量之鋰鎳鈷鋁系氧化物及特定之奈米碳管，故具備該正極活性物質層12b之鋰離子二次電池10之正極密度高，且輸出特性變得良好。
再者，於負極活性物質層11b與分隔件13之間、或正極活性物質層12b與分隔件13之間，可設置有未圖示之絕緣層。藉由設置絕緣層，可有效地防止正極12與負極11之間之短路。＜ Lithium ion secondary battery ＞
The positive electrode material of the present invention can constitute a positive electrode active material layer of a lithium ion secondary battery. The lithium ion secondary battery of the present invention includes a positive electrode active material layer composed of the positive electrode material.
FIG. 1 is a schematic cross-sectional view showing an embodiment of a lithium ion secondary battery of the present invention. The lithium ion secondary battery 10 includes a positive electrode 12, a negative electrode 11 arranged to face the positive electrode 12, and a separator 13 arranged between the positive electrode 12 and the negative electrode 11.
The negative electrode 11 includes a negative electrode current collector 11a and a negative electrode active material layer 11b laminated on the negative electrode current collector 11a, and the positive electrode 12 similarly includes a positive electrode current collector 12a and a negative electrode laminated on the positive electrode current collector 12a The positive electrode active material layer 12b composed of the positive electrode material of the invention. Since the positive electrode active material layer 12b composed of the positive electrode material of the present invention contains a specific amount of lithium nickel cobalt aluminum oxide and a specific carbon nanotube, the positive electrode of the lithium ion secondary battery 10 provided with the positive electrode active material layer 12b The density is high and the output characteristics become good.
Furthermore, an insulating layer (not shown) may be provided between the negative electrode active material layer 11 b and the separator 13, or between the positive electrode active material layer 12 b and the separator 13. By providing an insulating layer, a short circuit between the positive electrode 12 and the negative electrode 11 can be effectively prevented.
（正極）
本發明之鋰離子二次電池中之正極具有由本發明之正極材料所構成之正極活性物質層，較佳為具有正極集電體、及積層於正極集電體上之正極活性物質層。作為構成正極集電體之材料，例如，可列舉銅、鋁、鈦、鎳、不鏽鋼等具有導電性之金屬，較佳為使用鋁或銅，更佳為使用鋁。正極集電體一般由金屬箔所構成，其厚度並無特別限定，較佳為1〜50 μm。
正極材料較佳為由正極材料用組成物所形成。正極材料用組成物係包含上述鋰鎳鈷鋁系氧化物、奈米碳管、及黏合劑之組成物。正極材料用組成物較佳為進而含有溶劑。正極材料用組成物一般會成為漿料。正極材料用組成物中之各成分之含量以除溶劑以外之各成分之含量成為上述正極材料中所說明之含量之方式調整即可。
藉由將正極材料用組成物塗佈於正極集電體上，而於正極集電體上形成由正極材料所構成之正極活性物質層。正極材料用組成物中所含之鋰鎳鈷鋁系氧化物係含有氫氧化鋰等鹼性物質者，因此，存在於組成物中進行凝膠化而高黏度化，無法於正極集電體上形成正極活性物質層之情形。特別是使用含氟樹脂、尤其是聚偏二氟乙烯（PVDF）作為黏合劑時，凝膠化明顯容易發生。(positive electrode)
The positive electrode in the lithium ion secondary battery of the present invention has a positive electrode active material layer composed of the positive electrode material of the present invention, and preferably has a positive electrode current collector and a positive electrode active material layer laminated on the positive electrode current collector. Examples of the material constituting the positive electrode current collector include conductive metals such as copper, aluminum, titanium, nickel, and stainless steel. Aluminum or copper is preferably used, and aluminum is more preferably used. The positive electrode current collector is generally made of a metal foil, and its thickness is not particularly limited, but is preferably 1 to 50 μm.
The positive electrode material is preferably formed of a composition for a positive electrode material. The composition for a positive electrode material is a composition including the lithium nickel cobalt aluminum oxide, a carbon nanotube, and a binder. The composition for a positive electrode material preferably further contains a solvent. The composition for a positive electrode material generally becomes a slurry. The content of each component in the composition for a positive electrode material may be adjusted so that the content of each component other than the solvent becomes the content described in the above-mentioned positive electrode material.
The positive electrode current collector is coated with the composition for a positive electrode material to form a positive electrode active material layer composed of a positive electrode material on the positive electrode current collector. Lithium-nickel-cobalt-aluminum-based oxides contained in the composition for positive electrode materials contain alkaline substances such as lithium hydroxide. Therefore, they exist in the composition for gelation and high viscosity, and cannot be used on the positive electrode current collector. When a positive electrode active material layer is formed. Especially when a fluororesin, especially polyvinylidene fluoride (PVDF) is used as an adhesive, gelation is remarkably prone to occur.
為了防止此種凝膠化，較佳為使用摻合酸而成之正極材料用組成物作為正極材料用組成物。藉由使用酸，於含有含氟樹脂作為黏合劑之情形時，特別是於含有聚偏二氟乙烯（PVDF）作為黏合劑之情形時，可抑制組成物中之凝膠化。
作為酸，可為無機酸，亦可為有機酸，較佳為有機酸，更佳為二價之有機酸。
作為二價之有機酸，例如，可列舉草酸、丙二酸、丁二酸、戊二酸、己二酸、順丁烯二酸、反丁烯二酸等，其中，較佳為草酸、順丁烯二酸，更佳為草酸。
正極材料用組成物中之酸之摻合量以正極材料用組成物總量為基準，較佳為0.1〜10質量%。若為0.1質量%以上，則容易抑制凝膠化，若為10質量%以下，則容易抑制正極材料之電阻變高。正極材料用組成物中之酸之含量以正極材料總量為基準，更佳為0.2〜8質量%，進而較佳為0.5〜3質量%。再者，上述以正極材料用組成物總量為基準意指以正極材料用組成物之固形物成分之總量為基準。In order to prevent such gelation, it is preferable to use a composition for a positive electrode material obtained by mixing an acid as the composition for a positive electrode material. By using an acid, gelation in a composition can be suppressed when a fluorine-containing resin is contained as a binder, especially when polyvinylidene fluoride (PVDF) is contained as a binder.
The acid may be an inorganic acid or an organic acid, preferably an organic acid, and more preferably a divalent organic acid.
Examples of the divalent organic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, and fumaric acid. Among them, oxalic acid and cis acid are preferred. Butenoic acid is more preferably oxalic acid.
The blending amount of the acid in the composition for the positive electrode material is based on the total amount of the composition for the positive electrode material, and is preferably 0.1 to 10% by mass. If it is 0.1% by mass or more, it is easy to suppress gelation, and if it is 10% by mass or less, it is easy to suppress the resistance of the positive electrode material from increasing. The content of the acid in the composition for the positive electrode material is based on the total amount of the positive electrode material, more preferably 0.2 to 8% by mass, and even more preferably 0.5 to 3% by mass. In addition, the above-mentioned reference to the total amount of the composition for a positive electrode material refers to the total amount of solid components of the composition for a positive electrode material as a reference.
（負極）
本發明之鋰離子二次電池中之負極具有負極活性物質層，較佳為具有負極集電體、及積層於負極集電體上之負極活性物質層。負極活性物質層典型而言，包含負極活性物質、及負極用黏合劑。
作為負極活性物質層所使用之負極活性物質，可列舉石墨、硬碳等碳材料、錫化合物與矽及碳之複合體、鋰等，該等之中，較佳為碳材料，更佳為石墨。
負極活性物質之平均粒徑較佳為0.5〜50 μm，更佳為1〜30 μm，但並無特別限定。負極活性物質之平均粒徑意指藉由雷射繞射-散射法求出之負極活性物質之粒度分布中，體積累計為50%之粒徑（D50）。
負極活性物質層中之負極活性物質之含量以負極活性物質層總量為基準，較佳為50〜98.5質量%，更佳為60〜98質量%。(negative electrode)
The negative electrode in the lithium ion secondary battery of the present invention has a negative electrode active material layer, preferably a negative electrode current collector and a negative electrode active material layer laminated on the negative electrode current collector. The negative electrode active material layer typically includes a negative electrode active material and a negative electrode binder.
Examples of the negative electrode active material used in the negative electrode active material layer include carbon materials such as graphite and hard carbon, composites of tin compounds and silicon and carbon, and lithium. Among these, carbon materials are preferred, and graphite is more preferred. .
The average particle diameter of the negative electrode active material is preferably 0.5 to 50 μm, and more preferably 1 to 30 μm, but it is not particularly limited. The average particle diameter of the negative electrode active material means a particle diameter (D50) of 50% of the volume of the particle size distribution of the negative electrode active material obtained by the laser diffraction-scattering method.
The content of the negative electrode active material in the negative electrode active material layer is based on the total amount of the negative electrode active material layer, preferably 50 to 98.5% by mass, and more preferably 60 to 98% by mass.
負極活性物質層亦可含有導電助劑。導電助劑使用導電性高於上述負極活性物質之材料，具體而言，可列舉科琴黑、乙炔黑、奈米碳管、棒狀碳等碳材料等。
於負極活性物質層中含有導電助劑之情形時，導電助劑之含量以負極活性物質層總量為基準，較佳為1〜30質量%，更佳為2〜25質量%。The negative electrode active material layer may contain a conductive auxiliary agent. As the conductive auxiliary agent, a material having higher conductivity than the above-mentioned negative electrode active material is used. Specific examples include carbon materials such as Ketjen Black, acetylene black, carbon nanotubes, and rod-shaped carbon.
When the negative electrode active material layer contains a conductive auxiliary agent, the content of the conductive auxiliary agent is based on the total amount of the negative electrode active material layer, preferably 1 to 30% by mass, and more preferably 2 to 25% by mass.
作為負極活性物質層中所含有之負極用黏合劑，可使用與上述之正極材料中所使用之黏合劑同種者。
負極活性物質層中之負極用黏合劑之含量以負極活性物質層總量為基準，較佳為1.5〜40質量%，更佳為2.0〜25質量%。
負極活性物質層之厚度並無特別限定，較佳為10〜200 μm，更佳為50〜150 μm。As the binder for the negative electrode contained in the negative electrode active material layer, the same kind as the binder used in the above-mentioned positive electrode material can be used.
The content of the binder for the negative electrode in the negative electrode active material layer is based on the total amount of the negative electrode active material layer, preferably 1.5 to 40% by mass, and more preferably 2.0 to 25% by mass.
The thickness of the negative electrode active material layer is not particularly limited, but is preferably 10 to 200 μm, and more preferably 50 to 150 μm.
作為構成負極集電體之材料，例如，可列舉銅、鋁、鈦、鎳、不鏽鋼等具有導電性之金屬，該等之中，較佳為鋁或銅，更佳為銅。負極集電體一般由金屬箔所構成，其厚度並無特別限定，較佳為1〜50 μm。Examples of the material constituting the negative electrode current collector include conductive metals such as copper, aluminum, titanium, nickel, and stainless steel. Among these, aluminum or copper is preferred, and copper is more preferred. The negative electrode current collector is generally composed of a metal foil, and its thickness is not particularly limited, but is preferably 1 to 50 μm.
（分隔件）
本發明之鋰離子二次電池具備配置於負極與正極之間之分隔件。藉由分隔件，可有效地防止正極及負極之間之短路。又，分隔件亦可保持下述之電解質。
作為分隔件，可列舉多孔性之高分子膜、不織布、玻璃纖維等，該等之中，較佳為多孔性之高分子膜。作為多孔性之高分子膜，可例示乙烯系多孔質膜等烯烴系多孔質膜。(Divider)
The lithium ion secondary battery of the present invention includes a separator disposed between a negative electrode and a positive electrode. The separator can effectively prevent a short circuit between the positive electrode and the negative electrode. In addition, the separator may hold the electrolyte described below.
Examples of the separator include porous polymer films, nonwoven fabrics, and glass fibers. Among these, porous polymer films are preferred. Examples of porous polymer films include olefin-based porous films such as ethylene-based porous films.
（絕緣層）
本發明之鋰離子二次電池亦可為負極活性物質層上或正極活性物質層上具備絕緣層者。藉由絕緣層，可有效地防止正極及負極之間之短路。絕緣層較佳為包含絕緣性微粒子及絕緣層用黏合劑，且具有絕緣性微粒子藉由絕緣層用黏合劑黏結而構成之多孔質結構的層。(Insulation)
The lithium ion secondary battery of the present invention may be one having an insulating layer on the negative electrode active material layer or on the positive electrode active material layer. The insulating layer can effectively prevent a short circuit between the positive electrode and the negative electrode. The insulating layer is preferably a layer containing insulating fine particles and a binder for the insulating layer, and having a porous structure in which the insulating fine particles are bonded with the binder for the insulating layer.
絕緣性微粒子只要為絕緣性則並無特別限定，為有機粒子、無機粒子之任一種均可。作為具體之有機粒子，例如，可列舉由交聯聚甲基丙烯酸甲酯、交聯苯乙烯－丙烯酸共聚物、交聯丙烯腈樹脂、聚醯胺樹脂、聚醯亞胺樹脂、聚(2-丙烯醯胺-2-甲基丙磺酸鋰)、聚縮醛樹脂、環氧樹脂、聚酯樹脂、酚樹脂、三聚氰胺樹脂等有機化合物所構成之粒子。作為無機粒子，可列舉由二氧化矽、氮化矽、氧化鋁、軟水鋁石、氧化鈦、氧化鋯、氮化硼、氧化鋅、二氧化錫、氧化鈮（Nb2
O5
）、氧化鉭（Ta2
O5
）、氟化鉀、氟化鋰、黏土、沸石、碳酸鈣等無機化合物所構成之粒子。又，無機粒子亦可為由鈮-鉭複合氧化物、鎂-鉭複合氧化物等公知之複合氧化物所構成之粒子。絕緣性微粒子可單獨使用1種，亦可併用多種。
絕緣性微粒子之平均粒徑只要小於絕緣層之厚度則並無特別限定，例如為0.001〜1 μm，較佳為0.05〜0.8 μm，更佳為0.1〜0.6 μm。
絕緣層中所含有之絕緣性微粒子之含量以絕緣層總量為基準，較佳為15〜95質量%，更佳為40〜90質量%，進而較佳為60〜85質量%。若絕緣性微粒子之含量於上述範圍內，則絕緣層可形成均一之多孔質結構，且被賦予適當之絕緣性。The insulating fine particles are not particularly limited as long as they are insulating, and may be any of organic particles and inorganic particles. Specific organic particles include, for example, crosslinked polymethylmethacrylate, crosslinked styrene-acrylic copolymer, crosslinked acrylonitrile resin, polyimide resin, polyimide resin, and poly (2- Particles made of organic compounds such as acrylamine-2-methylpropanesulfonate), polyacetal resin, epoxy resin, polyester resin, phenol resin, and melamine resin. Examples of the inorganic particles include silicon dioxide, silicon nitride, aluminum oxide, boehmite, titanium oxide, zirconia, boron nitride, zinc oxide, tin dioxide, niobium oxide (Nb 2 O 5 ), and tantalum oxide. (Ta 2 O 5 ), potassium fluoride, lithium fluoride, clay, zeolite, calcium carbonate and other inorganic compounds. The inorganic particles may be particles composed of a known composite oxide such as a niobium-tantalum composite oxide or a magnesium-tantalum composite oxide. The insulating fine particles may be used singly or in combination.
The average particle diameter of the insulating fine particles is not particularly limited as long as it is smaller than the thickness of the insulating layer, and is, for example, 0.001 to 1 μm, preferably 0.05 to 0.8 μm, and more preferably 0.1 to 0.6 μm.
The content of the insulating fine particles contained in the insulating layer is based on the total amount of the insulating layer, preferably 15 to 95% by mass, more preferably 40 to 90% by mass, and still more preferably 60 to 85% by mass. When the content of the insulating fine particles is within the above range, the insulating layer can form a uniform porous structure and be provided with appropriate insulating properties.
作為絕緣層用黏合劑，可使用與上述正極材料中所使用之黏合劑同種者。絕緣層中之絕緣層用黏合劑之含量以絕緣層總量為基準，較佳為5〜50質量%，更佳為10〜45質量%，進而較佳為15〜40質量%。
絕緣層之厚度較佳為1〜10 μm，更佳為2〜8 μm，進而較佳為3〜7 μm。As the binder for the insulating layer, the same kind as the binder used in the above-mentioned positive electrode material can be used. The content of the adhesive for the insulating layer in the insulating layer is based on the total amount of the insulating layer, preferably 5 to 50% by mass, more preferably 10 to 45% by mass, and still more preferably 15 to 40% by mass.
The thickness of the insulating layer is preferably 1 to 10 μm, more preferably 2 to 8 μm, and even more preferably 3 to 7 μm.
（電解質）
本發明之鋰離子二次電池具備電解質。電解質並無特別限定，使用鋰離子二次電池中所使用之公知之電解質即可。作為電解質，例如使用電解液。
作為電解液，可例示包含有機溶劑及電解質鹽之電解液。作為有機溶劑，例如，可列舉碳酸乙二酯、碳酸丙二酯、碳酸二甲酯、γ-丁內酯、環丁碸、二甲基亞碸、乙腈、二甲基甲醯胺、二甲基乙醯胺、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、四氫呋喃、2-甲基四氫呋喃、二氧戊環、乙酸甲酯等極性溶劑、或該等溶劑之2種以上之混合物。作為電解質鹽，可列舉LiClO4
、LiPF6
、LiBF4
、LiAsF6
、LiSbF6
、LiCF3
CO2
、LiN(SO2
CF3
)2
、LiN(SO2
CF2
CF3
)2
、LiN(COCF3
)2
及LiN(COCF2
CF3
)2
、雙草酸硼酸鋰（LiB(C2
O4
)2
）等包含鋰之鹽。又，可列舉有機酸鋰鹽－三氟化硼錯合物、LiBH4
等錯合物氫化物等錯合物。該等鹽或錯合物可單獨使用1種，亦可為2種以上之混合物。
又，電解質亦可為於上述電解液中進而包含高分子化合物之凝膠狀電解質。作為高分子化合物，例如可列舉聚偏二氟乙烯等氟系聚合物、聚(甲基)丙烯酸甲酯等聚丙烯酸系聚合物。再者，凝膠狀電解質亦可用作分隔件。
電解質配置於負極及正極間即可，例如，電解質液填充於內部收納有上述負極、正極、及分隔件之電池單元內。又，電解質例如亦可塗佈於負極或正極上而配置於負極及正極間。(Electrolyte)
The lithium ion secondary battery of the present invention includes an electrolyte. The electrolyte is not particularly limited, and a known electrolyte used in a lithium ion secondary battery may be used. As the electrolyte, for example, an electrolytic solution is used.
Examples of the electrolytic solution include an electrolytic solution containing an organic solvent and an electrolyte salt. Examples of the organic solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, γ-butyrolactone, cyclobutylammonium, dimethylmethylene, acetonitrile, dimethylformamide, and dimethylformamide. Polar solvents such as ethylacetamide, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dioxolane, methyl acetate, or the like A mixture of two or more solvents. Examples of the electrolyte salt include LiClO 4 , LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 , LiCF 3 CO 2 , LiN (SO 2 CF 3 ) 2 , LiN (SO 2 CF 2 CF 3 ) 2 , and LiN (COCF 3 ) 2 and lithium-containing salts such as LiN (COCF 2 CF 3 ) 2 , lithium bisoxalate borate (LiB (C 2 O 4 ) 2 ), and the like. In addition, examples include complexes such as lithium organic acid salts-boron trifluoride complexes, and complex hydrides such as LiBH 4 . These salts or complexes may be used alone or as a mixture of two or more.
The electrolyte may be a gel-like electrolyte containing a polymer compound in the electrolyte. Examples of the polymer compound include a fluorine-based polymer such as polyvinylidene fluoride, and a polyacrylic polymer such as poly (meth) acrylate. Moreover, a gel-like electrolyte can also be used as a separator.
The electrolyte may be disposed between the negative electrode and the positive electrode. For example, the electrolyte liquid is filled in a battery cell in which the negative electrode, the positive electrode, and the separator are housed. The electrolyte may be applied to, for example, the negative electrode or the positive electrode and disposed between the negative electrode and the positive electrode.
鋰離子二次電池可為分別積層多個負極、正極而成之多層結構。於該情形時，負極及正極沿積層方向交替設置即可。又，分隔件配置於各負極與各正極之間即可，於設置絕緣層之情形時，設置於負極－分隔件間或正極－分隔件間即可。
實施例The lithium ion secondary battery may have a multilayer structure in which a plurality of negative electrodes and positive electrodes are laminated. In this case, the negative electrodes and the positive electrodes may be alternately disposed along the stacking direction. The separator may be disposed between each of the negative electrodes and each of the positive electrodes. In the case where an insulating layer is provided, it may be disposed between the negative electrode-separator or the positive electrode-separator.
Examples
以下，使用實施例進而詳細地說明本發明，但本發明並不限定於該等實施例。Hereinafter, the present invention will be described in detail using examples, but the present invention is not limited to these examples.
所得之鋰離子二次電池係藉由以下之評估方法評估。The obtained lithium ion secondary battery was evaluated by the following evaluation method.
（增黏評估）
對剛製作正極材料用組成物後之黏度、及於室溫（25℃）經過4天後之正極材料用組成物之黏度進行測定。自經過4天後之正極材料用組成物之黏度之值減去剛製作正極材料用組成物後之黏度，求出黏度上升值。
再者，黏度之測定係使用B型黏度計，於條件（25℃，100 rpm）進行測定。
根據以下之基準對黏度上升值進行評估，其值越大，判斷越進行凝膠化。
A：黏度上升值未達500 cps
B：黏度上升值為500 cps以上且未達1500 cps
C：黏度上升值為1500 cps以上且未達2500 cps
D：黏度上升值為2500 cps以上(Viscosity assessment)
The viscosity immediately after the composition for the positive electrode material was produced, and the viscosity of the composition for the positive electrode material after 4 days at room temperature (25 ° C) were measured. The viscosity increase value was obtained by subtracting the viscosity immediately after the composition for the positive electrode material was made from the viscosity of the composition for the positive electrode material after 4 days.
The viscosity was measured using a B-type viscometer under conditions (25 ° C, 100 rpm).
The viscosity increase value was evaluated based on the following criteria. The larger the value, the more gelatinization was judged.
A: Viscosity rise is less than 500 cps
B: Viscosity rise value is more than 500 cps and less than 1500 cps
C: Viscosity rise value is more than 1500 cps and less than 2500 cps
D: Viscosity rise value is above 2500 cps
（正極活性物質層之密度評估）
正極活性物質層之密度可以如下方式測定。首先，準備多片將正極按特定之大小（例如，直徑16 mm）沖裁而得之測定試樣。藉由精密天平稱量各測定試樣之質量，從而測定質量。自測定結果減去預先測得之正極集電體之質量，藉此，可算出測定試樣中之正極活性物質層之質量。又，藉由利用SEM對經剖面露出加工之測定試樣進行觀察等公知之方法，對正極活性物質層之厚度進行測定。可自各測定值之平均值根據下述式（1）算出正極活性物質層之密度。
正極活性物質層之密度（g/cc）＝正極活性物質層之質量（g）/[正極活性物質層之厚度（cm）×沖裁之正極之面積（cm2
）] （1）(Density evaluation of the positive electrode active material layer)
The density of the positive electrode active material layer can be measured as follows. First, prepare a plurality of measurement samples obtained by punching a positive electrode into a specific size (for example, a diameter of 16 mm). The mass of each measurement sample is measured by a precision balance to measure the mass. The mass of the positive electrode current collector measured in advance is subtracted from the measurement result, whereby the mass of the positive electrode active material layer in the measurement sample can be calculated. In addition, the thickness of the positive electrode active material layer is measured by a known method such as observing a measurement sample subjected to cross-section exposure processing with a SEM. The density of the positive electrode active material layer can be calculated from the average of each measured value according to the following formula (1).
Density of the positive electrode active material layer (g / cc) = mass of the positive electrode active material layer (g) / [thickness of the positive electrode active material layer (cm) × area of the positive electrode punched (cm 2 )] (1)
根據以下之基準對所得之正極活性物質層之密度進行評估。
A：3.50 g/cc以上
B：3.45 g/cc以上且未達3.50 g/cc
C：3.40 g/cc以上且未達3.45 g/cc
D：未達3.40 g/ccThe density of the obtained positive electrode active material layer was evaluated based on the following criteria.
A: above 3.50 g / cc
B: 3.45 g / cc or more and less than 3.50 g / cc
C: 3.40 g / cc or more and less than 3.45 g / cc
D: less than 3.40 g / cc
（輸出特性評估）
對各實施例、比較例中所製作之鋰離子二次電池如下所述求出放電電容，藉此進行評估。
進行20 A之定電流充電，其次，到達4.2 V後逐漸減少電流，於變為0.2 A之時進行結束充電之定電壓充電。其後，進行200 A之定電流放電，進行設為放電至2.5 V之時結束放電之放電，計算放電電容。根據以下之基準對輸出特性進行評估。
A：與2 A之定電流之放電電容相比，200 A之放電電容為30%以上
B：與2 A之定電流之放電電容相比，200 A之放電電容為20%以上且未達30%
C：與2 A之定電流之放電電容相比，200 A之放電電容為10%以上且未達20%
D：與2 A之定電流之放電電容相比，200 A之放電電容未達10%(Evaluation of output characteristics)
The lithium ion secondary batteries produced in each of the examples and comparative examples were evaluated as follows by determining the discharge capacitance.
The charging is performed at a constant current of 20 A. Secondly, the current is gradually reduced after reaching 4.2 V, and the constant voltage charging at the end of charging is performed when it reaches 0.2 A. Thereafter, a constant current discharge of 200 A was performed, and the discharge was set to be completed when the discharge reached 2.5 V, and the discharge capacitance was calculated. The output characteristics were evaluated based on the following criteria.
A: Compared with a discharge capacitor with a constant current of 2 A, a discharge capacitor of 200 A is more than 30%
B: Compared with a 2 A constant-current discharge capacitor, a 200 A discharge capacitor is more than 20% and less than 30%
C: Compared with a discharge capacitor with a constant current of 2 A, a discharge capacitor of 200 A is more than 10% and less than 20%
D: Compared with a discharge capacitor with a constant current of 2 A, the discharge capacitor at 200 A does not reach 10%
[實施例1]
（正極之製作）
將作為正極活性物質之平均粒徑為10 μm之鋰鎳鈷鋁系氧化物（NCA：Li1.0
Ni0.8
Co0.16
Al0 . 03
O2
）94質量份、奈米碳管2質量份、作為黏合劑之聚偏二氟乙烯（PVDF）3質量份、作為酸之草酸1質量份、及作為溶劑之N-甲基吡咯啶酮（NMP）混合。上述之奈米碳管（CNT）使用長度為5 μm、縱橫比為2778者。藉此，獲得固形物成分濃度調整為60質量%之正極材料用組成物。將該正極材料用組成物塗佈於作為正極集電體之厚度為15 μm之鋁箔之兩面，預乾燥後，於120℃進行真空乾燥。其後，將於兩面塗佈有正極材料用組成物之正極集電體於400 kN/m下進行輥壓，進而沖裁成電極尺寸為100 mm×200 mm見方，製成兩面具有正極材料（正極活性物質層）之正極。[Example 1]
(Production of positive electrode)
An average particle diameter of the positive electrode active material is 10 μm of lithium nickel cobalt aluminum oxide (NCA:. Li 1.0 Ni 0.8 Co 0.16 Al 0 03 O 2) 94 parts by mass, 2 parts by mass of carbon nanotubes, a bonding 3 parts by mass of polyvinylidene fluoride (PVDF) as an agent, 1 part by mass of oxalic acid as an acid, and N-methylpyrrolidone (NMP) as a solvent were mixed. The carbon nanotubes (CNTs) described above are those having a length of 5 μm and an aspect ratio of 2778. Thereby, the composition for positive electrode materials whose solid content concentration was adjusted to 60 mass% was obtained. This composition for a positive electrode material was coated on both sides of an aluminum foil having a thickness of 15 μm as a positive electrode current collector, pre-dried, and vacuum-dried at 120 ° C. Thereafter, the positive electrode current collector coated with the composition for the positive electrode material on both sides was rolled at 400 kN / m, and then punched into an electrode size of 100 mm × 200 mm square, to prepare a positive electrode material on both sides ( Positive electrode active material layer).
（負極之製作）
將作為負極活性物質之石墨（平均粒徑為10 μm）100質量份、作為黏合劑之苯乙烯丁二烯橡膠1.5質量份、羧甲基纖維素（CMC）之鈉鹽1.5質量份、及作為溶劑之水混合，獲得固形物成分調整為50質量%之負極材料用組成物。將該負極材料用組成物塗佈於作為負極集電體之厚度為15 μm之銅箔之兩面，於100℃進行真空乾燥。其後，將於兩面塗佈有負極材料用組成物之負極集電體於線壓500 kN/m進行輥壓，製成負極。再者，負極之尺寸為110 mm×210 mm。(Production of negative electrode)
100 parts by mass of graphite (average particle size: 10 μm) as a negative electrode active material, 1.5 parts by mass of styrene butadiene rubber as a binder, 1.5 parts by mass of sodium salt of carboxymethyl cellulose (CMC), and The solvent was mixed with water to obtain a composition for a negative electrode material having a solid content adjusted to 50% by mass. This negative electrode material composition was applied to both sides of a copper foil having a thickness of 15 μm as a negative electrode current collector, and vacuum dried at 100 ° C. Thereafter, a negative electrode current collector coated with a composition for a negative electrode material on both sides was rolled at a linear pressure of 500 kN / m to prepare a negative electrode. Moreover, the size of the negative electrode is 110 mm × 210 mm.
（電解液之製備）
於按3：7之體積比（EC：DEC）混合碳酸乙二酯（EC）與碳酸二乙酯（DEC）而成之溶劑中以成為1莫耳/升之方式溶解作為電解質鹽之LiPF6
，製備電解液。(Preparation of electrolyte)
LiPF 6 as an electrolyte salt was dissolved in a solvent prepared by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at a volume ratio of 3: 7 (EC: DEC) to 1 mol / liter. To prepare an electrolyte.
（鋰離子二次電池之製造）
將上述所得之負極10片、正極9片、及分隔件18片積層，獲得預積層體。此處，負極與正極係交替配置，於各負極與正極之間配置分隔件。又，作為分隔件，使用聚乙烯製多孔質膜。
將各正極之正極集電體之露出部之端部統一藉由超音波熔接進行接合，並接合突出於外部之端子用引板。同樣地，對各負極之負極集電體之露出部之端部統一藉由超音波熔接進行接合，並接合突出於外部之端子用引板。
其次，藉由鋁層壓膜夾住上述積層體，使端子用引板突出於外部，藉由層壓加工將三邊進行密封。自剩餘未密封之一邊注入上述所得之電解液，並進行真空密封，藉此製造層疊型之單元。
將所得之鋰離子二次電池之評估結果表示於表1。(Manufacture of lithium-ion secondary batteries)
The 10 negative electrodes, 9 positive electrodes, and 18 separators obtained as described above were laminated to obtain a pre-laminated body. Here, the negative electrode and the positive electrode are alternately arranged, and a separator is disposed between each negative electrode and the positive electrode. As the separator, a polyethylene porous film was used.
The ends of the exposed portions of the positive electrode current collectors of the respective positive electrodes were uniformly joined by ultrasonic welding, and the terminal lead plates protruding to the outside were joined. Similarly, the ends of the exposed portions of the negative electrode current collectors of the respective negative electrodes are uniformly joined by ultrasonic welding, and the terminal lead plates protruding from the outside are joined.
Next, the laminated body is sandwiched by an aluminum laminate film, the terminal lead plate is protruded to the outside, and three sides are sealed by lamination. The obtained electrolytic solution was injected from the remaining unsealed one and vacuum-sealed to manufacture a laminated cell.
The evaluation results of the obtained lithium ion secondary battery are shown in Table 1.
[實施例2]
除將奈米碳管變更為長度為15 μm、縱橫比為100者以外，以與實施例1相同之方式獲得鋰離子二次電池。將評估結果表示於表1。[Example 2]
A lithium ion secondary battery was obtained in the same manner as in Example 1, except that the carbon nanotube was changed to a length of 15 μm and an aspect ratio of 100. The evaluation results are shown in Table 1.
[實施例3]
除將酸之種類變更為順丁烯二酸以外，以與實施例1相同之方式獲得鋰離子二次電池。將評估結果表示於表1。[Example 3]
A lithium ion secondary battery was obtained in the same manner as in Example 1 except that the type of the acid was changed to maleic acid. The evaluation results are shown in Table 1.
[比較例1]
除將奈米碳管變更為長度為60 μm、縱橫比為8000者以外，以與實施例1相同之方式獲得鋰離子二次電池。將評估結果表示於表1。[Comparative Example 1]
A lithium ion secondary battery was obtained in the same manner as in Example 1 except that the carbon nanotube was changed to a length of 60 μm and an aspect ratio of 8000. The evaluation results are shown in Table 1.
[比較例2]
除將正極活性物質之種類變更為鎳錳鈷系氧化物（NMC）以外，以與實施例1相同之方式獲得鋰離子二次電池。將評估結果表示於表1。[Comparative Example 2]
A lithium ion secondary battery was obtained in the same manner as in Example 1 except that the type of the positive electrode active material was changed to a nickel-manganese-cobalt-based oxide (NMC). The evaluation results are shown in Table 1.
[比較例3]
除將奈米碳管變更為長度為30 μm、縱橫比為12000者以外，以與實施例1相同之方式獲得鋰離子二次電池。將評估結果表示於表1。[Comparative Example 3]
A lithium ion secondary battery was obtained in the same manner as in Example 1, except that the carbon nanotube was changed to a length of 30 μm and an aspect ratio of 12,000. The evaluation results are shown in Table 1.
[比較例4]
除使用長度為0.05 μm、縱橫比為1之碳系導電粒子（Denka公司製造之Denka Black HS-100）代替奈米碳管以外，以與實施例1相同之方式製作鋰離子二次電池。[Comparative Example 4]
A lithium-ion secondary battery was produced in the same manner as in Example 1 except that carbon-based conductive particles (Denka Black HS-100 manufactured by Denka Corporation) with a length of 0.05 μm and an aspect ratio of 1 were used instead of the carbon nanotubes.
[比較例5]
除使用3質量份之長度為6 μm、縱橫比為40之氣相生長碳纖維（昭和電工股份有限公司製造，商品名「VGCF-H」）代替奈米碳管以外，以與實施例1相同之方式製作鋰離子二次電池。[Comparative Example 5]
Except that 3 parts by mass of a vapor-grown carbon fiber (manufactured by Showa Denko Corporation, trade name "VGCF-H") having a length of 6 μm and an aspect ratio of 40 was used instead of the carbon nanotube, the same procedure as in Example 1 Method to produce a lithium ion secondary battery.
[參考例1]
除不使用酸以外，以與實施例1相同之方式進行實驗。正極材料用組成物之黏度過高，無法製作正極。[Reference Example 1]
The experiment was performed in the same manner as in Example 1 except that no acid was used. The viscosity of the composition for a positive electrode material is too high to make a positive electrode.
[表1]
可知使用本發明之鋰離子二次電池用正極材料之實施例1〜3之鋰離子二次電池的正極之密度高，輸出特性亦變得良好。
另一方面，未使用本發明之鋰離子二次電池用電極之比較例1〜5之鋰離子電池的正極之密度均低於實施例1〜3之鋰離子二次電池之正極之密度。It can be seen that the positive electrode of the lithium ion secondary battery of Examples 1 to 3 using the positive electrode material for a lithium ion secondary battery of the present invention has a high density and good output characteristics.
On the other hand, the densities of the positive electrodes of the lithium-ion batteries of Comparative Examples 1 to 5 without using the electrodes for lithium-ion secondary batteries of the present invention were lower than the densities of the positive electrodes of the lithium-ion secondary batteries of Examples 1 to 3.
10‧‧‧鋰離子二次電池10‧‧‧ Lithium-ion secondary battery
11‧‧‧負極 11‧‧‧ Negative
11a‧‧‧負極集電體 11a‧‧‧Negative current collector
11b‧‧‧負極活性物質層 11b‧‧‧Negative electrode active material layer
12‧‧‧正極 12‧‧‧Positive
12a‧‧‧正極集電體 12a‧‧‧Positive collector
12b‧‧‧正極活性物質層 12b‧‧‧Positive electrode active material layer
13‧‧‧分隔件 13‧‧‧ divider
圖1係表示本發明之鋰離子二次電池之一實施形態之概略剖視圖。FIG. 1 is a schematic cross-sectional view showing an embodiment of a lithium ion secondary battery of the present invention.
Claims (11)
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| KR102643670B1 (en) * | 2020-03-26 | 2024-03-04 | 삼성에스디아이 주식회사 | Rechargeable lithium battery |
| JP7216052B2 (en) | 2020-08-20 | 2023-01-31 | プライムプラネットエナジー＆ソリューションズ株式会社 | Positive electrode for secondary battery and secondary battery |
| CN112090382A (en) * | 2020-08-28 | 2020-12-18 | 江苏富矿智能科技有限公司 | Novel size mixing device for lithium ion battery production and size mixing method thereof |
| EP4224557A1 (en) * | 2020-09-30 | 2023-08-09 | Panasonic Intellectual Property Management Co., Ltd. | Positive electrode for nonaqueous electrolyte secondary batteries, and nonaqueous electrolyte secondary battery |
| JP7461309B2 (en) * | 2021-01-27 | 2024-04-03 | プライムプラネットエナジー＆ソリューションズ株式会社 | Material for forming positive electrode active material layer and non-aqueous electrolyte secondary battery using said material for forming positive electrode active material layer |
| JP7219783B2 (en) * | 2021-03-10 | 2023-02-08 | プライムプラネットエナジー＆ソリューションズ株式会社 | Non-aqueous electrolyte secondary battery |
| KR102623098B1 (en) * | 2022-01-13 | 2024-01-08 | 에스케이온 주식회사 | Cathode slurry for lithium secondary battery, preparation method of cathode for lithium secondary battery, cathode for lithium secondary battery, and lithium secondary battery including the same |
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| JPH1079244A (en) * | 1996-09-04 | 1998-03-24 | Toray Ind Inc | Electrode and nonaqueous electrolyte second battery using it |
| EP2673823B1 (en) * | 2011-02-07 | 2015-12-09 | Umicore | High nickel cathode material having low soluble base content |
| JP2013122859A (en) * | 2011-12-12 | 2013-06-20 | Panasonic Corp | Nonaqueous electrolyte secondary battery |
| JP6709586B2 (en) * | 2014-08-26 | 2020-06-17 | 東洋インキＳｃホールディングス株式会社 | Carbon black dispersion and its use |
| JP2016058257A (en) * | 2014-09-10 | 2016-04-21 | 三菱マテリアル株式会社 | Positive electrode for lithium ion secondary battery, and lithium ion secondary battery |
| JPWO2016068258A1 (en) * | 2014-10-29 | 2017-06-29 | 株式会社東芝 | Positive electrode and non-aqueous electrolyte battery |
| JP2016134218A (en) * | 2015-01-16 | 2016-07-25 | 日本電気株式会社 | Lithium ion secondary battery |
| JP2019061734A (en) * | 2015-12-25 | 2019-04-18 | 株式会社日立製作所 | Lithium ion secondary battery |
| JP2017142997A (en) * | 2016-02-10 | 2017-08-17 | 戸田工業株式会社 | Lithium nickelate-carbon composite positive electrode active material particle powder, and manufacturing method thereof, and nonaqueous electrolyte secondary battery |
-
2019
- 2019-02-27 TW TW108106841A patent/TW201939798A/en unknown
- 2019-02-27 JP JP2020503571A patent/JP6841971B2/en active Active
- 2019-02-27 WO PCT/JP2019/007580 patent/WO2019168035A1/en active Application Filing
Also Published As
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|---|---|
| WO2019168035A1 (en) | 2019-09-06 |
| JPWO2019168035A1 (en) | 2020-08-20 |
| JP6841971B2 (en) | 2021-03-10 |
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