KR20140048010A - Positive electrode for lithium ion secondary battery and lithium ion secondary battery including the same - Google Patents
Positive electrode for lithium ion secondary battery and lithium ion secondary battery including the same Download PDFInfo
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- 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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- H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
- H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
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- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
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Abstract
Description
본 발명은 리튬을 과량 함유하는 양극활물질층을 포함하는 리튬이온 이차전지용 양극 및 이를 포함하는 리튬이온 이차전지에 관한 것으로, 상세하게는 전이금속 대비 1당량을 초과하는 리튬을 함유하는 양극활물질층 및 리튬이온 전도층을 포함하는 양극 및 이를 포함하는 리튬이온 이차전지에 관한 것이다.The present invention relates to a positive electrode for a lithium ion secondary battery comprising a positive electrode active material layer containing an excessive amount of lithium, and a lithium ion secondary battery comprising the positive electrode active material layer. More particularly, the present invention relates to a positive electrode active material layer containing lithium in excess of 1 equivalent to the transition metal A lithium ion conductive layer, and a lithium ion secondary battery comprising the same.
최근 전기자동차, 하이브리드 자동차에 이차전지가 사용됨에 따라 고안전성 및 고용량의 전지성능을 기본적으로 요구하고 있다. 그래서 리튬이온 이차전지용 양극활물질에 대한 연구는 기존의 LiCoO2, LiMn2O4 등을 대체하여 4.2 V 이상의 고충전 전압에서 안정하고 고에너지 밀도의 우수한 특성을 갖는 물질을 찾고자 하는 방향으로 진행되었다. 그 결과 니켈-망간 또는 니켈-코발트-망간이 각각 1:1 또는 1:1:1로 혼합된 리튬금속산화물을 양극활물질에 사용하기 위한 시도 및 연구가 많이 행해졌다. 니켈, 코발트 또는 망간을 혼합하여 제조된 양극활물질은 각각의 전이금속들을 따로 사용하여 제조한 전지에 비해 제반 물성 및 전지 특성이 향상되었지만 망간 이온의 용출, 전해질의 분해, 산소 발생 등의 단점을 나타내고 있다.BACKGROUND ART [0002] In recent years, secondary batteries are used in electric vehicles and hybrid vehicles, and therefore, high performance and high capacity battery performance are basically required. Therefore, the study on the cathode active material for the lithium ion secondary battery has been carried out in order to replace the existing LiCoO 2 , LiMn 2 O 4 and the like, and to find a material having excellent characteristics of stable and high energy density at a high charging voltage of 4.2 V or more. As a result, many attempts and studies have been made to use a lithium metal oxide mixed with nickel-manganese or nickel-cobalt-manganese at a ratio of 1: 1 or 1: 1: 1, respectively, in the cathode active material. The cathode active material prepared by mixing nickel, cobalt, or manganese has improved physical properties and battery characteristics as compared with batteries prepared using the respective transition metals separately, but exhibits disadvantages such as elution of manganese ions, decomposition of electrolytes, and oxygen generation have.
상기 문제점을 해결하기 위해서, 본 발명은 리튬을 과량 함유하는 리튬금속산화물을 포함하는 양극활물질층 상에 리튬이온 전도층을 적층함으로써, 리튬이온 이동에는 문제 없이 망간 용출, 충전시 산소 발생, 전해질 분해 반응 등으로 인한 수명 저하 문제를 개선하고, 고용량의 전지를 제조하고자 한다.In order to solve the above problems, the present invention relates to a lithium ion secondary battery comprising a positive electrode active material layer containing a lithium-containing lithium oxide in an excess amount, wherein the lithium ion conductive layer is laminated on the positive electrode active material layer, The problem of lowering the lifetime due to the reaction or the like is solved and an attempt is made to produce a high capacity battery.
본 발명은 상기 과제를 해결하기 위하여, 양극 집전체, 상기 양극 집전체 상에 적층된 양극활물질층 및 상기 양극활물질층에 적층된 리튬이온 전도층을 포함하고, 상기 양극활물질층은 화학식 (1)로 표시되는 리튬금속산화물을 포함하는 것을 특징으로 하는 리튬이온 이차전지용 양극을 제공한다. The positive electrode active material layer includes a positive electrode current collector, a positive electrode active material layer laminated on the positive electrode current collector, and a lithium ion conductive layer laminated on the positive electrode active material layer, The positive electrode for a lithium ion secondary battery according to the present invention comprises a lithium metal oxide represented by the following formula:
Li1 + xM1 - xO2 (1)Li 1 + x M 1 - x O 2 (1)
(상기 화학식에서, x ≥ 0.05이고, M은 Co, Ni, Mn, Al, Zr, Ti, W, Mo, Fe, V, Cr 및 Cu로 이루어진 군에서 선택된 1종 이상이다.)Wherein M is at least one selected from the group consisting of Co, Ni, Mn, Al, Zr, Ti, W, Mo, Fe, V, Cr and Cu.
본 발명은 또한 상기 양극, 전해질 및 음극을 포함하는 리튬이온 이차전지를 제공한다.The present invention also provides a lithium ion secondary battery comprising the positive electrode, the electrolyte and the negative electrode.
본 발명에 따르면, 리튬을 과량 함유하는 리튬금속산화물과 전해질의 계면 접촉을 방지하며 리튬이온의 이동도는 높일 수 있는 고상의 리튬이온 전도층을 도입함으로써, 상기 리튬금속산화물과 전해질의 부반응을 억제하고 망간 용출, 산소 발생 등의 문제를 개선하여 전지의 수명을 획기적으로 향상시키며, 고용량의 전지를 제조할 수 있다.According to the present invention, by introducing a solid-state lithium ion conductive layer which prevents interfacial contact between the lithium metal oxide containing an excessive amount of lithium and the mobility of lithium ions and suppresses side reactions between the lithium metal oxide and the electrolyte It is possible to improve the lifetime of the battery by improving the problems such as elution of manganese and generation of oxygen, and to manufacture a high capacity battery.
도 1은 종래의 양극을 개략적으로 나타낸 것이다.
도 2는 본 발명에 따른 양극을 개략적으로 나타낸 것이다.Figure 1 schematically shows a conventional anode.
Figure 2 schematically illustrates the anode according to the invention.
본 발명은 양극 집전체, 상기 양극 집전체 상에 적층된 양극활물질층 및 상기 양극활물질층에 적층된 리튬이온 전도층을 포함하고, 상기 양극활물질층은 화학식 (1)로 표시되는 리튬금속산화물을 포함하는 것을 특징으로 하는 리튬이온 이차전지용 양극에 관한 것이다.The present invention provides a lithium secondary battery comprising a positive electrode collector, a positive electrode active material layer laminated on the positive electrode collector, and a lithium ion conductive layer laminated on the positive electrode active material layer, wherein the positive electrode active material layer comprises a lithium metal oxide represented by the formula (1) The present invention relates to a positive electrode for a lithium ion secondary battery.
Li1 + xM1 - xO2 (1)Li 1 + x M 1 - x O 2 (1)
(상기 화학식 (1)에서, x ≥ 0.05이고, M은 Co, Ni, Mn, Al, Zr, Ti, W, Mo, Fe, V, Cr 및 Cu로 이루어진 군에서 선택된 1종 이상이다.)Wherein M is at least one selected from the group consisting of Co, Ni, Mn, Al, Zr, Ti, W, Mo, Fe, V, Cr and Cu.
상기 화학식 (1)로 표시되는 리튬금속산화물은 하기 화학식 (2)로 표시되는 리튬금속산화물인 것이 바람직하다. The lithium metal oxide represented by the above formula (1) is preferably a lithium metal oxide represented by the following formula (2).
LiaNixCoyMnzO2 (2)Li a Ni x Co y Mn z O 2 (2)
(상기 화학식 (2)에서, a ≥ 1.05, 0 < x < 1, 0 < y < 1 ,0 < z < 1 , a+x+y+z = 2 이다.)(A? 1.05, 0 <x <1, 0 <y <1, 0 <z <1, a + x + y + z = 2 in the formula (2)
상기 화학식 (2)로 표시되는 리튬금속산화물은 과량의 리튬으로 인해 하기 화학식 (3)으로 표시되는 두가지 상으로 이루어져 있는데, 하나는 층상 구조의 LiNiaCobMncO2 (LiMO2) 상이고, 다른 하나는 층상구조의 Li2MnO3 상이다. The lithium metal oxide represented by the formula (2) is composed of two phases represented by the following formula (3) due to excess lithium, one of which is a layered LiNi a Co b Mn c O 2 (LiMO 2 ) phase, And the other is a layered Li 2 MnO 3 phase.
xLiNiaCobMncO2―(1-x)Li2MnO3 (3)xLiNi a Co b Mn c O 2 - (1-x) Li 2 MnO 3 (3)
(상기 화학식 (3)에서, 0 < x < 1, 0 < a < 1, 0 < b < 1, 0 < c < 1, a+b+c = 1 이다.)(0 <x <1, 0 <a <1, 0 <b <1, 0 <c <1, a + b + c = 1 in the formula (3)
LiMO2 상은 가역적인 충방전을 진행하는 활성 영역이고, Li2MnO3 상은 4.4 V 이하에서 Mn4 +를 가지는 비활성 영역이다. 그런데 Li2MnO3는 4.4 V 이상에서 전기화학 반응이 일어나는데, 이 경우 MnO2가 생성되면서 활성물질로 변한다.The LiMO 2 phase is an active region that undergoes reversible charge and discharge, and Li 2 MnO 3 The phase is an inactive region with Mn 4 + below 4.4 V. However, Li 2 MnO 3 electrochemically reacts at a voltage of 4.4 V or higher. In this case, MnO 2 is converted into an active material.
LiMO2 영역 (활성) LiMO2 → MO2 + Li+ + e- (4)LiMO 2 region (active) LiMO 2 → MO 2 + Li + + e - (4)
Li2MnO3 영역 (비활성) Li2MnO3 → MnO2 + 2Li+ + ½ O2 + 2e- (5)Li 2 MnO 3 region (inactive) Li 2 MnO 3 ? MnO 2 + 2Li + + ½O 2 + 2e - (5)
본 발명의 리튬이온 이차전지용 양극은 상기 화학식 (1)로 표시되는 리튬이 전이금속 대비 1당량을 초과하여 함유하는 리튬금속산화물을 포함하는 양극활물질층 상에 리튬이온 전도층이 적층된 것이다. 따라서 양극활물질층 상에 리튬이온 전도층이 형성되어 전지를 형성하였을 때 양극활물질과 전해질 사이에 위치하여 리튬금속산화물과 전해질의 계면 접촉을 방지하면서 리튬이온의 이동도를 높이는 역할을 한다. 따라서 양극활물질층의 리튬금속산화물과 전해질의 부반응을 방지하고 전지 수명을 획기적으로 향상시킬 수 있다. The positive electrode for a lithium ion secondary battery of the present invention is a lithium ion conductive layer laminated on a positive electrode active material layer containing a lithium metal oxide represented by the above formula (1) and containing lithium in excess of 1 equivalent based on the transition metal. Therefore, when a lithium ion conductive layer is formed on the cathode active material layer, the lithium ion conductive layer is positioned between the cathode active material and the electrolyte to prevent interfacial contact between the lithium metal oxide and the electrolyte, thereby enhancing the mobility of lithium ions. Therefore, it is possible to prevent a side reaction between the lithium metal oxide and the electrolyte in the positive electrode active material layer and significantly improve battery life.
상기 리튬이온 전도층은 리튬산화물 및 리튬인산화물로 이루어진 군에서 선택된 1종 이상을 포함할 수 있다. 리튬산화물로는 (La,Li)TiO3, Li3BO2.5N0 .5, Li9SiAlO8 등이 사용될 수 있고, 리튬인산화물로는 Li1 + xTi2 - xAlx(PO4)3, Li1 + xAlxGe2 -x(PO4)3, Li1 + xTi2 - xAlxSiy(PO4)3-y, Li0 .8La0 .6Zr2(PO4)3, LiTixZr2(PO4)3, LiAlZr(PO4)3 등이 사용될 수 있다(상기 식에서 0 < x < 1, 0 < y < 1임). The lithium ion conductive layer may include at least one selected from the group consisting of lithium oxide and lithium phosphorus oxide. Examples of the lithium oxide include (La, Li) TiO 3 , Li 3 BO 2 . 5 N 0 .5, Li 9 SiAlO as may be used, such as lithium phosphorus oxide 8 is Li 1 + x Ti 2 - x Al x (PO 4) 3, Li 1 + x Al x Ge 2 -x (PO 4 ) 3, Li 1 + x Ti 2 - x Al x Si y (PO 4) 3-y, Li 0 .8 La 0 .6 Zr 2 (PO 4) 3, LiTi x Zr 2 (PO 4) 3, LiAlZr (PO 4 ) 3, and the like can be used (0 <x <1, 0 <y <1 in the above formula).
상기 리튬이온 전도층의 두께는 100nm 이상 1㎛ 이하인 것이 바람직하다. 두께가 1㎛를 초과하는 경우 리튬이온의 이동을 방해하여 전지의 출력특성을 저하시킬 수 있으며 100nm 미만인 경우에는 양극을 보호하는 기능을 충분히 할 수 없으며, 제작 공정이 복잡해진다. The thickness of the lithium ion conductive layer is preferably 100 nm or more and 1 占 퐉 or less. When the thickness exceeds 1 탆, the lithium ion is prevented from moving and the output characteristics of the battery may be deteriorated. When the thickness is less than 100 nm, the function of protecting the positive electrode can not be sufficiently performed, and the manufacturing process becomes complicated.
본 발명의 리튬이온 이차전지용 양극은 양극 집전체 상에 양극활물질층을 도포한 후 건조하고, 상기 형성된 양극활물질층 상에 리튬이온 전도층을 도포하여 제조할 수 있다. The positive electrode for a lithium ion secondary battery of the present invention can be manufactured by applying a positive electrode active material layer on a positive electrode current collector, followed by drying, and coating a lithium ion conductive layer on the formed positive electrode active material layer.
상기 양극 집전체는 양극활물질의 전기화학반응에 의해 발생된 전자를 모으거나 전기화학반응에 필요한 전자를 공급하는 역할을 하며 도전성을 갖는다. 양극 집전체로는 알루미늄, 스테인리스 스틸, 니켈, 티탄, 소성 탄소 등을 사용할 수 있다.The cathode current collector functions to collect electrons generated by the electrochemical reaction of the cathode active material or to supply electrons necessary for the electrochemical reaction and has conductivity. As the positive electrode collector, aluminum, stainless steel, nickel, titanium, sintered carbon, or the like can be used.
본 발명에 있어서, 상기 양극 집전체의 표면에 미세한 요철을 형성하여 양극 활물질층의 결합력을 강화시킬 수도 있으며, 필름, 시트, 호일, 네트, 다공질체, 발포체, 부직포체 등 다양한 형태로 사용될 수 있다.In the present invention, fine unevenness may be formed on the surface of the positive electrode collector to enhance the bonding force of the positive electrode active material layer, and it may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, .
상기 양극활물질층은 리튬금속산화물, 도전재 및 바인더를 용매 중에 혼합, 분산시켜서 얻은 슬러리를 양극 집전체 상에 도포하고 건조하여 형성될 수 있다. The cathode active material layer may be formed by coating a slurry obtained by mixing and dispersing a lithium metal oxide, a conductive material, and a binder in a solvent on a cathode current collector, followed by drying.
상기 리튬금속산화물은 예를 들어 반응기에서 각기 다른 농도의 NiSO4, CoSO4, MnSO4, 암모니아수, NaOH 용액을 혼합하여 전이금속 전구체를 공침법으로 제조한 후, 상기 전이금속 전구체에 탄산리튬을 균일하게 혼합하고 열처리를 통해 제조할 수 있다. 상기 열처리는 600 ~ 1000 ℃의 온도에서 10시간 내지 30시간 동안 진행되는 것이 바람직하다. 열처리 후 얻은 리튬금속산화물은 추가로 그라인딩 및 분체 공정을 거칠 수 있다. The lithium metal oxide is prepared by coprecipitation of a transition metal precursor by mixing NiSO 4 , CoSO 4 , MnSO 4 , ammonia water, and NaOH solution of different concentrations in a reactor, for example, to uniform lithium carbonate to the transition metal precursor. Can be mixed and prepared by heat treatment. The heat treatment is preferably performed at a temperature of 600 to 1000 ° C. for 10 to 30 hours. The lithium metal oxide obtained after the heat treatment may be further subjected to a grinding and powder process.
상기 바인더는 활물질과 도전재를 결착시켜서 집전체에 고정시키는 역할을 하며, 폴리비닐리덴플로라이드, 폴리프로필렌, 카르복시메틸셀룰로오스, 전분, 히드록시프로필셀룰로오스, 폴리비닐피롤리돈, 테트라플루오로에틸렌, 폴리에틸렌, 에틸렌-프로필렌-디엔 폴리머(EPDM), 폴리비닐알코올, 스티렌-부타디엔 고무, 불소 고무 등 리튬이온 이차전지에서 통상적으로 사용되는 것들을 사용할 수 있다. The binder serves to fix the active material and the conductive material to fix the current collector, polyvinylidene fluoride, polypropylene, carboxymethyl cellulose, starch, hydroxypropyl cellulose, polyvinylpyrrolidone, tetrafluoroethylene, Polyethylene, ethylene-propylene-diene polymer (EPDM), polyvinyl alcohol, styrene-butadiene rubber, fluorine rubber, such as those commonly used in lithium ion secondary batteries can be used.
상기 도전재는 전지에 화학적 변화를 유발하지 않으면서 도전성을 가진 것이라면 특별히 제한되는 것은 아니고, 예컨대 인조 흑연, 천연 흑연, 아세틸렌 블랙, 덴카 블랙, 케첸 블랙, 채널 블랙, 램프 블랙, 서머 블랙, 탄소 섬유나 금속 섬유 등의 도전성 섬유, 산화 티탄 등의 도전성 금속 산화물, 알루미늄, 니켈 등의 금속 분말 등이 사용될 수 있다.The conductive material is not particularly limited so long as it has conductivity without causing chemical change in the battery, and for example, artificial graphite, natural graphite, acetylene black, denka black, ketjen black, channel black, lamp black, summer black, carbon fiber, Conductive fibers such as metal fibers, conductive metal oxides such as titanium oxide, metal powders such as aluminum and nickel, and the like can be used.
본 발명의 리튬이온 전도층은 용매(예를 들어 NMP)에 분산된 리튬이온 전도체 물질을 양극활물질층 상에 코팅하고 건조시킴으로써 제조될 수 있다. 상기 리튬이온 전도체 물질은 예를 들어 산화물, 인산화물을 사용할 수 있으며, 리튬이온 전도층의 두께는 100nm 이상 1㎛ 이하인 것이 바람직하다. 두께가 1㎛를 초과하는 경우 리튬이온의 이동을 방해하여 전지의 출력특성을 저하시킬 수 있으며 100nm 미만인 경우에는 양극을 보호하는 기능을 충분히 할 수 없으며, 제작 공정이 복잡해진다. The lithium ion conductive layer of the present invention can be produced by coating a lithium ion conductor material dispersed in a solvent (for example, NMP) on a cathode active material layer and drying. The lithium ion conductor material may be, for example, an oxide or a phosphorus oxide. The thickness of the lithium ion conductive layer is preferably 100 nm or more and 1 m or less. When the thickness exceeds 1 탆, the lithium ion is prevented from moving and the output characteristics of the battery may be deteriorated. When the thickness is less than 100 nm, the function of protecting the positive electrode can not be sufficiently performed, and the manufacturing process becomes complicated.
본 발명은 본 발명의 양극, 음극 및 전해질을 포함하는 리튬이온 이차전지를 제공한다. The present invention provides a lithium ion secondary battery comprising a positive electrode, a negative electrode and an electrolyte according to the present invention.
상기 리튬이온 이차전지는 당해 기술 분야에서 널리 알려져 있는 통상적인 방법에 의해서, 양극과 음극 사이에 다공성 분리막을 넣고 전해질을 투입하여 제조할 수 있다. The lithium ion secondary battery can be manufactured by putting a porous separator between an anode and a cathode and injecting an electrolyte by a conventional method well known in the art.
본 발명의 리튬이온 이차전지에서는 음극활물질로서 천연 흑연, 인조 흑연, 탄소섬유, 코크스, 카본블랙, 카본나노튜브, 플러렌, 활성탄, 리튬 금속이나 리튬 합금 등 당해 기술분야에서 통상적으로 사용되는 것을 사용할 수 있다. 음극 집전체로는 스테인레스강, 니켈, 구리, 티탄, 또는 이들의 합금 등을 사용할 수 있다.In the lithium ion secondary battery of the present invention, those commonly used in the related art such as natural graphite, artificial graphite, carbon fiber, coke, carbon black, carbon nanotube, fullerene, activated carbon, lithium metal or lithium alloy can be used as the negative electrode active material have. As the negative electrode current collector, stainless steel, nickel, copper, titanium, an alloy thereof, or the like can be used.
상기 전해질은 비수성 유기용매에 리튬염이 용해된 유기 전해질을 사용할 수 있다. 비수성 유기용매는 전지의 전기화학적인 반응에 관여하는 이온들이 이동할 수 있는 매개질 역할을 한다. 상기 비수성 유기용매로는 에틸렌 카보네이트, 프로필렌 카보네이트, 디메틸 카보네이트, 디에틸 카보네이트, 메틸프로필 카보네이트, 에틸프로필 카보네이트, 부틸렌 카보네이트, 아세토니트릴 등이 있으며, 이들을 단독으로 또는 조합하여 사용할 수 있다. 상기 리튬염은 리튬이온의 공급원으로 작용하며 리튬이온 이차전지 전해질에 통상적으로 사용되는 것을 사용할 수 있다. The electrolyte may be an organic electrolyte in which a lithium salt is dissolved in a non-aqueous organic solvent. Non-aqueous organic solvents serve as mediators through which ions involved in the electrochemical reactions of the cell can migrate. Examples of the non-aqueous organic solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, and acetonitrile. These solvents may be used alone or in combination. The lithium salt acts as a source of lithium ions and can be used as a lithium ion secondary battery electrolyte.
본 발명에 따른 리튬이온 이차전지는 양극과 음극 사이에 존재하여 두 전극간 단락을 방지하는 역할을 하는 분리막을 더 포함할 수 있다. 분리막으로서는 폴리올레핀, 폴리프로필렌, 폴리에틸렌 등의 고분자막, 미세다공성 필름, 직포 및 부직포와 같은 통상적으로 사용되는 것을 사용할 수 있다.The lithium ion secondary battery according to the present invention may further include a separator between the positive electrode and the negative electrode to prevent a short circuit between the two electrodes. As the separation membrane, conventionally used materials such as a polymer membrane such as polyolefin, polypropylene, and polyethylene, a microporous film, a woven fabric and a nonwoven fabric may be used.
이하 본 발명을 실시예에 의해 더욱 상세히 설명하지만 본 발명이 이들 실시예에 의해 한정되는 것은 아니다.Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by these Examples.
실시예Example
[실시예 1] Example 1
NiSO4 : CoSO4 : MnSO4 = 2 : 2 : 6의 몰비 조성으로 용액을 제조한 후 암모니아수 0.5M을 추가하고, NaOH 용액을 혼합하여 pH 10.8에서 전이금속 전구체를 제조하였다. 상기 전이금속 전구체에 리튬과 전이금속의 당량비가 1.2:0.8이 되도록 탄산리튬을 균일하게 혼합한 후 열처리를 통해 리튬금속산화물을 얻었다. 상기 열처리는 950 ℃의 온도에서 20시간 동안 진행하였다. NiSO 4 : CoSO 4 : MnSO 4 = 2: 2: 6 molar ratio, 0.5M ammonia water was added, and NaOH solution was mixed to prepare a transition metal precursor at pH 10.8. Lithium carbonate was uniformly mixed with the transition metal precursor so that the equivalence ratio of lithium to transition metal was 1.2: 0.8, followed by heat treatment to obtain a lithium metal oxide. The heat treatment was carried out at a temperature of 950 캜 for 20 hours.
상기 합성한 양극활물질과 Denka Black 도전재, PVDF 바인더를 94:3:3의 비율로 혼합하여 Al 호일 위에 코팅하여 양극활물질층을 형성하였다. 위와 같이 형성된 양극활물질층 상에 Li1 .3Ti1 .7Al0 .3(PO4)3를 NMP 용액에 분산시킨 후 얇게 코팅해 건조시켜 리튬이온 전도층을 형성하였다. 리튬이온 전도층의 코팅 두께는 1㎛로 제어했다. The synthesized cathode active material, Denka Black conductive material and PVDF binder were mixed at a ratio of 94: 3: 3 and coated on Al foil to form a cathode active material layer. Li 1 .3 Ti 1 .7 Al 0 .3 (PO 4 ) 3 was dispersed in an NMP solution on the cathode active material layer formed as described above, then coated thinly and dried to form a lithium ion conductive layer. The coating thickness of the lithium ion conductive layer was controlled to 1 mu m.
상기 얻어진 양극, 음극으로 리튬 메탈, 분리막은 다공성 PE 재질, 전해질로 1.3M LiPF6 EC/DMC/EC = 5:3:2 용액을 사용하여 코인셀을 제작하였다. 전지 테스트는 충전 4.6 V, 방전 2.5V로 진행하였다.Lithium metal was used as the anode and cathode, porous PE material was used as the separation membrane, 1.3M LiPF 6 EC / DMC / EC = 5: 3: 2 solution was used to prepare a coin cell. The battery test proceeded to charge 4.6 V and discharge 2.5V.
[실시예 2] [Example 2]
상기 실시예 1에서 Li1 .3Ti1 .7Al0 .3(PO4)3 대신 (La,Li)TiO3를 사용한 것을 제외하고 동일한 실험을 수행하였다. The same experiment was carried out except that (La, Li) TiO 3 was used instead of Li 1 .3 Ti 1 .7 Al 0 .3 (PO 4 ) 3 in Example 1 above.
[실시예 3][Example 3]
상기 실시예 1에서 리튬이온 전도층의 두께를 80nm로 한 것을 제외하고 동일한 실험을 수행하였다. The same experiment was performed except that the thickness of the lithium ion conductive layer in Example 1 was 80 nm.
[실시예 4]Example 4
상기 실시예 1에서 리튬이온 전도층의 두께를 1.5㎛으로 한 것을 제외하고 동일한 실험을 수행하였다. The same experiment was performed except that the thickness of the lithium ion conductive layer in Example 1 was set to 1.5 탆.
[비교예 1] Comparative Example 1
상기 실시예 1에서 리튬이온 전도층을 형성하지 않는 것을 제외하고 동일한 실험을 수행하였다. The same experiment was performed except that the lithium ion conductive layer was not formed in Example 1.
[비교예 2] [Comparative Example 2]
상기 실시예 1에서 리튬과 전이금속의 당량비가 1:1이 되도록 한 것을 제외하고 동일한 실험을 수행하였다. The same experiment was performed except that the equivalent ratio of lithium to transition metal was 1: 1 in Example 1 above.
[비교예 3] [Comparative Example 3]
상기 실시예 1에서 리튬이온 전도층을 형성하지 않고 리튬과 전이금속의 당량비가 1:1이 되도록 한 것을 제외하고 동일한 실험을 수행하였다. The same experiment was carried out except that the lithium ion conductive layer was not formed and the equivalent ratio of lithium to the transition metal was 1: 1 in Example 1.
상기 실시예와 비교예에서 제조한 코인셀의 전지 용량 및 용량유지율을 측정하였다. 전지 용량은 코인셀에 대해 0.1C-rate의 충방전을 통해 방전용량을 얻고, 방전용량을 전극 무게로 나누어 무게당 전지 용량을 얻었다. 용량 유지율은 25℃ 조건에서 1C-rate (1시간에 방전시키는 정도의 전류밀도)의 전류밀도로 충전과 방전을 반복한 후 50번째 충방전을 끝냈을 때 용량이 첫번째 용량대비 얼마였는지는 %로 나타낸 값이다. 그 결과를 표 1에 나타낸다.The cell capacity and the capacity retention ratio of the coin cells prepared in the above Examples and Comparative Examples were measured. The battery capacity was obtained by charging and discharging the coin cell at a rate of 0.1 C-rate, and dividing the discharge capacity by the electrode weight to obtain the battery capacity per weight. The capacity retention rate is a value expressed as a percentage (%) as to the capacity after the 50th charging / discharging after repeating charging and discharging at a current density of 1C-rate (current density of discharging at 1 hour) to be. The results are shown in Table 1.
상기 표 1에서 보듯이, 리튬 과량의 양극활물질층 상에 리튬이온 전도층을 구비한 양극을 사용하여 제조된 본 발명의 리튬이온 이차전지는, 리튬 과량의 양극활물질을 포함하여 전지 용량이 높고 리튬이온 전도층을 포함하여 용량유지율이 더 높아 고용량의 전지 수명이 개선된 리튬이온 이차전지를 제조할 수 있다. As shown in Table 1, the lithium ion secondary battery of the present invention, which is manufactured using a positive electrode having a lithium ion conductive layer on a lithium-excessive positive electrode active material layer, comprises a lithium-excessive amount of a positive electrode active material, It is possible to manufacture a lithium ion secondary battery including an ion conductive layer and having a higher capacity retention rate, thereby improving the battery life of a high capacity battery.
Claims (8)
Li1 + xM1 - xO2 (1)
(상기 화학식 (1)에서, x ≥ 0.05이고, M은 Co, Ni, Mn, Al, Zr, Ti, W, Mo, Fe, V, Cr 및 Cu로 이루어진 군에서 선택된 1종 이상이다.)A positive electrode current collector, a positive electrode active material layer laminated on the positive electrode current collector, and a lithium ion conductive layer laminated on the positive electrode active material layer, wherein the positive electrode active material layer comprises a lithium metal oxide represented by the formula (1) Features an anode for lithium ion secondary battery.
Li 1 + x M 1 - x O 2 (1)
Wherein M is at least one selected from the group consisting of Co, Ni, Mn, Al, Zr, Ti, W, Mo, Fe, V, Cr and Cu.
LiaNixCoyMnzO2 (2)
(상기 화학식 (2)에서, a ≥ 1.05, 0 < x < 1, 0 < y < 1 ,0 < z < 1 , a+x+y+z = 2 이다.)The positive electrode for a lithium ion secondary battery according to claim 1, wherein the lithium metal oxide represented by the formula (1) is a lithium metal oxide represented by the formula (2).
Li a Ni x Co y Mn z O 2 (2)
(A? 1.05, 0 <x <1, 0 <y <1, 0 <z <1, a + x + y + z = 2 in the formula (2)
xLiNiaCobMncO2―(1-x)Li2MnO3 (3)
(상기 화학식 (3)에서, 0 < x < 1, 0 < a < 1, 0 < b < 1, 0 < c < 1, a+b+c = 1 이다.)The cathode for a lithium ion secondary battery according to claim 2, wherein the lithium metal oxide represented by the formula (2) is a lithium metal oxide represented by the formula (3).
xLiNi a Co b Mn c O 2 - (1-x) Li 2 MnO 3 (3)
(In the formula (3), 0 <x <1, 0 <a <1, 0 <b <1, 0 <c <1, a + b + c = 1).
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| DE102014216423A1 (en) * | 2014-08-19 | 2016-02-25 | Robert Bosch Gmbh | Electrode for an energy storage and method of manufacture |
| US10454105B2 (en) | 2014-08-19 | 2019-10-22 | Robert Bosch Gmbh | Electrode for an energy accumulator and manufacturing method |
| KR20170113908A (en) * | 2016-03-29 | 2017-10-13 | 비나텍주식회사 | Lithium ion capacitor |
| KR20210067056A (en) | 2019-11-29 | 2021-06-08 | 현대자동차주식회사 | Lithium ion secondary battery, system and method of manufactuing lithium ion secondary battery |
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