JP5809201B2 - Lithium-rich manganese composite oxide cathode active material - Google Patents
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Description
本発明は、良好な電池特性を発現できるリチウム過剰マンガン複合酸化物系正極活物質に関する。 The present invention relates to a lithium-rich manganese composite oxide-based positive electrode active material that can exhibit good battery characteristics.
従来より、電池の性能を高めるべく、正極材料や負極材料として導電性の高い物質が用いられる。近年では、リチウムイオン電池等の次世代電池が益々台頭してきており、かかる電池における正極材料としても種々のものが開発されるなか、例えば非特許文献１に記載されるリチウム過剰マンガン複合酸化物を用いることも検討されつつある。かかるリチウム過剰マンガン複合酸化物を次世代電池の正極材料として採用するには、そのもの自体の導電性が低いため、粒子を微細化することによって良好な電池物性の発現を確保する必要がある。 Conventionally, a highly conductive substance is used as a positive electrode material or a negative electrode material in order to improve battery performance. In recent years, next-generation batteries such as lithium ion batteries have been increasingly developed, and various kinds of positive electrode materials in such batteries have been developed. For example, lithium-excess manganese composite oxides described in Non-Patent Document 1 are used. Use is also being considered. In order to employ such a lithium-rich manganese composite oxide as a positive electrode material for a next-generation battery, it is necessary to ensure good battery physical properties by making the particles finer because the conductivity itself is low.
しかしながら、単にリチウム過剰マンガン複合酸化物の粒子を微細化するのみでは、タップ密度が減少する傾向にあり、所望の電池特性を十分に発現できないおそれがある。 However, simply refining the particles of the lithium-excess manganese composite oxide tends to reduce the tap density, and there is a possibility that desired battery characteristics cannot be sufficiently exhibited.
したがって、本発明の課題は、リチウムイオン電池の正極材料として、優れた電池物性を発現し得るリチウム過剰マンガン複合酸化物系正極活物質を提供することにある。 Therefore, the subject of this invention is providing the lithium excess manganese complex oxide type positive electrode active material which can express the outstanding battery physical property as a positive electrode material of a lithium ion battery.
そこで本発明者らは、種々検討したところ、特定の処理を施すことにより得られるリチウム過剰マンガン複合酸化物系正極活物質であれば、タップ密度が大きく、優れた電池物性を発現できることを見出し、本発明を完成させるに至った。 Therefore, the present inventors have conducted various studies and found that a lithium-rich manganese composite oxide-based positive electrode active material obtained by performing a specific treatment has a large tap density and can exhibit excellent battery properties. The present invention has been completed.
すなわち、本発明は、リチウム過剰マンガン複合酸化物及び導電性炭素を混合した後、さらに圧縮力及びせん断力を付加しながら混合する処理を経ることにより得られるリチウム過剰マンガン複合酸化物系正極活物質を提供するものである。 That is, the present invention relates to a lithium-excess manganese composite oxide-based positive electrode active material obtained by mixing a lithium-excess manganese composite oxide and conductive carbon and then mixing them while adding compressive force and shearing force. Is to provide.
本発明のリチウム過剰マンガン複合酸化物系正極活物質は、リチウム過剰マンガン複合酸化物と導電性炭素とが極めて均一に分散され、かつ空隙が低減された粒子であるため、タップ密度が大きく、リチウムイオン電池の性能向上に大いに寄与することが期待される。 The lithium-rich manganese composite oxide-based positive electrode active material of the present invention is a particle in which the lithium-rich manganese composite oxide and conductive carbon are dispersed extremely uniformly and with reduced voids. It is expected to greatly contribute to improving the performance of ion batteries.
以下、本発明について詳細に説明する。
本発明のリチウム過剰マンガン複合酸化物系正極活物質は、リチウム過剰マンガン複合酸化物及び導電性炭素を混合した後、さらに圧縮力及びせん断力を付加しながら混合する処理を経ることにより得られる。かかる処理を経ることにより、リチウム過剰マンガン複合酸化物と導電性炭素とが均一に分散したまま堅固に凝集して粒子（以下、「複合体粒子」ともいう）を形成することにより、空隙が低減された複合体粒子を得ることができる。また、導電性炭素を変形又は延展させながらリチウム過剰マンガン複合酸化物が呈する粒子（以下、「一次粒子」ともいう）の表面に付着させ、導電性炭素の層を形成させることもできる。圧縮力及びせん断力を付加しながら混合する処理は、周速２５〜４０ｍ／ｓで回転するインペラを備える密閉容器を用いるのが好ましい。かかる容器内にリチウム過剰マンガン複合酸化物及び導電性炭素を投入し、容器を稼動させることにより、圧縮力及びせん断力を付加しながら混合する処理が可能となる。かかるインペラを備える密閉容器内では、インペラの回転によってこれらリチウム過剰マンガン複合酸化物及び導電性炭素が均一に混合されるとともに、インペラと容器内壁との間で圧縮力を付加されながらせん断力も付加されることとなる。インペラの周速は、得られる複合体粒子のタップ密度を高める観点から、好ましくは２５〜４０ｍ／ｓであり、より好ましくは２７〜３５ｍ／ｓである。
Hereinafter, the present invention will be described in detail.
The lithium-rich manganese composite oxide-based positive electrode active material of the present invention can be obtained by mixing a lithium-rich manganese composite oxide and conductive carbon and then mixing them while adding compressive force and shearing force. Through this treatment, the lithium-excess manganese composite oxide and conductive carbon are uniformly agglomerated while being uniformly dispersed to form particles (hereinafter also referred to as “composite particles”), thereby reducing voids. Composite particles can be obtained. Alternatively, a conductive carbon layer can be formed by adhering to the surface of particles (hereinafter also referred to as “primary particles”) exhibited by the lithium-rich manganese composite oxide while deforming or extending the conductive carbon. It is preferable to use an airtight container provided with an impeller that rotates at a peripheral speed of 25 to 40 m / s for the process of mixing while applying a compressive force and a shearing force. By introducing the lithium-excess manganese composite oxide and conductive carbon into such a container and operating the container, it is possible to perform a mixing process while applying compressive force and shearing force. In a closed container equipped with such an impeller, the lithium-rich manganese composite oxide and conductive carbon are uniformly mixed by the rotation of the impeller, and a shearing force is also applied while a compressive force is applied between the impeller and the inner wall of the container. The Rukoto. The peripheral speed of the impeller is preferably 25 to 40 m / s, more preferably 27 to 35 m / s, from the viewpoint of increasing the tap density of the resulting composite particles.
なお、得られる複合体粒子の均一性を高める観点、およびインペラを備える密閉容器内での処理時間を短縮化する観点から、かかる密閉容器内へリチウム過剰マンガン複合酸化物及び導電性炭素を投入する前に、予めこれらを混合してもよい。 In addition, from the viewpoint of improving the uniformity of the obtained composite particles and shortening the processing time in the sealed container equipped with the impeller, the lithium-excess manganese composite oxide and conductive carbon are introduced into the sealed container. These may be mixed in advance.
このような圧縮力及びせん断力を付加しながら混合することのできる密閉容器を備える装置としては、高速せん断ミル、ブレード型混練機等が挙げられ、具体的には、例えば、微粒子複合化装置 ノビルタ（ホソカワミクロン社製）を好適に用いることができる。かかる装置を用いることにより、容易に所定の圧縮力とせん断力を付加しながらの混合処理を行うことができ、このような処理を施すのみで本発明のリチウム過剰マンガン複合酸化物系正極活物質を得ることができる。
上記混合の処理条件としては、処理温度が、好ましくは５〜８０℃、より好ましくは１０〜５０℃であり、処理時間が、好ましくは５〜９０分、より好ましくは１０〜６０分である。処理雰囲気としては、特に限定されないが、不活性ガス雰囲気下、または還元ガス雰囲気下が好ましい。
Examples of the apparatus provided with a closed container that can be mixed while applying such compressive force and shearing force include a high-speed shear mill, a blade-type kneader, and the like. (Manufactured by Hosokawa Micron Corporation) can be preferably used. By using such an apparatus, it is possible to easily perform a mixing process while applying a predetermined compressive force and shearing force, and the lithium-rich manganese composite oxide-based positive electrode active material of the present invention can be obtained only by performing such a process. Can be obtained.
As the processing conditions for the mixing, the processing temperature is preferably 5 to 80 ° C., more preferably 10 to 50 ° C., and the processing time is preferably 5 to 90 minutes, more preferably 10 to 60 minutes. The treatment atmosphere is not particularly limited, but is preferably an inert gas atmosphere or a reducing gas atmosphere.
上記密閉容器内に投入するリチウム過剰マンガン複合酸化物と導電性炭素との質量比は、得られる電池物性を高める観点から、好ましくは９７：３〜８５：１５であり、より好ましくは９５：５〜８８：１２であり、さらに好ましくは９３：７〜９０：１０である。 The mass ratio between the lithium-rich manganese composite oxide and the conductive carbon charged into the sealed container is preferably 97: 3 to 85:15, more preferably 95: 5, from the viewpoint of improving the properties of the obtained battery. It is -88: 12, More preferably, it is 93: 7-90: 10.
なお、電池物性をより高める観点から、得られた複合体粒子を焼成してもよい。焼成条件は、不活性ガス雰囲気下又は還元条件下に４００℃以上、好ましくは４００〜８００℃で１０分〜３時間、好ましくは０．５〜１．５時間行うのが好ましい。 In addition, you may bake the obtained composite particle from a viewpoint of improving battery physical property more. The firing conditions are 400 ° C. or higher, preferably 400 to 800 ° C. for 10 minutes to 3 hours, preferably 0.5 to 1.5 hours under an inert gas atmosphere or reducing conditions.
リチウム過剰マンガン複合酸化物は、過剰のリチウムとマンガンを含む複合酸化物であり、遷移金属元素として、Ｍｎのほか、さらにＮｉ、Ｍｎ及びＣｏから選ばれる１種又は２種以上のものを含む。なかでも、遷移金属元素としてＭｎ、Ｃｏ及びＮｉを含むリチウム過剰マンガン複合酸化物が好ましく、具体的には、下記式で表される。
(１−ｚ)Ｌｉ2ＭｎＯ3・ｚＬｉＭＯ2（ｚは、０．２５≦ｚ≦０．７５を満たし、Ｍは、Ｎｉ、Ｍｎ及びＣｏから選ばれる１種又は２種以上の遷移金属元素を示す。）
なかでもａは、電池物性をより高める観点から、０．２５≦ａ≦０．５であるのが好ましい。かかるリチウム過剰マンガン複合酸化物としては、より具体的には、例えばＬｉ［Ｌｉ0.2Ｍｎ0.56Ｎｉ0.16Ｃｏ0.08］Ｏ2で表されるものが挙げられる。
The lithium-excess manganese composite oxide is a composite oxide containing excess lithium and manganese, and includes one or more selected from Ni, Mn, and Co in addition to Mn as a transition metal element. Especially, the lithium excess manganese complex oxide containing Mn, Co, and Ni as a transition metal element is preferable, and is specifically represented by the following formula.
(1-z) Li 2 MnO 3 .zLiMO 2 (z satisfies 0.25 ≦ z ≦ 0.75, and M represents one or more transition metal elements selected from Ni, Mn and Co) Show.)
Among these, a is preferably 0.25 ≦ a ≦ 0.5 from the viewpoint of further improving battery physical properties. More specifically, examples of the lithium-excess manganese composite oxide include those represented by Li [Li 0.2 Mn 0.56 Ni 0.16 Co 0.08 ] O 2 .
リチウム過剰マンガン複合酸化物は、リチウム化合物及びマンガン化合物のほか、必要に応じて遷移金属源を原料として用い、混合、粉砕、焼成することにより得られる一次粒子である。 The lithium-excess manganese composite oxide is primary particles obtained by mixing, pulverizing, and firing using a transition metal source as a raw material as necessary in addition to a lithium compound and a manganese compound.
用い得るリチウム化合物としては、リチウム酸化物又はリチウム水酸化物が挙げられる。具体的には、例えば、水酸化リチウム、炭酸リチウム、硝酸リチウム、酸化リチウム、シュウ酸リチウム、酢酸リチウム等が挙げられる。これらは１種単独で用いてもよく、２種以上組み合わせて用いてもよい。なかでも、電池物性を高める観点から、水酸化リチウムが好ましい。 Examples of the lithium compound that can be used include lithium oxide and lithium hydroxide. Specific examples include lithium hydroxide, lithium carbonate, lithium nitrate, lithium oxide, lithium oxalate, and lithium acetate. These may be used alone or in combination of two or more. Among these, lithium hydroxide is preferable from the viewpoint of improving battery physical properties.
用い得るマンガン化合物やその他の遷移金属源としては、硫酸塩、塩化物、酢酸塩、シュウ酸塩等が挙げられる。なかでも、電池物性を高める観点から、硫酸塩が好ましい。これらは１種単独で用いてもよく、２種以上組み合わせて用いてもよいが、マンガン化合物を含む２種以上を用いるのが好ましく、３種組み合わせて用いるのがより好ましい。 Examples of manganese compounds and other transition metal sources that can be used include sulfates, chlorides, acetates, and oxalates. Among these, sulfate is preferable from the viewpoint of improving battery physical properties. These may be used individually by 1 type, or may be used in combination of 2 or more types, but it is preferable to use 2 or more types including a manganese compound, and it is more preferable to use 3 types in combination.
これらリチウム化合物及びマンガン化合物のほか、必要に応じて遷移金属源を混合、粉砕、焼成してリチウム過剰マンガン複合酸化物の一次粒子を得る方法としては、例えばＪｏｕｒｎａｌ ｏｆ Ｐｏｗｅｒ Ｓｏｕｒｃｅ １９６（（２０１１），ｐ４８２１−４８２５）に記載の方法を用いることができる。 In addition to these lithium compound and manganese compound, a transition metal source may be mixed, pulverized, and fired as necessary to obtain primary particles of lithium-rich manganese composite oxide. For example, Journal of Power Source 196 ((2011), p4821-4825) can be used.
具体的には、例えば、まずリチウム化合物及びマンガン化合物のほか、必要に応じて遷移金属源に水を加えてろ過した後、洗浄・乾燥する。次いで、さらにリチウム化合物及び水を添加して混合し、粉砕・焼成する。
焼成条件は、例えば焼成温度８００〜１０００℃、焼成時間１２〜４８時間である。また、焼成する際、窒素やアルゴン等の不活性ガス雰囲気下としてもよく、酸素雰囲気下、或いは大気雰囲気下としてもよい。これより、原料となるリチウム過剰マンガン複合酸化物を得ることができる。
Specifically, for example, in addition to a lithium compound and a manganese compound, water is added to a transition metal source as necessary, followed by filtration, followed by washing and drying. Next, a lithium compound and water are further added, mixed, pulverized and fired.
The firing conditions are, for example, a firing temperature of 800 to 1000 ° C. and a firing time of 12 to 48 hours. Further, when firing, an inert gas atmosphere such as nitrogen or argon may be used, or an oxygen atmosphere or an air atmosphere may be used. From this, the lithium excess manganese complex oxide used as a raw material can be obtained.
リチウム過剰マンガン複合酸化物が有する平均粒径Ｘは、複合体粒子としての均一性を高めて得られる電池物性の向上を図る観点から、好ましくは２０〜４００ｎｍであり、より好ましくは２０〜３５０ｎｍであり、さらに好ましくは２０〜２５０ｎｍである。なお、かかる平均粒径Ｘは、試料を溶媒によって均一分散させ、動的光散乱法の粒度分析計（ナノトラックUPA-EX150、日機装株式会社製）により測定される値を意味する。 The average particle size X of the lithium-excess manganese composite oxide is preferably 20 to 400 nm, more preferably 20 to 350 nm, from the viewpoint of improving battery physical properties obtained by increasing the uniformity as composite particles. And more preferably 20 to 250 nm. The average particle diameter X means a value measured by a dynamic light scattering particle size analyzer (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.) after uniformly dispersing the sample with a solvent.
上記導電性炭素としては、カーボンブラックが好ましく、具体的には、例えば、アセチレンブラック、ケッチェンブラック、チャンネルブラック、ファーネスブラック、ランプブラック、サーマルブラック等が挙げられる。なかでも、良好な導電性を付与する観点から、アセチレンブラック、ケッチェンブラックが好ましい。また、これら導電性炭素の形状としては、リチウム過剰マンガン複合酸化物の一次粒子の少なくとも一部の表面を導電性炭素からなる層で被覆させて得られる電池物性をより高める観点から、中空形状を呈するもの、又は空隙を含む形状を呈するものであるのが好ましい。 Carbon black is preferable as the conductive carbon, and specific examples include acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black. Of these, acetylene black and ketjen black are preferred from the viewpoint of imparting good conductivity. In addition, as the shape of these conductive carbons, from the viewpoint of further improving the physical properties of the battery obtained by coating at least a part of the surface of the primary particles of the lithium-rich manganese composite oxide with a layer made of conductive carbon, a hollow shape is used. It is preferable that it exhibits or a shape including voids.
また、本発明で用いる導電性炭素は、リチウム過剰マンガン複合酸化物の一次粒子が有する平均粒径Ｘ以下の平均粒径Ｙを有するのが好ましい。導電性炭素がこのような平均粒径を有することにより、かかる導電性炭素がリチウム過剰マンガン複合酸化物の粒子と粒子の間隙に効率的に配置されて、空隙が低減された均一性の高い複合体粒子を得ることができる。 Moreover, it is preferable that the conductive carbon used by this invention has the average particle diameter Y below the average particle diameter X which the primary particle of lithium excess manganese complex oxide has. Since the conductive carbon has such an average particle size, the conductive carbon is efficiently arranged in the gap between the particles of the lithium-rich manganese composite oxide, and the highly uniform composite with reduced voids. Body particles can be obtained.
リチウム過剰マンガン複合酸化物が有する平均粒径Ｘと導電性炭素が有する平均粒径Ｙとの比（Ｘ／Ｙ）は、より効率的にリチウム過剰マンガン複合酸化物の粒子と粒子の間隙に配置される観点、及び得られる電池物性の向上を図る観点から、好ましくは１〜２０であり、より好ましくは１．５〜１０である。また、導電性炭素が有する平均粒径Ｙは、同様の観点から、好ましくは１０〜１００ｎｍであり、より好ましくは１０〜５０ｎｍである。なお、かかる平均粒径Ｙは、上記リチウム過剰マンガン複合酸化物の平均粒径Ｘと同様の方法により測定される値を意味する。 The ratio (X / Y) of the average particle diameter X of the lithium-excess manganese composite oxide to the average particle diameter Y of the conductive carbon is more efficiently arranged in the gap between the particles of the lithium-excess manganese composite oxide. From the viewpoint of improving the physical properties of the obtained battery and the obtained battery, it is preferably 1 to 20, and more preferably 1.5 to 10. Moreover, the average particle diameter Y which electroconductive carbon has becomes like this. Preferably it is 10-100 nm, More preferably, it is 10-50 nm. In addition, this average particle diameter Y means the value measured by the method similar to the average particle diameter X of the said lithium excess manganese complex oxide.
本発明のリチウム過剰マンガン複合酸化物系正極活物質のタップ密度は、好ましくは０．８〜２．５ｇ／ｃｍ3であり、より好ましくは１．０〜２．５ｇ／ｃｍ3であり、さらに好ましくは１．２〜２．５ｇ／ｃｍ3である。したがって、本発明のリチウム過剰マンガン複合酸化物系正極活物質は、極めて空隙が低減されてなり、これらリチウム過剰マンガン複合酸化物と導電性炭素とが非常に均一に分散してなる粒子であるため、これを正極材料として用いれば、得られる電池物性の向上を容易に図ることが可能となる。なお、リチウム過剰マンガン複合酸化物系正極活物質のタップ密度とは、重量既知の粉体試料ｍ（g）を入れた測定用容器を機械的にタップし、体積変化が認められなくなった時の粉体体積Ｖ（ｃｍ3）を読み取り、式 ｍ/Ｖ を用いて計算された値を平均したものを意味する。 The tap density of the lithium-rich manganese composite oxide positive electrode active material of the present invention is preferably 0.8 to 2.5 g / cm 3 , more preferably 1.0 to 2.5 g / cm 3 , Preferably it is 1.2-2.5 g / cm < 3 >. Accordingly, the lithium-excess manganese composite oxide-based positive electrode active material of the present invention is a particle in which the voids are extremely reduced and these lithium-excess manganese composite oxide and conductive carbon are very uniformly dispersed. If this is used as the positive electrode material, it is possible to easily improve the physical properties of the obtained battery. Note that the tap density of the lithium-rich manganese composite oxide-based positive electrode active material means that when a measuring container containing a powder sample m (g) with a known weight is mechanically tapped and no volume change is observed. It means a value obtained by reading the powder volume V (cm 3 ) and averaging the values calculated using the formula m / V.
また、本発明のリチウム過剰マンガン複合酸化物系正極活物質におけるリチウム過剰マンガン複合酸化物及び導電性炭素は、これらの均一性及び分散性を高める観点、及び得られる電池物性をより高める観点から、リチウム過剰マンガン複合酸化物の一次粒子の少なくとも一部の表面を、導電性炭素からなる層が被覆してなるのが好ましい。導電性炭素からなる層は、一次粒子の少なくとも一部の表面を被覆していてもよく、一次粒子のほぼ全表面を被覆していてもよい。これにより、リチウム過剰マンガン複合酸化物の一次粒子及び導電性炭素の各々が凝集するのを抑制することができ、導電性炭素がより緻密かつ均一に分散した複合体粒子であるリチウム過剰マンガン複合酸化物系正極活物質が得られ、導電性をより高めることが可能となる。 In addition, the lithium-excess manganese composite oxide and conductive carbon in the lithium-excess manganese composite oxide-based positive electrode active material of the present invention are from the viewpoint of increasing the uniformity and dispersibility thereof, and from the viewpoint of further improving the physical properties of the obtained battery. It is preferable that the surface of at least a part of the primary particles of the lithium-rich manganese composite oxide is covered with a layer made of conductive carbon. The layer made of conductive carbon may cover at least a part of the surface of the primary particles, or may cover almost the entire surface of the primary particles. Thereby, primary particles of lithium-rich manganese composite oxide and conductive carbon can be prevented from aggregating, and lithium-rich manganese composite oxide, which is a composite particle in which conductive carbon is more densely and uniformly dispersed. A physical positive electrode active material is obtained, and the conductivity can be further increased.
導電性炭素からなる層の厚みは、好ましくは０．１〜５．０ｎｍであり、より好ましくは０．５〜３．０ｎｍである。 The thickness of the layer made of conductive carbon is preferably 0.1 to 5.0 nm, more preferably 0.5 to 3.0 nm.
また、本発明のリチウム過剰マンガン複合酸化物系正極活物質が有する平均粒径Ｚは、得られるリチウムイオン電池において優れた電池物性を保持しつつ軽量化を図る観点から、５〜５０μｍであって、好ましくは５〜３０μｍであり、より好ましくは５〜２０μｍである。このように、本発明のリチウム過剰マンガン複合酸化物系正極活物質は、均一に分散したリチウム過剰マンガン複合酸化物と導電性炭素とを含有しつつも微細な複合体粒子であるため、これを用いて正極を形成することにより、優れた電池物性を有するリチウムイオン電池を得ることができる。なお、かかる平均粒径Ｚは、上記平均粒径Ｘ及びＹと同様の方法により測定される値を意味する。 The average particle size Z of the lithium-rich manganese composite oxide-based positive electrode active material of the present invention is 5 to 50 μm from the viewpoint of reducing the weight while maintaining excellent battery properties in the obtained lithium ion battery. The thickness is preferably 5 to 30 μm, more preferably 5 to 20 μm. As described above, the lithium-excess manganese composite oxide-based positive electrode active material of the present invention is a fine composite particle containing uniformly dispersed lithium-excess manganese composite oxide and conductive carbon. By using this to form a positive electrode, a lithium ion battery having excellent battery properties can be obtained. In addition, this average particle diameter Z means the value measured by the method similar to the said average particle diameter X and Y.
このようにして得られた本発明のリチウム過剰マンガン複合酸化物系正極活物質を用いてリチウムイオン電池を製造する方法は特に限定されず、公知の方法をいずれも使用できる。例えば、かかるリチウム過剰マンガン複合酸化物系正極活物質を結着剤や溶剤等の添加剤とともに混合して塗工液を得る。この際、必要に応じて、さらに導電助剤を添加して混合してもよい。かかる結着剤としては、特に限定されず、公知の剤をいずれも使用できる。具体的には、ポリテトラフルオロエチレン、ポリビニリデンフルオライド、ポリビニルクロライド、エチレンプロピレンジエンポリマー等が挙げられる。また、かかる導電助剤としては、特に限定されず、公知の剤をいずれも使用できる。具体的には、アセチレンブラック、ケッチェンブラック、天然黒鉛、人工黒鉛、繊維状炭素等が挙げられる。次いで、かかる塗工液をアルミ箔等の正極集電体上に塗布し、乾燥させて正極とする。 The method for producing a lithium ion battery using the lithium-rich manganese composite oxide-based positive electrode active material of the present invention thus obtained is not particularly limited, and any known method can be used. For example, the lithium-rich manganese composite oxide-based positive electrode active material is mixed with additives such as a binder and a solvent to obtain a coating solution. At this time, if necessary, a conductive additive may be further added and mixed. The binder is not particularly limited, and any known agent can be used. Specific examples include polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, and ethylene propylene diene polymer. Moreover, it does not specifically limit as this conductive support agent, Any well-known agent can be used. Specific examples include acetylene black, ketjen black, natural graphite, artificial graphite, and fibrous carbon. Next, such a coating solution is applied onto a positive electrode current collector such as an aluminum foil and dried to obtain a positive electrode.
本発明のリチウム過剰マンガン複合酸化物系正極活物質は、リチウムイオン電池の正極として非常に優れた放電容量を発揮する点で有用である。かかる正極を適用できるリチウム電池としては、正極と負極と電解液とセパレータを必須構成とするものであれば特に限定されない。 The lithium-rich manganese composite oxide positive electrode active material of the present invention is useful in that it exhibits a very excellent discharge capacity as a positive electrode of a lithium ion battery. A lithium battery to which such a positive electrode can be applied is not particularly limited as long as it has a positive electrode, a negative electrode, an electrolytic solution, and a separator as essential components.
ここで、負極については、リチウムイオンを充電時には吸蔵し、かつ放電時には放出することができれば、その材料構成で特に限定されるものではなく、公知の材料構成のものを用いることができる。たとえば、リチウム金属、グラファイト又は非晶質炭素等の炭素材料等である。そしてリチウムを電気化学的に吸蔵・放出し得るインターカレート材料で形成された電極、特に炭素材料を用いることが好ましい。 Here, as long as lithium ions can be occluded at the time of charging and released at the time of discharging, the material structure is not particularly limited, and a known material structure can be used. For example, a carbon material such as lithium metal, graphite, or amorphous carbon. It is preferable to use an electrode formed of an intercalating material capable of electrochemically inserting and extracting lithium, particularly a carbon material.
電解液は、有機溶媒に支持塩を溶解させたものである。有機溶媒は、通常リチウムイオン二次電池の電解液の用いられる有機溶媒であれば特に限定されるものではなく、例えば、カーボネート類、ハロゲン化炭化水素、エーテル類、ケトン類、ニトリル類、ラクトン類、オキソラン化合物等を用いることができる。 The electrolytic solution is obtained by dissolving a supporting salt in an organic solvent. The organic solvent is not particularly limited as long as it is an organic solvent that is usually used for an electrolyte solution of a lithium ion secondary battery. For example, carbonates, halogenated hydrocarbons, ethers, ketones, nitriles, lactones An oxolane compound or the like can be used.
支持塩は、その種類が特に限定されるものではないが、ＬｉＰＦ6、ＬｉＢＦ4、ＬｉＣｌＯ4及びＬｉＡｓＦ6から選ばれる無機塩、該無機塩の誘導体、ＬｉＳＯ3ＣＦ3、ＬｉＣ（ＳＯ3ＣＦ3）2及びＬｉＮ（ＳＯ3ＣＦ3）2、ＬｉＮ（ＳＯ2Ｃ2Ｆ5）2及びＬｉＮ（ＳＯ2ＣＦ3）（ＳＯ2Ｃ4Ｆ9）から選ばれる有機塩、並びに該有機塩の誘導体の少なくとも１種であることが好ましい。 The type of the supporting salt is not particularly limited, but an inorganic salt selected from LiPF 6 , LiBF 4 , LiClO 4 and LiAsF 6 , a derivative of the inorganic salt, LiSO 3 CF 3 , LiC (SO 3 CF 3 ) 2 and LiN (SO 3 CF 3 ) 2 , LiN (SO 2 C 2 F 5 ) 2 and LiN (SO 2 CF 3 ) (SO 2 C 4 F 9 ), and organic salt derivatives It is preferable that it is at least 1 sort of.
セパレータは、正極及び負極を電気的に絶縁し、電解液を保持する役割を果たすものである。たとえば、多孔性合成樹脂膜、特にポリオレフィン系高分子（ポリエチレン、ポリプロピレン）の多孔膜を用いればよい。 The separator plays a role of electrically insulating the positive electrode and the negative electrode and holding the electrolytic solution. For example, a porous synthetic resin film, particularly a polyolefin polymer (polyethylene, polypropylene) porous film may be used.
以下、本発明について、実施例に基づき具体的に説明するが、本発明はこれら実施例に限定されるものではない。 EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.
［製造例１］
水酸化リチウム、硫酸マンガン、硫酸ニッケル及び硫酸コバルトを用い、Ｊｏｕｒｎａｌ ｏｆ Ｐｏｗｅｒ Ｓｏｕｒｃｅ ２２１（（２０１３），ｐ１２２−１２７）に記載の方法にしたがって、混合・粉砕、焼成処理（焼成温度９００℃、焼成時間２４時間）を行い、リチウム過剰マンガン複合酸化物の一次粒子（平均粒径２００ｎｍ）を得た。
[Production Example 1]
Lithium hydroxide, manganese sulfate, nickel sulfate and cobalt sulfate were used, mixed and pulverized, and calcination (calcination temperature 900 ° C., calcination time) according to the method described in Journal of Power Source 221 ((2013), p122-127). 24 hours) to obtain primary particles (average particle size 200 nm) of the lithium-excess manganese composite oxide.
［実施例１］
製造例１で得られたリチウム過剰マンガン複合酸化物の一次粒子９３ｇとケッチェンブラック（ライオン社製、平均粒径３０ｎｍ）７ｇとを予め混合して混合物を得て、得られた混合物を微粒子複合化装置 ノビルタ（ホソカワミクロン社製）に投入し、２５〜３５℃で３０分間混合して、複合体粒子Ａを得た。得られた複合体粒子Ａの平均粒径は２０μｍであり、タップ密度は１．４９ｇ／ｃｍ3であった。
得られた複合体粒子ＡのＳＥＭ像を図１に示す。
[Example 1]
93 g of primary particles of the lithium-rich manganese composite oxide obtained in Production Example 1 and 7 g of Ketjen Black (manufactured by Lion Corporation, average particle size 30 nm) were mixed in advance to obtain a mixture, and the resulting mixture was fine-particle composite Chemical device Nobilta (manufactured by Hosokawa Micron) was mixed at 25 to 35 ° C. for 30 minutes to obtain composite particles A. The obtained composite particles A had an average particle diameter of 20 μm and a tap density of 1.49 g / cm 3 .
The SEM image of the obtained composite particle A is shown in FIG.
［比較例１］
製造例１で得られたリチウム過剰マンガン複合酸化物の一次粒子２．６３ｇ、ケッチェンブラック（ライオン社製、平均粒径３０ｎｍ）０．０９ｇ及び分散安定化剤（カルボキシメチルセルロース、ダイセルファインケム社製）を加えた水３０ｇを、遊星ボールミル（遊星型ボールミルＰ−５、フリッチュ社製）のジルコニア製ポットにジルコニア製ボールとともに投入し、２５〜７０℃で２４０分間混合して乾燥し、複合体粒子Ｂを得た。得られた複合体粒子Ｂの平均粒径は、２μｍであり、タップ密度は０．９１ｇ／ｃｍ3であった。
[Comparative Example 1]
2.63 g primary particles of the lithium-rich manganese composite oxide obtained in Production Example 1, 0.09 g of Ketjen Black (Lion Corporation, average particle size 30 nm) and a dispersion stabilizer (Carboxymethylcellulose, Daicel Finechem Co.) 30 g of water added with zirconia is put together with zirconia balls in a zirconia pot of a planetary ball mill (planet type ball mill P-5, manufactured by Fritsch), mixed at 25 to 70 ° C. for 240 minutes, and dried. Got. The obtained composite particles B had an average particle size of 2 μm and a tap density of 0.91 g / cm 3 .
［試験例１］
実施例１及び比較例１で得られた複合体粒子を用い、リチウムイオン二次電池の正極を作製した。実施例１及び比較例１で得られた複合体、ケッチェンブラック（導電剤）、ポリフッ化ビニリデン（粘結剤）を重量比８０：１０：１０の配合割合で混合し、これにＮ−メチル−２−ピロリドンを加えて充分混練し、正極スラリーを調製した。正極スラリーを厚さ２０μｍのアルミニウム箔からなる集電体に塗工機を用いて塗布し、８０℃で１２時間の真空乾燥を行った。その後、φ１４ｍｍの円盤状に打ち抜いてハンドプレスを用いて１６ＭＰａで２分間プレスし、正極とした。
[Test Example 1]
Using the composite particles obtained in Example 1 and Comparative Example 1, a positive electrode of a lithium ion secondary battery was produced. The composite obtained in Example 1 and Comparative Example 1, ketjen black (conductive agent), and polyvinylidene fluoride (binding agent) were mixed at a weight ratio of 80:10:10, and this was mixed with N-methyl. -2-Pyrrolidone was added and sufficiently kneaded to prepare a positive electrode slurry. The positive electrode slurry was applied to a current collector made of an aluminum foil having a thickness of 20 μm using a coating machine, and vacuum dried at 80 ° C. for 12 hours. Thereafter, it was punched into a disk shape of φ14 mm and pressed at 16 MPa for 2 minutes using a hand press to obtain a positive electrode.
次いで、上記の正極を用いてコイン型リチウムイオン二次電池を構築した。負極には、φ１５ｍｍに打ち抜いたリチウム箔を用いた。電解液には、エチレンカーボネート及びエチルメチルカーボネートを体積比１：１の割合で混合した混合溶媒に、ＬＩＰＦ6を１ｍｏｌ／ｌの濃度で溶解したものを用いた。セパレータには、ポリプロピレンなどの高分子多孔フィルムなど、公知のものを用いた。これらの電池部品を露点が−５０℃以下の雰囲気で常法により組み込み収容し、コイン型リチウム二次電池（ＣＲ−２０３２）を製造した。 Next, a coin-type lithium ion secondary battery was constructed using the positive electrode. A lithium foil punched to φ15 mm was used for the negative electrode. As the electrolytic solution, a solution obtained by dissolving LIPF 6 at a concentration of 1 mol / l in a mixed solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 1: 1 was used. As the separator, a known one such as a polymer porous film such as polypropylene was used. These battery components were assembled and housed in a conventional manner in an atmosphere with a dew point of −50 ° C. or lower to produce a coin-type lithium secondary battery (CR-2032).
製造したリチウムイオン二次電池を用いて定電流密度での充放電試験を行い、充放電容量を測定した。このときの充電条件は電流０．１ＣＡ（２０ｍＡ／ｇ）、電圧４．８Ｖの定電流定電圧充電とし、放電条件は電流０．１ＣＡ、終止電圧２．５Ｖの定電流放電とした。温度は全て３０℃とした。 A charge / discharge test at a constant current density was performed using the manufactured lithium ion secondary battery, and a charge / discharge capacity was measured. The charging conditions at this time were constant current and constant voltage charging with a current of 0.1 CA (20 mA / g) and a voltage of 4.8 V, and the discharging conditions were constant current discharging with a current of 0.1 CA and a final voltage of 2.5 V. All temperatures were 30 ° C.
上記結果より、実施例１で得られた複合体粒子Ａは、比較例１で得られた複合体粒子Ｂに比して、極めて均一性が高い上に空隙が低減されてなるため、タップ密度が非常に大きく、これを用いた二次電池において優れた電池物性を示すことがわかる。一方、比較例１で得られた複合体粒子Ｂは、微細な粒子ではあるものの、十分な量の導電性炭素を含有していない上に空隙が多いためにタップ密度が小さくなり、電池物性の低下を招いたものと考えられる。 From the above results, the composite particle A obtained in Example 1 is extremely uniform and has reduced voids as compared to the composite particle B obtained in Comparative Example 1. Therefore, the tap density It can be seen that the secondary battery using the same exhibits excellent battery properties. On the other hand, although the composite particle B obtained in Comparative Example 1 is a fine particle, it does not contain a sufficient amount of conductive carbon and has many voids, so that the tap density is reduced, and the battery physical properties are reduced. This is thought to have caused a decline.
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| KR101452029B1 (en) * | 2011-09-20 | 2014-10-23 | 주식회사 엘지화학 | Cathode active material with high capacity and lithium secondary battery comprising thereof |
| US20140238775A1 (en) * | 2011-09-21 | 2014-08-28 | Nitto Denko Corporation | Sound insulating material and sealing material |
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