JP2003173777A - Combining method and its combining material of positive electrode active material for nonaqueous lithium secondary battery and conductive subsidiary material, and positive electrode and nonaqueous lithium secondary battery using the same - Google Patents
Combining method and its combining material of positive electrode active material for nonaqueous lithium secondary battery and conductive subsidiary material, and positive electrode and nonaqueous lithium secondary battery using the sameInfo
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- JP2003173777A JP2003173777A JP2001373747A JP2001373747A JP2003173777A JP 2003173777 A JP2003173777 A JP 2003173777A JP 2001373747 A JP2001373747 A JP 2001373747A JP 2001373747 A JP2001373747 A JP 2001373747A JP 2003173777 A JP2003173777 A JP 2003173777A
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- positive electrode
- active material
- electrode active
- secondary battery
- lithium secondary
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、非水系リチウム二
次電池の正極活物質と導電助材との複合方法およびその
複合材料、正極に関し、正極活物質と導電助材の分散性
および接触抵抗の改善と二次電池の低抵抗化と高容量化
に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite method of a positive electrode active material and a conductive auxiliary material for a non-aqueous lithium secondary battery, a composite material thereof, and a positive electrode, and the dispersibility and contact resistance of the positive electrode active material and the conductive auxiliary material. And the reduction of resistance and the increase in capacity of the secondary battery.
【０００２】[0002]
【従来の技術】リチウム二次電池は、ニッケルカドミウ
ム電池、ニッケル水素電池に比べて、エネルギー密度が
高く、携帯端末の分野で急速に普及している。また、電
気自動車や電力貯蔵の分野でも期待されている。リチウ
ム二次電池は正極、負極およびセパレータを容器内に配
置し、有機溶媒による非水電解液を充填して構成されて
いる。正極活物質はアルミニウム箔等の集電体に正極活
物質を塗布し加圧成形したものである。正極活物質とし
てはコバルト酸リチウム(LiCoO2)、ニッケル酸リチウム
(LiNiO2)、マンガン酸リチウム(LiMnO2)、スピネル型マ
ンガン酸リチウム(LiMn2O4)などに代表されるようなリ
チウムと遷移金属の複合酸化物（以下、リチウム遷移金
属酸化物と言う。）の粉体が主として用いられている。
これら正極活物質の合成は一般にリチウム化合物(Li2CO
3 ，LiOH，LiCl等)粉末と遷移金属化合物(MnCO3, MnO2,
Mn3O4, Mn2O3, Co3O4，NiO等)粉末を混合し、焼成して
リチウム遷移金属酸化物とする方法が広く採用されてい
る。正極活物質を集電体に塗布するには、正極活物質に
重量比で数％〜数十％程度の導電助材、例えば黒鉛や非
晶質炭素等の炭素粉を混ぜ、さらにＰＶｄＦ（ポリフッ
化ビリニデン）、ＰＴＦＥ（ポリテトラフルオロエチレ
ン）等の結着剤とＮＭＰ（ｎ−メチル−ピロリドン）等
の溶媒を混練してペースト状にして集電体箔上に厚み20
μｍ〜200μｍに塗布、乾燥、プレス工程を経て正極が
作られている。2. Description of the Related Art Lithium secondary batteries have a higher energy density than nickel-cadmium batteries and nickel-hydrogen batteries and are rapidly spreading in the field of mobile terminals. It is also expected in the fields of electric vehicles and power storage. A lithium secondary battery is configured by arranging a positive electrode, a negative electrode and a separator in a container and filling a non-aqueous electrolytic solution with an organic solvent. The positive electrode active material is obtained by applying a positive electrode active material to a current collector such as an aluminum foil and press-molding it. Positive electrode active materials include lithium cobalt oxide (LiCoO 2 ) and lithium nickel oxide
(LiNiO 2 ), lithium manganate (LiMnO 2 ), spinel type lithium manganate (LiMn 2 O 4 ), and other composite oxides of lithium and transition metals (hereinafter referred to as lithium transition metal oxides). ) Powder is mainly used.
The synthesis of these positive electrode active materials is generally carried out using a lithium compound (Li 2 CO
3 , LiOH, LiCl, etc.) powders and transition metal compounds (MnCO 3 , MnO 2 ,
Mn 3 O 4 , Mn 2 O 3 , Co 3 O 4 , NiO, etc.) powders are mixed and fired to form lithium transition metal oxides. To apply the positive electrode active material to the current collector, the positive electrode active material is mixed with a conductive auxiliary material such as graphite or amorphous carbon in a weight ratio of several% to several tens% by weight, and PVdF (polyfluoride) is further added. Vinylidene chloride), PTFE (polytetrafluoroethylene) and other binders and NMP (n-methyl-pyrrolidone) and other solvents are kneaded to form a paste and a thickness of 20 on the collector foil.
A positive electrode is manufactured through a coating process, a drying process, and a pressing process to a thickness of μm to 200 μm.
【０００３】これら正極活物質は、電気伝導率が10-1〜
10-6S/cm2で一般の導体と比べ低く、アルミニウム集電
体と正極活物質間の電気伝導度および電気的接触状況
は、電池の初期容量や放電レート特性に大きな影響を与
える。そこで、アルミニウム集電体と正極活物質間もし
くは活物質相互間の電気伝導率を更に高めるように、正
極活物質よりも電気伝導率の高い炭素粉等の導電助材が
添加される。このような従来のコバルト酸リチウムやス
ピネル型マンガン酸リチウム等の正極活物質を集電体箔
に塗布形成した後の正極の状態を見ると、正極活物質お
よび導電助材は、通常、一次粒子が凝集した二次粒子の
状態で存在しており、凝集の仕方によりその分布は不均
一であった。このため、正極活物質と導電助材の間の電
気的接触状況にバラツキが生じ、正極活物質の能力を充
分に発揮することが出来なかった。These positive electrode active materials have an electric conductivity of 10 -1 to
At 10 -6 S / cm 2 , which is lower than that of general conductors, the electrical conductivity and electrical contact between the aluminum current collector and the positive electrode active material have a great influence on the initial capacity and discharge rate characteristics of the battery. Therefore, in order to further increase the electrical conductivity between the aluminum current collector and the positive electrode active material or between the active materials, a conductive auxiliary material such as carbon powder having a higher electrical conductivity than the positive electrode active material is added. Looking at the state of the positive electrode after applying and forming such a conventional positive electrode active material such as lithium cobalt oxide or spinel type lithium manganate on the current collector foil, the positive electrode active material and the conductive auxiliary material are usually primary particles. Exist in the form of aggregated secondary particles, and the distribution was non-uniform due to the manner of aggregation. For this reason, the electrical contact state between the positive electrode active material and the conductive auxiliary material varies, and the ability of the positive electrode active material cannot be fully exhibited.
【０００４】[0004]
【発明が解決しようとする課題】以上述べた従来技術に
おける正極の作製工程を図５に示す。従来技術によれ
ば、正極活物質、導電助材、結着剤を溶かした溶媒を各
々、別々に秤量して混練機にて一度に混練することによ
ってペーストを作製し、このペーストをアルミニウム集
電体に塗布し乾燥した後、プレスすることにより正極を
製造していた。このような従来法に使用されるコバルト
酸リチウムやスピネル型マンガン酸リチウム等の正極活
物質粒子は、粒子径がサブミクロンからミクロンオーダ
ーの一次粒子が凝集した二次粒子から構成されており、
その凝集力が強く、このような正極活物質を導電助材や
結着剤を溶かした溶媒と混練してアルミニウム集電体に
塗布した場合、正極活物質同士あるいは導電助材同士が
凝集し、集電体上に万遍なく正極活物質と導電助材が分
散した状態を得ることが不十分であった。このため、正
極活物質と導電助材の間の良好な接触を得るのが難し
く、初期容量が低くなるだけでなく、充放電サイクルが
進行するに従い、正極活物質自身が導電助材や集電体に
対し電気的に接触不良をおこし容量劣化の原因となった
り、放電電流を大きくした場合に容量が劣化する、いわ
ゆる放電レート特性の悪化する原因となっていた。FIG. 5 shows the steps for producing the positive electrode in the above-mentioned conventional technique. According to the conventional technique, a positive electrode active material, a conductive auxiliary material, and a solvent in which a binder is dissolved are separately weighed separately and kneaded at once with a kneader to prepare a paste, and the paste is made into an aluminum current collector. A positive electrode was manufactured by applying it to a body, drying it, and then pressing it. The positive electrode active material particles such as lithium cobalt oxide and spinel type lithium manganate used in such a conventional method are composed of secondary particles in which primary particles have a particle size of submicron to micron order are aggregated,
The cohesive force is strong, when such a positive electrode active material is kneaded with a solvent in which a conductive auxiliary material or a binder is dissolved and applied to an aluminum current collector, the positive electrode active materials or the conductive auxiliary materials are aggregated, It has been insufficient to obtain a state in which the positive electrode active material and the conductive additive are evenly dispersed on the current collector. For this reason, it is difficult to obtain good contact between the positive electrode active material and the conductive auxiliary material, and not only the initial capacity becomes low, but also the positive electrode active material itself may become a conductive auxiliary material or a collector as the charge / discharge cycle progresses. This causes electrical contact failure to the body and causes capacity deterioration, or capacity deterioration when the discharge current is increased, which is a cause of deterioration of so-called discharge rate characteristics.
【０００５】そこで本発明の目的は、正極活物質と導電
助材の分散性を改善し、電池の初期容量を向上させ、放
電レート特性を改善することである。この点で本発明で
作製した正極活物質と導電助材の複合材料は、分散性が
良好であり、作製に使用した噴霧乾燥法は、生産性、コ
スト面において有効な方法である。Therefore, an object of the present invention is to improve the dispersibility of the positive electrode active material and the conductive auxiliary material, improve the initial capacity of the battery, and improve the discharge rate characteristic. In this respect, the composite material of the positive electrode active material and the conductive auxiliary material produced in the present invention has good dispersibility, and the spray drying method used for the production is an effective method in terms of productivity and cost.
【０００６】[0006]
【課題を解決するための手段】本発明の非水系リチウム
二次電池用複合材料の製造方法は、遷移金属化合物とリ
チウム化合物を所定割合で反応させた正極活物質と導電
助材と結着剤を溶かした溶媒を混合してスラリーを作製
し、それを噴霧乾燥して複合材料を得ることを特徴とす
る。前記正極活物質は、スピネル型マンガン酸リチウ
ム、コバルト酸リチウムの少なくとも一種であることが
好ましい。前記導電助材は、炭素粉であることが望まし
く、炭素粉の周囲に正極活物質が保持されていることが
望ましい。炭素粉は比重が小さく、飛散し易いためであ
る。前記噴霧乾燥は、スプレードライヤで行うことが望
ましく、乾燥温度は１００〜３５０℃で行うことが望ま
しい。乾燥温度が１００℃未満の場合、乾燥が不十分で
あり、また３５０℃を越える場合、添加する炭素粉が分
解してしまう。さらには３００℃未満で乾燥することが
望ましい。前記噴霧乾燥の微粒化装置としては、加圧ノ
ズル式、２流体ノズル式、４流体ノズル式、ディスク式
があるが、いずれの装置を使用しても可能である。The method for producing a composite material for a non-aqueous lithium secondary battery according to the present invention comprises a positive electrode active material obtained by reacting a transition metal compound and a lithium compound at a predetermined ratio, a conductive auxiliary material, and a binder. Is mixed to prepare a slurry, which is spray-dried to obtain a composite material. The positive electrode active material is preferably at least one of spinel type lithium manganate and lithium cobalt oxide. The conductive auxiliary material is preferably carbon powder, and the positive electrode active material is preferably held around the carbon powder. This is because carbon powder has a low specific gravity and is easily scattered. The spray drying is preferably performed with a spray dryer, and the drying temperature is preferably 100 to 350 ° C. When the drying temperature is less than 100 ° C, the drying is insufficient, and when it exceeds 350 ° C, the carbon powder to be added is decomposed. Furthermore, it is desirable to dry at less than 300 ° C. As the atomizing device for spray drying, there are a pressure nozzle type, a two-fluid nozzle type, a four-fluid nozzle type and a disc type, but any of these can be used.
【０００７】これら本発明により合成された複合材料
は、噴霧乾燥により導電助材の周囲に正極活物質が保持
された構造となっている。このため、従来技術で正極活
物質と導電助材と結着剤を溶かした溶媒を混練し製造し
た正極に比べ、電極上に塗布した場合、正極活物質と導
電助材がむらなく均一に分散した状態で塗布できる。よ
って、正極活物質と導電助材との接触性が良くなり、電
気的な接触状態が良好になるため、初期容量および放電
レート特性も良好となる。The composite materials synthesized according to the present invention have a structure in which the positive electrode active material is held around the conductive auxiliary material by spray drying. Therefore, compared with the positive electrode manufactured by kneading the solvent in which the positive electrode active material, the conductive auxiliary material, and the binder are dissolved by the conventional technique, the positive electrode active material and the conductive auxiliary material are evenly and uniformly dispersed when applied on the electrode. It can be applied as it is. Therefore, the contact property between the positive electrode active material and the conductive additive is improved, and the electrical contact state is improved, so that the initial capacity and the discharge rate characteristics are also improved.
【０００８】本発明における複合材料は、非水系リチウ
ム二次電池用として有用なものである。例えば正極活物
質としてはスピネル型マンガン酸リチウム、コバルト酸
リチウムが適当であり、導電助材としては炭素粉が適当
であり、その製造方法としては噴霧乾燥が適当である。The composite material of the present invention is useful for a non-aqueous lithium secondary battery. For example, spinel type lithium manganate and lithium cobalt oxide are suitable as the positive electrode active material, carbon powder is suitable as the conductive auxiliary material, and spray drying is suitable as the manufacturing method thereof.
【０００９】[0009]
【発明の実施の形態】以下、本発明の実施例を図面を参
照して説明する。先ず、本発明による非水系リチウム二
次電池用複合材料は、図１のフローチャートに従って製
造される。まず工程１で、正極活物質（例えばLiCoO2,
LiMn2O4）、導電助材（例えば炭素粉）、結着剤（例え
ばポリビニルアルコール）、溶媒（例えば水）の所定量
を秤量する。なお、導電助材として金属粉を使用する場
合は、溶媒を有機溶媒に変えれば良い。また、長時間保
存する必要がなければ、結着剤を省くことも出来る。こ
れらの原料を工程２で、例えばボールミルを使って１〜
５０時間混合しスラリーを作製する。原料には必要によ
り添加元素として充放電特性を改善するためにCr, Al,
Co,Mg,Mo,Wの酸化物などを１〜１０ｗｔ％程度加えるこ
とも出来る。工程３でスラリーをスプレードライヤで噴
霧乾燥させて複合材料を作製する。噴霧乾燥とは、微粒
化装置を用いて乾燥室に微粒化したスラリーを供給し、
乾燥させて複合材料を得る方法である。ここで微粒化装
置としては、ディスク式、加圧ノズル式、２流体ノズル
式、４流体ノズル式の４種類の装置が従来用いられてお
り、どの方法を用いても複合材料を製造することが出来
る。このように、正極活物質と導電助材を最初から分散
させて複合化しておけば、正極を作製する時に充分な分
散性が得られる。次に工程４で篩い分けを行う。この篩
い分けによって複合材料の粒度分布を調整するが、必要
ない場合は省略することも出来る。BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, the composite material for a non-aqueous lithium secondary battery according to the present invention is manufactured according to the flowchart of FIG. First, in step 1, a positive electrode active material (for example, LiCoO 2 ,
LiMn 2 O 4 ), a conductive auxiliary material (for example, carbon powder), a binder (for example, polyvinyl alcohol), and a solvent (for example, water) are weighed in predetermined amounts. When metal powder is used as the conductive additive, the solvent may be changed to an organic solvent. Further, if it is not necessary to store it for a long time, the binder can be omitted. 1 to 2 of these raw materials in step 2, for example, using a ball mill
Mix for 50 hours to form a slurry. If necessary, Cr, Al, and
It is also possible to add an oxide of Co, Mg, Mo, W or the like in an amount of about 1 to 10 wt%. In step 3, the slurry is spray dried with a spray dryer to produce a composite material. Spray drying is a method of supplying atomized slurry to a drying chamber using an atomizer,
It is a method of obtaining a composite material by drying. Here, as the atomization device, four types of devices such as a disc type, a pressure nozzle type, a two-fluid nozzle type, and a four-fluid nozzle type have been conventionally used, and a composite material can be manufactured by any method. I can. Thus, if the positive electrode active material and the conductive auxiliary material are dispersed from the beginning to form a composite, sufficient dispersibility can be obtained when the positive electrode is manufactured. Next, in step 4, sieving is performed. This sieving adjusts the particle size distribution of the composite material, but can be omitted if not necessary.
【００１０】さて、図１のフローチャートにおける噴霧
乾燥は、例えば図２に概略を示すような噴霧乾燥装置を
用いることができる。図２の噴霧乾燥装置は、原料と溶
媒（例えば、水）の混合物を、ノズル先端部分で霧状に
微粒化した液滴を乾燥室で熱風に接触させ、瞬時に乾燥
する装置である。このため、正極活物質と導電助材を混
合した材料をそのままの状態で乾燥でき、導電助材の周
囲に正極活物質が保持された複合材料を得ることができ
る。For spray drying in the flow chart of FIG. 1, for example, a spray drying apparatus as schematically shown in FIG. 2 can be used. The spray-drying device of FIG. 2 is a device for instantaneously drying a mixture of a raw material and a solvent (for example, water) by atomizing droplets atomized into fine mist at the tip of a nozzle in a drying chamber to bring them into contact with hot air. Therefore, the material obtained by mixing the positive electrode active material and the conductive auxiliary material can be dried as it is, and a composite material in which the positive electrode active material is held around the conductive auxiliary material can be obtained.
【００１１】このようにして得られた複合材料は、最初
からミクロンオーダーで正極活物質と導電助材が混ざっ
ているため、電極上に塗布した場合、正極活物質と導電
助材がむらなく均一に分散した状態で塗布できる。この
ため、正極活物質と導電助材との接触性が良くなり、電
気的な接触状態も良好になるため、初期容量および放電
レート特性も良好となる。In the composite material thus obtained, since the positive electrode active material and the conductive auxiliary material are mixed in the order of micron from the beginning, when applied on the electrode, the positive electrode active material and the conductive auxiliary material are even and uniform. Can be applied in a dispersed state. Therefore, the contact property between the positive electrode active material and the conductive auxiliary material is improved, and the electrical contact state is also improved, so that the initial capacity and the discharge rate characteristics are also improved.
【００１２】本発明による正極の作製は以下の手順で行
った。まず、正極活物質と導電助材が複合化された複合
材料とＮＭＰに溶かした８ｗｔ％ＰＶｄＦを重量比で9
5：5の割合で混練しスラリ−状の合材とした。得られた
合材を厚さ２０μｍのアルミニウム集電体に約２００μ
ｍ厚に塗布した。塗布した合材を乾燥しプレスして約１
００μｍ厚にした後、所定の寸法に切断し、正極を得
た。得られた正極の特性評価は以下の手順で行った。ま
ず、正極の表面を走査型電子顕微鏡にて３００倍に拡大
して観察し、正極活物質と導電助材の分散性を確認し
た。次に正極を、電解液であるエチレンカ−ボネ−ト：
ジメチルカ−ボネ−ト＝1：2に溶かした1M−LiPF６（六
弗化燐リチウム）に十分に浸潤した後、セパレータ（25
μｍ厚ポリエチレン）、金属リチウム対極、金属リチウ
ム参照極とともに積み重ねてガラス瓶に付いている端子
と接続後、封入して評価用セルとした。セルが電気化学
的に平衡になるように数時間程度放置してから、充放電
測定装置に接続し測定を行った。The positive electrode according to the present invention was manufactured by the following procedure. First, a composite material in which a positive electrode active material and a conductive auxiliary material are composited, and 8 wt% PVdF dissolved in NMP are mixed in a weight ratio of 9%.
The mixture was kneaded at a ratio of 5: 5 to obtain a slurry-like mixture. About 200μ of the obtained mixture on a 20μm thick aluminum current collector
It was applied to a thickness of m. Approximately 1 by drying the coated mixture and pressing
After having a thickness of 00 μm, it was cut into a predetermined size to obtain a positive electrode. The characteristics of the obtained positive electrode were evaluated by the following procedure. First, the surface of the positive electrode was magnified 300 times with a scanning electron microscope and observed to confirm the dispersibility of the positive electrode active material and the conductive additive. Next, the positive electrode was charged with an ethylene carbonate as an electrolytic solution:
After sufficiently infiltrating 1M-LiPF 6 (lithium hexafluorofluoride) dissolved in dimethyl carbonate = 1: 2, a separator (25
(μm thick polyethylene), a metal lithium counter electrode, and a metal lithium reference electrode were stacked and connected to a terminal attached to a glass bottle, and then sealed to obtain a cell for evaluation. The cell was left for several hours so that it became electrochemically equilibrium, and then the cell was connected to a charge / discharge measuring device for measurement.
【００１３】以下、正極活物質としてコバルト酸リチウ
ム、導電助材として炭素粉を用いた実施例について説明
する。
（実施例１）図1に従い、コバルト酸リチウムと炭素粉
をそれぞれ所定量秤量し、これに水を加えてボ−ルミル
で混合してスラリーを作製した。このスラリーにＰＶＡ
溶液を添加攪拌した後、ディスク式ノズルを備えた噴霧
乾燥装置を用いて、乾燥温度２８０℃で噴霧乾燥し、球
状粒子を得た。得られた球状粒子を篩い分けし、平均粒
径１５μｍの複合材料を合成した。得られた複合材料の
断面を走査型電子顕微鏡で観察した結果を図３に示す。
図３において、白い部分が正極活物質、灰色の部分が導
電助材である。図３から判るように、導電助材（炭素
粉）の周囲に正極活物質が保持された球状の二次粒子が
形成され、正極活物質と導電助材が複合化されている。An example in which lithium cobalt oxide is used as the positive electrode active material and carbon powder is used as the conduction aid will be described below. (Example 1) According to FIG. 1, a predetermined amount of lithium cobalt oxide and carbon powder were weighed, water was added thereto and mixed by a ball mill to prepare a slurry. PVA in this slurry
After the solution was added and stirred, it was spray-dried at a drying temperature of 280 ° C. by using a spray-drying device equipped with a disc type nozzle to obtain spherical particles. The obtained spherical particles were sieved to synthesize a composite material having an average particle diameter of 15 μm. The result of observing the cross section of the obtained composite material with a scanning electron microscope is shown in FIG.
In FIG. 3, the white portion is the positive electrode active material and the gray portion is the conductive auxiliary material. As can be seen from FIG. 3, spherical secondary particles in which the positive electrode active material is held are formed around the conductive auxiliary material (carbon powder), and the positive electrode active material and the conductive auxiliary material are combined.
【００１４】得られた複合材料を用いて、図４に従い、
複合材料と溶媒に溶かした結着剤をそれぞれ所定量秤量
し、混練してスラリーを作製した。このスラリーをアル
ミニウム集電体に塗布した後、乾燥しプレスして正極を
合成した。得られた正極の表面を走査型電子顕微鏡で観
察した結果を図６の実施例１に示す。図６において、白
い部分が正極活物質、黒色の部分が導電助材である。図
６の実施例１から判るように、本発明による複合材料を
用いれば正極活物質および導電助材の凝集が少なく、分
散性は良好であった。According to FIG. 4, using the obtained composite material,
A predetermined amount of each of the composite material and the binder dissolved in the solvent was weighed and kneaded to prepare a slurry. After applying this slurry to an aluminum current collector, it was dried and pressed to synthesize a positive electrode. The result of observing the surface of the obtained positive electrode with a scanning electron microscope is shown in Example 1 of FIG. In FIG. 6, the white portion is the positive electrode active material and the black portion is the conductive auxiliary material. As can be seen from Example 1 in FIG. 6, when the composite material according to the present invention was used, aggregation of the positive electrode active material and the conductive additive was small and the dispersibility was good.
【００１５】（比較例１）実施例１で用いたコバルト酸
リチウムと炭素粉と溶媒に溶かした結着剤をそれぞれ所
定量秤量し、混練してスラリーを作製した。このスラリ
ーをアルミニウム集電体に塗布した後、乾燥しプレスし
て正極を合成した。得られた正極の表面を走査型電子顕
微鏡で観察した結果を図６の比較例１に示す。図６の比
較例１から判るように、複合材料を用いない場合、正極
活物質が凝集した白い塊の部分、あるいは導電助材が凝
集した黒い塊の部分が観察され、分散性は不十分であっ
た。以上の実施例および比較例について特性評価を行っ
た結果を表１に示す。Comparative Example 1 A predetermined amount of each of the lithium cobalt oxide used in Example 1, the carbon powder, and the binder dissolved in the solvent was weighed and kneaded to prepare a slurry. After applying this slurry to an aluminum current collector, it was dried and pressed to synthesize a positive electrode. The result of observing the surface of the obtained positive electrode with a scanning electron microscope is shown in Comparative Example 1 of FIG. As can be seen from Comparative Example 1 in FIG. 6, when the composite material was not used, a white lump portion in which the positive electrode active material was aggregated or a black lump portion in which the conductive auxiliary material was aggregated was observed, and the dispersibility was insufficient. there were. Table 1 shows the results of the characteristic evaluations of the above Examples and Comparative Examples.
【００１６】[0016]
【表１】 [Table 1]
【００１７】表１より、本発明の複合材料を用いれば良
好な分散状態が得られ、これにより初期の放電容量が高
く、放電レートを高くした時の容量維持率においても好
ましい結果を得ることが出来た。これに対して、比較例
１のように複合材料を用いない場合、分散性が悪く、こ
のため初期の放電容量が低くなり、放電レートを高くし
た時の容量維持率も低下する結果となった。From Table 1, when the composite material of the present invention is used, a good dispersion state is obtained, whereby the initial discharge capacity is high, and a favorable result can be obtained also in the capacity retention rate when the discharge rate is increased. done. On the other hand, when the composite material was not used as in Comparative Example 1, the dispersibility was poor, which resulted in a low initial discharge capacity and a low capacity retention rate when the discharge rate was increased. .
【００１８】（実施例２）：正極活物質としてスピネル
型マンガン酸リチウムを使用した以外は、実施例1と同
様に操作して複合材料を合成した。Example 2 A composite material was synthesized in the same manner as in Example 1 except that spinel type lithium manganate was used as the positive electrode active material.
【００１９】正極活物質としてスピネル型マンガン酸リ
チウムを使用した以外は、実施例１と同様に操作して正
極を合成した。A positive electrode was synthesized in the same manner as in Example 1 except that spinel type lithium manganate was used as the positive electrode active material.
【００２０】（比較例２）実施例２で用いたスピネル型
マンガン酸リチウムと炭素粉と溶媒に溶かした結着剤を
それぞれ所定量秤量し、混練してスラリーを作製した。
このスラリーをアルミニウム集電体に塗布した後、乾燥
しプレスして正極を合成した。以上の実施例および比較
例について特性評価を行った結果を表２に示す。Comparative Example 2 The spinel type lithium manganate used in Example 2, the carbon powder and the binder dissolved in the solvent were weighed in predetermined amounts and kneaded to prepare a slurry.
After applying this slurry to an aluminum current collector, it was dried and pressed to synthesize a positive electrode. Table 2 shows the results of the characteristic evaluation of the above Examples and Comparative Examples.
【００２１】[0021]
【表２】 [Table 2]
【００２２】表２より、本発明の複合材料を用いれば良
好な分散状態が得られ、初期の放電容量が高く、放電レ
ートを高くした時の容量維持率においても好ましい結果
を得ることが出来た。これに対して、比較例２のように
複合材料を用いない場合、分散性が悪く、このため初期
の放電容量が低くなり、放電レートを高くした時の容量
維持率も低下する結果となった。From Table 2, using the composite material of the present invention, a good dispersion state was obtained, the initial discharge capacity was high, and favorable results were obtained also in the capacity retention rate when the discharge rate was increased. . On the other hand, when the composite material was not used as in Comparative Example 2, the dispersibility was poor, which resulted in a low initial discharge capacity and a low capacity retention rate when the discharge rate was increased. .
【００２３】[0023]
【発明の効果】以上のように、本発明によれば、正極活
物質と導電助材の分散性を改善することが出来、駆動用
電源として好ましい非水系リチウム二次電池用の複合材
料とそれ用いた正極を得ることが出来、有用な非水系リ
チウム二次電池を提供することが出来る。As described above, according to the present invention, the dispersibility of the positive electrode active material and the conductive auxiliary material can be improved, and the composite material for a non-aqueous lithium secondary battery, which is preferable as a driving power source, and the same. The positive electrode used can be obtained, and a useful non-aqueous lithium secondary battery can be provided.
【図１】本発明に従って複合材料を作製するためのフロ
ーチャートを示す。FIG. 1 shows a flow chart for making a composite material according to the present invention.
【図２】本発明において噴霧乾燥を行い複合材料を作製
するための装置概略図である。FIG. 2 is a schematic view of an apparatus for producing a composite material by performing spray drying in the present invention.
【図３】本発明において作製した複合材料の断面写真で
ある。FIG. 3 is a cross-sectional photograph of the composite material produced in the present invention.
【図４】本発明に従って正極を作製するためのフローチ
ャートを示す。FIG. 4 shows a flow chart for making a positive electrode according to the present invention.
【図５】従来法に従って正極を作製するためのフローチ
ャートを示す。FIG. 5 shows a flowchart for producing a positive electrode according to a conventional method.
【図６】本発明および従来法に従って作製した正極の表
面写真である。FIG. 6 is a surface photograph of a positive electrode manufactured according to the present invention and a conventional method.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ テーマコート゛(参考） Ｈ０１Ｍ 10/40 Ｈ０１Ｍ 10/40 Ｚ (72)発明者 川田 常宏 埼玉県熊谷市三ヶ尻5200番地 日立金属株 式会社先端エレクトロニクス研究所内 Ｆターム(参考） 4G048 AA04 AB01 AB06 AC04 AC06 AE05 5H029 AJ02 AJ03 AK03 AL12 AM03 AM05 AM07 CJ02 CJ05 CJ08 CJ22 CJ30 DJ08 DJ16 EJ04 EJ12 HJ14 5H050 AA02 AA08 BA15 CA08 CA09 CB12 DA10 DA11 EA08 EA23 FA17 FA18 GA02 GA07 GA10 GA22 GA29 HA14 ─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. 7 Identification code FI theme code (reference) H01M 10/40 H01M 10/40 Z (72) Inventor Tsunehiro Kawada 5200 Mikkajiri, Kumagaya-shi, Saitama Hitachi Metals Co., Ltd. F-Term in Advanced Electronics Research Laboratory (reference) 4G048 AA04 AB01 AB06 AC04 AC06 AE05 5H029 AJ02 AJ03 AK03 AL12 AM03 AM05 AM07 CJ02 CJ05 CJ08 CJ22 CJ30 DJ08 DJ16 EJ04 EJ12 HJ14 5H050 AA02 AA08 BA15 CA18 DA23 FA12 CA11 GA07 GA10 GA22 GA29 HA14
Claims (7)
合して焼成し、得られた正極活物質と導電助材を噴霧乾
燥装置を用いて複合化することを特徴とする非水系リチ
ウム二次電池用正極活物質と導電助材の複合方法。1. A non-aqueous lithium secondary battery characterized in that a transition metal compound and a lithium compound are mixed and fired, and the obtained positive electrode active material and a conductive auxiliary material are compounded using a spray dryer. Method for compounding positive electrode active material and conductive additive for automobile.
合して焼成し、得られた正極活物質と炭素粉を噴霧乾燥
装置を用いて複合化することを特徴とする非水系リチウ
ム二次電池用正極活物質と導電助材の複合方法。2. A positive electrode for a non-aqueous lithium secondary battery, wherein a cobalt compound and a lithium compound are mixed and fired, and the obtained positive electrode active material and carbon powder are compounded using a spray dryer. A composite method of an active material and a conductive auxiliary material.
合して焼成し、得られた正極活物質と炭素粉を噴霧乾燥
装置を用いて複合化することを特徴とする非水系リチウ
ム二次電池用正極活物質と導電助材の複合方法。3. A positive electrode for a non-aqueous lithium secondary battery, characterized in that a manganese compound and a lithium compound are mixed and fired, and the obtained positive electrode active material and carbon powder are compounded using a spray dryer. A composite method of an active material and a conductive auxiliary material.
いて行い、乾燥温度を１００〜３５０℃で行うことを特
徴とする請求項１乃至３の何れかに記載の非水系リチウ
ム二次電池用正極活物質と導電助材の複合方法。4. The positive electrode for a non-aqueous lithium secondary battery according to claim 1, wherein the spray drying is performed using a spray dryer and a drying temperature is 100 to 350 ° C. A composite method of an active material and a conductive auxiliary material.
ウム二次電池用正極活物質と導電助材の複合方法により
得られた複合材料であって、導電助材は炭素粉であり、
この炭素粉の周囲に正極活物質が保持されていることを
特徴とする非水系リチウム二次電池用正極活物質と導電
助材の複合材料。5. A composite material obtained by the composite method of a positive electrode active material for a non-aqueous lithium secondary battery according to claim 1 and a conductive auxiliary material, wherein the conductive auxiliary material is carbon powder,
A composite material of a positive electrode active material for a non-aqueous lithium secondary battery and a conductive auxiliary material, characterized in that a positive electrode active material is held around the carbon powder.
物を正極活物質として、この正極活物質と導電助材を複
合化した材料に結着剤を溶かした溶媒を添加・混練した
後、これを金属箔に塗布・圧着・乾燥したことを特徴と
する正極。6. A composite oxide composed of lithium and a transition metal is used as a positive electrode active material, and a solvent in which a binder is dissolved is added to and kneaded with a material obtained by combining the positive electrode active material and a conductive auxiliary material, and then this is mixed. A positive electrode characterized by being coated, pressed and dried on a metal foil.
とする非水系リチウム二次電池。7. A non-aqueous lithium secondary battery using the positive electrode according to claim 7.
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| JP2001373747A JP2003173777A (en) | 2001-12-07 | 2001-12-07 | Combining method and its combining material of positive electrode active material for nonaqueous lithium secondary battery and conductive subsidiary material, and positive electrode and nonaqueous lithium secondary battery using the same |
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