JP2001089118A - Graphite particle, method for producing the same, negative electrode for lithium secondary battery and lithium secondary battery - Google Patents
Graphite particle, method for producing the same, negative electrode for lithium secondary battery and lithium secondary batteryInfo
- Publication number
- JP2001089118A JP2001089118A JP26139099A JP26139099A JP2001089118A JP 2001089118 A JP2001089118 A JP 2001089118A JP 26139099 A JP26139099 A JP 26139099A JP 26139099 A JP26139099 A JP 26139099A JP 2001089118 A JP2001089118 A JP 2001089118A
- Authority
- JP
- Japan
- Prior art keywords
- secondary battery
- lithium secondary
- graphite particles
- negative electrode
- graphite
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- 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
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、黒鉛粒子、その製
造法、前記黒鉛粒子を使用したリチウム二次電池用負極
及び前記負極を使用したリチウム二次電池に関する。さ
らに詳しくは、ポータブル機器、電気自動車、電力貯蔵
等に用いるのに好適な、高容量でかつサイクル特性、急
速充放電特性、安全性に優れたリチウム二次電池とそれ
を得るための負極、黒鉛粒子及びその製造法に関する。The present invention relates to graphite particles, a method for producing the same, a negative electrode for a lithium secondary battery using the graphite particles, and a lithium secondary battery using the negative electrode. More specifically, a lithium secondary battery having a high capacity, excellent in cycle characteristics, rapid charge / discharge characteristics, and safety, suitable for use in portable devices, electric vehicles, and electric power storage, and a negative electrode and graphite for obtaining the same. The present invention relates to particles and a method for producing the particles.
【０００２】[0002]
【従来の技術】従来のリチウム二次電池の負極材には、
例えば天然黒鉛粒子、コークスを黒鉛化した人造黒鉛粒
子、有機系高分子材料、ピッチ等を黒鉛化した人造黒鉛
粒子、これらを粉砕した黒鉛粒子などがある。これらの
黒鉛粒子は有機系結着剤及び有機溶剤と混合して黒鉛ペ
ーストとし、この黒鉛ペーストを銅箔の表面に塗布し、
溶剤を乾燥して、リチウム二次電池用負極として使用さ
れている。例えば、特公昭６２−２３４３３号公報に示
されるように、負極に黒鉛を使用することでリチウムの
デンドライトによる内容短絡の問題を解消し、サイクル
特性の改良を図っている。2. Description of the Related Art Conventional negative electrode materials for lithium secondary batteries include:
Examples thereof include natural graphite particles, artificial graphite particles obtained by graphitizing coke, organic polymer materials, artificial graphite particles obtained by graphitizing pitch and the like, and graphite particles obtained by pulverizing these. These graphite particles are mixed with an organic binder and an organic solvent to form a graphite paste, and the graphite paste is applied to the surface of a copper foil,
The solvent is dried and used as a negative electrode for a lithium secondary battery. For example, as shown in JP-B-62-23433, the use of graphite for the negative electrode solves the problem of content short-circuit due to lithium dendrite, thereby improving cycle characteristics.
【０００３】しかしながら、黒鉛結晶が発達している天
然黒鉛は、Ｃ軸方向の結晶の層間の結合力が、結晶の面
方向の結合に比べて弱いため、粉砕により黒鉛層間の結
合が切れ、アスペクト比が大きいいわゆる鱗状の黒鉛粒
子となる。鱗状黒鉛は、アスペクト比が大きいために、
バインダと混練して集電体に塗布して電極を作製したと
きに、鱗状黒鉛粒子が集電体の面方向に配向し、その結
果、充放電容量や急速充放電特性が低下しやすいばかり
でなく、黒鉛結晶へのリチウムの吸蔵・放出の繰り返し
によって発生するＣ軸方向の膨張・収縮により電極内部
の破壊が生じ、サイクル特性が低下する問題がある。更
にはアスペクト比が大きい黒鉛は比表面積も大きくなり
やすく、作製するリチウム二次電池の第一サイクル目の
不可逆容量が大きくエネルギー密度が小さく、また安全
性が低下する問題がある。そこで、高容量で、サイクル
特性、急速充放電特性が向上できるリチウム二次電池が
作製できる負極用炭素材料が要求されている。However, natural graphite in which graphite crystals are developed has a weaker bonding force between the layers of the crystal in the C-axis direction than the bonding in the plane direction of the crystals. So-called scale-like graphite particles having a large ratio are obtained. Scale-like graphite has a large aspect ratio,
When an electrode is produced by kneading with a binder and applying the mixture to a current collector, the scale-like graphite particles are oriented in the plane direction of the current collector, and as a result, the charge / discharge capacity and rapid charge / discharge characteristics are liable to be reduced. In addition, there is a problem that the inside of the electrode is broken due to the expansion and contraction in the C-axis direction caused by the repeated insertion and extraction of lithium into and from the graphite crystal, and the cycle characteristics are reduced. Furthermore, graphite having a large aspect ratio tends to have a large specific surface area, and the irreversible capacity in the first cycle of the produced lithium secondary battery is large, the energy density is small, and the safety is reduced. Therefore, there is a demand for a carbon material for a negative electrode capable of producing a lithium secondary battery having high capacity and improved cycle characteristics and rapid charge / discharge characteristics.
【０００４】[0004]
【発明が解決しようとする課題】本発明は、高容量で、
サイクル特性、急速充放電特性、安全性に優れるリチウ
ム二次電池の負極材料に好適な黒鉛粒子を提供するもの
である。また本発明は、高容量で、サイクル特性、急速
充放電特性、安全性に優れたリチウム二次電池の負極材
料に好適な黒鉛粒子の製造方法を提供するものである。
また本発明は、高容量で、サイクル特性、急速充放電特
性、安全性に優れたリチウム二次電池用負極を提供する
ものである。さらに本発明は、高容量で、サイクル特
性、急速充放電特性、安全性に優れたリチウム二次電池
を提供するものである。SUMMARY OF THE INVENTION The present invention has a high capacity,
An object of the present invention is to provide graphite particles suitable for a negative electrode material of a lithium secondary battery having excellent cycle characteristics, rapid charge / discharge characteristics, and safety. Another object of the present invention is to provide a method for producing graphite particles suitable for a negative electrode material of a lithium secondary battery having high capacity, excellent in cycle characteristics, rapid charge / discharge characteristics, and safety.
Another object of the present invention is to provide a negative electrode for a lithium secondary battery having a high capacity and excellent in cycle characteristics, rapid charge / discharge characteristics, and safety. Further, the present invention provides a lithium secondary battery having high capacity, excellent cycle characteristics, rapid charge / discharge characteristics, and excellent safety.
【０００５】[0005]
【課題を解決するための手段】本発明は、比表面積が
０．３〜２．０m2/g、アスペクト比が１．１〜５、かさ
密度が０．５g/cm3以上であり、偏平状の粒子を複数集
合又は結合してなる形状を有してなる黒鉛粒子に関す
る。また本発明は、結晶の層間距離ｄ（００２）が３．
３８Å以下、Ｃ軸方向の結晶子サイズＬｃ（００２）が
５００Å以上、平均粒径が１０〜１００μｍである前記
黒鉛粒子に関する。SUMMARY OF THE INVENTION The present invention relates to a flat plate having a specific surface area of 0.3 to 2.0 m 2 / g, an aspect ratio of 1.1 to 5 and a bulk density of 0.5 g / cm 3 or more. The present invention relates to a graphite particle having a shape formed by assembling or combining a plurality of particles in a shape. In the present invention, the interlayer distance d (002) of the crystal is 3.
The present invention relates to the graphite particles having a crystallite size Lc (002) in the C-axis direction of not more than 38 ° and not less than 500 ° and an average particle size of 10 to 100 μm.
【０００６】また本発明は、黒鉛化可能な骨材又は黒鉛
と黒鉛化可能なバインダを混合する工程、前記工程で得
られた混合物を５００〜２０００℃で焼成する工程、前
記工程で得られた焼成物を平均粒径１０〜１００μｍに
粉砕する工程、前記工程で得られた粉砕物を２５００℃
以上で黒鉛化する工程を含んでなる黒鉛粒子の製造法に
関する。また本発明は、前記黒鉛化可能な骨材が、平均
粒径が１〜８０μｍのコークス粉末である黒鉛粒子の製
造法に関する。Further, the present invention provides a step of mixing a graphitizable aggregate or graphite with a graphitizable binder, a step of firing the mixture obtained in the above step at 500 to 2000 ° C., and a step obtained by the above step. A step of pulverizing the calcined product to an average particle size of 10 to 100 μm;
The above relates to a method for producing graphite particles including a step of graphitizing. The present invention also relates to a method for producing graphite particles, wherein the graphitizable aggregate is coke powder having an average particle size of 1 to 80 μm.
【０００７】また本発明は、前記黒鉛粒子又は前記製造
法で製造した黒鉛粒子を含有してなるリチウム二次電池
用負極に関する。さらに本発明は、前記リチウム二次電
池用負極と、リチウム化合物を含む正極を有してなるリ
チウム二次電池に関する。[0007] The present invention also relates to a negative electrode for a lithium secondary battery containing the above graphite particles or the graphite particles produced by the above production method. Further, the present invention relates to a lithium secondary battery having the negative electrode for a lithium secondary battery and a positive electrode containing a lithium compound.
【０００８】[0008]
【発明の実施の形態】本発明になる黒鉛粒子は、比表面
積が０．３〜２．０m2/g、アスペクト比が１．１〜５、
かさ密度が０．５g/cm3以上であり、偏平状の粒子を複
数集合又は結合してなる形状を有してなるることが必要
であり、さらに、結晶の層間距離ｄ（００２）が３．３
８Å以下、Ｃ軸方向の結晶子サイズＬｃ（００２）が５
００Å以上、平均粒径が１０〜１００μｍである黒鉛粒
子であることが好ましい。DESCRIPTION OF THE PREFERRED EMBODIMENTS Graphite particles according to the present invention have a specific surface area of 0.3 to 2.0 m 2 / g, an aspect ratio of 1.1 to 5,
It is necessary that the bulk density is 0.5 g / cm 3 or more, and that the particles have a shape in which a plurality of flat particles are aggregated or bonded, and the interlayer distance d (002) of the crystal is 3 .3
8 ° or less, the crystallite size Lc (002) in the C-axis direction is 5
It is preferably graphite particles having an average particle diameter of 100 ° or more and 10 to 100 μm.
【０００９】このような黒鉛粒子を負極に使用すると、
高容量で、急速充放電特性、サイクル特性、安全性に優
れたリチウム二次電池を作製することが可能となる。こ
こで結晶の層間距離ｄ（００２）は黒鉛粒子の広角Ｘ線
回折の測定から算出される値は、３．３８Å以下である
ことが好ましく、３．３５〜３．３７の範囲であればよ
り好ましく、３．３５〜３．３６Åの範囲であればさら
に好ましい。この値が３．３８Åを超えると放電容量が
小さくなり、作製するリチウム二次電池の充放電容量が
小さくなる傾向にある。When such graphite particles are used for a negative electrode,
It is possible to manufacture a lithium secondary battery having high capacity and excellent in rapid charge / discharge characteristics, cycle characteristics, and safety. Here, as for the interlayer distance d (002) of the crystal, the value calculated from the wide-angle X-ray diffraction measurement of the graphite particles is preferably 3.38 ° or less, and more preferably in the range of 3.35 to 3.37. It is more preferably in the range of 3.35 to 3.36 °. If this value exceeds 3.38 °, the discharge capacity tends to be small, and the charge / discharge capacity of the produced lithium secondary battery tends to be small.
【００１０】また、Ｃ軸方向の結晶子サイズＬｃ（００
２）も広角Ｘ線回折の測定から算出される値で、５００
Å以上であることが好ましく、７００Å以上であればよ
り好ましく、１０００Å以上であればさらに好ましい。
この値が５００Å未満になると放電容量が小さくなり、
得られるリチウム二次電池の充放電容量が小さくなる傾
向にある。Further, the crystallite size Lc (00
2) is also a value calculated from the measurement of wide-angle X-ray diffraction, and is 500
Å or more, more preferably 700 Å or more, and even more preferably 1000 Å or more.
When this value is less than 500 °, the discharge capacity decreases,
The charge / discharge capacity of the obtained lithium secondary battery tends to be small.
【００１１】黒鉛粒子の比表面積は、０．３〜２．０m2
/gの範囲であることが必要とされ、０．４〜１．５m2/g
の範囲であれば好ましく、０．４〜１．０m2/gの範囲で
あればより好ましい。黒鉛粒子の比表面積が２．０m2/g
を超えると得られるリチウム二次電池の第一サイクル目
の不可逆容量が大きくなり、その結果エネルギー密度が
小さく、さらに安全性が低下する。また、黒鉛粒子の比
表面積が０．３m2/g未満では、得られるリチウム二次電
池のサイクル特性が低下する問題がある。比表面積の測
定は、ＢＥＴ法（窒素ガス吸着法）などの既知の方法を
とることができる。The specific surface area of the graphite particles is 0.3 to 2.0 m 2
/ g in the range of 0.4-1.5 m 2 / g
And more preferably in the range of 0.4 to 1.0 m 2 / g. The specific surface area of graphite particles is 2.0m 2 / g
When the value exceeds the above, the irreversible capacity in the first cycle of the obtained lithium secondary battery becomes large, and as a result, the energy density becomes small and the safety further decreases. Further, when the specific surface area of the graphite particles is less than 0.3 m 2 / g, there is a problem that the cycle characteristics of the obtained lithium secondary battery deteriorate. The specific surface area can be measured by a known method such as a BET method (nitrogen gas adsorption method).
【００１２】黒鉛粒子のアスペクト比は１．１〜５の範
囲であることが必要とされ、１．１〜３の範囲であれば
好ましく、１．３〜３の範囲であればより好ましく、
１．３〜２の範囲であればさらに好ましい。黒鉛粒子の
アスペクト比が１．１未満では、粒子間の接触面積が減
ることにより、導電性が低下する傾向にある。一方、ア
スペクトが５より大きくなると、急速充放電特性が低下
し易くなる傾向がある。なお、アスペクト比は、黒鉛粒
子の長軸方向の長さをＡ、短軸方向の長さをＢとしたと
き、Ａ／Ｂで表される。本発明におけるアスペクト比
は、顕微鏡で黒鉛粒子を拡大し、任意に１０個の粒子を
選択し、Ａ／Ｂを測定し、その平均値をとったものであ
る。The aspect ratio of the graphite particles is required to be in the range of 1.1 to 5, preferably in the range of 1.1 to 3, more preferably in the range of 1.3 to 3,
It is more preferable that the ratio is in the range of 1.3 to 2. When the aspect ratio of the graphite particles is less than 1.1, the contact area between the particles tends to decrease, so that the conductivity tends to decrease. On the other hand, when the aspect ratio is larger than 5, the rapid charge / discharge characteristics tend to decrease. The aspect ratio is represented by A / B, where A is the length in the major axis direction of the graphite particles and B is the length in the minor axis direction. The aspect ratio in the present invention is obtained by magnifying graphite particles with a microscope, arbitrarily selecting ten particles, measuring A / B, and taking the average value.
【００１３】また、黒鉛粒子のかさ密度は０．５g/cm3
以上であることが必要とされ、０．７g/cm3以上であれ
ば好ましく、０．９g/cm3以上であればより好ましく、
１．１g/cm3以上であればさらに好ましい。上限は特に
ないが、通常黒鉛の真密度である２．２g/cm3以下とさ
れる。黒鉛粒子のかさ密度が０．５g/cm3未満であると
負極を作製する際多くの結着剤が必要になり易く、その
結果作製するリチウム二次電池のエネルギー密度が小さ
くなり、また、負極を作成する際に使用する結着剤の量
を増量しないときは、集電体と黒鉛粒子の密着力が低下
し、その結果サイクル特性が低下する。かさ密度の測定
は、容量１００cm3のメスシリンダーを斜めにし、これ
に試料粉末１００cm3をさじを用いて徐々に投入し、メ
スシリンダーに栓をした後、メスシリンダーを５cmの高
さから５０回落下させた後の試料粉末の重量及び容積か
ら算出することができる。The bulk density of the graphite particles is 0.5 g / cm 3
It is necessary to be at least 0.7 g / cm 3 or more, more preferably 0.9 g / cm 3 or more,
More preferably, it is 1.1 g / cm 3 or more. Although there is no particular upper limit, it is usually set to 2.2 g / cm 3 or less, which is the true density of graphite. When the bulk density of the graphite particles is less than 0.5 g / cm 3 , a large amount of a binder is likely to be required when producing the negative electrode, and as a result, the energy density of the lithium secondary battery to be produced becomes small, and When the amount of the binder used in preparing the carbon black is not increased, the adhesion between the current collector and the graphite particles decreases, and as a result, the cycle characteristics deteriorate. To measure the bulk density, a measuring cylinder having a capacity of 100 cm 3 was slanted, and 100 cm 3 of sample powder was gradually poured into the measuring cylinder using a spoon. After the measuring cylinder was plugged, the measuring cylinder was dropped 50 times from a height of 5 cm. It can be calculated from the weight and volume of the sample powder after the drop.
【００１４】黒鉛粒子の平均粒径は、１０〜１００μｍ
の範囲であることが好ましく、１０〜８０μｍの範囲で
あればより好ましく、１０〜５０μｍの範囲であればさ
らに好ましい。本発明における平均粒径は、レーザー回
折式粒度分布計により測定することができ、その５０％
累積粒径を平均粒径と定義する。平均粒径が１０μｍ未
満では、負極を作製する際多くの結着剤が必要になり易
く、その結果作製するリチウム二次電池のエネルギー密
度が小さくなり、また、負極を作成する際に使用する結
着剤の量を増量しないときは、集電体と黒鉛粒子の密着
力が低下し、その結果サイクル特性が低下する傾向にあ
る。一方、１００μｍを超えると作成する電極の表面に
凹凸ができやすく、その結果、正極と負極が短絡しやす
くなる問題がある。The average particle size of the graphite particles is 10 to 100 μm.
Is preferably in the range of 10 to 80 μm, and more preferably in the range of 10 to 50 μm. The average particle size in the present invention can be measured by a laser diffraction type particle size distribution meter, and its 50%
The cumulative particle size is defined as the average particle size. When the average particle size is less than 10 μm, a large amount of a binder is likely to be required when producing the negative electrode, and as a result, the energy density of the lithium secondary battery produced becomes small, and the binder used when producing the negative electrode is produced. When the amount of the adhesive is not increased, the adhesion between the current collector and the graphite particles decreases, and as a result, the cycle characteristics tend to decrease. On the other hand, when the thickness exceeds 100 μm, irregularities are likely to be formed on the surface of the electrode to be formed, and as a result, there is a problem that the positive electrode and the negative electrode are easily short-circuited.
【００１５】本発明になる黒鉛粒子の構造は、偏平状の
粒子を複数集合又は結合してなる黒鉛粒子であることが
必要である。本発明において、偏平状の粒子とは、長軸
と短軸を有する形状の粒子のことであり、完全な球状で
ないものをいう。例えば鱗状、鱗片状、一部の塊状等の
形状のものがこれに含まれる。この黒鉛粒子において偏
平状の粒子は集合又は結合しているが、結合とは互いの
粒子が、タール、ピッチ等のバインダーを炭素化した炭
素（黒鉛を含む）を介して、化学的に結合している状態
をいい、集合とは互いの粒子が化学的に結合していない
が、その形状に起因して、その集合体としての形状を保
っている状態をいう。機械的な強度の面から、結合して
いるものが好ましい。The structure of the graphite particles according to the present invention is required to be a graphite particle obtained by assembling or combining a plurality of flat particles. In the present invention, flat particles are particles having a shape having a major axis and a minor axis, and are not perfectly spherical. For example, a shape such as a scaly shape, a scaly shape, or a partial lump shape is included in this. In the graphite particles, the flat particles are aggregated or bonded. The bond means that the particles are chemically bonded via carbon (including graphite) obtained by carbonizing a binder such as tar and pitch. The term "assembly" refers to a state in which particles are not chemically bonded to each other, but maintains the shape of the aggregate due to its shape. From the standpoint of mechanical strength, it is preferable to combine them.
【００１６】また黒鉛粒子の偏平状の粒子の集合又は結
合の状態としては、偏平状の粒子の配向面が非平行とな
るように集合又は結合している黒鉛粒子を含むことが好
ましい。ここで、偏平状の粒子の配向面が非平行とは、
それぞれの粒子の形状において有する偏平した面、換言
すれば最も平らに近い面を配向面として、複数の偏平状
の粒子がそれぞれの配向面を一定の方向にそろうことな
く集合している状態をいう。黒鉛粒子の構造を上記のよ
うにすることで、作製するリチウム二次電池の急速充放
電特性及びサイクル特性をより向上させることが可能と
なる。Preferably, the flat particles of the graphite particles are in a state of aggregation or bonding, and include graphite particles which are aggregated or bonded such that the orientation planes of the flat particles are non-parallel. Here, the orientation plane of the flat particles is non-parallel,
A flat surface having a shape of each particle, in other words, a state in which a plurality of flat particles are gathered without aligning each of the alignment surfaces in a certain direction, with the plane closest to the plane being the alignment surface. . By making the structure of the graphite particles as described above, it is possible to further improve the rapid charge / discharge characteristics and the cycle characteristics of the lithium secondary battery to be manufactured.
【００１７】本発明の黒鉛粒子において、前記のような
特性を満たすものが得られれば、その製造法に特に制限
はない。次のような製造法により得られる黒鉛粒子は、
本発明の効果を奏することができる。少なくとも黒鉛化
可能な骨材又は黒鉛と黒鉛化可能なバインダを混合する
工程、前記工程で得られた混合物を５００〜１２００℃
で焼成する工程、前記工程で得られた焼成物を平均粒径
１０〜１００μｍに粉砕する工程、前記工程で得られた
粉砕物を２５００℃以上で黒鉛化する工程を有するこ
と。There is no particular limitation on the production method of the graphite particles of the present invention as long as they satisfy the above-mentioned characteristics. Graphite particles obtained by the following manufacturing method,
The effects of the present invention can be achieved. Mixing at least a graphitizable aggregate or graphite and a graphitizable binder, and subjecting the mixture obtained in the above step to 500 to 1200 ° C.
B), pulverizing the calcined product obtained in the above step to an average particle size of 10 to 100 μm, and graphitizing the pulverized product obtained in the above step at 2500 ° C. or more.
【００１８】本発明の製造法において、黒鉛化可能な骨
材又は黒鉛と、黒鉛化可能なバインダとを、混合するこ
とで、アスペクト比を小さくするができ、かつ偏平状の
粒子を複数集合又は結合させた黒鉛粒子を作製すること
が可能となる。その結果作製するリチウム二次電池の急
速充放電特性及びサイクル特性を向上させることができ
る。In the production method of the present invention, the aspect ratio can be reduced by mixing a graphitizable aggregate or graphite and a graphitizable binder, and a plurality of flat particles are aggregated or formed. It becomes possible to produce bonded graphite particles. As a result, rapid charge / discharge characteristics and cycle characteristics of the manufactured lithium secondary battery can be improved.
【００１９】黒鉛化可能な骨材としては、例えばコーク
ス粉末、樹脂炭化物粉等が挙げられ、充放電容量及び急
速充放電特性の点で、コークス粉末が好ましく、ニード
ルコークス粉末であればより好ましい。また、骨材は、
充放電容量及び急速充放電特性の点で、平均粒径が１〜
８０μｍの粉末が好ましく、１〜６０μｍであればより
好ましく、５〜４０μｍであればさらに好ましい。Examples of the graphitizable aggregate include coke powder and resin carbide powder. Coke powder is preferable in terms of charge / discharge capacity and rapid charge / discharge characteristics, and needle coke powder is more preferable. Also, the aggregate is
In terms of charge / discharge capacity and rapid charge / discharge characteristics, the average particle size is 1 to
A powder of 80 μm is preferred, more preferably 1 to 60 μm, even more preferably 5 to 40 μm.
【００２０】黒鉛化可能なバインダとしては、ピッチ、
タールの他、熱硬化性樹脂、熱可塑性樹脂等の有機系材
料があげられる。黒鉛化可能なバインダの添加量として
は、使用するバインダの残炭率及び結着力によって異な
るが、例えば、前記黒鉛化可能な骨材又は黒鉛１００重
量部に対して１０〜１００重量部が好ましく、１０〜７
０重量部であればより好ましく、１０〜５０重量部であ
ればさらに好ましい。The binders that can be graphitized include pitch,
In addition to tar, organic materials such as thermosetting resins and thermoplastic resins can be used. The amount of the graphitizable binder to be added depends on the residual carbon ratio and the binding force of the binder used, but is preferably, for example, 10 to 100 parts by weight based on 100 parts by weight of the graphitizable aggregate or graphite, 10-7
0 parts by weight is more preferable, and 10 to 50 parts by weight is further preferable.
【００２１】また、黒鉛化可能な骨材と黒鉛化可能なバ
インダを混合する際に、黒鉛化触媒を添加してもよい。
黒鉛化触媒を添加することで得られる黒鉛粒子の結晶が
発達しやすくなり得られるリチウム二次電池の放電容量
を向上させることができる。黒鉛化触媒としては、Ｔ
ｉ、Ｓｉ、Ｆｅ、Ｎｉ、Ｂ等の金属又はこれらの金属の
酸化物若しくは炭化物が好ましい。黒鉛化触媒は、骨材
とバインダを混合する際に添加し、同時に混合すること
が好ましい。黒鉛化触媒を添加する場合、その量は、全
成分の配合量に対して１０重量％以下が好ましく、５重
量％以下であればより好ましい。黒鉛化触媒の添加量が
増えると、放電容量が増加させることができる反面、比
表面積が大きく且つかさ密度が低下する問題がある。When the graphitizable aggregate and the graphitizable binder are mixed, a graphitizing catalyst may be added.
By adding a graphitization catalyst, crystals of the graphite particles obtained can be easily developed, and the discharge capacity of the obtained lithium secondary battery can be improved. As a graphitization catalyst, T
Metals such as i, Si, Fe, Ni, and B, or oxides or carbides of these metals are preferred. The graphitization catalyst is preferably added when the aggregate and the binder are mixed, and mixed at the same time. When the graphitization catalyst is added, its amount is preferably 10% by weight or less, more preferably 5% by weight or less, based on the total amount of the components. When the amount of the graphitization catalyst is increased, the discharge capacity can be increased, but there is a problem that the specific surface area is large and the bulk density is reduced.
【００２２】混合する温度は、黒鉛化可能なバインダが
軟化溶融する温度であることが好ましく、その温度は使
用する材料によって異なるが、５０〜３５０℃の範囲が
好ましい。また、黒鉛化可能なバインダを溶剤等によっ
て、溶液にする場合には常温で混合してもよい。The mixing temperature is preferably the temperature at which the graphitizable binder softens and melts. The temperature varies depending on the material used, but is preferably in the range of 50 to 350 ° C. When a graphitizable binder is made into a solution with a solvent or the like, it may be mixed at room temperature.
【００２３】次いで黒鉛化可能な骨材と黒鉛化可能なバ
インダを混合した混合物は、５００〜２０００℃で焼成
し、さらに得られる焼成物を粉砕し、平均粒径を１０〜
１００μｍに調整し、さらに得られる粉砕物を２５００
℃以上の温度で黒鉛化することができる。粉砕前の焼成
温度は５００℃〜１５００℃が好ましく、７００〜１５
００℃であればより好ましい。粉砕前の焼成温度が２０
００℃を超えると、得られる黒鉛粒子のかさ密度が低
く、かつ比表面積が大きく、かつアスペクト比が大きく
なり、良好な特性が得られない問題がある。また粉砕前
の焼成温度が５００℃未満では、添加した黒鉛化可能な
バインダの炭素化が不十分となりやすく、その結果、粉
砕・黒鉛化後に粒子同士が結合してしまう問題がある。Next, the mixture obtained by mixing the graphitizable aggregate and the graphitizable binder is fired at 500 to 2000 ° C., and the obtained fired product is pulverized to have an average particle size of 10 to 10.
Adjusted to 100 μm, and the resulting pulverized material was 2500
It can be graphitized at a temperature of at least ℃. The sintering temperature before pulverization is preferably 500 ° C to 1500 ° C,
00 ° C. is more preferable. Firing temperature before grinding is 20
When the temperature exceeds 00 ° C., the obtained graphite particles have a low bulk density, a large specific surface area, and a large aspect ratio, and thus have a problem that good characteristics cannot be obtained. If the firing temperature before pulverization is lower than 500 ° C., carbonization of the added graphitizable binder tends to be insufficient, and as a result, there is a problem that particles are bonded after pulverization / graphitization.
【００２４】粉砕の方法としては、特に制限はなく、例
えば、ジェットミル、ハンマーミル、ピンミル等の衝撃
粉砕方式をとることができる。本発明では、黒鉛化前に
粉砕し粒度を調整し、黒鉛化後には粉砕を行わない方
が、比表面積、かさ密度、アスペクト比の点で好まし
い。粉砕粒子の平均粒径は、１０〜１００μｍの範囲で
あることが好ましく、１０〜８０μｍの範囲であればよ
り好ましく、１０〜５０μｍの範囲であればさらに好ま
しい。その理由は、前述の通りである。The method of pulverization is not particularly limited, and for example, an impact pulverization method such as a jet mill, a hammer mill, and a pin mill can be used. In the present invention, it is preferable in terms of specific surface area, bulk density and aspect ratio that pulverization is performed before graphitization to adjust the particle size and pulverization is not performed after graphitization. The average particle size of the pulverized particles is preferably in the range of 10 to 100 μm, more preferably in the range of 10 to 80 μm, and even more preferably in the range of 10 to 50 μm. The reason is as described above.
【００２５】黒鉛化の方法は特に制限はないが、例え
ば、自己揮発性ガス雰囲気、窒素雰囲気、アルゴン雰囲
気、真空中等で２５００℃以上の温度で行うことが得ら
れる黒鉛粒子の結晶性及び放電容量の点で好ましい。黒
鉛化温度は、２７００℃以上であればより好ましく、２
９００℃以上であればさらに好ましく、３０００℃以上
であれば特に好ましい。黒鉛化温度の上限としては３２
００℃以下であることが好ましい。The method of graphitization is not particularly limited. For example, the crystallinity and discharge capacity of graphite particles obtained at a temperature of 2500 ° C. or more in a self-volatile gas atmosphere, a nitrogen atmosphere, an argon atmosphere, a vacuum or the like can be used. It is preferred in terms of. The graphitization temperature is more preferably 2700 ° C. or more,
A temperature of 900 ° C or higher is more preferable, and a temperature of 3000 ° C or higher is particularly preferable. The upper limit of the graphitization temperature is 32
The temperature is preferably not higher than 00 ° C.
【００２６】以上の如く作製した黒鉛粒子は、負極に使
用することで、高容量で、サイクル特性、急速充放電特
性、安全性に優れたリチウム二次電池を作製することが
できる。本発明になる黒鉛粒子を負極にするには、有機
系結着剤及び溶剤と混練して、ペースト状にし、シート
状、ペレット状等の形状に成形される。有機系結着剤と
しては、例えば、ポリエチレン、ポリプロピレン、エチ
レンプロピレンターポリマー、ブタジエンゴム、スチレ
ンブタジエンゴム、ブチルゴム、イオン伝導率の大きな
高分子化合物等が使用できる。By using the graphite particles produced as described above for a negative electrode, a lithium secondary battery having high capacity, excellent cycle characteristics, rapid charge / discharge characteristics, and excellent safety can be produced. In order to make the graphite particles according to the present invention into a negative electrode, the graphite particles are kneaded with an organic binder and a solvent to form a paste, which is then shaped into a sheet, a pellet or the like. As the organic binder, for example, polyethylene, polypropylene, ethylene propylene terpolymer, butadiene rubber, styrene butadiene rubber, butyl rubber, a polymer compound having a high ionic conductivity, and the like can be used.
【００２７】前記イオン伝導率の大きな高分子化合物と
しては、ポリフッ化ビニリデン、ポリエチレンオキサイ
ド、ポリエピクロルヒドリン、ポリファスファゼン、ポ
リアクリロニトリル等が使用できる。黒鉛粒子と有機系
結着剤との混合比率は、黒鉛粒子１００重量部に対し
て、有機系結着剤を１〜２０重量部用いることが好まし
い。As the high molecular compound having a high ionic conductivity, polyvinylidene fluoride, polyethylene oxide, polyepichlorohydrin, polyphasphazene, polyacrylonitrile and the like can be used. The mixing ratio of the graphite particles to the organic binder is preferably 1 to 20 parts by weight of the organic binder with respect to 100 parts by weight of the graphite particles.
【００２８】溶剤としては、特に制限はなく、Ｎ−メチ
ル−２−ピロリドン、ジメチルホルムアミド、イソプロ
パノール等があげられる。溶剤の量も特に制限はなく、
黒鉛粒子は、有機系結着剤及び溶剤と混練し、粘度を調
整した後、集電体に塗布し、該集電体と一体化して負極
とされる。集電体としては、例えばニッケル、銅等の
箔、メッシュなどのの金属集電体が使用できる。なお一
体化は、例えばロール、プレス等の成形法で行うことが
でき、またこれらを組み合わせて一体化してもよい。The solvent is not particularly restricted but includes N-methyl-2-pyrrolidone, dimethylformamide, isopropanol and the like. There is no particular limitation on the amount of the solvent,
The graphite particles are kneaded with an organic binder and a solvent, and after adjusting the viscosity, applied to a current collector and integrated with the current collector to form a negative electrode. As the current collector, for example, a metal current collector such as a foil of nickel, copper or the like, or a mesh can be used. In addition, the integration can be performed by a molding method such as a roll, a press, or the like, and these may be combined and integrated.
【００２９】このようにして得られた負極は、リチウム
化合物を含む正極とともに、本発明のリチウム二次電池
に用いられる。リチウム二次電池は、例えば、正極と負
極をセパレータを介して対向して配置し、かつ電解液を
注入することにより得ることができ、これは従来の炭素
材料を負極に使用したリチウム二次電池に比較して、高
容量でサイクル特性、急速充放電特性に優れる。The negative electrode thus obtained is used together with the positive electrode containing a lithium compound in the lithium secondary battery of the present invention. A lithium secondary battery can be obtained, for example, by arranging a positive electrode and a negative electrode with a separator interposed therebetween, and injecting an electrolyte, which is a conventional lithium secondary battery using a carbon material for the negative electrode. As compared with, it has a high capacity and excellent cycle characteristics and rapid charge / discharge characteristics.
【００３０】本発明におけるリチウム二次電池の正極は
リチウム化合物を含むが、その材料に特に制限はなく、
例えばＬｉＮｉＯ2、ＬｉＣｏＯ2、ＬｉＭｎ2Ｏ4等を単
独又は混合して使用することができる。本発明における
リチウム二次電池は、正極及び負極とともに、通常リチ
ウム化合物を含む電解液を含む。電解液としては、Ｌｉ
ＣｌＯ4、ＬｉＰＦ6、ＬｉＡｓＦ、ＬｉＢＦ4、ＬｉＳ
Ｏ3ＣＦ4等のリチウム塩を、例えばエチレンカーボネー
ト、ジエチルカーボネート、ジメトキシエタン、ジメチ
ルカーボネート、メチルエチルカーボネート、メチルエ
チルカーボネート、テトラヒドロフラン等の非水系溶剤
に溶かしたいわゆる有機電解液や、固体若しくはゲル状
のいわゆるポリマー電解質を使用することができる。The positive electrode of the lithium secondary battery of the present invention contains a lithium compound, but the material is not particularly limited.
For example, LiNiO 2 , LiCoO 2 , LiMn 2 O 4 and the like can be used alone or in combination. The lithium secondary battery according to the present invention generally contains an electrolyte containing a lithium compound together with a positive electrode and a negative electrode. As the electrolyte, Li
ClO 4 , LiPF 6 , LiAsF, LiBF 4 , LiS
A so-called organic electrolytic solution in which a lithium salt such as O 3 CF 4 is dissolved in a non-aqueous solvent such as ethylene carbonate, diethyl carbonate, dimethoxyethane, dimethyl carbonate, methyl ethyl carbonate, methyl ethyl carbonate, tetrahydrofuran, etc .; So-called polymer electrolytes can be used.
【００３１】セパレータとしては、例えばポリエチレ
ン、ポリプロピレン等のポリオレフィンを主成分とした
不織布、クロス、微孔フィルム又はそれらを組み合わせ
たものを使用することができる。なお、作製するリチウ
ム二次電池の正極と負極が使用中も直接接触しない構造
にした場合は、セパレータを使用しなくとも良い。As the separator, for example, a nonwoven fabric, cloth, microporous film, or a combination thereof containing polyolefin such as polyethylene and polypropylene as a main component can be used. Note that when the positive electrode and the negative electrode of the lithium secondary battery to be manufactured do not directly contact during use, the separator may not be used.
【００３２】なお、図１に円筒型リチウム二次電池の一
例の一部断面正面図を示す。図１に示す円筒型リチウム
二次電池は、薄板状に加工された正極１と、同様に加工
された負極２がポリエチレン製微孔膜等のセパレータ３
を介して重ねあわせたものを捲回し、これを金属製等の
電池缶７に挿入し、密閉化されている。正極１は正極タ
ブ４を介して正極蓋６に接合され、負極２は負極タブ５
を介して電池底部へ接合されている。正極蓋６はガスケ
ット８にて電池缶（正極缶）７へ固定されている。FIG. 1 shows a partial cross-sectional front view of an example of a cylindrical lithium secondary battery. In the cylindrical lithium secondary battery shown in FIG. 1, a positive electrode 1 processed into a thin plate and a negative electrode 2 processed in the same manner are formed of a separator 3 such as a polyethylene microporous membrane.
Is wound up and inserted into a battery can 7 made of metal or the like to be sealed. The positive electrode 1 is joined to the positive electrode lid 6 via the positive electrode tab 4, and the negative electrode 2 is connected to the negative electrode tab 5.
To the bottom of the battery. The positive electrode lid 6 is fixed to a battery can (positive electrode can) 7 by a gasket 8.
【００３３】[0033]
【実施例】以下、本発明の実施例を説明する。 実施例１ 平均粒径２０μｍのニードルコークス粉末１００重量部
と、ピッチ１０重量部と、コールタール２０重量部を２
３０℃で１時間混合した。次いで、この混合物を１００
０℃で焼成した後、ピンミルで粉砕し、平均粒径が３８
μｍの粉末を作製した。この粉末をさらに３０００℃で
黒鉛化した後、目開き２００メッシュの篩いを通し、黒
鉛粒子を得た。得られた黒鉛粒子のかさ密度、平均粒
径、比表面積、ｄ（００２）、Ｌｃ（００２）、アスペ
クト比を表１に示す。また、得られた黒鉛粒子を電子顕
微鏡で観察した結果、偏平状の粒子が複数集合又は結合
した塊状の構造をしていた。Embodiments of the present invention will be described below. Example 1 100 parts by weight of needle coke powder having an average particle diameter of 20 μm, 10 parts by weight of pitch, and 20 parts by weight of coal tar
Mix at 30 ° C. for 1 hour. The mixture is then added to 100
After sintering at 0 ° C., the mixture is pulverized with a pin mill to have an average particle size of 38.
A μm powder was produced. This powder was further graphitized at 3000 ° C., and then passed through a sieve with openings of 200 mesh to obtain graphite particles. Table 1 shows the bulk density, average particle size, specific surface area, d (002), Lc (002), and aspect ratio of the obtained graphite particles. In addition, as a result of observing the obtained graphite particles with an electron microscope, it was found that a plurality of flat particles were aggregated or bonded, and had a massive structure.
【００３４】次いで、得られた黒鉛粒子を使用してリチ
ウム二次電池を作製した。図１に示した本発明のリチウ
ム二次電池を以下のようにして作製した。正極活物質と
してＬｉＣｏＯ2 ８８重量％を用いて、導電剤として
平均粒径２μｍの鱗片状黒鉛を７重量％、結着剤として
ポリフッ化ビニリデン（ＰＶＤＦ）５重量％添加して、
これにＮ−メチル−２−ピロリドンを加えて混合して正
極合剤のペーストを調整した。Next, a lithium secondary battery was manufactured using the obtained graphite particles. The lithium secondary battery of the present invention shown in FIG. 1 was manufactured as follows. Using 88% by weight of LiCoO 2 as a positive electrode active material, 7% by weight of flaky graphite having an average particle diameter of 2 μm as a conductive agent, and 5% by weight of polyvinylidene fluoride (PVDF) as a binder,
N-Methyl-2-pyrrolidone was added thereto and mixed to prepare a paste of the positive electrode mixture.
【００３５】同様に負極活物質として、前記の方法で作
製した黒鉛粒子に、結着剤としてＰＶＤＦを１０重量％
添加して、これにＮ−メチル−２−ピロリドンを加えて
混合して負極合剤のペーストを調整した。正極合剤を厚
み２５μｍのアルミニウム箔の両面に塗付し、その後１
２０℃で１時間真空乾燥した後、ロールプレスによって
電極を加圧成形し、さらに巾４０mm長さ２８５mmの大き
さに切り出して正極を作製した。但し、正極の両端の長
さ１０mmの部分は正極合剤が塗布されておらずアルミニ
ウム箔が露出しており、この一方に正極タブを超音波接
合によって圧着している。Similarly, as a negative electrode active material, 10% by weight of PVDF as a binder was added to the graphite particles produced by the above method.
N-methyl-2-pyrrolidone was added thereto and mixed to prepare a paste of the negative electrode mixture. A positive electrode mixture is applied to both sides of a 25-μm-thick aluminum foil.
After vacuum drying at 20 ° C. for 1 hour, the electrode was pressure-formed by a roll press, and cut into a size of 40 mm in width and 285 mm in length to produce a positive electrode. However, the positive electrode mixture was not applied to both ends of the positive electrode at a length of 10 mm, and the aluminum foil was exposed. A positive electrode tab was pressure-bonded to one of these parts by ultrasonic bonding.
【００３６】一方、負極合剤は厚み１０μｍの銅箔の両
面に塗布し、その後１２０℃で１時間真空乾燥した。真
空乾燥後、ロールプレスによって電極を加圧成形し、さ
らに巾４０mm長さ２９０mmの大きさに切り出して負極を
作製した。正極と同様に、負極の両端の長さ１０mmの部
分は負極合剤が塗布されておらず銅箔が露出しており、
この一方に負極タブを超音波接合によって圧着した。On the other hand, the negative electrode mixture was applied to both sides of a copper foil having a thickness of 10 μm, and then vacuum dried at 120 ° C. for 1 hour. After vacuum drying, the electrode was pressure-formed by a roll press, and cut into a size of 40 mm in width and 290 mm in length to produce a negative electrode. Like the positive electrode, the negative electrode mixture was not applied to the 10 mm long portions of both ends of the negative electrode, and the copper foil was exposed,
A negative electrode tab was pressure-bonded to one of the two by ultrasonic bonding.
【００３７】セパレータは、厚み２５μｍ巾４４mmのポ
リエチレン製の微孔膜を用いた。正極、セパレータ、負
極、セパレータの順で重ね合わせ、これを捲回して電極
群とした。これを単三サイズの電池缶に挿入して、負極
タブを缶底溶接し、正極蓋をかしめるための絞り部を設
けた。体積比が１：２のエチレンカーボネートとジメチ
ルカーボネートの混合溶媒に六フッ化リン酸リチウムを
１モル／リットル溶解させた電解液を電池缶に注入した
後、正極タブを正極蓋に溶接した後、正極蓋をかしめ付
けて電池を作製した。As the separator, a polyethylene microporous membrane having a thickness of 25 μm and a width of 44 mm was used. A positive electrode, a separator, a negative electrode, and a separator were superimposed in this order and wound to form an electrode group. This was inserted into an AA size battery can, the negative electrode tab was welded to the bottom of the can, and a throttle portion for caulking the positive electrode lid was provided. An electrolyte obtained by dissolving lithium hexafluorophosphate at 1 mol / liter in a mixed solvent of ethylene carbonate and dimethyl carbonate having a volume ratio of 1: 2 was injected into the battery can, and then the positive electrode tab was welded to the positive electrode cover. The battery was produced by caulking the positive electrode lid.
【００３８】この電池を用いて、充放電特性を評価し
た。作製したリチウム二次電池の充電条件は、電流３０
０mAで電池電圧４．２Ｖまで定電流で充電した後、電池
電圧４．２Ｖで電流が３０mAになるまで定電圧充電し
た。電流３００mAで電池電圧が２．８Ｖになるまで定電
流放電した時の放電容量を表２に示す。また、電流３０
０mAの時の放電容量に対し、電流９００mAで電池電圧が
２．８Ｖになるまで定電流放電した時の放電容量維持率
を表２に示す。また、電流３００mAで電池電圧４．２Ｖ
まで定電流で充電した後、電池電圧４．２Ｖで電流が３
０mAになるまで定電圧充電し、電流３００mAで電池電圧
が２．８Ｖになるまで定電流放電するサイクルを１００
回及び２００回繰り返した時の放電容量維持率を表２に
示す。また電流３００mAで電池電圧４．２Ｖまで定電流
で充電した後電池電圧４．２Ｖで電流が３０mAになるま
で定電圧充電し、電池を直径３mmの釘を差し、電池の状
態を観察し、安全性の評価をした。その結果を表２に示
す。Using this battery, the charge and discharge characteristics were evaluated. The charging condition of the manufactured lithium secondary battery is as follows.
After charging at 0 mA with a constant current to a battery voltage of 4.2 V, the battery was charged at a constant voltage of 4.2 V until the current reached 30 mA. Table 2 shows the discharge capacity when the battery was discharged at a constant current at a current of 300 mA until the battery voltage reached 2.8 V. In addition, current 30
Table 2 shows the discharge capacity retention ratio when the battery was discharged at a constant current until the battery voltage reached 2.8 V at a current of 900 mA with respect to the discharge capacity at 0 mA. At a current of 300 mA, the battery voltage is 4.2 V.
After charging the battery with a constant current up to
100 cycles of constant voltage charging until the current reaches 0 mA and constant current discharging until the battery voltage reaches 2.8 V at 300 mA.
Table 2 shows the discharge capacity retention ratio when the operation was repeated twice and 200 times. In addition, after charging the battery at a constant current up to a battery voltage of 4.2 V at a current of 300 mA, charging the battery at a constant voltage at a battery voltage of 4.2 V until the current becomes 30 mA, inserting a nail of 3 mm in diameter, observing the state of the battery, and safety. The sex was evaluated. Table 2 shows the results.
【００３９】比較例１ 平均粒径３５μｍのニードルコークス粉末を３０００℃
で黒鉛化して、黒鉛粒子を得た。実施例１と同様にリチ
ウム二次電池を作製し、充放電特性を評価した。得られ
た黒鉛粒子のかさ密度、平均粒径、比表面積、ｄ（００
２）、Ｌｃ（００２）、アスペクト比を表１に示す。ま
た、得られた黒鉛粒子を電子顕微鏡で観察した結果、鱗
状の粒子形状をしていた。また実施例１と同様の方法で
評価した充放電特性評価結果を表２に示す。Comparative Example 1 Needle coke powder having an average particle diameter of 35 μm was 3,000 ° C.
To obtain graphite particles. A lithium secondary battery was fabricated in the same manner as in Example 1, and the charge / discharge characteristics were evaluated. The bulk density, average particle size, specific surface area, d (00
Table 1 shows 2), Lc (002), and the aspect ratio. Observation of the obtained graphite particles with an electron microscope revealed that the graphite particles had a scale-like particle shape. Table 2 shows the results of the evaluation of the charge / discharge characteristics evaluated in the same manner as in Example 1.
【００４０】比較例２ メソフェーズピッチを平均粒径３２μｍに粉砕した後、
３００℃で酸化処理をした後、１０００℃で焼成した。
次いで、この粉末を３０００℃で黒鉛化した後、目開き
２００メッシュの篩いを通し、黒鉛粒子を得た。得られ
た黒鉛粒子のかさ密度、平均粒径、比表面積、ｄ（００
２）、Ｌｃ（００２）、アスペクト比を表１に示す。ま
た、得られた黒鉛粒子を電子顕微鏡で観察した結果、塊
状の粒子形状をしていた。また実施例１と同様の方法で
評価した充放電特性評価結果を表２に示す。Comparative Example 2 After the mesophase pitch was pulverized to an average particle size of 32 μm,
After oxidizing at 300 ° C., it was baked at 1000 ° C.
Next, the powder was graphitized at 3000 ° C., and then passed through a sieve having an opening of 200 mesh to obtain graphite particles. The bulk density, average particle size, specific surface area, d (00
Table 1 shows 2), Lc (002), and the aspect ratio. Observation of the obtained graphite particles with an electron microscope revealed that the graphite particles had a massive particle shape. Table 2 shows the results of the evaluation of the charge / discharge characteristics evaluated in the same manner as in Example 1.
【００４１】比較例３ 平均粒径２０μｍのニードルコークス粉末１００重量部
と、ピッチ１０重量部と、コールタール２０重量部を２
３０℃で１時間混合した。次いで、この混合物を粉砕、
成形して得た成形体を１０００℃で焼成した後、さらに
３０００℃で黒鉛化した。得られた黒鉛成形体を粉砕
し、目開き２００メッシュの篩いを通し、黒鉛粒子を得
た。得られた黒鉛粒子のかさ密度、平均粒径、比表面
積、ｄ（００２）、Ｌｃ（００２）、アスペクト比を表
１に示す。また、得られた黒鉛粒子を電子顕微鏡で観察
した結果、偏平状の粒子が複数集合又は結合した塊状の
構造をしていた。Comparative Example 3 100 parts by weight of needle coke powder having an average particle diameter of 20 μm, 10 parts by weight of pitch, and 20 parts by weight of coal tar
Mix at 30 ° C. for 1 hour. The mixture is then ground,
The molded body obtained by molding was fired at 1000 ° C. and then graphitized at 3000 ° C. The obtained graphite molded body was pulverized and passed through a sieve having openings of 200 mesh to obtain graphite particles. Table 1 shows the bulk density, average particle size, specific surface area, d (002), Lc (002), and aspect ratio of the obtained graphite particles. In addition, as a result of observing the obtained graphite particles with an electron microscope, it was found that a plurality of flat particles were aggregated or bonded, and had a massive structure.
【００４２】[0042]
【表１】 [Table 1]
【００４３】[0043]
【表２】 [Table 2]
【００４４】表２に示されるように、本発明の黒鉛粒子
は、高容量で、サイクル特性、急速充放電特性、安全性
に優れたリチウム二次電池として好適であることが示さ
れた。As shown in Table 2, it was shown that the graphite particles of the present invention were suitable as a lithium secondary battery having a high capacity, excellent cycle characteristics, rapid charge / discharge characteristics, and excellent safety.
【００４５】[0045]
【発明の効果】本発明の黒鉛粒子は、高容量で、サイク
ル特性、急速充放電特性、安全性に優れたリチウム二次
電池に好適なものである。また、本発明の製造法で作製
した黒鉛粒子は、高容量で、サイクル特性、急速充放電
特性安全性に優れたリチウム二次電池に好適なものであ
る。本発明のリチウム二次電池及びその負極は、高容量
で、サイクル特性、急速充放電特性、安全性に優れる。The graphite particles of the present invention are suitable for a lithium secondary battery having a high capacity, excellent cycle characteristics, rapid charge / discharge characteristics, and excellent safety. The graphite particles produced by the production method of the present invention are suitable for a lithium secondary battery having a high capacity, excellent cycle characteristics and rapid charge / discharge characteristics and safety. INDUSTRIAL APPLICABILITY The lithium secondary battery and the negative electrode of the present invention have high capacity, and are excellent in cycle characteristics, rapid charge / discharge characteristics, and safety.
【図１】本発明のリチウム二次電池の一例を示す概略図
である。FIG. 1 is a schematic view showing one example of a lithium secondary battery of the present invention.
１ 正極 ２ 負極 ３ セパレータ ４ 正極タブ ５ 負極タブ ６ 正極蓋 ７ 電池缶 ８ ガスケット DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 4 Positive electrode tab 5 Negative electrode tab 6 Positive electrode cover 7 Battery can 8 Gasket
───────────────────────────────────────────────────── フロントページの続き (72)発明者 村山 聡 茨城県日立市鮎川町三丁目３番１号 日立 化成工業株式会社山崎事業所内 (72)発明者 武井 康一 茨城県日立市鮎川町三丁目３番１号 日立 化成工業株式会社山崎事業所内 (72)発明者 藤田 淳 茨城県日立市鮎川町三丁目３番１号 日立 化成工業株式会社山崎事業所内 (72)発明者 山田 和夫 東京都港区芝浦四丁目９番25号 日立化成 工業株式会社内 Ｆターム(参考） 4G046 EA01 EA05 EB02 EC00 EC02 EC06 5H003 AA02 AA04 AA10 BA01 BA03 BB01 BC01 BC06 BD00 BD01 BD02 BD03 BD05 5H014 AA01 BB01 BB06 EE08 HH00 HH01 HH06 HH08 5H029 AJ03 AJ05 AJ12 AK03 AL06 AL07 AM03 AM04 AM05 AM07 BJ02 BJ14 CJ02 CJ08 CJ28 HJ01 HJ04 HJ05 HJ07 HJ08 HJ13 HJ14 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Satoshi Murayama 3-3-1 Ayukawacho, Hitachi City, Ibaraki Prefecture Inside the Hitachi Chemical Co., Ltd. Yamazaki Office (72) Inventor Koichi Takei 3-chome Ayukawacho, Hitachi City, Ibaraki Prefecture No.3-1 Hitachi Chemical Co., Ltd. Yamazaki Office (72) Inventor Jun Fujita 3-1-1 Ayukawacho, Hitachi City, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Yamazaki Office (72) Inventor Kazuo Yamada Minato-ku, Tokyo No. 9-25 Shibaura F-term in Hitachi Chemical Co., Ltd. (Reference) 4G046 EA01 EA05 EB02 EC00 EC02 EC06 5H003 AA02 AA04 AA10 BA01 BA03 BB01 BC01 BC06 BD00 BD01 BD02 BD03 BD05 5H014 AA01 BB01 BB06 EE08 HH00 HH5 H05HJH5H AJ05 AJ12 AK03 AL06 AL07 AM03 AM04 AM05 AM07 BJ02 BJ14 CJ02 CJ08 CJ28 HJ01 HJ04 HJ05 HJ07 HJ08 HJ13 HJ14
Claims (6)
クト比が１．１〜５、かさ密度が０．５g/cm3以上であ
り、偏平状の粒子を複数集合又は結合してなる形状を有
してなる黒鉛粒子。1. A plurality of flat particles having a specific surface area of 0.3 to 2.0 m 2 / g, an aspect ratio of 1.1 to 5 and a bulk density of 0.5 g / cm 3 or more, and Graphite particles having the following shape.
Å以下、Ｃ軸方向の結晶子サイズＬｃ（００２）が５０
０Å以上、平均粒径が１０〜１００μｍであ請求項１記
載の黒鉛粒子。2. An interlayer distance d (002) of a crystal is 3.38.
Å Hereinafter, the crystallite size Lc (002) in the C-axis direction is 50
The graphite particles according to claim 1, wherein the average particle size is 0 ° or more and 10 to 100 µm.
なバインダを混合する工程、前記工程で得られた混合物
を５００〜２０００℃で焼成する工程、前記工程で得ら
れた焼成物を平均粒径１０〜１００μｍに粉砕する工
程、前記工程で得られた粉砕物を２５００℃以上で黒鉛
化する工程を含んでなる黒鉛粒子の製造法。3. A step of mixing a graphitizable aggregate or graphite with a graphitizable binder, a step of firing the mixture obtained in the step at 500 to 2000 ° C., and a step of firing the fired product obtained in the step. A method for producing graphite particles, comprising a step of pulverizing to an average particle diameter of 10 to 100 μm and a step of graphitizing the pulverized product obtained in the above step at 2500 ° C. or higher.
０μｍのコークス粉末である請求項３記載の黒鉛粒子の
製造法。4. The graphitizable aggregate has an average particle size of 1 to 8.
The method for producing graphite particles according to claim 3, wherein the graphite particles are 0 µm coke powder.
請求項３若しくは４記載の製造法で製造した黒鉛粒子を
含有してなるリチウム二次電池用負極。5. A negative electrode for a lithium secondary battery comprising the graphite particles according to claim 1 or 2 or the graphite particles produced by the production method according to claim 3 or 4.
と、リチウム化合物を含む正極を有してなるリチウム二
次電池。6. A lithium secondary battery comprising the negative electrode for a lithium secondary battery according to claim 5, and a positive electrode containing a lithium compound.
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|---|---|---|---|
| JP26139099A JP2001089118A (en) | 1999-09-16 | 1999-09-16 | Graphite particle, method for producing the same, negative electrode for lithium secondary battery and lithium secondary battery |
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