JP2002083586A - Negative electrode for lithium secondary battery - Google Patents
Negative electrode for lithium secondary batteryInfo
- Publication number
- JP2002083586A JP2002083586A JP2001208317A JP2001208317A JP2002083586A JP 2002083586 A JP2002083586 A JP 2002083586A JP 2001208317 A JP2001208317 A JP 2001208317A JP 2001208317 A JP2001208317 A JP 2001208317A JP 2002083586 A JP2002083586 A JP 2002083586A
- 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.)
- Granted
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、新規な黒鉛粒子、
黒鉛粒子の製造法、黒鉛粒子を用いた黒鉛ペースト、リ
チウム二次電池負極及び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、急速充放電特性、サイクル特性
等に優れたリチウム二次電池とそれを得るための黒鉛粒
子、黒鉛粒子の製造法、黒鉛粒子を用いた黒鉛ペースト
及びリチウム二次電池負極に関する。The present invention relates to a novel graphite particle,
The present invention relates to a method for producing graphite particles, a graphite paste using the graphite particles, a negative electrode for a lithium secondary battery, and a lithium secondary battery. More specifically, portable equipment, electric vehicles, suitable for use in power storage, etc., rapid charge and discharge characteristics, lithium secondary batteries with excellent cycle characteristics and the like, and graphite particles for obtaining the same, a method for producing graphite particles, The present invention relates to a graphite paste using graphite particles and a negative electrode for a lithium secondary battery.
【０００２】[0002]
【従来の技術】従来黒鉛粒子は、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、溶剤を乾燥させて
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
よる内部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 graphite particles include, for example, natural graphite particles,
Examples include 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, the graphite paste is applied to the surface of a copper foil, and the solvent is dried to be used as a negative electrode for a lithium secondary battery. . For example, as shown in JP-B-62-23433,
By using graphite for the negative electrode, the problem of internal short circuit due to lithium dendrite is eliminated, and the cycle characteristics are improved.
【０００３】しかしながら、黒鉛結晶が発達している天
然黒鉛粒子及びコークスを黒鉛化した人造黒鉛粒子は、
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。この鱗状の黒鉛粒子は、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、鱗状の黒鉛粒子が集電体の面方向に配向し、
その結果、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軸方向の歪み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ばかりで
なく、急速充放電特性が悪くなる傾向にある。さらに、
アスペクト比が大きい鱗状の黒鉛粒子は、比表面積が大
きいため場合によっては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いばかりでなく、集電
体との密着性が悪く、多くのバインダが必要となる問題
点がある。集電体との密着性が悪いと、集電効果が低下
し、放電容量、急速充放電特性、サイクル特性等が低下
する問題がある。そこで、リチウム二次電池の急速充放
電特性及びサイクル特性又は第一サイクル目の不可逆容
量が小さく、サイクル特性若しくは第一サイクル目の不
可逆容量が小さく、急速充放電特性及びサイクル特性が
向上できる黒鉛粒子が要求されている。[0003] However, natural graphite particles in which graphite crystals are developed and artificial graphite particles obtained by graphitizing coke are:
Since the bonding force between the layers of the crystal in the c-axis direction is weaker than the bonding in the plane direction of the crystal, the bonding between the graphite layers is broken by pulverization,
So-called graphite particles having a large aspect ratio are obtained. Since the scale-like graphite particles have a large aspect ratio, when the electrode is produced by kneading with a binder and applying the mixture to the current collector, the scale-like graphite particles are oriented in the plane direction of the current collector,
As a result, distortion in the c-axis direction caused by repeated occlusion and release of lithium into and from graphite crystals causes not only the problem of destruction of the inside of the electrode and the deterioration of cycle characteristics, but also the deterioration of rapid charge and discharge characteristics. It is in. further,
Scale-like graphite particles having a large aspect ratio not only have a large irreversible capacity in the first cycle of a lithium secondary battery obtained in some cases because of a large specific surface area, but also have poor adhesion with a current collector, and many There is a problem that requires a binder. If the adhesion to the current collector is poor, there is a problem that the current collecting effect is reduced and the discharge capacity, rapid charge / discharge characteristics, cycle characteristics, and the like are reduced. Therefore, graphite particles capable of improving the rapid charge / discharge characteristics and the cycle characteristics of the lithium secondary battery because the rapid charge / discharge characteristics and the cycle characteristics or the irreversible capacity in the first cycle are small, and the cycle characteristics or the irreversible capacity in the first cycle are small. Is required.
【０００４】[0004]
【発明が解決しようとする課題】請求項１〜５に記載の
発明は、急速充放電特性及びサイクル特性に優れたリチ
ウム二次電池に好適な黒鉛粒子を提供するものである。
請求項６及び７に記載の発明は、第一サイクル日の不可
逆容量が小さく、サイクル特性に優れたリチウム二次電
池に好適な黒鉛粒子を提供するものである。請求項８及
び９に記載の発明は、第一サイクル目の不可逆容量が小
さく、急速充放電特性及びサイクル特性に優れたリチウ
ム電池に好適な黒鉛粒子を提供するものである。The first to fifth aspects of the present invention provide graphite particles suitable for a lithium secondary battery having excellent rapid charge / discharge characteristics and cycle characteristics.
The invention according to claims 6 and 7 provides graphite particles suitable for a lithium secondary battery having a small irreversible capacity on the first cycle day and excellent cycle characteristics. The inventions according to claims 8 and 9 provide graphite particles suitable for lithium batteries having a small irreversible capacity in the first cycle and excellent in rapid charge / discharge characteristics and cycle characteristics.
【０００５】請求項１０記載の発明は、急速充放電特性
及びサイクル特性に優れ又は第一サイクル目の不可逆容
量が小さく、サイクル特性に優れ若しくは第一サイクル
目の不可逆容量が小さく、急速充放電特性及びサイクル
特性に優れたリチウム二次電池に好適な黒鉛粒子の製造
法を提供するものである。請求項１１記載の発明は、急
速充放電特性及びサイクル特性に優れ又は第一サイクル
目の不可逆容量が小さく、サイクル特性に優れ若しくは
第一サイクル目の不可逆容量が小さく、急速充放電特性
及びサイクル特性に優れたリチウム二次電池に好適な黒
鉛ペーストを提供するものである。According to the tenth aspect of the present invention, the rapid charge / discharge characteristics and the cycle characteristics are excellent or the irreversible capacity in the first cycle is small, and the cycle characteristics are excellent or the irreversible capacity in the first cycle is small. Another object of the present invention is to provide a method for producing graphite particles suitable for a lithium secondary battery having excellent cycle characteristics. The invention according to claim 11 is excellent in rapid charge / discharge characteristics and cycle characteristics or has small irreversible capacity in the first cycle, excellent cycle characteristics or small irreversible capacity in the first cycle, and has rapid charge / discharge characteristics and cycle characteristics. It is intended to provide a graphite paste suitable for a lithium secondary battery excellent in excellentness.
【０００６】請求項１２記載の発明は、急速充放電特性
及びサイクル特性に優れ又は第一サイクル目の不可逆容
量が小さく、サイクル特性に優れ若しくは第一サイクル
目の不可逆容量が小さく、急速充放電特性及びサイクル
特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。請求項１３記載の発明は、急速充放電特性及びサ
イクル特性に優れ又は第一サイクル目の不可逆容量が小
さく、サイクル特性に優れ若しくは第一サイクル目の不
可逆容量が小さく、急速充放電特性及びサイクル特性に
優れたリチウム二次電池を提供するものである。According to a twelfth aspect of the present invention, the rapid charge / discharge characteristics and the cycle characteristics are excellent, or the irreversible capacity in the first cycle is small, and the cycle characteristics are excellent or the irreversible capacity in the first cycle is small. And a negative electrode for a lithium secondary battery having excellent cycle characteristics. The invention according to claim 13 is excellent in rapid charge / discharge characteristics and cycle characteristics or has a small irreversible capacity in the first cycle, excellent cycle characteristics or small irreversible capacity in the first cycle, and has rapid charge / discharge characteristics and cycle characteristics. It is intended to provide a lithium secondary battery having excellent characteristics.
【０００７】[0007]
【発明を解決するための手段】本発明は、扁平状の粒子
を複数、配向面が非平行となるように集合又は結合させ
てなる黒鉛粒子に関する。また、本発明は、前記黒鉛粒
子が、アスペクト比が５以下である黒鉛粒子に関する。
また、本発明は、前記黒鉛粒子が黒鉛粒子の集合体から
なる黒鉛粒子に関する。また、本発明は黒鉛粒子のアス
ペクト比が5以下である黒鉛粒子に関する。また、本発
明は、前記黒鉛粒子のアスペクト比が１．２〜５である
黒鉛粒子に関する。また、本発明は、比表面積が８ｍ2
／ｇ以下である黒鉛粒子に関する。また、本発明は、前
記比表面積が２〜５ｍ2／ｇである黒鉛粒子に関する。
また本発明は、前記黒鉛粒子が扁平状の粒子を複数、配
向面が非平行となるように集合又は結合させてなる黒鉛
粒子に関する。また本発明は、前記黒鉛粒子のアスペク
ト比が５以下である黒鉛粒子に関する。SUMMARY OF THE INVENTION The present invention relates to graphite particles obtained by assembling or bonding a plurality of flat particles so that their orientation planes are non-parallel. The present invention also relates to the graphite particles, wherein the graphite particles have an aspect ratio of 5 or less.
Further, the present invention relates to graphite particles, wherein the graphite particles are made of an aggregate of graphite particles. The present invention also relates to graphite particles having an aspect ratio of 5 or less. Further, the present invention relates to graphite particles, wherein the graphite particles have an aspect ratio of 1.2 to 5. Further, the present invention has a specific surface area of 8 m 2.
/ G or less. The present invention also relates to graphite particles having the specific surface area of 2 to 5 m 2 / g.
The present invention also relates to graphite particles obtained by assembling or bonding a plurality of flat graphite particles so that the orientation planes thereof are non-parallel. The present invention also relates to graphite particles having an aspect ratio of 5 or less.
【０００８】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に黒鉛化触媒を１〜５０重量
％添加して混合し、焼成した後粉砕することを特徹とす
る黒鉛粒子の製造法に関する。また、本発明は、前記の
いずれかの黒鉛粒子若しくは上記の方法で製造された黒
鉛粒子に有機系結着剤及び溶剤を添加し、混合してなる
黒鉛ペーストに関する。また、本発明は、上記の黒鉛ペ
ーストを集電体に塗布、一体化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、上記のリチウム
二次電池用負極と正極とをセパレータを介して対向して
配置し、かつその周辺に電解液が注入されたリチウム二
次電池に関する。Further, the present invention is characterized in that 1 to 50% by weight of a graphitizing catalyst is added to a graphitizable aggregate or graphite and a graphitizable binder, mixed, calcined, and ground. The present invention relates to a method for producing graphite particles. Further, the present invention relates to a graphite paste obtained by adding an organic binder and a solvent to any one of the above graphite particles or the graphite particles produced by the above method, and mixing them. The present invention also relates to a negative electrode for a lithium secondary battery obtained by applying the above graphite paste to a current collector and integrating the same. Furthermore, the present invention relates to a lithium secondary battery in which the above-described negative electrode for a lithium secondary battery and a positive electrode are arranged to face each other with a separator interposed therebetween, and an electrolyte is injected around the lithium secondary battery.
【０００９】[0009]
【発明の実施の形態】本発明の黒鉛粒子は、その特徴か
ら大きく３つに分けられる。本発明の第１の黒鉛粒子
は、扁平状の粒子を複数、配向面が非平行となるように
集合又は結合させたものである。本発明において、扁平
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。黒鉛
粒子において、複数の扁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扁平した面、
換言すれば最も平らに近い面を配向面として、複数の扁
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。BEST MODE FOR CARRYING OUT THE INVENTION The graphite particles of the present invention are roughly classified into three types according to their characteristics. The first graphite particles of the present invention are obtained by assembling or bonding a plurality of flat particles so that their orientation planes are non-parallel. 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 orientation plane of the plurality of flat particles is non-parallel, the flat surface having in the shape of each particle,
In other words, it refers to a state in which a plurality of flat particles assemble without aligning the respective orientation planes in a certain direction, with the plane closest to the plane being the orientation plane.
【００１０】この黒鉛粒子において扁平状の粒子は集合
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質を介して、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
化学的に結合してはないが、その形状等に起因して、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。１つの
黒鉛粒子において、扁平状の粒子の集合又は結合する数
としては、３個以上であることが好ましい。個々の扁平
状の粒子の大きさとしては、粒径で１〜１００μｍであ
ることが好ましく、これらが集合又は結合した黒鉛粒子
の平均粒径の２／３以下であることが好ましい。[0010] In the graphite particles, the flat particles are aggregated or bonded, and the bonding means that the particles are tar,
Through a carbonaceous material obtained by carbonizing a binder such as pitch, it refers to a state in which the particles are chemically bonded to each other. A state in which the shape of the aggregate is maintained. From the viewpoint of mechanical strength, it is preferable to combine them. In one graphite particle, the number of flat particles aggregated or bonded is preferably three or more. The size of each of the flat particles is preferably 1 to 100 μm in particle size, and is preferably 2/3 or less of the average particle size of the aggregated or bonded graphite particles.
【００１１】該黒鉛粒子を負極に使用すると、集電体上
に黒鉛結晶が配向し難く、負極黒鉛にリチウムを吸蔵・
放出し易くなるため、得られ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。なお、図１に本発明の黒鉛粒子の一例の粒子構造の
走査型電子顕微鏡写真を示す。図１において、（ａ）は
本発明になる黒鉛粒子の外表面の走査型電子顕微鏡写
真、（ｂ）は黒鉛粒子の断面の走査型電子顕微鏡写真で
ある。（ａ）においては、細かな鱗片状の黒鉛粒子が数
多く、それらの粒子の配向面を非平行にして結合し、黒
鉛粒子を形成している様子が観察できる。When the graphite particles are used for a negative electrode, it is difficult for graphite crystals to be oriented on a current collector, and lithium is occluded in the negative electrode graphite.
Since the lithium secondary battery is easily released, the charge / discharge characteristics and the cycle characteristics of the obtained lithium secondary battery can be improved. FIG. 1 shows a scanning electron micrograph of the particle structure of one example of the graphite particles of the present invention. In FIG. 1, (a) is a scanning electron micrograph of the outer surface of the graphite particles according to the present invention, and (b) is a scanning electron micrograph of a cross section of the graphite particles. In (a), it can be observed that a number of fine flake-like graphite particles are formed, and the orientation planes of these particles are combined in a non-parallel manner to form graphite particles.
【００１２】本発明の第２の黒鉛粒子は、アスペクト比
が５以下であるものである。この黒鉛粒子は、集電体上
で粒子が配向し難い傾向があり、上記と同様にリチウム
を吸蔵・放出し易くなる。アスペクト比は１．２〜５で
あることが好ましい。アスペクト比が１．２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。同様の理由で、より好ましい範囲は１．３
以上である。一方、黒鉛粒子のアスペクト比の上限とし
ては、３以下であることがより好ましい。アスペクト比
がこれより大きくなると、急速充放電特性が低下し易く
なる傾向がある。従って、特に好ましいアスペクト比は
１．３〜３である。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１００個の黒鉛粒子を
選択し、Ａ／Ｂを測定し、その平均値をとったものであ
る。The second graphite particles of the present invention have an aspect ratio of 5 or less. These graphite particles have a tendency that the particles are hardly oriented on the current collector, and easily occlude and release lithium as described above. The aspect ratio is preferably from 1.2 to 5. If the aspect ratio is less than 1.2,
When the contact area between the particles decreases, the conductivity tends to decrease. For the same reason, a more preferable range is 1.3.
That is all. On the other hand, the upper limit of the aspect ratio of the graphite particles is more preferably 3 or less. When the aspect ratio is larger than this, the rapid charge / discharge characteristics tend to deteriorate. Therefore, a particularly preferable aspect ratio is 1.3 to 3. In addition, the aspect ratio, when the length in the major axis direction of the graphite particles is A, and the length in the minor axis direction is B,
It is represented by A / B. The aspect ratio in the present invention is obtained by magnifying graphite particles with a microscope, arbitrarily selecting 100 graphite particles, measuring A / B, and taking the average value.
【００１３】前記第１の黒鉛粒子においては、アスペク
ト比が５以下のものが好ましく、アスペクト比が１．２
〜５のものがより好ましく、１．３〜３のものがさらに
好ましい。また、前記第２の黒鉛粒子としては、より小
さい黒鉛粒子の集合体又は結合体であることが好まし
い。The first graphite particles preferably have an aspect ratio of 5 or less, and have an aspect ratio of 1.2 or less.
To 5, more preferably 1.3 to 3. Further, it is preferable that the second graphite particles are an aggregate or a combination of smaller graphite particles.
【００１４】本発明の第３の黒鉛粒子は、比表面積が８
ｍ2／ｇ以下のものである。比表面積は、好ましくは５
ｍ2／ｇ以下とされる。該黒鉛粒子を負極に使用する
と、得られ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、また、第一サイク
ル目の不可逆容量を小さくすることができる。比表面積
が、８ｍ2／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、エネルギ
ー密度が小さく、さらに負極を作製する際多くの結着剤
が必要になるという問題がある。得られるリチウム二次
電池の急速充放電特性、サイクル特性等がさらに良好な
点から、比表面積は、１．５〜５ｍ2／ｇであることが
好ましく、２〜５ｍ2／ｇであることがより好ましい。
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。第３の黒鉛粒子におい
ては、第１の黒鉛粒子のように扁平状の粒子を複数、配
向面が非平行となるように集合又は結合させた黒鉛粒子
であることが好ましく、また、第２の黒鉛粒子のように
アスペクト比が５以下のものが好ましく、アスペクト比
が１．２〜５のものがより好ましく、１．３〜３のもの
がさらに好ましい。The third graphite particles of the present invention have a specific surface area of 8
m 2 / g or less. The specific surface area is preferably 5
m 2 / g or less. When the graphite particles are used for a negative electrode, the obtained lithium secondary battery can have improved rapid charge / discharge characteristics and cycle characteristics, and can have a reduced irreversible capacity in the first cycle. When the specific surface area exceeds 8 m 2 / g, the irreversible capacity in the first cycle of the obtained lithium secondary battery increases, the energy density is low, and a large amount of a binder is required when producing a negative electrode. There is a problem. The specific surface area is preferably 1.5 to 5 m 2 / g, and more preferably 2 to 5 m 2 / g, from the viewpoint that the obtained lithium secondary battery has more favorable rapid charge / discharge characteristics and cycle characteristics. More preferred.
The specific surface area can be measured by a known method such as a BET method (nitrogen gas adsorption method). The third graphite particles are preferably graphite particles in which a plurality of flat particles, such as the first graphite particles, are aggregated or bonded so that the orientation planes thereof are non-parallel. As for graphite particles, those having an aspect ratio of 5 or less are preferable, those having an aspect ratio of 1.2 to 5 are more preferable, and those having an aspect ratio of 1.3 to 3 are still more preferable.
【００１５】さらに、本発明で用いる各黒鉛粒子のＸ線
広角回折における結晶の層間距離ｄ（００２）は３．３
８Å以下が好ましく、３．３７Å以下であることがより
好ましい。ｃ軸方向の結晶子の大きさＬｃ（００２）は
５００Å以上が好ましく、１０００Å以上であることが
より好ましい。結晶の層間距離ｄ（００２）が小さくな
るかｃ軸方向の結晶子の大きさＬｃ（００２）が大きく
なると、放電容量が大きくなる傾向があり、好ましい。Further, the interlayer distance d (002) of crystals of each graphite particle used in the present invention in X-ray wide angle diffraction is 3.3.
It is preferably 8 ° or less, more preferably 3.37 ° or less. The crystallite size Lc (002) in the c-axis direction is preferably 500 ° or more, more preferably 1000 ° or more. When the interlayer distance d (002) of the crystal is small or the crystallite size Lc (002) in the c-axis direction is large, the discharge capacity tends to be large, which is preferable.
【００１６】本発明の上記各黒鉛粒子の製造法に特に制
限はないが、黒鉛化可能な骨材又は黒鉛と黒鉛化可能な
バインダに黒鉛化触媒を１〜５０重量％添加して混合
し、焼成した後粉砕することにより得ることができる。
これにより、黒鉛化触媒の抜けた後に細孔が生成され、
本発明の黒鉛粒子の良好な特性を与える。また、上記各
黒鉛粒子は、黒鉛又は骨材とバインダとの混合方法、バ
インダ量等の混合割合の調整、焼成後の粉砕条件等を適
宜選択することにより調整することもできる。There is no particular limitation on the method for producing each of the above graphite particles of the present invention. However, 1 to 50% by weight of a graphitizing catalyst is added to a graphitizable aggregate or graphite and a graphitizable binder, and mixed. It can be obtained by crushing after firing.
Thereby, pores are generated after the graphitization catalyst escapes,
Provides good properties of the graphite particles of the present invention. The above graphite particles can also be adjusted by appropriately selecting the mixing method of the graphite or the aggregate and the binder, adjusting the mixing ratio such as the amount of the binder, and the pulverizing conditions after firing.
【００１７】黒鉛化可能な骨材としては、例えば、コー
クス粉末、樹脂の炭化物等が使用できるが、黒鉛化でき
る粉末材料であれば特に制限はない。中でも、ニードル
コークス等の黒鉛化しやすいコークス粉末が好ましい。
また黒鉛としては、例えば天然黒鉛粉末、人造黒鉛粉末
等が使用できるが粉末状であれば特に制限はない。黒鉛
化可能な骨材又は黒鉛の粒径は、本発明で作製する黒鉛
粒子の粒径より小さいことが好ましい。As the graphitizable aggregate, for example, coke powder, resin carbide and the like can be used, but there is no particular limitation as long as the material can be graphitized. Among them, coke powder such as needle coke which is easily graphitized is preferable.
As the graphite, for example, natural graphite powder, artificial graphite powder and the like can be used, but there is no particular limitation as long as the powder is in the form of powder. The particle size of the graphitizable aggregate or graphite is preferably smaller than the particle size of the graphite particles produced in the present invention.
【００１８】さらに黒鉛化触媒としては、例えば鉄、ニ
ッケル、チタン、ケイ素、硼素等の金属、これらの炭化
物、酸化物などの黒鉛化触媒が使用できる。これらの中
で、ケイ素または硼素の炭化物または酸化物が好まし
い。これらの黒鉛化触媒の添加量は、得られる黒鉛粒子
に対して好ましくは１〜５０重量％、より好ましくは５
〜４０重量％の範囲、さらに好ましくは５〜３０重量％
の範囲とされ、１重量％未満であると黒鉛粒子のアスペ
クト比及び比表面積が大きくなり黒鉛の結晶の発達が悪
くなる傾向にあり、一方５０重量％を超えると均一に混
合することが困難で作業性が悪くなる傾向にある。Further, as the graphitization catalyst, for example, metals such as iron, nickel, titanium, silicon and boron, and graphitization catalysts such as carbides and oxides thereof can be used. Of these, carbides or oxides of silicon or boron are preferred. The amount of the graphitization catalyst to be added is preferably 1 to 50% by weight, more preferably 5 to 50% by weight based on the obtained graphite particles.
-40% by weight, more preferably 5-30% by weight
If the content is less than 1% by weight, the aspect ratio and the specific surface area of the graphite particles tend to be large, and the development of graphite crystals tends to be poor. On the other hand, if it exceeds 50% by weight, it is difficult to mix them uniformly. Workability tends to deteriorate.
【００１９】バインダとしては、例えば、タール、ピッ
チの他、熱硬化性樹脂、熱可塑性樹脂等の有機系材料が
好ましい。バインダの配合量は、扁平状の黒鉛化可能な
骨材又は黒鉛に対し、５〜８０重量％添加することが好
ましく、１０〜８０重量％添加することがより好まし
く、１５〜８０重量％添加することがさらに好ましい。
バインダの量が多すぎたり少なすぎると、作製する黒鉛
粒子のアスペクト比及び比表面積が大きくなり易いとい
う傾向がある。黒鉛化可能な骨材又は黒鉛とバインダの
混合方法は、特に制限はなく、ニーダー等を用いて行わ
れるが、バインダの軟化点以上の温度で混合することが
好ましい。具体的にはバインダがピッチ、タール等の際
には、５０〜３００℃が好ましく、熱硬化性樹脂の場合
には、２０〜１００℃が好ましい。As the binder, for example, organic materials such as thermosetting resin and thermoplastic resin are preferable in addition to tar and pitch. The binder is preferably added in an amount of 5 to 80% by weight, more preferably 10 to 80% by weight, and more preferably 15 to 80% by weight, based on the flat graphitizable aggregate or graphite. Is more preferable.
If the amount of the binder is too large or too small, the graphite particles to be produced tend to have an increased aspect ratio and specific surface area. The method of mixing the graphitizable aggregate or graphite and the binder is not particularly limited, and is performed using a kneader or the like, but it is preferable to mix at a temperature equal to or higher than the softening point of the binder. Specifically, when the binder is pitch, tar or the like, the temperature is preferably 50 to 300 ° C, and when the binder is a thermosetting resin, the temperature is preferably 20 to 100 ° C.
【００２０】次に上記の混合物を焼成し、黒鉛化処理を
行う。なお、この処理の前に上記混合物を所定形状に成
形しても良い。さらに、成形後、黒鉛化前に粉砕し、粒
径を調整した後、黒鉛化を行っても良い。焼成は前記混
合物が酸化し難い条件で焼成することが好ましく、例え
ば窒素雰囲気中、アルゴンガス雰囲気中、真空中で焼成
する方法が挙げられる。黒鉛化の温度は、２０００℃以
上が好ましく、２５００℃以上であることがより好まし
く、２８００℃〜３２００℃であることがさらに好まし
い。黒鉛化の温度が低いと、黒鉛の結晶の発達が悪く、
放電容量が低くなる傾向があると共に添加した黒鉛化触
媒が作製する黒鉛粒子に残存し易くなる傾向がある。黒
鉛化触媒が、作製する黒鉛粒子中に残存すると、放電容
量が低下する。黒鉛化の温度が高すぎると、黒鉛が昇華
することがある。Next, the above mixture is fired and graphitized. The mixture may be formed into a predetermined shape before this treatment. Further, after the molding, it may be pulverized before graphitization, and after adjusting the particle size, graphitization may be performed. The firing is preferably performed under conditions in which the mixture is unlikely to be oxidized, for example, a method of firing in a nitrogen atmosphere, an argon gas atmosphere, or in a vacuum. The temperature of graphitization is preferably 2000 ° C. or higher, more preferably 2500 ° C. or higher, and further preferably 2800 ° C. to 3200 ° C. If the temperature of graphitization is low, the development of graphite crystals is poor,
The discharge capacity tends to decrease and the added graphitization catalyst tends to remain in the produced graphite particles. If the graphitization catalyst remains in the graphite particles to be produced, the discharge capacity decreases. If the graphitization temperature is too high, the graphite may sublime.
【００２１】次に、得られた黒鉛化物を粉砕することが
好ましい。黒鉛化物の粉砕方法は、特に制限はないが、
例えばジェットミル、振動ミル、ピンミル、ハンマーミ
ル等の既知の方法をとることができる。粉砕後の粒径
は、平均粒径が１〜１００μｍが好ましく、１０〜５０
μｍであることがより好ましい。平均粒径が大きくなり
すぎる場合は作製する電極の表面に凹凸ができ易くなる
傾向がある。なお、本発明において平均粒径は、レーザ
ー回折粒度分布計により測定することができる。Next, the obtained graphitized product is preferably pulverized. The method of pulverizing the graphitized material is not particularly limited,
For example, a known method such as a jet mill, a vibration mill, a pin mill, and a hammer mill can be used. The particle size after pulverization is preferably such that the average particle size is 1 to 100 μm,
More preferably, it is μm. If the average particle size is too large, the surface of the electrode to be produced tends to have irregularities. In the present invention, the average particle size can be measured by a laser diffraction particle size distribution meter.
【００２２】本発明は、上記に示す工程を経ることによ
り、扁平状の粒子を複数、配向面が非平行となるように
集合又は結合させることができ、またアスペクト比が５
以下の黒鉛粒子を得ることができ、さらに比表面積が８
ｍ2／ｇ以下の黒鉛粒子を得ることができる。According to the present invention, a plurality of flat particles can be aggregated or bonded so that their orientation planes are non-parallel, and the aspect ratio is 5 through the above-described steps.
The following graphite particles can be obtained, and the specific surface area is 8
Graphite particles of m 2 / g or less can be obtained.
【００２３】本発明の黒鉛ペーストは、前記黒鉛粒子、
有機系結着剤及び溶剤を含む材料を混合して作製され
る。有機系結着割としては、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。本発
明において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、ポリフォスファゼン、ポリア
クリロニトリル等が使用できる。これらの中では、イオ
ン伝導率の大きな高分子化合物が好ましく、ポリフッ化
ビニリデンが特に好ましい。The graphite paste of the present invention comprises the graphite particles,
It is produced by mixing a material containing an organic binder and a solvent. 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, or the like can be used. In the present invention, as the polymer compound having a large ionic conductivity, polyvinylidene fluoride, polyethylene oxide,
Polyepichlorohydrin, polyphosphazene, polyacrylonitrile and the like can be used. Among these, a polymer compound having a large ionic conductivity is preferable, and polyvinylidene fluoride is particularly preferable.
【００２４】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３〜１
０重量部用いることが好ましい。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用いられる。溶剤の量に特
に制限はなく、所望の粘度に調整できればよいが、黒鉛
ペーストに対して、３０〜７０重量％用いられることが
好ましい。The mixing ratio of the graphite particles and the organic binder is as follows:
The organic binder is 3-1 to 100 parts by weight of the graphite particles.
It is preferable to use 0 parts by weight. The solvent is not particularly limited, and N-methyl 2-pyrrolidone, dimethylformamide, isopropanol and the like are used. The amount of the solvent is not particularly limited as long as it can be adjusted to a desired viscosity, but is preferably used in an amount of 30 to 70% by weight based on the graphite paste.
【００２５】本発明のリチウムイオン電池用負極は、前
記の各黒鉛粒子を使用することを特徴とする。このリチ
ウムイオン電池用負極は、前記黒鉛ペーストを、シート
状、ペレット状等の形状に成形することにより得ること
ができる。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。この
ようにして得られた負極はセパレータを介して正極を対
向して配置し、かつ電解液を注入することにより、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、急速充放電特性及びサイクル特性に優れ、かつ不可
逆容量が小さいリチウム二次電池を作製することができ
る。The negative electrode for a lithium ion battery of the present invention is characterized by using each of the above graphite particles. This negative electrode for a lithium ion battery can be obtained by molding the graphite paste into a sheet shape, a pellet shape, or the like. As the current collector, for example, a metal current collector such as a foil of nickel or copper, 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. The negative electrode obtained in this way is arranged with the positive electrode facing the other with a separator interposed therebetween, and injected with an electrolytic solution, so that the negative electrode is rapidly charged as compared with a conventional lithium secondary battery using a carbon material for the negative electrode. A lithium secondary battery having excellent discharge characteristics and cycle characteristics and small irreversible capacity can be manufactured.
【００２６】本発明におけるリチウム二次電池の正極に
用いられる材料については特に制限はなく、ＬｉＮｉＯ
2、ＬｉＣｏＯ2、ＬｉＭｎ2Ｏ4等を単独又は混合して使
用することができる。電解液としては、ＬｉＣｌＯ4、
ＬｉＰＦ6、ＬｉＡｓＦ6、ＬｉＢＦ4、ＬｉＳＯ3ＣＦ3
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、テトラヒドロフラン、プロピレンカーボネート等
の非水系溶剤に溶解したいわゆる有機電解液を使用する
ことができる。There is no particular limitation on the material used for the positive electrode of the lithium secondary battery in the present invention.
2 , LiCoO 2 , LiMn 2 O 4, etc. can be used alone or as a mixture. LiClO 4 ,
LiPF 6 , LiAsF 6 , LiBF 4 , LiSO 3 CF 3
For example, a so-called organic electrolytic solution in which a lithium salt such as ethylene carbonate, diethyl carbonate, dimethoxyethane, dimethyl carbonate, tetrahydrofuran, and propylene carbonate are dissolved can be used.
【００２７】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、微孔フィルム又はこれらを組み合わせ
たものを使用することができる。なお、図２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２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を介して重ね合わせたものを捲回
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７へ固定され
ている。As the separator, for example, a nonwoven fabric, cloth, microporous film, or a combination thereof, containing a polyolefin such as polyethylene or polypropylene as a main component can be used. FIG. 2 shows a partial cross-sectional front view of an example of the cylindrical lithium secondary battery. The cylindrical lithium secondary battery shown in FIG. 2 is formed by winding a positive electrode 1 processed into a thin plate and a negative electrode 2 processed in the same manner with a separator 3 such as a polyethylene microporous membrane interposed therebetween. This is inserted into a battery can 7 made of metal or the like to be sealed. The positive electrode 1 is connected to a positive electrode cover 6 via a positive electrode tab 4, and the negative electrode 2 is connected to a battery bottom via a negative electrode tab 5. The positive electrode lid 6 is fixed to the battery can 7 with a gasket 8.
【００２８】[0028]
【実施例】以下、本発明の実施例を図面を引用し説明す
る。 実施例１ （１）黒鉛粒子の調整 平均粒径が１０μｍのコークス粉末７０重量部、タール
ピッチ２０重量部、酸化鉄１０重量部及びコールタール
２０重量部を混合し、１００℃で１時間撹拌した。次い
で、窒素雰囲気中で２８００℃で焼成したのち粉砕し、
平均粒径が２０μｍの黒鉛粒子を得た。得られた黒鉛粒
子の走査型電子顕微鏡写真（ＳＥＭ写真）によれば、こ
の黒鉛粒子は、扁平状の粒子が多数、配向面が非平行と
なるように集合又は結合した構造をしていた。得られた
黒鉛粒子を１００個任意に選び出し、アスペクト比の平
均値を測定した結果、１．８であった。また得られた黒
鉛粒子のＸ線広角回折による結晶の層間距離ｄ（００
２）は３．３６０Å及び結晶子の大きさＬｃ（００２）
１０００Å以上であった。さらにＢＥＴ法による比表面
積は３．５ｍ2／ｇであった。Embodiments of the present invention will be described below with reference to the drawings. Example 1 (1) Preparation of Graphite Particles 70 parts by weight of coke powder having an average particle diameter of 10 μm, 20 parts by weight of tar pitch, 10 parts by weight of iron oxide and 20 parts by weight of coal tar were mixed and stirred at 100 ° C. for 1 hour. . Then, after firing at 2800 ° C. in a nitrogen atmosphere, pulverization is performed,
Graphite particles having an average particle size of 20 μm were obtained. According to a scanning electron micrograph (SEM photograph) of the obtained graphite particles, the graphite particles had a structure in which a large number of flat particles were aggregated or bonded so that the orientation planes were non-parallel. As a result of arbitrarily selecting 100 obtained graphite particles and measuring the average value of the aspect ratio, it was 1.8. The interlayer distance d (00) of the obtained graphite particles by X-ray wide angle diffraction
2) is 3.360 ° and the crystallite size Lc (002)
It was 1000 mm or more. Further, the specific surface area by the BET method was 3.5 m 2 / g.
【００２９】（２）リチウム二次電池の作製 図２に示す形状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を８８重量
％、導電剤として平均粒径が１μｍの鱗片状天然黒鉛を
７重量％及び結着剤としてポリフッ化ビニリデン（ＰＶ
ＤＦ）を５重量％添加して、これにＮ−メチル−２−ピ
ロリドン（ペーストの５０重量％、以下の例でも同様の
割合を添加）を加え混合して正極合剤のペーストを調整
した。同様に負極活物質として（１）で得た黒鉛粉末９
０重量％及び結着剤としてＰＶＤＦを１０重量％添加し
て、これにＮ−メチル−２−ピロリドン（ペーストの５
０重量％、以下の例でも同様の割合を添加）を加え混合
して負極合剤のペーストを得た。(2) Production of Lithium Secondary Battery A lithium secondary battery having the shape shown in FIG. 2 was produced as follows. 88% by weight of LiCoO 2 as a positive electrode active material, 7% by weight of flaky natural graphite having an average particle diameter of 1 μm as a conductive agent, and polyvinylidene fluoride (PV) as a binder
DF) was added at 5% by weight, and N-methyl-2-pyrrolidone (50% by weight of the paste, the same proportion was added in the following examples) was added thereto and mixed to prepare a paste of the positive electrode mixture. Similarly, the graphite powder 9 obtained in (1) was used as a negative electrode active material.
0% by weight and 10% by weight of PVDF as a binder were added thereto, and N-methyl-2-pyrrolidone (5% of the paste) was added thereto.
0% by weight, and the same ratio was added in the following examples) to obtain a paste of the negative electrode mixture.
【００３０】次に正極合剤のペーストを厚みが２５μｍ
のアルミニウム箔の両面に塗布し、その後１２０℃で１
時間真空乾燥した。真空乾燥後、ローラープレスによっ
て電極を加圧成形して厚みを１９０μｍとした。単位面
積当りの正極合剤塗布量は４９ｍｇ／ｃｍ2であり、幅
が４０ｍｍで長さが２８５ｍｍの大きさに切り出して正
極１を作製した。但し、正極１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４を超音波接合によっ
て圧着している。Next, paste the paste of the positive electrode mixture to a thickness of 25 μm.
On both sides of aluminum foil
Vacuum dried for hours. After vacuum drying, the electrode was pressure-formed by a roller press to a thickness of 190 μm. The coated amount of the positive electrode mixture per unit area was 49 mg / cm 2 , and the width was 40 mm and the length was cut out to a size of 285 mm to prepare a positive electrode 1. However, the positive electrode mixture was not applied to both ends of the positive electrode 1 and the aluminum foil was exposed at the 10 mm length portions, and the positive electrode tab 4 was press-bonded to one side of the positive electrode 1 by ultrasonic bonding.
【００３１】一方、負極合剤のペーストを厚みが１０μ
ｍ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、ローラープレスによって電極を
加圧成形して厚みを１７５μｍとした。単位面積当りの
負極合剤塗布量は２０ｍｇ／ｃｍ2であり、幅が４０ｍ
ｍで長さが２９０ｍｍの大きさに切り出して負極２を作
製した。これを正極１と同様に、負極２の両端の長さ１
０ｍｍ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５を超音波接合によって
圧着した。On the other hand, the paste of the negative electrode mixture has a thickness of 10 μm.
m, and then vacuum dried at 120 ° C. for 1 hour. After vacuum drying, the electrode was pressure-formed by a roller press to a thickness of 175 μm. The applied amount of the negative electrode mixture per unit area was 20 mg / cm 2 , and the width was 40 m.
A negative electrode 2 was prepared by cutting the sample into a size having a length of 290 mm and a length of 290 mm. This is, like the positive electrode 1, the length of both ends of the negative electrode 2.
The portion of 0 mm was not coated with the negative electrode mixture and the copper foil was exposed, and the negative electrode tab 5 was press-bonded to one of the portions by ultrasonic bonding.
【００３２】セパレータ３は、厚みが２５μｍで幅が４
４ｍｍのポリエチレン製の微孔膜を用いた。次いで図２
に示すように正極１、セパレータ３、負極２及びセパレ
ータ３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７に挿入して、負極タブ
５を缶底溶接し、正極蓋６をかしめるための絞り部を設
けた。この後体積比で１：１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（図示せず）
を電池缶７に注入した後、正極タブ４を正極蓋６に溶接
した後、正極蓋６をかしめてリチウム二次電池を得た。
得られたリチウム二次電池を用いて、充放電電流３００
ｍＡ、充電終止電圧を４．１５Ｖ及び放電終止電圧２．
８Ｖで充放電を繰り返した。また、充放電電流を３００
ｍＡから９００ｍＡの範囲で変化させ、急速充放電も行
った。その結果を図３及び図４に示す。The separator 3 has a thickness of 25 μm and a width of 4 μm.
A 4 mm polyethylene microporous membrane was used. Then Figure 2
As shown in (1), the positive electrode 1, the separator 3, the negative electrode 2, and the separator 3 were superimposed in this order, and were wound to form an electrode group. This was inserted into an AA size battery can 7, the negative electrode tab 5 was welded to the bottom of the can, and a throttle portion for caulking the positive electrode lid 6 was provided. Thereafter, an electrolyte (not shown) in which lithium hexafluorophosphate is dissolved in a mixed solvent of ethylene carbonate and dimethyl carbonate at a volume ratio of 1: 1 by 1 mol / liter.
Was poured into the battery can 7, the positive electrode tab 4 was welded to the positive electrode cover 6, and then the positive electrode cover 6 was caulked to obtain a lithium secondary battery.
Using the obtained lithium secondary battery, a charge / discharge current of 300
mA, charge end voltage 4.15V and discharge end voltage 2.
Charge and discharge were repeated at 8V. In addition, charge / discharge current is 300
Rapid charging and discharging were also performed by changing the current in the range of mA to 900 mA. The results are shown in FIGS.
【００３３】実施例２ 平均粒径が１０μｍのコークス粉末７０重量部、タール
ピッチ１０重量部、酸化鉄２重量部及びコールタール２
０重量部を混合し、１００℃で１時間撹拌した。次い
で、窒素雰囲気中で２８００℃で焼成したのち粉砕し、
平均粒径が２０μｍの黒鉛粒子を得た。電子顕微鏡で得
られた黒鉛粒子を観察した結果、扁平状の粒子が多数、
配向面が非平行となるように集合又は結合して形成され
た黒鉛粒子であることが確認された。得られた黒鉛粒子
を１００個任意に選び出し、アスペクト比の平均値を測
定した結果、４．８であった。また得られた黒鉛粒子の
Ｘ線広角回折による結晶の層間距離ｄ（００２）は３．
３６３Å及び結晶子の大きさＬｃ（００２）は１０００
Å以上であった。さらにＢＥＴ法による比表面積は４．
３ｍ2／ｇであった。得られた黒鉛粒子を実施例１と同
様の工程を経てリチウム二次電池を作製し、実施例１と
同様の電池特性試験を行った。その結果を図３及び図４
に示す。Example 2 70 parts by weight of coke powder having an average particle size of 10 μm, 10 parts by weight of tar pitch, 2 parts by weight of iron oxide and 2 parts of coal tar
0 parts by weight were mixed and stirred at 100 ° C. for 1 hour. Then, after firing at 2800 ° C. in a nitrogen atmosphere, pulverization is performed,
Graphite particles having an average particle size of 20 μm were obtained. As a result of observing the graphite particles obtained with an electron microscope, a large number of flat particles,
It was confirmed that the graphite particles were formed by assembling or bonding such that the orientation planes are non-parallel. As a result of arbitrarily selecting 100 obtained graphite particles and measuring the average value of the aspect ratio, it was 4.8. Further, the interlayer distance d (002) of the obtained graphite particles by X-ray wide-angle diffraction is 3.
363 ° and the crystallite size Lc (002) are 1000
It was more than Å. Further, the specific surface area by the BET method is 4.
It was 3 m 2 / g. Using the obtained graphite particles, a lithium secondary battery was manufactured through the same steps as in Example 1, and a battery characteristic test similar to that of Example 1 was performed. 3 and 4 show the results.
Shown in
【００３４】比較例１ 平均粒径が２０μｍのコークス粉末を窒素雰囲気中で２
８００℃で焼成し、平均粒径が２０μｍの黒鉛粒子を得
た。得られた黒鉛粒子は、アスペクト比の平均値が６、
比表面積は１１ｍ2／ｇ、結晶の層問距離ｄ（００２）
は３．３６５Å及び結晶子の大きさＬｃ（００２）は８
００Åの鱗状黒鉛であった。得られた鱗状黒鉛を実施例
１と同様の工程を経てリチウム二次電池を作製し、実施
例１と同様の電池特性試験を行った。その結果を図３及
び図４に示す。Comparative Example 1 Coke powder having an average particle size of 20 μm was placed in a nitrogen atmosphere.
It was fired at 800 ° C. to obtain graphite particles having an average particle size of 20 μm. The obtained graphite particles have an average aspect ratio of 6,
The specific surface area is 11 m 2 / g, and the crystal layer distance d (002)
Is 3.365 ° and the crystallite size Lc (002) is 8
It was a scaly graphite of 00 °. A lithium secondary battery was produced from the obtained flake graphite through the same steps as in Example 1, and a battery characteristic test similar to that of Example 1 was performed. The results are shown in FIGS.
【００３５】本発明の実施例１及び２と比較例１で得た
リチウム二次電池のリチウムの吸蔵・放出に関する比較
試験結果を下記に示す。図３は、リチウム二次電池の充
放電を繰り返し行った際の電池の放電容量と充放電サイ
クル回数の関係を示すグラフである。図３における９は
実施例１で得たリチウム二次電池の放電容量、１０は実
施例２で得たリチウム二次電池の放電容量及び１１は比
較例１で得たリチウム二次電池の放電容量を示す。The results of comparative tests on the insertion and extraction of lithium of the lithium secondary batteries obtained in Examples 1 and 2 of the present invention and Comparative Example 1 are shown below. FIG. 3 is a graph showing the relationship between the discharge capacity of the battery and the number of charge / discharge cycles when the charge / discharge of the lithium secondary battery is repeatedly performed. In FIG. 3, 9 is the discharge capacity of the lithium secondary battery obtained in Example 1, 10 is the discharge capacity of the lithium secondary battery obtained in Example 2, and 11 is the discharge capacity of the lithium secondary battery obtained in Comparative Example 1. Is shown.
【００３６】図３において実施例１で得たリチウム二次
電池の最高の放電容量は７５０ｍＡｈであり、５００サ
イクル目における放電容量の最高容量に対する容量低下
率は８％であった。実施例２で得たリチウム二次電池の
最高の放電容量は７２０ｍＡｈであり、５００サイクル
目における放電容量の最高容量に対する容量低下率は１
２％であった。また比較例で得たリチウム二次電池の最
高の放電容量は６５０ｍＡｈであり、５００サイクル目
における放電容量の最高容量に対する容量低下率は３１
％であった。In FIG. 3, the maximum discharge capacity of the lithium secondary battery obtained in Example 1 was 750 mAh, and the rate of decrease in the discharge capacity relative to the maximum capacity at the 500th cycle was 8%. The maximum discharge capacity of the lithium secondary battery obtained in Example 2 was 720 mAh, and the rate of decrease in discharge capacity relative to the maximum capacity at the 500th cycle was 1
2%. The maximum discharge capacity of the lithium secondary battery obtained in the comparative example was 650 mAh, and the capacity decrease rate of the discharge capacity at the 500th cycle with respect to the maximum capacity was 31.
%Met.
【００３７】さらに図４に急速充放電を行った場合の充
放電電流と放電容量の関係を示す。１２は実施例１で得
たリチウム二次電池の放電容量、１３は実施例２で得た
リチウム二次電池の放電容量及び１４は比較例１で得た
リチウム二次電池の放電容量を示す。充放電電流９００
ｍＡにおいて、実施例１で得たリチウム二次電池の放電
容量が６３０ｍＡｈ、実施例２で得たリチウム二次電池
の放電容量が５２０ｍＡｈであるのに対して、比較例１
で得たリチウム二次電池の放電容量は３５０ｍＡｈであ
った。これらの充放電電流３００ｍＡｈにおける放電容
量に対する容量低下率は、実施例１で得たリチウム二次
電池は１６％、実施例２で得たリチウム二次電池は２８
％及び比較例１で得たリチウム二次電池は４６％であっ
た。実施例１、２及び比較例１の試験結果により、本発
明の実施例になるリチウム二次電池は、高容量で、充放
電のサイクル特性に優れ、急速充放電特性を有すること
が確認された。FIG. 4 shows the relationship between the charge / discharge current and the discharge capacity when rapid charge / discharge is performed. 12 indicates the discharge capacity of the lithium secondary battery obtained in Example 1, 13 indicates the discharge capacity of the lithium secondary battery obtained in Example 2, and 14 indicates the discharge capacity of the lithium secondary battery obtained in Comparative Example 1. Charge / discharge current 900
In mA, the discharge capacity of the lithium secondary battery obtained in Example 1 was 630 mAh, and the discharge capacity of the lithium secondary battery obtained in Example 2 was 520 mAh, whereas the discharge capacity of Comparative Example 1 was 520 mAh.
The discharge capacity of the lithium secondary battery obtained in the above was 350 mAh. The capacity reduction rate with respect to the discharge capacity at a charge / discharge current of 300 mAh was 16% for the lithium secondary battery obtained in Example 1 and 28% for the lithium secondary battery obtained in Example 2.
% And the lithium secondary battery obtained in Comparative Example 1 was 46%. From the test results of Examples 1 and 2 and Comparative Example 1, it was confirmed that the lithium secondary batteries according to Examples of the present invention had high capacity, excellent charge / discharge cycle characteristics, and rapid charge / discharge characteristics. .
【００３８】実施例３ 平均粒径が１０μｍのコークス粉末５０重量部、タール
ピッチ２０重量部、炭化ケイ素１０重量部及びコールタ
ール２０重量部を混合し、１００℃で１時間撹拌した。
次いで、窒素雰囲気中で２８００℃で焼成した後粉砕
し、平均粒径が２０μｍの黒鉛粒子を作製した。得られ
た黒鉛粒子を１００個任意に選び出し、アスペクト比の
平均値を測定した結果、１．５であった。また得られた
黒鉛粒子のＢＥＴ法による比表面積は、２．９ｍ2／ｇ
であり、黒鉛粒子のＸ線広角回折による結晶の層間距離
ｄ（００２）は３．３６０Å及び結晶子の大きさＬｃ
（００２）は１０００Å以上であった。さらに得られた
黒鉛粒子の走査型電子顕微鏡写真（ＳＥＭ写真）によれ
ば、この黒鉛粒子は、扁平状の粒子が複数配向面が非平
行となるように集合又は結合した構造をしていた。Example 3 50 parts by weight of coke powder having an average particle diameter of 10 μm, 20 parts by weight of tar pitch, 10 parts by weight of silicon carbide and 20 parts by weight of coal tar were mixed and stirred at 100 ° C. for 1 hour.
Next, the powder was fired at 2800 ° C. in a nitrogen atmosphere and then pulverized to produce graphite particles having an average particle diameter of 20 μm. As a result of arbitrarily selecting 100 obtained graphite particles and measuring the average value of the aspect ratio, it was 1.5. The specific surface area of the obtained graphite particles measured by the BET method was 2.9 m 2 / g.
The interlayer distance d (002) of the crystal by the X-ray wide-angle diffraction of the graphite particles is 3.360 ° and the crystallite size Lc
(002) was 1000 ° or more. Further, according to a scanning electron micrograph (SEM photograph) of the obtained graphite particles, the graphite particles had a structure in which flat particles were aggregated or bonded such that a plurality of orientation planes became non-parallel.
【００３９】次いで得られた黒鉛粒子９０重量％にＮ−
メチル−２−ピロリドンに溶解したポリフッ化ビニリデ
ン（ＰＶＤＦ）を固形分で１０重量％加えて混練し、黒
鉛ペーストを得た。この黒鉛ペーストを厚さが１０μｍ
の圧延銅箔に塗布し、さらに乾燥して、面圧４９０ＭＰ
ａ（０．５トン／ｃｍ2）の圧力で圧縮成形し、試料電
極とした。黒鉛粒子層の厚さは７５μｍ及び密度は１．
５ｇ／ｃｍ3とした。Next, 90% by weight of the obtained graphite particles was
Polyvinylidene fluoride (PVDF) dissolved in methyl-2-pyrrolidone was added at a solid content of 10% by weight and kneaded to obtain a graphite paste. This graphite paste has a thickness of 10 μm.
Rolled copper foil, and further dried, with a surface pressure of 490MP
a (0.5 ton / cm 2 ) to obtain a sample electrode. The graphite particle layer has a thickness of 75 μm and a density of 1.
It was 5 g / cm 3 .
【００４０】作製した試料電極を３端子法による定電流
充放電を行い、リチウム二次電池用負極としての評価を
行った。図５はこのリチウム二次電池の概略図であり、
試料電極の評価は、図５に示すようにガラスセル１５
に、電解液１６としてＬｉＰＦ 4をエチレンカーボネー
ト（ＥＣ）及びジメチルカーボネート（ＤＭＣ）（ＥＣ
とＤＭＣは体積比で１：１）の混合溶媒に１モル／リッ
トルの濃度になるように溶解した溶液を入れ、試料電極
（負極）１７、セパレータ１８及び対極（正極）１９を
積層して配置し、さらに参照極２０を上部から吊るして
リチウム二次電池を作製して行った。なお、対極１９及
び参照極２０には金属リチウムを使用し、セパレータ１
８にはポリエチレン微孔膜を使用した。得られたリチウ
ム二次電池を用いて試料電極１７と対極１９の間に、試
料電極の面積に対して、０．３ｍＡ／ｃｍ2の定電流で
５ｍＶ（Ｖｖｓ．Ｌｉ／Ｌｉ+）まで充電し、１Ｖ（Ｖ
ｖｓ．Ｌｉ／Ｌｌ+）まで放電する試験を繰り返した。
表１に１サイクル目の黒鉛粒子の単位重量当りの充電容
量、黒鉛粒子の単位重量当りの放電容量、不可逆容量及
び５０サイクル目の黒鉛粒子の単位重量当りの放電容量
を示す。また、急速充放電特性評価として、０．３ｍＡ
／ｃｍ2の定電流で充電し、放電電流を０．３、２．
０、４．０及び６．０ｍＡ／ｃｍ2に変化させたときの
放電容量を表２に示す。The prepared sample electrode was subjected to a constant current by a three-terminal method.
Charge and discharge and evaluate as negative electrode for lithium secondary battery
went. FIG. 5 is a schematic diagram of the lithium secondary battery.
The evaluation of the sample electrode was performed using a glass cell 15 as shown in FIG.
And LiPF as the electrolyte 16 FourThe ethylene carbonate
(EC) and dimethyl carbonate (DMC) (EC
And DMC are mixed at 1 mol / l in a 1: 1) mixed solvent by volume.
Add the solution dissolved to the concentration of
(Negative electrode) 17, separator 18 and counter electrode (positive electrode) 19
Laminated and arranged, and further suspend the reference electrode 20 from above.
A lithium secondary battery was fabricated and performed. In addition, counter electrode 19 and
Lithium is used for the reference electrode 20 and the separator 1
8 used a polyethylene microporous membrane. Lichi obtained
Between the sample electrode 17 and the counter electrode 19 using a secondary battery.
0.3 mA / cm with respect to the area of the sample electrodeTwoAt a constant current of
5 mV (Vvs. Li / Li+) And 1V (V
vs. Li / Ll+) Was repeated.
Table 1 shows the charge capacity per unit weight of graphite particles in the first cycle.
Discharge capacity per unit weight of graphite particles, irreversible capacity and
Discharge capacity per unit weight of graphite particles at 50th and 50th cycles
Is shown. In addition, as a rapid charge / discharge characteristic evaluation, 0.3 mA
/ CmTwoAnd a discharge current of 0.3,2.
0, 4.0 and 6.0 mA / cmTwoWhen changed to
Table 2 shows the discharge capacity.
【００４１】実施例４ 平均粒径が１０μｍのコークス粉末５０重量部、タール
ピッチ１０重量部、炭化ケイ素５重量部及びコールター
ル１０重量部を混合し、１００℃で１時間撹拌した。次
いで、窒素雰囲気中で２８００℃で焼成した後粉砕し、
平均粒径が２０μｍの黒鉛粒子を作製した。得られた黒
鉛粒子を１００個任意に選び出し、アスペクト比の平均
値を測定した結果、４．５であった。また得られた黒鉛
粒子のＢＥＴ法による比表面積は、４．９ｍ2／ｇであ
り、黒鉛粒子のＸ線広角回折による結晶の層間距離ｄ
（００２）は３．３６２Å及び結晶子の大きさＬｃ（０
０２）は１０００Å以上であった。さらに得られた黒鉛
粒子は、扁平状の粒子が複数配向面が非平行となるよう
に集合又は結合した構造をしていた。Example 4 50 parts by weight of coke powder having an average particle diameter of 10 μm, 10 parts by weight of tar pitch, 5 parts by weight of silicon carbide and 10 parts by weight of coal tar were mixed and stirred at 100 ° C. for 1 hour. Then, after firing at 2800 ° C. in a nitrogen atmosphere, pulverization is performed,
Graphite particles having an average particle size of 20 μm were prepared. As a result of arbitrarily selecting 100 obtained graphite particles and measuring the average value of the aspect ratio, it was 4.5. The specific surface area of the obtained graphite particles by the BET method was 4.9 m 2 / g, and the interlayer distance d of the crystals of the graphite particles by X-ray wide-angle diffraction was determined.
(002) is 3.362 ° and the crystallite size Lc (0
02) was 1000 ° or more. Further, the obtained graphite particles had a structure in which flat particles were aggregated or bonded so that a plurality of orientation planes became non-parallel.
【００４２】以下実施例３と同様の工程を経てリチウム
二次電池を作製し、実施例３と同様の試験を行った。表
１に１サイクル目の黒鉛粒子の単位重量当りの充電容
量、黒鉛粒子の単位重量当りの放電容量、不可逆容量及
び５０サイクル目の黒鉛粒子の単位重量当りの放電容量
を示す。また急速充放電特性評価として、０．３ｍＡ／
ｃｍ2の定電流で充電し、放電電流を０．３、２．０、
４．０及び６．０ｍＡ／ｃｍ2に変化させたときの放電
容量を表２に示す。Thereafter, a lithium secondary battery was manufactured through the same steps as in Example 3, and the same test as in Example 3 was performed. Table 1 shows the charge capacity per unit weight of the graphite particles in the first cycle, the discharge capacity per unit weight of the graphite particles, the irreversible capacity, and the discharge capacity per unit weight of the graphite particles in the 50th cycle. In addition, as a quick charge / discharge characteristic evaluation, 0.3 mA /
The battery was charged at a constant current of 2 cm 2 and the discharge current was 0.3, 2.0,
Table 2 shows the discharge capacity when the discharge capacity was changed to 4.0 and 6.0 mA / cm 2 .
【００４３】実施例５ 平均粒径が１０μｍのコークス粉末５０重量部、タール
ピッチ５重量部及びコールタール５重量部を混合し、１
００℃で１時間撹拌した。次いで、窒素雰囲気中で２８
００℃で焼成した後粉砕し、平均粒径が２０μｍの黒鉛
粒子を作製した。得られた黒鉛粒子を１００個任意に選
び出し、アスペクト比の平均値を測定した結果、５であ
った。また得られた黒鉛粒子のＢＥＴ法による比表面積
は、６．３ｍ2／ｇであり、黒鉛粒子のＸ線広角回折に
よる結晶の層間距離ｄ（００２）は３．３６８Å及び結
晶子の大きさＬｃ（００２）は７００Åであった。さら
に得られた黒鉛粒子は、扁平状の粒子が複数、配向面が
非平行となるように集合又は結合した構造をしていた。Example 5 A mixture of 50 parts by weight of coke powder having an average particle diameter of 10 μm, 5 parts by weight of tar pitch and 5 parts by weight of coal tar was mixed.
Stirred at 00 ° C. for 1 hour. Then, in a nitrogen atmosphere, 28
After firing at 00 ° C., the powder was pulverized to produce graphite particles having an average particle diameter of 20 μm. As a result of arbitrarily selecting 100 obtained graphite particles and measuring the average value of the aspect ratio, it was 5. The specific surface area of the obtained graphite particles by the BET method was 6.3 m 2 / g, the interlayer distance d (002) of the graphite particles by X-ray wide-angle diffraction was 3.368 °, and the crystallite size Lc (002) was 700 °. Further, the obtained graphite particles had a structure in which a plurality of flat particles were aggregated or bonded so that the orientation planes were non-parallel.
【００４４】以下実施例３と同様の工程を経てリチウム
二次電池を作製し、実施例３と同様の試験を行った。表
１に１サイクル目の黒鉛粒子の単位重量当りの充電容
量、黒鉛粒子の単位重量当りの放電容量、不可逆容量及
び５０サイクル目の黒鉛粒子の単位重量当りの放電容量
を示す。また急速充放電特性評価として、０．３ｍＡ／
ｃｍ2の定電流で充電し、放電電流を０．３、２．０、
４．０及び６．０ｍＡ／ｃｍ2に変化させたときの放電
容量を表２に示す。Thereafter, a lithium secondary battery was manufactured through the same steps as in Example 3, and the same test as in Example 3 was performed. Table 1 shows the charge capacity per unit weight of the graphite particles in the first cycle, the discharge capacity per unit weight of the graphite particles, the irreversible capacity, and the discharge capacity per unit weight of the graphite particles in the 50th cycle. In addition, as a quick charge / discharge characteristic evaluation, 0.3 mA /
The battery was charged at a constant current of 2 cm 2 and the discharge current was 0.3, 2.0,
Table 2 shows the discharge capacity when the discharge capacity was changed to 4.0 and 6.0 mA / cm 2 .
【００４５】比較例２ 平均粒径が２２μｍのコークス粉末を窒素雰囲気中で２
８００℃で焼成して、平均粒径が２０μｍの黒鉛粒子を
得た。得られた黒鉛粒子は、アスペクト比の平均値が
７、ＢＥＴ法による比表面積が８．５ｍ2／ｇ、Ｘ線広
角回折による結晶の層間距離ｄ（００２）が３．３６８
Å及び結晶子の大きさＬｃ（００２）が８００Åの鱗状
の黒鉛であった。Comparative Example 2 Coke powder having an average particle size of 22 μm was mixed with nitrogen in a nitrogen atmosphere.
By firing at 800 ° C., graphite particles having an average particle size of 20 μm were obtained. The obtained graphite particles have an average aspect ratio of 7, a specific surface area of 8.5 m 2 / g by the BET method, and a crystal interlayer distance d (002) of 3.368 by wide-angle X-ray diffraction.
鱗 and the crystallite size Lc (002) were 800Å scale graphite.
【００４６】以下実施例３と同様の工程を経てリチウム
二次電池を作製し、実施例３と同様の試験を行った。表
１に１サイクル目の黒鉛粒子の単位重量当りの充電容
量、黒鉛粒子の単位重量当りの放電容量、不可逆容量及
び５０サイクル目の黒鉛粒子の単位重量当りの放電容量
を示す。また急速充放電特性評価として、０．３ｍＡ／
ｃｍ2の定電流で充電し、放電電流を０．３、２．０、
４．０及び６．０ｍＡ／ｃｍ2に変化させたときの放電
容量を表２に示す。A lithium secondary battery was manufactured through the same steps as in Example 3, and the same test as in Example 3 was performed. Table 1 shows the charge capacity per unit weight of the graphite particles in the first cycle, the discharge capacity per unit weight of the graphite particles, the irreversible capacity, and the discharge capacity per unit weight of the graphite particles in the 50th cycle. In addition, as a quick charge / discharge characteristic evaluation, 0.3 mA /
The battery was charged at a constant current of 2 cm 2 and the discharge current was 0.3, 2.0,
Table 2 shows the discharge capacity when the discharge capacity was changed to 4.0 and 6.0 mA / cm 2 .
【００４７】[0047]
【表１】 [Table 1]
【００４８】[0048]
【表２】 [Table 2]
【００４９】表１及び表２に示されるように、本発明の
実施例で得られたリチウム二次電池は放電容量が大き
く、第一サイクル目の不可逆容量が小さく、サイクル特
性及び急速放電特性に優れることが明らかである。As shown in Tables 1 and 2, the lithium secondary batteries obtained in Examples of the present invention have a large discharge capacity, a small irreversible capacity in the first cycle, and low cycle characteristics and rapid discharge characteristics. It is clear that it is excellent.
【００５０】[0050]
【発明の効果】請求項１〜５における黒鉛粒子は、急速
充放電特性及びサイクル特性に優れたリチウム二次電池
に好適な黒鉛粒子である。請求項６及び７における黒鉛
粒子は、第一サイクル目の不可逆容量が小さく、サイク
ル特性に優れたリチウム二次電池に好適な黒鉛粒子であ
る。請求項８及び９における黒鉛粒子は、急速充放電特
性及びサイクル特性に優れ又は第一サイクル目の不可逆
容量が小さく、サイクル特性に優れ若しくは第一サイク
ル目の不可逆容量が小さく、急速充放電特性及びサイク
ル特性に優れたリチウム二次電池に好適な黒鉛粒子であ
る。The graphite particles according to the first to fifth aspects are graphite particles suitable for a lithium secondary battery having excellent rapid charge / discharge characteristics and cycle characteristics. The graphite particles according to claims 6 and 7 have a small irreversible capacity in the first cycle and are suitable for lithium secondary batteries having excellent cycle characteristics. The graphite particles according to claims 8 and 9 have excellent rapid charge / discharge characteristics and cycle characteristics or a small irreversible capacity in the first cycle, and excellent cycle characteristics or small irreversible capacities in the first cycle. Graphite particles suitable for lithium secondary batteries having excellent cycle characteristics.
【００５１】請求項１０における方法により得られる黒
鉛粒子は、急速充放電特性及びサイクル特性に優れ又は
第一サイクル目の不可逆容量が小さく、サイクル特性に
優れ若しくは第一サイクル目の不可逆容量が小さく、急
速充放電特性及びサイクル特性に優れたリチウム二次電
池に好適な黒鉛粒子である。請求項１１における黒鉛ペ
ーストは、急速充放電特性及びサイクル特性に優れ又は
第一サイクル目の不可逆容量が小さく、サイクル特性に
優れ若しくは第一サイクル目の不可逆容量が小さく、急
速充放電特性及びサイクル特性に優れたリチウム二次電
池に好適な黒鉛ペーストである。The graphite particles obtained by the method according to claim 10 are excellent in rapid charge / discharge characteristics and cycle characteristics or small in irreversible capacity in the first cycle, excellent in cycle characteristics or small in irreversible capacity in the first cycle, Graphite particles suitable for lithium secondary batteries having excellent rapid charge / discharge characteristics and cycle characteristics. The graphite paste according to claim 11, which is excellent in rapid charge / discharge characteristics and cycle characteristics or has a small irreversible capacity in the first cycle, has excellent cycle characteristics or has a small irreversible capacity in the first cycle, and has rapid charge / discharge characteristics and cycle characteristics. It is a graphite paste suitable for a lithium secondary battery having excellent heat resistance.
【００５２】請求項１２におけるリチウム二次電池用負
極は、急速充放電特性及びサイクル特性に優れ又は第一
サイクル目の不可逆容量が小さく、サイクル特性に優れ
若しくは第一サイクル目の不可逆容量が小さく、急速充
放電特性及びサイクル特性に優れたリチウム二次電池に
好適なリチウム二次電池用負極である。請求項１３にお
けるリチウム二次電池は、急速充放電特性及びサイクル
特性に優れ又は第一サイクル目の不可逆容量が小さく、
サイクル特性に優れ若しくは第一サイクル目の不可逆容
量が小さく、急速充放電特性及びサイクル特性に優れる
リチウム二次電池である。The negative electrode for a lithium secondary battery according to claim 12 is excellent in rapid charge / discharge characteristics and cycle characteristics or has a small irreversible capacity in the first cycle, excellent cycle characteristics or a small irreversible capacity in the first cycle, It is a negative electrode for a lithium secondary battery suitable for a lithium secondary battery having excellent rapid charge / discharge characteristics and cycle characteristics. The lithium secondary battery according to claim 13 is excellent in rapid charge / discharge characteristics and cycle characteristics or has a small irreversible capacity in the first cycle,
The lithium secondary battery has excellent cycle characteristics or a small irreversible capacity in the first cycle, and has excellent rapid charge / discharge characteristics and cycle characteristics.
【図１】本発明になる黒鉛粒子の粒子構造を示す走査型
電子顕微鏡写真であり、（ａ）は粒子の外表面の写真、
（ｂ）は粒子の断面の写真である。FIG. 1 is a scanning electron micrograph showing the particle structure of graphite particles according to the present invention, wherein (a) is a photograph of the outer surface of the particles,
(B) is a photograph of a cross section of a particle.
【図２】円筒型リチウム二次電池の一部断面正面図であ
る。FIG. 2 is a partial cross-sectional front view of a cylindrical lithium secondary battery.
【図３】放電容量と充放電サイクル回数の関係を示すグ
ラフである。FIG. 3 is a graph showing a relationship between a discharge capacity and the number of charge / discharge cycles.
【図４】放電容量と充放電電流の関係を示すグラフであ
る。FIG. 4 is a graph showing a relationship between a discharge capacity and a charge / discharge current.
【図５】実施例３、４、５及び比較例２で、充放電特性
及び不可逆容量の測定に用いたリチウム二次電池の概略
図である。FIG. 5 is a schematic diagram of a lithium secondary battery used in Examples 3, 4, 5 and Comparative Example 2 for measuring charge / discharge characteristics and irreversible capacity.
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 ９ 実施例１で得たリチウム二次電池の放電容量 １０ 実施例２で得たリチウム二次電池の放電容量 １１ 比較例１で得たリチウム二次電池の放電容量 １２ 実施例１で得たリチウム二次電池の放電容量 １３ 実施例２で得たリチウム二次電池の放電容量 １４ 比較例１で得たリチウム二次電池の放電容量 １５ ガラスセル １６ 電解液 １７ 試料電極（負極） １８ セパレータ １９ 対極（正極） ２０ 参照極 Reference Signs List 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 9 discharge capacity of lithium secondary battery obtained in Example 1 10 discharge capacity of lithium secondary battery obtained in Example 2 11 Comparison Discharge capacity of lithium secondary battery obtained in Example 1 12 Discharge capacity of lithium secondary battery obtained in Example 1 13 Discharge capacity of lithium secondary battery obtained in Example 2 14 Lithium secondary obtained in Comparative Example 1 Battery discharge capacity 15 Glass cell 16 Electrolyte 17 Sample electrode (negative electrode) 18 Separator 19 Counter electrode (positive electrode) 20 Reference electrode
───────────────────────────────────────────────────── フロントページの続き (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工場内 (72)発明者 山田 和夫 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工場内 Ｆターム(参考） 4G046 EA01 EA02 EA03 EC01 EC05 EC06 5H029 AJ02 AJ05 AK03 AL07 AM02 AM03 AM04 AM07 CJ02 CJ08 CJ22 DJ08 DJ14 DJ16 DJ17 EJ12 HJ15 HJ17 5H050 AA02 AA07 BA17 CA07 CB08 DA11 EA24 FA13 FA17 FA19 GA02 GA05 GA10 GA22 HA05 HA07 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Atsushi Fujita 3-3-1, Ayukawacho, Hitachi City, Ibaraki Prefecture Inside the Yamazaki Plant of Hitachi Chemical Co., Ltd. (72) Kazuo Yamada 3-chome Ayukawacho, Hitachi City, Ibaraki Prefecture No. 1 F-term in Hitachi Chemical Co., Ltd. Yamazaki Factory (reference) 4G046 EA01 EA02 EA03 EC01 EC05 EC06 5H029 AJ02 AJ05 AK03 AL07 AM02 AM03 AM04 AM07 CJ02 CJ08 CJ22 DJ08 DJ14 DJ16 DJ17 EJ12 HJ15 HJ17 5H050 AA07 EA07 DA07 FA13 FA17 FA19 GA02 GA05 GA10 GA22 HA05 HA07
Claims (20)
なるように集合又は結合させてなる黒鉛粒子に、有機系
結着剤及び溶剤を添加し、混合してなる黒鉛ペーストを
集電体に塗布、一体化してなるリチウム二次電池用負
極。A graphite paste obtained by adding an organic binder and a solvent to graphite particles obtained by assembling or bonding a plurality of flat particles so that their orientation planes are non-parallel, and mixing them. A negative electrode for a lithium secondary battery, which is applied to and integrated with an electric body.
求項１記載のリチウム二次電池用負極。2. The negative electrode for a lithium secondary battery according to claim 1, wherein the graphite particles have pores.
請求項１又は２記載のリチウム二次電池用負極。3. The negative electrode for a lithium secondary battery according to claim 1, wherein the graphite particles have an aspect ratio of 5 or less.
ある請求項１、２又は３記載のリチウム二次電池用負
極。4. The negative electrode for a lithium secondary battery according to claim 1, wherein the specific surface area of the graphite particles is 8 m 2 / g or less.
する黒鉛粒子に、有機系結着剤及び溶剤を添加し、混合
してなる黒鉛ペーストを集電体に塗布、一体化してなる
リチウム二次電池用負極。5. A graphite obtained by adding an organic binder and a solvent to graphite particles having an aspect ratio of 5 or less and having pores, and applying and mixing a graphite paste to a current collector and integrating the graphite paste. Negative electrode for secondary battery.
を有する黒鉛粒子に、有機系結着剤及び溶剤を添加し、
混合してなる黒鉛ペーストを集電体に塗布、一体化して
なるリチウム二次電池用負極。6. An organic binder and a solvent are added to graphite particles having a specific surface area of 8 m 2 / g or less and having pores,
A negative electrode for a lithium secondary battery obtained by applying a graphite paste obtained by mixing to a current collector and integrating the same.
ム二次電池用負極と正極とをセパレータを介して対向し
て配置し、かつその周辺に電解液が注入されたリチウム
二次電池。7. A lithium secondary battery in which the negative electrode for a lithium secondary battery according to claim 1 and a positive electrode are arranged to face each other with a separator interposed therebetween, and an electrolyte is injected around the lithium secondary battery. .
なるように集合又は結合させてなるリチウム二次電池負
極用黒鉛粒子。8. Graphite particles for a negative electrode of a lithium secondary battery, wherein a plurality of flat particles are gathered or combined so that their orientation planes are non-parallel.
求項８記載のリチウム二次電池負極用黒鉛粒子。9. The graphite particles for a negative electrode of a lithium secondary battery according to claim 8, wherein the graphite particles have pores.
る平均粒径が１〜１００μｍであり、個々の扁平状の粒
子の大きさが、集合又は結合した黒鉛粒子の前記平均粒
径の２／３以下である請求項８又は９記載のリチウム二
次電池負極用黒鉛粒子。10. The average particle size measured by a laser diffraction particle size distribution analyzer is 1 to 100 μm, and the size of each flat particle is 2/3 of the average particle size of the aggregated or bonded graphite particles. The graphite particles for a negative electrode of a lithium secondary battery according to claim 8 or 9, wherein:
る請求項８、９又は１０記載のリチウム二次電池負極用
黒鉛粒子。11. The graphite particles for a negative electrode of a lithium secondary battery according to claim 8, wherein the graphite particles have an aspect ratio of 5 or less.
項１１記載のリチウム二次電池負極用黒鉛粒子。12. The graphite particles for a negative electrode of a lithium secondary battery according to claim 11, having an aspect ratio of 1.2 to 5.
項１１記載のリチウム二次電池負極用黒鉛粒子。13. The graphite particles for a negative electrode of a lithium secondary battery according to claim 11, wherein the graphite particles have an aspect ratio of 1.3 to 3.
項８〜１３のいずれかに記載のリチウム二次電池負極用
黒鉛粒子。14. The graphite particles for a negative electrode of a lithium secondary battery according to claim 8, having a specific surface area of 8 m 2 / g or less.
項８〜１４のいずれかに記載のリチウム二次電池負極用
黒鉛粒子。15. The graphite particles for a negative electrode of a lithium secondary battery according to claim 8, having a specific surface area of 2 to 5 m 2 / g.
有するリチウム二次電池負極用黒鉛粒子。16. Graphite particles for a lithium secondary battery negative electrode having an aspect ratio of 5 or less and having pores.
孔を有するリチウム二次電池負極用黒鉛粒子。17. Graphite particles for a negative electrode of a lithium secondary battery having a specific surface area of 8 m 2 / g or less and having pores.
黒鉛粒子の集合体からなるものである請求項１６又は１
７に記載のリチウム二次電池負極用黒鉛粒子。18. The graphite particles for a negative electrode of a lithium secondary battery,
17. An aggregate of graphite particles.
8. Graphite particles for a negative electrode of a lithium secondary battery according to 7.
能なバインダに黒鉛化触媒を１〜５０重量％添加して混
合し、焼成した後粉砕することを特徴とするリチウム二
次電池負極用黒鉛粒子の製造法。19. A negative electrode for a lithium secondary battery, comprising adding a graphitizing catalyst to a graphitizable aggregate or graphite and a graphitizable binder in an amount of 1 to 50% by weight, mixing, calcining and pulverizing. Method for producing graphite particles.
チウム二次電池負極用黒鉛粒子又は請求項１９に記載の
製造法で得られたリチウム二次電池負極用黒鉛粒子に有
機系結着剤及び溶剤を添加し、混合してなるリチウム二
次電池負極用黒鉛ペースト。20. An organic binder to the graphite particles for a negative electrode of a lithium secondary battery according to any one of claims 8 to 18 or the graphite particles for a negative electrode of a lithium secondary battery obtained by the production method according to claim 19. A graphite paste for a negative electrode of a lithium secondary battery obtained by adding and mixing an agent and a solvent.
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| JP20971396 | 1996-08-08 | ||
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| JP8-264265 | 1996-10-04 | ||
| JP2001208317A JP3325021B2 (en) | 1996-08-08 | 2001-07-09 | Graphite particles for negative electrode of lithium secondary battery and graphite paste for negative electrode of lithium secondary battery |
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