JPH0589879A - Lithium secondary battery - Google Patents

Lithium secondary battery

Info

Publication number
JPH0589879A
JPH0589879A JP4048329A JP4832992A JPH0589879A JP H0589879 A JPH0589879 A JP H0589879A JP 4048329 A JP4048329 A JP 4048329A JP 4832992 A JP4832992 A JP 4832992A JP H0589879 A JPH0589879 A JP H0589879A
Authority
JP
Japan
Prior art keywords
carbonaceous material
negative electrode
lithium
secondary battery
lithium secondary
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
Application number
JP4048329A
Other languages
Japanese (ja)
Other versions
JP3727666B2 (en
Inventor
Norio Takami
則雄 高見
Takahisa Osaki
隆久 大崎
Asako Satou
麻子 佐藤
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toshiba Corp
Original Assignee
Toshiba Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Toshiba Corp filed Critical Toshiba Corp
Priority to JP04832992A priority Critical patent/JP3727666B2/en
Publication of JPH0589879A publication Critical patent/JPH0589879A/en
Application granted granted Critical
Publication of JP3727666B2 publication Critical patent/JP3727666B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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

PURPOSE:To provide a lithium secondary battery equipped with a high capacity and with excellent cycle life by forming a negative electrode from a carbonaceous substance having a specific crystal structure and a specific peak in the differential. CONSTITUTION:A lithium secondary battery is provided with a positive electrode 4, a negative electrode 6 made of a carbonaceous substance occluding and releasing lithium ions, and a Li-ion conductive electrolyte. Therein the carbonaceous substance shall present a heat emission peak below 800 deg.C according to the differential thermal analysis, while an X-ray analysis shall indicate that the inter-plane distance (d002) of graphite structure (002) is below 0.370nm, the size (Lc) of crystallite in the C-axis direction is 4.0nm or less, and the absolute density is 1.7g/cm<3> or more. If the results from the differential thermal analysis meet the requirements, many lithium ions will be occluded in a fine structure of carbon, and the crystallite of size with the (d002) and (Lc) ranging as above allows occlusion and release of lithium ions easily.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、リチウム二次電池に関
し、特に負極を構成する炭素質物を改良し、優れた電池
特性を示すリチウム二次電池に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium secondary battery, and more particularly to a lithium secondary battery which has improved carbonaceous material constituting a negative electrode and exhibits excellent battery characteristics.

【０００２】[0002]

【従来の技術】近年、負極活物質としてリチウムを用い
た非水電解質電池は高エネルギー密度電池として注目さ
れており、正極活物質に二酸化マンガン（ＭｎＯ2 ）、
フッ化炭素［（ＣＦ2 ）］、塩化チオニル（ＳＯＣ
ｌ2 ）等を用いた一次電池は、既に電卓、時計の電源や
メモリのバックアップ電池として多用されている。2. Description of the Related Art In recent years, a non-aqueous electrolyte battery using lithium as a negative electrode active material has attracted attention as a high energy density battery, and manganese dioxide (MnO 2 ) is used as a positive electrode active material.
Fluorocarbon [(CF 2 )], thionyl chloride (SOC
Primary batteries using the l 2), etc., have already been widely used electronic calculator, as a backup battery power supply and memory clock.

【０００３】さらに、近年、ＶＴＲ，通信機器などの各
種の電子機器の小型、軽量化に伴いそれらの電源として
高エネルギー密度の二次電池の要求が高まったため、リ
チウムを負極活物質とするリチウム二次電池の研究が活
発に行われている。Furthermore, in recent years, with the miniaturization and weight reduction of various electronic devices such as VTRs and communication devices, there has been an increasing demand for secondary batteries having a high energy density as a power source for them. Research on secondary batteries is being actively conducted.

【０００４】リチウム二次電池は、負極にリチウムを用
い、リチウムイオン導電性電解質として炭酸プロピレン
（ＰＣ）、１，２−ジメトキシエタン（ＤＭＥ）、γ−
ブチロラクトン（γ−ＢＬ）、テトラヒドロフラン（Ｔ
ＨＦ）等の非水溶媒中にＬｉＣｌＯ4 、ＬｉＢＦ4 、Ｌ
ｉＡｓＦ6 等のリチウム塩を溶解した非水電解液やリチ
ウムイオン伝導性固体電解質から構成され、正極活物質
としては主にＴｉＳ2、ＭｏＳ2 、Ｖ2 Ｏ5 、Ｖ6 Ｏ13
等のリチウムとの間でトポケミカル反応する化合物が研
究されている。Lithium secondary batteries use lithium for the negative electrode and use propylene carbonate (PC), 1,2-dimethoxyethane (DME), γ- as lithium ion conductive electrolyte.
Butyrolactone (γ-BL), tetrahydrofuran (T
LiClO 4 , LiBF 4 , L in a non-aqueous solvent such as HF)
It is composed of a non-aqueous electrolytic solution in which a lithium salt such as iAsF 6 is dissolved or a lithium ion conductive solid electrolyte, and is mainly composed of TiS 2 , MoS 2 , V 2 O 5 , V 6 O 13 as a positive electrode active material.
Compounds that undergo a topochemical reaction with lithium, such as Al.

【０００５】しかしながら、上述した如くのリチウム二
次電池は、現在まだ実用化されていない。この主な理由
は、充放電効率が低く、しかも充放電回数（サイクル寿
命）が短いためである。この原因は、負極のリチウムと
非水電解液との反応によるリチウムの劣化によるところ
が大きいと考えられている。すなわち、放電時にリチウ
ムイオンとして非水電解液中に溶解したリチウムは、充
電時に析出する際に溶媒と反応し、その表面が一部不活
性化される。このため充放電を繰り返していくと、デン
ドライド状（樹枝状）や小球状にリチウムが析出し、さ
らにはリチウムが集電体より脱離するなどの現象が生じ
る。However, the lithium secondary battery as described above has not yet been put into practical use. The main reason for this is that the charge / discharge efficiency is low and the number of charge / discharge cycles (cycle life) is short. It is considered that this is largely due to the deterioration of lithium due to the reaction between the negative electrode lithium and the non-aqueous electrolyte. That is, the lithium dissolved in the non-aqueous electrolyte solution as lithium ions at the time of discharging reacts with the solvent at the time of depositing at the time of charging, and the surface thereof is partially inactivated. For this reason, when charging and discharging are repeated, lithium is deposited in a dendrite (dendritic) or small spherical shape, and further lithium is desorbed from the current collector.

【０００６】このようなことから、リチウム二次電池に
組み込まれる負極としてリチウムを吸蔵・放出する炭素
質物、例えばコークス、熱分解気相炭素などを用いるこ
とによって、リチウムと非水電解液との反応、さらには
デンドライド析出による負極特性の劣化を改善すること
が提案されている。しかしながら、係る負極はリチウム
イオンの吸蔵・放出量が少ないため、負極比容量（単位
はｍＡｈ／ｇまたはｍＡｈ／ｃｍ3 ）が小さいという問
題点があった。しかもリチウムイオンの吸蔵量を大きく
する（充電容量を大きくする）と、例えば炭素質物の結
晶構造が劣化したり、非水電解液中の溶媒を分解する等
の現象が生じる問題点があった。さらに、係る負極は充
電電流密度を高くすると、リチウムイオンの吸蔵量が低
下し、リチウム金属が析出するという問題点があった。
その結果、前記の如くの負極を組み込んだリチウム二次
電池の高容量化、サイクル寿命の長期化を達成すること
は困難であった。Therefore, by using a carbonaceous material that absorbs and releases lithium, such as coke and pyrolytic vapor-phase carbon, as a negative electrode incorporated in a lithium secondary battery, the reaction between lithium and the non-aqueous electrolyte solution is performed. Furthermore, it has been proposed to improve the deterioration of the negative electrode characteristics due to the deposition of dendrites. However, since such a negative electrode has a small amount of lithium ion absorption / desorption, the negative electrode specific capacity (unit: mAh / g or mAh / cm 3 ) Was small. Moreover, when the storage amount of lithium ions is increased (the charging capacity is increased), for example, the crystal structure of the carbonaceous material is deteriorated, and the solvent in the non-aqueous electrolyte is decomposed. Further, in such a negative electrode, when the charging current density is increased, the storage amount of lithium ions is reduced and lithium metal is deposited.
As a result, it has been difficult to achieve a high capacity and a long cycle life of the lithium secondary battery incorporating the negative electrode as described above.

【０００７】[0007]

【発明が解決しようとする課題】本発明は、上記の問題
点を解決するためになされたもので、負極に用いる炭素
質物を改良し、高容量でサイクル寿命の優れたリチウム
二次電池を提供するものである。The present invention has been made to solve the above problems, and provides a lithium secondary battery having a high capacity and an excellent cycle life by improving the carbonaceous material used for the negative electrode. To do.

【０００８】[0008]

【課題を解決するための手段および作用】本願の第１の
発明は、正極と、リチウムイオンを吸蔵・放出する炭素
質物からなる負極と、リチウムイオン伝導性電解質とを
備えたリチウム二次電池において、前記炭素質物が示差
熱分析で８００℃以下に発熱ピークを有し、Ｘ線回折に
おいて黒鉛構造の（００２）面の面間隔（ｄ002 ）が
０．３７０ｎｍ未満、Ｃ軸方向の結晶子の大きさ（Ｌ
ｃ）が４．０ｎｍ以下、真密度が１．７ｇ／ｃｍ3 以上
であることを特徴とするリチウム二次電池である。Means and Action for Solving the Problems The first invention of the present application is a lithium secondary battery comprising a positive electrode, a negative electrode made of a carbonaceous material that absorbs and releases lithium ions, and a lithium ion conductive electrolyte. The carbonaceous material has an exothermic peak at 800 ° C. or lower in differential thermal analysis, the (002) plane spacing (d 002 ) of the graphite structure in X-ray diffraction is less than 0.370 nm, and the crystallite of the C-axis direction is Size (L
c) is 4.0 nm or less and the true density is 1.7 g / cm 3. The lithium secondary battery is characterized by the above.

【０００９】本発明のリチウム二次電池に用いる炭素質
物は、六角網面構造（黒鉛構造）の炭素と、前記六角網
面構造の崩れた乱層構造の炭素からなる。空気中での示
差熱分析で発熱ピークが８００℃以下の値を示す炭素質
物は、炭素の微細組織にリチウムイオンが多く吸蔵する
性質を示す。これは、示差熱分析値が８００℃以下に発
熱ピークを示す炭素質物は、その炭素−炭素の原子間の
隙間がリチウムイオンが吸蔵・放出を行うのに十分な程
度に大きいからであると考えられる。逆に８００℃以下
に発熱ピークを有しない炭素質物は、電池に用いた場合
リチウムイオンの吸蔵・放出量が低下し、また、サイク
ル寿命が劣化する。好ましくは、６００℃〜７００℃の
範囲に前記発熱ピークを有する炭素質物であると良い。The carbonaceous material used in the lithium secondary battery of the present invention comprises carbon having a hexagonal network structure (graphite structure) and carbon having a disordered layer structure in which the hexagonal network structure is collapsed. A carbonaceous material showing an exothermic peak value of 800 ° C. or less in a differential thermal analysis in air has a property that a large amount of lithium ions are occluded in a fine structure of carbon. This is considered to be because the carbonaceous material whose differential thermal analysis value shows an exothermic peak at 800 ° C. or lower has a sufficiently large gap between the carbon-carbon atoms so that lithium ions can store and release lithium ions. Be done. On the other hand, a carbonaceous material having no exothermic peak at 800 ° C. or lower, when used in a battery, has a reduced lithium ion storage / release amount and a deteriorated cycle life. It is preferable that the carbonaceous material has the exothermic peak in the range of 600 ° C to 700 ° C.

【００１０】炭素質物の黒鉛構造を規定する指標として
は、Ｘ線回折により得られる（００２）面の面間隔（ｄ
002 ）、及びＣ軸方向の結晶子の大きさ（Ｌｃ）があ
る。前記負極材として適する炭素質物の黒鉛構造は、前
記面間隔（ｄ002 ）、が０．３７０ｎｍ未満、Ｃ軸方向
の結晶子の大きさ（Ｌｃ）が４．０ｎｍ以下とする。こ
の範囲であれば、リチウムイオンの吸蔵・放出が効果的
に増大でき、さらに真密度を高めることができる。具体
的に真密度の値は、１．７ｇ／ｃｍ2 以上である。真密
度の値が１．７ｇ／ｃｍ2 以上であるとリチウム二次電
池の比容量（ｍＡｈ／ｃｍ3 ）が増大できる。
（ｄ002 ）及び（Ｌｃ）の値が上記の範囲の炭素質物
は、結晶子の大きさが、リチウムイオンが容易に吸蔵・
放出できる大きさを有している。As an index for defining the graphite structure of the carbonaceous material, the interplanar spacing (d) of the (002) plane obtained by X-ray diffraction is used.
002 ), and the crystallite size (Lc) in the C-axis direction. The graphite structure of the carbonaceous material suitable as the negative electrode material has the above-mentioned interplanar spacing (d 002 ) of less than 0.370 nm and the crystallite size (Lc) in the C-axis direction of 4.0 nm or less. Within this range, the absorption / release of lithium ions can be effectively increased, and the true density can be further increased. Specifically, the value of true density is 1.7 g / cm 2 That is all. True density value is 1.7 g / cm 2 If it is above, the specific capacity of the lithium secondary battery (mAh / cm 3 ) Can be increased.
In the carbonaceous material in which the values of (d 002 ) and (Lc) are in the above ranges, the crystallite size is such that lithium ions easily occlude.
It has a size that can be released.

【００１１】このような（ｄ002 ）及び（Ｌｃ）の値が
前記範囲を逸脱すると前記炭素質物からなる負極のリチ
ウムイオンの吸蔵・放出量の減少、黒鉛構造の劣化及び
非水電解液中の溶媒の還元分解によるガス発生等を招
き、二次電池の容量減少とサイクル寿命の低下を生じる
恐れがある。より好ましい前記（ｄ002 ）及び（Ｌｃ）
の範囲は、（ｄ002 ）が０．３４５ｎｍ〜０．３７０ｎ
ｍ、（Ｌｃ）は２．５ｎｍ以下であると良い。さらに好
ましい（Ｌｃ）の値は１ｎｍ〜２．２ｎｍである。但
し、上記Ｘ線回折による（ｄ002 ）及び（Ｌｃ）は半価
幅中点法により求めた値である。以下、本明細書中の
（ｄ002 ）及び（Ｌｃ）は全て上記の方法により求めた
値である。When the values of (d 002 ) and (Lc) deviate from the above ranges, the amount of occlusion / release of lithium ions in the negative electrode composed of the carbonaceous material is reduced, the graphite structure is deteriorated, and the non-aqueous electrolyte solution contains This may lead to gas generation due to reductive decomposition of the solvent, resulting in a decrease in capacity of the secondary battery and a decrease in cycle life. More preferable (d 002 ) and (Lc)
The range of (d 002 ) is 0.345 nm to 0.370 n
m and (Lc) are preferably 2.5 nm or less. More preferable value of (Lc) is 1 nm to 2.2 nm. However, (d 002 ) and (Lc) by the above X-ray diffraction are values determined by the half-value width midpoint method. Hereinafter, (d 002 ) and (Lc) in the present specification are all values obtained by the above method.

【００１２】また、前記炭素質物を構成する黒鉛構造と
乱層構造の比率の尺度としては、アルゴンレーザ（波長
５１４．５ｎｍ）を光源として測定された炭素質物のラ
マンスペクトルがある。前記炭素質物について測定され
るラマンスペクトルには、１３６０ｃｍ-1付近に現れる
乱層構造に由来するピークと、１５８０ｃｍ-1付近に現
れる黒鉛構造に由来するピークとが存在する。そのピー
ク強度比、すなわち前記アルゴンレーザラマンスペクト
ル（波長５１４．５ｎｍ）における１５８０ｃｍ-1のピ
ーク強度（Ｒ２）に対する１３６０ｃｍ-1のピーク強度
（Ｒ１）の比（Ｒ１／Ｒ２）は、炭素質物の黒鉛構造と
乱層構造の比率の尺度となる。本願発明のリチウム二次
電池においては、前記の（Ｒ１／Ｒ２）の値が、０．９
より大きい炭素質物を用いることが好ましい。強度比
（Ｒ１／Ｒ２）がこの範囲である炭素質物は、リチウム
イオンを多量に吸蔵・放出できる乱層構造の割合が大き
く、結果として、負極容量は増大するためである。係る
強度比を０．９以下にすると、非水電解液中の溶媒の還
元分解によるガス発生が生じやすくなり、また前記炭素
質物からなる負極のリチウムイオンの吸蔵・放出量が低
下する恐れがある。さらに好ましい強度比（Ｒ１／Ｒ
２）は１．０〜２．０の範囲である。As a measure of the ratio of the graphite structure and the turbostratic structure constituting the carbonaceous material, there is a Raman spectrum of the carbonaceous material measured with an argon laser (wavelength 514.5 nm) as a light source. In the Raman spectrum measured for the carbonaceous material, there are peaks derived from the turbostratic structure appearing near 1360 cm −1 and peaks appearing near 1580 cm −1 derived from the graphite structure. The peak intensity ratio, i.e. the ratio of the argon laser Raman spectrum peak intensity of 1360 cm -1 to the peak intensity of 1580 cm -1 in (wavelength 514.5nm) (R2) (R1) (R1 / R2) is graphite structure carbonaceous material And the ratio of the turbostratic structure. In the lithium secondary battery of the present invention, the value of (R1 / R2) is 0.9
It is preferred to use a larger carbonaceous material. This is because the carbonaceous material having the strength ratio (R1 / R2) in this range has a large proportion of the disordered layer structure capable of absorbing and releasing a large amount of lithium ions, resulting in an increase in the negative electrode capacity. When the strength ratio is 0.9 or less, gas is likely to be generated due to the reductive decomposition of the solvent in the non-aqueous electrolyte solution, and the amount of occlusion / release of lithium ions in the negative electrode made of the carbonaceous material may decrease. .. More desirable strength ratio (R1 / R
2) is in the range of 1.0 to 2.0.

【００１３】また、前記炭素質物の形態としては、球
状、または粒状のものが挙げられる。特に、球状または
粒状の炭素質物の場合、粒径は０．５μｍから３０μｍ
の範囲に体積比率で９０％以上の粒度分布を有すること
が好ましい。上記の粒度分布を有する炭素質物はセパレ
ーターを通過する恐れがなく、且つ充填密度の高い負極
を作製することができる。さらに、１μｍから２０μｍ
の範囲に体積比率で９０％以上の粒度分布を有すると、
より好ましい。また、球状または粒状の炭素質物の場
合、平均粒径は２μｍから２０μｍの範囲であることが
好ましい。一般に炭素質物にはその微細組織が配向性を
有するものと配向性がランダムなものがあるが、本願発
明のリチウム二次電池においては、どちらでも良い。The form of the carbonaceous material may be spherical or granular. Especially in the case of spherical or granular carbonaceous material, the particle size is 0.5 μm to 30 μm.
It is preferable to have a particle size distribution of 90% or more in terms of volume ratio within the range. The carbonaceous material having the above particle size distribution does not have a risk of passing through the separator, and a negative electrode having a high packing density can be manufactured. Furthermore, 1 μm to 20 μm
When it has a particle size distribution of 90% or more by volume in the range of,
More preferable. In the case of spherical or granular carbonaceous material, the average particle size is preferably in the range of 2 μm to 20 μm. In general, carbonaceous materials include those having a fine structure having orientation and those having random orientation, but either of them may be used in the lithium secondary battery of the present invention.

【００１４】微細組織が配向性を有する球状または粒状
の炭素質物の配向、形態としては、図５のＡに示す放射
型、同図のＢに示すラメラ型、または同図のＣに示すラ
メラ（薄層）型と放射型とが複合されたブルックス−テ
ーラー型などにモデル化できる。なお、前記ブルックス
−テーラー型の定義については、「Ｃｈｅｍｉｃａｌ＆
Ｐｈｉｓｉｃｓ Ｃａｒｂｏｎ」Ｖｏｌ．１４，１９６
８，Ｐ２４８の文献、及び「Ｃａｒｂｏｎ」Ｖｏｌ．
３，１９６５，Ｐ１８５の文献にそれぞれ記載されてい
る。また、配向性が同心球状の炭素質物のも知られてい
る。As the orientation and morphology of a spherical or granular carbonaceous material having a fine texture, the radial type shown in FIG. 5A, the lamella type shown in FIG. 5B, or the lamella shown in C in FIG. It can be modeled as a Brooks-Taylor type in which a thin layer type and a radial type are combined. For the definition of the Brooks-Taylor type, see “Chemical &
Physics Carbon "Vol. 14,196
8, P248, and "Carbon" Vol.
3, 1965 and P185, respectively. Further, a carbonaceous material having a concentric spherical orientation is also known.

【００１５】また、例えば球の内部で放射状構造を有
し、かつ外部でランダム構造を有している炭素質物など
配向性を有する部分と配向性がランダムな部分とが混在
している炭素質物を用いても良い。Further, for example, a carbonaceous material such as a carbonaceous material having a radial structure inside a sphere and a random structure outside, a carbonaceous material in which a portion having orientation and a portion having random orientation are mixed. You may use.

【００１６】前記特性を有する炭素質物は、石油ピッ
チ、コールタールピッチ、原油分解ピッチ、有機樹脂、
合成高分子などを原料として不活性ガスの気流中または
真空中で焼成し、炭素化することにより得られる。The carbonaceous material having the above characteristics is petroleum pitch, coal tar pitch, crude oil cracking pitch, organic resin,
It is obtained by firing a synthetic polymer or the like as a raw material in a stream of an inert gas or in a vacuum to carbonize.

【００１７】特に石油ピッチ、石炭ピッチ、コールター
ル、重質油などを３５０℃〜４５０℃で熱処理すること
によって得られ、光学的異方性体として偏光顕微鏡下で
認識されるメソフェーズを高純度で含有するピッチ（メ
ソフェーズピッチまたはメソフェーズ小球体）、さらに
は、前記メソフェーズピッチを改質したネオメソフェー
ズピッチ、プリメソフェーズピッチ、及び潜在的異方性
ピッチなどメソフェーズピッチ系の原料を不活性ガスの
気流中または真空中において、６００℃以上１２００℃
以下の範囲で焼成したものを用いることにより容易に得
られる。より好ましい焼成温度は７５０℃〜１１００℃
の範囲である。焼成温度が６００℃以上１２００℃以下
の範囲を逸脱すると、負極の容量低下あるいはサイクル
劣化が生じる恐れがある。焼成時間は、１時間以上が望
ましく、より好ましくは２〜３０時間である。焼成時間
が１時間以下であると、負極の容量低下あるいはサイク
ル劣化が生じる恐れがある。Particularly, mesophase, which is obtained by heat-treating petroleum pitch, coal pitch, coal tar, heavy oil, etc. at 350 ° C. to 450 ° C. and is recognized as an optically anisotropic substance under a polarizing microscope, has high purity. The contained pitch (mesophase pitch or mesophase spherules), and further, the mesophase pitch-based raw materials such as neo-mesophase pitch, pre-mesophase pitch, and latently anisotropic pitch modified from the above mesophase pitch in an inert gas stream. Or 600 ° C or more in vacuum, 1200 ° C
It can be easily obtained by using one that is fired in the following range. More preferable firing temperature is 750 ° C to 1100 ° C.
The range is. If the firing temperature deviates from the range of 600 ° C. or more and 1200 ° C. or less, the capacity of the negative electrode may deteriorate or the cycle may deteriorate. The firing time is preferably 1 hour or more, more preferably 2 to 30 hours. If the firing time is 1 hour or less, the capacity of the negative electrode may be reduced or the cycle may be deteriorated.

【００１８】メソフェーズピッチ系の原料は、比較的低
温での焼成により、適度な黒鉛化度を示す炭素質物が得
られるので、製造上有利である。炭素質物の原料として
用いられる、メソフェーズピッチは、メソフェーズを９
５％以上の高純度に含有するピッチであることが好まし
い。メソフェーズピッチに含まれる不純物の多くは、主
に等方性ピッチである。メソフェーズピッチ中に含まれ
る等方性ピッチなどの不純物の含有率が高いと、焼成温
度を高くしなければ、得られる炭素質物の微細組織の配
向性を向上させることができない。しかしながら焼成温
度を高くすると黒鉛化度が高くなりリチウムイオンの吸
蔵・放出量は向上し難しくなる。好ましいメソフェーズ
ピッチの純度としては、９５％以上である。より好まし
いメソフェーズピッチの純度は９９〜１００％である。The mesophase pitch-based raw material is advantageous in production since a carbonaceous material having an appropriate degree of graphitization can be obtained by firing at a relatively low temperature. Mesophase pitch, which is used as a raw material for carbonaceous materials, is
The pitch is preferably contained in a high purity of 5% or more. Most of the impurities contained in the mesophase pitch are mainly isotropic pitch. If the content of impurities such as isotropic pitch contained in the mesophase pitch is high, the orientation of the fine structure of the obtained carbonaceous material cannot be improved unless the firing temperature is increased. However, if the firing temperature is raised, the degree of graphitization increases, and the amount of lithium ions stored and released increases, which becomes difficult. The preferred mesophase pitch purity is 95% or more. A more preferable mesophase pitch purity is 99 to 100%.

【００１９】また、本願の第２の発明は、正極と、リチ
ウムイオン吸蔵・放出する炭素質物からなる負極と、リ
チウムイオン伝導性電解質とを備えたリチウム二次電池
において、前記炭素質物が、示差熱分折で８００℃以下
に発熱ピークを有し、黒鉛構造の（００２）面の面間隔
（ｄ002 ）が０．３７０ｎｍ未満、Ｃ軸方向の結晶子の
大きさ（Ｌｃ）が４．０ｎｍ以下、引張強度が８００Ｍ
Ｐａ以上２５００ＭＰａ以下、引張弾性率が８０ＧＰａ
以上４５０ＧＰａ以下であることを特徴とするリチウム
二次電池である。前記炭素質物における示差分折は、前
述したのと同様である。The second invention of the present application is a lithium secondary battery comprising a positive electrode, a negative electrode made of a carbonaceous material which absorbs and releases lithium ions, and a lithium ion conductive electrolyte, wherein the carbonaceous material is a differential material. It has an exothermic peak at 800 ° C. or lower by thermal analysis, the (002) plane spacing (d 002 ) of the graphite structure is less than 0.370 nm, and the crystallite size (Lc) in the C-axis direction is 4.0 nm. Below, tensile strength is 800M
Pa or more and 2500 MPa or less, tensile elastic modulus of 80 GPa
The lithium secondary battery is 450 GPa or more and 450 GPa or less. The differential folding of the carbonaceous material is the same as described above.

【００２０】さらに、負極として適する炭素質物の黒鉛
構造は、前記面間隔（ｄ002 ）が０．３７０ｎｍ未満、
Ｃ軸方向の結晶子の大きさ（Ｌｃ）が４．０ｎｍ以下と
する。（ｄ002 ）が０．３７０ｎｍを越えると、炭素質
物のリチウムイオンを吸蔵・放出量が低下し、さらに真
密度が低下するため、それらにより電池の比容量（ｍＡ
ｈ／ｃｍ3 ）の低下を生じる恐がある。逆にこの範囲内
であると、結晶子の大きさがリチウムイオンの吸蔵・放
出が効果的に行われる大きさであり、また、（ｄ002 ）
が小さいため真密度を１．７ｇ／ｃｍ2 以上に高めるこ
とができる。それにより電池の比容量（ｍＡｈ／ｃ
ｍ3 ）が増大できる。好ましい範囲としては（ｄ002 ）
が０．３４８ｎｍ〜０．３６５ｎｍ、さらに好ましい範
囲としては、０．３４５ｎｍ〜０．３６５ｎｍである。
また好ましいＬｃの範囲は１ｎｍ〜２．５ｎｍである。Further, the graphite structure of the carbonaceous material suitable as the negative electrode has the above-mentioned interplanar spacing (d 002 ) of less than 0.370 nm,
The crystallite size (Lc) in the C-axis direction is 4.0 nm or less. If (d 002 ) exceeds 0.370 nm, the amount of lithium ions absorbed and released in the carbonaceous material is reduced, and the true density is further reduced.
h / cm 3 There is a fear of causing a decrease in. On the contrary, within this range, the crystallite size is a size at which lithium ions can be effectively absorbed and released, and (d 002 )
The true density is 1.7 g / cm 2 It can be increased to above. As a result, the specific capacity of the battery (mAh / c
m 3 ) Can be increased. The preferred range is (d 002 )
Is 0.348 nm to 0.365 nm, and a more preferable range is 0.345 nm to 0.365 nm.
The preferable range of Lc is 1 nm to 2.5 nm.

【００２１】炭素質物の機械的性質である引張強度と引
張弾性率は、リチウムイオンの可逆な吸蔵放出とそのサ
イクル寿命と関連している。本発明に係る二次電池に用
いる炭素質物としては引張強度が８００ＭＰａ以上２５
００ＭＰａ以下、引張弾性率が８０ＧＰａ以上４５０Ｇ
Ｐａの範囲の炭素質物を用いる。この範囲であると、リ
チウムイオンの吸蔵・放出に伴う炭素質物の構造の劣化
が抑制されてスムーズにリチウムイオンの吸蔵・放出が
できるため、充放電効率が高められ、かつサイクル寿命
を向上させることができる。この範囲と逸脱すると、リ
チウムイオンの吸蔵・放出量の低下あるいはサイクル寿
命の低下を生じる。より好ましい範囲としては、引張強
度は１２００ＭＰａ〜１８００ＭＰａ、引張弾性率は１
００ＧＰａ〜２００ＧＰａである。但し、上記の引張強
度及び引張弾性率の値は、炭素質物として繊維状の炭素
質物を用いた場合は、繊維軸方向に対する引張強度及び
引張弾性率を示すものとする。The mechanical properties of the carbonaceous material, that is, tensile strength and tensile modulus, are associated with reversible occlusion and release of lithium ions and their cycle life. The carbonaceous material used in the secondary battery according to the present invention has a tensile strength of 800 MPa or more and 25
00 MPa or less, tensile elastic modulus of 80 GPa or more and 450 G
A carbonaceous material in the range of Pa is used. Within this range, the deterioration of the carbonaceous material structure due to the absorption and desorption of lithium ions can be suppressed and the lithium ions can be smoothly absorbed and desorbed, so that the charge and discharge efficiency can be improved and the cycle life can be improved. You can If it deviates from this range, the amount of occlusion / release of lithium ions or the cycle life will decrease. As a more preferable range, the tensile strength is 1200 MPa to 1800 MPa, and the tensile elastic modulus is 1
It is 00 GPa to 200 GPa. However, when the fibrous carbonaceous material is used as the carbonaceous material, the above values of the tensile strength and the tensile elastic modulus indicate the tensile strength and the tensile elastic modulus in the fiber axis direction.

【００２２】一方、前記特性の他に黒鉛構造と乱層構造
の比率の尺度がアルゴンレーザ（波長５１４．５ｎｍ）
を光源として測定された１３６０ｃｍ-1のラマン強度Ｒ
１と１５８０ｃｍ-1のラマン強度Ｒ２の比（Ｒ１／Ｒ
２）で０．５〜１．５の範囲である炭素質物から負極を
形成することが好ましい。それによりリチウムイオンの
吸蔵・放出量をより一層増大でき、かつ充放電サイクル
時の構造の劣化を抑制でき、さらに非水電解液中の溶媒
の分解を防止でき好ましい。On the other hand, in addition to the above characteristics, the ratio of the graphite structure to the turbostratic structure is measured by an argon laser (wavelength 514.5 nm).
Raman intensity R of 1360 cm -1 measured with
Ratio of Raman intensity R2 of 1 and 1580 cm -1 (R1 / R
It is preferable to form the negative electrode from a carbonaceous material having a range of 0.5 to 1.5 in 2). This is preferable because the storage / release amount of lithium ions can be further increased, the structure deterioration during charge / discharge cycles can be suppressed, and the decomposition of the solvent in the non-aqueous electrolyte can be prevented.

【００２３】本願の第２の発明に係る炭素質物の形態と
して繊維状炭素質物が挙げられる。特に炭素質物として
炭素繊維を用いた場合、平均短径が１μｍ〜１００μ
ｍ、より好ましくは、２μｍ〜４０μｍの範囲になるよ
う粉砕して用いることが好ましい。同様に同炭素繊維の
平均長径も１μｍ〜１００μｍ、より好ましくは、２μ
ｍ〜４０μｍの範囲であることが好ましい。前記炭素質
物繊維の平均短径及び平均長径を１μｍ未満にすると、
炭素質物粒子がセパレータの孔を通り易くなり、正極と
負極の短絡を生じる恐れがあり、一方その平均短径及び
長径が１００μｍを越えると炭素質物粒子の比表面積が
小さくなってリチウムイオンの吸蔵・放出量を増大させ
ることが困難となる恐れがある。前記炭素繊維を粉砕す
る等の手段により平均粒径を前記範囲にすることも有効
である。さらに長径と短径は近い値であることが好まし
い。炭素繊維の長径の粒度分布は０．５μｍ〜５００μ
ｍの間に９０％以上の粒度分布を有することが好まし
い。より好ましくは、０．５μｍ〜７０μｍの間に９０
％以上の粒度分布を有することが望ましい。As a form of the carbonaceous material according to the second invention of the present application, a fibrous carbonaceous material can be mentioned. Especially when carbon fiber is used as the carbonaceous material, the average minor axis is 1 μm to 100 μm.
m, more preferably pulverized to a range of 2 μm to 40 μm before use. Similarly, the average major axis of the carbon fiber is also 1 μm to 100 μm, more preferably 2 μm.
It is preferably in the range of m to 40 μm. When the average minor axis and the average major axis of the carbonaceous material fiber are less than 1 μm,
The carbonaceous material particles may easily pass through the pores of the separator, which may cause a short circuit between the positive electrode and the negative electrode. On the other hand, when the average minor axis and major axis exceed 100 μm, the specific surface area of the carbonaceous material particles becomes small and the absorption of lithium ions It can be difficult to increase the release rate. It is also effective to bring the average particle diameter into the above range by means such as crushing the carbon fibers. Furthermore, it is preferable that the major axis and the minor axis have similar values. The particle size distribution of the major axis of carbon fiber is 0.5 μm to 500 μm.
It is preferable to have a particle size distribution of 90% or more during m. More preferably, it is 90 between 0.5 μm and 70 μm.
It is desirable to have a particle size distribution of at least%.

【００２４】一般に炭素質物にはその繊維組織が配向性
を有するものと配向性がランダムなものがあるが、本願
発明のリチウム二次電池においては、どちらでも良く、
配向性を有する部分と配向性がランダムな部分が混在し
ていても良い。In general, carbonaceous materials include those having a fibrous structure having an orientation and those having a random orientation. In the lithium secondary battery of the present invention, either may be used.
A portion having orientation and a portion having random orientation may be mixed.

【００２５】前述の炭素繊維の場合、繊維断面における
炭素層面の配向の仕方形態としては放射状構造、繊維表
面側で放射状構造かつ内部でランダム構造、短冊構造、
あるいはラメラ構造などが挙げられる。In the case of the above-mentioned carbon fiber, the manner of orientation of the carbon layer surface in the fiber cross section is a radial structure, a radial structure on the fiber surface side and a random structure inside, a strip structure,
Or a lamella structure etc. are mentioned.

【００２６】前述の如くの特性を示す炭素質物は、石油
ピッチ、コールタールピッチ、原油分解ピッチ、有機樹
脂、有機高分子化合物などを原料として不活性ガスの気
流中または真空中で焼成して、炭素化することにより得
られる。The carbonaceous material having the above-mentioned characteristics is calcined in a stream of an inert gas or in a vacuum from petroleum pitch, coal tar pitch, crude oil decomposition pitch, organic resin, organic polymer compound, etc. It is obtained by carbonizing.

【００２７】特に、前述の炭素繊維は、前記メソフェー
ズピッチ系の原料を溶融して紡条して作られる繊維を酸
化性雰囲気中で熱処理し繊維を不溶化後、真空中または
不活性雰囲気中で焼成し、炭素化することにより得られ
る。焼成温度は、２０００℃以下、特に６００℃〜１５
００℃であることが好ましい。焼成温度が２０００℃を
越えると黒鉛化度が高くなり、電池に用いた際リチウム
イオンの吸蔵・放出量が低下し、また、電解液の分解が
生じやすくなる。In particular, the above-mentioned carbon fiber is produced by melting the mesophase pitch-based raw material and spinning the fiber, heat-treating the fiber in an oxidizing atmosphere to insolubilize the fiber, and then firing it in a vacuum or in an inert atmosphere. And then carbonized. The firing temperature is 2000 ° C or lower, particularly 600 ° C to 15 ° C.
It is preferably 00 ° C. When the firing temperature exceeds 2000 ° C., the degree of graphitization becomes high, the amount of lithium ions stored and released when used in a battery is lowered, and the electrolytic solution is easily decomposed.

【００２８】メソフェーズピッチ系の原料は、比較的低
温（２０００℃以下）での焼成により、適度な黒鉛化度
を示す炭素質物が得られるので、製造上有利である。炭
素質物の原料として用いられる、メソフェーズピッチ
は、メソフェーズを９５％以上の高純度に含有するピッ
チであることが好ましい。メソフェーズピッチに含まれ
る不純物の多くは、主に等方性ピッチである。メソフェ
ーズピッチ中に含まれる等方性ピッチなどの不純物の含
有率が高いと、焼成温度を高くしなければ、得られる炭
素質物の微細組織の配向性を向上させることができな
い。しかしながら焼成温度を高くすると黒鉛化度が高く
なりリチウムイオンの吸蔵・放出量は向上し難くなる。
好ましいメソフェーズピッチの純度としては、９５％以
上である。より好ましいメソフェーズピッチの純度は９
９〜１００％である。The mesophase pitch-based raw material is advantageous in production since a carbonaceous material having an appropriate degree of graphitization can be obtained by firing at a relatively low temperature (2000 ° C. or lower). The mesophase pitch used as a raw material for the carbonaceous material is preferably a pitch containing mesophase in a high purity of 95% or more. Most of the impurities contained in the mesophase pitch are mainly isotropic pitch. If the content of impurities such as isotropic pitch contained in the mesophase pitch is high, the orientation of the fine structure of the obtained carbonaceous material cannot be improved unless the firing temperature is increased. However, when the firing temperature is increased, the degree of graphitization is increased and it becomes difficult to improve the amount of occlusion / release of lithium ions.
The preferred mesophase pitch purity is 95% or more. More preferable mesophase pitch purity is 9
It is 9 to 100%.

【００２９】さらに、本願の第３の発明は、正極と、リ
チウムイオンを吸蔵・放出する炭素質物からなる負極
と、リチウムイオン伝導性電解質とを備えたリチウム二
次電池において、前記炭素質物が、示差熱分析で８００
℃以下に発熱ピークを有し、黒鉛構造の（００２）面の
面間隔（ｄ002 ）が０．３７０ｎｍ未満、Ｃ軸方向の結
晶子の大きさ（Ｌｃ）が３．０ｎｍ以下で、真密度が
１．７ｇ／ｃｍ3 以上で微細組織の配向性がランダムで
あることを特徴とするリチウム二次電池である。Further, a third invention of the present application is a lithium secondary battery comprising a positive electrode, a negative electrode made of a carbonaceous material that absorbs and releases lithium ions, and a lithium ion conductive electrolyte, wherein the carbonaceous material is 800 by differential thermal analysis
It has an exothermic peak below ℃, the interplanar spacing (d 002 ) of the (002) plane of the graphite structure is less than 0.370 nm, the crystallite size (Lc) in the C-axis direction is below 3.0 nm, and the true density is Is 1.7 g / cm 3 As described above, the lithium secondary battery is characterized in that the orientation of the fine structure is random.

【００３０】本発明のリチウム二次電池に用いる炭素質
物は、黒鉛構造の炭素と乱層構造の炭素からなる。負極
に用いる炭素質物が示差熱分析で８００℃以下に発熱ピ
ークを有するとしたのは、その値が８００℃以下を示す
炭素質物は、炭素の微細組織にリチウムイオンが多く吸
蔵する性質を示すためである。これは炭素間の隙間が大
きいためであると考えられる。逆に８００℃を越える値
を示す炭素質物は、リチウムイオンの吸蔵・放出量が少
ない。より好ましくは、発熱ピークは６００℃以上、７
００℃以下に存在していることが好ましい。さらに６２
０℃〜７００℃の範囲であることが、より好ましい。ま
た、１種の炭素質物について、発熱ピークが複数存在す
る場合には、少なくとも一つのピークが８００℃以下の
範囲に存在していれば良い。より好ましくは、少なくと
も１つのピークが７００℃以下に存在し、その他のピー
クは７００℃以上に存在することが好ましい。The carbonaceous material used in the lithium secondary battery of the present invention comprises carbon having a graphite structure and carbon having a turbostratic structure. The reason why the carbonaceous material used for the negative electrode has an exothermic peak at 800 ° C. or less in the differential thermal analysis is that the carbonaceous material having a value of 800 ° C. or less has a property that many lithium ions are occluded in the fine structure of carbon. Is. It is considered that this is because the gap between carbons is large. On the contrary, the carbonaceous material having a value exceeding 800 ° C. has a small amount of lithium ion storage / release. More preferably, the exothermic peak is 600 ° C. or higher, 7
It is preferably present at 00 ° C or lower. Further 62
More preferably, it is in the range of 0 ° C to 700 ° C. In addition, when there are a plurality of exothermic peaks for one type of carbonaceous material, it is sufficient that at least one peak exists in the range of 800 ° C or lower. More preferably, at least one peak is present at 700 ° C or lower, and the other peaks are preferably present at 700 ° C or higher.

【００３１】また、前記炭素質物の黒鉛構造を規定する
指標として、Ｘ線回折により得られる（００２）面の面
間隔（ｄ002 ）及びＣ軸方向の結晶子の大きさ（Ｌｃ）
がある。負極として適する炭素質物の黒鉛構造は、前記
面間隔（ｄ002 ）が０．３７０ｎｍ未満の範囲で、Ｃ軸
方向の結晶子の大きさ（Ｌｃ）が３．０ｎｍ以下とす
る。この範囲を逸脱すると、炭素質物のリチウムイオン
の吸蔵・放出量が低下し、さらに真密度が低下するた
め、それらにより電池の比容量（ｍＡｈ／ｃｍ3 ）の低
下を生じる恐れがある。逆にこの範囲内であると、結晶
子の大きさがリチウムイオンの吸蔵・放出が効果的に行
われる大きさである。また、この範囲であると真密度を
１．７ｇ／ｃｍ3 以上に高めることができる。それによ
り電池の比容量（ｍＡｈ／ｃｍ3 ）が増大できる。好ま
しい範囲としては、（ｄ002 ）が０．３４５ｎｍ以上〜
０．３７０ｎｍ未満、より好ましい範囲としては、０．
３５０ｎｍ〜０．３６５ｎｍ、（Ｌｃ）が１．２ｎｍ〜
２．６ｎｍである。また好ましい真密度の値としては、
１．７５ｇ／ｃｍ3 〜１．９５ｇ／ｃｍ3 である。Further, the graphite structure of the carbonaceous material is defined.
As an index, the (002) plane obtained by X-ray diffraction
Interval (d002) And the crystallite size in the C-axis direction (Lc)
There is. The graphite structure of a carbonaceous material suitable as a negative electrode is
Surface spacing (d002) Is less than 0.370 nm, the C axis
The crystallite size (Lc) in the direction is 3.0 nm or less.
It If it deviates from this range, the carbonaceous material lithium ion
The amount of occlusion and release is reduced, and the true density is reduced.
Therefore, the specific capacity of the battery (mAh / cm3 ) Low
There is a risk of causing the bottom. Conversely, if it is within this range, crystals
The size of the child effectively stores and releases lithium ions.
It is a size that can be seen. In this range, the true density is
1.7 g / cm3 It can be increased to above. By that
Specific capacity of rechargeable battery (mAh / cm3 ) Can be increased. Preferred
The new range is (d002) Is 0.345 nm or more
It is less than 0.370 nm, and a more preferable range is 0.
350 nm to 0.365 nm, (Lc) is 1.2 nm to
It is 2.6 nm. Further, as a preferable value of true density,
1.75 g / cm3 ~ 1.95g / cm3 Is.

【００３２】また、アルゴンレーザラマンペクトル（波
長５１４．５ｎｍ）における１５８０ｃｍ-1のピーク強
度（Ｒ２）に対する１３６０ｃｍ-1のピーク強度（Ｒ
１）の比（Ｒ１／Ｒ２）は、０．７より大きいことが好
ましい。これはリチウムイオンを多量に吸蔵・放出でき
る乱層構造の割合が大きくなり、負極容量は増大するた
めである。係る強度比を０．７以下にすると、非水電解
液中の溶媒の分解が生じやすくなり、また、炭素質物か
らなる負極のリチウムイオンの吸蔵・放出量が低下する
恐れがある。より好ましい強度比（Ｒ１／Ｒ２）は０．
８〜１．１の範囲である。さらに好ましい範囲は、０．
８５〜１．００である。また、本願第３の発明の負極に
係る炭素質物は、その微細組織の配向性がランダムなも
のである。The peak intensity (R2) of the argon laser Raman spectrum (wavelength 514.5 nm) at 1580 cm -1 to the peak intensity (R2) of 1580 cm -1 was used.
The ratio (R1 / R2) of 1) is preferably larger than 0.7. This is because the proportion of the disordered layer structure capable of absorbing and releasing a large amount of lithium ions increases, and the negative electrode capacity increases. When the strength ratio is 0.7 or less, the solvent in the non-aqueous electrolyte is likely to be decomposed, and the amount of occlusion / release of lithium ions of the carbonaceous material negative electrode may be reduced. A more preferable intensity ratio (R1 / R2) is 0.
It is in the range of 8 to 1.1. A more preferable range is 0.
85 to 1.00. Further, in the carbonaceous material according to the negative electrode of the third invention of the present application, the orientation of its fine structure is random.

【００３３】本願の第３の発明に係る炭素質物の場合、
粒径は０．５μｍから３０μｍの範囲に体積比率で９０
％以上の粒度分布を有することが好ましい。上記の粒度
分布を有する炭素質物はセパレータを通過する恐れがな
く、且つ充填密度の高い負極を作製することができる。
より好ましい粒度分布の範囲は１μｍ〜２０μｍの範囲
である。また平均粒径は２μｍ〜２０μｍの範囲である
ことが好ましい。In the case of the carbonaceous material according to the third invention of the present application,
Particle size is in the range of 0.5 μm to 30 μm by volume ratio of 90
It is preferable to have a particle size distribution of at least%. The carbonaceous material having the above particle size distribution is unlikely to pass through the separator, and a negative electrode having a high packing density can be manufactured.
A more preferable range of particle size distribution is 1 μm to 20 μm. The average particle size is preferably in the range of 2 μm to 20 μm.

【００３４】上記の特性を有する微細組織の配向性がラ
ンダムな炭素質物は、特にフラン樹脂、フェノール樹
脂、アクリル樹脂、ハロゲン化ビニル樹脂、ポリアミド
樹脂などの有機高分子化合物を原料として、不活性ガス
の気流中または真空中１０００℃〜２８００℃の範囲で
焼成し、炭素化することにより容易に得られる。より好
ましい焼成温度は、２２００℃〜２６００℃の範囲であ
る。また、等方性ピッチを炭素化した繊維状炭素質物で
も良い。The carbonaceous material having the above-mentioned characteristics, in which the orientation of the microstructure is random, is obtained by using an organic polymer compound such as a furan resin, a phenol resin, an acrylic resin, a vinyl halide resin or a polyamide resin as a raw material, and an inert gas. It can be easily obtained by firing in an air stream or in a vacuum in the range of 1000 ° C to 2800 ° C and carbonizing. A more preferable firing temperature is in the range of 2200 ° C to 2600 ° C. Also, a fibrous carbonaceous material obtained by carbonizing isotropic pitch may be used.

【００３５】上記の如く樹脂や等方性ピッチを焼成して
得られる、微細組織の配向性がランダムな炭素質物は、
硬度が大きくかつ気孔率が小さいという特徴を持ってい
る。そのためリチウムイオンの吸蔵・放出に伴う構造の
劣化や自己放電は小さく、また真密度も高くなるため電
池を長寿命にし、かつ負極の容量を大きくすることがで
きる。中でもフェノール樹脂を１８００℃〜２６００℃
で焼成して炭素化したものが好ましい。The carbonaceous material obtained by firing the resin or the isotropic pitch as described above has a random microstructure orientation.
It is characterized by high hardness and low porosity. Therefore, the deterioration of the structure and the self-discharge due to the absorption / desorption of lithium ions are small, and the true density is high, so that the battery can have a long life and the capacity of the negative electrode can be increased. Above all, the phenol resin is 1800 ° C to 2600 ° C.
It is preferable to use a carbonized product that is fired in.

【００３６】一方、本願の第１の発明〜第３の発明にお
けるリチウムイオン伝導性電解質としては、例えばジエ
チルカーボネート、エチレンカーボネート、プロピレン
カーボネート、ブチレンカーボネート、γ−ブチロラク
トン、スルホラン、アセトニトリル、１，２−ジメトキ
シエタン、１，３−ジメトキシプロパン、ジエチルエー
テル、テトラヒドロフラン、２−メチルテトラヒドロフ
ラン、ジメトシキメタン、ジエトキシエタンから選ばれ
る少なくとも１種以上からなる非水溶媒に過塩素酸リチ
ウム（ＬｉＣｌＯ4 ）、六フッ化リン酸リチウム（Ｌｉ
ＰＦ6 ）、ホウフッ化リチウム（ＬｉＢＦ4 ）、六フッ
化砒素リチウム（ＬｉＡＳＦ6 ）、トリフルオロメタン
スルホン酸リチウム（ＬｉＣＦ3 ＳＯ3 ）などのリチウ
ム塩（電解質）を溶解した非水電解液を挙げることがで
きる。前記電解質の非水溶媒に対する溶解量は、０．５
〜１．０モル／１とすることが望ましい。また、電解質
として、リチウムイオン導電性の固体電解質を用いるこ
とができる。固体電解質は、例えば、高分子化合物にリ
チウム塩を複合した高分子固体電解質を挙げることがで
きる。リチウムイオン伝導性電解質に用いられる非水溶
媒、電解質、及び固体電解質は、上記の物質に限定され
るものではない。On the other hand, as the lithium ion conductive electrolyte in the first to third inventions of the present application, for example, diethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, sulfolane, acetonitrile, 1,2- Lithium perchlorate (LiClO 4 ), hexafluoride in a non-aqueous solvent consisting of at least one selected from dimethoxyethane, 1,3-dimethoxypropane, diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, dimethoxymethane, and diethoxyethane. Lithium phosphate (Li
PF 6 ), lithium borofluoride (LiBF 4 ), lithium hexafluoroarsenide (LiASF 6 ), lithium trifluoromethanesulfonate (LiCF 3 SO 3 ), and other non-aqueous electrolyte solutions in which a lithium salt (electrolyte) is dissolved. You can The amount of the electrolyte dissolved in the non-aqueous solvent is 0.5.
It is desirable to set it to ˜1.0 mol / 1. Further, a lithium ion conductive solid electrolyte can be used as the electrolyte. As the solid electrolyte, for example, a polymer solid electrolyte in which a lithium salt is compounded with a polymer compound can be used. The non-aqueous solvent, electrolyte, and solid electrolyte used for the lithium ion conductive electrolyte are not limited to the above substances.

【００３７】また、本願の第１の発明〜第３の発明に係
るリチウム二次電池の正極は、種々の酸化物、例えば、
二酸化マンガン、リチウムマンガン複合酸化物、リチウ
ム含有ニッケル酸化物、リチウム含有コバルト化合物、
リチウム含有ニッケルコバルト酸化物、リチウムを含む
非晶質五酸化バナジウムや、二硫化チタン、二硫化モリ
ブデンなどのカルコゲン化合物などを挙げることができ
る。The positive electrode of the lithium secondary battery according to the first to third inventions of the present application is made of various oxides, for example,
Manganese dioxide, lithium manganese composite oxide, lithium-containing nickel oxide, lithium-containing cobalt compound,
Examples thereof include lithium-containing nickel-cobalt oxide, amorphous vanadium pentoxide containing lithium, and chalcogen compounds such as titanium disulfide and molybdenum disulfide.

【００３８】[0038]

【実施例】以下、本発明を円筒形リチウム二次電池に適
用した例で詳細に説明する。 （実施例１）The present invention will be described in detail below with reference to an example in which the present invention is applied to a cylindrical lithium secondary battery. (Example 1)

【００３９】図１に、本実施例で用いた円筒形リチウム
二次電池の構成を示す。図１において、１は底部に絶縁
体２が配置された有底円筒状のステンレス容器である。
この容器１内には、電極群３が収納されている。この電
極群３は、正極４、セパレータ５及び負極６をこの順序
で積層した帯状物を負極６が外側に位置するように渦巻
き状に巻き回した構造になっている。FIG. 1 shows the structure of the cylindrical lithium secondary battery used in this example. In FIG. 1, reference numeral 1 is a bottomed cylindrical stainless steel container in which an insulator 2 is arranged on the bottom.
The electrode group 3 is housed in the container 1. The electrode group 3 has a structure in which a band-shaped material in which a positive electrode 4, a separator 5, and a negative electrode 6 are laminated in this order is spirally wound so that the negative electrode 6 is located outside.

【００４０】前記正極４は、リチウムコバルト酸化物
（Ｌｉx ＣｏＯ2 （0.8 ≦x ≦１））粉末８０重量％を
アセチレンブラック１５重量％及びポリテトラフルオロ
エチレン粉末５重量％と共に混合し、シート化し、エキ
スパンドメタル集電体に圧着した状態になっている。前
記セパレータ５は、ポリプロピレン性多孔質フィルムか
ら形成されている。The positive electrode 4 is made into a sheet by mixing 80 wt% of lithium cobalt oxide (Li x CoO 2 (0.8 ≤ x ≤ 1)) powder with 15 wt% of acetylene black and 5 wt% of polytetrafluoroethylene powder. , It is in a state of being crimped to the expanded metal current collector. The separator 5 is formed of a polypropylene porous film.

【００４１】負極に用いる炭素質物として球状炭素粒子
をコールタールピッチから熱処理、分離されたメソフェ
ーズ小球体をアルゴンガス気流中、７００℃で１０時間
焼成して得た。負極６は、この炭素質物９８重量％をエ
チレンプロピレン共重合体２重量％と共に混合し、これ
を集電体としてのステンレス箔に１０ｍｇ／ｃｍ2 の量
で塗布したものである。なお、前記炭素質物は、Ｘ線回
折による各種のパラメータを半価幅中点法で測定したと
ころ、（ｄ002 ）＝０．３６２，（Ｌｃ）＝１．２ｎｍ
であった。（但し、同物質をピークトップ法で測定した
ところ（ｄ002）＝０．３５４ｎｍ，Ｌｃ＝１．２ｎｍ
であった。）示差熱分析による発熱ピークは、二つ得ら
れ、６０９℃と６６５℃であった。また、アルゴンレー
ザを光源として測定された１３６０ｃｍ-1のラマン強度
Ｒ１と１５８０ｃｍ-1のラマン強度Ｒ２の比が１．５で
ある。また、本実施例の炭素質物は、１μｍから１５μ
ｍの範囲で体積比率で９０％以上の粒度分布を有し、ま
た平均粒径が５μｍであった。As carbonaceous material used for the negative electrode, spherical carbon particles were heat-treated from coal tar pitch, and the separated mesophase spheres were obtained by firing in an argon gas stream at 700 ° C. for 10 hours. For the negative electrode 6, 98% by weight of this carbonaceous material was mixed with 2% by weight of an ethylene-propylene copolymer, and this was mixed with stainless steel foil as a current collector at 10 mg / cm 2. It was applied in the amount of. In addition, the above-mentioned carbonaceous material was measured with various parameters by X-ray diffraction by the half-value width midpoint method, and was (d 002 ) = 0.362, (Lc) = 1.2 nm.
Met. (However, when the same substance was measured by the peak top method, (d 002 ) = 0.354 nm, Lc = 1.2 nm
Met. ) Two exothermic peaks by differential thermal analysis were obtained, which were 609 ° C and 665 ° C. The ratio of the Raman intensity R2 of the Raman intensity R1 and 1580 cm -1 in 1360 cm -1 measured argon laser as a light source is 1.5. In addition, the carbonaceous material of this example is 1 μm to 15 μm.
The particle size distribution was 90% or more by volume in the range of m, and the average particle size was 5 μm.

【００４２】前記容器１内には、六フッ化りん酸リチウ
ム（ＬｉＰＦ6 ）をエチレンカーボネートとプロピレン
カーボネイトと１，２−ジメトキシエタンの混合溶媒
（混合体積比率２５：２５：５０）に１．０モル／１の
濃度で溶解した組成の電解液が収容されている。前記電
極群３上には、中央部が開口された絶縁紙７が載置され
ている。さらに、前記容器１の上部開口部には、絶縁封
口板８が該容器１へのかしめ加工などにより液密に設け
られており、かつ該絶縁封口板８の中央には正極端子９
が嵌合されている。この正極端子９は、前記電極群３の
正極４に正極リード１０を介して接続されている。なお
電極群３の負極６は負極リード（図示しない）を介して
負極端子である前記容器１に接続されている。In the container 1, lithium hexafluorophosphate (LiPF 6 ) was added to a mixed solvent of ethylene carbonate, propylene carbonate and 1,2-dimethoxyethane (mixed volume ratio 25:25:50) at 1.0. An electrolytic solution having a composition dissolved at a concentration of mol / 1 is contained. On the electrode group 3, an insulating paper 7 having a central opening is placed. Further, an insulating sealing plate 8 is liquid-tightly provided in the upper opening of the container 1 by caulking the container 1, and the positive electrode terminal 9 is provided at the center of the insulating sealing plate 8.
Are fitted. The positive electrode terminal 9 is connected to the positive electrode 4 of the electrode group 3 via a positive electrode lead 10. The negative electrode 6 of the electrode group 3 is connected to the container 1 serving as a negative electrode terminal through a negative electrode lead (not shown).

【００４３】実施例１で用いた負極の炭素質物の前駆
体、焼成温度、焼成時間及びＸ線回折で測定した（ｄ
002 ）及び（Ｌｃ）の値（各々表１中では、
「（ｄ002 ）」，「（Ｌｃ）」と記載している。）示差
熱分析による発熱ピーク（表１中では「発熱ピーク」と
記載している。）、及びアルゴンレーザを光源として測
定された１３６０ｃｍ-1のラマン強度Ｒ１と１５８０ｃ
ｍ-1のラマン強度Ｒ２の比（表１中では「（Ｒ１／Ｒ
２）」と記載している。）を表１に記載した。なお、Ｘ
線回折で測定した（ｄ002 ）及び（Ｌｃ）の値の半価幅
中点法により求めた値である。また同欄の（ ）内の値
はピークトップ法により求めた（ｄ002 ）及び（Ｌｃ）
の値である。The carbonaceous material precursor for the negative electrode used in Example 1, the firing temperature, the firing time, and the X-ray diffraction measurement (d).
002 ) and (Lc) (in Table 1, respectively,
It is described as “(d 002 )” and “(Lc)”. ) Exothermic peak by differential thermal analysis (described as "exothermic peak" in Table 1), and Raman intensities R1 and 1580c at 1360 cm -1 measured with an argon laser as a light source.
Ratio of Raman intensity R2 of m -1 (in Table 1, "(R1 / R
2) ”. ) Is shown in Table 1. Note that X
It is a value obtained by the half-value midpoint method of the values of (d 002 ) and (Lc) measured by line diffraction. The values in parentheses in the same column were obtained by the peak top method (d 002 ) and (Lc).
Is the value of.

【００４４】[0044]

【表１】 （実施例２〜実施例６）以下に示すような負極を用い、
負極以外は実施例１と同様な電池を組み立てた。[Table 1] (Examples 2 to 6) Using a negative electrode as shown below,
A battery similar to that of Example 1 was assembled except for the negative electrode.

【００４５】負極に用いる炭素質物として球状炭素質物
粒子を、コールタールピッチから熱処理、分離されたメ
ソフェーズ小球体をアルゴンガス気流中表１に示す焼成
温度及び焼成時間でアルゴンガス気流中で焼成して得
た。負極６は前記炭素質物９８重量％をエチレンプロピ
レン共重合体２重量％と共に混合し、これを集電体とし
てのステンレス箔に１０ｍｇ／ｃｍ2 の量で塗布したも
のである。得られた炭素質物の各種の特性を実施例１と
同様の方法で測定した。その結果を表１に併記する。 （比較例１）Spherical carbonaceous material particles as the carbonaceous material used for the negative electrode were heat treated from coal tar pitch, and the separated mesophase spherules were fired in an argon gas stream in an argon gas stream at the firing temperature and firing time shown in Table 1. Obtained. For the negative electrode 6, 98% by weight of the carbonaceous material was mixed with 2% by weight of an ethylene-propylene copolymer, and this was added to a stainless steel foil as a current collector at 10 mg / cm 2. It was applied in the amount of. Various characteristics of the obtained carbonaceous material were measured by the same methods as in Example 1. The results are also shown in Table 1. (Comparative Example 1)

【００４６】以下に示すような負極を用い、負極以外は
実施例１と同様な電池を組み立てた。負極６は表１に示
す炭素質物前駆体を同表中に表される焼成温度及び焼成
時間でアルゴンガス気流中において焼成して得られた炭
素質物９８重量％をエチレンプロピレン共重合体２重量
％と共に混合し、これを集電体としてのステンレス箔に
１０ｍｇ／ｃｍ2 の量で塗布したものである。得られた
炭素質物の各種の特性を実施例１と同様の方法で測定し
た。その結果を表１に併記する。Using the negative electrode as shown below, a battery was assembled in the same manner as in Example 1 except for the negative electrode. The negative electrode 6 was obtained by firing the carbonaceous material precursor shown in Table 1 in an argon gas stream at the firing temperature and firing time shown in the same table, and obtaining 98% by weight of the carbonaceous material and 2% by weight of ethylene propylene copolymer. And mixed with stainless steel foil as a current collector at 10 mg / cm 2 It was applied in the amount of. Various characteristics of the obtained carbonaceous material were measured by the same methods as in Example 1. The results are also shown in Table 1.

【００４７】しかして、本実施例１〜実施例６及び比較
例１のリチウム二次電池について充電電流５０ｍＡで
４．２Ｖまで充電し、２．５Ｖまで５０ｍＡの電流で放
電する充放電を繰り返し行い、各電池の放電容量とサイ
クル寿命をそれぞれ測定した。その結果を図２に示す。Therefore, the lithium secondary batteries of Examples 1 to 6 and Comparative Example 1 were charged up to 4.2 V at a charging current of 50 mA, and repeatedly charged and discharged by discharging up to 2.5 V at a current of 50 mA. The discharge capacity and cycle life of each battery were measured. The result is shown in FIG.

【００４８】図２から明らかなように本実施例１〜実施
例６のリチウム二次電池では、比較例１の電池に比べて
容量が増大し、かつサイクル寿命が格段に向上されるこ
とが分かる。 （比較例２）以下に示すような粉度分布の範囲を有する
メソフェーズ小球体の球状炭素質物の負極を用い、負極
以外は実施例１と同様な構成の電池を組み立てた。As is clear from FIG. 2, the lithium secondary batteries of Examples 1 to 6 have a larger capacity and a significantly longer cycle life than the battery of Comparative Example 1. .. (Comparative Example 2) A battery having the same structure as in Example 1 was assembled using a negative electrode of a spherical carbonaceous material of mesophase spherules having the following range of fineness distribution.

【００４９】負極は、コールタールピッチから熱処理、
分離されたメソフェーズ小球体をアルゴンガス気流中、
７００℃で１０時間焼成して得られた前記粒度分布の範
囲が１５μｍから４０μｍで、平均粒径が２６μｍの炭
素質物粒子９８重量％をエチレンプロピレン共重合体２
重量％と共に混合し、これを集電体としてのステンレス
箔に１０ｍｇ／ｃｍ2 の量で塗布したものである。な
お、前記炭素質物粒子は、Ｘ線回折による各種のパラメ
ーターが（ｄ002 ）＝０．３５４，（Ｌｃ）＝１．２ｎ
ｍで、アルゴンレーザを光源として測定された１３６０
ｃｍ-1のラマン強度Ｒ１と１５８０ｃｍ-1のランマ強度
Ｒ２の比（Ｒ１／Ｒ２）が、１．５である。また、示差
熱分析による発熱ピークは２つ得られ、６０９℃と６６
５℃であった。The negative electrode is heat-treated from coal tar pitch,
The separated mesophase spheres in an argon gas stream,
98% by weight of carbonaceous material particles having a particle size distribution range of 15 μm to 40 μm and an average particle size of 26 μm obtained by firing at 700 ° C. for 10 hours were ethylene propylene copolymer 2
10% / cm 2 on a stainless steel foil as a current collector by mixing with the weight% It was applied in the amount of. The carbonaceous material particles had various parameters (d 002 ) = 0.354, (Lc) = 1.2n according to X-ray diffraction.
1360 m measured with an argon laser as the light source
The ratio of the rammer intensity R2 of the Raman intensity R1 and 1580 cm -1 in cm -1 (R1 / R2) is 1.5. In addition, two exothermic peaks were obtained by differential thermal analysis, which were 609 ° C and 66 ° C.
It was 5 ° C.

【００５０】しかして、比較例２は負極作成時に粒径の
大きい前記小球体は粉砕され、微粉片を生じたため、正
極とショートし電池作動はできなかった。また負極充填
密度は実施例１に比して１割低下していた。 （実施例７〜実施例１０）以下に示すような負極を用
い、実施例１と同様な電池を組み立てた。In Comparative Example 2, however, the small spheres having a large particle size were crushed during the production of the negative electrode, and fine powder pieces were produced, which caused a short circuit with the positive electrode and the battery could not operate. The negative electrode packing density was 10% lower than that in Example 1. (Examples 7 to 10) A battery similar to that of Example 1 was assembled using the following negative electrodes.

【００５１】まず、以下に示すように、負極に用いる炭
素質物として、炭素繊維粒子を得た。表２に示す炭素質
物前駆体を溶融後、紡条して繊維状とし、その後酸化性
雰囲気で熱処理を施し不融化した。その後不活性雰囲気
下で同表に示される焼成温度で焼成し、炭素繊維を得
た。得られた炭素繊維を粉砕して炭素繊維粒子とし、こ
の炭素繊維粒子９８重量％をエチレンプロピレン共重合
体２重量％と共に混合し、これを集電体としてのステン
レス箔に１０ｍｇ／ｃｍ2 の量で塗布することにより負
極６を得た。First, as shown below, the charcoal used for the negative electrode
Carbon fiber particles were obtained as a substance. Carbon quality shown in Table 2
After melting the precursor, it is spun into a fibrous form and then oxidized.
It was made infusible by heat treatment in an atmosphere. Then an inert atmosphere
Carbon fiber is obtained by firing at the firing temperature shown in the table below.
It was The obtained carbon fiber is crushed into carbon fiber particles and
Copolymerization of 98% by weight of carbon fiber particles of ethylene
Mix with 2% by weight of the body, and use this as a current collector.
10 mg / cm on the foil2 Negative by applying the amount of
Got 6

【００５２】なお、実施例７の炭素繊維粒子の長径は、
１μｍから３０μｍの範囲に体積％で９０％以上の粒度
分布を有し、平均長径が１０μｍであった。また、炭素
質物前駆体中のメソフェーズピッチの純度を表２に併記
した。The major axis of the carbon fiber particles of Example 7 was
The particle size distribution was 90% or more in volume% in the range of 1 μm to 30 μm, and the average major axis was 10 μm. Table 2 also shows the purity of mesophase pitch in the carbonaceous material precursor.

【００５３】また、各実施例で用いた炭素質物のＸ線回
折により得られた（ｄ002 ）及び（Ｌｃ）示差熱分析に
よる発熱ピーク（表２中では「発熱ピーク」として記載
されている。）、真密度、引張強度及び引張弾性率を測
定し表２に併記した。なお、Ｘ線回折による（ｄ002 ）
及び（Ｌｃ）の値は、半価幅中点法により求めた。 （比較例３〜比較例７）Further, the exothermic peaks (d 002 ) and (Lc) obtained by X-ray diffraction of the carbonaceous materials used in each Example are shown by differential thermal analysis (described as "exothermic peak" in Table 2). ), True density, tensile strength and tensile elastic modulus were measured and are also shown in Table 2. In addition, by X-ray diffraction (d 002 )
The values of and (Lc) were obtained by the half-width half-point method. (Comparative Examples 3 to 7)

【００５４】以下に示すような負極を用い、負極以外は
実施例１と同様な電池を組み立てた。まず、負極に用い
る炭素質物としての炭素繊維粒子を得た。表２に示す炭
素質物前駆体を実施例７〜実施例１０と同様な方法で炭
素繊維粒子とした。この炭素繊維粒子９８重量％をエチ
レンプロピレン共重合体２重量％と共に混合し、これを
集電体としてのステンレス箔に１０ｍｇ／ｃｍ2 の量で
塗布することにより負極６を得た。得られた負極の炭素
質物の諸特性を実施例７〜実施例１０と同様の方法で測
定した。その結果を表２に併記した。Using a negative electrode as shown below, a battery similar to that of Example 1 was assembled except for the negative electrode. First, carbon fiber particles as a carbonaceous material used for the negative electrode were obtained. The carbonaceous material precursors shown in Table 2 were made into carbon fiber particles by the same method as in Examples 7 to 10. 98% by weight of the carbon fiber particles were mixed with 2% by weight of an ethylene-propylene copolymer, and this was mixed with stainless steel foil as a current collector at 10 mg / cm 2. Negative electrode 6 was obtained by applying an amount of. Various properties of the obtained carbonaceous material of the negative electrode were measured by the same methods as in Examples 7 to 10. The results are also shown in Table 2.

【００５５】[0055]

【表２】 [Table 2]

【００５６】しかして、本実施例７〜実施例１０及び比
較例３〜比較例７のリチウム二次電池について充電電流
１２５ｍＡで４．２Ｖまで充電し、２．５Ｖまで１２５
ｍＡの電流で放電する充放電を繰り返し行ない、各電池
の放電容量とサイクル寿命をそれぞれ測定した。その結
果を図３に示す。Therefore, the lithium secondary batteries of Examples 7 to 10 and Comparative Examples 3 to 7 were charged up to 4.2 V at a charging current of 125 mA and up to 2.5 V.
Charging and discharging with a current of mA was repeated to measure the discharge capacity and cycle life of each battery. The result is shown in FIG.

【００５７】また、メソフェーズピッチを５５０℃で焼
成炭素化したものを負極として用いた電池を作成した。
しかしながら、サイクル劣化が大きく、容量も小さいも
のであった。Further, a battery was prepared using, as a negative electrode, one obtained by firing and carbonizing mesophase pitch at 550 ° C.
However, the cycle deterioration was large and the capacity was small.

【００５８】図３から明らかなように本実施例のリチウ
ム二次電池では、比較例３〜比較例７の電池に比べ容量
が増大し、かつサイクル寿命が格段に向上されることが
分かる。 （実施例１１〜実施例１４）以下に示すような負極を用
い、負極以外は実施例１と同様な電池を組み立てた。As is apparent from FIG. 3, the lithium secondary battery of this example has a larger capacity and a markedly improved cycle life as compared with the batteries of Comparative Examples 3 to 7. (Examples 11 to 14) Batteries similar to those of Example 1 were assembled using the following negative electrodes, except for the negative electrode.

【００５９】まず、表３に示す炭素質物前駆体を焼成温
度、焼成時間、炭素質物前駆体の分子量、及び炭素化を
促進または抑制させるための添加剤（触媒）などを調整
し、焼成炭素化して得た微細組織の配向性がランダムな
炭素質物を平均粒径１２μｍに粉砕後、この炭素質物粉
末９８重量％エチレンプロピレン共重合体２重量％と共
に混合し、これを集電体としての銅箔に１０ｍｇ／ｃｍ
2 の量で塗布することにより負極６を得た。First, the carbonaceous material precursor shown in Table 3 is carbonized by calcining it by adjusting the firing temperature, the firing time, the molecular weight of the carbonaceous material precursor, the additive (catalyst) for promoting or suppressing carbonization, and the like. The obtained carbonaceous material having a fine texture with random orientation is pulverized to have an average particle diameter of 12 μm, and then mixed with 98% by weight of this carbonaceous material powder and 2% by weight of ethylene propylene copolymer, and this is a copper foil as a current collector. 10 mg / cm
2 Negative electrode 6 was obtained by applying an amount of.

【００６０】各実施例で用いた炭素質物についてＸ線回
折により得られた（ｄ002 ）及び（Ｌｃ）、示差熱分析
による発熱ピーク（表３中で「発熱ピーク」として記載
されている。）、真密度、及びアルゴンレーザを光源と
して測定された１３６０ｃｍ-1のラマン強度Ｒ１と１５
８０ｃｍ-1のラマン強度Ｒ２の比（表３中では「Ｒ１／
Ｒ２」と記載されている。）を測定し表３に併記した。 （比較例８〜比較例１０）以下に示すような負極を用
い、負極以外は実施例１と同様な電池を組み立てた。Exothermic peaks (d 002 ) and (Lc) obtained by X-ray diffraction for the carbonaceous materials used in each example, which were obtained by differential thermal analysis (described as "exothermic peak" in Table 3). , True density, and Raman intensities R1 and 15 of 1360 cm -1 measured with an argon laser as a light source.
Ratio of Raman intensity R2 of 80 cm -1 (in Table 3, "R1 /
R2 ”. ) Was measured and is also shown in Table 3. (Comparative Examples 8 to 10) The following negative electrodes were used, and a battery similar to that of Example 1 was assembled except for the negative electrodes.

【００６１】まず、表３に示す炭素質物前駆体から実施
例１１〜実施例１４と同様な方法でその微細組織の配向
がランダムな炭素質物を得た。この炭素繊維粒子９８重
量％をエチレンプロピレン共重合体２重量％と共に混合
し、これを集電体としての銅箔に１０ｍｇ／ｃｍ2 の量
で塗布することにより負極６を得た。得られた負極の炭
素繊維粒子の諸特性を実施例１１〜実施例１４と同様の
方法で測定した。その結果を表３に併記した。First, from the carbonaceous material precursors shown in Table 3, carbonaceous materials having a random microstructure orientation were obtained in the same manner as in Examples 11 to 14. 98% by weight of the carbon fiber particles were mixed with 2% by weight of an ethylene-propylene copolymer, and this was added to a copper foil as a current collector at 10 mg / cm 2. Negative electrode 6 was obtained by applying an amount of. Various properties of the obtained carbon fiber particles of the negative electrode were measured by the same methods as in Examples 11 to 14. The results are also shown in Table 3.

【００６２】なお、比較例８及び比較例９は、特開昭６
２−１２２０６６号公報第７頁左上欄１０行目乃至同頁
左欄１７行目に開示された炭素質材料の調製方法に基づ
き製造した炭素質物である。比較例８は炭素化時の焼成
温度１８００℃、比較例９は炭素化時の焼成温度が２１
００℃である。Comparative Example 8 and Comparative Example 9 are disclosed in
It is a carbonaceous material produced based on the method for preparing a carbonaceous material disclosed on page 7, upper left column, line 10 to left column, line 17 of JP-A 2-122066. Comparative Example 8 has a calcination temperature of 1800 ° C. during carbonization, and Comparative Example 9 has a calcination temperature of 21 during carbonization.
It is 00 ° C.

【００６３】[0063]

【表３】 [Table 3]

【００６４】しかして、本実施例１１〜実施例１４及び
比較例８〜比較例１０のリチウム二次電池について充電
電流１２５ｍＡで４．２Ｖまで充電し、２．５Ｖまで１
２５ｍＡの電流で放電する充放電を繰り返し行い、各電
池の放電容量とサイクル寿命をそれぞれ測定した。その
結果を図４に示す。Therefore, the lithium secondary batteries of Examples 11 to 14 and Comparative Examples 8 to 10 were charged to 4.2 V at a charging current of 125 mA, and were charged to 2.5 V at 1 V.
Charging and discharging with a current of 25 mA was repeated to measure the discharge capacity and cycle life of each battery. The result is shown in FIG.

【００６５】図４から明らかなように本実施例のリチウ
ム二次電池では、比較例８〜比較例１０の電池に比べ容
量が増大し、且つサイクル寿命が格段に向上されること
が分かる。As is apparent from FIG. 4, in the lithium secondary battery of this example, the capacity was increased and the cycle life was remarkably improved as compared with the batteries of Comparative Examples 8 to 10.

【００６６】[0066]

【発明の効果】以上詳述した如く、本発明によれば高容
量でサイクル寿命に優れたリチウム二次電池を提供でき
る。As described above in detail, according to the present invention, a lithium secondary battery having a high capacity and an excellent cycle life can be provided.

【図面の簡単な説明】[Brief description of drawings]

【図１】本発明の実施例１における円筒型リチウム二次
電池を示す部分断面図。FIG. 1 is a partial cross-sectional view showing a cylindrical lithium secondary battery in Example 1 of the present invention.

【図２】実施例１〜実施例６及び比較例１のリチウム二
次電池における充放電サイクルと放電容量との関係を示
す特性図。FIG. 2 is a characteristic diagram showing the relationship between the charge / discharge cycle and the discharge capacity in the lithium secondary batteries of Examples 1 to 6 and Comparative Example 1.

【図３】実施例７〜本実施例１０及び比較例３〜比較例
７のリチウム二次電池における充放電サイクルと放電容
量との関係を示す特性図。FIG. 3 is a characteristic diagram showing the relationship between the charge / discharge cycle and the discharge capacity in the lithium secondary batteries of Examples 7 to 10 and Comparative Examples 3 to 7.

【図４】実施例１１〜本実施例１４及び比較例８〜比較
例１０のリチウム二次電池における充放電サイクルと放
電容量との関係を示す特性図。FIG. 4 is a characteristic diagram showing the relationship between the charge / discharge cycle and the discharge capacity in the lithium secondary batteries of Examples 11 to 14 and Comparative Examples 8 to 10.

【図５】炭素質物の微細組織の配向例を示す概略図。FIG. 5 is a schematic view showing an example of the orientation of a fine structure of a carbonaceous material.

【符号の説明】[Explanation of symbols]

１……ステンレス容器 ３……電極群 ４……正極 ５
……セパレータ ６……負極 ８……封口板 ９……正極端子1 ... Stainless steel container 3 ... Electrode group 4 ... Positive electrode 5
...... Separator 6 …… Negative electrode 8 …… Seal plate 9 …… Positive electrode terminal

Claims (3)

【特許請求の範囲】[Claims] 【請求項１】正極と、リチウムイオンを吸蔵・放出する
炭素質物からなる負極と、リチウムイオン伝導性電解質
とを備えたリチウム二次電池において、前記炭素質物が
示差熱分析で８００℃以下に発熱ピークを有し、黒鉛構
造の（００２）面の面間隔（ｄ002 ）が０．３７０ｎｍ
未満、Ｃ軸方向の結晶子の大きさ（Ｌｃ）が４．０ｎｍ
以下、真密度が１．７ｇ／ｃｍ3 以上であることを特徴
とするリチウム二次電池。1. A lithium secondary battery comprising a positive electrode, a negative electrode made of a carbonaceous material that absorbs and releases lithium ions, and a lithium ion conductive electrolyte, wherein the carbonaceous material exotherms below 800 ° C. by differential thermal analysis. It has a peak and the interplanar spacing (d 002 ) of the (002) plane of the graphite structure is 0.370 nm.
Less than, crystallite size (Lc) in the C-axis direction is 4.0 nm
Below, the true density is 1.7 g / cm 3. The lithium secondary battery characterized by the above. 【請求項２】正極と、リチウムイオンを吸蔵・放出する
炭素質物からなる負極と、リチウムイオン伝導性電解質
とを備えたリチウム二次電池において、前記炭素質物が
示差熱分析で８００℃以下に発熱ピークを有し、黒鉛構
造の（００２）面の面間隔（ｄ002 ）が０．３７０ｎｍ
未満、Ｃ軸方向の結晶子の大きさ（Ｌｃ）が４．０ｎｍ
以下、引張強度が８００ＭＰａ以上２５００ＭＰａ以
下、引張弾性率が８０ＧＰａ以上４５０ＧＰａ以下であ
ることを特徴とするリチウム二次電池。2. A lithium secondary battery comprising a positive electrode, a negative electrode composed of a carbonaceous material that absorbs and releases lithium ions, and a lithium ion conductive electrolyte, wherein the carbonaceous material generates heat of 800 ° C. or less by differential thermal analysis. It has a peak and the interplanar spacing (d 002 ) of the (002) plane of the graphite structure is 0.370 nm.
Less than, crystallite size (Lc) in the C-axis direction is 4.0 nm
Hereinafter, a lithium secondary battery having a tensile strength of 800 MPa or more and 2500 MPa or less and a tensile elastic modulus of 80 GPa or more and 450 GPa or less. 【請求項３】正極と、リチウムイオンを吸蔵・放出する
炭素質物からなる負極と、リチウムイオン伝導性電解質
とを備えたリチウム二次電池において、前記炭素質物が
示差熱分析で８００℃以下に発熱ピークを有し、黒鉛構
造の（００２）面の面間隔（ｄ002 ）が０．３７０ｎｍ
未満、Ｃ軸方向の結晶子の大きさ（Ｌｃ）が３．０ｎｍ
以下、真密度が１．７ｇ／ｃｍ3 以上で微細組織の配向
性がランダムであることを特徴とするリチウム二次電
池。3. A lithium secondary battery comprising a positive electrode, a negative electrode made of a carbonaceous material that absorbs and releases lithium ions, and a lithium ion conductive electrolyte, wherein the carbonaceous material generates heat of 800 ° C. or less by differential thermal analysis. It has a peak and the interplanar spacing (d 002 ) of the (002) plane of the graphite structure is 0.370 nm.
Less, the crystallite size (Lc) in the C-axis direction is 3.0 nm
Below, the true density is 1.7 g / cm 3. As described above, the lithium secondary battery is characterized in that the orientation of the fine structure is random.
JP04832992A 1991-07-29 1992-03-05 Lithium secondary battery Expired - Lifetime JP3727666B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP04832992A JP3727666B2 (en) 1991-07-29 1992-03-05 Lithium secondary battery

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP18799991 1991-07-29
JP3-187999 1991-07-29
JP04832992A JP3727666B2 (en) 1991-07-29 1992-03-05 Lithium secondary battery

Publications (2)

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JPH0589879A true JPH0589879A (en) 1993-04-09
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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0624913A3 (en) * 1993-03-30 1995-02-15 Sanyo Electric Co Lithium secondary battery.
US5985489A (en) * 1995-06-20 1999-11-16 Nippon Sanso Corporation Carbon for a lithium secondary battery, lithium secondary battery, and manufacturing methods therefor
EP0987781A2 (en) * 1996-05-27 2000-03-22 SANYO ELECTRIC Co., Ltd. Non-aqueous electrolyte battery
JP2002093406A (en) * 2000-09-18 2002-03-29 At Battery:Kk Nonaqueous electrolyte secondary battery
WO2007040007A1 (en) * 2005-09-09 2007-04-12 Kureha Corporation Negative electrode material for nonaqueous electrolyte secondary battery, process for producing the same, negative electrode and nonaqueous electrolyte secondary battery
WO2013157620A1 (en) * 2012-04-19 2013-10-24 株式会社 日立製作所 Negative electrode active material for lithium ion secondary battery and lithium ion secondary battery
JP2014116155A (en) * 2012-12-07 2014-06-26 Hitachi Chemical Co Ltd Negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, lithium ion secondary battery, and method for producing negative electrode material for lithium ion secondary battery
KR20170054839A (en) * 2015-11-10 2017-05-18 삼성에스디아이 주식회사 Negative electrode for a rechargeable lithium battery and rechargeable lithium battery comprising same
JP2019091651A (en) * 2017-11-16 2019-06-13 日産自動車株式会社 Nonaqueous electrolyte secondary battery

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0624913A3 (en) * 1993-03-30 1995-02-15 Sanyo Electric Co Lithium secondary battery.
US6447955B1 (en) 1993-03-30 2002-09-10 Sanyo Electric Co., Ltd. Lithium secondary battery with a negative electrode of heat-treated natural graphite
US5985489A (en) * 1995-06-20 1999-11-16 Nippon Sanso Corporation Carbon for a lithium secondary battery, lithium secondary battery, and manufacturing methods therefor
EP0987781A3 (en) * 1996-05-27 2008-05-28 SANYO ELECTRIC Co., Ltd. Non-aqueous electrolyte battery
EP0987781A2 (en) * 1996-05-27 2000-03-22 SANYO ELECTRIC Co., Ltd. Non-aqueous electrolyte battery
JP2002093406A (en) * 2000-09-18 2002-03-29 At Battery:Kk Nonaqueous electrolyte secondary battery
WO2007040007A1 (en) * 2005-09-09 2007-04-12 Kureha Corporation Negative electrode material for nonaqueous electrolyte secondary battery, process for producing the same, negative electrode and nonaqueous electrolyte secondary battery
JPWO2007040007A1 (en) * 2005-09-09 2009-04-16 株式会社クレハ Negative electrode material for non-aqueous electrolyte secondary battery, method for producing the same, and negative electrode and non-aqueous electrolyte secondary battery
US7858239B2 (en) 2005-09-09 2010-12-28 Kureha Corporation Negative electrode material for non-aqueous electrolyte secondary battery, process for producing the same, negative electrode, and non-aqueous electrolyte secondary battery
JP5065901B2 (en) * 2005-09-09 2012-11-07 株式会社クレハ Negative electrode material for non-aqueous electrolyte secondary battery, method for producing the same, and negative electrode and non-aqueous electrolyte secondary battery
WO2013157620A1 (en) * 2012-04-19 2013-10-24 株式会社 日立製作所 Negative electrode active material for lithium ion secondary battery and lithium ion secondary battery
JP2013222681A (en) * 2012-04-19 2013-10-28 Hitachi Chemical Co Ltd Negative electrode active material for lithium ion secondary battery, and lithium ion secondary battery
JP2014116155A (en) * 2012-12-07 2014-06-26 Hitachi Chemical Co Ltd Negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, lithium ion secondary battery, and method for producing negative electrode material for lithium ion secondary battery
KR20170054839A (en) * 2015-11-10 2017-05-18 삼성에스디아이 주식회사 Negative electrode for a rechargeable lithium battery and rechargeable lithium battery comprising same
JP2019091651A (en) * 2017-11-16 2019-06-13 日産自動車株式会社 Nonaqueous electrolyte secondary battery

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