JPH10255794A - Lithium secondary battery, its positive electrode active material and manufacture of the active material - Google Patents

Lithium secondary battery, its positive electrode active material and manufacture of the active material

Info

Publication number
JPH10255794A
JPH10255794A JP9054406A JP5440697A JPH10255794A JP H10255794 A JPH10255794 A JP H10255794A JP 9054406 A JP9054406 A JP 9054406A JP 5440697 A JP5440697 A JP 5440697A JP H10255794 A JPH10255794 A JP H10255794A
Authority
JP
Japan
Prior art keywords
active material
positive electrode
electrode active
lif
secondary battery
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
JP9054406A
Other languages
Japanese (ja)
Other versions
JP3397070B2 (en
Inventor
Kenji Nakai
賢治 中井
Masayuki Takashima
正之 高島
Susumu Yonezawa
晋 米沢
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.)
Resonac Corp
Original Assignee
Shin Kobe Electric Machinery Co Ltd
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Filing date
Publication date
Application filed by Shin Kobe Electric Machinery Co Ltd filed Critical Shin Kobe Electric Machinery Co Ltd
Priority to JP05440697A priority Critical patent/JP3397070B2/en
Publication of JPH10255794A publication Critical patent/JPH10255794A/en
Application granted granted Critical
Publication of JP3397070B2 publication Critical patent/JP3397070B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

Abstract

PROBLEM TO BE SOLVED: To provide positive electrode material for a lithium secondary battery with a high energy density, by making a specific proportion of at least one kind selected from Fe, Co, Ni or Ti, and Li contained as main ingredients, and making LiF contained in its active material particle. SOLUTION: Positive electrode material which contains LiMxOy (M is at least one kind selected from Fe, Co, Ni or Ti, and x=0.97-1.03, y=1.94-2.06), shown as a general formula, as an ingredient, and LiF in its active material particle, is made by baking lithium carbonate, hydroxide of metal selected form Fe, Co, Ni or Ti and LiF in the air. Positive electrode material which contains LiMnα Oβ(α=1.97-2.03, β=3.94-4.06) shown as a general formula, as a main ingredient, and LiF in its active material particle is made by baking lithium cabonate, a hydroxide of Mn and LiF in the air. Thereby, positive electrode active material for a lithium secondary battery with a high energy density is obtained.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【0001】[0001]

【発明の属する技術分野】本発明はリチウム二次電池及
びその正極活物質ならびに正極活物質の製造法に関する
ものである。
The present invention relates to a lithium secondary battery, a positive electrode active material thereof, and a method for producing a positive electrode active material.

【0002】[0002]

【従来の技術】負極活物質に金属リチウムを用いたリチ
ウム二次電池は、充電時にデンドライト状リチウムが析
出して正極と接触し内部短絡を起こしたり、金属リチウ
ムの化学的活性度が高いために安全性が低下する心配が
ある。そこで負極活物質として充電、放電に伴い、リチ
ウムを吸蔵、放出することのできる炭素質物が用いられ
るようになってきている。また正極活物質には、リチウ
ムを含有した遷移金属の酸化物が主に用いられている。
具体的には、高い電極電位と大きな放電容量を有し、空
気中で比較的安定なLiCoO2(コバルト酸リチウ
ム)である。上記炭素質物からなる負極活物質と上記正
極活物質とを、それぞれ完全放電状態で電池を組み立
て、初充電によって電池としての機能を付与している。
2. Description of the Related Art Lithium secondary batteries using metallic lithium as a negative electrode active material are disadvantageous in that, during charging, dendritic lithium precipitates and comes into contact with the positive electrode to cause an internal short circuit, or because of the high chemical activity of metallic lithium. There is a concern that safety will decrease. Therefore, as a negative electrode active material, a carbonaceous material capable of inserting and extracting lithium has been used with charge and discharge. As the positive electrode active material, an oxide of a transition metal containing lithium is mainly used.
Specifically, it is LiCoO 2 (lithium cobalt oxide) which has a high electrode potential and a large discharge capacity and is relatively stable in air. The battery is assembled in a completely discharged state using the negative electrode active material made of the carbonaceous material and the positive electrode active material, and a function as a battery is given by initial charging.

【0003】このような構成のリチウム二次電池は、高
エネルギー密度であるメリットを活かして、主にVTR
カメラやノートパソコン、携帯電話等のポータブル機器
に使用されている。パソコンのCPUの高速化に伴う消
費電力の増大、その他ポータブル機器の連続使用時間の
延長を目的とした、民生用電池への高エネルギー密度化
の要望は留まるところがない。その要望に応じるべく、
正極活物質、負極活物質ともに高エネルギー密度化の開
発が急ピッチで進められている。とりわけ正極活物質
は、現状で145〜150mAh/gの能力しか持たな
いLiCoO2に代わって、180〜200mAh/g
の能力を持つとされるLiNiO2や、Niの一部をC
o等の他の元素と置換したLiNiaCob2(a+b
=0.97〜1.03)が開発されている。しかしこれ
らは充放電サイクル初期の容量低下が大きいことや、L
iNiOや、LiNiCob2の吸湿による性能低
下を避けるために製造工程を除湿しなければならず、コ
スト高となってしまうことで実用化には至っていない。
このような理由からLiCoO2をモデファイすること
で高エネルギー密度化を図る提案がなされている。例え
ば特許第2526705号公報では、炭酸リチウムと、
炭酸コバルトとを出発物質とし、Li/Coのモル比を
1として混合、空気中で焼成後、冷却速度をコントロー
ルすることを提案している。そうすることで、LiCo
2の(003)面のX線回折ピーク強度を100とし
た場合の(101)面の強度が5〜15となる。すると
正極活物質は高エネルギー密度となり、しかも優れた充
放電サイクル特性を有することとなる。(この場合(1
01)面のX線回折ピーク強度を1とした場合の(00
3)面のX線回折ピーク強度は6.67から20の範囲
となる。)
[0003] Lithium secondary batteries having such a structure are mainly used in VTRs, taking advantage of their high energy density.
It is used in portable devices such as cameras, notebook computers, and mobile phones. There is no end to the demand for higher energy densities in consumer batteries for the purpose of increasing power consumption with the speeding up of the CPU of personal computers and extending the continuous use time of portable devices. To meet that request,
The development of high energy densities for both the positive electrode active material and the negative electrode active material is being promoted at a rapid pace. In particular, the positive electrode active material is replaced with LiCoO 2 which has a capacity of only 145 to 150 mAh / g at present, and 180 to 200 mAh / g.
LiNiO 2 , which is said to have the ability of
LiNi a Co b O 2 substituted with another element such as o (a + b
= 0.97 to 1.03). However, these have a large capacity decrease at the beginning of the charge / discharge cycle,
The manufacturing process must be dehumidified in order to avoid performance degradation due to moisture absorption of iNiO 2 or LiNi a Co b O 2 , and the cost has been increased, so that it has not been put to practical use.
For these reasons, proposals have been made to increase the energy density by modifying LiCoO 2 . For example, in Japanese Patent No. 2526705, lithium carbonate and
It is proposed that cobalt carbonate is used as a starting material, the molar ratio of Li / Co is 1, mixed, calcined in air, and the cooling rate controlled. By doing so, LiCo
Assuming that the X-ray diffraction peak intensity of the (003) plane of O 2 is 100, the intensity of the (101) plane is 5 to 15. Then, the positive electrode active material has a high energy density and excellent charge / discharge cycle characteristics. (In this case (1
(00) when the X-ray diffraction peak intensity of the (01) plane is 1
3) The X-ray diffraction peak intensity of the surface ranges from 6.67 to 20. )

【0004】[0004]

【発明が解決しようとする課題】しかし、焼成前の出発
物質の一つである炭酸コバルトは高純度品が入手しにく
く、組成が安定しない等の理由から、出発物質には水酸
化コバルトが相応しい。ところが、水酸化コバルトを原
料として焼成すると高エネルギー密度のLiCoO2
得られない。このような現実は、LiCoO2のみなら
ず、一般式LiMxy(Mは、Fe、Co、Ni、Ti
から選ばれる少なくとも1種であり、x=0.97〜
1.03、y=1.94〜2.06)、あるいは一般式
LiMnαβ(α=1.97〜2.03、β=3.9
4〜4.06)で表される正極活物質に共通して抱えて
いる問題である。特に前記MがNiの場合、すなわちL
iNixyを正極活物質として用いた電池では、初期充
放電サイクルでの容量低下が大きな課題である。そこで
本発明が解決しようとする課題は、一般式LiMx
y(Mは、Fe、Co、Ni、Tiから選ばれる少なく
とも1種であり、x=0.97〜1.03、y=1.9
4〜2.06)や、一般式LiMnαβ(α=1.9
7〜2.03、β=3.94〜4.06)を主体とする
リチウム二次電池用正極活物質を高エネルギー密度化す
ることである。また、Fe、Co、Ni、Ti、Mnの
炭酸塩を出発物質に用いずに、一般式LiMxy(M
は、Fe、Co、Ni、Tiから選ばれる少なくとも1
種であり、x=0.97〜1.03、y=1.94〜
2.06)や、一般式LiMnαβ(α=1.97〜
2.03、β=3.94〜4.06)を主体とする高エ
ネルギー密度のリチウム二次電池用正極活物質を得るこ
とである。
However, cobalt carbonate, which is one of the starting materials before calcination, is difficult to obtain in high purity and its composition is not stable. Therefore, cobalt hydroxide is suitable as the starting material. . However, when firing is performed using cobalt hydroxide as a raw material, LiCoO 2 having a high energy density cannot be obtained. Such a reality is caused not only by LiCoO 2 but also by the general formula LiM x O y (M is Fe, Co, Ni, Ti
X = 0.97-
1.03, y = 1.94~2.06), or the general formula LiMn α O β (α = 1.97~2.03 , β = 3.9
4 to 4.06). In particular, when M is Ni, ie, L
In a battery using iNi x O y as a positive electrode active material, a major problem is a reduction in capacity in an initial charge / discharge cycle. The problem to be solved by the present invention is to solve the general formula LiM x O
y (M is at least one selected from Fe, Co, Ni and Ti, x = 0.97 to 1.03, y = 1.9
4 to 2.06) and the general formula LiMn α O β (α = 1.9)
7 to 2.03, β = 3.94 to 4.06) is to increase the energy density of the positive electrode active material for a lithium secondary battery. Further, without using carbonates of Fe, Co, Ni, Ti and Mn as starting materials, the general formula LiM x O y (M
Is at least one selected from Fe, Co, Ni and Ti
X = 0.97 to 1.03, y = 1.94-
2.06) and the general formula LiMn α O β (α = 1.97-
2.03, β = 3.94 to 4.06) to obtain a high energy density positive electrode active material for a lithium secondary battery.

【0005】[0005]

【課題を解決するための手段】上記課題を解決するため
に本発明のリチウム二次電池用正極活物質は、一般式L
iMxy(Mは、Fe、Co、Ni、Tiから選ばれる
金属の少なくとも1種であり、x=0.97〜1.0
3、y=1.94〜2.06)を主たる成分とし、Li
Fを活物質粒子中に含有していることを特徴とする。上
記正極活物質を作製するには、炭酸リチウムと、Fe、
Co、Ni、Tiから選ばれる少なくとも1種の水酸化
物と、LiFとを空気中で焼成することが一つの手段と
して挙げられる。
Means for Solving the Problems In order to solve the above problems, a positive electrode active material for a lithium secondary battery according to the present invention has a general formula L
iM x O y (M is at least one kind of metal selected from Fe, Co, Ni and Ti, and x = 0.97 to 1.0
3, y = 1.94 to 2.06) as the main component and Li
It is characterized in that F is contained in the active material particles. To produce the positive electrode active material, lithium carbonate, Fe,
Firing at least one kind of hydroxide selected from Co, Ni, and Ti and LiF in the air is one example.

【0006】上記課題を解決するための本発明の別のリ
チウム二次電池用正極活物質は、一般式LiMnαβ
(α=1.97〜2.03、β=3.94〜4.06)
を主たる成分とし、LiFを活物質粒子中に含有してい
る正極活物質を用いたことを特徴とする。上記正極活物
質を作製するには、炭酸リチウムと、Mnの水酸化物
と、LiFを空気中で焼成することが一つの手段として
挙げられる。
Another positive electrode active material for a lithium secondary battery according to the present invention for solving the above-mentioned problems is represented by a general formula LiMn α O β
(Α = 1.97 to 2.03, β = 3.94 to 4.06)
And a positive electrode active material containing LiF in the active material particles is used. In order to produce the above-mentioned positive electrode active material, as one means, calcining lithium carbonate, a hydroxide of Mn, and LiF in air is mentioned.

【0007】上記一般式LiMxy又はLiMnαβ
で表される正極活物質を作製するに際し、炭酸リチウム
とMあるいはMnの水酸化物、さらには比較的微量のL
iFを併せて混合、焼成することで、比較的微量のLi
Fを正極活物質粒子中に含有し、それにより強い結晶配
向性を有する正極活物質が得られるものと考えられる。
また上記比較的微量のLiFの作用により、従来問題視
されていたCo等の水酸化物を出発物質に使用した際
の、正極活物質の低エネルギー密度化を避けることがで
きる。
The general formula LiM x O y or LiMn α O β
In preparing the positive electrode active material represented by the formula, lithium carbonate and a hydroxide of M or Mn, and a relatively small amount of L
By mixing and firing iF together, a relatively small amount of Li
It is considered that F is contained in the positive electrode active material particles, whereby a positive electrode active material having strong crystal orientation is obtained.
Further, by the action of the above-mentioned relatively small amount of LiF, it is possible to avoid a decrease in the energy density of the positive electrode active material when a hydroxide such as Co, which has been conventionally regarded as a problem, is used as a starting material.

【0008】前述した特許第2526750号公報の記
載(段落番号0007)では、結晶がc軸方向へ広がり
すぎると((003)面に対する(101)面のX線回折線
のピーク強度が5を下回ると)、エネルギー密度は増大
するが、充電時の結晶構造の変化の絶対量が大きくなる
ため可逆性、つまり充放電サイクル特性が低下するとあ
る。しかしながら本発明の構成を備えることで、結晶が
c軸方向へ広がりすぎた場合でも優れた充放電サイクル
特性が得られる。これは正極活物質粒子中に含有された
LiFが、結晶維持剤として作用しているためと考えら
れる。特に前述した一般式中のMがCoである場合は、
(003)面及び(006)面のX線回折線のピーク強度が
LiFの有無により大きく異なってくる。つまりLiF
が正極活物質粒子中に存在した場合、存在しない場合よ
りも前記ピーク強度は大きくなる。他の回折ピーク強度
は殆ど変化しないため、c軸方向へ発達した正極活物質
が得られていることがわかる。
According to the description of Japanese Patent No. 2526750 (paragraph 0007), when the crystal is too wide in the c-axis direction, the peak intensity of the X-ray diffraction line of the (101) plane with respect to the (003) plane falls below 5. ), The energy density increases, but the reversibility, that is, the charge / discharge cycle characteristics, deteriorates because the absolute amount of change in the crystal structure during charging increases. However, with the configuration of the present invention, excellent charge / discharge cycle characteristics can be obtained even when the crystals are too wide in the c-axis direction. This is presumably because LiF contained in the positive electrode active material particles acts as a crystallization maintaining agent. In particular, when M in the above general formula is Co,
The peak intensities of the X-ray diffraction lines of the (003) plane and the (006) plane greatly differ depending on the presence or absence of LiF. That is, LiF
Is present in the positive electrode active material particles, the peak intensity is higher than in the absence thereof. Since other diffraction peak intensities hardly change, it is understood that a positive electrode active material developed in the c-axis direction is obtained.

【0009】本発明に係る上記した比較的微量のLiF
は、特開平8−264183号公報で提案しているよう
な、正極活物質粒子表面を被覆する状態で存在していな
い。正極活物質粒子表面を、導電性の低いLiFで被覆
してしまうと、充放電反応を阻害する抵抗体として作用
することが懸念される。本発明の構成では、多少のLi
Fが正極活物質粒子表面に存在している箇所はあると考
えられるが、充放電を阻害する程度の量を有さない。ま
た上記公報の発明の構成を備えるには、正極活物質とL
iOHとを混合熱処理して活物質表面をLiOHで被覆
し、その後フッ素ガスあるいはフッ化窒素ガス中に曝す
処理を施すとしている。フッ素ガスやフッ化窒素ガスは
人体に有害である。その上、上記処理は正極活物質作製
後に施す必要があるため製造工程が煩雑である。本発明
では有害なガスを用いることもなく、正極活物質作製時
にLiFを正極活物質粒子中に含有させることができる
ため製造工程も煩雑にならない。
The relatively small amount of LiF according to the present invention
Does not exist in a state of covering the surface of the positive electrode active material particles as proposed in JP-A-8-264183. If the surface of the positive electrode active material particles is coated with LiF having low conductivity, there is a concern that the surface may function as a resistor that inhibits a charge / discharge reaction. In the configuration of the present invention, some Li
Although it is considered that there is a portion where F exists on the surface of the positive electrode active material particles, it does not have an amount that hinders charging and discharging. Further, in order to provide the configuration of the invention of the above publication, the positive electrode active material and L
The surface of the active material is coated with LiOH by performing a mixed heat treatment with iOH, and thereafter, a treatment of exposing the active material to a fluorine gas or a nitrogen fluoride gas is performed. Fluorine gas and nitrogen fluoride gas are harmful to the human body. In addition, since the above-mentioned treatment needs to be performed after the preparation of the positive electrode active material, the production process is complicated. In the present invention, since no harmful gas is used and LiF can be contained in the positive electrode active material particles at the time of preparing the positive electrode active material, the production process is not complicated.

【0010】特開平8−190909号公報では、Li
CoO2等の正極活物質を焼成により作製するに際し、
出発物質としてLiFを使用することができるという記
載がある(段落番号0010)。上記正極活物質を作製
するに際しそのリチウム供給源としてLiFを単独で使
用すると、十分に焼成が進行しない、目的とする活物質
が得られない。さらには過剰な量のLiFが正極活物質
粒子中に含有される、及び/又は正極活物質粒子表面を
LiFが覆う、あるいはLiF単体として残留し、正極
活物質粒子同士の電気的接触を阻害する形で存在するお
それがある。上記した、過剰な量のLiFが正極活物質
粒子中に含有されると、正極活物質のc軸方向への発達
が阻害されるおそれがある。従って正極活物質中に含有
されるLiFは極端に過剰な量であるべきでない。好ま
しくは正極活物質重量に対し0.002〜5ppmであ
る。そのような正極活物質を得るには、焼成される出発
物質の総量に対してLiFを1〜10重量%とする。
JP-A-8-190909 discloses that Li
When producing a positive electrode active material such as CoO 2 by firing,
There is a description that LiF can be used as a starting material (paragraph 0010). When LiF is used alone as the lithium supply source when producing the above-mentioned positive electrode active material, the firing does not proceed sufficiently and the desired active material cannot be obtained. Further, an excessive amount of LiF is contained in the positive electrode active material particles, and / or the surface of the positive electrode active material particles is covered with LiF, or remains as LiF alone, and inhibits electrical contact between the positive electrode active material particles. May exist in form. When an excessive amount of LiF is contained in the positive electrode active material particles, the development of the positive electrode active material in the c-axis direction may be hindered. Therefore, LiF contained in the positive electrode active material should not be excessively large. Preferably, it is 0.002 to 5 ppm based on the weight of the positive electrode active material. In order to obtain such a positive electrode active material, LiF is set to 1 to 10% by weight based on the total amount of the starting material to be fired.

【0011】[0011]

【発明の実施の形態】以下に本発明の実施の形態の一例
について図面を参照しながら説明する。図1は本発明を
実施したリチウム二次電池用試験セルの断面図である。
1は正極集電体で厚さ20μmのアルミニウム箔であ
る。平面サイズは直径20mmである。2は正極活物質
層で、後述する方法で調整した正極活物質LiCoO2
と、導電助剤であるグラファイト(日本黒鉛工業製SP
270)と、バインダーであるポリフッ化ビニリデン
(PVDF:クレハ化学工業製、KF#1100)と、
電解液とから構成される。正極活物質層2の作製方法を
記す。所定の方法で調整したLiCoO2(平均粒径約5
〜15μm)とグラファイト(平均粒径約0.5μm)
とPVDFを重量比で85:10:5に十分混合し、そ
こへ分散溶媒となるN−メチル−2−ピロリドンを適量
加え、十分に混練、分散させ、インク状にする。この混
練物をロールtoロールの転写により正極集電体1の両
面に塗着、乾燥、圧延し、正極活物質層2を得る。正極
活物質層2の厚さは75μmである。LiCoO2の作
製法を詳細に説明する。出発物質としての炭酸リチウム
と水酸化コバルトとを混合する。炭酸リチウムと水酸化
コバルトの量はLi/Coのモル比が1となるようにす
る。LiF量は全出発物質重量に対し5wt%とした。
これらを混合したものを空気中900℃で5〜20時間
焼成する。その後100℃/hの冷却速度で室温まで冷
却する。こうしてLiCoO2を得る。上記方法により
得られたLiCoO2は厳密に表現すると、一般式Li
Coxy(x=0.97〜1.03、y=1.94〜
2.06)程度の範囲のものとなる。これは一般式Li
xy(Mは、Fe、Co、Ni、Tiから選ばれる少
なくとも1種)である場合も同様である。上記したLi
CoO2の製造に際し、水酸化コバルトに代えて水酸化
マンガンを用い、炭酸リチウムと水酸化マンガンの量が
Li/Mnのモル比が0.5となるようにした場合、一
般式LiMnαβ(α=1.97〜2.03、β=
3.94〜4.06)が得られる。
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a test cell for a lithium secondary battery embodying the present invention.
Reference numeral 1 denotes a positive electrode current collector, which is an aluminum foil having a thickness of 20 μm. The plane size is 20 mm in diameter. Reference numeral 2 denotes a positive electrode active material layer, which is a positive electrode active material LiCoO 2 prepared by a method described later.
And graphite as a conductive additive (SP made by Nippon Graphite Industries, Ltd.)
270) and polyvinylidene fluoride as binder (PVDF: KF # 1100 manufactured by Kureha Chemical Industry Co., Ltd.)
And an electrolytic solution. A method for forming the positive electrode active material layer 2 will be described. LiCoO 2 (average particle size of about 5
~ 15μm) and graphite (average particle size about 0.5μm)
And PVDF are sufficiently mixed in a weight ratio of 85: 10: 5, and an appropriate amount of N-methyl-2-pyrrolidone as a dispersion solvent is added thereto, and the mixture is sufficiently kneaded and dispersed to form an ink. The kneaded material is applied to both surfaces of the positive electrode current collector 1 by roll-to-roll transfer, dried, and rolled to obtain the positive electrode active material layer 2. The thickness of the positive electrode active material layer 2 is 75 μm. The method for producing LiCoO 2 will be described in detail. Mix lithium carbonate and cobalt hydroxide as starting materials. The amounts of lithium carbonate and cobalt hydroxide are such that the molar ratio of Li / Co is 1. The LiF amount was 5 wt% based on the total weight of the starting materials.
A mixture of these is fired in air at 900 ° C. for 5 to 20 hours. Then, it is cooled to room temperature at a cooling rate of 100 ° C./h. Thus, LiCoO 2 is obtained. Strictly speaking, LiCoO 2 obtained by the above method is represented by the general formula Li
Co x O y (x = 0.97 to 1.03, y = 1.94 to
2.06). This is the general formula Li
M x O y (M is, Fe, Co, Ni, at least one selected from Ti) is the same when it is. Li mentioned above
In producing CoO 2 , when manganese hydroxide is used instead of cobalt hydroxide and the amount of lithium carbonate and manganese hydroxide is adjusted so that the molar ratio of Li / Mn is 0.5, the general formula LiMn α O β (Α = 1.97 to 2.03, β =
3.94 to 4.06) are obtained.

【0012】3は直径21mm負極活物質層で、厚さ
0.1mmの金属リチウムである。4はセパレータで、厚
さ25μmの微多孔性のポリエチレンフィルムである。
負極活物質層である金属リチウムをステンレススチール
製負極セル容器5の底中央部に圧着しその上にセパレー
タ4を配置し、さらにその上から正極集電体1と正極活
物質層2の一体化物を正極活物質層2の面がセパレータ
4側にくるように乗せる。ステンレススチール製負極セ
ル容器5の円周部内側には四フッ化エチレン樹脂製のイ
ンシュレータ6を配置し、有機電解液(1M LiPF
6が溶解されたプロピレンカーボネートとジメチルカー
ボネートの体積比1対1混合物)約2mlを注入後、そ
の内側にアルミニウム加圧治具7をねじ込む。ステンレ
ススチール製負極セル容器5とインシュレータ6の間、
インシュレータ6とアルミニウム加圧治具7の間にはセ
ル内の密閉を保つためO−リング8が挟まれている。
尚、ステンレススチール製負極セル容器5にはセル組立
時の気体抜きのために貫通孔9が設けられ、その外側開
口部は、セル組立終了時にストップ栓10でセル内の密
閉を保つ。
Reference numeral 3 denotes a negative electrode active material layer having a diameter of 21 mm, which is metallic lithium having a thickness of 0.1 mm. Reference numeral 4 denotes a separator, which is a microporous polyethylene film having a thickness of 25 μm.
Metal lithium, which is a negative electrode active material layer, is pressed against the center of the bottom of a stainless steel negative electrode cell container 5, a separator 4 is disposed thereon, and further a positive electrode current collector 1 and a positive electrode active material layer 2 are integrated therefrom. Is placed so that the surface of the positive electrode active material layer 2 faces the separator 4 side. An insulator 6 made of tetrafluoroethylene resin is disposed inside a circumferential portion of the stainless steel negative electrode cell container 5, and an organic electrolyte (1M LiPF) is provided.
After injecting about 2 ml of a 1: 1 mixture of propylene carbonate and dimethyl carbonate in which 6 has been dissolved (1: 1 volume ratio), an aluminum pressing jig 7 is screwed into the inside. Between the stainless steel negative electrode cell container 5 and the insulator 6,
An O-ring 8 is interposed between the insulator 6 and the aluminum pressing jig 7 to keep the inside of the cell tight.
The stainless steel negative electrode cell container 5 is provided with a through hole 9 for venting gas at the time of cell assembly, and the outer opening of the cell is kept closed by a stop plug 10 at the end of cell assembly.

【0013】本セルは実験を正確に実施する目的で設計
されたものである。従って、民生用のリチウム二次電池
の形状にはなりにくいと思われる。しかし本発明は電池
の形状や大きさ等を問わず適用可能である。例えば正極
と負極をセパレータを介し渦巻き状に捲回し、円筒形の
電池容器に収納した形状、正極と負極がセパレータを挟
んで直接接触しないよう積層され、角形容器に収納され
た形状等である。また本セルでは負極に金属リチウムを
用いているが、負極活物質として充電、放電に伴い、リ
チウムを吸蔵、放出することのできる材料、例えば炭素
質物、金属酸化物等も当然使用することができる。
This cell is designed for the purpose of conducting experiments accurately. Therefore, it is considered that the shape of the lithium secondary battery for consumer use is hardly obtained. However, the present invention is applicable regardless of the shape and size of the battery. For example, the positive electrode and the negative electrode may be spirally wound with a separator interposed therebetween and housed in a cylindrical battery container, or may be stacked so that the positive electrode and the negative electrode are not directly in contact with the separator interposed therebetween and housed in a rectangular container. In the present cell, metallic lithium is used for the negative electrode. However, as the negative electrode active material, a material capable of inserting and extracting lithium with charge and discharge, for example, a carbonaceous material, a metal oxide, and the like can also be used. .

【0014】[0014]

【実施例】上記した発明の実施の形態でのセルにおい
て、正極活物質の出発物質であるLiF量を、全出発物
質に対して0.5重量%、1重量%、3重量%、5重量
%、10重量%、15重量%とした実施例1〜6のセ
ル、及びLiFを全く使用しない従来例のセルについて
以下の実験を実施した。
EXAMPLES In the cell according to the embodiment of the present invention, the amount of LiF, which is a starting material of a positive electrode active material, was adjusted to 0.5% by weight, 1% by weight, 3% by weight, and 5% by weight based on all starting materials. %, 10% by weight, and 15% by weight, and the following experiments were performed on the cells of Examples 1 to 6 and the cell of the conventional example using no LiF at all.

【0015】(実験1)実施例1〜6及び従来例のセル
に用いる正極活物質LiCoO2について、X線回折分
析を実施した。その結果、いかなるLiF量においても
ピーク位置のシフトは全く見られなかった。LiFの混
合量が増えるに従って(003)面と(006)面のX
線回折ピーク強度が大きくなる。実施例1〜実施例6の
セルに用いた正極活物質は、従来例に比して結晶がc軸
方向に発達した構造であることを確認した。特に実施例
2〜実施例4のセルに用いた正極活物質は、さらにc軸
方向に発達した構造であることがわかった。LiF量が
全出発物質に対して5重量%を超えて作製された実施例
5、実施例6に用いられる正極活物質の前記X線回折ピ
ーク強度は減少し始める。従って正極活物質粒子中に含
有されるLiF量が多くなりすぎるとかえってc軸方向
への結晶の発達を阻害することがわかった。回折パター
ンからはLiF単独のピークは見られないが、焼成前後
の重量変化量から正極活物質粒子中にはLiFが含有さ
れていることは明らかである。またLiFはXPS分析
においても検出されている。
(Experiment 1) The positive electrode active material LiCoO 2 used in the cells of Examples 1 to 6 and the conventional example was subjected to X-ray diffraction analysis. As a result, no shift in the peak position was observed at any LiF amount. As the mixing amount of LiF increases, the X of the (003) plane and the (006) plane
The line diffraction peak intensity increases. It was confirmed that the positive electrode active materials used in the cells of Examples 1 to 6 had a structure in which crystals developed in the c-axis direction as compared with the conventional example. In particular, it was found that the positive electrode active materials used in the cells of Examples 2 to 4 had a structure further developed in the c-axis direction. The X-ray diffraction peak intensity of the positive electrode active materials used in Examples 5 and 6 prepared in which the amount of LiF exceeds 5% by weight based on all starting materials starts to decrease. Therefore, it was found that when the amount of LiF contained in the positive electrode active material particles was too large, the development of crystals in the c-axis direction was rather inhibited. Although no peak of LiF alone is seen from the diffraction pattern, it is clear from the weight change before and after firing that LiF is contained in the positive electrode active material particles. LiF has also been detected by XPS analysis.

【0016】(実験2)実施例1〜6及び従来例のセル
について充放電試験を実施した。セルの充放電条件は、
充電:4.2V定電圧、制限電流3mA、5h、25
℃、放電:3mA、終止電圧3.0V、25℃とした。
実施例1〜6及び従来例のセルの初回充放電容量、充電
量に対する放電効率(充放電効率)、容量維持率を表1
に示した。容量維持率は、以下の式から算出した。 また表1にはフッ素電極によるフッ素定量で求めた、正
極活物質中のLiF量(LiF含有量)及び正極活物質
製造時の全出発物質に対するLiF量(LiF混合量)
も併せて示した。前記フッ素定量法を詳しく説明する
と、正極活物質を塩酸に溶解させ、その溶液にORIO
N複合型フッ素電極96−09型を挿入して、予め検量
線を入力してあるORION SA720型メーターに
て数値を読みとる(一般のガラス電極を用いたpHメー
ターと同様の使用方式)方法である。
(Experiment 2) A charge / discharge test was performed on the cells of Examples 1 to 6 and the conventional example. Cell charging and discharging conditions are as follows:
Charge: 4.2V constant voltage, limited current 3mA, 5h, 25
° C, discharge: 3 mA, final voltage 3.0 V, and 25 ° C.
Table 1 shows the initial charge / discharge capacity, the discharge efficiency (charge / discharge efficiency) with respect to the charged amount, and the capacity retention rate of the cells of Examples 1 to 6 and the conventional example.
It was shown to. The capacity retention rate was calculated from the following equation. Table 1 shows the amount of LiF in the positive electrode active material (LiF content) and the amount of LiF with respect to all starting materials during the production of the positive electrode active material (LiF mixed amount), which were determined by fluorine determination using a fluorine electrode.
Are also shown. To explain the fluorine determination method in detail, the positive electrode active material is dissolved in hydrochloric acid, and ORIO is added to the solution.
This is a method in which an N-composite fluorine electrode 96-09 is inserted, and a numerical value is read by an ORION SA720 type meter in which a calibration curve is input in advance (the same use method as a pH meter using a general glass electrode). .

【0017】[0017]

【表1】 [Table 1]

【0018】表1から明らかなように、実施例1〜6の
セルは従来例のセルに比して充放電効率、容量保存率と
もに優れていることがわかる。
As is clear from Table 1, the cells of Examples 1 to 6 are superior to the cells of the conventional examples in both charge / discharge efficiency and capacity retention.

【0019】本実施例ではリチウム二次電池の正極活物
質にLiFを活物質粒子中に含有しているLiCoO2
のみについて記載したが、一般式LiMxy(Mは、F
e、Co、Ni、Tiから選ばれる少なくとも1種であ
り、x=0.97〜1.03、y=1.94〜2.0
6)あるいは一般式LiMnαβ(α=1.97〜
2.03、β=3.94〜4.06)であり、LiFを
活物質粒子中に含有していれば、本実施例と同様の効果
が得られる。
In this embodiment, LiCoO 2 containing LiF in active material particles is used as a positive electrode active material of a lithium secondary battery.
Only the general formula LiM x O y (M is F
e, at least one selected from Co, Ni, and Ti, x = 0.97 to 1.03, y = 1.94 to 2.0
6) Or LiMn α O β (α = 1.97-
2.03, β = 3.94 to 4.06), and if LiF is contained in the active material particles, the same effect as that of the present example can be obtained.

【0020】[0020]

【発明の効果】本発明により、Fe、Co、Ni、T
i、Mnの炭酸塩を出発物質に用いずに高エネルギー密
度を有するリチウム二次電池用正極活物質を得ることが
できた。また、一般式LiMxy(Mは、Fe、Co、
Ni、Tiから選ばれる少なくとも1種であり、x=
0.97〜1.03、y=1.94〜2.06)や、一
般式LiMnαβ(α=1.97〜2.03、β=
3.94〜4.06)を主体とする正極活物質を用いた
リチウム二次電池の高エネルギー密度化を図ることがで
きた。
According to the present invention, Fe, Co, Ni, T
A positive electrode active material for a lithium secondary battery having a high energy density could be obtained without using i and Mn carbonates as starting materials. In addition, a general formula LiM x O y (M is Fe, Co,
At least one selected from Ni and Ti, and x =
0.97 to 1.03, y = 1.94 to 2.06) and the general formula LiMn α O β (α = 1.97 to 2.03, β =
High energy density of a lithium secondary battery using a positive electrode active material mainly composed of 3.94 to 4.06) could be achieved.

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

【図1】本発明のリチウム二次電池の一例の断面図であ
る。
FIG. 1 is a sectional view of an example of a lithium secondary battery of the present invention.

【符号の説明】[Explanation of symbols]

1は正極集電体、2は正極活物質層、3は負極活物質
層、4はセパレータ、5はステンレススチール製負極容
器、6はインシュレータ、7はアルミニウム加圧治具、
8はOーリング、9は貫通孔、10はストップ栓
1 is a positive electrode current collector, 2 is a positive electrode active material layer, 3 is a negative electrode active material layer, 4 is a separator, 5 is a stainless steel negative electrode container, 6 is an insulator, 7 is an aluminum pressing jig,
8 is O-ring, 9 is through hole, 10 is stop stopper

Claims (8)

【特許請求の範囲】[Claims] 【請求項1】一般式LiMxy(Mは、Fe、Co、N
i、Tiから選ばれる少なくとも1種であり、x=0.
97〜1.03、y=1.94〜2.06)を主たる成
分とし、LiFを活物質粒子中に含有しているリチウム
二次電池用正極活物質。
1. The method of claim 1, wherein LiM x O y (M is Fe, Co, N
i, at least one selected from Ti, x = 0.
97 to 1.03, y = 1.94 to 2.06) as a main component, and a positive electrode active material for a lithium secondary battery containing LiF in active material particles.
【請求項2】一般式LiMnαβ(α=1.97〜
2.03、β=3.94〜4.06)を主たる成分と
し、LiFを活物質粒子中に含有しているリチウム二次
電池用正極活物質。
2. The general formula LiMn α O β (α = 1.97-
2.03, β = 3.94 to 4.06) as a main component, and a positive electrode active material for a lithium secondary battery containing LiF in active material particles.
【請求項3】LiF量が正極活物質全重量に対し0.0
02〜5ppmであることを特徴とする請求項1又は2
記載のリチウム二次電池用正極活物質。
3. The amount of LiF is 0.0 to the total weight of the positive electrode active material.
3. The composition according to claim 1, wherein the concentration is from 2 to 5 ppm.
The positive electrode active material for a lithium secondary battery according to the above.
【請求項4】炭酸リチウムと、Fe、Co、Ni、Ti
から選ばれる金属の少なくとも1種の水酸化物と、Li
Fとを空気中で焼成することを特徴とするリチウム二次
電池用正極活物質の製造法。
4. Lithium carbonate, Fe, Co, Ni, Ti
At least one hydroxide of a metal selected from
A method for producing a positive electrode active material for a lithium secondary battery, comprising firing F and air in the air.
【請求項5】炭酸リチウムと、Mnの水酸化物と、Li
Fを空気中で焼成することを特徴とするリチウム二次電
池用正極活物質の製造法。
5. Lithium carbonate, hydroxide of Mn, Li
A method for producing a positive electrode active material for a lithium secondary battery, comprising sintering F in air.
【請求項6】LiF量が、炭酸リチウムと、Fe、C
o、Ni、Tiから選ばれる金属の少なくとも1種の水
酸化物と、LiFの総量に対して1〜10重量%である
ことを特徴とする請求項4記載のリチウム二次電池用正
極活物質の製造法。
6. The method according to claim 1, wherein the amount of LiF is lithium carbonate, Fe, C
5. The positive electrode active material for a lithium secondary battery according to claim 4, wherein the amount is at least one hydroxide of a metal selected from o, Ni, and Ti, and 1 to 10% by weight based on the total amount of LiF. Manufacturing method.
【請求項7】LiF量が、炭酸リチウムと、Mnの水酸
化物と、LiFの総量に対して1〜10重量%であるこ
とを特徴とする請求項5記載のリチウム二次電池用正極
活物質の製造法。
7. The positive electrode active material for a lithium secondary battery according to claim 5, wherein the amount of LiF is 1 to 10% by weight based on the total amount of lithium carbonate, hydroxide of Mn, and LiF. The method of manufacturing the substance.
【請求項8】請求項1〜3のいずれかに記載した正極活
物質を用いたリチウム二次電池。
8. A lithium secondary battery using the positive electrode active material according to claim 1.
JP05440697A 1997-03-10 1997-03-10 Lithium secondary battery, positive electrode active material thereof, and method for producing positive electrode active material Expired - Fee Related JP3397070B2 (en)

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JPH10255794A true JPH10255794A (en) 1998-09-25
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Country Link
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1246279A2 (en) 2001-03-30 2002-10-02 SANYO ELECTRIC Co., Ltd. Nonaqueous electrolytic secondary battery and method of manufacturing the same
US6686096B1 (en) 2000-01-27 2004-02-03 New Billion Investments Limited Rechargeable solid state chromium-fluorine-lithium electric battery
JP2010277929A (en) * 2009-05-29 2010-12-09 Tdk Corp Manufacturing method of active material and electrode and active material and electrode

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6686096B1 (en) 2000-01-27 2004-02-03 New Billion Investments Limited Rechargeable solid state chromium-fluorine-lithium electric battery
EP1246279A2 (en) 2001-03-30 2002-10-02 SANYO ELECTRIC Co., Ltd. Nonaqueous electrolytic secondary battery and method of manufacturing the same
EP1246279A3 (en) * 2001-03-30 2008-12-03 SANYO ELECTRIC Co., Ltd. Nonaqueous electrolytic secondary battery and method of manufacturing the same
US7799458B2 (en) 2001-03-30 2010-09-21 Sanyo Electric Co., Ltd. Nonaqueous electrolytic secondary battery and method of manufacturing the same
JP2010277929A (en) * 2009-05-29 2010-12-09 Tdk Corp Manufacturing method of active material and electrode and active material and electrode

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