JP2002117832A - Lithium secondary battery - Google Patents
Lithium secondary batteryInfo
- Publication number
- JP2002117832A JP2002117832A JP2000307708A JP2000307708A JP2002117832A JP 2002117832 A JP2002117832 A JP 2002117832A JP 2000307708 A JP2000307708 A JP 2000307708A JP 2000307708 A JP2000307708 A JP 2000307708A JP 2002117832 A JP2002117832 A JP 2002117832A
- Authority
- JP
- Japan
- Prior art keywords
- positive electrode
- lithium secondary
- secondary battery
- electrode mixture
- lithium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、リチウムの吸蔵・
脱離現象を利用したリチウム二次電池に関し、特に、エ
ネルギー体積密度の高いリチウム二次電池に関する。TECHNICAL FIELD The present invention relates to a method for storing and storing lithium.
The present invention relates to a lithium secondary battery using a desorption phenomenon, and particularly to a lithium secondary battery having a high energy volume density.
【０００２】[0002]
【従来の技術】パソコン、ビデオカメラ、携帯電話等の
小型化に伴い、情報関連機器、通信機器の分野では、こ
れらの機器に用いる電源として、高エネルギー密度であ
るという理由から、リチウム二次電池が実用化され広く
普及するに至っている。また一方で、自動車の分野にお
いても、環境問題、資源問題から電気自動車の開発が急
がれており、この電気自動車用の電源としても、リチウ
ム二次電池が検討されている。2. Description of the Related Art With the miniaturization of personal computers, video cameras, mobile phones, and the like, in the fields of information-related equipment and communication equipment, lithium secondary batteries are used as power sources for these equipments because of their high energy density. Has been put to practical use and has spread widely. On the other hand, in the field of automobiles, the development of electric vehicles is urgent due to environmental problems and resource problems, and lithium secondary batteries are being studied as power sources for electric vehicles.
【０００３】リチウム二次電池に用いる正極は、ＬｉＣ
ｏＯ2等の粉末状のリチウム遷移金属複合酸化物を活物
質とするものが一般的である。このリチウム遷移金属複
合酸化物は電気伝導性に乏しいことから、現状、正極
は、例えばカーボンブラックのような炭素物質粉末を導
電材（導電助材）として混合し、さらにこれらの混合物
を結着するためのポリフッ化ビニリデン等の結着剤を混
合して正極合材を調製し、この正極合材を用いて形成さ
れている。The positive electrode used for a lithium secondary battery is LiC
Generally, a powdery lithium transition metal composite oxide such as oO 2 is used as an active material. Since this lithium transition metal composite oxide has poor electric conductivity, at present, the positive electrode mixes a carbon material powder such as carbon black as a conductive material (conductive auxiliary material) and further binds the mixture. A positive electrode mixture is prepared by mixing a binder such as polyvinylidene fluoride and the like, and is formed using this positive electrode mixture.
【０００４】ところが、上記導電材として混合する炭素
物質は、正極合材中に５ｗｔ％〜３０ｗｔ％程度混合さ
れており、この炭素物質は活物質と比較して密度が低く
嵩高いものであることから、正極自体の体積が大きくな
ってしまうという問題を抱えている。正極の体積が増大
すれば、電池の単位体積当たりの容量が小さくなり、つ
まり、体積エネルギー密度が低くなり、高エネルギー密
度であるというリチウム二次電池の特質が損なわれる結
果ともなっている。However, the carbon material to be mixed as the conductive material is mixed in the positive electrode mixture at about 5 wt% to 30 wt%, and this carbon material has a lower density and a higher bulk than the active material. Therefore, there is a problem that the volume of the positive electrode itself becomes large. When the volume of the positive electrode increases, the capacity per unit volume of the battery decreases, that is, the volume energy density decreases, and the characteristic of the lithium secondary battery that it has a high energy density is impaired.
【０００５】[0005]
【発明が解決しようとする課題】本発明者は、正極合材
中に導電材を含まない正極とすることで、エネルギー密
度の高いリチウム二次電池を構成できることに着目し
た。本発明は、この着想から生まれたものであり、導電
材を含まない正極合材を用いて正極を構成することによ
り、エネルギー密度の高い、特に、体積エネルギー密度
の高いリチウム二次電池を提供することを課題としてい
る。SUMMARY OF THE INVENTION The present inventor has paid attention to the fact that a lithium secondary battery having a high energy density can be formed by using a positive electrode containing no conductive material in the positive electrode mixture. The present invention is derived from this idea, and provides a lithium secondary battery having a high energy density, particularly a high volume energy density by forming a positive electrode using a positive electrode mixture containing no conductive material. That is the task.
【０００６】[0006]
【課題を解決するための手段】本発明のリチウム二次電
池は、粉末状のリチウム遷移金属複合酸化物からなる正
極活物質と、該正極活物質を結着するための結着剤とか
らなる正極合材を有する正極を含んで構成されることを
特徴とする。つまり、活物質および結着剤のみからなる
正極合材を調製し、この正極合材により正極を形成する
ものである。The lithium secondary battery of the present invention comprises a positive electrode active material comprising a powdery lithium transition metal composite oxide and a binder for binding the positive electrode active material. It is characterized by comprising a positive electrode having a positive electrode mixture. That is, a positive electrode mixture composed only of an active material and a binder is prepared, and a positive electrode is formed from this positive electrode mixture.
【０００７】従来から用いられている炭素物質の導電材
を使用していないことから、その分だけ正極合材は軽量
化し、また、正極合材の密度は高くなる。その結果、そ
の正極合材により形成された正極を有するリチウム二次
電池はエネルギー密度の高い、特に、体積エネルギー密
度の高いリチウム二次電池となる。[0007] Since a conventionally used carbon conductive material is not used, the weight of the positive electrode mixture is reduced and the density of the positive electrode mixture is increased accordingly. As a result, a lithium secondary battery having a positive electrode formed of the positive electrode mixture becomes a lithium secondary battery having a high energy density, particularly a high volume energy density.
【０００８】導電材を含まない正極合材の欠点は正極の
電気伝導性が低いことにある。したがって、リチウム電
池の内部抵抗が大きくなり、大電流での充放電では、充
分な容量が確保できないことになる。しかし、低電流の
充放電では充分に機能し、エネルギー密度の高さを充分
に活かすことができる。また、内部抵抗の増加について
は、実施の形態の項目において後述する手段を併用する
ことによって充分に抑制することができ、その点を加味
すれば、導電材を含まない正極合材を用いた正極によっ
て構成される本発明のリチウム二次電池は、実用的なリ
チウム二次電池となり得る。A disadvantage of the positive electrode mixture containing no conductive material is that the electric conductivity of the positive electrode is low. Therefore, the internal resistance of the lithium battery becomes large, and a sufficient capacity cannot be secured by charging and discharging with a large current. However, it can function satisfactorily in low-current charging and discharging, and can make full use of the high energy density. In addition, the increase in internal resistance can be sufficiently suppressed by using the means described later in the section of the embodiment, and in view of that point, the positive electrode using the positive electrode mixture containing no conductive material is used. Can be a practical lithium secondary battery.
【０００９】[0009]
【発明の実施の形態】以下に、本発明のリチウム二次電
池の実施形態について、正極の構成、リチウム二次電池
の構成の項目に分けて詳しく説明する。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a lithium secondary battery according to the present invention will be described in detail by dividing into items of a positive electrode configuration and a lithium secondary battery configuration.
【００１０】〈正極の構成〉本発明のリチウム二次電池
の正極は、粉末状のリチウム遷移金属複合酸化物からな
る正極活物質と、該正極活物質を結着するための結着剤
とからなる正極合材を有する。<Construction of Positive Electrode> The positive electrode of the lithium secondary battery of the present invention comprises a positive electrode active material comprising a powdery lithium transition metal composite oxide and a binder for binding the positive electrode active material. Having a positive electrode mixture.
【００１１】正極活物質となるリチウム遷移金属複合酸
化物は、その種類を限定するものではない。例えば、Ｌ
ｉＣｏＯ2、ＬｉＮｉＯ2、ＬｉＭｎＯ2、ＬｉＭｎ
2Ｏ4、Ｌｉ4Ｔｉ5Ｏ12、ＬｉＦｅＰＯ4等、種々の組成
で表されるものを用いることができる。なお、これら
は、単独で用いることも、２種以上のものを混合して活
物質とするものであってもよい。The type of the lithium transition metal composite oxide serving as the positive electrode active material is not limited. For example, L
iCoO 2 , LiNiO 2 , LiMnO 2 , LiMn
Those represented by various compositions such as 2 O 4 , Li 4 Ti 5 O 12 , and LiFePO 4 can be used. These may be used alone or as a mixture of two or more kinds to form an active material.
【００１２】４Ｖ級のリチウム二次電池を構成すること
ができるという点を考慮すれば、基本組成をＬｉＣｏＯ
2とする規則配列層状岩塩構造リチウムコバルト複合酸
化物、基本組成をＬｉＮｉＯ2とする規則配列層状岩塩
構造リチウムニッケル複合酸化物、基本組成をＬｉＭｎ
Ｏ2とする層状岩塩構造リチウムマンガン複合酸化物、
基本組成をＬｉＭｎ2Ｏ4とするスピネル構造リチウムマ
ンガン複合酸化物を用いることが望ましい。なお、「基
本組成」としたことは、上記それぞれの組成のものの
他、結晶構造におけるそれぞれの遷移金属サイトの一部
を基本となる遷移金属以外の遷移金属元素、Ａｌ、Ｌｉ
等から選ばれる１種以上の元素の原子で置換したもの、
リチウムサイトの一部をＫ、Ｎａ、Ｍｇ等のＬｉ以外の
アルカリ金属元素、アルカリ土類元素等から選ばれる１
種以上の元素の原子で置換したもの、遷移金属サイトお
よびリチウムサイトの両サイトを置換したもの、化学量
論組成から若干外れる組成のもの等も、本リチウム遷移
金属複合酸化物に含むことを意味するものである。Considering that a 4 V class lithium secondary battery can be constructed, the basic composition is LiCoO 2
It ordered layered rock salt structure lithium-cobalt composite oxide to 2, ordered layered rock salt structure lithium nickel composite oxide of the basic composition as LiNiO 2, a basic composition LiMn
A layered rock salt structure lithium manganese composite oxide to be O 2 ,
It is desirable to use a spinel-structured lithium manganese composite oxide having a basic composition of LiMn 2 O 4 . The term “basic composition” means that, in addition to those having the above compositions, a part of each transition metal site in the crystal structure is a transition metal element other than the basic transition metal, Al, Li
Those substituted with atoms of one or more elements selected from
Part of the lithium site is selected from alkali metal elements other than Li such as K, Na, Mg, etc., alkaline earth elements, etc.
This lithium transition metal composite oxide also includes those substituted with atoms of more than one kind of element, those substituted with both transition metal sites and lithium sites, and those slightly deviated from the stoichiometric composition. Is what you do.
【００１３】具体的に列挙した上記リチウム遷移金属複
合酸化物の中にあっては、大容量であり、比較的安価で
あり、結晶構造が比較的安定しており、バランスのとれ
たリチウム二次電池を構成することが可能であるという
点から、基本組成をＬｉＮｉＯ2とする規則配列層状岩
塩構造リチウムニッケル複合酸化物を選択することが望
ましい。Among the above-listed lithium transition metal composite oxides, large capacity, relatively inexpensive, relatively stable crystal structure, and balanced lithium secondary From the viewpoint that a battery can be configured, it is desirable to select an ordered layered rock-salt structure lithium nickel composite oxide having a basic composition of LiNiO 2 .
【００１４】正極活物質を結着する結着剤は、既に公知
の結着剤を用いることができ、その種類を特に限定する
ものではない。例えば、ポリテトラフルオロエチレン、
ポリフッ化ビニリデン、フッ素ゴム等の含フッ素樹脂、
ポリプロピレン、ポリエチレン等の熱可塑性樹脂等を用
いることができる。As the binder for binding the positive electrode active material, known binders can be used, and the type thereof is not particularly limited. For example, polytetrafluoroethylene,
Fluorinated resins such as polyvinylidene fluoride and fluoro rubber,
Thermoplastic resins such as polypropylene and polyethylene can be used.
【００１５】正極合材は、上記正極活物質に上記結着剤
を混合して行う。混合の方法についても特に限定するも
のではなく、通常の正極合材の混合方法に従えばよい。
例えば、攪拌機、混練機、ボールミル等の装置を用いて
均一になるように行えばよい。The positive electrode mixture is prepared by mixing the positive electrode active material with the binder. The method of mixing is not particularly limited, either, and may be a general mixing method of a positive electrode mixture.
For example, it may be carried out using a device such as a stirrer, a kneader, a ball mill or the like so as to be uniform.
【００１６】後に説明するように、例えば、正極合材は
集電体に塗工されて形成される。この塗工の際の作業性
の確保等を目的として、あるいは、結着剤中の活物質の
均一な分散を目的として、正極合材の調製の際、結着剤
が溶解する溶剤を添加するものであってもよい。この場
合の溶剤としては、Ｎ−メチル−２−ピロリドン等の有
機溶剤を用いることができる。ちなみに、この溶剤は、
正極合材塗布後の乾燥工程において正極より蒸散する。As will be described later, for example, the positive electrode mixture is formed by coating a current collector. For the purpose of ensuring workability at the time of coating, or for the purpose of uniformly dispersing the active material in the binder, a solvent in which the binder is dissolved is added during the preparation of the positive electrode mixture. It may be something. As a solvent in this case, an organic solvent such as N-methyl-2-pyrrolidone can be used. By the way, this solvent is
It evaporates from the positive electrode in the drying step after application of the positive electrode mixture.
【００１７】正極合材中における正極活物質と結着剤と
の配合比は、両者の合計を１００ｗｔ％とした場合に、
結着剤が２ｗｔ％〜１０ｗｔ％となるようにすることが
望ましい。結着剤の割合が多すぎる場合は、正極合材中
の活物質密度が小さくなり、リチウム二次電池のエネル
ギー密度が減少しすぎることになり、また、結着剤の割
合が小さすぎる場合は、良好な正極の作製が困難とな
る。The mixing ratio of the positive electrode active material and the binder in the positive electrode mixture is as follows when the total of both is 100 wt%.
It is desirable that the amount of the binder be 2 wt% to 10 wt%. If the proportion of the binder is too large, the active material density in the positive electrode mixture will be small, and the energy density of the lithium secondary battery will be too small, and if the proportion of the binder is too small, In addition, it is difficult to produce a good positive electrode.
【００１８】正極の作製は、リチウム二次電池の形態に
応じて行えばよい。一般的には、シート状の正極が用い
られる。シート状の正極を形成する場合、薄い集電体の
表面に、正極合材を層状に形成して行われる。この場
合、集電体としては、正極が晒される反応電位において
電気化学的に安定であることが要求され、例えば、アル
ミニウム等の箔を用いることができる。The production of the positive electrode may be performed according to the form of the lithium secondary battery. Generally, a sheet-like positive electrode is used. When a sheet-like positive electrode is formed, a positive electrode mixture is formed in a layer on the surface of a thin current collector. In this case, the current collector is required to be electrochemically stable at a reaction potential to which the positive electrode is exposed, and for example, a foil of aluminum or the like can be used.
【００１９】集電体の表面への正極合材層の形成は、溶
剤を添加したペースト状の上記正極合材を調製し、その
正極合材を塗工機（コータ）等により集電体表面に塗布
し、乾燥させて行えばよい。また、乾燥後、正極合材層
を緊密化する、正極合材密度を高める等の目的で、形成
された正極合材層をプレス等により圧縮することが望ま
しい。シート状の正極は、電池の仕様に応じた適切な大
きさに裁断等して、電池の組付けに供すればよい。The positive electrode mixture layer is formed on the surface of the current collector by preparing the above-mentioned positive electrode mixture in the form of a paste to which a solvent has been added, and applying the positive electrode mixture to the surface of the current collector using a coating machine (coater) or the like. And dried. After drying, it is desirable to compress the formed positive electrode mixture layer by pressing or the like for the purpose of, for example, making the positive electrode mixture layer denser or increasing the positive electrode mixture density. The sheet-shaped positive electrode may be cut into an appropriate size according to the specifications of the battery, and may be used for assembling the battery.
【００２０】集電体表面に正極合材が層状に形成されて
なる正極の場合、その正極合材層の層厚は、リチウム遷
移金属複合酸化物の粉末を構成する粒子の平均粒子直径
の２倍以下とすることが望ましい。つまり、リチウム遷
移金属複合酸化物の粉末を構成する粒子の平均粒子直径
をｒとし、正極合材の層厚をｄとした場合において、２
ｒ≧ｄという関係が成り立つことが望ましい。In the case of a positive electrode in which a positive electrode mixture is formed in a layer on the surface of the current collector, the layer thickness of the positive electrode mixture layer is two times the average particle diameter of the particles constituting the powder of the lithium transition metal composite oxide. It is desirable to set it to twice or less. That is, when the average particle diameter of the particles constituting the powder of the lithium transition metal composite oxide is r and the layer thickness of the positive electrode mixture is d, 2
It is desirable that the relationship r ≧ d be established.
【００２１】本発明のリチウム二次電池では、正極合材
中に導電材を含んでないことから、正極の電気伝導性は
低い。したがって、正極合材層の層厚が大きい場合は、
正極の内部抵抗が大きくなりすぎ、その内部抵抗により
充放電容量が低下してしまう。この減少は、充放電電流
が大きいほど顕著である。したがって、実用的な電池と
するためには、正極の内部抵抗をできるだけ小さなもの
とすることが望ましい。In the lithium secondary battery of the present invention, since the positive electrode mixture contains no conductive material, the electric conductivity of the positive electrode is low. Therefore, when the thickness of the positive electrode mixture layer is large,
The internal resistance of the positive electrode becomes too large, and the internal resistance lowers the charge / discharge capacity. This decrease is more remarkable as the charge / discharge current increases. Therefore, in order to obtain a practical battery, it is desirable that the internal resistance of the positive electrode be as small as possible.
【００２２】実験により実証されたことであるが、正極
合材層の厚さが活物質粒子の平均粒子直径の２倍以下と
なる上記態様の正極の場合、正極内の電気伝導性は比較
的良好に保たれ、導電材を含む正極と大差はない。した
がって、本態様のリチウム二次電池は、導電材を含む従
来のリチウム二次電池と比較しても、通常の電流値の充
放電における容量低下は少なく、また、重量パワー密度
（単位重量あたりのパワー密度）において遜色がない。
さらに、体積パワー密度（単位体積あたりのパワー密
度）に至っては、導電材を含まない分だけ正極合材層の
密度が高いことから、従来のリチウム二次電池よりも高
いものとなる。As demonstrated by experiments, in the case of the positive electrode of the above embodiment in which the thickness of the positive electrode mixture layer is twice or less the average particle diameter of the active material particles, the electric conductivity in the positive electrode is relatively low. It is kept well and is not much different from the positive electrode containing a conductive material. Therefore, the lithium secondary battery of the present embodiment has a small capacity decrease in charge and discharge at a normal current value and a weight power density (per unit weight) as compared with a conventional lithium secondary battery containing a conductive material. Power density).
Furthermore, the volume power density (power density per unit volume) is higher than that of a conventional lithium secondary battery because the density of the positive electrode mixture layer is high because the conductive material is not included.
【００２３】導電材を含むものの場合、正極合材層中の
電気伝導は、活物質粒子間に存在する導電材粒子によっ
て担保される。したがって、導電材を含まないものの場
合、活物質粒子どうしが接触する点が少ないほうが電気
伝導が良好となる。このことからすれば、同じ重量の正
極活物質を用いる場合、本発明のリチウム二次電池にお
いて、活物質粒子つまりリチウム遷移金属複合酸化物の
粉末粒子は大きいほうが好ましい。また、集電体表面に
正極合材が層状に形成されてなる上記態様の正極の場
合、あまり粒子径が小さいと正極合材層の層厚を薄くし
なければならなくなり、集電体等の蓄電に寄与しない部
分の体積を考慮すれば、却って体積エネルギー密度を減
少させてしまうことにもなり兼ねない。そこで、実用的
な範囲として、リチウム遷移金属複合酸化物の粉末を構
成する粒子の平均粒子直径は、５μｍ以上２０μｍ以下
であることが望ましい。さらに、リチウム遷移金属複合
酸化物の製造コストを考慮すれば、１５μｍ以下である
ことがより望ましく。また、よりパワー特性に優れたリ
チウム二次電池とするには、８μｍ以上であることがよ
り望ましい。In the case of a material containing a conductive material, the electric conduction in the positive electrode mixture layer is ensured by the conductive material particles existing between the active material particles. Therefore, in the case where the conductive material is not included, the smaller the number of contact points of the active material particles, the better the electric conductivity. From this fact, when the same weight of the positive electrode active material is used, in the lithium secondary battery of the present invention, it is preferable that the active material particles, that is, the powder particles of the lithium transition metal composite oxide be larger. Further, in the case of the positive electrode of the above aspect in which the positive electrode mixture is formed in a layer on the current collector surface, if the particle size is too small, the layer thickness of the positive electrode mixture layer must be reduced, and the current collector and the like Considering the volume of the portion that does not contribute to power storage, the volume energy density may be reduced instead. Therefore, as a practical range, the average particle diameter of the particles constituting the powder of the lithium transition metal composite oxide is desirably 5 μm or more and 20 μm or less. Further, in consideration of the production cost of the lithium transition metal composite oxide, the thickness is more preferably 15 μm or less. Further, in order to obtain a lithium secondary battery having more excellent power characteristics, it is more preferable that the thickness is 8 μm or more.
【００２４】〈リチウム二次電池の構成〉本発明のリチ
ウム二次電池は、上記正極を用いて構成される。その構
成は、一般のリチウム二次電池と異なるものではなく、
既に公知のリチウム二次電池の構成に従えばよい。例え
ば、上記正極とリチウムを吸蔵・脱離可能な負極と、非
水電解液と、その正極と負極とを離隔し非水電解液を保
持可能なセパレータとを備えて電池系を構成することが
できる。<Structure of Lithium Secondary Battery> The lithium secondary battery of the present invention is configured using the above-described positive electrode. Its configuration is not different from general lithium secondary batteries,
What is necessary is just to follow the structure of a well-known lithium secondary battery. For example, it is possible to configure a battery system including the positive electrode, a negative electrode capable of inserting and extracting lithium, a nonaqueous electrolyte, and a separator capable of separating the positive electrode and the negative electrode and holding a nonaqueous electrolyte. it can.
【００２５】負極は、金属リチウム、リチウム合金等を
用いることができる。また、デンドライトの析出の危険
性を回避すべく、正極同様、リチウムイオンを吸蔵・離
脱できる負極活物質に結着剤を混合し、適当な溶剤を加
えてペースト状にした負極合材を、銅等の金属箔製の集
電体の表面に塗布乾燥することで負極合材層を形成させ
て作製することが望ましい。この場合、正極同様、必要
に応じて合材密度を高めるべくその負極合材層を圧縮し
てもよい。As the negative electrode, metallic lithium, lithium alloy or the like can be used. Also, in order to avoid the danger of dendrite precipitation, similarly to the positive electrode, a negative electrode mixture prepared by mixing a binder with a negative electrode active material capable of inserting and extracting lithium ions and adding an appropriate solvent to form a paste is used as a copper. It is preferable to form the negative electrode mixture layer by applying and drying the surface of a current collector made of a metal foil such as the above. In this case, similarly to the positive electrode, the negative electrode mixture layer may be compressed as necessary to increase the mixture density.
【００２６】その場合の負極活物質には、例えば、天然
黒鉛、人造黒鉛、フェノール樹脂等の有機化合物焼成
体、コークス等の炭素物質の粉状体を用いることができ
る。負極結着剤としては、正極同様、ポリフッ化ビニリ
デン等の含フッ素樹脂等を、これら活物質および結着剤
を分散させる溶剤としてはＮ−メチル−２−ピロリドン
等の有機溶剤を用いることができる。In this case, as the negative electrode active material, for example, natural graphite, artificial graphite, an organic compound fired body such as a phenol resin, or a powdered carbon material such as coke can be used. As the negative electrode binder, like the positive electrode, a fluorine-containing resin such as polyvinylidene fluoride or the like can be used, and as a solvent for dispersing these active materials and the binder, an organic solvent such as N-methyl-2-pyrrolidone can be used. .
【００２７】上記正極と負極とを積層して電極体を形成
させるが、正極と負極との間には、正極と負極とを分離
し電解液を保持する機能を果たすセパレータを挟装す
る。セパレータには、ポリエチレン、ポリプロピレン等
の薄い微多孔膜を用いることができる。The above-mentioned positive electrode and negative electrode are laminated to form an electrode body. A separator is interposed between the positive electrode and the negative electrode to separate the positive electrode and the negative electrode and hold the electrolyte. As the separator, a thin microporous film such as polyethylene or polypropylene can be used.
【００２８】非水電解液は、有機溶媒に電解質であるリ
チウム塩を溶解させたもので、有機溶媒としては、非プ
ロトン性有機溶媒、例えばエチレンカーボネート、プロ
ピレンカーボネート、ジメチルカーボネート、ジエチル
カーボネート、エチルメチルカーボネート、γ−ブチロ
ラクトン、アセトニトリル、１，２−ジメトキシエタ
ン、テトラヒドロフラン、ジオキソラン、塩化メチレン
等の１種またはこれらの２種以上の混合溶媒を用いるこ
とができる。また、溶解させる電解質としては、Ｌｉ
Ｉ、ＬｉＣｌＯ4、ＬｉＡｓＦ6、ＬｉＢＦ4、ＬｉＰ
Ｆ6、ＬｉＮ（ＣＦ3ＳＯ2）2等のリチウム塩を用いるこ
とができる。The non-aqueous electrolyte is obtained by dissolving a lithium salt as an electrolyte in an organic solvent. Examples of the organic solvent include aprotic organic solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl. One type of carbonate, γ-butyrolactone, acetonitrile, 1,2-dimethoxyethane, tetrahydrofuran, dioxolan, methylene chloride and the like, or a mixed solvent of two or more types thereof can be used. The electrolyte to be dissolved is Li
I, LiClO 4 , LiAsF 6 , LiBF 4 , LiP
Lithium salts such as F 6 and LiN (CF 3 SO 2 ) 2 can be used.
【００２９】なお、上記セパレータおよび非水電解液と
いう構成に代えて、ポリエチレンオキシド等の高分子量
ポリマーとＬｉＣｌＯ4やＬｉＮ（ＣＦ3ＳＯ2）2等のリ
チウム塩を使用した高分子固体電解質を用いることもで
き、また、上記非水電解液をポリアクリロニトリル等の
固体高分子マトリクスにトラップさせたゲル電解質を用
いることもできる。Instead of using the separator and the non-aqueous electrolyte, a solid polymer electrolyte using a high molecular weight polymer such as polyethylene oxide and a lithium salt such as LiClO 4 or LiN (CF 3 SO 2 ) 2 is used. It is also possible to use a gel electrolyte in which the above non-aqueous electrolyte is trapped in a solid polymer matrix such as polyacrylonitrile.
【００３０】以上の構成要素によって電池系が構成され
る本発明のリチウム二次電池であるが、その形状は円筒
型、積層型、コイン型等、種々のものとすることができ
る。いずれの形状を採る場合であっても、上記構成要素
を電池ケースに収納し、正極集電体および負極集電体か
ら外部に通ずる正極端子および負極端子までの間を集電
用リード等を用いて接続し、電池ケースを密閉して電池
系を外部と離隔し、リチウム二次電池が完成される。The lithium secondary battery of the present invention, in which a battery system is constituted by the above-described components, can have various shapes such as a cylindrical type, a stacked type, a coin type and the like. In any case, the above components are housed in a battery case, and a current collecting lead or the like is used between the positive electrode current collector and the negative electrode current collector to the positive electrode terminal and the negative electrode terminal communicating to the outside. The battery case is sealed, the battery system is separated from the outside, and the lithium secondary battery is completed.
【００３１】〈他の実施形態の許容〉以上、本発明の上
記本発明のリチウム二次電池の実施形態について説明し
たが、上述した実施形態は一実施形態にすぎず、本発明
のリチウム二次電池は、上記実施形態を始めとして、当
業者の知識に基づいて種々の変更、改良を施した種々の
形態で実施することができる。<Allowance of Other Embodiments> The embodiment of the lithium secondary battery of the present invention has been described above. However, the above-described embodiment is merely an embodiment, and the lithium secondary battery of the present invention is not limited to the embodiment. The battery can be implemented in various forms including various modifications and improvements based on the knowledge of those skilled in the art, including the above embodiment.
【００３２】[0032]
【実施例】上記実施形態に基づき、導電材を含まない正
極を用いた本発明のリチウム二次電池を作製し、導電材
を含む正極を用いた従来のリチウム二次電池との間で、
エネルギー密度、パワー密度を比較した。また、正極合
材の層厚の異なる種々の正極を用いたリチウム二次電池
をも作製し、正極合材層の層厚と放電容量との関係をも
調査した。以下に、これらについて記載する。EXAMPLES Based on the above embodiment, a lithium secondary battery of the present invention using a positive electrode containing no conductive material was manufactured, and a lithium secondary battery using a positive electrode containing a conductive material was produced.
The energy density and the power density were compared. In addition, lithium secondary batteries using various positive electrodes having different layer thicknesses of the positive electrode mixture were also manufactured, and the relationship between the layer thickness of the positive electrode mixture layer and the discharge capacity was also investigated. These are described below.
【００３３】（１）エネルギー密度、パワー密度の比較 〈実施例１のリチウム二次電池〉本発明のリチウム二次
電池の実施例として、以下の構成のリチウム二次電池を
作製した。正極活物質には、組成式ＬｉＮｉ0.8Ｃｏ
0.15Ａｌ0.05Ｏ2で表される規則配列層状岩塩構造リチ
ウムニッケル複合酸化物を用いた。ちなみに、このリチ
ウムニッケル複合酸化物は、その粒子の平均粒子直径が
１０μｍのものとした。結着剤には、ポリフッ化ビニリ
デン（ＰＶｄＦ）を用いた。さらに、これらを分散、溶
解する溶剤としてＮ−メチル−２−ピロリドン（ＮＭ
Ｐ）を用いた。(1) Comparison of energy density and power density <Lithium secondary battery of Example 1> As an example of the lithium secondary battery of the present invention, a lithium secondary battery having the following configuration was manufactured. The positive electrode active material has a composition formula of LiNi 0.8 Co
A lithium nickel composite oxide having an ordered layered rock salt structure represented by 0.15 Al 0.05 O 2 was used. The lithium nickel composite oxide had an average particle diameter of 10 μm. Polyvinylidene fluoride (PVdF) was used as the binder. Further, N-methyl-2-pyrrolidone (NM) is used as a solvent for dispersing and dissolving them.
P) was used.
【００３４】まず、上記リチウムニッケル複合酸化物の
９７重量部に対して、ＰＶｄＦを３重量部混合し、さら
に適量のＮＭＰを添加し、これを充分に混練して、ペー
スト状の正極合材を調製した。この正極合材ペースト
を、塗工機を用いて、厚さ２０μｍのアルミニウム箔集
電体の両面に塗布し、乾燥させて、シート状の正極を得
た。さらにこの正極を、ロールプレスにて圧縮し、シー
ト状の正極を完成させた。この完成した正極は、正極合
材層の片面あたり厚さを２０μｍ（活物質粒子の平均粒
子直径の２倍）とするものであり、その大きさを５４ｍ
ｍ×４５０ｍｍとするものである。First, 3 parts by weight of PVdF was mixed with 97 parts by weight of the above lithium nickel composite oxide, an appropriate amount of NMP was added, and this was sufficiently kneaded to obtain a paste-like positive electrode mixture. Prepared. This positive electrode mixture paste was applied to both surfaces of a 20 μm-thick aluminum foil current collector using a coating machine, and dried to obtain a sheet-shaped positive electrode. Further, this positive electrode was compressed by a roll press to complete a sheet-shaped positive electrode. The finished positive electrode had a thickness per side of the positive electrode mixture layer of 20 μm (twice the average particle diameter of the active material particles), and the size was 54 m.
m × 450 mm.
【００３５】対向する負極は、負極活物質として人造黒
鉛である黒鉛化メソフェーズ小球体（ＭＣＭＢ）を用い
た。まず、このＭＣＭＢの９０重量部に対して、ＰＶｄ
Ｆを１０重量部混合し、さらに適量のＮＭＰを添加し、
これを充分に混練して、ペースト状の負極合材を調製し
た。この負極合材ペーストを、塗工機を用いて、厚さ１
０μｍの銅箔集電体の両面に塗布し、乾燥させて、シー
ト状の負極を得た。さらに、この負極を、ロールプレス
にて圧縮し、シート状の負極を完成させた。この完成し
た負極は、負極合材層の片面あたり厚さを５０μｍとす
るものであり、その大きさを５６ｍｍ×５００ｍｍとす
るものである。The opposite negative electrode used was graphitized mesophase microspheres (MCMB), which was artificial graphite, as the negative electrode active material. First, PVd was added to 90 parts by weight of this MCMB.
F by mixing 10 parts by weight, further adding an appropriate amount of NMP,
This was sufficiently kneaded to prepare a paste-like negative electrode mixture. This negative electrode mixture paste was applied to a thickness of 1 using a coating machine.
It was applied to both sides of a 0 μm copper foil current collector and dried to obtain a sheet-shaped negative electrode. Further, this negative electrode was compressed by a roll press to complete a sheet-shaped negative electrode. In the completed negative electrode, the thickness per one side of the negative electrode mixture layer is 50 μm, and the size is 56 mm × 500 mm.
【００３６】上記正極および負極を、その間に厚さ２５
μｍ、幅５８ｍｍのポリエチレンセパレータを挟装し、
外径３．５ｍｍφの捲回芯を中心に捲回してロール状の
電極体を形成し、次いで、この電極体を、非水電解液と
ともに１８６５０型電池ケースに挿設し、リチウム二次
電池を完成させるものとした。用いた非水電解液は、エ
チレンカーボネートとジエチルカーボネートとを体積比
１：１で混合した混合溶媒に、ＬｉＰＦ6を１Ｍの濃度
で溶解させたものを使用した。ちなみに、電極体の体積
は、５．１５ｃｍ3であった。The positive electrode and the negative electrode are placed between them with a thickness of 25
μm, sandwiching a polyethylene separator with a width of 58 mm,
A roll-shaped electrode body is formed by winding around a wound core having an outer diameter of 3.5 mmφ, and then this electrode body is inserted into a 18650 type battery case together with a non-aqueous electrolyte to form a lithium secondary battery. It was to be completed. The non-aqueous electrolyte used was one in which LiPF 6 was dissolved at a concentration of 1 M in a mixed solvent obtained by mixing ethylene carbonate and diethyl carbonate at a volume ratio of 1: 1. Incidentally, the volume of the electrode body was 5.15 cm 3 .
【００３７】〈比較例１のリチウム二次電池〉上記実施
例１のリチウム二次電池と正極の異なるリチウム二次電
池を作製した。正極活物質には、実施例１のリチウム二
次電池と同じ組成式ＬｉＮｉ0.8Ｃｏ0 .15Ａｌ0.05Ｏ2で
表される規則配列層状岩塩構造リチウムニッケル複合酸
化物を用いた。同様に、結着剤には、ポリフッ化ビニリ
デン（ＰＶｄＦ）を用いた。さらに、これらを分散、溶
解する溶剤としてＮ−メチル−２−ピロリドン（ＮＭ
Ｐ）を用いた。さらに、本リチウム二次電池の正極で
は、導電材として、カーボンブラックを用いた。<Lithium Secondary Battery of Comparative Example 1>
A lithium secondary battery having a positive electrode different from that of the lithium secondary battery of Example 1
A pond was made. As the positive electrode active material, the lithium secondary battery of Example 1 was used.
LiNi same composition formula as secondary battery0.8Co0 .15Al0.05OTwoso
Represented ordered layered rock salt structure lithium nickel composite acid
Was used. Similarly, polyvinylidene fluoride is used as the binder.
Den (PVdF) was used. Furthermore, these are dispersed and dissolved.
N-methyl-2-pyrrolidone (NM
P) was used. Furthermore, with the positive electrode of this lithium secondary battery,
Used carbon black as a conductive material.
【００３８】まず、上記リチウムニッケル複合酸化物の
８５重量部に対して、カーボンブラックを１０重量部、
ＰＶｄＦを５重量部混合し、さらに適量のＮＭＰを添加
し、これを充分に混練して、ペースト状の正極合材を調
製した。この正極合材ペーストを、塗工機を用いて、厚
さ２０μｍのアルミニウム箔集電体の両面に塗布し、乾
燥させて、シート状の正極を得た。さらにこの正極を、
ロールプレスにて圧縮し、シート状の正極を完成させ
た。正極１つあたりに使用される正極活物質の量は、実
施例１のリチウム二次電池の場合と同じ量とし、正極の
大きさも、実施例１のリチウム二次電池の場合と同じ５
４ｍｍ×４５０ｍｍとした。その結果、この完成した正
極は、正極合材層の片面あたり厚さを３５μｍとするも
のとなっている。First, 10 parts by weight of carbon black was added to 85 parts by weight of the lithium nickel composite oxide.
5 parts by weight of PVdF was mixed, an appropriate amount of NMP was further added, and the mixture was sufficiently kneaded to prepare a paste-like positive electrode mixture. This positive electrode mixture paste was applied to both surfaces of a 20 μm-thick aluminum foil current collector using a coating machine, and dried to obtain a sheet-shaped positive electrode. In addition, this positive electrode
It was compressed by a roll press to complete a sheet-shaped positive electrode. The amount of the positive electrode active material used for one positive electrode was the same as that of the lithium secondary battery of Example 1, and the size of the positive electrode was the same as that of the lithium secondary battery of Example 1.
4 mm x 450 mm. As a result, this completed positive electrode has a thickness per one side of the positive electrode mixture layer of 35 μm.
【００３９】上記実施例１のリチウム二次電池の場合
と、他の構成を同じくし、同様のプロセスでリチウム二
次電池を完成させた。正極の厚さが厚くなっている分だ
け、電極体の捲回径が大きくなったため、このリチウム
二次電池の電極体の体積は、実施例１のリチウム二次電
池と比較して大きく、７．０８ｃｍ3となった。A lithium secondary battery was completed by the same process as that of the lithium secondary battery of Example 1 except for the other components. Since the wound diameter of the electrode body was increased by the thickness of the positive electrode, the volume of the electrode body of this lithium secondary battery was larger than that of the lithium secondary battery of Example 1, 0.08 cm 3 .
【００４０】〈エネルギー密度の評価〉上記実施例１お
よび比較例１のリチウム二次電池の放電容量の測定を行
い、両者のエネルギー密度を比較した。<Evaluation of Energy Density> The discharge capacities of the lithium secondary batteries of Example 1 and Comparative Example 1 were measured, and the energy densities of the two were compared.
【００４１】放電容量の測定の条件は、２０℃の環境温
度下、充電終止電圧４．１Ｖまで電流密度０．２ｍＡ／
ｃｍ2の定電流で充電した後、放電終止電圧３．０Ｖま
で電流密度０．２ｍＡ／ｃｍ2の定電流で放電させ、こ
のときの放電容量を測定するものとした。そして、それ
ぞれの放電容量をそれぞれの電極体の体積で除して、そ
れぞれの体積エネルギー密度を求めた。この結果とし
て、それぞれのリチウム二次電池の放電容量、電極体体
積、体積エネルギー密度を、下記表１に示す。The conditions for measuring the discharge capacity were as follows: an environment temperature of 20 ° C., a current density of 0.2 mA /
After charging at a constant current of 2 cm 2 , the battery was discharged at a constant current of 0.2 mA / cm 2 to a discharge end voltage of 3.0 V, and the discharge capacity at this time was measured. Then, each of the discharge capacities was divided by the volume of each of the electrode bodies to obtain each of the volume energy densities. As a result, the discharge capacity, the electrode body volume, and the volume energy density of each lithium secondary battery are shown in Table 1 below.
【００４２】[0042]
【表１】 [Table 1]
【００４３】上記表１から明らかなように、実施例１の
リチウム二次電池は、比較例１のリチウム二次電池に比
べ、体積エネルギー密度が約２０％も大きくなっている
ことが判る。この結果から、導電材を含まない正極を用
いた本発明のリチウム二次電池は、エネルギー密度、特
に体積エネルギー密度の高いリチウム二次電池であるこ
とが確認できる。As is clear from Table 1, the lithium secondary battery of Example 1 has a volume energy density about 20% larger than that of the lithium secondary battery of Comparative Example 1. From this result, it can be confirmed that the lithium secondary battery of the present invention using the positive electrode containing no conductive material is a lithium secondary battery having a high energy density, particularly a high volume energy density.
【００４４】〈パワー密度の評価〉上記実施例１および
比較例１のリチウム二次電池に対して、パワー密度の測
定を行った。測定の要領は、２０℃の環境温度下、それ
ぞれのリチウム二次電池を、ＳＯＣ２０％、５０％、８
０％の３つの充電状態において、０．２〜１０ｍＡ／ｃ
ｍ2の異なる電流密度の種々の定電流で１０秒間充電お
よび放電させ、それらの場合の電池電圧の変化を測定す
るものである。異なる電流における電池電圧の変化値を
外挿し、充電であれば１０秒間で充電終止電圧４．１Ｖ
に達すると仮定した場合の最大電流値を求め、また、放
電であれば１０秒間で放電終止電圧３．０Ｖに達すると
仮定した場合の最大電流値を求め、それぞれの最大電流
値に充電終止電圧または放電終止電圧を乗じた値をその
リチウム二次電池のその充電状態または放電状態におけ
るパワーとした。<Evaluation of Power Density> The lithium secondary batteries of Example 1 and Comparative Example 1 were measured for power density. The procedure of the measurement is as follows. At an environmental temperature of 20 ° C., each of the lithium secondary batteries is subjected to SOC 20%, 50%, and 8%.
0.2 to 10 mA / c in three charged states of 0%
The battery was charged and discharged at various constant currents having different current densities of m 2 for 10 seconds, and the change in battery voltage was measured in those cases. Extrapolate the change value of the battery voltage at different currents and charge end voltage 4.1V in 10 seconds for charging
The maximum current value when it is assumed that the discharge end voltage is reached is obtained, and the maximum current value when it is assumed that the discharge end voltage reaches 3.0 V in 10 seconds in the case of discharge is obtained. Alternatively, the value obtained by multiplying the discharge end voltage was defined as the power in the charged state or the discharged state of the lithium secondary battery.
【００４５】パワー密度は、そのパワーの値をそれぞれ
のリチウム二次電池の電極体の体積で除し、体積パワー
密度を求めた。充電時における体積パワー密度を充電体
積パワー密度、放電時における体積パワー密度を放電体
積パワー密度と称することとした。この結果として、図
１に、実施例１および比較例１のリチウム二次電池の充
電体積パワー密度および放電体積パワー密度を示す。The power density was obtained by dividing the value of the power by the volume of the electrode body of each lithium secondary battery to obtain a volume power density. The volume power density during charging is referred to as charging volume power density, and the volume power density during discharging is referred to as discharging volume power density. As a result, FIG. 1 shows the charge volume power density and the discharge volume power density of the lithium secondary batteries of Example 1 and Comparative Example 1.
【００４６】図１から明らかなように、比較例１のリチ
ウム二次電池と比べて、充電体積パワー密度および放電
体積パワー密度とも、実施例１のリチウム二次電池が優
っている。この結果から、導電材を含まない正極を用い
た本発明のリチウム二次電池は、パワー密度、特に体積
パワー密度の高いリチウム二次電池であることが確認で
きる。As is apparent from FIG. 1, the lithium secondary battery of Example 1 is superior to the lithium secondary battery of Comparative Example 1 in both the charge volume power density and the discharge volume power density. From these results, it can be confirmed that the lithium secondary battery of the present invention using the positive electrode containing no conductive material is a lithium secondary battery having high power density, particularly high volume power density.
【００４７】（２）正極合材層の層厚と放電容量との関
係 〈実施例２のリチウム二次電池〉導電材を含まない正極
を用いた本発明の実施例となるリチウム二次電池であっ
て、正極合材層の層厚の種々異なるリチウム二次電池を
作製した。正極合材層の層厚を除き、他の構成は、上記
実施例１のリチウム二次電池と同様である。正極合材層
の層厚がそれぞれ１０μｍ、１５μｍ、２０μｍ、２５
μｍ、３０μｍとなる５種のものを作製した。正極活物
質となるリチウムニッケル複合酸化物粒子の平均粒子直
径が１０μｍであることから、正極合材層の層厚（ｄ）
のリチウムニッケル複合酸化物粒子の平均粒子直径
（ｒ）に対する比（ｄ／ｒ：「正極合材層厚比」と呼
ぶ）は、それぞれ１、１．５、２、２．５、３となる。
ちなみに、正極合材層厚比が２のものは、上記実施例１
と同じ構成となる。(2) Relationship between Layer Thickness of Positive Electrode Mixture Layer and Discharge Capacity <Lithium Secondary Battery of Example 2> In the lithium secondary battery of the present invention using a positive electrode containing no conductive material. Then, lithium secondary batteries having different thicknesses of the positive electrode mixture layer were manufactured. Except for the thickness of the positive electrode mixture layer, other configurations are the same as those of the lithium secondary battery of Example 1 described above. The thickness of the positive electrode mixture layer is 10 μm, 15 μm, 20 μm, and 25 μm, respectively.
Five types having a thickness of 30 μm were prepared. Since the average particle diameter of the lithium nickel composite oxide particles serving as the positive electrode active material is 10 μm, the thickness of the positive electrode mixture layer (d)
Of the lithium nickel composite oxide particles to the average particle diameter (r) (d / r: referred to as “positive electrode mixture layer thickness ratio”) are 1, 1.5, 2, 2.5, and 3, respectively. .
Incidentally, when the positive electrode mixture layer thickness ratio was 2,
Has the same configuration as
【００４８】〈比較例２のリチウム二次電池〉導電材を
含む正極を用いたリチウム二次電池であって、正極合材
層の層厚の種々異なるリチウム二次電池を作製した。正
極合材層の層厚を除き、他の構成は、上記比較例１のリ
チウム二次電池と同様である。上記実施例２のリチウム
二次電池の場合と同様、正極合材層の層厚がそれぞれ１
０μｍ、１５μｍ、２０μｍ、２５μｍ、３０μｍとな
る５種のものを作製した。それぞれの正極合材層厚比に
ついても、上記実施例２のリチウム二次電池の場合と同
様となる。<Lithium Secondary Battery of Comparative Example 2> A lithium secondary battery using a positive electrode containing a conductive material, and having different thicknesses of the positive electrode mixture layer, was manufactured. Except for the thickness of the positive electrode mixture layer, other configurations are the same as those of the lithium secondary battery of Comparative Example 1 described above. As in the case of the lithium secondary battery of Example 2, the thickness of the positive electrode mixture layer was 1
Five types of 0 μm, 15 μm, 20 μm, 25 μm, and 30 μm were produced. The respective positive electrode mixture layer thickness ratios are the same as in the case of the lithium secondary battery of Example 2 described above.
【００４９】〈放電容量の評価〉上記実施例２および比
較例２のそれぞれのリチウム二次電池の放電容量の測定
を行った。放電容量の測定の条件は、２０℃の環境温度
下、充電終止電圧４．１Ｖまで電流密度０．２ｍＡ／ｃ
ｍ2の定電流で充電した後、放電終止電圧３．０Ｖまで
電流密度０．２ｍＡ／ｃｍ2の定電流で放電させ、この
ときの放電容量を測定するものとした。そして、それぞ
れの放電容量をそれぞれのリチウム二次電池おいて使用
されている正極活物質の重量で除して、それぞれの正極
活物質単位重量あたりの放電容量（以下、「活物質放電
容量」と略す）を求めた。この結果として、実施例２お
よび比較例２のそれぞれのリチウム二次電池における正
極合材層の層厚と活物質放電容量との関係を図２に示
す。<Evaluation of Discharge Capacity> The discharge capacity of each of the lithium secondary batteries of Example 2 and Comparative Example 2 was measured. The conditions for measuring the discharge capacity were as follows: an environment temperature of 20 ° C., a current density of 0.2 mA / c up to a charge termination voltage of 4.1 V.
After charging at a constant current of m 2 , the battery was discharged at a constant current of 0.2 mA / cm 2 to a discharge end voltage of 3.0 V, and the discharge capacity at this time was measured. Then, each discharge capacity is divided by the weight of the positive electrode active material used in each lithium secondary battery, and the discharge capacity per unit weight of each positive electrode active material (hereinafter referred to as “active material discharge capacity”) (Abbreviated). As a result, FIG. 2 shows the relationship between the thickness of the positive electrode mixture layer and the active material discharge capacity in each of the lithium secondary batteries of Example 2 and Comparative Example 2.
【００５０】図２から明らかなように、導電材を含む正
極を用いた比較例２のリチウム二次電池では、正極合材
層の層厚が厚くなっても、殆ど活物質放電容量が減少し
ていない。これは、導電材が正極合材層の良好な電気伝
導性を担保していることを表している。これに対し、導
電材を含まない正極を用いた実施例２のリチウム二次電
池では、正極合材層の層厚が厚くなるにつれて、活物質
放電容量が減少していることがわかる。導電材を含まな
いことで、正極合材中の電気伝導が減少し、電池の内部
抵抗が上昇することが伺える。As is clear from FIG. 2, in the lithium secondary battery of Comparative Example 2 using the positive electrode containing the conductive material, even when the thickness of the positive electrode mixture layer was increased, the discharge capacity of the active material almost decreased. Not. This indicates that the conductive material ensures good electrical conductivity of the positive electrode mixture layer. On the other hand, in the lithium secondary battery of Example 2 using the positive electrode containing no conductive material, it can be seen that the active material discharge capacity decreases as the thickness of the positive electrode mixture layer increases. By not including the conductive material, it can be seen that the electric conductivity in the positive electrode mixture decreases and the internal resistance of the battery increases.
【００５１】しかし、正極合材層厚比が２以下となる場
合においては、比較例２のリチウム二次電池の９０％以
上の活物質放電容量が確保されており、実用的には問題
のない放電容量の減少に留まっている。したがって、正
極合材層の層厚を正極活物質の粒子の平均粒子直径の２
倍以下とすることにより、放電容量の減少を少なくで
き、かつ、上述した、エネルギー密度およびパワー密度
の高さを享受できることで、本発明のリチウム二次電池
は、実用的なリチウム二次電池となることが確認でき
る。However, when the thickness ratio of the positive electrode mixture layer is 2 or less, the active material discharge capacity of 90% or more of the lithium secondary battery of Comparative Example 2 is secured, and there is no practical problem. Only the discharge capacity decreases. Therefore, the thickness of the positive electrode mixture layer is set to 2 times the average particle diameter of the particles of the positive electrode active material.
By not more than twice, the reduction in discharge capacity can be reduced, and, as described above, the high energy density and high power density can be enjoyed, so that the lithium secondary battery of the present invention is a practical lithium secondary battery. Can be confirmed.
【００５２】[0052]
【発明の効果】本発明は、リチウム二次電池において従
来用いられてきた導電材を排除し、活物質とそれを結着
する結着剤のみで正極合材を構成し、その正極合材によ
って形成されるされる正極を含むようにリチウム二次電
池を構成するものである。このような構成とすること
で、本発明のリチウム二次電池は、エネルギー密度、特
に体積エネルギー密度の高いリチウム二次電池となる。According to the present invention, a positive electrode mixture is constituted only by an active material and a binder for binding the same, excluding a conductive material conventionally used in a lithium secondary battery. The lithium secondary battery is configured to include the formed positive electrode. With such a configuration, the lithium secondary battery of the present invention is a lithium secondary battery having high energy density, particularly high volume energy density.
【図１】 導電材を含まない正極を用いた実施例１およ
び導電材を含む正極を用いた比較例１のそれぞれのリチ
ウム二次電池の充電体積パワー密度および放電体積パワ
ー密度を示す。FIG. 1 shows a charge volume power density and a discharge volume power density of a lithium secondary battery of Example 1 using a positive electrode containing no conductive material and Comparative Example 1 using a positive electrode containing a conductive material.
【図２】 導電材を含まない正極を用いた実施例２およ
び導電材を含む正極を用いた比較例２のそれぞれのリチ
ウム二次電池における正極合材層の層厚と活物質放電容
量との関係を示す。FIG. 2 shows the relationship between the thickness of the positive electrode mixture layer and the active material discharge capacity in each of the lithium secondary batteries of Example 2 using a positive electrode containing no conductive material and Comparative Example 2 using a positive electrode containing a conductive material. Show the relationship.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 右京 良雄 愛知県愛知郡長久手町大字長湫字横道41番 地の１ 株式会社豊田中央研究所内 Ｆターム(参考） 5H029 AJ03 AK03 AL07 AL08 AL12 DJ08 DJ16 HJ04 HJ05 5H050 AA08 BA16 BA17 CA07 CA08 CB08 CB09 CB12 DA02 DA11 FA17 HA04 HA05 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshio Ukyo 41-cho, Yojimichi, Nagakute-cho, Aichi-gun, Aichi F-1 term in Toyota Central R & D Laboratories Co., Ltd. 5H029 AJ03 AK03 AL07 AL08 AL12 DJ08 DJ16 HJ04 HJ05 5H050 AA08 BA16 BA17 CA07 CA08 CB08 CB09 CB12 DA02 DA11 FA17 HA04 HA05
Claims (4)
らなる正極活物質と、 該正極活物質を結着するための結着剤と、 からなる正極合材を有する正極を含んで構成されるリチ
ウム二次電池。1. A positive electrode comprising a positive electrode active material comprising a powdery lithium transition metal composite oxide, a binder for binding the positive electrode active material, and a positive electrode mixture comprising: Lithium secondary battery.
が層状に形成されてなり、 前記リチウム遷移金属複合酸化物の粉末を構成する粒子
の平均粒子直径をｒと、前記正極合材の層厚をｄとした
場合において、次式が成立する請求項１に記載のリチウ
ム二次電池。 ２ｒ≧ｄ2. The positive electrode according to claim 1, wherein the positive electrode mixture is formed in a layer on the surface of a current collector, and the average particle diameter of particles constituting the powder of the lithium transition metal composite oxide is r; 2. The lithium secondary battery according to claim 1, wherein the following equation is satisfied when the thickness of the material is d. 2r ≧ d
を構成する粒子の平均粒子直径は、５μｍ以上２０μｍ
以下である請求項１または請求項２に記載のリチウム二
次電池。3. An average particle diameter of particles constituting the powder of the lithium transition metal composite oxide is 5 μm or more and 20 μm or more.
The lithium secondary battery according to claim 1, wherein the lithium secondary battery is:
本組成をＬｉＮｉＯ2とする規則配列層状岩塩構造リチ
ウムニッケル複合酸化物である請求項１ないし請求項３
のいずれかに記載のリチウム二次電池。4. The lithium transition metal composite oxide according to claim 1, wherein the lithium transition metal composite oxide is an ordered layered rock salt structure lithium nickel composite oxide having a basic composition of LiNiO 2.
The lithium secondary battery according to any one of the above.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000307708A JP4780361B2 (en) | 2000-10-06 | 2000-10-06 | Lithium secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000307708A JP4780361B2 (en) | 2000-10-06 | 2000-10-06 | Lithium secondary battery |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2002117832A true JP2002117832A (en) | 2002-04-19 |
| JP4780361B2 JP4780361B2 (en) | 2011-09-28 |
Family
ID=18788174
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2000307708A Expired - Fee Related JP4780361B2 (en) | 2000-10-06 | 2000-10-06 | Lithium secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4780361B2 (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006278076A (en) * | 2005-03-29 | 2006-10-12 | Sanyo Electric Co Ltd | Nonaqueous electrolyte secondary battery |
| US7368497B2 (en) | 2001-08-31 | 2008-05-06 | Sumitomo Bakelite Company, Ltd. | Resin composition, prepreg, laminate, and semiconductor package |
| JP2009224119A (en) * | 2008-03-14 | 2009-10-01 | Toyota Central R&D Labs Inc | Preliminary charge and discharge method of lithium-ion secondary battery, and lithium-ion secondary battery |
| WO2010137582A1 (en) * | 2009-05-26 | 2010-12-02 | 石原産業株式会社 | Lithium titanate, process for production of same, and electrode active material and electricity storage device each comprising same |
| JP2011257790A (en) * | 2010-06-04 | 2011-12-22 | Nippon Telegr & Teleph Corp <Ntt> | Relevant information extraction device, method thereof, and program |
| JP2013518376A (en) * | 2010-01-28 | 2013-05-20 | ジュート−ヘミー イーペー ゲーエムベーハー ウント コー カーゲー | Electrode for lithium ion secondary battery without added conductive agent |
| JP2013518377A (en) * | 2010-01-28 | 2013-05-20 | ジュート−ヘミー イーペー ゲーエムベーハー ウント コー カーゲー | Electrode for lithium ion secondary battery |
| US20200185714A1 (en) * | 2018-12-10 | 2020-06-11 | Lg Chem, Ltd. | Positive Electrode Material, Producing Method Thereof, Positive Electrode and Lithium Secondary Battery Comprising the Same |
| CN114843457A (en) * | 2021-02-01 | 2022-08-02 | 三星Sdi株式会社 | Positive electrode, lithium battery including the same, and method of manufacturing the same |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04269465A (en) * | 1991-02-25 | 1992-09-25 | Matsushita Electric Ind Co Ltd | Nonaqueous electrolyte secondary battery |
| JP2000173598A (en) * | 1998-12-07 | 2000-06-23 | Japan Storage Battery Co Ltd | Manufacture of electrode and battery |
-
2000
- 2000-10-06 JP JP2000307708A patent/JP4780361B2/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04269465A (en) * | 1991-02-25 | 1992-09-25 | Matsushita Electric Ind Co Ltd | Nonaqueous electrolyte secondary battery |
| JP2000173598A (en) * | 1998-12-07 | 2000-06-23 | Japan Storage Battery Co Ltd | Manufacture of electrode and battery |
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7368497B2 (en) | 2001-08-31 | 2008-05-06 | Sumitomo Bakelite Company, Ltd. | Resin composition, prepreg, laminate, and semiconductor package |
| JP2006278076A (en) * | 2005-03-29 | 2006-10-12 | Sanyo Electric Co Ltd | Nonaqueous electrolyte secondary battery |
| JP2009224119A (en) * | 2008-03-14 | 2009-10-01 | Toyota Central R&D Labs Inc | Preliminary charge and discharge method of lithium-ion secondary battery, and lithium-ion secondary battery |
| KR101829177B1 (en) * | 2009-05-26 | 2018-02-13 | 이시하라 산교 가부시끼가이샤 | Lithium titanate, process for production of same, and electrode active material and electricity storage device each comprising same |
| US9452940B2 (en) | 2009-05-26 | 2016-09-27 | Ishihara Sangyo Kaisha, Ltd. | Lithium titanate, electrode active material and electricity storage device each comprising the same |
| CN102428031A (en) * | 2009-05-26 | 2012-04-25 | 石原产业株式会社 | Lithium titanate, process for production of same, and electrode active material and electricity storage device each comprising same |
| WO2010137582A1 (en) * | 2009-05-26 | 2010-12-02 | 石原産業株式会社 | Lithium titanate, process for production of same, and electrode active material and electricity storage device each comprising same |
| KR101761428B1 (en) * | 2009-05-26 | 2017-07-25 | 이시하라 산교 가부시끼가이샤 | Lithium titanate, process for production of same, and electrode active material and electricity storage device each comprising same |
| JP5726074B2 (en) * | 2009-05-26 | 2015-05-27 | 石原産業株式会社 | Lithium titanate, method for producing the same, electrode active material using the same, and electricity storage device |
| US9126847B2 (en) | 2009-05-26 | 2015-09-08 | Ishihara Sangyo Kaisha, Ltd. | Lithium titanate, electrode active material and electricity storage device each comprising the same |
| JP2013518377A (en) * | 2010-01-28 | 2013-05-20 | ジュート−ヘミー イーペー ゲーエムベーハー ウント コー カーゲー | Electrode for lithium ion secondary battery |
| JP2013518376A (en) * | 2010-01-28 | 2013-05-20 | ジュート−ヘミー イーペー ゲーエムベーハー ウント コー カーゲー | Electrode for lithium ion secondary battery without added conductive agent |
| JP2011257790A (en) * | 2010-06-04 | 2011-12-22 | Nippon Telegr & Teleph Corp <Ntt> | Relevant information extraction device, method thereof, and program |
| US20200185714A1 (en) * | 2018-12-10 | 2020-06-11 | Lg Chem, Ltd. | Positive Electrode Material, Producing Method Thereof, Positive Electrode and Lithium Secondary Battery Comprising the Same |
| CN114843457A (en) * | 2021-02-01 | 2022-08-02 | 三星Sdi株式会社 | Positive electrode, lithium battery including the same, and method of manufacturing the same |
| JP2022117978A (en) * | 2021-02-01 | 2022-08-12 | 三星エスディアイ株式会社 | Positive electrode, lithium battery adopting the same, and manufacturing method of the same |
| JP7342162B2 (en) | 2021-02-01 | 2023-09-11 | 三星エスディアイ株式会社 | Positive electrode, lithium battery using the same, and manufacturing method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JP4780361B2 (en) | 2011-09-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3619125B2 (en) | Nonaqueous electrolyte secondary battery | |
| CN100583541C (en) | Battery | |
| JP2001110418A (en) | Positive electrode for lithium secondary battery and the lithium secondary battery | |
| JP3491529B2 (en) | Non-aqueous electrolyte secondary battery | |
| JP2016042461A (en) | Positive electrode material, positive electrode including the same and lithium battery including the positive electrode | |
| JP3579280B2 (en) | Negative electrode for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery provided with this negative electrode | |
| JP3229757B2 (en) | Lithium secondary battery | |
| JP2003077476A (en) | Lithium ion secondary battery | |
| JPH11121012A (en) | Nonaqueous electrolytic battery | |
| JP4780361B2 (en) | Lithium secondary battery | |
| JP2006066298A (en) | Lithium secondary battery | |
| JPS63121258A (en) | Nonaqueous secondary battery | |
| JP2003115324A (en) | Nonaqueous electrolyte battery | |
| JP2002216744A (en) | Nonaqueous electrolyte battery and manufacturing method of positive electrode for nonaqueous electrolyte battery | |
| JP4534291B2 (en) | Lithium secondary battery | |
| JP4649691B2 (en) | Positive electrode for lithium secondary battery | |
| JP2003007332A (en) | Lithium secondary battery and manufacturing method of the same | |
| JP2000149996A (en) | Manufacture of nonaqueous electrolyte secondary battery | |
| JPH09306546A (en) | Positive electrode plate for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery | |
| JP2004296305A (en) | Lithium ion secondary battery | |
| JP2002305035A (en) | Lithium secondary battery | |
| JP2002025626A (en) | Aging method for lithium secondary battery | |
| JP4843833B2 (en) | Method for improving low temperature characteristics of lithium secondary battery | |
| JPH11312523A (en) | Electrode for battery and nonaqueous electrolyte battery | |
| JP2001223031A (en) | Lithium secondary battery |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20070905 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20100909 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20100914 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20101105 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20110609 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20110622 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140715 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140715 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140715 Year of fee payment: 3 |
|
| S531 | Written request for registration of change of domicile |
Free format text: JAPANESE INTERMEDIATE CODE: R313532 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140715 Year of fee payment: 3 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| LAPS | Cancellation because of no payment of annual fees |