JPH07235291A - Secondary battery - Google Patents
Secondary batteryInfo
- Publication number
- JPH07235291A JPH07235291A JP6340916A JP34091694A JPH07235291A JP H07235291 A JPH07235291 A JP H07235291A JP 6340916 A JP6340916 A JP 6340916A JP 34091694 A JP34091694 A JP 34091694A JP H07235291 A JPH07235291 A JP H07235291A
- Authority
- JP
- Japan
- Prior art keywords
- positive electrode
- active material
- lithium
- battery
- negative electrode
- 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]
【産業上の利用分野】この発明は、非水電解液二次電池
の性能改善に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improving the performance of a non-aqueous electrolyte secondary battery.
【０００２】[0002]
【従来の技術】電子機器の小型化、軽量化が進められる
中、その電源として高エネルギー密度の二次電池の要望
がさらに強まっている。その要望に答えるため、非水電
解液二次電池が注目され、その実用化が試みられて来
た。特に負極にリチウム金属を使用する、いわゆるリチ
ウム二次電池は最も可能性が大きいと思われたが、金属
リチウム負極は充放電の繰り返しによりバウダー化して
著しくその性能が劣化したり、また金属リチウムがデン
ドライトに析出して内部ショートを引起したりするた
め、実用的なサイクル寿命に問題があり、今だ実用化は
難しい。そこで最近ではカーボンへのリチウムイオンの
出入りを利用するカーボン電極を負極とする非水電解液
二次電池が開発中である。この電池は本発明者等によっ
て、リチウムイオン二次電池と名付けて１９９０年に始
めて世の中に紹介されたもので（雑誌Ｐｒｏｇｒｅｓｓ
Ｉｎ Ｂａｔｔｅｒｉｅｓ ＆ ＳｏｌａｒＣｅｌｌ
ｓ，Ｖｏｌ．９，１９９０，ｐ２０９ 参照）、現在で
は電池業界、学会においても次世代の二次電池“リチウ
ムイオン二次電池”と呼ばれるほどに認識され、その実
用化に拍車がかかっている。代表的には正極材料にリチ
ウム含有複合酸化物を用い、負極にはコークスやグラフ
ァイト等の炭素質材料が用いられる。実際、正極材料と
してＬｉＣｏＯ２を使用し、負極には特殊な炭素材料
（ある程度の乱層構造を有した擬黒鉛材料）を使用し
て、２１０Ｗｈ／ｌ程のエネルギー密度を持つリチウム
イオン二次電池が、既に少量ではあるが携帯電話やビデ
オカメラの電源として実用されている。しかしこの電池
の大きな欠点としては、電池の価格が高くなることであ
る。その一つは過充電保護回路を必要とすることにあ
る。現在実用化されているリチウムイオン二次電池は過
充電された場合に発火したりする危険性があるので、電
池パック内にＩＣ化された過充電保護回路を装着して対
策している。また高価なコバルトを使用することも電池
価格の高くなる大きな要因である。資源的に乏しい理由
からコバルトの価格低下は将来においても望めない。安
価なリチウムイオン二次電池を考える上で、リチウムマ
ンガン複合酸化物が極めて魅力ある正極材料である。リ
チウムマンガン複合酸化物（ＬｉＭｎ２Ｏ４等）は安価
な材料で、加えて過充電における安全性がきわめて高
く、過充電保護回路を必要としない。正極活物質にＬｉ
ＣｏＯ２を使用し、負極に炭素質材料を使用したリチウ
ムイオン二次電池の電池反応は次のようになる。正規の
充放電反応では、 過充電においては、 正極：Ｌｉ１−ｘＣｏＯ２→Ｌｉ１−ｘ−αＣｏＯ２
＋ αＬｉ＋ ＋αｅ−（３） 負極：ＬｉＣ６＋αＬｉ＋＋αｅ− → ＬｉＣ６ ＋
Ｌｉ０（金属）（４） 正規の充電では正極活物質中の約６割のリチウムが引き
抜かれ、負極中カーボンにドーピングされる。そして正
極活物質はＬｉ１−ｘＣｏＯ２（ｘ≒０．６）となって
いるが、過充電ではさらに残りのリチウムが引き抜かれ
ることになり、過充電において引き抜かれたリチウムは
負極では金属リチウムとして負極表面に析出する。この
負極表面に析出した金属リチウムは、極めて活性である
ために電解液と激しく反応して熱暴走することがあり、
過充電における安全性に不安がある。一方、正極にリチ
ウムマンガン複合酸化物（ＬｉＭｎ２Ｏ４等）を使用し
た場合には、正規の充放電反応で下記に示す反応（５）
が正極反応である。つまり、正規の充電において正極中
のリチウムはほとんど引き抜かれ、過充電ではもはや正
極中より負極へ移動するリチウムは存在しない。したが
って過充電で負極に金属リチウムが析出することがな
く、過充電での安全性が確保される。 しかし、残念ながら価格面、安全性の面では大きな特長
を持ちながら、リチウムマンガン複合酸化物を正極材料
とするリチウムイオン二次電池は充放電サイクルに伴う
容量の劣化が大きく、特に高温下（３５℃以上）での充
放電サイクルに伴う容量の劣化が大きいため、まだ実用
化されていない。2. Description of the Related Art As electronic devices are becoming smaller and lighter, there is a growing demand for high energy density secondary batteries as their power sources. In order to meet the demand, attention has been paid to non-aqueous electrolyte secondary batteries, and attempts have been made to put them into practical use. In particular, the so-called lithium secondary battery, which uses lithium metal for the negative electrode, seemed to have the greatest potential, but the metallic lithium negative electrode became a bower due to repeated charging and discharging, and its performance was significantly deteriorated. Since it deposits on dendrites and causes an internal short circuit, there is a problem with practical cycle life, and it is still difficult to put it into practical use. Therefore, recently, a non-aqueous electrolyte secondary battery having a carbon electrode as a negative electrode, which utilizes the movement of lithium ions into and out of carbon, is under development. This battery was introduced to the world by the present inventors for the first time in 1990 under the name of lithium ion secondary battery (Progress magazine).
In Batteries & SolarCell
s, Vol. 9, 1990, p. 209), and nowadays it is recognized in the battery industry and academic societies as to be called the next-generation secondary battery “lithium ion secondary battery”, and its practical application is accelerating. Typically, a lithium-containing composite oxide is used for the positive electrode material, and a carbonaceous material such as coke or graphite is used for the negative electrode. In fact, LiCoO 2 is used as the positive electrode material, and a special carbon material (pseudo-graphite material having a certain degree of disordered layer structure) is used as the negative electrode, and a lithium ion secondary battery having an energy density of about 210 Wh / l. However, it has already been put into practical use as a power source for mobile phones and video cameras, albeit in a small amount. However, a major drawback of this battery is the high cost of the battery. One is that it requires an overcharge protection circuit. Since the lithium-ion secondary battery currently put into practical use has a risk of catching fire when overcharged, an IC-based overcharge protection circuit is mounted in the battery pack as a countermeasure. The use of expensive cobalt is also a major factor in increasing the battery price. Due to the scarcity of resources, the price decline of cobalt cannot be expected in the future. The lithium-manganese composite oxide is a very attractive positive electrode material when considering an inexpensive lithium-ion secondary battery. Lithium-manganese composite oxide (LiMn 2 O 4 etc.) is an inexpensive material, has extremely high safety in overcharge, and does not require an overcharge protection circuit. Li as the positive electrode active material
The battery reaction of a lithium ion secondary battery using CoO 2 and a carbonaceous material for the negative electrode is as follows. In a regular charge / discharge reaction, In overcharge, the positive electrode: Li 1-x CoO 2 → Li 1-x-α CoO 2
+ ΑLi + + αe − (3) Negative electrode: LiC 6 + αLi + + αe − → LiC 6 +
Li 0 (Metal) (4) In regular charging, about 60% of lithium in the positive electrode active material is extracted and the carbon in the negative electrode is doped. The positive electrode active material is Li 1-x CoO 2 (x≈0.6), but the remaining lithium is further extracted by overcharge, and the lithium extracted by overcharge is metallic lithium in the negative electrode. Is deposited on the surface of the negative electrode. The metallic lithium deposited on the surface of the negative electrode is extremely active and may react violently with the electrolytic solution to cause thermal runaway.
I am worried about the safety of overcharging. On the other hand, when a lithium manganese composite oxide (LiMn 2 O 4 etc.) is used for the positive electrode, the reaction (5) shown below occurs in a regular charge / discharge reaction.
Is the positive electrode reaction. That is, most of the lithium in the positive electrode is extracted during normal charging, and there is no lithium that moves from the positive electrode to the negative electrode during overcharging. Therefore, metal lithium does not deposit on the negative electrode due to overcharge, and safety during overcharge is secured. However, unfortunately, lithium-ion secondary batteries using lithium-manganese composite oxide as a positive electrode material have large capacity deterioration associated with charge / discharge cycles, especially at high temperatures (35 It has not been put to practical use yet because the capacity is greatly deteriorated with a charge / discharge cycle at temperatures above ℃.
【０００３】[0003]
【発明が解決しようとする課題】本発明はスピネル型リ
チウムマンガン複合酸化物を主たる正極活物質材料と
し、過充電での安全性も高く、サイクル特性も良好なリ
チウムイオン二次電池を提供しようとするものである。DISCLOSURE OF THE INVENTION The present invention uses a spinel type lithium manganese composite oxide as a main positive electrode active material, and aims to provide a lithium ion secondary battery having high safety in overcharge and good cycle characteristics. To do.
【０００４】[0004]
【課題を解決するための手段】正極中に主たる正極活物
質であるリチウムマンガン複合酸化物に混じて、固体の
リチウムイオン伝導体を含有せしめる。炭素材料を負極
活物質とした場合の一つの具体的方法は、５モル％以上
５０モル％以下でＬｉＣｏ１−ｙＮｉｙＯ２（ただし、
０≦ｙ≦１）を混合して正極を作成し、正極活物質層に
含有するＭｎのモル数（ａ）、ＣｏおよびＮｉのモル数
の和（ｂ）、正極と対向する負極活物質層に含有する活
物質炭素のモル数（ｃ）との間で、０．１２≦（ａ＋２
ｂ）／２ｃ≦０．１７の関係にあるようにする。Means for Solving the Problems A solid lithium ion conductor is contained in a positive electrode by being mixed with a lithium manganese composite oxide which is a main positive electrode active material. One specific method when the carbon material is used as the negative electrode active material is 5 mol% or more and 50 mol% or less of LiCo 1-y Ni y O 2 (however,
0 ≦ y ≦ 1) to prepare a positive electrode, the number of moles of Mn contained in the positive electrode active material layer (a), the sum of the number of moles of Co and Ni (b), and the negative electrode active material layer facing the positive electrode. 0.12 ≦ (a + 2) with the number of moles (c) of the active material carbon contained in
b) /2c≦0.17.
【０００５】[0005]
【作用】正極活物質としてＬｉＣｏＯ２で代表される一
般式ＬｉＣｏ１−ｙＮｉｙＯ２（ただし、０≦ｙ≦１）
で示される複合酸化物を使用したリチウムイオン二次電
池は良好な充放電サイクル特性を示す。この場合、正規
の充電（充電電圧４．２Ｖ）では正極活物質中に存在し
ていたリチウムの約６０％が引き抜かれ、充電完了時点
でも正極活物質中には４０％のリチウムが残存する。従
って活物質中の充分な残存リチウムによって活物質のイ
オン伝導は良好に保たれるので、充放電のサイクルに伴
う容量劣化が少ないものと考えられる。しかし前にも述
べたとおり、正極活物質中の残存リチウムは過充電にお
いては負極への金属リチウム析出を来たし、過充電での
安全性を損なう。Function A general formula LiCo 1-y Ni y O 2 represented by LiCoO 2 as a positive electrode active material (where 0 ≦ y ≦ 1)
The lithium-ion secondary battery using the composite oxide represented by shows good charge-discharge cycle characteristics. In this case, in regular charging (charging voltage 4.2V), about 60% of the lithium present in the positive electrode active material is extracted, and 40% of lithium remains in the positive electrode active material even at the time of completion of charging. Therefore, the sufficient lithium remaining in the active material keeps the ionic conduction of the active material in good condition, and it is considered that the capacity deterioration due to charge / discharge cycles is small. However, as described above, the residual lithium in the positive electrode active material causes the deposition of metallic lithium on the negative electrode during overcharge, which impairs safety during overcharge.
【０００６】一方、正極活物質にスピネル型リチウムマ
ンガン複合酸化物（代表的にはＬｉＭｎ２Ｏ４）を使用
するリチウムイオン二次電池では、正規の充電反応（充
電電圧４．２Ｖ）において正極活物質中のリチウムはほ
とんど引き抜かれてしまう。これが過充電においても安
全な理由ではあるが、一方では充放電のサイクルに伴う
容量劣化の原因とも考えられる。つまり充電完了時点で
は正極活物質中には残存リチウムが極めて少なく、リチ
ウムイオンの活物質結晶内の移動でもたらされるべきイ
オン伝導が損なわれ、反応出来ない活物質がだんだん増
えていくことか容量劣化の原因と考えられる。電極活物
質の充放電反応が効率よく進行するためには、全ての活
物質への良好な電子伝導とイオン伝導が保たれなければ
ならない。活物質への電子伝導付与は、グラファイトや
アセチレンブラックなどの導電助剤の混合によって従来
から行われていが、活物質へのイオン伝導付与に関して
は前例がない。On the other hand, in a lithium-ion secondary battery using a spinel type lithium manganese composite oxide (typically LiMn 2 O 4 ) as a positive electrode active material, the positive electrode is activated in a regular charging reaction (charging voltage 4.2V). Most of the lithium in the substance is extracted. This is the reason why it is safe even in overcharge, but on the other hand, it is also considered to be the cause of capacity deterioration due to charge / discharge cycles. In other words, at the time of completion of charging, there is very little residual lithium in the positive electrode active material, the ion conduction that should be caused by the movement of lithium ions in the active material crystal is impaired, and the number of active materials that cannot react increases gradually or the capacity deteriorates. Is considered to be the cause. In order for the charge / discharge reaction of the electrode active material to proceed efficiently, good electron conduction and ionic conduction to all active materials must be maintained. The electron conductivity is given to the active material by mixing a conductive auxiliary agent such as graphite or acetylene black, but there is no precedent for giving the ion conduction to the active material.
【０００７】本発明では、正極中にリチウムイオン導電
性を有する固体を含有せしめることで、充電完了時点で
も、残存リチウムが少なくなってリチウムイオンの伝導
性が損なわれた活物質にリチウムイオン伝導性を援助
し、スピネル型リチウムマンガン複合酸化物を正極活物
質としたリチウムイオン二次電池のサイクル特性を大幅
に改善しようとするものである。ＬｉＣｏ１−ｙＮｉｙ
Ｏ２からＬｉをある程度引き抜いたＬｉｘＣｏ１−ｙＮ
ｉｙＯ２（ただし、０＜ｘ＜１、０≦ｙ≦１）は良好な
リチウムイオン伝導体であることが知られている。従っ
てＬｉｘＣｏ１−ｙＮｉｙＯ２（ただし、０＜Ｘ＜１、
０≦ｙ≦１）をイオン伝導補助剤として正極中に含有せ
しめることで、一つの実施方法として本発明が実施でき
る。In the present invention, by incorporating a solid having lithium ion conductivity in the positive electrode, the amount of residual lithium is reduced and the lithium ion conductivity is impaired even when the charging is completed. To significantly improve the cycle characteristics of a lithium ion secondary battery using a spinel type lithium manganese composite oxide as a positive electrode active material. LiCo 1-y Ni y
Li x Co 1-y N obtained by extracting Li to some extent from O 2.
It is known that i y O 2 (where 0 <x <1, 0 ≦ y ≦ 1) is a good lithium ion conductor. Therefore, Li x Co 1-y Ni y O 2 (where 0 <X <1,
By including 0 ≦ y ≦ 1) as an ion conduction auxiliary agent in the positive electrode, the present invention can be carried out as one method of implementation.
【０００８】具体的な実施においては主活物質であるリ
チウムマンガン複合酸化物に対して５モル％以上でＬｉ
Ｃｏ１−ｙＮｉｙＯ２（ただし、０≦ｙ≦１）を混合し
て正極を作成すればよい。添加したＬｉＣｏ１−ｙＮｉ
ｙＯ２は活物質としても働き、一部リチウムイオンが引
き抜かれ、正極中ではＬｉｘＣｏ１−ｙＮｉｙＯ２（た
だし、０＜ｘ＜１、０≦ｙ≦１）の状態で存在するの
で、イオン伝導補助剤として有効に働き、主活物質の充
放電効率が良好に持続される。しかしＬｉＣｏ１−ｙＮ
ｉｙＯ２の混合は基本的に正極材料費を上げることとな
るし、ＬｉｘＣｏ１−ｙＮｉｙＯ２中の残存リチウムは
過充電において負極への金属リチウムの析出を来たし、
過充電での安全性を損なう原因ともなるので、本発明で
はＬｉｘＣｏ１−ｙＮｉｙＯ２は正極主活物質に対して
５モル％以上５０モル％以下、好ましくは３０モル％以
下、さらに好ましくは２０モル％以下に規制する。さら
に負極活物質として炭素質材料を使用して電池を作成す
る場合は、正極活物質層に含有するＭｎのモル数
（ａ）、ＣｏおよびＮｉのモル数の和（ｂ）および正極
と対向する負極活物質層に含有する活物質炭素のモル数
（ｃ）が ０．１２≦（ａ＋２ｂ）／２ｃ≦０．１７ の関係を満たすことによって、過充電での安全性も確保
される。[0008] In a specific implementation, the lithium-manganese composite oxide, which is the main active material, contains 5 mol% or more of Li.
Co 1-y Ni y O 2 (where 0 ≦ y ≦ 1) may be mixed to form the positive electrode. Added LiCo 1-y Ni
y O 2 also functions as an active material, some lithium ions are extracted, and it exists in the state of Li x Co 1-y Ni y O 2 (where 0 <x <1, 0 ≦ y ≦ 1) in the positive electrode. Therefore, it works effectively as an ion conduction auxiliary agent, and the charge / discharge efficiency of the main active material is favorably maintained. However, LiCo 1-y N
The mixture of i y O 2 basically raises the cost of the positive electrode material, and the residual lithium in Li x Co 1-y Ni y O 2 causes the deposition of metallic lithium on the negative electrode during overcharge,
In the present invention, Li x Co 1-y Ni y O 2 is contained in an amount of 5 mol% or more and 50 mol% or less, preferably 30 mol% or less, relative to the positive electrode main active material, because it may cause a loss of safety in overcharging. It is more preferably regulated to 20 mol% or less. Further, when a battery is made using a carbonaceous material as the negative electrode active material, the number of moles of Mn (a), the sum of the numbers of moles of Co and Ni contained in the positive electrode active material layer (b), and the positive electrode are opposed to the positive electrode. When the number of moles (c) of the active material carbon contained in the negative electrode active material layer satisfies the relationship of 0.12 ≦ (a + 2b) /2c≦0.17, safety in overcharging is also secured.
【０００９】上記式において（ａ＋２ｂ）／２は初回充
電前の負極と対向する正極活物質層に元来含有していた
リチウム量（Ｚ）に等しい。本発明者はリチウムマンガ
ン複合酸化物とＬｉＣｏ１−ｙＮｉｙＯ２の混合比率お
よびＺ／ｃの値を変化させて電池特性を比較検討した結
果、電池容量、過充電での安全性、充放電サイクル性能
が何れも充分確保される前記範囲を見いだした。In the above formula, (a + 2b) / 2 is equal to the amount of lithium (Z) originally contained in the positive electrode active material layer facing the negative electrode before initial charging. The present inventor compared the battery characteristics by changing the mixing ratio of the lithium manganese oxide and LiCo 1-y Ni y O 2 and the value of Z / c, and as a result, the battery capacity, safety in overcharging, charging The above range was found in which the discharge cycle performance was sufficiently secured.
【００１０】[0010]
【実施例】以下、実施例により本発明をさらに詳しく説
明する。The present invention will be described in more detail with reference to the following examples.
【００１１】実施例１ 炭素質材料を負極活物質とする電池への本発明の実施例
を、図１〜４を参照しながら円筒型電池について説明す
る。図１は本実施例の電池の全体構造を示すものであ
る。本発明を実施するための発電要素である電池素子は
次のようにして用意した。２８００℃で熱処理をしたメ
ソカーボンマイクロビーズ（ｄ００２＝３．３７Å）の
８６重量部にアセチレンブブラックの４重量部、結着剤
としてポリフッ化ビニリデン（ＰＶＤＦ）１０重量部を
加え、溶剤であるＮ−メチル−２−ピロリドンと湿式混
合して負極合剤ペーストとした。そしてこの負極合剤ペ
ーストを負極集電体となる厚さ０．０１ｍｍの銅箔の両
面に種々の塗布量で均一に塗布し、乾燥後ローラープレ
ス機で加圧成型して、帯状の負極（１）を種々の活物質
炭素量を含有させて作成した。Example 1 An example of the present invention for a battery using a carbonaceous material as a negative electrode active material will be described with reference to FIGS. 1 to 4 for a cylindrical battery. FIG. 1 shows the overall structure of the battery of this embodiment. A battery element which is a power generation element for carrying out the present invention was prepared as follows. To 86 parts by weight of mesocarbon microbeads (d 002 = 3.37Å) heat-treated at 2800 ° C., 4 parts by weight of acetylene black and 10 parts by weight of polyvinylidene fluoride (PVDF) as a binder were added, and the mixture was used as a solvent. It was wet-mixed with N-methyl-2-pyrrolidone to obtain a negative electrode mixture paste. Then, the negative electrode mixture paste was uniformly applied on both surfaces of a 0.01 mm-thick copper foil serving as a negative electrode collector in various coating amounts, dried, and then pressure-molded with a roller press machine to form a strip-shaped negative electrode ( 1) was prepared by incorporating various amounts of carbon in the active material.
【００１２】続いて正極を次のようにして用意した。市
販の二酸化マンガン（ＭｎＯ２）と炭酸リチウム（Ｌｉ
２ＣＯ３）をＬｉとＭｎの原子比が１：２の組成比にな
るように混合し、これを空気中７５０℃で２０時間焼成
してＬｉＭｎ２Ｏ４を調整した。次に市販の炭酸リチウ
ム（Ｌｉ２ＣＯ３）と炭酸コバルト（ＣｏＣＯ３）をＬ
ｉとＣｏの原子比が１：１の組成比になるように混合
し、空気中８５０℃で約５時間焼成してＬｉＣｏＯ２を
調整した。こうして調整したＬｉＭｎ２Ｏ４とＬｉＣｏ
Ｏ２は表１に示す種々のモル比で混合し、その混合物８
７重量部にアセチレンブラック２重量部、グラファイト
８重量部を加えてよく混合し、さらに結合剤としてポリ
フッ化ビニリデン３重量部と溶剤であるＮ−メチル−２
−ピロリドンを加えて湿式混合して、ＬｉＭｎ２Ｏ４へ
のＬｉＣｏＯ２の混合比率の異なる正極合剤ペーストを
用意した。この正極合剤ペーストは正極集電体となる厚
さ０．０２ｍｍのアルミニウム箔の両面に種々の塗布量
で均一に塗布し、乾燥後ローラープレス機で加圧成型し
て帯状の正極（２）を種々の活物質量を含有させて作成
した。Subsequently, a positive electrode was prepared as follows. Commercially available manganese dioxide (MnO 2 ) and lithium carbonate (Li
2 CO 3 ) was mixed so that the atomic ratio of Li and Mn was 1: 2, and this was baked in air at 750 ° C. for 20 hours to prepare LiMn 2 O 4 . Next, commercially available lithium carbonate (Li 2 CO 3 ) and cobalt carbonate (CoCO 3 ) were mixed with L
Li and Co were mixed so that the atomic ratio was 1: 1 and the mixture was baked in air at 850 ° C. for about 5 hours to prepare LiCoO 2 . LiMn 2 O 4 and LiCo thus adjusted
O 2 was mixed in various molar ratios shown in Table 1 to obtain a mixture 8
To 7 parts by weight, 2 parts by weight of acetylene black and 8 parts by weight of graphite were added and mixed well, and further 3 parts by weight of polyvinylidene fluoride as a binder and N-methyl-2 as a solvent.
- and wet mixed with the pyrrolidone to prepare different positive electrode material mixture paste of a mixture ratio of LiCoO 2 to LiMn 2 O 4. This positive electrode material mixture paste was applied uniformly on both sides of a 0.02 mm-thick aluminum foil serving as a positive electrode current collector in various coating amounts, dried and then pressure-molded with a roller press machine to form a strip-shaped positive electrode (2). Was prepared by containing various amounts of active materials.
【００１３】こうして作成した負極（１）と正極（２）
はその間に多孔質ポリプロピレン製セパレータ（３）を
挟んでロール状に巻き上げて、平均外径１５．７ｍｍの
巻回体として電池素子を作成した。次にニッケルメッキ
を施した鉄製の電池缶（４）の底部に絶縁板（５）を設
置し、上記電池素子を収納する。電池素子より取り出し
た負極リード（６）を上記電池缶の底に溶接し、電池缶
の中に１モル／リットルのＬｉＰＦ６を溶解したエチレ
ンカーボネイト（ＥＣ）とジエチルカーボネート（ＤＥ
Ｃ）の混合溶液を電解液として注入する。その後、電池
素子の上部にも絶縁板（５）を設置し、ガスケット
（７）を嵌め、防爆弁（８）を図１に示すように電池内
部に設置する。電池素子より取り出した正極リード
（９）はこの防爆弁に電解液を注入する前に溶接してお
く。防爆弁の上には正極外部端子となる閉塞蓋体（１
０）をドーナツ型ＰＴＣスイッチ（１１）を挟んで重
ね、電池缶の縁をかしめて、図１に示す電池構造で外径
１６．５ｍｍ、高さ６５ｍｍで電池（Ａ）〜（Ｏ）の合
計１５種類の電池を作成した。この１５種類の電池はそ
れぞれ表１に示す設計値となっている。The negative electrode (1) and the positive electrode (2) thus prepared
A porous polypropylene separator (3) was sandwiched between the rolls and wound up in a roll to prepare a battery element as a wound body having an average outer diameter of 15.7 mm. Next, the insulating plate (5) is placed on the bottom of the nickel-plated iron battery can (4) to house the battery element. The negative electrode lead (6) taken out from the battery element was welded to the bottom of the battery can, and 1 mol / l of LiPF 6 was dissolved in the battery can, ethylene carbonate (EC) and diethyl carbonate (DE).
The mixed solution of C) is injected as an electrolytic solution. Then, the insulating plate (5) is also installed on the upper part of the battery element, the gasket (7) is fitted, and the explosion-proof valve (8) is installed inside the battery as shown in FIG. The positive electrode lead (9) taken out from the battery element is welded before injecting the electrolytic solution into this explosion-proof valve. On the explosion-proof valve, a closing lid (1
0) are stacked with a doughnut-type PTC switch (11) sandwiched between them, and the edges of the battery can are crimped, and the battery structure shown in FIG. 1 has an outer diameter of 16.5 mm, a height of 65 mm, and the total of batteries (A) to (O). Fifteen types of batteries were created. The 15 types of batteries have the design values shown in Table 1, respectively.
【００１４】作成した電池は、いずれも電池内部の安定
化を目的に常温で１２時間のエージング期間を経過させ
た後、充電上限電圧を４．２Ｖに設定し、常温で８時間
の充電を行い、放電は同じく常温で全ての電池について
８００ｍＡの定電流放電にて終止電圧３．０Ｖまで行
い、それぞれの電池の初期放電容量を求めた。初期放電
容量は表２に示す。 その後各電池は４０℃で充放電サイクル試験を行った。
充電電流は４００ｍＡで、充電上限電圧は４．２Ｖに設
定して４時間の充電を行い、放電は８００ｍＡの定電流
放電にて終止電圧３．０Ｖまで行って充放電を繰り返し
た。Each of the batteries thus prepared was subjected to an aging period of 12 hours at room temperature for the purpose of stabilizing the inside of the battery, then the charge upper limit voltage was set to 4.2 V, and the battery was charged at room temperature for 8 hours. Similarly, all batteries were discharged at a constant current of 800 mA at room temperature to a final voltage of 3.0 V, and the initial discharge capacity of each battery was determined. The initial discharge capacity is shown in Table 2. Thereafter, each battery was subjected to a charge / discharge cycle test at 40 ° C.
The charging current was 400 mA, the charging upper limit voltage was set to 4.2 V, charging was performed for 4 hours, and discharging was performed by constant current discharging of 800 mA to a final voltage of 3.0 V, and charging and discharging were repeated.
【００１５】サイクル特性は図２に示すように、ＬｉＣ
ｏＯ２を１００％使用した電池（Ｄ）は１５０サイクル
後でも８５％以上の高い容量維持率であるのに対し、Ｌ
ｉＣｏＯ２を全く添加していない電池（Ａ）はサイクル
に伴う容量低下が大きく１５０サイクル程で初期容量の
半分近くへ低下してしまう。ところが５％以上のＬｉＣ
ｏＯ２を混合した電池ではＬｉＣｏＯ２を１００％使用
した電池（Ｄ）と同程度までに容量維持率が改善され
る。しかし３モル％のＬｉＣｏＯ２の混合では不充分
で、少なくとも容量維持率の効果的改善には５％以上の
ＬｉＣｏＯ２の混合が必要であることがわかる。さらに
表２の結果をもとに、各電池の初期放電容量と各電池へ
のＬｉＣｏＯ２の混合比率との関係を見てみると、 図
３に示すように、Ｚ／ｃが一定のときＬｉＣｏＯ２の混
合比率か増すと容量か減少する。しかもリチウムマンガ
ン複合酸化物（ＬｉＭｎ２Ｏ４）を正極材料とするリチ
ウムイオン二次電池の大きな特長の一つは安価な材料で
ある点にあるので、高価なＬｉＣｏＯ２の添加は５０％
以下、好ましくは３０％以下、さらに好ましくは２０％
以下が望ましい。さらに、Ｚ／ｃが０．１１２の場合
（電池Ｈ、Ｉ、Ｊ）は何れも初期容量が小さくなること
から０．１２≦Ｚ／ｃが必要である。The cycle characteristics are as shown in FIG.
The battery (D) using 100% of oO 2 has a high capacity retention rate of 85% or more even after 150 cycles, while L
The battery (A) to which iCoO 2 was not added at all had a large decrease in capacity with cycles, and the capacity decreased to almost half of the initial capacity after about 150 cycles. However, 5% or more of LiC
The capacity retention rate of the battery containing oO 2 is improved to the same extent as the battery (D) using 100% LiCoO 2 . However, it can be seen that the mixing of 3 mol% LiCoO 2 is not sufficient, and at least 5% or more of LiCoO 2 must be mixed to effectively improve the capacity retention ratio. Furthermore, based on the results of Table 2, the relationship between the initial discharge capacity of each battery and the mixing ratio of LiCoO 2 to each battery is examined. As shown in FIG. 3, when Z / c is constant, LiCoO 2 is constant. When the mixing ratio of 2 is increased, the capacity is decreased. Moreover, one of the major features of the lithium-ion secondary battery using the lithium manganese composite oxide (LiMn 2 O 4 ) as the positive electrode material is that it is an inexpensive material, so the addition of expensive LiCoO 2 is 50%.
Or less, preferably 30% or less, more preferably 20%
The following is desirable. Further, when Z / c is 0.112 (batteries H, I, and J), the initial capacity becomes small, so 0.12 ≦ Z / c is required.
【００１６】リチウムマンガン複合酸化物（ＬｉＭｎ２
Ｏ４）を正極材料とするリチウムイオン二次電池のもう
一つの大きな特長は過充電における安全性にある。試作
した電池は次のようにして過充電での安全性を評価し
た。まず正規の充電として、充電電流は４００ｍＡで、
充電上限電圧は４．２Ｖに設定して４時間の充電を行っ
た。続いて充電上限電圧を１０Ｖに設定し、充電電流を
１．６Ａに上げて１時間過充電を行って、電池表面の最
高到達温度を測定して図４に示した。Ｚ／ｃが０．１７
以下の電池ではほぼ１２０℃が最高到達温度であるが、
Ｚ／ｃ＝０．１７９では１６０℃以上に上がり、Ｚ／ｃ
＝０．１９の電池は結局電池内部より火を吹きだし３０
０℃以上の温度に達してしまった。先に電池容量の観点
から０．１２≦Ｚ／ｃであるとしたが、過充電の安全性
の点からはＺ／ｃ≦１．７とすべきである。ここで使用
するＺの値は初回充電前の負極と対向する正極活物質層
に元来含有していたリチウム量（Ｚ）であり、正極活物
質中の遷移元素（実施例ではＭｎおよびＣｏ）量との関
係においては Ｚ＝（ａ＋２ｂ）／２ （ただしａ、ｂはそれぞれ正極中のＭｎおよびＣｏの含
有モル数）であり、（ａ＋２ｂ）／２はいかなる充放電
状態によっても不変であるので、便宜上これをもって過
充電の安全性を確保できる最適な設計値として次のよう
に表すことが出来る。 ０．１２≦（ａ＋２ｂ）／２ｃ≦１．７Lithium manganese composite oxide (LiMn 2
Another major feature of the lithium ion secondary battery using O 4 ) as a positive electrode material is safety in overcharging. The prototype battery was evaluated for safety in overcharge as follows. First, for regular charging, the charging current is 400 mA,
The charging upper limit voltage was set to 4.2 V and charging was performed for 4 hours. Subsequently, the charging upper limit voltage was set to 10 V, the charging current was raised to 1.6 A and overcharging was performed for 1 hour, and the highest temperature reached on the battery surface was measured and shown in FIG. Z / c is 0.17
In the batteries below, the maximum temperature reached is approximately 120 ° C,
When Z / c = 0.179, the temperature rises to 160 ° C or higher, and Z / c
= 0.19 battery eventually blows fire from inside the battery 30
The temperature has reached 0 ° C or higher. Although 0.12 ≦ Z / c was described above from the viewpoint of battery capacity, Z / c ≦ 1.7 should be satisfied from the viewpoint of overcharge safety. The value of Z used here is the amount of lithium (Z) originally contained in the positive electrode active material layer facing the negative electrode before initial charging, and is a transition element (Mn and Co in the examples) in the positive electrode active material. In relation to the amount, Z = (a + 2b) / 2 (where a and b are the number of moles of Mn and Co contained in the positive electrode), and (a + 2b) / 2 is invariable under any charge / discharge state. For convenience, this can be expressed as the following as an optimum design value that can ensure the safety of overcharge. 0.12 ≦ (a + 2b) /2c≦1.7
【００１７】実施例２ 市販の炭酸リチウム（Ｌｉ２ＣＯ３）と炭酸コバルト
（ＣｏＣＯ３）および炭酸ニッケル（ＮｉＣＯ３）をＬ
ｉとＣｏとＮｉの原子比が１：０．５：０．５の組成比
になるように混合し、空気中８５０℃で約５時間焼成し
てリチウムコバルトニッケル複合酸化物（ＬｉＣｏ
０．５Ｎｉ０．５Ｏ２）を調整した。調整したＬｉＣｏ
０．５Ｎｉ０．５Ｏ２は実施例１で調整したＬｉＭｎ２
Ｏ４に表３に示すモル比で混合し、その混合物を正極活
物質として、実施例１と全く同様にして電池（Ｐ）、
（Ｑ）、（Ｒ）を作成し、実施例１と同様な評価を行
い、その結果を表３に示した。実施例２では実施例１で
のＬｉＣｏＯ２の代わりにＬｉＣｏ０．５Ｎｉ０．５Ｏ
２を使用し、電池（Ｐ）は実施例１で見いだされた適正
な設計値で、電池（Ｑ）はＺ／ｃ＝０．１９で適正範囲
からはずれた設計値となっており、電池（Ｒ）はＬｉＣ
ｏ０．５Ｎｉ０．５Ｏ２の混合量が不充分な範囲で試作
した。Example 2 Commercially available lithium carbonate (Li 2 CO 3 ), cobalt carbonate (CoCO 3 ), and nickel carbonate (NiCO 3 ) were added as L.
i, Co, and Ni were mixed so that the atomic ratio was 1: 0.5: 0.5, and the mixture was fired in air at 850 ° C. for about 5 hours to obtain a lithium cobalt nickel composite oxide (LiCo
0.5 Ni 0.5 O 2 ) was prepared. Adjusted LiCo
0.5 Ni 0.5 O 2 is LiMn 2 prepared in Example 1.
A battery (P) was mixed with O 4 in a molar ratio shown in Table 3, and the mixture was used as a positive electrode active material in exactly the same manner as in Example 1.
(Q) and (R) were prepared and evaluated in the same manner as in Example 1, and the results are shown in Table 3. In Example 2, LiCo 0.5 Ni 0.5 O was used instead of LiCoO 2 in Example 1.
2 is used, the battery (P) has a proper design value found in Example 1, and the battery (Q) has a design value outside the proper range at Z / c = 0.19. R) is LiC
A trial production was carried out in a range in which the amount of o 0.5 Ni 0.5 O 2 was insufficient.
【００１８】結果は表３に示したように電池（Ｐ）は容
量、過充電での安全性、サイクル特性全てにおいて実施
例１の結果から予測される満足な結果を示したのに対
し、電池（Ｑ）は過充電での安全性が確保されず、電池
（Ｒ）はサイクル特性におい て容量劣化の大きい結果となり、ＬｉＣｏＯ２の代わり
にＬｉＣｏ０．５Ｎｉ０．５Ｏ２を使用しても同様な結
果が得られることがわかる。従ってリチウムマンガン複
合酸化物を正極活物質とするリチウムイオン二次電池に
おいては、リチウムイオンの良好なイオン伝導体として
知られるＬｉｘＣｏ１−ｙＮｉｙＯ２（ただし、０＜ｘ
＜１、０≦ｙ≦１）を正極中にイオン伝導補助剤として
含有せしめることが、そのサイクル特性の改善に有効で
あることが明らかである。As shown in Table 3, the battery (P) showed satisfactory results predicted from the results of Example 1 in all of capacity, safety in overcharge, and cycle characteristics, whereas the battery (P) showed (Q) does not ensure safety in overcharging, and battery (R) has a cycle characteristic As a result, the capacity deterioration is large, and it is understood that similar results can be obtained by using LiCo 0.5 Ni 0.5 O 2 instead of LiCoO 2 . Therefore, in a lithium ion secondary battery using a lithium manganese composite oxide as a positive electrode active material, Li x Co 1-y Ni y O 2 (where 0 <x
It is clear that the inclusion of <1, 0 ≦ y ≦ 1) in the positive electrode as an ion conduction aid is effective in improving the cycle characteristics.
【００１９】またこのスピネル型リチウムマンガン複合
酸化物にイオン伝導を付加するという、サイクル特性改
善手法は、イオン伝導補助剤として他のリチウムイオン
伝導体を使用することも当然可能である。The cycle characteristic improving method of adding ionic conduction to the spinel type lithium manganese composite oxide can naturally use other lithium ion conductors as an ionic conduction auxiliary agent.
【００２０】前述の実施例では負極活物質として２８０
０℃で熱処理をしたメソカーボンマイクロビーズ（ｄ
００２＝３．３７Å）を使用したが、他の炭素材料（ピ
ッチコークス、石油系コークス、天然黒鉛等）を負極活
物質とする場合も同様の効果が期待できる。In the above-mentioned embodiment, 280 is used as the negative electrode active material.
Mesocarbon microbeads (d
002 = 3.37Å) was used, but the same effect can be expected when other carbon materials (pitch coke, petroleum coke, natural graphite, etc.) are used as the negative electrode active material.
【００２１】さらには、本発明による第一の改善はスピ
ネル型リチウムマンガン複合酸化物を正極活物質とする
非水電解液二次電池において、正極活物質にイオン伝導
を付加してサイクル特性を改善するものであり、この本
発明による第一の改善は炭素材料以外の、例えばリチウ
ム金属やリチウム合金、遷移金属の硫化物（ＴｉＳ２、
ＮｂＳ２、ＶＳ２等）、 Ｌｉ１＋ｘＴｉ２−ｘＯ
４（０≦Ｘ≦１／３）、Ｎｂ２Ｏ３等を負極活物質とす
る場合にも適用できるものである。Further, the first improvement of the present invention is to improve the cycle characteristics by adding ion conduction to the positive electrode active material in a non-aqueous electrolyte secondary battery using a spinel type lithium manganese composite oxide as the positive electrode active material. The first improvement according to the present invention is, for example, a sulfide (TiS 2 ,
NbS 2, VS 2, etc.), Li 1 + x Ti 2 -x O
4 (0 ≦ X ≦ 1/3), Nb 2 O 3 and the like can be applied to the negative electrode active material.
【００２２】また本実施例では本実施例で使用した負極
活物質に最もよく適合する電解液の一つとして１モル／
リットルのＬｉＰＦ６を溶解したエチレンカーボネイト
（ＥＣ）とジエチルカーボネート（ＤＥＣ）の混合溶液
を使用したが、この他従来から知られている各種の非水
溶媒に各種のリチウム塩を溶解して構成される非水電解
液が、使用する負極活物質との適合性から選択して使用
することが出来る。非水電解液を構成できる非水溶媒と
してはプロピレンカーボネート、エチレンカーボネー
ト、γ−ブチロラクトン、ジメトキシエタン、ジエトキ
シエタン、ジエチルエーテル、テトラヒドロフラン、ジ
オキソラン、スルホラン、メチルスルホラン等が公知で
あり、これらの単独又は２種以上が混合して使用され
る。リチウム塩としてはＬｉＡｓＦ６、ＬｉＰＦ６、Ｌ
ｉＢＦ４、ＬｉＣｌＯ４、ＬｉＣＦ３ＣＯ２、 ＬｉＣ
Ｆ３ＳＯ３等が使用できる。Further, in this embodiment, 1 mol / mol was used as one of the electrolytes most suitable for the negative electrode active material used in this embodiment.
A mixed solution of ethylene carbonate (EC) and diethyl carbonate (DEC) in which 1 liter of LiPF 6 was dissolved was used. In addition, various lithium salts were dissolved in various conventionally known non-aqueous solvents. The non-aqueous electrolyte solution can be selected and used from the compatibility with the negative electrode active material used. As the non-aqueous solvent that can form the non-aqueous electrolytic solution, propylene carbonate, ethylene carbonate, γ-butyrolactone, dimethoxyethane, diethoxyethane, diethyl ether, tetrahydrofuran, dioxolane, sulfolane, methylsulfolane and the like are known, and these alone or Two or more kinds are mixed and used. LiAsF 6 , LiPF 6 , L as the lithium salt
iBF 4 , LiClO 4 , LiCF 3 CO 2 , LiC
F 3 SO 3 or the like can be used.
【００２３】実施例３ 負極活物質にスピネル系リチウムチタン酸化物を使用し
た実施例を示す。 負極の作成 スピネル系リチウムチタン酸化物は一般式Ｌｉ１＋ｘＴ
ｉ２−ｘＯ４において０≦Ｘ≦１／３の範囲で存在す
る。本実施例ではＸ＝１／３で実施する。二酸化チタン
（ＴｉＯ２：アナターゼ）と水酸化リチウム（ＬｉＯ
Ｈ）を５／３モル：４／３モルの比でよく混合し、混合
物をペレット状に加圧成型し、これをヘリウム雰囲気で
８００℃で２４時間焼成してＬｉ４／３Ｔｉ５／３Ｏ４
を合成し、粉砕して平均粒径１０．５ミクロンの粉末に
調整する。調整したリチウムチタン酸化物（Ｌｉ４／３
Ｔｉ５／３Ｏ４）の９０重量部をカーボンブラックの３
重量部、グラファイト４重量部および結合剤としてポリ
フッ化ビニリデン３重量部とともに溶剤であるＮ−メチ
ル−２−ピロリドンと湿式混合してスラリー（ペースト
状）にする。このスラリーを集電体とする厚さ０．０２
ｍｍのアルミニウム箔の両面に均一に塗布し、乾燥後ロ
ーラープレス機で加圧成型して帯状の負極（１ｂ）を作
成する。Example 3 An example in which spinel lithium titanium oxide is used as the negative electrode active material is shown. Preparation of Negative Electrode Spinel-based lithium titanium oxide has the general formula Li 1 + x T
i 2-x O 4 exists in the range of 0 ≦ X ≦ 1/3. In this embodiment, X = 1/3. Titanium dioxide (TiO 2 : anatase) and lithium hydroxide (LiO
H) is mixed well at a ratio of 5/3 mol: 4/3 mol, the mixture is pressure-molded into a pellet, and this is fired in a helium atmosphere at 800 ° C. for 24 hours to make Li 4/3 Ti 5/3. O 4
Is synthesized and ground to prepare a powder having an average particle size of 10.5 microns. Adjusted lithium titanium oxide (Li 4/3
90 parts by weight of Ti 5/3 O 4 ) and carbon black 3
1 part by weight, 4 parts by weight of graphite, and 3 parts by weight of polyvinylidene fluoride as a binder are wet-mixed with N-methyl-2-pyrrolidone as a solvent to form a slurry (paste form). Thickness of this slurry as current collector 0.02
mm aluminum foil is evenly applied on both sides, dried and then pressure-molded with a roller press to form a strip-shaped negative electrode (1b).
【００２４】正極の作成 実施例２で調整したＬｉＣｏ０．５Ｎｉ０．５Ｏ２を実
施例１で調整したＬｉＭｎ２Ｏ４に２０：８０のモル比
で混合し、その混合物を正極活物質として、実施例１と
全く同様にして正極（２ｂ）を作成する。Preparation of Positive Electrode LiCo 0.5 Ni 0.5 O 2 prepared in Example 2 was mixed with LiMn 2 O 4 prepared in Example 1 in a molar ratio of 20:80, and the mixture was mixed with the positive electrode active material. As described above, the positive electrode (2b) is prepared in exactly the same manner as in Example 1.
【００２５】電池の作成 こうして作成した負極（１ｂ）と正極（２ｂ）はその間
にセパレータ（３）を挟んでロール状に巻き上げて、平
均外径１５．７ｍｍの巻回体として電池素子を作成す
る。なお、セパレータには電解液に対して安定な材質の
不織布や多孔質膜が使用できるが、充分な強度を保持
し、出来るだけ薄いものが好ましく、多孔質のポリプロ
ピレン製やポリエチレン製のセパレータが市販品として
入手可能であり、ここでは実施例１で使用したものと同
じ、厚さ０．０２５ｍｍの多孔質ポリプロピレン製セパ
レータを使用した。電池素子を電池缶（４）に納め電解
液としては１モル／リットルのＬｉＣｌＯ４を溶解した
エチレンカーボネイト（ＥＣ）とジメチルカーボネート
（ＤＭＣ）の混合溶液を注入し、後は全く実施例１と同
様にして、図１に示す電池構造で外径１６．５ｍｍ、高
さ６５ｍｍの電池（Ｓ）を作成した。Preparation of Battery The negative electrode (1b) and the positive electrode (2b) thus prepared are wound into a roll with a separator (3) sandwiched between them to prepare a battery element as a wound body having an average outer diameter of 15.7 mm. . Although a non-woven fabric or porous membrane that is a stable material for the electrolyte can be used for the separator, it is preferable that it has sufficient strength and is as thin as possible, and a porous polypropylene or polyethylene separator is commercially available. As the product, a porous polypropylene separator having a thickness of 0.025 mm, which is the same as that used in Example 1, was used here. The battery element was placed in a battery can (4), and an electrolytic solution was injected with a mixed solution of ethylene carbonate (EC) and dimethyl carbonate (DMC) in which 1 mol / liter of LiClO 4 was dissolved. Then, a battery (S) having an outer diameter of 16.5 mm and a height of 65 mm was prepared with the battery structure shown in FIG.
【００２６】比較例 正極作成において、実施例１で調整したＬｉＭｎ２Ｏ４
単独を正極活物質とした以外は総て実施例３と同じで電
池（Ｔ）を作成した。Comparative Example LiMn 2 O 4 prepared in Example 1 was used to prepare a positive electrode.
A battery (T) was prepared in the same manner as in Example 3 except that the positive electrode active material was used alone.
【００２７】実施例３および比較例で作成した電池
（Ｓ）、（Ｔ）は、電池内部の安定化を目的に常温で１
２時間のエージング期間を経過させた後、充電上限電圧
を３．２Ｖに設定し、常温で８時間の充電を行い、放電
は同じく常温で８００ｍＡの定電流放電にて終止電圧
２．０Ｖまで行ったところ、電池（Ｓ）（Ｔ）は共に１
０００ｍＡｈの初期放電容量を示した。しかしその後の
４０℃における充放電サイクル試験では、ＬｉＭｎ２Ｏ
４単独を正極活物質とした電池（Ｔ）はサイクルに伴う
容量低下が大きく、１５０サイクル程で初期容量の半分
近くへ低下した。これに対し電池（Ｓ）は１５０サイク
ル後でも８５％以上の高い容量維持率であった。また電
池（Ｓ）は過充電試験においてもその到達最高温度は１
２０℃以下に止まり、安全な結果であった。The batteries (S) and (T) prepared in Example 3 and the comparative example were kept at room temperature for the purpose of stabilizing the inside of the battery.
After the aging period of 2 hours has elapsed, the charge upper limit voltage is set to 3.2 V, charging is performed at room temperature for 8 hours, and discharging is performed at a constant current discharge of 800 mA at room temperature to a final voltage of 2.0 V. Batteries (S) and (T) are both 1
It showed an initial discharge capacity of 000 mAh. However, in the subsequent charge / discharge cycle test at 40 ° C., LiMn 2 O
The battery (T) in which 4 alone was used as the positive electrode active material showed a large decrease in capacity with cycles, and it decreased to nearly half of the initial capacity in about 150 cycles. On the other hand, the battery (S) had a high capacity retention rate of 85% or more even after 150 cycles. The maximum temperature reached for the battery (S) is 1 even in the overcharge test.
It was below 20 ° C, which was a safe result.
【００２８】[0028]
【発明の効果】以上のように、主活物質であるリチウム
マンガン複合酸化物に対して５モル％以上でＬｉＣｏ
１−ｙＮｉｙＯ２（ただし、０≦ｙ≦１）を混合して電
池を作成すれば、添加したＬｉＣｏ１−ｙＮｉｙＯ２は
活物質としても働き、リチウムイオンの一部が引き抜か
れ、正極中ではＬｉｘＣｏ１−ｙＮｉｙＯ２（ただし、
０＜ｘ＜１）の状態で存在する。ＬｉｘＣｏ１−ｙＮｉ
ｙＯ２（０＜ｘ＜１、０≦ｙ≦１）は良好なイオン伝導
体であるためイオン伝導補助剤として有効に働き、充放
電サイクルに伴う容量劣化の少ないリチウムイオン二次
電池となる。しかしＬｉｘＣｏ１−ｙＮｉｙＯ２中の残
存リチウムは過充電において負極への金属リチウムの析
出を来たし、過充電での安全性を損なう原因ともなるの
で、本発明ではＬｉｘＣｏ１−ｙＮｉｙＯ２は正極主活
物質に対して５０モル％以下、好ましくは３０モル％以
下、さらに好ましくは２０モル％以下に規制する。特に
負極に炭素材料を活物質として使用する場合は、正極活
物質層に含有するＭｎのモル数（ａ）、ＣｏおよびＮｉ
のモル数の和（ｂ）および正極と対向する負極活物質層
に含有する活物質炭素のモル数（ｃ）が ０．１２≦（ａ＋２ｂ）／２ｃ≦０．１７ の関係を満たすことによって、過充電での安全性が確保
される。本発明によれば安価なリチウムマンガン複合酸
化物がリチウムイオン二次電池の正極主活物質として使
用できるようになり、既存の二次電池にも充分に代わり
うる、高容量、長寿命で且つ安全なリチウムイオン二次
電池が安価に提供できるようになり、その工業的価値は
大である。As described above, the LiCo content of 5 mol% or more relative to the lithium manganese composite oxide, which is the main active material, is satisfied.
If 1-y Ni y O 2 (where 0 ≦ y ≦ 1) is mixed to form a battery, the added LiCo 1-y Ni y O 2 also functions as an active material, and a part of the lithium ion is extracted. Li x Co 1-y Ni y O 2 (provided that
It exists in the state of 0 <x <1). Li x Co 1-y Ni
Since y O 2 (0 <x <1, 0 ≦ y ≦ 1) is a good ion conductor, it works effectively as an ion conduction auxiliary agent, and becomes a lithium ion secondary battery with less capacity deterioration due to charge / discharge cycles. . However, the residual lithium in Li x Co 1-y Ni y O 2 causes the deposition of metallic lithium on the negative electrode during overcharging, which may cause the safety of overcharging to be impaired. Therefore, in the present invention, Li x Co 1- y Ni y O 2 is regulated to 50 mol% or less, preferably 30 mol% or less, and more preferably 20 mol% or less with respect to the positive electrode main active material. Particularly when a carbon material is used as an active material for the negative electrode, the number of moles of Mn (a) contained in the positive electrode active material layer, Co and Ni
(B) and the number of moles of active material carbon (c) contained in the negative electrode active material layer facing the positive electrode satisfy the relationship of 0.12 ≦ (a + 2b) /2c≦0.17. The safety in overcharging is secured. According to the present invention, an inexpensive lithium manganese composite oxide can be used as a positive electrode main active material of a lithium-ion secondary battery, which can sufficiently replace an existing secondary battery, has a high capacity, a long life, and is safe. Lithium ion secondary battery can be provided at low cost, and its industrial value is great.
【図１】実施例における電池の構造を示した模式的断面
図FIG. 1 is a schematic cross-sectional view showing the structure of a battery in an example.
【図２】試作二次電池のサイクル特性[Fig. 2] Cycle characteristics of prototype secondary battery
【図３】正極中ＬｉＣｏＯ２混合比率と電池容量の関係
図FIG. 3 is a diagram showing the relationship between the LiCoO 2 mixing ratio in the positive electrode and the battery capacity.
【図４】試作電池の過充電での温度上昇[Figure 4] Temperature rise due to overcharge of prototype battery
１は負極、２は正極、３はセパレータ、４は電池缶、５
は絶縁板、６は負極リード、７はガスケット、８は防爆
弁、９は正極リード、１０は閉塞蓋体である。1 is a negative electrode, 2 is a positive electrode, 3 is a separator, 4 is a battery can, 5
Is an insulating plate, 6 is a negative electrode lead, 7 is a gasket, 8 is an explosion-proof valve, 9 is a positive electrode lead, and 10 is a closing lid.
Claims (4)
を有する電池であって、前記正極にスピネル型リチウム
マンガン複合酸化物を主活物質として用いる非水電解液
二次電池において、前記正極中には固体のリチウムイオ
ン伝導体を主活物質に混じて含有せしめたことを特長と
する非水電解液二次電池。1. A battery having a positive electrode, a negative electrode, a separator and a non-aqueous electrolytic solution, wherein the positive electrode comprises a spinel-type lithium manganese composite oxide as a main active material in the positive electrode. The non-aqueous electrolyte secondary battery is characterized by containing a solid lithium ion conductor mixed with the main active material.
可能な炭素材料を主活物質として用いた請求項１記載の
非水電解液二次電池。2. The non-aqueous electrolyte secondary battery according to claim 1, wherein a carbon material capable of doping and dedoping lithium is used as a main active material for the negative electrode.
４（ただし、０≦Ｘ≦１／３）で示されるリチウムチタ
ン酸化物を主活物質として用いた請求項１記載の非水電
解液二次電池。3. The negative electrode has the general formula Li 1 + x Ti 2-x O.
4. The non-aqueous electrolyte secondary battery according to claim 1, wherein a lithium titanium oxide represented by 4 (where 0 ≦ X ≦ 1/3) is used as a main active material.
ｘＣｏ１−ｙＮｉｙＯ２（ただし０＜ｘ＜１、０≦ｙ≦
１）が正極主活物質に対して５モル％以上２０モル％以
下で混合されていて、正極活物質層に含有するＭｎのモ
ル数（ａ）とＣｏおよびＮｉのモル数の和（ｂ）および
正極と対向する負極活物質層に含有する活物質炭素のモ
ル数（ｃ）が、 ０．１２≦（ａ＋２ｂ）／２ｃ≦０．１７ の関係にあることを特徴とする請求項２記載の非水電解
液二次電池。4. Li as a lithium ion conductor in the positive electrode
x Co 1-y Ni y O 2 (where 0 <x <1, 0 ≦ y ≦
1) is mixed in an amount of 5 mol% or more and 20 mol% or less with respect to the positive electrode main active material, and the sum of the number of moles of Mn (a) and the number of moles of Co and Ni contained in the positive electrode active material layer (b). And the number of moles (c) of the active material carbon contained in the negative electrode active material layer facing the positive electrode has a relationship of 0.12 ≦ (a + 2b) /2c≦0.17. Non-aqueous electrolyte secondary battery.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34091694A JP3436600B2 (en) | 1993-12-27 | 1994-12-26 | Rechargeable battery |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP35505493 | 1993-12-27 | ||
| JP5-355054 | 1993-12-27 | ||
| JP34091694A JP3436600B2 (en) | 1993-12-27 | 1994-12-26 | Rechargeable battery |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07235291A true JPH07235291A (en) | 1995-09-05 |
| JP3436600B2 JP3436600B2 (en) | 2003-08-11 |
Family
ID=26576830
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP34091694A Expired - Lifetime JP3436600B2 (en) | 1993-12-27 | 1994-12-26 | Rechargeable battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3436600B2 (en) |
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| JP2010153258A (en) * | 2008-12-25 | 2010-07-08 | Toshiba Corp | Nonaqueous electrolyte battery |
| JP2013110134A (en) * | 2008-12-25 | 2013-06-06 | Toshiba Corp | Nonaqueous electrolyte battery |
| JP2012522339A (en) * | 2009-03-30 | 2012-09-20 | ユミコア ソシエテ アノニム | High voltage negative active material for rechargeable lithium batteries |
| JP2012195055A (en) * | 2011-03-14 | 2012-10-11 | Mitsubishi Motors Corp | State management method of lithium ion battery |
| JP2014167886A (en) * | 2013-02-28 | 2014-09-11 | Toshiba Corp | Battery |
| US11417873B2 (en) | 2015-12-21 | 2022-08-16 | Johnson Ip Holding, Llc | Solid-state batteries, separators, electrodes, and methods of fabrication |
| USRE49205E1 (en) | 2016-01-22 | 2022-09-06 | Johnson Ip Holding, Llc | Johnson lithium oxygen electrochemical engine |
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| JP3436600B2 (en) | 2003-08-11 |
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