JP2001313024A - Lithium secondary battery - Google Patents
Lithium secondary batteryInfo
- Publication number
- JP2001313024A JP2001313024A JP2000126913A JP2000126913A JP2001313024A JP 2001313024 A JP2001313024 A JP 2001313024A JP 2000126913 A JP2000126913 A JP 2000126913A JP 2000126913 A JP2000126913 A JP 2000126913A JP 2001313024 A JP2001313024 A JP 2001313024A
- Authority
- JP
- Japan
- Prior art keywords
- positive electrode
- active material
- electrode active
- lithium
- secondary battery
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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】本発明はリチウム二次電池に
係り、特に、正極集電体にリチウムイオンを放出・吸蔵
することができる正極活物質を塗着した正極と、リチウ
ムイオンを吸蔵・放出することができる炭素材を負極活
物質とする負極と、を用いたリチウム二次電池に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium secondary battery and, more particularly, to a positive electrode having a positive electrode current collector coated with a positive electrode active material capable of releasing and storing lithium ions, and a method of storing and releasing lithium ions. And a negative electrode using a carbon material as a negative electrode active material.
【０００２】[0002]
【従来の技術】従来、負極活物質にリチウムを用いたリ
チウム電池は、高いエネルギーを有することから、数々
の方面でその二次電池化が試みられてきた。しかし、負
極活物質に純金属リチウムを用いる場合には、充放電の
繰り返しに伴う負極リチウムの針状析出（いわゆる、デ
ンドライトの生成）が起こるので、針状析出リチウムが
正極に到達することにより電池内部での短絡が発生し電
池性能が著しく低下するといった性能面での問題と、内
部短絡によって過大な電流が流れることによる発熱で封
口部に不良が生じたり、電解質の揮発より電池の内圧が
著しく上昇するといった安全面での問題と、を考慮する
必要がある。特に安全面では、化学的に活性で反応性の
高い金属リチウムが空気中の水分と反応すると、下記化
学式（１）に示すように、水素ガスと反応熱とが電池の
安全性を阻害する。2. Description of the Related Art Conventionally, a lithium battery using lithium as a negative electrode active material has high energy, and therefore, attempts have been made to convert it to a secondary battery in various fields. However, when pure metal lithium is used as the negative electrode active material, needle-like deposition of the negative electrode lithium (so-called dendrite generation) occurs due to repetition of charge / discharge. There is a performance problem such as an internal short circuit that significantly reduces battery performance, and an internal short circuit causes excessive current to generate heat, resulting in a failure in the sealing part. It is necessary to consider safety issues such as rising. Particularly in terms of safety, when chemically active and highly reactive metallic lithium reacts with moisture in the air, the hydrogen gas and the heat of reaction impair the safety of the battery as shown in the following chemical formula (1).
【０００３】[0003]
【化１】 Embedded image
【０００４】デンドライト生成による問題を解決するた
めの対策として、負極に、Ｌｉ−Ａｌ合金などのリチウ
ム合金や、充放電に伴いリチウムイオンの吸蔵、放出が
可能な炭素材が用いられている。とりわけ、非水電解液
と、このような炭素材を負極に用いたリチウム二次電池
は、高い安全性を有していることと、ニッケル・カドミ
ウム電池などの従来の二次電池に比べて高容量、高エネ
ルギー密度であることから、その市場は破竹の勢いで増
大するものと予測されている。[0004] As measures to solve the problem caused by dendrite formation, a lithium alloy such as a Li-Al alloy or a carbon material capable of inserting and extracting lithium ions with charge and discharge is used for the negative electrode. In particular, a non-aqueous electrolyte and a lithium secondary battery using such a carbon material as a negative electrode have high safety and are higher than conventional secondary batteries such as nickel-cadmium batteries. Due to its capacity and high energy density, its market is expected to grow at a rapid pace.
【０００５】リチウム二次電池は、通常、正極・負極共
に活物質が金属箔に塗着され、セパレータを挟んで両極
が捲回された後、円筒形の缶に収納され、電解液注液
後、キャップ封口され、初充電することによって電池と
しての機能が付与される。負極活物質に用いられる炭素
材は、いわばリチウムが放出しきった状態、すなわち放
電状態であるので、通常、正極も放電状態の活物質、例
えばＬｉＣｏＯ２やＬｉＮｉＯ２などが用いられる。こ
のような構成のリチウム二次電池は、高エネルギーであ
るメリットを活かして、主にＶＴＲカメラやノートパソ
コン、携帯電話等のポータブル機器の主電源として使用
されている。このため現在、さらに高容量、高エネルギ
ー密度のリチウム二次電池が要望されている。[0005] In a lithium secondary battery, an active material is usually applied to a metal foil for both a positive electrode and a negative electrode, and both electrodes are wound with a separator interposed therebetween, and then housed in a cylindrical can. The cap is sealed, and a function as a battery is provided by the first charge. Since the carbon material used for the negative electrode active material is in a state where lithium has been completely released, that is, in a discharged state, the active material in which the positive electrode is also in a discharged state, such as LiCoO 2 or LiNiO 2 , is usually used. The lithium secondary battery having such a configuration is mainly used as a main power supply for portable devices such as a VTR camera, a notebook computer, and a mobile phone, taking advantage of its high energy. Therefore, there is a demand for a lithium secondary battery having a higher capacity and a higher energy density.
【０００６】このような高容量化を実現するために、例
えば特開平第６−３４２６７３号公報には、正極活物質
より電位が低く、かつ、容量密度が正極活物質より大き
い含リチウム化合物を正極に混ぜ込んだリチウム二次電
池に関する技術が開示されている。In order to realize such a high capacity, for example, Japanese Patent Application Laid-Open No. Hei 6-342573 discloses a lithium-containing compound having a potential lower than that of a positive electrode active material and having a larger capacity density than that of the positive electrode active material. There is disclosed a technology relating to a lithium secondary battery mixed with a lithium secondary battery.
【０００７】なお、本発明に関連して、正極に放電電位
の低い副活物質を添加し、負極に放電可能なリチウムを
予め保持させた構成とすることで、過放電時の正負極の
電位を制限して過放電による正負極の劣化を抑制する、
特開平第５−１５１９９５号公報に開示された技術があ
る。In connection with the present invention, by adding a sub-active material having a low discharge potential to the positive electrode and holding the dischargeable lithium in the negative electrode in advance, the potential of the positive and negative electrodes during overdischarge is increased. Limit the deterioration of the positive and negative electrodes due to overdischarge,
There is a technique disclosed in JP-A-5-151995.
【０００８】[0008]
【発明が解決しようとする課題】しかしながら、上述し
た構成のリチウム二次電池では、初充電時に炭素材に吸
蔵されたリチウムの約８０％しか次の放電で放出でき
ず、残りの２０％分は炭素材中に残留するので、初充電
に使われた電気量のおよそ８０％しか以降の放電、充電
に用いられない、という問題点がある。すなわち、正極
活物質に予め存在していたリチウムの約８０％しか充
電、放電に関与させることができず、正極活物質が持っ
ている能力の約８０％しか発揮することができない。However, in the lithium secondary battery having the above-described structure, only about 80% of the lithium occluded in the carbon material at the time of the first charge can be released in the next discharge, and the remaining 20% is used for the remaining 20%. Since it remains in the carbon material, there is a problem that only about 80% of the amount of electricity used for the first charge is used for the subsequent discharge and charge. That is, only about 80% of the lithium existing in the positive electrode active material can be involved in charging and discharging, and only about 80% of the capability of the positive electrode active material can be exhibited.
【０００９】また、上記特開平第６−３４２６７３号公
報の技術では、正極に混ぜ込んだ材料は初充電時以外の
充電、放電にはほとんど関与しないので、却って正極内
のリチウムイオンや電子の動きを妨げることとなり電池
の内部抵抗を増させ、十分な容量アップを図ることが難
しい、という問題点がある。In the technique disclosed in Japanese Patent Application Laid-Open No. 6-342673, since the material mixed in the positive electrode hardly participates in charging and discharging except for the initial charging, the movement of lithium ions and electrons in the positive electrode is rather restricted. And the internal resistance of the battery is increased, and it is difficult to sufficiently increase the capacity.
【００１０】本発明は以上の問題点に鑑み、負極炭素材
に残留するリチウム量を有効に活用した高容量のリチウ
ム二次電池を提供することを課題とする。In view of the above problems, an object of the present invention is to provide a high-capacity lithium secondary battery that effectively utilizes the amount of lithium remaining in a negative electrode carbon material.
【００１１】[0011]
【課題を解決するための手段】上記課題を解決するため
に本発明は、正極集電体にリチウムイオンを放出・吸蔵
することができる正極活物質を塗着した正極と、リチウ
ムイオンを吸蔵・放出することができる炭素材を負極活
物質とする負極と、を用いたリチウム二次電池におい
て、前記正極集電体と前記正極活物質との間に、該正極
活物質よりも放電電位が低い第二正極活物質層を備えた
ことを特徴とする。SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a positive electrode comprising a positive electrode current collector coated with a positive electrode active material capable of releasing and occluding lithium ions; In a lithium secondary battery using a negative electrode using a carbon material that can be released as a negative electrode active material, a discharge potential is lower than the positive electrode active material between the positive electrode current collector and the positive electrode active material. A second positive electrode active material layer is provided.
【００１２】リチウム二次電池の正極活物質として一般
に用いられるＬｉＣｏＯ２やＬｉＮｉＯ２などの充電・
放電電位幅は、金属リチウムを基準として、おおよそ
４．３〜３．０Ｖである。これに対し本発明では、正極
集電体と正極活物質との間に、充電・放電電位幅が、金
属リチウムを基準として、おおよそ３．３〜１．５Ｖ程
度の放電電位が低い第二正極活物質層を備えている。こ
のため、初充電時には、はじめに第二正極活物質層が充
電され、次いでＬｉＣｏＯ２やＬｉＮｉＯ２などの正極
活物質が充電される。つまり、はじめに第二正極活物質
層からリチウムが電解液中に放出され、次いでＬｉＣｏ
Ｏ２やＬｉＮｉＯ２などの正極活物質からリチウムが電
解液中に放出される、という反応が起こる。一方、負極
炭素材には電解液中のリチウムが吸蔵される、という反
応が起こる。正極活物質に予め存在しているリチウム量
だけでなく、第二正極活物質層に存在しているリチウム
量も負極炭素材に吸蔵させてやろうというものである。Charging and charging of LiCoO 2 and LiNiO 2 generally used as a positive electrode active material of a lithium secondary battery
The discharge potential width is approximately 4.3 to 3.0 V on the basis of metallic lithium. On the other hand, in the present invention, the second positive electrode having a charge / discharge potential width of about 3.3 to 1.5 V with a low discharge potential on the basis of metallic lithium is provided between the positive electrode current collector and the positive electrode active material. An active material layer is provided. For this reason, at the time of initial charging, the second positive electrode active material layer is charged first, and then the positive electrode active material such as LiCoO 2 or LiNiO 2 is charged. That is, first, lithium is released into the electrolytic solution from the second positive electrode active material layer, and then LiCo
A reaction occurs in which lithium is released from the positive electrode active material such as O 2 or LiNiO 2 into the electrolytic solution. On the other hand, a reaction occurs in which the negative electrode carbon material absorbs lithium in the electrolytic solution. Not only the amount of lithium existing in the positive electrode active material but also the amount of lithium existing in the second positive electrode active material layer is to be absorbed in the negative electrode carbon material.
【００１３】電池放電終了時の正極電位は金属リチウム
を基準として約３．０Ｖであるので、第二正極活物質層
に存在するリチウムは放電にほとんど関与しない。つま
り、初充電で放出されたリチウムは、放電では吸蔵され
ない。従って、第二正極活物質層に存在するリチウムを
負極炭素材に残留するリチウムにあてがうことができる
わけである。そうすると、正極活物質に予め存在してい
るリチウム量は、負極炭素材中に残留することなく充
電、放電に関与させることができ、電池の容量アップに
つながる。Since the positive electrode potential at the end of battery discharge is about 3.0 V based on metallic lithium, lithium present in the second positive electrode active material layer hardly participates in the discharge. That is, lithium released at the time of initial charge is not occluded by discharge. Therefore, lithium existing in the second positive electrode active material layer can be applied to lithium remaining in the negative electrode carbon material. Then, the amount of lithium already existing in the positive electrode active material can be involved in charging and discharging without remaining in the negative electrode carbon material, leading to an increase in battery capacity.
【００１４】このように本発明では、電子伝導性を有
し、リチウムの放出が可能で、リチウムの吸蔵（放電）
電位の低い第二正極活物質層を正極集電体と正極活物質
との間に備えることにより、残留するリチウム量を有効
に活用して高容量のリチウム二次電池を得ることができ
る。とりわけ、一般に、充電・放電電位幅が、金属リチ
ウムを基準としておおよそ３．３〜１．５Ｖ程度の活物
質はリチウムを放出すると電気抵抗が下がるので、第二
正極活物質層に適している。このような第二活物質層
は、第二活物質のみからなる膜で好適にはＬｉｘＭｎＯ
２の膜としてもよく、又は、第二正極活物質粉末と炭素
粉末と結着材との混合物を含有して形成するようにして
もよい。As described above, the present invention has electron conductivity, can release lithium, and occludes (discharges) lithium.
By providing the second positive electrode active material layer having a low potential between the positive electrode current collector and the positive electrode active material, a high-capacity lithium secondary battery can be obtained by effectively utilizing the remaining amount of lithium. In particular, in general, an active material having a charge / discharge potential width of about 3.3 to 1.5 V on the basis of metallic lithium is suitable for the second positive electrode active material layer because the electric resistance decreases when lithium is released. Such a second active material layer is a film composed of only the second active material, preferably Li x MnO.
2 film, or may be formed by containing a mixture of the second positive electrode active material powder, the carbon powder, and the binder.
【００１５】[0015]
【発明の実施の形態】（第１実施形態）以下、図面を参
照して本発明が適用可能なリチウム二次電池の第１の実
施の形態について説明する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter, a first embodiment of a lithium secondary battery to which the present invention can be applied will be described with reference to the drawings.
【００１６】図１に示すように、本実施形態の円筒形リ
チウム二次電池２０は、正極板１１及び負極板１２を、
厚さ２０μｍの微多孔性のポリエチレンフィルムからな
るセパレータ６を介して渦巻き状に捲回した捲回群１３
を備えている。As shown in FIG. 1, a cylindrical lithium secondary battery 20 of the present embodiment comprises a positive electrode plate 11 and a negative electrode plate 12,
A winding group 13 wound spirally through a separator 6 made of a microporous polyethylene film having a thickness of 20 μm.
It has.
【００１７】正極板１１は、厚さ２０μｍ、平面サイズ
５０ｍｍ×４５０ｍｍのチタン箔からなる正極集電体１
の両面に、厚さ約２５μｍの、第二正極活物質層として
のＬｉｘＭｎＯ２膜２が形成されている。このＬｉｘＭ
ｎＯ２膜２は、次のようにして正極集電体１上に形成さ
れる。The positive electrode plate 11 is a positive electrode current collector 1 made of titanium foil having a thickness of 20 μm and a plane size of 50 mm × 450 mm.
A Li x MnO 2 film 2 having a thickness of about 25 μm as a second positive electrode active material layer is formed on both surfaces of the substrate. This Li x M
The nO 2 film 2 is formed on the positive electrode current collector 1 as follows.
【００１８】耐熱ガラス製の電解セル内に、電解液であ
るＭｎＳＯ４（１モル）−Ｈ２ＳＯ ４（０．５モル）の
混合水溶液を満たし、陰極をグラファイト板とし、陽極
に正極集電体となるチタン箔を配置して、電流密度０．
５〜１Ａ／ｄｍ３、温度９０°Ｃで陽極のチタン箔表面
上にＭｎＯ２を電解析出させる。この析出量は、下記化
学式（２）に示すように、ファラデーの法則に従って通
電時間で調整することができる。An electrolytic solution is placed in an electrolytic cell made of heat-resistant glass.
MnSO4(1 mol) -H2SO 4(0.5 mol)
Fill the mixed aqueous solution, make the cathode a graphite plate,
A titanium foil serving as a positive electrode current collector is disposed at a current density of 0.
5-1 A / dm3Titanium foil surface of anode at temperature of 90 ° C
MnO on top2Is electrolytically deposited. The amount of precipitation is
As shown in Formula (2), the communication is performed according to Faraday's law.
It can be adjusted by the charging time.
【００１９】[0019]
【化２】 Embedded image
【００２０】ＬｉｘＭｎＯ２膜は、水分のない雰囲気下
で表面にＭｎＯ２が電解析出されたチタン箔を正極とす
る簡易リチウム電池を作製し放電させることにより形成
することができる。このような簡易リチウム電池は、例
えば、図２に示すように、ＭｎＯ２が両面に電解析出さ
れた正極集電体１ａを試験極とし、試験極の両側にグラ
スウール３ａを介して、金属リチウム５ａと対極集電体
４ａとからなる対極を配置することにより作製可能であ
る。対極集電体４ａには、例えば、厚さ２０μｍのニッ
ケル箔を使用することができ、簡易リチウム電池の容器
にはガラス容器７ａを用いることができる。簡易リチウ
ム電池の電解液６ａには、プロピレンカーボネートと
１，２−ジメトキシエタンとの混合溶液（混合比：体積
で１：１）に、１ｍｏｌ／ｄｍ３となるように６フッ化
リン酸リチウム（ＬｉＰＦ６）を溶解したものを用い
た。The Li x MnO 2 film can be formed by producing and discharging a simple lithium battery using a titanium foil having MnO 2 electrolytically deposited on its surface as a positive electrode in an atmosphere without moisture. As shown in FIG. 2, for example, as shown in FIG. 2, such a simple lithium battery uses a positive electrode current collector 1a on which MnO 2 is electrolytically deposited on both sides as a test electrode, and a metal lithium on both sides of the test electrode via glass wool 3a. It can be manufactured by arranging a counter electrode composed of 5a and the counter electrode current collector 4a. For example, a nickel foil having a thickness of 20 μm can be used for the counter electrode current collector 4a, and a glass container 7a can be used for the container of the simple lithium battery. In the electrolyte 6a of the simple lithium battery, a mixed solution of propylene carbonate and 1,2-dimethoxyethane (mixing ratio: 1: 1 by volume) was prepared so as to have a concentration of 1 mol / dm 3 of lithium hexafluorophosphate ( LiPF 6 ) was used.
【００２１】下表１に放電条件を示す。表１の条件で放
電すると、ＬｉｘＭｎＯ２のｘ値は約１．１となる。Table 1 below shows the discharge conditions. When discharging under the conditions shown in Table 1, the x value of Li x MnO 2 becomes about 1.1.
【００２２】[0022]
【表１】 [Table 1]
【００２３】そして、ＬｉｘＭｎＯ２膜２が両面に形成
された正極集電体１を、脱水した１，２−ジメトキシエ
タンで、付着した電解液を洗い流した後、乾燥させ、Ｌ
ｉｘＭｎＯ２膜２の形成が完了する。Then, the positive electrode current collector 1 having the Li x MnO 2 film 2 formed on both sides thereof is washed with dehydrated 1,2-dimethoxyethane to remove the attached electrolyte, and then dried.
Formation of i x MnO 2 film 2 is completed.
【００２４】ＬｉｘＭｎＯ２膜２が両面に形成された正
極集電体１には、更に、正極活物質３が塗着され、正極
板１１とされる。正極活物質層３は、リチウムイオンを
電極反応種とする正極活物質としてのＬｉＣｏＯ２（平
均粒径約２μｍ）と、導電助剤であるグラファイト（平
均粒径約０．５μｍ）と、バインダー（結着剤）である
ポリフッ化ビニリデン（ＰＶＤＦ）と、電解液と、で構
成されている。正極板１１の作製手順について詳述すれ
ば、ＬｉＣｏＯ２とグラファイトとＰＶＤＦとを重量比
で８０：１０：１０に十分混合し、そこへ分散溶媒とな
るＮ−メチル−２−ピロリドン（ＮＭＰ）を適量加え、
十分に混練、分散させ、インク状にし、この混練物をロ
ールからロールへの転写（ロールｔｏロール転写）によ
り正極集電体１の両面に形成されたＬｉｘＭｎＯ２膜２
に塗着、乾燥させることにより得ることができる（ただ
し、この段階では、電解液は含まれていない。）。正極
活物質層３の厚さは、ＬｉｘＭｎＯ２膜２の表面から１
００μｍである。A positive electrode active material 3 is further applied to a positive electrode current collector 1 having a Li x MnO 2 film 2 formed on both sides to form a positive electrode plate 11. The positive electrode active material layer 3 includes LiCoO 2 (average particle diameter of about 2 μm) as a positive electrode active material using lithium ions as an electrode reactive species, graphite (average particle diameter of about 0.5 μm) as a conductive additive, and a binder ( It is composed of polyvinylidene fluoride (PVDF), which is a binder, and an electrolytic solution. The production procedure of the positive electrode plate 11 will be described in detail. LiCoO 2 , graphite and PVDF are sufficiently mixed in a weight ratio of 80:10:10, and N-methyl-2-pyrrolidone (NMP) as a dispersion solvent is added thereto. Add an appropriate amount,
A Li x MnO 2 film 2 formed on both surfaces of the positive electrode current collector 1 by sufficiently kneading and dispersing to form an ink, and transferring the kneaded material from roll to roll (roll-to-roll transfer)
And an electrolyte solution (at this stage, no electrolytic solution is contained). The thickness of the positive electrode active material layer 3 is 1 mm from the surface of the Li x MnO 2 film 2.
00 μm.
【００２５】一方、負極板１２は、厚さ１０μｍ、平面
サイズ５０ｍｍ×４５０ｍｍの銅箔からなる負極集電体
４の両面に、リチウムイオンを電極反応種とする負極活
物質である無定形炭素（平均粒径約１０μｍ）と、バイ
ンダーであるポリフッ化ビニリデンと、電解液と、で構
成された負極活物質層５が塗着されている。この負極板
１２の作製手順について詳述すれば、無定形炭素とＰＶ
ＤＦを重量比で９０：１０となるように混合し、そこへ
分散溶媒となるＮ−メチル−２−ピロリドンを適量加
え、十分に混練、分散させ、インク状にし、この混練物
をロールｔｏロール転写により負極集電体４の両面に塗
着、乾燥させることにより得ることができる（ただし、
この段階では電解液は入っていない。）。負極活物質層
５の厚さは、負極集電体４の表面から１００μｍであ
る。On the other hand, the negative electrode plate 12 is made of an amorphous carbon (a negative electrode active material using lithium ions as an electrode reactive species) on both surfaces of a negative electrode current collector 4 made of copper foil having a thickness of 10 μm and a plane size of 50 mm × 450 mm. A negative electrode active material layer 5 composed of an average particle size of about 10 μm), polyvinylidene fluoride as a binder, and an electrolyte is applied. The production procedure of the negative electrode plate 12 will be described in detail.
DF was mixed at a weight ratio of 90:10, an appropriate amount of N-methyl-2-pyrrolidone as a dispersion solvent was added thereto, and the mixture was kneaded and dispersed sufficiently to form an ink. It can be obtained by coating and drying both sides of the negative electrode current collector 4 by transfer (however,
At this stage, no electrolyte is contained. ). The thickness of the negative electrode active material layer 5 is 100 μm from the surface of the negative electrode current collector 4.
【００２６】図１に示すように、捲回群１３は、円筒形
リチウム二次電池２０の缶体となる円筒状の有底負極缶
７に挿入されている。負極缶７には、一端を負極集電体
４に予め溶接しておいた負極タブ端子の他端が捲回群１
３の挿入後に溶接される。一方、正極タブ端子９の一端
は予め正極集電体１に溶接されており、他端が捲回群１
３の挿入後に正極キャップ８に溶接される。また、円筒
形リチウム二次電池２０は、正極キャップ８を負極缶７
上部開口に配置し、ガスケット１０を介して負極缶７上
部がカシメられ、密閉されている。As shown in FIG. 1, the wound group 13 is inserted into a cylindrical bottomed negative electrode can 7 which is a can of a cylindrical lithium secondary battery 20. In the negative electrode can 7, the other end of the negative electrode tab terminal, one end of which is welded in advance to the negative electrode current collector 4, has a winding group 1
3 after welding. On the other hand, one end of the positive electrode tab terminal 9 is welded to the positive electrode current collector 1 in advance, and the other end is
3 is welded to the positive electrode cap 8 after insertion. Further, the cylindrical lithium secondary battery 20 has the positive electrode cap 8 attached to the negative electrode can 7.
It is arranged in the upper opening, and the upper part of the negative electrode can 7 is caulked and sealed through the gasket 10.
【００２７】更に、円筒形リチウム二次電池２０の負極
缶７内には、図示しない電解液が注液されている。本実
施形態では、電解液に、電解液に対して１ｍｏｌ／ｌと
なるようにＬｉＰＦ６が溶解された、炭酸エチレンと炭
酸ジエチルとの混合溶媒であり、その混合比を体積にし
て１：１としものを用い、負極缶７内に電解液を４ｍｌ
注液した。Further, an electrolytic solution (not shown) is injected into the negative electrode can 7 of the cylindrical lithium secondary battery 20. In the present embodiment, a mixed solvent of ethylene carbonate and diethyl carbonate in which LiPF 6 is dissolved in the electrolytic solution so as to be 1 mol / l with respect to the electrolytic solution, and the mixing ratio is 1: 1 by volume. 4 ml of electrolyte in negative electrode can 7
Injected.
【００２８】（第２実施形態）次に、本発明が適用可能
なリチウム二次電池の第２の実施の形態について説明す
る。本実施形態のリチウム二次電池は、第二正極活物質
層として、ＬｉｘＭｎＯ２粉末と炭素粉末と結着材との
混合物を用いたものである。なお、本実施形態におい
て、上述した第１実施形態と同一の部材には同一の符号
を付しその説明を省略し、異なる箇所のみ説明する。(Second Embodiment) Next, a second embodiment of a lithium secondary battery to which the present invention can be applied will be described. The lithium secondary battery of the present embodiment uses a mixture of Li x MnO 2 powder, carbon powder, and a binder as the second positive electrode active material layer. In this embodiment, the same members as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Only different parts will be described.
【００２９】本実施形態の円筒形リチウム二次電池の第
二正極活物質層は、第１実施形態に示したＬｉｘＭｎＯ
２膜２のみからなる第二正極活物質層に代えて、Ｌｉｘ
ＭｎＯ２粉末（平均粒径約２μｍ）と、導電助剤である
グラファイト（平均粒径約０．５μｍ）と、バインダー
であるポリフッ化ビニリデン（ＰＶＤＦ）と、で構成さ
れた第二正極活物質層が用いられている。本実施形態の
第二正極活物質層について詳述すれば、ＬｉｘＭｎＯ２
と、グラファイトと、ＰＶＤＦと、を重量比で８０：１
０：１０に十分混合し、そこへ分散溶媒となるＮ−メチ
ル−２−ピロリドンを適量加え、十分に混練、分散さ
せ、インク状として、この混練物をロールｔｏロール転
写により正極集電体１の両面に塗着、乾燥させたもので
ある。そして、第１実施形態と同様に、簡易リチウム電
池を作製、放電、洗浄することによって、第二正極活物
質層を得た。The second positive electrode active material layer of the cylindrical lithium secondary battery of the present embodiment is composed of the Li x MnO shown in the first embodiment.
Li x instead of the second positive electrode active material layer consisting of only two films 2
Second positive electrode active material layer composed of MnO 2 powder (average particle size of about 2 μm), graphite (average particle size of about 0.5 μm) as a conductive additive, and polyvinylidene fluoride (PVDF) as a binder Is used. The second positive electrode active material layer of the present embodiment will be described in detail as follows: Li x MnO 2
, Graphite, and PVDF in a weight ratio of 80: 1.
The mixture was sufficiently mixed at 0:10, N-methyl-2-pyrrolidone as a dispersion solvent was added in an appropriate amount, and the mixture was sufficiently kneaded and dispersed to form an ink. It was applied on both sides of the film and dried. Then, similarly to the first embodiment, a simple lithium battery was prepared, discharged, and washed to obtain a second positive electrode active material layer.
【００３０】[0030]
【実施例】上記第１及び第２実施形態に従って作製した
円筒形リチウム二次電池（以下、実施例１、２の電池と
いう。）と、正極集電体１に第二正極活物質層を形成せ
ず、その他は上記実施例１、２と全く同様に作製した比
較例の電池と、を作製した。EXAMPLE A cylindrical lithium secondary battery (hereinafter referred to as the batteries of Examples 1 and 2) manufactured according to the first and second embodiments, and a second positive electrode active material layer formed on the positive electrode current collector 1 Other than that, a battery of a comparative example manufactured in exactly the same manner as in Examples 1 and 2 above was manufactured.
【００３１】（試験）そして、これらの電池を以下に示
す条件で初充電し、放電する充放電試験を行った。 初充電：４．２Ｖ定電圧、上限電流１００ｍＡ、２０
ｈ、２５°Ｃ、休止１ｈ 放電：１００ｍＡ定電流、終止電圧２．８Ｖ、２５°Ｃ （試験結果・評価）図３及び図４に、充放電試験の試験
結果を示す。なお、図３は、初充電時とその後の放電時
の電圧と電流の様子を横軸時間に対して示したものであ
り、図４は、同条件で充電、放電サイクルを繰り返した
ときの、サイクル進行に伴う放電容量推移を示したもの
である。(Test) A charge / discharge test was conducted in which these batteries were initially charged and discharged under the following conditions. Initial charge: 4.2V constant voltage, upper limit current 100mA, 20
h, 25 ° C., rest 1 h Discharge: 100 mA constant current, final voltage 2.8 V, 25 ° C. (Test Results / Evaluation) FIGS. 3 and 4 show test results of the charge / discharge test. FIG. 3 shows the state of the voltage and current at the time of initial charge and at the time of subsequent discharge with respect to the horizontal axis time, and FIG. 4 shows the case where the charge and discharge cycles were repeated under the same conditions. It shows a change in discharge capacity with progress of a cycle.
【００３２】図３に示すように、実施例１、２の電池の
方が比較例の電池より初充電容量、放電容量共に大きい
ことが明らかである。また、図４に示すように、比較例
の電池に比べ、実施例１、２の電池の方が高い容量を維
持し続けていることが明白である。As shown in FIG. 3, it is apparent that the batteries of Examples 1 and 2 both have larger initial charge capacity and discharge capacity than the battery of Comparative Example. Further, as shown in FIG. 4, it is apparent that the batteries of Examples 1 and 2 continue to maintain a higher capacity than the batteries of the comparative example.
【００３３】下表２は、実施例１、２及び比較例の電池
における活物質の化学量論関係を纏めたものである。な
お、表２において、正極活物質の単位活物質重量あたり
の理論容量は１４０ｍＡｈ／ｇ、負極活物質の単位活物
質重量あたりの理論容量は２８０ｍＡｈ／ｇ、ＬｉｘＭ
ｎＯ２の単位活物質重量あたりの理論容量は２００ｍＡ
ｈ／ｇとして計算し、活物質量から算出した電池容量
は、実施例１、２の電池では、（１，４００×０．８）
＋１００＝１，２２０（ｍＡｈ）、比較例の電池では、
１，４００×０．８＝１，１２０（ｍＡｈ）として算出
した。Table 2 below summarizes the stoichiometry of the active materials in the batteries of Examples 1 and 2 and Comparative Example. In Table 2, the theoretical capacity per unit active material weight of the positive electrode active material was 140 mAh / g, the theoretical capacity per unit active material weight of the negative electrode active material was 280 mAh / g, and Li x M
The theoretical capacity of nO 2 per unit active material weight is 200 mA
The battery capacity calculated as h / g and calculated from the amount of active material was (1,400 × 0.8) in the batteries of Examples 1 and 2.
+ 100 = 1,220 (mAh), and in the battery of the comparative example,
It was calculated as 1,400 × 0.8 = 1,120 (mAh).
【００３４】[0034]
【表２】 [Table 2]
【００３５】表２に示すように、電池内に仕込んだ正極
及び負極活物質量やＬｉｘＭｎＯ２量から計算される電
池の放電容量と、図３及び図４に示した試験結果の容量
とは、実施例１、２の電池及び比較例の電池共にほぼ一
致していることが分かる。As shown in Table 2, the discharge capacity of the battery calculated from the amounts of the positive and negative electrode active materials and Li x MnO 2 charged in the battery, and the capacities of the test results shown in FIGS. Indicates that the batteries of Examples 1 and 2 and the battery of the comparative example are almost the same.
【００３６】なお、以上の実施形態では、正極活物質に
ＬｉＣｏＯ２を用い、第二正極活物質層にＬｉｘＭｎＯ
２のみからなる膜又はＬｉｘＭｎＯ２粉末を含む混合物
の層、及びＬｉｘＭｎＯ２の形成手順等を例示したが、
本発明はこれに限定されることなく上述した特許請求の
範囲内において他の種々の実施形態を採ることができる
ものである。In the above embodiment, LiCoO 2 is used for the positive electrode active material, and Li x MnO 2 is used for the second positive electrode active material layer.
2 and a layer of a mixture containing Li x MnO 2 powder, and a procedure for forming Li x MnO 2 , etc.
The present invention is not limited to this, and can adopt various other embodiments within the scope of the claims described above.
【００３７】[0037]
【発明の効果】以上説明したように、本発明によれば、
正極集電体と正極活物質との間に、該正極活物質よりも
放電電位が低い第二正極活物質層を備えているので、リ
チウム二次電池の高容量化を図ることができる点で効果
がある。As described above, according to the present invention,
Since the second positive electrode active material layer having a lower discharge potential than the positive electrode active material is provided between the positive electrode current collector and the positive electrode active material, the capacity of the lithium secondary battery can be increased. effective.
【図面の簡単な説明】[Brief description of the drawings]
【図１】本発明が適用可能な第１実施形態の円筒形リチ
ウム二次電池の断面図である。FIG. 1 is a cross-sectional view of a cylindrical lithium secondary battery according to a first embodiment to which the present invention can be applied.
【図２】正極集電体の両面にＬｉｘＭｎＯ２膜を形成さ
せるために作製した簡易リチウム電池の断面図である。FIG. 2 is a cross-sectional view of a simple lithium battery manufactured to form a Li x MnO 2 film on both surfaces of a positive electrode current collector.
【図３】実施例及び比較例の電池の初充電及び放電電圧
推移を示すグラフである。FIG. 3 is a graph showing initial charge and discharge voltage transitions of batteries of Examples and Comparative Examples.
【図４】実施例及び比較例の電池の充放電サイクルに伴
う放電容量推移を示すグラフである。FIG. 4 is a graph showing a change in discharge capacity of a battery of an example and a comparative example with a charge / discharge cycle.
１、１ａ 正極集電体 ２、２ａ ＬｉｘＭｎＯ２膜（第二正極活物質層） ３ 正極活物質層 ４ 負極集電体 ５ 負極活物質層 ６ セパレータ １１ 正極板（正極） １２ 負極板（負極） ２０ 円筒形リチウム二次電池（リチウム二次電池）1,1a positive electrode current collector 2, 2a Li x MnO 2 film (second positive electrode active material layer) 3 positive electrode active material layer 4 anode current collector 5 anode active material layer 6 separator 11 positive electrode plate (positive electrode) 12 a negative electrode plate ( Negative electrode) 20 Cylindrical lithium secondary battery (lithium secondary battery)
フロントページの続き Ｆターム(参考） 5H029 AJ03 AK03 AL08 AM03 AM04 AM05 AM07 BJ02 BJ12 BJ14 DJ08 DJ12 DJ17 EJ04 HJ02 HJ12 5H050 AA08 BA17 CA08 CA09 CB09 EA08 EA24 FA02 FA04 FA08 HA02 HA12 Continued on front page F-term (reference) 5H029 AJ03 AK03 AL08 AM03 AM04 AM05 AM07 BJ02 BJ12 BJ14 DJ08 DJ12 DJ17 EJ04 HJ02 HJ12 5H050 AA08 BA17 CA08 CA09 CB09 EA08 EA24 FA02 FA04 FA08 HA02 HA12
Claims (5)
蔵することができる正極活物質を塗着した正極と、リチ
ウムイオンを吸蔵・放出することができる炭素材を負極
活物質とする負極と、を用いたリチウム二次電池におい
て、前記正極集電体と前記正極活物質との間に、該正極
活物質よりも放電電位が低い第二正極活物質層を備えた
ことを特徴とするリチウム二次電池。A positive electrode comprising a positive electrode current collector coated with a positive electrode active material capable of releasing and storing lithium ions, and a negative electrode using a carbon material capable of storing and releasing lithium ions as a negative electrode active material. , A lithium secondary battery comprising a second positive electrode active material layer having a lower discharge potential than the positive electrode active material between the positive electrode current collector and the positive electrode active material. Rechargeable battery.
みからなる膜であるとを特徴とする請求項１に記載のリ
チウム二次電池。2. The lithium secondary battery according to claim 1, wherein the second positive electrode active material layer is a film made of only the second active material.
２の膜であることを特徴とする請求項１又は請求項２に
記載のリチウム二次電池。3. The method according to claim 2, wherein the second positive electrode active material layer is formed of Li x MnO.
The lithium secondary battery according to claim 1 or claim 2, characterized in that a second film.
質粉末と炭素粉末と結着材との混合物を含有することを
特徴とする請求項１に記載のリチウム二次電池。4. The lithium secondary battery according to claim 1, wherein the second positive electrode active material layer contains a mixture of a second positive electrode active material powder, a carbon powder, and a binder.
２粉末と炭素粉末と結着材との混合物からなることを特
徴とする請求項１又は請求項４に記載のリチウム二次電
池。5. The method according to claim 1, wherein the second positive electrode active material layer is formed of Li x MnO.
5. The lithium secondary battery according to claim 1, wherein the lithium secondary battery comprises a mixture of 2 powder, carbon powder, and a binder.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000126913A JP2001313024A (en) | 2000-04-27 | 2000-04-27 | Lithium secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000126913A JP2001313024A (en) | 2000-04-27 | 2000-04-27 | Lithium secondary battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2001313024A true JP2001313024A (en) | 2001-11-09 |
Family
ID=18636599
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2000126913A Abandoned JP2001313024A (en) | 2000-04-27 | 2000-04-27 | Lithium secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2001313024A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001338639A (en) * | 2000-05-25 | 2001-12-07 | Sony Corp | Non-aqueous electrolyte battery |
| KR100769567B1 (en) | 2005-12-07 | 2007-10-23 | 한국전기연구원 | Anode For Hybrid Capacitor, Manufacturing Method thereof and Hybrid Capacitor |
| US10985407B2 (en) | 2017-11-21 | 2021-04-20 | Samsung Electronics Co., Ltd. | All-solid-state secondary battery including anode active material alloyable with lithium and method of charging the same |
| US11824155B2 (en) | 2019-05-21 | 2023-11-21 | Samsung Electronics Co., Ltd. | All-solid lithium secondary battery and method of charging the same |
-
2000
- 2000-04-27 JP JP2000126913A patent/JP2001313024A/en not_active Abandoned
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001338639A (en) * | 2000-05-25 | 2001-12-07 | Sony Corp | Non-aqueous electrolyte battery |
| KR100769567B1 (en) | 2005-12-07 | 2007-10-23 | 한국전기연구원 | Anode For Hybrid Capacitor, Manufacturing Method thereof and Hybrid Capacitor |
| US10985407B2 (en) | 2017-11-21 | 2021-04-20 | Samsung Electronics Co., Ltd. | All-solid-state secondary battery including anode active material alloyable with lithium and method of charging the same |
| US11764407B2 (en) | 2017-11-21 | 2023-09-19 | Samsung Electronics Co., Ltd. | All-solid-state secondary battery including anode active material alloyable with lithium and method of charging the same |
| US11929463B2 (en) | 2017-11-21 | 2024-03-12 | Samsung Electronics Co., Ltd. | All-solid-state secondary battery and method of charging the same |
| US11824155B2 (en) | 2019-05-21 | 2023-11-21 | Samsung Electronics Co., Ltd. | All-solid lithium secondary battery and method of charging the same |
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