JP2000195550A - Nonaqueous electrolyte secondary battery - Google Patents
Nonaqueous electrolyte secondary batteryInfo
- Publication number
- JP2000195550A JP2000195550A JP10372464A JP37246498A JP2000195550A JP 2000195550 A JP2000195550 A JP 2000195550A JP 10372464 A JP10372464 A JP 10372464A JP 37246498 A JP37246498 A JP 37246498A JP 2000195550 A JP2000195550 A JP 2000195550A
- Authority
- JP
- Japan
- Prior art keywords
- negative electrode
- positive electrode
- sheet
- aqueous electrolyte
- 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.)
- Pending
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、非水電解液二次電
池に関する。TECHNICAL FIELD The present invention relates to a non-aqueous electrolyte secondary battery.
【０００２】[0002]
【従来の技術】近年、ノートパソコン、携帯電話等の小
型電子機器が急速に普及し、モバイルコンピューティン
グ化が進行しつつある。それに伴い、多機能化するこれ
ら電子機器の長時間駆動を可能にするために、電源であ
る二次電池に対する高容量化がますます強く要求されて
いる。かかる二次電池としては、リチウム複合金属酸化
物を含む正極と、リチウムイオンを吸蔵放出する炭素質
物を負極とする非水電解液二次電池が開発され、多く使
用されている。2. Description of the Related Art In recent years, small electronic devices such as notebook personal computers and mobile phones have rapidly spread, and mobile computing has been progressing. Along with this, in order to enable the multifunctional electronic devices to be driven for a long time, there is an increasing demand for higher capacity secondary batteries as power supplies. As such a secondary battery, a non-aqueous electrolyte secondary battery having a positive electrode containing a lithium composite metal oxide and a negative electrode made of a carbonaceous material that stores and releases lithium ions has been developed and used in many cases.
【０００３】前記非水電解液二次電池では、正負極共に
活物質として粉体状のものを用い、それと導電剤等を混
合し、結着剤を用いて集電体上にシート状に成形して電
極としている。前記電極をセパレータを介在させて積層
することで電極群を構成し容器に収め、非水溶媒にリチ
ウム塩を電解質として溶解させた非水電解液を加えて構
成されている。In the non-aqueous electrolyte secondary battery, both the positive and negative electrodes use a powdery active material, mix it with a conductive agent, and form a sheet on a current collector using a binder. And the electrodes. The electrodes are stacked with a separator interposed therebetween to form an electrode group, housed in a container, and added with a non-aqueous electrolyte in which a lithium salt is dissolved as an electrolyte in a non-aqueous solvent.
【０００４】現在、電池容量の増大は強い要請であり、
そのためには活物質のリチウムイオン吸蔵放出量の増加
やセパレータの膜厚を薄くすることなどが試みられてい
る。そうした電池容量増加の方法のひとつとして、正負
電極シートの高密度化も重要となりつつある。前記電極
は多孔質であり、その空隙に非水電解液が含浸する事で
大きな反応表面積が得られ、結果として活物質が有効利
用されている。しかし、電極シートの空隙率の低下は、
非水電解液の保液量の低下だけでなく、非水電解液の含
浸性の低下も伴う。これにより、活物質が有効利用され
ずに容量低下やレート特性の低下が起こる。また、リチ
ウム電池の正負電極は充放電に伴って活物質が膨張収縮
するために、電極内から非水電解液が押し出され易く非
水電解液の枯渇を招きサイクル特性低下につながる。空
隙率の低下による悪影響は正負両極で生じるが、これま
で正極では空隙率２５〜３０％程度以上を、負極では３
３％以上を確保する必要があり、電池高容量化のための
壁となっていた。At present, increasing the battery capacity is a strong demand,
For this purpose, attempts have been made to increase the amount of lithium ions absorbed and released by the active material and to reduce the thickness of the separator. As one method of increasing the battery capacity, increasing the density of the positive and negative electrode sheets is also becoming important. The electrode is porous, and a large reaction surface area is obtained by impregnating the void with a non-aqueous electrolyte, and as a result, the active material is effectively used. However, the decrease in the porosity of the electrode sheet
Not only does the retention amount of the non-aqueous electrolyte decrease, but also the impregnation of the non-aqueous electrolyte decreases. As a result, the active material is not effectively used, and the capacity and the rate characteristics decrease. In addition, since the active material of the positive and negative electrodes of the lithium battery expands and contracts with charging and discharging, the non-aqueous electrolyte is easily pushed out from the inside of the electrode, leading to depletion of the non-aqueous electrolyte, leading to deterioration in cycle characteristics. The adverse effect due to the decrease in the porosity occurs at both the positive and negative electrodes.
It is necessary to secure 3% or more, which has been a barrier for increasing the capacity of the battery.
【０００５】[0005]
【発明が解決しようとする課題】本発明は、リチウム複
合金属酸化物の粉体をシート状に成形した正極シートの
空隙率が２２％以下であり、かつリチウムを吸蔵放出す
ることのできる炭素質物をシート状に成形した負極シー
トの空隙率が３１％以下である高密度電極を有する非水
電解液二次電池において使用可能な非水電解液を提供す
ることを目的とする。SUMMARY OF THE INVENTION The present invention relates to a carbonaceous material which has a porosity of 22% or less and is capable of inserting and extracting lithium from a lithium composite metal oxide powder formed into a sheet. It is an object of the present invention to provide a non-aqueous electrolyte which can be used in a non-aqueous electrolyte secondary battery having a high-density electrode having a porosity of 31% or less in a negative electrode sheet formed into a sheet.
【０００６】[0006]
【課題を解決するための手段】本発明に係わる非水電解
液二次電池は、成式ＬｉＭ（１−ｘ）ＸｘＯ2-yＹ
y（Ｍ、ＸはＣｏ，Ｎｉ，Ｍｎのうちいずれかを表わ
す、ＹはＦ、Ｎのうちいずれかを表わす，０＜ｘ≦１、
０＜ｙ≦１）で表わされるリチウム複合金属酸化物であ
り、平均粒径が１μｍから５０μｍの粉体を正極活物質
とし、導電剤等をあわせてシート状に成形した空隙率２
２％以下の高密度正極シートおよび集電体からなる正極
と、リチウムを吸蔵放出することのできる炭素質物を負
極活物質としてシート状に成形した空隙率３１％以下の
高密度負極シートおよび集電体からなる負極と、前記正
極と前記負極の間に多孔性のセパレータを介在させて構
成した電極群と、非水溶媒と電解質を含有する非水電解
液を具備してなる非水電解液二次電池であって、前記非
水電解液の２０℃における粘度η（mPa・s）と電解質濃
度ｘ（モル／Ｌ）の比η／ｘが２以上４．５以下である
ことを特長とするものである。SUMMARY OF THE INVENTION A non-aqueous electrolyte secondary battery according to the present invention has the following formula: LiM (1-x) X x O 2-y Y
y (M, X represents any one of Co, Ni, Mn, Y represents any one of F, N, 0 <x ≦ 1,
0 <y ≦ 1), a powder having an average particle diameter of 1 μm to 50 μm as a positive electrode active material, and a porosity of 2 formed into a sheet by combining a conductive agent and the like.
A positive electrode comprising a high-density positive electrode sheet and a current collector of 2% or less, and a high-density negative electrode sheet having a porosity of 31% or less and formed into a sheet using a carbonaceous material capable of inserting and extracting lithium as a negative electrode active material and a current collector A non-aqueous electrolyte solution comprising a non-aqueous electrolyte solution comprising a non-aqueous electrolyte, a non-aqueous electrolyte solution containing a non-aqueous solvent and an electrolyte. A secondary battery, wherein the ratio η / x of the viscosity η (mPa · s) at 20 ° C. of the nonaqueous electrolyte to the electrolyte concentration x (mol / L) is 2 or more and 4.5 or less. Things.
【０００７】[0007]
【発明の実施の形態】以下に本発明に係わる非水電解液
二次電池（例えば円筒形非水電解液二次電池）を図１を
参照して詳細に説明する。DESCRIPTION OF THE PREFERRED EMBODIMENTS A non-aqueous electrolyte secondary battery (for example, a cylindrical non-aqueous electrolyte secondary battery) according to the present invention will be described in detail with reference to FIG.
【０００８】例えばステンレスからなる有底円筒状の容
器１は、底部に絶縁体２が配置されている。電極群３は
前記容器1内に収納されている。前記電極群３は、正極
シートを集電体上に備えた正極４、セパレータ５及び負
極シートを集電体上に備えた負極６をこの順序で積層し
た帯状物を前記負極６が外側に位置するように渦巻状に
捲回した構造になっている。前記セパレータ５は、例え
ば合成樹脂製不織布、ポリエチレン多孔質フィルム、ポ
リプロピレン多孔質フィルムから形成されている。For example, a cylindrical container 1 having a bottom made of stainless steel has an insulator 2 disposed at the bottom. The electrode group 3 is housed in the container 1. The electrode group 3 is a strip formed by laminating a positive electrode 4 provided with a positive electrode sheet on a current collector, a separator 5 and a negative electrode 6 provided with a negative electrode sheet on a current collector in this order. The structure is spirally wound. The separator 5 is formed of, for example, a synthetic resin nonwoven fabric, a polyethylene porous film, or a polypropylene porous film.
【０００９】前記容器1内には、非水電解液が収納され
ている。中央部が開口された絶縁紙７は、前記容器１内
の前記電極群３の上方に載置されている。絶縁封口板８
は、前記容器１の上部開口部に配置され、かつ前記上部
開口部付近を内側にかしめ加工することにより前記封口
板８は前記容器１に液密に固定されている。正極端子９
は、前記絶縁封口板８の中央にはめ込まれている。正極
リード１０の一端は、前記正極４に、他端は前記正極端
子９にそれぞれ接続されている。前記負極６は、図示し
ない負極リードを介して負極端子である前記容器１に接
続されている。In the container 1, a non-aqueous electrolyte is stored. The insulating paper 7 having a central portion opened is placed above the electrode group 3 in the container 1. Insulating sealing plate 8
Is disposed in the upper opening of the container 1 and the vicinity of the upper opening is caulked inward to fix the sealing plate 8 to the container 1 in a liquid-tight manner. Positive terminal 9
Is fitted in the center of the insulating sealing plate 8. One end of the positive electrode lead 10 is connected to the positive electrode 4, and the other end is connected to the positive electrode terminal 9. The negative electrode 6 is connected to the container 1 as a negative electrode terminal via a negative electrode lead (not shown).
【００１０】次に、前記正極４、前記負極６および前記
非水電解液の構成について具体的に説明する。 １）正極の構成 前記正極４は、活物質、導電材および結着剤等をあわせ
てシート状に成形した空隙率２２％以下の高密度正極シ
ートを集電体の片面もしくは両面に備えた電極である。Next, the configurations of the positive electrode 4, the negative electrode 6, and the non-aqueous electrolyte will be specifically described. 1) Configuration of Positive Electrode The positive electrode 4 is an electrode provided with a high-density positive electrode sheet having a porosity of 22% or less formed on a sheet by combining an active material, a conductive material, a binder, and the like on one or both surfaces of a current collector. It is.
【００１１】前記活物質は成式ＬｉＭ（１−ｘ）ＸｘＯ
2-yＹy（Ｍ、ＸはＣｏ，Ｎｉ，Ｍｎのうちいずれかを表
わす、ＹはＦ、Ｎのうちいずれかを表わす，０＜ｘ≦
１、０＜ｙ≦１）で表わされるリチウム複合金属酸化物
であり、平均粒径が１μｍから５０μｍの粉体である。
前記正極活物質を一種、あるいは複数種類混合して用い
ることができる。The active material is of the formula LiM (1-x) X x O
2-y Y y (M and X represent any one of Co, Ni and Mn, Y represents any one of F and N, 0 <x ≦
1, 0 <y ≦ 1) and a powder having an average particle size of 1 μm to 50 μm.
The above-mentioned positive electrode active materials can be used singly or as a mixture of a plurality of types.
【００１２】前記導電剤は、特に限定されるものではな
いが、アセチレンブラック、各種形状の天然および人工
黒鉛、コークス等を用いる事ができる。The conductive agent is not particularly limited, but acetylene black, natural and artificial graphite of various shapes, coke, and the like can be used.
【００１３】前記結着剤としては、ポリテトラフルオロ
エチレン（ＰＴＦＥ）、ポリフッ化ビニリデン（ＰＶｄ
Ｆ）、エチレン−プロピレン−ジエン共重合体、スチレ
ン−ブタジエンゴム等を用いることができる。As the binder, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVd)
F), ethylene-propylene-diene copolymer, styrene-butadiene rubber and the like can be used.
【００１４】前記集電体としては、例えばアルミニウム
箔、ステンレス箔、ニッケル箔等を用いることができ
る。As the current collector, for example, aluminum foil, stainless steel foil, nickel foil or the like can be used.
【００１５】前記正極活物質と前記導電剤は、前記結着
剤を加えて混練によりシート化することができる。ある
いは、トルエン、Ｎ−メチルピロリドン（ＮＭＰ）等の
溶媒に溶解、懸濁してスラリー化した後、前記集電体上
に塗布、乾燥してシート化することも可能である。その
後、必要に応じてロールプレス等を用いた圧延を行うこ
とによって正極シートの空隙率を制御することができ
る。前記空隙率は、前記正極の内で前記集電体を除いた
部分である正極シートについて定義される。前記空隙率
は前記正極シートに含まれるすべての成分の重量構成比
および比重から計算によって求めることができる。 ２）負極の構成 前記負極６は、負極活物質および結着剤等をあわせてシ
ート状に成形した空隙率３１％以下の高密度負極シート
を集電体の片面もしくは両面に備えた電極である。[0015] The positive electrode active material and the conductive agent can be formed into a sheet by kneading with the addition of the binder. Alternatively, after dissolving and suspending in a solvent such as toluene or N-methylpyrrolidone (NMP) to form a slurry, the slurry may be coated on the current collector and dried to form a sheet. Thereafter, the porosity of the positive electrode sheet can be controlled by performing rolling using a roll press or the like as necessary. The porosity is defined for a positive electrode sheet that is a portion of the positive electrode excluding the current collector. The porosity can be determined by calculation from the weight composition ratio and specific gravity of all components contained in the positive electrode sheet. 2) Configuration of Negative Electrode The negative electrode 6 is an electrode provided on one or both sides of a current collector with a high-density negative electrode sheet having a porosity of 31% or less formed by combining a negative electrode active material, a binder, and the like into a sheet. .
【００１６】前記負極活物質はリチウムを吸蔵放出する
ことのできる炭素質材料である。前記炭素質材料は特に
限定されるものではないが、原料として、石油や石炭な
どのコークスやピッチ、天然ガスや低級炭化水素などの
低分子量有機化合物、ポリアクリロニトリル、フェノー
ル樹脂等の合成高分子などが上げられ、これらを７００
℃から3000℃で焼成して炭化あるいは黒鉛化して炭素質
材料としたものを用いることができる。形状としてはり
ん片状、繊維状、球状など各種形状のものが可能であ
る。The negative electrode active material is a carbonaceous material capable of inserting and extracting lithium. The carbonaceous material is not particularly limited, but as a raw material, coke or pitch such as petroleum or coal, a low molecular weight organic compound such as natural gas or lower hydrocarbon, polyacrylonitrile, a synthetic polymer such as a phenol resin, and the like. Are raised to 700
A carbonaceous material which is carbonized or graphitized by firing at 3,000 to 3000 ° C. can be used. Various shapes such as flakes, fibers, and spheres are possible.
【００１７】前記結着剤としては、ポリテトラフルオロ
エチレン（ＰＴＦＥ）、ポリフッ化ビニリデン（ＰＶｄ
Ｆ）、スチレン−ブタジエンゴム、カルボキシメチルセ
ルロース（ＣＭＣ）等を用いることができる。As the binder, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVd)
F), styrene-butadiene rubber, carboxymethyl cellulose (CMC) and the like can be used.
【００１８】前記集電体としては、例えば銅箔、ステン
レス箔、ニッケル箔等を用いることができる。As the current collector, for example, a copper foil, a stainless steel foil, a nickel foil or the like can be used.
【００１９】前記負極活物質と前記結着剤は、水、Ｎ−
メチルピロリドン（ＮＭＰ）等の溶媒に溶解、懸濁して
スラリー化した後、前記集電体上に塗布、乾燥してシー
ト化することができる。その後、必要に応じてロールプ
レス等を用いた圧延を行うことによって負極シートの空
隙率を制御することができる。前記空隙率は、前記負極
の内で前記集電体を除いた部分である負極シートについ
て定義される。前記空隙率は前記負極シートに含まれる
すべての成分の重量構成比および比重から計算によって
求めることができる。 ３）非水電解液の構成 前記容器1内に収容される前記非水電解液としては、２
０℃における粘度η（mPa・s）と電解質濃度ｘ（モル／
Ｌ）の比η／ｘが２以上４．５以下であるものが使用さ
れる。The negative electrode active material and the binder are water, N-
After dissolving and suspending in a solvent such as methylpyrrolidone (NMP) to form a slurry, it can be coated on the current collector and dried to form a sheet. Thereafter, the porosity of the negative electrode sheet can be controlled by performing rolling using a roll press or the like as necessary. The porosity is defined for a negative electrode sheet that is a portion of the negative electrode excluding the current collector. The porosity can be obtained by calculation from the weight composition ratio and specific gravity of all components contained in the negative electrode sheet. 3) Configuration of Nonaqueous Electrolyte The nonaqueous electrolyte contained in the container 1 is 2
The viscosity η (mPa · s) at 0 ° C. and the electrolyte concentration x (mol /
L) having a ratio η / x of 2 or more and 4.5 or less is used.
【００２０】前記非水電解液は、少なくとも一種類以上
の非水溶媒と、リチウムを含む少なくとも一種類以上の
電解質から構成される。The non-aqueous electrolyte comprises at least one kind of non-aqueous solvent and at least one kind of electrolyte containing lithium.
【００２１】前記非水溶媒として、エチレンカーボネー
ト、プロピレンカーボネートなどの環状カーボネート、
γ―ブチロラクトン等の環状エステル、エチルメチルカ
ーボネート、ジメチルカーボネート、ジエチルカーボネ
ートなどの鎖状カーボネート、テトラメチルスルフォラ
ン、Ｎ−メチルピロリドンなどを単独あるいは複数種混
合して用いることができる。As the non-aqueous solvent, cyclic carbonates such as ethylene carbonate and propylene carbonate;
Cyclic esters such as γ-butyrolactone, chain carbonates such as ethyl methyl carbonate, dimethyl carbonate and diethyl carbonate, tetramethylsulfolane, N-methylpyrrolidone and the like can be used alone or in combination.
【００２２】前記電解質として、例えば、過塩素酸リチ
ウム（ＬｉＣｌＯ４）、六フッ化リン酸リチウム（Ｌｉ
ＰＦ６）、ホウフッ化リチウム（ＬｉＢＦ４）、ビスト
リフルオロメチルスルホニルイミドリチウム（ＬｉＮ
（ＣＦ３ＳＯ２）２）などのリチウム塩が挙げられる。Examples of the electrolyte include lithium perchlorate (LiClO 4 ) and lithium hexafluorophosphate (Li
PF 6 ), lithium borofluoride (LiBF 4 ), lithium bistrifluoromethylsulfonylimide (LiN
(CF3SO 2) 2) is a lithium salt and the like.
【００２３】前記粘度η（mPa・s）は市販の回転式粘度
計を用いて測定した値でよい。測定は２０℃で行う。The viscosity η (mPa · s) may be a value measured using a commercially available rotary viscometer. The measurement is performed at 20 ° C.
【００２４】以上説明した本発明に係わる非水電解液二
次電池は、成式ＬｉＭ（１−ｘ）Ｘ ｘＯ2-yＹy（Ｍ、Ｘ
はＣｏ，Ｎｉ，Ｍｎのうちいずれかを表わす、ＹはＦ、
Ｎのうちいずれかを表わす，０＜ｘ≦１、０＜ｙ≦１）
で表わされるリチウム複合金属酸化物であり、平均粒径
が１μｍから５０μｍの粉体を正極活物質とし、導電剤
等をあわせてシート状に成形した空隙率２２％以下の高
密度正極シートおよび集電体からなる正極と、リチウム
を吸蔵放出することのできる炭素質物を負極活物質とし
てシート状に成形した空隙率３１％以下の高密度負極シ
ートおよび集電体からなる負極と、前記正極と前記負極
の間に多孔性のセパレータを介在させて構成した電極群
と、非水溶媒と電解質を含有する非水電解液を具備して
なる非水電解液二次電池であって、前記非水電解液の２
０℃における粘度η（mPa・s）と電解質濃度ｘ（モル／
Ｌ）の比η／ｘが２以上４．５以下である。このような
非水電解液二次電池は、従来において実用化されてきた
ものに比べて、大きな容量および放電レート特性、サイ
クル特性を実現できる。The non-aqueous electrolyte 2 according to the present invention described above
The secondary battery is LiM(1-x)X xO2-yYy(M, X
Represents any of Co, Ni and Mn, Y represents F,
Represents any one of N, 0 <x ≦ 1, 0 <y ≦ 1)
Is a lithium composite metal oxide represented by
A powder of 1 μm to 50 μm as a positive electrode active material, and a conductive agent
High porosity of 22% or less
A positive electrode comprising a high-density positive electrode sheet and a current collector, and lithium
A carbonaceous material capable of inserting and extracting nitrogen is used as a negative electrode active material.
High-density negative electrode with a porosity of 31% or less
A negative electrode comprising a sheet and a current collector, the positive electrode and the negative electrode
Electrodes composed of a porous separator interposed between them
And a non-aqueous electrolyte containing a non-aqueous solvent and an electrolyte.
A non-aqueous electrolyte secondary battery comprising:
The viscosity η (mPa · s) at 0 ° C. and the electrolyte concentration x (mol /
L) ratio η / x is 2 or more and 4.5 or less. like this
Non-aqueous electrolyte secondary batteries have been practically used in the past.
Large capacity and discharge rate characteristics, size
It is possible to realize the hull characteristics.
【００２５】これまで、非水電解液の研究は主にイオン
導伝率の高いものを得ることを目的として行われてき
た。しかし、実際の電池において非水電解液を使用した
場合は必ずしも、得られる電池特性とイオン導伝率は相
関していなかった。本研究では、イオン導伝率以上に粘
度と電解質濃度に着目して鋭意研究を行う事で、従来に
おいて実用化されてきた電極よりも高い充填密度をもつ
正負電極シートの使用を可能してより大きな電池容量を
実現したばかりでなく、前記空隙率以下の高密度電極で
放電レート特性の向上をも実現した。ここで、正負電極
シートの空隙率は極めて重要である。つまり、空隙率を
小さくすれば単位体積当たりにより多くを充填すること
ができるため、計算上は電池の容量を向上させることが
できるが、これまで実用化されていない。しかし、前記
粘度η（mPa・s）と前記電解質濃度ｘ（モル／Ｌ）の比
η／ｘが２以上４．５以下である非水電解液を前記高密
度電極シートに適用することで、高容量電池を可能にし
た。これは以下のような理由によるものである。前記高
密度電極シートを使用した場合は、電池製造プロセスで
の非水電解液注入時における非水電解液の正負電極シー
トへの含浸や、充放電中の活物質の体積膨張収縮に伴う
電極群からの非水電解液の出入りに追随できることが重
要であり、これは非水電解液の粘度によって決まる。加
えて、前記高密度電極シートでは、電極シート中に保持
しうる非水電解液の絶対量が少なく電池反応に必要なリ
チウムイオンの量が不足するために、非水電解液中の電
解質濃度が重要になる。これら非水電解液の粘度と電解
質濃度はそれぞれ単独では十分な効果がなく、ある一定
のバランスを保つときに大きな効果を表すことが見出さ
れた。それがすなわち前記粘度η（mPa・s）と前記電解
質濃度ｘ（モル／Ｌ）の比η／ｘが２以上４．５以下で
ある。前記比η／ｘが２を下回ると、活物質表面での非
水電解液の分解が顕著になる。これは、低粘度の溶媒を
用いるため溶媒による電解質の溶媒和が十分でないため
と考えられる。加えて粘度が低いために電極シートへの
含浸は容易であるが逆に電極シートからの沁みだしも容
易になり電池のサイクル中に電極群中の非水電解液が枯
渇する。以上の結果としてサイクル特性が低い。逆に、
前記比η／ｘが４．５を超えると、非水電解液による十
分なリチウムイオンの活物質への供給が行われなくなり
容量が低下する。前記粘度が３〜６．５mPa・sかつ前記
電解質濃度が１．２〜１．６モル／Ｌのときにより効果
が大きい。これは、前記電解質濃度が１．２モル／Ｌよ
り低いとサイクル中での電解質の少量の分解であって
も、サイクル特性に影響を与えてしまい、サイクル特性
の劣化が見られるためである。一方、１．６モル／Ｌを
超えると、溶媒による電解質の溶媒和が弱まり、電解質
の分解が大きくなるためである。また、より好ましくは
η／ｘが３．５〜４．２である。Heretofore, research on non-aqueous electrolytes has been conducted mainly with the aim of obtaining one having a high ionic conductivity. However, when a non-aqueous electrolyte was used in an actual battery, the obtained battery characteristics and ion conductivity were not always correlated. In this research, we focused on viscosity and electrolyte concentration more than ionic conductivity and made it possible to use positive and negative electrode sheets with higher packing density than electrodes that have been practically used in the past. Not only a large battery capacity was realized, but also an improvement in discharge rate characteristics was realized with a high-density electrode having the porosity or less. Here, the porosity of the positive and negative electrode sheets is extremely important. In other words, if the porosity is reduced, more can be filled per unit volume, so that the capacity of the battery can be calculated, but it has not been put to practical use. However, by applying a non-aqueous electrolyte having a ratio η / x of the viscosity η (mPa · s) to the electrolyte concentration x (mol / L) of 2 or more and 4.5 or less to the high-density electrode sheet, High-capacity batteries were made possible. This is due to the following reasons. When the high-density electrode sheet is used, impregnation of the non-aqueous electrolyte into the positive and negative electrode sheets during non-aqueous electrolyte injection in the battery manufacturing process, and an electrode group associated with volume expansion and contraction of the active material during charging and discharging It is important to be able to follow the inflow and outflow of the nonaqueous electrolyte from the electrolyte, which is determined by the viscosity of the nonaqueous electrolyte. In addition, in the high-density electrode sheet, since the absolute amount of the non-aqueous electrolyte that can be held in the electrode sheet is small and the amount of lithium ions necessary for the battery reaction is insufficient, the electrolyte concentration in the non-aqueous electrolyte is low. Becomes important. It has been found that the viscosity and electrolyte concentration of these non-aqueous electrolytes alone do not have a sufficient effect, but show a significant effect when a certain balance is maintained. That is, the ratio η / x between the viscosity η (mPa · s) and the electrolyte concentration x (mol / L) is 2 or more and 4.5 or less. When the ratio η / x is less than 2, the decomposition of the non-aqueous electrolyte on the surface of the active material becomes significant. This is presumably because a low-viscosity solvent is used, and solvation of the electrolyte by the solvent is not sufficient. In addition, since the viscosity is low, the impregnation into the electrode sheet is easy, but conversely the seepage from the electrode sheet is also easy, and the non-aqueous electrolyte in the electrode group is depleted during the cycle of the battery. As a result, the cycle characteristics are low. vice versa,
When the ratio η / x exceeds 4.5, sufficient supply of lithium ions to the active material by the nonaqueous electrolyte is not performed, and the capacity decreases. The effect is greater when the viscosity is 3 to 6.5 mPa · s and the electrolyte concentration is 1.2 to 1.6 mol / L. This is because if the electrolyte concentration is lower than 1.2 mol / L, even if a small amount of the electrolyte is decomposed in the cycle, the cycle characteristics are affected, and the cycle characteristics are deteriorated. On the other hand, when it exceeds 1.6 mol / L, the solvation of the electrolyte by the solvent is weakened, and the decomposition of the electrolyte is increased. Further, η / x is more preferably 3.5 to 4.2.
【００２６】前記粘度と前記電解質濃度の条件を満たす
ときに、従来よりも高密度な電極シートが使用可能にな
り電池の高容量化を図ることができるが、前記非水電解
液を用いるときに正極シートにおいては空隙率２２％以
下、負極シートにおいては空隙率３１％以下とすること
で、前記正負電極シートを構成する活物質や導電剤が近
接して放電レート特性が向上することが見出された。よ
り好ましい範囲は正極シートで１８〜２０％、負極シー
トで２８〜３０．５％の範囲であり、前記範囲の電極シ
ートであると電池製造時の非水電解液含浸が容易であり
短時間での非水電解液注入が可能となる。また、正極活
物質の平均粒径は、３〜１２μｍのときに、過大な圧延
を行うことなく前記の空隙率を満たし易いため活物質の
圧延時の損壊がなく、特に良好な特性が得られる。前記
のより好ましい比η／ｘである３．５〜４．２の非水電
解液は、前記のより好ましい正極シート空隙率１８〜２
０％および負極シート空隙率２８〜３０．５％のものと
組み合わせるとき最も良好な放電レート特性および高容
量が得られる。When the conditions of the viscosity and the electrolyte concentration are satisfied, it is possible to use an electrode sheet having a higher density than in the prior art and to increase the capacity of the battery. By setting the porosity to 22% or less in the positive electrode sheet and the porosity to 31% or less in the negative electrode sheet, it was found that the active material and the conductive agent constituting the positive and negative electrode sheets approached to improve the discharge rate characteristics. Was done. A more preferable range is 18 to 20% for the positive electrode sheet and 28 to 30.5% for the negative electrode sheet. When the electrode sheet has the above range, impregnation with a non-aqueous electrolyte during battery production is easy, and the Can be injected into the non-aqueous electrolyte. In addition, when the average particle diameter of the positive electrode active material is 3 to 12 μm, the porosity is easily satisfied without performing excessive rolling, so that the active material is not damaged during rolling, and particularly favorable characteristics are obtained. . The non-aqueous electrolyte having a more preferable ratio η / x of 3.5 to 4.2 has a positive electrode sheet porosity of 18 to 2 as described above.
The best discharge rate characteristics and the highest capacity can be obtained when combined with 0% and the negative electrode sheet porosity of 28 to 30.5%.
【００２７】以上の本発明とその効果を図２を用いて詳
細に説明する。The present invention and its effects will be described in detail with reference to FIG.
【００２８】図２中で領域Ａは本発明を表し、正負極シ
ート共に、前記空隙率以下かつ非水電解液が２＜η／ｘ
４．５を満たす範囲である。これら条件を満たすため
に、電極が高密度であるため高容量が得られ、活物質が
近接するために放電レート特性が高く、電解液の含浸・
保持が十分に行われるため良好なサイクル特性が得られ
る。領域Ｂは少なくとも正極シートか負極シートのいず
れかの空隙率が高い範囲であり、非水電解液の含浸は十
分であるが、電極密度が低いため放電レート特性が低
く、電池容量も小さい。領域Ｃは比η／ｘが２を下回る
領域であり、活物質表面での非水電解液の分解が顕著に
なるためにサイクル特性が低い。領域Ｄは比η／ｘが
４．５を超える範囲であり、粘度と電解質濃度のバラン
スが十分でなく、粘度に対して電解質濃度が低いために
活物質へのリチウムイオン供給が十分に行われず、電極
シート中の活物質が有効利用されないために容量が小さ
く、放電レート特性も低い。領域Ｅは比η／ｘが４．５
を超え、電極シートの空隙率も高いために領域ＢとＤの
欠点を合わせ持ち、電池容量が小さく、放電レート特性
が低い。領域Ｆは比η／ｘが２を下回り、電極シートの
空隙率も高いために領域ＢとＣの欠点を合わせ持ち、電
池容量が小さく、放電レート特性とサイクル特性が低
い。 (実施例)以下、本発明の実施例を詳細に説明する。 （実施例１）平均粒径５μｍのリチウムコバルト酸化物
（ＬｉｘＣｏＯ２（０．８≦ｘ≦１））粉末９１重量
％、アセチレンブラック３重量％、グラファイト３重量
％、ポリフッ化ビニリデン３重量％をＮ−メチルピロリ
ドンに加えて混合してスラリーとし、このスラリーを２
５μのアルミニウム箔からなる集電体の両面に塗布後、
熱風乾燥してＮ−メチルピロリドンを除去し、プレスす
ることにより空隙率１９％の正極シートを備えた正極を
作成した。塗布量は片面当たり２００ｇ／ｍ２で、プレ
ス後の前記電極の厚さは１４２μｍであった。In FIG. 2, a region A represents the present invention, and the positive and negative electrode sheets have a porosity equal to or less than the porosity and the non-aqueous electrolyte is 2 <η / x.
This is a range that satisfies 4.5. In order to satisfy these conditions, a high capacity is obtained due to the high density of the electrodes, and the discharge rate characteristics are high due to the close proximity of the active material.
Good cycle characteristics are obtained because the holding is performed sufficiently. The region B is a range where the porosity of at least either the positive electrode sheet or the negative electrode sheet is high, and the impregnation with the non-aqueous electrolyte is sufficient. However, since the electrode density is low, the discharge rate characteristics are low and the battery capacity is low. Region C is a region where the ratio η / x is less than 2, and the decomposition of the non-aqueous electrolyte on the active material surface becomes remarkable, so that the cycle characteristics are low. In the region D, the ratio η / x exceeds 4.5, the balance between the viscosity and the electrolyte concentration is not sufficient, and the electrolyte concentration is low with respect to the viscosity, so that lithium ions are not sufficiently supplied to the active material. Since the active material in the electrode sheet is not effectively used, the capacity is small and the discharge rate characteristics are low. In the region E, the ratio η / x is 4.5.
, And the porosity of the electrode sheet is high, so that it has the disadvantages of regions B and D, the battery capacity is small, and the discharge rate characteristics are low. Region F has a drawback of regions B and C because the ratio η / x is less than 2 and the porosity of the electrode sheet is high, the battery capacity is small, and the discharge rate characteristics and cycle characteristics are low. (Examples) Hereinafter, examples of the present invention will be described in detail. Example 1 91% by weight of lithium cobalt oxide (LixCoO 2 (0.8 ≦ x ≦ 1)) powder having an average particle size of 5 μm, 3% by weight of acetylene black, 3% by weight of graphite, and 3% by weight of polyvinylidene fluoride Add to N-methylpyrrolidone and mix to form a slurry.
After coating on both sides of a current collector made of 5μ aluminum foil,
Hot air drying was performed to remove N-methylpyrrolidone, and pressing was performed to produce a positive electrode having a positive electrode sheet having a porosity of 19%. The coating amount was 200 g / m 2 per one side, and the thickness of the electrode after pressing was 142 μm.
【００２９】また、メソフェーズピッチを原料としたメ
ソフェーズ炭素繊維をアルゴン雰囲気下で６００℃にて
熱処理後、平均粒径２０μに粉砕し、不活性雰囲気下で
３０００℃にて黒鉛化することにより炭素質物を製造し
た。Further, a mesophase carbon fiber using mesophase pitch as a raw material is heat-treated at 600 ° C. in an argon atmosphere, crushed to an average particle diameter of 20 μm, and graphitized at 3000 ° C. in an inert atmosphere to obtain a carbonaceous material. Was manufactured.
【００３０】前記炭素質物９６．７重量％をスチレンブ
タジエンゴム２．２重量％およびカルボキシメチルセル
ロース１．１重量％と共に混合し、水を溶媒として使用
してスラリーとし、これを銅箔からなる集電体の両面に
塗布後、乾燥した。これをプレスすることにより空隙率
３０％の負極シートを備えた負極を作成した。塗布量は
片面当たり８０ｇ／ｍ２で、プレス後の前記電極の厚さ
は１２３μｍであった。96.7% by weight of the carbonaceous material is mixed with 2.2% by weight of styrene-butadiene rubber and 1.1% by weight of carboxymethylcellulose, and a slurry is formed using water as a solvent. After application to both sides of the body, it was dried. This was pressed to produce a negative electrode provided with a negative electrode sheet having a porosity of 30%. The coating amount was 80 g / m 2 per one side, and the thickness of the electrode after pressing was 123 μm.
【００３１】前記正極、ポリエチレン製多孔質フィルム
からなるセパレータおよび前記負極シートをそれぞれこ
の順序で積層した後、渦巻き状に捲回して円筒形状の電
極群を作成した。The positive electrode, the separator made of a porous film made of polyethylene, and the negative electrode sheet were laminated in this order, and then spirally wound to form a cylindrical electrode group.
【００３２】さらに、電解質としての六フッ化リン酸リ
チウム（ＬｉＰＦ６）を、エチレンカーボネート（Ｅ
Ｃ）、エチルメチルカーボネート（ＭＥＣ）の混合溶媒
（体積比率３４：６６）に１．５モル／Ｌ溶解して非水
電解液を調製した。前記組成の非水電解液の粘度は、回
転式粘度計（東機産業製、Ｒ型粘度計）で２０℃にて測
定したところ、６．１mPa・sであった。η／ｃは４．０
７である。Further, lithium hexafluorophosphate (LiPF 6 ) as an electrolyte was replaced with ethylene carbonate (E
C) and 1.5 mol / L in a mixed solvent of ethyl methyl carbonate (MEC) (volume ratio 34:66) to prepare a non-aqueous electrolyte. The viscosity of the nonaqueous electrolytic solution having the above composition was 6.1 mPa · s as measured at 20 ° C. with a rotary viscometer (manufactured by Toki Sangyo Co., Ltd., R-type viscometer). η / c is 4.0
7
【００３３】前記電極群及び前記電解液をステンレス製
の有底円筒状容器内にそれぞれ収納して前述した図１に
示す構造を有する円筒形非水電解液二次電池を組み立て
た。 （実施例２）正極の厚みを１４７μにして、正極シート
の空隙率を２２％にした以外は実施例１と同様な構成で
前述した円筒形非水電解液二次電池を組み立てた。 （実施例３）負極の厚みを１２５μにして、負極シート
の空隙率を３１％にした以外は実施例１と同様な構成で
前述した円筒形非水電解液二次電池を組み立てた。 （実施例４）電解質としての六フッ化リン酸リチウム
（ＬｉＰＦ６）を、エチレンカーボネート（ＥＣ）、エ
チルメチルカーボネート（ＭＥＣ）の混合溶媒（体積比
率３４：６６）に１．２５モル／Ｌ溶解して非水電解液
を調製した。前記組成の非水電解液の粘度は、回転式粘
度計（東機産業製、Ｒ型粘度計）で２０℃にて測定した
ところ、４．４mPa・sであった。η／ｃは３．５２であ
った。前記非水電解液以外は実施例１と同様な構成で前
述した円筒形非水電解液二次電池を組み立てた。 （実施例５）電解質としてのホウフッ化リチウム（Ｌｉ
ＢＦ４）を、エチレンカーボネート（ＥＣ）、γ−ブチ
ロラクトン（ＢＬ）の混合溶媒（体積比率２５：７５）
に１モル／Ｌ溶解して非水電解液を調製した。前記組成
の非水電解液の粘度は、回転式粘度計（東機産業製、Ｒ
型粘度計）で２０℃にて測定したところ、４．０mPa・s
であった。η／ｃは４．００であった。前記非水電解液
以外は実施例１と同様な構成で前述した円筒形非水電解
液二次電池を組み立てた。 （比較例１）正極の厚みを１５３μにして、正極シート
の空隙率を２６％にした以外は実施例１と同様な構成で
前述した円筒形非水電解液二次電池を組み立てた。図２
では範囲Ｂにあたる比較例である。 （比較例２）負極の厚みを１３０μにして、負極シート
の空隙率を３４％にした以外は実施例１と同様な構成で
前述した円筒形非水電解液二次電池を組み立てた。図２
では範囲Ｂにあたる比較例である。 （比較例３）電解質としての六フッ化リン酸リチウム
（ＬｉＰＦ６）を、エチルメチルカーボネート（ＭＥ
Ｃ）に１モル／Ｌ溶解して非水電解液を調製した。前記
組成の非水電解液の粘度は、回転式粘度計（東機産業
製、Ｒ型粘度計）で２０℃にて測定したところ、１．８
mPa・sであった。η／ｃは１．８であった。前記非水電
解液以外は実施例１と同様な構成で前述した円筒形非水
電解液二次電池を組み立てた。図２では範囲Ｃにあたる
比較例である。 （比較例４）電解質としての六フッ化リン酸リチウム
（ＬｉＰＦ６）を、エチレンカーボネート（ＥＣ）、エ
チルメチルカーボネート（ＭＥＣ）の混合溶媒（体積比
率３４：６６）に２モル／Ｌ溶解して非水電解液を調製
した。前記組成の非水電解液の粘度は、回転式粘度計
（東機産業製、Ｒ型粘度計）で２０℃にて測定したとこ
ろ、９．８mPa・sであった。η／ｃは４．９であった。
前記非水電解液以外は実施例１と同様な構成で前述した
円筒形非水電解液二次電池を組み立てた。図２では範囲
Ｄにあたる比較例である。 （比較例５）正極の厚みを１５３μにして、正極シート
の空隙率を２６％にした以外は実施例１と同様な正極を
作成した。The above-mentioned electrode group and the above-mentioned electrolytic solution were respectively housed in a stainless steel bottomed cylindrical container to assemble the above-mentioned cylindrical non-aqueous electrolyte secondary battery having the structure shown in FIG. (Example 2) The cylindrical nonaqueous electrolyte secondary battery described above was assembled in the same manner as in Example 1 except that the thickness of the positive electrode was 147 µm and the porosity of the positive electrode sheet was 22%. (Example 3) The cylindrical non-aqueous electrolyte secondary battery described above was assembled in the same manner as in Example 1 except that the thickness of the negative electrode was 125 µm and the porosity of the negative electrode sheet was 31%. (Example 4) 1.25 mol / L of lithium hexafluorophosphate (LiPF 6 ) as an electrolyte was dissolved in a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (MEC) (volume ratio 34:66). Thus, a non-aqueous electrolyte was prepared. The viscosity of the nonaqueous electrolytic solution having the above composition was 4.4 mPa · s as measured at 20 ° C. with a rotary viscometer (manufactured by Toki Sangyo, R-type viscometer). η / c was 3.52. The cylindrical non-aqueous electrolyte secondary battery described above was assembled in the same configuration as in Example 1 except for the non-aqueous electrolyte. (Example 5) Lithium borofluoride (Li
BF 4 ) was mixed with a mixed solvent of ethylene carbonate (EC) and γ-butyrolactone (BL) (volume ratio 25:75).
Was dissolved in 1 mol / L to prepare a non-aqueous electrolyte. The viscosity of the non-aqueous electrolyte having the above composition was measured using a rotary viscometer (manufactured by Toki Sangyo, R
4.0 mPa · s when measured at 20 ° C.
Met. η / c was 4.00. The cylindrical non-aqueous electrolyte secondary battery described above was assembled in the same configuration as in Example 1 except for the non-aqueous electrolyte. (Comparative Example 1) The cylindrical nonaqueous electrolyte secondary battery described above was assembled in the same configuration as in Example 1 except that the thickness of the positive electrode was 153 µm and the porosity of the positive electrode sheet was 26%. FIG.
Is a comparative example corresponding to the range B. (Comparative Example 2) The cylindrical non-aqueous electrolyte secondary battery described above was assembled in the same configuration as in Example 1 except that the thickness of the negative electrode was 130 µm and the porosity of the negative electrode sheet was 34%. FIG.
Is a comparative example corresponding to the range B. (Comparative Example 3) Lithium hexafluorophosphate (LiPF 6 ) as an electrolyte was replaced with ethyl methyl carbonate (ME
C) was dissolved at 1 mol / L to prepare a non-aqueous electrolyte. The viscosity of the non-aqueous electrolyte having the above composition was measured at 20 ° C. with a rotary viscometer (manufactured by Toki Sangyo, R-type viscometer), and was 1.8.
mPa · s. η / c was 1.8. The cylindrical non-aqueous electrolyte secondary battery described above was assembled in the same configuration as in Example 1 except for the non-aqueous electrolyte. FIG. 2 is a comparative example corresponding to the range C. (Comparative Example 4) Lithium hexafluorophosphate (LiPF 6 ) as an electrolyte was dissolved in a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (MEC) (volume ratio 34:66) at 2 mol / L. A non-aqueous electrolyte was prepared. The viscosity of the nonaqueous electrolytic solution having the above composition was 9.8 mPa · s when measured at 20 ° C. with a rotary viscometer (manufactured by Toki Sangyo, R-type viscometer). η / c was 4.9.
The cylindrical non-aqueous electrolyte secondary battery described above was assembled in the same configuration as in Example 1 except for the non-aqueous electrolyte. FIG. 2 is a comparative example corresponding to the range D. (Comparative Example 5) A positive electrode similar to that of Example 1 was prepared except that the thickness of the positive electrode was 153 µm and the porosity of the positive electrode sheet was 26%.
【００３４】負極の厚みを１３０μにして、負極シート
の空隙率を３４％にした以外は実施例１と同様な負極を
作成した。A negative electrode was prepared in the same manner as in Example 1 except that the thickness of the negative electrode was 130 μm and the porosity of the negative electrode sheet was 34%.
【００３５】次に、電解質としての六フッ化リン酸リチ
ウム（ＬｉＰＦ６）を、エチレンカーボネート（Ｅ
Ｃ）、エチルメチルカーボネート（ＭＥＣ）の混合溶媒
（体積比率３４：６６）に２モル／Ｌ溶解して非水電解
液を調製した。前記組成の非水電解液の粘度は、回転式
粘度計（東機産業製、Ｒ型粘度計）で２０℃にて測定し
たところ、９．８mPa・sであった。η／ｃは４．９であ
った。前記正極と前記非水電解液以外は実施例１と同様
な構成で前述した円筒形非水電解液二次電池を組み立て
た。図２では範囲Ｅにあたる比較例である。 （比較例６）電解質としての六フッ化リン酸リチウム
（ＬｉＰＦ６）を、エチルメチルカーボネート（ＭＥ
Ｃ）に１モル／Ｌ溶解して非水電解液を調製した。前記
組成の非水電解液の粘度は、回転式粘度計（東機産業
製、Ｒ型粘度計）で２０℃にて測定したところ、１．８
mPa・sであった。η／ｃは１．８であった。前記非水電
解液以外は比較例５と同様な構成で前述した円筒形非水
電解液二次電池を組み立てた。図２では範囲Ｆにあたる
比較例である。Next, lithium hexafluorophosphate (LiPF 6 ) as an electrolyte was mixed with ethylene carbonate (E
C) and 2 mol / L in a mixed solvent of ethyl methyl carbonate (MEC) (volume ratio 34:66) to prepare a non-aqueous electrolyte. The viscosity of the nonaqueous electrolytic solution having the above composition was 9.8 mPa · s when measured at 20 ° C. with a rotary viscometer (manufactured by Toki Sangyo, R-type viscometer). η / c was 4.9. The cylindrical non-aqueous electrolyte secondary battery described above was assembled with the same configuration as in Example 1 except for the positive electrode and the non-aqueous electrolyte. FIG. 2 is a comparative example corresponding to the range E. (Comparative Example 6) Lithium hexafluorophosphate (LiPF 6 ) as an electrolyte was replaced with ethyl methyl carbonate (ME
C) was dissolved at 1 mol / L to prepare a non-aqueous electrolyte. The viscosity of the non-aqueous electrolyte having the above composition was measured at 20 ° C. with a rotary viscometer (manufactured by Toki Sangyo, R-type viscometer), and was 1.8.
mPa · s. η / c was 1.8. The cylindrical non-aqueous electrolyte secondary battery described above was assembled in the same configuration as in Comparative Example 5 except for the non-aqueous electrolyte. FIG. 2 is a comparative example corresponding to the range F.
【００３６】得られた実施例１〜５および比較例１〜６
の円筒形非水電解液二次電池について、電池容量試験と
サイクル特性試験を実施した。充電は８００ｍＡの定電
流で４．２Ｖまで行った後、定電圧で合計充電時間が５
時間になるように行った。充電、放電間の休止時間は１
０分とした。このような充放電を繰り返し行い、２サイ
クル目の放電容量を各電池の電池容量とし、この容量の
７０％に到達したサイクル数をサイクル特性を表すサイ
クル寿命とした。結果を表１に示す。The obtained Examples 1 to 5 and Comparative Examples 1 to 6
A battery capacity test and a cycle characteristic test were performed for the cylindrical non-aqueous electrolyte secondary battery. Charging was performed up to 4.2 V at a constant current of 800 mA, and the total charging time was 5 at a constant voltage.
I went to time. Pause time between charge and discharge is 1
0 minutes. Such charge / discharge was repeated, and the discharge capacity in the second cycle was defined as the battery capacity of each battery, and the number of cycles reaching 70% of this capacity was defined as the cycle life indicating the cycle characteristics. Table 1 shows the results.
【００３７】また、実施例１〜５および比較例１〜６の
円筒形非水電解液二次電池について、３２０ｍＡの電流
で放電した際の放電容量（Ｃ１）と、３２００ｍＡの電
流で放電した際の放電容量（Ｃ２）を測定し、それらの
比Ｃ２／Ｃ１の値を放電レート特性とし、表１に併記す
る。The cylindrical non-aqueous electrolyte secondary batteries of Examples 1 to 5 and Comparative Examples 1 to 6 were discharged at a current of 320 mA and a discharge capacity (C 1 ) of 3200 mA. The discharge capacity (C 2 ) at that time was measured, and the value of the ratio C 2 / C 1 was used as a discharge rate characteristic and is also shown in Table 1.
【表１】 表１から明らかなように、実施例１〜５の非水電解液二
次電池は、図２での範囲Ｂおよび範囲Ｄ〜Ｆに該当する
比較例１、２、４〜６と比べて電池容量が大きく、放電
レート特性に優れていることがわかる。また、実施例１
〜５の非水電解液二次電池は、図２での範囲Ｃ、Ｆに該
当する比較例３、６に比べてサイクル寿命が長いことが
わかる。[Table 1] As is clear from Table 1, the non-aqueous electrolyte secondary batteries of Examples 1 to 5 were compared with Comparative Examples 1, 2, and 4 to 6 corresponding to the range B and the range DF in FIG. It can be seen that the capacity is large and the discharge rate characteristics are excellent. Example 1
It can be seen that the non-aqueous electrolyte secondary batteries of Nos. To 5 have a longer cycle life than Comparative Examples 3 and 6 corresponding to ranges C and F in FIG.
【００３８】従って、空隙率２２％以下の高密度正極シ
ートおよび集電体からなる正極と、空隙率３１％以下の
高密度負極シートおよび集電体からなる負極と、粘度と
電解質濃度の比であるη／ｘが２以上４．５以下である
非水電解液を用いることによって、高い電池容量と高い
サイクル特性と高い放電レート特性を同時に達成するこ
とができたのである。Therefore, the positive electrode composed of a high-density positive electrode sheet and a current collector having a porosity of 22% or less, and the negative electrode composed of a high-density negative electrode sheet and a current collector having a porosity of 31% or less have a ratio of viscosity and electrolyte concentration. By using a non-aqueous electrolyte having a certain η / x of 2 or more and 4.5 or less, high battery capacity, high cycle characteristics, and high discharge rate characteristics could be simultaneously achieved.
【００３９】なお、前記実施例１〜５では、円筒形非水
電解液二次電池に適用した例を説明したが、有底矩形状
の容器内に正極、負極、セパレータおよび非水電解液が
収納された構造の角型非水電解液二次電池にも同様に適
用することができる。In the first to fifth embodiments, an example in which the present invention is applied to a cylindrical non-aqueous electrolyte secondary battery has been described. However, a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte are accommodated in a bottomed rectangular container. The present invention can be similarly applied to a square nonaqueous electrolyte secondary battery having a housed structure.
【００４０】[0040]
【発明の効果】以上説明したように、本発明によれば、
大容量であり、高いサイクル特性と高い放電レート特性
を同時に達成することが可能な非水電解液二次電池を提
供することができる。As described above, according to the present invention,
A non-aqueous electrolyte secondary battery having a large capacity and capable of simultaneously achieving high cycle characteristics and high discharge rate characteristics can be provided.
【図１】本発明に係る円筒形非水電解液二次電池の一例
を示す部分断面図である。FIG. 1 is a partial cross-sectional view showing an example of a cylindrical non-aqueous electrolyte secondary battery according to the present invention.
【図２】本発明の正極負極空隙率範囲を示す線図であ
る。FIG. 2 is a diagram showing a positive electrode negative electrode porosity range of the present invention.
１・・・容器、 ３・・・電極群、 ４・・・正極、 ５・・・セパレータ、 ６・・・負極、 ８・・・封口板。 DESCRIPTION OF SYMBOLS 1 ... Container, 3 ... Electrode group, 4 ... Positive electrode, 5 ... Separator, 6 ... Negative electrode, 8 ... Sealing plate.
───────────────────────────────────────────────────── フロントページの続き Ｆターム(参考） 5H003 AA02 AA04 BB01 BB05 BB14 BC01 BC04 BD00 BD01 BD02 BD06 5H014 AA02 AA06 EE01 EE10 HH00 HH02 HH06 HH08 5H029 AJ03 AK03 AL06 AL07 AM02 AM03 AM05 AM07 BJ02 BJ14 CJ03 DJ04 DJ07 DJ08 DJ13 HJ02 HJ05 HJ09 HJ10 HJ14 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 5H003 AA02 AA04 BB01 BB05 BB14 BC01 BC04 BD00 BD01 BD02 BD06 5H014 AA02 AA06 EE01 EE10 HH00 HH02 HH06 HH08 5H029 AJ03 AK03 AL06 AL07 AM02 AM03 AM05 AM07 DJ02 DJ07 DJ04 HJ05 HJ09 HJ10 HJ14
Claims (1)
y（Ｍ、ＸはＣｏ，Ｎｉ，Ｍｎのうちいずれかを表わ
す、ＹはＦ、Ｎのうちいずれかを表わす，０＜ｘ≦１、
０＜ｙ≦１）で表わされるリチウム複合金属酸化物であ
り、平均粒径が１μｍから５０μｍの粉体を正極活物質
とし、導電剤等をあわせてシート状に成形した空隙率２
２％以下の高密度正極シートおよび集電体からなる正極
と、リチウムを吸蔵放出することのできる炭素質物を負
極活物質としてシート状に成形した空隙率３１％以下の
高密度負極シートおよび集電体からなる負極と、前記正
極と前記負極の間に多孔性のセパレータを介在させて構
成した電極群と、有機溶媒と電解質を含有する非水電解
液を具備してなる非水電解液二次電池であって、前記非
水電解液の２０℃における粘度η（mPa・s）と電解質濃
度ｘ（モル／Ｌ）の比η／ｘが２以上４．５以下である
ことを特長とする非水電解液二次電池。1. Formula LiM (1-x) X x O 2-y Y
y (M, X represents any one of Co, Ni, Mn, Y represents any one of F, N, 0 <x ≦ 1,
0 <y ≦ 1), a powder having an average particle diameter of 1 μm to 50 μm as a positive electrode active material, and a porosity of 2 formed into a sheet by combining a conductive agent and the like.
A positive electrode comprising a high-density positive electrode sheet and a current collector of 2% or less, and a high-density negative electrode sheet having a porosity of 31% or less and formed into a sheet using a carbonaceous material capable of inserting and extracting lithium as a negative electrode active material and a current collector And a non-aqueous electrolyte secondary solution comprising a non-aqueous electrolyte solution containing an organic solvent and an electrolyte, and an electrode group formed by interposing a porous separator between the positive electrode and the negative electrode. A battery characterized in that the ratio η / x of the viscosity η (mPa · s) at 20 ° C. to the electrolyte concentration x (mol / L) of the nonaqueous electrolyte is 2 or more and 4.5 or less. Water electrolyte secondary battery.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10372464A JP2000195550A (en) | 1998-12-28 | 1998-12-28 | Nonaqueous electrolyte secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10372464A JP2000195550A (en) | 1998-12-28 | 1998-12-28 | Nonaqueous electrolyte secondary battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2000195550A true JP2000195550A (en) | 2000-07-14 |
Family
ID=18500491
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10372464A Pending JP2000195550A (en) | 1998-12-28 | 1998-12-28 | Nonaqueous electrolyte secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2000195550A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002110233A (en) * | 2000-09-29 | 2002-04-12 | Toshiba Corp | Non-aqueous electrolyte secondary battery |
| JP2002319433A (en) * | 2001-02-15 | 2002-10-31 | Mitsubishi Chemicals Corp | Nonaqueous electrolyte secondary cell and nonaqueous electrolytic solution used for the same |
| JP2003086180A (en) * | 2001-09-11 | 2003-03-20 | Masayuki Yoshio | Positive electrode active material of nonaqueous electrolyte secondary battery and secondary battery using it |
| WO2005011028A1 (en) * | 2003-07-28 | 2005-02-03 | Showa Denko K.K. | High density electrode and battery using the electrode |
| JP2010225366A (en) * | 2009-03-23 | 2010-10-07 | Sanyo Electric Co Ltd | Nonaqueous electrolyte secondary battery |
| JP2011065842A (en) * | 2009-09-16 | 2011-03-31 | Nissan Motor Co Ltd | Electrolyte for lithium secondary battery, and bipolar secondary battery using the same |
| US8298707B2 (en) | 2000-12-28 | 2012-10-30 | Sony Corporation | Positive active material and nonaqueous electrolyte secondary battery |
-
1998
- 1998-12-28 JP JP10372464A patent/JP2000195550A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002110233A (en) * | 2000-09-29 | 2002-04-12 | Toshiba Corp | Non-aqueous electrolyte secondary battery |
| US8298707B2 (en) | 2000-12-28 | 2012-10-30 | Sony Corporation | Positive active material and nonaqueous electrolyte secondary battery |
| JP2002319433A (en) * | 2001-02-15 | 2002-10-31 | Mitsubishi Chemicals Corp | Nonaqueous electrolyte secondary cell and nonaqueous electrolytic solution used for the same |
| JP2003086180A (en) * | 2001-09-11 | 2003-03-20 | Masayuki Yoshio | Positive electrode active material of nonaqueous electrolyte secondary battery and secondary battery using it |
| WO2005011028A1 (en) * | 2003-07-28 | 2005-02-03 | Showa Denko K.K. | High density electrode and battery using the electrode |
| JP2010225366A (en) * | 2009-03-23 | 2010-10-07 | Sanyo Electric Co Ltd | Nonaqueous electrolyte secondary battery |
| JP2011065842A (en) * | 2009-09-16 | 2011-03-31 | Nissan Motor Co Ltd | Electrolyte for lithium secondary battery, and bipolar secondary battery using the same |
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