JPH1145738A - Lithium secondary battery and its manufacture - Google Patents
Lithium secondary battery and its manufactureInfo
- Publication number
- JPH1145738A JPH1145738A JP10144102A JP14410298A JPH1145738A JP H1145738 A JPH1145738 A JP H1145738A JP 10144102 A JP10144102 A JP 10144102A JP 14410298 A JP14410298 A JP 14410298A JP H1145738 A JPH1145738 A JP H1145738A
- Authority
- JP
- Japan
- Prior art keywords
- secondary battery
- lithium secondary
- active material
- battery according
- material layer
- 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
-
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Landscapes
- Cell Electrode Carriers And Collectors (AREA)
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
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
関する。更に詳しくは、従来の液体状電解質に代えて、
ポリマー電解質(電解質をポリマーに含浸又は保持され
たものも含む)を用いたリチウム二次電池に関し、サイ
クル特性に優れ、外部からの圧力、曲げに対して耐えう
る優れたリチウム二次電池に関する。[0001] The present invention relates to a lithium secondary battery. More specifically, instead of the conventional liquid electrolyte,
The present invention relates to a lithium secondary battery using a polymer electrolyte (including one in which an electrolyte is impregnated or held in a polymer), and relates to an excellent lithium secondary battery that has excellent cycle characteristics and can withstand external pressure and bending.
【0002】[0002]
【従来の技術】近年、カメラ一体型VTR装置、オーデ
ィオ機器、携帯型コンピュータ、携帯電話等様々な機器
の小型化、軽量化が進んでおり、これら機器の電源とし
ての電池に対する高性能化要請が高まっている。中でも
電気自動車の動力源としての電池として高電圧、高エネ
ルギー密度で、且つ優れたサイクル特性の実現が可能な
リチウム二次電池の開発が盛んになっている。2. Description of the Related Art In recent years, various devices such as a camera-integrated VTR device, an audio device, a portable computer, and a cellular phone have been reduced in size and weight, and there has been a demand for higher performance of a battery as a power supply for these devices. Is growing. Above all, development of lithium secondary batteries capable of achieving high voltage, high energy density and excellent cycle characteristics as batteries as power sources for electric vehicles has been active.
【0003】リチウム二次電池は概ね、リチウムイオン
を吸蔵放出可能な正極及び負極、並びに非水電解質液と
からなっており、例えば正極にコバルト酸リチウムを含
む電極、負極に炭素材料を含む電極、及び電解質液を用
いた二次電池の場合には、充電中に正極中からリチウム
イオンが電解液を介して負極中に吸蔵され、放電時には
負極中からリチウムイオンが放出され電解液を介して正
極中に吸蔵されるというものである。この電極に要求さ
れる特性として、電極へのリチウムイオンの吸蔵能力及
び放出能力が大きく、これら吸蔵・放出の繰り返し(サ
イクル)による各能力の低下を抑えることである。A lithium secondary battery generally comprises a positive electrode and a negative electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolyte solution. For example, an electrode containing lithium cobalt oxide for the positive electrode, an electrode containing a carbon material for the negative electrode, And in the case of a secondary battery using an electrolyte solution, lithium ions are occluded in the negative electrode through the electrolyte solution during charging while the lithium ions are released from the negative electrode through the electrolyte solution during discharge and the positive electrode is discharged through the electrolyte solution. It is to be absorbed inside. As a characteristic required for this electrode, the ability to occlude and release lithium ions to and from the electrode is large, and it is necessary to suppress a decrease in each ability due to the repetition (cycle) of occlusion and release.
【0004】このような優れたリチウム二次電池の正極
に要求される特性としては正極層内での導電性が挙げら
れる。正極に用いる、リチウムイオンを吸蔵放出可能な
化合物は導電性が殆ど無い酸化物を用いることが多く、
これのみでは正極として機能しないので、通常炭素等の
導電性物質を用いて導電性を付与し、正極として用いて
いる。又、電解液としては従来、高電圧を得る為に非水
系の電解液が用いられてきた。一方、非水系電解液を用
いた際には液状であるが故に濾液、これに伴なう発火の
危険を有していることから、近年では安全性を向上させ
るために非水電解液を、例えばゲル状ポリマーに含浸又
は保持させたものや、ポリマー自体が電解質として働
く、いわゆるポリマー電解質の開発が行われている。The characteristics required for the positive electrode of such an excellent lithium secondary battery include conductivity in the positive electrode layer. Compounds that can store and release lithium ions used for the positive electrode often use oxides with little conductivity,
Since this alone does not function as a positive electrode, it is generally used as a positive electrode by imparting conductivity using a conductive substance such as carbon. Conventionally, non-aqueous electrolytes have been used to obtain high voltage. On the other hand, when a non-aqueous electrolyte is used, the filtrate is in a liquid state and therefore has a danger of ignition accompanying it.In recent years, a non-aqueous electrolyte has been used to improve safety. For example, a so-called polymer electrolyte in which a gel polymer is impregnated or held or a polymer itself functions as an electrolyte has been developed.
【0005】特にリチウム二次電池においては電解質液
を用いた際に生ずるリチウムのデンドライト析出による
内部短絡による発熱、発火が問題となっており、優れた
ポリマー電解質の開発とその応用が望まれていた。さら
に上述のポリマー電解質は、それ自体が二次電池系で使
用されるセパレーターの代用を勤めることが可能となる
ので、従来のようにセパレータを用いずとも、このポリ
マー電解質を挟んで正極と負極を接合させることで電池
を構成できる。この様にポリマー電解質を用いることで
軽量、形状柔軟性が向上するので、例えばシート状の如
き薄膜化が可能であり、軽量、省スペースな電池が作成
可能となる有利な点がある。また、ポリマー電解質は、
電池の内部抵抗低下やエネルギー密度向上のため、内部
短絡をしない範囲で、薄いことが望まれている。In particular, in a lithium secondary battery, heat generation and ignition due to an internal short circuit due to lithium dendrite deposition when an electrolyte solution is used poses a problem, and development and application of an excellent polymer electrolyte have been desired. . Further, since the above-mentioned polymer electrolyte itself can serve as a substitute for a separator used in a secondary battery system, a positive electrode and a negative electrode can be sandwiched between the polymer electrolyte without using a separator as in the related art. A battery can be formed by joining. By using a polymer electrolyte in this way, the weight and shape flexibility are improved, so that, for example, a thin film such as a sheet can be formed, and there is an advantage that a lightweight and space-saving battery can be manufactured. Also, the polymer electrolyte is
To reduce the internal resistance of the battery and improve the energy density, it is desired that the battery be as thin as possible without causing an internal short circuit.
【0006】[0006]
【発明が解決しようとする課題】ポリマー電解質は電極
の活物質層上に設けるが、この際、ポリマー電解質が活
物質層内に含浸したり、又、独立に層を形成する場合等
がある。ポリマー電解質としてゲルのごとき機械的強度
の弱いものを用いる際には、特にポリマー電解質を薄膜
化した場合に、ポリマー電解質層と接する正極又は負極
の活物質層表面が荒れていると外部からのわずかな圧力
でも正負極の内部短絡の原因となったり、電流の集中の
ためデンドライトの発生の起点となり、サイクル特性を
劣化させるという問題があった。また、活物質表面を完
全に平坦にしてしまうと、ポリマー電解質層との接着性
が低下し、容易に剥離を招き、ポリマー電池の特徴たる
可撓性を損なうという問題があった。The polymer electrolyte is provided on the active material layer of the electrode. In this case, the polymer electrolyte may be impregnated in the active material layer or may be formed independently. When using a polymer electrolyte having low mechanical strength such as gel, especially when the polymer electrolyte is thinned, if the surface of the active material layer of the positive electrode or the negative electrode in contact with the polymer electrolyte layer is rough, a small amount of Even at a high pressure, internal short-circuiting between the positive and negative electrodes may occur, or the concentration of current may cause the generation of dendrite, deteriorating the cycle characteristics. Further, if the surface of the active material is completely flattened, there is a problem that the adhesiveness to the polymer electrolyte layer is reduced, the separation is easily caused, and the characteristic flexibility of the polymer battery is impaired.
【0007】[0007]
【課題を解決するための手段】本発明は上記実状に鑑み
て為されたものであり、サイクル特性に優れたリチウム
二次電池を得るために鋭意検討した結果、正極、負極の
活物質層表面粗度を特定範囲にすることにより、又、さ
らにはポリマー電解質層の表面粗度を特定範囲とするこ
とにより、内部短絡しにくく、且つサイクル特性のよ
い、可撓性に優れたリチウム二次電池を得られることを
見いだし、完成したものである。DISCLOSURE OF THE INVENTION The present invention has been made in view of the above situation, and as a result of intensive studies to obtain a lithium secondary battery having excellent cycle characteristics, it has been found that the surface of the active material layer of the positive electrode and the negative electrode has By setting the roughness to a specific range, and furthermore, by setting the surface roughness of the polymer electrolyte layer to a specific range, an internal short circuit is hard to occur, and a lithium secondary battery having excellent cycle characteristics and excellent flexibility is provided. It is found that it can be obtained and is completed.
【0008】[0008]
【発明の実施の形態】以下に、本発明を詳細に説明す
る。本発明でいう表面粗度とは、任意の方法で算出でき
るが例えば、非接触もしくは接触式の表面粗度計を用い
て測定された粗さ曲線から求めることができる。また、
例えばポリマー電解質層の活物質層との接触面の表面粗
度とは、界面を剥離し、表面粗度として測定しても良い
し、あるいは、切断面をSEM等の顕微鏡により観察
し、粗さ曲線を求め、算出してもよい。Rp、Rvにつ
いては、例えば上述の如き方法により得られた粗さ曲線
より、最小二乗法を用いて平均線を求める。Rp値(平
均線高さ)とは、平均線と粗さ曲線の最高山頂の間隔、
また、Rv値(平均線深さ)とは、平均線と最深谷底の
間隔である。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The surface roughness referred to in the present invention can be calculated by any method. For example, it can be determined from a roughness curve measured using a non-contact or contact type surface roughness meter. Also,
For example, the surface roughness of the contact surface between the polymer electrolyte layer and the active material layer may be measured by measuring the surface roughness by peeling off the interface or by observing the cut surface with a microscope such as an SEM. A curve may be obtained and calculated. As for Rp and Rv, for example, an average line is obtained from the roughness curves obtained by the above-described method using the least square method. The Rp value (average line height) is the distance between the average line and the highest peak of the roughness curve,
The Rv value (average line depth) is the distance between the average line and the deepest valley bottom.
【0009】本発明においては、正、負極における活物
質表面のRp値が0.1μm〜20μmであり、Rv値
は0.1μm〜50μmであることが好ましい。Rp値
は、特に1〜10μmとすることが好ましい。Rp値が
20μmを超えると、電池が内部短絡を起こしやすくな
ったり、局部的な電流集中によるサイクル特性の低下
や、デンドライトの発生につながることがある。また、
0.1μmに満たないとポリマー電解質との接着性が低
下し、電池の可撓性を損なうことがある。また、Rv値
は、特に、1μm〜20μmであることが好ましい。R
v値が50μmを超えると電池の容量低下につながり、
0.1μmに満たないと、ポリマー電解質との接着性に
悪影響を与えることがある。In the present invention, the Rp value of the active material surface of the positive and negative electrodes is preferably 0.1 μm to 20 μm, and the Rv value is preferably 0.1 μm to 50 μm. The Rp value is particularly preferably 1 to 10 μm. When the Rp value exceeds 20 μm, the battery may easily cause an internal short circuit, the cycle characteristics may be deteriorated due to local current concentration, or dendrite may be generated. Also,
If the thickness is less than 0.1 μm, the adhesion to the polymer electrolyte may be reduced, and the flexibility of the battery may be impaired. Further, the Rv value is particularly preferably 1 μm to 20 μm. R
If the v value exceeds 50 μm, the capacity of the battery decreases,
If the thickness is less than 0.1 μm, the adhesiveness to the polymer electrolyte may be adversely affected.
【0010】さらに、本発明においては、ポリマー電解
質層が活物質層とは独立して層を形成する際に、ポリマ
ー電解質層の活物質層との接触面のRp値が0.1μm
〜50μm、Rv値が0.1μm〜20μmであること
が好ましい。Rp値は、特に1〜10μmであることが
好ましい。Rp値が50μmを超えると、電池の容量低
下につながることがあり、0.1μmに満たないと、電
解質との接着性に悪影響を与えることがある。Rv値
は、特に1μm〜10μmとすることが好ましい。Rv
値が20μmを超えると、電池が内部短絡を起こしやす
くなったり、局部的な電流集中を起こし、サイクル特性
の低下や、デンドライト発生につながることがある。ま
た、0.1μmに満たないと、正、負極活物質層との接
着性が低下し、電池の可撓性を損なうことがある。Further, in the present invention, when the polymer electrolyte layer is formed independently of the active material layer, the Rp value of the contact surface of the polymer electrolyte layer with the active material layer is 0.1 μm.
It is preferable that the Rv value is 0.1 μm to 20 μm. The Rp value is particularly preferably 1 to 10 μm. If the Rp value exceeds 50 μm, the capacity of the battery may be reduced. If the Rp value is less than 0.1 μm, the adhesiveness to the electrolyte may be adversely affected. The Rv value is particularly preferably 1 μm to 10 μm. Rv
When the value exceeds 20 μm, the battery is likely to cause an internal short circuit or local current concentration, which may lead to a decrease in cycle characteristics and dendrite generation. On the other hand, when the thickness is less than 0.1 μm, the adhesiveness to the positive and negative electrode active material layers is reduced, and the flexibility of the battery may be impaired.
【0011】本発明のリチウム二次電池においてはこの
ように電極活物質層やポリマー電解質層表面の粗さを特
定範囲とすることで、特にポリマー電解質(層)の厚さ
を50μm以下とした薄膜化されたリチウム二次電池に
おいても好適なものが得られるのである。ポリマー電解
質(層)の厚さは任意であるが、通常、10〜50μm
である。In the lithium secondary battery of the present invention, by setting the surface roughness of the electrode active material layer and the surface of the polymer electrolyte layer to a specific range, the thickness of the polymer electrolyte (layer) is particularly reduced to 50 μm or less. Suitable lithium secondary batteries can also be obtained. Although the thickness of the polymer electrolyte (layer) is arbitrary, it is usually 10 to 50 μm.
It is.
【0012】また、このようなRpと短絡との関係は電
解質厚さにも依存する。近年、エネルギー密度に対する
向上要求は高まってきており、電解質層の平均厚さ
(d)と活物質層表面の平均線高さ(Rp)と、電池特
性の関係を検討した結果、Rp/dが0.3以下、中で
も0.3〜0.002、特に0.25〜0.05であれ
ば、収率よく良好な特性が得られることを見い出した。
Rp/dが0.3をこえると、局部的な電流集中により
3700mV以上の高電位部でデンドライトの発生によ
る短縮を生じたり、大電流充放電において、サイクル特
性の低下をひきおこす原因となるのである。The relationship between Rp and the short circuit also depends on the thickness of the electrolyte. In recent years, the demand for improvement in energy density has been increasing, and as a result of examining the relationship between the average thickness (d) of the electrolyte layer, the average line height (Rp) of the active material layer surface, and the battery characteristics, Rp / d was found to be It has been found that good properties can be obtained with good yield when the ratio is 0.3 or less, especially 0.3 to 0.002, particularly 0.25 to 0.05.
If Rp / d exceeds 0.3, local current concentration may cause shortening due to generation of dendrite in a high potential portion of 3700 mV or more, or cause deterioration of cycle characteristics in large current charging / discharging. .
【0013】本発明のリチウム二次電池は正極、負極及
びポリマー電解質を主たる構成要件とする。まず本発明
のリチウム二次電池における電極について説明する。一
般的に、リチウム二次電池における正極や負極は、アル
ミニウム箔や銅箔の様な集電体上に正極(負極)活物
質、結合樹脂(バインダー)、導電材料及び溶媒等を含
有する電極の活物質層を形成する塗料を塗布、乾燥して
製造する。[0013] The lithium secondary battery of the present invention mainly comprises a positive electrode, a negative electrode and a polymer electrolyte. First, the electrodes in the lithium secondary battery of the present invention will be described. In general, a positive electrode or a negative electrode in a lithium secondary battery is formed of an electrode containing a positive electrode (negative electrode) active material, a binder resin (binder), a conductive material, a solvent, and the like on a current collector such as an aluminum foil or a copper foil. It is manufactured by applying and drying a paint for forming an active material layer.
【0014】本発明における正極に用いる活物質であ
る、リチウムイオンを吸蔵放出可能な化合物としては、
無機化合物としてはFe、Co、Ni、Mn等の遷移金
属の遷移金属酸化物、リチウムと遷移金属との複合酸化
物、遷移金属硫化物等が挙げられる。具体的には、Mn
O、V2 O5 、V6 O13、TiO2 等の遷移金属酸化物
粉末、ニッケル酸リチウム、コバルト酸リチウムなどの
リチウムと遷移金属との複合酸化物粉末、TiS2 、F
eSなどの遷移金属硫化物粉末等が挙げられる。有機化
合物としては、例えばポリアニリン等の導電性ポリマー
等が挙げられる。又、これら無機化合物、有機化合物を
任意の割合で混合しても良い。As the active material used for the positive electrode in the present invention, compounds capable of inserting and extracting lithium ions include:
Examples of the inorganic compound include a transition metal oxide of a transition metal such as Fe, Co, Ni, and Mn, a composite oxide of lithium and a transition metal, and a transition metal sulfide. Specifically, Mn
Transition metal oxide powders such as O, V 2 O 5 , V 6 O 13 and TiO 2 ; composite oxide powders of lithium and transition metal such as lithium nickelate and lithium cobalt oxide; TiS 2 , F
Transition metal sulfide powders such as eS are exemplified. Examples of the organic compound include a conductive polymer such as polyaniline. Further, these inorganic compounds and organic compounds may be mixed at an arbitrary ratio.
【0015】負極活物質材料としては、Li金属箔の他
にリチウムイオンを吸蔵放出可能な化合物としてグラフ
ァイトやコークス等を用いるが、特に安全性の面からコ
ークスが好ましい。これら正極、負極の活物質の粒径は
電池のその他の構成要件とのかねあいで適宜選択すれば
よいが、通常、平均粒径1〜30μm、特に1〜10、
中でも3〜8μmとすることで、請求項記載の表面粗度
が得られやすくなる。さらには、空隙率を容易に制御す
ることが可能であるという効果があるので好ましい。As the negative electrode active material, graphite or coke is used as a compound capable of inserting and extracting lithium ions in addition to the Li metal foil. Coke is particularly preferable from the viewpoint of safety. The particle size of the active material of the positive electrode and the negative electrode may be appropriately selected in consideration of other components of the battery, but is usually 1 to 30 μm in average particle size, particularly 1 to 10 μm,
In particular, when the thickness is 3 to 8 μm, the surface roughness described in the claims can be easily obtained. Further, it is preferable because the porosity can be easily controlled.
【0016】バインダーとしては、電解液等に対して安
定である必要があり耐候性、耐薬品性、耐熱性、難燃性
等が望まれる。さらにイオン伝導性に優れた材料が望ま
しく例えば架橋性のポリエチレンオキシド樹脂等が挙げ
られる。さらに好ましくは、ポリエチレンオキシド樹脂
末端にアクリル基、メタアクリル基等を導入し熱や紫外
線等により架橋させたものが好ましい。The binder must be stable with respect to an electrolytic solution or the like, and is desired to have weather resistance, chemical resistance, heat resistance, flame retardancy, and the like. Further, a material having excellent ion conductivity is desirable, and examples thereof include a cross-linkable polyethylene oxide resin. More preferably, those obtained by introducing an acryl group, a methacryl group, or the like into the terminal of the polyethylene oxide resin and cross-linking by heat, ultraviolet light, or the like are preferable.
【0017】導電性物質としては、リチウムを吸蔵放出
可能な化合物粉末に適量混合して導電性を付与できるも
のであれば特に制限は無いが、アセチレンブラック、カ
ーボンブラック、黒鉛などの炭素粉末や、使用する電極
電位で安定な金属粉末などが挙げられる。これら導電性
物質のDBP吸油量は100〜500cc/100g、
特に150〜300cc/100gが好ましい。又、平
均粒径は1〜100〔nm〕、特に10〜50〔nm〕
が好ましい。活物質と導電性物質との重量比は、98/
2〜90/10の範囲が好ましい。The conductive substance is not particularly limited as long as it can impart conductivity by mixing an appropriate amount of compound powder with a compound powder capable of inserting and extracting lithium, but carbon powder such as acetylene black, carbon black, and graphite; Metal powders that are stable at the electrode potential to be used are exemplified. The DBP oil absorption of these conductive substances is 100 to 500 cc / 100 g,
Particularly, 150 to 300 cc / 100 g is preferable. The average particle size is 1 to 100 [nm], particularly 10 to 50 [nm].
Is preferred. The weight ratio between the active material and the conductive material is 98 /
A range of 2 to 90/10 is preferred.
【0018】正極を形成する塗料の溶媒としては、前記
バインダーを分散、溶解可能で、且つ容易に乾燥するも
のが好ましい。例えばアクリロニトリル、ジメチルカー
ボネート等が挙げられる。正極の集電体としては、一般
的にアルミ箔を用いる。負極の集電体としては、銅箔を
用いる。これら集電体においては、活物質層を設ける表
面を予め粗面化処理を行うと結着効果が高くなるので好
ましい。表面の粗面化方法としては、機械的研磨法、電
解研磨法または化学研磨法が挙げられる。機械的研磨法
としては、研磨剤粒子を固着した研磨布紙、砥石、エメ
リバフ、鋼線などを備えたワイヤーブラシなどで集電体
表面を研磨する方法が挙げられる。As the solvent of the coating material for forming the positive electrode, those which can disperse and dissolve the binder and easily dry are preferable. For example, acrylonitrile, dimethyl carbonate and the like can be mentioned. Generally, an aluminum foil is used as the current collector of the positive electrode. A copper foil is used as a current collector of the negative electrode. In these current collectors, it is preferable that the surface on which the active material layer is provided be roughened in advance, since the binding effect will be increased. Examples of the surface roughening method include a mechanical polishing method, an electrolytic polishing method, and a chemical polishing method. Examples of the mechanical polishing method include a method of polishing the surface of the current collector with a polishing cloth paper having abrasive particles fixed thereon, a grindstone, an emery buff, a wire brush provided with a steel wire, or the like.
【0019】集電体への正極及び負極の形成方法は、特
に限定されるものではないが、塗料の粘度が高いことか
らコンマリバースコート、スクイーズコート、リップコ
ート等の塗布方式を用いるのが好ましい。正極及び負極
の各活物質層の厚み(平均厚さ)は夫々通常、20〜2
00μm程度である。正、負極における活物質層の表面
粗度をコントロールするためには、活物質粒子径を変え
たり、活物質層形成塗料を基材上に塗布・乾燥した後、
塗膜にプレス処理をする方法や塗料の溶媒の種類、量を
制御するという種々の方法が有る。例えば、正、負極の
活物質層を集電体上に形成した後に、圧力を1〜500
0〔kg/cm2 〕、好ましくは1〜1000〔kg/
cm2 〕、温度を室温〜200〔℃〕、好ましくは室温
〜150〔℃〕でカレダーにより圧力をかけることで成
し得る。The method for forming the positive electrode and the negative electrode on the current collector is not particularly limited, but it is preferable to use a coating method such as a converse coat, a squeeze coat, and a lip coat because of the high viscosity of the paint. . The thickness (average thickness) of each active material layer of the positive electrode and the negative electrode is usually 20 to 2 respectively.
It is about 00 μm. To control the surface roughness of the active material layer in the positive and negative electrodes, change the active material particle size, or apply and dry the active material layer forming paint on the substrate,
There are various methods of pressing the coating film and controlling the type and amount of the solvent of the paint. For example, after forming the positive and negative electrode active material layers on the current collector, the pressure is increased to 1 to 500.
0 [kg / cm 2 ], preferably 1 to 1000 [kg / cm 2 ]
cm 2 ] at a temperature of room temperature to 200 ° C., preferably room temperature to 150 ° C., by applying pressure with a calender.
【0020】次に、ポリマー電解質について説明する。
ポリマー電解質としては、それ自体電解質を構成するも
のであってもよく、ゲル状ポリマー中に電解液を含有す
るものであっもよいが、後者の場合には、一般的にはゲ
ル状ポリマーに含有させる電解液は非水電解液が好適で
あり、これは非水溶媒に電解質を溶解させたものを用い
るのが一般的である。Next, the polymer electrolyte will be described.
The polymer electrolyte may itself constitute an electrolyte, or may contain an electrolyte solution in a gel polymer, but in the latter case, it is generally contained in a gel polymer. The electrolytic solution to be used is preferably a non-aqueous electrolytic solution, which is generally obtained by dissolving an electrolyte in a non-aqueous solvent.
【0021】ポリマー電解質作成に用いる電解質として
は、電解質として正極活物質及び負極活物質に対して安
定であり、且つリチウムイオンが前記正極活物質あるい
は負極活物質と電気化学反応をするための移動を行い得
るものであればいずれのものでも使用することができ
る。具体的にはLiPF6 、LiAsF6 、LiSbF
6 、LiBF4 、LiClO4 、LiI、LiBr、L
iCl、LiAlCl、LiHF2 、LiSCN、Li
SO3 CF2 等が挙げられる。これらのうちでは特にL
iPF6 、LiClO4 が好ましい。As the electrolyte used for preparing the polymer electrolyte, the electrolyte is stable with respect to the positive electrode active material and the negative electrode active material, and transfers lithium ions for performing an electrochemical reaction with the positive electrode active material or the negative electrode active material. Anything that can be performed can be used. LiPF 6 in particular, LiAsF 6, LiSbF
6 , LiBF 4 , LiClO 4 , LiI, LiBr, L
iCl, LiAlCl, LiHF 2 , LiSCN, Li
SO 3 CF 2 and the like. Among these, L
iPF 6 and LiClO 4 are preferred.
【0022】これら電解質の電解液における含有量は、
一般的に0.5〜2.5mol/lである。この電解質
を溶解する溶媒は特に限定されないが、比較的高誘電率
の溶媒が好適に用いられる。具体的にはエチレンカーボ
ネート、プロピレンカーボネート等の環状カーボネート
類、ジメチルカーボネート、ジエチルカーボネート、エ
チルメチルカーボネートなどの非環状カーボネート類、
テトラヒドロフラン、2−メチルテトラヒドロフラン、
ジメトキシエタン等のエーテル類、γ−ブチルラクトン
等のラクトン類、スルフォラン等の硫黄化合物、アセト
ニトリル等のニトリル類が挙げられる。又、これらの2
種以上を、任意の割合で混合して用いてもよい。これら
の中でも特にエチレンカーボネート、プロピレンカーボ
ネート等の環状カーボネート類、ジメチルカーボネー
ト、ジエチルカーボネート、エチルメチルカーボネート
などの非環状カーボネート類から選ばれた1種又は任意
の割合からなる2種以上の混合溶液が好ましい。The content of these electrolytes in the electrolyte is as follows:
Generally, it is 0.5 to 2.5 mol / l. The solvent for dissolving the electrolyte is not particularly limited, but a solvent having a relatively high dielectric constant is preferably used. Specifically, ethylene carbonate, cyclic carbonates such as propylene carbonate, dimethyl carbonate, diethyl carbonate, non-cyclic carbonates such as ethyl methyl carbonate,
Tetrahydrofuran, 2-methyltetrahydrofuran,
Examples include ethers such as dimethoxyethane, lactones such as γ-butyl lactone, sulfur compounds such as sulfolane, and nitriles such as acetonitrile. In addition, these 2
Species or more may be mixed and used in an arbitrary ratio. Among these, ethylene carbonate, cyclic carbonates such as propylene carbonate, dimethyl carbonate, diethyl carbonate, and a mixture of two or more kinds of arbitrary ratios selected from an acyclic carbonate such as ethyl methyl carbonate are preferable. .
【0023】ポリマー電解質は、電解質溶解液をゲルを
形成するポリマー、例えばポリエチレンオキサイド、ポ
リプロピレンオキサイド、ポリエチレンオキサイドのイ
ソシアネート架橋体、フェニレンオキシド、フェニレン
スルフィド系ポリマー等の重合体に含浸させゲル状のポ
リマー電解質を作成する。必要に応じてアクリル基など
重合性の官能基を持つ化合物を電解質溶液と混合し、U
Vなどのエネルギー線を照射し重合したり、混合物を熱
により重合させて、ポリマー電解質を得てもよい。電解
質の電解質溶解液における含有量は一般に0.5〜2.
5mol/lである。また、この場合のゲルを構成する
ポリマーの強度としてはピン刺し強度<1mmφ0.5
rの球面座圧触試験として通常1〜50g・F程度のも
のが用いられる。なお、補強材として、不織布あるいは
多孔質膜等を組合せて用いてもよく、この場合の前記ピ
ン刺し強度としては、100〜500g・F程度であ
る。The polymer electrolyte is prepared by impregnating the electrolyte solution with a gel-forming polymer, for example, a polymer such as polyethylene oxide, polypropylene oxide, a crosslinked isocyanate of polyethylene oxide, phenylene oxide, or a phenylene sulfide polymer. Create If necessary, a compound having a polymerizable functional group such as an acrylic group is mixed with the electrolyte solution,
A polymer electrolyte may be obtained by irradiating an energy ray such as V and polymerizing the mixture, or by polymerizing the mixture by heat. The content of the electrolyte in the electrolyte solution is generally 0.5 to 2.
5 mol / l. The strength of the polymer constituting the gel in this case was as follows: pin piercing strength <1 mmφ0.5
As the spherical contact pressure test for r, a test of about 1 to 50 g · F is usually used. In addition, a nonwoven fabric or a porous film may be used in combination as a reinforcing material. In this case, the pin piercing strength is about 100 to 500 g · F.
【0024】ポリマー電解質層を形成する塗料の粘度は
塗工方法や塗料形成材料にもよるが、10000cp以
下とするのが好ましい。この範囲であれば、正、負極の
活物質層表面の凹凸に電解質を容易に入り込ませること
ができるので、電解質層の表面粗度、正極負極層との界
面粗度は、接触している正極負極層の表面粗度を逆に写
し取った大きさとなる。即ち、活物質層表面のRp、R
v値がこの表面に接触するポリマー電解質層表面のR
v、Rp値となるので好ましい。また、逆に電解質溶液
の粘度が100000cpを超えるような高粘度の場
合、容易に正、負極の活物質層表面の凹凸になじまない
ことがある。The viscosity of the coating material for forming the polymer electrolyte layer is preferably 10,000 cp or less, depending on the coating method and the coating material. Within this range, the electrolyte can easily penetrate into the unevenness of the active material layer surfaces of the positive and negative electrodes, so that the surface roughness of the electrolyte layer and the interface roughness with the positive and negative electrode layers are The size is obtained by reversely copying the surface roughness of the negative electrode layer. That is, Rp, R on the surface of the active material layer
The v value is the R of the surface of the polymer electrolyte layer in contact with this surface.
v and Rp are preferable. On the other hand, when the viscosity of the electrolyte solution is higher than 100000 cp, the positive and negative electrode active material layers may not easily conform to the irregularities on the surface.
【0025】本発明の特徴は上述した如く、ポリマー電
解質を用いたリチウム二次電池において正、負極の活物
質層、ポリマー電解質層の表面を特定範囲とすることに
よりサイクル特性や外部からの圧力による曲げ等の変形
に強く、カード型等の薄膜化二次電池を提供することが
可能となる。以下、本発明を具体的に説明する。As described above, the feature of the present invention is that, in a lithium secondary battery using a polymer electrolyte, the surface of the active material layer of the positive and negative electrodes and the surface of the polymer electrolyte layer are set to a specific range, whereby the cycle characteristics and the external pressure are reduced. It is possible to provide a thin-film secondary battery such as a card type which is resistant to deformation such as bending. Hereinafter, the present invention will be described specifically.
【0026】以下に実施例を示し、本発明を更に具体的
に説明するが、本発明はその要旨を越えない限り、以下
に示す実施例に制限されるものではない。 実施例1 以下に示す組成に従い正極用塗料を作成しアルミ基材上
に塗布してリチウム二次電池用の正極とし評価した。正
極用塗料の原料としては以下のものを使用した。The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples unless it exceeds the gist of the present invention. Example 1 A coating material for a positive electrode was prepared according to the composition shown below, and applied to an aluminum substrate to evaluate a positive electrode for a lithium secondary battery. The following materials were used as the raw materials for the positive electrode paint.
【0027】 正極活物資材 LiCoO2 平均粒径:5μm(FMC社製) 導電材 アセチレンブラック 平均粒径:40nm(電気化学工業製) バインダー Photomer4050(Henkel社製) 溶剤 DMC:ジメチルカーボネート(三菱化学) 架橋開始剤 Trignox42(Akuzo Nobel社製)Cathode active material LiCoO 2 Average particle size: 5 μm (manufactured by FMC) Conductive material Acetylene black Average particle size: 40 nm (manufactured by Denki Kagaku Kogyo) Binder Photomer 4050 (manufactured by Henkel) Solvent DMC: dimethyl carbonate (Mitsubishi Chemical) Crosslinking initiator Trignox42 (Akuzo Nobel)
【0028】上記正極用材料を下記の割合で、秤量後、
混練・分散処理を行い塗料化した。 LiCoO2 59.0wt% アセチレンブラック 8.0wt% Photomer4050 8.0wt% Trignox42 0.1wt% PC 24.9wt%After weighing the above positive electrode material at the following ratio,
The mixture was kneaded and dispersed to obtain a paint. LiCoO 2 59.0% by weight Acetylene black 8.0% by weight Photomer 4050 8.0% by weight Trignox 0.1% by weight PC 24.9% by weight
【0029】この塗料を、厚さ20μmのアルミ箔上に
ドクターブレードを用いて、膜厚が150μmになるよ
う塗布した。次にプレス圧が10kgf/cm2となる
ようプレスを行い、120℃で架橋させて電極材が塗布
されたシートを得た。This paint was applied on a 20 μm-thick aluminum foil using a doctor blade so that the film thickness became 150 μm. Next, pressing was performed so that the pressing pressure became 10 kgf / cm 2, and crosslinking was performed at 120 ° C. to obtain a sheet on which the electrode material was applied.
【0030】次に以下に示す組成に従い負極用塗料を作
成し鋼基材上に塗布してLi電池用の正極とし評価し
た。負極塗料の原料としては以下のものを使用した。 負極活物資材 人造黒鉛粉KS6 平均粒径:5μm(LONZA社製) バインダー Photomer4050(Henkel社製) 溶剤 DMC:ジメチルカーボネート(三菱化学) PC:プロピレンカーボネート(三菱化学) EC:エチレンカーボネート(三菱化学) 架橋開始剤 Trignox42(Akuzo Nobel社製)Next, a negative electrode paint was prepared according to the following composition and applied to a steel substrate to evaluate a positive electrode for a Li battery. The following were used as raw materials for the negative electrode paint. Material for negative electrode active material Artificial graphite powder KS6 Average particle size: 5 μm (manufactured by LONZA) Binder Photomer 4050 (manufactured by Henkel) Solvent DMC: dimethyl carbonate (Mitsubishi Chemical) PC: propylene carbonate (Mitsubishi Chemical) EC: ethylene carbonate (Mitsubishi Chemical) Crosslinking initiator Trignox42 (Akuzo Nobel)
【0031】上記負極用材料を下記の割合で、秤量後、
混練・分散処理を行い塗料化した。 KS6 45.0wt% Photomer4050 10.9wt% Trignox42 0.1wt% PC 22.0wt% EC 22.0wt%After weighing the above negative electrode material at the following ratio,
The mixture was kneaded and dispersed to obtain a paint. KS6 45.0 wt% Photomer 4050 10.9 wt% Trignox42 0.1 wt% PC 22.0 wt% EC 22.0 wt%
【0032】この塗料を、厚さ20μmの銅箔上にドク
ターブレードを用い膜厚が150μmになるよう塗布し
た。次にプレス圧が10kgf/cm2となるようプレ
スを行い、120℃で架橋させて電極材が塗布されたシ
ートを得た。次に以下に示す組成に従いポリマー電解質
を作製した。原料としては以下のものを使用した。 アクリルモノマー Photomer4050(Henkel社製) Photomer4158(Henkel社製) ポリマー ポリエチレンオキシド(分子量400万:和光純薬) 溶剤 PC:プロピレンカーボネート(三菱化学) リチウム塩 LiClO4 (和光純薬) 架橋開始剤 Darocure1173(Ciba−Geigy社製)This paint was applied on a copper foil having a thickness of 20 μm using a doctor blade so that the film thickness became 150 μm. Next, pressing was performed so that the pressing pressure became 10 kgf / cm 2, and crosslinking was performed at 120 ° C. to obtain a sheet on which the electrode material was applied. Next, a polymer electrolyte was prepared according to the following composition. The following materials were used. Acrylic monomer Photomer 4050 (manufactured by Henkel) Photomer 4158 (manufactured by Henkel) Polymer Polyethylene oxide (molecular weight: 4,000,000: Wako Pure Chemical) Solvent PC: propylene carbonate (Mitsubishi Chemical) Lithium salt LiClO 4 (Wako Pure Chemical) Crosslinking initiator Darocure 1173 (Ciba) -Geigy)
【0033】上記材料を下記の割合で、秤量後、攪拌溶
解し、ポリマー電解質溶液を得た。 Photomer4050 6.0wt% Photomer4158 4.0wt% ポリエチレンオキシド 0.5wt% PC 79.0wt% LiClO4 10.0wt% Darocure1173 0.5wt%The above-mentioned materials were weighed at the following ratios and dissolved by stirring to obtain a polymer electrolyte solution. Photomer 4050 6.0 wt% Photomer 4158 4.0 wt% Polyethylene oxide 0.5 wt% PC 79.0 wt% LiClO 4 10.0 wt% Darocure 1173 0.5 wt%
【0034】この溶液の粘度をB型粘度計を用いて測定
したところ、200cpであった。次にこの溶液を、銅
基材上に塗布した負極活物質層上に、ドクターブレード
を用い膜厚(d)が50μmになるように塗布し、10
00J/cm2 で紫外線照射を行い、ポリマー電解質層
を得た。なお、このポリマー電解質層を構成するポリマ
ーのピン刺し強度は20g・fであった。このポリマー
電解質層付きの負極の反対の面に正極を重ね合わせ、電
極を取り付け、アルミ蒸着を施したポリエチレン製の袋
内に減圧封入し、リチウム二次電池を得た。ポリマー電
解質層の断面を観察したところ、ポリマー電解質はほぼ
正、負極の活物質層表面の凹凸に含浸しており、断面を
走査型電子顕微鏡により観察し粗さ曲線を求めたとこ
ろ、正極側の活物質層のRp値は10μm、Rv値は6
μm、負極側の活物質層のRp値は12μm、Rv値は
9μmであった。したがって、Rp/dは正極側0.
2、負極側0.24であった。When the viscosity of this solution was measured using a B-type viscometer, it was 200 cp. Next, this solution was applied on the negative electrode active material layer applied on the copper base material using a doctor blade so that the film thickness (d) became 50 μm.
Ultraviolet irradiation was performed at 00 J / cm 2 to obtain a polymer electrolyte layer. In addition, the pin piercing strength of the polymer constituting this polymer electrolyte layer was 20 g · f. The positive electrode was placed on the opposite side of the negative electrode with the polymer electrolyte layer, the electrodes were attached, and the resultant was sealed under reduced pressure in an aluminum-deposited polyethylene bag to obtain a lithium secondary battery. When the cross section of the polymer electrolyte layer was observed, the polymer electrolyte was almost positive, and the surface of the active material layer of the negative electrode was impregnated with irregularities, and the cross section was observed with a scanning electron microscope to obtain a roughness curve. The active material layer has an Rp value of 10 μm and an Rv value of 6
μm, the Rp value of the active material layer on the negative electrode side was 12 μm, and the Rv value was 9 μm. Therefore, Rp / d is 0.
2, 0.24 on the negative electrode side.
【0035】このリチウム二次電池を5個充放電試験に
供したところ、すべて内部短絡もなく、良好な電池特性
を示し、容量が初期容量の80%以下となるサイクル数
をライフと定義すると、サイクルライフは53回であっ
た。この電池を100mmRの曲率で曲げたが、ポリマ
ー電解質と活物質層との剥離は観察されず、良好な接着
性を示していた。そしてこのリチウム二次電池に対し、
5kg/cm2 の荷重を加えたが、内部短絡もなく、電
池特上も影響がなかった。When five lithium secondary batteries were subjected to a charge / discharge test, all of them exhibited good battery characteristics without any internal short circuit, and the number of cycles at which the capacity became 80% or less of the initial capacity was defined as life. The cycle life was 53 times. The battery was bent at a curvature of 100 mmR, but no separation between the polymer electrolyte and the active material layer was observed, indicating good adhesion. And for this lithium secondary battery,
A load of 5 kg / cm 2 was applied, but there was no internal short circuit and no special effect on the battery.
【0036】実施例2 負極作製時のプレス圧を20kgf/cm2 とした以外
は実施例1と同様に行い、リチウム二次電池を作製し
た。実施例1と同様にポリマー電池断面から正、負極活
物質層の表面粗度を求めたところ、正極側のRp値は1
0μm、Rv値は6μm、負極側のRp値は5μm、R
v値は7μmであった。したがって、Rp/dは正極側
0.2、負極側0.1であった。得られた電池5個を充
放電試験に供したところ、すべて得られた電池のサイク
ルライフは、58回と良好な特性を示し、100mmR
の曲げ試験に耐える良好な接着性を示した。次いで行っ
た5kg/cm2 の荷重試験後も特性は変わらなかっ
た。Example 2 A lithium secondary battery was manufactured in the same manner as in Example 1 except that the press pressure at the time of manufacturing the negative electrode was set to 20 kgf / cm 2 . When the surface roughness of the positive and negative electrode active material layers was determined from the cross section of the polymer battery in the same manner as in Example 1, the Rp value on the positive electrode side was 1
0 μm, Rv value is 6 μm, Rp value on the negative electrode side is 5 μm, R
The v value was 7 μm. Therefore, Rp / d was 0.2 on the positive electrode side and 0.1 on the negative electrode side. When five of the obtained batteries were subjected to a charge / discharge test, the cycle life of all of the obtained batteries was 58 times, showing good characteristics.
Showed good adhesiveness to withstand the bending test. After the subsequent 5 kg / cm 2 load test, the characteristics did not change.
【0037】比較例1 負極作製時に、プレス処理をすることなく負極層を形成
した以外は実施例1と同様に行い、リチウム二次電池サ
ンプルを作製した。実施例1同様にポリマー電池断面か
ら正、負極活物質層の表面粗度を求めたところ、正極側
のRp値は10μm、Rv値は6μmの負極側のRp値
は、37μm、Rv値は25μmであった。したがっ
て、Rp/dは正極側0.2、負極側0.74であっ
た。得られた電池5個に対し充放電試験を試みたとこ
ろ、5個のうち1個は、1V以下で、2個は3.8V以
上の電圧で短絡をおこした。1V以下で短絡した電池を
分解観察したところ、突起が欠け落ちたと思われる微粉
が、活物質表面から遊離する形で存在していた。また、
3.8V以上で短絡した電池を分解観察したところ、局
部的にリチウムデンドライトの発生がみられ、正極表面
まで到達していた。残りの2個について、繰り返し充放
電試験をしたところ、サイクルライフは平均12回であ
り、5kg/cm2 の荷重試験により内部短絡をおこし
た。Comparative Example 1 A lithium secondary battery sample was manufactured in the same manner as in Example 1 except that the negative electrode layer was formed without performing a press treatment when the negative electrode was manufactured. When the surface roughness of the positive and negative electrode active material layers was determined from the cross section of the polymer battery in the same manner as in Example 1, the Rp value on the positive electrode side was 10 μm, the Rv value was 6 μm, the Rp value on the negative electrode side was 37 μm, and the Rv value was 25 μm. Met. Therefore, Rp / d was 0.2 on the positive electrode side and 0.74 on the negative electrode side. When a charge / discharge test was performed on five of the obtained batteries, one of the five batteries was short-circuited at a voltage of 1 V or less and two were short-circuited at a voltage of 3.8 V or more. When the battery short-circuited at 1 V or less was disassembled and observed, the fine powder which seemed to have chipped off was present in a form free from the surface of the active material. Also,
When the battery short-circuited at 3.8 V or more was disassembled and observed, lithium dendrite was locally generated and reached the positive electrode surface. The remaining two batteries were subjected to repeated charge / discharge tests. The cycle life was 12 times on average, and an internal short circuit was caused by a load test of 5 kg / cm 2 .
【0038】比較例2 負極作製時のプレス圧を5kgとした以外は、実施例1
と同様に行い、リチウム二次電池を作製した。実施例1
同様にポリマー電池断面から正、負極活物質層の表面粗
度をもとめたところ、正極層のRp値は10μm、Rv
値は6μm、負極層のRp値は25μm、Rv値は25
μmであった。したがって、Rp/dは、正極層0.
2、負極層0.5であった。得られた電池5個を充放電
試験に供したところ、5個のうち2個は3.8V以上の
電圧で短絡をおこした。初期充電が正常に行われた3個
について、繰り返し充放電試験をしたところ、サイクル
ライフは平均20回であった。Comparative Example 2 Example 1 was repeated except that the pressing pressure at the time of producing the negative electrode was 5 kg.
In the same manner as described above, a lithium secondary battery was produced. Example 1
Similarly, when the surface roughness of the positive and negative electrode active material layers was determined from the cross section of the polymer battery, the Rp value of the positive electrode layer was 10 μm and Rv
The value was 6 μm, the Rp value of the negative electrode layer was 25 μm, and the Rv value was 25 μm.
μm. Therefore, Rp / d is 0.
2. The negative electrode layer was 0.5. When five of the obtained batteries were subjected to a charge / discharge test, two of the five batteries were short-circuited at a voltage of 3.8 V or more. When the charge / discharge test was repeatedly performed on the three batteries that were normally charged, the cycle life was 20 times on average.
【0039】比較例3 負極作製時のプレス圧を7kgf/cm2 とした以外
は、実施例1と同様に行い、リチウム二次電池を作製し
た。実施例1同様にポリマー電池断面から正、負極活物
質層の表面粗度をもとめたところ、正極層のRp値は1
0μm、Rv値は6μm、負極層のRp値は22μm、
Rv値は25μmであった。したがって、Rp/dは、
正極層0.2、負極層0.44であった。得られた電池
5個を充放電試験に供したところ、5個のうち2個は
3.8V以上の電圧で短絡をおこした。初期充電が正常
に行われた3個について、繰り返し充放電試験をしたと
ころ、サイクルライフは平均35回であった。Comparative Example 3 A lithium secondary battery was produced in the same manner as in Example 1 except that the press pressure at the time of producing the negative electrode was 7 kgf / cm 2 . When the surface roughness of the positive and negative electrode active material layers was determined from the cross section of the polymer battery in the same manner as in Example 1, the Rp value of the positive electrode layer was 1
0 μm, Rv value is 6 μm, Rp value of the negative electrode layer is 22 μm,
The Rv value was 25 μm. Therefore, Rp / d is
The positive electrode layer was 0.2 and the negative electrode layer was 0.44. When five of the obtained batteries were subjected to a charge / discharge test, two of the five batteries were short-circuited at a voltage of 3.8 V or more. When the charge and discharge test was repeatedly performed on the three batteries that were normally charged in the initial stage, the cycle life was 35 times on average.
【0040】比較例4 負極作製時のプレス圧を100kgf/cm2 とした以
外は、実施例1と同様に行い、リチウム二次電池を作製
した。実施例1同様にポリマー電池断面から正、負極活
物質層の表面粗度をもとめたところ、正極層のRp値は
1μm、Rv値は2μm、負極層のRp値は0.05μ
m、Rv値は0.07μmであった。得られた電池5個
を充放電試験に供したところ、5個とも初期充電が正常
に行われた。しかしながら、100mmRの曲げ試験を
行ったところ、電解質/負極界面での剥離が観察され、
界面接着性の乏しいものであった。Comparative Example 4 A lithium secondary battery was produced in the same manner as in Example 1 except that the press pressure at the time of producing the negative electrode was 100 kgf / cm 2 . When the surface roughness of the positive and negative electrode active material layers was determined from the cross section of the polymer battery in the same manner as in Example 1, the Rp value of the positive electrode layer was 1 μm, the Rv value was 2 μm, and the Rp value of the negative electrode layer was 0.05 μm.
m and Rv values were 0.07 μm. When five of the obtained batteries were subjected to a charge / discharge test, initial charging was normally performed for all five batteries. However, when a bending test of 100 mmR was performed, peeling at the electrolyte / negative electrode interface was observed,
The surface adhesion was poor.
【0041】[0041]
【発明の効果】本発明のリチウム二次電池は、製品収
率、サイクル特性に優れ、外部からの圧力や曲げに対し
て耐えうる優れたものである。The lithium secondary battery of the present invention is excellent in product yield and cycle characteristics, and can withstand external pressure and bending.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 FI H01M 10/38 H01M 10/38 ──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. 6 Identification code FI H01M 10/38 H01M 10/38
Claims (19)
び負極、並びにポリマー電解質とを具備するリチウム二
次電池であって、正極及び負極がリチウムイオンを吸蔵
放出可能な化合物を含む活物質層を集電体上に設け、活
物質層上にポリマー電解質層を設けたものであり、活物
質層表面のRp値(平均線高さ)が0.1μm〜20μ
mであることを特徴とするリチウム二次電池。1. A lithium secondary battery comprising a positive electrode and a negative electrode capable of inserting and extracting lithium ions, and a polymer electrolyte, wherein the positive electrode and the negative electrode collect an active material layer containing a compound capable of inserting and extracting lithium ions. An Rp value (average line height) on the surface of the active material layer is 0.1 μm to 20 μm.
m, a lithium secondary battery.
0.1μm〜50μmであ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。2. The Rv value (average line depth) of the active material layer surface is 0.1 μm to 50 μm.
4. The lithium secondary battery according to 1.
の接触面のRp値が0.1μm〜50μmであることを
特徴とする請求項1又は2に記載のリチウム二次電池。3. The lithium secondary battery according to claim 1, wherein an Rp value of a contact surface of the polymer electrolyte layer with the active material layer is 0.1 μm to 50 μm.
の接触面のRv値が0.1μm〜20μmであることを
特徴とする請求項3に記載のリチウム二次電池。4. The lithium secondary battery according to claim 3, wherein the polymer electrolyte layer has an Rv value of 0.1 μm to 20 μm at a contact surface with the active material layer.
物質層表面でのRp値/dが0.3以下であることを特
徴とする請求項1乃至4のいずれか1つに記載のリチウ
ム二次電池。5. The method according to claim 1, wherein, when an average thickness of the electrolyte layer is d, an Rp value / d on the surface of the active material layer is 0.3 or less. The lithium secondary battery according to the above.
のRp値についても、Rp/dが0.3以下であること
を特徴とする請求項5に記載のリチウム二次電池。6. The lithium secondary battery according to claim 5, wherein Rp / d is 0.3 or less for both the positive and negative electrode active material layers.
であることを特徴とする、請求項1乃至6のいずれか1
つに記載のリチウム二次電池。7. The method according to claim 1, wherein the thickness of the polymer electrolyte layer is 50 μm or less.
The lithium secondary battery according to any one of the above.
であることを特徴とする請求項1乃至7のいずれか1つ
に記載のリチウム二次電池。8. The Rp value of the active material layer surface is 1 to 10 μm
The lithium secondary battery according to claim 1, wherein:
ことを特徴とする請求項6に記載のリチウム二次電池。9. The lithium secondary battery according to claim 6, wherein Rp / d is 0.3 to 0.002.
リチウムと遷移金属の複合酸化物、遷移金属硫化物及び
導電性ポリマーからなる群から選ばれるものであること
を特徴とする請求項1乃至9のいずれか1つに記載のリ
チウム二次電池。10. A positive electrode active material comprising: a transition metal oxide;
The lithium secondary battery according to any one of claims 1 to 9, wherein the lithium secondary battery is selected from the group consisting of a composite oxide of lithium and a transition metal, a transition metal sulfide, and a conductive polymer.
ラファイト及びコークスから選ばれるものであることを
特徴とする請求項1乃至10のいずれか1つに記載のリ
チウム二次電池。11. The lithium secondary battery according to claim 1, wherein the negative electrode active material is selected from lithium metal, graphite and coke.
子で構成されることを特徴とする請求項10又は11に
記載のリチウム二次電池。12. The lithium secondary battery according to claim 10, wherein the active material is composed of particles having an average particle size of 1 to 30 μm.
は導電性物質を含有することを特徴とする請求項1乃至
12のいずれか1つに記載のリチウム二次電池。13. The lithium secondary battery according to claim 1, wherein the active material layer contains a binder component and / or a conductive material.
ンオキシド樹脂あるいはその誘導体であることを特徴と
する請求項13に記載のリチウム二次電池。14. The lithium secondary battery according to claim 13, wherein the binder component is a crosslinkable polyethylene oxide resin or a derivative thereof.
金属粉末であることを特徴とする請求項13又は14に
記載のリチウム二次電池。15. The conductive substance is a carbonaceous powder or
The lithium secondary battery according to claim 13, wherein the lithium secondary battery is a metal powder.
nmであることを特徴とする請求項15に記載のリチウ
ム二次電池。16. The conductive material has an average particle size of 1 to 100.
The lithium secondary battery according to claim 15, wherein
8/2〜90/10であることを特徴とする請求項13
乃至16のいずれか1つに記載のリチウム二次電池。17. The weight ratio between the active material and the conductive material is 9
14. The ratio is from 8/2 to 90/10.
17. The lithium secondary battery according to any one of items 16 to 16.
箔であることを特徴とする請求項1乃至17のいずれか
1つに記載のリチウム二次電池。18. The lithium secondary battery according to claim 1, wherein the current collector is an aluminum foil or a copper foil.
を吸蔵放出可能な化合物を含む活物質層を集電体上に設
けた後、室温〜150℃で、1〜5000kg/cm2
の圧力でカレンダー法により圧力をかけた後、活物質層
上にポリマー電解質層を設けて積層し、活物質層表面の
Rpを0.1〜20μmとしてなることを特徴とするリ
チウム二次電池の製造方法。19. An active material layer containing a compound capable of inserting and extracting lithium ions is provided on a current collector as a positive electrode and a negative electrode, and then at room temperature to 150 ° C. and 1 to 5000 kg / cm 2.
After applying pressure by a calendering method at a pressure of, a lithium secondary battery is characterized in that a polymer electrolyte layer is provided and laminated on the active material layer, and the Rp of the active material layer surface is set to 0.1 to 20 μm. Production method.
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JP14410298A JP4053657B2 (en) | 1997-05-30 | 1998-05-26 | Lithium secondary battery and manufacturing method thereof |
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JP14176797 | 1997-05-30 | ||
JP9-141767 | 1997-05-30 | ||
JP14410298A JP4053657B2 (en) | 1997-05-30 | 1998-05-26 | Lithium secondary battery and manufacturing method thereof |
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