JPH11191432A - Lithium secondary battery - Google Patents
Lithium secondary batteryInfo
- Publication number
- JPH11191432A JPH11191432A JP9360466A JP36046697A JPH11191432A JP H11191432 A JPH11191432 A JP H11191432A JP 9360466 A JP9360466 A JP 9360466A JP 36046697 A JP36046697 A JP 36046697A JP H11191432 A JPH11191432 A JP H11191432A
- Authority
- JP
- Japan
- Prior art keywords
- lithium
- secondary battery
- positive electrode
- charge
- lithium secondary
- 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、リチウム二次電池
に関し、詳しくは非水系リチウム二次電池の高温劣化対
策及び保存劣化対策として有効な、非水電解液の改良に
関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium secondary battery, and more particularly to an improvement of a non-aqueous electrolyte which is effective as a measure against high-temperature deterioration and storage deterioration of a non-aqueous lithium secondary battery.
【０００２】[0002]
【従来の技術】リチウム二次電池は、正極と負極との間
で一方が放出したリチウムイオンを他方が吸蔵するとい
う可逆反応によって充放電を行うものであり、パソコ
ン、ワープロ、携帯電話、電気自動車に実用化されてい
る。こうした作動環境下では高温に達することが多く、
性能劣化が著しく生じるため、そのような環境下でも特
性が劣化しないリチウム二次電池の開発が期待されてい
る。2. Description of the Related Art A lithium secondary battery performs charging and discharging by a reversible reaction in which one side releases lithium ions between a positive electrode and a negative electrode, and performs charging and discharging. A personal computer, a word processor, a mobile phone, and an electric vehicle Has been put to practical use. Under these operating conditions, temperatures often reach high temperatures,
Since the performance is remarkably deteriorated, development of a lithium secondary battery whose characteristics are not deteriorated even in such an environment is expected.
【０００３】従来のリチウム二次電池は、正極活物質と
してマンガン酸リチウム等の金属酸化物が使用され、負
極としては金属リチウムやリチウムイオンを吸蔵・放出
する物質を使用している。電解液としては、非水溶媒に
電解質としてＬｉＰＦ6 ，ＬｉＢＦ4 ，ＬｉＣ１Ｏ4 等
のリチウム塩を溶かしたものが用いられる。In a conventional lithium secondary battery, a metal oxide such as lithium manganate is used as a positive electrode active material, and a material that stores and releases metal lithium and lithium ions is used as a negative electrode. As the electrolytic solution, a solution in which a lithium salt such as LiPF 6 , LiBF 4 , or LiC1O 4 is dissolved as an electrolyte in a non-aqueous solvent is used.
【０００４】これらの正、負極及び電解液の組み合わせ
により、様々な構成が考えられる。また、種々の添加剤
も提案されている。Various configurations are conceivable depending on the combination of the positive electrode, the negative electrode, and the electrolytic solution. Various additives have also been proposed.
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、正極に
マンガン酸リチウムを使用した非水系リチウム二次電池
では、高温になるとＭｎの溶出が原因と考えられる充放
電効率の低下が確認される。However, in a non-aqueous lithium secondary battery using lithium manganate for the positive electrode, a decrease in charge / discharge efficiency attributable to elution of Mn is confirmed at high temperatures.
【０００６】そこで、本発明の目的は、上記課題を解決
し、高温時の充放電効率の低下を抑えて高温特性を改良
したリチウム二次電池を提供することにある。Accordingly, an object of the present invention is to solve the above problems and to provide a lithium secondary battery having improved high-temperature characteristics by suppressing a decrease in charge / discharge efficiency at high temperatures.
【０００７】[0007]
【課題を解決するための手段】上記目的を達成するた
め、本発明のリチウム二次電池は、有機溶媒にリチウム
塩を溶解させて非水電解液とし、正極にマンガン酸リチ
ウムを使用したリチウム二次電池であって、前記非水電
解液に電気化学的酸化及び吸着等により皮膜を形成可能
な物質としてピロール誘導体を０．５〜８％の濃度で添
加し、また、前記マンガン酸リチウムの比表面積を０．
１〜１ｍ2 ／ｇとし、前記マンガン酸リチウムのＬｉ／
Ｍｎ比を１．０５／２〜１．２５／２としたものであ
る。In order to achieve the above object, a lithium secondary battery of the present invention comprises a lithium salt in which a lithium salt is dissolved in an organic solvent to form a non-aqueous electrolyte and lithium manganate is used for a positive electrode. A secondary battery, wherein a pyrrole derivative is added to the nonaqueous electrolyte at a concentration of 0.5 to 8% as a substance capable of forming a film by electrochemical oxidation, adsorption, or the like; Set the surface area to 0.
1 to 1 m 2 / g, and Li /
The Mn ratio was 1.05 / 2 to 1.25 / 2.
【０００８】本発明によれば、高温時の充放電効率の低
下が抑えられ、高温の環境下でも充放電サイクル寿命特
性の劣化しない、高温特性の改善されたリチウム二次電
池が得られる。According to the present invention, it is possible to obtain a lithium secondary battery having an improved high-temperature characteristic in which a decrease in charge-discharge efficiency at a high temperature is suppressed and a charge-discharge cycle life characteristic does not deteriorate even in a high-temperature environment.
【０００９】本発明の動作原理としては、電解液中にピ
ロール誘電体を添加した場合、充電時の正極電位上昇に
伴う反応として、電解酸化重合反応等により正極に皮膜
が形成され、この皮膜が正極側からのＭｎの溶出を抑制
するものと考えられる。この時の反応により負極側では
電解液からリチウムイオンが挿入され、電解液中のリチ
ウムイオン濃度が減少するが、電解液中のリチウム塩濃
度を十分に濃くしておけば問題はない。また、一般的に
この種の電解酸化重合反応では水素ガスが発生するが、
初充電をガスが抜けるような開放下で行えば問題はな
い。According to the principle of operation of the present invention, when a pyrrole dielectric is added to an electrolytic solution, a film is formed on a positive electrode by an electrolytic oxidation polymerization reaction or the like as a reaction accompanying a positive electrode potential rise during charging. It is considered that elution of Mn from the positive electrode side is suppressed. Lithium ions are inserted from the electrolytic solution on the negative electrode side by the reaction at this time, and the lithium ion concentration in the electrolytic solution decreases. However, there is no problem if the lithium salt concentration in the electrolytic solution is sufficiently increased. In general, hydrogen gas is generated in this type of electrolytic oxidation polymerization reaction,
There is no problem if the first charge is performed in an open state where gas escapes.
【００１０】本発明において、添加するピロール誘電体
の濃度は０．５〜８％の割合であることが好ましく、ピ
ロール誘電体濃度が０．５％未満では形成される皮膜の
厚さが十分でなく、充放電サイクル寿命を延ばす効果が
確認されない。またピロール誘電体濃度が８％を越える
と、皮膜が十分厚く形成されるが、その反面正極活物質
を集電体から引き剥がすような力が働くため、サイクル
寿命の特性向上に寄与しなくなる。In the present invention, the concentration of the pyrrole dielectric to be added is preferably 0.5 to 8%, and if the concentration of the pyrrole dielectric is less than 0.5%, the thickness of the formed film is sufficient. No effect of extending the charge / discharge cycle life was confirmed. If the pyrrole dielectric concentration exceeds 8%, the film is formed to be sufficiently thick, but on the other hand, a force acts to peel off the positive electrode active material from the current collector, so that it does not contribute to improvement in cycle life characteristics.
【００１１】また、マンガン酸リチウムの比表面積は
０．１〜１ｍ2 ／ｇであることが好ましく、０．１ｍ2
／ｇ未満の比表面積のものは作成できなかった。しか
し、マンガン酸リチウムの比表面積が０．１ｍ2 ／ｇ未
満では、活物質と電解液との反応面積が小さくなり、電
流密度が過大となって容量が低下したり、電圧が低下す
るといった問題があると考えられる。また、マンガン酸
リチウムの比表面積が１ｍ2 ／ｇを超えると、電解液と
の反応面積が大きくなり、充放電特性が劣化する。[0011] The specific surface area of the lithium manganate is preferably from 0.1~1m 2 / g, 0.1m 2
/ G specific surface area could not be produced. However, when the specific surface area of lithium manganate is less than 0.1 m 2 / g, the reaction area between the active material and the electrolytic solution becomes small, the current density becomes excessive, and the capacity decreases, and the voltage decreases. It is thought that there is. On the other hand, when the specific surface area of lithium manganate exceeds 1 m 2 / g, the reaction area with the electrolytic solution increases, and the charge / discharge characteristics deteriorate.
【００１２】更に、Ｌｉ／Ｍｎ比は１．０５／２〜１．
２５／２であることが好ましく、前記以外の範囲では結
晶構造が安定しておらず、放充電サイクルが劣化する。Further, the Li / Mn ratio is 1.05 / 2 to 1.
The ratio is preferably 25/2, and in the range other than the above, the crystal structure is not stable, and the discharge / charge cycle is deteriorated.
【００１３】電解液としては、非水溶媒に電解質として
ＬｉＰＦ6 ，ＬｉＢＦ4 ，ＬｉＣ１Ｏ4 等のリチウム塩
を溶かしたものを用いることができるが、本発明におい
ては、添加する電解質がＬｉＰＦ6 である場合において
特に望ましい結果が得られる。As the electrolytic solution, a solution in which a lithium salt such as LiPF 6 , LiBF 4 , or LiC1O 4 is dissolved in a non-aqueous solvent can be used. In the present invention, the electrolyte to be added is LiPF 6 . Particularly desirable results are obtained in some cases.
【００１４】[0014]
【発明の実施の形態】以下、本発明の実施形態を図示の
実施例を中心に説明する。但し、下記の実施形態は一例
であり、本発明は下記の実施形態に限定されるものでは
ない。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below with reference to examples shown in the drawings. However, the following embodiment is an example, and the present invention is not limited to the following embodiment.
【００１５】［電池の作製］正極活物質のＬｉＭｎ2 Ｏ
4 （マンガン酸リチウム）は、ＭｎＯ2 （二酸化マンガ
ン）とＬｉ2 ＣＯ3 （炭酸リチウム）とをモル比で２／
０．８〜２／１．５までの範囲で変化させ混合し、空気
中で７００〜８００℃で加熱焼結した。こうして作成し
たＬｉｘＭｎ2 Ｏ4 （０．８＜ｘ＜１．５）を粉砕機を
使用して比表面積を制御した。ＢＥＴ表面積計で測定し
たところ、比表面積０．１〜３．８２であった。[Production of Battery] LiMn 2 O as a positive electrode active material
4 (lithium manganate) is a mixture of MnO 2 (manganese dioxide) and Li 2 CO 3 (lithium carbonate) in a molar ratio of 2 /
The mixture was changed in a range of 0.8 to 2 / 1.5, mixed and heated and sintered at 700 to 800 ° C. in air. The specific surface area of LixMn 2 O 4 (0.8 <x <1.5) thus prepared was controlled using a pulverizer. When measured with a BET surface area meter, the specific surface area was 0.1 to 3.82.
【００１６】以上の工程で作成したＬｉＭｎ2 Ｏ4 を正
極活物質として用い、以下に述べるようにして、図４に
示す単三型（１４．５φｍｍ×５０ｍｍ）のリチウム二
次電池を作製した。Using the LiMn 2 O 4 prepared in the above steps as a positive electrode active material, an AA (14.5 mm × 50 mm) lithium secondary battery shown in FIG. 4 was prepared as described below.
【００１７】図４は、従来公知のものと同じ巻回式非水
電解液二次電池の構造図である。図４において、１は正
極であり、正極活物質と誘電剤のカーボン粉末及び結着
剤のＰＴＦＥの水性ディスバージョンを、質量比で１０
０：１０：１０の割合で混合し、水を加えて混練しペー
スト状としたものを、アルミニウム箔の両面に塗布し、
乾燥、圧延した後、所定の大きさに切断し帯状正極シー
トに作成した。また、上記の材料の混合比率のうちＰＴ
ＦＥの水性ディスバージョンの割合は、そのうちの固形
分の割合である。FIG. 4 is a structural view of the same type of conventional non-aqueous electrolyte secondary battery known in the art. In FIG. 4, reference numeral 1 denotes a positive electrode, which is an aqueous dispersion of a positive electrode active material, a carbon powder of a dielectric agent, and PTFE as a binder in a mass ratio of
The mixture was mixed at a ratio of 0:10:10, and kneaded by adding water to form a paste, which was applied to both sides of an aluminum foil,
After drying and rolling, it was cut into a predetermined size to form a belt-shaped positive electrode sheet. In addition, of the mixing ratios of the above materials, PT
The percentage of aqueous dispersion of the FE is the percentage of solids therein.
【００１８】２は負極であり、負極活物質としての炭素
質粉末と結着剤のＰＴＦＥの水性ディスバージョンを、
質量比で１００：５の割合で混合し、水を加えて混練し
ペースト状としたものを、銅箔の両面に塗布し、乾燥、
延圧した後、所定の大きさに切断し帯状負極シートに作
成した。なおＰＴＦＥの比率は上記と同様に固形分の割
合である。Reference numeral 2 denotes a negative electrode, which comprises an aqueous dispersion of carbonaceous powder as a negative electrode active material and PTFE as a binder,
The mixture was mixed at a mass ratio of 100: 5, water was added and kneaded to form a paste, which was applied to both sides of a copper foil, dried,
After the elongation, it was cut into a predetermined size to form a strip-shaped negative electrode sheet. In addition, the ratio of PTFE is a ratio of a solid content similarly to the above.
【００１９】こうして、作成した正極１と負極２とを多
孔質フィルム３を介して渦巻状に巻回して、発電要素を
形成し、これを有底筒形の外装缶４内に挿入する。その
際、発電要素の上部には前記正極１側に接続する正極リ
ード板５が、下部には前記負極２側に接続する負極リー
ド板１１が突出した状態とする。The positive electrode 1 and the negative electrode 2 thus formed are spirally wound through the porous film 3 to form a power generating element, which is inserted into the bottomed cylindrical outer can 4. At this time, a positive electrode lead plate 5 connected to the positive electrode 1 side protrudes above the power generating element, and a negative electrode lead plate 11 connected to the negative electrode 2 side protrudes below the power generating element.
【００２０】発電要素を外装缶４内に挿入後、絶縁板８
の孔１３より電極棒を挿入して負極リード板１１をスポ
ット溶接により外装缶４の内底面中心に接続し、また正
極リード板５を、安全弁１０付きの正極端子板７の底部
をなす封口板６に、スポット溶接する。After inserting the power generating element into the outer can 4, the insulating plate 8
The negative electrode lead plate 11 is connected to the center of the inner bottom surface of the outer can 4 by spot welding, and the positive electrode lead plate 5 is connected to the sealing plate forming the bottom of the positive electrode terminal plate 7 with the safety valve 10 by inserting an electrode rod through the hole 13. 6 is spot-welded.
【００２１】その後、外装缶４内に電解液及び添加剤
（ピロール誘導体濃度が０〜１５％になるように変化さ
せる）を注入し、正極端子板７を封口ガスケット９を介
して外装缶４の開口にかしめ付けして、単三型（１４．
５φｍｍ×５０ｍｍ）サイズのリチウム二次電池が完成
される。Thereafter, an electrolytic solution and an additive (changed so that the pyrrole derivative concentration becomes 0 to 15%) are injected into the outer can 4, and the positive electrode terminal plate 7 is inserted into the outer can 4 via a sealing gasket 9. It is caulked to the opening and AA type (14.
A lithium secondary battery having a size of 5 mm × 50 mm) is completed.
【００２２】［サイクル特性試験］こうして作成したリ
チウム二次電池について、その充放電サイクル寿命（サ
イクル数）の試験を次の条件で行った。 試験温度：４５℃ 充 電 ：定電流 ０．２℃ 終止電圧４．２Ｖ 放 電 ：定電流 ０．２℃ 終止電圧３．０Ｖ 「サイクル数」は、初サイクルの放電容量に対して８０
％以上の放電容量を維持していたサイクルの最終値をサ
イクル数（回）とし、その電池の寿命とした。また、図
１，２，３に示したピロール誘導体は３−アセチル１−
メチルピロールである。[Cycle Characteristics Test] The lithium secondary battery thus prepared was subjected to a charge / discharge cycle life (cycle number) test under the following conditions. Test temperature: 45 ° C Charge: Constant current 0.2 ° C Final voltage 4.2V Discharge: Constant current 0.2 ° C Final voltage 3.0V The “number of cycles” is 80 times the discharge capacity of the first cycle.
% Was defined as the number of cycles (times), and the life of the battery was determined. In addition, the pyrrole derivative shown in FIGS.
Methyl pyrrole.
【００２３】図１は、ピロール誘導体濃度、つまり電解
液全体におけるピロール誘導体の割合を０〜１５％の範
囲で変化させた場合に、サイクル数がどのように変化す
るかを示したもので、横軸にピロール誘導体添加量
（％）を、縦軸にサイクル数（回）をとってある。この
ときの、正極のマンガン酸リチウムの比表面積は０．５
（ｍ2 ／ｇ）であり、Ｌｉ／Ｍｎ比は１．１である。図
１中で、黒丸印のサイクル特性曲線は電解質がＬｉＰＦ
6 の場合を、黒三角印のサイクル特性曲線は電解質がＬ
ｉＢＦ4 の場合を、黒四角印のサイクル特性曲線は電解
質がＬｉＣｌＯ4 の場合をそれぞれ示している。ここ
で、図１に表されているデータはＬｉＰＦ6 、ＬｉＢＦ
4 、ＬｉＣｌＯ4 がすべて１モルのときのものである。FIG. 1 shows how the number of cycles changes when the concentration of the pyrrole derivative, that is, the proportion of the pyrrole derivative in the whole electrolyte is changed in the range of 0 to 15%. The axis indicates the amount of pyrrole derivative added (%), and the axis of ordinate indicates the number of cycles (times). At this time, the specific surface area of the lithium manganate of the positive electrode was 0.5
(M 2 / g) and the Li / Mn ratio is 1.1. In FIG. 1, the cycle characteristic curve indicated by a black circle indicates that the electrolyte is LiPF.
In the case of 6 , the cycle characteristic curve indicated by the black triangle indicates that the electrolyte is L
In the case of iBF 4 , the cycle characteristic curves indicated by black squares indicate the case where the electrolyte is LiClO 4 . Here, the data shown in FIG. 1 is LiPF 6 , LiBF
4 and LiClO 4 are all 1 mol.
【００２４】図１に示したように、本発明により電解液
の添加剤としてピロール誘電体を使用することにより、
充放電効率が飛躍的に向上することが確認される。その
効果は添加量に依存しピロール誘電体濃度が０．５〜８
％である範囲でサイクルが改善される。また電解質の種
類による影響が大きくＬｉＰＦ6 を使用した際に、サイ
クル特性の改善が最も顕著となることが判る。As shown in FIG. 1, by using a pyrrole dielectric as an additive of the electrolyte according to the present invention,
It is confirmed that the charge / discharge efficiency is dramatically improved. The effect depends on the amount of addition and the pyrrole dielectric concentration is 0.5 to 8
%, The cycle is improved. In addition, it can be seen that the effect of the type of the electrolyte is large, and when LiPF 6 is used, the cycle characteristics are most significantly improved.
【００２５】図２は、正極のマンガン酸リチウムの比表
面積を０．１〜３．８２の範囲で変えた場合に、サイク
ル数がどのように変化するかを示したもので、横軸に比
表面積（ｍ2 ／ｇ）を、縦軸にサイクル数（回）をとっ
てある。このときの、ピロール誘導体の添加量は５％で
あり、正極のマンガン酸リチウムのＬｉ／Ｍｎ比は１．
１である。FIG. 2 shows how the number of cycles changes when the specific surface area of lithium manganate of the positive electrode is changed in the range of 0.1 to 3.82. The surface area (m 2 / g) is plotted on the vertical axis with the number of cycles (times). At this time, the addition amount of the pyrrole derivative was 5%, and the Li / Mn ratio of lithium manganate of the positive electrode was 1.
It is one.
【００２６】図２に示したように、電解質にピロール誘
電体が適切な濃度範囲内で添加された電池であっても、
ＬｉＭｎ2 Ｏ4 の比表面積を制御しなければ、充放電サ
イクルが改善されないことが確認された。その比表面積
の範囲としては、比表面積０．１〜１ｍ2 ／ｇが適切で
ある。As shown in FIG. 2, even in a battery in which a pyrrole dielectric is added to an electrolyte within an appropriate concentration range,
It was confirmed that the charge / discharge cycle was not improved unless the specific surface area of LiMn 2 O 4 was controlled. As the range of the specific surface area, 0.1 to 1 m 2 / g is appropriate.
【００２７】また、図３は、ＬｉＭｎ2 Ｏ4 のＬｉ／Ｍ
ｎ比を０．８／２〜１．５／２の範囲で変えた場合に、
サイクル数がどのように変化するかを示したもので、横
軸にＬｉｘＭｎ2 Ｏ4 （０．８＜ｘ＜１．５）を、縦軸
にサイクル数（回）をとってある。このときの、ピロー
ル誘導体の添加量は５％であり、正極のマンガン酸リチ
ウムの比表面積は０．５（ｍ2 ／ｇ）である。FIG. 3 shows Li / M of LiMn 2 O 4.
When the n ratio is changed in the range of 0.8 / 2 to 1.5 / 2,
It shows how the number of cycles changes, with the horizontal axis representing LixMn 2 O 4 (0.8 <x <1.5) and the vertical axis representing the number of cycles (times). At this time, the amount of the pyrrole derivative added was 5%, and the specific surface area of the lithium manganate of the positive electrode was 0.5 (m 2 / g).
【００２８】図３に示したように、電解質にＬｉＰＦ6
が使用されかつピロール誘電体が適切な濃度範囲内で添
加され、比表面積も適切な範囲で制御された電池であっ
ても、ＬｉＭｎ2 Ｏ4 のＬｉ／Ｍｎ比を制御しなければ
充放電サイクルは改善されない。その範囲としては、Ｌ
ｉ／Ｍｎ比が１．０５／２〜１．２５／２であるのが適
切である。As shown in FIG. 3, LiPF 6 is used as the electrolyte.
Is used, the pyrrole dielectric is added in an appropriate concentration range, and the specific surface area is also controlled in an appropriate range. However, if the Li / Mn ratio of LiMn 2 O 4 is not controlled, the charge / discharge cycle Does not improve. The range is L
Suitably, the i / Mn ratio is between 1.05 / 2 and 1.25 / 2.
【００２９】要するに、上に述べた条件を全て満たすと
き、充放電特性が最も改善され、高温での充放電サイク
ルの長寿命化を果たした電池が提供される。In short, when all of the above-mentioned conditions are satisfied, a battery is provided which has the most improved charge / discharge characteristics and a longer life of a charge / discharge cycle at a high temperature.
【００３０】そこで、図１〜図４で説明した有機溶媒に
リチウム塩としてＬｉＰＦ6 を溶解させた液を非水電解
液とし、正極にマンガン酸リチウムを使用した単三型リ
チウム二次電池において、電気化学的酸化により皮膜形
成可能な物質としてピロール誘導体を選択して、ピロー
ル誘導体濃度が０．５〜８％となる割合で非水電解液に
添加し、また、マンガン酸リチウムの比表面積を０．１
〜１ｍ2 ／ｇとし、Ｌｉ／Ｍｎ比を１．０５／２〜１．
２５／２としたところ、高温での充放電サイクル寿命の
長いＬｉＭｎ2 Ｏ4 系単三型リチウム二次電池が作製で
きた。また、同様にリチウム塩としてＬｉＢＦ4 、Ｌｉ
ＣｌＯ4 を用いて単三型リチウム二次電池を試作した
が、この場合も、従来より長い充放電サイクル寿命の単
三型リチウム二次電池が作製できた。Therefore, in an AA lithium secondary battery using a solution in which LiPF 6 is dissolved as a lithium salt in the organic solvent described in FIGS. 1 to 4 as a non-aqueous electrolyte and lithium manganate as a positive electrode, A pyrrole derivative is selected as a substance capable of forming a film by electrochemical oxidation, and the pyrrole derivative is added to the non-aqueous electrolyte at a concentration of 0.5 to 8%, and the specific surface area of lithium manganate is set to 0. .1
Ｌｉ1 m 2 / g and a Li / Mn ratio of 1.05 / 2 to 1.
When the ratio was 25/2, a LiMn 2 O 4 -based AA lithium secondary battery having a long charge / discharge cycle life at a high temperature could be produced. Similarly, lithium salts such as LiBF 4 and Li
A prototype AA lithium secondary battery was manufactured using ClO 4 , but in this case also, an AA lithium secondary battery having a longer charge / discharge cycle life than the conventional one could be fabricated.
【００３１】また、ピロール誘導体の種類を変えて同様
の測定を行った結果を表１に示す。Table 1 shows the results of similar measurements performed with different kinds of pyrrole derivatives.
【表１】 [Table 1]
【００３２】この時のピロール誘導体添加量は５％と
し、Ｌｉ／Ｍｎ比は１．１、正極マンガン酸リチウムの
比表面積は０．５（ｍ2 ／ｇ）である。充放電サイクル
特性の最も良かった３−アセチル１−メチルピロールの
サイクル数を１００％とし、種々のピロール誘導体に対
するサイクル数を相対的に％で示した。それぞれの添加
剤で充放電サイクル特性改善の効果が確認された。この
結果より２，５基の水素を置換したものは重合による電
解酸化皮膜を生成し難く良好な結果が得られなかったと
考えられる。また１基の水素を置換したものは導電性が
劣るため、電子の流れを阻害しサイクル特性に悪影響を
与えると推察される。そのため、３，４基のみを置換し
たピロール誘導体を選択すれば良好な結果が得られると
予想される。At this time, the amount of the pyrrole derivative added was 5%, the Li / Mn ratio was 1.1, and the specific surface area of the positive electrode lithium manganate was 0.5 (m 2 / g). The cycle number of 3-acetyl 1-methylpyrrole having the best charge / discharge cycle characteristics was defined as 100%, and the cycle numbers for various pyrrole derivatives were relatively expressed as%. The effect of improving the charge / discharge cycle characteristics was confirmed with each additive. From these results, it is considered that those obtained by substituting two or five hydrogen atoms hardly formed an electrolytic oxide film by polymerization, so that good results could not be obtained. In addition, it is presumed that the substitution of one hydrogen has a poor conductivity, so that the flow of electrons is inhibited and the cycle characteristics are adversely affected. Therefore, it is expected that good results will be obtained by selecting a pyrrole derivative substituted with only 3, 4 groups.
【００３３】[0033]
【発明の効果】以上に説明したように本発明によれば、
非水電解液に電気化学的酸化により皮膜を形成可能な物
質としてピロール誘導体を０．５〜８％の濃度で添加し
たので、充放電サイクル寿命を延ばすことができる。ま
た、前記マンガン酸リチウムの比表面積を０．１〜１ｍ
２／ｇとし、活物質と電解液との反応面積を適正なもの
としたので、良好な充放電特性を得ることができる。更
に、前記マンガン酸リチウムのＬｉ／Ｍｎ比を１．０５
／２〜１．２５／２としたので、結晶構造を安定させて
放充電サイクルの劣化を防止に寄与させることができ
る。According to the present invention as described above,
Since the pyrrole derivative is added to the nonaqueous electrolyte at a concentration of 0.5 to 8% as a substance capable of forming a film by electrochemical oxidation, the charge / discharge cycle life can be extended. The specific surface area of the lithium manganate is 0.1 to 1 m.
Since the reaction area was 2 / g and the reaction area between the active material and the electrolytic solution was appropriate, good charge / discharge characteristics can be obtained. Further, the Li / Mn ratio of the lithium manganate is set to 1.05
Since the ratio is set to / 2 to 1.25 / 2, it is possible to stabilize the crystal structure and contribute to prevention of deterioration of the discharge / charge cycle.
【００３４】従って、本発明によれば、正極マンガン酸
リチウムを用いたリチウム二次電池の高温での充放電サ
イクル特性が向上したリチウム二次電池を得ることがで
きる。Therefore, according to the present invention, it is possible to obtain a lithium secondary battery using lithium manganate as a positive electrode and having improved charge / discharge cycle characteristics at a high temperature.
【００３５】また、特に添加する電解質をＬｉＰＦ6 と
した場合においては、充放電サイクル特性が顕著に優れ
るリチウム二次電池を得ることができる。Further, when the electrolyte to be added is LiPF 6 , a lithium secondary battery having remarkably excellent charge / discharge cycle characteristics can be obtained.
【図１】本発明の一実施形態におけるピロール誘導体の
添加量（％）と充放電サイクル数との関係を示す図であ
る。FIG. 1 is a diagram showing the relationship between the amount (%) of a pyrrole derivative added and the number of charge / discharge cycles in one embodiment of the present invention.
【図２】本発明の一実施形態における正極のマンガン酸
リチウムの比表面積（ｍ2 ／ｇ）と充放電サイクル数と
の関係を示す図である。FIG. 2 is a diagram showing the relationship between the specific surface area (m 2 / g) of lithium manganate of the positive electrode and the number of charge / discharge cycles in one embodiment of the present invention.
【図３】本発明の一実施形態におけるＬｉＭｎ2 Ｏ4 の
Ｌｉ／Ｍｎ比と充放電サイクル数との関係を示す図であ
る。FIG. 3 is a diagram showing the relationship between the Li / Mn ratio of LiMn 2 O 4 and the number of charge / discharge cycles in one embodiment of the present invention.
【図４】本発明の一実施形態に係るリチウム二次電池の
断面図である。FIG. 4 is a sectional view of a lithium secondary battery according to an embodiment of the present invention.
１ 正極 ２ 負極 ３ セパレータ ４ 外装缶 ５ 正極リード板 ６ 封口板 ７ 正極端子板 ８ 絶縁板 ９ 封口ガスケット １０ 安全弁 １１ 負極リード板 DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 4 Outer can 5 Positive electrode lead plate 6 Sealing plate 7 Positive terminal plate 8 Insulating plate 9 Sealing gasket 10 Safety valve 11 Negative electrode lead plate
Claims (2)
非水電解液とし、正極にマンガン酸リチウムを使用した
リチウム二次電池であって、前記非水電解液にピロール
誘導体を０．５〜８％の濃度で添加し、また、前記マン
ガン酸リチウムの比表面積を０．１〜１ｍ2 ／ｇとし、
前記マンガン酸リチウムのＬｉ／Ｍｎ比を１．０５／２
〜１．２５／２としたことを特徴とするリチウム二次電
池。1. A lithium secondary battery using a liquid in which a lithium salt is dissolved in an organic solvent as a non-aqueous electrolyte, and using lithium manganate for a positive electrode, wherein the non-aqueous electrolyte contains 0.5% of a pyrrole derivative. -8%, and the specific surface area of the lithium manganate is 0.1-1 m 2 / g;
The Li / Mn ratio of the lithium manganate is 1.05 / 2
To 1.25 / 2.
ムであることを特徴とする請求項１記載のリチウム二次
電池。2. The lithium secondary battery according to claim 1, wherein said lithium salt is lithium hexafluorophosphate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9360466A JPH11191432A (en) | 1997-12-26 | 1997-12-26 | Lithium secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9360466A JPH11191432A (en) | 1997-12-26 | 1997-12-26 | Lithium secondary battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH11191432A true JPH11191432A (en) | 1999-07-13 |
Family
ID=18469532
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9360466A Pending JPH11191432A (en) | 1997-12-26 | 1997-12-26 | Lithium secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH11191432A (en) |
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| JP2007504619A (en) * | 2003-09-19 | 2007-03-01 | エルジー・ケム・リミテッド | Non-aqueous lithium secondary battery with improved cycle characteristics and / or high temperature stability |
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- 1997-12-26 JP JP9360466A patent/JPH11191432A/en active Pending
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| KR101375024B1 (en) * | 2007-07-23 | 2014-03-17 | 삼성에스디아이 주식회사 | Lithium ion battery including oxygen scavenger |
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