JPH07302589A - Nonaqueous electrolyte secondary battery - Google Patents
Nonaqueous electrolyte secondary batteryInfo
- Publication number
- JPH07302589A JPH07302589A JP6129434A JP12943494A JPH07302589A JP H07302589 A JPH07302589 A JP H07302589A JP 6129434 A JP6129434 A JP 6129434A JP 12943494 A JP12943494 A JP 12943494A JP H07302589 A JPH07302589 A JP H07302589A
- Authority
- JP
- Japan
- Prior art keywords
- battery
- negative electrode
- positive electrode
- lithium
- lithium ion
- 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
Landscapes
- Carbon And Carbon Compounds (AREA)
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】この発明は、非水電解液二次電池
の性能改善に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improving the performance of a non-aqueous electrolyte secondary battery.
【0002】[0002]
【従来の技術】電子機器の小型化、軽量化が進められる
中、その電源として高エネルギー密度の二次電池の要望
がさらに強まっている。その要望に答えるため、以前よ
り高い電池電圧が得られる非水電解液二次電池が注目さ
れ、その実用化が試みられて来た。しかし負極のサイク
ル寿命に問題があり、実用化はなかなか難しいことが判
ってきた。しかし極く最近になって、カーボンへのリチ
ウムイオンの出入りを利用するカーボン電極を負極とす
る非水電解液二次電池が開発され、非水電解液二次電池
もようやく実用化の段階に入った。この電池は本発明者
等によって、リチウムイオン二次電池と名付けて199
0年に始めて世の中に紹介されたもので(雑誌Prog
ress In Batteries & Solar
Cells,Vol.9,1990,p209 参
照), 現在では電池業界、学会においても“リチウム
イオン二次電池”の呼び名で認知され、次世代の二次電
池と言われてその実用化に拍車がかかっている。代表的
には正極材料にリチウム含有複合酸化物(例えばLiC
oO2、LiMn2O4等)を用い、負極にはコークス
やグラファイト等の炭素質材料が用いられる。実際、正
極にLiCoO2を使用し、負極には特殊な炭素材料
(ある程度の乱層構造を有した擬黒鉛材料)を使用し
て、240Wh/l程のエネルギー密度を持つリチウム
イオン二次電池が、既に携帯電話やビデオカメラの電源
として実用されている。既存のニッケルカドミウム二次
電池のエネルギー密度は100〜150Wh/lであ
り、リチウムイオン二次電池のエネルギー密度は初期に
おいては既存の電池のそれをはるかに上回るものであ
る。しかし現状のリチウムイオン二次電池は充放電サイ
クルに伴う容量の劣化が大きく、500回の充放電サイ
クル後ではそのエネルギー密度も160〜170Wh/
lまで下がってしまうので、充放電サイクルを繰り返す
と高エネルギー密度の電池であるという特徴が薄れてく
る。2. Description of the Related Art As electronic devices are becoming smaller and lighter, there is a growing demand for high energy density secondary batteries as their power sources. In order to meet the demand, a non-aqueous electrolyte secondary battery, which can obtain a higher battery voltage than before, has attracted attention, and its practical application has been attempted. However, it has been found that there is a problem in the cycle life of the negative electrode, and it is quite difficult to put it into practical use. However, very recently, a non-aqueous electrolyte secondary battery has been developed that uses a carbon electrode as a negative electrode, which utilizes the inflow and outflow of lithium ions into carbon, and finally the non-aqueous electrolyte secondary battery is also in the stage of practical application. It was This battery was named by the present inventors as a lithium ion secondary battery and was named 199
It was introduced to the world for the first time in 0 years (the magazine Prog
less In Batteries & Solar
Cells, Vol. 9, 1990, p. 209), it is now recognized in the battery industry and academic societies under the name of "lithium ion secondary battery", and it is said to be the next-generation secondary battery, and its practical application is being accelerated. Typically, a lithium-containing composite oxide (for example, LiC) is used as a positive electrode material.
oO 2 , LiMn 2 O 4, etc.) and a carbonaceous material such as coke or graphite is used for the negative electrode. In fact, using LiCoO 2 for the positive electrode and a special carbon material (pseudo-graphite material having a certain degree of disordered layer structure) for the negative electrode, a lithium ion secondary battery having an energy density of about 240 Wh / l is obtained. , Has already been used as a power source for mobile phones and video cameras. The energy density of the existing nickel-cadmium secondary battery is 100 to 150 Wh / l, and the energy density of the lithium-ion secondary battery is much higher than that of the existing battery in the initial stage. However, the current lithium-ion secondary battery has a large deterioration in capacity with charge / discharge cycles, and its energy density is 160 to 170 Wh / hour after 500 charge / discharge cycles.
Since it drops to 1, the characteristic of a battery having a high energy density is diminished when the charge / discharge cycle is repeated.
【0003】[0003]
【発明が解決しようとする課題】本発明はリチウムイオ
ン二次電池のサイクル特性の改善に関するものである。DISCLOSURE OF THE INVENTION The present invention relates to improvement of cycle characteristics of a lithium ion secondary battery.
【0004】[0004]
【課題を解決するための手段】課題解決の手段は、電極
中に個体のリチウムイオン伝導体を活物質に混じて含有
せしめるものである。[Means for Solving the Problem] The means for solving the problem is to incorporate an individual lithium ion conductor in an electrode by mixing it with an active material.
【0005】[0005]
【作用】正極にリチウム含有複合酸化物(LiMn2O
4、LiCoO2、LiNiO2等)を使用し、負極に
は炭素材料を使用するリチウムイオン二次電池では、一
般に第1回目の充電では充電効率(放電量/充電量)は
90%程度であるが2回目以降は99%以上を示す。し
かし100%ではない。充電効率が100%とならない
主な原因は、電極反応として充電反応に平行して不可逆
的な副反応が起こることによると考えられる。厳密には
正極と負極では副反応の起こる割合は異なるので、正極
と負極の充電効率は異なり、正極か負極かの何れか悪い
方の充電効率が電池としての充電効率として現れる。そ
して正極と負極の充放電効率の差は充放電を繰り返す度
に積算されて、電池容量の低下をきたすことになる。前
記リチウムイオン二次電池の充電では、充電電気量に相
当するリチウムイオンが正極ではリチウム含有複合酸化
物より脱ドープされ、負極ではカーボン中にドーピング
される。つまり96500クーロンの充電量に対して
は、1グラム当量のリチウムイオンが正極活物質から抜
き出され、カーボン中に進入するのが理想的充電反応で
ある。負極にリチウムを可逆的にドープおよび脱ドープ
可能な炭素材料を主活物質として用いる前記リチウムイ
オン二次電池では、その電解液には有機電解液が使用さ
れる。有機電解液は有機溶媒にリチウム塩(例えばLi
PF6、LiBF4等)を溶解したものであって、電解
液中の電気伝導はカチオン(Li+)とアニオン(PF
6 −、BF4 −等)の両方のイオンの移動で行われる。
従ってリチウムイオンの輸率は1ではない。充電時にカ
ーボン中へドーピングされるリチウムイオンは電解液を
通して正極より負極へ移動してくるものであるが、リチ
ウムイオンの輸率は1ではないので、負極ではリチウム
イオン不足となる。反対に放電では正極でリチウムイオ
ン不足となる。特にリチウムイオン不足での充電は負極
においてカーボン中へのリチウムイオンのドーピング反
応以外に副反応が不可逆的に起こることになり、容量劣
化の原因となる。本発明では少なくとも負極中に、個体
のリチウムイオン伝導体を活物質炭素に混じて添加する
ことで、負極におけるリチウムイオン不足を解消し、容
量劣化の原因を取り除くことに成功した。つまり有機溶
媒にリチウム塩を溶解した有機電解液と異なり、個体の
リチウムイオン伝導体によるイオン伝導ではリチウムイ
オンの輸率はほぼ1であり、充電末期においても負極中
のリチウムイオン不足を来たさない。したがって充放電
の繰り返しによる容量劣化は極度に少なくなる。[Function] A lithium-containing composite oxide (LiMn 2 O
4 , LiCoO 2 , LiNiO 2, etc.) and a lithium ion secondary battery using a carbon material for the negative electrode generally has a charging efficiency (discharge amount / charge amount) of about 90% in the first charge. Indicates 99% or more after the second time. But not 100%. It is considered that the main reason why the charging efficiency does not reach 100% is that an irreversible side reaction occurs in parallel with the charging reaction as an electrode reaction. Strictly speaking, the positive electrode and the negative electrode have different rates of side reactions, so that the positive electrode and the negative electrode have different charging efficiencies, and the charging efficiency of either the positive electrode or the negative electrode appears as the charging efficiency of the battery. Then, the difference between the charge and discharge efficiencies of the positive electrode and the negative electrode is integrated every time charge and discharge are repeated, resulting in a decrease in battery capacity. In charging the lithium-ion secondary battery, lithium ions corresponding to the amount of charged electricity are dedoped from the lithium-containing composite oxide in the positive electrode and are doped in carbon in the negative electrode. That is, with respect to the charge amount of 96500 coulombs, the ideal charge reaction is that 1 gram equivalent of lithium ions is extracted from the positive electrode active material and enters the carbon. In the lithium ion secondary battery using a carbon material capable of reversibly doping and dedoping lithium as a main active material in the negative electrode, an organic electrolytic solution is used as the electrolytic solution. The organic electrolytic solution is a lithium salt (for example, Li
PF 6 , LiBF 4, etc.) are dissolved, and the electric conduction in the electrolytic solution is cation (Li + ) and anion (PF
6 − , BF 4 −, etc.).
Therefore, the transport number of lithium ion is not 1. Lithium ions doped into carbon during charging move from the positive electrode to the negative electrode through the electrolytic solution. However, since the transport number of lithium ions is not 1, the negative electrode lacks lithium ions. On the contrary, in the discharge, lithium ions are insufficient in the positive electrode. In particular, charging due to a shortage of lithium ions causes irreversible side reactions other than the doping reaction of lithium ions in carbon in the negative electrode, which causes capacity deterioration. In the present invention, by adding a solid lithium ion conductor mixed with the active material carbon to at least the negative electrode, the lack of lithium ions in the negative electrode has been eliminated, and the cause of capacity deterioration has been successfully eliminated. That is, unlike the organic electrolyte solution in which a lithium salt is dissolved in an organic solvent, the transport number of lithium ions is almost 1 in the ionic conduction by the solid lithium ion conductor, and the lithium ions in the negative electrode are insufficient even at the end of charging. Absent. Therefore, capacity deterioration due to repeated charging and discharging is extremely reduced.
【0006】[0006]
【実施例】以下、実施例により本発明をさらに詳しく説
明する。The present invention will be described in more detail with reference to the following examples.
【0007】実施例1 図1を参照しながら本発明を具体的な円筒型電池につい
て説明する。図1は本実施例の電池の全体構造を示すも
のである。本発明を実施するための発電要素である電池
素子は次のようにして用意した。2800℃で熱処理を
したメソカーボンマイクロビーズ(d002=3.37
Å)の84重量部に4重量部の窒化リチウム(Li
3N)をよく混合し、さらにこアセチレンブブラックの
2重量部、さらに結着剤としてポリフッ化ビニリデン
(PVDF)10重量部を加え、溶剤であるN−メチル
−2−ピロリドンと湿式混合してスラリー(ペースト
状)にした。そしてこのスラリーを負極集電体となる厚
さ0.01mmの銅箔の両面に均一に塗布し、乾燥後ロ
ーラープレス機で加圧成型して帯状の負極(1)を作成
した。Example 1 The present invention will be described with reference to FIG. 1 for a specific cylindrical battery. FIG. 1 shows the overall structure of the battery of this embodiment. A battery element which is a power generation element for carrying out the present invention was prepared as follows. Mesocarbon micro beads heat treated at 2800 ° C. (d 002 = 3.37)
Å) 84 parts by weight of 4 parts by weight of lithium nitride (Li
3 N) is mixed well, 2 parts by weight of this acetylene black and 10 parts by weight of polyvinylidene fluoride (PVDF) as a binder are further added, and the mixture is wet mixed with N-methyl-2-pyrrolidone which is a solvent. It was made into a slurry (paste form). Then, this slurry was uniformly applied to both surfaces of a 0.01 mm-thick copper foil serving as a negative electrode current collector, dried, and then pressure-molded with a roller press to form a strip-shaped negative electrode (1).
【0008】続いて正極は次のようにして用意した。二
酸化マンガンと炭酸リチウムをLiとMnの原子比が
1.077:2の組成比になるように混合し、これを空
気中750℃で20時間焼成してスピネル型リチウムマ
ンガン酸化物(Li1.05Mn1.95O4)を調整
した。このLi1.05Mn1.95O4の90重量部
にグラファイト4重量部とアセチレンブラック3重量部
を加えてよく混合し、さらに結着剤としてポリフッ化ビ
ニリデン3重量部と溶剤であるN−メチル−2−ピロリ
ドンを加えて湿式混合してスラリーにする。このスラリ
ーを正極集電体となる厚さ0.02mmのアルミニウム
箔の両面に均一に塗布し、乾燥後ローラープレス機で加
圧成型して帯状の正極(2)を作成した。Subsequently, the positive electrode was prepared as follows. Manganese dioxide and lithium carbonate were mixed so that the atomic ratio of Li and Mn was 1.077: 2, and the mixture was baked in air at 750 ° C. for 20 hours to spinel-type lithium manganese oxide (Li 1. 05 Mn 1.95 O 4 ). To 90 parts by weight of this Li 1.05 Mn 1.95 O 4 , 4 parts by weight of graphite and 3 parts by weight of acetylene black were added and mixed well, and further 3 parts by weight of polyvinylidene fluoride as a binder and N- which was a solvent. Methyl-2-pyrrolidone is added and wet mixed to form a slurry. This slurry was uniformly applied to both sides of a 0.02 mm-thick aluminum foil which is a positive electrode current collector, dried and pressure-molded with a roller press machine to prepare a strip-shaped positive electrode (2).
【0009】こうして作成した負極(1)と正極(2)
はその間に多孔質ポリプロピレン製セパレータ(3)を
挟んでロール状に巻き上げて、平均外径15.7mmの
巻回体として電池素子を作成した。次にニッケルメッキ
を施した鉄製の電池缶(4)の底部に絶縁板(14)を
設置し、上記電池素子を収納する。電池素子より取り出
した負極リード(5)を上記電池缶の底に溶接し、電池
缶の中に1モル/リットルのLiPF6を溶解したエチ
レンカーボネイト(EC)とジエチルカーボネート(D
EC)の混合溶液を電解液として注入する。その後、電
池素子の上部にも絶縁板(14)を設置し、ガスケット
(15)を嵌め、防爆弁(28)を図1に示すように電
池内部に設置する。電池素子より取り出した正極リード
(7)はこの防爆弁に電解液を注入する前に溶接してお
く。防爆弁の上には正極外部端子となる閉塞蓋体(2
9)をドーナツ型PTCスイッチ(16)を挟んで重
ね、電池缶の縁をかしめて、図1に示す電池構造で外径
16.5mm、高さ65mmの電池(A)を完成した。The negative electrode (1) and the positive electrode (2) thus prepared
A porous polypropylene separator (3) was sandwiched between the rolls and wound up in a roll to prepare a battery element as a wound body having an average outer diameter of 15.7 mm. Next, the insulating plate (14) is placed on the bottom of the nickel-plated iron battery can (4) to house the battery element. The negative electrode lead (5) taken out from the battery element was welded to the bottom of the battery can, and ethylene carbonate (EC) and diethyl carbonate (D) were prepared by dissolving 1 mol / liter of LiPF 6 in the battery can.
A mixed solution of EC) is injected as an electrolytic solution. After that, the insulating plate (14) is also installed on the upper part of the battery element, the gasket (15) is fitted, and the explosion-proof valve (28) is installed inside the battery as shown in FIG. The positive electrode lead (7) taken out from the battery element is welded before injecting the electrolytic solution into this explosion-proof valve. On the explosion-proof valve, a closing lid (2
9) were stacked with a doughnut-type PTC switch (16) in between, and the edges of the battery can were crimped to complete a battery (A) having an outer diameter of 16.5 mm and a height of 65 mm with the battery structure shown in FIG.
【0010】実施例2 市販の炭酸リチウム(Li2CO3)と炭酸コバルト
(CoCO3)をLiとCoの原子比が1.03:1の
組成比になるように混合し、空気中で900℃約10時
間焼成してLiCoO2を得る。焼成後のLiCoO2
は非常に固い塊として得られるので、これを紛砕機にか
けて平均粒径0.02mmの粉末状としてLiCoO2
を調整した。実施例1で調整したLi1.05Mn
1.95O4の75重量部に上記で調整したLioO2
の15重量部とグラファイト4重量部とアセチレンブラ
ック3重量部を加えてよく混合し、さらに結着剤として
ポリフッ化ビニリデン3重量部と溶剤であるN−メチル
−2−ピロリドンを加えて湿式混合してスラリーにす
る。このスラリーを正極集電体となる厚さ0.02mm
のアルミニウム箔の両面に均一に塗布し、乾燥後ローラ
ープレス機で加圧成型して帯状の正極(2b)を作成し
た。後は、この正極(2b)と実施例1で作成した負極
(1)とを組合せ、実施例1と同じように正極と負極の
間には多孔質ポリプロピレン製セパレータ(3)を挟ん
でロール状に巻き上げて、平均外径15.7mmの電池
素子を作成し、全くその後も実施例1と同じにして電池
(B)を作成した。Example 2 Commercially available lithium carbonate (Li 2 CO 3 ) and cobalt carbonate (CoCO 3 ) were mixed so that the atomic ratio of Li and Co was 1.03: 1, and the mixture was heated in air to 900 Calcination is performed for about 10 hours to obtain LiCoO 2 . LiCoO 2 after firing
Since it is obtained as a very hard mass, it is pulverized into a powder with an average particle size of 0.02 mm to obtain LiCoO 2
Was adjusted. Li 1.05 Mn prepared in Example 1
LioO 2 adjusted above to 75 parts by weight of 1.95 O 4.
15 parts by weight of graphite, 4 parts by weight of graphite and 3 parts by weight of acetylene black were added and mixed well, and further 3 parts by weight of polyvinylidene fluoride as a binder and N-methyl-2-pyrrolidone as a solvent were added and wet mixed. To make a slurry. The thickness of this slurry to be a positive electrode current collector is 0.02 mm
The aluminum foil was evenly coated on both sides, dried, and then pressure-molded with a roller press to form a strip-shaped positive electrode (2b). After that, this positive electrode (2b) was combined with the negative electrode (1) prepared in Example 1, and a porous polypropylene separator (3) was sandwiched between the positive electrode and the negative electrode in the same manner as in Example 1 to form a roll shape. Then, a battery element having an average outer diameter of 15.7 mm was wound up, and the battery (B) was manufactured in the same manner as in Example 1 after that.
【0011】実施例3 実施例2で調整した粉末状LiCoO2の90重量部に
グラファイトを4重量部とアセチレンブラック3重量部
を加えてよく混合し、さらに結合剤としてポリフッ化ビ
ニリデン3重量部を溶剤であるN−メチル−2−ピロリ
ドンと湿式混合してスラリーにする。このスラリーを正
極集電体となる厚さ0.02mmのアルミニウム箔の両
面に均一に塗布し、乾燥後ローラープレス機で加圧成型
して帯状の正極(2c)を作成する。後は、この正極
(2c)と実施例1で作成した負極(1)とを組合せ、
実施例1と同じように正極と負極の間には多孔質ポリプ
ロピレン製セパレータ(3)を挟んでロール状に巻き上
げて、平均外径15.7mmの電池素子を作成し、全く
その後も実施例1と同じにして電池(C)を作成した。Example 3 To 90 parts by weight of the powdery LiCoO 2 prepared in Example 2, 4 parts by weight of graphite and 3 parts by weight of acetylene black were added and mixed well, and further 3 parts by weight of polyvinylidene fluoride as a binder. Wet mix with solvent N-methyl-2-pyrrolidone to form a slurry. This slurry is uniformly applied to both sides of a 0.02 mm-thick aluminum foil which will be a positive electrode current collector, dried and then pressure-molded with a roller press to form a strip-shaped positive electrode (2c). Then, the positive electrode (2c) and the negative electrode (1) prepared in Example 1 were combined,
Similar to Example 1, a porous polypropylene separator (3) was sandwiched between the positive electrode and the negative electrode and rolled up to form a battery element having an average outer diameter of 15.7 mm. A battery (C) was prepared in the same manner as above.
【0012】比較例1 従来の方法によって正極活物質にスピネル型リチウムマ
ンガン酸化物を使用し、負極活物質に黒鉛質炭素材料を
使用したリチウムイオン二次電池を作成し、本発明によ
る電池(A)および電池(B)と比較する。2800℃
で熱処理をしたメソカーボンマイクロビーズ(d002
=3.37Å)の86重量部にアセチレンブラックの4
重量部と結着剤としてポリフッ化ビニリデン(PVD
F)10重量部を加え、溶剤であるN−メチル−2−ピ
ロリドンと湿式混合してスラリー(ペースト状)にし
た。そしてこのスラリーを負極集電体となる厚さ0.0
1mmの銅箔の両面に均一に塗布し、乾燥後ローラープ
レス機で加圧成型して帯状の負極(1d)を作成した。
実施例1にて合成したリチウムマンガン酸化物(Li
1.05Mn1.95O4)の90重量部に、グラファ
イト4重量部とアセチレンブラック3重量部を加えてよ
く混合し、さらに結合剤としてポリフッ化ビニリデン3
重量部と溶剤としてN−メチル−2−ピロリドンを加え
て湿式混合してスラリーにする。このスラリーを正極集
電体となる厚さ0.02mmのアルミニウム箔の両面に
均一に塗布し、乾燥後ローラープレス機で加圧成型して
帯状の正極(2d)を作成した。こうして作成した負極
(1d)と正極(2d)は実施例と同じようにその間に
多孔質ポリプロピレン製セパレータ(3)を挟んでロー
ル状に巻き上げて、平均外径15.7mmの巻回体とし
て電池素子を作成し、全くその後も実施例と同じにして
電池(E)を作成した。Comparative Example 1 A lithium ion secondary battery using a spinel type lithium manganese oxide as a positive electrode active material and a graphitic carbon material as a negative electrode active material was prepared by a conventional method. ) And battery (B). 2800 ° C
Mesocarbon microbeads (d 002
= 3.37Å) 86 parts by weight of acetylene black 4
Parts by weight and polyvinylidene fluoride (PVD) as a binder
F) 10 parts by weight was added and wet mixed with N-methyl-2-pyrrolidone as a solvent to form a slurry (paste form). Then, this slurry was used as a negative electrode current collector in a thickness of 0.0
A 1 mm copper foil was evenly applied on both sides, dried, and pressure-molded with a roller press to form a strip-shaped negative electrode (1d).
The lithium manganese oxide synthesized in Example 1 (Li
To 90 parts by weight of 1.05 Mn 1.95 O 4 ), 4 parts by weight of graphite and 3 parts by weight of acetylene black were added and mixed well, and further polyvinylidene fluoride 3 was added as a binder.
Parts by weight and N-methyl-2-pyrrolidone as a solvent are added and wet-mixed to form a slurry. This slurry was uniformly applied on both sides of a 0.02 mm-thick aluminum foil serving as a positive electrode current collector, dried, and then pressure-molded with a roller press to form a strip-shaped positive electrode (2d). The negative electrode (1d) and the positive electrode (2d) thus produced were wound in a roll shape with a porous polypropylene separator (3) sandwiched therebetween in the same manner as in the example to obtain a battery having an average outer diameter of 15.7 mm as a wound battery. A device was prepared, and a battery (E) was prepared in the same manner as in the examples.
【0013】比較例2 正極活物質にリチウムコバルト酸化物(LiCoO2)
を使用し、負極活物質に黒鉛質炭素材料を使用したリチ
ウムイオン二次電池を従来の方法によって作成し、本発
明による電池(C)と比較する。比較例1で作成したも
のと同じ帯状の負極(1d)と実施例3で作成した帯状
の正極(2c)を組合せ、実施例1と同じように正極と
負極の間には多孔質ポリプロピレン製セパレータ(3)
を挟んでロール状に巻き上げて、平均外径15.7mm
の電池素子を作成し、全くその後も実施例1と同じにし
て電池(F)を作成した。Comparative Example 2 Lithium cobalt oxide (LiCoO 2 ) was used as the positive electrode active material.
And a lithium ion secondary battery using a graphite carbon material as the negative electrode active material by a conventional method and compared with the battery (C) according to the present invention. The same strip-shaped negative electrode (1d) as that prepared in Comparative Example 1 and the strip-shaped positive electrode (2c) prepared in Example 3 were combined, and a porous polypropylene separator was provided between the positive and negative electrodes as in Example 1. (3)
It is wound up in a roll shape with the sandwiched between and has an average outer diameter of 15.7 mm.
A battery element was prepared, and the battery (F) was prepared in the same manner as in Example 1 after that.
【0014】充放電サイクル試験 こうして作成した実施例1の電池(A)、実施例2の電
池(B)および比較例1の電池(E)は、いずれも電池
内部の安定化を目的に常温で12時間のエージング期間
を経過させた後、充電電流は200mAで、充電上限電
圧を4.2Vに設定し、第一回目の充電として常温で8
時間の充電を行い、引き続いて第1回目の放電は常温で
800mAの定電流放電にて終止電圧3.0Vまで行っ
た。その後各電池は常温で充放電サイタル試験を行っ
た。充放電サイクル試験においては、充電電流は400
mAで、充電上限電圧は4.2Vに設定して4時間の充
電を行い、放電は800mAの定電流放電にて終止電圧
3.0Vまで行って充放電を繰り返し、その結果を図2
に示した。また実施例3の電池(C)および比較例2の
電池(F)は、同じく電池内部の安定化を目的に常温で
12時間のエージング期間を経過させた後、充電電流は
200mAで、充電上限電圧を4.1Vに設定し、第1
回目の充電として常温で8時間の充電を行い、引き続い
て第1回目の放電は常温で800mAの定電流放電にて
終止電圧3.0Vまで行った。その後各電池は常温で充
放電サイクル試験を行った。充放電サイクル試験におい
ては、充電電流は400mAで、充電上限電圧は4.2
Vに設定して4時間の充電を行い、放電は800mAの
定電流放電にて終止電圧3.0Vまで行って充放電を繰
り返し、その結果を図3に示した。Charge / Discharge Cycle Test The battery (A) of Example 1, the battery (B) of Example 2 and the battery (E) of Comparative Example 1 thus prepared were all kept at room temperature for the purpose of stabilizing the inside of the battery. After the aging period of 12 hours has elapsed, the charging current is 200 mA, the charging upper limit voltage is set to 4.2 V, and the first charging is performed at room temperature for 8 hours.
The battery was charged for a period of time, and then the first discharge was performed at room temperature by a constant current discharge of 800 mA to a final voltage of 3.0V. Thereafter, each battery was subjected to a charge / discharge cyta test at room temperature. In the charge / discharge cycle test, the charging current is 400
At mA, the charge upper limit voltage is set to 4.2V, charging is performed for 4 hours, discharge is performed at a constant current discharge of 800 mA to an end voltage of 3.0V, and charge and discharge are repeated.
It was shown to. The battery (C) of Example 3 and the battery (F) of Comparative Example 2 also had a charging current of 200 mA and an upper limit of charging after a aging period of 12 hours at room temperature for the purpose of stabilizing the inside of the battery. Set the voltage to 4.1V and
As the second charge, the battery was charged at room temperature for 8 hours, and then the first discharge was carried out at room temperature by a constant current discharge of 800 mA to a final voltage of 3.0V. Then, each battery was subjected to a charge / discharge cycle test at room temperature. In the charge / discharge cycle test, the charging current was 400 mA and the charging upper limit voltage was 4.2.
V was charged for 4 hours, discharging was performed at a constant current of 800 mA to a final voltage of 3.0 V, and charging / discharging was repeated. The results are shown in FIG.
【0015】正極活物質にリチウムマンガン複合酸化物
を使用し、負極活物質として黒鉛質炭素材料を使用する
リチウムイオン二次電池では、その充放電サイクル特性
を図2に示したように、従来技術の電池(E)では、充
放電サイクルが進行するにつれ、容量がかなり減ってい
く。100サイクル時点ではすでに初期容量の90%程
の容量となってしまい、200サイクル時点では第1回
目放電容量に対して85%の容量である。これに対し、
少なくとも負極に個体リチウムイオン伝導体としてよく
知られているLi3Nを添加混合した本発明による電池
(A)では、極めて容量劣化の度合いは少なくなり、2
00サイクル時点でも第1回目放電容量の94%が維持
されている。さらに本発明による電池(B)では、容量
劣化の度合いはさらに少なく、200サイクル時点でも
第1回目放電容量の96%が維持されている。電池
(B)では正極中にもイオン伝導助材を含有せしめた実
施例である。つまり正極中に主活物質のリチウムマンガ
ン酸化物に加えてLiCoO2を混合しているが、Li
CoO2はLiがある程度引き抜かれたLi1−XCo
O2においては良好なリチウムイオン伝導体であること
が知られている。正極中に添加したLiCoO2は活物
質としても働き、正極中では一部リチウムイオンが引き
抜かれてLi1−XCoO2(Xはおおよそ0<X<
0.7)の状態で存在するので、イオン伝導補助剤とし
て有効に働き、正極主活物質の充放電効率が良好に持続
されるため、さらに良好なサイクル特性が得られるもの
と思われる。In a lithium ion secondary battery using a lithium manganese composite oxide as a positive electrode active material and a graphitic carbon material as a negative electrode active material, its charge / discharge cycle characteristics are shown in FIG. In the battery (E), the capacity is considerably reduced as the charging / discharging cycle progresses. At the time of 100 cycles, the capacity is already about 90% of the initial capacity, and at the time of 200 cycles, the capacity is 85% of the first discharge capacity. In contrast,
In the battery (A) according to the present invention in which at least the negative electrode is added and mixed with Li 3 N, which is well known as a solid lithium ion conductor, the degree of capacity deterioration is extremely small, and
Even at the time of the 00th cycle, 94% of the first discharge capacity is maintained. Furthermore, in the battery (B) according to the present invention, the degree of capacity deterioration is further small, and 96% of the first discharge capacity is maintained even after 200 cycles. In the battery (B), this is an example in which the positive electrode also contains an ion conduction auxiliary material. That is, LiCoO 2 is mixed in the positive electrode in addition to the lithium manganese oxide as the main active material.
CoO 2 is Li 1-X Co in which Li is extracted to some extent.
It is known that O 2 is a good lithium ion conductor. LiCoO 2 added to the positive electrode also functions as an active material, and in the positive electrode, lithium ions are partially extracted and Li 1-X CoO 2 (X is approximately 0 <X <
Since it exists in the state of 0.7), it works effectively as an ion conduction auxiliary agent, and the charge / discharge efficiency of the positive electrode main active material is favorably maintained, so that it is considered that even better cycle characteristics can be obtained.
【0016】同様に正極主活物質としてLiCoO2を
使用した場合の、本発明による電池(C)と従来技術に
よる電池(F)の比較においても、その充放電サイクル
特性は図3に示したように、従来技術の電池(F)で
は、充放電サイクルが進行するにつれ、容量がかなり減
っていく。100サイクル時点では電池(E)と同じく
初期容量の90%程の容量となってしまい、200サイ
クル時点では第1回目放電容量に対して85%の容量と
なってしまう。これに対し、少なくとも負極にリチウム
イオン伝導体として知られているLi3Nを添加混合し
た電池(C)では極めて劣化度合いは少なくなり、20
0サイクル時点でも第1回目放電容量96%が維持され
ている。Similarly, in the comparison between the battery (C) of the present invention and the battery (F) of the prior art when LiCoO 2 is used as the positive electrode main active material, the charge / discharge cycle characteristics are as shown in FIG. In addition, the capacity of the conventional battery (F) decreases considerably as the charging / discharging cycle progresses. At the time of 100 cycles, the capacity becomes about 90% of the initial capacity like the battery (E), and at the time of 200 cycles, the capacity becomes 85% of the first discharge capacity. On the other hand, in the battery (C) in which at least the negative electrode was mixed with Li 3 N known as a lithium ion conductor, the degree of deterioration was extremely small, and
The first discharge capacity of 96% is maintained even at the 0th cycle.
【0017】なお上述の実施例では本発明の効果がもっ
とも顕著に現れる例として、正極活物質としてLi
1.05Mn1.95O4とLiCoO2を使用した場
合について説明したが、負極にリチウムを可逆的にドー
プおよび脱ドープ可能な炭素材料を主活物質として用い
る非水電解液二次電池であれば、 一般式Li[Mn2−XAX]O4(AはLi、Co、
Ni、Fe等) で示されるスピネル型リチウムマンガン酸化物やLiN
iO2等の他のリチウム含有複合酸化物を正極活物質と
する電池においても、本発明は同様な改善効果を現すも
のである。また上述の実施例では負極活物質に混合する
個体のリチウムイオン伝導体としてLi3Nを使用して
説明したが、Li3Nはそのリチウムの一部をCo等の
他の元素で置換可能であり、Li3−XCoXN(0<
X≦0.5)を負極活物質に混合した場合も上述の実施
例と同様な結果が得られた。その他の個体リチウムイオ
ン伝導体でも同様な添加効果が期待できることはもちろ
んである。In the above-mentioned embodiment, as an example in which the effect of the present invention is most prominent, as the positive electrode active material, Li
The case where 1.05 Mn 1.95 O 4 and LiCoO 2 are used has been described, but in a non-aqueous electrolyte secondary battery using a carbon material capable of reversibly doping and dedoping lithium as a main active material in the negative electrode. If so, the general formula Li [Mn 2−X AX ] O 4 (A is Li, Co,
Ni, Fe, etc.) spinel type lithium manganese oxide and LiN
The present invention also exhibits the same improvement effect in a battery using another lithium-containing composite oxide such as iO 2 as the positive electrode active material. Although Li 3 N is used as a solid lithium ion conductor to be mixed with the negative electrode active material in the above-mentioned embodiments, Li 3 N can replace a part of the lithium with another element such as Co. Yes, Li 3-X Co X N (0 <
When X ≦ 0.5) was mixed with the negative electrode active material, the same result as that of the above-described example was obtained. Needless to say, the similar addition effect can be expected with other solid lithium ion conductors.
【0018】[0018]
【発明の効果】負極にリチウムを可逆的にドープおよび
脱ドープ可能な炭素材料を主活物質として用いる従来の
リチウムイオン二次電池ではその電解液には有機電解液
が使用される。有機電解液は有機溶媒にリチウム塩(例
えばLiPF6、LiBF4等)を溶解したものであっ
て、有機電解液中の電気伝導はカチオン(Li+)とア
ニオン(PF6 −、BF4 −等)の両方のイオンの移動
で行われる。従って従来リチウムイオン二次電池の充放
電反応では、リチウムイオンの輸率は1ではないので、
負極では充電時に、正極では放電時にそれぞれ電極中電
解液にリチウムイオン不足を生じ、特に充電時の負極で
のリチウムイオン不足は電池の容量劣化を引き起こす。
本発明にあっては、少なくとも負極中に、個体のリチウ
ムイオン伝導体を活物質の炭素材料に混じて添加するこ
とで、負極における充電時のリチウムイオン不足を解消
し、容量劣化の原因を取り除くことが出来る。つまり有
機溶媒にリチウム塩を溶解した有機電解液と異なり、個
体のリチウムイオン伝導体によるイオン伝導ではリチウ
ムイオンの輸率はほぼ1であり、充電末期においても負
極中のリチウムイオン不足を来たさない。したがって充
放電の繰り返しによる容量劣化は極度に少なくなる。よ
ってリチウムイオン二次電池のこれまでの大きな欠点で
ある充放電サイクルに伴う容量劣化を大幅に改善でき、
高容量、長寿命のリチウムイオン二次電池が提供できる
ようになり、その工業的価値は大である。In the conventional lithium ion secondary battery using the carbon material capable of reversibly doping and dedoping lithium as the main active material in the negative electrode, the organic electrolyte is used as the electrolyte. The organic electrolytic solution is one in which a lithium salt (for example, LiPF 6 , LiBF 4 etc.) is dissolved in an organic solvent, and the electric conduction in the organic electrolytic solution is cation (Li + ) and anion (PF 6 − , BF 4 − etc.). ) Is done by the transfer of both ions. Therefore, in the charge / discharge reaction of the conventional lithium ion secondary battery, the transport number of lithium ion is not 1,
When the negative electrode is charged and when the positive electrode is discharged, a shortage of lithium ions occurs in the electrolytic solution in the electrode, and in particular, a shortage of lithium ions at the negative electrode during charging causes capacity deterioration of the battery.
In the present invention, at least in the negative electrode, by adding a solid lithium ion conductor mixed with the carbon material of the active material, eliminating the shortage of lithium ions at the time of charging in the negative electrode and eliminating the cause of capacity deterioration. You can That is, unlike the organic electrolyte solution in which a lithium salt is dissolved in an organic solvent, the transport number of lithium ions is almost 1 in the ion conduction by the solid lithium ion conductor, and the lithium ions in the negative electrode are insufficient even at the end of charging. Absent. Therefore, capacity deterioration due to repeated charging and discharging is extremely reduced. Therefore, it is possible to significantly reduce the capacity deterioration due to the charge / discharge cycle, which is a major drawback of lithium-ion secondary batteries.
A high-capacity, long-life lithium-ion secondary battery can be provided, and its industrial value is great.
【図1】実施例における電池の構造を示した模式的断面
図FIG. 1 is a schematic cross-sectional view showing the structure of a battery in an example.
【図2】リチウムマンガン酸化物を正極とする電池のサ
イクル特性図FIG. 2 is a cycle characteristic diagram of a battery using lithium manganese oxide as a positive electrode.
【図3】リチウムコバルト酸化物を正極とする電池のサ
イクル特性図FIG. 3 is a cycle characteristic diagram of a battery using lithium cobalt oxide as a positive electrode.
1は負極、2は正極、3はセパレータ、4は電池缶、5
は負極リード、7は正極リード、14は絶縁板、15は
ガスケット、16はPTC素子 28は防爆弁、29は閉塞蓋体である。1 is a negative electrode, 2 is a positive electrode, 3 is a separator, 4 is a battery can, 5
Is a negative electrode lead, 7 is a positive electrode lead, 14 is an insulating plate, 15 is a gasket, 16 is a PTC element 28 is an explosion-proof valve, and 29 is a closed lid.
─────────────────────────────────────────────────────
─────────────────────────────────────────────────── ───
【手続補正書】[Procedure amendment]
【提出日】平成6年9月20日[Submission date] September 20, 1994
【手続補正1】[Procedure Amendment 1]
【補正対象書類名】明細書[Document name to be amended] Statement
【補正対象項目名】発明の名称[Name of item to be amended] Title of invention
【補正方法】変更[Correction method] Change
【補正内容】[Correction content]
【発明の名称】 非水電解液二次電池Title of invention Non-aqueous electrolyte secondary battery
Claims (2)
を有する電池であって、前記負極にはリチウムを可逆的
にドープおよび脱ドープ可能な炭素材料を主活物質とし
て用いる非水電解液二次電池において、少なくとも前記
負極中には個体のリチウムイオン伝導体を主活物質の炭
素材料に混じて含有せしめたことを特長とする非水電解
液二次電池。1. A battery having a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte, wherein the negative electrode uses a carbon material capable of reversibly doping and de-doping lithium as a main active material. In a secondary battery, a non-aqueous electrolyte secondary battery characterized in that at least the negative electrode contains a solid lithium ion conductor mixed with a carbon material as a main active material.
窒化物であることを特徴とする請求項1記載の非水電解
液二次電池。2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the lithium ion conductor is a lithium-containing nitride.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP6129434A JPH07302589A (en) | 1994-05-06 | 1994-05-06 | Nonaqueous electrolyte secondary battery |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP6129434A JPH07302589A (en) | 1994-05-06 | 1994-05-06 | Nonaqueous electrolyte secondary battery |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH07302589A true JPH07302589A (en) | 1995-11-14 |
Family
ID=15009390
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP6129434A Pending JPH07302589A (en) | 1994-05-06 | 1994-05-06 | Nonaqueous electrolyte secondary battery |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH07302589A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5565600B2 (en) * | 2011-03-14 | 2014-08-06 | 三菱自動車工業株式会社 | Capacity recovery method for lithium ion battery |
-
1994
- 1994-05-06 JP JP6129434A patent/JPH07302589A/en active Pending
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5565600B2 (en) * | 2011-03-14 | 2014-08-06 | 三菱自動車工業株式会社 | Capacity recovery method for lithium ion battery |
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