JP2003036846A - Lithium secondary battery - Google Patents
Lithium secondary batteryInfo
- Publication number
- JP2003036846A JP2003036846A JP2001222415A JP2001222415A JP2003036846A JP 2003036846 A JP2003036846 A JP 2003036846A JP 2001222415 A JP2001222415 A JP 2001222415A JP 2001222415 A JP2001222415 A JP 2001222415A JP 2003036846 A JP2003036846 A JP 2003036846A
- Authority
- JP
- Japan
- Prior art keywords
- positive electrode
- negative electrode
- lithium
- capacity
- electrode plate
- 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
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、特に、リチウムマンガン複酸化物を正極活物質の
主体とするリチウム二次電池に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium secondary battery, and more particularly to a lithium secondary battery containing lithium manganese composite oxide as a main component of a positive electrode active material.
【０００２】[0002]
【従来の技術】従来、一般に広く用いられているリチウ
ム二次電池は、正極にコバルト酸リチウムを用いたもの
が主流である。しかし、コバルト酸リチウムは、原料と
なるコバルトの埋蔵量が少なくコスト高となるため、代
わりの正極材料として資源量が豊富なマンガンを含むリ
チウムマンガン複酸化物を使用する動きが活発に進んで
いる。そのリチウムマンガン複酸化物であっても、コバ
ルト酸リチウムほどではないが、一般に負極に使用され
る炭素材と比較すれば、未だコスト高である。このよう
なリチウムマンガン複酸化物の中で、現在主に使用され
ているものはスピネル構造のリチウムマンガン複酸化物
である。2. Description of the Related Art Lithium secondary batteries, which have been widely used in the past, mainly use lithium cobalt oxide as a positive electrode. However, since lithium cobalt oxide has a low reserve of cobalt as a raw material and is costly, there is an active movement to use lithium manganese complex oxide containing manganese, which has abundant resources, as an alternative cathode material. . Even with the lithium manganese composite oxide, the cost is still higher than that of the carbon material generally used for the negative electrode, though not so much as lithium cobalt oxide. Among such lithium manganese composite oxides, the one mainly used at present is a spinel structure lithium manganese composite oxide.
【０００３】一般に、スピネル構造のリチウムマンガン
複酸化物は活物質単体で見た場合の不可逆容量率が５％
以下であり、また、負極に使用される炭素材の不可逆容
量率は一般に５％以上である。不可逆容量率は、金属リ
チウムを対極とし、初期１回から５回程度充放電を繰り
返した際の充電容量の総和と放電容量の総和の差である
不可逆容量を初回充電容量で除し、それを百分率で表現
したものである。従って、正極活物質にスピネル構造の
リチウムマンガン複酸化物を、負極活物質に炭素材を使
用した電池では、正極の不可逆容量率よりも負極の不可
逆容量率が大きいため、初回充電時に正極から負極に移
動したリチウムイオンの全量が放電時に負極から正極に
戻ることができなくなり、高価な正極活物質の可逆容量
を十分に使用することが出来ず、非経済的であった。In general, the spinel structure lithium manganese oxide has an irreversible capacity ratio of 5% when viewed as an active material alone.
Further, the irreversible capacity ratio of the carbon material used for the negative electrode is generally 5% or more. The irreversible capacity ratio is calculated by dividing the irreversible capacity, which is the difference between the total charge capacity and the total discharge capacity when the charge and discharge are repeated about 1 to 5 times with the lithium metal as the counter electrode, and dividing it by the initial charge capacity. It is expressed as a percentage. Therefore, in a battery using a spinel structure lithium manganese composite oxide as the positive electrode active material and a carbon material as the negative electrode active material, the irreversible capacity ratio of the negative electrode is larger than the irreversible capacity ratio of the positive electrode. It was uneconomical because the entire amount of lithium ions transferred to the anode could not return from the negative electrode to the positive electrode during discharge, and the reversible capacity of the expensive positive electrode active material could not be fully used.
【０００４】また、充電中に負極表面で金属リチウムが
析出することによりセパレータを貫通し、短絡に至ると
いう問題があった。これを防止するためには、正極充電
容量よりも負極充電容量を大きくする必要があった。Further, there is a problem in that metallic lithium is deposited on the surface of the negative electrode during charging and penetrates the separator, resulting in a short circuit. In order to prevent this, it is necessary to make the negative electrode charge capacity larger than the positive electrode charge capacity.
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、上述の
ように正極の不可逆容量率よりも負極の不可逆容量率が
大きいため、正極活物質の可逆容量を有効に使用するこ
とができず、高容量の電池を得ることができなかった。
これを避けるために負極材料をできるだけ少なくして負
極の不可逆容量を減少させた場合には、充放電にかかわ
る活物質量も少なくなるため負極材料を高利用率で使用
することが必要となるので、負極材料の負担が大きくな
り得られた電池は一般に短寿命であるという問題があっ
た。However, since the irreversible capacity ratio of the negative electrode is larger than the irreversible capacity ratio of the positive electrode as described above, the reversible capacity of the positive electrode active material cannot be effectively used, resulting in a high capacity. I couldn't get a battery.
In order to avoid this, if the amount of the negative electrode material is reduced as much as possible and the irreversible capacity of the negative electrode is reduced, the amount of the active material involved in charging / discharging also decreases, so it is necessary to use the negative electrode material at a high utilization rate. However, the burden of the negative electrode material becomes large, and thus the obtained battery has a problem that the life is generally short.
【０００６】本発明は、上記事案に鑑み、高容量かつ長
寿命のリチウム二次電池を提供することを課題とする。In view of the above problems, it is an object of the present invention to provide a lithium secondary battery with high capacity and long life.
【０００７】[0007]
【課題を解決するための手段】上記課題を解決するため
に、本発明は、リチウムマンガン複酸化物を正極活物質
の主体とするリチウム二次電池において、前記リチウム
マンガン複酸化物は結晶構造が異なる２種以上のリチウ
ムマンガン複酸化物を含み、かつ、前記正極の可逆容量
を負極の可逆容量以下としたものである。In order to solve the above-mentioned problems, the present invention provides a lithium secondary battery comprising a lithium manganese compound oxide as a main active material of a positive electrode, wherein the lithium manganese compound oxide has a crystal structure. It contains two or more different lithium manganese oxides, and the reversible capacity of the positive electrode is not more than the reversible capacity of the negative electrode.
【０００８】本発明では、正極の可逆容量を負極の可逆
容量以下とすることにより、充電時に正極から離脱して
負極に移動するリチウムイオンの量が負極の可逆容量以
下となり、負極の負担を低減することができるので、負
極の劣化を抑制することができると共に、充電時に正極
から負極に移動したリチウムイオンと同量のリチウムイ
オンが放電時には正極に挿入され、正極を有効に活用す
ることができるので、電池容量を高めることができる。
このような効果を得るためのリチウムマンガン複酸化物
として、結晶構造の異なる２種以上のリチウムマンガン
複酸化物を配合したものを用いる。In the present invention, the reversible capacity of the positive electrode is set to be less than or equal to the reversible capacity of the negative electrode, so that the amount of lithium ions that are separated from the positive electrode and moved to the negative electrode during charging is less than or equal to the reversible capacity of the negative electrode, thus reducing the load on the negative electrode. Therefore, the deterioration of the negative electrode can be suppressed, and the same amount of lithium ions that have moved from the positive electrode to the negative electrode during charging can be inserted into the positive electrode during discharging, so that the positive electrode can be effectively utilized. Therefore, the battery capacity can be increased.
As a lithium manganese composite oxide for obtaining such an effect, a mixture of two or more kinds of lithium manganese composite oxides having different crystal structures is used.
【０００９】この場合において、リチウムマンガン複酸
化物に層状構造リチウムマンガン複酸化物とスピネル構
造リチウムマンガン複酸化物とを配合して用いるように
すれば、層状構造リチウムマンガン複酸化物の結晶の層
間にリチウムイオンが挿入・離脱されるので、より高容
量の電池とすることができる。このとき、層状構造リチ
ウムマンガン複酸化物とスピネル構造リチウムマンガン
複酸化物との配合重量比は３０：７０〜７５：２５の範
囲が好ましい。また、負極活物質に結晶性炭素材を用い
たときには、負極の不可逆容量が少なく可逆容量が多い
ため、正極の不可逆容量率を１０％以上とすることによ
り、負極の可逆容量分のリチウムイオンを離脱させるこ
とができるので、負極の負担を低減して長寿命とするこ
とができる。逆に、負極活物質に無定型炭素材を用いた
ときには、負極の可逆容量が少ないため、正極の不可逆
容量率を２０％以上とすることにより、充電時に負極に
移動するリチウムイオン量を減少させることができるの
で、負極の負担を低減して長寿命とすることができる。In this case, if the layered structure lithium manganese composite oxide and the spinel structure lithium manganese composite oxide are mixed and used in the lithium manganese composite oxide, the layers of the crystal of the layered structure lithium manganese composite oxide can be used. Since lithium ions are inserted into and removed from the battery, a battery with higher capacity can be obtained. At this time, the compounding weight ratio of the layered structure lithium manganese composite oxide and the spinel structure lithium manganese composite oxide is preferably in the range of 30:70 to 75:25. Further, when a crystalline carbon material is used as the negative electrode active material, the irreversible capacity of the negative electrode is small and the reversible capacity is large. Therefore, by setting the irreversible capacity rate of the positive electrode to 10% or more, lithium ions corresponding to the reversible capacity of the negative electrode can be obtained. Since it can be detached, the load on the negative electrode can be reduced and the life can be extended. On the contrary, when an amorphous carbon material is used as the negative electrode active material, the reversible capacity of the negative electrode is small. Therefore, by setting the irreversible capacity ratio of the positive electrode to 20% or more, the amount of lithium ions transferred to the negative electrode during charging is reduced. Therefore, the burden on the negative electrode can be reduced and the life can be extended.
【００１０】[0010]
【発明の実施の形態】以下、本発明のリチウム二次電池
を円筒型リチウムイオン電池に適用した実施の形態につ
いて説明する。BEST MODE FOR CARRYING OUT THE INVENTION Embodiments in which the lithium secondary battery of the present invention is applied to a cylindrical lithium ion battery will be described below.
【００１１】＜正極板＞結晶構造の異なるリチウムマン
ガン複酸化物としての層状構造マンガン酸リチウムとス
ピネル構造マンガン酸リチウムを後述する重量比で配合
したマンガン酸リチウム粉末を正極活物質に用いた。マ
ンガン酸リチウム粉末と、導電剤として鱗片状黒鉛と、
結着剤としてポリフッ化ビニリデンと、を例えば８６：
９：５などの重量比で配合した正極合剤に分散溶媒とし
てＮ−メチルピロリドンを添加、混練してスラリとし
た。このスラリを厚さ２０μｍのアルミ箔（正極集電
体）の両面に塗布した。その後乾燥、プレス、裁断して
後述する所定寸法の正極板を得た。この正極板の一部を
切り取り、金属リチウムを対極として、初期１回から５
回までの充放電を繰り返し、充電容量と放電容量を測定
して、正極板の初回充電容量、不可逆容量率、可逆容量
を求めた。なお、充放電電圧範囲は４．５Ｖから３．２
Ｖ（Ｌｉ／Ｌｉ＋基準）とし、正極活物質中のリチウム
イオンが離脱する反応を充電反応とした。<Positive Electrode Plate> A lithium manganate powder having a layered structure lithium manganate as a lithium manganese composite oxide having a different crystal structure and a spinel structure lithium manganate mixed in a weight ratio described below was used as a positive electrode active material. Lithium manganate powder, and flake graphite as a conductive agent,
Polyvinylidene fluoride as a binder, for example, 86:
N-methylpyrrolidone was added as a dispersion solvent to the positive electrode mixture mixed at a weight ratio of 9: 5, and kneaded to obtain a slurry. This slurry was applied to both sides of a 20 μm thick aluminum foil (positive electrode current collector). Then, it was dried, pressed and cut to obtain a positive electrode plate having a predetermined size described later. Cut off a part of this positive electrode plate, and use metallic lithium as a counter electrode from the initial 1 to 5
The charge capacity and the discharge capacity were measured by repeating charge and discharge up to times, and the initial charge capacity, the irreversible capacity rate, and the reversible capacity of the positive electrode plate were obtained. The charging / discharging voltage range is from 4.5V to 3.2.
V (Li / Li + basis) was used, and the reaction in which lithium ions in the positive electrode active material desorb was defined as the charging reaction.
【００１２】＜負極板＞負極活物質に無定型炭素材とし
ての非晶質炭素粉末又は結晶性炭素材としての黒鉛粉末
を用い、これに結着剤としてポリフッ化ビニリデンを例
えば９２：８などの重量比で添加、混合して負極合剤を
作製した。この負極合剤に添加剤としてカーボンブラッ
クを固形分中の割合が５重量％になるように添加し、分
散溶媒としてＮ−メチルピロリドンを添加、混練してス
ラリとした。このスラリを厚さ１０μｍの圧延銅箔（負
極集電体）の両面に塗布した。その後乾燥、プレス、裁
断して後述する所定寸法の負極板を得た。この負極板の
一部を切り取り、上述した正極板と同様に金属リチウム
を対極として充電容量と放電容量を測定し、負極板の初
回充電容量、不可逆容量率、可逆容量を求めた。なお、
充放電電圧範囲は１．５Ｖから０Ｖ（Ｌｉ／Ｌｉ＋基
準）とし、負極活物質中にリチウムイオンが挿入する反
応を充電反応とした。<Negative Electrode Plate> An amorphous carbon powder as an amorphous carbon material or a graphite powder as a crystalline carbon material is used as a negative electrode active material, and polyvinylidene fluoride as a binder, for example, 92: 8. A negative electrode mixture was prepared by adding and mixing in a weight ratio. Carbon black was added as an additive to this negative electrode mixture so that the ratio in the solid content was 5% by weight, and N-methylpyrrolidone was added as a dispersion solvent and kneaded to obtain a slurry. This slurry was applied to both sides of a rolled copper foil (negative electrode current collector) having a thickness of 10 μm. Then, it was dried, pressed and cut to obtain a negative electrode plate having a predetermined size described later. A part of the negative electrode plate was cut out, and the charge capacity and the discharge capacity were measured using metallic lithium as a counter electrode in the same manner as the positive electrode plate described above, and the initial charge capacity, irreversible capacity rate and reversible capacity of the negative electrode plate were obtained. In addition,
The charge / discharge voltage range was 1.5 V to 0 V (Li / Li + reference), and the reaction in which lithium ions were inserted into the negative electrode active material was the charge reaction.
【００１３】上述のように作製した正極板の可逆容量が
負極板の可逆容量以下となるように正極板と負極板を組
み合わせ、以下のようにして円筒型リチウムイオン電池
を作製した。また、負極活物質に黒鉛を用いたときには
不可逆容量率が１０％以上の正極板と組み合わせるよう
にし、非晶質炭素を用いたときには不可逆容量率が２０
％以上の正極板と組み合わせるようにした。The positive electrode plate and the negative electrode plate were combined so that the reversible capacity of the positive electrode plate manufactured as described above was less than or equal to that of the negative electrode plate, and a cylindrical lithium ion battery was manufactured as follows. When graphite is used as the negative electrode active material, it is combined with a positive electrode plate having an irreversible capacity ratio of 10% or more, and when amorphous carbon is used, the irreversible capacity ratio is 20%.
% Or more positive electrode plates.
【００１４】＜電池の作製＞図１に示すように、上記正
極板と負極板とを、これら両極板が直接接触しないよう
に厚さ４０μｍのポリエチレン製セパレータと共に捲回
し捲回群１とした。このとき、正極リード片と負極リー
ド片とが、それぞれ捲回群１の互いに反対側の両端面に
位置するようにした。また、正極板、負極板、セパレー
タの長さを調整し、捲回群１の直径を３８±０．１ｍｍ
とした。<Production of Battery> As shown in FIG. 1, the positive electrode plate and the negative electrode plate were wound together with a polyethylene separator having a thickness of 40 μm so as to prevent the two electrode plates from directly contacting each other to form a winding group 1. At this time, the positive electrode lead piece and the negative electrode lead piece were respectively positioned on opposite end surfaces of the winding group 1. In addition, the lengths of the positive electrode plate, the negative electrode plate, and the separator are adjusted so that the diameter of the winding group 1 is 38 ± 0.1 mm.
And
【００１５】正極リード片を変形させ、その全てを、捲
回群１の軸芯のほぼ延長線上にある正極集電リング４の
周囲から一体に張り出している鍔部周面付近に集合、接
触させた後、正極リード片と鍔部周面とを超音波溶接し
て正極リード片を鍔部周面に接続した。一方、負極集電
リング５と負極リード片との接続操作も、正極集電リン
グ４と正極リード片との接続操作と同様に実施した。The positive electrode lead pieces are deformed, and all of them are gathered and contacted in the vicinity of the peripheral surface of the flange portion which integrally projects from the periphery of the positive electrode current collecting ring 4 which is almost on the extension line of the axis of the winding group 1. Then, the positive electrode lead piece and the peripheral surface of the flange portion were ultrasonically welded to connect the positive electrode lead piece to the peripheral surface of the flange portion. On the other hand, the operation of connecting the negative electrode current collecting ring 5 and the negative electrode lead piece was performed in the same manner as the operation of connecting the positive electrode current collecting ring 4 and the positive electrode lead piece.
【００１６】その後、正極集電リング４の鍔部周面全周
に絶縁被覆を施し、捲回群１をニッケルメッキが施され
たスチール製の電池容器２内に挿入した。電池容器２の
外径は４０ｍｍ、内径は３９ｍｍである。Thereafter, the circumference of the flange portion of the positive electrode current collecting ring 4 was covered with an insulating coating, and the winding group 1 was inserted into a nickel-plated steel battery container 2. The battery container 2 has an outer diameter of 40 mm and an inner diameter of 39 mm.
【００１７】負極集電リング５には予め電気的導通のた
めの負極リード板が溶接されており、電池容器２内に捲
回群１を挿入後、電池容器２の底部と負極リード板とを
溶接した。一方、正極集電リング４には、予め複数枚の
アルミニウム製のリボンを重ね合わせて構成した正極リ
ードを溶接しておき、正極リードの他端を、電池容器２
を封口するための電池蓋３の下面に溶接した。電池蓋
は、蓋ケースと、気密を保つ弁押さえと、開裂弁とで構
成されており、これらが積層されて蓋ケースの周縁をカ
シメることによって組立てられている。A negative electrode lead plate for electrical conduction is welded to the negative electrode current collecting ring 5 in advance, and after the winding group 1 is inserted into the battery container 2, the bottom of the battery container 2 and the negative electrode lead plate are joined together. Welded. On the other hand, a positive electrode lead formed by stacking a plurality of aluminum ribbons in advance is welded to the positive electrode current collecting ring 4, and the other end of the positive electrode lead is connected to the battery container 2
Was welded to the lower surface of the battery lid 3 for sealing. The battery lid is composed of a lid case, a valve retainer for keeping airtightness, and a cleaving valve, and these are stacked and assembled by caulking the periphery of the lid case.
【００１８】非水電解液を所定量電池容器２内に注入
し、その後、正極リードを折りたたむようにして電池蓋
３で電池容器２に蓋をし、ＥＰＤＭ樹脂製ガスケットを
介してカシメて密封することにより円筒形リチウムイオ
ン電池１０を完成させた。A predetermined amount of non-aqueous electrolyte is injected into the battery container 2, and then the battery container 2 is covered with the battery cover 3 so that the positive electrode lead is folded, and the battery container 2 is caulked and sealed with an EPDM resin gasket. Thus, the cylindrical lithium-ion battery 10 was completed.
【００１９】非水電解液には、エチレンカーボネートと
ジメチルカーボネートの混合溶液中へ６フッ化リン酸リ
チウム（ＬｉＰＦ６）を１モル／リットル溶解したもの
を用いた。As the non-aqueous electrolyte, a solution prepared by dissolving 1 mol / liter of lithium hexafluorophosphate (LiPF 6 ) in a mixed solution of ethylene carbonate and dimethyl carbonate was used.
【００２０】[0020]
【実施例】次に、本実施形態に従って作製した円筒形リ
チウムイオン電池１０の実施例について説明する。な
お、比較のために作製した比較例の電池についても併記
する。EXAMPLES Next, examples of the cylindrical lithium-ion battery 10 manufactured according to this embodiment will be described. The battery of the comparative example prepared for comparison is also shown.
【００２１】＜実施例１＞下表１及び下表２に示すよう
に、実施例１では、正極活物質に層状構造マンガン酸リ
チウムとスピネル構造マンガン酸リチウムを重量比５
５：４５で配合したものを用い、負極活物質に非晶質炭
素を用いた。正極合剤層のかさ密度（以下、正極かさ密
度という。）は２．４ｇ／ｃｍ３とし、正極板の寸法は
幅８２ｍｍ、長さ２５９０ｍｍ、厚さ０．１５４ｍｍ、
重量は８０ｇとした。また、負極合剤層のかさ密度（以
下、負極かさ密度という。）は１．０ｇ／ｃｍ３とし、
負極板の寸法は幅８６ｍｍ、長さ２７１０ｍｍ、厚さ
０．１５２ｍｍ、重量は５３ｇとした。正極板の初回充
電容量は１１．２Ａｈ、不可逆容量率は２２％、可逆容
量は８．７Ａｈであり、負極板の初回充電容量は１１．
７Ａｈ、不可逆容量率は２０％、可逆容量は９．３Ａｈ
であった。<Example 1> As shown in Tables 1 and 2 below, in Example 1, a layered structure of lithium manganate and a spinel structure of lithium manganate were used in a weight ratio of 5 as the positive electrode active material.
Amorphous carbon was used as the negative electrode active material, using the mixture of 5:45. The bulk density of the positive electrode mixture layer (hereinafter referred to as the positive electrode bulk density) is 2.4 g / cm 3, and the size of the positive electrode plate is 82 mm in width, 2590 mm in length, and 0.154 mm in thickness.
The weight was 80 g. The bulk density of the negative electrode mixture layer (hereinafter referred to as the negative electrode bulk density) is 1.0 g / cm 3 ,
The dimensions of the negative electrode plate were 86 mm in width, 2710 mm in length, 0.152 mm in thickness, and 53 g in weight. The positive electrode plate had an initial charge capacity of 11.2 Ah, the irreversible capacity rate was 22%, the reversible capacity was 8.7 Ah, and the negative electrode plate had an initial charge capacity of 11.
7Ah, irreversible capacity rate 20%, reversible capacity 9.3Ah
Met.
【００２２】＜実施例２＞下表１及び下表２に示すよう
に、実施例２では、正極活物質に層状構造マンガン酸リ
チウムとスピネル構造マンガン酸リチウムを重量比７
５：２５で配合したものを用い、負極板は実施例１と同
一仕様のものを用いた。正極かさ密度は２．４ｇ／ｃｍ
３とし、正極板の寸法は幅８２ｍｍ、長さ２５９０ｍ
ｍ、厚さ０．１２５ｍｍ、重量は６５ｇとした。正極板
の初回充電容量は１０．２Ａｈ、不可逆容量率は２９
％、可逆容量は７．２Ａｈであった。<Example 2> As shown in Tables 1 and 2 below, in Example 2, a layered structure lithium manganate and a spinel structure lithium manganate were used in a weight ratio of 7 as a positive electrode active material.
The negative electrode plate having the same specifications as in Example 1 was used. Positive electrode bulk density is 2.4 g / cm
3 and then, the dimensions of the positive electrode plate width 82mm, length 2590m
m, the thickness was 0.125 mm, and the weight was 65 g. The initial charge capacity of the positive electrode plate is 10.2 Ah, and the irreversible capacity rate is 29.
%, The reversible capacity was 7.2 Ah.
【００２３】＜実施例３＞下表１及び下表２に示すよう
に、実施例３では、正極活物質に層状構造マンガン酸リ
チウムとスピネル構造マンガン酸リチウムを重量比３
０：７０で配合したものを用い、負極活物質に黒鉛を用
いた。正極かさ密度は２．４ｇ／ｃｍ３とし、正極板の
寸法は幅８２ｍｍ、長さ２６２０ｍｍ、厚さ０．１９０
ｍｍ、重量は９９ｇとした。また、負極かさ密度は１．
８ｇ／ｃｍ３とし、負極板の寸法は幅８６ｍｍ、長さ２
７４０ｍｍ、厚さ０．１１３ｍｍ、重量は６４ｇとし
た。正極板の初回充電容量は１１．４Ａｈ、不可逆容量
率は１３％、可逆容量は９．９Ａｈであり、負極板の初
回充電容量は１１．８Ａｈ、不可逆容量率は１０％、可
逆容量は１０．６Ａｈであった。<Example 3> As shown in Tables 1 and 2 below, in Example 3, the positive electrode active material was composed of layered structure lithium manganate and spinel structure lithium manganate in a weight ratio of 3;
Graphite was used as the negative electrode active material by using the mixture prepared at 0:70. The bulk density of the positive electrode was 2.4 g / cm 3, and the dimensions of the positive electrode plate were a width of 82 mm, a length of 2,620 mm, and a thickness of 0.190.
mm, and the weight was 99 g. The bulk density of the negative electrode is 1.
The size of the negative electrode plate was 8 g / cm 3 and the width was 86 mm and the length was 2
The thickness was 740 mm, the thickness was 0.113 mm, and the weight was 64 g. The positive electrode plate had an initial charge capacity of 11.4 Ah, an irreversible capacity ratio of 13%, and a reversible capacity of 9.9 Ah. The negative electrode plate had an initial charge capacity of 11.8 Ah, an irreversible capacity ratio of 10%, and a reversible capacity of 10. It was 6 Ah.
【００２４】[0024]
【表１】 [Table 1]
【００２５】[0025]
【表２】 [Table 2]
【００２６】＜実施例４＞表１及び表２に示すように、
実施例４では、正極活物質に層状構造マンガン酸リチウ
ムとスピネル構造マンガン酸リチウムを重量比５０：５
０で配合したものを用い、負極板は実施例３と同一仕様
のものを用いた。正極かさ密度は２．４ｇ／ｃｍ３と
し、正極板の寸法は幅８２ｍｍ、長さ２６２０ｍｍ、厚
さ０．１５９ｍｍ、重量は８３ｇとした。正極板の初回
充電容量は１１．２Ａｈ、不可逆容量率は２０％、可逆
容量は８．９Ａｈであった。<Example 4> As shown in Tables 1 and 2,
In Example 4, a layered structure lithium manganate and a spinel structure lithium manganate were used as a positive electrode active material in a weight ratio of 50: 5.
0 was used, and the negative electrode plate had the same specifications as in Example 3. The bulk density of the positive electrode was 2.4 g / cm 3, and the size of the positive electrode plate was 82 mm in width, 2620 mm in length, 0.159 mm in thickness, and 83 g in weight. The positive electrode plate had an initial charge capacity of 11.2 Ah, an irreversible capacity rate of 20%, and a reversible capacity of 8.9 Ah.
【００２７】＜比較例１＞表１及び表２に示すように、
比較例１では、正極活物質にスピネル構造マンガン酸リ
チウムのみを用い、負極活物質に非晶質炭素を用いた。
正極かさ密度は２．７ｇ／ｃｍ３とし、正極板の寸法は
幅８２ｍｍ、長さ２１２０ｍｍ、厚さ０．２４０ｍｍ、
重量は１１１ｇとした。また、負極かさ密度は１．０ｇ
／ｃｍ３とし、負極板の寸法は幅８６ｍｍ、長さ２７１
０ｍｍ、厚さ０．１５２ｍｍ、重量は４４ｇとした。正
極板の初回充電容量は９．２Ａｈ、不可逆容量率は４
％、可逆容量は８．８Ａｈであり、負極板の初回充電容
量は９．５Ａｈ、不可逆容量率は２０％、可逆容量は
７．６Ａｈであった。<Comparative Example 1> As shown in Tables 1 and 2,
In Comparative Example 1, only the spinel structure lithium manganate was used as the positive electrode active material, and the amorphous carbon was used as the negative electrode active material.
The bulk density of the positive electrode was 2.7 g / cm 3, and the dimensions of the positive electrode plate were a width of 82 mm, a length of 2120 mm, and a thickness of 0.240 mm,
The weight was 111 g. The negative electrode bulk density is 1.0 g.
/ Cm 3 , the size of the negative electrode plate is 86 mm in width and 271 in length
The thickness was 0 mm, the thickness was 0.152 mm, and the weight was 44 g. The positive electrode plate has an initial charge capacity of 9.2 Ah and an irreversible capacity ratio of 4
%, The reversible capacity was 8.8 Ah, the initial charge capacity of the negative electrode plate was 9.5 Ah, the irreversible capacity rate was 20%, and the reversible capacity was 7.6 Ah.
【００２８】＜比較例２＞表１及び表２に示すように、
比較例２では、正極活物質にスピネル構造マンガン酸リ
チウムのみを用い、負極活物質に黒鉛を用いた。正極か
さ密度は２．７ｇ／ｃｍ３とし、正極板の寸法は幅８２
ｍｍ、長さ２３２０ｍｍ、厚さ０．２４０ｍｍ、重量は
１２１ｇとした。また、負極かさ密度は１．８ｇ／ｃｍ
３とし、負極板の寸法は幅８６ｍｍ、長さ２４４０ｍ
ｍ、厚さ０．１１３ｍｍ、重量は７２ｇとした。正極板
の初回充電容量は１０．０Ａｈ、不可逆容量率は４％、
可逆容量は９．６Ａｈであり、負極板の初回充電容量は
１０．５Ａｈ、不可逆容量率は１０％、可逆容量は９．
４Ａｈであった。<Comparative Example 2> As shown in Tables 1 and 2,
In Comparative Example 2, only spinel structure lithium manganate was used as the positive electrode active material, and graphite was used as the negative electrode active material. The bulk density of the positive electrode is 2.7 g / cm 3, and the size of the positive electrode plate is width 82.
mm, length 2320 mm, thickness 0.240 mm, and weight 121 g. The bulk density of the negative electrode is 1.8 g / cm.
3 and then, the size of the negative electrode plate width 86 mm, length 2440m
m, the thickness was 0.113 mm, and the weight was 72 g. The initial charge capacity of the positive electrode plate is 10.0 Ah, the irreversible capacity rate is 4%,
The reversible capacity was 9.6 Ah, the initial charge capacity of the negative electrode plate was 10.5 Ah, the irreversible capacity rate was 10%, and the reversible capacity was 9.
It was 4 Ah.
【００２９】上記実施例及び比較例の電池について、電
池容量、正極板の可逆容量に対する電池容量の割合であ
る正極利用率及び負極板の可逆容量に対する電池容量の
割合である負極利用率を下表３に示す。また、それぞれ
の電池容量を定格容量とし、その定格容量の８時間率の
電流値で、充電時の終止電圧を４．３Ｖ、放電時の終止
電圧を３．０Ｖとして充放電サイクルを繰り返したとき
の、サイクル数に対する容量維持率の変化を図２に示
す。For the batteries of the above Examples and Comparative Examples, the following table shows the battery capacity, the positive electrode utilization rate, which is the ratio of the battery capacity to the reversible capacity of the positive electrode plate, and the negative electrode utilization rate, which is the ratio of the battery capacity to the reversible capacity of the negative electrode plate. 3 shows. In addition, when each battery capacity is rated capacity and the rated voltage has a current value of 8 hours, the end voltage during charging is 4.3 V and the end voltage during discharging is 3.0 V, and the charge / discharge cycle is repeated. FIG. 2 shows the change in the capacity retention rate with respect to the number of cycles.
【００３０】[0030]
【表３】 [Table 3]
【００３１】表３に示したように、実施例１〜実施例４
の電池は、正極板の不可逆容量が負極板の不可逆容量よ
りも大きい（表２参照）ため、電池容量は正極板の可逆
容量と同じであった。これに対して、比較例１及び比較
例２の電池は、負極板の不可逆容量が正極板の不可逆容
量よりも大きいため初回充電時に正極板から負極板に移
動したリチウムイオンの全量が放電時に正極に戻らない
ので、電池容量は正極板の初回充電容量から負極板の不
可逆容量が差し引かれた結果となった。As shown in Table 3, Examples 1 to 4
In the battery of No. 3, the irreversible capacity of the positive electrode plate was larger than that of the negative electrode plate (see Table 2), and therefore the battery capacity was the same as the reversible capacity of the positive electrode plate. On the other hand, in the batteries of Comparative Example 1 and Comparative Example 2, since the irreversible capacity of the negative electrode plate was larger than the irreversible capacity of the positive electrode plate, the total amount of lithium ions transferred from the positive electrode plate to the negative electrode plate at the time of initial charging was the positive electrode at the time of discharging. Therefore, the battery capacity was the result of subtracting the irreversible capacity of the negative electrode plate from the initial charge capacity of the positive electrode plate.
【００３２】また、正極の可逆容量を負極の可逆容量以
下とした実施例１〜実施例４の電池は、正極の可逆容量
を負極の可逆容量以上とした比較例１及び比較例２の電
池と比較して、正極利用率が１００％と高く、電池容量
も高くなった。正極利用率、負極利用率は、それぞれ正
極、負極の可逆容量と逆比例の関係にあるので、可逆容
量の低い方が利用率は高くなる。更に、図２から明らか
なように、実施例１〜実施例４の電池は、サイクル数２
００回後でも９６％以上の容量維持率を示した。従っ
て、実施例１〜実施例４の電池は、正極活物質を効率よ
く使用しており経済的であると共に、高容量かつ長寿命
の電池であった。The batteries of Examples 1 to 4 in which the reversible capacity of the positive electrode was less than or equal to the reversible capacity of the negative electrode were the same as those of Comparative Examples 1 and 2 in which the reversible capacity of the positive electrode was greater than or equal to the reversible capacity of the negative electrode. In comparison, the positive electrode utilization rate was as high as 100%, and the battery capacity was also high. Since the positive electrode utilization rate and the negative electrode utilization rate are inversely proportional to the reversible capacities of the positive electrode and the negative electrode, respectively, the lower the reversible capacity, the higher the utilization rate. Further, as is clear from FIG. 2, the batteries of Examples 1 to 4 had a cycle number of 2
Even after 00 times, the capacity retention rate of 96% or more was shown. Therefore, the batteries of Examples 1 to 4 were economical because they used the positive electrode active material efficiently, and had high capacity and long life.
【００３３】また、表３に示したように、実施例１と比
較例１の電池及び実施例３と比較例２の電池をそれぞれ
比較すると、同一体積の捲回群を作製することにおいて
同じ負極活物質を使用し、負極板の厚さを同じにした場
合、正極活物質に層状構造マンガン酸リチウムとスピネ
ル構造マンガン酸リチウムを重量比３０：７０〜７５：
２５の範囲で配合して用いた実施例１及び実施例３の電
池の方が高い電池容量であった。Further, as shown in Table 3, when the batteries of Example 1 and Comparative Example 1 and the batteries of Example 3 and Comparative Example 2 were compared, the same negative electrode was produced in the production of the wound group having the same volume. When the active material is used and the thickness of the negative electrode plate is the same, the weight ratio of the layered structure lithium manganate and the spinel structure lithium manganate is 30:70 to 75: as the positive electrode active material.
The batteries of Examples 1 and 3 used by blending in the range of 25 had a higher battery capacity.
【００３４】更に、実施例２と比較例１の電池及び実施
例４と比較例２の電池をそれぞれ比較すると、同一容量
の電池では、正極板の可逆容量を負極板の可逆容量以下
とし、層状構造マンガン酸リチウムとスピネル構造マン
ガン酸リチウムを配合して用いた実施例２及び実施例４
の電池の方が、負極利用率が低減され、サイクル数２０
０回後でも９８％以上の容量維持率を示した（図２参
照）。Further, when comparing the batteries of Example 2 and Comparative Example 1 and the batteries of Example 4 and Comparative Example 2, the reversible capacity of the positive electrode plate was set to be equal to or less than the reversible capacity of the negative electrode plate in the case of batteries having the same capacity. Example 2 and Example 4 in which the structured lithium manganate and the spinel structured lithium manganate were blended and used.
Battery has a lower negative electrode utilization rate and 20 cycles
Even after 0 times, the capacity retention rate was 98% or more (see FIG. 2).
【００３５】また、負極活物質に結晶性の低い非晶質炭
素を用いた実施例１及び実施例２の電池では、正極板の
不可逆容量率を２０％以上としたので、負極の負担が少
なく、容量維持率の高い電池であり、逆に、結晶性の高
い黒鉛を用いた実施例３及び実施例４の電池では、正極
板の不可逆容量率を１０％以上としたので、負極の負担
が少なく、容量維持率の高い電池であった。Further, in the batteries of Examples 1 and 2 in which amorphous carbon having low crystallinity was used as the negative electrode active material, the irreversible capacity ratio of the positive electrode plate was set to 20% or more, so that the burden on the negative electrode was small. In the batteries of Examples 3 and 4 in which graphite having high capacity retention was used and which had high crystallinity, the irreversible capacity of the positive electrode plate was set to 10% or more, so that the burden on the negative electrode was increased. The number of batteries was low and the capacity retention rate was high.
【００３６】更に、実施例１と実施例３の電池の定格容
量をそれぞれ比較例１と比較例２の電池容量にあわせた
場合、実施例１の電池では１．５Ａｈを実施例３の電池
では１．０Ａｈを蓄積でき、かつ正極利用率、負極利用
率共に低減されるため、長寿命である。Further, when the rated capacities of the batteries of Example 1 and Example 3 are matched with the battery capacities of Comparative Example 1 and Comparative Example 2, respectively, the battery of Example 1 is 1.5 Ah and the battery of Example 3 is Since 1.0 Ah can be accumulated and both the positive electrode utilization rate and the negative electrode utilization rate are reduced, the life is long.
【００３７】上述のように、本実施例では、正極板の可
逆容量を負極板の可逆容量以下としたので、充電時に正
極板から負極板に移動したリチウムイオンと同量のリチ
ウムイオンが正極に戻されるので電池容量を高めること
ができ、また、充電時の負極板の負担が少なく、負極板
の劣化を抑制して容量維持率を高くすることができた。
また、正極板の可逆容量と逆比例の関係にある正極利用
率を高くすることができた。従って、本実施例の円筒形
リチウムイオン電池１０は、正極材料を有効に活用し、
高容量かつ長寿命の電池とすることができた。また、層
状構造マンガン酸リチウムとスピネル構造マンガン酸リ
チウムとを重量比が３０：７０〜７５：２５の範囲で配
合して用いたので、層状構造マンガン酸リチウムの結晶
の層間にリチウムイオンが挿入・離脱され、より高容量
の電池とすることができた。更に、負極活物質に結晶性
炭素材の黒鉛を用いたときには、正極板の不可逆容量率
を１０％以上としたことにより、負極板の可逆容量分の
リチウムイオンを正極板から離脱させたので負極板の負
担が低減して長寿命とすることができた。更に、負極活
物質に無定型炭素材の非晶質炭素を用いたときには、正
極板の不可逆容量率を２０％以上としたことにより、充
電時に負極に移動するリチウムイオン量を減少させたの
で負極板の負担が低減して長寿命とすることができた。As described above, in this example, the reversible capacity of the positive electrode plate was set to be equal to or less than the reversible capacity of the negative electrode plate, so that the same amount of lithium ions as the lithium ions transferred from the positive electrode plate to the negative electrode plate during charging is transferred to the positive electrode. Since it was returned, the battery capacity could be increased, the burden on the negative electrode plate during charging was small, and deterioration of the negative electrode plate could be suppressed to increase the capacity retention rate.
In addition, the positive electrode utilization rate, which is inversely proportional to the reversible capacity of the positive electrode plate, could be increased. Therefore, the cylindrical lithium ion battery 10 of the present embodiment effectively utilizes the positive electrode material,
A battery with high capacity and long life could be obtained. Further, since the layered structure lithium manganate and the spinel structure lithium manganate were mixed and used in a weight ratio of 30:70 to 75:25, lithium ions were inserted between the layers of the layered structure lithium manganate crystal. It was detached and it was possible to make a battery with a higher capacity. Furthermore, when graphite of crystalline carbon material is used as the negative electrode active material, the irreversible capacity ratio of the positive electrode plate is set to 10% or more, so that lithium ions corresponding to the reversible capacity of the negative electrode plate are released from the positive electrode plate. The load on the plate was reduced and the life could be extended. Furthermore, when amorphous carbon, which is an amorphous carbon material, is used as the negative electrode active material, the amount of lithium ions transferred to the negative electrode during charging is reduced by setting the irreversible capacity ratio of the positive electrode plate to 20% or more. The load on the plate was reduced and the life could be extended.
【００３８】なお、本実施形態では、円筒形電池につい
て例示したが、本発明は電池の形状については限定され
ず、角形、その他の多角形の電池にも適用可能である。
また、本発明の適用可能な構造としては、上述した電池
容器に電池蓋がカシメによって封口されている構造の電
池以外であっても構わない。このような構造の一例とし
て正負外部端子が電池蓋を貫通し、電池容器内で軸芯を
介して正負外部端子が押し合っている状態の電池を挙げ
ることができる。更に本発明は、正極板及び負極板を捲
回式の構造とせず、積層式の構造としたリチウム二次電
池にも適用可能である。In the present embodiment, the cylindrical battery is exemplified, but the present invention is not limited to the shape of the battery and can be applied to a prismatic battery and other polygonal batteries.
Further, the applicable structure of the present invention may be other than the battery having a structure in which the battery lid is sealed by caulking in the battery container described above. An example of such a structure is a battery in which positive and negative external terminals penetrate a battery lid and positive and negative external terminals are pressed against each other via a shaft core in a battery container. Further, the present invention can be applied to a lithium secondary battery having a laminated structure instead of the positive electrode plate and the negative electrode plate having a wound structure.
【００３９】また、本実施形態では、結晶構造が異なる
層状構造とスピネル構造の２種のマンガン酸リチウムを
用いたが、本発明で用いることのできるリチウム二次電
池用正極活物質としては、リチウムイオンを挿入・離脱
可能な材料であり、予め十分な量のリチウムイオンを挿
入したリチウムマンガン複酸化物であればよく、結晶構
造の異なる３種以上を含むようにしてもよい。更に、結
晶中のリチウムやマンガンの一部をそれら以外の元素で
置換あるいはドープした材料を使用するようにしてもよ
い。In this embodiment, two kinds of lithium manganate having a layered structure and a spinel structure, which have different crystal structures, are used. As the positive electrode active material for a lithium secondary battery which can be used in the present invention, lithium is used. It is a material capable of inserting / releasing ions, and may be a lithium manganese composite oxide into which a sufficient amount of lithium ions have been inserted in advance, and may include three or more kinds having different crystal structures. Further, a material obtained by substituting or doping a part of lithium or manganese in the crystal with an element other than these may be used.
【００４０】更に、本実施形態では、負極活物質に、非
晶質炭素又は黒鉛を用いた例を示したが、天然黒鉛や、
人造の各種黒鉛材、コークスなどの炭素材料等を使用し
てもよく、用いる炭素材の結晶性により上述のように正
極板の不可逆容量率を調整すればよい。また、粒子形状
についても、鱗片状、球状、繊維状、塊状等、特に制限
されるものではない。Further, in the present embodiment, an example in which amorphous carbon or graphite is used as the negative electrode active material is shown, but natural graphite or
Various artificial graphite materials, carbon materials such as coke, and the like may be used, and the irreversible capacity ratio of the positive electrode plate may be adjusted as described above depending on the crystallinity of the carbon material used. Further, the particle shape is not particularly limited and may be scale-like, spherical, fibrous, lump-like or the like.
【００４１】また、本発明は、本実施形態で例示した導
電材、結着剤には限定されず、通常用いられているいず
れのものも使用可能である。本実施形態以外で用いるこ
とのできるリチウム二次電池用極板活物質結着剤として
は、テフロン（登録商標）、ポリエチレン、ポリスチレ
ン、ポリブタジエン、ブチルゴム、ニトリルゴム、スチ
レン／ブタジエンゴム、多硫化ゴム、ニトロセルロー
ス、シアノエチルセルロース、各種ラテックス、アクリ
ロニトリル、フッ化ビニル、フッ化ビニリデン、フッ化
プロピレン、フッ化クロロプレン等の重合体及びこれら
の混合体などがある。The present invention is not limited to the conductive material and the binder exemplified in this embodiment, and any of the commonly used materials can be used. Examples of the electrode plate active material binder for a lithium secondary battery that can be used in other embodiments include Teflon (registered trademark), polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, styrene / butadiene rubber, polysulfide rubber, There are polymers such as nitrocellulose, cyanoethyl cellulose, various latexes, acrylonitrile, vinyl fluoride, vinylidene fluoride, propylene fluoride and chloroprene fluoride, and mixtures thereof.
【００４２】また更に、本実施形態では、正極合剤中の
マンガン酸リチウム粉末と、鱗片状黒鉛と、ポリフッ化
ビニリデンとを配合する重量比を８６：９：５などと
し、負極合剤中の非晶質炭素粉末又は黒鉛粉末と、ポリ
フッ化ビニリデンとを配合する重量比を９２：８などと
したが、これらを配合する重量比については特に制限さ
れるものではなく、正極合剤、負極合剤として通常用い
られる範囲で配合して用いればよい。Furthermore, in the present embodiment, the weight ratio of the lithium manganate powder, the flake graphite and polyvinylidene fluoride mixed in the positive electrode mixture is set to 86: 9: 5 or the like, and the negative electrode mixture in the negative electrode mixture is made. The weight ratio of the amorphous carbon powder or graphite powder and polyvinylidene fluoride was set to 92: 8, but the weight ratio of these is not particularly limited, and the positive electrode mixture and the negative electrode mixture are not limited. It may be used by blending in the range usually used as an agent.
【００４３】更にまた、本実施形態では、エチレンカー
ボネートとジメチルカーボネートの混合溶媒にＬｉＰＦ
６を溶解した非水電解液を例示したが、一般的なリチウ
ム塩を電解質とし、これを有機溶媒に溶解した非水電解
液を用いてもよく、本発明は用いられるリチウム塩や有
機溶媒には特に制限されない。例えば、電解質として
は、ＬｉＣｌＯ４、ＬｉＡｓＦ６、ＬｉＢＦ４、ＬｉＢ
（Ｃ６Ｈ５）４、ＣＨ３ＳＯ３Ｌｉ、ＣＦ３ＳＯ３Ｌｉ
等やこれらの混合物を用いることができる。また、有機
溶媒としては、プロピレンカーボネート、１，２−ジメ
トキシエタン、１，２−ジエトキシエタン、γ−ブチロ
ラクトン、テトラヒドロフラン、１，３−ジオキソラ
ン、４−メチル−１，３−ジオキソラン、ジエチルエー
テル、スルホラン、メチルスルホラン、アセトニトリ
ル、プロピオニトリル等、又はこれらの２種類以上を混
合した混合溶媒を用いることができ、更に、混合配合比
についても限定されるものではない。Furthermore, in the present embodiment, the mixed solvent of ethylene carbonate and dimethyl carbonate is mixed with LiPF.
Although the non-aqueous electrolytic solution in which 6 is dissolved is exemplified, a non-aqueous electrolytic solution in which a general lithium salt is used as an electrolyte and this is dissolved in an organic solvent may be used, and the present invention is applicable to the lithium salt and the organic solvent used. Is not particularly limited. For example, as the electrolyte, LiClO 4, LiAsF 6, LiBF 4, LiB
(C 6 H 5) 4, CH 3 SO 3 Li, CF 3 SO 3 Li
Etc. and mixtures thereof can be used. Further, as the organic solvent, propylene carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, Sulfolane, methylsulfolane, acetonitrile, propionitrile, etc., or a mixed solvent prepared by mixing two or more of these can be used, and the mixing ratio is not limited.
【００４４】[0044]
【発明の効果】以上説明したように、本発明によれば、
正極活物質に結晶構造の異なる２種以上のリチウムマン
ガン複酸化物を配合したものを用い、正極の可逆容量を
負極の可逆容量以下とすることにより、充電時に正極か
ら離脱して負極に移動するリチウムイオンの量が負極の
可逆容量以下となり、負極の負担を低減することができ
るので、負極の劣化を抑制することができると共に、充
電時に正極から負極に移動したリチウムイオンと同量の
リチウムイオンが放電時には正極に挿入され、正極を有
効に活用することができるので、電池容量を高めること
ができる、という効果を得ることができる。As described above, according to the present invention,
By using a positive electrode active material in which two or more kinds of lithium manganese composite oxides having different crystal structures are blended, and the reversible capacity of the positive electrode is set to be equal to or less than the reversible capacity of the negative electrode, the positive electrode active material is separated from the positive electrode during charging and moves to the negative electrode. Since the amount of lithium ions is less than or equal to the reversible capacity of the negative electrode and the burden on the negative electrode can be reduced, deterioration of the negative electrode can be suppressed, and the same amount of lithium ions as the lithium ions transferred from the positive electrode to the negative electrode during charging. Is inserted into the positive electrode at the time of discharging and the positive electrode can be effectively used, so that the battery capacity can be increased.
【図１】 本発明が適用可能な実施形態の円筒形リチウ
ムイオン電池の断面図である。FIG. 1 is a cross-sectional view of a cylindrical lithium ion battery of an embodiment to which the present invention can be applied.
【図２】 本発明が適用可能な実施形態の円筒形リチウ
ムイオン電池の充放電サイクル数に対する容量維持率の
変化を示したグラフである。FIG. 2 is a graph showing changes in the capacity retention rate with respect to the number of charge / discharge cycles of the cylindrical lithium ion battery of the embodiment to which the present invention is applicable.
１ 捲回群 ２ 電池容器 ３ 電池蓋 ４ 正極集電リング ５ 負極集電リング １０ 円筒形リチウムイオン電池（リチウム二次電池） 1 winding group 2 Battery container 3 Battery lid 4 Positive electrode collector ring 5 Negative electrode collector ring 10 Cylindrical lithium-ion battery (lithium secondary battery)
───────────────────────────────────────────────────── フロントページの続き Ｆターム(参考） 5H029 AJ03 AJ05 AK03 AK19 AL06 AL07 AM03 AM05 AM07 BJ02 BJ14 CJ08 DJ16 DJ17 HJ01 HJ02 HJ19 5H050 AA07 AA08 BA17 CA09 CB07 CB08 GA10 HA01 HA02 HA19 ─────────────────────────────────────────────────── ─── Continued front page F-term (reference) 5H029 AJ03 AJ05 AK03 AK19 AL06 AL07 AM03 AM05 AM07 BJ02 BJ14 CJ08 DJ16 DJ17 HJ01 HJ02 HJ19 5H050 AA07 AA08 BA17 CA09 CB07 CB08 GA10 HA01 HA02 HA19
Claims (5)
の主体とするリチウム二次電池において、前記リチウム
マンガン複酸化物は結晶構造が異なる２種以上のリチウ
ムマンガン複酸化物を含み、かつ、前記正極の可逆容量
が負極の可逆容量以下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 lithium manganese composite oxide as a main component of a positive electrode active material, wherein the lithium manganese composite oxide includes two or more kinds of lithium manganese composite oxides having different crystal structures, and A rechargeable lithium battery, wherein the reversible capacity of the positive electrode is less than or equal to the reversible capacity of the negative electrode.
構造リチウムマンガン複酸化物とスピネル構造リチウム
マンガン複酸化物とを含むもの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 lithium secondary battery according to claim 1, wherein the lithium manganese composite oxide includes a layered structure lithium manganese composite oxide and a spinel structure lithium manganese composite oxide.
と前記スピネル構造リチウムマンガン複酸化物との配合
重量比が、３０：７０〜７５：２５であることを特徴と
する請求項２に記載のリチウム二次電池。3. The lithium according to claim 2, wherein the compounding weight ratio of the layered structure lithium manganese composite oxide and the spinel structure lithium manganese composite oxide is 30:70 to 75:25. Secondary battery.
り、前記正極の不可逆容量率が１０％以上であることを
特徴とする請求項１乃至請求項３のいずれか１項に記載
のリチウム二次電池。4. The active material of the negative electrode is a crystalline carbon material, and the irreversible capacity ratio of the positive electrode is 10% or more, according to any one of claims 1 to 3. Lithium secondary battery.
り、前記正極の不可逆容量率が２０％以上であることを
特徴とする請求項１乃至請求項３のいずれか１項に記載
のリチウム二次電池。5. The active material of the negative electrode is an amorphous carbon material, and the irreversible capacity ratio of the positive electrode is 20% or more, according to any one of claims 1 to 3. Lithium secondary battery.
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|---|---|---|---|
| JP2001222415A JP3979044B2 (en) | 2001-07-24 | 2001-07-24 | Lithium secondary battery |
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