JP4007162B2

JP4007162B2 - Non-aqueous electrolyte secondary battery

Info

Publication number: JP4007162B2
Application number: JP2002321703A
Authority: JP
Inventors: 正幸遠藤
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 2002-11-05
Filing date: 2002-11-05
Publication date: 2007-11-14
Anticipated expiration: 2022-11-14
Also published as: JP2003178805A

Description

【０００１】
【発明の属する技術分野】
本発明は、非水電解液二次電池に関し、特に負極集電に用いる負極リードの改良に関するものである。
【０００２】
【従来の技術】
近年、電子技術の進歩により、電子機器の高性能化、小型化、ポータブル化が進み、これらの電子機器に使用される高エネルギー密度の二次電池の要求が強まっている。
【０００３】
これらの電子機器に使用される二次電池としては、ニッケル・カドミウム電池や鉛電池などが挙げられるが、これらの電池では、放電電位が低く、エネルギー密度の高い電池を得るという点ではまだ不十分である。
【０００４】
そこで最近は、リチウムやリチウム合金もしくは炭素材料のようなリチウムイオンをドープ及び脱ドープすることが可能な物質を負極として用い、また正極にリチウムコバルト複合酸化物などのリチウム複合酸化物を使用する非水電解液二次電池の研究・開発が行われている。この電池は、電池電圧が高く、高エネルギー密度を有し、自己放電も少なく、かつサイクル特性に優れている。
【０００５】
上記非水電解液二次電池としては、例えば、帯状のアルミニウムの正極集電体の両面に正極活物質を塗布して形成された正極と、帯状の銅の負極集電体の両面に負極活物質を塗布して形成された負極とを、絶縁体を介して巻回して巻回電極体とし、この巻回電極体を上下に絶縁板を設置した状態で電池缶に収納した後、電池蓋にて電池缶を密閉してなる円筒型非水電解液二次電池が知られている。
【０００６】
この円筒型非水電解液二次電池では、負極の集電を行うために、負極集電体に溶接されたニッケル製負極リードにて、負極と電池缶とが電気的に導通するようになっている。また、正極の集電を行うために、正極集電体に溶接されたアルミニウム製正極リードにて、正極と電池蓋とが電気的に導通するようになっている。なお、負極リードに、負極集電体と同じである銅を用いずに、ニッケルを用いるのは、負極集電体への溶接が容易である、取扱いが容易である等の理由による。
【０００７】
【発明が解決しようとする課題】
上記非水電解液二次電池では、外部ショート等により大電流が流れると集電部が発熱し、電池温度が上昇するという問題がある。前記温度上昇は、特に負極リードからの発熱の影響が大きい。なぜなら、負極リードは、他の集電部、例えば、負極集電体に用いられる銅や、正極集電体及び正極リードに用いられるアルミニウム等よりも、電気抵抗が大きく、発熱しやすいからである。
【０００８】
この負極リードの発熱量は、負極リードの断面積に反比例するので、負極リードの幅が広ければ広いほど、又は負極リードの厚みが厚ければ厚いほど、負極リードの発熱量は小さくなる。そのため、外部ショート等により大電流が流れたときの電池温度の上昇を抑えるためには、負極リードの断面積を大きくすればよい。しかし、負極リードの断面積が大きすぎると、すなわち、負極リードの幅が広すぎたり、負極リードの厚みが厚すぎたりすると、電池の製造工程において、巻回電極体を電池缶に挿入する際に、負極リードが電池缶に引っかかり、巻回電極体の挿入不良が発生しやすいという問題がある。
【０００９】
本発明は、このような課題に鑑みてなされたものであり、外部ショート等が生じて大電流が流れても電池の温度上昇が少なく、その上、製造工程において巻回電極体の挿入不良が発生しにくく生産性が高い非水電解液二次電池を提供することを目的とする。
【００１０】
【課題を解決するための手段】
上述の目的を達成するために、本発明者は、非水電解液二次電池について、電池容量、負極リードの断面積、外部ショート発生時の電池の温度上昇、及び巻回電極体の挿入不良等の関係について実験を重ねて検討した結果、本発明を成すに至った。
【００１１】
すなわち、本発明の非水電解液二次電池は、帯状のアルミニウム箔の両面に正極合剤を塗布し圧縮成型した帯状の正極と、帯状の銅箔の両面に負極合剤を塗布し圧縮成型した帯状の負極とをセパレーターを介して積層し、多数回巻回してなる電極体と、前記電極体を収納させた電池容器と非水電解液とを備え、前記帯状の負極の端部にニッケル製の負極リードが溶接され、かつ、前記ニッケル製の負極リードが電池容器に溶接されてなる非水電解液二次電池において、電池容量と前記負極リードの断面積の比が３．０Ａｈ／ｍｍ^２〜６．３Ａｈ／ｍｍ^２であることを特徴とする。
【００１２】
なお、電池容量の測定は、例えば、終止電圧２．７５Ｖ、２．５時間率として測定する。
【００１３】
本発明の非水電解液二次電池は、外部ショート等が生じて大電流が流れても、あまり電池の温度が上昇することがない。その上、製造工程において、巻回電極体の挿入不良が発生しにくい。
【００１４】
【発明の実施の形態】
以下に、本発明を適用した具体的な実施例について、図面を参照しながら説明する。
【００１５】
実施例１
図１に示すような非水電解液二次電池を次のように作製した。まず、正極２を次のように作製した。まず、炭酸リチウムと炭酸コバルトをＬｉ／Ｃｏ（モル比）＝１になるように混合し、空気中で９００℃、５時間焼成した。この材料についてＸ線回折測定を行った結果、ＪＣＰＤＳカードのＬｉＣｏＯ_２と良く一致していた。そして、このＬｉＣｏＯ_２９５重量部と炭酸リチウム５重量部とを混合して正極活物質とした。そして、この正極活物質を９１重量部、電導材としてグラファイトＫＳ−１５を６重量部、及び結着剤としてポリフッ化ビニリデン（ＰＶＤＦ）を３重量部を混合し正極合剤を作製して、これをＮ−メチル２ピロリドンに分散させてスラリー状にした。そして、正極集電体として帯状アルミニウム箔を用い、この正極集電体１１の両面に、正極合剤（スラリー）を均一に塗布し、乾燥させた後、ロールプレス機で圧縮成型し、帯状の正極２を作製した。
【００１６】
次に、負極１を次のように作製した。負極活物質には、出発材料に石油ピッチを用い、これに酸素を含む官能基を１０％〜２０％導入（いわゆる酸素架橋）した後、不活性ガス気流中１０００℃で焼成して得られたガラス状炭素に近い性質を持つ難黒鉛炭素材料粉末を用いた。この材料について、Ｘ線回折測定を行った結果、（００２）面の面間隔は０．３７６ｎｍで、また、真比重は１．５８であった。このようにして得られた炭素材料９０重量部と、結着剤としてポリフッ化ビニリデン（ＰＶＤＦ）１０重量部とを混合して負極合剤を作製し、この負極合剤をＮ−メチル２ピロリドンに分散させてスラリー状にした。負極集電体として帯状銅箔を用い、この負極集電体１０の両面に、負極合剤（スラリー）を均一に塗布し、乾燥させた後、ローラープレス機で圧縮成型し、帯状の負極１を作製した。そして、この負極１の端部に、集電をとるための厚さ０．１ｍｍ、幅４ｍｍのニッケル製の負極リード１２を溶接した。
【００１７】
以上のように作製した負極１と正極２とを、厚さ２５μｍの微多孔性ポリプロピレンフィルムよりなるセパレーター３を介して積層し、多数回巻回することにより巻回電極体を作製した。なお、巻回は、セパレーターの端部をまずセンターピン１４に巻き取り、これを中心に多数回巻回した。
【００１８】
次に、ニッケルメッキを施した鉄製の電池缶５に、電池缶５の底部に絶縁板４を挿入した上で、前記巻回電極体を収納した。このとき、負極１の集電をとるために、負極１の端部に取り付けられたニッケル製の負極リード１２を電池缶５に溶接した。また、正極２の集電をとるために、正極２の端部にアルミニウム製の正極リード１３の一端を取り付け、前記正極リード１３の他の一端を、巻回電極体と電池蓋７との間に配設される安全弁装置８に溶接した。
【００１９】
なお、安全弁装置８は、アルミニウムに切り込みを入れたもので、電池内圧が一定以上になると、切り込み部が開裂し、内圧を開放するとともに、正極リード１３と電池蓋７との間の接続が切れ、電流を遮断するものである。
【００２０】
そして、電池缶５の中にプロピレンカーボネートとジエチルカーボネートとの等容量混合溶媒中にＬｉＰＦ_６を１モル／ｌの割合で溶解した非水電解液を注入して、巻回電極体に含浸させた。
【００２１】
そして、安全弁装置８上に、感熱電池遮断素子９（ＰＴＣ素子）と電池蓋７とを、電池缶５に蓋をするように、この順に重ねた後、アフファルトを塗布した絶縁封口ガスケット６を介して電池缶５をかしめて、これらを固定して、直径１８ｍｍ、高さ６５ｍｍの円筒型非水電解液二次電池を作製した。
【００２２】
なお、感熱電池遮断素子９は、電池温度が上昇したときに電流が流れるのを抑制するための素子である。すなわち、周囲温度の上昇により熱せられて、ある臨界温度（例えば、１２０℃前後）に達すると、急激に電気抵抗が増大（例えば、１０万倍以上）して、電流値を抑制するものである。
【００２３】
実施例２
負極リードに、厚さ０．１ｍｍ、幅４ｍｍのニッケル製の負極リードを用いて、直径２６ｍｍ、高さ６５ｍｍの円筒型非水電解液二次電池を、実施例１と同様に作製した。
【００２４】
実施例３
負極リードに、厚さ０．１ｍｍ、幅６ｍｍのニッケル製の負極リードを用いて、直径２６ｍｍ、高さ６５ｍｍの円筒型非水電解液二次電池を、実施例１と同様に作製した。
【００２５】
比較例１
負極リードに、厚さ０．１ｍｍ、幅１．５ｍｍのニッケル製の負極リードを用いて、直径１８ｍｍ、高さ６５ｍｍの円筒型非水電解液二次電池を、実施例１と同様に作製した。
【００２６】
比較例２
負極リードに、厚さ０．１ｍｍ、幅３ｍｍのニッケル製の負極リードを用いて、直径２６ｍｍ、高さ６５ｍｍの円筒型非水電解液二次電池を、実施例１と同様に作製した。
【００２７】
比較例３
負極リードに、厚さ０．２ｍｍ、幅４ｍｍのニッケル製の負極リードを用いて、直径１８ｍｍ、高さ６５ｍｍの円筒型非水電解液二次電池を、実施例１と同様に作製した。
【００２８】
比較例４
負極リードに、厚さ０．３ｍｍ、幅６ｍｍのニッケル製の負極リードを用いて、直径２６ｍｍ、高さ６５ｍｍの円筒型非水電解液二次電池を、実施例１と同様に作製した。
【００２９】
このようにして各実施例及び各比較例の非水電解液二次電池を１００本ずつ作製して、製造工程において巻回電極体の挿入不良が生じた電池の数を調べた。
【００３０】
そして、正常に巻回電極体の挿入がされて完成した電池の中から、各実施例及び各比較例について、それぞれ１０本ずつ抽出して、電池容量を測定した。なお、電池容量の測定は、直径１８ｍｍ，高さ６５ｍｍの電池である実施例１，比較例１，比較例３の電池については、充電電圧４．２０Ｖ，充電電流１０００ｍＡ，充電時間２．５ｈで充電し、放電電流５００ｍＡ，終止電圧２．７５Ｖで放電して測定した。また、直径２６ｍｍ，高さ６５ｍｍの電池である実施例２，実施例３，比較例２，比較例４の電池については、充電電圧４．２０Ｖ，充電電流２０００ｍＡ，充電時間２．５ｈで充電し、放電電流１０００ｍＡ，終止電圧２．７５Ｖで放電して測定した。
【００３１】
その後、再び充電を行った上で、外部ショート試験を行い、外部ショート時の電池の最高温度を調べた。
【００３２】
以上の測定の結果を表１に示す。
【００３３】
【表１】

【００３４】
この結果から、明らかなように、本実施例の非水電解液二次電池は、巻回電極体の挿入不良が生じることがない。そして、外部ショートが生じても電池の温度上昇が少なく、最も温度が上昇した実施例２の非水電解液二次電池であっても８５℃までしか上昇していない。
【００３５】
【発明の効果】
以上の説明から明らかなように、本発明のように電池容量と負極リードの断面積の比を規定することにより、外部ショート等が生じて大電流が流れても、あまり電池の温度が上昇することがない非水電解液二次電池であって、その上、製造工程において巻回電極体の挿入不良が発生しにくく生産性が高い非水電解液二次電池を提供することができる。
【図面の簡単な説明】
【図１】本発明を適用した非水電解液二次電池の一構成例を示す概略断面図である。
【符号の説明】
１負極、２正極、３セパレータ、４絶縁板、５電池缶、６絶縁封口ガスケット、７電池蓋、８安全弁装置、９感熱電池遮断素子、１０負極集電体、１１正極集電体、１２負極リード、１３正極リード[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-aqueous electrolyte secondary battery, and more particularly to improvement of a negative electrode lead used for negative electrode current collection.
[0002]
[Prior art]
In recent years, due to advances in electronic technology, electronic devices have become higher performance, smaller, and more portable, and the demand for high energy density secondary batteries used in these electronic devices has increased.
[0003]
Secondary batteries used in these electronic devices include nickel cadmium batteries and lead batteries, but these batteries are still insufficient in terms of obtaining batteries with low discharge potential and high energy density. It is.
[0004]
Therefore, recently, a substance capable of doping and dedoping lithium ions such as lithium, lithium alloy, or carbon material is used as the negative electrode, and a lithium composite oxide such as lithium cobalt composite oxide is used for the positive electrode. Research and development of water electrolyte secondary batteries are underway. This battery has a high battery voltage, a high energy density, little self-discharge, and excellent cycle characteristics.
[0005]
Examples of the non-aqueous electrolyte secondary battery include a positive electrode formed by applying a positive electrode active material on both surfaces of a strip-shaped aluminum positive electrode current collector, and a negative electrode active material on both surfaces of a strip-shaped copper negative electrode current collector. A negative electrode formed by applying a substance is wound through an insulator to form a wound electrode body, and the wound electrode body is stored in a battery can with an insulating plate installed on the upper and lower sides, and then a battery lid A cylindrical non-aqueous electrolyte secondary battery is known in which a battery can is sealed.
[0006]
In this cylindrical non-aqueous electrolyte secondary battery, in order to collect the negative electrode, the negative electrode and the battery can are electrically connected by the nickel negative electrode lead welded to the negative electrode current collector. ing. Further, in order to collect the positive electrode, the positive electrode and the battery lid are electrically connected to each other by an aluminum positive electrode lead welded to the positive electrode current collector. The reason why nickel is used for the negative electrode lead without using the same copper as the negative electrode current collector is that welding to the negative electrode current collector is easy and handling is easy.
[0007]
[Problems to be solved by the invention]
The non-aqueous electrolyte secondary battery has a problem that when a large current flows due to an external short circuit or the like, the current collector generates heat and the battery temperature rises. The increase in temperature is particularly affected by heat generated from the negative electrode lead. This is because the negative electrode lead has a higher electrical resistance and is more likely to generate heat than other current collectors such as copper used for the negative electrode current collector, aluminum used for the positive electrode current collector and the positive electrode lead, and the like. .
[0008]
Since the heat generation amount of the negative electrode lead is inversely proportional to the cross-sectional area of the negative electrode lead, the heat generation amount of the negative electrode lead decreases as the width of the negative electrode lead increases or the thickness of the negative electrode lead increases. Therefore, in order to suppress an increase in battery temperature when a large current flows due to an external short circuit or the like, the cross-sectional area of the negative electrode lead may be increased. However, if the cross-sectional area of the negative electrode lead is too large, that is, if the width of the negative electrode lead is too wide or the thickness of the negative electrode lead is too thick, the winding electrode body is inserted into the battery can in the battery manufacturing process. In addition, there is a problem that the negative electrode lead is caught in the battery can, and poor insertion of the wound electrode body is likely to occur.
[0009]
The present invention has been made in view of such problems, and even when an external short circuit occurs and a large current flows, the temperature of the battery is small. In addition, there is no insertion failure of the wound electrode body in the manufacturing process. An object of the present invention is to provide a non-aqueous electrolyte secondary battery that does not easily generate and has high productivity.
[0010]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present inventor, regarding the non-aqueous electrolyte secondary battery, the battery capacity, the cross-sectional area of the negative electrode lead, the temperature rise of the battery when an external short occurs, and the insertion failure of the winding electrode body As a result of repeated experiments on the relationship, etc., the present invention has been achieved.
[0011]
That is, the non-aqueous electrolyte secondary battery of the present invention, strip-shaped and strip-shaped cathode coated was compression molded positive electrode mixture on both sides of an aluminum foil, coated compression molding the negative electrode mixture on both sides of a strip-shaped copper foil A strip-shaped negative electrode is laminated via a separator, and is wound many times , a battery container containing the electrode body and a non-aqueous electrolyte, and nickel at the end of the strip-shaped negative electrode In a non-aqueous electrolyte secondary battery in which a negative electrode lead made of nickel is welded and the negative electrode lead made of nickel is welded to a battery container, the ratio of the cross-sectional area of the battery capacity to the negative electrode lead is 3.0 Ah / characterized in that it is a ^{^{mm 2 ~ 6.3 Ah / mm 2}} .
[0012]
The battery capacity is measured, for example, as a final voltage of 2.75 V and a 2.5 hour rate.
[0013]
In the non-aqueous electrolyte secondary battery of the present invention, even when an external short circuit occurs and a large current flows, the temperature of the battery does not increase so much. In addition, poor insertion of the wound electrode body hardly occurs in the manufacturing process.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific examples to which the present invention is applied will be described with reference to the drawings.
[0015]
Example 1
A non-aqueous electrolyte secondary battery as shown in FIG. 1 was produced as follows. First, the positive electrode 2 was produced as follows. First, lithium carbonate and cobalt carbonate were mixed so that Li / Co (molar ratio) = 1, and fired in air at 900 ° C. for 5 hours. As a result of X-ray diffraction measurement of this material, it was in good agreement with LiCoO _{2 of} JCPDS card. Then, 95 parts by weight of LiCoO ₂ and 5 parts by weight of lithium carbonate were mixed to obtain a positive electrode active material. Then, 91 parts by weight of this positive electrode active material, 6 parts by weight of graphite KS-15 as a conductive material, and 3 parts by weight of polyvinylidene fluoride (PVDF) as a binder were mixed to prepare a positive electrode mixture. Was dispersed in N-methyl-2-pyrrolidone to form a slurry. Then, a strip-shaped aluminum foil is used as the positive electrode current collector, and the positive electrode mixture (slurry) is uniformly applied to both surfaces of the positive electrode current collector 11 and dried, followed by compression molding with a roll press machine. A positive electrode 2 was produced.
[0016]
Next, the negative electrode 1 was produced as follows. The negative electrode active material was obtained by using petroleum pitch as a starting material, introducing 10% to 20% of a functional group containing oxygen (so-called oxygen crosslinking), and then firing at 1000 ° C. in an inert gas stream. A non-graphite carbon material powder having properties close to glassy carbon was used. As a result of X-ray diffraction measurement of this material, the (002) plane spacing was 0.376 nm and the true specific gravity was 1.58. A negative electrode mixture was prepared by mixing 90 parts by weight of the carbon material thus obtained and 10 parts by weight of polyvinylidene fluoride (PVDF) as a binder, and this negative electrode mixture was changed to N-methyl-2-pyrrolidone. Dispersed into a slurry. Using a strip-shaped copper foil as a negative electrode current collector, a negative electrode mixture (slurry) was uniformly applied to both surfaces of the negative electrode current collector 10 and dried, followed by compression molding with a roller press machine. Was made. A nickel negative electrode lead 12 having a thickness of 0.1 mm and a width of 4 mm for collecting current was welded to the end of the negative electrode 1.
[0017]
The negative electrode 1 and the positive electrode 2 produced as described above were laminated via a separator 3 made of a microporous polypropylene film having a thickness of 25 μm and wound many times to produce a wound electrode body. In the winding, the end of the separator was first wound around the center pin 14 and wound many times around this.
[0018]
Next, after the insulating plate 4 was inserted into the bottom of the battery can 5 in an iron battery can 5 plated with nickel, the wound electrode body was accommodated. At this time, a nickel negative electrode lead 12 attached to the end of the negative electrode 1 was welded to the battery can 5 in order to collect the negative electrode 1. Further, in order to collect the current of the positive electrode 2, one end of an aluminum positive electrode lead 13 is attached to the end of the positive electrode 2, and the other end of the positive electrode lead 13 is connected between the wound electrode body and the battery lid 7. It welded to the safety valve apparatus 8 arrange | positioned by this.
[0019]
In addition, the safety valve device 8 is made by cutting aluminum, and when the internal pressure of the battery exceeds a certain level, the cut portion is cleaved to release the internal pressure, and the connection between the positive electrode lead 13 and the battery lid 7 is disconnected. The current is cut off.
[0020]
Then, a non-aqueous electrolyte solution in which LiPF ₆ was dissolved at a ratio of 1 mol / l in an equal volume mixed solvent of propylene carbonate and diethyl carbonate was injected into the battery can 5 and impregnated into the wound electrode body. .
[0021]
Then, a thermal battery interrupting element 9 (PTC element) and a battery lid 7 are stacked on the safety valve device 8 in this order so as to cover the battery can 5, and then the insulating seal gasket 6 coated with afphalt is used. The battery can 5 was caulked and fixed to produce a cylindrical nonaqueous electrolyte secondary battery having a diameter of 18 mm and a height of 65 mm.
[0022]
The thermal battery interrupting element 9 is an element for suppressing current from flowing when the battery temperature rises. That is, when heated to an ambient temperature and reaches a certain critical temperature (for example, around 120 ° C.), the electrical resistance suddenly increases (for example, 100,000 times or more) to suppress the current value. .
[0023]
Example 2
A negative electrode lead made of nickel having a thickness of 0.1 mm and a width of 4 mm was used as the negative electrode lead, and a cylindrical nonaqueous electrolyte secondary battery having a diameter of 26 mm and a height of 65 mm was produced in the same manner as in Example 1.
[0024]
Example 3
Using a nickel negative electrode lead having a thickness of 0.1 mm and a width of 6 mm as the negative electrode lead, a cylindrical nonaqueous electrolyte secondary battery having a diameter of 26 mm and a height of 65 mm was produced in the same manner as in Example 1.
[0025]
Comparative Example 1
A cylindrical non-aqueous electrolyte secondary battery having a diameter of 18 mm and a height of 65 mm was prepared in the same manner as in Example 1 by using a nickel negative electrode lead having a thickness of 0.1 mm and a width of 1.5 mm as the negative electrode lead. .
[0026]
Comparative Example 2
Using a nickel negative electrode lead having a thickness of 0.1 mm and a width of 3 mm as the negative electrode lead, a cylindrical nonaqueous electrolyte secondary battery having a diameter of 26 mm and a height of 65 mm was produced in the same manner as in Example 1.
[0027]
Comparative Example 3
Using a nickel negative electrode lead having a thickness of 0.2 mm and a width of 4 mm as the negative electrode lead, a cylindrical nonaqueous electrolyte secondary battery having a diameter of 18 mm and a height of 65 mm was produced in the same manner as in Example 1.
[0028]
Comparative Example 4
A negative electrode lead made of nickel having a thickness of 0.3 mm and a width of 6 mm was used as the negative electrode lead, and a cylindrical nonaqueous electrolyte secondary battery having a diameter of 26 mm and a height of 65 mm was produced in the same manner as in Example 1.
[0029]
In this way, 100 non-aqueous electrolyte secondary batteries of each Example and each Comparative Example were produced, and the number of batteries in which the defective insertion of the wound electrode body occurred in the manufacturing process was examined.
[0030]
And 10 pieces were extracted about each Example and each comparative example from the battery which was inserted normally by the winding electrode body, and the battery capacity was measured. The battery capacity was measured for the batteries of Example 1, Comparative Example 1 and Comparative Example 3, which are batteries having a diameter of 18 mm and a height of 65 mm, at a charging voltage of 4.20 V, a charging current of 1000 mA, and a charging time of 2.5 h. The measurement was performed by charging and discharging at a discharge current of 500 mA and a final voltage of 2.75 V. The batteries of Example 2, Example 3, Comparative Example 2, and Comparative Example 4, which are batteries having a diameter of 26 mm and a height of 65 mm, were charged at a charging voltage of 4.20 V, a charging current of 2000 mA, and a charging time of 2.5 h. The discharge current was measured at 1000 mA and the final voltage was 2.75 V.
[0031]
Then, after charging again, an external short test was conducted to check the maximum battery temperature when the external short circuit occurred.
[0032]
The results of the above measurement are shown in Table 1.
[0033]
[Table 1]

[0034]
As is clear from this result, in the nonaqueous electrolyte secondary battery of this example, the insertion failure of the wound electrode body does not occur. And even if an external short circuit occurs, the battery temperature rises little, and even the non-aqueous electrolyte secondary battery of Example 2 where the temperature rises most only rises to 85 ° C.
[0035]
【The invention's effect】
As is clear from the above description, by defining the ratio of the battery capacity and the cross-sectional area of the negative electrode lead as in the present invention, even if an external short circuit occurs and a large current flows, the battery temperature rises too much. In addition, it is possible to provide a non-aqueous electrolyte secondary battery that has high productivity and is less likely to cause poor insertion of the wound electrode body in the manufacturing process.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a configuration example of a nonaqueous electrolyte secondary battery to which the present invention is applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Negative electrode, 2 Positive electrode, 3 Separator, 4 Insulation board, 5 Battery can, 6 Insulation sealing gasket, 7 Battery cover, 8 Safety valve apparatus, 9 Thermal battery interruption | blocking element, 10 Negative electrode collector, 11 Positive electrode collector, 12 Negative electrode Lead, 13 Positive lead

Claims

A belt-like positive electrode formed by compressing and molding a positive electrode mixture on both sides of a belt-like aluminum foil;
An electrode body formed by laminating a negative electrode mixture on both sides of a belt-shaped copper foil and compressing and molding the strip-shaped negative electrode through a separator and winding it many times , a battery container containing the electrode body, and non-water With electrolyte,
In a non-aqueous electrolyte secondary battery in which a nickel negative electrode lead is welded to an end of the strip-shaped negative electrode , and the nickel negative electrode lead is welded to a battery container,
The non-aqueous electrolyte secondary battery, wherein the ratio of the battery capacity and the cross-sectional area of the negative electrode lead is 3.0 Ah / mm ² to 6.3 Ah / mm ² .

The positive electrode material mixture including a positive electrode active material, a composite oxide containing lithium as the positive electrode active material,
The negative electrode material mixture contains a negative electrode active material, after introduction of functional groups containing oxygen to petroleum pitch was used non-graphitizable carbon material obtained by firing in an inert gas stream as the negative electrode active material The non-aqueous electrolyte secondary battery according to claim 1.

The positive electrode has one end of an aluminum positive electrode lead attached to the end of the positive electrode , a safety valve device is welded to the other end of the positive electrode lead, and a battery lid is attached to the safety valve device via a thermal battery blocking element. non-aqueous electrolyte secondary battery according to claim 1, wherein the are.