CN100495804C - lithium secondary battery - Google Patents

lithium secondary battery Download PDF

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CN100495804C
CN100495804C CNB2006800011743A CN200680001174A CN100495804C CN 100495804 C CN100495804 C CN 100495804C CN B2006800011743 A CNB2006800011743 A CN B2006800011743A CN 200680001174 A CN200680001174 A CN 200680001174A CN 100495804 C CN100495804 C CN 100495804C
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battery
negative electrode
resistant layer
porous heat
lithium secondary
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CN101061601A (en
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藤川万乡
铃木刚平
井上薰
岛田干也
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Panasonic Holdings Corp
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Matsushita Electric Industrial Co Ltd
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    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
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    • Y02P70/00Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50Manufacturing or production processes characterised by the final manufactured product

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Abstract

A lithium secondary battery that is excellent in resistance to short-circuits and heat, is unlikely to suffer a capacity loss due to impact such as dropping, and has a high capacity. The lithium secondary battery includes: an electrode assembly including a strip-like positive electrode and a strip-like negative electrode that are wound together with a porous heat-resistant layer interposed therebetween; a non-aqueous electrolyte; and a battery can. The battery has a restricting part for restricting vertical movement of the electrode assembly. The distance A from the restricting part to the inner bottom face of the battery can and the width B of the negative electrode satisfy the relation: 0.965<=B/A<=0.995.

Description

锂二次电池 lithium secondary battery

技术领域 technical field

本发明涉及一种具有出色的抗短路性和耐热性的安全性较高的锂二次电池。本发明特别涉及一种用于防止电池因冲击如下落而产生容量损失的技术。The present invention relates to a relatively safe lithium secondary battery having excellent short-circuit resistance and heat resistance. In particular, the present invention relates to a technique for preventing capacity loss of a battery due to impact such as dropping.

背景技术 Background technique

锂二次电池作为便携式装置及其他装置的高容量电源已受到关注。此外,锂二次电池作为电动车辆等的高输出电源近来也日益受到关注。化学电池如锂二次电池通常具有能使正极与负极电绝缘并保持电解液的隔膜。在锂二次电池中,主要用聚烯烃(如聚乙烯、聚丙烯等)制成的微孔膜作隔膜。通过将正极和负极与插入两电极之间的隔膜缠绕在一起,锂二次电池的电极组件可制造成圆柱形的或基本椭圆的圆柱形。Lithium secondary batteries have attracted attention as high-capacity power sources for portable devices and others. In addition, lithium secondary batteries have recently attracted increasing attention as high-output power sources for electric vehicles and the like. Chemical batteries such as lithium secondary batteries generally have a separator that electrically insulates the positive electrode from the negative electrode and holds the electrolyte. In lithium secondary batteries, microporous membranes made of polyolefins (such as polyethylene, polypropylene, etc.) are mainly used as separators. An electrode assembly of a lithium secondary battery may be manufactured in a cylindrical or substantially elliptical cylindrical shape by winding a positive electrode and a negative electrode together with a separator interposed between the two electrodes.

圆柱形的锂二次电池可用作,例如,动力工具和笔记本电脑的电源。圆柱形的锂二次电池可通过将其电池壳的开口边卷曲在密封板上进行密封。为使密封板固定在电池壳顶部开口的外围,电池壳在其侧壁的上半部有一内径减小的槽部(狭窄部分)。专利文献1提出了一种高容量设计,该设计中负极的宽度B(38mm)与从狭窄部分到电池壳外底面的距离A(39.7mm)之间满足关系式:B/A=0.957。Cylindrical lithium secondary batteries are used, for example, as power sources for power tools and notebook computers. A cylindrical lithium secondary battery can be sealed by crimping the open side of its battery case on a sealing plate. In order to fix the sealing plate on the periphery of the top opening of the battery case, the battery case has a groove portion (narrow portion) with a reduced inner diameter in the upper half of its side wall. Patent Document 1 proposes a high-capacity design, in which the width B (38mm) of the negative electrode and the distance A (39.7mm) from the narrow portion to the outer bottom surface of the battery case satisfy the relationship: B/A=0.957.

棱柱形的锂二次电池可用作,例如,便携式电话和数字式静物摄影机的电源。由于棱柱形的锂二次电池比圆柱形的更容易安入装置中,因此它们正变得日益普及。在棱柱形的锂二次电池中,连接电极与终端的引线容易与电池壳接触,这不同于圆柱形的锂二次电池。当极性与电池壳相反的引线接触到电池壳时会发生短路。因此通常在电极组件的上半部和电池壳的盖(绝缘板)之间设置绝缘体(以下称上部绝缘体)。为进一步提高抗短路性,人们也提出在电极组件的下半部和电池壳的底部之间设置绝缘体(以下称下部绝缘体)(专利文献2)。A prismatic lithium secondary battery is used, for example, as a power source for cellular phones and digital still cameras. Since prismatic lithium secondary batteries are easier to fit into devices than cylindrical ones, they are becoming increasingly popular. In a prismatic lithium secondary battery, a lead wire connecting an electrode and a terminal is easily in contact with a battery case, which is different from a cylindrical lithium secondary battery. A short circuit occurs when a lead of the opposite polarity to the battery case contacts the battery case. Therefore, an insulator (hereinafter referred to as an upper insulator) is usually provided between the upper half of the electrode assembly and the cover (insulation plate) of the battery case. In order to further improve short-circuit resistance, it has also been proposed to provide an insulator (hereinafter referred to as a lower insulator) between the lower half of the electrode assembly and the bottom of the battery case (Patent Document 2).

棱柱形的锂二次电池的电极组件通常制造成从上部绝缘体的下表面到电池壳内底面的距离A和负极的宽度B之间满足关系式:B/A≤0.96。B/A的比值越高,电池容量越高。然而,如果B/A的比值过高,电极组件会对扭曲敏感,从而导致正极和负极间直接接触,即短路。在专利文献2中,通过设置用作缓冲器的下部绝缘体,B/A的比值设定为高达0.97。The electrode assembly of the prismatic lithium secondary battery is usually manufactured so that the distance A from the lower surface of the upper insulator to the inner bottom surface of the battery case and the width B of the negative electrode satisfy the relationship: B/A≤0.96. The higher the ratio of B/A, the higher the battery capacity. However, if the ratio of B/A is too high, the electrode assembly is sensitive to distortion, which leads to a direct contact between the positive and negative electrodes, i.e., a short circuit. In Patent Document 2, by providing a lower insulator serving as a buffer, the ratio of B/A is set as high as 0.97.

同时,当锂二次电池在极端高温环境下长时间保藏时,其由微孔膜制成的隔膜有收缩趋势。如果隔膜收缩,那么正极和负极实际上会彼此接触从而产生内部短路。考虑到近来的发展趋势是使隔膜变薄同时增加锂二次电池的容量,因此防止内部短路变得尤其重要。一旦内部短路发生,短路会因短路电流产生的焦耳热而扩大,从而导致电池过热。Meanwhile, when a lithium secondary battery is stored for a long time in an extremely high-temperature environment, its separator made of a microporous membrane tends to shrink. If the separator shrinks, the positive and negative electrodes actually touch each other creating an internal short circuit. Considering the recent trend of thinning the separator while increasing the capacity of lithium secondary batteries, preventing internal short circuits has become especially important. Once an internal short circuit occurs, the short circuit will expand due to the Joule heat generated by the short circuit current, resulting in overheating of the battery.

因此,在发生内部短路时,为抑制这类短路扩大,提出在电极活性材料层上形成含有无机填料(固体细颗粒)和粘合剂的多孔耐热层。氧化铝、二氧化硅等可用作无机填料。无机填料填在多孔耐热层中,此处的填料粒子用相对少量的粘合剂彼此粘结(专利文献3)。由于多孔耐热层即使在高温下都具有抗收缩性,故其起到在内部短路下抑制电池过热的作用。Therefore, in order to suppress the expansion of such a short circuit when an internal short circuit occurs, it has been proposed to form a porous heat-resistant layer containing an inorganic filler (solid fine particles) and a binder on the electrode active material layer. Alumina, silica, and the like can be used as the inorganic filler. Inorganic fillers are filled in the porous heat-resistant layer, where filler particles are bound to each other with a relatively small amount of binder (Patent Document 3). Since the porous heat-resistant layer has shrinkage resistance even at high temperatures, it functions to suppress overheating of the battery under internal short circuits.

专利文献1:日本专利申请No.平11-354084。Patent Document 1: Japanese Patent Application No. Hei 11-354084.

专利文献2:日本专利申请No.2004-31263。Patent Document 2: Japanese Patent Application No. 2004-31263.

专利文献3:日本专利申请No.平7-220759。Patent Document 3: Japanese Patent Application No. Hei 7-220759.

发明内容 Contents of the invention

本发明要解决的问题The problem to be solved by the present invention

为了实现具有高容量和出色的抗短路性的锂二次电池,可以将专利文献1或专利文献2的提议与专利文献3的提议组合采用。此组合明显减少了内部短路,但在电池受到冲击时,如下落时,会导致明显的容量损失。In order to realize a lithium secondary battery having high capacity and excellent short-circuit resistance, the proposal of Patent Document 1 or Patent Document 2 and the proposal of Patent Document 3 may be adopted in combination. This combination significantly reduces internal short circuits, but results in a significant loss of capacity when the battery is subjected to shocks, such as being dropped.

考虑到上述问题,本发明的目的之一是提供一种具有出色的抗短路性、能防止下落引起的容量损失并且能进行高容量设计的锂二次电池。In view of the above-mentioned problems, one of the objects of the present invention is to provide a lithium secondary battery having excellent short-circuit resistance, preventing capacity loss due to dropping, and capable of high-capacity design.

解决问题的方法way of solving the problem

本发明涉及一种锂二次电池,其包括:具有底部、侧壁和顶部开口的电池壳;电极组件;非水电解液;以及覆盖用以容纳电极组件和电解液的电池壳的顶部开口的密封板。电极组件包括与插入在正极和负极之间的多孔耐热层缠绕在一起的条形正极和条形负极。正极包括正极芯部件和涂在该芯部件上的正极活性材料层,并且负极包括负极芯部件和涂在该芯部件上的负极活性材料层。电池具有限制电极组件垂直移动的限制部位,并且从该限制部位到电池壳底部内表面的距离A与负极的宽度B之间满足关系式:0.965≤B/A≤0.995。The invention relates to a lithium secondary battery, which comprises: a battery case having a bottom, a side wall and a top opening; an electrode assembly; a non-aqueous electrolyte; sealing board. The electrode assembly includes a strip-shaped positive electrode and a strip-shaped negative electrode intertwined with a porous heat-resistant layer interposed between the positive electrode and the negative electrode. The positive electrode includes a positive electrode core member and a positive electrode active material layer coated on the core member, and the negative electrode includes a negative electrode core member and a negative electrode active material layer coated on the core member. The battery has a restriction position that restricts the vertical movement of the electrode assembly, and the distance A from the restriction position to the inner surface of the bottom of the battery case and the width B of the negative electrode satisfy the relationship: 0.965≤B/A≤0.995.

电池壳底部的内表面会有轻微的凹陷部分和突出部分。然而,在此情况下,凹陷部分和突出部分间的高度差通常不超过0.05mm,因此可忽略不计。此外,负极的宽度B是指条形负极的较短边的长度。也就是说,负极的宽度B对应于圆柱形电极组件中电极部分的最大高度处。The inner surface of the bottom of the battery case will have slight depressions and protrusions. In this case, however, the difference in height between the recessed portion and the protruding portion is usually not more than 0.05 mm and thus can be ignored. In addition, the width B of the negative electrode refers to the length of the shorter side of the strip-shaped negative electrode. That is, the width B of the negative electrode corresponds to the maximum height of the electrode portion in the cylindrical electrode assembly.

根据本发明的锂二次电池具有包含位于多孔耐热层和正极之间或多孔耐热层和负极之间的微孔膜的隔膜。A lithium secondary battery according to the present invention has a separator including a microporous membrane between a porous heat-resistant layer and a positive electrode or between a porous heat-resistant layer and a negative electrode.

多孔耐热层形成在,例如,正极活性材料层和负极活性材料层中至少一个的表面上。The porous heat-resistant layer is formed, for example, on the surface of at least one of the positive electrode active material layer and the negative electrode active material layer.

多孔耐热层包括,例如,绝缘填料和粘合剂。以100重量份的绝缘填料为基准,粘合剂的含量优选为1~10重量份。多孔耐热层优选具有40~80%的孔隙度。The porous heat-resistant layer includes, for example, insulating fillers and binders. Based on 100 parts by weight of the insulating filler, the content of the binder is preferably 1-10 parts by weight. The porous heat-resistant layer preferably has a porosity of 40 to 80%.

绝缘填料优选包含无机氧化物。无机氧化物优选包含氧化铝、二氧化硅、氧化镁、二氧化钛及氧化锆中的至少一种。The insulating filler preferably contains an inorganic oxide. The inorganic oxide preferably contains at least one of alumina, silica, magnesia, titania, and zirconia.

当电极组件基本为圆柱形并且电池壳为圆柱形时,限制部位优选采用设置在电池壳侧壁上半部的内径减小的电池壳的槽部。当距离A根据直径减小的槽部的深度变化时,从槽部的最深部分(朝电池壳的中心凸出最大的部分)到电池壳底部的内表面的距离为距离A。When the electrode assembly is substantially cylindrical and the battery case is cylindrical, the restricting portion is preferably a groove of the battery case with a reduced inner diameter provided on the upper half of the side wall of the battery case. When the distance A varies according to the depth of the reduced-diameter groove, the distance from the deepest portion of the groove (the portion that protrudes most toward the center of the battery case) to the inner surface of the bottom of the battery case is the distance A.

根据本发明的锂二次电池具有位于电极组件和密封板之间的绝缘体。在此情况下,当电极组件为基本椭圆的圆柱形并且电池壳为棱柱形时,限制部位优选为绝缘体的下半部表面。在棱柱形的锂二次电池中,从限制部位到电池壳底部的内表面的距离A与负极的宽度B之间优选满足关系式:0.975≤B/A≤0.995。A lithium secondary battery according to the present invention has an insulator between an electrode assembly and a sealing plate. In this case, when the electrode assembly is substantially elliptical cylindrical and the battery case is prismatic, the restricting portion is preferably the lower half surface of the insulator. In a prismatic lithium secondary battery, the distance A from the limiting portion to the inner surface of the bottom of the battery case and the width B of the negative electrode preferably satisfy the relationship: 0.975≤B/A≤0.995.

发明效果Invention effect

本发明可以提供一种具有出色的抗短路性和耐热性、能避免因冲击如下落引起的容量损失并且提供较高容量的锂二次电池。The present invention can provide a lithium secondary battery having excellent short-circuit resistance and heat resistance, avoiding capacity loss due to impact such as dropping, and providing higher capacity.

附图说明 Description of drawings

图1是本发明的一个圆柱形锂二次电池示例的剖面示意图;以及Fig. 1 is a schematic cross-sectional view of an example of a cylindrical lithium secondary battery of the present invention; and

图2是本发明的一个棱柱形锂二次电池示例的剖面示意图。Fig. 2 is a schematic cross-sectional view of an example of a prismatic lithium secondary battery of the present invention.

具体实施方式 Detailed ways

本发明涉及一种锂二次电池,其包括:具有底部、侧壁和顶部开口的电池壳;电极组件;非水电解液;以及覆盖用以容纳电极组件和电解液的电池壳的顶部开口的密封板。该电极组件包括与插入在正极和负极之间的多孔耐热层缠绕在一起的条形正极和条形负极。正极包括正极芯部件和涂在该芯部件上的正极活性材料层,并且负极包括负极芯部件和涂在该芯部件上的负极活性材料层。电池具有限制电极组件垂直移动的限制部位,并且从限制部位到电池壳底部的内表面的距离A与负极的宽度B之间满足关系式:0.965≤B/A≤0.995。The invention relates to a lithium secondary battery, which comprises: a battery case having a bottom, a side wall and a top opening; an electrode assembly; a non-aqueous electrolyte; sealing board. The electrode assembly includes a strip-shaped positive electrode and a strip-shaped negative electrode intertwined with a porous heat-resistant layer interposed between the positive electrode and the negative electrode. The positive electrode includes a positive electrode core member and a positive electrode active material layer coated on the core member, and the negative electrode includes a negative electrode core member and a negative electrode active material layer coated on the core member. The battery has a restricting part that restricts the vertical movement of the electrode assembly, and the distance A from the restricting part to the inner surface of the bottom of the battery case and the width B of the negative electrode satisfy the relationship: 0.965≤B/A≤0.995.

本发明人坚持不懈地研究了具有多孔耐热层的电极组件并有如下两个发现。The inventors of the present invention have persistently studied an electrode assembly having a porous heat-resistant layer and made the following two discoveries.

首先,带有多孔耐热层的电极组件与没有多孔耐热层的传统电极组件相比在充电/放电过程中具有较小的形变。这可能是因为多孔耐热层具有比正极、负极、以及隔膜更低的表面平整度,结果电极和隔膜不会滑动或移动。First, the electrode assembly with the porous heat-resistant layer has less deformation during the charging/discharging process than the conventional electrode assembly without the porous heat-resistant layer. This may be because the porous heat-resistant layer has a lower surface flatness than the positive electrode, the negative electrode, and the separator, so that the electrodes and the separator do not slide or move.

第二,当电极组件没有发生适当形变时,该电极组件不能稳固地固定在电池壳中。因此,当这种电池下落时,其电极组件中的电极会移动,从而导致容量损失。Second, when the electrode assembly is not properly deformed, the electrode assembly cannot be firmly fixed in the battery case. Therefore, when such a battery is dropped, the electrodes in its electrode assembly move, resulting in a loss of capacity.

基于这些发现,在本发明中,负极的宽度B和从限制部位到电池壳底部的内表面的距离A的比值(B/A的比值)被设为比传统值更高的范围。当B/A的比值满足关系式:0.965≤B/A≤0.995时,电极组件中电极的移动(尤其在电池下落时)明显受到抑制,从而不会发生容量损失。Based on these findings, in the present invention, the ratio of the width B of the negative electrode to the distance A from the restriction to the inner surface of the bottom of the battery case (ratio of B/A) is set to a higher range than the conventional value. When the ratio of B/A satisfies the relationship: 0.965≤B/A≤0.995, the movement of the electrodes in the electrode assembly (especially when the battery is dropped) is obviously suppressed, so that capacity loss does not occur.

如果B/A的比值超过0.96,电极组件的扭曲变大,这通常会导致短路。此外,锂二次电池的负极宽度通常设计成大于正极的宽度,因此负极的形变尤其是一个问题。然而,由于本发明中的电极组件具有多孔耐热层,即使负极的边缘在靠近电极组件上表面或下表面附近轻微变形,也不会发生短路。因此,B/A的比值可设定为0.965或更高。根据本发明,通过使负极的宽度接近于从限制部位到电池壳底部的内表面的距离A,可以在提高耐下落冲击的同时实现高容量。If the ratio of B/A exceeds 0.96, the distortion of the electrode assembly becomes large, which often causes a short circuit. In addition, the width of the negative electrode of lithium secondary batteries is usually designed to be larger than the width of the positive electrode, so deformation of the negative electrode is particularly a problem. However, since the electrode assembly in the present invention has a porous heat-resistant layer, even if the edge of the negative electrode is slightly deformed near the upper or lower surface of the electrode assembly, no short circuit will occur. Therefore, the ratio of B/A can be set to 0.965 or higher. According to the present invention, by making the width of the negative electrode close to the distance A from the restricting portion to the inner surface of the bottom of the battery case, high capacity can be achieved while improving drop impact resistance.

如果B/A的比值不到0.965,则难以实现高容量,此外,电池在下落时很可能因电极组件中的电极移动而有容量损失。另一方面,如果B/A的比值超过0.995,负极在靠近电极组件上表面或下表面处有明显变形。于是,多孔耐热层受到破坏,从而使内部短路易于发生。If the ratio of B/A is less than 0.965, it is difficult to achieve a high capacity, and in addition, the battery is likely to suffer capacity loss due to movement of electrodes in the electrode assembly when dropped. On the other hand, if the ratio of B/A exceeds 0.995, the negative electrode is significantly deformed near the upper or lower surface of the electrode assembly. Then, the porous heat-resistant layer is damaged, so that internal short circuit is liable to occur.

当0.965≤B/A≤0.995时,可以得到不会发生内部短路、具有高容量和出色的耐下落冲击的锂二次电池。When 0.965≦B/A≦0.995, a lithium secondary battery free from internal short circuit, high capacity and excellent drop impact resistance can be obtained.

根据本发明的锂二次电池可以具有或不具有包含微孔膜的隔膜。隔膜位于多孔耐热层和正极之间或多孔耐热层和负极之间。隔膜的作用在于支撑结构上易碎的多孔耐热层。因此,为进一步提高耐下落冲击,电池优选具有隔膜。The lithium secondary battery according to the present invention may or may not have a separator including a microporous membrane. The separator is located between the porous heat-resistant layer and the positive electrode or between the porous heat-resistant layer and the negative electrode. The role of the diaphragm is to support the fragile porous heat-resistant layer on the structure. Therefore, in order to further improve the drop impact resistance, the battery preferably has a separator.

微孔膜材料优选为聚烯烃,并且该聚烯烃优选为聚乙烯、聚丙烯等。也可使用同时包含聚乙烯和聚丙烯的微孔膜。微孔膜的厚度优选8~20μm以确保其起到支撑多孔耐热层并保持高容量设计的作用。The microporous membrane material is preferably polyolefin, and the polyolefin is preferably polyethylene, polypropylene or the like. Microporous membranes comprising both polyethylene and polypropylene can also be used. The thickness of the microporous membrane is preferably 8-20 μm to ensure that it can support the porous heat-resistant layer and maintain a high-capacity design.

多孔耐热层可以仅形成在正极活性材料层的表面上或负极活性材料层的表面上。或者,多孔耐热层可以同时形成在正极活性材料层的表面和负极活性材料层的表面上。然而,为了用可靠方式避免内部短路,多孔耐热层优选形成在设计成比正极活性材料层具有更大面积的负极活性材料层的表面上。此外,该多孔耐热层可以形成在芯部件的一个侧面上的活性材料层上或形成在芯部件的两个侧面上的活性材料层上。此外,多孔耐热层优选粘附在活性材料层的表面上。The porous heat-resistant layer may be formed only on the surface of the positive electrode active material layer or on the surface of the negative electrode active material layer. Alternatively, the porous heat-resistant layer may be formed simultaneously on the surface of the positive electrode active material layer and the surface of the negative electrode active material layer. However, in order to avoid internal short circuit in a reliable manner, the porous heat-resistant layer is preferably formed on the surface of the negative electrode active material layer designed to have a larger area than the positive electrode active material layer. In addition, the porous heat-resistant layer may be formed on the active material layer on one side of the core member or on the active material layer on both sides of the core member. In addition, the porous heat-resistant layer is preferably adhered on the surface of the active material layer.

多孔耐热层可以为独立的薄片。然而,由于薄片形的多孔耐热层没有高的机械强度,故可能难以处理。此外,多孔耐热层可以粘附在隔膜的表面上。然而,由于隔膜在高温下会收缩,故必须密切注意多孔耐热层的制造条件。为消除这类问题,多孔耐热层也优选形成在正极活性材料层的表面上或负极活性材料层的表面上。The porous heat-resistant layer can be an independent sheet. However, since the flake-shaped porous heat-resistant layer does not have high mechanical strength, it may be difficult to handle. In addition, a porous heat-resistant layer can be adhered to the surface of the separator. However, since the separator shrinks at high temperatures, close attention must be paid to the manufacturing conditions of the porous heat-resistant layer. In order to eliminate such problems, the porous heat-resistant layer is also preferably formed on the surface of the positive electrode active material layer or on the surface of the negative electrode active material layer.

多孔耐热层优选包含绝缘填料和粘合剂。使用刮片或口模式涂布机,将含有绝缘填料和少量粘合剂的原料浆料涂在电极活性材料层或隔膜的表面上并干燥后,形成该多孔耐热层。使用如一台双臂捏和机,将绝缘填料、粘合剂、以及液体组份进行混合,制备出原料浆料。The porous heat-resistant layer preferably contains insulating fillers and binders. The porous heat-resistant layer is formed after coating and drying a raw material slurry containing an insulating filler and a small amount of a binder on the surface of an electrode active material layer or a separator using a doctor blade or a die coater. The raw material slurry is prepared by mixing the insulating filler, binder, and liquid components using, for example, a two-arm kneader.

此外,多孔耐热层可以是由高耐热性的树脂的纤维形成的薄膜。高耐热性的树脂优选为芳族聚酰胺、聚酰胺酰亚胺等。然而,包含绝缘填料和粘合剂的多孔耐热层因粘合剂的作用而具有比高耐热性树脂的纤维形成的薄膜更高的结构强度,故其是优选的。In addition, the porous heat-resistant layer may be a film formed of fibers of a highly heat-resistant resin. The highly heat-resistant resin is preferably aramid, polyamideimide, or the like. However, a porous heat-resistant layer comprising an insulating filler and a binder has higher structural strength than a film formed of fibers of a high heat-resistant resin due to the action of the binder, and is therefore preferable.

多孔耐热层的厚度优选为0.5~20μm,并且进一步优选为1~10μm。如果多孔耐热层的厚度低于0.5μm,其抑制内部短路的效果降低。此外,如果多孔耐热层的厚度超过20μm,正极和负极间距离过大,这会导致电池的输出特性下降。The thickness of the porous heat-resistant layer is preferably 0.5 to 20 μm, and more preferably 1 to 10 μm. If the thickness of the porous heat-resistant layer is less than 0.5 μm, its effect of suppressing internal short circuits decreases. In addition, if the thickness of the porous heat-resistant layer exceeds 20 μm, the distance between the positive electrode and the negative electrode becomes too large, which leads to a decrease in the output characteristics of the battery.

绝缘填料可以包含纤维或高耐热性的树脂珠,但是优选包含无机氧化物。由于无机氧化物是硬的,故它们能使正极和负极间的距离即使在充电/放电引起电极膨胀时仍保持在合适的范围内。在无机氧化物中,尤其优选例如氧化铝、二氧化硅、氧化镁、二氧化钛、以及氧化锆,这是因为它们在锂二次电池的工作环境中具有较高的电化学稳定性。它们可以单独地或两个或更多个组合使用。The insulating filler may contain fibers or highly heat-resistant resin beads, but preferably contains inorganic oxides. Since the inorganic oxides are hard, they can keep the distance between the positive electrode and the negative electrode within an appropriate range even when the electrodes expand due to charging/discharging. Among inorganic oxides, such as alumina, silica, magnesia, titania, and zirconia are particularly preferable because they have high electrochemical stability in the working environment of a lithium secondary battery. They can be used alone or in combination of two or more.

在包含绝缘填料和粘合剂的多孔耐热层中,以100重量份的绝缘填料为基准,粘合剂的含量优选为1~10重量份,并且进一步优选为2~8重量份,以保持多孔耐热层的机械强度及其离子导电率。大多数的粘合剂和增稠剂会因含有非水溶剂的电解液而发生固有地溶胀。因此,如果粘合剂的含量超过10重量份,粘合剂会过度溶胀使多孔耐热层的微孔闭合,从而使离子导电率降低并阻止电池反应发生。另一方面,如果粘合剂的含量低于1重量份,多孔耐热层的机械强度降低。In the porous heat-resistant layer comprising an insulating filler and a binder, based on 100 parts by weight of the insulating filler, the content of the binder is preferably 1 to 10 parts by weight, and more preferably 2 to 8 parts by weight, so as to maintain The mechanical strength of the porous heat-resistant layer and its ionic conductivity. Most binders and thickeners inherently swell with electrolytes containing non-aqueous solvents. Therefore, if the content of the binder exceeds 10 parts by weight, the binder may excessively swell to close the micropores of the porous heat-resistant layer, thereby reducing ion conductivity and preventing battery reactions from occurring. On the other hand, if the content of the binder is less than 1 part by weight, the mechanical strength of the porous heat-resistant layer decreases.

用于多孔耐热层中的粘合剂并无特别限定,但优选为例如聚偏二氟乙烯(以下称PVDF)、聚四氟乙烯(以下称PTFE)、以及聚丙烯酸型橡胶粒子(例如Zeon公司的BM-500B(商品名))。优选将PTFE或BM-500B与增稠剂组合使用。增稠剂并无特别限定,但优选为例如羧甲基纤维素(以下称CMC)、聚环氧乙烷(以下称PEO)、以及改性丁腈橡胶(例如Zeon公司的BM-720H(商品名))。The binder used in the porous heat-resistant layer is not particularly limited, but is preferably, for example, polyvinylidene fluoride (hereinafter referred to as PVDF), polytetrafluoroethylene (hereinafter referred to as PTFE), and polyacrylic rubber particles (such as Zeon company's BM-500B (trade name)). It is preferred to use PTFE or BM-500B in combination with a thickener. The thickener is not particularly limited, but is preferably for example carboxymethyl cellulose (hereinafter referred to as CMC), polyethylene oxide (hereinafter referred to as PEO), and modified nitrile rubber (such as BM-720H of Zeon Company (commercial product) name)).

包含绝缘填料和粘合剂的多孔耐热层的孔隙度优选为40%~80%,并且进一步优选为45%~65%,以保持多孔耐热层的机械强度并提高其耐下落冲击。由于多孔耐热层具有比正极、负极、以及隔膜更低的表面平整度,故电极和隔膜的滑动(移动)受到极大抑制。于是,电极组件易于移动。然而,当具有40%~80%孔隙度的多孔耐热层浸入适量电解液时,电极组件会溶胀到合适的程度。于是,溶胀的电极组件压住了电池壳的内侧壁。当40%~80%孔隙度产生的效应和B/A最佳比值的效应互相促进时,耐下落冲击进一步得到提高。如果孔隙度低于40%,电解液没有充分浸润多孔耐热层,于是电极组件没有溶胀到合适的程度。另一方面,如果孔隙度超过80%,多孔耐热层的机械强度降低。The porosity of the porous heat-resistant layer including the insulating filler and the binder is preferably 40% to 80%, and further preferably 45% to 65% in order to maintain the mechanical strength of the porous heat-resistant layer and improve its drop impact resistance. Since the porous heat-resistant layer has lower surface flatness than the positive electrode, the negative electrode, and the separator, the sliding (movement) of the electrodes and the separator is greatly suppressed. Thus, the electrode assembly is easy to move. However, when the porous heat-resistant layer with a porosity of 40%-80% is immersed in an appropriate amount of electrolyte, the electrode assembly will swell to a suitable degree. Then, the swollen electrode assembly presses against the inner side wall of the battery case. When the effect of 40%-80% porosity and the effect of optimal B/A ratio promote each other, the drop impact resistance is further improved. If the porosity is lower than 40%, the electrolyte solution does not sufficiently infiltrate the porous heat-resistant layer, so that the electrode assembly does not swell to an appropriate degree. On the other hand, if the porosity exceeds 80%, the mechanical strength of the porous heat-resistant layer decreases.

应该注意到,多孔耐热层的孔隙度可以通过改变绝缘填料的中值粒径、粘合剂的含量以及原料浆料的干燥条件进行控制。例如,升高干燥温度或增加干燥用的热空气流量可导致孔隙度相对增加。孔隙度可由如下参数计算得到,例如,多孔耐热层的厚度、绝缘填料和粘合剂的含量、以及绝缘填料和粘合剂的实际比重。多孔耐热层的厚度可通过拍摄电极的几个横截面(例如10个横截面)的SEM照片及这几个横截面的平均厚度确定。此外,孔隙度可以用汞压测孔仪确定。It should be noted that the porosity of the porous heat-resistant layer can be controlled by changing the median particle size of the insulating filler, the content of the binder, and the drying conditions of the raw material slurry. For example, increasing the drying temperature or increasing the flow of hot air for drying can result in a relative increase in porosity. The porosity can be calculated from the following parameters, for example, the thickness of the porous heat-resistant layer, the content of insulating fillers and binders, and the actual specific gravity of insulating fillers and binders. The thickness of the porous heat-resistant layer can be determined by taking SEM photos of several cross-sections (for example, 10 cross-sections) of the electrode and the average thickness of these several cross-sections. Additionally, porosity can be determined using mercury porosimetry.

圆柱形锂二次电池具有截面基本为圆形的圆柱形(圆柱形)的电极组件。此外,圆柱形锂二次电池具有如图1所示的圆柱形电池壳100。该圆柱形电池壳一端开口并且另一端用平底110封闭。就常见的圆柱形锂二次电池而言,电池壳的开口边卷曲到密封板120的圆周上从而密封其顶部开口。在此情况下,限制电极组件垂直移动的限制部位是设置在电池壳100侧壁上半部的具有减小内径的电池壳100的槽部130。槽部130也有固定密封板120的功能。A cylindrical lithium secondary battery has a cylindrical (cylindrical) electrode assembly with a substantially circular cross section. In addition, the cylindrical lithium secondary battery has a cylindrical battery case 100 as shown in FIG. 1 . The cylindrical battery case is open at one end and closed with a flat bottom 110 at the other end. In the case of a common cylindrical lithium secondary battery, the open side of the battery case is crimped onto the circumference of the sealing plate 120 to seal the top opening thereof. In this case, the restricting portion restricting the vertical movement of the electrode assembly is the groove portion 130 of the battery case 100 having a reduced inner diameter provided on the upper half of the side wall of the battery case 100 . The groove portion 130 also has the function of fixing the sealing plate 120 .

棱柱形的锂二次电池具有横截面为基本椭圆的圆柱形(近椭圆形的圆柱形)的电极组件。此外,棱柱形锂二次电池具有如图2所示的棱柱形(基本为矩形的)的电池壳200。该棱柱形电池壳一端开口并且另一端用平底210封闭。就常见的棱柱形锂二次电池而言,电池壳的顶部开口通过将其开口边和金属密封板220焊接在一起密封。此外,绝缘体230(上部绝缘体)位于密封板220和电极组件之间以防止电极中的引线和电池壳200接触。绝缘体230具有电极引线通孔,从而使绝缘体几乎不移动。因此,限制电极组件垂直移动的限制部位为绝缘体230的下表面。A prismatic lithium secondary battery has an electrode assembly having a substantially elliptical cylindrical shape (nearly elliptical cylindrical shape) in cross section. In addition, the prismatic lithium secondary battery has a prismatic (substantially rectangular) battery case 200 as shown in FIG. 2 . The prismatic battery case is open at one end and closed with a flat bottom 210 at the other end. For a common prismatic lithium secondary battery, the top opening of the battery case is sealed by welding the opening edge and the metal sealing plate 220 together. In addition, an insulator 230 (upper insulator) is located between the sealing plate 220 and the electrode assembly to prevent lead wires in the electrode from contacting the battery case 200 . The insulator 230 has electrode lead through holes so that the insulator hardly moves. Therefore, the limiting portion that limits the vertical movement of the electrode assembly is the lower surface of the insulator 230 .

绝缘体的厚度优选为电池壳高度的2%~10%,从而确保其功能并减少死角。The thickness of the insulator is preferably 2% to 10% of the height of the battery case, so as to ensure its function and reduce dead space.

在圆柱形锂二次电池中,用作限制部位的槽部的纵剖面受生产方式的限制一般为V形或U形。因此,距离A的变化依赖于用作限制部位的槽部的深度。在此情况下,从槽部最深部分到电池壳底部的内表面的距离为距离A。在此情况下,如果B/A的比值为0.965或以上,可以获得足够的耐下落冲击。然而,考虑到高容量和耐下落冲击的平衡,圆柱形锂二次电池中更优选为0.970≤B/A≤0.990。In a cylindrical lithium secondary battery, the longitudinal section of the groove serving as a restricting part is generally V-shaped or U-shaped due to the limitation of the production method. Therefore, the distance A varies depending on the depth of the groove serving as the restricting portion. In this case, the distance from the deepest part of the groove to the inner surface of the bottom of the battery case is the distance A. In this case, if the ratio of B/A is 0.965 or more, sufficient drop impact resistance can be obtained. However, in consideration of the balance between high capacity and drop impact resistance, it is more preferable that 0.970≦B/A≦0.990 in cylindrical lithium secondary batteries.

另一方面,在棱柱形锂二次电池中,用作限制部位的绝缘体230的下表面是平的。因此,为获得出色的耐下落冲击,B/A的比值优选0.975或以上。此外,考虑到高容量和耐下落冲击的平衡,棱柱形锂二次电池中更优选为0.975≤B/A≤0990。On the other hand, in the prismatic lithium secondary battery, the lower surface of the insulator 230 serving as the confinement site is flat. Therefore, in order to obtain excellent drop impact resistance, the ratio of B/A is preferably 0.975 or more. In addition, in consideration of the balance between high capacity and drop impact resistance, 0.975≦B/A≦0990 is more preferable in the prismatic lithium secondary battery.

正极包括正极芯部件和涂在该芯部件各侧面上的正极活性材料层。正极芯部件为适于缠绕的条形并含有Al、Al合金等。正极活性材料层包含作为基本组分的正极活性材料以及视需要可包含的任选组分如导电剂和粘合剂。这些材料没有特别限定,但是优选的正极活性材料为含锂的过渡金属氧化物。在含锂的过渡金属氧化物中,优选为例如钴酸锂、改性钴酸锂、镍酸锂、改性镍酸锂、锰酸锂和改性锰酸锂。The positive electrode includes a positive electrode core member and a positive electrode active material layer coated on each side of the core member. The positive electrode core member is in a bar shape suitable for winding and contains Al, Al alloy, or the like. The positive electrode active material layer contains the positive electrode active material as an essential component and may contain optional components such as a conductive agent and a binder if necessary. These materials are not particularly limited, but a preferred cathode active material is a lithium-containing transition metal oxide. Among lithium-containing transition metal oxides, preferred are, for example, lithium cobaltate, modified lithium cobaltate, lithium nickelate, modified lithium nickelate, lithium manganate, and modified lithium manganate.

负极包括负极芯部件和涂在该芯部件各侧面上的负极活性材料层。负极芯部件为适于缠绕的条形并含有Cu、Cu合金等。负极的宽度B等于负极芯部件的宽度。负极活性材料层包含作为基本组分的负极活性材料及视需要可包含的任选组分如导电剂和粘合剂。这些材料没有特别限定,但优选的负极活性材料包括各种天然石墨、各种人造石墨、含硅的复合材料如硅化物、金属锂、以及各种合金材料。The negative electrode includes a negative electrode core member and a negative electrode active material layer coated on each side of the core member. The negative electrode core member is in a strip shape suitable for winding and contains Cu, Cu alloy, and the like. The width B of the negative electrode is equal to the width of the negative electrode core member. The negative electrode active material layer contains the negative electrode active material as an essential component and may contain optional components such as a conductive agent and a binder if necessary. These materials are not particularly limited, but preferred negative electrode active materials include various natural graphites, various artificial graphites, silicon-containing composite materials such as silicide, metal lithium, and various alloy materials.

例举的用于正极或负极的粘合剂包括PTFE、PVDF、以及丁苯橡胶。例举的导电剂包括乙炔黑、Ketjen黑(注册商标)、以及各种石墨。Exemplary binders for positive or negative electrodes include PTFE, PVDF, and styrene-butadiene rubber. Exemplary conductive agents include acetylene black, Ketjen black (registered trademark), and various graphites.

非水电解液优选含有非水溶剂及溶于其中的锂盐。锂盐没有特别限定,但优选为例如LiPF6和LiBF4。这些锂盐可以单独使用,也可以两种或多种组合使用。非水溶剂没有特别限定,但优选的例子包括碳酸乙二酯(EC)、碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、以及碳酸甲乙酯(EMC)。这些非水溶剂可以单独使用,也可以两种或多种组合使用。The non-aqueous electrolytic solution preferably contains a non-aqueous solvent and a lithium salt dissolved therein. The lithium salt is not particularly limited, but is preferably, for example, LiPF6 and LiBF4. These lithium salts may be used alone or in combination of two or more. The non-aqueous solvent is not particularly limited, but preferable examples include ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC). These nonaqueous solvents may be used alone or in combination of two or more.

电池壳的材料必须在锂二次电池的工作电压范围内电化学稳定。例如,优选使用铁或铝。此外,电池壳可以用镍或锡电镀。The material of the battery case must be electrochemically stable within the working voltage range of the lithium secondary battery. For example, iron or aluminum is preferably used. In addition, the battery case can be plated with nickel or tin.

图1是示范用的本发明的圆柱形锂二次电池的剖面示意图。FIG. 1 is a schematic cross-sectional view of a cylindrical lithium secondary battery of the present invention for demonstration.

通过将正极101和负极102与隔膜103以及插入在正极和负极之间的多孔耐热层(未显示)缠绕在一起,制造出圆柱形电极组件。隔膜103位于多孔耐热层和正极101之间。然而,如果多孔耐热层具有足够的厚度,隔膜103是不需要的。将电极组件插入圆柱形电池壳100中。电池壳100侧壁的上半部具有一内径相对小于其他部分的槽部130。槽部130是在电极组件放入电池壳100后形成的。槽部130的纵剖面是U形的。之后,将电解液注入到电池壳100中。电池壳100的顶部开口通过在槽部130上安装密封板120并将电池壳100的开口边卷曲在密封板120的圆周上密封。A cylindrical electrode assembly was fabricated by winding the positive electrode 101 and the negative electrode 102 together with the separator 103 and a porous heat-resistant layer (not shown) interposed between the positive and negative electrodes. The separator 103 is located between the porous heat-resistant layer and the positive electrode 101 . However, the separator 103 is unnecessary if the porous heat-resistant layer has a sufficient thickness. The electrode assembly was inserted into the cylindrical battery case 100 . The upper half of the side wall of the battery case 100 has a groove portion 130 whose inner diameter is relatively smaller than other parts. The groove portion 130 is formed after the electrode assembly is put into the battery case 100 . The longitudinal section of the groove portion 130 is U-shaped. After that, the electrolytic solution was injected into the battery case 100 . The top opening of the battery case 100 is sealed by installing the sealing plate 120 on the groove portion 130 and crimping the opening edge of the battery case 100 on the circumference of the sealing plate 120 .

厚度可忽略不计的上部绝缘体板106和下部绝缘体板107设置在电极组件的顶部和底下。正极导线104的一端连接到正极101的芯部件,而另一端连接到设置在密封板120下表面上的内部未端108a。内部未端108a和外部正极末端108之间是连续的。负极导线(未显示)的一端连接到负极102的芯部件,而另一端连接到电池壳100的内底面。An upper insulator plate 106 and a lower insulator plate 107 of negligible thickness are disposed on top and under the electrode assembly. One end of the positive electrode lead 104 is connected to the core member of the positive electrode 101 , and the other end is connected to the inner terminal 108 a provided on the lower surface of the sealing plate 120 . There is continuity between the inner terminal 108a and the outer positive terminal 108 . One end of a negative electrode lead (not shown) is connected to the core member of the negative electrode 102 , and the other end is connected to the inner bottom surface of the battery case 100 .

图2是示范用的本发明的棱柱形锂二次电池的剖面示意图。Fig. 2 is a schematic cross-sectional view of an exemplary prismatic lithium secondary battery of the present invention.

通过将正极和负极与隔膜以及插入在正极和负极之间的多孔耐热层缠绕在一起,制造出近椭圆形的圆柱形电极组件。电极组件201插入到基本为矩形的(棱柱形的)电池壳200中。在电极组件201放入电池壳200中后,绝缘体230安装在电极组件201的顶部以防止电池壳200或正极导线202的一端与负极导线203之间的短路。绝缘体230固定在电池壳200的开口附近。A nearly elliptical cylindrical electrode assembly is fabricated by winding the positive and negative electrodes together with a separator and a porous heat-resistant layer inserted between the positive and negative electrodes. The electrode assembly 201 is inserted into a substantially rectangular (prismatic) battery case 200 . After the electrode assembly 201 is put into the battery case 200 , an insulator 230 is installed on top of the electrode assembly 201 to prevent a short circuit between the battery case 200 or one end of the positive lead 202 and the negative lead 203 . The insulator 230 is fixed near the opening of the battery case 200 .

密封板220具有外围配有绝缘垫片206的负极末端207。负极导线203连接到负极末端207,而正极导线202连接到密封板220的下表面。The sealing plate 220 has a negative terminal 207 surrounded by an insulating gasket 206 . The negative electrode lead 203 is connected to the negative electrode terminal 207 , and the positive electrode lead 202 is connected to the lower surface of the sealing plate 220 .

电解液从密封板220中的注入孔注入到电池壳200中,并且该注入孔通过焊接用密封塞209密封。电池壳200的顶部开口通过装配密封板220并用激光焊接开口边和密封板220密封。The electrolytic solution is injected into the battery case 200 from an injection hole in the sealing plate 220 , and the injection hole is sealed by a sealing plug 209 for welding. The top opening of the battery case 200 is sealed by assembling a sealing plate 220 and welding the opening edge and the sealing plate 220 by laser.

下面将举例具体说明本发明的内容。The content of the present invention will be described in detail below with examples.

实施例1Example 1

在此实施例中,说明的是图1所示的圆柱形锂二次电池。In this embodiment, the cylindrical lithium secondary battery shown in FIG. 1 is explained.

(电池1)(Battery 1)

(i)正极的制备(i) Preparation of positive electrode

使用一台双臂捏合机,将3kg的钴酸锂、1kg的Kureha化学工业有限公司的PVDF#1320(含12wt%PVDF的N-甲基-2-吡咯烷酮(以下称作NMP)溶液)、90g的乙炔黑、以及适量的NMP进行搅拌,制备出正极混合物浆料。将所得的浆料涂在包含15μm厚铝箔的正极芯部件的两个侧面上,经干燥和辊压后形成了带有正极活性材料层的正极。该正极的总厚度为160μm。该正极被切割成宽度为56.5mm的条带。Using a double-arm kneader, 3 kg of lithium cobaltate, 1 kg of PVDF#1320 (N-methyl-2-pyrrolidone (hereinafter referred to as NMP) solution containing 12 wt % PVDF), 90 g of Kureha Chemical Industry Co., Ltd. Acetylene black and an appropriate amount of NMP were stirred to prepare a positive electrode mixture slurry. The resulting slurry was coated on both sides of a positive electrode core member comprising a 15 μm thick aluminum foil, dried and rolled to form a positive electrode with a positive electrode active material layer. The total thickness of the positive electrode was 160 μm. The positive electrode was cut into strips with a width of 56.5 mm.

(ii)负极的制备(ii) Preparation of negative electrode

使用一台双臂捏和机,将3kg的人造石墨、75g的Zeon公司的BM-400B(含40wt%改性丁苯橡胶的水分散体)、30g的CMC、以及适量的水进行搅拌,制备出负极混合物浆料。将所得的浆料涂在包含10μm厚铜箔的负极芯部件的两个侧面上,经干燥和辊压后形成了带有负极活性材料层的负极。该负极的总厚度为180μm。该负极被切割成宽度为57.5mm的条带。Using a double-arm kneader, the BM-400B (water dispersion containing 40wt% modified styrene-butadiene rubber) of 3kg of artificial graphite, 75g of Zeon Company, 30g of CMC, and an appropriate amount of water are stirred to prepare Get out the negative electrode mixture slurry. The resulting slurry was coated on both sides of a negative electrode core member comprising a 10 μm thick copper foil, dried and rolled to form a negative electrode with a negative electrode active material layer. The total thickness of the negative electrode was 180 μm. The negative electrode was cut into strips with a width of 57.5 mm.

(iii)多孔耐热层的形成(iii) Formation of porous heat-resistant layer

使用一台双臂捏和机,将970g的中值粒径为0.3μm的氧化铝(绝缘填料)、375g的Zeon公司的BM-720H(含8wt%改性聚丙烯腈橡胶的NMP溶液(粘合剂))、以及适量的NMP进行搅拌,制备出原料浆料。将所得的原料浆料涂在负极活性材料层的表面上,并用130℃的热空气(流量:1.5m/min)干燥4分钟,从而形成5μm厚的多孔耐热层。各个多孔耐热层的孔隙度为50%。孔隙度根据如下参数计算:通过拍摄其横截面的SEM照片确定的多孔耐热层的厚度;通过X射线荧光分析得到的给定区域的多孔耐热层中氧化铝的含量;氧化铝和粘合剂的实际比重;以及氧化铝与粘合剂间的重量比。Using a double-arm kneader, 970g of alumina (insulating filler) with a median particle size of 0.3 μm, 375g of Zeon’s BM-720H (NMP solution containing 8wt% modified polyacrylonitrile rubber (viscosity) mixture)), and an appropriate amount of NMP are stirred to prepare a raw material slurry. The resulting raw material slurry was coated on the surface of the negative electrode active material layer, and dried with hot air at 130° C. (flow rate: 1.5 m/min) for 4 minutes, thereby forming a 5 μm thick porous heat-resistant layer. The porosity of each porous heat-resistant layer was 50%. The porosity is calculated based on the following parameters: the thickness of the porous heat-resistant layer determined by taking SEM pictures of its cross-section; the alumina content of the porous heat-resistant layer in a given area by X-ray fluorescence analysis; alumina and adhesion the actual specific gravity of the agent; and the weight ratio between alumina and binder.

(iv)电解液的制备(iv) Preparation of electrolyte

将LiPF6以1mol/liter的浓度溶解在体积比为1:1:1的碳酸乙二酯(EC)、碳酸二甲酯(DMC)、以及碳酸甲乙酯(EMC)的溶剂混合物中,并且将该溶液和3wt%的碳酸乙烯酯混合,制备出电解液。LiPF6 was dissolved in a solvent mixture of ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) with a volume ratio of 1:1:1 at a concentration of 1mol/liter, and the This solution was mixed with 3 wt% ethylene carbonate to prepare an electrolytic solution.

(v)电池的制造(v) Manufacture of batteries

通过将两个侧面上形成多孔耐热层的负极和正极与插入其间的10μm厚的聚乙烯微孔膜(购自Celgard K.K.,宽度:60.7mm)的隔膜缠绕在一起,制造出圆柱形电极组件。A cylindrical electrode assembly was fabricated by winding the negative and positive electrodes with porous heat-resistant layers formed on both sides with a separator of 10 μm thick polyethylene microporous membrane (available from Celgard K.K., width: 60.7 mm) interposed therebetween .

然后将该电极组件插入到镀镍的铁的圆柱形电池壳中(内径:18mm)。应该注意到上部绝缘体板和下部绝缘体板分别位于电极组件的顶部和底下,因为它们非常薄,故其厚度可忽略不计。其后,在电池壳侧壁的上半部设置一槽部,此处电池壳的内径是减小的。该槽部的纵剖面是U形的,并且该直径减小的槽部的深度为1.5μm。从电池壳的内底面到该槽部的最深部分的距离A是60.5mm。The electrode assembly was then inserted into a nickel-plated iron cylindrical battery case (inner diameter: 18 mm). It should be noted that the upper and lower insulator plates are located on the top and bottom of the electrode assembly, respectively, and since they are very thin, their thicknesses are negligible. Thereafter, a groove portion is provided in the upper half of the side wall of the battery case where the inner diameter of the battery case is reduced. The longitudinal section of the groove portion was U-shaped, and the depth of the diameter-reduced groove portion was 1.5 μm. The distance A from the inner bottom surface of the battery case to the deepest part of the groove was 60.5 mm.

接着将5.5g的电解液注入到电极组件的中空部,从而使电极组件浸入电解液。其后,将密封板安装在电池壳的槽部上,并将电池壳的开口边卷曲在密封板的圆周上。制造出的圆柱形锂二次电池的内径为18mm,高度为65.0mm,并且设计容量为2200mAh。B/A的比值(负极的宽度B(57.5mm)与距离A(60.5mm)的比值)为0.950。Next, 5.5 g of electrolytic solution was injected into the hollow portion of the electrode assembly, thereby immersing the electrode assembly in the electrolytic solution. Thereafter, the sealing plate was mounted on the groove portion of the battery case, and the opening side of the battery case was crimped on the circumference of the sealing plate. The manufactured cylindrical lithium secondary battery had an inner diameter of 18 mm, a height of 65.0 mm, and a design capacity of 2200 mAh. The ratio of B/A (the ratio of the width B (57.5 mm) of the negative electrode to the distance A (60.5 mm)) was 0.950.

(电池2~5)(Battery 2~5)

用与电池1相同的制造方法制得圆柱形锂二次电池2~5,所不同的只是负极宽度B分别变为58.5mm、59.2mm、60.2mm、以及61.2mm,正极宽度分别变为57.5mm、58.2mm、59.2mm、以及60.2mm,设计容量分别变为2239mAh、2266mAh、2305mAh、以及2244mAh。各种电池中B/A的比值为0.967(电池2)、0.979(电池3)、0.995(电池4)、以及1.012(电池5)。Cylindrical lithium secondary batteries 2 to 5 were produced by the same manufacturing method as battery 1, except that the width B of the negative electrode was changed to 58.5mm, 59.2mm, 60.2mm, and 61.2mm respectively, and the width of the positive electrode was changed to 57.5mm respectively , 58.2mm, 59.2mm, and 60.2mm, the design capacity becomes 2239mAh, 2266mAh, 2305mAh, and 2244mAh respectively. The ratios of B/A in the various batteries were 0.967 (Battery 2), 0.979 (Battery 3), 0.995 (Battery 4), and 1.012 (Battery 5).

(电池6)(Battery 6)

用与电池3相同的制造方法制得圆柱形锂二次电池,所不同的只是多孔耐热层形成在正极活性材料层的表面上而不在负极活性材料层的表面上。A cylindrical lithium secondary battery was fabricated by the same manufacturing method as Battery 3, except that the porous heat-resistant layer was formed on the surface of the positive electrode active material layer instead of the surface of the negative electrode active material layer.

(电池7)(Battery 7)

用与电池4相同的制造方法制得圆柱形锂二次电池,所不同的只是多孔耐热层是形成在正极活性材料层的表面上而不在负极活性材料层的表面上。A cylindrical lithium secondary battery was fabricated by the same manufacturing method as battery 4, except that the porous heat-resistant layer was formed on the surface of the positive electrode active material layer instead of the surface of the negative electrode active material layer.

(电池8)(Battery 8)

用与电池3相同的制造方法制得圆柱形锂二次电池,所不同的只是多孔耐热层的厚度变为15μm并且没有用隔膜制造电极组件。A cylindrical lithium secondary battery was fabricated by the same fabrication method as Battery 3, except that the thickness of the porous heat-resistant layer was changed to 15 μm and the electrode assembly was not fabricated using a separator.

(电池9)(Battery 9)

用与电池3相同的制造方法制得圆柱形锂二次电池,所不同的只是多孔耐热层中的氧化铝变为具有相同中值粒径的氧化镁。A cylindrical lithium secondary battery was produced by the same manufacturing method as Battery 3, except that the aluminum oxide in the porous heat-resistant layer was changed to magnesium oxide having the same median particle size.

(电池10)(Battery 10)

用与电池3相同的制造方法制得圆柱形锂二次电池,所不同的只是多孔耐热层中的氧化铝变为具有相同中值粒径的二氧化硅。A cylindrical lithium secondary battery was fabricated by the same manufacturing method as battery 3, except that the alumina in the porous heat-resistant layer was changed to silica having the same median particle size.

(电池11)(Battery 11)

用与电池3相同的制造方法制得圆柱形锂二次电池,所不同的只是多孔耐热层中的氧化铝变为具有相同中值粒径的二氧化钛。A cylindrical lithium secondary battery was fabricated by the same manufacturing method as Battery 3, except that the alumina in the porous heat-resistant layer was changed to titania having the same median particle size.

(电池12)(Battery 12)

用与电池3相同的制造方法制得圆柱形锂二次电池,所不同的只是多孔耐热层中的氧化铝变为具有相同中值粒径的氧化锆。A cylindrical lithium secondary battery was produced by the same manufacturing method as battery 3, except that the alumina in the porous heat-resistant layer was changed to zirconia having the same median particle size.

(电池13)(Battery 13)

多孔耐热层的形成过程如下。The formation process of the porous heat-resistant layer is as follows.

将65g干燥的无水氯化钙加到1kg的NMP中,并在反应器中将混合物加热到80℃使其完全溶解。将所得的氯化钙的NMP溶液冷却至室温,接着将32g的对苯二胺加入其中并完全溶解。其后,将反应器置于20℃的恒温室中,并且在1小时内逐步将58g的二氯对苯二甲酸加入到NMP溶液中。该NMP溶液在20℃恒温室中放置1小时以使聚合反应进行,从而合成聚对苯二甲酰对苯二胺(以下称PPTA)。65 g of dry anhydrous calcium chloride was added to 1 kg of NMP, and the mixture was heated to 80° C. in the reactor to completely dissolve it. The obtained NMP solution of calcium chloride was cooled to room temperature, and then 32 g of p-phenylenediamine was added thereto and completely dissolved. Thereafter, the reactor was placed in a constant temperature room at 20° C., and 58 g of dichloroterephthalic acid was gradually added to the NMP solution within 1 hour. The NMP solution was left in a thermostatic chamber at 20° C. for 1 hour to allow polymerization to proceed, thereby synthesizing poly-p-phenylene terephthalamide (hereinafter referred to as PPTA).

在反应完成后,将NMP溶液(聚合液)从恒温室转放到真空室并减压搅拌30分钟以除气。用氯化钙的NMP溶液稀释所得的聚合液,制备出含1.4wt%PPTA的芳族聚酰胺树脂的NMP溶液。After the reaction was completed, the NMP solution (polymerization solution) was transferred from the thermostatic chamber to a vacuum chamber and stirred under reduced pressure for 30 minutes to degas. The obtained polymerization solution was diluted with an NMP solution of calcium chloride to prepare an NMP solution of an aramid resin containing 1.4 wt% of PPTA.

用刮片将所得的芳族聚酰胺树脂的NMP溶液涂在隔膜的一个表面上并用80℃的热空气(流量:0.5m/sec)干燥。用纯水充分清洗所得的芳族聚酰胺树脂薄膜,以除去氯化钙并在薄膜中形成微气孔。然后将该薄膜干燥,从而在隔膜的一个表面上形成5μm厚的多孔耐热层。该多孔耐热层的孔隙度为48%。电极组件制造成使多孔耐热层与正极相接触。多孔耐热层没有形成在负极活性材料层上。除上述不同之外,用与电池3相同的制造方法制得圆柱形锂二次电池。The resulting NMP solution of aramid resin was applied on one surface of the separator with a doctor blade and dried with hot air at 80°C (flow rate: 0.5 m/sec). The resulting aramid resin film was sufficiently washed with pure water to remove calcium chloride and form microvoids in the film. The film was then dried to form a 5 µm thick porous heat-resistant layer on one surface of the separator. The porosity of the porous heat-resistant layer was 48%. The electrode assembly is fabricated so that the porous heat-resistant layer is in contact with the positive electrode. A porous heat-resistant layer was not formed on the negative electrode active material layer. A cylindrical lithium secondary battery was produced by the same manufacturing method as Battery 3 except for the above differences.

(电池14)(Battery 14)

多孔耐热层的形成过程如下。The formation process of the porous heat-resistant layer is as follows.

将21g的一氯苯三酸酐和20g的二氨基二苯醚加入到1kg的NMP中,并将它们在室温下混合在一起,制备出聚酰胺酸的NMP溶液(聚酰胺酸含量:3.9wt%)。用刮片将所得的聚酰胺酸NMP溶液涂在隔膜的一个表面上。将所得的涂层膜用80℃的热空气干燥(流量:0.5m/sec)以使聚酰胺酸脱水成环,从而形成聚酰胺酰亚胺。通过这种方法,在隔膜的一个表面上形成5μm厚的多孔耐热层。该多孔耐热层的孔隙度为47%。极组件制造成使多孔耐热层与正极相接触。多孔耐热层没有形成在负极活性材料层上。除这些不同之外,用与电池3相同的制造方法制得圆柱形锂二次电池。The trichloromellitic anhydride of 21g and the diaminodiphenyl ether of 20g are added in the NMP of 1kg, and they are mixed together at room temperature, prepare the NMP solution of polyamic acid (polyamic acid content: 3.9wt% ). The resulting polyamic acid NMP solution was applied to one surface of the separator with a spatula. The resulting coating film was dried with hot air at 80° C. (flow rate: 0.5 m/sec) to dehydrate and ring the polyamic acid, thereby forming polyamideimide. By this method, a 5 μm thick porous heat-resistant layer was formed on one surface of the separator. The porosity of the porous heat-resistant layer was 47%. The pole assembly is fabricated such that the porous heat-resistant layer is in contact with the positive electrode. A porous heat-resistant layer was not formed on the negative electrode active material layer. A cylindrical lithium secondary battery was produced in the same manufacturing method as Battery 3 except for these differences.

(电池15)(Battery 15)

用刮片将用与电池13相同的方法制得的芳族聚酰胺树脂的NMP溶液涂在平滑的不锈钢(SUS)板上,并将所得的涂膜在120℃、减压干燥10小时。然后将该涂膜从SUS板中分离出来,从而获得15μm厚的独立薄片式的多孔耐热层。该多孔耐热层的孔隙度为51%。通过将正极和负极与插入其间的该薄片式的多孔耐热层,但不包括隔膜,缠绕在一起,制造出电极组件。多孔耐热层没有形成在负极活性材料层上。除上述不同之外,用与电池3相同的制造方法制得圆柱形锂二次电池。The NMP solution of the aramid resin prepared in the same manner as in Battery 13 was coated on a smooth stainless steel (SUS) plate with a doctor blade, and the resulting coating film was dried at 120°C for 10 hours under reduced pressure. The coating film was then separated from the SUS plate to obtain a 15 μm thick porous heat-resistant layer in the form of an independent sheet. The porosity of the porous heat-resistant layer was 51%. An electrode assembly is manufactured by winding a positive electrode and a negative electrode with the sheet-like porous heat-resistant layer interposed therebetween, but excluding the separator. A porous heat-resistant layer was not formed on the negative electrode active material layer. A cylindrical lithium secondary battery was produced by the same manufacturing method as Battery 3 except for the above differences.

(电池16)(Battery 16)

用刮片将用与电池14相同的方法制得的聚酰胺酸的NMP溶液涂在平滑的不锈钢(SUS)板上。将所得的涂层用80℃的热空气(流量:0.5m/sec)干燥以使聚酰胺酸脱水成环。然后将涂膜从SUS板中分离出来,从而获得15μm厚的独立薄片式的多孔耐热层。该多孔耐热层的孔隙度为52%。通过将正极和负极与插入其间的该薄片式的多孔耐热层,但不包括隔膜,缠绕在一起,制造出电极组件。多孔耐热层没有形成在负极活性材料层上。除上述不同之外,用与电池3相同的制造方法制得圆柱形锂二次电池。The NMP solution of polyamic acid prepared in the same manner as in Battery 14 was applied to a smooth stainless steel (SUS) plate with a spatula. The resulting coating was dried with hot air at 80° C. (flow rate: 0.5 m/sec) to dehydrate the polyamic acid to form a ring. The coating film was then separated from the SUS plate to obtain a 15 μm thick porous heat-resistant layer in the form of an independent sheet. The porosity of the porous heat-resistant layer was 52%. An electrode assembly is manufactured by winding a positive electrode and a negative electrode with the sheet-like porous heat-resistant layer interposed therebetween, but excluding the separator. A porous heat-resistant layer was not formed on the negative electrode active material layer. A cylindrical lithium secondary battery was produced by the same manufacturing method as Battery 3 except for the above differences.

(电池17)(Battery 17)

多孔耐热层的形成过程如下。The formation process of the porous heat-resistant layer is as follows.

使用一台双臂捏和机,将995g的氧化铝(中值粒径为0.3μm)、62.5g的Zeon公司的BM-720H、以及适量的NMP进行搅拌,制备出原料浆料。将所得的原料浆料涂在负极活性材料层的表面上,并用130℃的热空气(流量:1.5m/min)干燥4分钟,从而形成5μm厚的多孔耐热层。各个多孔耐热层的孔隙度为61%。除这些不同之外,用与电池3相同的制造方法制得圆柱形锂二次电池。A double-arm kneader was used to stir 995 g of alumina (median particle size: 0.3 μm), 62.5 g of Zeon BM-720H, and an appropriate amount of NMP to prepare a raw material slurry. The resulting raw material slurry was coated on the surface of the negative electrode active material layer, and dried with hot air at 130° C. (flow rate: 1.5 m/min) for 4 minutes, thereby forming a 5 μm thick porous heat-resistant layer. The porosity of each porous heat-resistant layer was 61%. A cylindrical lithium secondary battery was produced in the same manufacturing method as Battery 3 except for these differences.

(电池18)(Battery 18)

多孔耐热层的形成过程如下。The formation process of the porous heat-resistant layer is as follows.

使用一台双臂捏和机,将990g的氧化铝(中值粒径为0.3μm)、125g的Zeon公司的BM-720H、以及适量的NMP进行搅拌,制备出原料浆料。将所得的原料浆料涂在负极活性材料层的表面上,并用130℃的热空气(流量:1.5m/min)干燥4分钟,从而形成5μm厚的多孔耐热层。各个多孔耐热层的孔隙度为57%。除这些不同之外,用与电池3相同的制造方法制得圆柱形锂二次电池。A double-arm kneader was used to stir 990 g of alumina (median particle size: 0.3 μm), 125 g of Zeon BM-720H, and an appropriate amount of NMP to prepare a raw material slurry. The resulting raw material slurry was coated on the surface of the negative electrode active material layer, and dried with hot air at 130° C. (flow rate: 1.5 m/min) for 4 minutes, thereby forming a 5 μm thick porous heat-resistant layer. The porosity of each porous heat-resistant layer was 57%. A cylindrical lithium secondary battery was produced in the same manufacturing method as Battery 3 except for these differences.

(电池19)(Battery 19)

多孔耐热层的形成过程如下。使用一台双臂捏和机,将900g的氧化铝(中值粒径为0.3μm)、1250g的Zeon公司的BM-720H、以及适量的NMP进行搅拌,制备出原料浆料。将所得的原料浆料涂在负极活性材料层的表面上,并用130℃的热空气(流量:1.5m/mim)干燥4分钟,从而形成5μm厚的多孔耐热层。各个多孔耐热层的孔隙度为42%。除这些不同之外,用与电池3相同的制造方法制得圆柱形锂二次电池。The formation process of the porous heat-resistant layer is as follows. A double-arm kneader was used to stir 900 g of alumina (median particle size: 0.3 μm), 1250 g of Zeon BM-720H, and an appropriate amount of NMP to prepare a raw material slurry. The resulting raw material slurry was coated on the surface of the negative electrode active material layer, and dried with hot air at 130° C. (flow rate: 1.5 m/min) for 4 minutes, thereby forming a 5 μm thick porous heat-resistant layer. The porosity of each porous heat-resistant layer was 42%. A cylindrical lithium secondary battery was produced in the same manufacturing method as Battery 3 except for these differences.

(电池20)(Battery 20)

多孔耐热层的形成过程如下。The formation process of the porous heat-resistant layer is as follows.

使用一台双臂捏和机,将800g的氧化铝(中值粒径为0.3μm)、2500g的Zeon公司的BM-720H、以及适量的NMP进行搅拌,制备出原料浆料。将所得的原料浆料涂在负极活性材料层的表面上,并用130℃的热空气(流量:1.5m/mim)干燥4分钟,从而形成5μm厚的多孔耐热层。各个多孔耐热层的孔隙度为35%。除这些不同之外,用与电池3相同的制造方法制得圆柱形锂二次电池。A double-arm kneader was used to stir 800 g of alumina (median particle size: 0.3 μm), 2500 g of Zeon BM-720H, and an appropriate amount of NMP to prepare a raw material slurry. The resulting raw material slurry was coated on the surface of the negative electrode active material layer, and dried with hot air at 130° C. (flow rate: 1.5 m/min) for 4 minutes, thereby forming a 5 μm thick porous heat-resistant layer. The porosity of each porous heat-resistant layer was 35%. A cylindrical lithium secondary battery was produced in the same manufacturing method as Battery 3 except for these differences.

(电池21~25)(Battery 21~25)

用与电池3相同的制造方法制得圆柱形锂二次电池21~25,所不同的只是用于干燥涂覆的原料浆料以形成多孔耐热层过程的热空气的流量分别变为0.5m/min、1m/min、2m/min、5m/min、以及8m/min。各种电池的多孔耐热层的孔隙度为30%(电池21)、42%(电池22)、60%(电池23)、78%(电池24)、以及89%(电池25)。Cylindrical lithium secondary batteries 21 to 25 were produced in the same manufacturing method as battery 3, except that the flow rate of the hot air used to dry the coated raw material slurry to form a porous heat-resistant layer was changed to 0.5m respectively. /min, 1m/min, 2m/min, 5m/min, and 8m/min. The porosity of the porous heat-resistant layer of each battery was 30% (Battery 21), 42% (Battery 22), 60% (Battery 23), 78% (Battery 24), and 89% (Battery 25).

(电池26)(Battery 26)

用与电池1相同的制造方法制得圆柱形锂二次电池,所不同的只是隔膜的厚度变为15μm并且没有多孔耐热层形成。A cylindrical lithium secondary battery was fabricated by the same manufacturing method as Battery 1 except that the thickness of the separator was changed to 15 μm and no porous heat-resistant layer was formed.

(电池27)(Battery 27)

用与电池2相同的制造方法制得圆柱形锂二次电池,所不同的只是隔膜的厚度变为15μm并且没有多孔耐热层形成。A cylindrical lithium secondary battery was fabricated by the same manufacturing method as that of Battery 2, except that the thickness of the separator was changed to 15 μm and no porous heat-resistant layer was formed.

(电池28)(Battery 28)

用与电池3相同的制造方法制得圆柱形锂二次电池,所不同的只是隔膜的厚度变为15μm并且没有多孔耐热层形成。A cylindrical lithium secondary battery was fabricated by the same manufacturing method as Battery 3, except that the thickness of the separator was changed to 15 μm and no porous heat-resistant layer was formed.

(电池29)(Battery 29)

用与电池4相同的制造方法制得圆柱形锂二次电池,所不同的只是隔膜的厚度变为15μm并且没有多孔耐热层形成。A cylindrical lithium secondary battery was fabricated by the same manufacturing method as Battery 4, except that the thickness of the separator was changed to 15 μm and no porous heat-resistant layer was formed.

(电池30)(Battery 30)

用与电池5相同的制造方法制得圆柱形锂二次电池,所不同的只是隔膜的厚度变为15μm并且没有多孔耐热层形成。A cylindrical lithium secondary battery was fabricated by the same manufacturing method as Battery 5, except that the thickness of the separator was changed to 15 μm and no porous heat-resistant layer was formed.

各种电池进行两次预充电和放电,并且在45℃环境下保藏7天。之后,对它们进行如下评估。表1、表2、以及表3分别概括了多孔耐热层的特征、电池设计、以及评估结果。Each battery was precharged and discharged twice, and stored at 45°C for 7 days. Afterwards, they are evaluated as follows. Table 1, Table 2, and Table 3 summarize the characteristics of the porous heat-resistant layer, battery design, and evaluation results, respectively.

(内部短路检查)(internal short circuit check)

各种电池均制造100个样品。这些样品电池在20℃的环境下按如下条件进行放电,并测量它们的开路电压。其后,将这些电池在45℃环境下保藏10天并再次测量它们的开路电压。当电池在45℃环境下保藏前后的开路电压差值为0.3V或以上时,可确定这类电池处于内部短路状态。内部短路的发生率如表3所示。100 samples of each battery are manufactured. These sample batteries were discharged under the following conditions in an environment of 20° C., and their open circuit voltages were measured. Thereafter, these batteries were preserved for 10 days in an environment of 45° C. and their open circuit voltages were measured again. When the difference between the open circuit voltage of the battery before and after storage at 45°C is 0.3V or more, it can be determined that this type of battery is in an internal short circuit state. The occurrence rate of internal short circuit is shown in Table 3.

恒流充电:充电电流1500mA/充电终止电压4.2V;Constant current charging: charging current 1500mA/charging termination voltage 4.2V;

恒压充电:充电电压4.2V/充电终止电流100mA。Constant voltage charging: charging voltage 4.2V/charging termination current 100mA.

(下落试验)(drop test)

经过内部短路检查的电池在20℃环境下按如下条件进行充电和放电,并且获得它们的放电容量。The batteries subjected to the internal short-circuit inspection were charged and discharged under the following conditions in an environment of 20° C., and their discharge capacities were obtained.

恒流充电:充电电流1500mA/充电终止电压4.2V;Constant current charging: charging current 1500mA/charging termination voltage 4.2V;

恒压充电:充电电压4.2V/充电终止电流100mA;Constant voltage charging: charging voltage 4.2V/charging termination current 100mA;

恒流放电:放电电流2200mA/放电终止电压3V。Constant current discharge: discharge current 2200mA/discharge termination voltage 3V.

其后,这些电池在20℃环境下从16cm高处重复下落30次,然后按上述条件进行充电和放电,并获得它们的放电容量。于是获得下落试验后放电容量相对下落试验前放电容量的百分比。耐下落冲击的结果如表3所示。Thereafter, these batteries were repeatedly dropped from a height of 16 cm 30 times in an environment of 20°C, and then charged and discharged under the above-mentioned conditions, and their discharge capacities were obtained. The percentage of the discharge capacity after the drop test relative to the discharge capacity before the drop test was thus obtained. The results of drop impact resistance are shown in Table 3.

(下落试验后内部短路检查)(Internal short circuit inspection after drop test)

下落试验后,用与下落试验前相同的方法检查电池内部短路。下落后内部短路发生率的结果如表3所示。After the drop test, use the same method as before the drop test to check the internal short circuit of the battery. Table 3 shows the results of the occurrence rate of internal short circuits after dropping.

(高输出特性)(high output characteristics)

各种电池在20℃环境下按如下条件进行充电和放电,并且获得它们的放电容量。Various batteries were charged and discharged under the following conditions in an environment of 20° C., and their discharge capacities were obtained.

恒流充电:充电电流1500mA/充电终止电压4.2V;Constant current charging: charging current 1500mA/charging termination voltage 4.2V;

恒压充电:充电电压4.2V/充电终止电流100mA;Constant voltage charging: charging voltage 4.2V/charging termination current 100mA;

恒流放电:放电电流440mA/放电终止电压3V;Constant current discharge: discharge current 440mA/discharge termination voltage 3V;

恒流充电:充电电流1500mA/充电终止电压4.2V;Constant current charging: charging current 1500mA/charging termination voltage 4.2V;

恒压充电:充电电压4.2V/充电终止电流100mA;Constant voltage charging: charging voltage 4.2V/charging termination current 100mA;

恒流放电:放电电流4400mA/放电终止电压3V。Constant current discharge: discharge current 4400mA/discharge termination voltage 3V.

于是可获得电池在4400mA下的放电容量相对其在440mA下的放电容量的百分比。高输出特性结果如表3所示。The percentage of the battery's discharge capacity at 4400 mA relative to its discharge capacity at 440 mA can then be obtained. Table 3 shows the high output characteristic results.

(钉穿刺试验)(nail puncture test)

各种电池在2200mA的充电电流下充电至4.35V的截止电压。在20℃的环境下,将铁钉(直径为2.7mm)以5mm/sec的速度敲入各种充电的电池的侧壁中,并用附于电池侧壁上的热电偶测定电池温度。90秒后的电池温度如表3所示。Various batteries were charged to a cut-off voltage of 4.35V at a charging current of 2200mA. In an environment of 20°C, an iron nail (2.7 mm in diameter) was driven into the side walls of various charged batteries at a speed of 5 mm/sec, and the temperature of the batteries was measured with a thermocouple attached to the side walls of the batteries. The battery temperature after 90 seconds is shown in Table 3.

表1Table 1

  电池 多孔耐热层(μm)      多孔耐热层的位置 隔膜(μm) 填料 粘合剂含量(wt%)     孔隙度(%)   1 5 负极 10 氧化铝 3 50 2 5 负极 10 氧化铝 3 50 3 5 负极 10 氧化铝 3 50 4 5 负极 10 氧化铝 3 50 5 5 负极 10 氧化铝 3 50 6 5 正极 10 氧化铝 3 50 7 5 正极 10 氧化铝 3 50 8 15 负极 氧化铝 3 50 9 5 负极 10 氧化镁 3 50 10 5 负极 10 二氧化硅 3 50 11 5 负极 10 二氧化钛 3 50 12 5 负极 10 氧化锆 3 50 13 5 隔膜 10 芳族聚酰胺 48 14 5 隔膜 10 聚酰胺酰亚胺 47 15 15 独立的薄片片       芳族聚酰胺 51 16 15 独立的薄片片       聚酰胺酰亚胺 52 17 5 负极 10 氧化铝 0.5 61 18 5 负极 10 氧化铝 1 57 19 5 负极 10 氧化铝 10 42 20 5 负极 10 氧化铝 20 35 21 5 负极 10 氧化铝 3 30 22 5 负极 10 氧化铝 3 42 23 5 负极 10 氧化铝 3 60 24 5 负极 10 氧化铝 3 78 25 5 负极 10 氧化铝 3 89 26 15 27 15 28 15 29 15 30 15 Battery Porous heat-resistant layer (μm) The location of the porous heat-resistant layer Diaphragm (μm) filler Binder content (wt%) Porosity(%) 1 5 negative electrode 10 Aluminum oxide 3 50 2 5 negative electrode 10 Aluminum oxide 3 50 3 5 negative electrode 10 Aluminum oxide 3 50 4 5 negative electrode 10 Aluminum oxide 3 50 5 5 negative electrode 10 Aluminum oxide 3 50 6 5 positive electrode 10 Aluminum oxide 3 50 7 5 positive electrode 10 Aluminum oxide 3 50 8 15 negative electrode none Aluminum oxide 3 50 9 5 negative electrode 10 magnesium oxide 3 50 10 5 negative electrode 10 silica 3 50 11 5 negative electrode 10 Titanium dioxide 3 50 12 5 negative electrode 10 Zirconia 3 50 13 5 diaphragm 10 Aramid 48 14 5 diaphragm 10 polyamideimide 47 15 15 individual flakes none Aramid 51 16 15 individual flakes none polyamideimide 52 17 5 negative electrode 10 Aluminum oxide 0.5 61 18 5 negative electrode 10 Aluminum oxide 1 57 19 5 negative electrode 10 Aluminum oxide 10 42 20 5 negative electrode 10 Aluminum oxide 20 35 twenty one 5 negative electrode 10 Aluminum oxide 3 30 twenty two 5 negative electrode 10 Aluminum oxide 3 42 twenty three 5 negative electrode 10 Aluminum oxide 3 60 twenty four 5 negative electrode 10 Aluminum oxide 3 78 25 5 negative electrode 10 Aluminum oxide 3 89 26 none 15 27 none 15 28 none 15 29 none 15 30 none 15

表2Table 2

  电池 负极宽度B(mm)      正极宽度(mm)     设计容量(mAh)    B/A 1 57.5 56.5 2200 0.950 2 58.5 57.5 2239 0.967 3 59.2 58.2 2266 0.979 4 60.2 59.2 2305 0.995 5 61.2 60.2 2344 1.012 6 59.2 58.2 2266 0.979 7 60.2 59.2 2305 0.995 8 59.2 58.2 2266 0.979 9 59.2 58.2 2266 0.979 10 59.2 58.2 2266 0.979 11 59.2 58.2 2266 0.979 12 59.2 58.2 2266 0.979 13 59.2 58.2 2266 0.979 14 59.2 58.2 2266 0.979 15 59.2 58.2 2266 0.979 16 59.2 58.2 2266 0.979 17 59.2 58.2 2266 0.979 18 59.2 58.2 2266 0.979 19 59.2 58.2 2266 0.979 20 59.2 58.2 2266 0.979 21 59.2 58.2 2266 0.979 22 59.2 58.2 2266 0.979 23 59.2 58.2 2266 0.979 24 59.2 58.2 2266 0.979 25 59.2 58.2 2266 0.979 26 57.5 56.5 2200 0.950 27 58.5 57.5 2239 0.967 28 59.2 58.2 2266 0.979 29 60.2 59.2 2305 0.995 30 61.2 60.2 2344 1.012 Battery Negative electrode width B(mm) Positive electrode width (mm) Design capacity (mAh) B/A 1 57.5 56.5 2200 0.950 2 58.5 57.5 2239 0.967 3 59.2 58.2 2266 0.979 4 60.2 59.2 2305 0.995 5 61.2 60.2 2344 1.012 6 59.2 58.2 2266 0.979 7 60.2 59.2 2305 0.995 8 59.2 58.2 2266 0.979 9 59.2 58.2 2266 0.979 10 59.2 58.2 2266 0.979 11 59.2 58.2 2266 0.979 12 59.2 58.2 2266 0.979 13 59.2 58.2 2266 0.979 14 59.2 58.2 2266 0.979 15 59.2 58.2 2266 0.979 16 59.2 58.2 2266 0.979 17 59.2 58.2 2266 0.979 18 59.2 58.2 2266 0.979 19 59.2 58.2 2266 0.979 20 59.2 58.2 2266 0.979 twenty one 59.2 58.2 2266 0.979 twenty two 59.2 58.2 2266 0.979 twenty three 59.2 58.2 2266 0.979 twenty four 59.2 58.2 2266 0.979 25 59.2 58.2 2266 0.979 26 57.5 56.5 2200 0.950 27 58.5 57.5 2239 0.967 28 59.2 58.2 2266 0.979 29 60.2 59.2 2305 0.995 30 61.2 60.2 2344 1.012

表3table 3

  电池 短路发生率(%)       耐下落冲击(%)       下落后短路发生率(%)             高输出特性(%)       钉刺后电池温度(℃)           1 0 93.0 2 90.3 86 2 0 99.8 1 91.4 85 3 0 99.9 0 90.6 84 4 0 99.7 0 92.3 86 5 24 99.8 2 91.9 83 6 2 100.0 0 90.2 83 7 14 99.5 9 88.7 90 8 3 99.7 19 86.6 83 9 0 99.7 0 88.9 84 10 0 99.8 0 88.7 86 11 0 99.9 2 88.6 81 12 0 99.9 0 88.9 86 13 0 99.7 8 89.2 86 14 0 99.6 9 89.5 82 15 3 99.5 16 90.1. 91 16 1 99.8 14 90.6 92 17 0 99.8 11 90.1 94 18 0 99.8 0 88.9 89 19 0 99.8 2 83.8 80 20 0 99.9 0 79.5 80 21 0 95.7 0 82.4 83 22 0 98.6 0 87.9 84 23 0 99.8 0 89.0 88 24 0 99.7 6 90.5 85 25 0 100.0 10 93.4 90 26 0 99.7 0 88.1 128 27 15 99.9 0 88.2 124 28 22 99.8 0 87.9 126 29 30 99.8 0 89.1 130 30 46 99.8 0 88.8 124 Battery Short circuit occurrence rate (%) Drop impact resistance (%) Occurrence rate of short circuit after falling (%) High output characteristics (%) Battery temperature after nailing (°C) 1 0 93.0 2 90.3 86 2 0 99.8 1 91.4 85 3 0 99.9 0 90.6 84 4 0 99.7 0 92.3 86 5 twenty four 99.8 2 91.9 83 6 2 100.0 0 90.2 83 7 14 99.5 9 88.7 90 8 3 99.7 19 86.6 83 9 0 99.7 0 88.9 84 10 0 99.8 0 88.7 86 11 0 99.9 2 88.6 81 12 0 99.9 0 88.9 86 13 0 99.7 8 89.2 86 14 0 99.6 9 89.5 82 15 3 99.5 16 90.1. 91 16 1 99.8 14 90.6 92 17 0 99.8 11 90.1 94 18 0 99.8 0 88.9 89 19 0 99.8 2 83.8 80 20 0 99.9 0 79.5 80 twenty one 0 95.7 0 82.4 83 twenty two 0 98.6 0 87.9 84 twenty three 0 99.8 0 89.0 88 twenty four 0 99.7 6 90.5 85 25 0 100.0 10 93.4 90 26 0 99.7 0 88.1 128 27 15 99.9 0 88.2 124 28 twenty two 99.8 0 87.9 126 29 30 99.8 0 89.1 130 30 46 99.8 0 88.8 124

在负极宽度B相对从槽部(限制部位)到电池壳内底面的距离A过小的电池1中,容量密度较较小,此外耐下落冲击较低。下落试验后,将电池1拆开进行观察,结果发现缠绕电极组件的电极有移动。In the battery 1 in which the width B of the negative electrode is too small relative to the distance A from the groove portion (restricted portion) to the inner bottom surface of the battery case, the capacity density is low, and the drop impact resistance is low. After the drop test, the battery 1 was disassembled for observation, and it was found that the electrodes of the wound electrode assembly moved.

电池1因多孔耐热层的作用而没发生内部短路,但有效面积(正极和负极彼此相对的面积)的减小导致其容量损失。因配有多孔耐热层,其电极组件可以抗形变,故其不能稳固地固定在电池壳的内侧。缠绕电极组件的电极在重复下落时可能因此而发生移动。The battery 1 did not suffer from internal short circuit due to the effect of the porous heat-resistant layer, but the reduction in the effective area (the area where the positive and negative electrodes face each other) resulted in loss of its capacity. With a porous heat-resistant layer, its electrode assembly can resist deformation, so it cannot be firmly fixed on the inside of the battery case. The electrodes of the wound electrode assembly may thus move when dropped repeatedly.

另一方面,在负极宽度B相对从槽部到电池壳内底面的距离A过大的电池5中,耐短路性较低。将确定处于内部短路态的电池5的样品拆开进行观察。结果发现负极表面上的多孔耐热层在电极组件的上半部有损坏。还发现隔膜发生开裂。On the other hand, in the battery 5 in which the negative electrode width B is too large relative to the distance A from the groove portion to the inner bottom surface of the battery case, the short-circuit resistance is low. A sample of battery 5 determined to be in an internal short-circuit state was disassembled for observation. It was found that the porous heat-resistant layer on the surface of the negative electrode was damaged in the upper half of the electrode assembly. It was also found that the septum cracked.

在B/A的比值在0.965~0.995的电池2~4中,耐短路性较高,此外耐下落冲击得到提高。本发明的电池除隔膜外还配有多孔耐热层。因此,即使当负极比正极宽、电极组件上半部有轻微变形时,由多孔耐热层和隔膜组成的双层结构使变形部分绝缘。此外,由于B/A的比值较高,电极组件稳固地夹在槽部和电池壳的内底面间。电池的耐下落冲击可能因此而得到提高。Batteries 2 to 4 having a B/A ratio of 0.965 to 0.995 had high short-circuit resistance and improved drop impact resistance. The battery of the present invention is equipped with a porous heat-resistant layer in addition to the separator. Therefore, even when the negative electrode is wider than the positive electrode and the upper half of the electrode assembly is slightly deformed, the double-layer structure consisting of the porous heat-resistant layer and the separator insulates the deformed part. In addition, due to the high ratio of B/A, the electrode assembly is firmly sandwiched between the groove portion and the inner bottom surface of the battery case. The battery's drop impact resistance may thus be improved.

在没有多孔耐热层的电池26~30中,耐下落冲击不受限制部位位置的影响均是优良的。人们相信,没有多孔耐热层的电极组件变形到一合适程度,故其稳固地固定在电池壳内。即使在这些电池下落时,导致容量损失的缠绕电极组件的电极移动可能因此而受到抑制。然而,这些电池26~30在钉穿刺试验中明显过热。此外,在限制部位位置分别与电池2~4相同的电池27~29中,耐短路性较低。人们相信,这些电池27~29的负极有轻微变形。然而,由于这些电池没有多孔耐热层,当隔膜因负极形变发生开裂时,内部短路不能防止。In the batteries 26 to 30 having no porous heat-resistant layer, the drop impact resistance was excellent regardless of the position of the restricting portion. It is believed that the electrode assembly without the porous heat-resistant layer deforms to an appropriate degree so that it is firmly held within the battery case. Even when these batteries are dropped, electrode movement of the wound electrode assembly, which causes capacity loss, may thus be suppressed. However, these batteries 26-30 significantly overheated in the nail puncture test. In addition, in the batteries 27 to 29 having the same restriction positions as the batteries 2 to 4, the short-circuit resistance is low. It is believed that the negative electrodes of these batteries 27-29 were slightly deformed. However, since these batteries do not have a porous heat-resistant layer, internal short circuits cannot be prevented when the separator cracks due to deformation of the negative electrode.

在电池6和7中,多孔耐热层形成在正极活性材料层的表面上。在这两种电池中,具有更宽负极的电池7显示出相对低的耐短路性。这可能是因为多孔耐热层形成在比负极活性材料层更窄的正极活性材料层的表面上,于是负极表面在电极组件的上半部与正极的上边缘相接触。In Batteries 6 and 7, a porous heat-resistant layer was formed on the surface of the positive electrode active material layer. Of these two batteries, battery 7 with a wider negative electrode showed relatively low short-circuit resistance. This may be because the porous heat-resistant layer is formed on the surface of the cathode active material layer which is narrower than the anode active material layer, so that the anode surface is in contact with the upper edge of the cathode at the upper half of the electrode assembly.

在没有隔膜的电池8中,其落下后的耐短路性略低。其多孔耐热层结构上比隔膜更易碎。于是,多孔耐热层受下落冲击作用而局部损坏,从而发生短路。In battery 8 without a separator, its short-circuit resistance after being dropped was slightly lower. Its porous heat-resistant layer is structurally more fragile than the diaphragm. Then, the porous heat-resistant layer is partially damaged by the impact of the drop, so that a short circuit occurs.

在隔膜表面有由耐热树脂制成的多孔耐热层的电池13和14中,落下后的耐短路性略低。耐热树脂制成的多孔耐热层的机械强度低于包含绝缘填料和粘合剂的多孔耐热层的机械强度。通过下落冲击作用可能因此而发生短路。In Batteries 13 and 14 having a porous heat-resistant layer made of a heat-resistant resin on the surface of the separator, the short-circuit resistance after dropping was slightly lower. The mechanical strength of a porous heat-resistant layer made of a heat-resistant resin is lower than that of a porous heat-resistant layer comprising an insulating filler and a binder. A short circuit may thus occur due to the impact of the drop.

在具有独立的多孔耐热层薄片并且没有隔膜的电池15和16中,它们下落后的耐短路性低于电池13和电池14下落后的耐短路性。这源于该事实,即耐热树脂制成的多孔耐热层强度差并且多孔耐热层的强度没有因隔膜的缺少而得到提高。In Batteries 15 and 16 having separate porous heat-resistant layer sheets and no separator, their short-circuit resistance after dropping was lower than that of Batteries 13 and 14 after being dropped. This stems from the fact that the porous heat-resistant layer made of heat-resistant resin is poor in strength and the strength of the porous heat-resistant layer is not improved by the absence of the separator.

在多孔耐热层中含0.5wt%粘合剂的电池17中,落下后的耐短路性略低。这可能是因为低含量的粘合剂减弱了填料粒子的粘附力,从而导致多孔耐热层的机械强度较差。In Battery 17 containing 0.5% by weight of the binder in the porous heat-resistant layer, the short-circuit resistance after dropping was slightly lower. This may be because the low content of binder weakens the adhesion of filler particles, resulting in poor mechanical strength of the porous heat-resistant layer.

另一方面,在含有20wt%粘合剂的电池20中,高输出特性较低。这可能是因为过量的粘合剂降低了多孔耐热层的孔隙度,此外,过量的粘合剂随电解液溶胀,从而使多孔耐热层的微孔闭合并降低了离子导电率。另一方面,在粘合剂含量为1wt%~10wt%的电池18~19中,耐短路性和高输出特性都是优良的。On the other hand, in the battery 20 containing 20 wt% of the binder, the high output characteristics were low. This may be because the excess binder reduces the porosity of the porous heat-resistant layer, and in addition, the excess binder swells with the electrolyte, which closes the micropores of the porous heat-resistant layer and reduces the ionic conductivity. On the other hand, in Batteries 18 to 19 having a binder content of 1 wt % to 10 wt %, both the short circuit resistance and high output characteristics were excellent.

在因控制干燥条件获得的带有30%孔隙度的多孔耐热层的电池21中,耐下落冲击略低。其原因可能如下。由于孔隙度较低,多孔耐热层没有充分地浸润电解液,于是电极组件的溶胀较小。因此,不能防止电极组件在下落时移动。在具有89%孔隙度的多孔耐热层的电池25中,落下后的耐短路性略低。这可能是因为多孔耐热层的机械强度较差。In the battery 21 with a porous heat-resistant layer having a porosity of 30% obtained by controlling the drying conditions, the drop impact resistance was slightly lower. The reason for this may be as follows. Due to the lower porosity, the porous heat-resistant layer does not fully infiltrate the electrolyte, so the swelling of the electrode assembly is less. Therefore, the electrode assembly cannot be prevented from moving when dropped. In Battery 25 having a porous heat-resistant layer with a porosity of 89%, the short-circuit resistance after being dropped was slightly low. This may be due to the poor mechanical strength of the porous heat-resistant layer.

另一方面,在带有孔隙度为40%~80%的多孔耐热层的电池22~24中,耐下落冲击和落下后的耐短路性均是优良的。其原因可能如下。由于最佳化的孔隙度,多孔耐热层的机械强度得到保持。此外,多孔耐热层随电解液溶胀到一合适程度。结果防止了电极组件的移动。On the other hand, in the batteries 22 to 24 with porous heat-resistant layers having a porosity of 40% to 80%, both drop impact resistance and short circuit resistance after drop were excellent. The reason for this may be as follows. Due to the optimized porosity, the mechanical strength of the porous heat-resistant layer is maintained. In addition, the porous heat-resistant layer swells to a suitable degree with the electrolyte. As a result, movement of the electrode assembly is prevented.

实施例2Example 2

在该实施例中,说明的是图2所示的棱柱形锂二次电池。In this embodiment, the prismatic lithium secondary battery shown in FIG. 2 is explained.

(电池31)(battery 31)

除如下不同之外,用与实施例1相同的制造方法制得电极组件。正极的总厚度变为150μm,正极的宽度变为42.7mm。负极的总厚度变为150μm,负极的宽度变为43.7mm。隔膜的宽度变为47mm。电极组件的形状变为椭圆的圆柱形。An electrode assembly was produced in the same manufacturing method as in Example 1 except for the following differences. The total thickness of the positive electrode becomes 150 μm, and the width of the positive electrode becomes 42.7 mm. The total thickness of the negative electrode became 150 μm, and the width of the negative electrode became 43.7 mm. The width of the diaphragm becomes 47 mm. The shape of the electrode assembly becomes an elliptical cylinder.

将所得的电极组件插入49mm高(底部厚度:0.5mm)、34mm宽、以及5.2mm厚的铝的棱柱形电池壳中。在将1.5mm厚的绝缘体安装在电极组件顶部后,把2.5g与实施例1相同的电解液注入到电池壳中。从电池壳的内底面到绝缘体下表面的距离A为46.0mm。应该注意到电极组件的下半部通过绝缘薄片与电池壳绝缘,但由于绝缘薄片非常薄,其厚度可忽略不计。The resulting electrode assembly was inserted into an aluminum prismatic battery case of 49 mm high (bottom thickness: 0.5 mm), 34 mm wide, and 5.2 mm thick. After installing a 1.5 mm thick insulator on top of the electrode assembly, 2.5 g of the same electrolyte as in Example 1 was injected into the battery case. The distance A from the inner bottom surface of the battery case to the lower surface of the insulator was 46.0 mm. It should be noted that the lower half of the electrode assembly is insulated from the battery case by an insulating sheet, but since the insulating sheet is very thin, its thickness is negligible.

其后,将1.0mm厚的矩形密封板安装在电池壳的顶部开口,并且用激光将电池壳的开口边和密封板的外围焊接在一起。制成的棱柱形锂二次电池的高度为50mm,宽度为34mm,厚度为5.2mm,设计容量为950mAh。B/A的比值(负极宽度B(43.7mm)与距离A(46.0mm)的比值)为0.95。Thereafter, a 1.0 mm thick rectangular sealing plate was mounted on the top opening of the battery case, and the opening side of the battery case and the periphery of the sealing plate were welded together by laser. The manufactured prismatic lithium secondary battery has a height of 50 mm, a width of 34 mm, a thickness of 5.2 mm, and a design capacity of 950 mAh. The ratio of B/A (the ratio of the negative electrode width B (43.7 mm) to the distance A (46.0 mm)) was 0.95.

(电池32~35)(Battery 32~35)

用与电池31相同的制造方法制得棱柱形锂二次电池32~35,所不同的只是负极宽度B分别变为44.6mm、45mm、45.7mm、以及46.5mm,正极宽度分别变为43.6mm、44mm、44.7mm、以及45.5mm,设计容量分别变为970mAh、979mAh、994mAh、以及1012mAh。各种电池中B/A的比值为0.970(电池32)、0.978(电池33)、0.993(电池34)、以及1.011(电池35)。The prismatic lithium secondary batteries 32-35 were manufactured by the same manufacturing method as the battery 31, except that the width B of the negative electrode was changed to 44.6mm, 45mm, 45.7mm, and 46.5mm respectively, and the width of the positive electrode was changed to 43.6mm, 44mm, 44.7mm, and 45.5mm, the design capacity becomes 970mAh, 979mAh, 994mAh, and 1012mAh respectively. The ratios of B/A in the various batteries were 0.970 (Battery 32), 0.978 (Battery 33), 0.993 (Battery 34), and 1.011 (Battery 35).

(电池36和37)(batteries 36 and 37)

分别用与电池33和34相同的制造方法制得棱柱形锂二次电池36和37,所不同的只是多孔耐热层是形成在正极活性材料层的表面上而不在负极活性材料层的表面上。The prismatic lithium secondary batteries 36 and 37 were made in the same manufacturing method as the batteries 33 and 34 respectively, except that the porous heat-resistant layer was formed on the surface of the positive electrode active material layer and not on the surface of the negative electrode active material layer .

(电池38)(Battery 38)

用与电池33相同的制造方法制得棱柱形锂二次电池,所不同的只是多孔耐热层的厚度变为15μm并且没有用隔膜制造电极组件。A prismatic lithium secondary battery was fabricated by the same fabrication method as battery 33, except that the thickness of the porous heat-resistant layer was changed to 15 μm and the electrode assembly was not fabricated using a separator.

(电池39~42)(Battery 39~42)

用与电池33相同的制造方法制得棱柱形锂二次电池39~42,所不同的只是多孔耐热层中的氧化铝分别变为具有相同中值粒径的氧化镁、二氧化硅、二氧化钛、以及氧化锆。(电池43~50)The prismatic lithium secondary batteries 39-42 were produced by the same manufacturing method as the battery 33, except that the aluminum oxide in the porous heat-resistant layer was changed to magnesium oxide, silicon dioxide, and titanium dioxide with the same median particle size, respectively. , and zirconia. (Battery 43~50)

用与电池33相同的制造方法制得棱柱形锂二次电池43~50,所不同的只是分别使用了与实施例1中电池13~20相同的多孔耐热层。Prismatic lithium secondary batteries 43-50 were manufactured by the same manufacturing method as battery 33, except that the same porous heat-resistant layers as batteries 13-20 in Example 1 were used respectively.

(电池51~55)(Battery 51~55)

用与电池33相同的制造方法制得棱柱形锂二次电池51~55,所不同的只是用以干燥涂覆的原料浆料以形成多孔耐热层的热空气的流量分别变为0.5m/min、1m/min、2m/min、5m/min、以及8m/min。各种电池的多孔耐热层的孔隙度为30%(电池51)、42%(电池52)、60%(电池53)、78%(电池54)、或89%(电池55)。The prismatic lithium secondary batteries 51 to 55 were produced in the same manufacturing method as the battery 33, except that the flow rate of the hot air used to dry the coated raw material slurry to form the porous heat-resistant layer was changed to 0.5 m/ min, 1m/min, 2m/min, 5m/min, and 8m/min. The porosity of the porous heat-resistant layer of each battery was 30% (Battery 51), 42% (Battery 52), 60% (Battery 53), 78% (Battery 54), or 89% (Battery 55).

(电池56~60)(Battery 56~60)

分别用与电池31~35相同的制造方法制得棱柱形锂二次电池56~60,所不同的只是隔膜的厚度变为15μm并且没有设置多孔耐热层。Prismatic lithium secondary batteries 56 to 60 were produced in the same manufacturing method as batteries 31 to 35, respectively, except that the thickness of the separator was changed to 15 μm and the porous heat-resistant layer was not provided.

各种电池进行两次预充电和放电,然后在45℃环境下保藏7天。之后,用如下方式对它们进行评估。表4、表5、以及表6分别概括了多孔耐热层的特征、电池设计、以及评估结果。Each battery was precharged and discharged twice, and then stored at 45°C for 7 days. Afterwards, they are evaluated as follows. Table 4, Table 5, and Table 6 summarize the characteristics of the porous heat-resistant layer, battery design, and evaluation results, respectively.

(内部短路检查)(internal short circuit check)

用与实施例1相同的方法检查这些电池的内部短路,所不同的只是它们按如下条件充电。结果见表6。These batteries were checked for internal short circuit in the same manner as in Example 1, except that they were charged under the following conditions. The results are shown in Table 6.

恒流充电:充电电流665mA/充电终止电压4.2V;Constant current charging: charging current 665mA/charging termination voltage 4.2V;

恒压充电:充电电压4.2V/充电终止电流100mA。Constant voltage charging: charging voltage 4.2V/charging termination current 100mA.

(下落试验)(drop test)

用与实施例1相同的方法评价这些电池的耐下落冲击,所不同的只是它们按如下条件进行充电和放电。结果见表6。The drop impact resistance of these batteries was evaluated in the same manner as in Example 1, except that they were charged and discharged under the following conditions. The results are shown in Table 6.

恒流充电:充电电流665mA/充电终止电压4.2V;Constant current charging: charging current 665mA/charging termination voltage 4.2V;

恒压充电:充电电压4.2V/充电终止电流100mA;Constant voltage charging: charging voltage 4.2V/charging termination current 100mA;

恒流放电:放电电流950mA/放电终止电压3V。Constant current discharge: discharge current 950mA/discharge termination voltage 3V.

(下落试验后内部短路检查)下落试验后,用与下落试验前相同的方法检查这些电池的内部短路。落下后的短路发生率结果见表6。(Inspection of internal short circuit after drop test) After the drop test, these batteries were inspected for internal short circuit in the same manner as before the drop test. Table 6 shows the results of the occurrence rate of short circuits after the drop.

(高输出特性)(high output characteristics)

在20℃环境下,各种电池按如下条件进行放电和充电,并且获得它们的放电容量。In an environment of 20°C, various batteries were discharged and charged under the following conditions, and their discharge capacities were obtained.

恒流充电:充电电流665mA/充电终止电压4.2V;Constant current charging: charging current 665mA/charging termination voltage 4.2V;

恒压充电:充电电压4.2V/充电终止电流100mA;Constant voltage charging: charging voltage 4.2V/charging termination current 100mA;

恒流放电:放电电流190mA/放电终止电压3V;Constant current discharge: discharge current 190mA/discharge termination voltage 3V;

恒流充电:充电电流665mA/充电终止电压4.2V;Constant current charging: charging current 665mA/charging termination voltage 4.2V;

恒压充电:充电电压4.2V/充电终止电流100mA;Constant voltage charging: charging voltage 4.2V/charging termination current 100mA;

恒流放电:放电电流1900mA/放电终止电压3V。Constant current discharge: discharge current 1900mA/discharge termination voltage 3V.

于是可获得电池在1900mA下的放电容量相对其在190mA下的放电容量的百分比。高输出特性结果见表6。The percentage of the battery's discharge capacity at 1900 mA relative to its discharge capacity at 190 mA can then be obtained. See Table 6 for the high output characteristic results.

(钉穿刺试验)(nail puncture test)

各种电池在950mA的充电电流下充电至4.35V的截止电压。用与实施例1相同的方法将钉子敲入电池中,并对90秒后的电池温度进行评估。结果见表6。Various cells were charged to a cut-off voltage of 4.35V at a charge current of 950mA. A nail was driven into the battery by the same method as in Example 1, and the temperature of the battery after 90 seconds was evaluated. The results are shown in Table 6.

表4Table 4

  电池 多孔耐热层(μm)      多孔耐热层的位置         隔膜(μm) 填料 粘合剂含量(wt%)     孔隙度(%)   31 5 负极 10 氧化铝 3 50 32 5 负极 10 氧化铝 3 50 33 5 负极 10 氧化铝 3 50 34 5 负极 10 氧化铝 3 50 35 5 负极 10 氧化铝 3 50 36 5 正极 10 氧化铝 3 50 37 5 正极 10 氧化铝 3 50 38 15 负极 氧化铝 3 50 39 5 负极 10 氧化镁 3 50 40 5 负极 10 二氧化硅 3 50 41 5 负极 10 二氧化钛 3 50 42 5 负极 10 氧化锆 3 50 43 5 隔膜 10 芳族聚酰胺 48 44 5 隔膜 10 聚酰胺酰亚胺 47 45 15 独立的薄片 芳族聚酰胺 51 46 15 独立的薄片 聚酰胺酰亚胺 52 47 5 负极 10 氧化铝 0.5 61 48 5 负极 10 氧化铝 1 57 49 5 负极 10 氧化铝 10 42 50 5 负极 10 氧化铝 20 35 51 5 负极 10 氧化铝 3 30 52 5 负极 10 氧化铝 3 42 53 5 负极 10 氧化铝 3 60 54 5 负极 10 氧化铝 3 78 55 5 负极 10 氧化铝 3 89 56 15 57 15 58 15 59 15 60 15 Battery Porous heat-resistant layer (μm) The location of the porous heat-resistant layer Diaphragm (μm) filler Binder content (wt%) Porosity(%) 31 5 negative electrode 10 Aluminum oxide 3 50 32 5 negative electrode 10 Aluminum oxide 3 50 33 5 negative electrode 10 Aluminum oxide 3 50 34 5 negative electrode 10 Aluminum oxide 3 50 35 5 negative electrode 10 Aluminum oxide 3 50 36 5 positive electrode 10 Aluminum oxide 3 50 37 5 positive electrode 10 Aluminum oxide 3 50 38 15 negative electrode none Aluminum oxide 3 50 39 5 negative electrode 10 magnesium oxide 3 50 40 5 negative electrode 10 silica 3 50 41 5 negative electrode 10 Titanium dioxide 3 50 42 5 negative electrode 10 Zirconia 3 50 43 5 diaphragm 10 Aramid 48 44 5 diaphragm 10 polyamideimide 47 45 15 individual slices none Aramid 51 46 15 individual slices none polyamideimide 52 47 5 negative electrode 10 Aluminum oxide 0.5 61 48 5 negative electrode 10 Aluminum oxide 1 57 49 5 negative electrode 10 Aluminum oxide 10 42 50 5 negative electrode 10 Aluminum oxide 20 35 51 5 negative electrode 10 Aluminum oxide 3 30 52 5 negative electrode 10 Aluminum oxide 3 42 53 5 negative electrode 10 Aluminum oxide 3 60 54 5 negative electrode 10 Aluminum oxide 3 78 55 5 negative electrode 10 Aluminum oxide 3 89 56 none 15 57 none 15 58 none 15 59 none 15 60 none 15

表5table 5

  电池 负极宽度B(mm)      正极宽度(mm)   设计容量(mAh)    B/A 31 43.7 42.7 950 0.950 32 44.6 43.6 970 0.970 33 45 44 979 0.978 34 45.7 44.7 994 0.993 35 46.5 45.5 1012 1.011 36 45 44 979 0.978 37 45.7 44.7 994 0.993 38 45 44 979 0.978 39 45 44 979 0.978 40 45 44 979 0.978 41 45 44 979 0.978 42 45 44 979 0.978 43 45 44 979 0.978 44 45 44 979 0.978 45 45 44 979 0.978 46 45 44 979 0.978 47 45 44 979 0.978 48 45 44 979 0.978 49 45 44 979 0.978 50 45 44 979 0.978 51 45 44 979 0.978 52 45 44 979 0.978 53 45 44 979 0.978 54 45 44 979 0.978 55 45 44 979 0.978 56 43.7 42.7 950 0.950 57 44.6 43.6 970 0.970 58 45 44 979 0.978 59 45.7 44.7 994 0.993 60 46.5 45.5 1012 1.011 Battery Negative electrode width B(mm) Positive electrode width (mm) Design capacity (mAh) B/A 31 43.7 42.7 950 0.950 32 44.6 43.6 970 0.970 33 45 44 979 0.978 34 45.7 44.7 994 0.993 35 46.5 45.5 1012 1.011 36 45 44 979 0.978 37 45.7 44.7 994 0.993 38 45 44 979 0.978 39 45 44 979 0.978 40 45 44 979 0.978 41 45 44 979 0.978 42 45 44 979 0.978 43 45 44 979 0.978 44 45 44 979 0.978 45 45 44 979 0.978 46 45 44 979 0.978 47 45 44 979 0.978 48 45 44 979 0.978 49 45 44 979 0.978 50 45 44 979 0.978 51 45 44 979 0.978 52 45 44 979 0.978 53 45 44 979 0.978 54 45 44 979 0.978 55 45 44 979 0.978 56 43.7 42.7 950 0.950 57 44.6 43.6 970 0.970 58 45 44 979 0.978 59 45.7 44.7 994 0.993 60 46.5 45.5 1012 1.011

表6Table 6

  电池 短路发生率(%)       耐下落冲击(%)       落下后短路发生率(%)         高输出特性(%)       钉穿刺后电池温度(℃)             31 0 93.3 1 90.4 83 32 0 98.0 0 91.2 86 33 0 99.9 0 90.1 80 34 0 99.7 0 89.4 82 35 20 98.8 0 88.9 83 36 4 99.8 3 90.2 86 37 11 99.7 12 91.3 86 38 2 99.8 13 87.8 93 39 0 99.7 0 89.1 86 40 0 99.9 0 90.1 86 41 0 99.8 0 88.9 82 42 0 99.8 0 90.4 84 43 0 99.6 10 88.8 82 44 0 99.7 11 90.1 84 45 0 99.8 12 91.2 85 46 0 99.9 11 90.7 82 47 0 99.9 8 90.4 87 48 0 99.8 0 91.4 82 49 0 99.7 0 85.3 81 50 0 99.9 0 80.3 78 51 0 96.0 0 87.7 83 52 0 99.8 0 88.2 88 53 0 100.0 0 89.4 81 54 0 99.7 0 90.0 85 55 2 99.8 14 92.1 94 56 0 99.7 0 88.4 126 57 15 99.9 0 88.9 123 58 20 99.8 0 90.2 131 59 28 99.8 0 89.1 124 60 48 99.8 5 90.1 130 Battery Short circuit occurrence rate (%) Drop impact resistance (%) Occurrence rate of short circuit after drop (%) High output characteristics (%) Battery temperature after nail piercing (°C) 31 0 93.3 1 90.4 83 32 0 98.0 0 91.2 86 33 0 99.9 0 90.1 80 34 0 99.7 0 89.4 82 35 20 98.8 0 88.9 83 36 4 99.8 3 90.2 86 37 11 99.7 12 91.3 86 38 2 99.8 13 87.8 93 39 0 99.7 0 89.1 86 40 0 99.9 0 90.1 86 41 0 99.8 0 88.9 82 42 0 99.8 0 90.4 84 43 0 99.6 10 88.8 82 44 0 99.7 11 90.1 84 45 0 99.8 12 91.2 85 46 0 99.9 11 90.7 82 47 0 99.9 8 90.4 87 48 0 99.8 0 91.4 82 49 0 99.7 0 85.3 81 50 0 99.9 0 80.3 78 51 0 96.0 0 87.7 83 52 0 99.8 0 88.2 88 53 0 100.0 0 89.4 81 54 0 99.7 0 90.0 85 55 2 99.8 14 92.1 94 56 0 99.7 0 88.4 126 57 15 99.9 0 88.9 123 58 20 99.8 0 90.2 131 59 28 99.8 0 89.1 124 60 48 99.8 5 90.1 130

在负极宽度B相对从绝缘体(限制部位)下表面到电池壳内底面的距离A过小的电池31中,容量密度较小,此外耐下落冲击较低。下落试验后,将电池31拆开进行观察,结果发现缠绕电极组件的电极发生了移动。In the battery 31 in which the width B of the negative electrode is too small relative to the distance A from the lower surface of the insulator (restriction portion) to the inner bottom surface of the battery case, the capacity density is small, and the drop impact resistance is low. After the drop test, the battery 31 was disassembled for observation, and it was found that the electrodes of the wound electrode assembly moved.

电池31因多孔耐热层的作用而没有内部短路,但有效面积(正极和负极彼此相对的面积)的减小导致其容量损失。因配有多孔耐热层,其电极组件是抗形变的,故其不能稳固地固定在电池壳的内侧。缠绕电极组件的电极在重复下落时可能因此而发生移动。The battery 31 has no internal short circuit due to the effect of the porous heat-resistant layer, but the reduction in the effective area (the area where the positive and negative electrodes face each other) results in loss of its capacity. Due to the porous heat-resistant layer, the electrode assembly is resistant to deformation, so it cannot be firmly fixed on the inside of the battery case. The electrodes of the wound electrode assembly may thus move when dropped repeatedly.

另一方面,在负极宽度B相对从绝缘体下表面到电池壳内底面的距离A过大的电池35中,耐短路性较低。将确定处于内部短路态的电池35的样品拆开进行观察。结果发现负极表面上的多孔耐热层在电极组件的上半部有损坏。还发现隔膜发生开裂。On the other hand, in the battery 35 in which the width B of the negative electrode is too large relative to the distance A from the lower surface of the insulator to the inner bottom surface of the battery case, the short-circuit resistance is low. A sample of the battery 35 determined to be in the internal short-circuit state was disassembled for observation. It was found that the porous heat-resistant layer on the surface of the negative electrode was damaged in the upper half of the electrode assembly. It was also found that the septum cracked.

在B/A的比值为0.975~0.995的电池33~34中,耐短路性较高,此外耐下落冲击得到了提高。本发明的电池除有隔膜外还配有多孔耐热层。因此,即使当负极比正极宽、电极组件上半部有轻微变形时,由多孔耐热层和隔膜组成的双层结构使变形部分绝缘。此外,由于B/A的比值较高,电极组件稳固地夹在绝缘体下半部的表面和电池壳的内底面之间。电池的耐下落冲击可能因此而得到提高。Batteries 33 to 34 having a B/A ratio of 0.975 to 0.995 had high short-circuit resistance and improved drop impact resistance. The battery of the invention is equipped with a porous heat-resistant layer in addition to the diaphragm. Therefore, even when the negative electrode is wider than the positive electrode and the upper half of the electrode assembly is slightly deformed, the double-layer structure consisting of the porous heat-resistant layer and the separator insulates the deformed part. In addition, due to the high ratio of B/A, the electrode assembly is firmly sandwiched between the surface of the lower half of the insulator and the inner bottom surface of the battery case. The battery's drop impact resistance may thus be improved.

然而,在B/A的比值为0.965~0.975的电池32中,耐下落冲击略低于具有相同比值范围的B/A的圆柱形电池2(实施例1)的耐下落冲击。就圆柱形电池而言,其槽部(限制部位)的横截面是近似V形的或U形的。因此,电极组件的顶部被槽部的斜坡压住。另一方面,就棱柱形锂二次电池而言,绝缘体(限制部位)下半部的表面是平的,因此没有如槽部那样的斜坡。各种电池在更为有效的B/A比值范围内可能因此而存在上述差异。However, in the battery 32 having a B/A ratio of 0.965 to 0.975, the drop impact resistance was slightly lower than that of the cylindrical battery 2 (Example 1) having the same ratio range of B/A. In the case of a cylindrical battery, the cross section of its groove portion (restricted portion) is approximately V-shaped or U-shaped. Therefore, the top of the electrode assembly is pressed by the slope of the groove portion. On the other hand, in the case of a prismatic lithium secondary battery, the surface of the lower half of the insulator (restriction portion) is flat, so there is no slope like the groove portion. Various batteries may therefore have the above-mentioned differences in the range of more effective B/A ratios.

在没有多孔耐热层的电池56~60中,耐下落冲击不受限制部位位置的影响均是优良的。人们相信,因没有多孔耐热层的电极组件变形到一合适程度,故其稳固地固定在电池壳内。即使在这些电池下落时,导致容量损失的缠绕电极组件的电极移动可能因此而受到抑制。然而,这些电池56~60在钉穿刺试验中明显过热。此外,在限制部位位置分别与电池32~34相同的电池57~59中,耐短路性较低。人们相信,这些电池57~59的负极有轻微变形。然而,由于这些电池没有多孔耐热层,当隔膜因负极形变发生开裂时,内部短路不能防止。In the batteries 56 to 60 having no porous heat-resistant layer, the drop impact resistance was excellent regardless of the position of the restricting portion. It is believed that since the electrode assembly without the porous heat-resistant layer is deformed to an appropriate degree, it is held firmly within the battery case. Even when these batteries are dropped, electrode movement of the wound electrode assembly, which causes capacity loss, may thus be suppressed. However, these batteries 56-60 significantly overheated in the nail puncture test. In addition, in the batteries 57 to 59 having the same positions of the restriction parts as the batteries 32 to 34, the short-circuit resistance is low. It is believed that the negative electrodes of these cells 57-59 were slightly deformed. However, since these batteries do not have a porous heat-resistant layer, internal short circuits cannot be prevented when the separator cracks due to deformation of the negative electrode.

在电池36和37中,多孔耐热层形成在正极活性材料层的表面上。在这两种电池中,具有更宽负极的电池37显示出相对较低的耐短路性。这可能是因为多孔耐热层形成在比负极活性材料层更窄的正极活性材料层的表面上,于是负极表面在电极组件的上半部与正极的上半部边缘相接触。In batteries 36 and 37, a porous heat-resistant layer was formed on the surface of the positive electrode active material layer. Among the two batteries, the battery 37 with a wider negative electrode showed relatively lower short-circuit resistance. This may be because the porous heat-resistant layer is formed on the surface of the positive electrode active material layer which is narrower than the negative electrode active material layer, so that the negative electrode surface is in contact with the upper half edge of the positive electrode at the upper half of the electrode assembly.

在没有隔膜的电池38中,下落后的耐短路性略低。多孔耐热层结构上比隔膜更易碎。于是,多孔耐热层受下落冲击作用而局部损坏,从而发生短路。In the battery 38 without a separator, the short-circuit resistance after dropping was slightly lower. The porous heat-resistant layer is structurally more fragile than the diaphragm. Then, the porous heat-resistant layer is partially damaged by the impact of the drop, so that a short circuit occurs.

在隔膜表面有由耐热树脂制成的多孔耐热层的电池43和44中,下落后的耐短路性略低。耐热树脂制成的多孔耐热层的机械强度低于包含绝缘填料和粘合剂的多孔耐热层的机械强度。于是,短路通过下落冲击作用发生。In batteries 43 and 44 having a porous heat-resistant layer made of a heat-resistant resin on the surface of the separator, the short-circuit resistance after dropping was slightly lower. The mechanical strength of a porous heat-resistant layer made of a heat-resistant resin is lower than that of a porous heat-resistant layer comprising an insulating filler and a binder. Then, a short circuit occurs by the drop impact action.

在具有独立的多孔耐热层薄片并且没有隔膜的电池45和46中,它们落下后的耐短路性低于电池43和电池44落下后的耐短路性。这源于该事实,即由耐热树脂制成的多孔耐热层强度差并且多孔耐热层的强度没有因隔膜的缺少而得到提高。In Batteries 45 and 46 having separate porous heat-resistant layer sheets and no separator, their short-circuit resistance after being dropped was lower than that of Batteries 43 and 44 after being dropped. This stems from the fact that the porous heat-resistant layer made of heat-resistant resin is poor in strength and the strength of the porous heat-resistant layer is not improved by the absence of the separator.

在多孔耐热层中含0.5wt%粘合剂的电池47中,落下后的耐短路性略低。这可能是因为低含量的粘合剂减弱了填料粒子的粘附力,从而导致多孔耐热层的机械强度较差。In Battery 47 containing 0.5% by weight of the binder in the porous heat-resistant layer, the short-circuit resistance after dropping was slightly lower. This may be because the low content of binder weakens the adhesion of filler particles, resulting in poor mechanical strength of the porous heat-resistant layer.

另一方面,在含有20wt%粘合剂的电池50中,高输出特性略低。这可能是因为过量的粘合剂降低了多孔耐热层的孔隙度,此外,过量的粘合剂随电解液溶胀,从而使多孔耐热层的微孔闭合并降低了离子导电率。另一方面,在粘合剂含量为1wt%~10wt%的电池48~49中,耐短路性和高输出特性都是优良的。On the other hand, in the battery 50 containing 20 wt% of the binder, the high output characteristics were slightly lower. This may be because the excess binder reduces the porosity of the porous heat-resistant layer, and in addition, the excess binder swells with the electrolyte, which closes the micropores of the porous heat-resistant layer and reduces the ionic conductivity. On the other hand, in Batteries 48 to 49 having a binder content of 1 wt % to 10 wt %, both the short circuit resistance and high output characteristics were excellent.

在因控制干燥条件获得的带有30%孔隙度的多孔耐热层的电池51中,耐下落冲击略低。其原因可能如下。由于孔隙度低,多孔耐热层没有充分地浸润电解液,于是电极组件的溶胀较小。因此,不能防止电极组件在下落时移动。在具有89%孔隙度的多孔耐热层的电池55中,落下后的耐短路性是略低的。这可能是因为多孔耐热层的机械强度较差。In the battery 51 with a porous heat-resistant layer having a porosity of 30% obtained by controlling the drying conditions, the drop impact resistance was slightly lower. The reason for this may be as follows. Due to the low porosity, the porous heat-resistant layer does not fully infiltrate the electrolyte, so the swelling of the electrode assembly is small. Therefore, the electrode assembly cannot be prevented from moving when dropped. In the battery 55 having a porous heat-resistant layer with a porosity of 89%, the short-circuit resistance after being dropped was slightly lower. This may be due to the poor mechanical strength of the porous heat-resistant layer.

另一方面,在带有孔隙度为40%~80%的多孔耐热层的电池52~54中,耐下落冲击和落下后的耐短路性均是优良的。其原因可能如下。由于最佳化的孔隙度,多孔耐热层的机械强度得到保持。此外,多孔耐热层随电解液溶胀到一合适程度。于是防止了电极组件的移动。On the other hand, in the batteries 52 to 54 with porous heat-resistant layers having a porosity of 40% to 80%, both drop impact resistance and short circuit resistance after drop were excellent. The reason for this may be as follows. Due to the optimized porosity, the mechanical strength of the porous heat-resistant layer is maintained. In addition, the porous heat-resistant layer swells to a suitable degree with the electrolyte. Movement of the electrode assembly is thus prevented.

工业实用性Industrial Applicability

由于本发明的锂二次电池具有出色的抗短路性和耐热性以及高安全性并且不会因冲击如下落而有容量损失,故可用作任何便携式装置的电源,如个人数字助理和便携式电子设备。本发明的锂二次电池可用作如家庭用的小型蓄电装置、两轮机动车、电动车、以及两用电动车的电源,并且本发明的用途无特别限定。Since the lithium secondary battery of the present invention has excellent short-circuit resistance and heat resistance and high safety and does not have capacity loss due to impact such as dropping, it can be used as a power source of any portable device such as a personal digital assistant and a portable battery. Electronic equipment. The lithium secondary battery of the present invention can be used, for example, as a power source for small electric storage devices for household use, two-wheeled vehicles, electric vehicles, and dual-purpose electric vehicles, and the use of the present invention is not particularly limited.

Claims (13)

1.一种锂二次电池,包括:具有底部、侧壁和顶部开口的电池壳;电极组件;非水电解液;以及覆盖用以容纳所述电极组件和所述电解液的所述电池壳的顶部开口的密封板,1. A lithium secondary battery, comprising: a battery case having a bottom, a side wall and an opening at the top; an electrode assembly; a non-aqueous electrolyte; and covering the battery case for containing the electrode assembly and the electrolyte The top opening of the sealing plate, 其特征在于,所述电极组件包括与插入在正极和负极之间的多孔耐热层缠绕在一起的条形正极和条形负极,所述正极包括正极芯部件和涂在正极芯部件两面上的正极活性材料层,所述负极包括负极芯部件和涂在负极芯部件两面上的负极活性材料层,It is characterized in that the electrode assembly includes a strip-shaped positive electrode and a strip-shaped negative electrode intertwined with a porous heat-resistant layer inserted between the positive electrode and the negative electrode, and the positive electrode includes a positive electrode core part and a coating coated on both sides of the positive electrode core part. a positive electrode active material layer, the negative electrode comprising a negative electrode core part and a negative electrode active material layer coated on both sides of the negative electrode core part, 所述电池具有限制所述电极组件垂直移动的限制部位,从所述限制部位到所述电池壳内底面的距离A与所述负极的宽度B之间满足关系式:0.965≤B/A≤0.995,The battery has a restricting part that restricts the vertical movement of the electrode assembly, and the distance A from the restricting part to the inner bottom surface of the battery case and the width B of the negative electrode satisfy the relationship: 0.965≤B/A≤0.995 , 所述多孔耐热层含有绝缘填料和粘合剂,以及The porous heat-resistant layer contains insulating fillers and binders, and 所述多孔耐热层具有40%~80%的孔隙度和0.5~20μm的厚度。The porous heat-resistant layer has a porosity of 40% to 80% and a thickness of 0.5 to 20 μm. 2.如权利要求1所述的锂二次电池,其特征在于,进一步包括含有微孔膜的隔膜,所述隔膜插入在所述多孔耐热层和所述正极之间或在所述多孔耐热层和所述负极之间。2. The lithium secondary battery according to claim 1, further comprising a separator comprising a microporous membrane, the separator being inserted between the porous heat-resistant layer and the positive electrode or between the porous heat-resistant layer and the negative electrode. 3.如权利要求1所述的锂二次电池,其特征在于,所述多孔耐热层形成在所述正极活性材料层和所述负极活性材料层中至少一个的表面上。3. The lithium secondary battery according to claim 1, wherein the porous heat-resistant layer is formed on a surface of at least one of the positive electrode active material layer and the negative electrode active material layer. 4.如权利要求1所述的锂二次电池,其特征在于,所述绝缘填料包含无机氧化物。4. The lithium secondary battery according to claim 1, wherein the insulating filler comprises an inorganic oxide. 5.如权利要求4所述的锂二次电池,其特征在于,所述无机氧化物包括选自于氧化铝、二氧化硅、氧化镁、二氧化钛、以及氧化锆中的至少一种。5. The lithium secondary battery according to claim 4, wherein the inorganic oxide comprises at least one selected from alumina, silica, magnesia, titania, and zirconia. 6.如权利要求1所述的锂二次电池,其特征在于,以100重量份的所述绝缘填料为基准,所述的粘合剂的量为1~10重量份。6 . The lithium secondary battery according to claim 1 , wherein, based on 100 parts by weight of the insulating filler, the amount of the binder is 1-10 parts by weight. 7.如权利要求1所述的锂二次电池,其特征在于,所述电极组件为圆柱形,所述电池壳为圆筒形,所述限制部位是位于电池壳侧壁上部的使内径减小的所述电池壳的槽部。7. The lithium secondary battery according to claim 1, wherein the electrode assembly is cylindrical, the battery case is cylindrical, and the restricting part is located on the upper part of the side wall of the battery case to reduce the inner diameter. The groove portion of the battery case is small. 8.如权利要求1所述的锂二次电池,其特征在于,进一步包含位于所述电极组件和所述密封板之间的绝缘体,其中所述电极组件为截面为椭圆的圆柱形,所述电池壳为棱柱形,所述限制部位是绝缘体的下部表面。8. The lithium secondary battery as claimed in claim 1, further comprising an insulator between the electrode assembly and the sealing plate, wherein the electrode assembly is a cylinder with an elliptical cross-section, and the The battery case has a prism shape, and the limiting part is the lower surface of the insulator. 9.如权利要求7所述的锂二次电池,其特征在于,从所述限制部位到所述电池壳底部的内表面的距离A与所述负极的宽度B之间满足关系式:0.970≤B/A≤0.990。9. The lithium secondary battery according to claim 7, characterized in that, the distance A from the restricting part to the inner surface of the bottom of the battery case and the width B of the negative electrode satisfy the relationship: 0.970≤ B/A≤0.990. 10.如权利要求8所述的锂二次电池,其特征在于,从所述限制部位到所述电池壳底部的内表面的距离A与所述负极的宽度B之间满足关系式:0.975≤B/A≤0.990。10. The lithium secondary battery according to claim 8, characterized in that, the distance A from the restricting part to the inner surface of the bottom of the battery case and the width B of the negative electrode satisfy the relationship: 0.975≤ B/A≤0.990. 11.如权利要求8所述的锂二次电池,其特征在于,从所述限制部位到所述电池壳底部的内表面的距离A与所述负极的宽度B之间满足关系式:0.975≤B/A≤0.995。11. The lithium secondary battery according to claim 8, characterized in that, the distance A from the restricting part to the inner surface of the bottom of the battery case and the width B of the negative electrode satisfy the relationship: 0.975≤ B/A≤0.995. 12.如权利要求1所述的锂二次电池,其特征在于,以100重量份的所述绝缘填料为基准,所述粘合剂的量为2~8重量份。12 . The lithium secondary battery according to claim 1 , wherein, based on 100 parts by weight of the insulating filler, the amount of the binder is 2-8 parts by weight. 13.如权利要求1所述的锂二次电池,其特征在于,所述多孔耐热层具有40%~65%的孔隙度。13. The lithium secondary battery according to claim 1, wherein the porous heat-resistant layer has a porosity of 40%-65%.
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