JP3802282B2 - Cylindrical secondary battery - Google Patents

Description

【００５３】
次に、負荷率試験を行なった。先ず充電率０.１２５Ｃにて８時間の充電を行なった後、放電率０.２５Ｃ〜１.２５Ｃの範囲で０.１２５Ｃの刻み幅で放電率を変化させ、各放電率で放電終止電圧２.７Ｖまで放電を行なった。そして、ＰＴＣ素子が作動して通電不可能となる負荷率にて、試験終了とした。
【００５４】
試験結果を表１に示す。表１から明らかな様に、電池Ｘでは０.２５Ｃまでの負荷率で放電が可能であったのに対し、電池Ａ１、Ａ２、Ａ３では、１Ｃまでの負荷率で放電が可能となった。
又、電池Ａ４では０.５Ｃ、電池Ａ５では０.７５Ｃ、電池Ａ６では０.８７５Ｃまでの負荷率で放電が可能となり、ＰＴＣ素子の面積の増大に伴って、放電可能な負荷率の幅が拡がることが明らかとなった。
【００５５】
上述の如く、本発明に係る円筒型リチウムイオン二次電池においては、ＰＴＣ素子の大きさにガス排出弁機構による制限がないために、従来よりも大きな面積のＰＴＣ素子が設置可能であり、これによって、従来より大きな電流による放電が可能となる。
尚、本発明電池は、放電容量が２Ａｈ以上の大型電池で特に大きな効果が得られる。
【図面の簡単な説明】
【図１】 第１比較例の円筒型リチウムイオン二次電池の正面図である。
【図２】 該円筒型リチウムイオン二次電池の正極側の電極端子機構を示す拡大断面図である。
【図３】 該円筒型リチウムイオン二次電池の負極側の電極端子機構を示す拡大断面図である。
【図４】 前記正極側の電極端子機構の分解斜視図である。
【図５】 第２比較例の円筒型リチウムイオン二次電池の正面図である。
【図６】 ガス排出弁及びガス排出口からなるガス排出弁機構の拡大断面図である。
【図７】 本発明例の円筒型リチウムイオン二次電池において、正極側の電極端子機構を示す拡大断面図である。
【図８】 該電極端子機構の分解斜視図である。
【図９】 第３比較例における正極側の電極端子機構を示す拡大断面図である。
【図１０】 従来の円筒型リチウムイオン二次電池における正極側の電極端子機構を示す拡大断面図である。
【符号の説明】
(１) 電池缶
(11) 筒体
(12) 蓋体
(14) Ｖ字状溝
(16) ＰＴＣ素子
(２) 巻き取り電極体
(３) 集電タブ
(４) 電極端子機構
(41) 第１端子部材
(５) 第２端子部材
(56) ねじ部材
(６) 絶縁部材
(63) 熱収縮性絶縁部材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cylindrical secondary battery in which a winding electrode body is housed inside a cylindrical battery can and the electric power generated by the winding electrode body can be taken out from an electrode terminal mechanism attached to the battery can. It is about.
[0002]
[Prior art]
In recent years, lithium ion secondary batteries have attracted attention as a power source for portable electronic devices and electric vehicles because of their high energy density.
For example, as shown in FIG. 10, a cylindrical lithium secondary battery having a relatively large capacity used for an electric vehicle is a cylindrical battery in which a lid (12) is welded and fixed to an opening of a cylindrical body (11). The take-up electrode body (2) is accommodated inside the can (1). An electrode terminal mechanism (9) is attached to the lid (12), and the winding electrode body (2) and the electrode terminal mechanism (9) are connected to each other by a plurality of current collecting tabs (3). The electric power generated by the winding electrode body (2) can be taken out from the electrode terminal mechanism (9). In addition, a spring return type gas discharge valve (13) is attached to the lid (12) as a gas discharge valve mechanism when the pressure increases.
An electrode terminal mechanism having the same configuration is also attached to a lid (not shown) fixed to the other opening of the cylindrical body (11), and both electrode terminal mechanisms form a positive and negative pair.
[0003]
The take-up electrode body (2) includes a separator (22) impregnated with a non-aqueous electrolyte between a positive electrode (23) containing a lithium composite oxide and a negative electrode (21) containing a carbon material. Is wound in a spiral shape. A plurality of current collecting tabs (3) are drawn out from the positive electrode (23) and the negative electrode (21) of the winding electrode body (2), respectively, and the tips (31) of the plurality of current collecting tabs (3) having the same polarity are drawn out. ) Is connected to one electrode terminal mechanism (9).
[0004]
FIG. 10 shows a state in which the tip end portions of some current collecting tabs are connected to the electrode terminal mechanism (9), and the other current collecting tabs are connected to the electrode terminal mechanism (9). The illustration is omitted.
[0005]
The electrode terminal mechanism (9) includes a screw member (91) attached through the lid (12) of the battery can (1). A flange portion (92) is provided at the proximal end of the screw member (91). ) Is formed. In the through hole of the lid (12), for example, an insulating packing (93) made of polypropylene is mounted, and the electrical insulation and sealing performance between the lid (12) and the fastening member (91) are maintained. . A washer (94) is fitted to the screw member (91) from the outside of the cylindrical body (11), and a first nut (95) and a second nut (96) are screwed together. The first nut (95) is tightened, and the insulating packing (93) is clamped by the flange portion (92) and the washer (94) of the screw member (91), thereby improving the sealing performance.
The tip portions (31) of the plurality of current collecting tabs (3) are connected to the back surface of the flange portion (92) of the screw member (91) by spot welding or ultrasonic welding.
By the way, in a lithium ion secondary battery, a PTC (Positive Temperature Coefficient) element having a positive temperature characteristic in a positive or negative electrode terminal mechanism in order to cut off the current when an excessive current is generated. Are known (Japanese Utility Model Laid-Open No. 52-53929, Japanese Patent Laid-Open No. 5-74493, etc.). When an excessive current is generated in such a secondary battery, the temperature of the PTC element rises due to Joule heat. For example, when the temperature reaches 50 ° C. to 80 ° C., the resistance of the PTC element increases abruptly and the current is cut off. It is.
[0007]
[Problems to be solved by the invention]
However, in the conventional cylindrical secondary battery having the gas discharge valve mechanism and the PTC element, both the gas discharge valve mechanism and the PTC element are attached to the lid of the battery can. The elements are mutually limited in size and shape. For example, a large hole for gas discharge is opened in the central part of the PTC element. It was much smaller than the area of the lid.
As a result, the rated current value of the PTC element becomes smaller than the rated current value of the battery itself. For example, a battery having a discharge capacity of 80 Ah has a problem that it can only flow a current of 20 A at a rate of 1/4 time at most.
[0008]
Accordingly, an object of the present invention is to provide a cylindrical secondary battery in which the rated current can be increased by forming the PTC element in a larger area than before.
[0009]
[Means for solving the problems]
In the cylindrical secondary battery according to the present invention, the winding electrode body (2) is accommodated in the battery can (1) in which the lid (12) is fixed to the opening of the cylinder (11). The lid body (12) is attached with an electrode terminal mechanism (4) while maintaining electrical insulation and airtightness with respect to the lid body (12), and the winding electrode body (2) and the electrode terminal mechanism (4) Are electrically connected to each other.
As shown in FIG. 7, a cylindrical gas discharge member (20) having a gas chamber (29) inside is formed on the outer surface of the lid (12) of the battery can (1). Installed with electrical insulation, the inside of the battery can (1) and the gas chamber (29) of the gas discharge member (20) communicate with each other, and the battery can ( A gas discharge valve mechanism that operates when the internal pressure of 1) exceeds a predetermined value is provided.
The electrode terminal mechanism (4) is connected to the winding electrode body (2) through the external terminal portion disposed on the surface of the gas discharge member (20) and the lid body (12) of the battery can (1). The gas discharge member (20) and the internal terminal portion are electrically connected to each other, and a flat PTC element (16) is provided between the surface of the gas discharge member (20) and the external terminal portion. ) Intervenes.
[0010]
In the cylindrical secondary battery of the present invention, the electric power generated by the winding electrode body (2) is the internal terminal portion of the electrode terminal mechanism (4), the gas discharge member (20), the PTC element (16), and the electrode. It is taken out through the external terminal portion of the terminal mechanism (4). Here, when an excessive current is generated, the electrical resistance of the PTC element (16) increases rapidly, and the current is cut off.
Further, when the internal pressure of the battery can (1) increases beyond a predetermined value, the pressure of the gas chamber (29) of the gas discharge member (20) also increases at the same time, the gas discharge valve mechanism is activated, and the pressure is increased. Opened.
[0011]
According to the cylindrical secondary battery of the present invention, since the gas discharge valve mechanism is provided on the outer peripheral surface of the gas discharge member (20), the electrode terminal mechanism (4) has no relation to the gas discharge valve mechanism. A PTC element (16) can be attached between the external terminal portion and the gas discharge member (20). Therefore, the PTC element (16) can be formed in a shape that is substantially the same in size as the gas discharge member (20) and has no holes at all, and thereby the gas discharge member (20). A wide area equivalent to the area of can be secured.
[0012]
In a specific configuration, the external terminal portion of the electrode terminal mechanism (4) has a flat portion that is in close contact with the surface of the PTC element (16).
According to the specific configuration, the external terminal portion of the electrode terminal mechanism (4) and the gas discharge member (20) can be brought into contact with the entire area of both surfaces of the PTC element (16), whereby the PTC The contact area between the element (16) and the electrode terminal mechanism (4) can be maximized to allow passage of a large current.
[0013]
In a specific configuration, the gas discharge valve mechanism is formed by a V-shaped groove (28) formed on the outer peripheral surface of the gas discharge member (20) and circling the gas discharge member (20).
In this specific configuration, when the internal pressure of the battery can (1) increases beyond a predetermined value, the internal pressure causes the gas discharge member (20) to break along the V-shaped groove (28) and the pressure is released. The
[0014]
【The invention's effect】
In the cylindrical secondary battery according to the present invention, since the gas discharge valve mechanism and the PTC element are provided at positions where they do not interfere with each other, the size and shape of the gas discharge valve mechanism and the PTC element are limited. Therefore, the PTC element can be formed in a larger area than before, and as a result, charging / discharging with a larger current than before can be performed.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention applied to a cylindrical lithium ion secondary battery will be described in detail with reference to the drawings.
First Comparative Example As shown in FIG. 1, the cylindrical lithium ion secondary battery of this comparative example has a cylindrical battery can (12) with lids (12) (12) fixed to both ends of a cylindrical body (11). 1), and the take-up electrode body (2) is accommodated in the battery can (1).
A positive electrode terminal mechanism (4) is attached to one lid (12) of the battery can (1), and a negative electrode terminal mechanism (40) is attached to the other lid (12). Yes.
[0016]
As shown in FIGS. 2 and 4, the electrode terminal mechanism (4) of the positive electrode projects the screw shaft portion (42) upward on the upper surface of the disc-shaped flange portion (43) on the outside of the lid (12). A first terminal member (41) provided, and a second terminal member having a round shaft portion (53) projecting downwardly via a boss portion (52) on the lower surface of the disc-shaped flange portion (51). 5), and the screw hole (54) is recessed in the round shaft portion (53) of the second terminal member (5).
A nut (8) is screwed into the screw shaft portion (42) of the first terminal member (41) via a washer (81).
Further, a circle having the same diameter as the flange portions (43) and (51) is provided between the flange portion (43) of the first terminal member (41) and the flange portion (51) of the second terminal member (5). A plate-like PTC element (16) is sandwiched.
[0017]
An insulating member (6) is interposed between the second terminal member (5) and the lid (12). A concave portion (61) into which the boss portion (52) of the second terminal member (5) is fitted is formed on the upper surface of the insulating member (6), and a second terminal member is formed on the bottom portion of the concave portion (61). A central hole (62) through which the round shaft portion (53) of (5) passes is formed.
A packing member (7) is disposed inside the lid (12). The packing member (7) includes a cylindrical portion (71) that fits into the central hole (15) of the lid (12) and a flange portion (72) that is in close contact with the inner surface of the lid (12). 71) and the flange portion (72) are provided with a central hole (73) through which the round shaft portion (53) of the second terminal member (5) passes.
[0018]
On the back surface of the flange portion (72) of the packing member (7), a screw member (56) comprising a screw shaft portion (57) and a hexagonal head portion (58) is installed via a washer member (55). The shaft portion (57) is screwed into the screw hole (54) of the second terminal member (5).
And the front-end | tip part of the several current collection tab (3) extended from the positive electrode of a winding electrode body (2) is clamped between the hexagon head (58) of a screw member (56), and a washer member (55). .
[0019]
The insulating member (6), the second terminal member (5), the PTC element (16), and the flange portion (43) of the first terminal member (41) are overlapped to form a laminate as shown in FIG. The outer peripheral portion of the laminate is held and integrated by the heat-shrinkable insulating member (63). In the assembly process, the heat-shrinkable insulating member (63) is heated in a state where it is attached to the outer peripheral surface of the laminate with a margin, so that the whole contracts and holds the laminate. It is.
[0020]
Thus, the first terminal member (41), the nut (8), and the washer (81) constitute an external terminal portion, and the second terminal member (5), the washer member (55), and the screw member (56) internally. A terminal part is configured.
In addition, the outer peripheral surface of the cylindrical body (11) of the battery can (1) surrounds the space between the end surface on the positive electrode side of the winding electrode body (2) and the inner surface of the lid body (12). A V-shaped groove (14) that goes around the body (11) is recessed, and the V-shaped groove (14) constitutes a gas discharge valve mechanism.
[0021]
On the other hand, as shown in FIG. 3, the negative electrode terminal mechanism (40) includes a second terminal member (50) installed through the lid (12), and a lower surface of the second terminal member (50). The screw shaft portion (42) protrudes downward.
A nut (8) is screwed into the screw shaft portion (42) of the second terminal member (50) via a washer (81).
[0022]
An insulating member (60) is interposed between the second terminal member (50) and the lid (12). Further, a packing member (7) having the same shape as the positive electrode side is provided inside the lid (12). That is, the packing member (7) includes a cylindrical portion (71) fitted into the central hole of the lid (12) and a flange portion (72) closely attached to the inner surface of the lid (12). ) And the flange portion (72) are provided with a central hole through which the round shaft portion of the second terminal member (50) passes.
[0023]
Similar to the positive electrode side, on the back surface of the flange portion (72) of the packing member (7), a screw member (56) comprising a screw shaft portion (57) and a hexagonal head portion (58) via a washer member (55). ) And the screw shaft portion (57) is screwed into the screw hole (54) of the second terminal member (5).
And the front-end | tip part of several current collection tab (3) extended from the negative electrode of a winding electrode body (2) is clamped between the hexagonal head (58) of a screw member (56), and a washer member (55). .
[0024]
In addition, the outer peripheral surface of the cylindrical body (11) of the battery can (1) surrounds the space between the negative electrode side end surface of the winding electrode body (2) and the inner surface of the lid body (12). A V-shaped groove (14) that goes around the body (11) is recessed, and the V-shaped groove (14) constitutes a gas discharge valve mechanism on the negative electrode side.
[0025]
In the cylindrical lithium ion secondary battery, for example, the current generated from the winding electrode body (2) during discharge is collected by the current collecting tab (3), the screw member (56), the second terminal member (5), the PTC element. It flows to the external circuit through (16) and the first terminal member (41).
In this process, when the internal pressure of the battery can (1) exceeds a predetermined value, for example, 5 kg / cm ² · G for some reason, the cylinder (11) of the battery can (1) is V-shaped due to the internal pressure. Break along the groove (14) and the pressure is released.
When the current increases beyond a predetermined value, the temperature of the PTC element (16) rises due to Joule heat. For example, when the temperature exceeds 50 ° C., the electrical resistance value of the PTC element (16) increases abruptly. Is cut off.
[0026]
In the cylindrical lithium ion secondary battery of the first comparative example, no hole is formed in the PTC element (16), and the first terminal member (41) is formed over the entire area of both sides of the PTC element (16). ) Flange part (43) and second terminal member (5) flange part (51) are in close contact with each other over a wide contact area to form a current path, so that a larger current than in the past flows. I can do it.
[0027]
Second Comparative Example The cylindrical lithium ion secondary battery of this comparative example is replaced with the gas discharge valve mechanism by the V-shaped groove (14) in the cylindrical lithium ion secondary battery of the first comparative example, as shown in FIG. As shown in FIG. 6, a plurality of gas outlets (18) established in the cylinder (11) of the battery can (1) and these gas outlets (18) are closed and welded to the outer peripheral surface of the cylinder (11). It is equipped with a gas discharge valve mechanism comprising a plurality of aluminum foil gas discharge valves (17). Other structures are the same as the cylindrical lithium ion secondary battery of the first comparative example.
For example, the gas discharge valve (17) has a thickness of 50 μm and an outer diameter of 16 mm, and the gas discharge port (18) has an inner diameter of 8 mm.
[0028]
In the cylindrical lithium ion secondary battery of the second comparative example, when the internal pressure of the battery can (1) exceeds a predetermined value, for example, 5 kg / cm ² · G for some reason, the internal pressure is received and gas is discharged. The valve (17) is broken and the pressure is released from the gas outlet (18).
[0029]
Cylindrical lithium ion secondary battery of the present invention embodiment examples of the present invention, as the positive electrode terminal mechanism (4), in which equipped the structure shown in FIGS. An electrode terminal mechanism (40) having the same structure as that of the first comparative example is attached to the negative electrode side (not shown).
[0030]
As shown in FIGS. 7 and 8, the lid (12) of the battery can (1) is provided with a pair of screw holes (10) and (10) on both sides of the central hole (15).
In the positive electrode terminal mechanism (4), a disk-shaped insulating member (66) is disposed outside the lid (12). The insulating member (66) is provided with a central hole (67), and a pair of through holes that match the screw holes (10) and (10) of the lid (12) on both sides of the central hole (67). (68) (68) has been established.
[0031]
A flat cylindrical gas discharge member (20) having a gas chamber (29) inside is disposed outside the insulating member (66).
A round shaft portion (26) projects downward from the lower surface of the gas discharge member (20), and a screw hole (27) is formed in the round shaft portion (26).
Also, at the bottom of the gas discharge member (20), a pair of screw holes (10) (10) matching the through holes (68) (68) of the insulating member (66) on both sides of the round shaft portion (26). These screw holes (10), (10) communicate with the gas chamber (29).
Furthermore, an external screw (24) is formed at the upper end of the gas discharge member (20).
[0032]
A pipe member (33) made of an insulating material such as Teflon passes through each through hole (68) of the insulating member (66), and an external screw (35) formed at the upper end of the pipe member (33). Is screwed into the screw hole (25) of the gas discharge member (20), and an external screw (35) formed at the lower end of the pipe member (33) is attached to the lid (12) of the battery can (1). Screwed into the screw hole (10).
As a result, the inside of the battery can (1) and the gas chamber (29) of the gas discharge member (20) communicate with each other through the central holes (34) and (34) of the pipe members (33) and (33). Become.
[0033]
A disk-shaped PTC element (16) is installed on the upper surface of the gas discharge member (20), and a first portion comprising a flange portion (43) and a screw shaft portion (42) is further formed on the upper surface of the PTC element (16). A terminal member (41) is installed. Here, the PTC element (16) has the same diameter as the flange part (43) of the gas discharge member (20) and the first terminal member (41).
The gas discharge member (20), the PTC element (16), and the flange portion (43) are stacked on each other to form a laminated body, and the outer peripheral portion of the laminated body is fastened with a hooked ring made of an insulating material. A member (64) is mounted, and an inner screw (65) formed at the lower end of the fastening member (64) is screwed into an outer screw (24) of the gas discharge member (20), thereby It is integrated.
[0034]
As in the first comparative example, the nut (8) is screwed into the screw shaft portion (42) of the first terminal member (41) via the washer (81).
In addition, a packing member (7) is provided inside the lid (12), as in the first comparative example. The packing member (7) includes a cylindrical portion (71) that fits into the central hole (15) of the lid (12) and a flange portion (72) that is in close contact with the inner surface of the lid (12). 71) and the flange portion (72) are provided with a central hole (73) through which the round shaft portion (53) of the second terminal member (5) passes.
[0035]
Further, the back surface of the flange portion (72) of the packing member (7) is composed of a screw shaft portion (57) and a hexagonal head portion (58) via a washer member (55), as in the first comparative example. The screw member (56) is installed, and the screw shaft portion (57) is screwed into the screw hole (54) of the second terminal member (5).
And the front-end | tip part of the several current collection tab (3) extended from the positive electrode of a winding electrode body (2) is clamped between the hexagon head (58) of a screw member (56), and a washer member (55). .
[0036]
Thus, the first terminal member (41), the nut (8), and the washer (81) constitute an external terminal portion, and the gas discharge member (20), the washer member (55), and the screw member (56) are internally provided. A terminal part is configured.
Further, a V-shaped groove (28) extending surrounding the gas chamber (29) is formed in the outer peripheral surface of the gas discharge member (20), and the gas discharge valve mechanism is provided by the V-shaped groove (28). It is composed.
[0037]
In the above-described cylindrical lithium ion secondary battery, for example, the current generated from the winding electrode body (2) at the time of discharging is a current collecting tab (3), a screw member (56), a gas discharge member (20), a PTC element ( 16) and through the first terminal member (41) to the external circuit.
In this process, if the internal pressure of the battery can (1) exceeds a predetermined value, for example, 5 kg / cm ² · G for some reason, the same pressure also acts on the gas chamber (29) of the gas discharge member (20). The gas discharge member (20) is broken along the V-shaped groove (28) to release the pressure.
When the current increases beyond a predetermined value, the temperature of the PTC element (16) rises due to Joule heat. For example, when the temperature exceeds 50 ° C., the electrical resistance value of the PTC element (16) increases abruptly. Shut off.
[0038]
In the cylindrical lithium ion secondary battery, no hole is formed in the PTC element (16), and the flange portion of the first terminal member (41) (with respect to the entire area of both sides of the PTC element (16) ( 43) and the gas discharge member (20) are in close contact with each other over a wide contact area to form a current path, so that a larger current can be flowed than before.
[0039]
Performance comparison experiment In order to confirm the performance of the cylindrical lithium ion secondary battery according to the present invention, the present invention example battery and the comparative example battery were prototyped through the following steps, and a performance comparison experiment was performed.
[0040]
[Preparation of positive electrode]
LiCoO ₂ as a positive electrode active material and carbon as a conductive agent were mixed at a weight ratio of 90: 5 to obtain a positive electrode mixture. Next, an NMP solution was prepared by dissolving polyvinylidene fluoride as a binder in N-methyl-2-pyrrolidone (NMP). Then, the positive electrode mixture and the NMP solution were kneaded so that the weight ratio of the positive electrode mixture and polyvinylidene fluoride was 95: 5 to prepare a slurry, and this slurry was used as both surfaces of the aluminum foil as the positive electrode current collector. Was applied by a doctor blade method and vacuum dried at 150 ° C. for 2 hours to produce a positive electrode.
[0041]
[Preparation of negative electrode]
An NMP solution was prepared by dissolving polyvinylidene fluoride as a binder in NMP. Then, a graphite powder having a particle diameter of 10 μm and an NMP solution are kneaded so that the weight ratio of the graphite powder and polyvinylidene fluoride is 85:15 to prepare a slurry, and this slurry is used as a copper as a negative electrode current collector. It apply | coated to both surfaces of foil by the doctor blade method, and vacuum-drying was performed at 150 degreeC for 2 hours, and the negative electrode was produced.
[0042]
[Preparation of electrolyte]
LiPF ₆ was dissolved at a ratio of 1 mol / l in a solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1 to prepare an electrolytic solution.
[0043]
[Battery assembly]
Between the positive electrode and the negative electrode obtained as described above, a separator made of an ion-permeable polyethylene microporous film was sandwiched and wound in a spiral shape to constitute a wound electrode body. Then, using the wound electrode body, seven types of batteries A1 to A6 and X described later were assembled for comparison. Here, the battery A3 is the battery of the present invention example.
The positive current collecting tab (3) is made of aluminum and the negative current collecting tab (3) is made of nickel and has a thickness of 0.1 mm. Joined to the body.
The cylindrical body (11) of the battery can (1) was formed with an outer diameter of 60 mm, a height of 300 mm, and a thickness of 2 mm, and the lid (12) was formed with a diameter of 60 mm and a thickness of 5 mm.
[0044]
Battery A1
The battery A1 has the structure of the first comparative example shown in FIG. 1. When the internal pressure of the battery can (1) exceeds 5 kg / cm ² · G, the cylindrical body (11) of the battery can (1) is V The depth of the V-shaped groove (14) is defined so as to break along the character-shaped groove (14). Moreover, the PTC element (16) was formed with an outer diameter of 60 mm and operated at 50 ° C. or higher.
[0045]
Battery A2
The battery A2 has the structure of the second comparative example shown in FIG. 5, and has a gas discharge valve (17) made of aluminum foil that is broken when the internal pressure of the battery can (1) exceeds 5 kg / cm ² · G. It is.
Moreover, the PTC element (16) was formed with an outer diameter of 60 mm and operated at 50 ° C. or higher.
[0046]
Battery A3
The battery A3 has the structure of the present invention example shown in FIG. 7, and when the internal pressure of the battery can (1) exceeds 5 kg / cm ² · G, the gas discharge member (20) has a V-shaped groove (28). The depth of the V-shaped groove (28) is defined so as to break along. Moreover, the PTC element (16) was formed with an outer diameter of 60 mm and operated at 50 ° C. or higher.
[0047]
Batteries A4 to A6
The battery A4 has the same structure as the battery A1 except that the area of the PTC element (16) in the battery A1 is set to 50% of the area of the lid (12).
The battery A5 has the same structure as the battery A1 except that the area of the PTC element (16) in the battery A1 is set to 80% of the area of the lid (12).
The battery A6 has the same structure as the battery A1 except that the area of the PTC element (16) in the battery A1 is set to 90% of the area of the lid (12).
[0048]
Battery X
The battery X has the structure of the third comparative example shown in FIG. 9, and an insulator (109), an internal terminal member (107), a PTC element are provided outside the cylindrical body (11) constituting the battery can (1). (100) and an external terminal member (101) are arranged, and these are fixed to the battery can (1) by a heat-shrinkable insulating member (110).
A packing member (111) is attached to a through hole formed at an eccentric position of the lid (12) of the battery can (1), and a round shaft portion (108) protruding downward from the internal terminal member (107) is provided. ) Penetrates the central hole of the pan member (111). A screw member (113) is screwed into the round shaft portion (108) via a washer member (112), and a plurality of current collecting tabs are provided between the washer member (112) and the screw member (113). The tip (31) of (3) is clamped.
[0049]
The external terminal member (101) has a screw shaft portion (104) protruding from the eccentric position of the disc portion (102), and a washer (106) is provided on the screw shaft portion (104). The nut (105) is screwed through.
The lid (12), the insulator (109), the internal terminal member (107), and the PTC element (100) are provided with central ports (117), (116), (115), and (114). In addition, a gas discharge valve (103) made of a metal thin film having an outer diameter of 5.8 mm is formed in the central portion of the disc portion (102) of the external terminal member (101).
[0050]
The battery can (1) has an outer diameter of 60 mm and a length of 300 mm, and the gas discharge valve (103) is designed to burst when the internal pressure of the battery can (1) reaches 5 kg / cm ² · G. Yes.
The PTC element (100) has an outer diameter of 33 mm and an inner diameter of 6 mm, has an area of about 30% of the area of the lid (12), and operates at 50 ° C. or higher.
[0051]
[Experiment]
First, the battery capacity was confirmed. After charging for 8 hours at a charging rate of 0.125 C, discharging was performed at a discharge final voltage of 2.7 V or 8 hours at a discharging rate of 0.125 C. C is a current value for discharging the rated capacity in one hour. In this case, 1C = 76A.
As a result, as shown in Table 1, the discharge capacity of each battery was 76 Ah.
[0052]
[Table 1]

[0053]
Next, a load factor test was performed. First, after charging for 8 hours at a charge rate of 0.125 C, the discharge rate is changed in steps of 0.125 C within the range of the discharge rate of 0.25 C to 1.25 C, and the end-of-discharge voltage 2 at each discharge rate. Discharge to 0.7V. Then, the test was terminated at a load factor at which the PTC element was activated and could not be energized.
[0054]
The test results are shown in Table 1. As apparent from Table 1, the battery X was capable of discharging at a load factor up to 0.25 C, whereas the batteries A1, A2, and A3 were capable of discharging at a load factor up to 1 C.
Further, the battery A4 can be discharged at a load factor up to 0.5C, the battery A5 at 0.75C, and the battery A6 at a load factor up to 0.875C. As the area of the PTC element increases, the range of the load factor that can be discharged increases. It became clear that it expanded.
[0055]
As described above, in the cylindrical lithium ion secondary battery according to the present invention, since the size of the PTC element is not limited by the gas discharge valve mechanism, a PTC element having a larger area than the conventional one can be installed. Therefore, discharge with a larger current than before can be performed.
The battery of the present invention is particularly effective for large batteries having a discharge capacity of 2 Ah or more.
[Brief description of the drawings]
FIG. 1 is a front view of a cylindrical lithium ion secondary battery of a first comparative example.
FIG. 2 is an enlarged sectional view showing an electrode terminal mechanism on the positive electrode side of the cylindrical lithium ion secondary battery.
FIG. 3 is an enlarged sectional view showing an electrode terminal mechanism on the negative electrode side of the cylindrical lithium ion secondary battery.
FIG. 4 is an exploded perspective view of the electrode terminal mechanism on the positive electrode side.
FIG. 5 is a front view of a cylindrical lithium ion secondary battery of a second comparative example.
FIG. 6 is an enlarged cross-sectional view of a gas discharge valve mechanism including a gas discharge valve and a gas discharge port.
FIG. 7 is an enlarged cross-sectional view showing an electrode terminal mechanism on the positive electrode side in a cylindrical lithium ion secondary battery of an example of the present invention.
FIG. 8 is an exploded perspective view of the electrode terminal mechanism.
FIG. 9 is an enlarged sectional view showing an electrode terminal mechanism on the positive electrode side in a third comparative example.
FIG. 10 is an enlarged cross-sectional view showing an electrode terminal mechanism on the positive electrode side in a conventional cylindrical lithium ion secondary battery.
[Explanation of symbols]
(1) Battery can
(11) Tube
(12) Lid
(14) V-shaped groove
(16) PTC element
(2) Winding electrode body
(3) Current collection tab
(4) Electrode terminal mechanism
(41) First terminal member
(5) Second terminal member
(56) Screw member
(6) Insulating material
(63) Heat-shrinkable insulation member

Claims (3)

  The winding electrode body (2) is accommodated in the battery can (1) formed by fixing the lid body (12) to the opening of the cylindrical body (11), and the lid body (12) includes a lid body (12). 12) The electrode terminal mechanism (4) is attached while maintaining electrical insulation and airtightness, and the winding electrode body (2) and the electrode terminal mechanism (4) are electrically connected to each other, and the winding electrode In the cylindrical secondary battery in which the electric power generated by the body (2) can be taken out from the electrode terminal mechanism (4), the outer surface of the lid (12) of the battery can (1) has an internal gas chamber. A cylindrical gas discharge member (20) having (29) is installed so as to be electrically insulated from the lid (12), and the inside of the battery can (1) and the gas chamber of the gas discharge member (20) ( 29) and a gas discharge valve mechanism that operates when the internal pressure of the battery can (1) exceeds a predetermined value is provided on the outer peripheral surface of the gas discharge member (20). ) Is placed on the surface of the gas discharge member (20) A gas discharge member (20) and an internal terminal part, comprising an internal terminal part and an internal terminal part connected to the take-up electrode body (2) through the lid (12) of the battery can (1). A cylindrical element characterized in that a flat element (16) having a positive resistance temperature coefficient is interposed between the surface of the gas discharge member (20) and the external terminal part, which are electrically connected to each other. Next battery. The cylindrical secondary battery according to claim 1 , wherein the external terminal portion of the electrode terminal mechanism (4) has a flat portion that is in close contact with the surface of the element (16). Gas exhaust valve mechanism according to claim 1 or claim 2 is constituted by a V-shaped groove (28) formed on the outer peripheral surface orbiting gas discharge member (20) of the gas discharge member (20) Cylindrical secondary battery.

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