JP2005149794A - Electrode for battery and battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode for a battery, which prevents a short circuit current on the occurrence of a short circuit from localizing to a part, and a battery. <P>SOLUTION: A plurality of electrodes for battery 15 are laminated to be used, where a fuse portion (resistor portion) 18 is formed in the electrode for battery 15 to limit a current path. An example of the fuse portion 18 is a narrow range portion of the electrode, where the narrow range portion is an incision formed in the electrode and is blocked by a gap 17. The fuse portion 18 melts on the occurrence of the short circuit, to electrically separate a short-circuit area from the current path and to prevent further heat generation. If a plurality of the fuse portions 18 are formed, some of them can be melted by heat. In this case, the fuse portions 18 melt, to electrically separate the short-circuit area from the current path, and other fuse portions 18 restrict the current flowing through the electrode. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a battery configured by stacking a plurality of electrodes, such as a lithium battery, and an electrode used in the battery.

FIG. 16 shows an example of a conventional lithium secondary battery. The lithium secondary battery 1 is a so-called square shape, and is provided between a plurality of positive electrodes (electrodes) 2, negative electrodes (electrodes) 3, and the positive electrodes 2, and negative electrodes 3. The separators 4... Arranged and a non-aqueous electrolyte are mainly used.
The positive electrode 2..., The negative electrode 3... And the separator 4... And the non-aqueous electrolyte are housed in a battery case 5 made of stainless steel or the like. A sealing body 6 is attached to the opening of the battery case 5.

In the battery case 5, a plurality of positive electrodes 2, separators 4, and negative electrodes 3 are alternately stacked and stored.
A positive electrode tab portion 12a is formed at one end of the positive electrode 2 ..., and a positive electrode lead 12b for connecting the positive electrode tab portion 12a is attached to an upper portion of the positive electrode tab portion 12a.
And the positive electrode terminal 7 which penetrates the sealing body 6 is attached to the upper part of the positive electrode lead 12b.
Further, negative electrode tabs 13a are formed at one end of the negative electrodes 3 ..., and negative electrode leads 13b for connecting the negative electrode tabs 13a are attached to the upper portions of the negative electrode tabs 13a.
And the negative electrode terminal 8 which penetrates the sealing body 6 is attached to the upper part of the negative electrode lead 13b.
With the above configuration, the positive electrode terminal 7 and the negative electrode terminal 8 are configured to extract current from the positive electrode 2... And the negative electrode 3.
A safety valve 9 is provided in the approximate center of the sealing body 6.
JP-A-5-314984 JP-A-5-314985 JP-A-5-314969

In such a lithium secondary battery, with an increase in size and capacity, the current and time flowing through the short circuit portion when an internal short circuit occurs tends to be large and long.
In a small lithium battery (18650 type) with a battery capacity of several Wh, the heat generation is about 80 ° C. to 100 ° C. However, in the case of a large lithium secondary battery of several hundred Wh, if the internal short circuit is forced, several thousand A A current flows and a temperature rise of 400 ° C. or more occurs.
If the local short-circuit current level exceeds a predetermined threshold, there is a possibility that a thermal runaway in which an exothermic reaction further progresses due to a local temperature rise due to Joule heat generation. Leading to improved reliability.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a battery electrode and a battery that can suppress local concentration of a short-circuit current at the time of a short circuit.

In the present invention, the following means are adopted in order to solve the above problems.
The invention described in claim 1 is characterized in that, in a battery electrode in which a plurality of sheets are stacked to constitute a battery, a resistance portion for limiting a current path is provided in the electrode.
According to a second aspect of the present invention, in the battery electrode according to the first aspect, the electrode main body and a tab portion provided at one end of the electrode main body and connected to the battery terminal are provided, and the electrode main body and the tab portion At least one of the resistance portions is provided.
According to a third aspect of the present invention, in the battery electrode according to the second aspect, the resistance portion is provided on both the electrode body and the tab portion.
According to a fourth aspect of the present invention, in the battery electrode according to any one of the first to third aspects, the resistance portion is a narrow portion of the electrode limited by a notch formed in the electrode. To do.
According to a fifth aspect of the present invention, in the battery electrode according to the fourth aspect, the electrode is divided into a plurality of narrow electrode plate sections by the notches, and each electrode plate section is separated from each other by the narrow portion. The current path is long due to the connected state.
According to a sixth aspect of the present invention, in the battery electrode according to any one of the first to fifth aspects, a metal layer having a plurality of holes is provided on each of both surfaces of the insulating layer, and the periphery of the hole is the resistance. It is characterized by being part.

An outline of the present invention is shown in FIG.
FIG. 15A shows a conventional example, in which a group of electrodes each having a positive electrode and a negative electrode are connected in parallel to form one battery.
When a short circuit of the resistance R _S (≈0Ω) occurs in a certain portion, a short circuit current flows through the internal resistance R _{i of the} electrode. Since the internal resistance R _i is small, a large current I flows and heat is generated in proportion to the square of the current.
When a resistor _Rh is provided in the electrode as shown in FIG. 15 (b), the current flowing at the time of short-circuiting is suppressed (current I ′ <I). Below the speed, thermal runaway is suppressed.
That is, by providing a resistance portion in the electrode as in the present invention, it is possible to prevent a large current from flowing locally at the time of a short circuit as described above and suppress heat generation.
Furthermore, it has been found that it is effective to increase the current path resistance by narrowing and extending the current path.
Also, if resistance parts are provided on both the electrode body and the tab part, heat is generated more effectively while suppressing the total resistance value than when a resistance part is provided on either the electrode body or the tab part. It was also found that can be suppressed.

  A seventh aspect of the present invention is the battery electrode according to any one of the first to sixth aspects, wherein the resistance portion is dissolved by heat caused by a short-circuit current.

In the present invention, when the resistance portion melts as a fuse, the short-circuit portion is electrically isolated and the short-circuit current is interrupted to prevent further heat generation. For example, when the material of the electrode is aluminum, the melting point is about 660 ° C., so the size of the resistance portion is determined so that the resistance portion exceeds this temperature by the current flowing at the time of short circuit.
When a plurality of resistance portions are provided on the electrode or the tab portion, some of them may be melted by heat. In this case, the short-circuit current is suppressed by electrically isolating the short-circuit portion by the dissolved resistance portion or by restricting the current path.

  The invention according to claim 8 is the battery electrode according to any one of claims 1 to 7, wherein the electrode is fused to a separator.

  In the present invention, manufacturing inconveniences such as breaking of the electrode along the notch are eliminated, and the handleability of the electrode is improved.

  The invention according to claim 9 is a battery in which a plurality of electrodes are stacked, wherein the electrode is the electrode according to any one of claims 1 to 8.

  According to the present invention, when the electrode is short-circuited, the short-circuit current is suppressed by the resistance portion, or the resistance portion is dissolved and the short-circuit portion is electrically isolated, thereby preventing thermal runaway of the battery. A battery with high reliability can be obtained.

In the present invention, the following effects can be obtained.
By providing a resistance portion in the electrode or in the tab portion, a large current is prevented from flowing during a short circuit, and heat generation is suppressed. Moreover, a short circuit part is electrically isolated by making a resistance part into the fuse which melt | dissolves with a heat | fever. Therefore, by adopting such an electrode for a battery, thermal runaway of the battery can be prevented and a battery with higher reliability can be obtained.
Furthermore, heat generation can be suppressed very effectively by providing resistance portions on both the electrode body and the tab portion.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an electrode (positive electrode, negative electrode) 15 according to this embodiment. The electrode 15 includes a tab portion 15a connected to the battery terminal and an electrode main body 15b, and is provided so that a tab portion 15a narrower than the electrode main body 15b protrudes upward from an upper edge end portion of the electrode main body 15b.
The electrode body 15b is divided into a plurality of narrow and narrow electrode plate sections 16, 16,..., And each electrode plate section 16, 16... Is separated from each other by a gap (cut) 17 as an insulating region. Part) 18. As a result, the current path is thin and long. That is, the current path resistance of the electrode plate sections 16, 16. The fuse portion 18 is a narrow electrode region limited by the gap 17 and has an electric resistance due to its narrow width. When manufacturing this electrode 15 (easy after electrode layer coating), the gap 17 is punched while leaving the fuse portion 18 so that each electrode section 16 is connected. Thereby, the whole is integrally formed.
An example of a short circuit is shown in FIG. When a short circuit occurs at the reference numeral 19 in the figure, the resistance of the short circuit increases due to the current path resistance of the electrode plate section 16 itself, so that the flowing current is limited. By increasing the number of electrode plate sections, the current path resistance of the electrode plate section 16 itself increases. When the resistance increases to a certain extent, the maximum temperature is lowered with a decrease in the short-circuit current, and thermal runaway is suppressed.
Further, by providing the fuse portions 18a and 18b in the upper part of the section, the fuse portion 18 generates heat due to a high current and melts. As a result, the short circuit 19 is electrically isolated, and heat generation after the isolation is prevented. Therefore, the occurrence of thermal runaway is prevented.

FIG. 3 shows an electrode (positive electrode, negative electrode) 20 shown as a modification. The electrode 20 includes a tab portion 20a connected to the battery terminal and an electrode main body 20b, and is provided so that a tab portion 20a narrower than the electrode main body 20b protrudes upward from an upper edge end portion of the electrode main body 20b.
In the electrode body 20b, a plurality of electrode plate sections 22, 22,... Are connected by a fuse part (resistor part) 24 with a gap (cut) 23 therebetween as an insulating region. The fuse portion 24 is a narrow electrode region limited by the gap 23 and has an electric resistance because of its narrow width. When the electrode 20 is manufactured (easy after electrode layer coating), the gaps 23 are punched out in a lattice shape while leaving the fuse portions 24 so that the electrode plate sections 22 are connected. Thereby, the whole is integrally formed.
Also in this modification, a high current flows through the fuse portion 24 in the same manner as in FIG. Since the fuse part 24 is an electric resistance, it generates heat by a high current and melts. As a result, the short circuit is electrically isolated and heat generation after isolation is prevented. Therefore, the occurrence of thermal runaway is prevented.
Even when the fuse part 24 does not melt, the fuse part 24 restricts the current path as a resistance, so that the flowing current is smaller than in the conventional case. Since the heat generation is proportional to the square of the current, the rate of temperature rise is slower than the conventional example in which the fuse portion 24 is not provided. Therefore, the generated heat is naturally dissipated and thermal runaway is suppressed.

  4 and FIG. 5 show modifications (electrodes 26 and 27) in which the arrangement of the electrode plate sections 22 is different. In these examples, the same effect as in FIG. 3 can be obtained. In the case of FIG. 4, since the gap 23 is not provided over the entire width or height of the electrode 26, the electrode 26 is not bent along the gap 23 during manufacturing, and is easier to handle.

  FIG. 6 shows an electrode 28 as a modification. In the illustrated example, the electrode is divided into a plurality of electrode plate sections 30 by a plurality of rows of perforations 29. Each perforation 29 includes a plurality of gaps (cuts) 29a and a large number of fuse portions (resistance portions) 29b that connect the electrode plate sections 30 alternately. The fuse portion 29b is a narrow electrode region limited by the gap 29a, and has an electric resistance due to the narrow width. Also in this example, the perforation 29 is applied to the electrode 28 when the electrode 28 is punched. Thereby, the whole is integrally formed.

Also in this electrode, similarly to the above example, the fuse portion 29b is melted at the time of a short circuit, the short circuit portion is electrically isolated, and excessive heat generation is prevented.
Even when the fuse portion 29b is not melted, the fuse portion 29b limits the current path as a resistor, so that the temperature rise rate is suppressed and thermal runaway is suppressed as in the above example.

  Furthermore, for each of the above examples, as shown in FIG. 7, a separator 31 may be fused to the electrode. As a result, the strength is enhanced, manufacturing inconveniences such as breaking along the gap 23, the perforation 29, and the like are eliminated, and the handleability of the electrode is improved.

Furthermore, FIG. 8 is an example of another electrode, and is a sectional view of the electrode. Metal layers 34 are formed on both surfaces of the insulating layer (polymer film) 33. Further, an electrode layer 35 is applied. As shown in FIG. 9 or 10, the metal layer 34 is provided with holes 36 and 37 as a whole. Around these holes 36 and 37 are fuse portions (resistor portions) 38 and 39.
Also in this example, at the time of a short circuit, the fuse parts 38 and 39 are melted, the short circuit part is electrically isolated, and excessive heat generation is prevented. Even when the fuse portions 38 and 39 are not melted, the fuse portions 38 and 39 limit the current path as a resistance, so that the temperature rise rate is suppressed and thermal runaway is suppressed as in the above example.
Note that the lithium battery has a thick electrode, and therefore, a plurality of electrode plates must be bonded to form a single electrode. Therefore, the process of putting the gap 23 or the perforation 29 can be manufactured more easily than the present modification in which a hole is made in the whole.

Furthermore, like the electrode 40 of FIG. 11, as a modification of the electrode 20 of FIG. 3, the gap 23 may be widened away from the tab portion 40a connected to the battery terminal. Relative to the tab portion 40a in the figure, L ₁ the distance to the gap 23 extending closest to the left-right direction from the electrode body 40b on the _edge, the distance L ₂ to the gap 23 extending in the next left-right _direction, further electrode body 40b the distance to the lower edge of the L _3. Let these relationships be L ₁ <L ₂ <L ₃ .
When configured as in this example, the vicinity of the tab portion 40a has a higher resistance. In the prior art in which the gap 23 and the fuse portion 24 are not provided, a higher current flows as the distance from the tab portion 40a increases. Therefore, in this example, the high current can be efficiently suppressed by providing an appropriate resistor for the place where the high current flows.
For the same reason, the width of the fuse portion 24 may be increased as the distance from the tab portion 40a increases.
Of course, the present modification can be applied not only to the electrode 20 of FIG. 3 but also to the other electrodes described above.

Furthermore, as a modification, a fuse portion may be provided in the tab portion 41a as in the electrode 41 of FIG. In the main electrode 41, the tab portion 41a is divided into a plurality of narrow and narrow electrode plate sections 42, 42, and the electrode plate sections 42, 42 are separated from each other by a gap (cut) 42a as an insulating region. Thus, they are connected by a fuse part (resistor part) 42b. As a result, the current path is thin and long. The fuse portion 42b is a narrow electrode region limited by a gap, and has an electric resistance due to its narrow width. When the electrode 41 is manufactured (easy after electrode layer coating), the gap 42a is punched while leaving the fuse portion 42b so that the electrode plate sections 42 are connected. Thereby, the whole is integrally formed.
Also in the main electrode 41, heat generation at the time of a short circuit can be prevented by the action of the fuse portion 42b and the current path resistance of the electrode plate section 42 as in the above examples.

Furthermore, you may comprise as follows. A perforation 44 along a curve is provided so as to surround the tab portion 43a in the vicinity of the tab portion 43a on the electrode main body 43b side like the electrode 43 in FIG. In this case, since the perforation 42 is along a curve, it is difficult to bend and handling becomes easy.
Note that the detailed configuration of the perforation 44 is the same as that of the perforation 29 described above, and thus the description thereof is omitted.
Also in this electrode 43, the perforation 44 is provided, so that heat generation at the time of a short circuit can be prevented.

In each of the above examples, a resistor is provided only on the tab portion or only on the electrode body. Furthermore, if a resistance part is provided in both the tab part and the electrode body, heat generation can be suppressed more effectively. About the general lithium battery of 300wh class, the heat_generation | fever when the nail penetration test was done by changing the resistance value of a tab part and an electric current path was measured. The results are shown in FIG. The example of FIG. 12 was used as the resistance of the tab portion, and the example of FIG. 1 was used as the resistance of the electrode body.
When the fuse part is provided only in the tab part, the heat generation is suppressed to 106 ° C. or less when the resistance of the tab part is 500 mΩ or more, and when the fuse part is provided only in the electrode body, the resistance is 48.5 mΩ or more and 110 The exotherm was suppressed to ℃. On the other hand, when these are combined, like the battery 9 and the battery 10, the resistance of the tab portion is 100 mΩ and the resistance of the electrode body is 9.7 mΩ, or the resistance of the tab portion is 200 mΩ and the resistance of the electrode body is 2.9 mΩ. In this case, it was confirmed that the maximum temperatures were sufficiently low at 120 ° C. and 125 ° C., respectively.
Thus, if a fuse part is provided in both a tab part and an electrode main body, a highly reliable battery can be comprised, maintaining high energy efficiency.

It is a front view of the electrode for batteries shown as one embodiment of the present invention. It is the front view shown about the state at the time of the short circuit of the battery electrode. It is a front view of the electrode for batteries shown as other embodiments of the present invention. It is the front view shown about the modification of the electrode for batteries. It is the front view shown about the modification of the electrode for batteries. It is the front view shown about the modification of the electrode for batteries. It is the front view shown about the modification of the electrode for batteries. It is a modification of a battery electrode and is a sectional view of the electrode. It is the figure shown about the modification of the electrode for batteries. It is the figure shown about the modification of the electrode for batteries. It is the front view shown about the modification of the electrode for batteries. It is the front view shown about the modification of the electrode for batteries. It is the front view shown about the modification of the electrode for batteries. It is the table | surface which showed the heat_generation | fever when a nail penetration test was done by changing the resistance value of a tab part and an electrode main body. It is the schematic circuit diagram shown about the principle of the battery electrode of this invention. It is the partial fracture | rupture perspective view shown about the structure of the general lithium secondary battery.

Explanation of symbols

15 Electrode 15a Tab portion 15b Electrode body 17 Gap (cut)
18 Fuse part (resistor part)
20 Electrode 20a Tab portion 20b Electrode body 23 Gap (cut)
24 Fuse part (resistor part)
26, 27, 28 Electrode 29 Perforation 29a Clearance (cut)
29b Fuse part (resistor part)
31 Separator 33 Insulating layer 34 Metal layer 36, 37 Hole 38, 39 Fuse part (resistance part)
40, 41, 43 Electrode 40a, 41a, 43a Tab part 42 Electrode plate section 42a Gap (cut)
42b Fuse part 44 perforation

Claims (9)

In the electrode for a battery constituting a battery by stacking a plurality of sheets,
A battery electrode, wherein a resistance portion for limiting a current path is provided in the electrode.   An electrode main body and a tab portion provided at one end of the electrode main body and connected to a battery terminal are provided, and the resistance portion is provided in at least one of the electrode main body and the tab portion. Item 2. The battery electrode according to Item 1.   The battery electrode according to claim 2, wherein the resistance portion is provided on both the electrode main body and the tab portion.   4. The battery electrode according to claim 1, wherein the resistance portion is a narrow portion of the electrode limited by a notch formed in the electrode. 5.   The electrode is divided into a plurality of narrow electrode plate sections by the notch, and each electrode plate section is connected to each other by the narrow portion, so that a current path is long. The battery electrode according to claim 4.   The battery electrode according to any one of claims 1 to 5, wherein a metal layer having a plurality of holes is provided on each of both surfaces of the insulating layer, and the periphery of the hole is the resistance portion.   The battery electrode according to claim 1, wherein the resistance portion is dissolved by heat caused by a short-circuit current.   The battery electrode according to any one of claims 1 to 7, wherein the electrode is fused to a separator. In a battery in which a plurality of electrodes are laminated,
The battery according to claim 1, wherein the electrode is an electrode according to claim 1.

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