JP2007134110A - Lead-acid storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lead acid storage battery using a fiber mat separator which does not require jointing of separators in which a necessary jointing strength is hard to obtain, and suppresses short circuit between the electrode plates due to expansion of an active material and deterioration of battery capacity caused by this. <P>SOLUTION: A fiber mat separator is folded into two and made in V-shape, and a separator which is folded in zigzag shape alternately so that it may be folded to nearly cross the folded line at right angles is formed, and an electrode plate of one polarity is arranged at a first separator overlapping part of which the upper part is open and the bottom part is closed. An electrode plate of the other polarity is arranged at a second separator overlapping part of which both the upper part and the bottom part are open, or at any one or both of the end faces of zigzag separators, and at least, a pair of the first separator overlapping part with no electrode plate and the second separator overlapping part with no electrode plate are arranged between the pair of electrode plates mutually opposed to each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lead storage battery used for an electric vehicle power source and the like.

  Conventionally, in lead-acid batteries, a bag-like separator has been used to prevent an internal short circuit between the electrodes due to softening of the active material and dropping off from the electrodes. For example, in an open-liquid type lead-acid battery used in general start-up lead-acid batteries, the left and right ends of a sheet-like separator made of a synthetic resin such as polyethylene are sealed by crimping, laser welding, or heat welding. In addition, a bag-like separator is widely used.

  In particular, in lead acid batteries for cycle services and control valve type lead acid batteries, a mat separator that is impregnated with an electrolytic solution and abuts on the electrode plate surface with an appropriate pressure is used. As a material of such a mat separator, a material having acid resistance to a dilute sulfuric acid electrolytic solution, such as glass fiber or a polypropylene fiber subjected to hydrophilic treatment such as sulfonation treatment, and having affinity with the electrolytic solution Is used.

  In a lead storage battery, the active material of a positive electrode and a negative electrode expand | swells according to the use. In the case of cycle service where deep charge and discharge are repeated, the expansion of the negative electrode active material is particularly remarkable, and the expanded active material causes an internal short circuit between the electrode plates, causing a decrease in capacity. In the case of using a lattice body having no frame bones on the side portions, such as an expanded lattice body, such expansion of the active material is particularly likely to occur.

  In order to prevent such an internal short circuit due to expansion of the active material, a structure is known in which an electrode plate is disposed on a folded separator and the side portions of the electrode plate are covered with the separator.

  For example, in Patent Document 1, the separators are alternately folded, and the positive and negative electrode plates are arranged between the separators, and the lower end and side surfaces of the separator are wrapped so as to wrap any one of these positive and negative plates in a bag shape. The structure which welded the part is shown.

  In said structure, the process of joining a separator is needed. When a fiber mat made of polypropylene fiber or glass fiber mixed with this is used as a raw material, mats can be joined to each other by heat welding. As described above, the bonding strength is remarkably reduced as compared with the case where the bonding surfaces are closely adhered and welded.

In addition, even when an adhesive or hot melt agent is applied to the fiber mat and bonded together, it is relatively easy to peel between the part where the fiber mat adhesive or hot melt agent has penetrated and the part that has not penetrated. Therefore, satisfactory bonding strength could not be obtained.
JP 59-163772 A

  The present invention eliminates the need for bonding between separators in a lead storage battery using a fiber mat separator, which makes it difficult to obtain the required bonding strength, and suppresses short-circuiting between electrodes due to active material expansion and battery capacity reduction due to this. The purpose is to do.

  In order to solve the above-described problem, the invention according to claim 1 of the present invention is a fold which is substantially perpendicular to the fold at the bottom, in which a separator made of fiber mat is folded in two to form a V shape. In order to form a spelling separator with an opening at the top, the electrode plate of one polarity is placed on the first separator overlap part with the top open and the bottom closed. , The second separator overlapping portion having both the top and the bottom opened, or the end face of the zigzag separator, the other polarity electrode plate is disposed, and they are different from each other, and Between the pair of electrode plates facing each other, at least one pair of a first separator overlapping portion where no electrode plate is arranged and a second overlapping portion where no electrode plate is arranged is arranged, and at least the negative electrode plate is on that side Part It shows a lead-acid battery, characterized in that it comprises an expandable lattice having no frame bone.

  According to the configuration of the present invention described above, the side and bottom portions of at least one polarity electrode plate can be covered without bonding the mat separators. It is possible to suppress a decrease in battery capacity due to.

  Hereinafter, the structure of the lead acid battery by embodiment of this invention is demonstrated.

  As shown in FIG. 1, a fiber mat 101 made of a synthetic resin fiber such as glass fiber or polypropylene is folded in two to form a V shape. Next, the folds are folded alternately at the folds 103 that are substantially orthogonal to the folds 102 at the bottom of the folded fiber mat 101 to form the fold separators 201 shown in FIG.

  Fiber mats are overlapped in the zigzag fold separator 201 by two folds and zigzag folds, and an opening is formed at the overlapping end on the opposite side of the fold 102 at the bottom. In the present invention, the electrode plate 203 having either the positive polarity or the negative polarity is arranged in the first separator overlapping portion 202 formed by folding in which the upper portion is opened and the bottom portion is closed by the fold line 102. .

  Then, the upper part is open and the bottom part is not closed by the fold 102, that is, at least one of the second separator overlapping part 204 formed by the zigzag fold or the end face 205 of the zigzag fold separator 201 has the other polarity. The electrode plate 203 ′ is arranged to form the electrode plate group 206 shown in FIG.

  In the present invention, the first separator overlapping portion 202 that does not dispose the electrode plate and the second electrode that does not dispose the electrode plate between a pair of the electrode plates 203 and the electrode plate 203 ′ that are different in polarity and face each other. The electrode plate 203 and the electrode plate 203 ′ are arranged on the zigzag separator 201 so that at least one pair of the overlapping portions 204 exists.

  It should be noted that whether the electrode plate 203 ′ is arranged at either the second separator overlapping portion 204, the end face 205 of the zigzag separator 201, or both is determined by the electrode constituting the electrode plate group. It depends on the number of plates 203 and electrode plates 203 ′.

  For example, in the case of two electrode plates 203 and three electrode plates 203 ′ as in the electrode plate group 206 used in the battery of the present invention shown in FIG. 2, one electrode plate 203 ′ is a second electrode plate. The other two sheets of the electrode plate 203 ′ are arranged on the end face 205 of the folded separator 201. In this case, the electrode plate 203 ′ is disposed on both the second separator overlapping portion 204 and the end face 205.

  If the electrode plates at both ends of the electrode plate group 206 in FIG. 2 are removed to form two electrode plates 203 and one electrode plate 203 ′, the electrode plate 203 ′ is only the second separator overlapping portion 204. Will be placed.

  Furthermore, in the electrode plate group 305 used in the battery of the present invention using the zipper folding separator 301 (corresponding to the zigzag folding separator 201 having a small number of zigzag foldings shown in FIG. 2) as shown in FIG. Is disposed in the first separator overlapping portion 302 located in the center, and the electrode plate 203 ′ is disposed only on the end face 303. In this case as well, a pair of second separator overlapping portions 304 having no electrode plates is disposed between the adjacent electrode plates 203 and 203 ′ as well as the first separator overlapping portions 302 having no electrode plates.

  That is, in the present invention, the electrode plate 203 ′ is different from the first separator overlapping portion 202 (302) in which the electrode plate 203 is disposed to the first separator overlapping portion 202 (302) in which the electrode plate is not disposed. What is necessary is just to arrange | position to the position where at least one pair of the 2nd separator overlap part 204 (304) which has not arrange | positioned an electrode plate exists, and the arrangement position of electrode plate 203 'is 2nd separator overlap depending on the number of electrode plate components. Either one or both of the mating portion 204 and the end surface 205 is used.

  Further, either one of the electrode plate 203 and the electrode plate 203 ′ is a positive electrode plate, and the other one is a negative electrode plate, but at least the negative electrode plate does not have a frame on its side, and the lattice is open on the side. An expanded lattice body having grids is provided.

  Then, by using the electrode plate group 206 and the electrode plate group 305, a known configuration is adopted thereafter, and the lead storage battery according to the present invention is obtained by creating a lead storage battery.

  In the lead-acid battery of the present invention, the bonding strength is unstable, and without joining the fiber mats, the side and bottom of one polar plate and the side and bottom of the adjacent other polar plate are connected. Can be isolated with fiber mat. Therefore, in particular, in the negative electrode plate using an expanded lattice body that does not have a frame on the side part, even when the active material is volume-expanded by a deep charge / discharge cycle, the inside of the electrode plate due to the expanded active material A short circuit and a decrease in battery capacity due to this can be suppressed.

  In the present invention, between the adjacent electrode plates, at least a pair of the first separator overlapping portion 202 (302) and the second separator overlapping portion 204 (304), in which neither electrode plate is disposed, is disposed.

  For example, as shown in FIG. 4, in the separator 401 that is alternately folded at the fold orthogonal to the fold after being folded in two, the first overlapping portion 402 and the second overlapping that are adjacent to each other are folded. When the electrode plates 203 and 203 ′ are disposed on the portion 404 and the end surface 405, the electrode plate side portions are exposed on both the electrode plate 203 and the electrode plate 203 ′, and therefore, the expansion active material causes an internal short circuit between these electrode plates. .

  In addition, when only the second separator overlapping portion where one electrode plate is not arranged is arranged between a pair of adjacent electrode plates, the expansion active material permeates between the zigzag folds where the fiber mat is not joined. And causes an internal short circuit between the plates. In addition, when both the electrode plates 203 and 203 ′ are arranged in the end portion 205 and the second separator overlapping portion 204, the bottom portion of each electrode plate is not covered with the fiber mat. This is not preferable because an internal short circuit occurs.

  A lead storage battery according to the above-described example of the present invention and a lead storage battery according to a comparative example to be described later were prepared, and a battery capacity transition in repeated charge / discharge was confirmed by a cycle life test. In both the inventive examples and the comparative examples, the electrode plate 203 was a positive electrode plate having an expanded lattice body, and the electrode plate 203 ′ was a negative electrode plate having an expanded lattice body. All were made into the control valve type lead acid battery of 12V4.8Ah.

(1) Battery A of the present invention example
In the embodiment of the present invention described above, the control valve type lead storage battery (12V12Ah) has the electrode plate group 206 shown in FIG. In addition, as a fiber mat, the glass mat whose thickness at the time of 19.6kPa pressurization is 0.6 mm was used. The battery according to the example of the present invention is referred to as a battery A.

(2) Battery B of Comparative Example
As shown in FIG. 4, the battery B of the comparative example uses a separator 401 that is folded in a V shape so that the glass fiber mat is folded in two so as to be substantially perpendicular to the folded fold. A second separator having both an upper portion and a bottom portion, which is disposed in the first separator overlapping portion 402 having an open top portion and a closed bottom portion, and is adjacent to the end face 405 and the polar plate 203. It is a battery having a group configuration housed in the overlapping portion 404. In addition, in order to make the distance between the electrode plates the same as the battery A of the present invention example, the thickness of the glass fiber mat when the pressure of 19.6 kPa was applied was 1.8 mm.

(3) Battery C of Comparative Example
The battery C of the comparative example is a battery having a group configuration in which an electrode plate 203 and an electrode plate 203 ′ are laminated via a flat glass fiber mat 501 as shown in FIG. In addition, in order to make the distance between the electrode plates the same as the battery A of the present invention example, the thickness of the glass fiber mat 501 when pressed with 19.6 kPa was 1.8 mm.

(4) Battery D of Comparative Example
As shown in FIG. 6, the battery D of the comparative example includes a bag-shaped glass fiber mat 601 containing an electrode plate 203 ′ (a negative electrode in this embodiment) and an electrode plate 203 (a positive electrode in this embodiment). A battery having a stacked group structure. The bag-like glass fiber mat 601 has an opening at the top by folding a flat glass fiber mat having a thickness of 1.8 mm when pressed with 19.6 kPa into two V-shaped shapes and joining both sides. It is made into the bag shape which has. In addition, the joining of both side parts was performed by heat welding using what mixed the polypropylene resin fiber in the glass fiber mat.

(5) Battery E of Comparative Example
In the battery E of the comparative example, the electrode plate enclosed in the bag-shaped glass fiber mat 601 used in the battery D of the comparative example is the electrode plate 203 (positive electrode in the embodiment), and the electrode plate 203 ′ (negative electrode in the present embodiment). ).

  Each of the batteries A to B of the present invention and the batteries B to E of the comparative examples was discharged to 10.5 V at 1.2 A in a 25 ° C. atmosphere, and then 14.7 V constant voltage charging (maximum charging current 4 8A) was carried out for 8 hours. The cycle life test was conducted with this discharge-charging as one cycle. The result is shown in FIG. The battery capacity is shown as a percentage when the initial capacity is 100, that is, the capacity maintenance rate.

  From the results shown in FIG. 7, the discharge capacity of the battery B and the battery C of the comparative example rapidly decreases after 200 cycles. When the batteries B and C were disassembled, the negative electrode active material expanded significantly and was internally short-circuited at the side of the electrode plate group.

  The discharge capacity of the battery D of the comparative example was drastically reduced after 250 cycles, and the battery E of the comparative example was drastically reduced after 300 cycles. In the battery D of the comparative example, the joint portion of the bag-shaped glass fiber mat 601 was peeled off due to significant expansion of the negative electrode active material, and an internal short circuit occurred. In the battery E of the comparative example, the positive electrode active material and the positive electrode lattice body expanded with the significant expansion of the negative electrode active material, the joint portion of the bag-like fiber mat peeled off, and was short-circuited with the expanded negative electrode active material.

  On the other hand, in the battery A of the example of the present invention, the rapid capacity decrease as seen in the battery of the comparative example does not proceed. It had 90% of the initial capacity at the 400th cycle and 50% of the initial capacity at the 600th cycle. When the test was completed in 600 cycles and the battery A was disassembled, both the positive electrode and the negative electrode active material expanded significantly, but no internal short circuit occurred. Moreover, when the polarization of the positive electrode and the polarization of the negative electrode were measured in the discharge at the 600th cycle, the polarization at the positive electrode was large, and it was recognized that the deterioration progressed significantly at the positive electrode.

  As mentioned above, according to this invention, it turns out that the internal short circuit by the expansion | swelling of the negative electrode active material which progresses especially by progress of a charging / discharging cycle, and the fall of the discharge capacity by this can be suppressed.

  In this invention, since an internal short circuit can be suppressed by a charging / discharging cycle, it is very suitable for the lead storage battery of various uses including the object for cycle services.

The figure which shows the fiber mat folded in half Diagram showing electrode group Diagram showing another group of electrode plates The figure which shows the group structure of the battery B of a comparative example The figure which shows the group structure of the battery C of a comparative example. The figure which shows the group structure of the battery D of a comparative example. Figure showing cycle life test results

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Fiber mat 102 The fold (at the bottom) 103 The fold (approximately orthogonal to the fold at the bottom) 201 The zigzag separator 202 The first separator overlapping portion 203, 203 ′ The electrode plate 204 The second separator overlapping portion 205 End face 206 Electrode plate group 301 Spiral folding separator 302 First separator overlapping portion 303 End face 304 Second separator overlapping portion 305 Electrode plate group 401 Separator 402 First separator overlapping portion 404 Second separator overlapping portion 405 End surface 501 Glass fiber mat 601 Bag-shaped glass fiber mat

Claims (1)

A separator made of fiber mat is folded in two and overlapped into a V shape,
A spelling separator having an opening at the top by alternately spelling so that the fold is substantially orthogonal to the fold at the bottom,
An electrode plate of one polarity is arranged in the first separator overlapping portion where the top is open and the bottom is closed,
An electrode plate of the other polarity is arranged on either one or both of the second separator overlapped portion where both the top and bottom are opened, or the end face of the spell separator,
At least one pair of a first separator overlapping portion where no electrode plate is disposed and a second separator overlapping portion where no electrode plate is disposed is disposed between a pair of electrode plates having different polarities and facing each other. ,
At least the negative electrode plate is provided with an expanded lattice body having no frame on the side portion thereof.

Images