JP2012138295A - Secondary battery and method for reusing secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply detect the inner pressure rise of a secondary battery.SOLUTION: A plurality of thin wall parts 16a, 16b, 16c are provided in a lid part 14 of the secondary battery 10. Respective thin wall parts 16a, 16b, 16c are in a concave state in an initial state, and changed to a convex state from a concave state having respectively different thresholds in accordance with the inner pressure rise of the secondary battery 10. Appreciation of the inner pressure depends on whether any one of the thin wall parts 16a, 16b, 16c is in the convex state without decomposing the secondary battery 10.

Description

  The present invention relates to a secondary battery and a method for reusing a secondary battery, and more particularly to detection of internal pressure of a secondary battery.

  Conventionally, a technique for detecting an increase in internal pressure of a secondary battery (pressure per unit area due to gas inside a battery case) has been proposed.

  For example, in Patent Document 1 below, in a secondary battery including a battery outer can containing a power generation element composed of a positive electrode plate, a negative electrode plate, a separator and an electrolyte, and a lid sealing the outer can, the side surface of the outer can It is disclosed that a strain sensor for detecting a change in volume of a battery outer can by increasing a battery internal pressure is mounted at least on a part of the recess.

  In Patent Document 2, a conductive path is formed between the battery lid and the heating element inside the battery via the diaphragm portion and the lead, and the diaphragm portion is displaced when the internal pressure of the battery case rises to a predetermined value or more. Further, it is disclosed that the diaphragm portion and the lead are separated by the displacement of the diaphragm portion, and the conductive path is interrupted.

JP 2000-173676 A JP 2000-90960 A

  However, in the prior art, the detection of whether or not the internal pressure of the secondary battery has risen above the threshold value is limited to binary detection, and the continuous change in the internal pressure of the secondary battery is visually detected. There is a problem that cannot be easily grasped.

  In particular, recently, as typified by hybrid vehicles and electric vehicles, an assembled battery composed of a secondary battery is often mounted as a driving power on a mobile body, and as a result, the assembled battery collected from the user. There is also an increasing demand for reconfiguring a battery into a battery pack having reusable performance. In order to perform rebuilding efficiently, it is indispensable to grasp the characteristics and deterioration state of the secondary battery to be rebuilt, and it is extremely important to grasp the internal pressure history of the secondary battery.

  An object of the present invention is to provide a technique capable of easily grasping an internal pressure history of a secondary battery by visually recognizing the external battery without disassembling the secondary battery, and a reuse technique using the same. .

  The present invention includes a case that accommodates an electrode plate and an electrolytic solution, and at least first and second deformation portions that are formed in the case and each indicate a different degree of deformation with respect to the internal pressure of the secondary battery. And

  In one embodiment of the present invention, the first and second deformed portions are both concave toward the inner side of the secondary battery in the initial state, and the internal pressure of the secondary battery increases. The first and second deformed portions are deformed so as to form a convex state from the concave state toward the outer side of the secondary battery, and the first and second deformed portions are subjected to internal pressure when changing from the concave state to the convex state. The threshold is different.

  The present invention is also a method for reusing a secondary battery, wherein the secondary battery is formed in a case containing an electrode plate and an electrolyte, and the case, each of which is different from the internal pressure of the secondary battery. At least first and second deformable portions that indicate the degree of the above, and ranking the secondary batteries according to at least the degree of deformation of the first and second deformable portions; And a step of reusing the secondary battery according to the method.

  According to the present invention, the internal pressure can be evaluated only by visually recognizing the appearance without disassembling the secondary battery. Moreover, the reuse of the secondary battery is facilitated by evaluating the internal pressure and ranking it.

It is an external appearance perspective view of the secondary battery of an embodiment. It is a top view of the secondary battery of an embodiment. It is sectional drawing of the cover part of the secondary battery of embodiment. It is a graph which shows the internal pressure of a thin part, and the degree of a deformation | transformation. It is typical explanatory drawing which shows a deformation | transformation of the thin part accompanying a raise of internal pressure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an external perspective view of the secondary battery 10 in the present embodiment. FIG. 2 shows a plan view of the secondary battery 10.

  The secondary battery 10 includes an electrode plate group, a rectangular parallelepiped integrated battery case 12 containing an electrolytic solution and integrally molded with a resin, and a resinous lid portion 14 that seals the opening of the integrated battery case 12. . The electrode plate group is composed of a laminate in which a positive electrode plate, a negative electrode plate, and a separator are laminated. The electrode plate group is accommodated in the integrated battery case 12 while being joined to the positive electrode current collector plate and the negative electrode current collector plate. Although not shown, a positive external terminal is provided at one end of the integrated battery case 12, and a negative external terminal is provided at the other end. The positive external terminal is connected to the positive current collector through the through hole, and the negative external terminal is similarly connected to the negative current collector through the through hole. The integrated battery case 12 and the lid part 14 in this embodiment are combined to form a case.

  On the lid portion 14 of the secondary battery 10, at least two thin portions 16 as deformed portions are formed at substantially equal intervals along the longitudinal direction of the secondary battery 10. The thin portion 16 is a portion in which the thickness of the lid portion 16 is thinner than the other portions, and the planar shape thereof is formed in a circular shape as shown in the plan view of FIG. In the drawing, three thin portions 16a, 16b, and 16c are formed in the longitudinal direction of the secondary battery 10, and in the initial state, these thin portions 16a, 16b, and 16c are formed inside the lid portion 14. It is in a depressed concave state.

  FIG. 3 shows a cross-sectional view of the lid portion 14. As can be seen from the figure, the thin-walled portions 16 a, 16 b, and 16 c are relatively thinner than the other portions, and are recessed toward the inside of the secondary battery 10. However, the thin portions 16a, 16b, and 16c are not the same, and the thickness, the size, and the shape are different from each other. That is, since the thin portions 16a, 16b, and 16c are all concave toward the inside of the secondary battery and the internal pressure of the secondary battery 10 is directly applied, the internal pressure increases. The thin portions 16a, 16b, and 16c are also deformed by the influence of the internal pressure, but the degree of deformation with respect to the internal pressure is different, and more specifically, the threshold values of the internal pressure are different from each other.

  FIG. 4 shows the relationship between the internal pressure of the secondary battery 10 and the deformation of the thin portion 16 in the present embodiment. In the figure, the horizontal axis represents the internal pressure P of the secondary battery 10. Further, the vertical axis indicates the state of deformation, the minus indicates that it is concave toward the inside of the secondary battery 10, and the plus is that it is convex toward the outside of the secondary battery 10. Indicates. The thin-walled portion 16 is deformed negatively in the initial state, that is, in a concave state, but deforms toward the outside of the secondary battery 10 as the internal pressure increases, and eventually changes from a concave state to a convex state through a flat state. It should be noted that once the concave state is reversed and the convex state is reached, the concave state is not normally restored unless a pressure of a certain level or more is applied.

  When the internal pressure of the secondary battery 10 rises from the initial state to Pa and becomes thin, the thin-walled portion 16a changes from a concave state to a flat state. It protrudes from the surface of the part 14.

  The thin-walled portion 16b becomes concave or flat when the internal pressure of the secondary battery 10 rises from the initial state to Pb (where Pb> Pa), and is positive, that is, convex when the internal pressure exceeds Pb. In appearance, it protrudes from the surface of the lid 14.

  The thin portion 16c is flattened from the concave state when the internal pressure of the secondary battery 10 rises from the initial state to Pc (where Pc> Pb), and when the internal pressure exceeds Pc, it is positive, that is, the convex state. In appearance, it protrudes from the surface of the lid portion 14.

  As described above, the thin-walled portions 16a, 16b, and 16c are different from Pa, Pb, and Pc in internal pressure threshold values for transition from the concave state to the convex state. Since the thin-walled portion 10 of the present embodiment does not normally return to the concave state once it is in the convex state, the value (internal pressure history) when the internal pressure increases most by visually checking the state of the thin-walled portions 16a, 16b, 16c. ) Can be easily grasped.

  That is, when all of the thin portions 16a, 16b, and 16c remain in the concave state, the internal pressure of the secondary battery 10 reaches only less than Pa.

  Moreover, when only the thin part 16a is flat and the thin parts 16b and 16c remain in a concave state, the internal pressure of the secondary battery 10 has reached Pa.

  Moreover, when only the thin part 16a is a convex state and the thin parts 16b and 16c remain a concave state, the internal pressure of the secondary battery 10 has reached Pa or more and less than Pb.

  Moreover, when the thin part 16a is a convex state, the thin part 16b is a flat state, and the thin part 16c is a concave state, the internal pressure of the secondary battery 10 has reached Pb.

  When the thin portions 16a and 16b are convex and the thin portion 16c is concave, the internal pressure of the secondary battery 10 has reached Pb or more and less than Pc.

  Further, when the thin portions 16a and 16b are in a convex state and the thin portion 16c is in a flat state, the internal pressure of the secondary battery 10 has reached Pc.

  Furthermore, when all of the thin portions 16a, 16b, and 16c are in a convex state, the internal pressure of the secondary battery 10 exceeds Pc.

  In order to change the internal pressure threshold value at which the deformation of the thin-walled portions 16a, 16b, and 16c changes from the concave state to the convex state, for example, the thickness of the thin-walled portions 16a, 16b, and 16c may be changed. If the thicknesses of 16a, 16b, and 16c are ta, tb, and tc, respectively, ta <tb <tc and so on. However, since the thin-walled portions 16a, 16b, and 16c are formed in the lid portion 14, it is needless to say that the thin-walled portions 16a, 16b, and 16c need to have a thickness and strength that can function as the lid portion 14.

  Of course, since the mechanical strength of the thin-walled portion 16 is also limited, it is assumed that the thin-walled portion 16 is destroyed when the internal pressure of the secondary battery 10 rises above a certain value. Even in this case, since the limit strengths of the thin portions 16a, 16b, and 16c are different, the internal pressure history of the secondary battery 10 can be obtained by visually observing which of the thin portions 16a, 16b, and 16c is destroyed. I can grasp it. For example, when the thin portion 16a is destroyed among the thin portions 16a, 16b, and 16c, the internal pressure of the secondary battery 10 is higher than the critical internal pressure of the thin portion 16a and lower than the critical internal pressure of the thin portion 16b. I can understand what happened. The smallest value among the critical internal pressures of the thin-walled portions 16a, 16b, and 16c is set in a range in which excessive expansion or destruction does not occur in order to prevent excessive expansion or destruction of the integrated battery case 12 due to an increase in internal pressure. It is desirable to do.

  FIG. 5 schematically shows the relationship between the state of the thin portions 16a, 16b and 16c formed on the lid portion 14 in the present embodiment and the internal pressure. It shows that the internal pressure of the secondary battery 10 increases in the order of FIGS. 5 (a), 5 (b), 5 (c), and 5 (d).

FIG. 5A shows a state in which the internal pressure of the secondary battery 10 is the lowest, and all of the thin portions 16a, 16b, and 16c are concave. When Pa = 0.15 (Pascal), Pb = 0.30 (Pascal), and Pc = 0.45 (Pascal), the internal pressure P of the secondary battery 10 is
P <0.15
Means that

FIG. 5B shows a state in which the internal pressure of the secondary battery 10 has increased, the thin portion 16a is in a convex state, and the thin portions 16b and 16c remain in a concave state. The internal pressure P of the secondary battery 10 is
0.15 ≦ P <0.30
Means that

FIG. 5C shows a state in which the internal pressure of the secondary battery 10 is further increased, and the thin portions 16a and 16b are in a convex state and the thin portion 16c is in a concave state. The internal pressure P of the secondary battery 10 is
0.30 ≦ P <0.45
Means that

FIG. 5D shows a state in which the internal pressure of the secondary battery 10 is further increased, and the thin portions 16a, 16b, and 16c are all convex. The internal pressure P of the secondary battery 10 is
0.45 <P
Means that

FIG. 5E shows a state where the internal pressure of the secondary battery 10 is further increased and the thin portion 16a is broken. When the critical internal pressure of the thin-walled portion 16a, that is, the internal pressure leading to fracture is 0.5 (pascal), the internal pressure P of the secondary battery 10 is
P> 0.50
Means that

As described above, the internal pressure history of the secondary battery 10 can be grasped without disassembling the secondary battery 10 by visually recognizing the external shape of the thin portions 16a, 16b, and 16c. The internal pressure of the secondary battery 10 is known to increase due to various factors. Specifically,
(1) When the state of charge (SOC) of the secondary battery 10 is high (2) When the regenerative current is relatively large when mounted on the vehicle (3) When the ambient pressure is small (4) When overdischarged, etc. The internal pressure increases. Therefore, when the internal pressure history is increasing, it can be determined that the secondary battery 10 has any of these histories. In addition, the internal pressure of the secondary battery 10 is closely related to the life of the secondary battery 10, and there is a negative correlation between the internal pressure history and the life of the secondary battery 10, that is, the higher the internal pressure, the shorter the life. It is known. For example, it is known that a secondary battery that is more overcharged has a higher internal pressure and a shorter life than a secondary battery that is less overcharged.

  Therefore, after recognizing the internal pressure of the secondary battery 10 according to the present embodiment, when the secondary battery 10 is reused, the lifetime of the secondary battery 10 can be evaluated according to the grasped internal pressure.

  For example, when a secondary battery that has been used once is used to newly form an assembled battery composed of a plurality of secondary batteries 10, the battery is ranked into five ranks A to E according to the life of the secondary battery 10. Specifically, the secondary battery 10 in the state of FIG. 5A has the lowest internal pressure and the longest life, and the secondary battery 10 in the state of FIG. Rank B is assumed to be low and the life is relatively long, and the secondary battery 10 in the state of FIG. In the state shown in FIG. 5 (e), the thin portion 16a is broken, so that it is not reused.

  After ranking as described above, only the secondary batteries 10 ranked as rank A are collected to form a new assembled battery, or the same number of ranks A and B are collected to form a new assembled battery. .

  According to the present embodiment, the secondary battery 10 collected from the market is not disassembled, and only the appearance inspection is performed to rank the secondary battery 10 according to the life of the secondary battery 10 and reassemble the assembled battery according to the rank classification. Configuration is possible.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this, A various deformation | transformation is possible.

  For example, in the present embodiment, the three thin portions 16 are provided, but the present invention is not limited to this, and a plurality of thin portions 16 can be provided. Further, the planar shape is not limited to a circle, and may be any shape such as an ellipse or a rectangle. Further, in order to adjust the degree of deformation of the thin portion with respect to the internal pressure, the thin portion may be cut.

  Moreover, in this embodiment, although the case where one single battery (cell) was fundamentally accommodated in the integrated battery case 12 was illustrated, the several single cell in the integrated battery case 12 mutually connected via the partition. The present invention may also be applied to a battery module that is housed and electrically connected via a through hole. In this case, the thin portion 16 can be provided for each of the plurality of single cells. For example, in the case of a battery module that accommodates six unit cells, a total of six thin portions 16 are formed in the lid portion 14 so as to correspond to each of the six unit cells. In addition, the movement of gas may be interrupted | blocked by the partition between adjacent single cells, and you may communicate by a communicating hole etc. When the movement of the gas is blocked by the partition walls, the internal pressure of the secondary battery may be estimated on the assumption that the internal pressures are substantially the same because the respective cells are in the same usage situation. Moreover, you may provide a some thin part with respect to one single cell.

  Moreover, in the said embodiment, although the thin part was provided in the cover part 14, you may provide a thin part other than the cover part 14. FIG. Moreover, in the said embodiment, although the thin part is used as a deformation | transformation part, if it deform | transforms with an internal pressure, it will not be restricted to a thin part. For example, the material may be deformed by using an easily deformable material.

  Furthermore, in the present embodiment, the thin portion 16 is provided as a member whose state changes according to the internal pressure of the secondary battery 10, but the thin portion 16 is not necessarily limited to the thin portion, and the strength of the resin of the lid portion 14 is high. Alternatively, different resins may be used. In the above embodiment, the thin portion is not deformed (becomes a convex state) and then does not return to the original state (recessed state). You may make it return. Thereby, the present internal pressure of the secondary battery can be known.

  10 Secondary battery, 12 Integrated battery case, 14 Lid, 16 Thin part.

Claims (3)

A case for accommodating an electrode plate and an electrolyte, and
At least first and second deformed portions formed in the case, each indicating a different degree of deformation relative to the internal pressure of the secondary battery;
A secondary battery comprising: The secondary battery according to claim 1,
The first and second deformed portions both form a concave state toward the inner side of the secondary battery in the initial state, and the secondary battery is moved from the concave state to the secondary battery as the internal pressure of the secondary battery increases. Deformed to form a convex state toward the outer side, and
The secondary battery, wherein the first and second deforming portions have different internal pressure threshold values when changing from the concave state to the convex state. A method for reusing a secondary battery,
The secondary battery is
A case for accommodating an electrode plate and an electrolyte, and
At least first and second deformed portions formed in the case, each indicating a different degree of deformation relative to the internal pressure of the secondary battery;
It is equipped with
Ranking the secondary batteries according to at least the degree of deformation of the first and second deformation parts; and
Reusing secondary batteries according to the ranking;
A method for reusing a secondary battery, comprising:

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