JP2018054521A - Secondary battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deterioration prediction method and deterioration prediction device that take into consideration variations for each battery.SOLUTION: A secondary battery module according to the present invention includes: a secondary battery; a current measurement unit that measures a current of the secondary battery; a temperature measurement unit that measures a temperature of the secondary battery; a timer that clocks a time; and a calculation unit that calculates an integration amount of a current time of the secondary battery and a use SOC range from the measured current and the time clocked by the timer. In the secondary battery module, the calculation unit calculates an integration amount of a current time within a first temperature range and second temperature range in a prescribed SOC range, converts the integration amount of the current time within the first temperature range into an integration amount of a current time within the second temperature range, and calculates a total deterioration rate using a value obtained by summing up the integration amount of the current time within the second temperature range and the converted integration amount of the current time.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a deterioration estimation method and a deterioration estimation device in a secondary battery module used as a power source for automobiles, for example.

  In recent years, lithium ion secondary batteries have been used as power sources for electric vehicles and hybrid vehicles. Lithium ion secondary batteries for automobiles are required to have high output, high energy density, and long life.

  Moreover, there is an idea that a lithium ion secondary battery can be used for a long life from the viewpoint of control. Therefore, it is also required to accurately grasp the deterioration state of the lithium ion secondary battery and appropriately control based on the deterioration state.

  In order to solve the above problems, Patent Document 1 discloses an estimation method for estimating a deterioration state of a secondary battery used.

Japanese Patent No. 5466564

  Patent Document 1 estimates the deterioration state of a battery by converting use conditions subdivided by temperature and state of charge (SOC) into a single reference deterioration mode.

  However, in the method of Patent Document 1, conditions that do not assume actual traveling are used as the reference deterioration mode, and therefore, deterioration prediction that takes into account variations among batteries is not performed.

  Therefore, an object of the present invention is to solve the above problems. Specifically, it is an object to provide a deterioration prediction method and a deterioration prediction apparatus that take into account variations among batteries.

In order to solve the above problems, the secondary battery module according to the present invention includes a secondary battery, a current measurement unit that measures the current of the secondary battery, a temperature measurement unit that measures the temperature of the secondary battery, and a time. A secondary battery module comprising: a timer for measuring the current, and a calculation unit for calculating a current-time integrated amount and a used SOC range of the secondary battery from the measured current and the time by the timer. , Calculating the current time integrated amount in the first temperature range and the second temperature range in the predetermined SOC range, and converting the current time integrated amount in the first temperature range into the current time integrated amount in the second temperature range And
The total deterioration rate is calculated using a value obtained by adding the current time integrated amount in the second temperature range and the converted current time integrated amount.

  Moreover, the secondary battery module in the present invention lowers the upper limit value of the used SOC range when the secondary battery, the measurement unit for measuring the voltage of the secondary battery, and the measured voltage exceed a predetermined voltage value.

  According to the present invention, since it is possible to predict deterioration without going through a reference deterioration mode that does not assume actual traveling, it is possible to perform more accurate deterioration prediction.

External perspective view of prismatic secondary battery Exploded perspective view of prismatic secondary battery Exploded perspective view of wound electrode group The block conceptual diagram of the secondary battery module 1 which concerns on this embodiment. Current accumulated amount classification table corresponding to temperature-SOC of this embodiment Cycle characteristic diagram corresponding to the classification table of this embodiment Control flowchart of this embodiment Diagram explaining the method of repeated calculation Method for calculating total deterioration rate using FIG.

Example 1 will be described below.

  FIG. 1 is an external perspective view of a prismatic secondary battery 100 according to the present embodiment.

  The prismatic secondary battery 100 includes a battery can 1 and a lid (battery lid) 6. The battery can 1 has a side surface and a bottom surface having a pair of opposed wide surfaces with a relatively large area and a pair of opposed narrow surfaces with a relatively small area, and has an opening 1a above it.

  A wound group 3 is accommodated in the battery can 1, and an opening 1 a of the battery can 1 is sealed by a battery lid 6. The battery lid 6 has a substantially rectangular flat plate shape and is welded so as to close the upper opening 1 a of the battery can 1 to seal the battery can 1. The battery lid 6 is provided with a positive external terminal 8A and a negative external terminal 8B. The wound group 3 is charged via the positive external terminal 8A and the negative external terminal 8B, and power is supplied to the external load. The battery cover 6 is integrally provided with a gas discharge valve 10, and when the pressure in the battery container rises, the gas discharge valve 10 opens to discharge gas from the inside, and the pressure in the battery container is reduced. Thereby, the safety of the square secondary battery C1 is ensured.

  FIG. 2 is an exploded perspective view of the prismatic secondary battery.

  The battery can 1 of the prismatic secondary battery C1 has a rectangular bottom surface 22, a rectangular tubular side surface 21 rising from the bottom surface 22, and an opening 1a opened upward at the upper end of the side surface 21. . A wound group 3 is accommodated in the battery can 1 via an insulating protective film 2.

  Since the wound group 3 is wound in a flat shape, the wound group 3 has a pair of opposed curved portions having a semicircular cross section and a flat portion formed continuously between the pair of curved portions. ing. The winding group 3 is inserted into the battery can 1 from one curved portion side so that the winding axis direction is along the lateral width direction of the battery can 1, and the other curved portion side is disposed on the upper opening side.

  The positive electrode foil exposed portion 31c of the wound group 3 is electrically connected to a positive external terminal 8A provided on the battery lid 6 via a positive current collector (current collector terminal) 4A. Further, the negative electrode foil exposed portion 32c of the wound group 3 is electrically connected to a negative external terminal 8B provided on the battery lid 6 via a negative current collector (current collector terminal) 4B. As a result, power is supplied from the wound group 3 to the external load via the positive current collector plate 4A and the negative current collector plate 4B, and externally supplied to the wound group 3 via the positive current collector plate 4A and the negative current collector plate 4B. The generated power is supplied and charged.

  In order to electrically insulate the positive electrode current collector plate 4A and the negative electrode current collector plate 4B, and the positive electrode external terminal 8A and the negative electrode external terminal 8B from the battery lid 6, respectively, a gasket 5 and an insulating plate 7 are provided on the battery lid 6. It has been. Moreover, after injecting electrolyte solution into the battery can 1 from the injection hole 9, the injection stopper 11 is joined to the battery cover 6 by laser welding to seal the injection hole 9, and the rectangular secondary battery C1 is sealed. To do.

Here, examples of the material for forming the positive electrode external terminal 8A and the positive electrode current collector plate 4A include an aluminum alloy, and examples of the material for forming the negative electrode external terminal 8B and the negative electrode current collector plate 4B include a copper alloy. Examples of the material for forming the insulating plate 7 and the gasket 5 include resin materials having insulating properties such as polybutylene terephthalate, polyphenylene sulfide, and perfluoroalkoxy fluororesin.

Further, the battery lid 6 is provided with a liquid injection hole 9 for injecting an electrolytic solution into the battery container. The liquid injection hole 9 is an injection stopper after the electrolytic solution is injected into the battery container. 11 is sealed. Here, as the electrolytic solution injected into the battery container, for example, a non-aqueous electrolytic solution in which a lithium salt such as lithium hexafluorophosphate (LiPF ₆ ) is dissolved in a carbonic acid ester-based organic solvent such as ethylene carbonate is used. Can be applied.

  The positive external terminal 8A and the negative external terminal 8B have a weld joint that is welded to a bus bar or the like. The weld joint has a rectangular parallelepiped block shape protruding upward from the battery lid 6, and has a configuration in which the lower surface faces the surface of the battery lid 6 and the upper surface is parallel to the battery lid 6 at a predetermined height position. Have.

  The positive electrode connecting portion 12A and the negative electrode connecting portion 12B have cylindrical shapes that protrude from the lower surfaces of the positive electrode external terminal 8A and the negative electrode external terminal 8B, respectively, and the tips can be inserted into the positive electrode side through hole 6A and the negative electrode side through hole 6B. Have. 12 A of positive electrode connection parts and the negative electrode connection part 12B penetrate the battery cover 6, and are inside of the battery can 1 rather than the positive electrode current collecting plate base 41A of the positive electrode current collecting plate 4A and the negative electrode current collecting plate 4B, and the negative electrode current collecting plate base 41B. The positive electrode external terminal 8 </ b> A, the negative electrode external terminal 8 </ b> B, the positive electrode current collector plate 4 </ b> A, and the negative electrode current collector plate 4 </ b> B are integrally fixed to the battery lid 6. A gasket 5 is interposed between the positive electrode external terminal 8A, the negative electrode external terminal 8B, and the battery cover 6, and an insulating plate is interposed between the positive electrode current collector plate 4A, the negative electrode current collector plate 4B, and the battery cover 6. 7 is interposed.

  The positive electrode current collector plate 4A and the negative electrode current collector plate 4B are a rectangular plate-shaped positive electrode current collector plate base 41A, a negative electrode current collector plate base 41B, and a positive electrode current collector plate base 41A, which are arranged to face the lower surface of the battery lid 6. The negative electrode current collector base 41B is bent at the side end and extends toward the bottom surface along the wide surface of the battery can 1 to form the positive electrode foil connection portion 31d and the negative electrode foil connection portion 32d of the wound group 3. It has a positive electrode side connection end portion 42A and a negative electrode side connection end portion 42B which are connected in a state of being overlapped facing each other. The positive electrode collector plate base 41A and the negative electrode collector plate base 41B are respectively formed with a positive electrode side opening hole 43A and a negative electrode side opening hole 43B through which the positive electrode connecting part 12A and the negative electrode connecting part 12B are inserted.

The insulating protective film 2 is wound around the winding group 3 with the direction along the flat plane of the winding group 3 and the direction perpendicular to the winding axis direction of the winding group 3 as the central axis direction. The insulating protective film 2 is made of a single sheet or a plurality of film members made of synthetic resin such as PP (polypropylene), for example, and is a direction parallel to the flat surface of the wound group 3 and perpendicular to the winding axis direction. Has a length that can be wound around the winding center.

  FIG. 3 is an exploded perspective view showing a state in which a part of the wound electrode group is developed.

  The winding group 3 is configured by winding the negative electrode 32 and the positive electrode 31 in a flat shape with a separator 33 therebetween. In the winding group 3, the outermost electrode is the negative electrode 32, and the separator 33 is wound outside thereof. The separator 33 has a role of insulating between the positive electrode 31 and the negative electrode 32.

  The portion of the negative electrode 32 to which the negative electrode mixture 32b is applied is larger in the width direction than the portion of the positive electrode 31 to which the positive electrode mixture 31b is applied. It is comprised so that it may be pinched | interposed into the part to which the mixture 32b was apply | coated. The positive foil exposed portion 31c and the negative foil exposed portion 32c are bundled at a plane portion and connected by welding or the like. The separator 33 is wider than the portion where the negative electrode mixture 32b is applied in the width direction, but is wound to a position where the metal foil surface at the end is exposed at the positive electrode foil exposed portion 31c and the negative electrode foil exposed portion 32c. Therefore, it does not hinder the welding when bundled.

  The positive electrode 31 has a positive electrode active material mixture on both surfaces of a positive electrode foil that is a positive electrode current collector, and a positive electrode foil in which the positive electrode active material mixture is not applied to one end in the width direction of the positive electrode foil An exposed portion 31c is provided.

  The negative electrode 32 has a negative electrode active material mixture on both sides of a negative electrode foil that is a negative electrode current collector, and the negative electrode foil in which the negative electrode active material mixture is not applied to the other end in the width direction of the positive electrode foil An exposed portion 32c is provided. The positive foil exposed portion 31c and the negative foil exposed portion 32c are regions where the metal surface of the electrode foil is exposed, and are wound so as to be disposed at one side and the other side in the winding axis direction.

  Regarding the negative electrode 32, 10 parts by weight of polyvinylidene fluoride (hereinafter referred to as PVDF) is added as a binder to 100 parts by weight of amorphous carbon powder as a negative electrode active material, and N as a dispersion solvent. -A negative electrode mixture in which methylpyrrolidone (hereinafter referred to as NMP) was added and kneaded was prepared. This negative electrode mixture was applied to both surfaces of a 10 μm thick copper foil (negative electrode electrode foil) leaving a welded portion (negative electrode uncoated portion). Then, the negative electrode 32 with a negative electrode active material application part thickness of 70 micrometers which does not contain copper foil was obtained through drying, a press, and a cutting process.

  In this embodiment, the case where amorphous carbon is used as the negative electrode active material is exemplified, but the present invention is not limited to this. Natural graphite capable of inserting and removing lithium ions and various artificial graphite materials Carbonaceous materials such as coke, compounds such as Si and Sn (for example, SiO, TiSi2 etc.), or composite materials thereof may be used, and the particle shape is particularly limited, such as scaly, spherical, fibrous, or massive Is not to be done.

  As for the positive electrode 31, 10 parts by weight of flaky graphite as a conductive material and 10 parts by weight of PVDF as a binder are added to 100 parts by weight of lithium manganate (chemical formula LiMn 2 O 4) as a positive electrode active material. A positive electrode mixture in which NMP was added and kneaded as a dispersion solvent was prepared. This positive electrode mixture was applied to both surfaces of an aluminum foil (positive electrode foil) having a thickness of 20 μm leaving a welded portion (positive electrode uncoated portion). Thereafter, a positive electrode 31 having a thickness of 90 μm in the thickness of the positive electrode active material coating portion not including an aluminum foil was obtained through drying, pressing, and cutting processes.

  Further, in the present embodiment, the case where lithium manganate is used as the positive electrode active material is exemplified, but other lithium manganate having a spinel crystal structure or a lithium manganese composite oxide or layered in which a part is substituted or doped with a metal element A lithium cobalt oxide or lithium titanate having a crystal structure, or a lithium-metal composite oxide obtained by substituting or doping a part thereof with a metal element may be used.

Moreover, in this embodiment, although the case where PVDF was used as a binder of the coating part in a positive electrode and a negative electrode was illustrated, polytetrafluoroethylene (PTFE), polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, styrene Use polymers such as butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethyl cellulose, various latexes, acrylonitrile, vinyl fluoride, vinylidene fluoride, propylene fluoride, chloroprene fluoride, acrylic resins, and mixtures thereof. Moreover, as a shaft core, what was comprised by winding the resin sheet whose bending rigidity is higher than any of the positive electrode foil 31a, the negative electrode foil 32a, and the separator 33 can be used, for example.

  Then, the block conceptual diagram of the secondary battery module 101 which concerns on this embodiment is demonstrated using FIG. The secondary battery module 101 of the present embodiment includes a plurality of prismatic secondary batteries 100 connected in series and includes a control circuit such as the arithmetic unit 107. Connected to the series circuit is a current measuring means 104, which detects the current flowing through the series circuit.

  Then, the current information detected by the current measuring unit 104 is transmitted to the calculation unit 107. On the other hand, voltage measuring means 103 is provided in parallel with the series circuit. The voltage information measured by the voltage detection means 103 is also output to the calculation unit 107.

  Further, the temperature information of the square secondary battery 100 and the time information output from the timer 6 are input to the calculation unit 107. Then, the calculation unit 107 calculates the SOC from these pieces of information, and records the values so as to be associated with the current time integrated total value division table 108. By adopting such a method, actual data of the currently used prismatic secondary battery 100 is accumulated.

  FIG. 5 is a table associating the temperature with the SOC range, and the current time integrated amount is stored in each table. This data is stored as A1, A2, A3, B1, B2,... C3 in a storage unit (not shown) stored in the battery controller. In the present embodiment, description will be made using a 3 × 3 matrix. However, as the number of matrices increases, more accurate deterioration prediction becomes possible. On the other hand, the smaller the number of matrices, there is also an advantage that the calculation load is reduced.

  Further, in the present embodiment, there is an approximate expression of a deterioration curve corresponding to each temperature-SOC range as shown in FIG. Therefore, control as shown in FIG. 7 can be performed, and deterioration can be predicted without going through a reference deterioration mode that does not assume actual traveling. Therefore, more accurate deterioration prediction can be performed.

  Next, the control method of this embodiment will be described with reference to FIG.

  First, in step S1, the deterioration rate is calculated using an approximate expression of a deterioration curve from the current-time integrated amount of A1 in the SOC range of 0 to 30% and the temperature of −30 to 25 ° C.

  Then, in step S2, a current-time integrated amount X1 corresponding to the deterioration amount calculated in step S1 is calculated from an approximate expression of a deterioration curve with an SOC range of 0 to 30% and a temperature of 25 to 45 ° C.

  Thereafter, in step S3, the current time integrated amount X1 calculated in step S2 is added to the SOC range 0 to 30%, and the current time integrated amount A2 at a temperature of 25 to 45 ° C., and the SOC range 0 to 30%, the temperature 25 to 25%. A deterioration rate is calculated from an approximate expression of a deterioration curve at 50 ° C.

  Finally, as described in step S4, the current time integrated amount C3 at the SOC range of 50 to 100% and the temperature of 45 to 60 ° C. is added to the current time integrated amount X8 calculated by repetitive calculation, and the SOC range 50 The total deterioration rate is calculated from the approximate expression of the deterioration curve at ˜100% and the temperature of 45-60 ° C.

  FIG. 8 is a diagram showing a repeated calculation order. In this embodiment, the calculation is performed in the order of A1, A2, and A3, and then the calculation is performed in the order of B1, B2, B3, and finally C1, C2, and C3. On the other hand, if it is within the same SOC range, it is not necessary to be particular about the calculation order, and it may be calculated in order from B1 instead of calculating in order from A1, or may be calculated in advance from C1.

  FIG. 9 is a diagram visually showing calculation of C2 to C3 in FIG. Thus, the final total deterioration rate is calculated by converting the deterioration rate at C2 into the current time integrated amount X8 of the deterioration equation corresponding to C3, and further adding C3 and substituting it into the deterioration equation. It will be.

  By controlling as described above, it is possible to predict deterioration without going through a reference deterioration mode that does not assume actual traveling. Therefore, it becomes possible to perform more accurate deterioration prediction.

  The first embodiment will be briefly summarized. The degradation prediction apparatus according to the present invention includes a secondary battery, a voltage measurement unit that measures the voltage of the secondary battery, a current measurement unit that measures the current of the secondary battery, and a secondary current based on the measured current and voltage. In the deterioration prediction apparatus having a calculation unit that calculates the current time integrated amount of the battery and the used SOC range, the calculation unit calculates the current time integrated amount in the first temperature range and the second temperature range in the predetermined SOC range. The value obtained by converting the current time integrated amount in the first temperature range into the current time integrated amount in the second temperature range, and adding the current time integrated amount in the second temperature range and the converted current time integrated amount. The total deterioration rate is calculated using By adopting such a configuration, it is possible to predict deterioration without going through a reference deterioration mode that does not assume actual traveling. Therefore, it becomes possible to perform more accurate deterioration prediction.

DESCRIPTION OF SYMBOLS 1 ... Battery can, 1a ... Opening part, 2 ... Insulating protective film, 3 ... Winding group, 4A ... Positive electrode collector plate, 4B ... Negative electrode collector plate, 5 ... Gasket, 6 ... Battery cover, 6A ... Positive electrode side penetration Hole, 6B ... negative electrode side through-hole, 7 ... insulating plate, 8A ... positive electrode external terminal, 8B ... negative electrode external terminal, 9 ... injection port, 10 ... gas discharge valve, 11 ... injection plug, 12A ... positive electrode connection part, 12B ... Negative electrode connection part, 21 ... Side face, 22 ... Bottom face, 31 ... Positive electrode, 31a ... Positive electrode foil, 31b ... Positive electrode mixture, 31c ... Positive electrode foil exposed part, 32 ... Negative electrode, 32a ... Negative electrode foil, 32b ... Negative electrode Mixture, 32c ... negative electrode foil exposed portion, 31d ... positive electrode foil connecting portion, 32d ... negative electrode foil connecting portion, 33 ... separator, 100 ... square secondary battery, 101 ... secondary battery module, 103 ... voltage measuring means, 104 ... Current measuring means, 107 ... calculation unit, 108 ... table

Claims (2)

A secondary battery,
A current measuring unit for measuring the current of the secondary battery;
A temperature measuring unit for measuring the temperature of the secondary battery;
A timer to measure time,
In the secondary battery module, comprising: an arithmetic unit that calculates a current time integrated amount and a used SOC range of the secondary battery from the measured current and the time by the timer.
The computing unit is
The current time integrated amount in the first temperature range and the second temperature range in the predetermined SOC range is calculated, and the current time integrated amount in the first temperature range is converted into the current time integrated amount in the second temperature range. ,
The secondary battery module which calculates a total deterioration rate using the value which added the current time integrated amount in said 2nd temperature range and the converted said current time integrated amount. The secondary battery module according to claim 1,
A secondary battery module that includes a voltage measurement unit that measures the voltage of the secondary battery, and lowers an upper limit value of a use SOC range when a predetermined voltage value is exceeded.

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