JP2012238522A - Assembled battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve cycle life performance in an assembled battery by preventing heat radiation performance of electric cells as well as preventing a temperature rise of a connection body in the assembled battery.SOLUTION: The assembled battery 100 which is configured that a plurality of electric cells 2 in a substantially cuboid shape are arranged closely in standing state in a predetermined direction and terminals 23A, 23B of those electric cells 2 are connected with the connection body 4 is characterized in that a protruding part 211 that is formed on at least one lateral surface of a battery case 21 of the adjacent electric cells 2 and extends along a standing direction and the connection body 4 is located above a heat radiation space S formed by the protruding part 211 between the adjacent electric cells 2.

Description

  The present invention relates to an assembled battery configured by using a plurality of lead storage batteries, for example.

  Conventionally, for example, when charging / discharging a lead storage battery, a temperature rise of the lead storage battery due to heat generation during charging / discharging has been a problem. At the time of discharging the lead storage battery, heat generation due to Joule heat caused by internal resistance and polarization of the lead storage battery can be considered. On the other hand, when charging a lead storage battery, Joule heat resulting from internal resistance and polarization of the lead storage battery and heat generation due to water electrolysis can be considered.

  In the case of configuring an assembled battery by using a lead storage battery having such characteristics as a single battery, each lead storage battery (especially a battery case) is arranged without any gap from the viewpoint of making the installation space of the assembled battery compact. Since it becomes difficult to contact air, the thermal radiation performance of each lead acid battery will fall. If it does so, the temperature of each lead acid battery will rise gradually, the deterioration of a positive electrode plate (positive electrode grid corrosion and softening of a positive electrode active material) will arise, and the deterioration of a negative electrode plate (a loss of the organic expander in a negative electrode active material) There is a problem that the negative electrode active material expands) and the high-rate discharge characteristics and cycle life performance of the battery pack deteriorate.

  Here, as shown in Patent Document 1, a convex part is provided outside the battery case of the unit cell, and the convex part of the adjacent unit cell is brought into contact with each other so that air passes through the space of the concave part. A battery that dissipates heat from an assembled battery is considered.

  However, merely forming a space between the battery cells of the unit cells is not sufficient to prevent the deterioration of the high rate discharge characteristics and cycle life performance of the assembled battery. In other words, the connecting body that connects the terminals of the adjacent lead storage batteries rises in temperature due to the temperature effect of the lead storage battery and the heat generated by the internal resistance of the connecting body. The problem arises that the discharge characteristics and cycle life performance are degraded.

Japanese Unexamined Patent Publication No. 7-85847

  Therefore, the present invention has been made to solve the above-mentioned problems all at once, and prevents a decrease in the heat dissipation performance of the unit cell in the assembled battery and prevents a temperature rise of the connected body, thereby causing a high rate discharge of the assembled battery. The main problem is to improve the characteristics and cycle life performance.

  That is, the assembled battery according to the present invention is an assembled battery in which a plurality of unit cells having a substantially rectangular parallelepiped shape are closely arranged in a predetermined direction in a standing state, and the terminals of the unit cells are connected by a connecting body. A protrusion extending along the standing direction is formed on at least one outer surface of the adjacent unit cells, and the connection body is an upper part of the heat dissipation space formed between the adjacent unit cells by the protrusion. It is located in.

  In such a case, since a heat radiation space is formed between adjacent unit cells, it is possible to prevent deterioration of the heat radiation performance of each unit cell, and the connection body is located above the heat radiation space. The temperature rise of the connection body can be prevented. Thereby, the high rate discharge characteristic and cycle life performance of an assembled battery can be improved.

  In particular, the temperature rise of the assembled battery is suppressed by the connection body being located above the heat radiation space. The effect of suppressing the temperature rise of the assembled battery is that the proportion of the heat radiated downward from the surface of the connecting body is absorbed by the battery case, and the upward air generated inside the discharge space This is based on the fact that the flow of heat promotes the transfer of heat from the connection body to the air.

  Further, since the effect of suppressing the temperature rise of the assembled battery is further improved, the entire battery case including the protruding portion or the protruding portion can be composed of a polymer material to which a high thermal conductive filler is added. preferable. This is because the thermal conductivity of the protrusion is increased and the heat dissipation performance is improved. When the heat dissipation performance is improved, the amount of upward air flow is increased, and as a result, the action of cooling the connection body is promoted. A guideline for obtaining this effect is that the thermal conductivity is 0.2 W / m · K or more.

  In addition, since the effect of suppressing the temperature rise of the assembled battery is further improved, the vertical dimension of the upper opening of the heat dissipation space is the width dimension of the connection body (if the connection body cover is provided, the connection body cover It is preferable to make it larger than (width dimension). This is because it is reduced that the upward air flow generated in the discharge space is obstructed by the bottom surface of the connection body. With this configuration, the upward air flow can flow separately on one side and the other side in the width direction of the connection body, and as a result, a cooling action by air is obtained on the entire surface of the connection body. It is done.

  In the case of having an assembled battery case that accommodates a plurality of unit cells, a protrusion that extends along the vertical direction on at least one of the unit cell that contacts the side wall of the assembled battery case or the side wall of the assembled battery case Is preferably formed. If this is the case, a heat radiation space can be formed not only between adjacent unit cells but also between the assembled battery case and the unit cell, and the unit cells accommodated in the assembled battery case are suitably cooled regardless of the position. Therefore, the high rate discharge characteristics and cycle life performance of the assembled battery can be further improved.

  It is desirable to have a connection body cover that covers the connection body, and the connection body cover is made of a polymer material to which an insulating and high thermal conductive filler is added, and is located above the heat dissipation space. If this is the case, the connection body can be efficiently dissipated through the connection body cover, and since the connection body cover is located in the upper part of the heat dissipation space, the air from the heat dissipation space is directly applied to the connection body cover. It is possible to improve the heat dissipation of the connection body cover.

  According to the present invention configured as described above, it is possible to improve the high-rate discharge characteristics and cycle life performance of the assembled battery by preventing deterioration of the heat dissipation performance of the single battery in the assembled battery and preventing the temperature of the connected body from rising. Can do.

The perspective view which shows the assembled battery of this embodiment typically. The top view which shows the assembled battery of the embodiment typically. The perspective view which shows typically the lead storage battery (unit cell) of the embodiment. The side view and top view which show typically the lead storage battery (unit cell) of the same embodiment. The elements on larger scale which show the lead acid battery which adjoins the same embodiment. The figure which shows the result of having evaluated the thermal conductivity etc. of PP resin containing a boron nitride. The figure which shows the graph of transition of the cycle number and assembled battery temperature in the high rate discharge cycle life test in each assembled battery. The figure which shows the cycle number until it reaches a lifetime in the high-rate discharge cycle life test in each assembled battery. The figure which shows the assembled battery temperature graph during the height dimension of the protrusion part in each concave width sum total, and a high rate discharge cycle life test. The top view which shows typically the lead storage battery of deformation | transformation embodiment. The elements on larger scale which show the lead acid battery which adjoins of deformation | transformation embodiment.

  Hereinafter, an embodiment of an assembled battery according to the present invention will be described with reference to the drawings.

  The assembled battery 100 according to the present embodiment is used by being mounted on, for example, a transport vehicle such as an electric vehicle or a forklift vehicle, an automatic guided vehicle (AGV), and the like, as shown in FIGS. 1 and 2. As described above, a plurality of lead storage batteries 2 having a substantially rectangular parallelepiped shape are arranged in a predetermined direction in a standing state and accommodated in the assembled battery case 3, and the terminals of the lead storage batteries 2 are connected by the connection body 4. Has been.

  Specifically, as shown in FIG. 2 in particular, this includes a plurality of lead storage batteries 2 having a substantially rectangular parallelepiped shape, and the plurality of lead storage batteries 2 in a vertical direction (short direction, Y direction in FIG. 2) and a horizontal direction. An assembled battery case 3 accommodated in close proximity (longitudinal direction, X direction in FIG. 2), a connection body 4 (not shown in FIG. 1 etc.) for connecting terminals of a plurality of lead storage batteries in series, and the connection body 4 and a connecting body cover 5 that covers 4. Reference numeral 6 denotes an electric cable, and reference numeral 7 denotes a plug terminal.

  Each lead-acid battery 2 is of a monoblock type, and as shown in FIG. 3, a battery case 21 having a substantially rectangular parallelepiped shape in which an electrode plate group is accommodated, and a lid body 22 that closes an upper opening of the battery case 21. And have. A positive electrode terminal 23 </ b> A and a negative electrode terminal 23 </ b> B are provided at both ends in the longitudinal direction of the lid body 22, and a liquid injection port (not shown) for injecting an electrolytic solution into the battery case 21 is provided at the center. In this embodiment, a float liquid plug 24 having a float for confirming the liquid level is provided at the liquid injection port. The lead storage battery 2 of the present embodiment uses a liquid clad lead storage battery (2V-165Ah / 5hR) that can improve the durability of the battery and extend its life.

  The battery case 21 and the lid body 22 of the present embodiment are resin molded bodies made of a polymer material to which insulating and high thermal conductive fillers are added. Insulating and high thermal conductive fillers are, for example, boron nitride, aluminum nitride, alumina, silicon carbide, magnesia, and the like, and these fillers are added to polypropylene (PP) resin, which is a polymer material, so that the battery case 21 and the lid The body 22 is molded. The amount of filler added is 1 to 30% by volume in consideration of the moldability of the battery case 21 and the lid 22. The thermal conductivity of PP resin is 0.14 (W / m · K). When 30% by volume of boron nitride is added to PP resin, the thermal conductivity is 0.5 (W / m · K). Become. Thus, the heat dissipation of the battery case 21 and the lid body 22 itself can be improved by forming the battery case 21 and the lid body 22 from a polymer material to which an insulating and high thermal conductive filler is added.

  These lead storage batteries 2 are arranged in a state of standing in a matrix battery case 3 made of metal such as iron having a bottomed rectangular box shape with an open upper surface, and in close contact with each other in a matrix in the vertical and horizontal directions. Is done. 1 and 2 show a case in which the lead storage batteries 2 are closely arranged in four rows in the vertical direction and six rows in the horizontal direction, and the assembled battery 100 of the present embodiment includes 24 lead storage batteries connected in series. The battery voltage is 48V (lead storage battery is 2V battery).

  And the battery case 21 of each lead acid battery 2 makes the mutually same shape, and as shown in FIG.3 and FIG.4, in the four outer surface 21a-21d of the battery case 21 of each lead acid battery 2, it is a standing direction (vertical). A plurality of projecting portions 211 projecting along (direction) are formed. Specifically, out of the four outer surfaces 21a to 21d, two projecting portions 211 are formed on the short side surfaces 21a and 21b in parallel to each other from the upper end to the lower end along the standing direction at both ends thereof. The two protrusions 211 form one recess on the short side surfaces 21a and 21b. On the other hand, among the four outer surfaces 21a to 21d, the long side surfaces 21c and 21d are formed with six protruding portions 211 in parallel with each other from the upper end to the lower end along the standing direction. These six protrusions 211 form five recesses on the long side surfaces 21c and 21d. These protrusions 211 function as heat radiating fins, and can efficiently dissipate heat generated inside the battery.

  Moreover, the protrusion part 211 formed in the battery case 21 is comprised so that the cross section orthogonal to an upright direction may make a substantially rectangular shape. And the protrusion dimension (height dimension) of the protrusion part 211 is 5 mm, for example, and the sum total of the width dimension of the recessed part formed of the protrusion part 211 is the outer surface 21a-21d of the battery case 21 about the width dimension of the protrusion part 211. It is set to be 1/2 or more of the total width dimension.

  And as shown in FIG. 5, in the state which accommodated the some lead acid battery 2 in the assembled battery case 3, the front end surface of the protrusion part 211 formed in each of the short side surfaces 21a and 21b of the lead acid battery 2 adjacent to the horizontal direction While contacting each other, the front end surfaces of the protruding portions 211 formed on the long side surfaces 21c and 21d of the lead live battery 2 adjacent in the vertical direction are in contact with each other. Thereby, the thermal radiation space S extended along a perpendicular direction between the battery cases 21 of the lead storage battery 2 adjacent to a horizontal direction and a vertical direction and opened upwards is formed.

  Further, in the lead storage battery 2 that contacts the side wall of the assembled battery case 100, the protruding portion 211 formed in the battery case 21 of the lead storage battery 2 contacts the side wall of the assembled battery case 3, whereby the lead storage battery 2 and the assembled battery. A heat radiation space S extending along the vertical direction and opening upward is formed between the case 3 and the case 3. In this way, the heat radiation space S is formed between the battery cases 21 of the lead storage battery 2 adjacent in the horizontal direction and the vertical direction, and the heat radiation space S is formed between the assembled battery case 3 and the lead storage battery 2. Regardless of the storage position in the battery case 3, it is possible to prevent the heat dissipation performance of each battery 2 from being deteriorated.

  As shown in FIG. 5, the connecting body 4 electrically connects the positive terminal 23 </ b> A of one lead storage battery 2 and the negative terminal 23 </ b> B of the other lead storage battery 2 in the lead storage battery 2 adjacent in the lateral direction. It is. The connection body 4 of the present embodiment is made of metal such as lead or lead alloy, for example, and has a through hole into which one positive terminal 23A fits and a through hole into which the other negative terminal 23B fits. It joins by welding in the state which each terminal 23A and 23B fitted. An electric cable 6 is connected to a terminal to which the connection body 4 is not connected.

  The connection body cover 5 is made of a polymer material to which an insulating and high thermal conductive filler is added, and covers the upper surface and side surfaces of the connection body 4 joined to the positive terminal 23A and the negative terminal 23B. The connection body cover 5 can be adjusted in length according to the length of the connection body, and the portions covering the end portions of the connection body 4 provided with the through holes are slidable with respect to the center portion. It is configured. The insulating and high thermal conductive filler is, for example, boron nitride, aluminum nitride, alumina, silicon carbide, magnesia, or the like. These fillers are added to a polypropylene (PP) resin, which is a polymer material, to connect the connector cover 5. Is molded. The amount of filler added is 1 to 30% by volume in consideration of the moldability of the connection body cover 5. Here, the results of evaluating the thermal conductivity, volume resistivity and moldability of the PP resin containing boron nitride are shown in FIG. The thermal conductivity of PP resin is 0.14 (W / m · K). When 30% by volume of boron nitride is added to PP resin, the thermal conductivity is 0.5 (W / m · K). . In the present embodiment, a composition D (having 30% by volume of boron nitride added) having good moldability and the highest thermal conductivity is used. Thus, the heat dissipation of the connection body cover 5 itself can be improved by forming the connection body cover 5 from the polymer material to which the insulating and high thermal conductive filler is added.

  And in this embodiment, the connection body 4 and the connection body cover 5 which connect the lead storage battery 2 adjacent to the horizontal direction are the upper part of one heat dissipation space S formed between the lead storage batteries 2 adjacent to the said horizontal direction. (Refer to FIG. 5). Specifically, the vertical dimension of the upper opening of the heat dissipation space S formed between the lead storage batteries 2 adjacent in the lateral direction is set to be larger than the width dimension of the connection body cover 5, and the connection body 4 and the connection A body cover 5 is provided so as to block the longitudinal center of the upper opening of the heat radiation space S. In addition, the horizontal direction dimension of the upper opening of the thermal radiation space S formed between the lead storage batteries 2 adjacent to the horizontal direction is 10 mm.

  Next, (1) conventional battery pack A in which no protruding portion is provided in the battery case and no insulating and high thermal conductive filler is added, and (2) boron nitride is applied to the battery case 21, the lid 22 and the connection body cover 5. The assembled battery B using the added polymer material and the battery case 21 having no protrusions, and (3) the polymer material obtained by adding boron nitride to the battery case 21, the lid 22 and the connection body cover 5, An assembled battery C (assembled battery according to this embodiment) in which the protruding portion 211 is provided in the tank 21; (4) a battery case using a polymer material in which boron nitride is added to the battery case 21, the lid 22, and the connection body cover 5; 21 shows a comparison of the assembled battery D in which a protruding portion is provided at 21 and the protruding portion is located directly below the connecting body 4 (the connecting body 4 is not directly above the heat radiation space S).

  In order to confirm the high-rate discharge cycle life performance of the assembled batteries A to D, after discharging the assembled batteries A to D with a current of 165 A for 18 minutes, a pattern of charging 1.8 hours with a current of 33 A A test for one cycle was performed. Moreover, in order to confirm the capacity | capacitance in the cycle life test of assembled battery A-D, the judgment discharge which discharges assembled battery A-D until the terminal voltage becomes 40.8V with the electric current of 33A for every 100 cycles of the said pattern. Then, the time when the capacity of the assembled battery A to D was less than 80% of the initial value (the capacity of the assembled battery at the start of the high rate discharge cycle life test) was determined as the assembled battery life.

  FIG. 7 is a graph showing the transition of the assembled battery temperature during the high rate discharge cycle life test of the assembled batteries A to D. The assembled battery temperature was measured by inserting thermocouples into the gaps between the corners of four batteries adjacent in the vertical and horizontal directions at the center of the assembled battery. As can be seen from FIG. 7, the assembled battery B has a lower assembled battery temperature than the assembled battery A, and the assembled battery D has a lower assembled battery temperature than this. It can be seen that the battery C has a lower assembled battery temperature. Further, FIG. 8 shows the number of cycles until the assembled batteries A to D reach the lifetime in the high rate discharge cycle life test. As can be seen from FIG. 8, the cycle life of the assembled battery B is extended (3300 cycles) compared to the cycle life of the assembled battery A (2200 cycles), and the cycle life of the assembled battery D is further extended. (3400 cycles), it can be seen that the cycle life of the battery pack C is further extended (3500 cycles).

  In addition, using the assembled battery 100 in which 24 lead storage batteries (unit cells) having different height dimensions of the protrusions 211 with respect to the width dimensions of the recesses formed in the battery case 21 are connected in series, the pattern is similar to the above. A high rate discharge cycle life test was conducted. At that time, FIG. 9 shows the relationship between the height dimension of the protrusion 211 and the assembled battery temperature during the high rate discharge cycle life test in each width dimension of the recess formed in the battery case 21. When the sum of the widths of the recesses is 1/3, the sum of the widths of the recesses is one third of the sum of the widths of the outer surfaces 21a to 21d of the battery case 21. When the sum of the width dimensions of the recesses is a half of the sum of the width dimensions of the outer surfaces 21a to 21d of the battery case 21, the sum of the recess widths = 2/3 is the sum of the width dimensions of the recesses. The case where it is 2/3 with respect to the sum total of the width dimension of 21 outer surface 21a-21d is shown. As can be seen from FIG. 9, it can be seen that the larger the height of the protruding portion 211 is, the lower the assembled battery temperature is. When the total concave width is ½ or more, the total concave width is ½ or more. However, it can be seen that the temperature of the assembled battery is significantly reduced.

<Effect of this embodiment>
According to the present embodiment configured as described above, since the heat radiation space S is formed between the adjacent lead live batteries 2, it is possible to prevent the heat radiation performance of each lead live battery 2 from being lowered. Since the connection body 4 and the connection body cover 5 are located in the upper part, the temperature rise of the connection body 4 can be prevented. Thereby, the high rate discharge characteristic and cycle life performance of the assembled battery 100 can be improved.

<Other modified embodiments>
The present invention is not limited to the above embodiment.

  For example, in the above embodiment, the plurality of lead storage batteries are closely arranged in the vertical direction and the horizontal direction, but may be closely arranged in one of the vertical direction and the horizontal direction.

  In the embodiment, the protrusions 211 are provided on the four outer surfaces of the battery case. However, the protrusions 211 may be formed on the bottom surface of the battery case as shown in FIG. In this case, the protrusion 211 provided on the bottom surface may be formed along the vertical direction so as to be continuous with the protrusion 211 formed on the long side surface, or continuous with the protrusion 211 formed on the short side surface. As such, it may be formed along the lateral direction. FIG. 10 illustrates the latter. If this is the case, a heat radiation space can be formed between the bottom surface of the lead storage battery 2 and the bottom surface of the assembled battery case 3, and the heat radiation performance of the assembled battery 100 can be improved. In particular, by forming the protruding portion 211 on the bottom surface so as to be continuous with the protruding portion 211 formed on the short side surface, air can easily pass through the heat radiation space formed under the connecting body cover, and the connecting body cover 5 and the connecting body cover 5 are connected. The temperature rise of the body 4 can be more effectively prevented.

  Furthermore, in the said embodiment, although the radiation fin part was formed in all the four outer surfaces of a lead storage battery, as shown in FIG. 11, a radiation fin part is provided in at least one outer surface of an adjacent lead live battery. May be formed.

  In addition, a radiating fin portion may be formed on at least one of the lead battery that contacts the side wall of the assembled battery case or the side wall of the assembled battery case.

  In addition, in the above embodiment, only the connection body and the connection body cover that connect between the terminals of the lead storage batteries adjacent in the lateral direction are configured to be located in the upper part of the heat radiation space. You may comprise so that a body cover may be located in the upper part of heat dissipation space. Thereby, the temperature rise of all the connection bodies and a connection body cover can be prevented effectively.

  Moreover, although the protrusion part is formed in the battery case in the said embodiment, you may provide the cover body with the protrusion part of the same shape planar view as the battery case. Thereby, the fall of the thermal radiation performance of each lead acid battery can be prevented, and the high rate discharge characteristic and cycle life performance of an assembled battery can be improved.

  In the above embodiment, PP (polypropylene) resin is used as the polymer material, but PE (polyethylene) resin, AS (acrylonitrile styrene) resin, and ABS (acrylonitrile butadiene styrene) resin may be used.

  In the embodiment, the battery is an assembled battery in which 24 2V lead-acid batteries are connected in series. However, an assembled battery (24V) in which 12 2V lead-acid batteries are connected in series may be used, and 48 2V lead-acid batteries may be used. An assembled battery (96V) connected in series may be used.

  Moreover, in the said embodiment, although the liquid type clad lead acid battery was used, it is applicable also to a gel type or a granular silica type clad type lead acid battery, a paste type liquid type, or a control valve type lead acid battery.

  Moreover, although the said embodiment demonstrated the assembled battery using the some lead acid battery, it is applicable to the assembled battery using various batteries, such as an alkaline storage battery.

  In addition, it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

100 ・ ・ ・ Battery 2 ・ ・ ・ Lead battery (single cell)
3 ... Battery case 21 ... Battery case 21a-21d ... Outer surface 211 ... Projection part S ... Radiation space 23A, 23B ... Terminal 4 ... Connection body 5 ... Connector cover

Claims (5)

A battery assembly configured by closely arranging a plurality of unit cells having a substantially rectangular parallelepiped shape in a predetermined direction in a standing state, and connecting terminals of the unit cells by a connecting body,
A protrusion extending along the standing direction is formed on at least one outer surface of the adjacent unit cell,
The assembled battery is characterized in that the connection body is located above a heat dissipation space formed between the adjacent single cells by the protruding portion. It has an assembled battery case that houses the plurality of unit cells,
The assembled battery according to claim 1, wherein a protruding portion extending along a vertical direction is formed on at least one of the side wall of the assembled battery case or the unit cell contacting the side wall of the assembled battery case.   The assembled battery according to claim 1 or 2, wherein the battery case of the unit cell and the lid for closing the battery case are made of a polymer material to which an insulating and high thermal conductive filler is added.   The connection body cover which covers the said connection body, The said connection body cover consists of a polymeric material to which the insulating and high heat conductive filler was added, and is located in the upper part of the said thermal radiation space. An assembled battery according to any one of the above. The assembled battery according to claim 1, wherein the single battery is a lead storage battery.