Patent Description:
The present technology relates to a battery module.

A battery module in which a plurality of battery cells are stacked has been conventionally known. A partition wall portion (separator) for securing insulation is provided between the plurality of battery cells, and a path for cooling air is provided in the partition wall portion (<CIT> and <CIT>).

Further, patent document <CIT> discloses an electrochemical energy storage device comprising a casing, in which a plurality of flat galvanic cells are arranged. Between two adjacent flat galvanic cells is in each case, a flat heat conducting body and/or a flat elastic body arranged. Preferably, the flat galvanic cells, the flat heat conducting bodies and/or the flat elastic bodies exert upon each other at the contact surface areas, a force corresponding to a surface pressing, and the casing has a wall with a structure or with structures, in which a heat conducting body engages such that said heat conducting body may not be shiftable in the direction of the force acting on the contact surface areas.

Patent document <CIT> discloses a battery unit, in particular for an electric or hybrid motor vehicle, comprising: a plurality of battery cells, optionally physically grouped into modules of two or more battery cells, a housing that accepts and surrounds said plurality of battery cells, said housing comprising a bottom wall on which the battery cells rest, a top wall arranged above the battery cells, and side walls connecting the lower and upper walls, wherein at least one cooling channel passes through each of the lower and upper walls of the housing, via which a coolant is able to flow, said cooling channel being configured to cover the entirety of the surface of the lower wall, or of the upper wall, and wherein the lower and upper walls of the housing are connected by a plurality of cooling plates, each cooling plate being arranged between two adjacent battery cells, or modules of adjacent battery cells, or being in contact with at least one battery cell, and being configured to transmit the heat generated by the battery cells to the coolant.

Moreover, patent document <CIT> discloses a rechargeable battery module including a plurality of unit cells arranged at particular intervals; a heat sink plate mounted between the plurality of unit cells and adapted to dissipate heat generated by the plurality of unit cells; and at least one cooling channel positioned on a first side of the heat sink plate or penetrating through the heat sink plate and adapted to circulate a coolant. A method for dissipating heat from a plurality of unit cells arranged at particular intervals includes providing a heat sink having a channel adapted to circulate a coolant; positioning a heat sink between neighboring ones of the plurality of unit cells; and supplying a coolant to the channel.

For further reduction of manufacturing cost, however, there is still room for improvement in the cooling structure of the battery module. It is an object of the present technology to provide a battery module to attain efficient cooling while reducing manufacturing cost.

The above object is solved by the subject-matter of claim <NUM>. Further advantageous configurations of the invention can be drawn from the dependent claims.

A battery module according to an explanatory aspect of the present disclosure includes: a plurality of battery cells arranged side by side in a first direction, each of the plurality of battery cells having a prismatic shape; and a partition wall portion provided between the plurality of battery cells to secure electrical insulation between the plurality of battery cells. The partition wall portion includes a first partition wall portion and a second partition wall portion, the first partition wall portion and the second partition wall portion being provided alternately, the second partition wall portion having a shape different from a shape of the first partition wall portion, the second partition wall portion forming a cooling space between the second partition wall portion and each of two battery cells located on both sides beside the second partition wall portion in the first direction.

Hereinafter, embodiments of the present technology will be described. It should be noted that the same or corresponding portions are denoted by the same reference characters, and may not be described repeatedly.

It should be noted that in the embodiments described below, when reference is made to number, amount, and the like, the scope of the present technology is not necessarily limited to the number, amount, and the like unless otherwise stated particularly. Further, in the embodiments described below, each component is not necessarily essential to the present technology unless otherwise stated particularly.

It should be noted that in the present specification, the terms "comprise", "include", and "have" are open-end terms. That is, when a certain configuration is included, a configuration other than the foregoing configuration may or may not be included. Further, the present technology is not limited to one that necessarily exhibits all the functions and effects stated in the present embodiment.

In the present specification, the term "battery" is not limited to a lithium ion battery, and may include another battery such as a nickel-metal hydride battery. In the present specification, the term "electrode" may collectively represent a positive electrode and a negative electrode. Further, the term "electrode plate" may collectively represent a positive electrode plate and a negative electrode plate.

It should be noted that in the figures, a stacking direction of the battery cells is defined as a first direction serving as a Y direction, a direction in which two electrode terminals of each battery cell are arranged side by side is defined as a second direction serving as an X direction, and a height direction of the battery cell is defined as a third direction serving as a Z direction.

<FIG> is a perspective view showing a configuration of a battery module according to one embodiment of the present technology. <FIG> is a perspective view of the battery module of <FIG> when viewed in a direction of an arrow II. <FIG> is a perspective view showing configurations of a unit and end plates included in the battery module according to the embodiment of the present technology.

A battery module <NUM> is used as a power supply for driving a vehicle such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or a battery electric vehicle (BEV), for example.

First, an overall structure of battery module <NUM> will be described. As shown in <FIG>, battery module <NUM> includes a plurality of units <NUM>, end plates <NUM>, restraint members <NUM>, a lower restraint member <NUM>, a wiring member <NUM>, a duct <NUM>, and connection terminals <NUM>.

The plurality of units <NUM> are arranged side by side in the first direction (Y direction). Six units <NUM> are arranged side by side in the Y direction as the plurality of units <NUM> according to the present embodiment. It should be noted that the number of the plurality of units <NUM> is not particularly limited as long as two or more units <NUM> are included.

The plurality of units <NUM> are sandwiched between two end plates <NUM>. The plurality of units <NUM> according to the present embodiment are pressed by end plates <NUM> and restrained between two end plates <NUM>.

End plates <NUM> are provided at the both ends beside the plurality of units <NUM> in the Y direction. Each of end plates <NUM> is fixed to a base such as a pack case that accommodates battery module <NUM>. End plate <NUM> is composed of, for example, aluminum or iron.

Restraint members <NUM> are provided on both sides beside the plurality of units <NUM> and end plates <NUM> in the X direction. When restraint members <NUM> are engaged with end plates <NUM> with compressive force in the Y direction being applied to the plurality of units <NUM> arranged side by side and to end plates <NUM> and then the compressive force is released, tensile force acts on restraint members <NUM> that connect two end plates <NUM>. As a reaction thereto, restraint members <NUM> press two end plates <NUM> in directions of bringing them closer to each other. As a result, restraint members <NUM> restrain the plurality of units <NUM> in the first direction (the Y direction).

Each of restraint members <NUM> includes a plate-shaped portion <NUM>, a first flange portion <NUM>, and second flange portions <NUM>. Restraint member <NUM> is composed of iron, for example.

Plate-shaped portion <NUM> is a member extending in the Y direction. Plate-shaped portion <NUM> is provided with a plurality of openings <NUM>. The plurality of openings <NUM> are provided at intervals in the Y direction, and each of openings <NUM> is constituted of a through hole extending through plate-shaped portion <NUM> in the X direction.

First flange portion <NUM> extends from beside the side surfaces of the plurality of units <NUM> so as to be located over the upper surfaces of the plurality of units <NUM>. By providing first flange portion <NUM>, rigidity of restraint member <NUM> formed to be relatively thin can be secured.

Second flange portions <NUM> are connected to both ends of plate-shaped portion <NUM> in the Y direction. Second flange portions <NUM> are fixed to end plates <NUM>. Second flange portions <NUM> are fixed to end plates <NUM> by a known fixing method such as fastening of bolt, for example. Thus, restraint members <NUM> connect two end plates <NUM> to each other.

As shown in <FIG>, lower restraint member <NUM> is provided on the bottom surfaces of the plurality of units <NUM> and end plates <NUM>. Lower restraint member <NUM> protects below-described battery cells <NUM> from the bottom surface side. Lower restraint member <NUM> is composed of iron, for example.

As shown in <FIG>, wiring member <NUM> is provided at a position facing the plurality of units <NUM> in the Z direction. Wiring member <NUM> extends in the Y direction through the center portion of each of the plurality of units <NUM> in the X direction. Wiring member <NUM> is electrically connected to the plurality of units <NUM>. Wiring member <NUM> is, for example, a flexible printed circuit board.

Duct <NUM> extends in the Y direction. Duct <NUM> extends at a position overlapping with wiring member <NUM> when viewed in the Z direction. Duct <NUM> is disposed between each of the plurality of units <NUM> and wiring member <NUM> in the Z direction.

Connection terminals <NUM> are arranged on both sides beside the plurality of units <NUM> arranged side by side in the Y direction. Each of connection terminals <NUM> is provided at a position overlapping with end plate <NUM> when viewed in the Z direction. Connection terminal <NUM> connects battery module <NUM> to an external wiring such as a cable (not shown) disposed outside battery module <NUM>.

Next, a structure of unit <NUM> will be described. <FIG> is a perspective view showing a configuration of the unit included in the battery module according to the embodiment of the present technology. <FIG> is a perspective view of the unit of <FIG> when viewed in a direction of an arrow V.

As shown in <FIG>, each of the plurality of units <NUM> includes a plurality of battery cells <NUM>, a case <NUM> serving as a supporting member, and a bus bar <NUM>.

Unit <NUM> includes two or more battery cells <NUM>. Unit <NUM> according to one embodiment of the present technology includes four battery cells <NUM> as an even number of battery cells <NUM>. It should be noted that the number of battery cells <NUM> included in each of the plurality of units <NUM> is not particularly limited as long as two or more battery cells <NUM> are included. Moreover, an odd number of battery cells <NUM> may be included in each of the plurality of units <NUM>.

The plurality of battery cells <NUM> are arranged side by side in the first direction (Y direction). Four battery cells <NUM> are arranged side by side in the Y direction as the plurality of battery cells <NUM> according to the embodiment of the present technology. The arrangement direction of the plurality of units <NUM> is the same as the arrangement direction of the plurality of battery cells <NUM> in each of the plurality of units <NUM>.

Case <NUM> has an external appearance with a rectangular parallelepiped shape. Case <NUM> accommodates the plurality of battery cells <NUM>. Case <NUM> is composed of, for example, a resin such as polypropylene. As shown in <FIG>, case <NUM> is compressed in the first direction (Y direction) by restraint members <NUM>.

As shown in <FIG>, case <NUM> has a front wall portion <NUM>, a rear wall portion <NUM>, a first side wall portion <NUM>, a second side wall portion <NUM>, and an upper surface portion <NUM>.

Front wall portion <NUM> is a surface adjacent to one of restraint members <NUM>. As shown in <FIG>, front wall portion <NUM> is provided with a plurality of first ventilation ports <NUM>. Each of first ventilation ports <NUM> is a through hole extending through front wall portion <NUM> in the X direction.

As shown in <FIG>, rear wall portion <NUM> is a surface facing front wall portion <NUM> with the plurality of battery cells <NUM> being interposed therebetween in the X direction. Rear wall portion <NUM> is provided with a plurality of second ventilation ports <NUM>. Each of second ventilation ports <NUM> is a through hole extending through rear wall portion <NUM> in the X direction. Each of the plurality of second ventilation ports <NUM> communicates, through a below-described communication space <NUM>, with a corresponding one of first ventilation ports <NUM> arranged side by side in the X direction.

First side wall portion <NUM> and second side wall portion <NUM> are arranged side by side in the first direction (Y direction), and face each other.

As shown in <FIG>, first side wall portion <NUM> has a protrusion <NUM>. Protrusion <NUM> protrudes opposite to second side wall portion <NUM>. As shown in <FIG>, second side wall portion <NUM> is provided with a recess <NUM>. Recess <NUM> is recessed toward first side wall portion <NUM> and has a shape engageable with protrusion <NUM>. Protrusion <NUM> and recess <NUM> of adjacent units <NUM> of the plurality of units <NUM> are engaged with each other.

Upper surface portion <NUM> includes first wall portions <NUM>, second wall portions <NUM>, third wall portions <NUM>, fourth wall portions <NUM>, engagement surfaces <NUM>, and hole portions <NUM>. Two first wall portions <NUM> are formed parallel to each other so as to extend in the Y axis direction at the center portion in the X direction. Second wall portions <NUM>, third wall portions <NUM>, and fourth wall portions <NUM> are provided on both sides beside first wall portions <NUM> in the X direction so as to define installation positions for bus bars <NUM>. Each of second wall portions <NUM> is provided with a notch 252A through which a below-described voltage detection wire <NUM> extends. Second flange portions <NUM> of restraint members <NUM> are engaged with engagement surfaces <NUM>. Hole portions <NUM> communicate with below-described gas-discharge valves <NUM>.

Each of bus bars <NUM> is composed of an electric conductor. The plurality of bus bars <NUM> electrically connect the plurality of battery cells <NUM> together.

<FIG> is a perspective view showing a configuration of a battery cell included in the battery module according to the embodiment of the present technology.

As shown in <FIG>, battery cell <NUM> is, for example, a lithium ion battery. Battery cell <NUM> has a prismatic shape. Individual battery cell <NUM> has an output density of, for example, about <NUM> W/L or more.

Battery cell <NUM> according to the present embodiment has electrode terminals <NUM>, a housing <NUM>, and a gas-discharge valve <NUM>.

Electrode terminals <NUM> are formed on housing <NUM>. Electrode terminals <NUM> have a positive electrode terminal <NUM> and a negative electrode terminal <NUM> as two electrode terminals <NUM> arranged side by side along the second direction (the X direction) orthogonal to the first direction (the Y direction).

Positive electrode terminal <NUM> and negative electrode terminal <NUM> are provided to be separated from each other in the X direction. Positive electrode terminal <NUM> and negative electrode terminal <NUM> are provided on both sides beside wiring member <NUM> and duct <NUM> in the X direction.

Housing <NUM> has a rectangular parallelepiped shape, and forms the external appearance of battery cell <NUM>. An electrode assembly (not shown) and an electrolyte solution (not shown) are accommodated in housing <NUM>.

Housing <NUM> includes an upper surface <NUM>, a lower surface <NUM>, a first side surface <NUM>, a second side surface <NUM>, and a third side surface <NUM>.

Upper surface <NUM> is a flat surface orthogonal to the Z direction. Electrode terminals <NUM> are disposed on upper surface <NUM>. Lower surface <NUM> faces upper surface <NUM> along the third direction (Z direction) orthogonal to the first direction (Y direction).

Each of first side surface <NUM> and second side surface <NUM> is constituted of a flat surface orthogonal to the Y direction. Each of first side surface <NUM> and second side surface <NUM> has the largest area among the areas of the plurality of side surfaces of housing <NUM>. Each of first side surface <NUM> and second side surface <NUM> has a rectangular shape when viewed in the Y direction. Each of first side surface <NUM> and second side surface <NUM> has a rectangular shape in which the X direction corresponds to the long-side direction and the Z direction corresponds to the short-side direction when viewed in the Y direction.

The plurality of battery cells <NUM> are stacked such that first side surfaces <NUM> of battery cells <NUM>, <NUM> adjacent to each other in the Y direction face each other and second side surfaces <NUM> of battery cells <NUM>, <NUM> adjacent to each other in the Y direction face each other. Thus, positive electrode terminals <NUM> and negative electrode terminals <NUM> are alternately arranged in the Y direction in which the plurality of battery cells <NUM> are stacked.

It should be noted that when an odd number of battery cells <NUM> are included in unit <NUM>, the posture of unit <NUM> may be turned by <NUM>° with respect to the Z axis between units <NUM> adjacent to each other in the Y direction.

Gas-discharge valve <NUM> is provided in upper surface <NUM>. When internal pressure of housing <NUM> becomes more than or equal to a predetermined value due to gas generated inside housing <NUM>, gas-discharge valve <NUM> discharges the gas to the outside of housing <NUM>. The gas from gas-discharge valve <NUM> flows through duct <NUM> in <FIG> and is discharged to the outside of battery module <NUM>.

<FIG> is a partial perspective view showing a configuration of each voltage detection wire included in the battery module according to the embodiment of the present technology.

As shown in <FIG>, wiring member <NUM> includes voltage detection wires <NUM> that each detects a voltage. The plurality of voltage detection wires <NUM> extend to and are connected to bus bars <NUM>. One voltage detection wire <NUM> is disposed in each of the plurality of units <NUM>. Thus, voltage detection wire <NUM> can detect the voltage of unit <NUM>.

<FIG> is a cross sectional view of the unit of <FIG> when viewed in a direction of arrows of a line VIII-VIII. <FIG> is an enlarged view of a portion IX in <FIG>. <FIG> is a cross sectional view when viewed in a direction of arrows of a line X-X in <FIG>.

As shown in <FIG>, case <NUM> serving as a supporting member further has partition wall portions. Each of the partition wall portions is located between the plurality of battery cells <NUM>, and functions as a separator to secure electrical insulation between the plurality of battery cells <NUM>. The partition wall portions according to the present embodiment have a first partition wall portion <NUM> and second partition wall portions <NUM>.

As shown in <FIG>, battery cells <NUM> are sandwiched by first partition wall portion <NUM> and second partition wall portions <NUM> of case <NUM>. Case <NUM> supports battery cells <NUM> in the first direction (Y direction).

First partition wall portion <NUM> is located at substantially the center of unit <NUM> in the Y direction. First partition wall portion <NUM> in the present embodiment is disposed between two battery cells <NUM> arranged on the center side in the Y direction among four battery cells <NUM> accommodated in unit <NUM>. First partition wall portion <NUM> is continuous in the Z direction inside case <NUM>.

Second partition wall portions <NUM> are provided on both sides beside first partition wall portion <NUM> in the Y direction with battery cells <NUM> being interposed therebetween. Second partition wall portions <NUM> are continuous in the Z direction inside case <NUM>.

Each of second partition wall portions <NUM> has thin portions <NUM> and ribs <NUM>. Each of thin portions <NUM> is a portion of second partition wall portion <NUM> with a small thickness in the Y direction. Four thin portions <NUM> are provided along the Z direction so as to be centered on the upper surface portion <NUM> side with respect to the center of second partition wall portion <NUM> in the Z direction. Ribs <NUM> are located among four thin portions <NUM>.

In battery module <NUM>, first partition wall portion <NUM> and second partition wall portion <NUM> are alternately arranged side by side in the first direction (Y direction). First partition wall portion <NUM> and second partition wall portion <NUM> have different shapes. Each of first partition wall portion <NUM> and second partition wall portion <NUM> is in abutment with battery cell <NUM> in the first direction (Y direction). On this occasion, a contact area (second area) between second partition wall portion <NUM> and battery cell <NUM> is smaller than a contact surface (first area) between first partition wall portion <NUM> and battery cell <NUM>.

A partition wall portion is provided with a communication space <NUM> (cooling space) extending in the second direction (X direction) intersecting the first direction (Y direction) and the third direction (Z direction). Regarding the partition wall portions according to the present embodiment, a plurality of communication spaces <NUM> are provided in the both surfaces of second partition wall portion <NUM>. Since thin portions <NUM> and ribs <NUM> are formed in second partition wall portions <NUM>, communication spaces <NUM> communicate inside case <NUM> in which battery cells <NUM> are accommodated. Communication spaces <NUM> communicate with first ventilation ports <NUM> and second ventilation ports <NUM>.

As shown in <FIG>, communication space <NUM> is formed to extend across a whole of a width direction of second partition wall portion <NUM> in the second direction (X direction). Communication spaces <NUM> are continuous to openings <NUM> in the second direction (X direction). Thus, by introducing cooling air from first ventilation ports <NUM> or second ventilation ports <NUM> and allowing the cooling air to flow through communication spaces <NUM>, battery cells <NUM> accommodated in case <NUM> can be cooled.

At least part of communication spaces <NUM> is located on the upper surface <NUM> side with respect to the center between upper surface <NUM> and lower surface <NUM> of housing <NUM>. In the embodiment of the present technology, two communication spaces <NUM>, <NUM> provided on the upper surface <NUM> side among four communication spaces <NUM>, <NUM>, <NUM>, <NUM> arranged side by side in the Z direction are located on the upper surface <NUM> side with respect to the center between upper surface <NUM> and lower surface <NUM>.

Since at least part of communication spaces <NUM> is located on the upper surface <NUM> side with respect to the center between upper surface <NUM> and lower surface <NUM>, the center of gravity of case <NUM> serving as a supporting member can be low, with the result that case <NUM> can be stably freestanding.

In battery module <NUM> according to the embodiment of the present technology, second partition wall portions <NUM>, each of which has both surfaces provided with communication spaces <NUM> that contribute to cooling of battery cell <NUM>, are provided at every other location along the first direction (Y direction), thereby providing the same cooling effect to all the battery cells <NUM>. On the other hand, the thickness of first partition wall portion <NUM> having no communication space <NUM> formed therein can be made smaller than that of second partition wall portion <NUM>. Therefore, battery cells <NUM> can be efficiently and uniformly cooled while attaining reduced manufacturing cost and reduced size of battery module <NUM>.

Further, in battery module <NUM>, since the plurality of battery cells <NUM> are accommodated in case <NUM> such that they are arranged side by side in the first direction (Y direction), unit <NUM> is formed, and the plurality of such units <NUM> are arranged side by side in the first direction (Y direction) to form battery module <NUM>, the manufacturing process can be simplified as compared with a case where battery module <NUM> is manufactured with each of the plurality of battery cells <NUM> being handled as one unit. An example of the simplification is, for example, as follows: units <NUM> each formed to be small is caused to pass through a welding machine to weld bus bars <NUM> in units <NUM>, and then bus bars <NUM> over different units <NUM> are individually joined together, thereby attaining increased efficiency in the welding process.

Further, in battery module <NUM>, since units <NUM> each including the plurality of battery cells <NUM> accommodated in case <NUM> are formed, battery module <NUM> can be readily disassembled or replaced with each unit <NUM> being handled as one unit.

Further, in battery module <NUM>, since units <NUM> each including the plurality of battery cells <NUM> accommodated in case <NUM> are formed, battery module <NUM> can be divided with each unit <NUM> being handled as one unit when discarding battery module <NUM> so as to lower the voltage for the purpose of handling, thereby facilitating the discarding of battery module <NUM>.

Further, in battery module <NUM>, battery cells <NUM> can be restrained by restraint members <NUM> through the configurations of units <NUM>.

Further, in battery module <NUM>, the plurality of units <NUM> are connected together by bus bars <NUM>, with the result that battery module <NUM> can be manufactured with unit <NUM> being handled as one unit.

Further, in battery module <NUM>, since one voltage detection wire <NUM> is disposed on one unit <NUM>, cost of battery module <NUM> can be low as compared with a case where voltage detection wire <NUM> is disposed on each of battery cells <NUM>.

Claim 1:
A battery module (<NUM>) comprising:
a plurality of battery cells (<NUM>) arranged side by side in a first direction, each of the plurality of battery cells (<NUM>) having a prismatic shape;
a partition wall portion (<NUM>, <NUM>) provided between the plurality of battery cells (<NUM>) to secure electrical insulation between the plurality of battery cells (<NUM>);
a case (<NUM>) that accommodates the plurality of battery cells (<NUM>) and supports the plurality of battery cells (<NUM>) at least in the first direction so as to form a unit (<NUM>) including the plurality of battery cells (<NUM>); and
a restraint member (<NUM>) that restrains a plurality of the units (<NUM>) in the first direction, wherein
the case (<NUM>) of each unit (<NUM>) is compressed in the first direction by the restraint member (<NUM>),
the partition wall portion (<NUM>, <NUM>) includes
a first partition wall portion (<NUM>), and
a second partition wall portion (<NUM>), the first partition wall portion (<NUM>) and the second partition wall portion (<NUM>) being provided alternately, the second partition wall portion (<NUM>) having a shape different from a shape of the first partition wall portion (<NUM>), the second partition wall portion (<NUM>) forming a cooling space (<NUM>) between the second partition wall portion (<NUM>) and each of two battery cells (<NUM>) located on both sides beside the second partition wall portion (<NUM>) in the first direction.