JP7118109B2 - lithium ion battery - Google Patents

Description

The present invention relates to lithium ion batteries.

2. Description of the Related Art Conventionally, an assembled battery in which a plurality of lithium-ion cells are stacked is used as a power source for portable electronic devices such as electric vehicles and hybrid electric vehicles. When charging such an assembled battery, it is necessary to manage charging so that there is no overcharged unit cell.

Patent Document 1 describes that the voltage between the terminals of each cell in the battery pack is transmitted to an external charging device via electrical connections such as metal wiring and terminals. (See, for example, paragraph 0040 of Patent Document 1 and FIG. 4).

International Publication No. 2009/119075 JP-A-11-341693

In this way, when transmitting information about the characteristics of each single cell in the battery pack to an external device via an electrical connection, the number of wires and As the number of terminals increases, the problem of increased weight and increased space due to wiring and terminals arises. Moreover, if electrical wiring is installed, there is a risk of short-circuiting between cells and troublesome wiring.

In order to solve such problems, there is a concept of utilizing optical fibers for transmitting optical signals. For example, in Patent Document 2, an overcharge heating circuit including a light emitting diode is connected in parallel to both ends of a battery module including single cells connected in series, and when overcharge occurs, the light emission of the light emitting diode is common. It is disclosed that the light is sent to a light receiving diode by an optical fiber (see, for example, paragraphs 0012, 0023-0024 of Patent Document 2, and FIG. 5).

However, according to the technique described in Patent Document 2, although the risk of short-circuiting between single cells can be resolved by adopting the means of optical fibers, optical fibers also require wiring connection in the same way as the electrical wiring described above. However, the wiring required a lot of work, and the above-mentioned problems were still unsolved. In addition, if a configuration is adopted in which optical signals are collectively transmitted by an optical fiber, strict alignment is required, so there is also the problem of being vulnerable to positional deviation.
The present invention has been made in view of such problems, and its object is to eliminate the complexity of wiring in a configuration in which an optical signal is output from a light emitting portion of each unit cell that constitutes an assembled battery. To provide a lithium-ion battery capable of reducing the displacement and increasing the allowable amount of misalignment.

In order to achieve such an object, a lithium ion battery according to an embodiment of the present invention is
A plurality of stacked single cells, each of which has a measurement unit that measures characteristics of the single cell and a light emitting unit that emits light based on the characteristics of the single cell and outputs an optical signal. a single cell;
a light guide plate disposed adjacent to or in close proximity to the light emitting surface of the light emitting portion, the light guide plate having a light output portion for outputting an incident and propagated optical signal;
an exterior body that accommodates a plurality of batteries and a light guide plate,
The light guide plate is characterized in that it serves as a common transmission path for the optical signals from the plurality of cells.

As described above, according to the present invention, an optical signal output from a light-emitting portion of each unit cell that constitutes an assembled battery housed in an exterior body of a lithium-ion battery is transmitted to a light guide plate serving as a common transmission path. By configuring so as to transmit by , it is possible to reduce the complexity of wiring and increase the allowable amount of positional deviation.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structure of the lithium ion battery concerning one Embodiment of this invention, (a) is a perspective view which notched one part, (b) is a perspective view which shows an external appearance. FIG. 2 is a diagram showing a schematic cross-sectional structure of the lithium ion battery shown in FIG. 1; FIG. 4 is a diagram showing the configuration of a lithium-ion battery according to another embodiment of the present invention, where (a) is a partially cutaway perspective view and (b) is a perspective view showing the appearance. FIG. 4 is a diagram showing a modified example of the lithium ion battery shown in FIG. 3; FIG. 10A is a view showing a light guide plate of a lithium-ion battery according to another embodiment of the present invention, where (a) is a view showing a light guide plate having a conical (linear taper) cross-sectional shape, and (b) is an exponential function FIG. 4 illustrates a light guide plate having a tapered or parabolic tapered cross-sectional shape;

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or similar reference numerals indicate the same or similar elements, and repeated descriptions may be omitted. It goes without saying that the numerical values and materials described below are exemplary and, therefore, the present invention can be practiced using other numerical values and materials without departing from the scope of the invention.

A lithium-ion battery according to an embodiment of the present invention is a plurality of stacked single cells, each of which includes a measurement unit that measures the characteristics of the single cell and emits light based on the characteristics of the single cell. A plurality of unit cells having a light emitting portion that outputs a signal, and a light guide plate that is arranged adjacent to or in proximity to the light emitting surface of the light emitting portion, and has a light output portion from which the incident and propagated optical signal is emitted. It includes a light guide plate and an exterior body that accommodates a plurality of batteries and the light guide plate, and the light guide plate serves as a common transmission path for optical signals from the plurality of unit cells. A portion of the light guide plate may be pulled out of the exterior body and adhered to the exterior body to serve as a light output section. Alternatively, the entire light guide plate including the light output section may be housed in the exterior body.

Typically, a cell is formed by laminating a positive electrode current collector, a positive electrode active material layer, a separator, a negative electrode active material layer, and a negative electrode current collector in this order from the bottom. The unit cell has a positive electrode in which a positive electrode active material layer is formed on the surface of a substantially rectangular plate-shaped positive electrode current collector, and a negative electrode active material layer formed on the surface of a substantially rectangular flat negative electrode current collector. and a negative electrode are laminated with a substantially flat separator interposed therebetween. In the unit cell, an annular frame member is arranged between the positive electrode current collector and the negative electrode current collector, and the frame member fixes the peripheral edge portion of the separator between the positive electrode current collector and the negative electrode current collector. , the positive electrode active material layer, the separator and the negative electrode active material layer are sealed. For example, the light emitting section may be embedded in or attached to the frame member so as to be exposed on the side surface of the frame member.

(First embodiment)
FIG. 1 is a diagram showing the configuration of a lithium ion battery according to a first embodiment of the invention. FIG. (a) is a partially cutaway perspective view, and (b) is a perspective view showing the appearance.

As shown in FIG. 1, the lithium ion battery 1 has a plurality of stacked single cells 30 . The lithium ion battery 1 also has a light guide plate 60 that is arranged adjacent to or in close proximity to the light emitting surface of the light emitting section 20 . Furthermore, the lithium ion battery 1 has an exterior body 70 that accommodates the plurality of cells 30 and the light guide plate 60 .

A plurality of stacked single cells 30 constitute an assembled battery 50 . Although FIG. 1 shows a configuration in which five cells 30 are stacked, more or less than five cells may be stacked. Each unit cell 30 has a negative electrode current collector (not shown) and a positive electrode current collector (not shown) facing the negative electrode current collector. Two adjacent cells 30 in the assembled battery 50 are stacked such that the upper surface of the negative electrode current collector of one cell 30 and the lower surface of the positive electrode current collector of the other cell 30 are adjacent to each other. FIG. 1 shows an assembled battery 50 in which five cells 30 are connected in series.

The positive electrode current collector and the negative electrode current collector are made of metal materials such as copper, aluminum, titanium, stainless steel, nickel and alloys thereof, baked carbon, conductive polymer materials, conductive glass, etc. can be configured.

A conductive sheet is provided on the uppermost negative electrode current collector of the assembled battery 50 . A part of the conductive sheet is pulled out from the outer package 70 to form the lead wiring 57 . A conductive sheet is provided under the positive electrode current collector on the bottom surface of the assembled battery 50 . A part of the conductive sheet is pulled out from the exterior body 70 to form the lead wiring 59 . The conductive sheet can be constructed using any of metal materials such as copper, aluminum, titanium, stainless steel, nickel and alloys thereof, but is not limited to these materials as long as they are conductive materials. The conductive sheet may be constructed using a conductive polymeric material.

Each unit cell 30 has a measuring unit (not shown) that measures the characteristics of the unit cell and a light emitting unit 20 that emits light based on the measured characteristics and outputs an optical signal.

The measurement unit can be configured to measure the voltage of the cell 30 and control the light emission of the light emitting unit 20 based on the measured voltage. More specifically, the measurement unit is electrically coupled to voltage measurement terminals (not shown) that are in contact with the positive electrode current collector and the negative electrode current collector, respectively, and is electrically coupled to the voltage measurement terminals and to the light emitting unit 20 . and a control element (not shown). The control element can be configured using any semiconductor element such as IC or LSI. The control element is powered by the cell 30 and can be configured to supply a control signal to the light emitting section 20 according to the voltage between the positive and negative current collectors.

The light emitting unit 20 may be configured using light emitting elements such as LED elements and organic EL elements. The light emitting section 20 is powered by the cell 30 and can be configured to be driven (that is, emit light) based on a control signal from a control element that constitutes the measuring section.

The light-emitting portion 20 is arranged on one of the short sides of the cell 30 . Preferably, in a state in which the plurality of unit cells 30 are stacked, the light emitting surfaces of the plurality of light emitting units 20 are arranged in a line in the stacking direction of the plurality of unit cells 30 on the side surface of the assembled battery 50 .

The light guide plate 60 has an optical output portion from which the incident and propagated optical signal is emitted. In this embodiment, a part of the light guide plate 60 is pulled out from the exterior body 70 and serves as a light output section. An optical signal emitted from the optical output section is received by the light receiving section 80 . The light receiving section 80 can be configured using a photodiode, a phototransistor, or the like. The light-receiving section 80 may be configured using an LED element, which is a light-emitting element, as a light-receiving element. Note that, as described above, the entire light guide plate 60 including the light output section may be housed inside the exterior body 70 . In this case, it is not necessary to bring part of the light guide plate 60 into close contact with the exterior body 70 as will be described later. When the entire light guide plate 60 is housed inside the exterior body 70 , the light signal emitted from the light output section is received by the light receiving section 80 arranged inside the exterior body 70 .

FIG. 2 is a diagram showing a schematic cross-sectional structure of the lithium ion battery shown in FIG. As shown in FIG. 2 , the light guide plate 60 extending in the stacking direction of the cells is arranged adjacent to or close to the light emitting surface of the light emitting section 20 . The light guide plate 60 has a sufficient width (length in the direction orthogonal to the stacking direction of the cells) to receive the optical signal from the light emitting section 20 . The width dimension of the light guide plate 60 is larger than the maximum dimension of the light emitting surface of the light emitting section 20 (the diameter if the light emitting surface is circular, and the diagonal if the light emitting surface is rectangular). The light guide plate 60 is arranged so as to cover the light emitting surfaces of the plurality of light emitting portions 20 (each corresponding to a plurality of stacked unit cells) (preferably to cover all the light emitting surfaces). The light guide plate 60 is arranged so as to cover all of the light emitting directions of the light emitting section 20 (including cases in which the direction is aligned with the vertical direction of the light emitting surface and cases in which the direction is inclined from the vertical direction of the light emitting surface). The dimension in the thickness direction of the light guide plate 60 (the dimension in the stacking direction corresponding to the light emitting portion 20 of one cell) is not particularly limited, but is preferably larger than the thickness of the cell (thickness in the stacking direction), for example.

The light guide plate 60 is made of a material having a higher refractive index than the surrounding medium (for example, air). Here, the term "high refractive index" means a refractive index that differs from the refractive index of the surrounding medium so that incident light can be confined in the light guide plate and propagated. For example, the light guide plate 60 can be configured using a resin film or resin plate with a high refractive index. Preferably, the light guide plate 60 is constructed using a deformable resin film or resin plate to the extent that a bent portion of about 90 degrees can be formed. The deformable resin film or resin plate may be soft at normal temperature or room temperature, or hard at normal temperature or room temperature. For the light guide plate 60, for example, only the light input portion (the portion adjacent to or close to the light emitting surface of the light emitting portion 20) and the light output portion of the surface of the light guide plate 60 facing the light emitting surface of the light emitting portion 20 are made of a low refractive index material. It is also possible to adopt a configuration in which there is no confinement (reduced confinement capability), and portions other than the input section and the light output section (the back surface and side surfaces of the light guide plate 60) are covered with a material having a refractive index lower than that of vacuum.

The resin forming the resin film or the resin plate forming the light guide plate 60 is not limited, but may be an acrylic resin or the like. For example, a flexible resin film or resin plate can be selected from high-refractive-index resins called optical materials. A resin that forms the resin film or resin plate that constitutes the film light guide plate 60 is preferably made of a material that does not easily absorb the light emission wavelength band of the light emitting element. When the emission wavelength band of the light-emitting element is infrared light, a film made of a material having a low infrared absorption peak at 850 nm to 950 nm is desirable.

The light guide plate 60 is provided with scattering processing 60a at a position on the back surface corresponding to a position on the surface where the optical signal is received. The scattering processing 60a is applied to a position corresponding to the light emitting surface of the adjacent or adjacent light emitting section 20. As shown in FIG. The scattering processing 60a can be, for example, uneven processing. Part of the optical signal that has entered the light guide plate 60 and is scattered by the scattering processing 60a propagates in the direction of the light output section.

The light guide plate 60 has a reflective processing 60b applied to the bent portion, so that the light signal scattered by the bent portion can be reflected in the direction of the light output section. In addition, reflection processing 60b is applied to the end portion of the light guide plate 60 opposite to the end portion serving as the light output portion and the bent portion. The direction of the light output can be reflected.

Referring again to FIG. 1, the outer body 70 can be constructed using a metal can case or a polymer metal composite film. The exterior body 70 is sealed so as to maintain the internal pressure reduction.

With the above configuration, the lithium-ion battery of the present embodiment receives, outside or inside the exterior body, an optical signal output from the light-emitting portion of each unit cell that constitutes the assembled battery housed in the exterior body. It will be possible to use

As described above, in the lithium-ion battery of the present embodiment, the light guide plate is used as a common transmission path for transmitting optical signals output from the light-emitting units of the cells constituting the assembled battery. Compared to the case of using it as a path, the complexity of the positioning of the common transmission path is reduced, or the allowable amount of positional deviation is increased.

Furthermore, since the light guide plate is used as the common transmission path, the optical signal output from the light emitting unit is more easily received than when an optical fiber is used as the common transmission path. Even if the relative positions of the light emitting unit and the common transmission path change, the resistance to positional deviation between the light emitting unit and the common transmission path that may occur due to the change is increased. In addition, since the light guide plate is used as the common transmission path, it is possible to efficiently receive the optical signal over a relatively wide area. There is no need for additional components such as lenses for incident light.

In addition, by using a light guide plate made of a deformable resin film as a common transmission path, even if the position of the light emitting part changes due to deformation of the unit cell, etc., the change in position can be followed. As a result, it is possible to easily adjust the relative positions of the light emitting unit and the common transmission path by deforming the common transmission path.

(Second embodiment)
The present embodiment provides a lithium ion battery 1 using an exterior body 70 configured using a polymer-metal composite film. An assembled battery 50 including a plurality of stacked unit cells 30 is housed in an exterior body 70 configured using a laminate film (polymer-metal composite film) in which an aluminum foil or steel foil and a plastic film are laminated. be. The interior of the exterior body 70 is maintained in a decompressed state.

FIG. 3 is a diagram showing the configuration of a lithium ion battery 1 according to a second embodiment of the invention. FIG. 3(a) is a partially cutaway perspective view, and FIG. 3(b) is a perspective view showing the appearance.

The lithium-ion battery 1 of this embodiment has a plurality of stacked single cells 30, like the lithium-ion battery 1 shown in FIG. The lithium ion battery 1 also has a light guide plate 60 that is arranged adjacent to or in close proximity to the light emitting surface of the light emitting section 20 . Furthermore, the lithium ion battery 1 has an exterior body 70 that accommodates the plurality of cells 30 and the light guide plate 60 .

As shown in FIG. 3 , the light guide plate 60 extending in a direction substantially orthogonal to the stacking direction of the cells is arranged adjacent to or close to the light emitting surface of the light emitting section 20 . The light guide plate 60 has a width (length in the stacking direction of the cells) sufficient to receive optical signals from the plurality of light emitting units 20 arranged in the stacking direction of the cells. Since the light guide plate 60 in the lithium-ion battery 1 shown in FIG. 1 has a structure extending in the stacking direction of the plurality of unit cells 30, the propagation distance of the optical signal increases as the number of stacks of the unit cells 30 increases. , the intensity of the light at the light output may be reduced. On the other hand, in the light guide plate 60 extended in a direction substantially perpendicular to the stacking direction of the unit cells as in the present embodiment, the optical signal propagation distance, which increases as the number of stacks of the unit cells 30 increases, should be reduced. It is possible to reduce the possibility that the light intensity at the light output section is reduced.

As in the embodiment described with reference to FIG. 1, the light guide plate 60 is made of a resin film or a resin film that has a high refractive index and is deformable enough to form a bent portion of about 90 degrees. It can be constructed using a plate. Further, the light guide plate 60 may be provided with scattering processing 60a at a position corresponding to the light emitting surface of the adjacent or adjacent light emitting unit 20 on the back surface corresponding to the surface that receives the optical signal. Part of the optical signal that has entered the light guide plate 60 and is scattered by the scattering processing 60a propagates in the direction of the light output section. Further, the light guide plate 60 may be subjected to reflection processing 60b at the bent portion.

The assembled battery 50 is accommodated using two laminate films that constitute the exterior body 70 . More specifically, the assembled battery 50 placed on the planar first laminate film is covered with the second laminate film folded into a box shape, the pressure inside is reduced, and the edge of the first laminate film is The assembled battery 50 can be housed inside the exterior body 70 by heat-sealing the edge of the second laminate film and the edge of the second laminate film.

Part of the conductive sheet provided on the uppermost negative electrode current collector of the assembled battery 50 is pulled out from the edge of the outer package 70 (the portion where the first laminated film and the second laminated film overlap). A lead wiring 57 is formed. Similarly, part of the conductive sheet provided under the positive electrode current collector on the lowermost surface of the assembled battery 50 is also led out from the edge of the outer package 70 to form lead wiring 59 . Lead wires 57 and lead wires 59 are heat-sealed to the edges of the first laminate film and the second laminate film, respectively.

A part of the light guide plate 60 is pulled out from a cut (slit) formed along the folding line of the mountain-folded portion of the second laminate film folded into a box shape to serve as a light output portion. The light output section is heat-sealed to the mountain-folded portion of the second laminate film (the front and back surfaces of the light output section are closely attached to the second laminate film).

As shown in FIG. 3, the light guide plate 60 has a bent portion depending on the position of the mountain fold portion (position of the slit) in the second laminate film. Since the light guide plate 60 is formed using a resin film or resin plate that is deformable at normal temperature, room temperature, or the temperature range in which the battery is used, it is possible to easily form a bent portion during the manufacturing process. The light guide plate 60 may be made of a resin that is hard at normal or room temperature. In this case, the bent portion of the light guide plate 60 may be temporarily deformable by heat treatment during the manufacturing process. When the light guide plate 60 is made of a resin that is hard at room temperature or room temperature, the light emitting part and the light guide plate 60, which is a common transmission path, may be affected by changes in the volume of the cells, compared to the case where the light guide plate 60 is made of a resin that is soft at room temperature or room temperature. By deforming the light guide plate 60, the adjustment range of the relative position between the light emitting section 20 and the light guide plate 60 can be reduced.

FIG. 4 is a diagram showing a modification of the lithium ion battery 1 shown in FIG. The light guide plate 60 of the lithium ion battery 1 shown in FIG. 4 differs from the lithium ion battery 1 shown in FIG. 3 in that it does not include a bent portion. Since it does not include a bent portion, scattering or reflection in the light guide plate 60 is reduced, and optical signal loss is reduced.

The width of the slit in the mountain-folded portion of the second laminate film forming the exterior body is determined according to the width of the light guide plate 60 . Considering the internal decompression in the manufacturing process and the adhesion of the edges of the laminate film, it is advantageous to narrow the width of the light guide plate 60 and narrow the width of the slit.

FIG. 5 is a diagram showing a light guide plate 60 included in the lithium-ion battery according to this embodiment. FIG. 5(a) is a view showing a light guide plate 60 having a conical (linear taper) cross-sectional shape, and FIG. 5(b) is a view showing a light guide plate 60 having an exponential function taper or parabolic taper cross-sectional shape. be.

Optionally, the light guide plate 60 is shaped like the light guide plate 60 of FIG. 5(a) or the light guide plate 60 of FIG. 5(b) to reduce propagation loss and propagate optical signals with high efficiency. At the same time, the width of the light guide plate 60 can be reduced.

With the above configuration, the lithium-ion battery of the present embodiment receives and utilizes the optical signal output from the light emitting unit of each unit cell that constitutes the assembled battery housed in the outer package outside the outer package. It becomes possible to

As described above, in the lithium-ion battery of the present embodiment, the light guide plate is used as a common transmission path for transmitting optical signals output from the light-emitting units of the cells constituting the assembled battery. Compared to the case of using it as a path, the complexity of the positioning of the common transmission path is reduced, or the allowable amount of positional deviation is increased. In particular, considering the possibility of misalignment of the optical fiber due to the deformation of the outer package when decompressing the inside of the outer package made of laminated material, which can occur when optical fibers are used as a common transmission path, Lithium ion batteries of embodiments are notable.

Note that the lithium-ion battery package 70 described with reference to FIG. 1 may be configured using the first laminate film and the second laminate film as described with reference to FIG. In this case, a portion of the light guide plate 60 extending in the direction in which the light emitting units 20 are arranged is pulled out from the edge of the exterior body 70 (flat portion where the first laminate film and the second laminate film overlap). Then, it is heat-sealed to the edges of the first laminate film and the second laminate film to form a light output portion.

Various embodiments and modifications thereof have been described above, but the present invention can be implemented by replacing some or all of the constituent elements or by adding constituent elements without departing from the scope of the invention. It goes without saying that it is possible.

Reference Signs List 1 lithium-ion battery 20 light-emitting portion 30 unit cell 50 assembled battery 57, 59 lead wiring 60 light guide plate 70 exterior body 80 light-receiving portion

Claims (7)

A plurality of stacked unit cells, wherein each unit cell has a measuring unit that measures characteristics of the unit cell and a light emitting unit that emits light based on the characteristics of the unit cell and outputs an optical signal. a plurality of single cells;
a light guide plate disposed adjacent to or in close proximity to the light emitting surface of the light emitting portion, the light guide plate having a light output portion for outputting the incident and propagated optical signal;
An exterior body that houses the plurality of cells and the light guide plate,
The light guide plate serves as a common transmission path for the optical signals from the plurality of cells,
The lithium ion battery, wherein the light guide plate extends in a direction orthogonal to the stacking direction of the plurality of unit cells, and the width of the light guide plate decreases toward the light output section. The exterior body is formed of a laminate film,
2. The lithium ion battery according to claim 1, wherein said light guide plate is made of resin. The width direction dimension of the light guide plate perpendicular to the extending direction of the light guide plate is larger than the maximum dimension of the light emitting surface, and the light guide plate is located in the light emitting part corresponding to the plurality of stacked unit cells. 3. The lithium ion battery according to claim 1, arranged so as to cover the light emitting surface. 4. The lithium ion battery according to any one of claims 1 to 3, wherein said light guide plate is arranged so as to cover all light emitting directions of light emitting elements of said light emitting portion. 5. The lithium ion battery according to any one of claims 1 to 4, wherein said light guide plate is made of a deformable material following volumetric deformation of said plurality of cells. 3. The lithium ion battery according to claim 2, wherein a part of said light guide plate is pulled out from a mountain fold portion of said laminate film or a flat portion where said laminate films overlap. 7. A portion of the light guide plate is subjected to scattering processing or reflection processing, and the optical signal propagates by being scattered or reflected in the light guide plate and is output from the light output unit. or the lithium ion battery according to claim 1.

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