JP2010108751A - Battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery in which a high battery capacity density can be obtained, while securing electrical connections between a current collector and an electrode. <P>SOLUTION: The battery has two unit batteries that are laminated having a positive electrode, a negative electrode, and a solid electrolyte located in between the positive electrode and the negative electrode, and is provided with a positive electrode current collecting part 11. The surfaces of the positive electrodes of the two unit batteries are connected to a conductive connecting layer 25, and the positive electrode current collecting part 11 is conduction-connected to the end-face portion of the positive electrode 1, including the conductive connecting layer 25. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a battery, and more specifically to a battery capable of increasing the battery capacity density of laminated thin film batteries.

Batteries used in portable electronic devices are always required to be small or have high energy density and high safety. Among batteries, lithium batteries in particular are intensively researched and developed because they can obtain a high energy density due to the small atomic weight of lithium and high ionization energy. In the battery, the electrode needs to maintain good electrical contact with the current collector, but in the lithium battery, the negative electrode repeats expansion and contraction with charge / discharge, so ensure the above electrical contact. Is important. For this reason, a lithium battery in which the current collector can be elastically deformed while closely contacting the electrode has been proposed (Patent Document 1). Such a current collector includes, for example, an elastic base and a conductive layer formed on the surface of the elastic base. Another current collector can also be obtained by disposing a conductive polymer layer on the surface of the conductive substrate.
JP 2000-195523 A

  In order to increase the capacity of the battery, the battery must have a large area and be stacked. When the batteries are stacked, the multilayer structure of the above (elastic substrate / conductive layer) or (conductive substrate / conductive polymer) increases in thickness (height). As a result, the battery capacity per unit volume, that is, the battery capacity density inevitably decreases. For secondary batteries that expand and contract greatly due to charge and discharge, ensuring power collection in stacked batteries and ensuring sufficiently high battery capacity density are essential requirements for powering portable electronic devices. become.

  An object of this invention is to provide the battery which can obtain a high battery capacity density, ensuring the electrical connection of a collector and an electrode.

  The battery of the present invention includes a first battery, a second battery having a first electrode, a second electrode paired with the first electrode, and a solid electrolyte positioned between the first electrode and the second electrode. It is a battery provided with. The battery includes a current collector for the first electrode in the first and second batteries, and the surfaces of the first electrodes of the first and second batteries are connected to each other by a conductive connection layer. The current collector is conductively connected to the end face of the first electrode including the conductive connection layer.

According to said structure, it is not necessary to insert an elastic layer etc. between the 1st electrode which faces, and 1st electrodes should just be conductively connected. Even if expansion / contraction due to charging / discharging occurs, even if a simple mechanism is used or there is no such mechanism, electrical connection is ensured at the end face portion. Current collection by contact at the end face is less susceptible to expansion / contraction associated with charging / discharging, especially when the first electrode is a positive electrode that forms a skeleton for storing ions of the electric medium. Small volume change. For this reason, it is easy to maintain the conductive connection between the current collecting portion at the end face and the first electrode stably.
In addition, regarding the concern about the increase in volume due to the arrangement of the current collecting part on the end face part, even in the conventional current collecting system in which a metal foil or the like is inserted between the layers for current collecting, a current collecting terminal is provided on the end face part Since it has been arranged, it can be said that even if the current collecting part is arranged on the end face part, there is almost no increase in volume. For this reason, battery capacity density can be improved by the amount by which the stacking direction height is reduced.
The first and second batteries described above may be the same battery or different batteries. The battery of the present invention may include another battery in addition to the first and second batteries.

  The current collector in the end surface portion of the first electrode can include a conductive paste or a conductive adhesive positioned in contact with the end surface portion. As a result, even if there is a slight step between the two first electrodes at the end surface, the conductive paste or the conductive adhesive can be brought into close contact with the step surface to ensure predetermined conduction.

  The current collector at the end face of the first electrode can further include a conductive elastic material in addition to the conductive paste or the conductive adhesive. As a result, the stress applied to each current collector can be relaxed. For example, in a battery assembled by stacking a plurality of the above-mentioned batteries, it expands to the whole stacked battery by charging / discharging during use during the work of connecting the current collectors at the end face part in common or after packaging. When the shrinkage occurs, the conductive elastic material serves as a cushion and can relieve stress applied to each current collector. Examples of the conductive elastic material include carbon and a conductive polymer.

  The surfaces of the two first electrodes can be conductively connected by a conductive paste or a conductive adhesive. Thus, the two first electrode surfaces can be bonded (connected) to each other with a conductive paste or a conductive adhesive that becomes a conductive connection layer.

  The battery can be a lithium battery, and the first electrode can be a positive electrode. As a result, a lithium battery having a high battery capacity density can be obtained while reliably maintaining the electrical connection between the positive electrode and the current collector.

  The battery of the present invention may be one in which any of the batteries described above are stacked and assembled so that the current collecting portions are in the same position when viewed in plan. Thereby, the electrical connection between the electrode and the current collector is maintained, and a battery having a larger capacity can be provided while maintaining a high battery capacity density.

  In the assembled laminated battery, the current collector can be conductively connected by a common wiring extending in a direction in which a plurality of batteries are laminated. As a result, it is possible to simplify the current collector wiring structure, the wiring component, and the work of forming the wiring structure. An inexpensive assembled battery capable of supplying a large current can be obtained.

The battery of the present invention includes a conductive connection layer, a first active material layer located on one surface of the conductive connection layer, and a second active material layer located on the other surface of the conductive connection layer. And a current collector is connected to the end face of the first active material layer, the end face of the second active material layer, and the end face of the conductive connection layer. To do.
The current collector referred to in the present invention can be formed by providing a conductive paste or a conductive adhesive. The current collector can be composed of one member connected to the end face of the first active material layer, the end face of the second active material layer, and the end face of the conductive connection layer. Can also be included. The portion having the first active material layer, the conductive connection layer, and the second active material layer in the present invention can be regarded as one electrode, and can be regarded as either a positive electrode or a negative electrode. Note that the first active material layer and the second active material layer mean layers in the first electrode, and both of them (the first active material layer and the second active material layer) have the same polarity. is there.
By adopting such a configuration, even if the active material layer expands / shrinks due to charge / discharge, the electrical connection between the first active material layer, the second active material layer, and the conductive connection layer is achieved. Connection can be ensured reliably. This is because current collection at the end face is less susceptible to expansion and contraction. Therefore, a battery employing such a configuration lacks the need to include a conductive layer formed on the surface of an elastic substrate as disclosed in Patent Document 1. Therefore, a battery showing a high battery capacity density is obtained as a result of not providing the conductive layer.
In the battery according to the present invention, it is not necessary to include the conductive layer as disclosed in Patent Document 1, and just because the battery includes the conductive layer as disclosed in Patent Document 1, the battery is within the scope of the present invention. Is not excluded. The technical feature of the present invention is that the current collector is connected to the end face of the first active material layer, the end face of the second active material layer, and the end face of the conductive connection layer. The characteristics are the same as the battery of the other invention disclosed in the present application.

  According to the present invention, a battery having a high battery capacity density can be obtained while ensuring electrical connection between the electrode and the current collector.

(Embodiment 1)
FIG. 1 is a diagram showing a battery 10 according to Embodiment 1 of the present invention. FIG. 2 is a perspective view of the battery 10 shown in FIG. In FIG. 1, two positive electrodes 1 are conductively connected to a conductive connection layer 25, and the solid electrolyte 2 / negative electrode 3 / negative electrode current collector 12 are arranged symmetrically about the conductive connection layer 25. Has been. The conductive connection layer 25 is formed by a conductive paste or a conductive adhesive.
The current collection of the positive electrode is performed by the positive electrode current collector 11 that is conductively connected to the end face of (positive electrode 1 / conductive connection layer 25 / positive electrode 1). The positive electrode current collector 11 is composed of an end surface contact portion 11a that is in close contact with the end surface of the positive electrode 1, etc., a cushion portion 11b that combines conductivity and elasticity, and has a cushion action, and a current collector wiring portion 11c. ing. The end face contact portion 11a can be formed of a conductive paste or a conductive adhesive, similarly to the conductive connection layer 25. However, the conductive paste should be left with a little elasticity without firing at a high temperature. Moreover, it is good to use conductive elastic materials, such as carbon, for the cushion part 11b. Although the current collecting wiring part 11c is used alone as a current collecting wiring, it is a member that emphasizes the function of collecting current in common when a plurality of the batteries 10 are stacked and assembled as will be described later. A conductive tape is preferably used for the current collector wiring portion 11c.

  The thickness of the conductive connection layer 25 (conductive paste or conductive adhesive) is about 1 μm. In the conventional positive electrode current collecting structure (positive electrode / conductive layer / positive electrode current collector / conductive layer / positive electrode), the portion corresponding to the conductive connection layer 25 is (conductive layer / positive electrode current collector / conductive). Layer). Since the thickness of the copper foil, aluminum foil, etc. of the positive electrode current collector is 10 μm to 20 μm and the conductive layer is about 1 μm, the thickness of the battery should be reduced by 10 μm to 20 μm by the positive electrode current collecting structure shown in FIG. Can do.

  When forming (positive electrode 1 / conductive connection layer 25 / positive electrode 1) using a conductive paste, the two positive electrodes 1 are formed into a sintered body by one firing process (positive electrode 1 / conductive connection layer 25). / Positive electrode 1) can be produced. At this time, the firing temperature is determined according to the request for the material for forming the positive electrode 1 (the firing temperature for maximizing the function as the positive electrode). Accordingly, the material of the conductive paste should be determined. In contrast, when a conductive adhesive is used, the two sintered positive electrodes 1 are conductively bonded by the conductive adhesive. In the case of a conductive adhesive, it is solidified by evaporation of a solvent using a stock solution such as a conductive filler, a binder resin, and a solvent thereof. Many types of conductive adhesives are also commercially available.

  In the positive electrode current collector 11 that is conductively connected to the end face portion, the end face close contact portion 11a is formed by using a conductive paste or the like, even if there is a difference in level between the two positive end faces constituting the end face portion. Following the discrepancy, the entire end face can be adhered. The thickness of the conductive paste 11a in the positive electrode current collector 11 varies depending on the dimensional accuracy of the positive electrode or the like, but it is usually preferable to set the thickness to about 0.5 μm to 3 μm. With the end face contact portion 11a made of the conductive paste or the like, although it is an end face portion of a plurality of layers, current collection at the end face portion can be reliably performed. The width W of the positive electrode current collector 11 does not need to cover the entire width of the battery 10 as shown in FIG. The width W is about 100 μm to 300 μm, but can be arbitrarily set according to battery performance.

  In a stacked battery in which a plurality of the batteries shown in FIGS. 1 and 2 are stacked and assembled, the positive electrode current collector 11 is wired in a common position when viewed in a plan view. The current collector wiring portion 11c of the positive electrode current collector 11 is performed using a conductive tape or the like. The cushion part 11b in the positive electrode current collecting part 11 is a stress generated between the current collecting wiring part 11c caused by expansion / contraction due to charging / discharging of each battery in a laminated battery assembled by laminating a plurality of batteries. Can be mitigated and absorbed. By constituting the positive electrode current collector 11 by the end face contact part 11a / cushion part 11b / current collector wiring part 11c, it is possible to reliably collect current at the end face in a laminated battery assembled by laminating many batteries. In addition, the thickness can be significantly reduced. As a result, the battery capacity density can be improved.

Next, the portion of the lithium secondary battery 10 shown in FIG. 1 will be described.
(1) Conductive connection layer 25
The conductive connection layer 25 is preferably formed by a conductive paste or a conductive adhesive. When using a conductive paste, the two positive electrodes 1 can be fired simultaneously. That is, (the material before firing of the positive electrode / conductive paste / the material before firing of the positive electrode) can be fired under conditions optimal for the performance of the positive electrode. Many types of conductive paste are commercially available, such as a high-temperature fired material that can be fired at about 800 ° C. and a low-temperature fired material that can be fired at about 150 ° C. and can maintain elasticity. The firing temperature, hardness, elasticity, etc. are set according to the resin component contained therein. The optimum firing condition for the performance of the positive electrode is usually high-temperature firing, and a high-temperature fired material is preferably used. As the conductive paste, any commercially available metal filler-containing paste such as an Ag paste, Al paste, or Ni paste may be used. Moreover, as long as electroconductivity is ensured, a paste containing a carbon filler instead of a metal filler may be used. When a conductive adhesive is used to form the conductive connection layer 25, the conductive adhesive conductively connects two positive electrodes that have already been baked.
Whether the conductive paste is used or the conductive adhesive is used to form the conductive connection layer 25, the thickness of the conductive connection layer 25 is preferably about 1 μm as described above.
(2) End face adhesion part 11a
For the end face contact portion 11a, a low-temperature fired material of conductive paste or a conductive adhesive is preferably used. In order to collect electricity at the end face in close contact with the end face portions of the plurality of layers, it is preferable that the battery is elastic to some extent and can follow expansion / contraction due to charge / discharge of the secondary battery. The high-temperature fired type conductive paste is not suitable for the end face contact portion 11a because it has high hardness but is brittle.
(3) Positive electrode active material 1
A thin film of a lithium composite oxide such as LiCoO ₂ , LiMn ₂ O ₄ , or LiNiO ₂ can be used. As a forming method, a thin film forming process such as vapor deposition, sputtering, or PLD (pulsed laser deposition) can be used. Moreover, the sintered compact formed using the screen printing method etc. may be sufficient instead of a thin film. In both the case of the thin film and the case of the sintered body, the thickness is preferably 0.5 μm to 100 μm.
(4) Solid electrolyte 2
Li ₂ S—P ₂ S ₅ , LiLaTiO, LiLaZrO, or the like can be used. In addition, although partially overlapping, an Li—P—S—O amorphous film or a polycrystalline film may be used, or an Li—P—O—N amorphous film or a polycrystalline film may be used. As a forming method, a thin film forming process such as vapor deposition, sputtering, or PLD can be used. The thickness of the solid electrolyte is preferably about 1 μm to 20 μm.
(5) Negative electrode active material 3
A thin film of Li metal, Li alloy, Si, Sn, In, or Ag can be used. The thickness is preferably 0.5 μm to 75 μm. As a forming method, a thin film forming process such as vapor deposition, sputtering, or PLD can be used.
(6) Negative electrode current collector 12
Copper, aluminum, nickel, alloys of these metals, foils such as SUS (stainless steel), or plate-like bodies can be used. The thickness is preferably about 3 μm to 40 μm, but may be a thickness outside this range.
When the negative electrode active material is also used as the current collector without using the negative electrode current collector, the connection terminal is connected to the negative electrode active material with a conductive adhesive or the like.

Next, the manufacturing method will be described.
(Manufacturing method S1) Manufacturing method for conductively connecting two positive electrodes in a sintered body As shown in FIG. 3, two positive electrodes 1 for a sintered body are prepared and connected with a conductive adhesive or a conductive paste. To do. Next, the positive electrode current collector 11 is formed on the end face of (positive electrode 1 / conductive connection layer 25 / positive electrode 1) so as to be conductively connected. At this stage, the positive electrode current collector 11 forms the end face contact portion 11a / cushion portion 11b, and does not provide the current collector wiring portion 11c. The current collecting wiring portion 11c is preferably arranged when a plurality of the batteries 10 shown in FIG. 1 are stacked and assembled. After the positive electrode current collector 11 is formed on the end face part, (solid electrolyte 2 / negative electrode 3) is then formed on one laminated side by a thin film formation process, and then turned upside down on the other laminated side. Similarly, (solid electrolyte 2 / negative electrode 3) is formed by a thin film formation process.
(Manufacturing method S2) The method of manufacturing two positive electrodes by one sintering process As shown in FIG. 4, the sintering raw material (raw material) 1R used as the positive electrode 1 is connected by the electrically conductive paste 25R. The sintered material 1R can be manufactured by a screen printing method, a doctor blade method, or the like. By sintering this (positive electrode sintered material 1R / conductive paste 25R / positive electrode sintered material 1R), the positive electrode 1 composed of two sintered bodies can be obtained by a single sintering process. it can. Thereafter, the method of forming the positive electrode current collector 11 on the end face of (positive electrode 1 / conductive connection layer 25 / positive electrode 1) is the same as the method shown in FIG. 3 (production method S1). The subsequent thin film formation process is also the same as the method of FIG.
In both of the above production methods S1 and S2, a battery 10 shown in FIG. 1, that is, a laminate of two unit cells in a mirror symmetry position with the conductive connection layer 25 as a mirror surface is manufactured. Note that, in the present embodiment, the case of the same two unit batteries having a mirror-symmetrical relationship in particular has been illustrated, but the battery of the present invention is generally the same as the first battery and the second battery regardless of the difference. The battery should just be located on both sides of the conductive connection layer 25.

  Usually, the battery 10 shown in FIG. 1 is rarely used alone, and in most cases, as shown in FIG. 5, the battery 10 shown in FIG. . In the laminated battery 50 shown in FIG. 5, ten batteries 10 shown in FIG. 1 are laminated. Each battery 10 is an all-solid lithium secondary battery. In order to collect and collect the individual positive electrode current collectors 11 in common, a current collector wiring part 11c made of a conductive tape of common wiring is disposed outside (end face contact part 11a / cushion part 11b). A negative electrode current collector wiring 12c for wiring the individual current collectors 12 of the negative electrode 3 in common is also provided. For the negative electrode current collector 12, a copper foil or the like in which a lithium thin film is formed on the surface of the negative electrode that is in contact with lithium is preferably used.

  In the assembled battery 50, 10 batteries 10 are stacked and 20 unit batteries are stacked. However, all 20 unit batteries can be connected in parallel to supply a large current. In the portable device, the voltage can be handled by a single lithium battery, and the assembled laminated battery 50 shown in FIG. 5 is used to secure the battery capacity. The assembled laminated battery 50 can be reduced in thickness (stacked height) by a maximum of about 20 μm × 10 = 200 μm (0.2 mm) as compared with a conventional laminated battery. There is also a portable device in which 50 batteries 10 have to be stacked. In such a case, the battery 10 can be thinned up to about 1 mm.

  Although the embodiments and examples of the present invention have been described above, the embodiments and examples of the present invention disclosed above are merely examples, and the scope of the present invention is the implementation of these inventions. It is not limited to the form. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  According to the battery of the present invention, a battery having a high battery capacity density can be obtained while ensuring electrical connection between the electrode and the current collector. In particular, even if there is compression / expansion due to charging / discharging, stable and reliable current collection can be achieved, and current collection wiring, wiring components, and current collection wiring work can be simplified.

It is sectional drawing which shows the battery in embodiment of this invention. It is a perspective view of the battery of FIG. It is a figure which shows manufacturing method S1 of the battery of FIG. It is a figure which shows manufacturing method S2 of the battery of FIG. It is a figure which shows the laminated battery assembled by laminating | stacking 10 batteries of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode (positive electrode active material), 2 Solid electrolyte, 3 Negative electrode (negative electrode active material), 10 Battery (2 unit cells), 11 1st electrode (positive electrode) current collection part, 11a End surface contact | adherence part, 11b Cushion part (conductivity) 11c current collecting wiring part (conductive tape), 12 second electrode (negative electrode) current collecting part, 12c negative current collecting wiring, 25 conductive connection layer, 50 assembled laminated battery.

Claims (8)

A battery comprising a first battery and a second battery, comprising: a first electrode; a second electrode paired with the first electrode; and a solid electrolyte positioned between the first electrode and the second electrode. There,
A current collector for the first electrode in the first and second batteries;
The surfaces of the first electrodes of the first and second batteries are connected by a conductive connection layer,
The battery according to claim 1, wherein the current collecting portion of the first electrode is conductively connected to an end surface portion of the first electrode including the conductive connection layer.   2. The battery according to claim 1, wherein the current collecting portion at the end face portion of the first electrode includes a conductive paste or a conductive adhesive located in contact with the end face portion.   The battery according to claim 2, wherein the current collector at the end face of the first electrode further includes a conductive elastic material.   The battery according to any one of claims 1 to 3, wherein the surfaces of the two first electrodes are conductively connected by a conductive paste or a conductive adhesive.   The battery according to claim 1, wherein the battery is a lithium battery, and the first electrode is a positive electrode.   A battery according to any one of claims 1 to 5, wherein a plurality of the batteries are stacked and assembled so that the current collecting portions are in the same position when seen in a plan view.   The battery according to claim 6, wherein the current collector is conductively connected by a common wiring extending in a direction in which the plurality of batteries are stacked. A battery comprising: a conductive connection layer; a first active material layer located on one surface of the conductive connection layer; and a second active material layer located on the other surface of the conductive connection layer. ,
A battery, wherein a current collector is connected to an end face of the first active material layer, an end face of the second active material layer, and an end face of the conductive connection layer.

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