JP2005071889A - Battery case and battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery case and a battery that facilitates connection to an external electric circuit board while preventing an electrolyte from leaking due to a gap formed at a joint portion of a battery case of the battery.
A battery case is formed of a ceramic body in which a rectangular parallelepiped recess 1a is formed at the center of an upper surface, and a first conductor layer 1d and a second conductor layer 1e are independently provided on a lower surface. 1, a first metallized layer 1 b formed on the bottom surface of the recess 1 a, a second metallized layer 1 c formed around the recess 1 a on the top surface of the substrate 1, and the first metallized layer 1 b to the first metallized layer 1 b A first inner conductor 2b formed over the conductor layer 1d and a second inner conductor 2c formed over the second metallized layer 1c to the second conductor layer, and at least the lower main surface is The conductive lid 3 is electrically connected to the second metallized layer 1c and joined to the upper surface of the substrate 1 so as to cover the recess 1a.
[Selection] Figure 1

Description

  The present invention relates to a thin battery case and battery that can be used for communication equipment such as a mobile phone, can be easily connected to an external electric circuit board, and can effectively prevent leakage of electrolyte.

  In recent years, portable devices typified by mobile phones, portable computers, camera-integrated video tape recorders, etc. have been remarkably developed, and further miniaturization and weight reduction have been demanded. In addition, the demand for batteries as power sources for these portable devices continues to increase, and research on reducing the size and weight by increasing the energy density of the batteries is actively conducted. In particular, the lithium battery is a battery using lithium with a small atomic weight and a large ionization energy, so that it is possible to obtain a high energy density, to achieve a reduction in size and weight, and to be a battery that can be recharged more actively. It has been researched and has now been used for a wide range of applications including power supplies for portable devices.

  Batteries can be broadly divided into cylindrical and square types. The structure is that the positive and negative electrodes are housed in a metal battery case through a separator made of an insulating sheet, and an electrolyte is injected there. It is a sealed structure.

As a positive electrode of a lithium battery, for example, a metal oxide used as a positive electrode active material and a conductive material added thereto is generally used. For example, lithium cobaltate (LiCoO ₂ ) or lithium manganate (LiMn ₂ O ₄ ) is used as the positive electrode active material, and acetylene black (AB) or graphite is used as the conductive material. As the negative electrode of the battery, a lithium titanium composite oxide such as lithium titanate (Li ₄ Ti ₅ O ₁₂ ) or an active material such as graphite or amorphous carbon solidified with a resin is used.

In the lithium battery, the charge / discharge voltage of the positive electrode active material made of LiCoO ₂ or LiMn ₂ O ₄ is about 4V, while the charge / discharge voltage of the negative electrode active material made of a carbon material or the like is around 0V. For this reason, a high discharge voltage of about 3.5 V is achieved by combining these positive electrode active material, negative electrode active material, and electrolytic solution.

  For the positive electrode of the battery, the conductive material is added to the active material, and a binder such as polytetrafluoroethylene or polyvinylidene fluoride is added and mixed to form a slurry, which is formed into a sheet using a well-known doctor blade method. The sheet is formed and then cut into, for example, a circular shape.

  Also, the negative electrode is added to the above active material, as in the positive electrode, a binder such as polytetrafluoroethylene or polyvinylidene fluoride, mixed to form a slurry, and this is formed into a sheet using a known doctor blade method, Next, this sheet is cut into a circular shape, for example.

  Then, the positive electrode and the negative electrode thus prepared are accommodated in a battery case via a separator made of a polyolefin fiber nonwoven fabric or a polyolefin microporous film having a heat resistant temperature of about 150 ° C. A battery is obtained by injecting the liquid.

  In order to further reduce the size and density of the battery thus manufactured, a coin-type battery A shown in FIG. 3 has been developed.

This conventional battery A is a separator in which a positive electrode can 11 made of, for example, stainless steel provided with a disk-shaped positive electrode 11b and a negative electrode can 12 made of, for example, stainless steel provided with a disk-shaped negative electrode 12b are impregnated with an electrolyte. The battery case structure is configured such that the periphery of the positive electrode can 11 and the periphery of the negative electrode can 12 are caulked together via a gasket 15 made of, for example, insulating polypropylene resin. ing. Charging / discharging in the positive electrode 11b and the negative electrode 12b is performed via an external connection terminal member attached to the positive electrode can 11 and the negative electrode can 12 (see, for example, Patent Documents 1 and 2 below).
JP 2000-106195 A (page 6-12, FIG. 1) JP 2002-198019 A (page 3-4, FIG. 1)

  However, when the conventional battery A as shown in Patent Documents 1 and 2 is exposed to a temperature cycle test (for example, −40 ° C. to 85 ° C.) with a temperature range of a few hundred degrees over a long period of time, for example, Due to the difference in coefficient of thermal expansion between the gasket 15 made of polypropylene resin, the positive electrode can 11 and the negative electrode can 12, a gap is generated at the joining portion of the battery case can which is caulked around the positive electrode can 11 and the negative electrode can 12 through the gasket 15. There is a case where the electrolyte solution leaks, and this causes a problem that the battery performance of the battery A is deteriorated or the copper (Cu) wiring on the external electric circuit board is corroded and disconnected by the leaked electrolyte solution. Alternatively, there has been a problem in that moisture enters the inside of the battery A from this gap and deteriorates the battery performance.

  In addition, the conventional battery A must have a circular shape in plan view in order to securely caulk the periphery of the gasket 15, the positive electrode can 11 and the negative electrode can 12 without any gap, and the shape in plan view can be various shapes such as polygons. And could not. In recent years, with the miniaturization of devices, the market demand for various shapes as well as the size and space saving of batteries has increased, for example, the shape of the battery in plan view for mounting on an external electric circuit board in a space-saving manner. It was impossible to meet the demand for a square.

  Accordingly, the present invention has been completed in view of the above-mentioned problems, and its purpose is to deteriorate the battery performance due to leakage of the electrolyte due to the formation of a gap in the joint portion of the battery case due to long-term use. The battery case and battery with excellent mass productivity that can be easily connected to the external electric circuit board and can be reduced in size are not damaged by the leaked electrolyte solution. There is to do.

  The battery case of the present invention has a rectangular parallelepiped recess formed in the center of the upper surface, and a base made of ceramics having a first conductor layer and a second conductor layer provided independently on the lower surface, and the recess A first metallization layer formed on the bottom surface of the substrate, a second metallization layer formed around the recess on the top surface of the base, and a first metallization layer formed from the first metallization layer to the first conductor layer. The inner body and a second inner conductor formed from the second metallization layer to the second conductor layer, wherein at least the lower main surface is made of a lid body having conductivity. It is electrically connected to the second metallized layer and is bonded to the upper surface of the base so as to cover the concave portion.

  The battery of the present invention includes a battery case having the above configuration, a positive electrode plate connected to the first metallization layer so as to cover it, and an insulating sheet impregnated with an electrolytic solution on the upper surface of the positive electrode plate. A negative electrode plate placed in close contact with the upper surface of the negative electrode plate, the lower main surface is in contact with and electrically connected, and the lid body joined so as to cover the recess It is characterized by having.

  The battery case of the present invention has a rectangular parallelepiped recess formed at the center of the upper surface, a base body made of ceramics with the first conductor layer and the second conductor layer provided independently on the lower surface, and the bottom surface of the recess A first metallized layer formed on the substrate, a second metallized layer formed around the recess on the upper surface of the substrate, and a first inner conductor formed from the first metallized layer to the first conductor layer. And a second inner conductor formed from the second metallization layer to the second conductor layer, and at least a lid body whose lower main surface is conductive is electrically connected to the second metallization layer. The electrolyte is bonded to the upper surface of the base body so as to cover the concave portion, so that the electrolytic solution is bonded to the upper surface of the base body made of ceramics having excellent airtightness and excellent heat resistance so as to cover the concave portion. Formed with lid It and becomes housed in the inside of the case, it is possible to satisfactorily accommodate the electrolyte solution, it does not leak electrolyte occurs gap even when exposed to temperature cycling test. Moreover, since airtightness is maintained, it is possible to effectively prevent moisture, oxygen, or the like that deteriorates battery performance from entering the electrolytic solution from the outside.

  In addition, the substrate is not easily attacked by an electrolytic solution containing an organic solvent, an acid, and the like, and impurities dissolved from the substrate are not mixed in the electrolytic solution, so that the electrolytic solution is not deteriorated. For this reason, battery performance can be maintained satisfactorily.

  Moreover, even if the shape of the substrate in plan view is various shapes such as a quadrangle, the airtightness is maintained, and batteries having various shapes can be obtained according to market demand. As a result, it is possible to meet the market demand for a battery having an appropriate plan view shape suitable for space saving.

  Furthermore, since a portion to be caulked via a conventional resin is not required, the outer shape of the battery can be made as small as possible, which is suitable for recent miniaturization.

  In addition, a second metallized layer electrically connected to the lid is formed around the recess on the upper surface of the base, and a second conductor layer is provided on the lower surface of the base. By forming the second inner conductor over the second conductor layer, the first and second metallized layers respectively connected to the positive and negative electrode plates of the battery are electrically connected to the first and second metallized layers, respectively. By providing the second conductor layer on the lower surface of the base body, it is possible to easily connect to the wiring conductor on the surface of the external electric circuit board by surface mounting without using an external connection terminal member, etc., and it is excellent in mass productivity. It will be.

  The battery of the present invention is in close contact with the battery case having the above configuration, the positive electrode plate connected to the first metallization layer so as to cover it, and the upper surface of the positive electrode plate via an insulating sheet impregnated with an electrolytic solution. A negative electrode plate placed in this manner, and a lid body that is electrically connected with the lower main surface coming into contact with the upper surface of the negative electrode plate and that is joined so as to cover the recess. Therefore, the battery case having the above-described configuration has high airtight reliability and excellent mass productivity. In addition, the negative electrode plate can be directly connected to the lid, the internal resistance around the negative electrode plate can be greatly reduced, and the reliability is high, and charging and discharging can be performed stably over a long period of time. it can.

  The battery case of the present invention will be described in detail below. 1A is a cross-sectional view showing an example of an embodiment of a battery case of the present invention, and FIG. 1B is a plan view of the battery case.

  The battery case of the present invention is a base 1 made of ceramics in which a rectangular parallelepiped recess 1a is formed at the center of the upper surface, and a first conductor layer 1d and a second conductor layer 1e are provided independently on the lower surface. A first metallized layer 1b formed on the bottom surface of the recess 1a, a second metallized layer 1c formed around the recess 1a on the top surface of the substrate 1, and a first conductor from the first metallized layer 1b. A first inner conductor 2b formed over the layer 1d and a second inner conductor 2c formed over the second metallized layer 1c to the second conductor layer 1e, and at least the lower main surface is The conductive lid 3 is electrically connected to the second metallized layer 1c and joined to the upper surface of the substrate 1 so as to cover the recess 1a.

The substrate 1 of the present invention is made of ceramics such as an alumina sintered body and is manufactured as follows. For example, when the substrate 1 is made of an alumina sintered body, an organic binder suitable for raw material powders such as aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), magnesium oxide (MgO), and calcium oxide (CaO). Add a solvent and mix to form a slurry. This slurry is formed into a green sheet by a doctor blade method or a calender roll method and cut into a required size. Next, an appropriate punching process is performed to form the recesses 1a and the like in a plurality of green sheets selected from them.

  Then, a metal paste mainly composed of a metal powder such as tungsten (W) is printed on these green sheets, and the first metallized layer 1b, the first inner conductor 2b, the first conductor layer 1d, the second A printed pattern to be a conductor layer such as the metallized layer 1c, the second inner conductor 2c, and the second conductor layer 1e is formed, and then green sheets on which these printed patterns are formed are laminated, and the temperature is about 1600 ° C. By baking, the base | substrate 1 provided with the conductor layer is produced. The first conductor layer 1d is electrically connected to the first metallized layer 1b via the first inner conductor 2b, and the second conductor layer 1e is second metallized via the second inner conductor 2c. It is electrically connected to the layer 1c. The first conductor layer 1d is used as the positive electrode of the battery, and the second conductor layer 1e is used as the negative electrode. The first conductor layer 1d and the second conductor layer 1e are joined to the wiring conductor on the surface of the external electric circuit board via solder, whereby the battery is electrically connected to the external electric circuit.

  The base body 1 is not easily attacked by the electrolytic solution B-4 (FIG. 2) containing an organic solvent, an acid, etc. Therefore, impurities dissolved from the base body 1 are mixed in the electrolytic solution B-4 and the electrolytic solution B-4 is deteriorated. I will not let you. For this reason, the battery case which can maintain battery performance favorably can be obtained.

  The first and second inner conductors 2b and 2c are shown as one interlayer connection conductor (penetrating conductor) in FIG. 1 that is perpendicular to the first and second conductor layers 1d and 1e. However, the first and second conductor layers 1d and 1e formed on the lower surface of the substrate 1 may be formed by combining a plurality of internal wiring layers in the direction parallel to the vertical interlayer connection conductors. An electric circuit can be routed in the base 1, and the first and second conductor layers 1d and 1e can be formed at desired positions on the base 1.

  Further, the exposed surfaces of these conductor layers formed on the substrate 1 thus manufactured have a metal excellent in corrosion resistance and wettability with solder, specifically nickel (thickness 1 to 12 μm). A Ni) layer and a gold (Au) layer having a thickness of 0.3 to 5 μm are preferably sequentially deposited by a plating method or the like. Thereby, it can suppress effectively that the 1st metallization layer 1b formed especially in the inside of a battery case elutes easily by the voltage by charging / discharging. Further, the first and second conductor layers 1d and 1e and the second metallized layer 1c have better wettability with the solder, and the bonding strength with the wiring conductor on the external electric circuit board becomes stronger. .

  If the thickness of the Ni layer is less than 1 μm, it becomes difficult to prevent the oxidative corrosion of each conductor made of the metallized layer and to effectively prevent the metal component from eluting from the conductor, and the battery performance deteriorates. It becomes easy to do. On the other hand, if the thickness of the Ni layer exceeds 12 μm, it takes a long time to form the plating, so that the mass productivity is likely to be lowered and the electric resistance is likely to be increased.

  Further, if the thickness of the Au layer is less than 0.3 μm, it is difficult to form an Au layer having a uniform thickness, and a portion where the Au layer is extremely thin or a portion where the Au layer is not formed is likely to occur. The effect of preventing oxidative corrosion and the wettability with solder are likely to decrease. If the thickness of the Au layer exceeds 5 μm, it takes a lot of time to form the plating, and the mass productivity tends to decrease.

  The first and second conductor layers 1d and 1e are formed on the lower surface of the base 1. With this configuration, the first and second conductor layers 1d and 1e are soldered onto the wiring conductor on the surface of the external electric circuit board. By joining via the wire, the wiring conductor on the flat external electric circuit board and the battery can be easily connected, and the mass productivity is excellent.

  On the upper surface of the substrate 1, a conductive lid 3 such as aluminum (Al), copper (Cu), carbon, iron (Fe) -Ni-cobalt (Co) alloy, Fe-Ni alloy or the like is Al solder, silver. (Ag) Joined by a method such as brazing using brazing, Au-tin (Sn) solder, or bonding using a resin adhesive or the like, and used as a negative electrode of a battery. It is preferable that a second metallized layer 1c made of W is formed in advance at a portion where the lid 3 is bonded to the upper surface of the substrate 1, and a Ni layer and an Al layer are deposited on the surface thereof. Thus, the upper surface of the ceramic substrate 1 and the outer peripheral portion of the lid 3 can be joined with high work efficiency by, for example, the seam welding method or the ultrasonic joining method, and the mass productivity is excellent.

  More preferably, in the present invention, as shown in FIG. 1 (a), the lid 3 has a metallized layer 3a of W or the like formed on almost the entire lower main surface of the base 1 side, and an alumina sintered body. It is preferable that the base 1 is made of the same ceramic. The metallized layer 3a is electrically connected to the second metallized layer 1c and joined to the upper surface of the base 1 so as to cover the recess 1a. With this configuration, the upper main surface of the lid 3 is not made conductive, and unnecessary current can be prevented from flowing through the upper surface of the lid 3. Therefore, even if a conductive member contacts the upper main surface of the lid 3, it is possible to effectively prevent problems such as an electrical short circuit from occurring. Further, since the thermal expansion coefficient of the lid 3 is substantially the same as the thermal expansion coefficient of the base body 1, even when heat is applied to the battery case, the stress due to the thermal expansion difference is large at the joint between the base body 1 and the lid body 3. It is possible to prevent the occurrence of breakage such as cracks in the base body 1 and to effectively prevent the breakage of the base body 1 and to provide a battery case having excellent hermetic reliability.

  Next, the battery of the present invention will be described in detail below. FIG. 2 is a cross-sectional view showing an example of an embodiment of the battery of the present invention using the battery case of FIG. Here, B-1 is a positive electrode plate, B-2 is a negative electrode plate, B-3 is an insulating sheet, B-4 is an electrolytic solution, and D is a battery.

  The battery D of the present invention includes a battery case of the present invention, a positive electrode plate B-1 connected to the first metallized layer 1b so as to cover it, and an electrolytic solution B on the upper surface of the positive electrode plate B-1. -4 and the negative electrode plate B-2 placed so as to be in close contact with each other through the insulating sheet B-3 impregnated, and the lower main surface comes into contact with the upper surface of the negative electrode plate B-2 to electrically And a lid 3 joined so as to cover the recess 1a.

The positive electrode plate B-1 is a plate or sheet having a positive electrode active material such as LiCoO ₂ or LiMn ₂ O ₄ and a conductive material such as acetylene black or graphite, and the negative electrode plate B-2 is It is a plate or sheet containing a negative electrode active material made of a carbon material such as coke or carbon fiber.

  The positive electrode plate B-1 is obtained by adding a binder such as polytetrafluoroethylene or polyvinylidene fluoride to the positive electrode active material added with the conductive material, and mixing it to form a slurry. This is a well-known doctor blade method. For example, the sheet is formed into a sheet using, for example, and then cut into a circular shape.

  Similarly, the negative electrode plate B-2 is obtained by adding a binder such as polytetrafluoroethylene or polyvinylidene fluoride to the negative electrode active material and mixing it into a slurry, which is formed into a sheet using a known doctor blade method or the like. Then, the sheet is produced by cutting the sheet into, for example, a circular shape.

  The insulating sheet B-3 is made of a nonwoven fabric made of polyolefin fiber, a microporous membrane made of polyolefin, and the like, impregnated with the electrolytic solution B-4, and the positive electrode plate B-1 and the negative electrode plate B-2. Is disposed between the positive electrode plate B-1 and the negative electrode plate B-2 while preventing direct contact between the positive electrode plate B-1 and the negative electrode plate B-2. B-4 can be moved.

  The electrolytic solution B-4 is injected into the battery D from the upper surface of the recess 1a using an injection means such as a syringe in a container filled with, for example, argon (Ar) gas that hardly contains moisture. And the inside of the battery D can be sealed airtight by airtightly welding the lid 3 to the upper surface of the base body 1 after the injection.

  The electrolytic solution B-4 is obtained by dissolving a lithium salt such as lithium tetrafluoroborate or an acid such as hydrochloric acid, sulfuric acid or nitric acid in an organic solvent such as dimethoxyethane or propylene carbonate.

  Such an electrolytic solution B-4 is highly corrosive and soluble, but by using the battery case of the present invention, the substrate 1 is excellent in chemical resistance. The electrolyte solution B-4 is not easily affected by the electrolyte solution B-4, and impurities dissolved out from the battery case are not mixed in the electrolyte solution B-4 so that the electrolyte solution B-4 is not deteriorated. be able to.

  Further, in the battery case made of stainless steel, which has been conventionally used, as shown in FIG. 3, the positive electrode can 11 and the negative electrode can 12 are integrated by caulking them with a gasket 15 made of polypropylene resin or the like. Because of this caulked portion, the conventional battery A requires a size of about 2 mm in the caulking portion where the positive electrode can 11, the negative electrode can 12, and the separator 14 are combined. In other words, since there is no caulking portion, the outer shape of the battery D can be reduced, which can greatly contribute to downsizing of the portable device. Further, the airtight reliability is high and the mass productivity is excellent.

  Further, the lower main surface of the lid 3 can be brought into contact with the upper surface of the negative electrode plate B-2 to be electrically connected, and the wide surface of the lid 3 and the negative electrode plate B-2 is connected. As a result, the resistance between the negative electrode plate B-2 and the lid 3 can be greatly reduced, and the negative electrode plate B-2 and the lid 3 can be efficiently charged without causing an electrical loss. Since it can be discharged, it is highly reliable and can be charged and discharged stably over a long period of time.

  Note that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, in the present invention, the material of the ceramic base 1 of the battery case has been described as an alumina sintered body, but it may be made of other ceramics such as an aluminum nitride (AlN) sintered body or glass ceramics. In the case of a sintered material, the heat during operation can be efficiently dissipated to the outside.

  INDUSTRIAL APPLICABILITY The present invention can be used as a thin battery case and battery that can be easily connected to an external electric circuit board and can effectively prevent leakage of an electrolytic solution, as used in communication equipment such as a mobile phone.

(A) is sectional drawing which shows an example of embodiment about the battery case of this invention, (b) is a top view of (a). FIG. 2 is a cross-sectional view of a battery using the battery case of FIG. 1, showing an example of an embodiment of the battery of the present invention. It is sectional drawing which shows the example of the conventional battery.

Explanation of symbols

1: Base 1a: Recess 1b: First metallized layer 1c: Second metallized layer 1d: First conductor layer 1e: Second conductor layer 2b: First inner conductor 2c: Second inner conductor 3: Lid 3a: Metallized layer B-1: Positive electrode plate B-2: Negative electrode plate B-3: Insulating sheet B-4: Electrolytic solution

Claims (2)

A rectangular parallelepiped recess is formed in the center of the upper surface, and a base made of ceramics provided with the first conductor layer and the second conductor layer independently of each other on the lower surface, and the first formed on the bottom surface of the recess A metallization layer, a second metallization layer formed around a recess on the upper surface of the base, a first inner conductor formed from the first metallization layer to the first conductor layer, and the first A second inner conductor formed from the second metallized layer to the second conductor layer, and at least a lower main surface of the lid body is electrically connected to the second metallized layer. The battery case is connected to the upper surface of the base body so as to cover the recess. The battery case according to claim 1, a positive electrode plate connected to the first metallization layer so as to cover the first metallization layer, and an upper surface of the positive electrode plate so as to adhere to each other through an insulating sheet impregnated with an electrolyte. A negative electrode plate placed thereon, and a lower main surface in contact with an upper surface of the negative electrode plate to be electrically connected and the lid body joined so as to cover the concave portion. A battery characterized by that.

Images