RU2575480C1 - Layered element, assembled battery, including layered element, and method of assembling layered element - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: layered element includes outer casing, positive electrode, negative electrode, separator, located between positive electrode and negative electrode, and electrically conductive current collector, passing through positive electrode, negative electrode and separator in axial direction of outer casing. Positive electrode, negative electrode and separator are piled in axial direction of outer casing. First electrode, which represents one of positive and negative electrodes, is in contact with inner surface of outer casing, but is not in contact with current collector. Second electrode, which represents the other electrode, is not in contact with outer casing, but is in contact with current collector. Outer edge of second electrode is covered with separator. Peripheral edge of hole, through which current collector passes, in first electrode is covered with separator.

EFFECT: prevention of electric short circuit, improvement of cooling degree and increase of reliability of layered element assembly.

15 cl, 1 tbl, 12 dwg

Description

FIELD OF TECHNOLOGY

[0001] The present invention relates to a laminate. In particular, the present invention relates to a laminated cell with improved cooling characteristics, to an assembled battery including a laminated cell, and to a method for assembling a laminated cell.

BACKGROUND

[0002] Electrode designs of a secondary cell (ie, a secondary chemical current source or battery) are generally divided into two types, i.e. type of spiral winding and layered type. In an element having a design of spiral-wound electrodes (spiral-wound element; relates, for example, to Patent Document 1), a positive electrode and a negative electrode spirally wound with a separator laid between them are placed in the element casing. In an element having a layered type of construction of the electrodes (layered element), a group of electrodes including a positive electrode and a negative electrode, which are alternately stacked with a separator laid between them, are placed in the element casing. Patent Document 2 discloses an element of a cylindrical type in which disc-shaped electrodes are stacked. Patent Document 3 discloses a rectangular type element in which electrodes in the form of a rectangular sheet are stacked.

LIST OF QUOTES

[0003] PATENT LITERATURE

Patent Document 1: JP 2002-198044 A

Patent Document 2: JP 2000-48854 A

Patent Document 3: WO 2008/099609 A

SUMMARY OF THE INVENTION

TECHNICAL PROBLEM

[0004] As for the spiral wound element, a separator with low thermal conductivity is provided in a multilayer form between the surface and the center of the element. As a result of this, even when the surface temperature of the casing of the element is close to room temperature, the temperature of the part near the center of the spiral-wound element becomes quite high.

[0005] The cylindrical layered element disclosed in Patent Document 2 has a structure that allows the accumulation of electricity so that the stacked electrodes come into contact with the respective terminals. Therefore, during the assembly of the layered element of the cylindrical type, there is a probability of failures in the initial period of operation caused by a short circuit between the positive electrode and the negative electrode. In addition, upon repeated charging and discharging, the electrode is repeatedly compressed and expanded. As a result of this, there is a possibility of permanent failures caused by deformation and displacement of the electrode and a short circuit between the positive electrode and the negative electrode.

[0006] The present invention was developed to solve the problems described above, and its object is to suppress the temperature rise inside the cell and to prevent short circuit between the electrodes.

SOLUTION

[0007] To solve the above problem, the layered element according to the present invention includes: a tubular outer casing; positive electrode; negative electrode; a separator located between the positive electrode and the negative electrode; and an electrically conductive down conductor passing through the positive electrode, the negative electrode and the separator in the axial direction of the outer casing. In this case, the positive electrode, the negative electrode and the separator are stacked in the axial direction of the outer casing. The first electrode, which is one of the positive and negative electrodes, comes into contact with the inner surface of the outer casing in order to be electrically connected to the inner surface of the outer casing, but is not in contact with the down conductor. The second electrode, which is the other of the positive and negative electrodes, is not in contact with the inner surface of the outer casing, but comes in contact with the down conductor in order to be electrically connected to the down conductor. The outer edge of the second electrode is covered by a separator. The peripheral edge of the hole through which the collector passes is covered in the first electrode by a separator.

[0008] According to this configuration, the outer casing is made of metal and serves as the collector terminal of the first electrode. The outer dimension of the first electrode is slightly larger than the inner dimension of the tubular outer casing, so that the entire outer periphery of the first electrode or part of its outer periphery is in contact with the inner surface of the outer casing. When the first electrode is placed in the outer casing under pressure, the first electrode tightly comes into contact with the outer casing. Thus, the first electrode is connected to the outer casing with low thermal resistance. Therefore, this configuration is effective in cooling the first electrode.

[0009] In this case, the external size of the electrode refers to the size from the graphic center to the outer periphery of the sheet-like electrode. In the case of a disk-shaped electrode, the outer dimension is called the outer diameter. Similarly, the inner dimension of the outer casing refers to the size between the graphical center on the vertical section of the tubular outer casing in the axial direction and the inner surface of the outer casing. In the case of a cylindrical outer casing, the inner dimension is called the inner diameter.

[0010] The outer dimension of the second electrode is smaller than the inner dimension of the tubular outer casing, so that the second electrode does not come into contact with the outer casing. Therefore, the second electrode is isolated from the outer casing.

[0011] Heat generated from the first electrode is transferred directly to the outer casing. The heat released from the second electrode is transferred to the first electrode through a separator.

[0012] The overall heat transfer coefficient (U1) of the helically wound element is represented by mathematical formula 1, which will be described below. On the other hand, the total heat transfer coefficient (U2) of the laminate according to the present invention is represented by mathematical formula 2. From the comparison between the two coefficients it follows that there is a big difference between them in terms of the term number of turns n. In a spiral wound element, with an increase in the number of turns n, the overall heat transfer coefficient becomes smaller. A detailed description using the substitution of specific numerical values will be given in the following embodiments.

[0013] In the laminate element according to the present invention, as described above, there is no need for a conduit or heat sink to supply cooler to the element to limit the temperature inside the element. Therefore, the structure of the laminate according to the present invention is compact. Moreover, in the laminate element according to the present invention, it is easy to suppress the temperature rise within the element by cooling the surface of the outer casing.

[0014] Each of the positive electrode, negative electrode and separator has an opening formed in its center to allow the passage of the collector through it. A rod down conductor passes through these openings. The hole diameter of the first electrode is larger than the external size of the rod down conductor. Therefore, the first electrode does not come into contact with the down conductor. The hole diameter of the second electrode is smaller than the external size of the rod down conductor. Therefore, the second electrode comes into contact with the down conductor and is electrically connected to the down conductor. The collector is made of metal and serves as the collector of the second electrode. Moreover, the collector is preferably a round rod, but it can be a rectangular rod.

[0015] In addition, with respect to the layered element according to the present invention, in a state in which the electrodes and the separator are stacked, the outer edge of the second electrode is covered by the separator, and the peripheral edge of the hole through which the collector passes in the first electrode is covered by the separator. Therefore, the first electrode and the second electrode are reliably separated from each other by a separator at the outer edge of the second electrode and the peripheral edge of the hole in the first electrode. Therefore, the electrodes do not come into contact with each other on the outer edge of one of the electrodes and on the peripheral edge of the hole in the other electrode due to deformation of the electrodes. In the case of a disk-shaped electrode, the outer diameter of the separator is larger than the outer diameter of the second electrode. Moreover, in the case where the collector is a round rod, the diameter of the hole of the separator is smaller than the diameter of the hole of the first electrode.

[0016] In the laminate according to the present invention, the first electrode is surrounded by a bag-like first separator in a state in which the outer edge of the first electrode protrudes outward from the first separator, and the second electrode is surrounded by a bag-shaped second separator in a state in which the peripheral edge of the hole through which the collector passes , in the second electrode protrudes outward from the second separator. According to this configuration, since the separators are bag-shaped, the separators prevent short circuits between the electrodes due to dust or foreign matter originating from the electrodes.

[0017] In the laminate according to the present invention, the collector has a side surface on which a groove is formed, the diameter of the narrowest part of the collector being larger than the diameter of the hole through which the collector passes in the second electrode, and the diameter of the thickest part of the collector is smaller, than the diameter of the hole through which the collector passes in the first electrode.

[0018] There is a possibility that during assembly of the electrodes, the connection between the collector and the electrode weakens and the close contact between the collector and the electrode is impeded. To solve this problem, the layered element according to the present invention includes a down conductor on which a helical groove is formed. According to this configuration, it becomes possible to maintain a state in which the second electrode is tightly inserted into the down conductor along a helical groove formed on the down conductor. This configuration prevents loosening of the connection between the electrode and the collector during assembly of the laminate.

[0019] In the laminate according to the present invention, the negative electrode comprises a hydrogen storage alloy. In addition, in the layered cell according to the present invention, each of the positive and negative electrodes is an electrode that is charged and discharged, and also is an electrode that provides electrolysis of the electric current held in the laminated cell from the outside. According to this configuration, each of the positive and negative electrodes plays the role of an electrode that is charged and discharged in a secondary element (i.e., in a secondary chemical current source or battery), and the role of an electrode that generates hydrogen gas.

[0020] In the laminate according to the present invention, preferably, the charging capacity of the negative electrode is less than the charging capacity of the positive electrode. Such a layered element is a so-called negative electrode limited element. Here, these charging capacities in some cases are simply referred to as the capacitance of the positive electrode and the capacitance of the negative electrode, respectively.

[0021] The layered element according to the present invention further includes a hydrogen storage chamber located inside the outer casing for storing hydrogen gas released from the negative electrode. Here, the hydrogen storage chamber may be an independent space. Moreover, the hydrogen storage chamber is not an independent space, but can be formed on the lumen in the electrode and on the lumen in the separator.

[0022] In the negative electrode limited by the laminate, as the charge flows, the negative electrode is fully charged before the positive electrode is fully charged. When recharging, in which charging continues from a fully charged state, hydrogen gas is generated on the negative electrode (see reaction formula (1)).

H ⁺ + e ^- → 1 / 2H ₂ (1)

[0023] Gaseous hydrogen released from the negative electrode is accumulated in the hydrogen storage alloy of the negative electrode, serving as an energy source during the discharge. In the case of a positive nickel oxyhydroxide electrode, the reaction formula during the discharge is reaction formula (2).

Negative electrode: 1 / 2H ₂ → H ⁺ + e ^-

Positive electrode: NiOOH + e ^- + H ⁺ → Ni (OH) ₂ (2)

Total NiOOH + 1 / 2H ₂ → Ni (OH) ₂

[0024] Since the hydrogen storage alloy is expensive, a negative electrode substantially affects the price of the cell. In an ordinary secondary element limited by a positive electrode, the amount of materials for a negative electrode is 1.5–2 times greater than for a positive electrode. However, the laminate according to the present invention reduces the amount of expensive negative electrode materials. Therefore, it is possible to obtain an inexpensive layered element.

[0025] In the laminate according to the present invention, the negative electrode is charged so that the hydrogen storage alloy contained in the negative electrode accumulates gaseous hydrogen stored in the hydrogen storage chamber. According to this configuration, the negative electrode is charged with hydrogen gas generated by recharging. Therefore, gaseous hydrogen is effectively disposed of. The hydrogen storage alloy contained in the negative electrode acts as a so-called catalyst.

[0026] In the laminate according to the present invention, preferably, the positive electrode contains manganese dioxide. So far, a positive manganese dioxide electrode has been used for a primary element (i.e., a primary chemical current source), known as a manganese dioxide and zinc element, but has not been used for a secondary element. The reason for this is as follows. Namely, when a positive electrode based on manganese dioxide is discharged to produce manganese hydroxide, trimanganese tetraoxide Mn ₃ O _{4 is formed} , which is not able to recharge. However, the inventors of the present invention have found that irreversible tri-manganese tetroxide does not form upon contact of the positive electrode with oxygen. The inventors of the present invention have successfully used manganese dioxide as a material for the positive electrode of the secondary element by supplying oxygen to the peripheral periphery of the positive electrode.

[0027] In the laminate according to the present invention, the outer casing has a side portion formed in a cylindrical shape. Moreover, the outer casing has convex parts that are dome-shaped at its two axial ends, and a hydrogen storage chamber is provided in each of the convex parts.

[0028] When the charge continues after the negative electrode is fully charged, hydrogen gas is released from the negative electrode. The generated hydrogen gas accumulated in the hydrogen storage chamber is accumulated in the negative electrode during the discharge and is efficiently disposed of. Thus, it becomes possible to reduce the amount of expensive materials for the negative electrode. Therefore, it is possible to produce an inexpensive laminate. A design in which each of the two ends of the cylinder may protrude in a dome shape is suitable for storing high pressure hydrogen gas.

[0029] The assembled battery includes a plurality of laminate cells according to the present invention, and these laminate cells are connected to each other via a columnar metal fitting. Moreover, in each of the laminated elements, the outer casing has a cylindrical body part made of metal and lid parts for closing openings formed at the two axial ends of the body part, and the collector passes through the lid parts. The metal fitting has an upper surface and a lower surface, each of which has a connecting cavity formed on it. The end of the collector in one of the layered elements is inserted into the connecting cavity formed on the upper surface of the metal fitting. The end of the collector in another laminate adjacent to the laminate is inserted into the connecting cavity formed on the bottom surface of the metal fitting, with an insulator inserted between the end and the connecting cavity. The lower surface of the metal fitting is electrically connected to the outer casing in another laminate.

[0030] The lower surface and the upper surface of the metal fitting are able to come into surface contact with the lid portions of the adjacent laminate elements. The insulator is laid between the cavity formed on the lower surface of the metal fitting and the down conductor. Therefore, in two adjacent layered elements, the down conductors are isolated from each other. The collector in one of the laminate elements and the outer casing in the adjacent laminate element are connected to each other through a metal fitting. As a result, adjacent laminate elements are connected in series through a metal fitting.

[0031] The assembled battery includes a plurality of laminate cells according to the present invention. In this case, the outer casing in each of the laminated elements has a container closed at one end having a rectangular cross section and a lid for closing the container opening. The laminate elements are connected to each other so that the container in one of the laminate elements and the lid in the other of the laminate elements adjacent to the laminate element are in surface contact with each other.

[0032] According to this configuration, the lid in one laminate element and the bottom of the container in the adjacent laminate element come into contact with each other so that the two laminate elements are stacked and are electrically connected in series. It becomes possible to increase the voltage at the output of the assembled battery by connecting a large number of layered elements, as described above.

[0033] A method for assembling a layered element according to the present invention includes: a first step of pre-preparing a collector having a side surface on which a helical groove is formed, and a round rod having the same outer diameter as the diameter of the base of the profile of the helical groove on the collector; the second stage of the assembly is a group of electrodes in such a way as to sequentially insert a positive electrode and a negative electrode on a round rod with a separator located between the positive electrode and the negative electrode, and stack the electrodes in a stack; the third stage, carried out after the second stage, the placement of the pressure pads at the two ends of the group of electrodes to hold the group of electrodes and applying pressure to the pressure pads to compress the group of electrodes; the fourth stage of pulling a round rod while maintaining a compressed state; the fifth step of pushing the collector instead of the round rod into the group of electrodes while rotating the collector and then screwing the collector into the screw hole formed in the center of the pressure pad to assemble the electrode assembly while maintaining the compressed state of the group of electrodes; the sixth stage of placing the electrode assembly in the outer casing under pressure; the seventh stage of evacuation of the outer casing; the eighth stage of electrolyte injection into the outer casing; and a ninth step following the eighth step, attaching the cap to the outer casing to seal the outer casing.

FAVORABLE EFFECTS OF THE INVENTION

[0034] According to the present invention, the temperature rise within the cell is suppressed without the need for excessive cooling space. In addition, the laminate according to the present invention prevents short circuits between the electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG. 1 is a drawing illustrating a schematic configuration of a cylindrical type laminate according to a first embodiment, which, in particular, illustrates an axial section.

FIG. 2A is a sectional view illustrating a first electrode and a second electrode, each of which is surrounded by a bag-shaped separator.

FIG. 2B is a plan view illustrating a first electrode surrounded by a bag-shaped separator.

FIG. 2C is a plan view illustrating a second electrode surrounded by a bag-shaped separator.

FIG. 3 is a drawing illustrating a schematic configuration of a tubular type laminate member according to a second embodiment.

FIG. 4A is a drawing illustrating a schematic configuration in a state in which a metal fitting is attached to a tubular type laminate.

FIG. 4B is a drawing illustrating a configuration in the case where the assembled battery is configured with a tubular laminate.

FIG. 5 is a drawing illustrating a schematic configuration of a capsule type laminate according to a third embodiment.

FIG. 6A is a cross-sectional view illustrating in the axial direction a rectangular type laminate according to a fourth embodiment.

FIG. 6B is a plan view illustrating a rectangular type laminate according to a fourth embodiment.

FIG. 7 is a drawing illustrating a configuration in the case where the assembled battery is formed with a rectangular layered cell according to the fourth embodiment.

FIG. 8 is a sectional view schematically illustrating in the axial direction a cylindrical type laminate according to a fifth embodiment of the present invention.

FIG. 9 is a sectional view schematically illustrating a screw structure of a collector.

FIG. 10 is a drawing illustrating an embodiment in which the collector has a structure other than a screw structure.

FIG. 11 is a sectional view illustrating in the axial direction a method of assembling a laminate element.

FIG. 12 is a graph showing test results of temperature increase on a laminate.

DESCRIPTION OF EMBODIMENTS

[0036] Next, with reference to the drawings, a description will be given of embodiments of the present invention; however, the present invention should not be construed as limited by these embodiments.

[0037] Before describing respective embodiments of the present invention, an example of a secondary element (ie, secondary chemical current source or battery) to which the present invention is applied will first be described. The secondary element is not limited to the types described in the respective embodiments, and may be secondary elements such as a nickel-iron element, a zinc-manganese element, and a nickel-cadmium element.

<Nickel Metal Hydride Element>

[0038] The negative electrode contains, as a base material, a hydrogen storage alloy, for example, a lanthanum-nickel alloy. Nickel oxyhydroxide was used as the active material of the positive electrode. As the electrolyte held in the separator, an alkaline aqueous solution was used, such as an aqueous KOH solution, which is commonly used in a nickel metal hydride cell.

[0039] The negative electrode used therein is obtained as follows. Namely, the paste obtained by adding a solvent to a hydrogen storage alloy, an electrically conductive filler and a binder was applied to the substrate so as to form a sheet, and then cured. Similarly, the positive electrode used in it is obtained as follows. Namely, the paste obtained by adding a solvent to the positive electrode active material, an electrically conductive filler and a binder, was applied to the substrate so as to give a sheet shape, and then cured.

[0040] As used herein, the electrically conductive filler was carbon particles. The binder used here was a thermoplastic resin that dissolves in a water-soluble solvent. The substrate used here was an expandable nickel sheet. The separator used here was a polypropylene fiber.

<Manganese Dioxide Element>

[0041] The negative electrode contains a hydrogen storage alloy. The positive electrode contains manganese dioxide as an active material. Used here, the positive electrode and the negative electrode were obtained as follows. Namely, a paste obtained by adding a solvent to an active material, an electrically conductive filler and a binder was applied to a nickel substrate so as to give a sheet shape, and then cured. The electrically conductive filler, binder, separator and electrolyte used here were the same as in the nickel metal hydride cell.

[0042] In a positive electrode of an element based on manganese dioxide, manganese dioxide MnO ₂ is converted to manganese oxyhydroxide MnOOH during the discharge, and then to manganese hydroxide Mn (OH) ₂ . When the positive electrode is discharged to manganese hydroxide, trimanganese tetraoxide Mn ₃ O _{4 is formed} , which is not able to recharge. However, even when manganese dioxide undergoes oxidation during discharge, contact with oxygen allows manganese oxyhydroxide to revert to manganese dioxide. Thus, manganese dioxide does not change to manganese hydroxide, as a result of which irreversible trimanganese tetraoxide is not formed. So, the positive electrode does not contain tri-manganese tetraoxide or contains tri-manganese tetraoxide in an amount of less than 5%, at most. Oxygen gas released from the positive electrode during recharging is accumulated in the cell and used.

<Lithium-ion cell>

[0043] As for the negative electrode, lithium titanate, carboxymethyl cellulose (CMC) and Ketjen carbon black (KS) were first mixed, whereupon a suspension mixture was prepared. Then, this mixture was applied to stainless steel foil, temporarily dried, and then subjected to heat treatment. Thus, a negative electrode was obtained.

As for the positive electrode, lithium-iron phosphate, CMC, activated carbon and KS were first mixed, as a result of which a suspension mixture was prepared. Then, this mixture was applied to stainless steel foil, temporarily dried, and then subjected to heat treatment. Thus, a positive electrode was obtained.

The separator used here was a microporous film made of polypropylene. The electrolyte used here was 1 mol / L LiPF ₆ / EC: DEC. The electrically conductive agent used here was CS.

The binder used here was CMC. The down conductor used here was stainless steel.

<Nickel-zinc element>

[0044] The nickel-zinc cell includes: a negative electrode comprising zinc or a zinc compound; a positive electrode comprising nickel oxide, nickel hydroxide or nickel oxyhydroxide; and an electrolyte containing phosphate in the range from 0.025 M to 0.25 M and free alkali in the range from 4 M to 9 M.

<First Embodiment>

[0045] FIG. 1 is a sectional view schematically in the axial direction of a cylindrical type laminate (hereinafter simply referred to as a laminate) according to a first embodiment of the present invention. As illustrated in FIG. 1, the layered element 11 includes, as main constituent elements, an outer casing 15 , a collector 17 and electrode blocks 13, each of which is enclosed in an outer casing. The outer casing 15 is made with a cylindrical can 12 closed at one end and a disk-shaped lid 16 fixed to the opening 12c of the cylindrical can. Each of the cylindrical cans 12 and the lid 16 is made of iron, but can be made of another metal. The outer diameter of the lid 16 is slightly larger than the inner diameter of the opening 12c of the cylindrical can. After the electrode blocks 13 are enclosed in the outer casing 15, the cover 16 is mounted snugly in the opening 12c of the cylindrical can.

[0046] Each of the electrode blocks 13 is made with a positive electrode 13a containing the active material of the positive electrode, a negative electrode 13b containing a hydrogen storage alloy, and a separator 13c located between the positive electrode 13a and the negative electrode 13b to allow ions to pass through it but preventing the passage of electrons through it. The electrode blocks 13 are stacked axially (in the X direction in FIG. 1) of the cylindrical can 12 and are enclosed in an outer casing 15. The electrolyte (not illustrated) is held in the separator 13c. Each of the positive electrode 13a, the negative electrode 13b and the separator 13c is in the form of a disk with a hole formed in the center. The outer diameter of the negative electrode 13b is smaller than the inner diameter of the cylindrical can 12, so that the outer edge 13bb of the negative electrode is not in contact with the inner surface 12a of the cylindrical can. On the other hand, the outer diameter of the positive electrode 13a is larger than the inner diameter of the cylindrical can 12, so that the outer edge 13ab of the positive electrode is in contact with the inner surface 12a of the cylindrical can, and the positive electrode 13a is electrically connected to the cylindrical can 12. Preferably, the outer diameter of the positive electrode 13a is 100 μm larger than the inner diameter of the cylindrical can 12.

[0047] The collector 17 is made of nickel-plated iron and has a rod-shaped rod portion 17a and a holding portion 17b formed at one end of the rod portion 17a. The nickel plating treatment prevents the collector 17 from being corroded by the electrolyte contained in the separator 13c. The stem part 17a of the collector passes through the center of the electrode unit 13, including the positive electrode 13a, the negative electrode 13b and the separator 13c, in the axial direction (X direction in Fig. 1) of the outer casing 15. The diameter of the hole formed in the center of the negative electrode 13b is smaller than the outer diameter of the stem part 17a. Therefore, the peripheral edge l3ba of the hole of the negative electrode comes into contact with the rod portion 17a, so that the negative electrode 13b is electrically connected to the collector 17. On the other hand, the diameter of the hole formed in the center of the positive electrode 13a is larger than the outer diameter of the rod portion 17a . Therefore, the peripheral edge l3aa of the hole of the positive electrode does not come into contact with the rod portion 17a, so that the positive electrode 13a is electrically isolated from the collector 17.

[0048] The electrode blocks 13 are stacked sequentially on a holding portion 17b of the collector. The holding portion 17b prevents the electrode block 13 from falling off the end of the collector 17 during assembly. The holding portion 17b is disk-shaped. The holding part 17b is located on the bottom 12b of the cylindrical can with the insulating plate 14 inserted between the holding part 17b and the bottom 12b. The insulating plate 14 prevents electrical short circuit caused by direct contact of the collector 17 with the cylindrical can 12. The end of the rod part 17a opposite to the holding part 17b rests on the rod support 18 provided in the center of the cover 16. The rod support 18 is made of insulating material to prevent electrical short circuit between the cover 16 and the pc the shackle part 17a. The rod portion protruding from the cover 16 serves as the terminal 17c of the positive electrode. A cylindrical can 12 serves as the output of the negative electrode.

[0049] Next, a description will be made of the relationship between the dimensions of the positive electrode 13a, the negative electrode 13b and the separator 13c and the dimensions of the outer casing 15 and the collector 17. The outer edge of the separator 13c is covered by the positive electrode 13a (first electrode) and the outer edge of the negative electrode 13b (second electrode) is covered by a separator 13c. Moreover, the peripheral edge of the hole through which the collector 17 passes in the positive electrode 13a is covered with a separator 13c, and the peripheral edge of the hole through which the collector 17 passes in the separator 13c is covered with a negative electrode 13b.

[0050] In other words, the outer diameter of the separator 13c is larger than the outer diameter of the negative electrode 13b (second electrode). Therefore, the positive electrode 13a and the negative electrode 13b are completely separated from each other by a separator 13c in the vicinity of the inner peripheral surface of the outer casing 15. Thus, the electrodes do not come into contact with each other, even when deformed. In addition, the diameter of the hole formed in the center of the separator 13c is smaller than the diameter of the hole formed in the center of the positive electrode 13a. Therefore, the positive electrode 13a and the negative electrode 13b are completely separated from each other by a separator 13c in the vicinity of the outer peripheral surface of the collector 17. Thus, the electrodes do not come into contact with each other, even when deformed. Moreover, the outer diameter of the separator 13c is smaller than the outer diameter of the positive electrode 13a (first electrode). Therefore, the separator 13c is not laid between the positive electrode 13a and the cylindrical can 12. Furthermore, the diameter of the hole formed in the center of the separator 13c is larger than the diameter of the hole formed in the center of the negative electrode 13b. Therefore, the separator 13c is not laid between the negative electrode 13b and the collector 17.

[0051] The outer edge of the positive electrode 13a is brought into contact with the inner surface, which serves as the output of the collector, of the outer casing 15, so that electricity and heat generated by the positive electrode 13a can be transferred to the outer casing 15 with good efficiency. Similarly, the peripheral edge of the hole through which the collector passes in the negative electrode 13b is brought into contact with the collector 17 serving as the output of the collector, so that electricity generated at the negative electrode 13b can be transmitted to the collector 17 with good efficiency.

[0052] The authors of the present invention have adopted a stacked cylindrical element as an electrode structure. Thus, the authors of the present invention have made it possible to transmit the electricity and heat generated by the electrodes to the outer casing and the collector with good efficiency. Thus, the authors of the present invention have realized a layered element with improved cooling characteristics and current-carrying characteristics.

[0053] Next, a description will be given of the functions and effects of the cooling structure in the first embodiment.

The outer edge 13ab of the positive electrode is tightly pressed against the inner surface 12a of the cylindrical can and comes into tight contact with the inner surface 12a of the cylindrical can. The heat generated from the positive electrode 13a is transferred directly to the cylindrical can 12. Moreover, the heat generated from the negative electrode 13b is transferred to the positive electrode 13a through the separator 13c. The thin and single separator 13c does not interfere so much with heat transfer. As described above, the heat generated from each of the electrodes 13a and 13b is transferred to the cylindrical can 12 at a low thermal resistance, so that the temperature increase inside the laminate is suppressed.

[0054] Here, a description will be given of the difference in temperature increase between the laminate element according to an embodiment of the present invention and a standard helically wound element, based on an example calculation. In a spiral wound element, the total heat transfer coefficient (U1) is expressed by mathematical formula 1. On the other hand, in a layered element, the total heat transfer coefficient (U2) is expressed by mathematical formula 2.

[0055] [Mathematical formula 1]

, $$U_{\mathrm{one}}=\mathrm{one}/\left\{\frac{\mathrm{one}}{{\mathrm{<figure-callout\; id="0"\; label="h"\; filenames="00000009.png,00000012.png"\; state="\{\{state\}\}">h</figure-callout>}}_0}+\frac{t}{k}+\left(\frac{\mathrm{one}}{h_{\mathrm{one}}}+\frac{t_{+}}{k_{+}}+\frac{\mathrm{one}}{h_{\mathrm{one}}}+\frac{t_s}{h_s}+\frac{\mathrm{one}}{h_{\mathrm{one}}}+\frac{t_{-}}{h_{-}}\right)n\right\}$$

,

here n is the number of turns; k, k ₊ , k _- , k _s - thermal conductivity; t, t ₊ , t _- , t _s - thickness; h ₀ , h ₁ - laminar layer.

[0056] [Mathematical formula 2]

, $${\mathrm{<figure-callout\; id="2"\; label="U"\; filenames="00000004.png,00000006.png"\; state="\{\{state\}\}">U</figure-callout>}}_2=\mathrm{one}/\left\{\frac{\mathrm{one}}{{\mathrm{<figure-callout\; id="0"\; label="h"\; filenames="00000009.png,00000012.png"\; state="\{\{state\}\}">h</figure-callout>}}_0}+\frac{t}{k}+\frac{\mathrm{one}}{h_{\mathrm{one}}}+\frac{t^{*}}{k^{*}}\right\}$$

,

here k, k ^* is the thermal conductivity; t, t ^* is the thickness; h ₀ , h ₁ - laminar layer.

[0057] In this case, the calculation is made in relation to the element type 18650, used as an example. The spiral wound element has the following parameters.

t = 0.5 mm, t ₊ = t _- = t _s = 10 μm, k = k ₊ = k _- = 40 W · m ^-2 · degree ^-1

h ₀ = 100 W · m ^-2 · degree ^-1 , h ₁ = 1 W · m ^-2 · degree ^-1 , k _s = 1 W · m ^-2 · degree ^-1 ,

n = 9 / 0.03 = 300

Mathematical formula 1, in which these values are substituted, gives U ₁ = 0.0011 W · m ^-2 · degree ^-1 .

[0058] On the other hand, the laminate according to this embodiment has the following parameters.

h ₀ = 100 W · m ^-2 · degree ^-1 , t = 0.5 mm, k = 40 W · m ^-2 · degree ^-1

h ₁ = 10000 W · m ^-2 · degree ^-1 , t ^* = 0.009 m, k * = 40 W · m ^-2 · degree ^-1

Therefore, mathematical formula 2, in which these values are substituted, gives U ₂ = 100 W · m ^-2 · degree ^-1 .

[0059] A comparison between the two examples indicates that the laminate according to an embodiment of the present invention excels in heat transfer by about 100,000 times the standard spiral wound element.

[0060] A description will now be made of a modified example of the first embodiment. In particular, in this modified example, a bag-shaped separator is adopted.

FIG. 2A is a sectional view illustrating electrodes surrounded by a bag-shaped separator. For simplicity, FIG. 2A illustrates one positive electrode 13a and one negative electrode 13b. The positive electrode 13a is surrounded by a bag-shaped separator l3ca, with the exception of the outer edge. Moreover, the negative electrode 13b is surrounded by a bag-shaped separator 13cb, with the exception of the peripheral edge of the hole through which the collector passes.

[0061] FIG. 2B is a plan view illustrating a positive electrode 13a (first electrode) surrounded by a bag-shaped separator. FIG. 2C is a plan view illustrating a negative electrode 13b (second electrode) surrounded by a bag-shaped separator.

[0062] The positive electrode 13a is placed between two separators, each of which has an outer diameter that is smaller than the outer diameter of the positive electrode 13a, and a hole diameter that is larger than the diameter of the hole of the positive electrode 13a, and overlapping parts in the two separators (the edges of the holes) are connected to each other by heat welding. Thus, a positive electrode 13a is formed, surrounded by a bag-shaped separator 13ca. The negative electrode 13b is placed between two separators, each of which has an outer diameter that is larger than the outer diameter of the negative electrode 13b, and a hole diameter that is smaller than the diameter of the hole of the negative electrode 13b, and overlapping parts in the two separators (external peripheral parts) are connected to each other by thermal welding. Thus, a negative electrode 13b is formed, surrounded by a bag-shaped separator 13cb.

[0063] Dust or foreign matter generated from the electrodes during transport of the cell and during assembly of the cell is trapped inside the bag-shaped separator. A bag-shaped separator prevents the ingress of dust or foreign matter originating from the electrodes between the electrodes and between the electrode and the collector terminal. Therefore, an internal short circuit does not occur. In addition, the bag-shaped separator is prevented from getting between the positive electrode 13a and the cylindrical can 12 and between the negative electrode 13b and the collector 17 due to the location of the separators outside the correct location.

<Second embodiment>

[0064] FIG. 3 is a sectional view schematically in the axial direction of a tubular type laminate element (hereinafter simply referred to as a laminate element) according to a second embodiment of the present invention. As illustrated in FIG. 3, the laminate element 21 has almost the same structure as the laminate element 11 illustrated in FIG. 1, with the exception of part of the outer casing and part of the collector. In particular, the outer casing 25 is made with a round pipe 22 and disk-shaped covers 26 fixed to the openings 22b formed at the two ends of the round pipe 22. The collector 27 passes through the cover 26 and rests on the cover 26. Hereinafter, the difference will mainly be described. between the layered element 21 and the layered element 11.

[0065] The electrode blocks 23, each of which is provided with a positive electrode 23a, a negative electrode 23b and a separator 23c, are successively stacked in such a state that the stem portion 27a of the collector passes through them. The collector 27 is supported by rod supports 28 formed in the centers of the covers 26, respectively, at its two ends 27b. Each of the rod supports 28 is made of insulating material to prevent an electrical short circuit between the cover 26 and the collector 27. Each of the ends 27b of the collector 23 protruding from the covers 26 serves as a negative electrode terminal. The round tube 22 serves as the terminal of the positive electrode.

[0066] Next, a description will be given of an assembled battery including a laminate 21. FIG. 4A illustrates a state in which a metal fitting 29 is attached to the laminate element 21. The metal fitting 29 is located between the laminate element 21 and the adjacent laminate element 21 ′ so as to be brought into surface contact with the cover 26 of the laminate element 21. The metal fitting 29 is made of metal columnar shape, but it can be made of metal in the shape of a prism. The axial direction of the metal fitting 29 corresponds to the axial direction (X direction in FIG. 4A) of the collector 27. The metal fitting 29 has an upper surface 29a (left side in the figure), and a cavity 29aa is formed in the center of the upper surface 29a in a vertical direction to the upper surface 29a. The cavity 29aa allows the down conductor 27 ′ of the adjacent laminate element 21 'to enter therein. The metal fitting 29 also has a lower surface 29b (the right side in the figure), and a cavity 29ba is formed in the center of the lower surface 29b in a vertical direction to the lower surface 29b. The cavity 29ba allows the insulating part 24 to enter into it. Moreover, in the center of the insulating part 24, a cavity 24a is formed in a vertical direction to the lower surface 29b. The cavity 29a allows it to enter the stem portion 27b of the collector in the laminate 21. The lower surface 29b of the metal fitting is in surface contact with the cover 26 of the laminate, so that the laminate 21 and the adjacent laminate 21 ′ are electrically connected to each other through a metal fitting 29. In this case, the insulating part 24 prevents an electrical short circuit caused by the contact of the collector 27 with the outer casing 25.

[0067] As illustrated in FIG. 4B, it is possible to obtain an assembled battery 20 in which the laminate elements are connected in series by connecting adjacent laminate elements 21 to each other using a metal fitting 29.

<Third Embodiment>

[0068] FIG. 5 is a sectional view schematically in the axial direction of a capsule type laminate (hereinafter simply referred to as a laminate) according to a third embodiment of the present invention. Layered element 31 includes, as main constituent elements, an outer casing 35, a collector 37 and electrode blocks 33, each of which is enclosed in an outer casing. The external casing 35 is made with a cylindrical external structural unit 32 closed at one end and a cover 36 fixed to the opening 32c of the external structural unit 32. Both the external structural unit 32 and the cover 36 are made of nickel-plated iron, but can be made of metal, such as aluminum or titanium.

[0069] The external structural unit 32 has a tubular side portion 32a and a convex portion 32b that protrudes in a dome shape at its bottom, and a cover 36 also has a tubular side portion 36a and a convex portion 36b that protrudes in a dome shape at its bottom. The outer diameter of the side portion 36a of the lid is smaller than the inner diameter of the opening 32c of the external component 32. The opening 32c is closed by the cover 36 in such a way that the convex part 36b extends outward from the opening 32c of the external component. The cover 36 is connected to the external structural unit 32 by means of an insulating sealing part 38. The insulating sealing part 38 plays the role of electrical insulation of the external structural unit 32 from the cover 36, and also plays the role of forming a sealed space inside the external casing 35 by sealing the associated part. The insulating sealing part 38 is made of a material having insulating properties and compaction properties, such as asphalt-resinous substances.

[0070] Each of the electrode blocks 33 is made with a positive electrode 33a containing the active material of the positive electrode, a negative electrode 33b containing a hydrogen storage alloy, and a separator 33c located between the positive electrode 33a and the negative electrode 33b to allow ions to pass through it but prevent the passage of electrons through it. Moreover, the electrode blocks 33 are stacked in the axial direction (X direction in FIG. 5) of the external structural unit 32 and are enclosed in the outer casing 35. The electrolyte is held in the separator 33c. Each of the positive electrode 33a, the negative electrode 33b and the separator 33c is in the form of a disk with a hole formed in the center. Moreover, the outer diameter of the positive electrode 33a is smaller than the inner diameter of the external structural unit 32, so that the outer edge 33aa of the positive electrode is not in contact with the inner surface 32aa of the external structural unit. On the other hand, the outer diameter of the negative electrode 33b is larger than the inner diameter of the outer structural unit 32, so that the outer edge 33ba of the negative electrode is in contact with the inner surface 32aa of the outer structural unit 32, and thus, the negative electrode 33b is electrically connected to the outer assembly 32. Preferably, the outer diameter of the negative electrode 33b is 100 μm larger than the inner diameter of the outer assembly 32.

[0071] The collector 37 is made of electrically conductive nickel-plated iron and has a rod-shaped rod portion 37a and a holding portion 37b attached to one end of the rod portion 37a. The rod portion 37a of the collector 37 passes through the center of the electrode unit 33 made with the positive electrode 33a, the negative electrode 33b and the separator 33c, in the axial direction (X direction in Fig. 5) outer casing 35. The diameter of the hole formed in the center of the positive electrode 33a is smaller than the outer diameter of the rod portion 37a. Therefore, the peripheral edge 33ab of the hole of the positive electrode comes into contact with the rod portion 37a, so that the positive electrode 33a is electrically connected to the collector 37. On the other hand, the diameter of the hole formed in the center of the negative electrode 33b is larger than the outer diameter of the rod portion 37a . Therefore, the peripheral edge 33bb of the hole of the negative electrode is not in contact with the rod portion 37a.

[0072] The electrode blocks 33 are arranged in series in a stack on the holding portion 37b of the collector. Here, the holding portion 37b prevents the electrode block 33 from falling off from the end of the collector 37. The clamping blocks 34a, each of which is made of insulating material, are located at the two ends of the stacked electrode blocks 33 and protect the electrode blocks 33 from damage when stacking the electrode blocks 33 on top of each other friend and their compression (prepressing). The pressure pad 34a is preferably made of a material that is suitably used as an insulating material and a structural material, and is made of polypropylene. The holding portion 37b is disk-shaped. The holding portion 37b is not in contact with the convex portion 32b at the bottom of the external component. Therefore, the holding portion 37b and the external structural unit 32a are electrically isolated from each other. Opposite the holding portion 37b, the end portion 37c of the stem portion extends through an opening 36c formed in the center of the cover 36 and protrudes outward (rightward in the figure) from the cover 36. The end 37c protruding from the cover 36 serves as a lead of the positive electrode. External structural unit 32 serves as the output of the negative electrode.

[0073] Hydrogen accumulation chambers 39 are provided in the interior spaces of the convex portions 32b and 36b. More specifically, the hydrogen storage chamber 39 is located in a space that is formed by the inner surface 32ba, 36ba of the convex portion and the electrode unit 33, in the outer casing.

[0074] The negative electrode 33b comprises a hydrogen storage alloy. The charging capacity of the negative electrode 33b is smaller than the charging capacity of the positive electrode 33a. Hydrogen gas released from the negative electrode due to recharging accumulates in the hydrogen storage chamber 39. The hydrogen gas accumulated in the hydrogen storage chamber 39 is accumulated by the hydrogen storage alloy, whereby the negative electrode 33b is charged.

<Amount of active material>

[0075] In the laminate according to this embodiment of the present invention, the capacity of the positive electrode is 1000 mAh. The capacity of the negative electrode corresponds to 80% of the capacity of the positive electrode.

[0076] In the negative electrode limited element on the negative electrode, gaseous hydrogen is generated in the charge state. In other words, a charge of up to 800 mAh or more causes the release of gaseous hydrogen from the negative electrode (see reaction formula (1)). The released gaseous hydrogen accumulates in the negative electrode. Hydrogen gas that does not accumulate in the negative electrode accumulates in the gap formed inside the cell. Providing a hydrogen gas storage chamber in the element allows the element to accumulate and accumulate hydrogen gas in a larger amount. When gaseous hydrogen is generated in large quantities, the pressure in the cell increases. Each of the laminated elements according to the first to third embodiments has a sealed structure. Therefore, the accumulated gaseous hydrogen does not leak from the element.

[0077] As for the discharge of the layered element, the hydrogen accumulated in the negative electrode is "discharged" from the hydrogen storage alloy in the form of hydrogen ions and electrons. However, gaseous hydrogen accumulated and accumulated in the layered element accumulates in the hydrogen storage alloy, whereby the charged state of the negative electrode is maintained (see reaction formula (2) during discharge). As described above, hydrogen gas is not useless since hydrogen gas is used as an energy source during discharge. The hydrogen storage alloy acts as a so-called catalyst. Therefore, the change in the volume of the negative electrode during charge and discharge is quite small. This leads to preventing degradation of the negative electrode and to prolonging the life of the cell.

[0078] Here, the electrode plays the role of an electrode that is charged and discharged in a standard secondary cell (battery). In addition, the electrode also plays the role of an electrode that electrolyzes the water contained in the electrolyte to form hydrogen gas.

[0079] The price of the negative electrode, which is expensive, is 80% of the total price of the electrodes. The element limited by the positive electrode requires negative electrodes, which are 1.7 times larger than the positive electrodes. However, according to the present invention, the number of negative electrodes is reduced to 80% relative to the number of positive electrodes. Thus, it becomes possible to halve the price of the electrodes. Even when the number of negative electrodes is reduced, when using the gaseous hydrogen accumulated during recharging, the capacity of the cell does not decrease.

<Fourth Embodiment>

[0080] With reference to an axial sectional view of FIG. 6A, a rectangular type laminate (hereinafter simply referred to as a laminate) will be described according to a fourth embodiment of the present invention. Laminate element 71 includes, as main constituent elements, an outer casing 75 , down conductors 77 and electrode blocks 74, each of which is enclosed in an outer casing. The outer casing 75 is made with a body part 72 and a cover part 73. The body part 72 is a rectangular container closed at one end. The opening 72c of the housing part 72 is closed by a lid 73 so that a sealed space can be formed inside the housing part 72. Each of the body part 72 and the cover 73 is made of iron. As illustrated in the plan view of FIG. 6B, the laminate 71 is generally rectangular in shape.

[0081] Each of the electrode blocks 74 is provided with a positive electrode 74a containing the active material of the positive electrode, a negative electrode 74b containing the hydrogen storage alloy, and a separator 74c located between the positive electrode 74a and the negative electrode 74b to allow ions to pass through it but preventing the passage of electrons through it. The separator 74c plays the role of preventing a short circuit between the positive electrode 74a and the negative electrode 74b and the role of electrolyte retention. The positive electrode 74a and the negative electrode 74b are stacked in the axial direction (Y direction in FIG. 6A) of the body part 72 with the separator 74c laid between them and enclosed in an outer casing 75. Each of the positive electrode 74a, the negative electrode 74b and the separator 74c is shaped sheet. The outer dimension of the negative electrode 74b is smaller than the inner dimension of the body part 72, so that the outer edge 74bb of the negative electrode is not in contact with the inner surface 72a of the body part. On the other hand, the outer dimension of the positive electrode 74a is larger than the inner dimension of the housing part 72, so that the outer edge 74ab of the positive electrode is in contact with the inner surface 72a of the housing part 72 under pressure, and thus the positive electrode 74a is electrically connected to body part 72. Therefore, since the heat released from the electrode block 74 is transferred to the body part 72 with a small temperature gradient, the temperature rise of the electrode block 74 is suppressed. Preferably, the outer dimension of the positive electrode 74a is 100 microns larger than the inner dimension of the body part 72.

[0082] Each of the down conductors 77 is made of electrically conductive nickel-plated iron. Moreover, the collector 77 has an inverted cone-shaped countersunk portion 77b and a stem 77a following the countersunk portion 77b, and generally takes the form of a countersunk screw.

[0083] The electrodes 74b and 74a respectively have holes 74ba and 74aa through which the stem portion 77a of the collector 77 passes. The diameter of the hole 74ba formed on the negative electrode 74b is smaller than the outer diameter of the rod portion 77a, so that the negative electrode 74b is included contact with the rod portion 77a, and thus the negative electrode 74b is electrically connected to the collector 77. On the other hand, the diameter of the hole 74aa formed on the positive electrode 74a is larger than the outer diameter of the rod portion 77a, so that the positive electrode 74a is not in contact with the stem portion 77a.

[0084] Four down conductors 77 (see FIG. 6B) are connected to each other via a connection plate 77d located under the electrode blocks 74. In other words, the screw portion 77c formed at the lower end 77ca of the down conductor is screwed into the screw hole 77da formed on the connection plate 77d, so that the collector 77 is connected to the connection plate 77d. The electrode blocks 74 are arranged sequentially laid on the connection plate 77d, and the connection plate 77d prevents the electrode blocks 74 from falling off the end of the collector 77. Between the bottom 72b of the housing part and the connection plate 77d, an insulating plate 76b is arranged to prevent an electrical short circuit between the collector 77 and the case part 72 due to the contact of the connecting plate 77d with the bottom 72b of the body part. In particular, the connecting plate 77d is surrounded by an insulating plate 76b made of polypropylene.

[0085] The cover 73 has a partly flat plate 73a and a curved part 73b that is curved at right angles to the partly flat plate. Inside the curved portion 73b and on the opening 72c of the body part, an insulating plate 76a is arranged. The insulating plate 76a prevents electrical short circuits between the uppermost electrode unit 74 and the cover 73. On the opposite cover 73 of the surface of the insulating plate 76a, a groove 76aa is formed so that the outer edge of the opening of the body part 72 fits into it. Between the groove 76aa and the outer edge of the opening of the body part 72, a sealing part 80 made of asphalt-resinous materials is located so as to maintain tightness inside the outer casing 75. For simplicity, a sealing part 80 made of asphalt-resinous materials is also located on the hole, through which extends the rod portion 77a of the collector in the insulating plate 76a.

[0086] The cover 73 is connected to the connection plate 77d by a down conductor 77 acting as a countersunk screw. The housing part 72 serves as the terminal of the positive electrode, and the cover 73 serves as the terminal of the negative electrode.

<Assembled Battery>

[0087] FIG. 7 is a drawing illustrating a schematic configuration in the case where the assembled battery 70 is configured with a plurality of laminate elements 71. These laminate elements 71 are connected in series so that the flat plate portion 73a of the lid in one of the laminate elements 71 is opposite and brought into a surface contact with the bottom 72b of the housing part in the adjacent laminate. Connected sequentially laminated elements 71 are placed between the positive electrode output panel 78a and the negative electrode output panel 78b to form an assembled battery 70. More specifically, the positive electrode output panel 78a that is in surface contact with the housing part 72 and the negative electrode output panel 78b, which comes in surface contact with the lid 73, is located inside the housing 70a. Then, a plurality of laminate elements 71 are enclosed between the positive electrode output panel 78a and the negative electrode output panel 78b to form the assembled battery 70. External cold air is supplied to the housing 70a by the suction fan 79a and the exhaust fan 79b to cool the assembled battery 70. The output power from the assembled battery 70 removed from the positive electrode output panel 78a and the negative electrode output panel 78b through a cable (not illustrated).

<Fifth Embodiment>

[0088] FIG. 8 is a sectional view schematically illustrating in the axial direction a cylindrical type laminate element (hereinafter simply referred to as the laminate element) according to the fifth embodiment. Laminate element 90 includes, as main constituent elements, a cylindrical can 92, a collector 17 and electrode blocks 93, each of which is enclosed in a cylindrical can. Each of the electrode blocks 93 is made with a positive electrode 93a, a negative electrode 93b and a separator 93c located between the positive electrode 93a and the negative electrode 93b. The electrode blocks 93 are arranged sequentially stacked on top of each other on a clamping pad 98b located below the collector 97, and the clamping pad 98b prevents the electrode blocks 93 from falling off the end of the collector 97. The clamping pad 98b is a disk-shaped nickel-steel plate. A clamping pad 98a is located at the uppermost of the stacked electrode blocks 93, and the electrode blocks 93 can be compressed by the clamping blocks 98a and 98b.

[0089] The electrode blocks 93 are inserted into the cylindrical can 92 in the axial direction (X direction in FIG. 8) of the cylindrical can 92. The outer diameter of the positive electrode 93a is smaller than the inner diameter of the cylindrical can 92, so that the outer edge 93ab of the positive electrode is not included in contact with the inner surface 92a of the cylindrical can. On the other hand, the outer diameter of the negative electrode 93b is larger than the inner diameter of the cylindrical can 92, so that the outer periphery 93bb of the negative electrode comes into contact with the inner surface 92a of the cylindrical can 92, and the negative electrode 93b is electrically connected to the cylindrical can 92. the opening of the cylindrical can 92 is closed by the lid 96. Between the lid 96 and the cylindrical can 92 is an insulating part 99 to prevent electrical short circuit, causing removable contact of the lid 96 with a cylindrical can 92.

[0090] At the bottom 92b of the cylindrical can, an insulating sheet 94 is arranged to prevent an electric short circuit between the collector 97 and the cylindrical can 92 due to one end 97b of the collector coming into direct contact with the bottom 92b of the cylindrical can. A connecting plate 91 is attached to the other end of the collector 97, which has the shape of a plate curved downward and made of an elastic material. The end 91a of the connecting plate comes into contact with the bottom surface 96b of the cover and is pressed down by the cover 96. Thus, the collector 97 and the cover 96 are electrically connected to each other through the connecting plate 91. The protrusion 96a formed in the center of the cover 96 serves as a positive terminal electrode. In addition, the cylindrical can 92 serves as the output of the negative electrode.

[0091] This embodiment is different from each of the above embodiments with respect to a portion of the collector design. A distinction will be made here. FIG. 9 is a partial sectional view schematically illustrating the relationship between the collector 97 and the electrode unit 93. As illustrated in FIG. 9, the collector 97 has a side surface formed in the form of a screw portion 97c, which has helical grooves in which the base of the profile has a diameter d and the top of the profile has a diameter D (d <D).

[0092] As illustrated in FIG. 9, the diameter of the hole 93aa formed on the positive electrode 93a is smaller than the diameter (d) of the profile base of the screw portion 97c, so that the positive electrode 93a is screwed into the rod portion 97a of the collector and comes into tight contact with the collector 97. Thus, the positive electrode 93a is electrically connected to the collector 97. On the other hand, the diameter of the hole 93ba formed on the negative electrode 93b is larger than the diameter (D) of the profile tip of the screw portion 97c, so that the negative electrode 93b does not come into contact with the rod portion 97a down conductor. Thus, the negative electrode 93b is electrically isolated from the collector 97.

[0093] It becomes possible to satisfactorily guarantee contact between the positive electrode 93a and the collector 97 due to the fact that the diameter of the hole formed on the positive electrode 93a is made smaller than the outer diameter of the profile base of the screw portion of the collector 97. The helical grooves formed on the collector 97 prevent the weakening of the connection between the collector and the electrode during assembly of the electrode and provide tight contact between the collector and the electrode. That is, the tightly fitted state is maintained in such a way that the positive electrode 93a is mounted on the screw portion formed on the collector 97. Thus, it becomes possible to guarantee the state of contact of the electrode with the collector, even when the electrode becomes deformed during charge and discharge. Moreover, in addition to this embodiment, the down conductor with helical grooves is also applicable in the first to fourth embodiments.

[0094] FIG. 10 is a plan view (left side of FIG. 10) and a side view (right side of FIG. 10) illustrating a collector according to another embodiment. The down conductor 97 ′ has a lateral surface on which in the axial direction, V-grooves are formed entirely along the entire circumference, and their cross section has the shape of a saw tooth. Since the cross section of the collector is in the form of saw teeth, the contact area of the collector with the electrode becomes large. When bringing the electrode into tight contact with the collector in the axial direction under pressure, the electrode slides along the grooves formed on the collector. As a result of this, an improper contact between the electrode and the collector is less likely to occur. Even when the electrode becomes deformed during charge and discharge, the electrode is not damaged, since the electrode slides along the grooves of the collector.

[0095] With reference to FIG. 11, a description will now be made of a method for assembling a laminate according to the present invention. The electrode blocks 93 are stacked so that the positive electrode 93a and the negative electrode 93b are in series, with a separator 93c laid between them, worn on a round rod 95 with an outer diameter (d ′), which is slightly smaller than the base of the profile of each screw grooves formed on the lateral surface of the collector 97. Then, the electrode blocks 93 are stacked in predetermined sets (bags), and the pressure pads 98a and 98b are placed respectively at the two ends of the electrode blocks 93 to hold spp of electrodes, as a result of which the electrode set A is assembled (see the left side in Fig. 11).

[0096] Then, the group of electrodes is compressed by the pressure pads 98a and 98b, and the round rod 95 is pulled while maintaining the compressed state. Instead of a round rod 95, a collector 97 is pressed into the group of electrodes, which is held by the clamping blocks 98a and 98b and to which pressure is applied by rotating it. Then, the pressure pads 98a and 98b are screwed onto the collector 97 and the electrode assembly B is assembled in a state in which the group of electrodes is completely compressed (the right side in Fig. 11). Then, the electrode assembly B is placed in a cylindrical can 92 under pressure, the cylindrical can 92 is vented and the electrolyte is injected into the cylindrical can 92. After the electrolyte is injected, the lid 96 is fixed to the opening of the cylindrical can 92 and thus the opening of the cylindrical can 92 is closed, so that the layered the element becomes hermetically sealed.

<Test Results>

[0097] The laminate according to the fifth embodiment of the present invention was charged with a current of 0.5C to 8C, and after full charge, the internal temperature and the surface temperature of the laminate were measured. As for the method of measuring temperature, the internal temperature was measured using a thermocouple attached to the center of the collector. In addition, the surface temperature was measured using a thermocouple attached to the surface of the outer casing of the layered element. The measurement was carried out in a state in which the room temperature was set at 15 ° C, and the layered element was blown by means of a fan with air at a speed of 1 m / s.

[0098] Table 1 shows the results of measuring the temperature of the cell after the laminate has been charged so that the state of charge is 100% for each charging current (0.5C, 1C, 2C, 5C, 8C). In Table 1, the left column shows the largest difference between the surface temperature of the element and room temperature (= measured temperature - room temperature), and the right column shows the largest difference between the internal temperature of the element and room temperature (= core temperature - room temperature). At each of the charging currents, the difference between the temperature of the cell and room temperature rapidly increased when the state of charge exceeds 80%. At a charging current of 2C or less, each of the differences in the cell temperatures (measured temperature - room temperature, core temperature - room temperature) was less than 5 ° C. At a charging current of 8C, each of these temperature differences was less than 30 ° C.

[0099]

[Table 1] Maximum temperature difference Charging current Measured temperature - room temperature (° C) Core Temperature - Room Temperature (° C) 0.5C 1,57 2,3 1C 2.2 3,1 2C 2.27 4.2 5C 6.87 11.7 8C 13.8 28.7

[0100] FIG. 12 is a graph illustrating the difference between the internal temperature of an element after a charge and room temperature, with the values of the respective charging currents taken as parameters. In FIG. 12, the vertical axis represents the temperature difference, taken on a scale of degrees Celsius, and the vertical axis represents the elapsed time taken in minutes. It can be seen from the graph that the difference between the internal temperature of the element and room temperature (temperature increase) at a charging current of 2C or less is 4 ° C or less, which is quite small. The reason for this is considered to be as follows. Namely, the heat does not accumulate in the element, since heat emission during charge and heat dissipation are well balanced.

[0101] It should be noted that there is a difference between the internal temperature of the cell and room temperature at a charging current of 5C and a charging current of 8C. However, the difference between the internal temperature of the element and room temperature is reduced to less than 5 ° C in less than 20 minutes. From this result it follows that the element has quite excellent heat dissipating properties.

[0102] From the test results, it was obvious that the laminate according to the present invention has a large internal thermal conductivity, and the internal temperature of the element decreases in a short time, even when the temperature rises due to charge.

INDUSTRIAL APPLICABILITY

[0103] The laminate element according to the present invention can be suitably used as a consumer power storage device, in addition to an industrial power storage device.

[0104] LIST OF REFERENCES

11 - Layer element of a cylindrical type

12 - Cylindrical can (a: inner surface of the side)

13 - Electrode block (a: positive electrode, b: negative electrode, c: separator)

14 - Insulation plate

15 - External casing

16 - Cover

17 - Down conductor (a: rod part, b: holding part, c: positive electrode terminal)

19 - The hydrogen storage chamber

20 - Assembled battery

21 - The layered element of the tubular type

22 - Round pipe

23 - Electrode block

24 - Insulating part

25 - External casing

26 - Cover

27 - Down conductor

29 - Metal fitting

31 - element capsule type

32 - External structural unit (a: side part, b: convex part)

33 - Electrode block (a: positive electrode, b: negative electrode, c: separator)

35 - External casing

36 - Cover

37 - Down conductor (a: stem part, b: retaining part, c: end)

38 - Insulating sealing part

39 - hydrogen storage chamber

70 - Assembled Battery

71 - Laminate element of a rectangular type

72 - Body part

73 - Cover

74 - Electrode block

75 - External casing

76 - Insulation plate

77 - Down conductor

79 - Fan

91 - Connecting plate

92 - Cylindrical can

93 - Electrode block

94 - Insulating sheet

95 - Round rod

96 - Cover

97 - Down conductor

98 - Pressure block

99 - Insulating part.

Claims (15)

1. A layered element containing:
tubular outer casing;
positive electrode;
negative electrode;
a separator located between the positive electrode and the negative electrode; and
an electrically conductive down conductor passing through the positive electrode, the negative electrode and the separator in the axial direction of the outer casing, while
the positive electrode, the negative electrode and the separator are stacked in the axial direction of the outer casing,
the first electrode, which is one of the positive and negative electrodes, comes into contact with the inner surface of the outer casing so as to be electrically connected to the inner surface of the outer casing, but is not in contact with the down conductor,
the second electrode, which is the other of the positive and negative electrodes, is not in contact with the inner surface of the outer casing, but comes into contact with the down conductor in order to be electrically connected to the down conductor,
the outer edge of the separator is covered by the first electrode,
the peripheral edge of the hole through which the collector passes, in the separator is covered by a second electrode,
the outer edge of the second electrode is covered by a separator, and
The peripheral edge of the hole through which the collector passes is covered in the first electrode by a separator. 2. The layered element according to claim 1, wherein
the first electrode is surrounded by a bag-like first separator in a state in which the outer edge of the first electrode protrudes outward from the first separator, and
the second electrode is surrounded by a bag-shaped second separator in a state in which the peripheral edge of the hole through which the collector passes in the second electrode protrudes outward from the second separator. 3. The layered element according to claim 1, wherein
the down conductor has a lateral surface on which a groove is formed,
the diameter of the narrowest part of the collector is larger than the diameter of the hole through which the collector passes in the second electrode, and
the diameter of the thickest part of the collector is smaller than the diameter of the hole through which the collector passes in the first electrode. 4. The layered element according to claim 1, wherein
the negative electrode contains a hydrogen storage alloy. 5. The layered element according to claim 4, wherein
each of the positive and negative electrodes is an electrode that is charged and discharged, and also represents an electrode that provides electrolysis of the electrolyte held in the laminate element, supplied externally by an electric current. 6. The layered element according to any one of paragraphs. 4 and 5, while
the charge capacity of the negative electrode is less than the charge capacity of the positive electrode. 7. The layered element according to claim 6, further comprising:
a hydrogen storage chamber located inside the outer casing for storing hydrogen gas released from the negative electrode. 8. The layered element of claim 7, wherein
the negative electrode is charged in such a way that the hydrogen storage alloy alloy contained in the negative electrode accumulates hydrogen gas accumulated in the hydrogen storage chamber. 9. The layered element according to any one of paragraphs. 4 and 5, while
the positive electrode contains manganese dioxide. 10. The layered element of claim 7, wherein
the outer casing has a side portion formed with a cylindrical shape,
the outer casing has convex parts that are dome-shaped at its two axial ends, and
a hydrogen storage chamber is provided in each of the convex parts. 11. An assembled battery containing a plurality of laminated cells according to claim 1, connected to each other through a columnar metal fitting, wherein
in each of the laminated elements, the outer casing has a cylindrical body part made of metal and lid parts for closing openings formed at the two axial ends of the body part, and the collector passes through the lid parts,
metal fittings have an upper surface and a lower surface, each of which has a connecting cavity formed on it,
the end of the collector in one of the layered elements is inserted into the connecting cavity formed on the upper surface of the metal fitting,
the end of the collector in another of the laminate elements adjacent to the laminate element is inserted into the connecting cavity formed on the lower surface of the metal fitting, with an insulator laid between the end and the connecting cavity, and
the bottom surface of the metal fitting is electrically connected to the outer casing in another laminate. 12. An assembled battery containing a plurality of laminated cells according to claim 1, wherein
the outer casing in each of the laminate elements has a container closed at one end having a rectangular cross section and a lid for closing the container opening, and
the laminate elements are connected to each other so that the container in one of the laminate elements and the lid in another of the laminate elements adjacent to the laminate element are in surface contact with each other. 13. A method of assembling a layered element, comprising:
the first stage of preliminary preparation of the down conductor having a side surface on which a helical groove is formed, and a round rod having a smaller outer diameter than the diameter of the base of the profile of the helical groove on the down conductor;
the second stage of assembling the group of electrodes in such a way as to sequentially insert a positive electrode and a negative electrode on a round rod with a separator laid between the positive electrode and the negative electrode and stack the electrodes in a stack;
the third stage, carried out after the second stage, the placement of the pressure pads at the two ends of the group of electrodes to hold the group of electrodes and applying pressure to the pressure pads to compress the group of electrodes;
the fourth stage of pulling a round rod while maintaining a compressed state;
the fifth stage of pushing the collector instead of a round rod into the group of electrodes when rotating the collector, and then screwing the collector into the screw hole formed in the center of the pressure pad to assemble the electrode assembly while maintaining the compressed state of the group of electrodes;
the sixth stage of placing the electrode assembly in the outer casing under pressure;
the seventh stage of removing air from the outer casing;
the eighth step of injecting the electrolyte solution into the outer casing; and
the ninth stage, carried out after the eighth stage, attaching the cover to the outer casing to seal the outer casing. 14. The layered element according to claim 1, wherein
the first electrode is surrounded by a bag-like first separator in a state in which the outer edge of the first electrode protrudes outward from the first separator. 15. The layered element according to claim 1, wherein
the second electrode is surrounded by a bag-shaped second separator in a state in which the peripheral edge of the hole through which the collector passes in the second electrode protrudes outward from the second separator.

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