JP2004296319A - Nonaqueous secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive large-sized nonaqueous secondary battery of simplified terminal structure. <P>SOLUTION: In the nonaqueous secondary battery in which a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte containing a lithium salt are housed in a battery container, the battery thickness of a flat shape is less than 12 mm, its energy capacity is 30 Wh or more, and its volume energy density is 180 Wh/l or more, the battery container is composed of an upper lid 1 formed in a flat shape and a bottom container 2, and has a hole having the width of 6 mm or less on the side face of the bottom container, and at the hole part, a positive electrode terminal 3 and/or a negative electrode terminal 4 are insulated and mounted via an adhesive resin 7. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a non-aqueous secondary battery, and more particularly to a non-aqueous secondary battery for a power storage system.
[0002]
[Prior art]
In recent years, from the viewpoint of effective use of energy for resource saving and global environmental issues, attention has been paid to distributed power storage systems for homes for storing power at midnight and solar power, and power storage systems for electric vehicles. Are gathering. For example, Patent Literature 1 proposes a total system that combines electricity supplied from a power plant, gas cogeneration, a fuel cell, a storage battery, and the like, as a system that can supply energy to energy consumers under optimal conditions. A secondary battery used in such a power storage system needs a large battery having a large capacity, unlike a small secondary battery for a portable device having an energy capacity of 10 Wh or less. For this reason, in the above-described power storage system, a plurality of secondary batteries are usually stacked in series and used as an assembled battery. In most cases, a lead battery is used.
[0003]
On the other hand, in the field of small rechargeable batteries for portable devices, nickel-metal hydride batteries and lithium rechargeable batteries have been developed as new types of batteries to meet the needs of small size and high capacity, and have a volume energy density of 180 Wh / l or more. Batteries are commercially available. In particular, a lithium ion battery has a potential of a volume energy density exceeding 350 Wh / l, and is superior in reliability such as safety and cycle characteristics as compared with a lithium secondary battery using lithium metal as a negative electrode. From that, the market has been dramatically extended.
[0004]
Accordingly, in the field of large batteries for power storage systems, large lithium ion batteries are being developed as candidates for high energy density batteries.
[0005]
However, these large lithium-ion batteries have a high energy density, but are generally cylindrical, square, and other battery shapes, and tend to accumulate heat inside the battery, which poses a problem in reliability, especially safety. Was left.
[0006]
Patent Literature 2 discloses a flat nonaqueous secondary battery in which a nonaqueous electrolyte containing a positive electrode, a negative electrode, a separator, and a lithium salt is contained in a battery container. A non-aqueous secondary battery is disclosed which has a flat shape with a thickness of less than 12 mm, an energy capacity of 30 Wh or more, and a volume energy density of 180 Wh / l or more. It proposes that the battery has a unique battery shape (flat shape) to solve the problems of reliability and safety caused by the heat storage, which is a barrier to practical application.
[0007]
On the other hand, what hinders the practical use of large lithium-ion batteries is the cost of the batteries, and it is desired to reduce the cost of battery containers by simplifying the terminal structure and the like. In the flat battery, as described in Patent Documents 3 and 4, etc., a positive electrode terminal and a negative electrode terminal which are insulated from a battery container are provided on a flat surface of the battery, and a positive electrode current collector is formed inside the battery. It is electrically connected to the negative electrode current collector. Specifically, as shown in FIG. 1, a positive electrode terminal 3 made of aluminum and a negative electrode terminal 4 made of copper (head 6 mmφ, threaded portion at tip M3) are attached to upper cover 1. The positive electrode terminal 3 and the negative electrode terminal 4 are insulated from the upper lid 1 by a Teflon (registered trademark) gasket, the screw portion of the positive electrode terminal 3 is inserted into the positive electrode current collector of the electrode laminate, and the negative electrode terminal is inserted into the negative electrode current collector. No. 4 are inserted, and aluminum and copper nuts are respectively fastened and electrically connected (see FIG. 2).
[0008]
Further, in Patent Document 5, in order to enhance the reliability of the terminal portion, at least one of a positive electrode terminal and a negative electrode terminal fixed at a predetermined position of a battery container is provided, and at least two of the two or more electrode terminals have the same polarity. There is a need for a terminal structure having a complicated structure that connects the members by a connecting member and prevents the inside of the battery from rotating and breaking due to rotational stress from outside the battery.
[0009]
Further, in the case of a battery having a flat shape with a thickness of less than 12 mm, it is necessary to finish each part thin, and a large number of terminal components, and further cost reduction has been desired from the viewpoint of workability. .
[0010]
In addition, in the case of the above terminal structure, in a thin battery, the terminal needs to be manufactured on the flat side of a wide flat surface, and when assembling a module from a plurality of thin batteries, a gap between adjacent batteries must be taken more than necessary. There is also a problem that the volume energy density as a module becomes low as a result of many structures that cannot be achieved.
[0011]
[Patent Document 1]
JP-A-6-86463
[0012]
[Patent Document 2]
International Publication No. 99/60652 pamphlet
[0013]
[Patent Document 3]
JP 2000-251941 A
[0014]
[Patent Document 4]
JP 2000-251940 A
[0015]
[Patent Document 5]
JP 2001-216953 A
[0016]
[Problems to be solved by the invention]
An object of the present invention is to provide an inexpensive large non-aqueous secondary battery having a simple terminal structure in a flat non-aqueous secondary battery having a thickness of less than 12 mm.
[0017]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to achieve the above object, and as a result, have found the following nonaqueous secondary battery, and have completed the present invention.
[0018]
Item 1 A nonaqueous electrolyte containing a positive electrode, a negative electrode, a separator, and a lithium salt is contained in a battery container, has a flat shape with a thickness of less than 12 mm, and has an energy capacity of 30 Wh or more and a volume energy density of 180 Wh / l or more. In the non-aqueous secondary battery, the battery container includes a flat top cover and a bottom container, and has a hole having a width of 6 mm or less on a side surface of the bottom container. And / or a non-aqueous secondary battery, wherein the negative electrode terminal is insulated and attached via an adhesive resin.
[0019]
Item 2. The non-aqueous secondary battery according to Item 1, wherein a positive electrode terminal and / or a negative electrode terminal are insulated and attached to the upper lid and the bottom container via an adhesive resin in the hole.
[0020]
Item 3. The nonaqueous system according to Item 1 or 2, wherein the hole is provided at two places on the side surface of the bottom container, and the positive electrode terminal or the negative electrode terminal is insulated and attached to the hole portion through an adhesive resin. Next battery.
[0021]
Item 4 The non-aqueous secondary battery according to Item 2 or 3, wherein the adhesive resin is an adhesive resin having thermoplasticity.
[0022]
Item 5. The non-aqueous secondary battery according to Item 2 or 3, wherein the adhesive resin is at least one selected from the group consisting of olefin-based, acrylic-based, epoxy-based, urethane-based, and silicon-based resins.
[0023]
Item 6 The holes provided on the side surface of the bottom container of the battery container are formed by drawing, and have burrs having a length of 1 mm or more toward the outside of the bottom container. The non-aqueous secondary battery according to any one of the above.
[0024]
Item 7. The nonaqueous secondary battery according to any one of Items 1 to 5, wherein the periphery of the battery container in which the top lid and the bottom container are overlapped is hermetically joined by welding.
[0025]
Item 8. The non-aqueous secondary battery according to any one of Items 1 to 5, wherein the upper lid and the bottom container in the battery container are made of aluminum or an alloy mainly containing aluminum.
[0026]
Item 9 The nonaqueous secondary battery according to any one of Items 1 to 5, wherein the positive electrode terminal or the negative electrode terminal is connected to a current collector by welding.
[0027]
Item 10. The non-aqueous secondary battery according to Item 1, wherein the positive electrode and the negative electrode include a substance capable of doping and undoping lithium.
[0028]
Item 11: The positive electrode comprises a lithium composite manganese oxide and a formula Li_aNi_bMn_cM_dO₂[Wherein M is at least one element selected from the group consisting of Co, Al and Fe, and 1 ≦ a ≦ 1.1, 0.3 ≦ b Item 10 wherein at least one selected from the group consisting of <0.5, 0.3 ≦ c <0.5, 0 <d ≦ 0.4, b ≧ c, b + c + d = 1] is used as the active material. Non-aqueous secondary battery.
[0029]
Item 12. The nonaqueous secondary battery according to Item 1, wherein the flat front and back surfaces are rectangular.
[0030]
Item 13 The non-aqueous secondary battery according to Item 1, wherein the thickness of the battery container is 0.2 mm or more and 1 mm or less.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a non-aqueous secondary battery according to an embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a plan view and a side view of a flat rectangular (note-type) non-aqueous secondary battery for a power storage system, which is an example of the present embodiment. FIG. 4 is a diagram showing the inside of the battery shown in FIG. FIG. 5 is a side view showing an electrode stack housed in the storage device. Here, the case where the electrodes are stacked is described, but the present invention is not limited to this electrode structure.
[0032]
As shown in FIGS. 3 and 4, the non-aqueous secondary battery of the present embodiment includes a battery container including an upper lid 1 and a bottom container 2, a plurality of positive electrodes 101a housed in the battery container, and a negative electrode. And an electrode laminate including the separators 101b and 101c and the separator 104. In the case of the flat nonaqueous secondary battery as in the present embodiment, the positive electrode 101a and the negative electrode 101b (or the negative electrode 101c disposed on both outer sides of the stacked body) are provided with a separator 104 interposed therebetween, for example, as shown in FIG. However, the present invention is not particularly limited to this arrangement, and the number of layers and the like can be variously changed according to the required capacity and the like. The shape of the non-aqueous secondary battery shown in FIGS. 1 and 2 is, for example, 210 mm in length × 150 mm in width × 6 mm in thickness.₂O₄In the case of a lithium secondary battery using a carbon material for the manganese-based lithium composite oxide and the negative electrodes 101b and 101c, for example, it can be used for a power storage system.
[0033]
In the present invention, the battery container includes a flat top cover and a bottom container. The upper lid and the bottom container have a structure that can be in close contact at the joint. In order to effectively join the upper lid and the bottom container, a flanged portion that has been drawn may be provided around the bottom container. A hole having a width of 6 mm or less is provided on the side surface of the bottom container, and a positive electrode terminal, a negative electrode terminal, or both terminals are insulated and attached to the bottom container with an adhesive resin in the hole (for example, FIG. 3 and FIG. 5). In addition, this hole is shown in an elongated shape in FIGS. 3 and 5, but the shape is not limited. The size of this hole is appropriately determined depending on the terminal size of the positive electrode terminal 3 or the negative electrode terminal 4. In the present invention, the width is 6 mm or less, preferably 4 mm or less, and 1 mm or more is practically preferable. If it exceeds, the thickness of the adhesive resin 7 increases, and the workability decreases. Here, the width of the hole is the size of the hole in the thickness direction of the battery, and is indicated by x in FIG.
[0034]
Further, it is desirable that the hole has a burr formed by, for example, drawing by burring or the like (for example, see burr 8 in FIG. 7). In the case where the burr 8 is provided, the burr is preferably directed outward from the battery in terms of processing, and the burr length is preferably 1 mm or more, and more preferably 1.5 mm or more and 4 mm or less. Here, the reason why the burr 8 is provided is to improve the adhesiveness and airtightness of the adhesive portion between the adhesive resin 7 and the bottom container 2.
[0035]
The holes provided on the side surface of the bottom container are for taking out electrode terminals from the inside of the battery. Usually, one or two holes are provided in the side surface of the bottom container, from which the positive electrode terminal and / or the negative electrode terminal are taken out. In a battery provided with one hole on the side surface of the bottom container, a positive electrode terminal or a negative electrode terminal is provided from the opening thereof, and the battery body serves as a negative electrode terminal or a positive electrode terminal. In a battery having two holes on the side surface of the bottom container, a positive electrode terminal and a negative electrode terminal are provided from the two holes. In these holes, each terminal is insulated and attached to the bottom container via an adhesive resin.
[0036]
For example, as one embodiment, FIGS. 3 and 5 show a battery in which two holes are provided in a bottom container.
[0037]
The positive electrode current collector 106a of each of the positive electrodes 101a shown in FIG. 4 is electrically connected to the positive electrode terminal 3, and the negative electrode current collector 106b of each of the negative electrodes 101b and 101c is electrically connected to the negative electrode terminal 4. As a connection method, ultrasonic welding, laser welding, resistance welding, or the like is used, which is cost-effective because connection parts such as screws are not required.
[0038]
The adhesive resin 7 that insulates the positive electrode terminal 3 or the negative electrode terminal 4 from the top lid 1 and the bottom container 2 is not particularly limited, and examples thereof include olefin-based, acrylic-based, epoxy-based, urethane-based, and silicon-based resins. However, a heat-sealing adhesive resin represented by a modified polypropylene or a modified polyethylene and having a low moisture permeability is preferable because it has high resistance to an electrolytic solution. The adhesive resin 7 must be in close contact with the positive electrode terminal 3, the negative electrode terminal 4, and the bottom container 2. For example, as shown in FIGS. 7 is tightly molded (leaving the portions 3a and 4a connecting the positive electrode current collector and the negative electrode current collector and the external terminal portions 3 and 4), and is fitted and adhered to the bottom container 2, and then the positive electrode current collector 106a and the negative electrode current collector The electric body 106b is electrically connected to each terminal.
[0039]
Thereafter, the upper lid 1 and the bottom container 2 are melted at the point A shown in the enlarged view in FIG. Examples of the welding method include laser welding, arc welding, resistance welding and the like. Among them, laser welding is preferred because the welding area is small and energy can be concentrated, so that deformation distortion of the container and heat influence on the periphery are small. For the bonding of the outer peripheral portion, it is possible to use a heat welding film used in a film type small lithium ion battery, but in the case of a flat type large battery such as the present invention, the welding area becomes large, and moisture permeates. It is preferable to join by welding. In addition, since the positive and negative terminals can be provided on the side surface in this manner, when a module including a battery pack is manufactured, the gap between adjacent batteries can be minimized, and as a result, the energy density of the module can be increased. It becomes possible.
[0040]
The upper lid 1 is provided with a liquid injection port 5 for an electrolytic solution. After the liquid injection, the liquid is sealed using a sealing film 6 made of, for example, an aluminum-modified polypropylene laminated film.
[0041]
The positive electrode active material used for the positive electrode 101a is not particularly limited as long as it is a lithium-based positive electrode material capable of doping and undoping lithium, and lithium composite cobalt oxide, lithium composite nickel oxide, lithium composite manganese oxide Alternatively, a mixture thereof, or a system in which one or more different metal elements are added to these composite oxides can be used. Above all, it is preferable to use a lithium composite manganese oxide or a lithium nickel manganese composite oxide represented by the following formula from the viewpoints of energy density, cost and safety of the battery.
[0042]
Li_aNi_bMn_cM_dO₂
[Wherein, M is at least one element selected from the group consisting of Co, Al and Fe, and 1 ≦ a ≦ 1.1, 0.3 ≦ b <0.5, 0.3 ≦ c <0.5, 0 <d ≦ 0.4, b ≧ c, b + c + d = 1]
The formula: Li_aNi_bMn_cM_dO₂In the formula, a indicating the molar ratio of Li is usually about 1 ≦ x ≦ 1.1. If a deviates from this range, the cycle characteristics are reduced, or the capacity of the active material is significantly reduced.
[0043]
B indicating the molar ratio of Ni is usually about 0.3 ≦ b <0.5. When b is too large, the capacity of the battery increases, but the thermal stability decreases and the safety of the battery also decreases. If it is too small, the capacity of the battery decreases.
[0044]
C indicating the molar ratio of Mn is usually about 0.3 ≦ c <0.5. If c is too large, the thermal stability is improved and the safety of the battery is improved, but the capacity of the battery is reduced. On the other hand, if it is too small, the capacity of the battery increases, but the thermal stability decreases and the safety of the battery also decreases.
[0045]
Examples of the element M that replaces Ni or Mn in the formula include Co, Al, and Fe. Of these, Co and Al are more preferable in terms of cycle characteristics and safety. D indicating the molar ratio of the substitution element M is generally about 0 <d ≦ 0.4. When M is 0, the powder of the active material becomes bulky, and the high-rate discharge characteristics also decrease. When M is too large, the thermal stability of the active material decreases.
[0046]
As the negative electrode active material used for the negative electrodes 101b and 101c,
The material is not particularly limited as long as it is a lithium-based negative electrode material, and is preferably a material capable of doping and undoping lithium, because safety and reliability such as cycle life are improved. Examples of materials capable of doping and undoping lithium include graphite-based materials, carbon-based materials, tin oxides, and metal oxides such as silicon oxides that are used as negative electrode materials for known lithium ion batteries. From the viewpoint of cost, for example, a graphite-based material having a double structure in which a surface of a graphite-based material such as natural graphite is coated with a carbon material is desirable.
[0047]
The method for forming the positive electrode active material and the negative electrode active material of the present invention into an electrode can be appropriately selected from known methods according to the desired characteristics of the nonaqueous secondary battery and the like. For example, a slurry is prepared by mixing a positive electrode active material (or a negative electrode active material), a binder, and, if necessary, a solvent such as N-methyl-2-pyrrolidone (NMP). , Compression and the like.
[0048]
Examples of the binder include, but are not particularly limited to, fluorinated resins such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene, fluorinated rubber, SBR, acrylic resins, and olefins such as polyethylene and polypropylene.
[0049]
When the positive electrode or the negative electrode is formed on the current collector, the material of the current collector is not particularly limited as long as it is selected in consideration of the withstand voltage of the material, and copper foil, stainless steel foil, titanium foil, An example is an aluminum foil.
[0050]
The configuration of the separator 104 is not particularly limited, but a single-layer or multiple-layer separator can be used, and at least one of the separators is preferably made of a nonwoven fabric. In this case, cycle characteristics are improved. Also, the material of the separator 104 is not particularly limited, and examples thereof include polyolefin such as polyethylene and polypropylene, polyamide, kraft paper, glass, and cellulosic materials. The heat shrinkage at 150 ° C. is preferably 5% or less in any of the directions along the plane from the viewpoint of the heat resistance of the battery. Cellulose, polyester, polyamide, and polyphenylene sulfide It is preferable to use a resin such as a fluorine-based or polyolefin-based resin, or an inorganic fiber such as a glass fiber.
[0051]
As the electrolyte of the secondary battery of the present invention, a known non-aqueous electrolyte containing a lithium salt can be used, and it is appropriately determined according to use conditions such as a positive electrode material, a negative electrode material, and a charging voltage.₆, LiBF₄, LiClO₄Lithium salt was dissolved in an organic solvent such as propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, dimethoxyethane, γ-butyrolactone, methyl acetate, methyl formate, or a mixed solvent of two or more of these. And the like. Further, the concentration of the electrolytic solution is not particularly limited, but is generally practically 0.5 mol / l to 2 mol / l. Naturally, this electrolytic solution has a water content of 100 ppm or less. Preferably, it is used. The non-aqueous electrolyte used in this specification means a concept including a non-aqueous electrolyte and an organic electrolyte, and also includes a concept including a gel or solid electrolyte.
[0052]
The non-aqueous secondary battery configured as described above can be used in a home power storage system (nighttime power storage, cogeneration, solar power generation, etc.), a power storage system of an electric vehicle, and the like, and has a large capacity and a high capacity. It can have energy density. In this case, the energy capacity is preferably 30 Wh or more, more preferably 50 Wh or more, and the energy density is preferably 180 Wh / l or more, more preferably 200 Wh / l. When the energy capacity is less than 30 Wh or when the volume energy density is less than 180 Wh / l, the capacity is small for use in a power storage system, and it is necessary to increase the number of series-parallel batteries to obtain a sufficient system capacity. In addition, it is not preferable for a power storage system because a compact design is difficult.
[0053]
The non-aqueous secondary battery of the present embodiment has a flat shape and a thickness of less than 12 mm, more preferably less than 10 mm. The lower limit of the thickness is practically 2 mm or more in consideration of the filling rate of the electrode and the battery size (the smaller the thickness, the larger the area for obtaining the same capacity). When the thickness of the battery is 12 mm or more, it becomes difficult to sufficiently dissipate the heat generated inside the battery to the outside, or the temperature difference between the inside of the battery and the vicinity of the battery surface increases, resulting in a difference in internal resistance. , The variation in the amount of charge and the voltage increases. Although the specific thickness is appropriately determined according to the battery capacity and the energy density, it is preferable to design the thickness so as to obtain the expected heat radiation characteristics.
[0054]
In addition, the nonaqueous secondary battery of the present embodiment can have, for example, various flattened front and back surfaces of a battery container, such as a square, a circle, and an ellipse. However, it may be a polygon such as a triangle and a hexagon. Further, it may be a cylindrical shape such as a thin-walled cylinder. In the case of a cylindrical shape, the thickness of the cylinder is the thickness referred to here. Further, from the viewpoint of ease of manufacture, the flat front and back surfaces of the battery are preferably rectangular, and a notebook shape as shown in FIG. 3 is preferable.
[0055]
In the present embodiment, the battery container is composed of a flat-shaped upper lid and a drawn bottom container, and the upper lid 1 and the lower container 2 are mainly made of stainless steel, aluminum, or an alloy mainly composed of aluminum. Among them, it is preferable to use aluminum or an alloy mainly composed of aluminum from the viewpoint of the weight energy density and cost of the battery.
As the aluminum alloy material, for example, an alloy of one or more metals selected from among Si, Fe, Cu, Mn, Mg, Cr, Zn, Ti and the like, and aluminum can be used. In the components of the Al—Mn alloy, the content of the Mn component is preferably set to 0.5% by weight to 2.0% by weight. If the Mn content is less than 0.5% by weight, the mechanical strength and the rigidity of large-sized components are reduced. In addition, the formability and laser welding characteristics are reduced. On the other hand, if it exceeds 2.0% by weight, the effect of improving strength does not increase so much, and the possibility of cracking due to the appearance of coarse intermetallic compounds increases. Further, the content of the Mg component in the Mg-Al-based alloy is preferably set to 0.02% by weight to 0.8% by weight. When the Mg content is 0.8% by weight or more, poor welding such as cracks and holes tends to occur when laser welding the battery container.
[0056]
The thickness of the upper lid 1 and the bottom container 2 constituting the battery container is appropriately determined depending on the use of the battery, the material of the battery case, and the like, and is not particularly limited, but is preferably 80% or more of the battery surface area. The thickness of the portion (the thickness of the portion having the largest area constituting the battery container) is 0.2 mm or more. If the thickness is less than 0.2 mm, there is a problem that the strength required for battery production cannot be obtained. From this viewpoint, the thickness is more preferably 0.3 mm or more, and further preferably 0.4 mm or more. It is. The thickness of this portion is desirably 1 mm or less. When the thickness exceeds 1 mm, the force for pressing down the electrode surface increases, but it is not desirable because the internal volume of the battery is reduced and a sufficient capacity cannot be obtained, or the weight increases, which is not desirable. Preferably it is 0.7 mm or less.
[0057]
By the way, in the case of the large-sized battery having a flat shape of the present invention, since the force for sandwiching and pressing the electrode surface is weakened, the internal resistance is increased, or the cycle life is reduced and the battery performance is affected. There is. To solve these problems, it is possible to seal the inside of the battery so as to be lower than the atmospheric pressure as described below.
[0058]
In order to keep the internal pressure of the completed battery lower than the atmospheric pressure, the positive electrode 101a, the negative electrodes 101b and 101c, the separator 104 and the non-aqueous electrolyte are accommodated in the battery container, and the pressure in the battery container is reduced to the atmospheric pressure. The final sealing step of the battery container is performed in the state of less than. This final sealing step is preferably performed after at least one charging operation. In this case, gas may be generated inside the electrolyte due to decomposition of the electrolyte in the early stage of the first charging. In this case, if the final sealing step is performed at a pressure lower than the atmospheric pressure without performing the charging operation, the subsequent first sealing may be performed. This is because the inside of the battery becomes pressurized (atmospheric pressure or more) due to the charging operation, the thickness of the battery becomes thicker, the internal resistance and the capacity of the battery fluctuate, and stable cycle characteristics cannot be obtained. In particular, when a liquid electrolyte using graphite for the negative electrode and a lithium composite oxide for the positive electrode is used, gas is easily generated.
[0059]
This charging operation may employ various conditions depending on the types of the positive electrode material, the negative electrode material, the separator, the electrolyte, etc. used in the battery, the water content and impurities of these materials, the voltage at which the battery is used, and the like. For example, the battery may be charged at a rate of about 4 to 8 hours to the operating voltage of the battery, a constant voltage may be applied as necessary, and the battery may be discharged at a rate of about 8 hours to the normal lower limit voltage. After this charging operation, a final sealing step is performed. Further, the battery may be sealed after performing only the charging operation of the capacity of the battery or less, or various charging operations such as sealing after repeating charging and discharging two or more times are possible. It is important to keep the internal pressure of the battery below atmospheric pressure.
[0060]
【Example】
Hereinafter, examples of the present invention will be described, and the present invention will be described more specifically. The present invention is not limited by the description of these examples.
[0061]
Example
(1) First, as a lithium nickel manganese-based composite oxide, LiNi_1/3Mn_1/3Co_1/3O₂, Natural graphite having a high specific surface area as a conductive material (BET specific surface area = 250 g / m 2)²) And acetylene black were dry mixed. Slurry 1 was prepared by uniformly dispersing the obtained mixture in N-methyl-2-pyrrolidone (NMP) in which polyvinylidene fluoride (PVDF) as a binder was dissolved. Next, the slurry 1 was applied to both sides of an aluminum foil serving as a current collector, dried, and then pressed to obtain a positive electrode.
[0062]
The solid content weight ratio in the positive electrode was adjusted to be lithium nickel manganese composite oxide: high specific surface area natural graphite: acetylene black: PVDF = 92: 3: 2: 3.
[0063]
FIG. 6A is an explanatory diagram of the positive electrode. In this embodiment, the coating area (W1 × W2) of the positive electrode 101a is 183 × 130 mm²It is. In addition, a current collector 106a to which the slurry 1 is not applied is provided on the short side of the electrode.
[0064]
(2) The double-structure graphite particles are natural graphite (average particle size 25 μm, tap density 0.86 g / cm).³) And petroleum pitch (softening point 250 ° C, toluene insoluble content 30%) were mixed and calcined.
[0065]
(3) The double-structured graphite particles produced in the above (2) (the spacing (d002) of the (002) plane of the graphite particle core is less than 0.34 nm, the spacing (d002) of the (002) plane of the coating layer = After that, artificial graphite as a conductive material was dry-mixed, and then uniformly dispersed in NMP in which PVDF as a binder was dissolved to prepare a slurry 2. Next, the slurry 2 was applied to both surfaces of a copper foil serving as a current collector, dried, and then pressed to obtain a negative electrode.
[0066]
The solid content ratio (weight ratio) in the negative electrode was adjusted to be double structure graphite particles: artificial graphite: PVDF = 93: 2: 5.
[0067]
FIG. 6B is an explanatory diagram of the negative electrode. The application area (W1 × W2) of the negative electrode 101b is 186.5 × 133 mm²It is. In addition, a current collector 106b to which the slurry 2 is not applied is provided on the short side of the electrode.
[0068]
Further, the slurry 2 was applied only on one side by the same method as described above, thereby producing a single-sided electrode. The single-sided electrode is arranged on the outside in the electrode laminate of item (3) described later (101c in FIG. 4).
[0069]
(4) As shown in FIG. 4, 11 sheets of the positive electrode obtained in the above item (1) and 12 sheets of the negative electrode obtained in the above item (2) (two sheets on one side) were separated by a separator 104 (rayon paper making: (Thickness: 30 μm).
[0070]
(5) As shown in FIG. 5, a thin plate made of a Mn-Al alloy 3003 having a thickness of 0.5 mm is drawn down to a depth of 5.5 mm, and the side portion thereof is drawn by burring (outward burr depth of about 3 mm). , And a width of about 1.5 mm (x part in FIG. 5) and a length of about 24 mm. The bottom container 2 has a 5 mm wide flange. The upper lid 1 was also made of a thin plate made of a Mn-Al-based alloy 3003 having a thickness of 0.5 mm. Next, a modified polypropylene resin 7 is heat-sealed around an aluminum positive electrode terminal 3 having a thickness of 0.8 mm, a width of 20 mm, and a length of 26 mm, and a copper negative electrode terminal 4 having the same dimensions. Heat welded.
[0071]
(6) Ultrasonic welding of each positive electrode current collector 106a of the electrode laminate manufactured in the above item (3) to the 3a portion of the positive electrode terminal 3 and each negative electrode current collector 106b of the 4a portion of the negative electrode terminal 4; Along with the lid 1, the corner A in FIG. Next, vinylene carbonate in an amount corresponding to 2% by weight of the total solvent weight was added to a solvent obtained by mixing electrolyte solutions (ethylene carbonate and ethyl methyl carbonate at a volume ratio of 30:70) from the injection port 5 (diameter 6 mm). After that, the concentration of LiPF was adjusted to 1 mol / l.₆Was dissolved. Next, the injection port 5 was temporarily closed using a temporary fixing bolt under atmospheric pressure.
[0072]
(7) The battery was charged at a current of 3.4 A to 4.2 V at 25 ° C., and then a constant current and constant voltage charging of applying a constant voltage of 4.2 V was performed for a total of 8 hours, followed by a constant current of 2 A. To 2.5V.
[0073]
(8) Next, after removing the temporary fixing bolt of the battery, the inside of the container becomes 4 × 10⁴A sealing film 6 made of an aluminum foil-modified polypropylene laminated film having a thickness of 0.08 mm and punched into a diameter of 12 mm so as to be under a reduced pressure of Pa (300 Torr) was heated at a temperature of 250 to 350 ° C. and a pressure of 1 to 3 kg / cm.²The liquid injection port 5 was finally sealed by heat-sealing under the conditions of a pressurization time of 5 to 10 seconds to obtain a flat notebook battery having a width of 148 mm, a height of 210 mm and a thickness of 6.5 mm. .
[0074]
(9) Using this battery at 25 ° C., charge the battery to 4.2 V with a current of 3 A, then perform a constant current and constant voltage charge of applying a constant voltage of 4.2 V for a total of 8 hours, and then perform a constant charge of 3 A The battery was discharged to a current of 2.5 V, and the capacity was measured to obtain a capacity of 15.0 Ah.The energy of this battery was 54.0 Wh, and the energy density was 267 Wh / l.
Comparative example
(1) First, as a lithium nickel manganese-based composite oxide, LiNi_1/3Mn_1/3Co_1/3O₂, Natural graphite having a high specific surface area as a conductive material (BET specific surface area = 250 g / m 2)²) And acetylene black were dry mixed. Slurry 1 was prepared by uniformly dispersing the obtained mixture in N-methyl-2-pyrrolidone (NMP) in which polyvinylidene fluoride (PVDF) as a binder was dissolved. Next, the slurry 1 was applied to both sides of an aluminum foil serving as a current collector, dried, and then pressed to obtain a positive electrode.
[0075]
The solid content weight ratio in the positive electrode was adjusted to be lithium nickel manganese composite oxide: high specific surface area natural graphite: acetylene black: PVDF = 92: 3: 2: 3.
[0076]
FIG. 8A is an explanatory diagram of a positive electrode. In this embodiment, the coating area (W1 × W2) of the positive electrode 101a is 177 × 130 mm²It is. A current collector 106a to which the slurry 1 is not applied is provided on the short side of the electrode, and a hole having a diameter of 3 mm is formed in the center thereof.
[0077]
(2) The double-structure graphite particles are natural graphite (average particle size 25 μm, tap density 0.86 g / cm).³) And petroleum pitch (softening point 250 ° C, toluene insoluble content 30%) were mixed and calcined.
[0078]
(3) The double-structured graphite particles produced in the above (2) (the spacing (d002) of the (002) plane of the graphite particle core is less than 0.34 nm, the spacing (d002) of the (002) plane of the coating layer = After that, artificial graphite as a conductive material was dry-mixed, and then uniformly dispersed in NMP in which PVDF as a binder was dissolved to prepare a slurry 2. Next, the slurry 2 was applied to both surfaces of a copper foil serving as a current collector, dried, and then pressed to obtain a negative electrode.
[0079]
The solid content ratio (weight ratio) in the negative electrode was adjusted to be double structure graphite particles: artificial graphite: PVDF = 93: 2: 5.
[0080]
FIG. 8B is an explanatory diagram of the negative electrode. The application area (W1 × W2) of the negative electrode 101b is 133 × 181.5 mm²It is. In addition, a current collector 106b to which the slurry 2 is not applied is provided on the short side of the electrode, and a hole having a diameter of 3 mm is formed in the center thereof.
[0081]
Further, the slurry 2 was applied only on one side by the same method as described above, thereby producing a single-sided electrode. The single-sided electrode is arranged on the outside in the electrode laminate of item (3) described later (101c in FIG. 4).
[0082]
(4) As shown in FIG. 4, 11 sheets of the positive electrode obtained in the above item (1) and 12 sheets of the negative electrode obtained in the above item (2) (two sheets on one side) were separated by a separator 104 (rayon paper making: (Thickness: 30 μm) to form an electrode laminate.
[0083]
(5) As shown in FIG. 9, a SUS304 thin plate having a thickness of 0.5 mm was squeezed to a depth of 5.5 mm, a bottom container 2 was formed, and a top cover 1 was also formed of a SUS304 thin plate having a thickness of 0.5 mm. . Next, the positive electrode terminal 3 made of aluminum and the negative electrode terminal 4 made of copper (head diameter: 6 mm, screw portion at the tip M3) were attached to the upper lid 1. The positive and negative electrode terminals 3 and 4 were insulated from the upper lid 1 by a Teflon (registered trademark) gasket.
[0084]
(6) The holes of the respective positive electrode current collectors 106a and the holes of the respective negative electrode current collectors 106b of the electrode laminate prepared in the above item (3) are inserted into the negative electrode terminal 4, respectively. (FIG. 2), the connected electrode laminate was fixed with insulating tape, and the corner A of FIG. 10 was laser-welded over the entire circumference. Next, vinylene carbonate in an amount corresponding to 2% by weight of the total solvent weight was added to a solvent obtained by mixing electrolyte solutions (ethylene carbonate and ethyl methyl carbonate at a volume ratio of 30:70) from the injection port 5 (diameter 6 mm). After that, the concentration of LiPF was adjusted to 1 mol / l.₆Was dissolved. Next, the injection port 5 was temporarily closed using a temporary fixing bolt under atmospheric pressure.
[0085]
(7) After charging the battery at a current of 3.4 A to 4.2 V at 25 ° C., a constant current and constant voltage charge of applying a constant voltage of 4.2 V was performed for a total of 8 hours, followed by a constant current of 2 A. To 2.5V.
[0086]
(8) Next, after removing the temporary fixing bolt of the battery, the inside of the container becomes 4 × 10⁴A sealing film 6 made of an aluminum foil-modified polypropylene laminated film having a thickness of 0.08 mm and punched into a diameter of 12 mm so as to be under a reduced pressure of Pa (300 Torr) was heated at a temperature of 250 to 350 ° C. and a pressure of 1 to 3 kg / cm.²The liquid injection port 5 was finally sealed by heat-sealing under the conditions of a pressurization time of 5 to 10 seconds to obtain a flat notebook battery having a width of 148 mm, a height of 210 mm and a thickness of 6.5 mm. .
[0087]
(9) Using this battery at 25 ° C., charge the battery to 4.2 V with a current of 3 A, then perform a constant current and constant voltage charge of applying a constant voltage of 4.2 V for a total of 8 hours, and then perform a constant charge of 3 A When the battery was discharged to a current of 2.5 V and the capacity was measured, a capacity of 14.5 Ah was obtained.
When comparing the example with the comparative example, the example has a simple terminal structure and a small number of parts, so that the cost of the battery can be reduced. Density can be increased.
[0088]
【The invention's effect】
The non-aqueous secondary battery of the present invention has a simple terminal structure and can be manufactured at low cost. In particular, the advantage is large in a large non-aqueous secondary battery.
[0089]
Further, when assembling a module from a plurality of thin batteries, the gap between the batteries can be reduced as much as possible, and the volume energy density of the module can be increased.
[Brief description of the drawings]
FIG. 1 is a diagram showing a cross-sectional view of an upper lid and a bottom container in a conventional flat battery.
FIG. 2 is a diagram showing a cross-sectional view near a positive electrode terminal or a negative electrode terminal in a flat battery according to the related art.
FIG. 3 is a plan view and a side view of a non-aqueous secondary battery for a power storage system according to an embodiment of the present invention.
4 is a diagram showing a side view of an electrode laminate housed inside the battery shown in FIG.
5 is a diagram showing a side view of the upper lid and the bottom container shown in FIG. 3 as viewed from the electrode terminal side.
6 is a plan view of a positive electrode, a negative electrode, and a separator that constitute the electrode laminate shown in FIG.
FIG. 7 is a cross-sectional view showing the vicinity of a positive electrode terminal or a negative electrode terminal of the battery shown in FIG.
FIG. 8 is a plan view of a positive electrode, a negative electrode, and a separator constituting an electrode laminate in a flat battery of a comparative example.
FIG. 9 is a cross-sectional view of an upper lid and a bottom container in a flat battery of a comparative example.
FIG. 10 is a plan view and a side view of a flat battery of a comparative example.
[Explanation of symbols]
1 Top lid
2 bottom container
3 Positive terminal
4 Negative electrode terminal
5 Injection port
6 Sealing film
7 Adhesive resin
8 Kaeri
101a positive electrode (both sides)
101b negative electrode (both sides)
101c negative electrode (one side)
104 separator
105a positive electrode current collector
105b negative electrode current collector
106a positive electrode current collector
106b negative electrode current collector

Claims (13)

A nonaqueous electrolyte containing a positive electrode, a negative electrode, a separator, and a lithium salt is accommodated in a battery container, has a flat shape with a thickness of less than 12 mm, and has an energy capacity of 30 Wh or more and a volume energy density of 180 Wh / l or more. In the nonaqueous secondary battery, the battery container includes an upper lid and a bottom container configured in a flat shape, and has a hole having a width of 6 mm or less on a side surface of the bottom container, and a positive electrode terminal and / or A non-aqueous secondary battery, wherein the negative electrode terminal is insulated and attached via an adhesive resin. The non-aqueous secondary battery according to claim 1, wherein a positive electrode terminal and / or a negative electrode terminal are insulated and attached to the upper lid and the bottom container via an adhesive resin in the hole. 3. The non-aqueous secondary according to claim 1, wherein the hole is provided in two places on the side surface of the bottom container, and a positive electrode terminal or a negative electrode terminal is insulated and attached to the hole portion through an adhesive resin. 4. battery. The non-aqueous secondary battery according to claim 2, wherein the adhesive resin is an adhesive resin having thermoplasticity. 4. The non-aqueous secondary battery according to claim 2, wherein the adhesive resin is at least one selected from the group consisting of olefin-based, acrylic-based, epoxy-based, urethane-based, and silicon-based resins. 5. The hole provided in the side surface portion of the bottom container of the battery container is formed by drawing, and has a burr with a length of 1 mm or more toward the outside of the bottom container. The non-aqueous secondary battery according to any one of the above. The non-aqueous secondary battery according to any one of claims 1 to 5, wherein the periphery of the battery container in which the top lid and the bottom container are overlapped is hermetically joined by welding. The non-aqueous secondary battery according to any one of claims 1 to 5, wherein the upper lid and the bottom container in the battery container are made of aluminum or an alloy mainly containing aluminum. The non-aqueous secondary battery according to claim 1, wherein the positive terminal or the negative terminal is connected to a current collector by welding. The non-aqueous secondary battery according to claim 1, wherein the positive electrode and the negative electrode include a substance capable of doping and undoping lithium. Wherein at least a positive electrode, a lithium composite manganese oxide and formula _{Li a Ni b Mn c M d} O 2 lithium-nickel-manganese composite oxide represented by wherein, M is selected from the group consisting of Co, Al and Fe One element, and 1 ≦ a ≦ 1.1, 0.3 ≦ b <0.5, 0.3 ≦ c <0.5, 0 <d ≦ 0.4, b ≧ c, b + c + d = The non-aqueous secondary battery according to claim 10, wherein at least one selected from the group consisting of 1) is used as an active material. The non-aqueous secondary battery according to claim 1, wherein the shape of the flat front and back surfaces is rectangular. The non-aqueous secondary battery according to claim 1, wherein the thickness of the battery container is 0.2 mm or more and 1 mm or less.

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