JP2017152299A - Nonaqueous electrolyte secondary battery and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a nonaqueous electrolyte secondary battery which can bring about superior discharge characteristic, a superior appearance and a superior yield in a compact coin cell or the like, which is capable of supplying a large current pulse of in a region of approximately 1 mA to several mA; and a method for manufacturing the nonaqueous electrolyte secondary battery.SOLUTION: In a nonaqueous electrolyte secondary battery, a storage container 2 is arranged by a combination of a bottomed cylindrical positive electrode can 12 with an opening 12a and a covered cylindrical negative electrode can 22 provided that a containing space is formed between the positive electrode can 12 and the negative electrode can. An inner bottom face in the positive electrode can 12 and an inner lid face of the negative electrode can 22 are made a positive electrode current collecting part 14 and a negative electrode current collecting part 24 respectively; the positive and negative electrode current collecting parts are electrically connected with a positive electrode 10 and a negative electrode 20 respectively. The positive electrode current collecting part 14 and the negative electrode current collecting part 24 each have an uneven structure including flat portions 14a, 24a and concave portions 14b, 24b which are respectively provided on the inner bottom face of the corresponding positive electrode can 12 and the inner lid face of the corresponding negative electrode can 22.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a nonaqueous electrolyte secondary battery and a method for manufacturing the same.

  A non-aqueous electrolyte secondary battery includes, for example, a pair of polarizable electrodes composed of a positive electrode and a negative electrode, a positive electrode and a negative electrode in a storage container sealed with a positive electrode can and a negative electrode can (battery can) made of stainless steel. A separator interposed between the positive electrode and the negative electrode, a non-aqueous electrolyte impregnated in the positive electrode, the negative electrode, and the separator and containing a non-aqueous solvent such as a supporting salt and an organic solvent. It is to be prepared. Such a non-aqueous electrolyte secondary battery has a high energy density and is lightweight, and is used, for example, in a power supply unit of an electronic device or a power storage unit that absorbs fluctuations in the amount of power generated by a power generation device.

  Further, in the non-aqueous electrolyte secondary battery having the above-described configuration, for example, the connection between the positive electrode can and the positive electrode and the connection between the negative electrode can and the negative electrode may be directly bonded using a conductive paste or the like, or In some cases, each electrode is bonded and electrically connected to a metal current collector fixed to the inner bottom surface of the positive electrode can and the negative electrode can by welding or pressure welding.

In addition, since a non-aqueous electrolyte secondary battery using a negative electrode containing silicon oxide (SiO _x ) as a negative electrode active material can obtain a high discharge capacity, it is particularly small non-aqueous such as a coin type (button type). It is used as an electrolyte secondary battery. Such coin-type non-aqueous electrolyte secondary batteries are known to have high voltage, high energy density, excellent charge / discharge characteristics, long cycle life, and high reliability. Therefore, such a coin-type non-aqueous electrolyte secondary battery has been conventionally used as a backup power source or a real-time clock for a semiconductor memory in various small electronic devices such as a mobile phone, a PDA, a portable game machine, and a digital camera. It is used as a power source for function backup. In recent years, a coin-type non-aqueous electrolyte secondary battery is expected to be applied to a main power source in communication equipment such as Bluetooth (registered trademark) as a new application. On the other hand, in such applications as a main power source, a discharge characteristic at a larger current is required as compared with a backup power source such as a conventional semiconductor memory or a real time clock.

  Here, when the coin type (button type) as described above is applied to a main power source of a communication device, for example, it is required to take out a large current pulse of 1 mA or more, so it is necessary to greatly reduce the internal resistance of the battery. There is. Thus, as a means for reducing the internal resistance, conventionally, increasing the contact area between each electrode and the positive electrode can or the negative electrode can, or between each electrode and each current collector, etc. Is being considered.

  As described above, with the aim of improving the discharge current characteristics by increasing the contact area between the electrode and the battery can and reducing the contact resistance (internal resistance), the wire mesh made of a metal such as stainless steel is used. A secondary battery in which a negative electrode and a negative electrode can are connected has been proposed (see, for example, Patent Document 1).

  In addition, a battery in which the contact area between the electrode and the battery can is increased by adopting a configuration in which irregularities are formed on the bottom (top) of the battery can has been proposed (see, for example, Patent Document 2). .

JP-A-7-320787 JP 2001-332227 A

  However, when a metal wire mesh is used as a current collector, as in the secondary battery described in Patent Document 1, there is a process for fixing the wire mesh used as a current collector to a battery can or an electrode pellet. The increase causes problems such as a decrease in productivity and an increase in production cost. In addition, when using a metal mesh for the current collector, a sheet-shaped metal mesh is used by punching in accordance with the shape of the electrode, so if the punching waste (work piece) at this time remains inside the battery, an internal short It may cause. Furthermore, the workpiece may remain between the wire mesh and other members (battery can or electrode), which may hinder fixation between them. Therefore, when the current collector is manufactured by punching a wire mesh, the battery yield may be reduced.

  Further, in the case of forming irregularities on the battery can as in the battery described in Patent Document 2, the irregularities are formed in the battery can at the same time as the press forming of the battery can by providing an uneven portion inside the press mold. Due to the method, for example, it is difficult to form unevenness as a fine shape such as a lattice shape. Further, the technique described in Patent Document 2 has a problem that the uneven shape is not only preferable on the inner surface side of the battery can but also on the outer surface side, which is not preferable in terms of the appearance as a battery.

  The present invention has been made in view of the above problems, and can effectively reduce internal resistance in a small battery that can supply a large current pulse in a region of about 1 mA to several mA and has an increased discharge current compared to the prior art. An object of the present invention is to provide a non-aqueous electrolyte secondary battery that can be discharged for a long time while maintaining a sufficient discharge current and voltage and is excellent in discharge characteristics and appearance characteristics.

  In addition, the present invention is capable of supplying a large current pulse in the region of about 1 mA to several mA and producing a small battery with an increased discharge current as compared with the prior art while maintaining a sufficient discharge current and voltage. It is an object of the present invention to provide a method for producing a non-aqueous electrolyte secondary battery capable of producing a non-aqueous electrolyte secondary battery that can be discharged for a long time and has excellent discharge characteristics and appearance characteristics with high yield.

  The present inventor has intensively studied to solve the above problems, and in particular, in a small non-aqueous electrolyte secondary battery that supplies a large current pulse with a discharge current of 1 mA or more, while ensuring sufficient discharge characteristics, Repeated experiments to improve time yield. As a result, first, an uneven structure is formed on the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can constituting the battery container, and this portion is used as a current collector integrated with the positive electrode can or the negative electrode can. It has been found that the contact area between the positive electrode and negative electrode and the current collector can be reliably increased and the contact resistance can be reduced. In addition, by forming the concavo-convex structure of the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can by etching, it is possible to prevent the production of a work piece that has become a problem when a battery can is manufactured by a conventional method. And it discovered that a concavo-convex structure could be formed with a fine pattern. As a result, non-aqueous electrolyte secondary batteries with a higher discharge current than before can be discharged for a long time with sufficient discharge current and voltage maintained, with excellent appearance characteristics and a significant yield. The present invention has been completed.

  That is, the nonaqueous electrolyte secondary battery of the present invention includes a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator disposed between the positive electrode and the negative electrode, at least a supporting salt and an organic solvent. A nonaqueous electrolyte secondary battery housed in a metal storage container, the storage container comprising a bottomed cylindrical positive electrode can having an opening, A lidded cylindrical negative electrode can that forms a housing space with the positive electrode can is combined, and the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can are electrically connected to the positive electrode or the negative electrode, respectively. The current collector is characterized by having a concavo-convex structure comprising a flat portion and a recess provided on the inner bottom surface and the inner lid surface.

  According to the present invention, the current collector portion having a concavo-convex structure integrated with the positive electrode can and the negative electrode can is provided on the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can. Since the contact area between the current collector and the current collector provided in the negative electrode can is increased, the contact resistance between them is reduced. In addition, since the concave and convex structure is provided on the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can, the concave and convex shape does not occur on the outer surface side. Therefore, in particular, in a small non-aqueous electrolyte secondary battery capable of supplying a large current pulse in the region of about 1 mA to several mA, it is possible to discharge for a long time while maintaining a sufficient discharge current and voltage. Discharge characteristics and appearance characteristics can be obtained.

  Further, in the non-aqueous electrolyte secondary battery of the present invention, in the above configuration, each of the current collectors provided in the positive electrode can and the negative electrode can has a ratio of the flat part to the area of the current collector of 10 to 10. It is preferable that it is 50%.

  According to the present invention, by setting the ratio of the flat portion to the area of the current collecting portion within the above range, the contact area between each electrode and the current collecting portion is reliably increased, and the contact area between these is remarkable. Can be reduced.

  In the non-aqueous electrolyte secondary battery of the present invention, in the above configuration, it is preferable that at least a part of the current collector provided in the positive electrode can or the negative electrode can is embedded in the positive electrode and the negative electrode. .

  According to the present invention, since at least a part of the current collector is embedded in the positive electrode and the negative electrode, the contact area between each electrode and each current collector is greatly increased, and the contact resistance is significantly reduced. Is done.

  In the non-aqueous electrolyte secondary battery of the present invention, the positive electrode can and the negative electrode can may be made of stainless steel in the above configuration.

  According to the present invention, since the positive electrode can and the negative electrode can are made of stainless steel, the hardness of the current collecting part having a concavo-convex structure is increased, and part of the current collecting part easily enters the positive electrode and the negative electrode. The contact area between each electrode and the current collector can be reliably increased, and the contact resistance between them can be greatly reduced.

  In the non-aqueous electrolyte secondary battery of the present invention, the positive electrode can and the negative electrode can may be made of a clad material whose outer surface is stainless steel and whose inner surface is aluminum, nickel, or copper. .

  According to the present invention, by using the clad material having the above-described configuration for the positive electrode can and the negative electrode can, a material having a low hardness, that is, aluminum, nickel, or copper is disposed on the inner surface side. It becomes easy to form a concavo-convex structure. Moreover, aluminum, nickel, or copper is arrange | positioned at the inner surface side of a positive electrode can and a negative electrode can, and the contact resistance between each electrode and a current collection part is reduced significantly by comprising a current collection part from these materials. It becomes possible.

  In the non-aqueous electrolyte secondary battery of the present invention, in the above configuration, it is more preferable that a shape of the current collecting portion in plan view is a lattice shape or a ring shape including the flat portion and the concave portion. .

  According to the present invention, the contact area between each electrode and the current collector is further increased because the current collector has the above-described shape in plan view, so that the contact resistance can be effectively reduced.

  In the non-aqueous electrolyte secondary battery of the present invention, in the above configuration, it is more preferable that the positive electrode and the negative electrode contain at least one of graphite and carbon black as a conductive auxiliary.

  ADVANTAGE OF THE INVENTION According to this invention, the diffusion resistance in each electrode can be reduced more effectively because a positive electrode and a negative electrode contain graphite or carbon black.

  In the non-aqueous electrolyte secondary battery of the present invention, in the above structure, the non-aqueous electrolyte preferably contains at least lithium bis (fluorosulfonyl) imide (LiFSI) as a supporting salt.

  According to the present invention, when the supporting salt used for the non-aqueous electrolyte is LiFSI having a small molecular diameter, the diffusion resistance is reduced, so that the charge transfer is accelerated and the conductivity is improved. Can be significantly reduced.

  In the nonaqueous electrolyte secondary battery of the present invention, in the above configuration, the content of lithium bis (fluorosulfonyl) imide (LiFSI) contained as the supporting salt in the nonaqueous electrolyte is the total amount of the nonaqueous electrolyte. It is preferable that it is the range of 10-23 mass% with respect to.

  According to the present invention, by limiting the content of LiFSI in the non-aqueous electrolyte to the above range, the effect of reducing the diffusion resistance and improving the conductivity can be obtained more remarkably.

  In the non-aqueous electrolyte secondary battery of the present invention, in the above configuration, the non-aqueous electrolyte contains propylene carbonate (PC), ethylene carbonate (EC) and dimethoxyethane (DME) as a volume ratio as the organic solvent. It is preferable to contain in the range of {PC: EC: DME} = {0.5-1.5: 0.5-1.5: 1-3}.

According to the present invention, as the organic solvent constituting the non-aqueous electrolyte, first, a large discharge capacity is obtained by using PC and EC, which are cyclic carbonate solvents having a high dielectric constant and a high solubility of the supporting salt. Is possible. Moreover, since PC and EC have a high boiling point, for example, a non-aqueous electrolyte that hardly volatilizes even when used or stored in a high temperature environment can be obtained.
Further, by using PC having a melting point lower than that of EC as an organic solvent, it becomes possible to improve discharge characteristics particularly at a low temperature.
Further, by using DME which is a chain ether solvent having a low melting point as the organic solvent, the discharge characteristics at a low temperature are improved as described above. Further, since DME has a low viscosity, the conductivity of the nonaqueous electrolyte is improved. Furthermore, DME solvates with Li ion, and thereby a larger discharge capacity can be obtained as a non-aqueous electrolyte secondary battery.

  Next, the method for producing a non-aqueous electrolyte secondary battery of the present invention forms a bottomed cylindrical positive electrode can and a covered cylindrical negative electrode can having an opening by processing a metal plate material, and the positive electrode A storage container forming step for obtaining a storage container composed of a can and the negative electrode can, a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and a positive electrode including the negative electrode active material and the positive electrode and the negative electrode are disposed in the storage container. A non-aqueous electrolyte secondary battery manufacturing method including a separator and a battery assembly process that stores a non-aqueous electrolyte containing at least a supporting salt and an organic solvent, wherein the storage container forming process includes the positive electrode Including a process of forming a current collecting part having a concavo-convex structure composed of a flat part and a concave part by selectively removing at least a part of the inner bottom face of the can and the inner lid face of the negative electrode can by an etching process. And

  According to the present invention, in the storage container forming step, the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can are processed by an etching process to form a current collecting portion having a concavo-convex structure, thereby generating a processed piece or the like. Therefore, it is possible to prevent short circuit in the battery and imperfect fixing of the electrode. In addition, since the current collector can be formed with a finely patterned uneven structure by the etching process, the contact area between each electrode is increased and the contact resistance is reduced. Moreover, since it is the method of forming the current collection part of an uneven | corrugated structure by an etching process, an uneven | corrugated shape does not arise in the outer surface side of a positive electrode can and a negative electrode can. Therefore, in particular, a non-aqueous electrolyte secondary that can supply a large current pulse in the region of about 1 mA to several mA, can discharge for a long time while maintaining a sufficient discharge current and voltage, and has excellent discharge characteristics and appearance characteristics. Batteries can be manufactured with high yield.

According to the non-aqueous electrolyte secondary battery of the present invention, the current collector having an uneven structure integrated with the positive electrode can and the negative electrode can is provided on the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can. Therefore, the contact area between each electrode and each current collector increases, and the contact resistance between them decreases.
As a result, the internal resistance can be significantly reduced, and particularly in a small non-aqueous electrolyte secondary battery capable of supplying a large current pulse in the region of about 1 mA to several mA, a state in which sufficient discharge current and voltage are maintained. Can discharge for a long time, and excellent discharge characteristics can be obtained. In addition, the current collector part of the concavo-convex structure is provided on the inner surface side of the positive electrode can and the negative electrode can, and the rugged shape is not generated on the outer surface side, so that excellent appearance characteristics are obtained and work pieces and the like are generated during manufacturing. There is no, and it is excellent in yield.
Accordingly, it is possible to provide a non-aqueous electrolyte secondary battery that can sufficiently satisfy the discharge characteristics required in various small electronic devices to which a small non-aqueous electrolyte secondary battery such as a coin type is applied and that can improve the device characteristics. Is possible.

Further, according to the method for manufacturing a non-aqueous electrolyte secondary battery of the present invention, in the storage container forming step, the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can are etched to form a current collecting portion having a concavo-convex structure. Since the method is used, the current collector can be formed with a finely-patterned concavo-convex structure without producing a work piece or the like.
Accordingly, a small non-aqueous electrolyte secondary battery excellent in discharge characteristics and appearance characteristics capable of supplying a large current pulse in the region of about 1 mA to several mA, in which the internal resistance of the battery is significantly reduced, is obtained with high yield. It becomes possible to manufacture.

FIG. 1 is a cross-sectional view schematically showing a non-aqueous electrolyte secondary battery configured in a coin type (button type) according to an embodiment of the present invention. FIG. 2 is a diagram schematically illustrating a non-aqueous electrolyte secondary battery configured as a coin type (button type) according to an embodiment of the present invention, and the inner bottom surfaces of a positive electrode can and a negative electrode can constituting a storage container. It is the schematic which shows an example of the planar view shape of the current collection part provided in. FIG. 3 is a diagram schematically illustrating a non-aqueous electrolyte secondary battery configured as a coin type (button type) according to an embodiment of the present invention, and the inner bottom surfaces of the positive electrode can and the negative electrode can constituting the storage container. It is the schematic which shows the other example of the planar view shape of the current collection part provided in FIG. FIG. 4 is a diagram schematically illustrating a non-aqueous electrolyte secondary battery configured in a coin type (button type) according to an embodiment of the present invention, and the inner bottom surfaces of a positive electrode can and a negative electrode can constituting a storage container. It is the schematic which shows the other example of the planar view shape of the current collection part provided in FIG. FIG. 5 is a diagram schematically illustrating a non-aqueous electrolyte secondary battery configured in a coin type (button type) according to an embodiment of the present invention, and the inner bottom surfaces of the positive electrode can and the negative electrode can constituting the storage container. It is sectional drawing which shows an example of the principal part of the current collection part provided in. FIG. 6 is a diagram schematically illustrating a non-aqueous electrolyte secondary battery configured in a coin type (button type) according to an embodiment of the present invention, and the inner bottom surfaces of the positive electrode can and the negative electrode can constituting the storage container. It is sectional drawing which shows the other example of the principal part of the current collection part provided in.

  Hereinafter, embodiments of the nonaqueous electrolyte secondary battery and the manufacturing method thereof according to the present invention will be described, and each configuration will be described in detail with reference to FIGS. In addition, the nonaqueous electrolyte secondary battery described in the present invention specifically includes an active material used as a positive electrode or a negative electrode and a nonaqueous electrolyte contained in a container. Is applicable to electrochemical cells such as lithium ion capacitors.

<Nonaqueous electrolyte secondary battery>
The non-aqueous electrolyte secondary battery 1 of this embodiment shown in FIG. 1 is a so-called coin (button) type battery. The non-aqueous electrolyte secondary battery 1 includes a positive electrode 10 including a positive electrode active material capable of occluding and releasing lithium ions, a negative electrode 20 including a negative electrode active material capable of occluding and releasing lithium ions in a storage container 2, and A separator 30 disposed between the positive electrode 10 and the negative electrode 20 and a nonaqueous electrolyte 50 including at least a supporting salt and an organic solvent are provided.

  More specifically, the non-aqueous electrolyte secondary battery 1 is accommodated between the bottomed cylindrical positive electrode can 12 and the opening 12 a of the positive electrode can 12 with a gasket 40 interposed therebetween, and is accommodated between the positive electrode can 12. A storage container 2 that has a closed cylindrical (hat-shaped) negative electrode can 22 that forms a space, and seals the storage space by caulking the periphery of the opening 12a of the positive electrode can 12 toward the inside, that is, the negative electrode can 22 side. Is provided.

In the storage space sealed by the storage container 2, the positive electrode 10 provided on the positive electrode can 12 side and the negative electrode 20 provided on the negative electrode can 22 side are arranged to face each other via the separator 30, and the nonaqueous electrolyte 50 is further provided. Filled. In the example shown in FIG. 1, a lithium foil 60 is interposed between the negative electrode 20 and the separator 30.
As shown in FIG. 1, the gasket 40 is narrowly inserted along the inner peripheral surface of the positive electrode can 12 and connected to the outer periphery of the separator 30 to hold the separator 30.
Further, the positive electrode 10, the negative electrode 20, and the separator 30 are impregnated with a nonaqueous electrolyte 50 filled in the storage container 2.

  As shown in FIG. 1, the non-aqueous electrolyte secondary battery 1 has a positive electrode 10 electrically connected to a positive electrode current collector (current collector) 14 disposed on the inner bottom surface of the positive electrode can 12. The negative electrode 20 is electrically connected to a negative electrode current collector (current collector) 24 disposed on the inner lid surface of the negative electrode can.

  The nonaqueous electrolyte secondary battery 1 of the present embodiment is configured as described above, so that lithium ions move from one of the positive electrode 10 and the negative electrode 20 to the other, thereby accumulating (charging) charge. The electric charge can be discharged (discharged).

  In the nonaqueous electrolyte secondary battery 1 of the present embodiment, the positive electrode current collector 14 and the negative electrode current collector 24 are formed from flat portions 14a and 24a and recesses 14b and 24b provided on the inner bottom surface or the inner lid surface. It has an uneven structure.

  The present inventor has intensively studied in order to improve the discharge characteristics of a small non-aqueous electrolyte secondary battery that can supply a large current pulse in a range of about 1 mA to several mA used for various small electronic devices. As a result, a concave-convex structure is formed on the inner bottom surface of the positive electrode can 12 and the inner lid surface of the negative electrode can 22 constituting the storage container 2, and this portion is integrated with the positive electrode can 12 or the negative electrode can (positive electrode current collector). Portion 14, negative electrode current collector 24), the contact area between positive electrode 10 and negative electrode 20 and each current collector (positive electrode current collector 14, negative electrode current collector 24) is reliably increased, and contact resistance is increased. It was found that can be reduced. Further, it has been found that by providing a concavo-convex structure only on the inner surface side of the positive electrode can 12 and the negative electrode can 22, no concavo-convex shape is formed on the outer surface side, and excellent appearance characteristics can be maintained.

  Furthermore, when forming uneven structures on the inner bottom surface of the positive electrode can 12 and the inner lid surface of the negative electrode can 22, the present inventors selectively remove a part of the inner bottom surface and the inner lid surface by an etching process. Thus, it has been found that since the uneven structure can be formed in a fine pattern, a non-aqueous electrolyte secondary battery with a further reduced contact resistance can be manufactured by further increasing the contact area between each electrode and each current collector. Moreover, by forming the concavo-convex structure by etching the inner bottom surface of the positive electrode can 12 and the inner lid surface of the negative electrode can 22, it is possible to suppress the occurrence of workpieces and the like, causing a short circuit in the battery, It was found that immobilization could be prevented and the yield was greatly improved.

  That is, the present inventors are able to perform a long-time discharge in a small coin cell or the like with a low discharge current while maintaining a sufficient discharge current and voltage, and are non-aqueous with excellent discharge characteristics, appearance characteristics, and yield. The inventors have found that an electrolyte secondary battery can be realized, and have completed the present invention as described in detail below.

[Positive electrode can and negative electrode can (storage container)]
As described above, the storage container 2 is formed by combining the positive electrode can 12 and the negative electrode can 22 that forms a storage space between the positive electrode can 12.

  The positive electrode can 12 has a bottomed cylindrical shape and has a circular opening 12a in plan view. As a material of such a positive electrode can 12, a conventionally well-known thing can be used without a restriction | limiting, For example, stainless steel, such as SUS329J4L, is mentioned.

  Further, the negative electrode can 22 is configured in a covered cylindrical shape (hat shape), and the tip end portion 22a is configured to enter the positive electrode can 12 through the opening 12a. As the material of the negative electrode can 22, a conventionally known stainless steel can be used as in the material of the positive electrode can 12. For example, SUS304-BA or the like can be used.

  In addition, the positive electrode can 12 and the negative electrode can 22 include, in addition to the above-described single-layer metal plate made of stainless steel, for example, a multilayer clad having the above-mentioned stainless steel on the outer surface side and aluminum, nickel, or copper on the inner surface side. Materials can be used. As such a clad material, for example, a material formed into a plate shape by press-contacting aluminum, nickel or copper to stainless steel can be cited.

  The plate thickness of the metal plate material used for the positive electrode can 12 and the negative electrode can 22 is not limited to a single layer or multiple layers (cladding material), and is generally about 0.1 to 0.3 mm. For example, the positive electrode can 12 and the negative electrode can A plate material having an average plate thickness of about 0.20 mm can be used.

  As shown in FIG. 1, the positive electrode can 12 and the negative electrode can 22 are fixed by caulking the periphery of the opening 12a of the positive electrode can 12 toward the negative electrode can 22 with a gasket 40 interposed therebetween. The electrolyte secondary battery 1 is hermetically held in a state where an accommodation space is formed. For this reason, the maximum inner diameter of the positive electrode can 12 is larger than the maximum outer diameter of the negative electrode can 22.

In the nonaqueous electrolyte secondary battery 1 according to the present invention, as described above, the positive electrode current collector 14 having a concavo-convex structure including the flat portion 14 a and the concave portion 14 b is provided on the inner bottom surface of the positive electrode can 12. .
Similarly, on the inner lid surface of the negative electrode can 22, a negative electrode current collector 24 having a concavo-convex structure including a flat portion 24 a and a concave portion 24 b is provided.
That is, in the nonaqueous electrolyte secondary battery 1, the inner bottom surface of the positive electrode can 12 also serves as a current collector (positive electrode current collector 14) on the positive electrode 10 side, and the inner lid surface of the negative electrode can 22 is a current collector on the negative electrode 20 side. The battery body (negative electrode current collector 24) is also configured, and the battery can and the current collector are respectively integrated.

  The nonaqueous electrolyte secondary battery 1 according to the present invention includes the current collectors (the positive electrode current collector 14 and the negative electrode current collector 24) having an uneven structure integrated with the positive electrode can 12 or the negative electrode can 22. In addition, the contact area between the positive electrode 10 and the positive electrode current collector 14 and between the negative electrode 20 and the negative electrode current collector 24 increases. This is because at least a part of the positive electrode 10 or the negative electrode 20 made of a material to be described in detail later enters each of the recesses 14b and 24b provided in the positive electrode current collector 14 and the negative electrode current collector 24. This is because the contact area between each and the current collector increases. As described above, the contact area between each electrode and each current collector increases, so that the contact resistance between them is reduced, and the internal resistance of the nonaqueous electrolyte secondary battery 1 can be significantly reduced. it can. Thereby, in particular, in the small nonaqueous electrolyte secondary battery 1 capable of supplying a large current pulse in the region of about 1 mA to several mA, it becomes possible to discharge for a long time while maintaining a sufficient discharge current and voltage. Compared with a conventional non-aqueous electrolyte secondary battery, very excellent discharge characteristics can be obtained.

  In the nonaqueous electrolyte secondary battery 1 according to the present invention, the shape of the positive electrode current collector 14 and the negative electrode current collector 24 having a concavo-convex structure in plan view can increase the contact area with the positive electrode 10 or the negative electrode 20. If it is a simple shape, it will not specifically limit. For example, the shape of the positive electrode current collector 14 and the negative electrode current collector 24 in a plan view is shown in FIG. 3 in addition to a lattice shape including flat portions 14a (24a) and concave portions 14b (24b) as shown in FIG. Such a ring shape or a shape in which a concave portion is formed in a circular shape as shown in FIG. 4 is preferable. Here, in the example shown in FIG. 2, a plurality of flat portions 14 a (24 a) elongated in plan view are arranged at equal intervals in the vertical and horizontal directions, thereby a plurality of concave portions 14 b (24 b) having a rectangular shape in plan view. Are aligned vertically and horizontally. Moreover, in the example shown in FIG. 3, it is the structure by which the some flat part 14a (24a) made into the ring shape of planar view has been arrange | positioned at zigzag form.

  Moreover, the positive electrode current collector 14 and the negative electrode current collector 24 in the example shown in FIG. 4 have a plurality of concave portions 14b (24b) that are circular in a plan view and are arranged in a staggered manner. Although the detailed illustration of the positive electrode current collector 14 and the negative electrode current collector 24 shown in FIG. 4 is omitted in FIG. 4, the bottom edges of the recesses 14b and 24b have a shape close to a semicircular cross section. (See the cross-sectional shape shown in FIG. 5). In addition, the positive electrode current collector and the negative electrode current collector are not limited to the above shapes. For example, although detailed illustration is omitted, the shape of the concave portion in plan view is a rhombus shape or a triangle shape, and is arranged in a staggered manner. The same effects as described above can be obtained.

  In the nonaqueous electrolyte secondary battery 1 according to the present invention, the positive electrode current collector 14 and the negative electrode current collector 24 have the above-described shape in plan view, so that the contact area between each electrode and each current collector is small. Furthermore, since it increases, it becomes possible to reduce contact resistance effectively.

  Further, as shown in FIG. 5, in the cross-sectional shapes of the positive electrode current collector 14 and the negative electrode current collector 24, the bottom edges of the recesses 14 b and 24 b are not formed in a square shape. In the case where the conductive adhesive 25 (see FIG. 6) is interposed between the electrical parts, it is preferable from the viewpoint that the conductive adhesive 25 can be uniformly applied. Further, as shown in the illustrated example, the bottom edges of the recesses 14b and 24b are rounded in cross-sectional shape, and more preferably as close to a semicircular cross-sectional shape as possible. Thus, since the edge part of the bottom face of the recessed parts 14b and 24b is rounded, as shown in FIG. 6, the conductive adhesive 25 surely enters the recessed parts 14b and 24b. The occurrence of unevenness is suppressed, and the conductive adhesive 25 can be uniformly applied to each current collecting portion. On the other hand, if the bottom edge of the concave portion is formed in a square shape, the conductive adhesive 25 will not easily enter this portion, and application unevenness may occur.

  In the case where the concavo-convex structure is formed by an etching process, the corners of the bottom surfaces of the recesses 14b and 24b have a shape having a constant R as shown in the example due to the characteristics of this process. Thereby, in this invention, since the conductive adhesive 25 can be apply | coated uniformly with respect to each current collection part, the contact resistance between each electrode and each current collection part can be reduced effectively.

  Moreover, it is preferable that the ratio of the flat parts 14a and 24a with respect to the area of each current collection part is 10 to 50% in the positive electrode current collection part 14 and the negative electrode current collection part 24. By making the ratio of the flat portions 14a and 24a in the positive electrode current collector 14 and the negative electrode current collector 24 within the above range, the contact area between each electrode and the current collector is reliably increased, and the contact between them. The area can be significantly reduced. Here, if the ratio of the flat portions 14a and 24a in the positive electrode current collector 14 and the negative electrode current collector 24 is less than the lower limit of the above range, the ratio of the recesses 14b and 24b increases too much, and if the upper limit of the above range is exceeded. The ratio of the flat portions 14a and 24a increases too much, and in either case, it is difficult to contribute to an increase in the contact area.

  The average depth D of the concave portions 14b and 24b of the positive electrode current collector 14 and the negative electrode current collector 24 is the thickness of the metal plate material used for the positive electrode can 12 and the negative electrode can 22 as well as the positive electrode current collector 14 and the negative electrode current collector. Although it depends on the hardness of the positive electrode 10 and the negative electrode 20 pressed against the portion 24 and the deformation state at the time of charge and discharge, it is about 1/2 to 1/5 of the thickness of the positive electrode 10 and the negative electrode 20 described later in detail. A range is preferred. By setting the average depth D of the recesses 14b and 24b within the above range, the embedding allowance for each electrode of each current collector having a concavo-convex structure is optimized, and a large contact area can be secured, and each electrode It is securely fixed to the electric part, and it is possible to prevent inconvenience due to electrode displacement or the like.

On the other hand, when the average depth D of the concave portions 14b and 24b exceeds 1/2 with respect to the thickness of the positive electrode 10 and the negative electrode 20, the flat portions 14a and 24a are in a state of deeply biting into each electrode. May crack or crack, or conversely, the number of contact points between each electrode and each current collector may be reduced, resulting in incomplete electrical connection. In addition, since the flat portions 14a and 24a are deeply embedded in each electrode, a high pressing force is required in the pressure contact process, which increases the cost of manufacturing equipment and the like.
In addition, if the average depth D of the recesses 14b and 24b is less than 1/5 of the thickness of the positive electrode 10 and the negative electrode 20, the embedding allowance for each electrode of each current collector having an uneven structure is too small. Both are difficult to fix, and problems such as electrode displacement may occur. Also, the contact area between each electrode and each current collector is almost the same as when each current collector is configured on a flat surface, and it may be difficult to obtain the effect of adopting the uneven structure. .

  Further, in the nonaqueous electrolyte secondary battery 1 according to the present invention, as described above, the conductive adhesive 25 is applied to the positive electrode current collector 14 and the negative electrode current collector 24, and the respective recesses 14 b and 24 b are formed. It is preferable to allow the conductive adhesive 25 to enter inside and to interpose the conductive adhesive 25 between each electrode and each current collector from the viewpoint of further improving the adhesion and conductivity between them. As described above, in order to interpose the conductive adhesive 25 between each electrode and each current collector, a conductive material is provided in the concave portion of each current collector having an uneven structure as shown in FIG. It is preferable to provide a margin enough for the adhesive 25 to be interposed between each electrode and each current collector. More specifically, the average depth D of the recesses 14b and 24b is preferably about several tens to several hundreds μm in consideration of embedding by the positive electrode 10 and the negative electrode 20 and the intervention of the conductive adhesive 25. .

  As shown in FIG. 2, the flat portions 14 a and 14 b that are formed in a convex shape in a cross-sectional view have a narrow shape, as will be described later, with respect to the pellets constituting the positive electrode 10 and the negative electrode 20. This is preferable from the viewpoint of increasing the contact area between each electrode and each current collector. For example, when the shape of the positive electrode current collector 14 and the negative electrode current collector 24 in plan view is a lattice shape as shown in FIG. 2, the width W1 is set to 0.1 to 0.1 as shown in the sectional view of FIG. It is preferably about 0.3 mm.

  On the other hand, the width W2 of the recesses 14b and 24b is preferably in the range of about 1 to 2 mm. In the example shown in FIG. 2, since the concave portions 14b and 24b are formed in a square shape, it is preferable that the width is in the range of the width W2. If the width W2 of the recesses 14b and 24b is less than 1 mm, the conductive adhesive 25 is less likely to enter the recesses 14b and 24b when the conductive adhesive 25 is applied to the positive electrode current collector 14 and the negative electrode current collector 24. Become. Further, if the width W2 of the recesses 14b and 24b exceeds 2 mm, it may be difficult to contribute to an increase in the contact area between each electrode and each current collector.

  In the case where the concave portions 14b (24b) having a circular shape in plan view are arranged in a staggered manner as in the example shown in FIG. 4, for example, the minimum distance between the concave portions 14b (24b), that is, flat between the concave portions. The dimension of the portion where the width of the portion 14a (24a) is the shortest is preferably about 0.1 to 0.3 mm, similar to the above W1.

  In addition, as described above, when each current collector has a configuration in which concave portions having a rhombus shape in plan view are arranged in a staggered pattern, the diagonal long side dimension (LW) of the rhombus × diagonal short side dimension (SW) It is preferable that the relationship is LW: 2.5 mm or less × SW: 1.4 mm or less because a large contact area can be secured between each electrode and each current collector. Moreover, it is preferable that the width | variety of each flat part between each recessed part in this case shall be about 0.1-0.3 mm like said W1.

  In addition, as described above, even when each current collecting portion has a configuration in which triangular concave portions in plan view are arranged in a staggered manner, the width of each flat portion between the concave portions is 0 as in the above W1. It is preferable to be about 1 to 0.3 mm.

  In addition, when the single layer board | plate material which consists of stainless steel is used for the positive electrode can 12 and the negative electrode can 22, the hardness of the positive electrode current collection part 14 and negative electrode current collection part 24 which consist of an uneven structure is raised more. As described above, the positive electrode current collector 14 and the negative electrode current collector 24, which are formed of the flat portions 14a and 24a and the concave portions 14b and 24b, are increased in hardness, so that the positive electrode 10 or the negative electrode 20 is pressed into contact with these current collectors. In this case, the current collectors are not crushed and the depths of the recesses 14b and 24b are maintained. As a result, the positive electrode 10 or the negative electrode 20 can easily enter the recesses 14b and 24b, and the electrodes can enter deep into the recesses. Therefore, the contact area between each electrode and the current collector is reduced. Will definitely increase. Therefore, since the contact resistance between each electrode and each current collector can be greatly reduced, the discharge characteristics of the nonaqueous electrolyte secondary battery 1 can be further improved.

  On the other hand, when the positive electrode can 12 and the negative electrode can 22 are made of a multi-layer plate made of a clad material whose outer surface is made of a stainless steel material and whose inner surface is an aluminum material, nickel material or copper, the inner surface is low in hardness. Since the material is arranged, it becomes easy to perform the uneven processing. That is, it is easy to form the positive electrode current collector 14 or the negative electrode current collector 24 having the concavo-convex structure on the inner bottom surface of the positive electrode can 12 and the inner lid surface of the negative electrode can 22 by an etching process described in detail later. Become. Moreover, aluminum or nickel is arrange | positioned at the inner surface side of the positive electrode can 12 and the negative electrode can 22, and the positive electrode current collection part 14 or the negative electrode current collection part 24 is comprised from these materials, By each electrode and current collection part, The contact resistance between them is greatly reduced.

  As the position where the uneven structure is formed on the inner surface side of the positive electrode can 12 and the negative electrode can 22, since the negative electrode can 22 is a covered cylindrical (hat-shaped) member, the entire inner cover surface is usually etched to form the uneven structure. There is no problem in forming. On the other hand, since the positive electrode can 12 has an adhesive portion with the gasket 40 described later at the end of the inner bottom surface, it is necessary to form an uneven structure only in a position avoiding the adhesive portion with the gasket 40 in design. is there. Moreover, it is preferable to form an uneven structure in this whole area | region by performing an etching process to the whole area | region which the positive electrode 10 touches among the inner bottom faces of the positive electrode can 12. FIG.

  Although details of the etching process for forming the concavo-convex structure on the inner bottom surface of the positive electrode can 12 and the inner lid surface of the negative electrode can 22 will be described later, any method of wet etching or dry etching may be employed. In addition, although it is possible to form a concavo-convex structure using a method by sandblasting, it is most preferable to use a method by wet etching from the viewpoint of workability with respect to a metal plate material. In the present invention, the positive electrode current collector 14 or the negative electrode current collector 24 having a concavo-convex structure is formed by an etching process, so that a work piece or the like is not produced during manufacturing, and the nonaqueous electrolyte secondary battery is excellent in yield. 1 is obtained. Moreover, in the nonaqueous electrolyte secondary battery 1 according to the present invention, the concavo-convex structure of the positive electrode current collector 14 or the negative electrode current collector 24 provided on the inner surface side of the positive electrode can 12 and the negative electrode can 22 is formed by etching treatment. Thus, since the uneven shape does not occur on the outer surface side, the appearance characteristics are excellent.

  In addition, in the example shown in FIG. 1, although the front-end | tip part 22a of the negative electrode can 22 is made into the shape turned up on the outer surface side, it is not limited to this, For example, the end surface of the metal plate material was used as the front-end | tip part 22a. Even in the case where the folded shape is not provided, the present invention can be applied.

  Further, as a non-aqueous electrolyte secondary battery to which the configuration described in detail in the present embodiment can be applied, for example, a 920 size (outer diameter φ9 mm × X) which is a general size of a coin-type non-aqueous electrolyte secondary battery In addition to the height of 2.0 mm, various sizes, particularly small size batteries can be mentioned.

[gasket]
As shown in FIG. 1, the gasket 40 is formed in an annular shape along the inner peripheral surface of the positive electrode can 12, and the tip end portion 22 a of the negative electrode can 22 is disposed inside the annular groove 41.
The gasket 40 is preferably made of a resin having a heat deformation temperature of 230 ° C. or higher, for example. If the heat deformation temperature of the resin material used for the gasket 40 is 230 ° C. or higher, heat is generated when the nonaqueous electrolyte secondary battery 1 is used or stored in a high temperature environment or during use of the nonaqueous electrolyte secondary battery 1. Even if it occurs, it is possible to prevent the non-aqueous electrolyte 50 from leaking due to significant deformation of the gasket.

  Examples of the material of the gasket 40 include polypropylene resin (PP), polyphenylene sulfide (PPS), polyethylene terephthalate (PET), polyamide (PA), liquid crystal polymer (LCP), and tetrafluoroethylene-perfluoroalkyl vinyl ether. Polymer resin (PFA), polyether ether ketone resin (PEEK), polyether nitrile resin (PEN), polyether ketone resin (PEK), polyarylate resin, polybutylene terephthalate resin (PBT), polycyclohexanedimethylene terephthalate resin, Examples thereof include polyether resins such as polyether sulfone resin (PES), polyamino bismaleimide resin, polyether imide resin, and fluorine resin. Among these, it is preferable to use a polypropylene resin for the gasket 40 from the viewpoint that the gasket can be prevented from being remarkably deformed during use or storage in a high temperature environment, and the sealing performance of the nonaqueous electrolyte secondary battery is further improved.

  Moreover, the gasket 40 can be suitably used by adding glass fiber, My Cowisker, ceramic fine powder or the like to the above material in an addition amount of 30% by mass or less. By using such a material, it is possible to prevent the non-aqueous electrolyte 50 from leaking due to significant deformation of the gasket due to high temperature.

  Further, a sealing agent may be further applied to the inner surface of the annular groove of the gasket 40. As such a sealing agent, asphalt, epoxy resin, polyamide resin, butyl rubber adhesive, or the like can be used. The sealing agent is applied to the inside of the annular groove 41 and then dried.

  The gasket 40 is sandwiched between the positive electrode can 12 and the negative electrode can 22 and at least a part of the gasket 40 is compressed. However, the compression ratio is not particularly limited, and the nonaqueous electrolyte secondary battery is not limited. What is necessary is just to make it the range which can seal the inside of 1 reliably, and the fracture | rupture does not arise in the gasket 40.

[Nonaqueous electrolyte]
The nonaqueous electrolyte secondary battery 1 of the present invention uses a nonaqueous electrolyte 50 that includes at least an organic solvent and a supporting salt. Usually, the non-aqueous electrolyte used in the non-aqueous electrolyte secondary battery is made of a support salt dissolved in a non-aqueous solvent such as an organic solvent, taking into account the heat resistance and viscosity required for the non-aqueous electrolyte 50. Its characteristics are determined.

  In general, as a supporting salt contained in a nonaqueous electrolyte of a nonaqueous electrolyte secondary battery, a known Li compound added as a supporting salt to a nonaqueous electrolyte, specifically, lithium bis (fluorosulfonyl) imide (LiFSI) ) Or lithium bis (trifluoromethanesulfonyl) imide (LiTFSI). In the non-aqueous electrolyte secondary battery 1 according to the present invention, the supporting salt contained in the non-aqueous electrolyte 50 is not particularly limited, but it is preferable to employ one containing LiFSI. Thus, since the nonaqueous electrolyte 50 contains LiFSI having a small molecular diameter as a supporting salt, the diffusion resistance in the nonaqueous electrolyte 50 is reduced, so that the movement of electric charges is accelerated and the conductivity is improved. As a result, the internal resistance of the battery can be significantly reduced.

  The content of the supporting salt in the nonaqueous electrolyte 50 can be determined in consideration of the type of the supporting salt and the type of the positive electrode active material described later. In the present invention, the LiFSI content in the non-aqueous electrolyte 50 is more preferably in the range of 10 to 23 mass% (1 mol / L) with respect to the total amount of the non-aqueous electrolyte 50. By limiting the content of LiFSI in the nonaqueous electrolyte 50 to the above range, the effect of reducing the diffusion resistance and improving the conductivity can be obtained more remarkably. Therefore, it is possible to obtain even better discharge characteristics in a small non-aqueous electrolyte secondary battery such as a coin type having a relatively large discharge current and improved discharge characteristics as compared with the prior art.

In addition, by setting the LiFSI content in the nonaqueous electrolyte 50 within the above range, it is possible to suppress a voltage drop at the initial stage of discharge, and to improve discharge characteristics in a low temperature environment, which is sufficient in a wide temperature range. Discharge capacity is obtained.
In addition, the LiFSI content in the nonaqueous electrolyte 50 is more preferably in the range of 13 to 21% by mass with respect to the total amount of the nonaqueous electrolyte 50 from the viewpoint that the above effect is remarkably obtained.

  In addition, when the support salt concentration in the nonaqueous electrolyte 50 exceeds the upper limit of the above range, it is difficult to obtain a discharge capacity, and when it falls below the above lower limit, the internal resistance may be greatly increased. . For this reason, since the concentration of the supporting salt (LiFSI) in the nonaqueous electrolyte 50 is too high or too low, the battery characteristics may be adversely affected.

In the non-aqueous electrolyte secondary battery 1 according to the present invention, the organic solvent used for the non-aqueous electrolyte 50 is not particularly limited. For example, PC, EC that are cyclic carbonate solvents, and DME that is a chain ether solvent. Can be used as a mixed solvent containing a mixing ratio within an appropriate range.
Ensuring sufficient discharge characteristics in a small non-aqueous electrolyte secondary battery 1 capable of supplying a large current pulse in the region of about 1 mA to several mA by optimizing the composition of the organic solvent used in the non-aqueous electrolyte 50 In addition, the nonaqueous electrolyte secondary battery 1 capable of maintaining a sufficient discharge capacity in a wide temperature range including a low temperature environment can be realized.

  In general, when a non-aqueous electrolyte containing an organic solvent is used in a non-aqueous electrolyte secondary battery, the temperature dependence of the conductivity increases due to poor solubility of the lithium salt, which is lower than the characteristics at room temperature. There is a problem that the characteristics below are greatly deteriorated. On the other hand, in order to improve the low temperature characteristics, for example, when an asymmetrically structured ethyl methyl carbonate or acetate ester, which is a chain carbonate, is used as the organic solvent for the nonaqueous electrolyte, conversely, There exists a problem that the characteristic as an electrolyte secondary battery falls. Even when an organic solvent such as ethyl methyl carbonate is used for the non-aqueous electrolyte, the solubility of the lithium salt is still poor and there is a limit to improving the low-temperature characteristics.

Therefore, in the non-aqueous electrolyte secondary battery 1 according to the present invention, propylene carbonate (PC), ethylene carbonate (EC), and dimethoxyethane (DME) are used as organic solvents constituting the non-aqueous electrolyte 50 in an appropriate range. It is preferable to use what is contained.
Specifically, it is possible to obtain a large discharge capacity by using PC and EC having a high dielectric constant and a high solubility of the supporting salt as the cyclic carbonate solvent. Moreover, since PC and EC have a high boiling point, a non-aqueous electrolyte that hardly volatilizes even when used or stored in a high temperature environment is obtained.
Moreover, it becomes possible to improve a low temperature characteristic by using PC with melting | fusing point lower than EC as a cyclic carbonate solvent mixed with EC.
Moreover, low temperature characteristics are improved by using DME having a low melting point as a chain ether solvent. Moreover, since DME has a low viscosity, the electrical conductivity of the nonaqueous electrolyte is improved. Furthermore, DME solvates with Li ion, and thereby a large discharge capacity can be obtained as a non-aqueous electrolyte secondary battery.

  The cyclic carbonate solvent has a structure represented by the following (Chemical Formula 1). For example, propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), trifluoroethylene carbonate (TFPC), chloro Examples include ethylene carbonate (ClEC), trifluoroethylene carbonate (TFEC), difluoroethylene carbonate (DFEC), and vinylene carbonate (VEC). In the nonaqueous electrolyte secondary battery 1 according to the present invention, in particular, in consideration of ease of film formation on the electrode on the negative electrode 20, improvement in low temperature characteristics, and improvement in capacity retention at high temperatures As the cyclic carbonate solvent having the structure represented by the following (Chemical Formula 1), it is preferable to use two types of PC and EC.

  However, in the above (Chemical Formula 1), R1, R2, R3, and R4 each represent hydrogen, fluorine, chlorine, an alkyl group having 1 to 3 carbon atoms, or a fluorinated alkyl group. Moreover, R1, R2, R3, and R4 in the above (Chemical Formula 1) may be the same or different.

  As described above, a large discharge capacity can be obtained by using PC and EC having a high dielectric constant and a high solubility of the supporting salt as the cyclic carbonate solvent as the organic solvent used in the non-aqueous electrolyte 50. . Moreover, since PC and EC have a high boiling point, a non-aqueous electrolyte that hardly volatilizes even when used or stored in a high temperature environment can be obtained. Furthermore, excellent low-temperature characteristics can be obtained by using PC having a melting point lower than that of EC as a cyclic carbonate solvent by mixing with EC.

  The chain ether solvent has a structure represented by the following (Chemical Formula 2), and examples thereof include 1,2-dimethoxyethane (DME) and 1,2-diethoxyethane (DEE). In the present embodiment, in particular, as a chain ether solvent having a structure represented by the following (Chemical Formula 2) from the viewpoint of improving the low temperature characteristics while securing the capacity at room temperature in addition to the viewpoint of improving the conductivity. It is preferable to use DME which easily solvates with lithium ions.

  However, in the above (Chemical Formula 2), R5 and R6 each represent hydrogen, fluorine, chlorine, an alkyl group having 1 to 3 carbon atoms, or a fluorinated alkyl group. R5 and R6 may be the same or different.

  As described above, low temperature characteristics are improved by using DME having a low melting point as a chain ether solvent for the organic solvent used for the non-aqueous electrolyte 50. Further, since DME has a low viscosity, the electrical conductivity of the nonaqueous electrolyte is improved. Furthermore, since DME solvates to Li ions, a large discharge capacity can be obtained as a non-aqueous electrolyte secondary battery.

In the nonaqueous electrolyte secondary battery 1 according to the present invention, the mixing ratio of each organic solvent in the solvent of the nonaqueous electrolyte 50 is {PC: EC: DME} = 0.5 to 1.5: 0 in volume ratio. It is preferable to set in the range of .5-1.5: 1-3. Further, the mixing ratio in the solvent is more preferably in the range of 0.8 to 1.2: 0.8 to 1.2: 1.5 to 2.5 by volume ratio, and generally {PC: EC: Most preferably, DME} = {1: 1: 2}.
When the blending ratio of the organic solvent is in the above range, the effect of improving the low temperature characteristics can be obtained remarkably without impairing the capacity retention rate at high temperature or normal temperature as described above.

More specifically, if the blending ratio of propylene carbonate (PC), which is a cyclic carbonate solvent, is equal to or higher than the lower limit of the above range, the low temperature characteristics are improved by using a mixture of PC having a melting point lower than EC and EC. The effect which can be obtained is acquired notably.
On the other hand, since the concentration of the supporting salt cannot be increased because PC has a lower dielectric constant than that of EC, it is difficult to obtain a large discharge capacity if the content is too large. It is preferable to limit to the upper limit of the above range.

In addition, in the organic solvent, if the blending ratio of ethylene carbonate (EC), which is a cyclic carbonate solvent, is equal to or higher than the lower limit of the above range, the dielectric constant of the nonaqueous electrolyte 50 and the solubility of the supporting salt are increased, and the nonaqueous electrolyte A large discharge capacity as a secondary battery can be obtained.
On the other hand, EC is poor in electrical conductivity due to its high viscosity, and since its melting point is high, if the content is too high, the low temperature characteristics may be lowered, so the blending ratio is below the upper limit of the above range. It is preferable to limit to.
Furthermore, by setting the blending ratio of EC in the organic solvent within the above range, it is possible to suppress an increase in internal resistance under a low temperature environment.

Further, in the organic solvent, if the blending ratio of the chain ether solvent dimethoxyethane (DME) is not less than the lower limit of the above range, a low melting point of DME is contained in the organic solvent in a predetermined amount or more. An effect of improving the characteristics can be obtained. In addition, since DME has a low viscosity, electrical conductivity is improved, and a large discharge capacity can be obtained by solvating with Li ions.
On the other hand, since DME has a low dielectric constant, the concentration of the supporting salt cannot be increased, and if the content is too large, it may be difficult to obtain a large discharge capacity. It is preferable to limit to.
Furthermore, by setting the mixing ratio of DME in the organic solvent in the above range, it is possible to suppress a voltage drop at the initial stage of discharge.

  In the non-aqueous electrolyte secondary battery 1 according to the present invention, the non-aqueous electrolyte 50 contains LiFSI as a supporting salt after the above-described concavo-convex structure of the positive electrode current collector 14 and the negative electrode current collector 24 are provided. Furthermore, when a configuration containing PC, EC, and DME in an appropriate range as the organic solvent is employed, the internal resistance at the end of discharge of the entire battery is significantly reduced. Thereby, even in the small non-aqueous electrolyte secondary battery 1 that can supply a large current pulse in a region of about 1 mA to several mA, it is possible to ensure sufficient discharge characteristics.

  Furthermore, in the present invention, when the organic solvent used for the non-aqueous electrolyte 50 has the above composition, the viscosity of the non-aqueous electrolyte is prevented from increasing particularly in a low temperature environment of −30 to −40 ° C. It is possible to suppress the hindrance of the movement. Thereby, in the small nonaqueous electrolyte secondary battery 1 that can maintain a sufficient discharge capacity in a wide temperature range including a low temperature environment and can supply a large current pulse in a region of about 1 mA to several mA, Sufficient discharge characteristics can be ensured.

[Positive electrode]
The positive electrode 10 used for the nonaqueous electrolyte secondary battery 1 of the present invention contains, for example, a positive electrode active material made of lithium manganese oxide and graphite as a conductive auxiliary agent. Moreover, as the positive electrode 10, in addition to the positive electrode active material and the conductive additive (graphite), a mixture of polyacrylic acid or the like as a binder (binder) can be used.

The positive electrode active material contained in the positive electrode 10 is not particularly limited. For example, in addition to lithium manganese oxides such as LiMn ₂ O ₄ and Li ₄ Mn ₅ O ₁₂ having a spinel crystal structure, MoO ₃ (trioxide) Molybdenum) and the like.
Among the above lithium manganese oxides, in particular, a part of Mn, such as Li _{1 + x} Co _y Mn _2- xyO ₄ (0 ≦ x ≦ 0.33, 0 <y ≦ 0.2) Is preferably substituted with Co. As described above, by adding a transition metal element such as Co or Ni to lithium manganese oxide and using a positive electrode active material partially substituted with the transition metal element, an effect of further improving discharge characteristics can be obtained. .

In the present embodiment, by using a positive electrode active material made of lithium manganese oxide having the above composition for the positive electrode 10, the discharge characteristics are improved particularly in a low temperature environment, and the effect of obtaining a sufficient discharge capacity in a wide temperature range is remarkable. Further, sufficient discharge characteristics can be obtained even in the small non-aqueous electrolyte secondary battery 1 that can supply a large current pulse in the region of about 1 mA to several mA.
In the present embodiment, the positive electrode active material may contain not only one of the above lithium manganese oxides but also a plurality of them.

Moreover, when using the granular positive electrode active material which consists of the said material, the particle diameter (D50) is not specifically limited, For example, 0.1-100 micrometers is preferable and 1-10 micrometers is more preferable.
When the particle diameter (D50) of the positive electrode active material is less than the lower limit value of the above preferred range, the nonaqueous electrolyte secondary battery becomes difficult to handle because of increased reactivity when exposed to high temperatures, and the upper limit value. If it exceeds, the discharge rate may decrease.
In the present invention, the “particle diameter of positive electrode active material (D50)” is a particle diameter measured using a laser diffraction method and means a median diameter.

  The content of the positive electrode active material in the positive electrode 10 is determined in consideration of the discharge capacity required for the nonaqueous electrolyte secondary battery 1, and is preferably 50 to 95% by mass. If the content of the positive electrode active material is not less than the lower limit value of the above preferred range, sufficient discharge capacity can be easily obtained, and if it is not more than the preferred upper limit value, the positive electrode 10 can be easily molded.

  Although it does not specifically limit as a conductive support agent contained in the positive electrode 10 (Hereinafter, the conductive support agent contained in the positive electrode 10 may be called "positive electrode conductive support agent.") It contains at least one of graphite or carbon black. Is preferred.

Although it does not specifically limit as graphite used for a positive electrode conductive support agent, For example, artificial graphite is mentioned.
Further, the graphite used for the positive electrode conductive auxiliary agent preferably has a specific surface area of 240 m ² / g or more. Thus, in particular, the diffusion resistance in the positive electrode 10 is reduced by using graphite having a large specific surface area.
Moreover, as a particle diameter (D50) of the graphite used for a positive electrode conductive support agent, what is 10 micrometers or less is preferable. Thus, in particular, by using graphite having the above specific surface area and particle diameter as the positive electrode conductive auxiliary agent, it is possible to improve the conductivity and greatly improve the discharge characteristics.

  In the present invention, since the positive electrode 10 contains graphite as a conductive additive together with the positive electrode active material, the diffusion resistance in the positive electrode 10 is reduced by the action of graphite having a relatively large specific surface area. Thereby, since internal resistance is reduced, sufficient discharge characteristics can be ensured even in a small nonaqueous electrolyte secondary battery 1 capable of supplying a large current pulse in a region of about 1 mA to several mA.

  In addition, the content in the case where graphite is mixed in the positive electrode 10 is not particularly limited, but the diffusion resistance in the positive electrode 10 is effectively reduced to obtain sufficient conductivity, and the positive electrode 10 is formed into a pellet. From the viewpoint of improving moldability during molding, the content is preferably 4% by mass or more, and more preferably 10% by mass or more. On the other hand, the upper limit of the graphite content in the positive electrode 10 is preferably 40% by mass or less, and more preferably 25% by mass or less, from the viewpoint that the discharge capacity can be sufficiently obtained.

  In the present invention, carbon black may be contained as the positive electrode conductive additive in place of the above graphite or together with the above graphite. Examples of such carbon black include carbonaceous materials such as furnace black, ketjen black, and acetylene black. As the carbon black used as the positive electrode conductive additive, one of the above may be used alone, or two or more may be used in combination.

  In the present invention, when the positive electrode 10 contains carbon black in addition to graphite, the effect of reducing the diffusion resistance in the positive electrode 10 as described above can be obtained more remarkably. In a small non-aqueous electrolyte secondary battery having a relatively large discharge current, which is higher than that of the battery, further excellent discharge characteristics can be obtained.

  In addition, even when it contains carbon black instead of graphite as a positive electrode conductive support agent in the positive electrode 10, it is preferable to make the content into the range similar to graphite. Further, when the above carbon black is contained in addition to graphite as the positive electrode conductive additive in the positive electrode 10, the total content thereof may be within the above range as in the case of containing graphite alone. preferable.

The positive electrode 10 may contain a binder (hereinafter, the binder used for the positive electrode 10 may be referred to as a “positive electrode binder”).
As the positive electrode binder, conventionally known materials can be used. For example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), polyacrylic acid (PA), carboxymethyl cellulose (CMC) ), Polyvinyl alcohol (PVA), and the like. Among them, polyacrylic acid is preferable, and cross-linked polyacrylic acid is more preferable.
As the positive electrode binder, one of the above may be used alone, or two or more may be used in combination.
In addition, when using polyacrylic acid for a positive electrode binder, it is preferable to adjust polyacrylic acid to pH 3-10 previously. For adjusting the pH in this case, for example, an alkali metal hydroxide such as lithium hydroxide or an alkaline earth metal hydroxide such as magnesium hydroxide can be used.
Content of the positive electrode binder in the positive electrode 10 can be 1-20 mass%, for example.

The size of the positive electrode 10 is determined according to the size of the nonaqueous electrolyte secondary battery 1.
Further, the thickness of the positive electrode 10 is also determined according to the size of the non-aqueous electrolyte secondary battery 1, and if the non-aqueous electrolyte secondary battery 1 is a coin type for backup for various electronic devices, for example, , About 300 to 1000 μm.

The positive electrode 10 can be manufactured by a conventionally known manufacturing method.
For example, as a manufacturing method of the positive electrode 10, in addition to the positive electrode active material and the positive electrode conductive additive, a positive electrode binder is mixed as necessary to form a positive electrode mixture, and the positive electrode mixture is pressure-molded into an arbitrary shape. Is mentioned.
The pressure at the time of the above-described pressure molding is determined in consideration of the type of the positive electrode conductive additive, and can be set to, for example, 0.2 to 5 ton / cm ² .

  The positive electrode 10 provided in the nonaqueous electrolyte secondary battery 1 of the present embodiment is electrically connected to the positive electrode current collector 14 having a concavo-convex structure formed on the inner bottom surface of the positive electrode can 12. As described above, since the positive electrode 10 is connected to the positive electrode current collector 14 having the concavo-convex structure, the contact area between the positive electrode 10 and the positive electrode current collector 14 is increased, and the contact resistance is reduced. Accordingly, an effect of reducing the internal resistance of the battery is obtained.

  Furthermore, in the non-aqueous electrolyte secondary battery 1 of the present invention, it is preferable that at least a part of the positive electrode current collector 14 is embedded in the positive electrode 10 as shown in FIG. Here, as described in this embodiment, “at least a part of the positive electrode current collector 14 is embedded in the positive electrode 10” means, for example, that the positive electrode 10 and the positive electrode current collector 14 (positive electrode can 12). A state in which the flat portion 14a portion of the positive electrode current collector portion 14 enters and is embedded in the pellets forming the positive electrode 10 by pressure contact.

  Thus, when the configuration in which at least part of the positive electrode current collector 14 is embedded in the positive electrode 10 is adopted, the contact area between the positive electrode 10 and the positive electrode current collector 14 is greatly increased. Since the contact resistance is significantly reduced, the effect of reducing the internal resistance of the battery can be obtained more significantly.

  Moreover, in the nonaqueous electrolyte secondary battery 1 of the present invention, the positive electrode 10 is electrically connected to the positive electrode current collector 14 having a concavo-convex structure, and the negative electrode 20 is a negative electrode current collector having a concavo-convex structure as will be described later. When the configuration electrically connected to 24 is adopted, the contact area between each electrode and each current collector increases, so that the contact resistance can be further reduced and the internal resistance is also significantly reduced. Therefore, particularly when the present invention is applied to a small non-aqueous electrolyte secondary battery capable of supplying a large current pulse in the region of about 1 mA to several mA, sufficient discharge characteristics can be ensured.

[Negative electrode]
The negative electrode 20 used in the present embodiment is not particularly limited. For example, a negative electrode active material containing SiO _x (0 ≦ X <2) in which at least a part of the surface is coated with carbon can be used. . Further, as the negative electrode 20, in addition to the above negative electrode active material, an appropriate binder, a mixture of polyacrylic acid as a binder and graphite or the like as a conductive auxiliary agent can be used.

The negative electrode active material used for the negative electrode 20 is made of SiO or SiO ₂ , that is, a silicon oxide represented by the above-mentioned SiO _X (0 ≦ X <2). By using the silicon oxide having the above composition as the negative electrode active material, the nonaqueous electrolyte secondary battery 1 can be used at a high voltage, and the cycle characteristics are improved.
Further, the negative electrode 20 has, as a negative electrode active material, in addition to the above-mentioned SiO _X (0 ≦ X <2), further, an alloy-based negative electrode such as carbon and Li—Al, at least one of Si, WO ₂ and WO ₃ May be contained.

By using the above material as the negative electrode active material for the negative electrode 20, the reaction between the non-aqueous electrolyte 50 and the negative electrode 20 in the charge / discharge cycle is suppressed, and a decrease in capacity can be prevented. The negative electrode active material composed of SiO X coated with carbon ₍₀ ≦ X <2), the particles by charge and discharge even if the repeated swelling and contraction, decrease in conductivity is suppressed. Thereby, since the electroconductivity of the negative electrode 20 is maintained even when charging / discharging is repeated, the effect of improving the cycle characteristics is obtained.

Furthermore, the negative electrode 20 employs a configuration including a negative electrode active material made of SiO _X (0 ≦ X <2) whose surface is at least partially coated with carbon (C), thereby improving the conductivity of the negative electrode 20. In addition, an increase in internal resistance in a low temperature environment is suppressed. Thereby, the voltage drop in the initial stage of discharge is suppressed, and the discharge characteristics can be further stabilized. The negative electrode active material only needs to have at least a part of the surface of particles made of SiO _X (0 ≦ X <2) covered with carbon. Is preferable from the standpoint that

In the present invention, when the nonaqueous electrolyte 50 has the above composition and the negative electrode 20 including a negative electrode active material made of SiO _X (0 ≦ X <2) whose surface is coated with carbon is employed, In particular, since the discharge characteristics under a low temperature environment of −30 to −40 ° C. can be improved, the nonaqueous electrolyte secondary battery 1 capable of obtaining excellent charge / discharge characteristics in a wide temperature range can be realized.

The method of coating the particle surface of SiO _X (0 ≦ X <2), which is a negative electrode active material, with carbon is not particularly limited. For example, physical vapor deposition using a gas containing an organic substance such as methane or acetylene ( PVD) and chemical vapor deposition (CVD).

  When using the said material as a negative electrode active material, the particle diameter (D50) is not specifically limited, For example, 0.1-30 micrometers is preferable and 1-10 micrometers is more preferable. When the particle diameter (D50) of the negative electrode active material is less than the lower limit of the above preferred range, for example, the non-aqueous electrolyte secondary battery becomes difficult to handle because of increased reactivity when exposed to high temperatures, If the upper limit is exceeded, the discharge rate may be reduced.

In the present embodiment, the negative electrode active material used for the negative electrode 20 is described as an example in which the particle surface of SiO _X (0 ≦ X <2) is coated with carbon as described above. However, the present invention is not limited to this, and it is also possible to use SiO _X (0 ≦ X <2) particles not coated with carbon.

In the present embodiment, the negative electrode active material in the negative electrode 20 includes lithium (Li) and SiO _X (0 ≦ X <2), and the molar ratio (Li / SiO _X ) is 3.7 to More preferably, it is in the range of 4.9. Thus, the negative electrode active material is composed of lithium (Li) and SiO 2 _X, and by making these molar ratios within the above range, an effect of preventing charging abnormality and the like can be obtained. Moreover, even when the nonaqueous electrolyte secondary battery 1 is used or stored for a long period of time in a high temperature environment, the discharge capacity does not decrease and the effect of improving the storage characteristics can be obtained.

When the above molar ratio (Li / SiO _x ) is less than 3.7, the amount of Li is too small. Therefore, after use or storage for a long time in a high temperature environment, Li becomes insufficient and the discharge capacity decreases.
On the other hand, if the above molar ratio (Li / SiO _x ) exceeds 4.9, there is a possibility that charging abnormality may occur because Li is too much. Further, since the metal Li remains without being incorporated into the SiO _X, the discharge capacity resistance rises may be reduced.

Furthermore, in the present embodiment, the molar ratio (Li / SiO _x ) within the above range is selected and set in accordance with the type of the positive electrode active material contained in the positive electrode 10 described above. Is more preferable. For example, when lithium titanate is used as the positive electrode active material, the molar ratio (Li / SiO _X ) in the negative electrode active material is more preferably in the range of 4.0 to 4.7. Moreover, when lithium manganese oxide is used for the positive electrode active material, the molar ratio (Li / SiO _x ) in the negative electrode active material is more preferably in the range of 3.9 to 4.9. Thus, by setting the molar ratio (Li / SiO _X ) of the negative electrode active material in a range corresponding to the type of the positive electrode active material, it is possible to suppress an increase in initial resistance as described above, thereby preventing charging abnormality and the like. The effect that can be prevented and the discharge capacity does not decrease even after long-term use or storage in a high-temperature environment, and the effect of improving the storage characteristics can be obtained more remarkably.

The content of the negative electrode active material in the negative electrode 20 is determined in consideration of the discharge capacity and the like required for the non-aqueous electrolyte secondary battery 1, and is preferably 50% by mass or more, and more preferably 60 to 80% by mass. .
In the negative electrode 20, if the content of the negative electrode active material made of the above material is not less than the lower limit value of the above preferable range, sufficient discharge capacity can be easily obtained, and if the content is not more than the upper limit value, the forming process of the negative electrode 20 can be performed. Becomes easier.

  The negative electrode 20 may contain a conductive auxiliary (hereinafter, the conductive auxiliary used for the negative electrode 20 may be referred to as a “negative electrode conductive auxiliary”). As a negative electrode conductive support agent, it is preferable to contain at least one of graphite or carbon black like the positive electrode conductive support agent. When the negative electrode 20 contains either graphite or carbon black, the diffusion resistance in the negative electrode 20 can be more effectively reduced as in the case of the positive electrode 10.

  When the negative electrode 20 contains graphite as a conductive additive, the content thereof is preferably 20% by mass or more in the negative electrode 20. As described above, when the negative electrode 20 contains graphite in the above range, similarly to the positive electrode 10, diffusion resistance in the negative electrode 20 is reduced. Therefore, as described above, in the small non-aqueous electrolyte secondary battery 1 having a large discharge current, which has a higher discharge current than the conventional one, more excellent discharge characteristics can be obtained.

Although it does not specifically limit as graphite used for a negative electrode conductive support agent, Like the positive electrode conductive support agent, for example, what has a specific surface area of 240 m < ² > / g or more is preferable. Also in the negative electrode 20, as in the case of the positive electrode 10, together with the negative electrode active material, graphite is contained at 20% by mass or more as a conductive additive, so that the diffusion in the negative electrode 20 is caused by the action of graphite having a large specific surface area. Resistance is reduced. As a result, the internal resistance is reduced. In particular, in a small non-aqueous electrolyte secondary battery that can supply a large current pulse in a region of about 1 mA to several mA and has a higher discharge current than in the past, sufficient discharge is possible. The effect which can ensure a characteristic is acquired.

  The graphite content in the negative electrode 20 is preferably 20% by mass or more from the viewpoint of obtaining sufficient conductivity and improving the formability when the positive electrode 10 is formed into a pellet. From the viewpoint of sufficiently obtaining the discharge capacity, it is preferably 40% by mass or less.

  As in the case of the positive electrode 10, the negative electrode 20 may also contain carbon black as a negative electrode conductive additive instead of the above graphite or together with the above graphite. As such carbon black, the thing similar to what is contained in the positive electrode 10 as a positive electrode conductive support agent can be used.

The negative electrode 20 contains carbon black in addition to graphite, so that the effect of reducing the diffusion resistance in the negative electrode 20 is more remarkably obtained. When the above carbon black is contained in addition to graphite as the positive electrode conductive additive in the negative electrode 20, it is preferable that the total content thereof is within the above range as in the case of containing graphite alone.
Moreover, even when it contains carbon black instead of graphite as a positive electrode conductive support agent in the negative electrode 20, it is preferable to make the content into the range similar to graphite.

  In the present invention, the positive electrode 10 contains at least one of graphite and carbon black as a positive electrode conductive auxiliary agent in an appropriate amount, and further, the negative electrode 20 also contains the above negative electrode conductive auxiliary agent in an appropriate amount. The effect of reducing the diffusion resistance in the electrode can be obtained more remarkably. This makes it possible to obtain more excellent discharge characteristics, particularly in a small non-aqueous electrolyte secondary battery that can supply a large current pulse in the region of about 1 mA to several mA and that has an increased discharge current compared to the prior art. Become.

The negative electrode 20 may contain a binder (hereinafter, the binder used for the negative electrode 20 may be referred to as a “negative electrode binder”).
Examples of the negative electrode binder include polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), polyacrylic acid (PA), carboxymethyl cellulose (CMC), polyimide (PI), and polyamideimide (PAI). Acrylic acid is preferred, and cross-linked polyacrylic acid is more preferred.
As the negative electrode binder, one of the above may be used alone, or two or more may be used in combination. In addition, when using polyacrylic acid for a negative electrode binder, it is preferable to adjust polyacrylic acid to pH 3-10 previously. For adjusting the pH in this case, for example, an alkali metal hydroxide such as lithium hydroxide or an alkaline earth metal hydroxide such as magnesium hydroxide can be used.
Content of the negative electrode binder in the negative electrode 20 shall be 1-20 mass%, for example.

The size and thickness of the negative electrode 20 can be the same as the size and thickness of the positive electrode 10.
Further, the nonaqueous electrolyte secondary battery 1 shown in FIG. 1 employs a configuration in which a lithium foil 60 is provided on the surface of the negative electrode 20, that is, between the negative electrode 20 and a separator 30 described later.

As a method for producing the negative electrode 20, for example, the above-described material is used as a negative electrode active material, and a negative electrode conductive additive such as graphite and / or a negative electrode binder is mixed as necessary to prepare a negative electrode mixture, A method of pressure-molding this negative electrode mixture into an arbitrary shape can be employed.
In this case, the pressure at the time of pressure molding is determined in consideration of the type of the negative electrode conductive additive, and can be set to, for example, 0.2 to 5 ton / cm ² .

  Further, as shown in FIG. 1, also in the negative electrode 20, as in the case of the positive electrode 10, at least a part of the negative electrode current collector 24, specifically, the flat portion 24 a of the negative electrode current collector 24 is formed on the negative electrode 20. The part is preferably embedded. As described above, since at least a part of the negative electrode current collector 24 is embedded in the negative electrode 20, the contact area between the negative electrode 20 and the negative electrode current collector 24 is greatly increased, and the contact resistance is significantly reduced. Thus, the effect of significantly reducing the internal resistance can be expected.

  In the present invention, as described above, a configuration in which both of the positive electrode 10 and the negative electrode 20 are electrically connected to the current collecting portions (the positive current collecting portion 14 and the negative current collecting portion 24) having an uneven structure is adopted. In this case, the contact area between each electrode and each current collector is increased, the contact resistance is reduced, and the internal resistance is significantly reduced. Therefore, particularly when the present invention is applied to a small non-aqueous electrolyte secondary battery capable of supplying a large current pulse in the region of about 1 mA to several mA, sufficient discharge characteristics can be ensured.

[Separator]
The separator 30 is interposed between the positive electrode 10 and the negative electrode 20, and an insulating film having high ion permeability, excellent heat resistance, and a predetermined mechanical strength is used.
As the separator 30, a separator that is conventionally used for a separator of a nonaqueous electrolyte secondary battery and that is made of a material that satisfies the above characteristics can be applied without any limitation. For example, alkali glass, borosilicate glass, quartz glass, lead glass, etc. Nonwoven fabric made of glass, polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polyethylene terephthalate (PET), polyamideimide (PAI), polyamide, polyimide (PI), aramid, cellulose, fluororesin, ceramics, etc. Examples thereof include fibers. Among the above, it is more preferable to use a nonwoven fabric made of glass fiber as the separator 30. Glass fiber is excellent in mechanical strength and has a large ion permeability, so that the internal resistance can be reduced and the discharge capacity can be improved.
The thickness of the separator 30 is determined in consideration of the size of the nonaqueous electrolyte secondary battery 1, the material of the separator 30, and the like, and can be, for example, about 5 to 300 μm.

<Method for producing non-aqueous electrolyte secondary battery>
Next, a method for manufacturing the nonaqueous electrolyte secondary battery 1 of the present embodiment as shown in FIG. 1 will be described below.
The method for producing a nonaqueous electrolyte secondary battery according to the present invention forms a bottomed cylindrical positive electrode can 12 and a covered cylindrical negative electrode can 22 each having an opening 12a by processing a metal plate material. A storage container forming step for obtaining a storage container 2 composed of a can 12 and a negative electrode can 22, a positive electrode 10 including a positive electrode active material, a negative electrode 20 including a negative electrode active material, a positive electrode 10 and a negative electrode 20 in the storage container 2. Between the separator 30 and the battery assembly step for accommodating the nonaqueous electrolyte 50 containing at least a supporting salt and an organic solvent.

  In the manufacturing method according to the present invention, the container forming step selectively removes at least a part of the inner bottom surface of the positive electrode can 12 and the inner lid surface of the negative electrode can 22 by an etching process, so that the flat portion 14a and The method includes forming a concavo-convex structure of the positive electrode current collector portion 14 including the concave portion 14 b and forming a concavo-convex structure of the negative electrode current collector portion 24 including the flat portion 24 a and the concave portion 24 b.

  In addition, in the manufacturing method of the nonaqueous electrolyte secondary battery 1 according to the present invention, the container forming step which is a method of forming the positive electrode current collector 14 and the negative electrode current collector 24 having the concavo-convex structure as described above is provided. Except for the points included, substantially the same conditions and procedures as in the past can be employed.

[Storage container forming process]
In the storage container forming step, first, the above-described metal plate material made of stainless steel or a clad material made of a plurality of metals is used to press-mold the plate material, so that the storage container as shown in FIG. 2, a molded product of a bottomed cylindrical positive electrode can 12 having an opening 12 a and a covered cylindrical negative electrode can 22 is obtained.

  Next, by etching the inner bottom surface of the positive electrode can 12 and the inner lid surface of the negative electrode can 22, the positive electrode current collector 14 having a concavo-convex structure including a flat portion 14 a and a concave portion 14 b is formed on the positive electrode can 12. In addition, the negative electrode current collector 24 having a concavo-convex structure including a flat portion 24 a and a concave portion 24 b is formed in the negative electrode can 22.

  Specifically, first, masking is performed on regions where the uneven structure is to be formed by etching on the inner bottom surface of the positive electrode can 12 and the inner lid surface of the negative electrode can 22. At this time, a masking pattern is formed by applying a resist to the inner bottom surface and the inner lid surface by using, for example, a photolithography method according to a desired planar shape of the concavo-convex structure.

  Next, an etching process is performed on the inner bottom surface of the positive electrode can 12 and the inner lid surface of the negative electrode can 22 on which the masking pattern is formed. The etching method at this time is not particularly limited, and general wet etching or dry etching can be employed. Furthermore, a sandblasting method can also be employed. On the other hand, from the viewpoint of workability with respect to the metal material, it is preferable to employ a wet etching process using an etchant for etching the inner surfaces of the positive electrode can 12 and the negative electrode can 22.

  Although it does not specifically limit as etching liquid used for wet etching, It can select, considering the material of the metal plate material used for the positive electrode can 12 and the negative electrode can 22, The positive electrode can 12 and the etching liquid illustrated below and Etching is performed by immersing the negative electrode can 22.

  Here, for example, when a stainless steel plate is used for the positive electrode can 12 and the negative electrode can 22 and the stainless steel is etched, a ferric chloride aqueous solution or a cupric chloride aqueous solution having strong oxidizing power is used as an etchant. It is also preferable to use sulfuric acid or the like which is a strong acid.

  Further, when the positive electrode can 12 and the negative electrode can 22 are made of a multi-layer metal plate made of a clad material having a stainless steel material on the outer surface side and an aluminum material on the inner surface side, the aluminum is etched. . In this case, as the etching solution, for example, hydrochloric acid, phosphoric acid, sulfuric acid, acetic acid, oxalic acid, ascorbic acid, benzoic acid, butyric acid, citric acid, formic acid, lactic acid, isobutyric acid, malic acid, propionic acid, tartaric acid and the like Any of an aqueous solution, a sodium hydroxide aqueous solution, a ferric chloride solution, a sodium phosphate aqueous solution, dilute nitric acid, and the like can be used. Further, in these etching solutions, halogen ions can be contained at a predetermined concentration as necessary for the purpose of removing the oxide film present on the surface of the aluminum material.

On the other hand, when the positive electrode can 12 and the negative electrode can 22 are made of a metal plate made of a clad material having a stainless steel material on the outer surface side and a nickel material on the inner surface side, nickel is etched. In this case, for example, a ferric chloride aqueous solution or a cupric chloride aqueous solution can be used.
Further, when the positive electrode can 12 and the negative electrode can 22 are made of a metal plate made of a clad material having a stainless steel material on the outer surface side and a copper material on the inner surface side, the copper is etched. In this case, for example, in addition to sulfuric acid or oxalic acid containing a predetermined amount of halogen ion, hydrogen peroxide or nitric acid, a ferric chloride solution or ammonium persulfate contains a cupric chloride solution. Either nitric acid or nitric acid can be used.

  In the method described in this embodiment, the inner bottom surface of the positive electrode can 12 and the inner lid surface of the negative electrode can 22 are etched to remove at least a part of these to form the recesses 14b and 24b. The etching processing time is not particularly limited, and can be set in consideration of the shape of each current collector formed in plan view, the depth of the recess, and the like. The same applies to the temperature of the etching solution during the etching process, and it may be set as appropriate.

  Next, the masking pattern remaining on the inner bottom surface of the positive electrode can 12 and the negative electrode can 22 is removed by a conventionally known method, washed with water or the like, and then dried. Thereby, the positive electrode can 12 and the negative electrode can 22 in which the current collecting part of the uneven structure is formed on the inner bottom surface or the inner lid surface are obtained.

  In addition, surface treatment such as Ni plating is performed on the outer surfaces of the positive electrode can 12 and the negative electrode can 22 as necessary.

  In the present embodiment, uneven processing is facilitated by etching the inner surface side on which the metal material having low hardness in the clad material is disposed. Therefore, the planar view shapes of the positive electrode current collector 14 and the negative electrode current collector 24 having the concavo-convex structure as described above can be formed in a finer pattern.

[Battery assembly process]
Next, in the battery assembly process, the positive electrode 10, the negative electrode 20, the positive electrode 10, and the negative electrode 20 are placed in the storage container 2 composed of the positive electrode can 12 and the negative electrode can 22 obtained in the storage container forming process. 1 and a non-aqueous electrolyte 50 containing at least a supporting salt and an organic solvent, and assembling the non-aqueous electrolyte secondary battery 1 (cross section of the non-aqueous electrolyte secondary battery 1 in FIG. 1) (See diagram).

  Specifically, first, the positive electrode 10, the negative electrode 20, the separator 30, the gasket 40, the nonaqueous electrolyte 50, and the lithium foil 60 made of various materials as described above are prepared.

Next, the positive electrode 10 made of pellets containing a positive electrode active material is used on the positive electrode current collector 14 in the positive electrode can 12 obtained in the storage container forming step, for example, using a conductive resin adhesive containing carbon. Assemble and assemble the positive electrode unit. Specifically, after placing the positive electrode 10 on the positive electrode current collector 14 in the positive electrode can 12 coated with the conductive resin adhesive, the positive electrode current collector 14 is pressed into contact with the positive electrode current collector 14, thereby forming a positive electrode on the uneven structure of the positive electrode current collector 14. 10 is integrated so as to bite into a positive electrode unit.
And after drying this positive electrode unit under reduced pressure heating under high temperature conditions, a sealing agent is apply | coated to the inner surface of the opening part of a positive electrode can.

Further, the negative electrode unit is assembled by the following procedure.
That is, first, on the negative electrode current collector 24 of the negative electrode can 22 obtained in the storage container forming step, the negative electrode 20 made of pellets containing a negative electrode active material is used with a conductive resin adhesive containing carbon as a conductive filler. By bonding them together, they are integrated. Specifically, as in the case of the positive electrode unit, after the negative electrode 20 is placed on the negative electrode current collector 24 of the negative electrode can 22 coated with the conductive resin adhesive, the negative electrode current collector is pressed together. The negative electrode 20 is integrated so as to bite into the concavo-convex structure of the portion 24 to form a negative electrode unit.
Next, after this negative electrode unit is dried under reduced pressure under high temperature conditions, a lithium foil 60 is pressure-bonded onto the negative electrode 20 to form a lithium-negative electrode laminated electrode, and dried under reduced pressure under high temperature conditions.
Next, the separator 30 is laminated on the lithium foil 60.
And the negative electrode unit is produced by attaching the gasket 40 to the opening part of the negative electrode can 22. At this time, the tip 22 a of the negative electrode can 22 is attached so as to enter the annular groove 41 formed in the gasket 40.

  Next, the positive electrode can 12 and the negative electrode can 22 are filled with the nonaqueous electrolyte 50 so that the total amount per battery is 40 μL.

Next, the negative electrode unit obtained by the above procedure is caulked to the positive electrode unit so that the separator 30 contacts the positive electrode 10.
Specifically, first, the negative electrode unit in which each member is accommodated in the negative electrode can 22 is inserted into the opening 12 a of the positive electrode can 12.
Next, the space covered with the positive electrode can 12 and the negative electrode can 22 is sealed while the gasket 40 is compressed by caulking and fitting the periphery of the opening 12a of the positive electrode can 12 to the inside, that is, the negative electrode can 22 side. To do.
Through the above procedure, the non-aqueous electrolyte secondary battery 1 of the present embodiment that is small and coin-shaped (button type) as illustrated in FIG. 1 is obtained.

  According to the manufacturing method of the present invention, in the storage container forming step, the inner bottom surface of the positive electrode can 12 and the inner lid surface of the negative electrode can 22 are processed by an etching process so that the positive electrode current collector 14 and the negative electrode current collector having an uneven structure. By forming 24, each of these current collectors can be formed with a concavo-convex structure with a fine pattern without producing a work piece or the like. As a result, a small non-aqueous electrolyte secondary battery 1 having excellent discharge characteristics that can supply a large current pulse in a region of 1 mA or more in which the internal resistance of the battery is significantly reduced, and a work piece or the like remains in the battery. This makes it possible to manufacture with good yield.

  Moreover, since the manufacturing method according to the present invention is a method of forming each current collecting portion of the concavo-convex structure by etching the inner surface side of the positive electrode can 12 and the negative electrode can 22, the outer surface side of the positive electrode can 12 and the negative electrode can 22 Since the uneven shape does not occur, the nonaqueous electrolyte secondary battery 1 having excellent appearance characteristics can be manufactured.

<Other forms of non-aqueous electrolyte secondary battery>
The configuration described in this embodiment can be applied to an electrochemical cell such as a lithium ion capacitor.

<Applications of non-aqueous electrolyte secondary batteries>
As described above, the nonaqueous electrolyte secondary battery 1 of the present embodiment has excellent discharge characteristics particularly when a small coin cell or the like that can supply a large current pulse in the region of about 1 mA to several mA is configured. For example, in various small electronic devices such as a mobile phone, a PDA, a portable game machine, and a digital camera, it is suitably used as a backup power source for a semiconductor memory and a backup power source for a real-time clock function.

<Effect>
As described above, according to the nonaqueous electrolyte secondary battery 1 of the present invention, the positive electrode can 12 and the negative electrode can 22 are integrated on the inner bottom surface of the positive electrode can 12 and the inner lid surface of the negative electrode can 22. Since the positive electrode current collector 14 or the negative electrode current collector 24 having the concavo-convex structure is provided, the contact area between each electrode and each current collector increases, and the contact resistance between them increases.
As a result, the internal resistance can be significantly reduced, and particularly in a small non-aqueous electrolyte secondary battery capable of supplying a large current pulse in the region of about 1 mA to several mA, a state in which sufficient discharge current and voltage are maintained. Can discharge for a long time, and excellent discharge characteristics can be obtained. Moreover, since the current collecting part of the concavo-convex structure is provided on the inner surface side of the positive electrode can 12 and the negative electrode can 22 and the concavo-convex shape does not occur on the outer surface side, excellent appearance characteristics can be obtained, and a work piece or the like can be obtained during manufacturing. It does not occur and the yield is excellent.
Therefore, the non-aqueous electrolyte secondary battery 1 that can sufficiently satisfy the discharge characteristics required for various small electronic devices to which a small non-aqueous electrolyte secondary battery such as a coin type is applied and that can improve the device characteristics can be obtained with a high yield. It becomes possible to provide.

Further, according to the method for manufacturing the nonaqueous electrolyte secondary battery 1 according to the present invention, in the storage container forming step, the inner bottom surface of the positive electrode can 12 and the inner lid surface of the negative electrode can 22 are etched to form a positive and negative electrode assembly having a concavo-convex structure. Since the current collector 14 and the negative electrode current collector 24 are formed, the current collector can be formed with an uneven structure with a fine pattern without producing a work piece or the like.
Therefore, in particular, a small nonaqueous electrolyte secondary battery 1 having excellent discharge characteristics and capable of supplying a large current pulse in the region of 1 mA to several mA, in which the internal resistance of the battery is significantly reduced, is manufactured with high yield. It becomes possible.

  Next, an Example and a comparative example are shown and this invention is demonstrated further more concretely. The scope of the present invention is not limited by this embodiment, and the nonaqueous electrolyte secondary battery according to the present invention can be implemented with appropriate modifications within the scope not changing the gist of the present invention. is there.

<Preparation of nonaqueous electrolyte secondary battery>
[Example]
In the example, a coin-type non-aqueous electrolyte secondary battery, which is an electrochemical cell, in which a current collecting portion having a concavo-convex structure was formed on the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can, Discharge characteristics were measured (see nonaqueous electrolyte secondary battery 1 in FIG. 1).

That is, in the examples, first, a nonaqueous electrolyte having the following composition was _prepared , and Li _1.14 Co _0.06 Mn _1.80 O ₄ was used as the positive electrode active material, and the entire surface was carbon as the negative electrode active material. A nonaqueous electrolyte secondary battery was fabricated using the coated SiO. In this example, a coin-type (920 size) non-aqueous electrolyte secondary battery (lithium secondary battery) having an outer shape of 9.5 mm and a thickness of 2.0 mm in the cross-sectional view shown in FIG. 1 was produced.

(Production of storage container)
As the storage container, a positive electrode can and a negative electrode can having a current collecting part with an uneven structure on the inner surface side as shown in FIG. 1 were prepared.
First, as a material for the positive electrode can, a metal plate made of stainless steel (SUS329J4L: t = 0.20 mm) is prepared, and this is pressed to provide a bottomed opening having an opening as shown in FIG. A cylindrical positive electrode can was formed.
Further, as a material for the negative electrode can, a metal plate made of stainless steel (SUS304-BA: t = 0.20 mm) is prepared, and this is pressed to form a covered cylindrical negative electrode as shown in FIG. A can was molded.

Next, a mask pattern is formed on the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can by using a photolithography method, and wet etching treatment is performed. A positive electrode current collector and a negative electrode current collector having an uneven structure were formed.
Specifically, first, a masking pattern was formed by applying a resist material by a photolithography method to a region where the uneven structure on the inner surfaces of the positive electrode can and the negative electrode can was to be formed.
Next, an aqueous ferric chloride solution having a concentration of 35% by mass is used as the etching solution, the temperature of the etching solution is set to 65 ° C., and the positive electrode can and the negative electrode can are immersed for 10 minutes. Was etched.
Thereafter, the resist material was removed and washed.

  With such conditions and procedures, a positive electrode in which a concavo-convex structure having a plan view shape in which the concave portions are arranged in a lattice shape as shown in FIG. 2 is formed on the inner bottom surface and the inner lid surface. A can and a negative electrode can were obtained. The recesses formed at this time had a rectangular shape in plan view with a vertical and horizontal width W2 of 1.5 mm, and the flat portions had a lattice shape with a width W1 of 0.3 mm and extending in the vertical and horizontal directions. Moreover, the average depth D of a recessed part was 0.10 mm, and the ratio of the flat part with respect to the area of each current collection part was 28%.

(Nonaqueous electrolyte adjustment)
First, the organic solvent was adjusted according to the following blending ratio (volume%), and the non-aqueous electrolyte was adjusted by dissolving the supporting salt in this organic solvent. At this time, as an organic solvent, propylene carbonate (PC), ethylene carbonate (EC), and dimethoxyethane (DME) are mixed at a volume ratio of {PC: EC: DME} = {1: 1: 2}. Thus, the mixed solvent was adjusted. Next, a non-aqueous electrolyte was obtained by dissolving lithium bis (fluorosulfonyl) imide (LiFSI) as a supporting salt in the obtained mixed solvent so that the molar concentration was 1 mol / L.

(Production of battery)
As a positive electrode, first, commercially available lithium manganese oxide (Li _1.14 Co _0.06 Mn _1.80 O ₄ ), a particle size (D50) as a conductive auxiliary agent is 10.36 μm, and a specific surface area is 12. 5 m ² / g of graphite was mixed with polyacrylic acid as a binder (binder) and mixed in a ratio of lithium manganese oxide: graphite: polyacrylic acid = 95: 4: 1 (mass ratio). An agent was used.
Next, 98.6 mg of the obtained positive electrode mixture was pressure-molded with a pressure of ² ton / cm ² and pressure-molded into a disk-shaped pellet having a diameter of 8.9 mm.

Next, the obtained pellet (positive electrode) is bonded to the positive electrode current collector of the positive electrode can obtained by the above procedure using a conductive resin adhesive containing carbon, and these are integrated to obtain a positive electrode unit. It was. Thereafter, this positive electrode unit was dried by heating under reduced pressure in the atmosphere at 120 ° C. for 11 hours.
And the sealing agent was apply | coated to the inner surface of the opening part of the positive electrode can in a positive electrode unit.

Next, as a negative electrode, first, an SiO powder having carbon (C) formed on the entire surface was prepared, and this was used as a negative electrode active material. And, in this negative electrode active material, graphite having a particle size (D50) of 10.36 μm and a specific surface area of 12.5 m ² / g as a conductive auxiliary agent, and polyacrylic acid as a binder, 75: A negative electrode mixture was prepared by mixing at a ratio of 20: 5 (mass ratio).
Next, 15.1 mg of the obtained negative electrode mixture was pressure-molded with a pressure of ² ton / cm ² and pressure-molded into a disk-shaped pellet having a diameter of 6.7 mm.

Next, the obtained pellet (negative electrode) is bonded to the negative electrode current collector of the negative electrode can obtained by the above procedure using a conductive resin adhesive containing carbon as a conductive filler, and these are integrated. A negative electrode unit was obtained. Thereafter, this negative electrode unit was dried by heating under reduced pressure in the atmosphere at 160 ° C. for 11 hours.
Then, a lithium foil punched out to a diameter of 6.1 mm and a thickness of 0.38 mm was further pressure-bonded onto the pellet-shaped negative electrode to obtain a lithium-negative electrode laminated electrode.

  Next, after drying the nonwoven fabric made of glass fiber, it was punched into a disk shape having a diameter of 7 mm to obtain a separator. And this separator was mounted on the lithium foil crimped | bonded on the negative electrode, and the gasket made from a polypropylene was arrange | positioned in the opening part of the negative electrode can.

  Next, the positive electrode can and the negative electrode can were filled with 40 μL of the nonaqueous electrolyte prepared by the above procedure per battery in total.

  Next, the negative electrode unit was caulked to the positive electrode unit so that the separator contacted the positive electrode. And after sealing the positive electrode can and the negative electrode can by fitting the opening part of a positive electrode can, it left still at 25 degreeC for 7 days, and obtained a nonaqueous electrolyte secondary battery as shown in following Table 1 It was.

[Comparative example]
In the comparative example, a coin-type non-aqueous electrolyte was formed in the same manner as in the example, except that the concave and convex structure was not formed on the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can, and the planar current collector was used. A secondary battery was produced and its discharge characteristics were measured.

  That is, in the comparative example, the same procedure as in the above example, except that the etching process for the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can is omitted in the process of manufacturing the storage container shown in the example. Thus, a coin-type (920 size) non-aqueous electrolyte secondary battery as shown in Table 1 was produced.

<Evaluation method>
The internal resistance of the nonaqueous electrolyte secondary batteries of the above Examples and Comparative Examples obtained by the above procedure was measured at a value of AC 1 kHz by a R function using a commercially available LCR meter. At this time, the internal resistance of each non-aqueous electrolyte secondary battery was measured under temperature conditions in a normal temperature (25 ° C.) environment, and the results are shown in Table 1.

[Evaluation results]
First, as in the examples shown in Table 1, each of the electrodes is provided with an uneven structure composed of a flat portion and a concave portion on the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can. By adopting a configuration in which the current collectors are electrically connected to each other, the internal resistance is greatly reduced and the discharge characteristics are improved compared to the comparative example in which the current collectors are planar. I understand.

  Further, in the examples, the uneven structure provided on the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can is formed by the etching process, so that no work piece or the like occurs in the process, and the battery There were no problems such as a short circuit of the battery due to the remaining work piece in the inside, or a problem that the work piece was interposed between each electrode and each current collector and the fixing state became incomplete.

  From the results in the embodiments described above, as defined in claim 1 of the present invention, the current collector having a concavo-convex structure comprising a flat portion and a concave portion on the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can, respectively. By adopting a configuration in which a portion is provided and each electrode and each current collector are electrically connected, particularly, a large current pulse in a region of about 1 mA to several mA can be supplied. It is apparent that excellent discharge characteristics can be obtained when a small non-aqueous electrolyte secondary battery with an increased discharge current is constructed.

  As described above, the non-aqueous electrolyte secondary battery of the present invention can supply a large current pulse in the region of about 1 mA to several mA, and can be supplied with a small non-aqueous electrolyte secondary battery with an increased discharge current compared to the conventional case. In this case, excellent discharge characteristics can be obtained. Therefore, the non-aqueous electrolyte secondary battery of the present invention is a backup power source for a semiconductor memory or a real-time clock function in various small electronic devices such as a mobile phone, a PDA, a portable game machine, and a digital camera. Is preferably used.

DESCRIPTION OF SYMBOLS 1 ... Nonaqueous electrolyte secondary battery 2 ... Storage container 12 ... Positive electrode can 12a ... Opening part 14 ... Positive electrode current collection part (inner bottom face of positive electrode can),
14a ... flat part 14b ... concave part 22 ... negative electrode can 22a ... tip part 24 ... negative electrode current collector (inner cover surface of negative electrode can),
24a ... flat portion 24b ... concave portion 10 ... positive electrode 20 ... negative electrode 25 ... conductive adhesive 30 ... separator 40 ... gasket 41 ... annular groove 50 ... nonaqueous electrolyte 60 ... lithium foil

Claims (11)

A positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator disposed between the positive electrode and the negative electrode, and a nonaqueous electrolyte including at least a supporting salt and an organic solvent are made of metal. A non-aqueous electrolyte secondary battery housed in a container,
The storage container is a combination of a bottomed cylindrical positive electrode can having an opening and a covered cylindrical negative electrode can that forms a storage space between the positive electrode can and the inside of the positive electrode can. The bottom surface and the inner lid surface of the negative electrode can each be a current collector electrically connected to the positive electrode or the negative electrode,
The non-aqueous electrolyte secondary battery, wherein the current collector has a concavo-convex structure including a flat portion and a concave portion provided on the inner bottom surface and the inner lid surface.   2. The non-aqueous solution according to claim 1, wherein each of the current collectors provided in the positive electrode can and the negative electrode can has a ratio of the flat portion to an area of the current collector of 10 to 50%. Electrolyte secondary battery.   The non-aqueous electrolyte secondary according to claim 1, wherein at least a part of the current collector provided in the positive electrode can or the negative electrode can is embedded in the positive electrode and the negative electrode. battery.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the positive electrode can and the negative electrode can are made of stainless steel.   The said positive electrode can and negative electrode can consist of a clad material whose outer surface side is stainless steel and whose inner surface side is aluminum, nickel, or copper, The non-water as described in any one of Claims 1-3 characterized by the above-mentioned. Electrolyte secondary battery.   6. The non-collecting part according to claim 1, wherein a shape of the current collector in a plan view is a lattice shape or a ring shape including the flat portion and the concave portion. 7. Water electrolyte secondary battery.   The non-aqueous electrolyte secondary battery according to any one of claims 1 to 6, wherein the positive electrode and the negative electrode contain at least one of graphite and carbon black as a conductive additive.   The nonaqueous electrolyte secondary battery according to any one of claims 1 to 7, wherein the nonaqueous electrolyte includes at least lithium bis (fluorosulfonyl) imide (LiFSI) as a supporting salt.   The content of lithium bis (fluorosulfonyl) imide (LiFSI) contained as the supporting salt is in the range of 10 to 23% by mass with respect to the total amount of the non-aqueous electrolyte. Non-aqueous electrolyte secondary battery.   The non-aqueous electrolyte contains propylene carbonate (PC), ethylene carbonate (EC) and dimethoxyethane (DME) as the organic solvent in a volume ratio of {PC: EC: DME} = {0.5 to 1.5: It contains in the range of 0.5-1.5: 1-3}, The nonaqueous electrolyte secondary battery as described in any one of Claims 1-9 characterized by the above-mentioned. A storage container forming step of forming a bottomed cylindrical positive electrode can and a covered cylindrical negative electrode can having an opening by processing a metal plate, and obtaining a storage container composed of the positive electrode can and the negative electrode can; The non-aqueous electrolyte includes a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator disposed between the positive electrode and the negative electrode, and at least a supporting salt and an organic solvent in the storage container. A non-aqueous electrolyte secondary battery manufacturing method comprising:
In the storage container forming step, at least part of the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can is selectively removed by an etching process, whereby a current collecting portion having a concavo-convex structure including a flat portion and a concave portion The manufacturing method of the nonaqueous electrolyte secondary battery characterized by including the process which forms.

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