JP6697901B2 - Non-aqueous electrolyte secondary battery and manufacturing method thereof - Google Patents

Description

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

  A non-aqueous electrolyte secondary battery is, for example, a pair of polarizable electrodes composed of a positive electrode and a negative electrode, and a pair of polarizable electrodes composed of the positive electrode and the negative electrode, in a storage container that is sealed by 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 current collector electrically connected to the positive electrode and the negative electrode, a non-aqueous electrolyte that is impregnated into the positive electrode, the negative electrode and the separator, and includes a supporting salt and a non-aqueous solvent such as an organic solvent. Be prepared. Since such a non-aqueous electrolyte secondary battery has a high energy density and is lightweight, it is used, for example, in a power supply unit of an electronic device, a power storage unit that absorbs fluctuations in power generation of a power generator, and the like.

  Further, in the non-aqueous electrolyte secondary battery having the above configuration, for the connection between the positive electrode can and the positive electrode, and between the negative electrode can and the negative electrode, for example, by directly bonding using a conductive paste, or, In some cases, each electrode is adhered to 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, pressure welding, or the like.

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 suitable for a small non-aqueous electrolyte such as a coin type (button type). It is used as an electrolyte secondary battery. It is known that such a coin-type non-aqueous electrolyte secondary battery has a high voltage, a high energy density, excellent charge/discharge characteristics, and a long cycle life and high reliability. Therefore, such a coin-type non-aqueous electrolyte secondary battery has hitherto been used as a backup power source for a semiconductor memory or a real-time clock 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 backup power source for functions. Further, in recent years, the coin-type non-aqueous electrolyte secondary battery is expected to be applied to a main power source in a communication device such as Bluetooth (registered trademark) as a new application. On the other hand, in applications such as such a main power supply, discharge characteristics with a larger current are required as compared with conventional backup power supplies such as semiconductor memories and real-time clocks.

  Here, when the coin type (button type) as described above is applied to the main power source of a communication device or the like, it is necessary to take out a large current pulse of 1 mA or more, for example, and therefore 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, for the purpose 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), a metal net made of metal such as stainless steel is used. There has been proposed a secondary battery in which a negative electrode and a negative electrode can are connected (for example, see Patent Document 1).

  There is also proposed a battery in which the contact area between the electrode and the battery can is increased by forming the unevenness on the bottom (top) of the battery can (see, for example, Patent Document 2). ..

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

  However, like the secondary battery described in Patent Document 1, when a metal wire net is used as the current collector, a step for fixing the wire net used as the current collector to the battery can or the electrode pellet is performed. The increase causes problems such as a decrease in productivity and an increase in production cost. When a wire mesh is used as the current collector, a sheet-shaped wire mesh is punched out according to the shape of the electrode, so if the punched scraps (workpieces) remain inside the battery, an internal short circuit will occur. May cause. Furthermore, the above-mentioned processed piece may interfere with the fixing between the wire mesh and other members (battery can or electrode) when they remain between them. Therefore, when the current collector is manufactured by punching the wire net, the yield of the battery may decrease.

  Further, in the case of forming the unevenness on the battery can as in the battery described in Patent Document 2, the unevenness is provided inside the press die so that the unevenness is formed on the battery can at the same time as the press molding of the battery can. Due to the method, it is difficult to form the unevenness in a fine shape such as a lattice shape. In addition, the technique described in Patent Document 2 has a problem in that the unevenness is not preferable in terms of appearance as a battery, because the uneven shape is a shape that is protruded not only on the inner surface side but also on the outer surface side of the battery can.

  The present invention has been made in view of the above problems, and effectively reduces the internal resistance of a small battery that can supply a large current pulse in the region of 1 mA to several mA and that has a higher discharge current than conventional batteries. An object of the present invention is to provide a non-aqueous electrolyte secondary battery which 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 in manufacturing a small battery with an increased discharge current as compared with the conventional one, it is possible to maintain a sufficient discharge current and voltage for a long time. It is an object of the present invention to provide a method for manufacturing a non-aqueous electrolyte secondary battery, which can discharge for a long time and can manufacture a non-aqueous electrolyte secondary battery having excellent discharge characteristics and appearance characteristics with high yield.

  The present inventor has conducted extensive studies in order 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 producing sufficient discharge characteristics, manufacturing The experiment for improving the time yield was repeated. As a result, first, a concavo-convex structure is formed on the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can that form the battery container, and this portion is used as a current collecting portion integrated with the positive electrode can or the negative electrode can. It was found that the contact area between the positive electrode, the negative electrode, and the current collector can be reliably increased to reduce the contact resistance. In addition, by forming the uneven structure on the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can by etching treatment, it is possible to prevent the occurrence of processed pieces, which is a problem when a battery can is manufactured by a conventional method. It was also found that the uneven structure can be formed in a fine pattern. As a result, in the non-aqueous electrolyte secondary battery in which the discharge current is increased compared to the conventional one, it becomes possible to discharge for a long time while maintaining a sufficient discharge current and voltage, and the appearance characteristics are excellent, and the yield is significantly increased. The present invention has been completed and the present invention has been completed.

That is, the non-aqueous electrolyte secondary battery of the present invention, a positive electrode containing a positive electrode active material, a negative electrode containing 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 non-aqueous electrolyte containing a is a non-aqueous electrolyte secondary battery housed in a metal container, the container is a bottomed cylindrical positive electrode can having an opening, A cylindrical negative electrode can with a lid forming a housing space between the positive electrode can and 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. are as connected thereto collector portion, the collector unit is configured to have a concave-convex structure composed of a flat portion and a recess provided in said bottom surface and said inner lid surface, and, of the current collector the proportion of the flat portion to the area is characterized by 10-50% der Rukoto.

  According to the present invention, the positive electrode can and the positive electrode can are provided by providing the current collector having the concavo-convex structure integrated with the positive electrode can and the negative electrode can on the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can. Since the contact areas between the current collecting portion and the current collecting portion provided in the negative electrode can are reduced, the contact resistance between them is reduced. Further, since the concavo-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 concavo-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 1 mA to several mA, it is possible to discharge for a long time while maintaining a sufficient discharge current and voltage, which is excellent. Discharge characteristics and appearance characteristics are obtained.

Further , according to the present invention, by setting the ratio of the flat portion to the area of the current collector within the above range, the contact area between each electrode and the current collector is reliably increased, and the contact area between them is Can be significantly reduced.

  Further, 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, at least a part of the current collector is embedded in the positive electrode and the negative electrode, so that the contact area between each electrode and each current collector is significantly increased and the contact resistance is significantly reduced. To be done.

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

  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 portion having the concavo-convex structure is increased, and part of the current collecting portion 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 significantly reduced.

  Further, in the non-aqueous electrolyte secondary battery of the present invention, in the above configuration, the positive electrode can and the negative electrode can may be made of a clad material whose outer surface side is stainless steel and whose inner surface side 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 on the inner surface side, that is, any of aluminum, nickel, or copper is arranged, It becomes easy to form the uneven structure. Further, aluminum, nickel, or copper is arranged on the inner surface side of the positive electrode can and the negative electrode can, and the current collector is made of these materials, so that the contact resistance between each electrode and the current collector is significantly reduced. It will be possible.

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

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

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

  According to the present invention, since the positive electrode and the negative electrode contain graphite or carbon black, the diffusion resistance in each electrode can be reduced more effectively.

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

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

  Further, in the non-aqueous 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 non-aqueous electrolyte is equal to the total amount of the non-aqueous electrolyte. On the other hand, it is preferably in the range of 10 to 23% by mass.

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

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

According to the present invention, a large discharge capacity can be obtained by using PC and EC, which are cyclic carbonate solvents having a high dielectric constant and a high solubility of a supporting salt, as the organic solvent constituting the non-aqueous electrolyte. Is possible. In addition, since PC and EC have high boiling points, for example, a non-aqueous electrolyte that is hard to volatilize even when used or stored in a high temperature environment can be obtained.
Further, by using PC, which has a lower melting point than EC, as the organic solvent in combination with EC, it becomes possible to improve the discharge characteristics especially at low temperatures.
Also, by using DME, which is a chain ether solvent having a low melting point, as the organic solvent, the discharge characteristics at low temperatures are improved as in the above. Further, since DME has a low viscosity, the conductivity of the non-aqueous electrolyte is improved. Further, by solvating DME with Li ions, a larger discharge capacity can be obtained as a non-aqueous electrolyte secondary battery.

Next, the manufacturing method of the non-aqueous electrolyte secondary battery of the present invention, by processing a metal plate material, to form a bottomed cylindrical positive electrode can and an open cylindrical negative electrode can, the positive electrode A storage container forming step of obtaining a storage container composed of a can and the negative electrode can, and a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, and arranged between the positive electrode and the negative electrode in the storage container. A separator and a battery assembly step of containing a non-aqueous electrolyte containing at least a supporting salt and an organic solvent, and a method of manufacturing a non-aqueous electrolyte secondary battery, wherein the storage container forming step is the positive electrode. at least a portion by selectively removing by etching process, look including the process of forming the current collecting portion of the concavo-convex structure comprising a flat portion and the recess in the inner bottom surface and the inner lid surface of the negative electrode can of the can, and The current collecting portion is formed by setting the ratio of the flat portion to the area of the current collecting portion to 10 to 50% .

  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 etching to form a current collector having a concavo-convex structure, thereby generating a processed piece or the like. Therefore, it is possible to prevent a short circuit in the battery and incomplete fixing of the electrodes. In addition, since the current collecting portion can be formed with a finely patterned concavo-convex structure by the etching process, the contact area between each electrode is increased and the contact resistance is reduced. Further, since the current collecting portion having the concavo-convex structure is formed by etching, the concavo-convex shape does not occur on the outer surface side of the positive electrode can and the negative electrode can. Therefore, in particular, a non-aqueous electrolyte secondary battery that can supply a large current pulse in the region of 1 mA to several mA and can be discharged for a long time while maintaining a sufficient discharge current and voltage and is excellent in discharge characteristics and appearance characteristics. Batteries can be manufactured with high yield.

According to the non-aqueous electrolyte secondary battery of the present invention, a configuration in which the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can are provided with a current collector having an uneven structure integrated with the positive electrode can and the negative electrode can. Therefore, the contact area between each electrode and each current collecting portion is increased, and the contact resistance between them is reduced.
As a result, the internal resistance can be remarkably reduced, and particularly in a small non-aqueous electrolyte secondary battery capable of supplying a large current pulse in the region of 1 mA to several mA, a state in which sufficient discharge current and voltage are maintained. Discharge for a long time and excellent discharge characteristics can be obtained. In addition, the positive electrode can and the negative electrode can are provided with a current collecting portion having an uneven structure on the inner surface side, and the outer surface side does not have an uneven shape, so that excellent appearance characteristics are obtained and processed pieces and the like are produced during manufacturing. And yield is excellent.
Therefore, 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. Will be 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 subjected to etching treatment to form a current collecting portion having an uneven structure. Since it is a method, the current collecting portion can be formed with a finely patterned concavo-convex structure without producing a processed piece or the like.
Therefore, in particular, a small-sized non-aqueous electrolyte secondary battery, which has a significantly reduced internal resistance of the battery and can supply a large current pulse in the region of 1 mA to several mA and which is excellent in discharge characteristics and appearance characteristics, can be obtained with high yield. It becomes possible to manufacture.

FIG. 1 is a sectional view schematically showing a coin-type (button-type) non-aqueous electrolyte secondary battery according to an embodiment of the present invention. FIG. 2 is a diagram schematically illustrating a coin-type (button-type) non-aqueous electrolyte secondary battery that is an embodiment of the present invention. Inner bottom surfaces of a positive electrode can and a negative electrode can that form a storage container. FIG. 3 is a schematic view showing an example of a plan view shape of a current collector provided in the. FIG. 3 is a diagram schematically illustrating a coin-type (button-type) non-aqueous electrolyte secondary battery that is an embodiment of the present invention. Inner bottom surfaces of a positive electrode can and a negative electrode can that form a storage container. FIG. 7 is a schematic view showing another example of the plan view shape of the current collector provided in the. FIG. 4 is a diagram schematically illustrating a coin-type (button-type) non-aqueous electrolyte secondary battery that is an embodiment of the present invention. Inner bottom surfaces of a positive electrode can and a negative electrode can that form a storage container. FIG. 7 is a schematic view showing another example of the plan view shape of the current collector provided in the. FIG. 5: is a figure which illustrates typically the non-aqueous electrolyte secondary battery comprised by the coin type (button type) which is embodiment of this invention, and the inner bottom face of the positive electrode can and negative electrode can which comprise a storage container. FIG. 3 is a cross-sectional view showing an example of a main part of a current collector provided in the. FIG. 6 is a diagram schematically illustrating a coin-type (button-type) non-aqueous electrolyte secondary battery that is an embodiment of the present invention. Inner bottom surfaces of a positive electrode can and a negative electrode can that form a storage container. FIG. 6 is a cross-sectional view showing another example of the main part of the current collector provided in the.

  Hereinafter, embodiments of the non-aqueous electrolyte secondary battery of the present invention and a method for manufacturing the same will be described, and each configuration thereof will be described in detail with reference to FIGS. 1 to 6. The non-aqueous electrolyte secondary battery described in the present invention is specifically one in which an active material used as a positive electrode or a negative electrode and a non-aqueous electrolyte are housed in a container. Can be applied to an electrochemical cell such as a lithium ion capacitor.

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

  More specifically, the non-aqueous electrolyte secondary battery 1 is fixed between a positive electrode can 12 having a bottomed cylindrical shape and a gasket 40 in the opening 12 a of the positive electrode can 12, and is housed 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 to the inside, that is, the negative electrode can 22 side. Equipped with.

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 face each other via the separator 30, and the non-aqueous electrolyte 50 is It is filled. Further, in the example shown in FIG. 1, a lithium foil 60 is interposed between the negative electrode 20 and the separator 30.
Further, as shown in FIG. 1, the gasket 40 is inserted along the inner peripheral surface of the positive electrode can 12, is connected to the outer periphery of the separator 30, and holds the separator 30.
Further, the positive electrode 10, the negative electrode 20, and the separator 30 are impregnated with the nonaqueous electrolyte 50 filled in the storage container 2.

  Further, as shown in FIG. 1, in the non-aqueous electrolyte secondary battery 1, the positive electrode 10 is electrically connected to a positive electrode current collector (current collector) 14 arranged 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 arranged on the inner lid surface of the negative electrode can.

  The non-aqueous 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 to accumulate (charge) charges. It is capable of discharging (discharging) charges.

  In the non-aqueous electrolyte secondary battery 1 of the present embodiment, the positive electrode current collector 14 and the negative electrode current collector 24 are composed of the flat parts 14a and 24a and the recesses 14b and 24b provided on the inner bottom surface or the inner lid surface. Has an uneven structure.

  The present inventor has conducted earnest studies in order to improve the discharge characteristics of a small non-aqueous electrolyte secondary battery that can be used for various small electronic devices and can supply a large current pulse in the region of 1 mA to several mA. As a result, a concavo-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 that form the storage container 2, and this portion is integrated with the positive electrode can 12 or the negative electrode can (a positive electrode current collector). By using the portion 14 and the negative electrode current collector 24), the contact area between the positive electrode 10 and the negative electrode 20 and each current collector (the positive electrode current collector 14, the negative electrode current collector 24) is reliably increased, and the contact resistance is increased. It was found that Further, it has been found that by providing the concavo-convex structure only on the inner surface side of the positive electrode can 12 and the negative electrode can 22, the concavo-convex shape does not occur on the outer surface side, and excellent appearance characteristics can be maintained.

  Furthermore, the present inventors prefer to selectively remove a part of the inner bottom surface and the inner lid surface by etching when forming the uneven structure on the inner bottom surface of the positive electrode can 12 and the inner lid surface of the negative electrode can 22. It has been found that, since the uneven structure can be formed in a fine pattern, the contact area between each electrode and each current collecting portion can be further increased, and a non-aqueous electrolyte secondary battery with further reduced contact resistance can be manufactured. In addition, by forming the uneven structure by a method of 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 generation of processed pieces and the like, which may cause a short circuit in the battery or the electrode. It has been found that the immobilization can be prevented from being incomplete and the yield is significantly improved.

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

[Positive can and negative 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 a plan view. As a material for such a positive electrode can 12, any conventionally known material can be used without any limitation, and examples thereof include stainless steel such as SUS329J4L.

  In addition, the negative electrode can 22 is configured in a cylindrical shape (hat shape) with a lid, and a tip portion 22a thereof is configured to enter the positive electrode can 12 through the opening 12a. Like the material of the positive electrode can 12, the material of the negative electrode can 22 may be conventionally known stainless steel, and for example, SUS304-BA or the like can be used.

  Further, in the positive electrode can 12 and the negative electrode can 22, in addition to the single-layer metal plate material made of the above stainless steel, for example, the outer surface side is the above stainless steel and the inner surface side is a multi-layer clad of aluminum, nickel or copper. Materials can be used. As such a clad material, for example, a material in which aluminum, nickel, or copper is pressure-welded to stainless steel to have a plate-like shape can be used.

  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 or the negative electrode can. It is possible to use a plate member having an average plate thickness of about 0.20 mm in the whole 22.

  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 to the negative electrode can 22 side with the gasket 40 interposed therebetween, and the non-water can The electrolyte secondary battery 1 is hermetically held in the state where the accommodation space is formed. Therefore, 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 non-aqueous electrolyte secondary battery 1 according to the present invention, as described above, the positive electrode current collector 14 having the uneven structure including the flat portion 14a and the concave portion 14b 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 collecting portion 24 having a concavo-convex structure including a flat portion 24a and a concave portion 24b is provided.
That is, in the non-aqueous electrolyte secondary battery 1, the inner bottom surface of the positive electrode can 12 also serves as the current collector (positive electrode current collector 14) on the positive electrode 10 side, and the inner lid surface of the negative electrode can 22 collects on the negative electrode 20 side. It also serves as a body (negative electrode current collector 24) and has a structure in which the battery can and the current collector are integrated.

  The non-aqueous electrolyte secondary battery 1 according to the present invention is provided with each current collector (positive electrode current collector 14, negative electrode current collector 24) having an uneven structure integrated with the positive electrode can 12 or the negative electrode can 22. The contact areas 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 increase. This is because at least a part of the positive electrode 10 or the negative electrode 20 made of a material whose details will be described below enters the inside of each of the recesses 14b and 24b provided in the positive electrode current collector 14 and the negative electrode current collector 24, respectively. This is because the contact area between the collector and each current collector increases. In this way, the contact area between each electrode and each current collector is increased, so that the contact resistance between them is reduced, and the internal resistance of the non-aqueous electrolyte secondary battery 1 is significantly reduced. it can. As a result, 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. As compared with the non-aqueous electrolyte secondary battery having the conventional structure, very excellent discharge characteristics can be obtained.

  In the non-aqueous electrolyte secondary battery 1 according to the present invention, the plan-view shapes of the positive electrode current collector 14 and the negative electrode current collector 24 having the concavo-convex structure can increase the contact area with the positive electrode 10 or the negative electrode 20. The shape is not particularly limited as long as it has such a shape. For example, as a plan view shape of the positive electrode current collector 14 and the negative electrode current collector 24, in addition to the lattice shape including the flat portions 14a (24a) and the recesses 14b (24b) as shown in FIG. 2, it is also 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 14a (24a) that are elongated in a plan view are arranged at equal intervals in the vertical and horizontal directions to form a plurality of recesses 14b (24b) that are rectangular in a plan view. Are aligned vertically and horizontally. Further, in the example shown in FIG. 3, a plurality of flat portions 14a (24a) having a ring shape in plan view are arranged in a zigzag pattern.

  Further, in the positive electrode current collector 14 and the negative electrode current collector 24 in the example shown in FIG. 4, a plurality of recesses 14b (24b) having a circular shape in plan view are arranged in a zigzag pattern. Although not shown in detail in FIG. 4, the positive electrode current collector 14 and the negative electrode current collector 24 shown in FIG. 4 are configured such that the bottom edge portions of the recesses 14b and 24b have a shape close to a semicircular cross section. (See the cross-sectional shape shown in FIG. 5). Further, the positive electrode current collecting portion and the negative electrode current collecting portion are not limited to the above-mentioned shapes, and, for example, although detailed illustration is omitted, the plan view shape of the concave portion is a rhombic shape or a triangular shape, and each of them is arranged in a zigzag pattern. It is also possible to configure the above, and the same effect as described above can be obtained.

  In the non-aqueous electrolyte secondary battery 1 according to the present invention, since the positive electrode current collector 14 and the negative electrode current collector 24 have the above-described plan view shape, the contact area between each electrode and each current collector is reduced. Since it further increases, the contact resistance can be effectively reduced.

  Further, as shown in FIG. 5, in the cross-sectional shape of the positive electrode current collecting portion 14 and the negative electrode current collecting portion 24, the bottom edge portions of the recesses 14b and 24b are not formed in a square shape, so that each electrode and each current collecting portion are not formed. When the electrically conductive adhesive 25 (see FIG. 6) is interposed between the electrically conductive portion and the electrically conductive portion, it is preferable from the viewpoint that the electrically conductive adhesive 25 can be uniformly applied. In addition, as in the illustrated example, the bottom edge portions of the recesses 14b and 24b are formed to have a rounded cross section, and it is more preferable that the cross section has a semicircular shape as close as possible. In this way, the bottom edges of the recesses 14b and 24b are rounded so that the conductive adhesive 25 can surely enter the recesses 14b and 24b as shown in FIG. The occurrence of unevenness is suppressed, and the conductive adhesive 25 can be uniformly applied to each current collector. On the other hand, if the bottom edge of the recess is formed in a square shape, it becomes difficult for the conductive adhesive 25 to enter this portion, and uneven coating may occur.

  When the above-mentioned concavo-convex structure is formed by an etching process, the corners of the bottom surfaces of the recesses 14b and 24b have a constant R as shown in the figure due to the characteristics of this process. Accordingly, in the present invention, the conductive adhesive 25 can be uniformly applied to each current collecting portion, so that the contact resistance between each electrode and each current collecting portion can be effectively reduced.

  Further, in the positive electrode current collector 14 and the negative electrode current collector 24, it is preferable that the ratio of the flat portions 14a and 24a to the area of each current collector is 10 to 50%. By setting the ratio of the flat portions 14a and 24a in the positive electrode current collector 14 and the negative electrode current collector 24 to the above range, the contact area between each electrode and the current collector can be reliably increased, and the contact between them can be ensured. It is possible to significantly reduce the area. Here, when 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 becomes too large, and when the ratio exceeds the upper limit of the above range. The proportion of the flat portions 14a and 24a is too large, and in any case, it is difficult to contribute to the increase of the contact area.

  The average depth D of the recesses 14b and 24b of the positive electrode current collector 14 and the negative electrode current collector 24 is not limited to 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 deformed state at the time of charging/discharging, it is about ½ to ⅕ of the thickness of the positive electrode 10 and the negative electrode 20, which will be described in detail later. A range is preferred. By setting the average depth D of the recesses 14b and 24b within the above range, the embedding allowance of each current collector having the concavo-convex structure with respect to each electrode is optimized, and a large contact area can be secured, and each electrode can collect each electrode. Since it is securely fixed to the electric part, it is possible to prevent problems due to electrode displacement and the like.

On the other hand, when the average depth D of the recesses 14b and 24b exceeds 1/2 of the thickness of the positive electrode 10 and the negative electrode 20, the flat portions 14a and 24a are deeply cut into each electrode, and thus the electrodes There is a possibility that cracks or cracks may occur on the surface, or conversely, the number of contact points between each electrode and each current collector may decrease, resulting in incomplete electrical connection. Further, since the flat portions 14a and 24a are to be deeply embedded in the respective electrodes, a high pressing force is required in the pressure welding step, and the cost of manufacturing equipment and the like increases.
If the average depth D of the recesses 14b and 24b is less than ⅕ of the thickness of the positive electrode 10 and the negative electrode 20, the embedding allowance for each electrode of each current collector having a concavo-convex structure is too small. Both are difficult to be fixed, and there is a possibility that problems such as electrode displacement may occur. Further, the contact area between each electrode and each current collecting portion is almost the same as when each current collecting portion is formed on a plane, and it may be difficult to obtain the effect of adopting the uneven structure. .

  In addition, in the non-aqueous 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 to form the recesses 14b and 24b. It is preferable that the conductive adhesive 25 is allowed to enter the inside and the conductive adhesive 25 is interposed between each electrode and each current collecting portion in order to further improve the adhesion and conductivity between them. In this way, in order to interpose the conductive adhesive 25 between each electrode and each current collecting portion, as shown in the example shown in FIG. 6, the conductive adhesive is formed in the concave portion of each current collecting portion having an uneven structure. It is preferable to allow a sufficient amount of the adhesive adhesive 25 to intervene 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 of μm in consideration of the filling by the positive electrode 10 and the negative electrode 20 and the interposition of the conductive adhesive 25. .

  As in the example shown in FIG. 2, the flat portions 14a and 14b formed in a convex shape in a sectional view have a narrow width, as will be described later, with respect to the pellets forming the positive electrode 10 and the negative electrode 20. This is preferable from the viewpoint of easily biting and increasing the contact area between each electrode and each current collector. For example, in the case where the positive electrode current collector 14 and the negative electrode current collector 24 are formed in a lattice shape as shown in FIG. 2, the width W1 is 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 recesses 14b and 24b are formed in a square shape, it is preferable that the width W2 is in the above range in any case. If the width W2 of the recesses 14b and 24b is less than 1 mm, the conductive adhesive 25 is unlikely 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. If the width W2 of the recesses 14b and 24b exceeds 2 mm, it may be difficult to contribute to the increase in the contact area between each electrode and each current collector.

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

  Further, as described above, in the case where the current collecting portions are configured such that the concave portions having a rhombic shape in plan view are arranged in a zigzag pattern, the diagonal long side dimension (LW)×the diagonal short side dimension (SW) of the rhombus is calculated. 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. Further, in this case, the width of each flat portion between the recesses is preferably about 0.1 to 0.3 mm, similar to W1 described above.

  In addition, as described above, even when each current collecting portion is configured such that the concave portions having a triangular shape in plan view are arranged in a zigzag shape, the width of each flat portion between the concave portions is 0 as in the above W1. It is preferable that it is about 1 to 0.3 mm.

  In addition, when a single-layer plate material made of stainless steel is used for the positive electrode can 12 and the negative electrode can 22, the hardness of the positive electrode current collector 14 and the negative electrode current collector 24 having the uneven structure is further increased. In this way, the hardness of the positive electrode current collector 14 and the negative electrode current collector 24, which are formed by the flat portions 14a and 24a and the recesses 14b and 24b, is increased, so that the positive electrode 10 or the negative electrode 20 is pressed against the respective current collectors. In this case, the current collectors are not crushed and the depths of the recesses 14b and 24b are maintained. This makes it easier for the positive electrode 10 or the negative electrode 20 to enter the recesses 14b and 24b, and allows each electrode to penetrate deep into each recess, so that the contact area between each electrode and the current collector is reduced. It definitely increases. Therefore, the contact resistance between each electrode and each current collector can be significantly reduced, and the discharge characteristics of the non-aqueous electrolyte secondary battery 1 can be further improved.

  On the other hand, when a positive and negative electrode can 12 and a negative electrode can 22 are made of a stainless steel material on the outer surface side and a clad material of aluminum material, nickel material or copper on the inner surface side, the hardness of the inner surface side is low. 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 above-mentioned 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. Further, aluminum or nickel is arranged on the inner surface sides of the positive electrode can 12 and the negative electrode can 22, and the positive electrode current collector 14 or the negative electrode current collector 24 is made of these materials, so that the electrodes and the current collectors are separated from each other. The contact resistance between them is greatly reduced.

  Regarding the position where the concavo-convex 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 member having a cylindrical shape with a lid (hat shape), the inner surface of the inner lid is usually etched to form the concavo-convex structure. There is no problem in forming. On the other hand, since the positive electrode can 12 has an adhesive portion to the later-described gasket 40 at the end portion of the inner bottom surface, it is necessary to form the concavo-convex structure only at the position avoiding the adhesive portion to the gasket 40 by design. is there. Further, it is preferable that the entire surface of the inner bottom surface of the positive electrode can 12 in contact with the positive electrode 10 is subjected to an etching treatment to form an uneven structure over the entire area.

  The details of the etching treatment for forming the uneven 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, but either wet etching or dry etching may be employed. In addition, it is possible to form the concavo-convex structure using a method of sandblasting, but it is most preferable to use the method of wet etching treatment from the viewpoint of workability with respect to the metal plate material. In the present invention, the positive electrode current collector 14 or the negative electrode current collector 24 having the concavo-convex structure is formed by the etching treatment, so that a processed piece or the like does not occur during manufacturing and the non-aqueous electrolyte secondary battery is excellent in yield. 1 is obtained. Further, in the non-aqueous electrolyte secondary battery 1 according to the present invention, the positive electrode current collector 14 or the negative electrode current collector 24 having an uneven structure provided on the inner surface side of the positive electrode can 12 and the negative electrode can 22 is formed by etching. Since the outer surface does not have unevenness, the appearance characteristics are excellent.

  In addition, in the example shown in FIG. 1, the tip 22a of the negative electrode can 22 has a shape folded back to the outer surface side, but the invention is not limited to this, and for example, the end face of the metal plate material is the tip 22a. The present invention can be applied even when the above-mentioned folded shape is not provided.

  Further, as the non-aqueous electrolyte secondary battery to which the configuration described in detail in the present embodiment can be applied, for example, a coin-type non-aqueous electrolyte secondary battery having a general size of 920 size (outer diameter φ9 mm× In addition to the height (2.0 mm), batteries of various sizes, especially small size 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 portion 22 a of the negative electrode can 22 is arranged inside the annular groove 41.
Further, it is preferable that the gasket 40 is made of a resin having a heat distortion 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 will be generated when the non-aqueous electrolyte secondary battery 1 is used or stored in a high temperature environment or during use of the non-aqueous electrolyte secondary battery 1. Even if it occurs, it is possible to prevent the non-aqueous electrolyte 50 from leaking due to the 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. Polymerized resin (PFA), polyether ether ketone resin (PEEK), polyether nitrile resin (PEN), polyether ketone resin (PEK), polyarylate resin, polybutylene terephthalate resin (PBT), polycyclohexane dimethylene terephthalate resin, Examples include plastic resins such as polyether sulfone resin (PES), polyamino bismaleimide resin, polyether imide resin, and fluororesin. Among these, it is preferable to use polypropylene resin for the gasket 40 from the viewpoint that the gasket can be prevented from being significantly deformed during use or storage in a high temperature environment and the sealing property of the non-aqueous electrolyte secondary battery can be further improved.

  Further, as the gasket 40, a material obtained by adding glass fiber, michai whiskers, ceramic fine powder, or the like to the above material in an amount of 30% by mass or less can also be suitably used. By using such a material, it is possible to prevent the gasket from being significantly deformed due to high temperature and the non-aqueous electrolyte 50 from leaking.

  Further, a sealant may be further applied to the inner surface of the annular groove of the gasket 40. As such a sealant, asphalt, epoxy resin, polyamide resin, butyl rubber adhesive, etc. 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 thereof is in a compressed state. However, the compression rate at this time is not particularly limited, and the non-aqueous electrolyte secondary battery is not limited. The range may be such that the inside of 1 can be reliably sealed and the gasket 40 does not break.

[Non-aqueous electrolyte]
The non-aqueous electrolyte secondary battery 1 of the present invention uses, as the non-aqueous electrolyte 50, one containing at least an organic solvent and a supporting salt. Usually, the non-aqueous electrolyte used in the non-aqueous electrolyte secondary battery is composed of a supporting salt dissolved in a non-aqueous solvent such as an organic solvent, and the heat resistance and viscosity required for the non-aqueous electrolyte 50 are taken into consideration. , Its characteristics are determined.

  Generally, the supporting salt contained in the non-aqueous electrolyte of the non-aqueous electrolyte secondary battery is a known Li compound added to the non-aqueous electrolyte as a supporting salt, 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. As described above, the non-aqueous electrolyte 50 contains LiFSI having a small molecular diameter as a supporting salt, so that the diffusion resistance in the non-aqueous electrolyte 50 becomes small, so that the transfer of charges becomes faster 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 non-aqueous electrolyte 50 can be determined in consideration of the type of supporting salt and the type of positive electrode active material described later. In the present invention, the content of LiFSI 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 non-aqueous electrolyte 50 to the above range, the effect of reducing the diffusion resistance and improving the conductivity as described above can be more remarkably obtained. Therefore, in a small non-aqueous electrolyte secondary battery such as a coin-type battery having a relatively large discharge current and improved discharge characteristics, it is possible to obtain more excellent discharge characteristics.

Further, by setting the content of LiFSI in the non-aqueous electrolyte 50 in the above range, the voltage drop in the initial stage of discharge can be suppressed, and further the discharge characteristics in a low temperature environment can be improved, which is sufficient in a wide temperature range. The discharge capacity is obtained.
Further, the content of LiFSI in the non-aqueous electrolyte 50 is more preferably in the range of 13 to 21% by mass with respect to the total amount of the non-aqueous electrolyte 50, from the viewpoint that the above effect is remarkably obtained.

  If the concentration of the supporting salt in the non-aqueous electrolyte 50 exceeds the upper limit of the above range, it becomes difficult to obtain the discharge capacity, and if it is less than the above lower limit, the internal resistance may increase significantly. .. Therefore, if the concentration of the supporting salt (LiFSI) in the non-aqueous electrolyte 50 is too high or too low, the battery characteristics may be adversely affected. Therefore, the concentration is preferably in the above range.

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, but for example, PC and EC which are cyclic carbonate solvents, and DME which is a chain ether solvent. Can be used as a mixed solvent containing the compound in a proper mixing ratio.
By optimizing the composition of the organic solvent used for the non-aqueous electrolyte 50, ensure sufficient discharge characteristics in the small non-aqueous electrolyte secondary battery 1 capable of supplying a large current pulse in the region of about 1 mA to several mA. In addition, the non-aqueous electrolyte secondary battery 1 capable of maintaining a sufficient discharge capacity in a wide temperature range including a low temperature environment can be realized.

  Generally, when a non-aqueous electrolyte containing an organic solvent is used in a non-aqueous electrolyte secondary battery, the solubility of the lithium salt is poor, so the temperature dependence of the conductivity becomes large, and compared to the characteristics at room temperature, There is a problem in that the characteristics below are greatly degraded. On the other hand, in order to improve low-temperature characteristics, for example, when ethyl carbonate or acetic acid ester having an asymmetric structure which is a chain carbonic acid ester is used as the organic solvent of the non-aqueous electrolyte, conversely, non-aqueous solution under high temperature is used. There is a problem that the characteristics of the electrolyte secondary battery are deteriorated. Further, even when an organic solvent such as ethyl methyl carbonate is used as 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 appropriate organic solvents in the non-aqueous electrolyte 50. It is preferable to use the one that contains.
Specifically, first, it is possible to obtain a large discharge capacity by using PC and EC having a high dielectric constant and a high solubility of a supporting salt as the cyclic carbonate solvent. In addition, since PC and EC have high boiling points, a non-aqueous electrolyte that is hard to volatilize even when used or stored in a high temperature environment can be obtained.
Further, by using PC, which has a lower melting point than EC as the cyclic carbonate solvent, mixed with EC, it becomes possible to improve the low temperature characteristics.
Further, by using DME having a low melting point as the chain ether solvent, low temperature characteristics are improved. Further, since DME has a low viscosity, the electric conductivity of the non-aqueous electrolyte is improved. Furthermore, by solvating DME with Li ions, 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), and includes, for example, propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), trifluoroethylene carbonate (TFPC), chloro. Examples thereof include ethylene carbonate (ClEC), trifluoroethylene carbonate (TFEC), difluoroethylene carbonate (DFEC) and vinylene carbonate (VEC). In the non-aqueous electrolyte secondary battery 1 according to the present invention, particularly in consideration of easiness of forming a film on the electrode on the negative electrode 20, improvement of low temperature characteristics, and improvement of capacity retention ratio at high temperature. It is preferable to use two types of PC and EC as the cyclic carbonate solvent having a structure represented by the following (Chemical formula 1).

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

  As described above, 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 in the organic solvent used for the non-aqueous electrolyte 50. .. In addition, since PC and EC have high boiling points, a non-aqueous electrolyte that is hard to volatilize even when used or stored in a high temperature environment can be obtained. Furthermore, by using PC, which has a lower melting point than EC as the cyclic carbonate solvent, mixed with EC, excellent low-temperature characteristics can be obtained.

  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, as a chain ether solvent having a structure represented by the following (Chemical formula 2), in particular, from the viewpoint of improving conductivity, and further improving low-temperature characteristics while ensuring capacity at room temperature. It is preferable to use DME which is easily solvated 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. Moreover, since DME has a low viscosity, the electrical conductivity of the non-aqueous electrolyte is improved. Furthermore, since DME is solvated with Li ions, a large discharge capacity can be obtained as a non-aqueous electrolyte secondary battery.

In the non-aqueous electrolyte secondary battery 1 according to the present invention, the compounding ratio of each organic solvent in the solvent of the non-aqueous electrolyte 50 is {PC:EC:DME}=0.5 to 1.50 by volume ratio. It is preferable to set in the range of 0.5 to 1.5:1 to 3. The blending 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 in terms of volume ratio, and is 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 remarkably obtained without impairing the capacity retention rate at high temperature or room temperature as described above.

More specifically, if the blending ratio of propylene carbonate (PC), which is a cyclic carbonate solvent, is at least the lower limit of the above range, the low temperature characteristics are improved by mixing PC with a melting point lower than EC and EC. A remarkable effect can be obtained.
On the other hand, PC has a lower permittivity than EC and cannot increase the concentration of the supporting salt. Therefore, if the content is too high, it may be difficult to obtain a large discharge capacity. It is preferable to limit to the upper limit of the above range or less.

Further, in the organic solvent, when the blending ratio of ethylene carbonate (EC) which is a cyclic carbonate solvent is at least the lower limit of the above range, the dielectric constant of the non-aqueous electrolyte 50 and the solubility of the supporting salt are increased, and the non-aqueous electrolyte is increased. It becomes possible to obtain a large discharge capacity as a secondary battery.
On the other hand, EC has poor electric conductivity due to its high viscosity, and since its melting point is high, its low-temperature characteristics may deteriorate if its content is too high. Therefore, its compounding ratio should be below the upper limit of the above range. It is preferable to limit
Furthermore, by setting the blending ratio of EC in the organic solvent within the above range, it becomes possible to suppress an increase in internal resistance in a low temperature environment.

Further, in the organic solvent, if the compounding ratio of dimethoxyethane (DME) which is a chain ether solvent is not less than the lower limit of the above range, the DME having a low melting point is contained in the organic solvent at a predetermined amount or more, so that a low temperature is obtained. The effect of improving the characteristics can be obtained. Further, since DME has a low viscosity, electric 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 and cannot increase the concentration of the supporting salt, it may be difficult to obtain a large discharge capacity if the content thereof is too large. Therefore, the compounding ratio of DME is not more than the upper limit of the above range. It is preferable to limit
Furthermore, by setting the blending ratio of DME in the organic solvent within the above range, it is possible to suppress the voltage drop at the initial stage of discharge.

  In the non-aqueous electrolyte secondary battery 1 according to the present invention, in addition to the positive electrode current collector 14 and the negative electrode current collector 24 having the uneven structure described above, the non-aqueous electrolyte 50 contains LiFSI as a supporting salt, Furthermore, when the composition containing PC, EC and DME in an appropriate range is adopted as the organic solvent, the internal resistance of the entire battery at the end of discharge is significantly reduced. As a result, sufficient discharge characteristics can be secured even in a small nonaqueous electrolyte secondary battery 1 that can supply a large current pulse in the region of 1 mA to several mA.

  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 under a low temperature environment of −30 to −40° C. Can be prevented from being hindered from moving. Thereby, it is possible to maintain a sufficient discharge capacity in a wide temperature range including a low temperature environment, and further, in a small non-aqueous electrolyte secondary battery 1 capable of supplying a large current pulse in a region of about 1 mA to several mA, It becomes possible to secure sufficient discharge characteristics.

[Positive electrode]
The positive electrode 10 used in the non-aqueous electrolyte secondary battery 1 of the present invention contains, for example, a positive electrode active material made of lithium manganese oxide and also contains graphite as a conduction aid. Further, as the positive electrode 10, it is possible to use, 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).

The positive electrode active material contained in the positive electrode 10 is not particularly limited, and examples thereof include lithium manganese oxides such as LiMn ₂ O ₄ having a spinel type crystal structure and Li ₄ Mn ₅ O ₁₂ , as well as MoO ₃ (trioxide). Molybdenum) and the like.
In addition, among the above-mentioned lithium manganese oxides, in particular, a part of Mn such as Li _1+x Co _y Mn _2−x−y O ₄ (0≦x≦0.33, 0<y≦0.2) It is preferable that Co be replaced by Co. As described above, by adding the transition metal element such as Co or Ni to the lithium manganese oxide and using the positive electrode active material in which a part of the transition metal element is replaced by the transition metal element, the effect of further improving the discharge characteristics can be obtained. ..

In the present embodiment, by using the positive electrode active material composed of the lithium manganese oxide having the above composition for the positive electrode 10, the discharge characteristics are improved particularly in a low temperature environment, and a sufficient discharge capacity is obtained in a wide temperature range. In addition, sufficient discharge characteristics can be obtained even in the small nonaqueous electrolyte secondary battery 1 capable of supplying a large current pulse in the region of 1 mA to several mA.
Further, in the present embodiment, the positive electrode active material may contain not only one of the above lithium manganese oxides but also a plurality thereof.

When a granular positive electrode active material made of the above material is used, its particle diameter (D50) is not particularly limited and is, for example, preferably 0.1 to 100 μm, more preferably 1 to 10 μm.
If the particle size (D50) of the positive electrode active material is less than the lower limit of the above-mentioned preferred range, it becomes difficult to handle because the reactivity increases when the non-aqueous electrolyte secondary battery is exposed to high temperatures, and the upper limit is exceeded. If it exceeds, the discharge rate may decrease.
In addition, the "particle diameter (D50) of the positive electrode active material" in the present invention is a particle diameter measured by 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 and the like required for the non-aqueous electrolyte secondary battery 1, and is preferably 50 to 95% by mass. When the content of the positive electrode active material is at least the lower limit value of the above preferred range, sufficient discharge capacity is easily obtained, and when it is at most the preferred upper limit value, the positive electrode 10 is easily molded.

  The conductive auxiliary agent contained in the positive electrode 10 (hereinafter, the conductive auxiliary agent contained in the positive electrode 10 may be referred to as “positive electrode conductive auxiliary agent”) is not particularly limited, but it contains at least either graphite or carbon black. Is preferred.

The graphite used for the positive electrode conduction aid is not particularly limited, and examples thereof include artificial graphite.
Further, the graphite used for the positive electrode conduction aid preferably has a specific surface area of 240 m ² /g or more. Thus, the diffusion resistance in the positive electrode 10 is reduced by using graphite having a large specific surface area.
Further, the particle diameter (D50) of graphite used for the positive electrode conduction aid is preferably 10 μm or less. As described above, in particular, by using graphite having the above-mentioned specific surface area and particle diameter as the positive electrode conduction aid, it becomes possible to improve the conductivity and significantly improve the discharge characteristics.

  In the present invention, since graphite is contained in the positive electrode 10 as the conduction aid together with the positive electrode active material, the diffusion resistance in the positive electrode 10 is reduced by the action of the graphite having a relatively large specific surface area. As a result, the internal resistance is reduced, so that sufficient discharge characteristics can be ensured even in a small nonaqueous electrolyte secondary battery 1 that can supply a large current pulse in the region of approximately 1 mA to several mA.

  The content of graphite in the positive electrode 10 is not particularly limited, but the diffusion resistance in the positive electrode 10 can be effectively reduced to obtain sufficient conductivity, and the positive electrode 10 can be formed into a pellet form. From the viewpoint of improving the moldability at the time of molding, it 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 of easily obtaining a sufficient discharge capacity.

  In the present invention, carbon black may be contained as the positive electrode conduction aid 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 conduction aid, one of the above may be used alone, or two or more thereof 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, so that the discharge characteristic is conventionally reduced. It is possible to obtain more excellent discharge characteristics in a small non-aqueous electrolyte secondary battery having a relatively large discharge current, which is higher than that in.

  Even when carbon black is contained in the positive electrode 10 as the positive electrode conduction aid instead of graphite, the content is preferably in the same range as graphite. When the above carbon black is contained in addition to graphite as the positive electrode conduction aid in the positive electrode 10, the total content of the carbon blacks should be within the above range as in the case where graphite is contained alone. preferable.

The positive electrode 10 may include a binder (hereinafter, the binder used for the positive electrode 10 may be referred to as “positive electrode binder”).
As the positive electrode binder, a conventionally known substance can be used, and examples thereof include 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.
When polyacrylic acid is used for the positive electrode binder, it is preferable to adjust the pH of the polyacrylic acid to 3 to 10 in advance. 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.
The content of the positive electrode binder in the positive electrode 10 may be, for example, 1 to 20 mass %.

The size of the positive electrode 10 is determined according to the size of the non-aqueous 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 method of manufacturing the positive electrode 10, a method of mixing a positive electrode active material and a positive electrode conductive additive and, if necessary, a positive electrode binder to form a positive electrode mixture, and press-molding the positive electrode mixture into an arbitrary shape. Is mentioned.
The pressure at the time of pressure molding is determined in consideration of the kind of the positive electrode conductive additive, and can be set to, for example, 0.2 to 5 ton/cm ² .

  The positive electrode 10 included in the non-aqueous electrolyte secondary battery 1 of the present embodiment is electrically connected to the positive electrode current collector 14 having an uneven 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, the effect of reducing the internal resistance of the battery can be obtained.

  Further, in the non-aqueous electrolyte secondary battery 1 of the present invention, as shown in FIG. 1, it is preferable that at least a part of the positive electrode current collector 14 is embedded in the positive electrode 10. Here, as described in the present embodiment, "at least a part of the positive electrode current collector 14 is embedded in the positive electrode 10" means, for example, the positive electrode 10 and the positive electrode current collector 14 (positive electrode can 12). It means a state in which the flat portion 14a of the positive electrode current collector 14 is embedded and embedded in the pellet forming the positive electrode 10 by press contact.

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

  Further, in the non-aqueous electrolyte secondary battery 1 of the present invention, the positive electrode 10 is electrically connected to the positive electrode current collector 14 having an uneven structure, and the negative electrode 20 has a negative electrode current collector having an uneven structure, as described later. When the configuration electrically connected to 24 is adopted, the contact area between each electrode and each current collecting portion is increased, so that the contact resistance can be further 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 1 mA to several mA, sufficient discharge characteristics can be secured.

[Negative electrode]
The negative electrode 20 used in the present embodiment is not particularly limited, but for example, a negative electrode active material containing SiO _X (0≦X<2) whose surface is at least partially coated with carbon can be used. .. Further, as the negative electrode 20, in addition to the above-mentioned negative electrode active material, a mixture of a suitable binder, polyacrylic acid as a binder, and graphite or the like as a conductive additive can be used.

The negative electrode active material used for the negative electrode 20 is composed of SiO or SiO ₂ , that is, a silicon oxide represented by the above SiO _X (0≦X<2). By using the silicon oxide having the above composition as the negative electrode active material, the non-aqueous electrolyte secondary battery 1 can be used at high voltage and the cycle characteristics are improved.
In addition to the above-mentioned SiO _X (0≦X<2), the negative electrode 20 further includes carbon, an alloy-based negative electrode such as Li—Al, and at least one of Si, WO _2, and WO _3. Or may be contained.

By using the above-mentioned 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 the decrease in capacity can be prevented. In addition, the negative electrode active material made of SiO _X (0≦X<2) coated with carbon suppresses the decrease in conductivity even when the particles repeatedly swell and shrink due to charge and discharge. Thereby, the conductivity of the negative electrode 20 is maintained even when charging and discharging are repeated, so that an effect of improving cycle characteristics can be obtained.

Further, the negative electrode 20 has a structure 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. However, an increase in internal resistance in a low temperature environment is suppressed. As a result, the voltage drop at the initial stage of discharge can be suppressed, and the discharge characteristics can be further stabilized. The above negative electrode active material should have at least a part of the surface of the particles of SiO _X (0≦X<2) coated with carbon. Is preferable because it can be remarkably obtained.

In addition, in the present invention, when the non-aqueous electrolyte 50 has the above composition and the negative electrode 20 including the negative electrode active material made of SiO _X (0≦X<2) whose surface is coated with carbon is adopted, In particular, since the discharge characteristics under a low temperature environment of -30 to -40°C can be improved, it is possible to realize the non-aqueous electrolyte secondary battery 1 that can obtain excellent charge/discharge characteristics in a wide temperature range.

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

  When the above-mentioned material is used as the negative electrode active material, the particle diameter (D50) thereof is not particularly limited and is, for example, preferably 0.1 to 30 μm, more preferably 1 to 10 μm. When the particle diameter (D50) of the negative electrode active material is less than the lower limit of the above-mentioned preferred range, for example, the reactivity becomes high when the non-aqueous electrolyte secondary battery is exposed to high temperature, and thus it becomes difficult to handle. If it exceeds the upper limit, the discharge rate may decrease.

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

In the present embodiment, the negative electrode active material in the negative electrode 20, lithium (Li) and includes a _{SiO X (0 ≦ X <2} ), these molar ratio (Li / SiO _X) is 3.7 to It is more preferably in the range of 4.9. As described above, when the negative electrode active material is composed of lithium (Li) and SiO _X and the molar ratio of these is within the above range, the effect of preventing abnormal charging can be obtained. Further, even when the non-aqueous electrolyte secondary battery 1 is used or stored in a high temperature environment for a long period of time, the discharge capacity does not decrease and the storage characteristics are improved.

If the above molar ratio (Li/SiO _x ) is less than 3.7, the amount of Li is too small, and after use or storage for a long period of time in a high temperature environment, Li becomes insufficient and the discharge capacity decreases.
On the other hand, when the above molar ratio (Li/SiO _x ) exceeds 4.9, there is a possibility that abnormal charging may occur because the amount of Li is too large. Further, since the metal Li remains without being taken up by SiO _X , the resistance may increase and the discharge capacity may decrease.

Further, in the present embodiment, the molar ratio (Li/SiO _x ) in the above range is set by selecting a more appropriate range according to the kind of the positive electrode active material contained in the positive electrode 10. Is more preferable. For example, when lithium titanate is used as the positive electrode active material, the above molar ratio (Li/SiO _x ) in the negative electrode active material is more preferably in the range of 4.0 to 4.7. When lithium manganese oxide is used for the positive electrode active material, the above molar ratio (Li/SiO _x ) in the negative electrode active material is more preferably in the range of 3.9 to 4.9. In this way, by setting the molar ratio (Li/SiO _x ) of the negative electrode active material in a range according to the type of the positive electrode active material, the above-described increase in initial resistance is suppressed and charging abnormality or the like occurs. The effect that can be prevented, the discharge capacity does not decrease even after long-term use or storage in a high temperature environment, and the effect of improving storage characteristics can be more remarkably obtained.

The content of the negative electrode active material in the negative electrode 20 is determined in consideration of the discharge capacity required for the non-aqueous electrolyte secondary battery 1, and is, for example, 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 at least the lower limit value of the above preferred range, sufficient discharge capacity is easily obtained, and if it is at most the upper limit value, molding of the negative electrode 20 is performed. Will be easier.

  The negative electrode 20 may contain a conductive auxiliary agent (hereinafter, the conductive auxiliary agent used for the negative electrode 20 may be referred to as “negative electrode conductive auxiliary agent”). It is preferable that the negative electrode conduction aid contains at least one of graphite and carbon black, as in the case of the positive electrode conduction aid. Since 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, the negative electrode 20 contains graphite in the above range, like the positive electrode 10, so that the diffusion resistance in the negative electrode 20 is reduced. Therefore, similarly to the above, in the small-sized non-aqueous electrolyte secondary battery 1 having a large discharge current and a large discharge current as compared with the conventional case, more excellent discharge characteristics can be obtained.

The graphite used for the negative electrode conduction aid is not particularly limited, but as with the positive electrode conduction aid, for example, one having a specific surface area of 240 m ² /g or more is preferable. Similarly to the case of the positive electrode 10, the negative electrode 20 also contains graphite as a conductive additive in an amount of 20% by mass or more together with the negative electrode active material, so that the diffusion in the negative electrode 20 is caused by the action of the graphite having a large specific surface area. The resistance is reduced. As a result, the internal resistance is reduced, and in particular, a sufficient discharge is achieved 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 a higher discharge current than the conventional one. The effect of ensuring the characteristics can be obtained.

  The content of graphite 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 pellets. From the viewpoint of obtaining a sufficient discharge capacity, it is preferably 40% by mass or less.

  Further, as in the case of the positive electrode 10, the negative electrode 20 may also contain carbon black as a negative electrode conduction aid instead of the above graphite or together with the above graphite. As such carbon black, the same carbon black as that contained in the positive electrode 10 as a positive electrode conduction aid can be used.

Since the negative electrode 20 contains carbon black in addition to graphite, the effect of reducing the diffusion resistance in the negative electrode 20 can be more significantly obtained. When the above carbon black is contained in addition to graphite as the positive electrode conduction aid in the negative electrode 20, the total content thereof is preferably within the above range as in the case where graphite is contained alone.
Further, when carbon black is contained in the negative electrode 20 instead of graphite as the positive electrode conduction aid, the content is preferably in the same range as graphite.

  In the present invention, in addition to the positive electrode 10 containing an appropriate amount of at least one of graphite and carbon black as a positive electrode conduction aid, the negative electrode 20 also contains an appropriate amount of the above-mentioned negative electrode conduction aid. The effect of reducing the diffusion resistance in the electrode is more remarkably obtained. 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 approximately 1 mA to several mA and in which the discharge current is higher than in the conventional case. Become.

The negative electrode 20 may contain a binder (hereinafter, the binder used for the negative electrode 20 may be referred to as “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), polyamide imide (PAI), and the like. 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 of them may be used in combination. When polyacrylic acid is used as the negative electrode binder, it is preferable to adjust the pH of polyacrylic acid to 3 to 10 in advance. 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.
The content of the negative electrode binder in the negative electrode 20 is, for example, 1 to 20 mass %.

The size and thickness of the negative electrode 20 can be the same as the size and thickness of the positive electrode 10.
In the non-aqueous electrolyte secondary battery 1 shown in FIG. 1, 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 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 press-molding this negative electrode mixture into an arbitrary shape can be adopted.
The pressure at the time of pressure molding in this case is determined in consideration of the type of the negative electrode conductive additive, and can be, 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 provided in the negative electrode 20. It is preferred that the part is embedded. In this way, 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 significantly increased, and the contact resistance is significantly reduced. Therefore, the effect of significantly reducing the internal resistance can be expected.

  In the present invention, as described above, the configuration in which both the positive electrode 10 and the negative electrode 20 are electrically connected to the current collectors (positive electrode current collector 14, negative electrode current collector 24) having the 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 1 mA to several mA, sufficient discharge characteristics can be secured.

[Separator]
The separator 30 is an insulating film that is interposed between the positive electrode 10 and the negative electrode 20, has a large ion permeability, is excellent in heat resistance, and has a predetermined mechanical strength.
As the separator 30, a separator that is conventionally used for a non-aqueous electrolyte secondary battery and that is made of a material satisfying the above characteristics can be applied without any limitation, and examples thereof include alkali glass, borosilicate glass, quartz glass, and lead glass. Non-woven fabrics made of resins such as glass, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyethylene terephthalate (PET), polyamide imide (PAI), polyamide, polyimide (PI), aramid, cellulose, fluororesin and ceramics Fiber etc. are mentioned. Among the above, as the separator 30, it is more preferable to use a nonwoven fabric made of glass fiber. Since glass fiber has excellent mechanical strength and high ion permeability, it is possible to reduce the internal resistance and improve the discharge capacity.
The thickness of the separator 30 is determined in consideration of the size of the non-aqueous electrolyte secondary battery 1, the material of the separator 30, and the like, and may be, for example, about 5 to 300 μm.

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

  Then, in the manufacturing method according to the present invention, the storage 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 to form a flat portion 14a. The method includes forming the positive electrode current collector 14 having the concave-convex structure including the concave portion 14b and the negative electrode current collector 24 having the concave-convex structure including the flat portion 24a and the concave portion 24b.

  In the method for manufacturing the non-aqueous electrolyte secondary battery 1 according to the present invention, the storage container forming step is a method for forming the positive electrode current collector 14 and the negative electrode current collector 24 having the above-mentioned concavo-convex structure. Except for the points included, almost the same conditions and procedures as in the past can be adopted.

[Storage container forming process]
In the storage container forming step, first, a metal plate material made of the above-mentioned stainless steel or a clad material made of a plurality of metals is used to press-mold the plate material to thereby obtain a storage container as shown in FIG. A molded product of a bottomed cylindrical positive electrode can 12 having an opening 12a and a capped cylindrical negative electrode can 22 constituting No. 2 is obtained.

  Next, the inner bottom surface of the positive electrode can 12 and the inner lid surface of the negative electrode can 22 are subjected to etching treatment, so that the positive electrode current collector 14 having the uneven structure including the flat portion 14a and the concave portion 14b is formed on the positive electrode can 12. Then, the negative electrode current collector 24 having the concavo-convex structure including the flat portion 24a and the concave portion 24b is formed on the negative electrode can 22.

  Specifically, first, masking is performed on the inner bottom surface of the positive electrode can 12 and the inner lid surface of the negative electrode can 22 in regions where the concave-convex structure is to be formed by etching. 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 the desired plan view shape of the uneven structure.

  Then, 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 are subjected to etching treatment. The etching method at this time is not particularly limited, and general wet etching or dry etching can be adopted, and further, a method by sandblast can also be adopted. On the other hand, from the viewpoint of workability with respect to metal materials, it is preferable to adopt a method of wet etching using an etching solution for etching the inner surfaces of the positive electrode can 12 and the negative electrode can 22.

  The etching solution used for the wet etching is not particularly limited, but can be selected in consideration of the material of the metal plate material used for the positive electrode can 12 and the negative electrode can 22, and the etching solution exemplified below includes the positive electrode can 12 and An etching process is performed by immersing the negative electrode can 22.

  Here, for example, when a metal plate made of stainless steel is used for the positive electrode can 12 and the negative electrode can 22 and stainless steel is etched, an aqueous solution of ferric chloride or an aqueous solution of cupric chloride having a strong oxidizing power is used as an etching solution. Alternatively, it is preferable to use sulfuric acid 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 material made of a clad material in which the outer surface side is a stainless steel material and the inner surface side is an aluminum material, 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, etc. Any of an aqueous solution, an aqueous solution of sodium hydroxide, a ferric chloride solution, an aqueous solution of sodium phosphate, dilute nitric acid and the like can be used. Further, these etching solutions may contain halogen ions at a predetermined concentration, if necessary, for the purpose of removing the oxide film existing on the surface of the aluminum material.

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

  In the method described in the present 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 thereof to form the recesses 14b and 24b. The etching treatment time is not particularly limited, and can be set in consideration of the plan view shape of each current collector to be formed, the depth of the recess, and the like. The same applies to the temperature of the etching solution during the etching process, and may be set appropriately.

  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. As a result, the positive electrode can 12 and the negative electrode can 22 in which the current collector having the uneven structure is formed on the inner bottom surface or the inner lid surface are obtained.

  The outer surfaces of the positive electrode can 12 and the negative electrode can 22 are subjected to surface treatment such as Ni plating, if necessary.

  In the present embodiment, the concave-convex processing is facilitated by etching the inner surface side on which the metal material having low hardness in the clad material is arranged. Therefore, it becomes possible to form the positive electrode current collector 14 and the negative electrode current collector 24 having the uneven structure as described above in a plan view 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 formed of the positive electrode can 12 and the negative electrode can 22 obtained in the storage container forming process. The non-aqueous electrolyte secondary battery 1 is assembled by accommodating the separator 30 arranged between the two and the non-aqueous electrolyte 50 containing at least a supporting salt and an organic solvent (the cross section of the non-aqueous electrolyte secondary battery 1 in FIG. 1). See figure).

  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, which are made of various materials as described above, are prepared.

Next, on the positive electrode current collector 14 in the positive electrode can 12 obtained in the storage container forming step, the positive electrode 10 made of pellets containing a positive electrode active material is used, for example, a conductive resin adhesive containing carbon is used. The positive electrode unit is assembled by gluing 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 a conductive resin adhesive, the positive electrode current collector 14 is pressed against the positive electrode current collector 14 to form a positive electrode on the uneven structure of the positive electrode current collector 14. 10 is integrated so as to bite into it to form a positive electrode unit.
Then, this positive electrode unit is dried under reduced pressure under high temperature conditions, and then a sealant is applied to the inner surface of the opening of the positive electrode can.

In addition, the negative electrode unit is assembled according to 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 was used, and a conductive resin adhesive containing carbon as a conductive filler was used. These are integrated by bonding with each other. Specifically, as in the case of the positive electrode unit, 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, and then the two are pressed to contact each other, so that the negative electrode current collector is pressed. The negative electrode 20 is integrated so as to bite into the uneven structure of the portion 24 to form a negative electrode unit.
Next, this negative electrode unit is dried under reduced pressure under high temperature conditions, and then a lithium foil 60 is pressure-bonded onto the negative electrode 20 to form a lithium-negative electrode laminated electrode, which is dried under reduced pressure under high temperature conditions.
Next, the separator 30 is laminated on the lithium foil 60.
Then, the gasket 40 is attached to the opening of the negative electrode can 22 to manufacture the negative electrode unit. At this time, the tip portion 22a 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 non-aqueous 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 housed in the negative electrode can 22 is inserted into the opening 12 a of the positive electrode can 12.
Next, by crimping the periphery of the opening 12a of the positive electrode can 12 to the inside, that is, the negative electrode can 22 side, and fitting them together, the gasket 40 is compressed and the space covered by the positive electrode can 12 and the negative electrode can 22 is sealed. To do.
By the procedure as described above, the non-aqueous electrolyte secondary battery 1 of the present embodiment, which is small and is coin-shaped (button-shaped) 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 etching to process the positive and negative electrode current collectors 14 and the negative electrode current collector. By forming 24, it is possible to form each of these current collecting portions in a concavo-convex structure with a fine pattern without producing processed pieces or the like. As a result, a small non-aqueous electrolyte secondary battery 1 having a significantly reduced internal resistance of the battery and capable of supplying a large current pulse in the region of 1 mA or more and having excellent discharge characteristics, in which processed pieces and the like remain It becomes possible to manufacture with good yield without performing.

  In addition, since the manufacturing method according to the present invention is a method of forming each current collecting portion having an uneven 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 is not formed. Since the uneven shape does not occur, the non-aqueous electrolyte secondary battery 1 having excellent appearance characteristics can be manufactured.

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

<Use of non-aqueous electrolyte secondary battery>
As described above, the non-aqueous electrolyte secondary battery 1 of the present embodiment has extremely excellent discharge characteristics, particularly when a small coin cell or the like capable of supplying a large current pulse in a region of about 1 mA to several mA is configured. Therefore, it is suitable for use as a backup power source for semiconductor memories and a backup power source for the real-time clock function in various small electronic devices such as mobile phones, PDAs, portable game machines, and digital cameras.

<Effect>
As described above, according to the non-aqueous electrolyte secondary battery 1 of the present invention, the positive electrode can 12 and the negative electrode can 22 are integrated with 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 is increased, and the contact resistance between them is reduced.
As a result, the internal resistance can be remarkably reduced, and particularly in a small non-aqueous electrolyte secondary battery capable of supplying a large current pulse in the region of 1 mA to several mA, a state in which sufficient discharge current and voltage are maintained. Discharge for a long time and excellent discharge characteristics can be obtained. In addition, the positive electrode can 12 and the negative electrode can 22 are provided with a current collecting portion having an uneven structure on the inner surface side, and no uneven shape is formed on the outer surface side. Therefore, excellent appearance characteristics can be obtained, and a processed piece or the like is not produced during manufacturing. It does not occur, and the yield is excellent.
Therefore, the yield of the non-aqueous electrolyte secondary battery 1 capable of sufficiently satisfying the discharge characteristics required in various small electronic devices to which the small non-aqueous electrolyte secondary battery such as a coin type is applied and improving the device characteristics is improved. It will be possible to provide.

Further, according to the method for manufacturing the non-aqueous 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 subjected to etching treatment to collect the positive electrode having the uneven structure. Since the current collecting portion 14 and the negative electrode current collecting portion 24 are formed, it is possible to form the current collecting portion with a finely patterned concavo-convex structure without producing a processed piece or the like.
Therefore, in particular, a small-sized non-aqueous 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 remarkably reduced, is manufactured with high yield. It will be possible.

  Next, the present invention will be described more specifically by showing Examples and Comparative Examples. Note that the scope of the present invention is not limited by the present embodiment, and the non-aqueous electrolyte secondary battery according to the present invention can be appropriately modified and implemented within a range not changing the gist of the present invention. is there.

<Preparation of non-aqueous electrolyte secondary battery>
[Example]
In the examples, the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can are each formed with a current collector having a concavo-convex structure, and a coin-type non-aqueous electrolyte secondary battery that is an electrochemical cell is produced. The discharge characteristics were measured (see non-aqueous electrolyte secondary battery 1 in FIG. 1).

That is, in the examples, first, a non-aqueous electrolyte having the following composition was _prepared , and further, Li _1.14 Co _0.06 Mn _1.80 O ₄ was used as the positive electrode active material, and carbon was used on the entire surface as the negative electrode active material. A non-aqueous electrolyte secondary battery was produced 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.

(Preparation of storage container)
As a storage container, as shown in FIG. 1, a positive electrode can and a negative electrode can having a current collecting portion having an uneven structure on the inner surface side were produced.
First, as a material for the positive electrode can, a metal plate material made of stainless steel (SUS329J4L: t=0.20 mm) was prepared, and this was pressed to form a bottomed plate having an opening as shown in FIG. A cylindrical positive electrode can was molded.
Further, as a material for the negative electrode can, a metal plate material made of stainless steel (SUS304-BA: t=0.20 mm) was prepared, and this was pressed to form a cylindrical negative electrode with a lid as shown in FIG. The 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 a photolithography method, and a wet etching process is performed to form a grid pattern in plan view as shown in FIG. 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 photolithography to the areas where the concave-convex structure was to be formed on the inner surfaces of the positive electrode can and the negative electrode can.
Then, using an aqueous ferric chloride solution having a concentration of 35% by mass as an etching solution, the temperature of the etching solution was set to 65° C., and the positive electrode can and the negative electrode can were immersed for 10 min to obtain the inner bottom surface and the inner lid surface of each. Was etched.
After that, the resist material was removed and washed.

  By such conditions and procedures, a positive electrode having an inner bottom surface and an inner lid surface, as shown in FIG. 2, having a concavo-convex structure having flat portions and concave portions and having a planar view shape in which the concave portions are arranged in a grid pattern. A can and a negative electrode can were obtained. The concave portions formed at this time were rectangular in plan view with a width W2 of 1.5 mm in the vertical and horizontal directions, and the flat portions were in a lattice shape having a width W1 of 0.3 mm and extending in a plurality of rows in the vertical and horizontal directions. Further, the average depth D of the concave portions was 0.10 mm, and the ratio of the flat portion to the area of each current collecting portion was 28%.

(Adjustment of non-aqueous electrolyte)
First, an organic solvent was prepared according to the following blending ratio (volume %), and a supporting salt was dissolved in this organic solvent to prepare a non-aqueous electrolyte. At this time, as an organic solvent, propylene carbonate (PC), ethylene carbonate (EC), and dimethoxyethane (DME) are mixed in a volume ratio of {PC:EC:DME}={1:1:2}. By doing so, 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 each had a molar concentration of 1 mol/L.

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

Next, the obtained pellet (positive electrode) is adhered 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 Then, this positive electrode unit was dried under reduced pressure in the air at 120° C. for 11 hours.
Then, a sealant was applied to the inner surface of the opening of the positive electrode can in the positive electrode unit.

Next, as a negative electrode, first, a SiO powder having carbon (C) formed on the entire surface was prepared and used as a negative electrode active material. Then, 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 was used as a conduction aid, and polyacrylic acid was used as a binder, and 75: The mixture was mixed at a ratio of 20:5 (mass ratio) to obtain a negative electrode mixture.
Next, 15.1 mg of the obtained negative electrode mixture was pressure-molded with a pressing force of ² ton/cm ² , and was pressure-molded into a disk-shaped pellet having a diameter of 6.7 mm.

Next, the obtained pellet (negative electrode) is adhered 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. Then, this negative electrode unit was dried under reduced pressure in the atmosphere at 160° C. for 11 hours.
Then, a lithium foil punched to have a diameter of 6.1 mm and a thickness of 0.38 mm was 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 out into a disk shape having a diameter of 7 mm to obtain a separator. Then, this separator was placed on a lithium foil pressure-bonded onto the negative electrode, and a polypropylene gasket was placed in the opening of the negative electrode can.

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

  Next, the negative electrode unit was caulked to the positive electrode unit so that the separator was in contact with the positive electrode. Then, the positive electrode can and the negative electrode can were sealed by fitting the opening of the positive electrode can and then allowed to stand at 25° C. for 7 days to obtain a non-aqueous electrolyte secondary battery as shown in Table 1 below. It was

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

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

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

[Evaluation results]
First, as in the examples shown in Table 1, the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can were provided with a current collecting portion having a concavo-convex structure including a flat portion and a concave portion, and each electrode By adopting a configuration in which the current collector and each current collector are electrically connected, the internal resistance is greatly reduced and the discharge characteristics are improved compared to the comparative example in which the current collector is flat. I understand.

  In addition, in the examples, since the uneven structure provided on the inner bottom surface of the positive electrode can and the inner lid surface of the negative electrode can are formed by the etching treatment, no work pieces are generated in the process, and the battery is There were no problems such as short-circuiting of the battery due to the remaining processed pieces inside, or incomplete fixing state due to the processed pieces interposed between each electrode and each current collector.

  From the results of the examples described above, as defined in claim 1 of the present invention, a current collector having an uneven structure including 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 collecting portion are electrically connected, a large current pulse in a region of about 1 mA to several mA can be supplied, as compared with the conventional case. It is clear that excellent discharge characteristics can be obtained when a small non-aqueous electrolyte secondary battery with 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 is a small-sized non-aqueous electrolyte secondary battery having an increased discharge current compared to the conventional one. In this case, excellent discharge characteristics can be obtained. Therefore, the non-aqueous electrolyte secondary battery of the present invention is used in various small electronic devices such as mobile phones, PDAs, portable game machines, and digital cameras, as a backup power source for semiconductor memories and a backup power source for the real-time clock function. It is preferably used for.

DESCRIPTION OF SYMBOLS 1... Non-aqueous electrolyte secondary battery 2... Storage container 12... Positive electrode can 12a... Opening 14... Positive electrode current collector (inner bottom surface of positive electrode can),
14a... Flat part 14b... Recessed part 22... Negative electrode can 22a... Tip part 24... Negative electrode current collecting part (inner lid surface of negative electrode can),
24a... Flat part 24b... Recessed part 10... Positive electrode 20... Negative electrode 25... Conductive adhesive 30... Separator 40... Gasket 41... Annular groove 50... Nonaqueous electrolyte 60... Lithium foil

Claims (10)

A positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, a separator arranged between the positive electrode and the negative electrode, and a non-aqueous electrolyte containing 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 capped cylindrical negative electrode can forming 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 collecting portion electrically connected to the positive electrode or the negative electrode,
The current collector may have a concave-convex structure composed of a flat portion and a recess provided in said bottom surface and said inner lid surface, and the proportion of the flat portion to the area of the current collector is 10% to 50% non-aqueous electrolyte secondary battery which is characterized in der Rukoto. The non-aqueous electrolyte secondary battery according to claim 1, wherein at least a part of the current collector included in the positive electrode can or the negative electrode can is embedded in the positive electrode and the negative electrode. The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the positive electrode can and the negative electrode can are made of stainless steel. The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the positive electrode can and the negative electrode can are made of a clad material having an outer surface made of stainless steel and an inner surface made of aluminum, nickel, or copper. The planar view shape of the said current collection part is made into the grid shape which consists of the said flat part and the said recessed part, or the ring shape, The non-claim according to any one of claims 1 to 4. Water electrolyte secondary battery. The nonaqueous electrolyte secondary battery according to any one of claims 1 to 5 , wherein the positive electrode and the negative electrode contain at least one of graphite and/or carbon black as a conduction aid. The non-aqueous electrolyte secondary battery according to any one of claims 1 to 6 , wherein the non-aqueous electrolyte contains at least lithium bis(fluorosulfonyl)imide (LiFSI) as a supporting salt. The content of lithium bis included as a supporting salt (fluorosulfonyl) imide (LiFSI) is according to claim 7, wherein in the range of 10 to 23 wt% based on the total amount of the nonaqueous 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:. 0.5-1.5:1-3} is contained in the range, The non-aqueous electrolyte secondary battery in any one of the Claims 1-8 characterized by the above-mentioned. By processing a metal plate material to form a bottomed cylindrical positive electrode can and an open cylindrical negative electrode can having an opening, and a storage container forming step for obtaining a storage container composed of the positive electrode can and the negative electrode can. The storage container includes a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, a separator disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte containing at least a supporting salt and an organic solvent. A method of manufacturing a non-aqueous electrolyte secondary battery, comprising:
In the storage container forming step, by selectively removing at least a part of an inner bottom surface of the positive electrode can and an inner lid surface of the negative electrode can by an etching process, a current collecting portion having a concavo-convex structure including a flat portion and a concave portion. look including a process of forming a and method for producing a nonaqueous electrolyte secondary battery, and forming the current collecting portion the ratio of the flat portion to the area of the current collector as 10-50%.

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