JP2016178027A - Power storage device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device which is easy to manufacture while ensuring its capacity and output.SOLUTION: A power storage device comprises a negative electrode having a negative electrode active material layer including a hardly graphitizable carbon. The true specific weight of the hardly graphitizable carbon is 1.55-1.70 g/cm3, and the average particle diameter of the hardly graphitizable carbon is 6 μm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power storage element and a method for manufacturing the power storage element.

  Conventionally, an electricity storage element in which an electrode body having a positive electrode and a negative electrode is accommodated in a case has been used. As an electrical storage element, the thing using non-graphitizable carbon as a negative electrode active material is known (refer the following patent document 1).

JP 2002-279971 A

  This type of power storage element is required to improve output and capacity. Non-graphitizable carbon is easily oxidized unless stored in a dry environment. When the non-graphitizable carbon that is the negative electrode active material is oxidized, it is difficult to ensure a sufficient capacity of the power storage element. Therefore, in order to secure a sufficient capacity for the power storage element, it is desirable to quickly assemble the power storage element by accommodating the produced negative electrode in the case. The storage period of the negative electrode until it is used for assembling the power storage element can be shortened if the amount of the negative electrode manufactured at one time is reduced. However, when the amount of the negative electrode manufactured at one time is reduced, the negative electrode is frequently manufactured. In that case, it is difficult to efficiently manufacture the power storage element.

  An object of this invention is to provide the electrical storage element which can be manufactured efficiently, ensuring output and a capacity | capacitance.

The electricity storage device of the present invention,
Comprising a negative electrode having a negative electrode active material layer containing non-graphitizable carbon,
The true specific gravity of the non-graphitizable carbon is 1.55 g / cm ³ or more and 1.70 g / cm ³ or less, and the average particle size of the non-graphitizable carbon is 6 μm or less.

The method for producing the electricity storage device of the present invention comprises:
Producing a negative electrode having a negative electrode active material layer comprising non-graphitizable carbon,
For forming the negative electrode active material layer, non-graphitizable carbon having a true specific gravity of 1.55 g / cm ³ or more and 1.70 g / cm ³ or less and an average particle diameter of 6 μm or less is used.

The power storage element can improve output by containing non-graphitizable carbon having an average particle diameter of 6 μm or less in the negative electrode active material layer. Non-graphitizable carbon having a true specific gravity of 1.55 g / cm ³ or more and 1.70 g / cm ³ or less is unlikely to be oxidized due to the influence of humidity. Therefore, a negative electrode including such non-graphitizable carbon in the negative electrode active material layer causes a reduction in capacity of the power storage element even if the storage period from manufacture to storage in the case is longer than before. Hateful. Therefore, this power storage element can be efficiently manufactured while ensuring output and capacity.

The manufacturing method of the storage element is as follows:
Including assembling a storage element by housing the negative electrode in a case;
It may further include placing the negative electrode in an environment having a dew point temperature of −20 ° C. or higher before accommodating the negative electrode in the case.

  In such a method for manufacturing a power storage device, it is possible to suppress the storage environment of the negative electrode from being limited. Therefore, in such a method for manufacturing a power storage element, the power storage element can be manufactured more efficiently.

The manufacturing method of the storage element is as follows:
Including assembling a storage element by housing the negative electrode in a case;
It may further include placing the negative electrode in an environment having a dew point temperature of −35 ° C. or lower for 3 days or longer before accommodating the negative electrode in the case.

  In such a method for manufacturing a power storage element, the storage period of the negative electrode can be secured for 3 days or more, so that the power storage element can be manufactured more efficiently.

  ADVANTAGE OF THE INVENTION According to this invention, the electrical storage element which can be manufactured efficiently can be provided, ensuring an output and a capacity | capacitance.

FIG. 1 is a perspective view of a power storage device according to an embodiment of the present invention. 2 is a cross-sectional view taken along the line II-II in FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is an exploded view of the energy storage device according to the embodiment. FIG. 5 is a perspective view of a state in which a part of the energy storage device according to the embodiment is assembled, and is a perspective view of a state in which a liquid filling tap, an electrode body, a current collector, and a terminal portion are assembled to a cover plate. is there. FIG. 6 is a view for explaining the configuration of the electrode body of the energy storage device according to the embodiment. FIG. 7 is a diagram illustrating a flow according to the method for manufacturing the power storage element. FIG. 8 is a diagram illustrating a flow according to the method for manufacturing the power storage element. FIG. 9 is a diagram illustrating a flow according to the method for manufacturing the power storage element. FIG. 10 is a diagram illustrating a flow according to the method for manufacturing the power storage element.

Hereinafter, an embodiment of a power storage device according to the present invention will be described with reference to FIGS.
Examples of the power storage element include a primary battery, a secondary battery, and a capacitor. In the present embodiment, a chargeable / dischargeable secondary battery will be described as an example of a power storage element. In addition, the name of each component (each component) of this embodiment is a thing in this embodiment, and may differ from the name of each component (each component) in background art.

  The electricity storage device of this embodiment is a nonaqueous electrolyte secondary battery. More specifically, the power storage element is a lithium ion secondary battery that utilizes electron transfer that occurs as lithium ions move. This type of power storage element supplies electrical energy. One or a plurality of power storage elements are used. Specifically, the storage element is used singly when the required output and the required voltage are small. On the other hand, when at least one of a required output and a required voltage is large, the power storage element is used in a power storage device in combination with another power storage element. In the power storage device, a power storage element used in the power storage device supplies electric energy.

  As shown in FIGS. 1 to 6, the storage element includes an electrode body 2 including a positive electrode 23 and a negative electrode 24, a case 3 that houses the electrode body 2, and an external terminal 4 that is disposed outside the case 3. And an external terminal 4 electrically connected to the electrode body 2. In addition to the electrode body 2, the case 3, and the external terminal 4, the power storage element 1 includes a current collector 5 that electrically connects the electrode body 2 and the external terminal 4.

  The electrode body 2 is formed by winding a laminated body 22 in which the positive electrode 23 and the negative electrode 24 are laminated in a state of being insulated from each other.

  The positive electrode 23 has a metal foil and a positive electrode active material layer formed on the metal foil. The metal foil is strip-shaped. The metal foil of this embodiment is an aluminum foil, for example. The positive electrode 23 has a non-covered portion (a portion where the positive electrode active material layer is not formed) 231 of the positive electrode active material layer at one edge portion in the width direction that is the short direction of the band shape. A portion of the positive electrode 23 where the positive electrode active material layer is formed is referred to as a covering portion 232.

  The positive electrode active material layer includes a positive electrode active material and a binder.

The positive electrode active material is, for example, a lithium metal oxide. Specifically, the positive electrode active material is, for example, _a composite oxide (Li _a Co _y O ₂ , Li _a Ni _x ) represented by Li _a Me _b O _c (Me represents one or more transition metals). O ₂ , Li _a Mn _z O ₄ , Li _a Ni _x Co _y Mn _z O _2, etc.), Li _a Me _b (XO _c ) _d (Me represents one or more transition metals, and X represents, for example, P , Si, B, a polyanion compounds represented by the representative of the _{V) (Li a Fe b PO} 4, Li a Mn b PO 4, Li a Mn b SiO 4, Li a Co b PO 4 F , etc.). The positive electrode active material of this embodiment is LiNi _1/3 Co _1/3 Mn _1/3 O ₂ .

  Examples of the binder used in the positive electrode active material layer include polyvinylidene fluoride (PVdF), a copolymer of ethylene and vinyl alcohol, polymethyl methacrylate, polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyacrylic acid, and polymethacrylic acid. Styrene butadiene rubber (SBR). The binder of this embodiment is polyvinylidene fluoride.

  The positive electrode active material layer may further include a conductive additive such as ketjen black (registered trademark), acetylene black, or graphite. The positive electrode active material layer of this embodiment has acetylene black as a conductive additive.

  The negative electrode 24 has a metal foil and a negative electrode active material layer formed on the metal foil. The metal foil is strip-shaped. The metal foil of this embodiment is a copper foil, for example. The negative electrode 24 has a non-covered portion (negative electrode active material layer) of the negative electrode active material layer formed on the other edge portion in the width direction that is the short direction of the belt shape (on the side opposite to the non-covered portion 231 of the positive electrode 23). 241). The width of the covering portion (the portion where the negative electrode active material layer is formed) 242 of the negative electrode 24 is larger than the width of the covering portion 232 of the positive electrode 23.

  The negative electrode active material layer includes a negative electrode active material and a binder.

  The negative electrode active material is, for example, a material that causes an alloying reaction with carbon materials such as graphite, non-graphitizable carbon, and graphitizable carbon, or lithium ions such as silicon (Si) and tin (Sn). The negative electrode active material of this embodiment is non-graphitizable carbon.

The true specific gravity of the non-graphitizable carbon of this embodiment is 1.55 g / cm ³ or more and 1.70 g / cm ³ or less. The true specific gravity of non-graphitizable carbon can be measured based on JIS R7222: 1997 “Method for measuring physical properties of graphite material”. True specific gravity of the non-graphitizable carbon may be at 1.56 g / cm ³ or more 1.68 g / cm ³ or less, or may be 1.62 g / cm ³ or more 1.66 g / cm ³ or less. The average particle diameter (D50) of the non-graphitizable carbon of this embodiment is 6 μm or less. The average particle diameter (D50) of the non-graphitizable carbon may be 1 μm or more. Preferably, the average particle diameter (D50) of the non-graphitizable carbon is 2 μm or more and 4 μm or less.

  The average particle diameter of the hardly graphitized carbon can be measured by a laser diffraction scattering method. The average particle size means a particle size having a cumulative degree of 50% (D50) in a volume standard particle size distribution. Specifically, a laser diffraction type particle size distribution measuring device (Microtrack Bell Co., Ltd. MT3000EXII) is used as a measuring device, and Microtrack dedicated application software DMS (ver. 2) is used as measurement control software. As a specific measurement method, a scattering type measurement mode was adopted, and a wet cell in which a dispersion liquid in which a measurement target sample (non-graphitizable carbon) was dispersed in a dispersion solvent was placed in an ultrasonic environment for 2 minutes. Later, laser light is irradiated to obtain a scattered light distribution from the measurement sample. Then, the scattered light distribution is approximated by a lognormal distribution, and in the particle size distribution (horizontal axis, σ), the particle size corresponding to a cumulative degree of 50% (D50) is set in a range where the minimum is set to 0.021 μm and the maximum is set to 2000 μm. Average particle diameter. The dispersion also contains a surfactant and SN Dispersant 7347-C or Triton X-100 (registered trademark) as a dispersant. A few drops of dispersant are added to the dispersion. When the sample floats, SN wet 366 is added as a wetting material.

  The binder used for the negative electrode active material layer is the same as the binder used for the positive electrode active material layer. The binder of this embodiment is polyvinylidene fluoride.

  In the electrode body 2 of the present embodiment, the positive electrode 23 and the negative electrode 24 configured as described above are wound in a state where they are insulated by the separator 25. That is, in the electrode body 2 of the present embodiment, the laminated body 22 of the positive electrode 23, the negative electrode 24, and the separator 25 is wound. The separator 25 is an insulating member. The separator 25 is disposed between the positive electrode 23 and the negative electrode 24. Thereby, in the electrode body 2 (specifically, the laminated body 22), the positive electrode 23 and the negative electrode 24 are insulated from each other. The separator 25 holds the electrolytic solution in the case 3. Thereby, at the time of charging / discharging of the electrical storage element 1, lithium ion moves between the positive electrode 23 and the negative electrode 24 which are laminated | stacked alternately on both sides of the separator 25. FIG.

The separator 25 has a strip shape. Separator 25 is constituted by porous films, such as polyethylene, polypropylene, cellulose, polyamide, for example. The separator 25 is formed by providing an inorganic layer containing inorganic particles such as SiO ₂ particles, Al ₂ O ₃ particles, boehmite (alumina hydrate) on a substrate formed of a porous film. Also good. The separator 25 of the present embodiment is made of polyethylene, for example. The width of the separator (the dimension of the strip shape in the short direction) is slightly larger than the width of the covering portion 242 of the negative electrode 24. The separator 25 is disposed between the positive electrode 23 and the negative electrode 24 that are overlapped with each other so that the covering portions 232 are overlapped with each other in the width direction. At this time, the non-covered portion 231 of the positive electrode 23 and the non-covered portion 241 of the negative electrode 24 do not overlap. That is, the non-covered portion 231 of the positive electrode 23 protrudes in the width direction from the region where the positive electrode 23 and the negative electrode 24 overlap, and the non-covered portion 241 of the negative electrode 24 extends from the region where the positive electrode 23 and the negative electrode 24 overlap in the width direction ( It protrudes in a direction opposite to the protruding direction of the non-covered portion 231 of the positive electrode 23. The electrode body 2 is formed by winding the stacked positive electrode 23, negative electrode 24, and separator 25, that is, the stacked body 22. The portion where only the uncovered portion 231 of the positive electrode 23 or the uncovered portion 241 of the negative electrode 24 is stacked constitutes the uncovered stacked portion 26 in the electrode body 2.

  The uncoated laminated portion 26 is a portion that is electrically connected to the current collector 5 in the electrode body 2. The uncoated laminated portion 26 of the present embodiment is divided into two parts (divided into two parts) with the hollow portion 27 (see FIG. 2) sandwiched between the wound positive electrode 23, negative electrode 24, and separator 25 in the winding center direction. Uncovered laminated portion) 261.

  The uncoated laminated portion 26 configured as described above is provided on each electrode of the electrode body 2. That is, the non-coated laminated portion 26 in which only the non-coated portion 231 of the positive electrode 23 is laminated constitutes the non-coated laminated portion of the positive electrode in the electrode body 2, and the non-coated laminated portion in which only the non-coated portion 241 of the negative electrode 24 is laminated. 26 constitutes an uncoated laminated portion of the negative electrode in the electrode body 2.

  The case 3 includes a case main body 31 having an opening and a cover plate 32 that closes (closes) the opening of the case main body 31. The case 3 houses the electrolytic solution in the internal space 33 together with the electrode body 2 and the current collector 5. Case 3 is formed of a metal having resistance to the electrolytic solution. The case 3 of the present embodiment is formed of an aluminum metal material such as aluminum or an aluminum alloy, for example. The case 3 may be formed of a metal material such as stainless steel and nickel, or a composite material obtained by bonding a resin such as nylon to aluminum.

The electrolytic solution is a non-aqueous electrolytic solution. The electrolytic solution is obtained by dissolving an electrolyte salt in an organic solvent. Examples of the organic solvent include cyclic carbonates such as propylene carbonate and ethylene carbonate, and chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. The electrolyte salt is LiClO ₄ , LiBF ₄ , LiPF ₆ or the like. The electrolyte solution of this embodiment is prepared by mixing 1 mol / L LiPF ₆ in a mixed solvent in which propylene carbonate, dimethyl carbonate, and ethyl methyl carbonate are adjusted at a ratio of propylene carbonate: dimethyl carbonate: ethyl methyl carbonate = 3: 2: 5. Is dissolved.

  The case 3 is formed by joining the opening peripheral edge 34 of the case main body 31 and the peripheral edge of the cover plate 32 in an overlapped state. The case 3 has an internal space 33 defined by the case main body 31 and the lid plate 32. In this embodiment, the opening peripheral part 34 of the case main body 31 and the peripheral part of the cover plate 32 are joined by welding. In the present embodiment, welding is performed between the opening peripheral edge 34 of the case main body 31 and the peripheral edge of the lid plate 32 in a state where the electrode body 2 and the current collector 5 are accommodated in the internal space 33.

  The negative electrode 24 of the present embodiment includes non-graphitizable carbon that is hardly affected by humidity as a negative electrode active material. Non-graphitizable carbon having a high true specific gravity is unlikely to oxidize even in an environment where the dew point temperature is −20 ° C. or higher. If the environment has a lower dew point temperature, the oxidation of non-graphitizable carbon can be further suppressed. Therefore, the negative electrode 24 can be placed in an environment with such a dew point temperature for a certain period from the time of manufacture.

  Therefore, the negative electrode 24 can be stored in an environment having a dew point temperature of −20 ° C. or higher before being housed in the case 3 as a constituent member of the electrode body 2. The dew point temperature of the environment where the negative electrode 24 is stored may be 10 ° C. or less. Preferably, the dew point temperature of the environment where the negative electrode 24 is stored is −10 ° C. or lower. The negative electrode 24 placed in such an environment may be in a single state where the laminate 22 is not formed, or may be in the state of the electrode body 2, and the negative electrode active material layer before the negative electrode active material layer is formed. The state of the substance alone may be used. Preferably, the negative electrode 24 is placed in an environment where the dew point temperature is −20 ° C. or higher from when the negative electrode active material layer is manufactured to when the negative electrode 24 is accommodated in the case 3.

  The negative electrode 24 can be placed in an environment having a dew point temperature of −35 ° C. or lower for 3 days or more before being housed in the case 3 as a constituent member of the electrode body 2. The negative electrode 24 may be placed in an environment having a dew point temperature of −35 ° C. or lower for 5 days or more, or may be placed for 7 days or more. The dew point temperature of the environment where the negative electrode 24 is placed may be −50 ° C. or higher. The period during which the negative electrode 24 is placed in an environment with a dew point temperature of −35 ° C. or lower may be, for example, 20 days or less, or 10 days or less. The negative electrode 24 placed in an environment with a dew point temperature of −35 ° C. or lower may be in a single state where the laminated body 22 is not formed or in the state of the electrode body 2. The negative electrode 24 placed in an environment with a dew point temperature of −35 ° C. or lower may be in the state of the negative electrode active material alone before forming the negative electrode active material layer. In addition, the negative electrode 24 placed in an environment with a dew point temperature of −35 ° C. or lower can be placed as a whole for three days or more before being housed in the case 3 as a constituent member of the electrode body 2. That is, the number of days to be placed in the state of the negative electrode active material alone, the number of days to be placed in the state of the negative electrode 24 on which the negative electrode active material layer is formed, the number of days to be placed in the state of the electrode body 2, and the like can be integrated. . Preferably, the negative electrode 24 is placed for 3 days or more in an environment where the dew point temperature is −35 ° C. or lower from when the negative electrode active material layer is manufactured to when the negative electrode 24 is accommodated in the case 3. In the present embodiment, the time when the negative electrode active material layer is manufactured means the time when the formation of the negative electrode active material layer is completed. In the present embodiment, before the negative electrode 24 is accommodated in the case 3 means before the welding of the case body 31 and the cover plate 32 is completed.

  The case main body 31 is a plate-like closing portion 311 having a closing portion 311 having an inner surface facing the inside of the case 3 and an outer surface facing the outer side of the case 3, and a body portion 312 connected to the periphery of the closing portion 311. And a cylindrical body 312 extending toward the inner surface of the closing portion 311 and surrounding the inner surface.

  The closing portion 311 is located at the lower end of the case main body 31 when the case main body 31 is arranged so that the opening faces upward (that is, it becomes the bottom wall of the case main body 31 when the opening faces upward). ) Part. The blocking part 311 has a rectangular shape when viewed in the normal direction of the blocking part 311. The four corners of the closing part 311 are arcuate.

  In the following, as shown in FIG. 1, the long side direction of the blocking part 311 is the X-axis direction, the short side direction of the blocking part 311 is the Y-axis direction, and the normal direction of the blocking part 311 is the Z-axis direction.

  The body portion 312 of the present embodiment has a rectangular tube shape. Specifically, the body portion 312 has a flat rectangular tube shape. The body portion 312 has a pair of long wall portions 313 extending from the long side at the periphery of the closing portion 311 and a pair of short wall portions 314 extending from the short side at the periphery of the closing portion 311. That is, the pair of long wall portions 313 are opposed to each other with an interval in the Y-axis direction (specifically, an interval corresponding to the short side of the periphery of the closing portion 311), and the pair of short wall portions 314 are spaced in the X-axis direction. (In detail, they are opposed to each other with a gap corresponding to the long side of the periphery of the blocking portion 311). By connecting the end portions of the short wall portion 314 corresponding to the pair of long wall portions 313 (specifically, facing each other in the Y-axis direction), a rectangular tube-shaped body portion 312 is formed.

  As described above, the case body 31 has a rectangular tube shape (that is, a bottomed rectangular tube shape) in which one end portion in the opening direction (Z-axis direction) is closed.

  The lid plate 32 is a plate-like member that closes the opening of the case body 31. Specifically, the cover plate 32 contacts the case body so as to close the opening of the case body 31. More specifically, the peripheral edge of the cover plate 32 is overlapped with the open peripheral edge 34 of the case body 31 so that the cover plate 32 closes the opening. In a state where the opening peripheral edge 34 and the cover plate 32 are overlapped, the boundary portion between the cover plate 32 and the case main body 31 is welded. Thereby, the case 3 is configured.

  The cover plate 32 has a contour shape corresponding to the opening peripheral edge 34 of the case body 31 when viewed in the Z-axis direction. That is, the lid plate 32 is a rectangular plate material that is long in the X-axis direction when viewed in the Z-axis direction. Further, the four corners of the cover plate 32 are arcuate.

The electricity storage device of this embodiment includes a negative electrode having a negative electrode active material layer containing non-graphitizable carbon, and the true specific gravity of the non-graphitizable carbon is 1.55 g / cm ³ or more and 1.70 g / cm ³ or less, and The average particle diameter of the non-graphitizable carbon is 6 μm or less.

The method for producing an electricity storage device of this embodiment includes producing a negative electrode having a negative electrode active material layer containing non-graphitizable carbon. The formation of the negative electrode active material layer has a true specific gravity of 1.55 g / cm ³ or more. 1. Use of non-graphitizable carbon having an average particle size of 6 μm or less and 1.70 g / cm ³ or less. 7-10, in the manufacturing method of the electrical storage element of this embodiment, the negative electrode which has a negative electrode active material layer containing non-graphitizable carbon is produced (step S11), and dew point temperature is -20 degreeC or more environment. After the prepared negative electrode is placed (step S12), the negative electrode is housed in a case to assemble a storage element (step S13). In this embodiment, the negative electrode is accommodated in the case by accommodating an electrode body including the negative electrode in the case.

  In the method for producing an electric storage element, a negative electrode having a negative electrode active material layer containing non-graphitizable carbon is produced (step S21), and the produced negative electrode is placed in an environment having a dew point temperature of −35 ° C. or lower for 3 days or more (step After carrying out S22), the negative electrode may be housed in a case and a power storage element may be assembled (step S23).

  In the method for manufacturing the electricity storage device of this embodiment, the dew point temperature is between the production of the anode having the anode active material layer containing non-graphitizable carbon and the assembly of the electricity storage device by housing the anode in the case. Both placing the negative electrode in an environment of −20 ° C. or higher and placing the negative electrode in an environment having a dew point temperature of −35 ° C. or lower for 3 days or more may be performed.

  Therefore, in the method for manufacturing the electricity storage device of this embodiment, a negative electrode having a negative electrode active material layer containing non-graphitizable carbon is produced (step S31), and the produced negative electrode is placed in an environment with a dew point temperature of −20 ° C. or higher. (Step S32), and after placing the negative electrode in an environment where the dew point temperature is −35 ° C. or lower (Step S33), housing the negative electrode in the case and assembling the storage element (Step S34) Also good.

  In the method for manufacturing an electricity storage device of this embodiment, a negative electrode having a negative electrode active material layer containing non-graphitizable carbon is produced (step S41), and the produced negative electrode is subjected to an environment with a dew point temperature of −35 ° C. or lower for 3 days or more. After placing the negative electrode in an environment where the dew point temperature is −20 ° C. or higher (step S43), the negative electrode is housed in the case and the storage element is assembled (step S44). May be.

In the method for manufacturing the electricity storage device of this embodiment, the output of the electricity storage device can be improved by adding non-graphitizable carbon having an average particle diameter of 6 μm or less to the negative electrode active material layer. Non-graphitizable carbon having a true specific gravity of 1.55 g / cm ³ or more and 1.70 g / cm ³ or less is unlikely to be oxidized due to the influence of humidity. Therefore, a negative electrode including such a non-graphitizable carbon in the negative electrode active material layer is unlikely to cause a capacity reduction in the power storage element even if the storage period from manufacture to storage in the case is extended compared to the conventional case. . Therefore, in the method for manufacturing a power storage element of the present embodiment, the power storage element can be efficiently manufactured while ensuring the output and capacity of the power storage element.

  A method for manufacturing a power storage element includes housing a negative electrode in a case and assembling the power storage element, and in an environment in which a dew point temperature is −20 ° C. or higher after the negative electrode is manufactured and the negative electrode is housed in the case. A negative electrode can be placed on.

  In such a method for manufacturing a power storage device, it is possible to suppress the storage environment of the negative electrode from being limited. Therefore, in the method for manufacturing a power storage device of this embodiment, the power storage device can be manufactured efficiently.

  A method for manufacturing a power storage element includes housing a negative electrode in a case and assembling the power storage element, and in an environment in which a dew point temperature is −35 ° C. or lower after the negative electrode is manufactured and the negative electrode is housed in the case. The negative electrode can be placed for 3 days or longer.

  In such a method for manufacturing a power storage element, the storage period of the negative electrode can be secured for 3 days or more, so that the power storage element can be manufactured efficiently.

  In addition, the electrical storage element of this invention is not limited to the said embodiment, Of course, a various change can be added in the range which does not deviate from the summary of this invention. For example, the configuration of another embodiment can be added to the configuration of a certain embodiment, and a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment. Furthermore, a part of the configuration of an embodiment can be deleted.

  Moreover, in the said embodiment, although the case where an electrical storage element was used as a nonaqueous electrolyte secondary battery (for example, lithium ion secondary battery) which can be charged / discharged was demonstrated, the kind and magnitude | size (capacity | capacitance) of an electrical storage element are arbitrary. It is. Moreover, in the said embodiment, although the lithium ion secondary battery was demonstrated as an example of an electrical storage element, it is not limited to this. For example, the present invention can be applied to various secondary batteries, other primary batteries, and power storage elements of capacitors such as electric double layer capacitors.

  The power storage element (eg, battery) may be used in a power storage device (a battery module when the power storage element is a battery). The power storage device includes at least two power storage elements 1 and a bus bar member that electrically connects two (different) power storage elements 1 to each other. In this case, the technique of the present invention only needs to be applied to at least one power storage element 1.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

(Average particle size and output of non-graphitizable carbon)
A plurality of types of non-graphitizable carbon having different average particle diameters (D50) were prepared as negative electrode active materials.
Using this non-graphitizable carbon, negative electrodes were formed under the same conditions other than the average particle diameter.
A power storage device was produced using the negative electrode, and the output was measured.
The relationship between the average particle diameter of non-graphitizable carbon and the output of the electricity storage device is shown in Table 1 below.
Table 1 shows the electricity storage when the non-graphitizable carbon having each average particle diameter is used, based on the output of the electricity storage element when the non-graphitizable carbon having an average particle diameter of 10 μm is used as a reference (100%). The output of the element is shown as a relative ratio.
From the results shown in this table, it can be seen that the output of the electricity storage element is improved by adding non-graphitizable carbon having an average particle diameter of 6 μm or less to the negative electrode active material layer.

(True specific gravity and moisture content of non-graphitizable carbon)
Three types of non-graphitizable carbon having different true specific gravity were prepared, and the moisture content of each non-graphitizable carbon after being placed in an environment with a dew point temperature of −20 ° C. for 150 hours was measured.
The results are shown in Table 2 below.

From the results shown in Table 2, the non-graphitizable carbon having a true specific gravity of 1.55 g / cm ³ or more and 1.70 g / cm ³ or less has a moisture adsorption amount of 1.55 g in an environment with a dew point temperature of −20 ° C. It can be seen that it is less than non-graphitizable carbon having a true specific gravity of less than / cm ³ .
That is, it can be seen that non-graphitizable carbon having a true specific gravity of 1.55 g / cm ³ or more and 1.70 g / cm ³ or less hardly oxidizes even in an environment with a dew point temperature of −20 ° C.

(Change in true specific gravity and capacity of non-graphitizable carbon)
A negative electrode was prepared using the above three types of non-graphitizable carbon as a negative electrode active material.
A storage element was produced using this negative electrode, and the capacity (C ₀ ) was measured.
Next, this negative electrode was stored for 15 days in an environment with a dew point temperature of −20 ° C. and an environment with a dew point temperature of −35 ° C., respectively, and a storage element was fabricated using the negative electrode after this storage.
The measured capacity of the power storage element was produced (C _1).
The ratio (C ₁ / C ₀ ) of the capacity (C ₁ ) to the initial capacity (C ₀ ) when the negative electrode after storage for 15 days is used is shown in Table 3 below as the capacity retention rate.

From the results shown in Table 3, the negative electrode using non-graphitizable carbon having a true specific gravity of 1.55 g / cm ³ or more and 1.70 g / cm ³ or less may take days to be incorporated into a power storage device. It turns out that it is hard to produce a capacity | capacitance fall to an electrical storage element.

(Change in moisture content of non-graphitizable carbon depending on storage environment)
Change in moisture content by using non-graphitizable carbon with a true specific gravity of 1.64 g / cm ³ and storing this non-graphitizable carbon in an environment with a dew point temperature of −20 ° C. and an environment with a dew point temperature of −35 ° C. for a maximum of 7 days. Was observed.
And the moisture content for every time passage when the initial moisture content is 100% is shown in the following Table 4 as a relative ratio.

From the results shown in Table 4, the non-graphitizable carbon having a true specific gravity of 1.55 g / cm ³ or more and 1.70 g / cm ³ or less is almost in its initial state in a dew point temperature of −35 ° C. It turns out that it does not change.

As described above, by using non-graphitizable carbon having a true specific gravity of 1.55 g / cm ³ or more and 1.70 g / cm ³ or less and an average particle diameter of 6 μm or less as the negative electrode active material, the output of the electricity storage element can be improved. It can be seen that a reduction in the capacitance of the element can be suppressed.
Further, by using non-graphitizable carbon having a true specific gravity of 1.55 g / cm ³ or more and 1.70 g / cm ³ or less as a negative electrode active material, it is possible to store electricity even if it takes time to assemble a power storage element after manufacturing the negative electrode. It can be seen that a sufficient capacitance of the element is secured. Therefore, the storage period of the negative electrode can be extended by using non-graphitizable carbon having a true specific gravity of 1.55 g / cm ³ or more and 1.70 g / cm ³ or less as the negative electrode active material. That is, by using non-graphitizable carbon having a true specific gravity of 1.55 g / cm ³ or more and 1.70 g / cm ³ or less as the negative electrode active material, the degree of freedom of the manufacturing process is increased, and the electricity storage device can be efficiently manufactured.

1: power storage element, 23: positive electrode, 24: negative electrode, 25: separator

Claims (4)

Comprising a negative electrode having a negative electrode active material layer containing non-graphitizable carbon,
The flame true specific gravity of the graphitized carbon is less 1.55 g / cm ³ or more 1.70 g / cm ^3, and an average particle diameter of the flame graphitized carbon is 6μm or less, the electric storage element. Producing a negative electrode having a negative electrode active material layer comprising non-graphitizable carbon,
The negative electrode active material layer is formed by using a non-graphitizable carbon having a true specific gravity of 1.55 g / cm ³ or more and 1.70 g / cm ³ or less and an average particle diameter of 6 μm or less. Including assembling a storage element by housing the negative electrode in a case;
The method for manufacturing a storage element according to claim 2, further comprising placing the negative electrode in an environment having a dew point temperature of -20 ° C or higher before the negative electrode is housed in the case. Including assembling a storage element by housing the negative electrode in a case;
The method for manufacturing a power storage element according to claim 2, further comprising placing the negative electrode in an environment having a dew point temperature of −35 ° C. or lower for 3 days or longer before accommodating the negative electrode in the case.

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