Electrode, electrode structure, battery, aircraft, and electrode production method and electrode structure production method

Abstract

SOLUTION: To provide an electrode production method that includes the steps of preparing a current collector, forming an active material layer containing an organic compound as an active material on at least one surface of the current collector, and fixing the active material layer and the current collector, and in which the current collector includes a conductive layer including a conductive material, and a support layer that supports the conductive layer, electrical conductivity of the support layer is less than electrical conductivity of the conductive layer, density of the support layer is less than density of the conductive layer, the step of fixing the active material layer and the current collector includes a step of applying a pressure to the stacked active material layer and the current collector, and the pressure is set or adjusted such that (i) a change rate in electrical resistance of the current collector before and after the pressure is applied to the active material layer and the current collector is within 50%, or (ii) an absolute value of a difference in electrical resistance of the current collector before and after the pressure is applied to the active material layer and the current collector is less than 1 [Ω].SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electrode, an electrode structure, a battery, an aircraft, and a method for producing an electrode and a method for producing an electrode structure. [Background technology]

[0002] Patent Document 1 discloses the formation of a positive electrode active material layer using a coating composition for a positive electrode active material layer containing a positive electrode active material, a binder, and a solvent. Patent Document 2 discloses the application of a press treatment with a heated roller to a negative electrode current collector containing a negative electrode mixture slurry. Patent Document 3 discloses the fabrication of a positive electrode by applying an electrode paste to a current collector, drying it, and then rolling it with a roll press at a linear pressure of 290 kgf / cm. [Prior art document] [Patent Documents] [Patent Document 1] JP 2006-156102 A [Patent Document 2] JP 2015-185092 A [Patent Document 3] JP 2014-143041 A Summary of the Invention [Means for solving the problem]

[0003] A first aspect of the present invention provides a method for producing an electrode. The method includes, for example, a step of preparing a current collector. The method includes, for example, a step of forming an active material layer containing an organic compound as an active material on at least one surface of the current collector. The method includes, for example, a step of bonding the active material layer and the current collector. In the method, the current collector includes, for example, a conductive layer containing a conductive material. The current collector includes, for example, a support layer that supports the conductive layer. In the method, the conductivity of the support layer is, for example, lower than the conductivity of the conductive layer. The density of the support layer is, for example, lower than the density of the conductive layer. In the method, the step of bonding the active material layer and the current collector includes, for example, a step of applying pressure to the stacked active material layer and current collector. In the above method, the pressure is set or adjusted, for example, so that (i) the rate of change in the electrical resistance of the current collector before and after application of pressure to the active material layer and the current collector is within 50%, or (ii) the absolute value of the difference in the electrical resistance of the current collector before and after application of pressure to the active material layer and the current collector is less than 1 [Ω].

[0004] A second aspect of the present invention provides a method for producing an electrode. The method includes, for example, a step of preparing a current collector. The method includes, for example, a step of forming an active material layer containing an organic compound as an active material on at least one surface of the current collector. The method includes, for example, a step of bonding the active material layer and the current collector. In the method, the current collector includes, for example, a conductive layer containing a conductive material. The current collector includes, for example, a support layer that supports the conductive layer. In the method, the conductivity of the support layer is, for example, lower than the conductivity of the conductive layer. The density of the support layer is, for example, lower than the density of the conductive layer. In the method, the step of bonding the active material layer and the current collector includes, for example, a step of applying pressure to the stacked active material layer and current collector. In the above method, the pressure is set or adjusted so that, for example, the value obtained by subtracting (ii) the value of the first voltage measured by applying a current to the conductive layer of the current collector before the pressure is applied from the value of the second voltage measured by applying a current to the conductive layer of the current collector after the pressure is applied is less than 100 mV.

[0005] A third aspect of the present invention provides a method for producing an electrode. The method includes, for example, preparing a current collector. The method includes, for example, forming an active material layer containing an organic compound as an active material on at least one surface of the current collector. The method includes, for example, adhering the active material layer and the current collector. In the method, the current collector includes, for example, a conductive layer containing a conductive material. The current collector includes, for example, a support layer supporting the conductive layer. In the method, the conductivity of the support layer is, for example, lower than the conductivity of the conductive layer. The density of the support layer is, for example, lower than the density of the conductive layer. In the method, adhering the active material layer and the current collector includes, for example, applying pressure to the stacked active material layer and current collector. In the method, the pressure is set or adjusted, for example, so that the porosity of the active material layer after pressure application is 25 to 40%.

[0006] In the method for producing an electrode according to the first, second, and / or third aspect, the step of applying pressure may include applying pressure to the stacked active material layers and current collector using a roll press at a linear pressure of 1.0 kgf / cm to 200 kgf / cm. In any of the methods for producing an electrode described above, the support layer may be a sheet-like resin material. In any of the methods for producing an electrode described above, the conductive layer may include layered or foil-like aluminum. The thickness of the layered or foil-like aluminum may be 0.05 μm to 5 μm.

[0007] In a fourth aspect of the present invention, there is provided a method for producing an electrode structure. The method includes, for example, a step of preparing a positive electrode and a negative electrode. The method includes, for example, a step of preparing a separator. The method includes, for example, a step of stacking a positive electrode, a separator, and a negative electrode in this order. In the method, the step of preparing the positive electrode and the negative electrode includes, for example, a step of producing at least one of the positive electrode and the negative electrode by any of the above methods for producing electrodes.

[0008] In a fifth aspect of the present invention, there is provided an electrode. The electrode includes, for example, a current collector. The electrode includes, for example, an active material layer disposed on at least one surface of the current collector and containing an organic compound as an active material. In the electrode, the current collector includes, for example, a conductive layer containing a conductive material. The current collector includes, for example, a support layer supporting the conductive layer. In the electrode, the conductive layer has a thickness of, for example, 0.05 μm to 5 μm. The conductivity of the support layer is, for example, lower than the conductivity of the conductive layer. The density of the support layer is, for example, lower than the density of the conductive layer. The electrical resistance of the current collector is, for example, 0.01 mΩ to 1 Ω.

[0009] In the above electrode, the active material layer may have a porosity of 25 to 40%. In any of the above electrodes, the conductive layer may be aluminum foil. In any of the above electrodes, the support layer may be a sheet-like resin material.

[0010] In any of the above electrodes, the current collector may have a plurality of through holes formed therein. The circle-equivalent diameter of each of the plurality of through holes may be 15 μm to 150 μm. In any of the above electrodes, the ratio of the total area of the plurality of through holes on one surface of the current collector to the outer area of the one surface of the current collector may be 30% or more. Any of the above electrodes may include an internal conductive layer disposed on the inner walls of at least some of the plurality of through holes and containing a conductive material. The internal conductive layer may have three or more layers with different main components.

[0011] In a sixth aspect of the present invention, there is provided an electrode structure. The electrode structure includes, for example, one or more positive electrodes. The electrode structure includes, for example, one or more negative electrodes. The electrode structure includes, for example, one or more separators disposed between each of the one or more positive electrodes and each of the one or more negative electrodes. In the electrode structure, at least one of the one or more positive electrodes and the one or more negative electrodes is, for example, any of the electrodes according to the fifth aspect.

[0012] In the above electrode structure, the separator may contain a polymer solid electrolyte.

[0013] In a seventh aspect of the present invention, there is provided a battery. The battery includes, for example, any of the electrode structures according to the sixth aspect. The battery includes, for example, a housing that houses the electrode structure.

[0014] The above-mentioned battery may include at least one of a positive electrode connector that electrically connects one or more positive electrodes and a negative electrode connector that electrically connects one or more negative electrodes. In any of the above-mentioned batteries, the positive electrode connector may include a positive electrode support that sandwiches and supports a portion of one or more positive electrodes. In any of the above-mentioned batteries, the negative electrode connector may include a negative electrode support that sandwiches and supports a portion of one or more negative electrodes.

[0015] In an eighth aspect of the present invention, there is provided an aircraft. The aircraft includes, for example, any of the batteries according to the seventh aspect. The aircraft includes, for example, a thrust generating device that generates thrust using electrical energy stored in the battery.

[0016] The above summary of the invention does not list all of the necessary features of the present invention, and subcombinations of these features may also constitute inventions. [Brief explanation of the drawings]

[0017] [Figure 1] 1 shows a schematic diagram of an example of the system configuration of an aircraft 100. [Figure 2] An example of a power storage cell 112 is shown schematically. [Figure 3] Another example of a storage cell 112 is shown schematically. [Figure 4] An example of a current collector 400 is shown schematically. [Figure 5] An example of a current collector 500 is shown schematically. [Figure 6] An example of a current collector 600 is shown schematically. [Figure 7] An example of a laminate structure 760 is shown schematically. [Figure 8]An example of the electrical connection relationship of the electrodes of the laminated structure 760 is shown schematically. [Figure 9] An example of a method for manufacturing the energy storage cell 112 is shown schematically. [Figure 10] An example of a method for manufacturing the positive electrode 220 is shown schematically. [Figure 11] 1 shows charge / discharge curves of Example 1 and Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0018] According to one embodiment (sometimes referred to as the present embodiment) illustrated in this specification, an electrode for use in a battery (particularly a secondary battery) is produced using a current collector having a conductive layer and a support layer supporting the conductive layer. The method for producing the electrode includes, for example, a step of preparing a current collector, a step of forming an active material layer on at least one surface of the current collector, and a step of fixing the active material layer and the current collector.

[0019] In this embodiment, the conductive layer includes, for example, a conductive material. Furthermore, for example, the conductivity of the support layer is lower than that of the conductive layer, and the density of the support layer is lower than that of the conductive layer. This can improve the energy density per unit mass of the storage cell [Wh / kg-storage cell] and / or the capacity per unit mass of the active material [mAh / g-active material] compared to conventional storage cells.

[0020] For example, conventionally, aluminum foil, copper foil, or the like having a thickness of about 8 to 20 μm has been used as the current collector. Therefore, in conventional batteries, the mass ratio of the positive and negative electrode current collectors to the mass of the storage cell was 20 to 25%. In contrast, according to this embodiment, a portion of the current collector is formed from a material (typically air or a thermoplastic resin material) having a lower density than aluminum foil or copper foil. As a result, a storage cell having excellent energy density per unit mass and / or capacity per unit mass of active material can be provided. For example, according to this embodiment, a storage cell having an energy density per unit mass of 350 [Wh / kg-storage cell] or more can be provided. Furthermore, a battery including the storage cell according to this embodiment has a high energy density per unit mass and is therefore particularly suitable for use in aircraft.

[0021] According to this embodiment, pressure is applied to the stacked active material layer and current collector to bond them together. Here, as the conductive layer becomes thinner, the conductive layer becomes more susceptible to damage during the bonding process. In particular, if the conductivity of the support layer is lower than that of the conductive layer, significant damage to the conductive layer increases the electrical resistance of the current collector, resulting in a decrease in the energy density per unit mass of the battery [Wh / kg-battery] and / or the capacity per unit mass of the active material [mAh / g-active material].

[0022] Therefore, according to the present embodiment, the pressure in the bonding step is set or adjusted to a relatively small value so as to suppress breakage of the conductive layer of the current collector.

[0023] In one embodiment, the pressure in the fixing step is set or adjusted so that (i) the rate of change in the electrical resistance (resistivity) of the current collector before and after application of pressure to the active material layer and the current collector is within 50%, or (ii) the absolute value of the difference in the electrical resistance (resistivity) of the current collector before and after application of pressure to the active material layer and the current collector is less than 1 [Ω]. The pressure in the fixing step is preferably set or adjusted so that the absolute value of the difference is 500 m[Ω] or less, and more preferably set or adjusted so that the absolute value of the difference is 100 m[Ω] or less. This prevents breakage of the conductive layer of the current collector.

[0024] In another embodiment, the pressure in the fixing step is set or adjusted so that (i) the value of the second voltage measured by applying a current to the conductive layer of the current collector after the pressure has been applied minus (ii) the value of the first voltage measured by applying a current to the conductive layer of the current collector before the pressure has been applied is less than 100 mV. This prevents breakage of the conductive layer of the current collector. The first and second voltages are measured, for example, by a low resistivity meter having a voltage measurement function and an output function. The first and second voltages can be measured, for example, by a four-terminal, four-probe method using a low resistivity meter (Loresta-GX MCP-T700, manufactured by Nitto Seiko Analytech Co., Ltd.).

[0025] In another embodiment, the pressure in the fixing step is set or adjusted so that the porosity of the active material layer after pressure application is 20 to 40%, thereby suppressing breakage of the conductive layer of the current collector.

[0026] As described above, in this embodiment, the pressure in the bonding step is set or adjusted to a relatively small value. For example, when the active material layer and the current collector are bonded using a roll press, the linear pressure of the roll press is set or adjusted to 200 kgf / cm or less. On the other hand, when the pressure in the bonding step is low, the active material layer and the current collector are less likely to bond to each other. In this regard, the present inventors have found that when the active material contained in the active material layer is mainly an organic compound (sometimes referred to as an organic active material), the active material layer and the current collector can be bonded to each other even with a relatively small pressure.

[0027] As described in JP 2014-143041 A, when the active material contained in the active material layer is primarily an inorganic compound (sometimes referred to as an inorganic active material), a high linear pressure of 290 kgf / cm or more is applied using a roll press. This is because inorganic active materials have a relatively high Young's modulus and are hard, and it is presumed that unless high pressure is applied in the above-mentioned bonding step, the bonded interface between the active materials will not be maintained. In contrast, organic active materials have a relatively low Young's modulus and are soft, and it is presumed that the bonded interface between the active materials will be maintained even if the pressure in the bonding step is low.

[0028] The Young's modulus of inorganic active materials is often 70 to 200 GPa. The Young's modulus of organic active materials is often 0.5 GPa or less. The Young's modulus is measured, for example, using a nanoindenter. The nanoindenter measures the hardness and / or Young's modulus of a sample by crushing a sample spread on a glass slide using a flat-tipped flat punch indenter.

[0029] Therefore, in this embodiment, prior to the fixing step, an active material layer containing an organic compound as an active material is formed on at least one surface of the current collector, thereby making it possible to reduce the pressure in the fixing step of the active material layer and the current collector.

[0030] Furthermore, when the active material contained in the active material layer is primarily an organic compound, the capacity per unit mass of the active material may decrease when high voltage is applied to the active material layer. The cause of this phenomenon is unclear, but as mentioned above, organic active materials have a smaller Young's modulus than inorganic active materials. Therefore, when high voltage is applied to the active material layer, the active material particles may deform or the voids between the particles may decrease. This is thought to result in impeded penetration of the electrolyte into the active material layer and a decrease in the ionic conduction paths and / or electrical conduction paths in the active material layer.

[0031] As described above, according to this embodiment, high voltage is not applied to the active material layer during the electrode production process. Therefore, even when the active material layer mainly contains an organic active material as the active material, the above-mentioned capacity decrease is suppressed. Furthermore, organic active materials are generally lighter than inorganic active materials. Therefore, when the electrode according to this embodiment is incorporated into a battery, the energy density of the battery is improved. In particular, by using organic molecules with a relatively small molecular weight and the ability to donate and accept multiple electrons as the active material of the battery, the energy density of the battery can be significantly improved. In particular, the mass energy density [Wh / kg] of the battery is significantly improved.

[0032] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0033] In this specification, when a numerical range is expressed as "A to B," the expression means A or more and B or less. Furthermore, "substituted or unsubstituted" means "substituted with any substituent, or not substituted with any substituent." The type of the above-mentioned substituent is not particularly limited unless otherwise specified in the specification. Furthermore, the number of the above-mentioned substituents is not particularly limited unless otherwise specified in the specification.

[0034] (Overview of the flying vehicle 100) 1 schematically illustrates an example of the system configuration of an aircraft 100. In this embodiment, the aircraft 100 includes a storage battery 110, a power control circuit 120, one or more electric motors 130, one or more propellers 140, one or more sensors 150, and a control device 160. In this embodiment, the storage battery 110 includes one or more storage cells 112.

[0035] In this embodiment, the flying object 100 flies using electrical energy stored in the storage battery 110. Examples of the flying object 100 include an airplane, an airship or balloon, a hot air balloon, a helicopter, and a drone.

[0036] In this embodiment, the storage battery 110 receives electrical energy from an external charging device (not shown) via the power control circuit 120 and stores the electrical energy in one or more storage cells 112. The storage battery 110 also supplies the electrical energy stored in the one or more storage cells 112 to the electric motor 130 via the power control circuit 120.

[0037] In this embodiment, the power storage cell 112 stores electric energy (this may be referred to as charging the power storage cell 112). The power storage cell 112 also releases the stored electric energy (this may be referred to as discharging the power storage cell 112). The power storage cell 112 may be a secondary battery.

[0038] The power storage cell 112 may be an all-solid-state battery. The power storage cell 112 may be an all-solid-state secondary battery. An all-solid-state secondary battery is a secondary battery that is substantially free of the above-described electrolytic solution or gel electrolyte, and includes, for example, a pair of electrodes and a solid electrolyte layer disposed between the pair of electrodes.

[0039] A secondary battery that is substantially free of an electrolytic solution or a gel electrolyte refers not only to a case where the secondary battery does not contain an electrolytic solution or a gel electrolyte, but also to a case where the secondary battery contains a small amount of an electrolytic solution or a gel electrolyte. This is because, even if the constituent materials of the secondary battery dissolve in the solvent contained in the electrolytic solution or the gel electrolyte, if the amount of the solvent contained in the secondary battery is small, the effect on the battery performance of the constituent materials of the secondary battery dissolving in the solvent can be ignored.

[0040] In one embodiment, the energy storage cell 112 does not include at least one of (i) an electrolyte solution containing a supporting electrolyte salt and a solvent, and (ii) a gel electrolyte containing a supporting electrolyte salt, an organic polymer compound, and an organic solvent. In another embodiment, the ratio of the mass [kg] of the electrolyte solution and the gel electrolyte to the mass [kg] of the organic compound used as the active material is less than 5%.

[0041] Examples of carrier ions for secondary batteries include lithium, sodium, potassium, magnesium, calcium, etc. Examples of secondary batteries include sodium ion secondary batteries, lithium ion secondary batteries, lithium metal secondary batteries, lithium air secondary batteries, lithium sulfur secondary batteries, and magnesium ion secondary batteries.

[0042] For example, a material that can store a large amount of charge per unit volume is often selected as the active material for a secondary battery mounted on a vehicle. On the other hand, in this embodiment, the storage cell 112 is mounted on the aircraft 100. Therefore, it is preferable that the active material used in the storage cell 112 be a material that can store a large amount of charge per unit mass.

[0043] The mass energy density of the storage cell 112 is preferably 350 [Wh / kg-storage cell] or more, more preferably 400 Wh / kg-storage cell] or more, even more preferably 500 Wh / kg-storage cell] or more, even more preferably 600 Wh / kg-storage cell] or more, and even more preferably 700 Wh / g-storage cell] or more. This results in a storage cell that is particularly suitable for use as a power source for an aircraft.

[0044] The volumetric energy density of the storage cell 112 is 300 [Wh / m 3 - Storage cell] or more 1200 [Wh / m 3 -storage cell] or less, 400 [Wh / m 3 - Storage cell] or more 1000 [Wh / m 3 When the storage cell 112 is installed in the aircraft 100 as part of the power supply of the aircraft 100, the volumetric energy density of the storage cell 112 may be 600 [Wh / m 3 -storage cell] or less, and 800 [Wh / m 3 -storage cell] or less.

[0045] The energy storage cell 112 may have a mass energy density within the above-mentioned ranges and a volume energy density within the above-mentioned ranges. This allows the energy storage cell, which is relatively difficult to use as a power source for a vehicle, to be used as a power source for an aircraft. Details of the energy storage cell 112 will be described later.

[0046] In this embodiment, the power control circuit 120 controls the input and output of power to the storage battery 110. The power control circuit 120 may control the input and output of power to the storage battery 110 based on commands from the control device 160. The power control circuit 120 includes, for example, multiple switching elements that operate based on control signals from the control device 160.

[0047] In this embodiment, the electric motor 130 receives electrical energy from the storage battery 110 via the power control circuit 120. The electric motor 130 uses the electrical energy received from the storage battery 110 to rotate the propeller 140. In this way, the electric motor 130 can generate propulsion force for the aircraft 100 using the electrical energy stored in the storage cell 112.

[0048] In this embodiment, the sensor 150 measures various physical quantities related to the position and attitude of the flying object 100. Examples of sensors for measuring various physical quantities related to the position and attitude of the flying object 100 include a GPS signal receiver, an acceleration sensor, an angular acceleration sensor, and a gyro sensor. The sensor 150 may measure various physical quantities related to the state of the storage battery 110. Examples of sensors for measuring various physical quantities related to the state of the storage battery 110 include a temperature sensor, a current sensor, and a voltage sensor.

[0049] In this embodiment, the control device 160 controls the aircraft 100. The control device 160 may control the input and output of power to the storage battery 110 by controlling the power control circuit 120. For example, the control device 160 controls the output current, output voltage, input current, input voltage, etc. of the storage battery 110. This allows the control device 160 to control the position and attitude of the aircraft 100. The control device 160 may control the position and attitude of the aircraft 100 by controlling the power control circuit 120 based on the output from the sensor 150.

[0050] The storage battery 110 may be an example of a secondary battery. The storage cell 112 may be an example of a secondary battery. The electric motor 130 may be an example of a propulsion force generating device. The secondary battery may be an example of a battery.

[0051] (Outline of the storage cell 112) 2 schematically shows an example of the power storage cell 112. In this embodiment, the details of the power storage cell 112 will be described using as an example a case where the power storage cell 112 is a coin-type all-solid-state secondary battery. However, it should be noted that the power storage cell 112 is not limited to a coin-type all-solid-state secondary battery.

[0052] (storage cell) In this embodiment, the energy storage cell 112 includes a positive electrode case 212, a negative electrode case 214, a sealant 216, and a metal spring 218. The energy storage cell 112 also includes a positive electrode 220, a separator 230, and a negative electrode 240. In this embodiment, the positive electrode 220 includes a positive electrode current collector 222 and a positive electrode active material layer 224. In this embodiment, the negative electrode 240 includes a negative electrode current collector 242 and a negative electrode active material layer 244.

[0053] In this embodiment, the energy storage cell 112 includes a structure 260 having a positive electrode 220, a separator 230, and a negative electrode 240. As shown in FIG. 2 , the positive electrode 220, the separator 230, and the negative electrode 240 are stacked in this order, and the separator 230 is disposed between the positive electrode 220 and the negative electrode 240.

[0054] In this embodiment, the details of the storage cell 112 will be described using as an example a case where the storage cell 112 does not substantially contain an electrolytic solution or a gel electrolyte. Also, in this embodiment, the details of the storage cell 112 will be described using as an example a case where the positive electrode current collector 222 has (i) a conductive layer containing a conductive material and (ii) a support layer that supports the conductive layer.

[0055] In this embodiment, by assembling the positive electrode case 212 and the negative electrode case 214, a space is formed inside the positive electrode case 212 and the negative electrode case 214. A metal spring 218, a positive electrode 220, a separator 230, and a negative electrode 240 are housed inside the space formed by the positive electrode case 212 and the negative electrode case 214. The positive electrode 220, the separator 230, and the negative electrode 240 are fixed inside the positive electrode case 212 and the negative electrode case 214 by the repulsive force of the metal spring 218.

[0056] The positive electrode case 212 and the negative electrode case 214 are made of, for example, a thin, disc-shaped conductive material. In this embodiment, the sealant 216 seals the gap formed between the positive electrode case 212 and the negative electrode case 214. The sealant 216 includes an insulating material. The sealant 216 insulates the positive electrode case 212 and the negative electrode case 214.

[0057] (positive electrode) In this embodiment, the positive electrode current collector 222 holds the positive electrode active material layer 224. In this embodiment, the positive electrode current collector 222 has an electrical resistance of 0.01 mΩ to 1 Ω. This suppresses fluctuations in voltage measured by applying a current to the conductive layer under specific measurement conditions before and after pressure is applied to the conductive layer (details of the conductive layer will be described later) of the positive electrode current collector 222 during manufacture of the positive electrode current collector 222 to, for example, less than 100 mV. The positive electrode current collector 222 may have an electrical resistance of 0.01 mΩ to 333 mΩ, or may have an electrical resistance of 0.01 mΩ to 100 mΩ.

[0058] The density of the positive electrode current collector 222 is, for example, 1.1 to 2.0 g / cm 3 As a result, for example, the main component of the active material contained in the positive electrode active material layer 224 is anthraquinone (density: 1.3 g / cm 3 ), anthracene (density: 1.25 g / cm 3 ) and / or naphthalene (density: 1.14 g / cm 3 ), the mass of the positive electrode 220 including the positive electrode current collector 222 and the positive electrode active material layer 224 becomes very light, and the mass energy density of the power storage cell 112 becomes large.

[0059] In this embodiment, at least a portion of the positive electrode current collector 222 is made of a material having a lower density than metal. At least a portion of the positive electrode current collector 222 may be made of a material having a lower density than aluminum. For example, at least a portion of the positive electrode current collector 222 is made of resin. This allows the weight of the energy storage cell 112 to be reduced.

[0060] In particular, when a separator 230 containing a solid electrolyte as a main component is used, the mass of the separator 230 may become relatively large depending on the type of solid electrolyte. Even in such a case, by forming at least a portion of the positive electrode current collector 222 from a resin, an increase in the overall mass of the energy storage cell 112 is suppressed. As a result, the capacity per mass of the energy storage cell 112 and the energy density of the energy storage cell 112 are improved.

[0061] For example, the positive electrode current collector 222 includes a conductive layer containing a conductive material and a support layer that supports the conductive layer. The conductive layer and the support layer will be described in detail later.

[0062] Examples of the shape of the positive electrode current collector 222 include a foil shape (sometimes referred to as a plate shape, film shape, sheet shape, etc.), a mesh shape, and a perforated plate shape. The thickness of the positive electrode current collector 222 is not particularly limited, but is preferably 1 to 200 μm. The thickness of the positive electrode current collector 222 may be 6 to 20 μm, or may be 4 to 10 μm.

[0063] In this embodiment, the positive electrode active material layer 224 is formed on at least one surface of the positive electrode current collector 222. The thickness of the positive electrode active material layer 224 per surface of the positive electrode current collector 222 may be 1 to 100 μm, or may be 5 to 50 μm.

[0064] The positive electrode active material layer 224 includes, for example, a positive electrode active material and a binding material (sometimes referred to as a binder). The positive electrode active material layer 224 may further include at least one of an electrically conductive material and an ionically conductive material. The positive electrode active material layer 224 may include a positive electrode active material and an ionically conductive material. This can prevent the ion conduction path and / or the electron conduction path formed inside the positive electrode active material layer 224 from being broken.

[0065] In one embodiment, the positive electrode active material layer 224 is formed by applying a slurry containing a solvent and materials constituting the positive electrode active material layer 224 to at least one surface of the positive electrode current collector 222 and then drying the slurry. Examples of the solvent include various solvent substances and mixtures thereof. The type of the solvent substance is not particularly limited, but examples of the solvent substance include N-methylpyrrolidone (NMP) and water.

[0066] In another embodiment, the positive electrode active material layer 224 is formed by mixing materials constituting the positive electrode active material layer 224, forming the mixture into a sheet, and pressing the sheet-like mixture onto at least one surface of the positive electrode current collector 222. When an organic compound is used as the positive electrode active material, the positive electrode current collector 222 and the positive electrode active material layer 224 are pressed together so as not to apply excessive pressure to the positive electrode active material layer 224 in the above-mentioned pressing step.

[0067] For example, when a coater is used to coat the precursor material of the positive electrode active material layer 224 onto the positive electrode current collector 222, the pressure applied to the precursor material of the positive electrode active material layer 224 is adjusted. For example, the coating gap of the coater is set to 180 μm or more. The coating gap may be set to 200 μm or more. This prevents the ion conduction paths and / or electron conduction paths in the positive electrode active material layer 224 from being broken.

[0068] When an organic compound is used as the positive electrode active material, the ratio of the volume of the organic compound functioning as the positive electrode active material to the volume of the positive electrode active material layer 224 (sometimes referred to as the active material volume ratio) may be 60% or more. The ratio of the volume of the organic compound functioning as the positive electrode active material to the volume of the positive electrode active material layer 224 is preferably 60 to 80%, and more preferably 65 to 75%.

[0069] When the positive electrode active material layer 224 is pressed under high pressure, the ratio of the volume of the organic compound functioning as the positive electrode active material to the volume of the positive electrode active material layer 224 exceeds 80%. If this ratio exceeds 80%, the ion conduction paths become narrower or are cut off. As a result, the capacity of the positive electrode active material layer 224 decreases. The high pressure may mean 50 MPa or more, 100 MPa or more, or 500 MPa or more.

[0070] On the other hand, if the ratio of the volume of the organic compound functioning as the positive electrode active material to the volume of the positive electrode active material layer 224 is less than 60%, the conductivity of carrier ions will be good, but the density of the positive electrode active material will be low and the mass of the positive electrode active material contained in the positive electrode active material layer 224 will be low, resulting in a small capacity of the positive electrode active material layer 224.

[0071] The ratio of the volume of the organic compound functioning as the positive electrode active material to the volume of the positive electrode active material layer 224 is determined based on the results of observation using, for example, a three-dimensional scanning electron microscopy (SEM). For example, according to "Numerical Evaluation of Active Material Volume by Three-Dimensional SEM (C0316)" (https: / / www.mst.or.jp / casestudy / tabid / 1318 / pdid / 87 / Default.aspx) proposed by the Materials Science and Technology Foundation, information such as the abundance ratio of each substance in a certain volume and the average volume can be obtained by repeating SEM observations and acquiring several tens of consecutive images.

[0072] The active material volume fraction in the positive electrode active material layer 224 is determined, for example, by the magnitude of pressure applied to the positive electrode active material layer 224 during the manufacturing process of the energy storage cell 112. As the pressure applied to the positive electrode active material layer 224 during the manufacturing process of the energy storage cell 112 increases, the active material volume fraction in the positive electrode active material layer 224 increases. The relationship between the magnitude of the pressure applied to the positive electrode active material layer 224 and the degree of increase in the active material volume fraction in the positive electrode active material layer 224 differs depending on, for example, the type of organic active material.

[0073] Therefore, for example, when an organic compound is used as the positive electrode active material, the maximum value of the pressure applied to the positive electrode active material layer 224 during the manufacturing process of the storage cell 112 is adjusted or controlled so that the volume ratio of the active material in the positive electrode active material layer 224 included in the manufactured storage cell 112 is 80% or less. This prevents the occurrence of a phenomenon in which the actual capacity of the positive electrode and / or battery is significantly reduced compared with the theoretical capacity of the positive electrode and / or battery.

[0074] Furthermore, the smaller the Young's modulus of the positive electrode active material layer 224, the greater the degree of increase in the active material volume ratio when a high voltage is applied to the positive electrode active material layer 224. Therefore, when the positive electrode active material is an organic compound, the Young's modulus of the positive electrode active material layer 224 may be adjusted to be approximately the same as the Young's modulus of the separator 230. For example, when the separator 230 is mainly composed of a polymer solid electrolyte and the positive electrode active material is an organic compound, the material and / or manufacturing conditions of the positive electrode active material layer 224 are determined so that the ratio of the Young's modulus of the polymer solid electrolyte to the Young's modulus of the positive electrode active material is 0.7 to 1.3.

[0075] The Young's modulus is measured, for example, by a bending test specified in JIS K 7171. In the bending test, the strain rate is set to about 1% / min.

[0076] There is no particular limitation on the Young's modulus of the positive electrode active material layer 224. For example, when the pressure applied to the positive electrode active material layer 224 in the manufacturing process of the energy storage cell 112 is relatively small, the material of the positive electrode active material layer 224 can be determined arbitrarily without considering the Young's modulus of the positive electrode active material layer 224.

[0077] Furthermore, according to this embodiment, the pressure applied to the positive electrode collector 222 and the positive electrode active material layer 224 is set or adjusted as described above also in the process of fixing the positive electrode collector 222 and the positive electrode active material layer 224. This prevents breakage of the conductive layer included in the positive electrode collector 222, even if the conductive layer is thin. As a result, an increase in the electrical resistance of the positive electrode collector 222 is suppressed. According to this embodiment, not only is a decrease in capacity due to a decrease in the ion conduction paths and / or conductive paths of the positive electrode active material layer 224 suppressed, but a decrease in capacity due to an increase in the electrical resistance of the positive electrode collector 222 can also be suppressed.

[0078] As described above, according to this embodiment, the pressure in the fixing step is set or adjusted so that the ratio of the volume of the organic compound functioning as the positive electrode active material to the volume of the positive electrode active material layer 224 is 60 to 80%. In this case, the ratio of the volume of voids to the volume of the positive electrode active material layer 224 (sometimes referred to as void ratio or porosity) is 25 to 40%.

[0079] (Cathode active material) The positive electrode active material contained in the positive electrode active material layer 224 may be any of various materials capable of absorbing and releasing carrier ions of the power storage cell 112. In this embodiment, the positive electrode active material is mainly composed of one or more types of organic compounds. The positive electrode active material may also contain an inorganic compound. For example, 80 mass % or more of the positive electrode active material contained in the positive electrode active material layer 224 is composed of an organic compound.

[0080] As described above, the positive electrode 220 includes the positive electrode current collector 222 and the positive electrode active material layer 224. The mass of the positive electrode active material layer 224 may be 80% or more of the total mass of the positive electrode 220. The mass of the positive electrode active material may be 80% or more of the total mass of the positive electrode active material layer 224. The mass of the organic compound used as the positive electrode active material may be 80% or more of the total mass of the positive electrode active material.

[0081] Examples of inorganic compounds used as the positive electrode active material (sometimes referred to as inorganic positive electrode active materials) include metal oxides, metal silicates, metal phosphates, metal borates, etc. Examples of the metals include transition metals such as V, Mn, Ni, and Co.

[0082] As the organic compound used as the positive electrode active material (sometimes referred to as organic positive electrode active material), various redox-active compounds are used as the organic positive electrode active material. Examples of the organic positive electrode active material include conjugated polymers, disulfides, quinones, localized radicals, and delocalized radicals.

[0083] The organic positive electrode active material may be at least one compound selected from the group consisting of aromatic hydrocarbons, aromatic heterocyclic compounds, alkenes substituted with one or more cyano groups, disulfides, and derivatives thereof, as well as compounds containing structures or structural units derived therefrom. When the organic positive electrode active material is a compound containing the above structural units, its degree of polymerization may be 100 or less. The above derivatives may be compounds in which one or more hydrogen atoms have been substituted with a ketone group, an OH group, an OM group (M is a metal, and examples of M include a battery carrier metal, an alkali metal, and an alkaline earth metal), a nitro group, or the like.

[0084] The organic positive electrode active material may be at least one compound selected from the group consisting of a compound having a structure in which at least two oxygen atoms are bonded to a benzene ring, a compound having a structure in which at least two hydroxyl groups are bonded to a benzene ring, a compound having a structure in which at least two carbon atoms of a benzene ring are replaced with nitrogen atoms, a compound having a structure in which at least two cyano groups are bonded to a carbon double bond, a compound having a disulfide bond, derivatives thereof, and compounds having structures or structural units derived therefrom. When the organic positive electrode active material is a compound having the above structural units, its degree of polymerization may be 100 or less. The above derivatives may be compounds in which one or more hydrogen atoms are substituted with a ketone group, an OH group, an OM group (M is a metal. Examples of M include a battery carrier metal, an alkali metal, an alkaline earth metal, etc.), a nitro group, or the like.

[0085] A compound having a structure derived from a specific compound may be a compound having a group or structure formed by removing at least one hydrogen atom contained in the specific compound. A compound having a structure derived from a specific compound may be a monomer, dimer, or polymer of the compound. For example, a compound having a structure derived from benzoquinone, which is an example of a derivative of an aromatic hydrocarbon, may be a derivative of a polycyclic aromatic hydrocarbon such as naphthoquinone, anthraquinone, or phenanthrenequinone.

[0086] For example, 1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, and 9,10-anthraquinone contain a structure derived from benzoquinone. 5,8-dihydroxy-1,4-naphthoquinone (sometimes referred to as naphthazarin) is an example of a compound containing a structure derived from 1,4-naphthoquinone. 9,10-anthraquinone is also an example of a compound containing a structure derived from 1,4-naphthoquinone.

[0087] Similarly, examples of compounds containing structural units derived from a specific compound include polymers or oligomers containing, as repeating units, the specific compound or a group or structure formed by removing at least one hydrogen atom contained in the specific compound. As described above, compounds containing structural units derived from a specific compound are preferably oligomers with a degree of polymerization of 100 or less. This allows the production of batteries with high mass energy density.

[0088] The organic positive electrode active material may be a compound such that, when the volume fraction of the active material in the positive electrode active material layer 224 exceeds 80%, the capacity of the positive electrode active material layer 224 is less than 50% of the theoretical capacity of the positive electrode active material layer 224. The organic positive electrode active material may be a compound such that, when the volume fraction of the active material in the positive electrode active material layer 224 exceeds 80%, the capacity of the positive electrode active material layer 224 is less than 50% of the theoretical capacity of the positive electrode active material layer 224, and, when the volume fraction of the active material in the positive electrode active material layer 224 is 65 to 75%, the capacity of the positive electrode active material layer 224 is 50% or more (more preferably, 70% or more) of the theoretical capacity of the positive electrode active material layer 224. As described above, according to this embodiment, even when such an organic compound is used as the positive electrode active material of a battery, a high-capacity battery can be manufactured.

[0089] Examples of such organic compounds include organic molecules that have a relatively small molecular weight and are capable of donating and accepting multiple electrons. When the organic molecule is a low-molecular-weight compound, the molecular weight of the organic molecule is, for example, 500 or less. The molecular weight of the organic molecule may be 200 or less. When the organic molecule is a polymer or oligomer, the molecular weight of the organic molecule is, for example, 5000 or less. The molecular weight of the organic molecule may be 3000 or less.

[0090] The organic positive electrode active material may be at least one compound selected from the group consisting of organic compounds having a solubility in ethylene carbonate (EC) of 0.01 to 40 [mmol / L-EC] at 0.1013 MPa and 25°C, and organic compounds having a solubility in diethyl carbonate (DEC) of 0.01 to 40 [mmol / L-DEC] at 0.1013 MPa and 25°C. The upper limit of the numerical range for the solubility is preferably 10 [mmol / L-solvent]. As described above, according to this embodiment, even when such an organic compound is used as the positive electrode active material of a battery, a battery with a relatively long life can be produced.

[0091] Examples of such organic compounds include organic molecules that have a relatively small molecular weight and are capable of donating and accepting multiple electrons. When the organic molecule is a low-molecular-weight compound, the molecular weight of the organic molecule is, for example, 500 or less. The molecular weight of the organic molecule may be 200 or less. When the organic molecule is a polymer or oligomer, the molecular weight of the organic molecule is, for example, 5000 or less. The molecular weight of the organic molecule may be 3000 or less.

[0092] As described above, the more easily the organic active material of the energy storage cell 112 dissolves in the solvent of the electrolyte solution or gel electrolyte, the greater the effect of the energy storage cell 112 being substantially free of the electrolyte solution or gel electrolyte. Ethylene carbonate (EC) and diethyl carbonate (DEC) are aprotic organic solvents that are widely used as solvents for the electrolyte solution or gel electrolyte. Therefore, when the positive electrode active material layer 224 contains an organic compound having the above-mentioned solubility, the effect of the energy storage cell 112 being substantially free of the electrolyte solution or gel electrolyte can be greater.

[0093] Specific examples of organic positive electrode active materials include at least one compound selected from the group consisting of compounds represented by the following chemical formulas and derivatives thereof, as well as compounds containing structures or structural units derived therefrom. As described above, a compound containing a structure derived from a specific compound may be a compound containing a group or structure formed by removing at least one hydrogen atom contained in the specific compound. Similarly, examples of compounds containing structural units derived from a specific compound include polymers or oligomers containing, as repeating units, the specific compound or a group or structure formed by removing at least one hydrogen atom contained in the specific compound.

[0094] [ka]

[0095] The above-mentioned derivatives may be compounds in which one or more hydrogen atoms have been substituted with deuterium, a hydroxyl group, an OM group (M is a metal. Examples of M include a battery carrier metal, an alkali metal, and an alkaline earth metal), a halogen, various organic groups, or the like. The molecular weight of at least one compound selected from the above group is, for example, 500 or less. The molecular weight of at least one compound selected from the above group may be 200 or less. The compound containing the above-mentioned structural unit is preferably an oligomer having a degree of polymerization of 100 or less.

[0096] In the above chemical formula, R and R' each independently represent hydrogen, deuterium, a hydroxyl group, an OM group (M is a metal. Examples of M include a battery carrier metal, an alkali metal, and an alkaline earth metal), a nitro group, an amino group, a sulfo group, or an organic group. Examples of the organic group include various monovalent groups. Examples of the organic group include an alkyl group, an alkenyl group, a ketone group, a carboxyl group, a carbonyl group, an aryl group, a cyano group, and a group containing a heterocycle. R and R' each independently may be one selected from hydrogen, deuterium, a hydroxyl group, an OM group (M is a metal. Examples of M include a battery carrier metal, an alkali metal, and an alkaline earth metal), a ketone group, a cyano group, a carbonyl group, and a group containing a heterocycle.

[0097] The organic group may be a monovalent group having a structure derived from a compound represented by each of the following chemical formulas or a derivative thereof.

[0098] [ka]

[0099] The monovalent group having a structure derived from the compound represented by each of the above chemical formulas may be a group obtained by removing one of the hydrogen atoms bonded to the aromatic ring in each of the above chemical formulas. The derivative of the compound represented by each of the above chemical formulas may be a compound in which one or more hydrogen atoms in the above chemical formulas have been substituted with deuterium, a halogen, a hydroxyl group, an OM group (M is a metal. Examples of M include a battery carrier metal, an alkali metal, an alkaline earth metal, etc.), a nitro group, an amino group, a sulfo group, an organic group, etc. The monovalent group having a structure derived from the above derivative may be a group obtained by removing one of the hydrogen atoms bonded to the aromatic ring of the derivative.

[0100] For example, when separator 230 is composed of a solid electrolyte layer mainly containing at least one compound selected from polyethylene oxide (PEO), poly(3,4-ethylenedioxythiophene) (PEDOT), and derivatives thereof, cathode active material layer 224 contains, as an organic cathode active material, at least one compound selected from the group consisting of compounds represented by the above chemical formulas, derivatives thereof, and compounds containing structures or structural units derived therefrom, thereby suppressing a decrease in capacity of the organic cathode active material described above.

[0101] The compounds represented by the above chemical formulas and their derivatives have small molecular weights and are capable of donating and accepting multiple electrons. Therefore, when these compounds are used as the active material of the energy storage cell 112, the energy density and / or capacity of the energy storage cell 112 is improved. In particular, according to this embodiment, the energy storage cell 112 is substantially free of an electrolytic solution or a gel electrolyte. Furthermore, the positive electrode active material layer 224 has a porosity of 20% or more. This further improves the energy density and / or capacity of the energy storage cell 112.

[0102] Among the above chemical formulas, examples of compounds containing a structure derived from p-benzoquinone include 5,8-dihydroxy-1,4-naphthoquinone (sometimes referred to as naphthazarin) and naphthazarin dimer. Similarly, examples of compounds containing a structure derived from p-benzenediol include naphthazarin and naphthazarin dimer. By using these compounds as positive electrode active materials, batteries with high energy density can be produced.

[0103] The compound containing a structure derived from p-benzoquinone may be 2,4-dihydroxy-p-benzoquinone. Among the above chemical formulas, an example of a compound containing a structure derived from o-benzoquinone is 4-nitro-1,2-benzoquinone. By using these compounds as positive electrode active materials, batteries with high energy density can be produced.

[0104] (Materials other than positive electrode active material) The binder material contained in the positive electrode active material layer 224 binds the materials that make up the positive electrode active material layer 224 together and maintains the electrode shape of the positive electrode 220. As the binder material, for example, various polymer materials are used. Examples of the polymer materials include carboxymethyl cellulose, styrene-butadiene rubber, polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), polyacrylic acid, polyethylene oxide (PEO), poly(3,4-ethylenedioxythiophene) (PEDOT), and derivatives thereof.

[0105] The binder material may be a material that dissolves in a solvent in which the solubility of the organic positive electrode active material is greater than a predetermined value. The solubility of the binder material in the solvent may be equal to or greater than the solubility of the organic positive electrode active material in the solvent. This facilitates the disassembly process of the storage cell 112, for example, when reusing the constituent materials of the storage cell 112.

[0106] The conductive material contained in the positive electrode active material layer 224 improves the conductivity of the positive electrode active material layer 224, thereby reducing the resistance of the positive electrode 220. The conductive material is not particularly limited as long as it is a material that has electronic conductivity. Examples of conductive materials include carbon-based materials, metal-based materials, and conductive polymer materials. These conductive materials may be used alone, or two or more conductive additives may be used in combination.

[0107] Examples of carbon-based materials include graphite, carbon black (e.g., acetylene black, ketjen black, etc.), coke, amorphous carbon, carbon fiber, carbon nanotubes, graphene, etc. Examples of metal-based materials include aluminum, gold, silver, copper, iron, platinum, chromium, tin, indium, titanium, nickel, etc. Examples of conductive polymer materials include polyphenylene derivatives, etc.

[0108] The conductive material may be a material that dissolves in a solvent in which the solubility of the organic positive electrode active material is greater than a predetermined value. The solubility of the conductive material in the solvent may be equal to or greater than the solubility of the organic positive electrode active material in the solvent. This facilitates the disassembly process of the storage cell 112, for example, when reusing the constituent materials of the storage cell 112.

[0109] The conductive material contained in the positive electrode active material layer 224 improves the conductivity of carrier ions in the positive electrode active material layer 224. For example, various solid electrolytes are used as the conductive material. Examples of solid electrolytes include sulfide-based solid electrolytes, oxide-based solid electrolytes, and polymer solid electrolytes. Polymer solid electrolytes may be used as the conductive material. Examples of polymer solid electrolytes include polyethylene oxide (PEO), poly(3,4-ethylenedioxythiophene) (PEDOT), and at least one compound selected from derivatives thereof.

[0110] As will be described later, in this embodiment, separator 230 includes a polymer solid electrolyte. The type of polymer solid electrolyte used as the conductive material may be the same as or different from the type of polymer solid electrolyte included in separator 230.

[0111] The conductive material may be a material that dissolves in a solvent in which the solubility of the organic positive electrode active material is greater than a predetermined value. The solubility of the conductive material in the solvent may be equal to or greater than the solubility of the organic positive electrode active material in the solvent. This facilitates the disassembly process of the storage cell 112, for example, when reusing the constituent materials of the storage cell 112.

[0112] (separator) In this embodiment, the separator 230 is disposed between the positive electrode 220 and the negative electrode 240 to separate the positive electrode 220 from the negative electrode 240. The separator 230 also ensures the conductivity of carrier ions between the positive electrode 220 and the negative electrode 240. The thickness of the separator 230 is not particularly limited, but is preferably 10 to 50 μm.

[0113] In this embodiment, the separator 230 includes a layer-shaped (sometimes referred to as a plate-shaped, film-shaped, sheet-shaped, etc.) solid electrolyte (sometimes referred to as a solid electrolyte layer). This allows the solid electrolyte layer to function as a separator for the energy storage cell 112.

[0114] In one embodiment, a solid electrolyte layer is used as separator 230. The solid electrolyte layer may be composed of a single solid electrolyte layer or multiple solid electrolyte layers. In another embodiment, separator 230 is a laminate of one or multiple solid electrolyte layers and another layer containing a material other than the solid electrolyte. The other layer may have ion conductivity. An example of the other layer is a composite material including a resin having multiple through holes formed therein and an ion-conductive material filled into the through holes.

[0115] This allows the production of a secondary battery that does not contain an electrolytic solution or a gel electrolyte. As a result, even if the positive electrode active material layer 224 and / or the negative electrode active material layer 244 contain an organic active material as the main active material, a decrease in battery life due to the dissolution of the organic active material in the solvent of the electrolytic solution or the gel electrolyte can be suppressed.

[0116] The separator 230 is not limited to the above embodiment. For example, a porous material having a solid electrolyte disposed inside the pores may be used as the separator 230. The separator 230 may be fabricated by immersing an appropriate support material or holding material in a gel electrolyte or an electrolyte solution, allowing the gel electrolyte or electrolyte solution to infiltrate the support material or holding material, and then solidifying the electrolyte disposed inside the support material or holding material. For example, the support material or holding material containing the gel electrolyte or electrolyte solution is dried, thereby solidifying the electrolyte disposed inside the support material or holding material.

[0117] Examples of solvents for electrolytic solutions or gel electrolytes include ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), butylene carbonate (BC), fluoroethylene carbonate (FEC), γ-butyrolactone, sulfolane, acetonitrile, 1,2-dimethoxymethane, 1,3-dimethoxypropane, diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, and mixtures thereof. In particular, ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) are widely used as solvents for electrolytic solutions or gel electrolytes.

[0118] (Solid electrolyte layer) In this embodiment, the separator 230 includes a solid electrolyte layer containing a polymer solid electrolyte as a main constituent material. The solid electrolyte layer contains, for example, 80 mass % or more of a true polymer solid electrolyte. When the separator 230 contains a polymer solid electrolyte as a main constituent material, the separator 230 can be bonded to the positive electrode 220 and / or the negative electrode 240 without a high-pressure pressing process.

[0119] As a result, for example, even when the positive electrode active material layer 224 and / or the negative electrode active material layer 244 contain an organic active material, the positive electrode active material layer 224 and / or the negative electrode active material layer 244 can have a porosity of 20% or more. As described above, when the porosity of the positive electrode active material layer 224 and / or the negative electrode active material layer 244 is 20% or more, the resulting energy storage cell 112 has a high ratio of the capacity of the positive electrode active material layer 224 and / or the negative electrode active material layer 244 to the theoretical capacity. The ratio of the capacity of the positive electrode active material layer 224 and / or the negative electrode active material layer 244 to the theoretical capacity is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more.

[0120] The solid electrolyte layer is produced, for example, by applying a slurry containing the materials constituting the solid electrolyte layer and a solvent onto a smooth support plate and then drying the slurry. Examples of the solvent include various solvents and mixtures thereof. While the type of the solvent is not particularly limited, examples of the solvent include N-methylpyrrolidone (NMP), water, and methanol.

[0121] The polymer solid electrolyte constituting the solid electrolyte layer is, for example, 1×10 -4 A polymer material having an ionic conductivity of [S / cm] or more is used. When an organic compound is used as the positive electrode active material and / or the negative electrode active material of the power storage cell 112, at least one of the type, composition, and molecular weight of the polymer material may be determined so that the ratio of the Young's modulus of the polymer material to the Young's modulus of the organic compound is 0.7 to 1.3.

[0122] This further suppresses a decrease in the porosity of the active material during the manufacturing process or use of the energy storage cell 112. When the solid electrolyte layer is mainly made of a polymer solid electrolyte, the pressure inside the energy storage cell 112 during use is usually about 0.1 to 0.2 [MPa]. On the other hand, when the solid electrolyte layer is mainly made of an inorganic solid electrolyte, the pressure inside the energy storage cell during use is usually increased to about 500 [MPa].

[0123] Examples of the polymer solid electrolyte constituting the solid electrolyte layer include polyethylene oxide (PEO), poly(3,4-ethylenedioxythiophene) (PEDOT), and at least one compound selected from derivatives thereof. The solid electrolyte layer may be substantially composed of a single polymer solid electrolyte, or may contain two or more types of polymer solid electrolytes.

[0124] (Negative electrode) In this embodiment, the negative electrode current collector 242 holds the negative electrode active material layer 244. Examples of materials for the negative electrode current collector 242 include copper, aluminum, stainless steel, nickel, titanium, and alloys thereof.

[0125] The negative electrode current collector 242 may include a conductive resin. The negative electrode current collector 242 may be a conductive resin. In one embodiment, the conductive resin includes a conductive polymer. In another embodiment, the conductive resin may be a polymer including a conductive filler.

[0126] The negative electrode current collector 242 may have a configuration similar to that of the positive electrode current collector 222. For example, the negative electrode current collector 242 includes a conductive layer containing a conductive material and a support layer that supports the conductive layer. The support layer is made of a material that has a lower density than metal. The support layer may also be made of a material that has a lower density than aluminum. For example, the support layer is made of resin. This can reduce the weight of the energy storage cell 112.

[0127] When a carrier metal is used as the negative electrode active material, the carrier metal can also serve as a current collector. For example, when the carrier metal of the power storage cell 112 is lithium and the negative electrode active material is lithium metal, the lithium metal is used as a current collector. In this case, the power storage cell 112 does not need to include the negative electrode current collector 242.

[0128] The negative electrode current collector 242 may be in the form of a foil (sometimes called a plate or film), a mesh, or a perforated plate. The thickness of the negative electrode current collector 242 is not particularly limited, but may be 1 to 200 μm. The thickness of the negative electrode current collector 242 may be 4 to 20 μm, or may be 6 to 10 μm.

[0129] In this embodiment, the negative electrode active material layer 244 is formed on at least one surface of the negative electrode current collector 242. The thickness of the negative electrode active material layer 244 per surface of the negative electrode current collector 242 may be 0 to 200 μm, or may be 1 to 100 μm.

[0130] The negative electrode active material layer 244 includes, for example, a negative electrode active material and a binding material (sometimes referred to as a binder). The negative electrode active material layer 244 may further include at least one of an electrically conductive material and an ion-conductive material. The negative electrode active material layer 244 may include a negative electrode active material and an ion-conductive material. This can prevent the ion conduction path and / or the electron conduction path formed inside the negative electrode active material layer 244 from being broken.

[0131] In one embodiment, the negative electrode active material layer 244 is produced by applying a slurry containing the materials constituting the negative electrode active material layer 244 and an organic solvent to at least one surface of the negative electrode current collector 242 and then drying the slurry. Examples of the solvent include various solvent substances and mixtures thereof. The type of the solvent substance is not particularly limited, but examples of the solvent substance include N-methylpyrrolidone (NMP) and water.

[0132] In another embodiment, the negative electrode active material layer 244 is formed by mixing materials constituting the negative electrode active material layer 244, forming the mixture into a sheet, and pressing the sheet-like mixture onto at least one surface of the negative electrode current collector 242. When an organic compound is used as the negative electrode active material, the negative electrode current collector 242 and the negative electrode active material layer 244 are pressed together so as not to apply excessive pressure to the negative electrode active material layer 244 in the above-mentioned pressing step.

[0133] For example, when a coater is used to coat the precursor material of the negative electrode active material layer 244 onto the negative electrode current collector 242, the pressure applied to the precursor material of the negative electrode active material layer 244 is adjusted. For example, the coating gap of the coater is set to 180 μm or more. The coating gap may be set to 200 μm or more. This prevents the ion conduction paths and / or electron conduction paths in the negative electrode active material layer 244 from being broken.

[0134] When an organic compound is used as the negative electrode active material, the ratio of the volume of the organic compound functioning as the negative electrode active material to the volume of the negative electrode active material layer 244 (sometimes referred to as the active material volume ratio) may be 60% or more. The ratio of the volume of the organic compound functioning as the negative electrode active material to the volume of the negative electrode active material layer 244 is preferably 60 to 80%, and more preferably 65 to 75%.

[0135] When the negative electrode active material layer 244 is pressed under high pressure, the ratio of the volume of the organic compound functioning as the negative electrode active material to the volume of the negative electrode active material layer 244 exceeds 80%. If this ratio exceeds 80%, the ion conduction paths become narrower or are cut off. As a result, the capacity of the negative electrode active material layer 244 decreases. The high pressure may mean 50 MPa or more, 100 MPa or more, or 500 MPa or more.

[0136] On the other hand, if the ratio of the volume of the organic compound functioning as the negative electrode active material to the volume of the negative electrode active material layer 244 is less than 60%, the conductivity of carrier ions will be good, but the density of the negative electrode active material will be low and the mass of the positive electrode active material contained in the negative electrode active material layer 244 will be low, resulting in a decrease in the capacity of the negative electrode active material layer 244.

[0137] The active material volume ratio in the negative electrode active material layer 244 is derived by the same procedure as the active material volume ratio in the positive electrode active material layer 224. For example, the active material volume ratio in the negative electrode active material layer 244 is determined based on the results of observation using a three-dimensional scanning electron microscopy (SEM).

[0138] The active material volume fraction in the negative electrode active material layer 244 is determined, for example, by the magnitude of pressure applied to the negative electrode active material layer 244 during the manufacturing process of the energy storage cell 112. As the pressure applied to the negative electrode active material layer 244 during the manufacturing process of the energy storage cell 112 increases, the active material volume fraction in the negative electrode active material layer 244 increases. The relationship between the magnitude of the pressure applied to the negative electrode active material layer 244 and the degree of increase in the active material volume fraction in the negative electrode active material layer 244 differs depending on, for example, the type of organic active material.

[0139] Therefore, for example, when an organic compound is used as the negative electrode active material, the maximum value of the pressure applied to the negative electrode active material layer 244 during the manufacturing process of the storage cell 112 is adjusted or controlled so that the volume ratio of the active material in the negative electrode active material layer 244 included in the manufactured storage cell 112 is 80% or less. This prevents the occurrence of a phenomenon in which the actual capacity of the negative electrode and / or battery is significantly reduced compared with the theoretical capacity of the negative electrode and / or battery.

[0140] Furthermore, the smaller the Young's modulus of the negative electrode active material layer 244, the greater the degree of increase in the active material volume ratio when a high voltage is applied to the negative electrode active material layer 244. Therefore, when the negative electrode active material is an organic compound, the Young's modulus of the negative electrode active material layer 244 may be adjusted to be approximately the same as the Young's modulus of the separator 230. For example, when the separator 230 is mainly composed of a polymer solid electrolyte and the negative electrode active material is an organic compound, the material and / or manufacturing conditions of the negative electrode active material layer 244 are determined so that the ratio of the Young's modulus of the polymer solid electrolyte to the Young's modulus of the negative electrode active material is 0.7 to 1.3.

[0141] The Young's modulus is measured, for example, by a bending test specified in JIS K 7171. In the bending test, the strain rate is set to about 1% / min.

[0142] There is no particular limitation on the Young's modulus of the negative electrode active material layer 244. For example, when the pressure applied to the negative electrode active material layer 244 in the manufacturing process of the energy storage cell 112 is relatively small, the material of the negative electrode active material layer 244 can be determined arbitrarily without considering the Young's modulus of the negative electrode active material layer 244.

[0143] As will be described later, a foil of a carrier metal such as lithium metal may be used as the negative electrode active material layer. In this case, the material for the negative electrode active material layer may be determined without taking into consideration the Young's modulus of the negative electrode active material layer.

[0144] (Negative electrode active material) As the negative electrode active material contained in the negative electrode active material layer 244, various materials capable of absorbing and releasing carrier ions of the power storage cell 112 are used. The negative electrode active material may be an inorganic compound or an organic compound. These negative electrode active materials may be used alone, or two or more types of negative electrode active materials may be combined. For example, a metal foil capable of releasing carrier ions of the power storage cell 112 is used as the negative electrode active material layer 244. This improves the mass energy density of the power storage cell 112.

[0145] When the negative electrode current collector 242 includes a conductive layer containing a conductive material and a support layer supporting the conductive layer, similar to the positive electrode current collector 222, according to one embodiment, a metal (e.g., Li metal) capable of releasing carrier ions of the power storage cell 112 is used as the negative electrode active material. In this case, the negative electrode active material contained in the negative electrode active material layer 244 is composed almost entirely of the metal. In other embodiments, the negative electrode active material may be composed mainly of one or more types of organic compounds. The negative electrode active material may also include an inorganic compound. For example, 80 mass % or more of the negative electrode active material contained in the negative electrode active material layer 244 is composed of an organic compound.

[0146] Examples of inorganic compounds used as the negative electrode active material (sometimes referred to as inorganic negative electrode active materials) include (i) carrier metals and alloys containing carrier metals, (ii) tin, silicon, and alloys containing tin, silicon, and these, (iii) silicon oxides, and (iv) titanium oxides. For example, when the power storage cell 112 is a lithium secondary battery, metallic lithium, lithium titanium oxide (LTO), and the like are used as the negative electrode active material. When a material not containing a carrier metal is used as the negative electrode active material, the material may be pre-doped with a carrier metal.

[0147] The organic compound used as the negative electrode active material (sometimes referred to as an organic negative electrode active material) may be at least one compound selected from the group consisting of aromatic heterocyclic compounds and derivatives thereof, and compounds containing structures or structural units derived therefrom. When the organic negative electrode active material is a compound containing the above structural units, its degree of polymerization may be 100 or less. The above derivatives may be compounds in which one or more hydrogen atoms have been substituted with a ketone group, an OH group, an OM group (M is a metal. Examples of M include a battery carrier metal, an alkali metal, and an alkaline earth metal), a nitro group, or the like.

[0148] As described above, the negative electrode active material layer 244 may include a foil-shaped carrier metal. For example, the negative electrode active material layer 244 includes a lithium metal foil. This provides the carrier metal to the energy storage cell 112. The thickness of the metal foil may be 1 to 200 μm, 10 to 100 μm, or 20 to 50 μm. The thickness and / or mass of the metal foil may be determined depending on the content of the positive electrode active material in the positive electrode active material layer 224.

[0149] (Materials other than negative electrode active material) The binder material contained in the negative electrode active material layer 244 binds the materials constituting the negative electrode active material layer 244 together and maintains the electrode shape of the negative electrode 240. As the binder material, for example, various polymer materials are used. Examples of the polymer materials include carboxymethyl cellulose, styrene-butadiene rubber, polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), polyacrylic acid, polyethylene oxide (PEO), poly(3,4-ethylenedioxythiophene) (PEDOT), and derivatives thereof.

[0150] The binder material may be a material that dissolves in a solvent in which the solubility of the organic negative electrode active material is greater than a predetermined value. The solubility of the binder material in the solvent may be equal to or greater than the solubility of the organic negative electrode active material in the solvent. This facilitates the disassembly process of the storage cell 112, for example, when reusing the constituent materials of the storage cell 112.

[0151] The conductive material contained in the negative electrode active material layer 244 improves the conductivity of the negative electrode active material layer 244, thereby reducing the resistance of the negative electrode 240. The conductive material is not particularly limited as long as it is a material that has electronic conductivity. Examples of conductive materials include carbon-based materials, metal-based materials, and conductive polymer materials. These conductive materials may be used alone, or two or more conductive additives may be used in combination.

[0152] Examples of carbon-based materials include graphite, carbon black (e.g., acetylene black, ketjen black, etc.), coke, amorphous carbon, carbon fiber, carbon nanotubes, graphene, etc. Examples of metal-based materials include aluminum, gold, silver, copper, iron, platinum, chromium, tin, indium, titanium, nickel, etc. Examples of conductive polymer materials include polyphenylene derivatives, etc.

[0153] The conductive material may be a material that dissolves in a solvent in which the solubility of the organic negative electrode active material is greater than a predetermined value. The solubility of the binder material in the solvent may be equal to or greater than the solubility of the organic negative electrode active material in the solvent. This facilitates the disassembly process of the storage cell 112, for example, when reusing the constituent materials of the storage cell 112.

[0154] The conductive material contained in the negative electrode active material layer 244 improves the conductivity of carrier ions in the negative electrode active material layer 244. Examples of the conductive material include various solid electrolytes. Examples of the solid electrolyte include sulfide-based solid electrolytes, oxide-based solid electrolytes, and polymer solid electrolytes. Examples of the conductive material include polymer solid electrolytes. Examples of the polymer solid electrolyte include at least one compound selected from polyethylene oxide (PEO), poly(3,4-ethylenedioxythiophene) (PEDOT), and derivatives thereof.

[0155] As described above, in this embodiment, separator 230 includes a polymer solid electrolyte. The type of polymer solid electrolyte used as the conductive material may be the same as or different from the type of polymer solid electrolyte included in separator 230.

[0156] The conductive material may be a material that dissolves in a solvent in which the solubility of the organic negative electrode active material is greater than a predetermined value. The solubility of the conductive material in the solvent may be equal to or greater than the solubility of the organic negative electrode active material in the solvent. This facilitates the disassembly process of the storage cell 112, for example, when reusing the constituent materials of the storage cell 112.

[0157] The positive electrode case 212 may be an example of a casing. The negative electrode case 214 may be an example of a casing. The positive electrode 220 may be an example of an electrode. The positive electrode current collector 222 may be an example of a current collector. The positive electrode active material layer 224 may be an example of an active material layer. The negative electrode 240 may be an example of an electrode. The negative electrode current collector 242 may be an example of a current collector. The negative electrode active material layer 244 may be an example of an active material layer. The structure 260 may be an example of an electrode structure. The organic active material may be an example of an organic compound. The organic positive electrode active material may be an example of an organic compound. The organic negative electrode active material may be an example of an organic compound.

[0158] (An example of another embodiment) In this embodiment, the details of the storage cell 112 have been described using the example where the storage cell 112 is a coin-type secondary battery. However, the type, structure, etc. of the storage cell 112 are not limited to this embodiment. In another embodiment, the storage cell 112 may be a cylindrical battery including a wound electrode body in which a positive electrode, a separator, and a negative electrode are wound in a spiral shape. In yet another embodiment, the storage cell 112 may be a laminated battery in which a laminated electrode body in which positive electrodes and negative electrodes are alternately stacked with separators sandwiched between them is sealed with a laminate.

[0159] In this embodiment, the details of the energy storage cell 112 have been described using as an example a case where the anode 240 has the anode current collector 242 and the anode active material layer 244. However, the anode of the energy storage cell 112 is not limited to this embodiment. In other embodiments, a foil-shaped carrier metal functions as the anode current collector 242 and the anode active material layer 244. For example, when the energy storage cell 112 is a lithium metal secondary battery, metallic lithium can be used as the anode.

[0160] In this embodiment, the details of the energy storage cell 112 have been described using as an example a case in which the positive electrode current collector 222 has (i) a conductive layer containing a conductive material and (ii) a support layer that supports the conductive layer, the positive electrode active material layer 224 mainly contains an organic compound as an active material, and the negative electrode 240 has an arbitrary configuration. However, the negative electrode of the energy storage cell 112 is not limited to this embodiment.

[0161] In another embodiment, the negative electrode current collector 242 has (i) a conductive layer containing a conductive material and (ii) a support layer supporting the conductive layer, the negative electrode active material layer 244 mainly contains an organic compound as an active material, and the positive electrode 220 may have any configuration. In still another embodiment, the positive electrode current collector 222 and the negative electrode current collector 242 have (i) a conductive layer containing a conductive material and (ii) a support layer supporting the conductive layer, and the positive electrode active material layer 224 and the negative electrode active material layer 244 mainly contain an organic compound as an active material.

[0162] Fig. 3 schematically shows another example of the energy storage cell 112. The energy storage cell 112 described with reference to Fig. 3 differs from the energy storage cell 112 described with reference to Fig. 2 in that a liquid or gel electrolyte 350 is accommodated inside the space formed by the positive electrode case 212 and the negative electrode case 214, in addition to a metal spring 218, a positive electrode 220, a separator 230, and a negative electrode 240, and in that a material other than a solid electrolyte may be used for the separator 230. Except for the above differences, the energy storage cell 112 described with reference to Fig. 3 may have a similar configuration to the energy storage cell 112 described with reference to Fig. 2.

[0163] A known electrolytic solution or gel electrolyte may be used as the liquid or gel electrolyte 350. A known separator may be used as the separator 230.

[0164] The positive electrode current collector 222 will be described in detail with reference to FIGS. 4, 5, and 6. As described above, the negative electrode current collector 242 may have a similar configuration to the positive electrode current collector 222. FIG. 4 schematically shows a cross-sectional view of a current collector 400, which is an example of the positive electrode current collector 222. FIG. 5 schematically shows an example of a cross-sectional view of a current collector 500, which is an example of the positive electrode current collector 222. FIG. 6 schematically shows an example of a cross-sectional view of a current collector 600, which is an example of the positive electrode current collector 222.

[0165] 4 , the current collector 400 includes a support layer 420, a conductive layer 442, and a conductive layer 444. In this embodiment, the support layer 420 has a first plane 422, a second plane 424, and a side surface 426. In this embodiment, the conductive layer 442 is disposed on the first plane 422 of the support layer 420. The conductive layer 444 is disposed on the second plane 424 of the support layer 420.

[0166] In this embodiment, the support layer 420 supports the conductive layer 442 and the conductive layer 444. This prevents damage to the conductive layer 442 and the conductive layer 444. The density of the support layer 420 is lower than the density of the conductive layer 442 or the conductive layer 444. For example, the support layer 420 is made of a material having a density lower than the density of the conductive layer 442 or the conductive layer 444. The support layer 420 may be a sheet-shaped resin material.

[0167] The conductivity of support layer 420 is not particularly limited, but the conductivity of support layer 420 may be lower than the conductivity of conductive layer 442 or conductive layer 444. The thickness of support layer 420 is not particularly limited, but the thickness of support layer 420 may be greater than the thickness of conductive layer 442 or conductive layer 444. As the thickness of support layer 420 increases, the mass of support layer 420 also increases. Therefore, when support layer 420 is made of a sheet-like resin material, the thickness of support layer 420 may be 10 μm or less, preferably 7 μm or less, and more preferably 5 μm or less.

[0168] In this embodiment, the conductive layer 442 and the conductive layer 444 include a conductive material having a resistivity of 8.0×10 -8 The conductive material may be a material having a resistivity of [Ω·m] or more. The conductive material may be a metal. Examples of the metal include aluminum, stainless steel, nickel, and alloys thereof. Examples of stainless steel include SUS-430 and SUS-304. The conductive material may be aluminum.

[0169] The thickness of conductive layer 442 and / or conductive layer 444 (shown as the length in the vertical direction in the drawing) may be 0.05 μm to 7 μm. The thickness of conductive layer 442 and / or conductive layer 444 may be 0.05 μm to 5 μm, 0.1 μm to 3 μm, 0.1 μm to 2 μm, or 0.5 μm to 1 μm. The thickness of conductive layer 442 and / or conductive layer 444 may be 0.05 μm to 4 μm, 0.05 μm to 3 μm, 0.05 μm to 2 μm, or 0.05 μm to 1 μm. The thickness of conductive layer 442 and / or conductive layer 444 is preferably 0.1 μm to 5 μm, and more preferably 0.1 μm to 1 μm. Even relatively thin commercially available aluminum foils have a thickness of 6 to 10 μm. Therefore, by providing current collector 400 with conductive layer 442 and / or conductive layer 444 having a thickness of 5 μm or less, the energy density per unit mass of the storage cell [Wh / kg-storage cell] is improved compared to when commercially available aluminum foils are used as conductive layer 442 and / or conductive layer 444.

[0170] At least one of conductive layer 442 and / or conductive layer 444 may be an aluminum layer or foil having the above-mentioned thickness. The aluminum layer or foil may be disposed on the surface of support layer 420 by pasting, or may be formed on the surface of support layer 420 by vapor deposition, deposition, or the like.

[0171] When the thickness of the conductive layer 442 and / or the conductive layer 444 is 7 μm or less, the mass energy density of the power storage cell 112 is improved. When the thickness of the conductive layer 442 and / or the conductive layer 444 is 5 μm or less, the mass energy density of the power storage cell 112 is further improved. When the thickness of the conductive layer 442 and / or the conductive layer 444 is 1 μm or less, the mass energy density of the power storage cell 112 is significantly improved. Generally, when the thickness of the conductive layer is 0.1 μm or less or less than 0.1 μm, the conductive layer 442 and / or the conductive layer 444 is easily damaged. However, the conductive layer 442 and the conductive layer 444 according to this embodiment are supported by the support layer 420. Therefore, even when the thickness of the conductive layer 442 and / or the conductive layer 444 is approximately 0.05 to 0.1 μm, damage to the conductive layer 442 and / or the conductive layer 444 can be suppressed.

[0172] When the support layer 420 is made of a resin material, the resistance to breakage of the conductive layers 442 and 444 in the above-described fixing step is approximately the same as the resistance to breakage of the current collector 400 in the above-described fixing step. The degree of resistance to breakage of the current collector 400 is determined, for example, by a tensile test of a sample cut into a strip from the current collector 400, including the support layer 420, the conductive layers 442, and the conductive layers 444. Note that if a portion of the conductive layers 442 and 444 breaks during the fixing step, the electrical resistance of the conductive layers 442 and 444 may increase compared to before the fixing step was performed.

[0173] The size and shape of the sample are, for example, as disclosed in "Testing Machine Academia" (Keyence Corporation, [online]https: / / www.keyence.co.jp / ss / products / recorder / testing-machine / material / tension.jsp (April 6, 2022)), a rectangular overall shape measuring 20 mm wide x 100 mm long, with a tapered region measuring 40 mm long in the center. The tapered region has a narrow region measuring 10 mm wide x 20 mm long in the center. One end of the tapered region and one end of the narrow region are connected, and the other end of the tapered region and the other end of the narrow region are connected.

[0174] The tensile test is carried out, for example, in accordance with IPC-TM-650 or in accordance with IPC-TM-650. Specifically, fixtures are attached to both ends of the sample, and the sample is pulled up and down to measure the tensile strength of the sample. The pulling speed is set to, for example, 2 inches / min (50.8 mm / min). The tensile strength under the above conditions may be expressed, for example, as Ts(50). The number in parentheses above indicates the pulling speed.

[0175] The tensile strength Ts(50) of the above sample may be 360 MPa or more. The tensile strength Ts(50) may be 450 MPa or more.

[0176] 5, current collector 500 differs from current collector 400 described in relation to FIG. 4 in that a plurality of through-holes 522 are formed in support layer 420. Current collector 500 may have the same configuration as current collector 400, except for the above-mentioned difference.

[0177] When a simple metal foil is used as a current collector, forming through holes in the current collector may result in bending of the metal foil, making it difficult to form the through holes. Therefore, forming through holes in the current collector is difficult, particularly when active material layers are formed on both sides of the metal foil. In contrast, according to this embodiment, the conductive layer is supported by a support layer such as a resin sheet, so that the current collector is relatively less likely to bend even when through holes are formed in the current collector.

[0178] According to this embodiment, a portion of the plurality of through holes 522 is filled with a conductive material 546. The conductive material 546 electrically connects the conductive layer 442 and the conductive layer 444.

[0179] The circle-equivalent diameter (sometimes referred to as the circle-equivalent diameter) of each of the plurality of through-holes 522 may be 15 μm to 150 μm. The interval between two adjacent through-holes 522 may be 30 μm to 250 μm.

[0180] If the equivalent circle diameter of through hole 522 is smaller than 15 μm, when a conductive layer (sometimes referred to as an internal conductive layer) for electrically connecting conductive layer 442 and conductive layer 444 is formed on the inner wall surface of through hole 522, the thickness of the conductive layer formed on the inner wall surface becomes small, resulting in an increase in the electrical resistance of the conductive layer. On the other hand, if the equivalent circle diameter of through hole 522 is larger than 150 μm, when a conductive layer for electrically connecting conductive layer 442 and conductive layer 444 is formed on the inner wall surface of through hole 522, the total amount of the conductive layer becomes small, resulting in an increase in the electrical resistance of conductive layer 442 and conductive layer 444. Furthermore, if the equivalent circle diameter of through hole 522 is larger than 150 μm, the strength of current collector 500 may be insufficient.

[0181] The circle-equivalent diameter (sometimes referred to as the circle-equivalent diameter) of each of the plurality of through holes 522 may be 15 μm to 150 μm, 15 μm to 50 μm, or 15 to 35 μm. The circle-equivalent diameter of through holes 522 that are not filled with conductive material 546 may be 15 μm to 50 μm, or 15 to 35 μm. The circle-equivalent diameter of through holes 522 that are filled with conductive material 546 is not particularly limited. This can suppress breakage of conductive layers 442 and 444, while achieving weight reduction of current collector 500.

[0182] The ratio of the total area of the plurality of through holes 522 on one surface of the current collector 500 to the outer area of the one surface of the current collector 500 may be 30% or more. The ratio of the total area of the through holes 522 on one surface of the current collector 500 that are not filled with the conductive material 546 to the outer area of the one surface of the current collector 500 may be 30% or more. This can reduce the weight of the current collector 500 while suppressing breakage of the conductive layers 442 and 444.

[0183] 6, current collector 600 differs from current collector 500 described in relation to FIG. 5 in that current collector 600 has a plurality of through holes 620 formed therein, penetrating support layer 420, conductive layer 442, and conductive layer 444. Current collector 500 may have the same configuration as current collector 500, except for the above-mentioned differences.

[0184] In this embodiment, a conductive layer 642 is formed on the surface of at least some of the inner wall portions 622 of the plurality of through holes 620. The conductive layer 642 includes a conductive material. The conductive material may be a metal. Examples of the metal include aluminum, stainless steel, nickel, and alloys thereof. Examples of stainless steel include SUS-430 and SUS-304. The conductive material may be aluminum.

[0185] The conductive layer 642 may have three or more layers with different main components. The conductive layer 642 may include an auxiliary layer, a target layer, and a protective layer. For example, a first layer mainly composed of nickel is formed on the surface of the inner wall portion 622 of the through hole 620, a second layer mainly composed of copper is formed on the first layer, and a chromate coating is formed on the second layer. The thickness of the first layer may be about 0.1 μm, the thickness of the second layer may be about 1 μm, and the thickness of the chromate coating may be about 0.3 μm.

[0186] The conductive layer 642 may electrically connect the conductive layer 442 and the conductive layer 444. The conductive layer 642 may be an example of an internal conductive layer.

[0187] 7 schematically illustrates an example of a laminated structure 760. In the embodiment described in relation to FIG. 2, the structure 260 is an example in which the positive electrode 220, the separator 230, and the negative electrode 240 are laminated in this order, and details of the structure (sometimes referred to as an electrode structure) that constitutes part of the battery are described. However, the electrode structure is not limited to the structure 260.

[0188] 7 and 8, details of a laminated structure 760, which is another example of an electrode structure, will be described. FIG. 7 schematically shows an example of a cross section of the laminated structure 760. FIG. 8 schematically shows an example of an electrical connection relationship between the electrodes of the laminated structure 760. The laminated structure 760 may have a similar configuration to the structure 260, except that it includes a plurality of positive electrodes 220, a plurality of separators 230, and a plurality of negative electrodes 240.

[0189] In this embodiment, the stacked structure 760 includes one or more positive electrodes 220, one or more negative electrodes 240, and one or more separators 230 disposed between each of the one or more positive electrodes 220 and each of the one or more negative electrodes 240. As shown in Fig. 7 , the stacked structure 760 includes a plurality of positive electrodes 220, a plurality of negative electrodes 240, and a plurality of separators 230 disposed between each of the plurality of positive electrodes 220 and each of the plurality of negative electrodes 240.

[0190] Except for the positive electrode 220 arranged on the outermost side of the laminated structure 760, each of the multiple positive electrodes 220 has a positive electrode active material layer 224 arranged on both sides of the positive electrode current collector 222. The positive electrode 220 arranged on the outermost side of the laminated structure 760 has a positive electrode active material layer 224 arranged on one side of the positive electrode current collector 222.

[0191] Except for the negative electrode 240 arranged on the outermost side of the laminated structure 760, each of the multiple negative electrodes 240 has a negative electrode active material layer 244 arranged on both sides of the negative electrode current collector 242. The negative electrode 240 arranged on the outermost side of the laminated structure 760 has a negative electrode active material layer 244 arranged on one side of the negative electrode current collector 242.

[0192] 7, the stacked structure 760 includes a positive electrode connecting portion 820 that electrically connects each of the multiple positive electrodes 220. According to this embodiment, the positive electrode connecting portion 820 has a lead 822 and a sub-lead 824 that sandwich and support a portion of the multiple positive electrodes 220. This improves the strength of the connection points of the multiple positive electrodes 220.

[0193] At the positive electrode connection portion 820, the multiple positive electrodes 220 may be physically connected by welding. Examples of welding methods include ultrasonic welding, resistance welding, and laser welding. The planar dimensions of the sub-lead 824 may be larger than the planar dimensions of the welded area. The planar dimensions of the lead 822 may be larger than the planar dimensions of the sub-lead 824.

[0194] The lead 822 is made of, for example, a plate-shaped conductive material. The thickness of the lead 822 may be 10 to 300 μm, preferably 30 to 200 μm, and more preferably 50 to 100 μm.

[0195] The material of the sub-lead 824 is not particularly limited. The sub-lead 824 is made of, for example, aluminum, nickel, stainless steel, or an alloy thereof. The sub-lead 824 may be made of a resin material such as polypropylene or polyimide. The thickness of the sub-lead 824 may be 10 to 300 μm, preferably 30 to 200 μm, and more preferably 50 to 100 μm.

[0196] Similarly, the laminated structure 760 includes a negative electrode connecting portion 840 that electrically connects each of the multiple negative electrodes 240. According to the present embodiment, the negative electrode connecting portion 840 has a lead 842 and a sub-lead 844 that sandwich and support a portion of the multiple positive electrodes 220. This improves the strength of the connection points of the multiple negative electrodes 240.

[0197] At the negative electrode connection portion 840, the multiple negative electrodes 240 may be physically connected by welding. Examples of welding methods include ultrasonic welding, resistance welding, and laser welding. The planar dimensions of the sub-lead 844 may be larger than the planar dimensions of the welded area. The planar dimensions of the lead 842 may be larger than the planar dimensions of the sub-lead 844.

[0198] The lead 842 is made of, for example, a plate-shaped conductive material. The thickness of the lead 842 may be 10 to 300 μm, preferably 30 to 200 μm, and more preferably 50 to 100 μm.

[0199] The material of the sub-lead 844 is not particularly limited. The sub-lead 844 is made of, for example, aluminum, nickel, stainless steel, or an alloy thereof. The sub-lead 844 may be made of a resin material such as polypropylene or polyimide. The thickness of the sub-lead 844 may be 10 to 300 μm, preferably 30 to 200 μm, and more preferably 50 to 100 μm.

[0200] The lead 822 and the sub-lead 824 may be an example of a positive electrode support portion. The lead 842 and the sub-lead 844 may be an example of a negative electrode support portion.

[0201] (An example of another embodiment) In the present embodiment, the details of the laminated structure 760 have been described using as an example a case in which the laminated structure 760 includes the positive electrode connecting portion 820 and the negative electrode connecting portion 840. However, the laminated structure 760 is not limited to this embodiment. In other embodiments, the laminated structure 760 may include at least one of the positive electrode connecting portion 820 and the negative electrode connecting portion 840.

[0202] FIG. 9 schematically shows an example of a method for manufacturing a storage cell 112. In this embodiment, a method for producing a storage cell 112 including a stacked structure 760 is described. According to this embodiment, first, in step 912 (step may be abbreviated as S), a plurality of positive electrodes 220 and a plurality of negative electrodes 240 are prepared. Details of the method for preparing the positive electrodes 220 or the negative electrodes 240 will be described later. Also, in S914, a plurality of separators 230 are prepared. Next, in S920, the positive electrodes 220, the separators 230, and the negative electrodes 240 are stacked in this order. In this way, the stacked structure 760 is produced.

[0203] Next, in S932, the plurality of positive electrodes 220 of the laminated structure 760 are electrically connected. Furthermore, in S934, the plurality of negative electrodes 240 of the laminated structure 760 are electrically connected. Thereafter, in S940, the laminated structure 760 is housed inside the positive electrode case 212 and the negative electrode case 214, and the energy storage cell 112 is assembled.

[0204] 10 schematically illustrates an example of a method for manufacturing a positive electrode 220. According to this embodiment, first, in S1010, a positive electrode current collector 222 is prepared. Next, in S1022, a positive electrode slurry containing a positive electrode active material and a solvent is prepared. Next, in S1024, the positive electrode slurry is applied to the surface of the positive electrode current collector 222. The positive electrode slurry is then dried. As a result, a positive electrode active material layer 224 is formed on the surface of the positive electrode current collector 222.

[0205] Next, in S1030, the positive electrode active material layer 224 and the positive electrode current collector 222 are fixed to each other. More specifically, pressure is applied to the stacked positive electrode active material layer 224 and positive electrode current collector 222 to fix the positive electrode active material layer 224 and the positive electrode current collector 222 to each other.

[0206] In one embodiment, the pressure in the fixing step is set or adjusted so that (i) the rate of change in the electrical resistance (resistivity) of the current collector before and after pressure is applied to the active material layer and the current collector is within 50%, or (ii) the absolute value of the difference in the electrical resistance (resistivity) of the current collector before and after pressure is applied to the active material layer and the current collector is 1 [Ω] or less. The pressure in the fixing step may be set or adjusted so that the absolute value of the difference is less than 1 [Ω]. The pressure in the fixing step is preferably set or adjusted so that the absolute value of the difference is 500 m[Ω] or less, and more preferably set or adjusted so that the absolute value of the difference is 100 m[Ω] or less. This prevents breakage of the conductive layer of the current collector. The electrical resistance of the current collector can be measured, for example, by a four-terminal, four-probe method using a low resistivity meter (Loresta-GX MCP-T700, manufactured by Nitto Seiko Analytech Co., Ltd.).

[0207] In another embodiment, the pressure in the fixing step is set or adjusted so that (i) the value of the second voltage measured by applying a current to the conductive layer of the current collector after the pressure has been applied minus (ii) the value of the first voltage measured by applying a current to the conductive layer of the current collector before the pressure has been applied is less than 100 mV. This prevents breakage of the conductive layer of the current collector. The first and second voltages are measured, for example, by a low resistivity meter having a voltage measurement function and an output function. The first and second voltages can be measured, for example, by a four-terminal, four-probe method using a low resistivity meter (Loresta-GX MCP-T700, manufactured by Nitto Seiko Analytech Co., Ltd.).

[0208] In another embodiment, the pressure in the fixing step is set or adjusted so that the porosity of the active material layer after pressure application is 20 to 40%, thereby suppressing breakage of the conductive layer of the current collector.

[0209] For example, when a roll press is used to apply pressure to the positive electrode active material layer 224 and the positive electrode current collector 222, the roll press is controlled so that the linear pressure applied to the positive electrode active material layer 224 and the positive electrode current collector 222 is 1.0 kgf / cm to 200 kgf / cm. The roll press may be controlled so that the linear pressure is 2 kgf / cm to 150 kgf / cm, or may be controlled so that the linear pressure is 10 kgf / cm to 100 kgf / cm. This produces a positive electrode current collector 222 having the above-mentioned properties. [Example]

[0210] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. Example 1 A laminated pouch-type battery was fabricated using naphthazarin dimer as the positive electrode active material by the following procedure.

[0211] (Preparation of positive electrode) First, a positive electrode current collector was prepared. The positive electrode current collector was a polyimide film (Kapton, manufactured by Toray DuPont, thickness 5 μm) with aluminum layers formed on both sides by electroless plating. The thickness of the aluminum layer was 1 μm per side. The purity of the aluminum was 99% or more. The density of the positive electrode current collector was 1.9 g / cm. 3 It was.

[0212] Next, a predetermined amount of naphthazarin dimer and a conductive material were mixed into an NMP solution containing PVdF as a binder material, and the concentration was adjusted with NMP to prepare a slurry composition. The naphthazarin dimer was synthesized by a known method. Carbon nanotubes (manufactured by Cnano Technology) were used as the conductive material. The positive electrode active material and the conductive material were previously crushed in a mortar and classified. The average particle size of the positive electrode active material based on the number was approximately 25 μm. The average particle size of the positive electrode active material was determined using a scanning electron microscope (sometimes referred to as SEM). The positive electrode active material, conductive material, and binder material were mixed in a ratio of positive electrode active material:conductive material:binder material = 95:2:3 (mass ratio). The theoretical capacity of the active material was 462 mA / g.

[0213] Next, the slurry composition was applied to one surface of a positive electrode current collector and dried. The coating amount of the active material was 3.5 g / cm. 2 It was.

[0214] Before applying pressure to the positive electrode current collector on which the active material layer was formed to bond the active material layer and the positive electrode current collector, the electrical resistance of the positive electrode current collector was measured. Specifically, a four-terminal ESP probe was contacted with the positive electrode current collector to measure the resistance value. This value was compared before and after pressing. Next, the voltage change when a current value corresponding to 1.0 C for the cell capacity was applied was roughly calculated by dividing the current value by the number of layers. The measurement terminals were separated by 5 mm.

[0215] Then, pressure was applied to the positive electrode current collector on which the active material layer was formed using a roll press to bond the active material layer and the positive electrode current collector. The linear pressure of the roll press was 60 kgf / cm, and the coating gap was 200 μm. The porosity of the active material layer after pressing was 31%.

[0216] Before cutting out a positive electrode from the positive electrode current collector with the active material layer fixed thereto, the electrical resistance of the pressed positive electrode current collector was measured using the same procedure as that performed before the active material layer and the positive electrode current collector were fixed thereto.

[0217] Next, the positive electrode current collector on which the active material layer was formed was cut into the shape of a positive electrode. This resulted in a positive electrode having a planar shape of 34 mm wide x 30 mm high, with a square tab of 10 mm wide x 10 mm high attached to one side. The planar shape of the positive electrode was approximately L-shaped.

[0218] (Preparation of negative electrode) First, a negative electrode current collector was prepared. The negative electrode current collector consisted of a polyimide film (Kapton, manufactured by Toray DuPont, 5 μm thick) with copper layers formed on both sides by electroless plating. The thickness of the copper layer was 1 μm per side. The purity of the copper was 99.9% or higher. Metallic Li (manufactured by Honjo Metals Co., Ltd., purity 99.8%, 20 μm) was used as the negative electrode active material. Metallic Li was attached to both sides of the negative electrode current collector using the pressure bonding method.

[0219] Next, the negative electrode current collector with the metallic Li attached was cut into the shape of a negative electrode. This resulted in a negative electrode with a planar shape of 37 mm wide x 32 mm high, with a square tab of 10 mm wide x 10 mm high attached to one side. The planar shape of the negative electrode was approximately L-shaped.

[0220] (Battery assembly) Next, a laminated pouch-type battery was assembled. A polypropylene sheet was used as the separator. A mixed solution of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and dimethyl ether (DME) (manufactured by Kishida Chemical Co., Ltd.) was used as the electrolyte. The ratio of LiTFSI to DME in the mixture was 1:2 (molar ratio), and the concentration of LiTFSI was 3 mol / L.

[0221] In Example 1, a laminate structure was assembled using one positive electrode, one separator, and one negative electrode. The laminate structure was then housed inside a housing, and the housing was then filled with an electrolyte solution. This resulted in a laminate pouch-type battery.

[0222] Example 2 A stacked pouch-type battery was fabricated using rubeanic acid dimer as the positive electrode active material. The stacked pouch-type battery was fabricated according to the following procedure.

[0223] (Preparation of positive electrode) First, a positive electrode current collector was prepared. Throughholes with a diameter of 30 μm were formed at 100 μm intervals in a polyimide film (Toray DuPont, Kapton, 5 μm thick) as a support layer. An aluminum layer was formed on both sides of the polyimide film with the throughholes and on the inner wall surfaces of the throughholes by electroless plating. The thickness of the aluminum layer on the flat surface of the polyimide film was 1 μm per side. The thickness of the aluminum layer formed on the inner wall surfaces of the throughholes was 0.1 μm. The purity of the aluminum was 99% or higher. The density of the positive electrode current collector was 1.9 g / cm3.

[0224] Next, a predetermined amount of rubeanic acid dimer and conductive material were mixed into an NMP solution containing PVdF as a binder material, and the concentration was adjusted with NMP to prepare a slurry composition. Carbon nanofiber (VGCF, Showa Denko K.K.) was used as the conductive material. The positive electrode active material and conductive material were previously pulverized in a mortar and classified. The average particle size based on the number of active materials was approximately 10 μm. The positive electrode active material, conductive material, and binder material were mixed in a ratio of positive electrode active material:conductive material:binder material = 88:9:3 (mass ratio). The theoretical capacity of the active material was 610 mAh / g.

[0225] Next, the slurry composition was applied to one surface of a positive electrode current collector and dried. The coating amount of the active material was 11.1 g / cm. 2 It was.

[0226] Before applying pressure to the positive electrode current collector on which the active material layer was formed to fix the active material layer and the positive electrode current collector, the electrical resistance of the positive electrode current collector was measured. The electrical resistance of the positive electrode current collector was measured using the same procedure as in Example 1.

[0227] Then, pressure was applied to the positive electrode current collector on which the active material layer was formed using a roll press to bond the active material layer and the positive electrode current collector. The linear pressure of the roll press was 100 kgf / cm, and the coating gap was 280 μm. The porosity of the active material layer after pressing was 40%.

[0228] Before cutting out the positive electrode from the positive electrode current collector with the active material layer fixed thereto, the electrical resistance of the pressed positive electrode current collector was measured. The electrical resistance of the positive electrode current collector was measured in the same manner as in Example 1.

[0229] Next, the positive electrode current collector on which the active material layer was formed was cut into the shape of a positive electrode, thereby obtaining a positive electrode having a planar shape with a square tab of 10 mm wide x 10 mm high attached to one side of a square of 37 mm wide x 32 mm high.

[0230] (Preparation of negative electrode) A negative electrode was produced in the same manner as in Example 1.

[0231] (Battery assembly) Next, a laminated pouch-type battery was assembled. A polyethylene film (9 μm, manufactured by Seigen Co., Ltd.) with an alumina coating on its surface was used as the separator. A mixed solution of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and dimethyl ether (DME) (manufactured by Kishida Chemical Co., Ltd.) was used as the electrolyte. The ratio of LiTFSI to DME in the mixture was 1:2 (molar ratio), and the LiTFSI concentration was 3 mol / L.

[0232] In Example 2, a laminate structure was assembled using four positive electrodes, seven separators, and four negative electrodes. The laminate structure was then housed inside a battery case, and the case was filled with an electrolyte. This resulted in a laminate pouch-type battery with a cell capacity of 1.0 Ah.

[0233] (Comparative Example 1) A laminated pouch-type battery was fabricated using LiNiCoMnO2 (NCM111, manufactured by Sugisugi Energy Co., Ltd.) as the positive electrode active material. The laminated pouch-type battery was fabricated in the same manner as in Example 1, except that the positive electrode material was different and the coating gap was adjusted so that the linear pressure of the roll press was 290 kgf / cm.

[0234] (Comparative Example 2) A laminated pouch-type battery was fabricated using naphthazarin dimer as the positive electrode active material. The laminated pouch-type battery was fabricated in the same manner as in Example 1, except that a 12 μm thick aluminum foil was used as the current collector, the coating gap was adjusted so that the linear pressure of the roll press was 290 kgf / cm, and a graph filter was used as the separator. The porosity of the active material layer after pressing was 21%.

[0235] (Reference example 1) A laminated pouch-type battery was fabricated using LiNiCoMnO2 (NCM111, manufactured by Sugisugi Energy Co., Ltd.) as the positive electrode active material. The laminated pouch-type battery was fabricated in the same manner as in Comparative Example 1, except that a 12 μm thick aluminum foil was used as the current collector.

[0236] (Reference example 2) A laminated pouch-type battery was fabricated using LiNiCoMnO2 (NCM111, manufactured by Sugisugi Energy Co., Ltd.) as the positive electrode active material. The laminated pouch-type battery was fabricated using the same procedure as in Reference Example 1, except that the coating gap was adjusted so that the linear pressure of the roll press was 800 kgf / cm. The porosity of the active material layer after pressing was 25%.

[0237] (evaluation) As described above, for each of Example 1, Example 2, Comparative Example 1, Comparative Example 2, Reference Example 1, and Reference Example 2, the change in electrical resistance of the current collector before and after the positive electrode pressing process (sometimes referred to as the fixing process) during the production process of each battery was measured. The capacity of each produced battery was also measured. The capacity of each battery was measured using a charge-discharge tester (TOSCAT3100, manufactured by Toyo Systems Co., Ltd.).

[0238] In Example 1, a constant current charge / discharge test was carried out in a potential range of 4.5-1.2 V (vs. Li / Li) at a current density of 20 mA / g in an atmosphere of 45° C. The charge rate and discharge rate were 0.1 C.

[0239] In Example 2, 5.5 mAh / cm under an atmosphere of 40°C 2 A constant current charge / discharge test was carried out in the potential range of 4.1-1.5 V (vs. Li+ / Li) at a current density of 0.1 C. The charge and discharge rates were 0.1 C.

[0240] In Comparative Example 1, a constant current charge / discharge test was carried out in an atmosphere of 25° C. at a current density of 30 mA / g in a potential range of 4.3-2.8 V (vs. Li / Li). The charge rate and discharge rate were 0.1 C.

[0241] In Comparative Example 2, a constant current charge / discharge test was carried out in a potential range of 4.1-1.5 V (vs. Li / Li) at a current density of 20 mA / g in an atmosphere of 40° C. The charge rate and discharge rate were 0.05 C.

[0242] In Reference Example 1, a constant current charge / discharge test was carried out in a potential range of 4.3-2.8 V (vs. Li / Li) at a current density of 30 mA / g in an atmosphere of 25° C. The charge rate and discharge rate were 0.1 C.

[0243] In Reference Example 2, a constant current charge / discharge test was carried out in a potential range of 4.3-2.8 V (vs. Li / Li) at a current density of 30 mA / g in an atmosphere of 25° C. The charge rate and discharge rate were 0.1 C.

[0244] The measurement results for each of the Examples, Comparative Examples, and Reference Examples are shown in Table 1. In Table 1, a "◎" in "Capacity" indicates that the measurement result of the battery capacity was 80% or more of the theoretical capacity. Similarly, a "◯" in "Capacity" indicates that the measurement result of the battery capacity was 70% or more but less than 80% of the theoretical capacity. A "×" in "Capacity" indicates that the measurement result of the battery capacity was less than 70% of the theoretical capacity.

[0245] In Table 1, a "good" in the "voltage change amount" column indicates that the change in the resistance value of the current collector before and after the positive electrode pressing process was 10 to 50 mV, and the rate of change in resistance value was within 50%. A "bad" in the "voltage change amount" column indicates that the change in the resistance value of the current collector before and after the positive electrode pressing process exceeded 100 mV, and the rate of change in resistance value exceeded 50%.

[0246] [Table 1]

[0247] In Examples 1 and 2, a resin material with an Al layer disposed on both sides was used as the positive electrode current collector. In Examples 1 and 2, the thickness of the Al layer was very thin and the density of the resin material was lower than that of Al, so batteries with high capacities were fabricated. As shown in Table 1, the capacities of the batteries according to Examples 1 and 2 were equal to or greater than those of the batteries according to Reference Examples 1 and 2.

[0248] (Comparison between Examples 1 and 2 and Comparative Example 1) As described above, the aluminum layers of the positive electrode current collectors in Example 1, Example 2, and Comparative Example 1 are very thin and prone to breakage. According to Examples 1 and 2, the positive electrode active material layer contains an organic compound as the active material, and the linear pressure applied in the pressing step was set or adjusted to 200 kgf / cm or less. In Examples 1 and 2, the change in voltage (or resistance value) before and after the pressing step was small, which indicates that breakage of the aluminum layer in the pressing step was suppressed.

[0249] On the other hand, in Comparative Example 1, the positive electrode active material layer contained an inorganic compound as the active material, and the linear pressure applied in the pressing process exceeded 200 kgf / cm. In Comparative Example 1, the change in voltage (or resistance value) before and after the pressing process was large, and it is presumed that the aluminum layer broke during the pressing process. For example, although the aluminum layer in Comparative Example 1 was only 1 μm thick, an inorganic active material, which is harder than an organic compound, was used as the active material, and high pressure was applied during the pressing process, which is presumed to have caused the aluminum layer to break.

[0250] (Comparison between Examples 1 and 2 and Comparative Example 2) The positive electrode active material layers of Example 1, Example 2, and Comparative Example 2 contain an organic compound as an active material. As described above, when high pressure is applied to the positive electrode active material layer in the pressing process, the capacity per unit mass of the active material may decrease. In Examples 1 and 2, the pressure applied to the positive electrode active material layer in the pressing process was set or adjusted so that the porosity of the positive electrode active material layer after pressing was within the range of 25 to 40%.

[0251] On the other hand, in Comparative Example 2, a pressure of 290 kgf / cm was applied in the pressing process, resulting in a porosity of 21% in the positive electrode active material layer after pressing. As shown in Table 1, the batteries of Examples 1 and 2 are superior to the battery of Comparative Example 2 in energy density per unit mass and / or capacity per unit mass of active material. In Comparative Example 2, an aluminum foil with a thickness of 12 μm was used as the current collector. This is thought to have suppressed breakage of the current collector during the pressing process, thereby suppressing the change in voltage (or resistance value) before and after the pressing process.

[0252] As described above, even when the current collector has a conductive layer with a thickness of approximately 0.05 μm to 7 μm or 0.05 μm to 5 μm, the use of an organic compound as the active material can suppress damage to the conductive layer during the current collector manufacturing process. Furthermore, when a current collector is manufactured using an organic compound as the active material, the capacity of a battery manufactured using the current collector can be improved by adjusting the pressure applied to the active material layer during the current collector manufacturing process. In this case, the pressure applied to the conductive layer is also reduced, further suppressing damage to the conductive layer.

[0253] (Charge-discharge cycle test) A charge-discharge cycle test was performed on the batteries of Example 1 and Comparative Example 2. The results of the charge-discharge cycle test (charge-discharge curves) are shown in Figure 11. In Figure 11, the solid line shows the charge-discharge curve of Example 1, and the dotted line shows the charge-discharge curve of Comparative Example 2.

[0254] 11, when the current collector includes a conductive layer and a support layer and the conductive layer is thin, the battery capacity can be improved by reducing the pressure applied to the active material layer and the current collector in the fixing step. Furthermore, when an organic compound is used as the active material, the above effect is particularly pronounced.

[0255] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0256] It should be noted that the order of execution of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and that the processes can be performed in any order unless the output of a previous process is used in a subsequent process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," etc. for convenience, this does not mean that the processes must be performed in this order.

[0257] By using one embodiment of the present invention, it is possible to improve the amount of energy per weight in a rechargeable battery, thereby realizing a lighter rechargeable battery that can store more power. Rechargeable batteries can be brought to disaster sites, for example, and used to supply energy to disaster victims, thereby contributing to the achievement of Sustainable Development Goal (SDG) 7 "Affordable and clean energy" or Goal 13 "Climate action." [Explanation of symbols]

[0258] 100 flying vehicle, 110 storage battery, 112 storage cell, 120 power control circuit, 130 electric motor, 140 propeller, 150 sensor, 160 control device, 212 positive electrode case, 214 negative electrode case, 216 sealant, 218 metal spring, 220 positive electrode, 222 positive electrode current collector, 224 positive electrode active material layer, 230 separator, 240 negative electrode, 242 negative electrode current collector, 244 negative electrode active material layer, 260 structure, 350 electrolyte, 400 current collector, 420 support layer, 422 first plane, 424 second plane, 426 side, 442 conductive layer, 444 conductive layer, 500 current collector, 522 through hole, 546 conductive material, 600 current collector, 620 Through hole, 622 inner wall portion, 642 conductive layer, 760 laminated structure, 820 positive electrode connection portion, 822 lead, 824 sub-lead, 840 negative electrode connection portion, 842 lead, 844 sub-lead

Claims

1. providing a current collector; forming an active material layer containing an organic compound as an active material on at least one surface of the current collector; bonding the active material layer and the current collector; and The current collector is a conductive layer including a conductive material; a support layer that supports the conductive layer; Equipped with the electrical conductivity of the support layer is less than the electrical conductivity of the conductive layer; the density of the support layer is less than the density of the conductive layer; The step of bonding the active material layer and the current collector includes: applying pressure to the stacked active material layer and the current collector; Including, The pressure is (i) the rate of change in electrical resistance of the current collector before and after pressure is applied to the active material layer and the current collector is within 50%, or (ii) so that the absolute value of the difference in electrical resistance of the current collector before and after pressure is applied to the active material layer and the current collector is less than 1 [Ω]; be set or adjusted, A method for producing an electrode.

2. providing a current collector; forming an active material layer containing an organic compound as an active material on at least one surface of the current collector; bonding the active material layer and the current collector; and The current collector is a conductive layer including a conductive material; a support layer that supports the conductive layer; Equipped with the electrical conductivity of the support layer is less than the electrical conductivity of the conductive layer; the density of the support layer is less than the density of the conductive layer; The step of bonding the active material layer and the current collector includes: applying pressure to the stacked active material layer and the current collector; Including, The pressure is set or adjusted so that a value obtained by subtracting (ii) a value of a first voltage measured by applying a current to the conductive layer of the current collector before the pressure is applied from a value of a second voltage measured by applying a current to the conductive layer of the current collector after the pressure is applied is less than 100 mV. A method for producing an electrode.

3. providing a current collector; forming an active material layer containing an organic compound as an active material on at least one surface of the current collector; bonding the active material layer and the current collector; and The current collector is a conductive layer including a conductive material; a support layer that supports the conductive layer; Equipped with the electrical conductivity of the support layer is lower than the electrical conductivity of the conductive layer; the density of the support layer is less than the density of the conductive layer; The step of bonding the active material layer and the current collector includes: applying pressure to the stacked active material layer and the current collector; Including, The pressure is so that the porosity of the active material layer after pressure is applied is 25 to 40%. be set or adjusted, A method for producing an electrode.

4. The step of applying pressure comprises: applying pressure to the stacked active material layer and the current collector using a roll press so that the linear pressure is 1.0 kgf / cm to 200 kgf / cm; Including, The method according to any one of claims 1 to 3.

5. The support layer is a sheet-shaped resin material. The method according to any one of claims 1 to 3.

6. the conductive layer comprises aluminum in a layer or foil form; The thickness of the layer or foil of aluminum is 0.05 μm to 5 μm. The method according to any one of claims 1 to 3.

7. providing a positive electrode and a negative electrode; providing a separator; stacking the positive electrode, the separator, and the negative electrode in this order; and The step of preparing the positive electrode and the negative electrode includes: Producing at least one of the positive electrode and the negative electrode by the method of any one of claims 1 to 3; Including, A method for producing an electrode structure.

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