JP7027190B2 - State estimation method, estimation device, system for non-aqueous lithium-type power storage element - Google Patents

Description

The present invention relates to a state estimation method and a state estimation device for a non-aqueous lithium storage element, and a system including a non-aqueous lithium storage element and a state estimation device thereof.

In recent years, from the viewpoint of energy conservation and effective use of energy aiming at conservation of global environment, power smoothing system or midnight power storage system for wind power generation, distributed power storage system for home use based on solar power generation technology, power storage for electric vehicles Systems and the like are attracting attention.
The first requirement of the batteries used in these power storage systems is high energy density. Lithium-ion batteries are being energetically developed as promising candidates for high-energy density batteries that can meet such demands.
The second requirement is that the output characteristics are high. For example, in a combination of a high efficiency engine and a power storage system (for example, a hybrid electric vehicle) or a combination of a fuel cell and a power storage system (for example, a fuel cell electric vehicle), high output discharge characteristics in the power storage system are required at the time of acceleration. There is.
Currently, electric double layer capacitors, nickel-metal hydride batteries, and the like are being developed as high-output power storage devices.

Among the electric double layer capacitors, those using activated carbon for the electrodes have an output characteristic of about 0.5 to 1 kW / L. This electric double layer capacitor has high durability (cycle characteristics and high temperature storage characteristics), and has been considered to be the most suitable device in the field where high output is required. However, the energy density is only about 1 to 5 Wh / L. Therefore, it is necessary to further improve the energy density.
On the other hand, the nickel-metal hydride battery currently used in a hybrid electric vehicle has a high output equivalent to that of an electric double layer capacitor and an energy density of about 160 Wh / L. However, research is being vigorously pursued to further increase its energy density and output, as well as to improve its durability (particularly, stability at high temperatures).
In addition, research is underway to increase the output of lithium-ion batteries. For example, a lithium ion battery has been developed in which a high output exceeding 3 kW / L can be obtained at a discharge depth (a value indicating what percentage of the discharge capacity of the power storage element is discharged) of 50%. However, the energy density is 100 Wh / L or less, and the design is such that the high energy density, which is the greatest feature of the lithium ion battery, is intentionally suppressed. Moreover, since the durability (cycle characteristics and high temperature storage characteristics) is inferior to that of the electric double layer capacitor, the lithium ion battery has a discharge depth of 0 to 100% in order to have practical durability. It will be used in a range narrower than the range. Since the capacity of the lithium-ion battery that can be actually used becomes smaller, research for further improving the durability is being vigorously pursued.

As described above, there is a strong demand for practical use of a power storage element having high energy density, high output characteristics, and durability. However, each of the existing power storage elements described above has advantages and disadvantages. Therefore, there is a demand for a new power storage element that satisfies these technical requirements. As a promising candidate, a power storage element called a lithium ion capacitor has attracted attention and is being actively developed.
The energy of the capacitor is represented by 1/2 · C · V ² (where C is the capacitance and V is the voltage).
A lithium-ion capacitor is a type of power storage element (non-aqueous lithium-type power storage element) that uses a non-aqueous electrolyte solution containing a lithium salt. -A power storage element that charges and discharges by a non-Faraday reaction due to desorption, and a Faraday reaction by the storage and release of lithium ions at the negative electrode, similar to a lithium ion battery.

To summarize the above-mentioned electrode materials and their characteristics, high output and high durability are achieved when charging and discharging are performed by adsorption / desorption (non-Faraday reaction) of ions on the surface of activated carbon using a material such as activated carbon for the electrodes. However, the energy density becomes low (for example, it is multiplied by 1). On the other hand, when an oxide or carbon material is used for the electrode and charging / discharging is performed by a Faraday reaction, the energy density is high (for example, 10 times that of a non-Faraday reaction using activated carbon), but the durability and output characteristics are high. There is a problem in.
As a combination of these electrode materials, the electric double-layer capacitor uses activated carbon (energy density 1 times) for the positive electrode and the negative electrode, and both the positive and negative electrodes are charged and discharged by a non-Faraday reaction, and have high output and high durability. However, it is characterized by low energy density (1x positive electrode x 1x negative electrode = 1).
Lithium-ion secondary batteries are characterized by using a lithium transition metal oxide (energy density 10 times) for the positive electrode and a carbon material (energy density 10 times) for the negative electrode, and charging and discharging both the positive and negative electrodes by a Faraday reaction. Energy density (positive electrode 10 times x negative electrode 10 times = 100), but there are problems with output characteristics and durability. Further, in order to satisfy the high durability required for a hybrid electric vehicle or the like, the discharge depth must be limited, and a lithium ion secondary battery can use only 10 to 50% of its energy.
Lithium-ion capacitors use activated carbon (1x energy density) for the positive electrode and carbon material (10x energy density) for the negative electrode, and are characterized by performing charging and discharging by a non-Faraday reaction at the positive electrode and a Faraday reaction at the negative electrode. It is a new asymmetric capacitor that combines the characteristics of a multi-layer capacitor and a lithium-ion secondary battery. The lithium ion capacitor has a high energy density (1x positive electrode x 10x negative electrode = 10) while having high output and high durability, and does not need to limit the discharge depth as in a lithium ion secondary battery.

Examples of applications of lithium ion capacitors include electric storage for railways, construction machinery, and automobiles. In these applications, since the space for mounting the power storage element is limited, there is a demand for a power storage element having a higher energy density and being able to be miniaturized. For example, Patent Document 3 discloses a technique for improving the energy density of a lithium ion capacitor by mixing iron phosphate (LiFePO ₄ ), which is one of the transition metal oxides, with activated carbon of a positive electrode. ..
On the other hand, in the above-mentioned applications such as automobile applications, lithium ion capacitors are used in a wide temperature environment from low temperature to high temperature, so that deterioration progresses during use. In order to appropriately control the charge and discharge of the lithium ion capacitor, a method of estimating the state of the lithium ion capacitor with high accuracy while using the power storage system is required.
For example, Patent Document 1 proposes a method of predicting a deterioration rate from information such as voltage and temperature of a storage battery. Further, Patent Document 2 proposes a method of estimating deterioration from the temperature and voltage of an operating capacitor. However, it has not been easy to accurately predict the deterioration state of a non-aqueous lithium-type power storage element in which activated carbon and a transition metal oxide are mixed with a positive electrode active material as described in Patent Document 3.

International Publication No. 2012/095894 Japanese Patent No. 4042917 Japanese Unexamined Patent Publication No. 2012-89825

Neither patent document mentions a technique for estimating the deterioration state of a non-aqueous lithium-type power storage element using a composite positive electrode, which is a mixture of activated carbon and a lithium transition metal oxide having an olivine structure in the positive electrode. .. In particular, it is difficult to easily estimate the state of a non-aqueous lithium-type power storage element in operation. Therefore, the problem to be solved by the present invention is a method for estimating the state of a non-aqueous lithium-type power storage element in operation and a deterioration estimation device in which activated carbon and a lithium transition metal oxide having an olivine structure are mixed in a positive electrode. Another object of the present invention is to provide a system including a non-aqueous lithium-type power storage element and a state estimation device thereof.

The present inventors have found that the above problems can be solved by the following technical means, and have completed the present invention.
[1]
A method for estimating the state of a non-aqueous lithium-type power storage element including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution containing lithium ions.
The negative electrode has a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material provided on one side or both sides of the negative electrode current collector, and the negative electrode active material occludes lithium ions. And contains materials that can be released
The positive electrode has a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material provided on one side or both sides of the positive electrode current collector, and the positive electrode active material includes activated carbon and lithium ions. Contains a lithium transition metal oxide with an olivine structure capable of storing and releasing.
The maximum is the quadratic derivative d ² V / dQ ² calculated from the discharge curve obtained by taking the capacitance Q when the non-aqueous lithium power storage element is discharged at a constant current on the horizontal axis and the voltage V on the vertical axis. As parameters, the voltage at the time of measuring the discharge curve, the current or power at the time of measuring the discharge curve, and the negative voltage of the non-aqueous lithium type power storage element are used as parameters, and a database group collected in advance is created and the non-voltage is in operation. The current, voltage, and temperature of the water-based lithium-type power storage element are measured, d ² V / dQ ² is calculated, and the voltage at which d ² V / dQ ² is maximized is used as the non-water-based lithium power storage element based on the database group. A method for estimating the state of a non-aqueous lithium-type power storage element, which comprises estimating the negative voltage potential of the element.
[2]
A method for estimating the state of a non-aqueous lithium-type power storage element including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution containing lithium ions.
The negative electrode has a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material provided on one side or both sides of the negative electrode current collector, and the negative electrode active material occludes lithium ions. And contains materials that can be released
The positive electrode has a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material provided on one side or both sides of the positive electrode current collector, and the positive electrode active material includes activated carbon and lithium ions. Contains a lithium transition metal oxide with an olivine structure capable of storing and releasing.
A database group was created in which the discharge resistance and charge resistance of the non-aqueous lithium energy storage element were collected in advance with the voltage and negative potential of the non-aqueous lithium energy storage element as parameters, and the current of the non-aqueous lithium energy storage element in operation. And the voltage and temperature are measured, and the quadratic derivative d ² V / dQ ² is calculated from the discharge curve obtained by taking the capacity Q on the horizontal axis and the voltage V on the vertical axis, and d ² V / dQ ² is The non-aqueous lithium type is characterized in that the discharge resistance or the charge resistance of the non-aqueous lithium type energy storage element is estimated from the negative potential of the non-aqueous lithium type energy storage element estimated from the maximum voltage based on the database group. A method for estimating the state of a power storage element.
[3]
The lithium transition metal oxide has the following formula:
Li _x2 FePO ₄ {In the formula, x2 satisfies 0.8 ≦ x2 ≦ 1.2. },
Li _x2 CoPO ₄ {In the formula, x2 satisfies 0.8 ≦ x2 ≦ 1.2. }, And Li _x2 MnPO ₄ {In the formula, x2 satisfies 0.8 ≦ x2 ≦ 1.2. },
The method for estimating the state of a non-aqueous lithium-type power storage element according to [1] or [2], which comprises at least one lithium transition metal oxide selected from the group consisting of.
[4]
The content of the lithium transition metal oxide is 1.0% by mass to 50.0% by mass based on the total mass of the positive electrode active material layer, according to any one of [1] to [3]. The method for estimating the state of the non-aqueous lithium-type power storage element described.
[5]
When the mass ratio of the activated carbon in the positive electrode active material layer is A ₁ and the mass ratio of the lithium transition metal oxide is A ₂ , A ₂ / A ₁ is 0.1 or more and 2.5 or less. , The state estimation method for a non-aqueous lithium-type power storage element according to any one of [1] to [4].
[6]
The positive electrode contains at least one selected from the group consisting of lithium carbonate, lithium oxide, and lithium hydroxide in an amount of 0.2% by mass or more and 50% by mass or less based on the total amount of the positive electrode active material [1]. The method for estimating the state of the non-aqueous lithium-type power storage element according to any one of [5].
[7]
A state estimation device for a non-aqueous lithium storage element including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution containing lithium ions.
The negative electrode of the non-aqueous lithium-type power storage element has a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material provided on one side or both sides of the negative electrode current collector, and the negative electrode active material is provided. The material includes a material capable of storing and releasing lithium ions.
The positive electrode of the non-aqueous lithium-type power storage element has a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material provided on one side or both sides of the positive electrode current collector, and the positive electrode active material is provided. The material comprises activated carbon and a lithium transition metal oxide having an olivine structure capable of storing and releasing lithium ions, and the state estimator is:
The maximum is the quadratic derivative d ² V / dQ ² calculated from the discharge curve obtained by taking the capacitance Q when the non-aqueous lithium power storage element is discharged at a constant current on the horizontal axis and the voltage V on the vertical axis. The voltage is a storage unit having a database group collected in advance with the temperature at the time of measuring the discharge curve, the current or power at the time of measuring the discharge curve, and the negative voltage of the non-aqueous lithium type power storage element as parameters; and the non-aqueous system in operation. The d ² V / dQ ² is calculated from the measured values of the current, voltage and temperature of the lithium type storage element, and the non-aqueous lithium type storage is based on the database group from the voltage at which d ² V / dQ ² is maximized. Arithmetic processing unit that estimates the negative voltage potential of the element;
A state estimation device for a non-aqueous lithium-type power storage element.
[8]
A state estimation device for a non-aqueous lithium storage element including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution containing lithium ions.
The negative electrode of the non-aqueous lithium-type power storage element has a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material provided on one side or both sides of the negative electrode current collector, and the negative electrode active material is provided. The material includes a material capable of storing and releasing lithium ions.
The positive electrode of the non-aqueous lithium-type power storage element has a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material provided on one side or both sides of the positive electrode current collector, and the positive electrode active material is provided. The material comprises activated carbon and a lithium transition metal oxide having an olivine structure capable of storing and releasing lithium ions, and the state estimator is:
A storage unit having a database group in which the discharge resistance and charge resistance of the non-aqueous lithium storage element are collected in advance with the voltage and negative potential of the non-aqueous lithium storage element as parameters; and the non-aqueous lithium storage element in operation. From the measured values of current, voltage and temperature, the quadratic derivative d ² V / dQ ² of the discharge curve obtained by taking the capacity Q on the horizontal axis and the voltage V on the vertical axis is calculated, and d ² V / dQ An arithmetic processing unit that estimates discharge resistance or charge resistance from the negative voltage of the power storage element estimated from the voltage at which ² is the maximum, based on the database group;
A state estimation device for a non-aqueous lithium-type power storage element.
[9]
The lithium transition metal oxide has the following formula:
Li _x2 FePO ₄ {In the formula, x2 satisfies 0.8 ≦ x2 ≦ 1.2. },
Li _x2 CoPO ₄ {In the formula, x2 satisfies 0.8 ≦ x2 ≦ 1.2. }, And Li _x2 MnPO ₄ {In the formula, x2 satisfies 0.8 ≦ x2 ≦ 1.2. },
The state estimation device for a non-aqueous lithium storage element according to [7] or [8], which comprises at least one lithium transition metal oxide selected from the group consisting of.
[10]
The content of the lithium transition metal oxide is 1.0% by mass to 50.0% by mass based on the total mass of the positive electrode active material layer, according to any one of [7] to [9]. The state estimation device for the non-aqueous lithium type power storage element described.
[11]
When the mass ratio of the activated carbon in the positive electrode active material layer is A ₁ and the mass ratio of the lithium transition metal oxide is A ₂ , A ₂ / A ₁ is 0.1 or more and 2.5 or less. , The state estimation device for the non-aqueous lithium power storage element according to any one of [7] to [10].
[12]
The positive electrode contains at least one selected from the group consisting of lithium carbonate, lithium oxide, and lithium hydroxide in an amount of 0.2% by mass or more and 50% by mass or less based on the total amount of the positive electrode active material [7]. The state estimation device for the non-aqueous lithium-type power storage element according to any one of [11].
[13]
(A) A non-aqueous lithium power storage element including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolytic solution containing lithium ions, wherein the negative electrode is a negative electrode current collector and one or both sides of the negative electrode current collector. It has a negative electrode active material layer containing a negative electrode active material provided above, the negative electrode active material contains a material capable of storing and releasing lithium ions, and the positive electrode is a positive electrode current collector and the positive electrode collection. It has a positive electrode active material layer containing a positive electrode active material provided on one side or both sides of an electric body, and the positive electrode active material is lithium having an activated carbon and an olivine structure capable of storing and releasing lithium ions. A non-aqueous lithium-type power storage element containing a transition metal oxide; and (b) the state estimation device according to any one of [7] to [12];
System including.
[14]
The above systems are a power storage module system, a power regeneration assist system, a power load leveling system, a non-disruptive power supply system, a contactless power supply system, an energy harvest system, a power storage system, an electric power steering system, an emergency power supply system, and an in-wheel motor system. , The system according to [13], which is at least one selected from the group consisting of an idling stop system, a transportation equipment system, a quick charging system and a smart grid system.
[15]
In addition to the non-aqueous lithium storage element and the state estimation device, the system
(C) A lead battery, a nickel hydrogen battery, a lithium ion secondary battery or a fuel cell connected in series or in parallel with the non-aqueous lithium power storage element;
The system according to [13].
[16]
The system is at least one selected from the group consisting of a power storage system, an electric power steering system, an emergency power supply system, an in-wheel motor system, an idling stop system, a transportation equipment system, a quick charging system and a smart grid system. The system according to [15].
[17]
The system according to [16], wherein the system is a photovoltaic power generation storage system.
[18]
The system according to [16], wherein the system is the transportation equipment system and is an electric vehicle, a plug-in hybrid vehicle, a hybrid vehicle, or an electric motorcycle.

By using the method, apparatus and system of the present invention, it is possible to estimate the state of a non-aqueous lithium storage element in which activated carbon and a lithium transition metal oxide having an olivine structure are mixed in a positive electrode with high accuracy and easily. can.

FIG. 1 is a schematic diagram showing a discharge curve of the non-aqueous lithium-type power storage element according to the present embodiment. FIG. 2 is a schematic diagram showing the first derivative dV / dQ of the discharge curve of the non-aqueous lithium-type power storage element in the present embodiment. FIG. 3 is a schematic diagram showing a quadratic derivative d ² V / dQ ² of the discharge curve of the non-aqueous lithium storage element in the present embodiment. FIG. 4 is a block diagram of the state estimation device. FIG. 5 is a configuration diagram of a power storage module system. FIG. 6 is a cycle pattern of the power storage module.

Hereinafter, embodiments of the present invention (hereinafter referred to as “embodiments”) will be described in detail, but the present invention is not limited to the following embodiments. The upper limit value and the lower limit value in each numerical range of the following embodiments can be arbitrarily combined to form an arbitrary numerical range.
Non-aqueous lithium-type power storage elements generally include a positive electrode, a negative electrode, a separator, an electrolytic solution, and an exterior body as main components. As the electrolytic solution, an organic solvent in which a lithium salt is dissolved (hereinafter referred to as a non-aqueous electrolytic solution) is used.

[State estimation method]
A first aspect of the present invention is a method for estimating the state of a non-aqueous lithium storage element containing activated carbon and a lithium transition metal oxide having an olivine structure capable of occluding and releasing lithium ions in a positive electrode active material. In the embodiment of the state estimation method:
(A) The maximum is the quadratic derivative d ² V / dQ ² calculated from the discharge curve obtained by taking the capacity Q when the power storage element is discharged at a constant current on the horizontal axis and the voltage V on the vertical axis. With the database group collected in advance with the negative voltage, temperature, current or power as parameters; and / or (a) the discharge resistance, charge resistance or discharge capacity of the power storage device with the negative potential as parameters. With the collected databases;
Is created and stored in the storage unit of the arithmetic unit as needed, the current, voltage and temperature of the non-aqueous lithium type power storage element in operation are measured, d ² V / dQ ² is calculated, and d ² V / From the voltage at which dQ ² is maximized, it is possible to estimate the negative potential, the discharge resistance, or the charge resistance of the power storage element based on the above database (a) or (b).
This is because the resistance component of the negative electrode is the positive electrode as the resistance component of the non-aqueous lithium storage element containing activated carbon and lithium transition metal oxide having an olivine structure capable of occluding and releasing lithium ions in the positive electrode active material. It is considered that the state estimation method focusing on the deterioration of the negative electrode is effective because it is larger than the resistance component of. Since the deterioration of the resistance of the negative electrode largely depends on the potential of the negative electrode, it is possible to estimate the resistance of the power storage element itself, which is largely occupied by the resistance component of the negative electrode, by estimating the potential of the negative electrode.

[Voltage at which d ² V / d Q ² calculated from the discharge curve is maximum]
First, constant current charging is performed until the upper limit voltage _VH (for example, 4.0 V) is reached at a current value of 1 C in a constant temperature bath in which the non-aqueous lithium type power storage element is set to a constant temperature T ₁ , and then the upper limit voltage is applied. Constant voltage charging to which a constant voltage of _VH is applied is performed for a total of 30 minutes. After that, let Q (Ah or Wh) be the capacity when constant current discharge is performed with a constant current I ₁ or a constant power P ₁ up to the lower limit voltage _VL (for example, 2.0 V). The transition of the discharge capacity with respect to the cell voltage V (V) at this time is taken as the discharge curve in the present specification. A schematic diagram of the discharge curve is shown in FIG. In FIG. 1, the discharge capacity is shown on the horizontal axis and the voltage is shown on the vertical axis. From this discharge curve, the first derivative dV / dQ (see FIG. 2) and the second derivative d ² V / dQ ² (see FIG. 3) are obtained, and the discharge capacity Q when the second derivative is maximized is obtained. Q _A , find the corresponding voltage _VA . Further, the method for measuring the negative electrode potential at this time is not particularly limited, but the following method is used. The negative electrode potential varies depending on the voltage of the non-aqueous lithium-type power storage element, but since it may be uniquely determined, the negative electrode potential at any voltage may be used.

(1) Method of measuring the negative voltage at the lower limit voltage of the non-aqueous lithium type electricity storage element In a constant temperature bath in which the non-aqueous lithium type electricity storage element is set to 25 ° C., the lower limit voltage _VL (for example, 2.0V) with a current value of 20C. ) Is charged with a constant current, and then a constant voltage charge with a constant voltage of the lower limit voltage _VL is performed for a total of 30 minutes. Subsequently, the non-aqueous lithium storage element is disassembled in the argon box, the negative electrode is taken out, and the potential difference between the negative electrode and the lithium reference electrode at this time is measured to measure the negative electrode at the lower limit voltage _VL of the non-aqueous lithium storage element. The potential V ₁ (Li ⁺ / Li) is obtained.

(2) Method of measuring the negative electrode potential at the voltage at which d ² V / dQ ² is maximized d ² V / dQ ² obtained at a sufficiently low rate (for example, 1C) with respect to the discharge capacity of the non-aqueous lithium storage element. Let _VA be the voltage at which is maximum. This voltage is presumed to be the voltage corresponding to the plateau of the lithium transition metal oxide having an olivine structure. In a constant temperature bath set to 25 ° C for a non-aqueous lithium-type power storage element, constant current charging is performed at a current value of 20 C until _VA is reached, and then constant voltage charging is performed by applying a constant voltage of _VA for a total of 30. Do it for a minute. Subsequently, the non-aqueous lithium storage element is disassembled in the argon box, the negative electrode is taken out, and the potential difference between the negative electrode and the lithium reference electrode at this time is measured to measure the negative electrode potential V in _VA of the non-aqueous lithium storage element. ₁ (Li ⁺ / Li) is required.
As a result, when the temperature T _{1, the} current I ₁ or the power P ₁ , and the negative electrode potential V ₁ , the voltage _{VA (T1, I 1 or P1, V1} ) at which d ² V / d Q ² calculated from the discharge curve is maximized is the maximum. ₎ Is required.

[Database group of voltage that maximizes d ² V / d Q ² ]
In one embodiment of the method of the present invention, the database group of the voltage at which d ² V / dQ ² is maximized is the temperature when measuring the discharge curve, the current or power when measuring the discharge curve, and the non-aqueous lithium type. The negative electrode potential of the power storage element is collected in advance as a parameter.
The details of the parameterization of the negative electrode potential will be described below. Generally, while the non-aqueous lithium-type power storage element operates, lithium in the negative electrode is gradually lost, and the negative electrode potential rises as compared with the time when the power storage element is completed. Therefore, it is sufficient that the range of the negative electrode potential as a parameter is on the higher potential side than the negative electrode potential at the time of completion of the non-aqueous lithium storage element.
The method for adjusting the negative electrode potential is not particularly limited, but the following method is used.

(1) Method of applying a charge / discharge cycle load to a non-aqueous lithium-type power storage element Generally, when a charge / discharge cycle load is applied, lithium is gradually deactivated. By measuring the potential and the change in the voltage at which d ² V / dQ ² is maximized, a database of the voltage at which d ² V / dQ ² is maximized can be obtained with the negative electrode potential as a parameter. The method of applying the charge / discharge cycle load is not particularly limited, but for example, the following method can be considered.
First, a plurality of non-aqueous lithium-type power storage elements are constantly charged in a constant temperature bath set at 25 ° C. until the upper limit voltage V _H is reached at a current value of 300 C, and then the lower limit voltage _VL at a current value of 300 C. Is discharged at a constant current until it reaches. The charge / discharge process is repeated a certain number of times (for example, 10,000 times). The negative electrode potential is measured by the above-mentioned negative electrode potential measuring method using one of a plurality of non-aqueous lithium-type power storage elements. Further, one of a plurality of non-aqueous lithium-type power storage elements may be used to acquire the voltage at which d ² V / d Q ² calculated from the discharge curve is maximized by the above-mentioned method. By repeating the above operation every fixed number of cycles (for example, 10,000 times, ^{20,000 times, 30,000 times, ...), the voltage at which d2 V / dQ 2 is} maximized when the negative electrode potential is raised. Database is obtained.
Temperature, current or power by controlling the environmental temperature of the non-aqueous lithium storage element and the measured current or power when measuring the discharge curve before the start of the cycle test and when the charge / discharge cycle load is applied. A database of the voltage at which d ² V / d Q ² is maximized can be obtained. An example of such a database is shown in Table 1.

(2) Method of applying a high-temperature load to a non-aqueous lithium-type power storage element Generally, when a high-temperature load is applied, lithium is gradually deactivated, which raises the negative electrode potential, and the negative electrode potential and d ² at that time. By measuring the change in the voltage at which V / dQ ² is maximized, a database of the voltage at which d ² V / dQ ² is maximized can be obtained with the negative electrode potential as a parameter. The method of applying a high temperature load is not particularly limited, but for example, the following method can be considered.
First, a non-aqueous lithium-type power storage element as a plurality of cells is constantly charged until a current value of 100 C is reached, and then constant voltage charging is performed for 10 minutes by applying a constant voltage of voltage _VH . Then, the cell is stored in a high temperature environment (for example, 60 ° C.), and after a certain period (for example, one month), it is taken out from the high temperature environment. The negative electrode potential is measured by the above-mentioned negative electrode potential measuring method using one of a plurality of non-aqueous lithium-type power storage elements. Further, one of a plurality of non-aqueous lithium-type power storage elements may be used to acquire the voltage at which d ² V / d Q ² calculated from the discharge curve is maximized by the above-mentioned method. By repeating the above operation at regular intervals (for example, after 2 weeks, 4 weeks, 6 weeks, ...), d ² V / dQ ² is the maximum when the negative electrode potential is increased. A database of the following voltages is obtained.

By controlling the environmental temperature of the non-aqueous lithium storage element and the measured current or power when measuring the discharge curve before the start of the high temperature test and when a high temperature load is applied, the temperature, current or power can be used as parameters. A database of the voltage at which d ² V / d Q ² is maximized can be obtained. An example of such a database is shown in Table 1.
As the temperature interval as a parameter, it is preferable to acquire in advance the voltage at which d ² V / dQ ² is maximized at the temperature from the upper limit to the lower limit of the specification range of the non-aqueous lithium-type power storage element. Further, as the current or electric power section, the voltage at which d ² V / dQ ² is maximized may be acquired in advance for the current or electric power from the upper limit to the lower limit of the specification range of the non-aqueous lithium storage element. preferable.

The above two methods (1) and (2) have been given as examples, but the method is not limited to a single method. Rather, in order to improve the accuracy of state estimation, it is preferable to adjust the negative electrode potential by a method suitable for the actual usage environment of the non-aqueous lithium storage element. For example, if the method has a high frequency of charge / discharge cycle load such as for regenerative use, the above (1) is used. However, even in regenerative applications, if there is time to wait at a high temperature when the non-aqueous lithium-type power storage element is not operating, the increase in the negative electrode potential due to a high temperature load using the method as described in (2) above (1). It is preferable to construct a database group in combination with the method of).

[Discharge resistance]
As used herein, the discharge resistance Ra (Ω) is a value obtained by the following method:
First, in a constant temperature bath in which the non-aqueous lithium type power storage element is set to 25 ° C., a constant current discharge is performed until the lower limit voltage _VL (for example, 2.0 V) is reached at a current value of 1 C, and then at a current value of 20 C. Constant current charging is performed until an arbitrary voltage V _X with an upper limit voltage V _H (for example, 4.0 V) or less and a lower limit voltage _VL or more is reached, and then constant voltage charging with a constant voltage of V _X is applied for a total of 30 minutes. conduct. Subsequently, a constant current discharge is performed with a current value of 50 C to a lower limit voltage _VL (for example, 2.0 V) to obtain a discharge curve (time-voltage). In this discharge curve, when the voltage at the discharge time = 0 second obtained by extrapolating from the voltage values at the time points of the discharge time of 1 second and 2 seconds is taken as Eo, the voltage drop ΔE = V _X −Eo. , And Ra = ΔE / (50C (current value A)).

[Charging resistance]
As used herein, the charging resistance Rb (Ω) is a value obtained by the following method:
First, the non-aqueous lithium-type power storage element is constantly charged in a constant temperature bath set at 25 ° C. until the upper limit voltage _VH (for example, 4.0 V) is reached at a current value of 1 C, and then at a current value of 20 C. A constant current discharge is performed until an arbitrary voltage V _X of the upper limit voltage V _H (for example, 4.0 V) or less and a lower limit voltage _VL or more is reached, and then a constant voltage discharge of V _X is applied for a total of 30 minutes. conduct. Subsequently, constant current charging is performed up to an upper limit voltage _VH (for example, 4.0 V) with a current value of 50 C to obtain a charging curve (time-voltage). In this charging curve, when the voltage at the charging time = 0 seconds obtained by extrapolating from the voltage values at the charging times of 1 second and 2 seconds is defined as Eo, the voltage drop ΔE = −V _X + Vb. , And Rb = ΔE / (50C (current value A)).

[Database group of discharge resistance and charge resistance]
In another embodiment of the method of the present invention, a database group of discharge resistance and charge resistance is collected in advance with the voltage of the non-aqueous lithium storage element and the negative electrode potential as parameters. The voltage may be measured by adjusting V _X in the calculation of the discharge resistance and / or the charge resistance described above. The method for adjusting the negative electrode potential is not particularly limited, but the same method as described above can be used, and the discharge resistance, charge resistance, and discharge capacity when the negative electrode potential is adjusted can be measured by the above-mentioned method. , Discharge resistance and charge resistance database group can be collected in advance with the voltage and negative electrode potential of the non-aqueous lithium storage element as parameters. An example of such a database is shown in Table 2 below.

[Method of calculating the voltage at which d ² V / dQ ² of the non-aqueous lithium-type power storage element in operation is maximized]
In the present invention, for example, the following method is used as a method for calculating the voltage at which d ² V / dQ ² of the non-aqueous lithium storage element in operation is maximized. As for the method of measuring the temperature of the non-aqueous lithium-type power storage element, any of the methods of measuring the positive electrode terminal, the negative electrode terminal, or the main body of the power storage element may be used, and the power storage element is stacked as an assembled battery or a cell stack. It is preferable to measure the temperature of the positive electrode terminal or the negative electrode terminal.

(1) Method of calculating from a constant current or constant power discharge curve for a non-aqueous lithium energy storage element in operation The non-aqueous lithium energy storage element reaches an upper limit voltage _VH (for example, 4.0 V) with a current value of 1C. Constant current charging is performed until the voltage is increased, and then constant voltage charging is performed for a total of 30 minutes by applying a constant voltage of the upper limit voltage _VH . After that, while measuring the temperature T of the non-aqueous lithium-type power storage element, the capacity when constant current or low power discharge is applied with constant current I or constant power P to the lower limit voltage _VL (for example, 2.0 V) is Q ( Ah). The transition of the discharge capacity with respect to the cell voltage V (V) at this time is used as the discharge curve, and the linear derivative dV / dQ and the secondary derivative d ² V / dQ ² are obtained, and d ² V / dQ ² becomes the maximum. The voltage at the time is obtained, and thereby the voltage at which d ² V / dQ ² of the non-aqueous lithium-type power storage element in operation is maximized can be obtained. As the temperature at this time, the time average value of the measured temperature is acquired. Further, as the current value or the power value at this time, the measured constant current value or the constant power value is acquired.

(2) Method of calculating from the operating data of the non-aqueous lithium-type power storage element in operation d ² V / dQ ² is calculated from the operating data without interrupting the actual non-aqueous lithium-type power storage element from the operating data. The calculation method will be described in (2a) or (2b) below. In the following method, data obtained by measuring the current, voltage, and temperature flowing through the operating non-aqueous lithium storage element is used.

(2a) Method of calculating from discharge data during operation When the non-aqueous lithium power storage element is operated by a usage method (for example, fluctuation range: about ± 20%) in which the discharge current and discharge power do not fluctuate significantly. , Extract the data obtained by discharging the power storage element from the upper limit voltage V _H to the lower limit voltage _VL , and obtain the voltage that maximizes d ² V / d Q ² from the time transition of the discharge current and voltage at that time. Is possible. In this method, arithmetic processing can be easily performed. As the temperature at this time, the time average value of the measured temperature is acquired. Further, as the current or power value at this time, the time average value of the measured current or the measured power is acquired.

(2b) Method of calculating by limiting the voltage range and current range from the discharge data during operation Non-aqueous lithium type with a usage method (for example, regenerative use of automobiles or forklifts) in which the discharge current and discharge power fluctuate greatly. When operating the power storage element, it is necessary to perform arithmetic processing. Specifically, in the entire discharge data, a non-aqueous system from the upper limit voltage _VH to the lower limit voltage _VL in a state where the discharge current and the discharge power do not fluctuate significantly (for example, the fluctuation range: about ± 20%). The data in which the lithium-type power storage element is operating is extracted, and the voltage at which d ² V / d Q ² is maximized is obtained from the time transition of the discharge current and the voltage at that time. Further, as the temperature at this time, the time average value of the measured temperature is acquired. Further, as the current or power value at this time, the time average value of the measured current or the measured power is acquired.

[Estimation method of negative electrode potential of non-aqueous lithium storage element in operation]
Based on the voltage at which d ² V / dQ ² of the non-aqueous lithium storage element in operation obtained by the above method is maximized, and the temperature, current or power value at that time, d ² V / dQ ² is maximum. Refer to the database group of voltage, and acquire the closest data from the database group. The negative electrode potential of the data acquired from this database group is used as the estimated negative electrode potential of the non-aqueous lithium-type power storage element in operation.

[Estimation method of discharge resistance or charge resistance of non-aqueous lithium-type power storage element in operation]
Based on the estimated negative electrode potential of the non-aqueous lithium storage element in operation obtained by the above method, refer to the database group of discharge resistance and charge resistance, and discharge resistance and charge resistance corresponding to the nearest negative electrode potential. Get the data. As described above, each discharge resistance and charge resistance database possesses data at each voltage of the power storage element, so that the discharge resistance and / or charge resistance at an arbitrary voltage _VX of the power storage element can be estimated.

In the method of the present invention, the negative electrode potential, the discharge resistance, or the charge resistance can be estimated from the voltage at which d ² V / dQ ² of the non-aqueous lithium storage element in operation is maximized. This is because (i) the non-aqueous lithium power storage element according to the embodiment of the present invention mixes a lithium transition metal oxide having an olivine structure with activated carbon as a positive electrode active material, so that d ² V / dQ. Since the negative electrode potential can be estimated from the voltage at which ² is the maximum, and (ii) relatively low resistance activated carbon is used as the positive electrode active material, the resistance of the positive electrode is low with respect to the resistance of the negative electrode, and the negative electrode is used. This is because the discharge resistance and / or the charge resistance can be estimated from the negative electrode potential because the correlation between the potential and the discharge resistance and the charge resistance is large. From the above (i) and (ii), the negative electrode potential, the discharge resistance, and the charge resistance can be estimated with high accuracy.

[Usage of estimated negative electrode potential, discharge resistance, and charge resistance]
According to the method of the present invention, the negative electrode potential, the discharge resistance, and / or the charge resistance of the non-aqueous lithium storage element in operation can be easily estimated, so that the estimated negative electrode potential, the discharge resistance, and / or the charge resistance can be used. Based on this, it is possible to adjust the usage load of the non-aqueous lithium-type power storage element. Examples of adjusting the working load are shown in (1) to (3) below.

(1) Adjustment of the usage load of the storage element based on the estimated negative electrode potential When the estimated negative electrode potential becomes higher than the predetermined negative electrode potential threshold, the usage load of the non-aqueous lithium storage element is reduced. By instructing a system equipped with a non-aqueous lithium storage element, it is possible to suppress an increase in the negative electrode potential due to deactivation of lithium in the negative electrode and extend the life of the non-aqueous lithium storage element.

(2) Adjustment of load used by the power storage element based on the estimated discharge resistance and charge resistance When the estimated discharge resistance and charge resistance become higher than the predetermined discharge resistance and charge resistance thresholds, the non-aqueous system By instructing a system equipped with a non-aqueous lithium storage element to take measures such as reducing the usage load of the lithium storage element, it is possible to suppress an increase in resistance beyond the threshold or estimated value and extend the life of the non-aqueous lithium storage element. It can be extended.

(3) Adjustment of load used by the storage element by comparing the estimated discharge resistance and the measured resistance of the storage element in operation According to the method of the present invention, the discharge resistance and charge resistance of the non-aqueous lithium storage element in operation are estimated. At the same time, measure the discharge resistance and charge resistance. A threshold value of the resistance magnification calculated by resistance magnification = measured resistance value ÷ estimated resistance value is set in advance, and when the resistance magnification exceeds the threshold value, the load of using the power storage element is reduced by the non-aqueous lithium type. By instructing a system equipped with a power storage element, it is possible to suppress an increase in resistance above the threshold value and extend the life of the non-aqueous lithium type power storage element. When the measured resistance value becomes larger than the estimated resistance value, in addition to the deterioration due to the lithium deactivation of the negative electrode, the decrease in electron conductivity due to cracks in the positive electrode or the negative electrode, and the diffusion resistance due to the clogging of the activated carbon of the positive electrode active material. Since it is presumed that the deterioration mode such as increase is also progressing, it is possible to reduce the usage load and suppress the progress of deterioration.
As a method of actually measuring the resistance value of the non-aqueous lithium-type storage element in operation in the system, a method of measuring the AC resistance of 1 kHz at an arbitrary voltage or a pulse discharge is applied to the non-aqueous lithium-type energy storage element. A method of calculating from the voltage drop at time can be mentioned.

[State estimation device]
A second aspect of the present invention is an apparatus for estimating the state of a non-aqueous lithium-type power storage element including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution containing lithium ions (hereinafter referred to as “state estimation device”). ..
The positive electrode, negative electrode, separator and non-aqueous electrolyte solution contained in the non-aqueous lithium storage element will be described later.
In one embodiment, the state estimator is:
The voltage at which d ² V / d Q ² is maximized, which is calculated from the discharge curve obtained by taking the capacity Q when the non-aqueous lithium type power storage element is discharged at a constant current on the horizontal axis and the voltage V on the vertical axis, is set. A storage unit having a database group collected in advance with the temperature when measuring the discharge curve, the current or power when measuring the discharge curve, and the negative voltage potential of the power storage element as parameters;
D ² V / dQ ² is calculated from the measured values of current, voltage and temperature of the non-aqueous lithium-type power storage element in operation, and from the voltage at which d ² V / dQ ² is maximized, based on the database group. With an arithmetic processing unit that estimates the negative potential of the power storage element;
To prepare for. FIG. 4 shows an example of the configuration of the state estimation device. Voltage data is delivered from the voltage measuring unit, current data is delivered from the current measuring unit, temperature data is delivered from the temperature measuring unit to the arithmetic processing unit, and the arithmetic processing unit has d ² V / dQ ² stored in the storage unit. By associating the database group of the maximum voltage with the measured data of voltage, current and temperature, the state of the power storage element is estimated, and the estimated state is shown to the observer via the output unit. A component (not shown) in which at least two of the voltage measuring unit, the current measuring unit, and the temperature measuring unit are integrated may be used.

In the second embodiment of the present invention, the state estimator is:
A storage unit having a database group in which the discharge resistance and charge resistance of the non-aqueous lithium storage element are collected in advance with the voltage and negative potential of the non-aqueous lithium storage element as parameters; and the non-aqueous lithium storage element in operation. The quadratic derivative d ² V / dQ ² of the discharge curve obtained by measuring the current, voltage and temperature and taking the capacity Q on the horizontal axis and the voltage V on the vertical axis is calculated, and d ² V / dQ ² An arithmetic processing unit that estimates the discharge resistance or charge resistance from the negative voltage of the power storage element estimated from the voltage at which is the maximum, based on the database group;
To prepare for. FIG. 4 shows an example of the configuration of the state estimation device. Voltage data from the voltage measurement unit, current data from the current measurement unit, and temperature data from the temperature measurement unit are delivered to the arithmetic processing unit, and the arithmetic processing unit stores the discharge resistance / charge resistance database group stored in the storage unit. Is associated with the measured data of voltage, current and temperature, the state of the power storage element is estimated, and the estimated state is shown to the observer via the output unit.

[Use of state estimation device]
In another embodiment of the invention
(A) Non-aqueous lithium storage element and
(B) With the state estimation device described above,
A system including is provided. The state estimation device includes a system including a non-aqueous lithium type power storage element, for example, a power storage module system, a power regeneration assist system, a power load leveling system, a non-disruptive power supply system, a contactless power supply system, an energy harvest system, a power storage system, and the like. It can be used in solar power storage systems, electric power steering systems, emergency power supply systems, in-wheel motor systems, idling stop systems, transportation equipment systems, quick charging systems, smart grid systems, and the like.

FIG. 5 is a block diagram of a power storage module system using a non-aqueous lithium power storage element. The power storage module 9 has a cell stack 2 in which a plurality of power storage elements 1 having tab terminals 5 are stacked between a plurality of end plates (3, 3), and crosses the end plate 3 and the cell stack 2. It is reinforced by the arranged fastener 4. A bus bar 6 can be arranged between the plurality of tab terminals (5, 5). When estimating the state of the power storage module 9, as shown in FIG. 5, the voltage measurement terminal 7, the temperature measurement terminal 8 and / or the current measurement terminal (not shown) of the state estimation device are connected to the tab terminal of the power storage module 9. The voltage, temperature and / or current of the power storage module 9 may be measured by contacting each of the 5s. Further, the voltage measuring terminal 7 may also serve as a current measuring terminal. Although the drawing shows a structure in which the positive and negative tabs protrude from both ends of the power storage element, it can be applied even if the positive and negative tabs protrude from one side.
The power storage system is preferably used for natural power generation such as solar power generation or wind power generation, the power load leveling system is preferably used for microgrids, and the non-disruptive power supply system is preferably used for production equipment in factories. In the non-contact power supply system, the non-aqueous lithium energy storage element is used for leveling voltage fluctuations such as microwave power transmission or electric field resonance and for storing energy. In the energy harvest system, the non-aqueous lithium energy storage element is used for vibration power generation. In order to use the electric power generated by the above, each is suitably used.

In power storage systems, electric power steering systems, emergency power supply systems, in-wheel motor systems, idling stop systems, transportation equipment systems, quick charging systems, smart grid systems, etc., a plurality of (a) non-aqueous lithium cells are used as cell stacks. The type storage element is connected in series or in parallel, or (a) a non-aqueous lithium type storage element and (c) a lead battery, a nickel hydrogen battery, a lithium ion secondary battery or a fuel cell are connected in series or in parallel. Can be done.
Further, the state estimation device according to the present embodiment can be mounted on a transportation device system, for example, on a transportation device such as an electric vehicle, a plug-in hybrid vehicle, a hybrid vehicle, or an electric motorcycle.
The power regeneration assist system, electric power steering system, emergency power supply system, in-wheel motor system, idling stop system, or a combination thereof described above are suitably mounted on transportation equipment.

[Positive electrode]
The positive electrode has a positive electrode current collector and a positive electrode active material layer existing on one side or both sides thereof.
Further, the positive electrode preferably contains a lithium compound as a positive electrode precursor before assembling the power storage element. As will be described later, in the present embodiment, it is preferable to pre-dope the negative electrode with lithium ions in the energy storage element assembly process, but the pre-doping method includes a positive electrode precursor containing a lithium compound, a negative electrode, a separator, an exterior body, and an exterior body. It is preferable to apply a voltage between the positive electrode precursor and the negative electrode after assembling the power storage element using the non-aqueous electrolyte solution. The lithium compound is preferably contained in the positive electrode active material layer formed on the positive electrode current collector of the positive electrode precursor. The lithium compound may be contained in the positive electrode precursor in any embodiment. For example, the lithium compound may be present between the positive electrode current collector and the positive electrode active material layer, or may be present on the surface of the positive electrode active material layer.
In the present specification, the positive electrode state before the lithium doping process is defined as a positive electrode precursor, and the positive electrode state after the lithium doping process is defined as a positive electrode.

[Positive electrode active material layer]
The positive electrode active material layer contained in the positive electrode according to the present embodiment contains a positive electrode active material containing a lithium transition metal oxide having an olivine structure capable of occluding and releasing activated carbon and lithium ions. The positive electrode active material layer preferably contains optional components such as a transition metal oxide, a conductive filler, a binder, and a dispersion stabilizer in addition to the positive electrode active material, and can occlude and release lithium ions. It is more preferable to contain a transition metal oxide.
Further, it is preferable that the positive electrode active material layer of the positive electrode precursor contains a lithium compound other than the positive electrode active material.

[Positive electrode active material]
The positive electrode active material according to the present embodiment includes activated carbon and a lithium transition metal oxide having an olivine structure capable of occluding and releasing lithium ions. Further, the positive electrode active material may be used in combination with another carbon material (carbon nanotube, conductive polymer, or porous carbon material).

[Activated carbon]
There are no particular restrictions on the type of activated carbon used as the positive electrode active material and its raw materials.
It is preferable to optimally control the pores of the activated carbon in order to achieve both high input / output characteristics and high energy density. Specifically, the amount of mesopores derived from pores having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method is V1 (cc / g), and the amount of micropores derived from pores having a diameter of less than 20 Å calculated by the MP method is used. When V2 (cc / g) is set, (1) for high input / output characteristics, 0.3 <V1 ≦ 0.8 and 0.5 ≦ V2 ≦ 1.0 are satisfied, and the BET method is used. Activated carbon having a measured specific surface area of 1,500 m ² / g or more and 3,000 m ² / g or less (hereinafter, also referred to as activated carbon 1) is preferable, and (2) in order to obtain a high energy density, 0. Activated carbon that satisfies 8 <V1 ≦ 2.5 and 0.8 <V2 ≦ 3.0 and has a specific surface area measured by the BET method of 2,300 m ² / g or more and 4,200 m ² / g or less. Hereinafter, it is also referred to as activated carbon 2).

[Transition metal oxide]
The positive electrode active material according to the present embodiment can occlude and release lithium ions from the viewpoint of achieving both high energy density and high output of the power storage element and maintaining their characteristics within a wide temperature range. Contains a lithium transition metal oxide having an olivine structure. In addition, in this specification, the term "transition metal oxide" is assumed to include a transition metal phosphate.
As a transition metal oxide having an olivine structure capable of occluding and releasing lithium ions, specifically, the following formula:
Li _x1 MPO ₄ {In the formula, M is at least one element selected from the group consisting of Co, Ni, Fe, Mn and Cu, and x1 satisfies 0 ≦ x1 ≦ 2. }, And Li _z V ₂ (PO ₄ ) ₃ {in the formula, z satisfies 0 ≦ z ≦ 3},
Included are at least one lithium transition metal oxide selected from the group consisting of.
Among the lithium transition metal oxides described above, from the viewpoint of achieving both high energy density and high output and maintaining their characteristics within a wide temperature range, the following formula:
Li _x2 FePO ₄ {In the formula, x2 satisfies 0.8 ≦ x2 ≦ 1.2. },
Li _x2 CoPO ₄ {In the formula, x2 satisfies 0.8 ≦ x2 ≦ 1.2. }, And Li _x2 MnPO ₄ {In the formula, x2 satisfies 0.8 ≦ x2 ≦ 1.2. },
At least one selected from the group consisting of is preferred.

The average particle size of the lithium transition metal oxide is preferably 0.1 to 20 μm. When the average particle size is 0.1 μm or more, the capacity per electrode volume tends to be high due to the high density of the active material layer. As the average particle size becomes smaller, the durability may decrease, but if the average particle size is 0.1 μm or more, such a defect is unlikely to occur. On the other hand, when the average particle size is 20 μm or less, it tends to be easy to adapt to high-speed charging / discharging. The average particle size is more preferably 0.5 to 15 μm, still more preferably 1 to 10 μm. Further, when the average particle size of the lithium transition metal oxide is smaller than the average particle size of the carbon material, the lithium transition metal oxide can be arranged in the voids formed by the carbon material having a large average particle size, and the power storage element can be arranged. It is preferable because it can reduce the resistance.

[Amount of Lithium Transition Metal Oxide]
When the content of the lithium transition metal oxide is G ₁ with reference to the total mass of the positive electrode active material layer, G ₁ is 1.0% by mass or more and 50.0% by mass or less, preferably 10.0. It is by mass% or more and 45.0% by mass or less, and more preferably 15.0% by mass or more and 40.0% by mass or less. Further, if the content G ₁ is 1.0% by mass or more, the plateau region indicated by the lithium transition metal oxide can be discriminated even on the discharge curve, so that d ² V / d Q ² calculated from the discharge curve is the maximum. It is possible to detect the voltage and increase the energy density of the power storage element. When the content rate G ₁ is 50.0% by mass or less, the power storage element can be increased in output.

[Mass ratio of activated carbon and lithium transition metal oxide]
When the mass ratio of the activated carbon in the positive electrode active material layer is A ₁ and the mass ratio of the lithium transition metal oxide is A ₂ , it is preferable that A ₂ / A ₁ is 0.1 or more and 2.5 or less. , More preferably 0.2 or more and 2.0 or less, still more preferably 0.3 or more and 1.2 or less. Further, when A ₂ / A ₁ is 0.1 or more, the bulk density of the positive electrode active material layer can be increased, and the capacity of the power storage element can be increased. If A ₂ / A ₁ is 2.5 or less, the plateau region indicated by the lithium transition metal oxide can be discriminated even on the discharge curve, so the voltage at which d ² V / d Q ² calculated from the discharge curve is maximized is detected. In addition, the resistance of the power storage element can be reduced because the electron conduction between the activated carbons is enhanced.

[Content ratio of positive electrode active material]
The content ratio of the positive electrode active material in the positive electrode active material layer is preferably 35% by mass or more and 95% by mass or less based on the total mass of the positive electrode active material layer in the positive electrode precursor. The lower limit of the content ratio of the positive electrode active material is more preferably 45% by mass or more, further preferably 55% by mass or more. On the other hand, the upper limit of the content ratio of the positive electrode active material is more preferably 90% by mass or less, further preferably 80% by mass or less. By setting the content ratio in this range, the power storage element exhibits suitable charge / discharge characteristics.

[Lithium compound]
It is preferable that the positive electrode active material layer of the positive electrode precursor of the present embodiment contains a lithium compound other than the positive electrode active material. As used herein, the term "lithium compound" is different from lithium salts as electrolytes and the lithium transition metal oxides described above.
The lithium compound according to the present embodiment is selected from lithium carbonate, lithium oxide, lithium hydroxide, lithium fluoride, lithium chloride, lithium oxalate, lithium iodide, lithium nitride, lithium oxalate, and lithium acetate 1. Seeds and above are preferably used. Among them, lithium carbonate, lithium oxide, and lithium hydroxide are more preferable, and lithium carbonate is more preferably used from the viewpoint that it can be handled in the air and has low hygroscopicity. Such a lithium compound decomposes when a voltage is applied, functions as a dopant source for lithium doping to the negative electrode, and forms pores in the positive electrode active material layer, so that the electrolytic solution has excellent retention and ionic conductivity. It is possible to form an excellent positive electrode. When an electrolytic solution in which a lithium salt such as LiPF ₆ described later is dissolved in advance is used as the non-aqueous electrolytic solution, the lithium metal carbonate can also be used alone. The lithium compound contained in the positive electrode precursor may be one kind, may contain two or more kinds of lithium compounds, or may be used as a mixture of the lithium compound and another alkali metal carbonate.

It is preferable to prepare the positive electrode precursor so that the mass ratio of the lithium compound contained in the positive electrode precursor is 10% by mass or more and 50% by mass or less. When the mass ratio of the lithium compound is 10% by mass or more, a sufficient amount of lithium ions can be pre-doped into the negative electrode, and the capacity of the non-aqueous lithium-type power storage element is increased. When the mass ratio of the lithium compound is 50% by mass or less, the electron conduction in the positive electrode precursor can be enhanced, so that the lithium compound can be efficiently decomposed.
When the positive electrode precursor contains the above two or more kinds of alkali metal compounds or alkaline earth metal compounds in addition to the lithium metal compound, the total amount of the alkali metal compound and the alkaline earth metal compound is one side of the positive electrode precursor. It is preferable to prepare the positive electrode precursor so that it is contained in the positive electrode active material layer in a proportion of 1% by mass or more and 50% by mass or less.

[Lithium compound of positive electrode precursor]
The lithium compound is preferably in the form of particles. The average particle size of the lithium compound contained in the positive electrode precursor is preferably 0.1 μm or more and 100 μm or less. The upper limit of the average particle size of the lithium compound contained in the positive electrode precursor is more preferably 50 μm or less, further preferably 20 μm or less, and most preferably 10 μm or less. On the other hand, the lower limit of the average particle size of the lithium compound contained in the positive electrode precursor is more preferably 0.3 μm or more, and further preferably 0.5 μm or more. When the average particle size of the lithium compound is 0.1 μm or more, the pores remaining after the oxidation reaction of the lithium compound in the positive electrode have a sufficient volume to hold the electrolytic solution, so that the high load charge / discharge characteristics are exhibited. improves. When the average particle size of the lithium compound is 100 μm or less, the surface area of the lithium compound does not become excessively small, so that the rate of the oxidation reaction of the lithium compound can be ensured. The upper and lower limits of the range of the average particle size of the lithium compound can be arbitrarily combined.

[Lithium compound of positive electrode]
In the present embodiment, when the average particle size of the lithium compound other than the positive electrode active material contained in the positive electrode is X ₁ , it is preferably in the range of 0.1 μm ≦ X ₁ ≦ 10.0 μm. A more preferable range of the average particle size of the lithium compound is 0.5 μm ≦ X ₁ ≦ 5.0 μm. When X ₁ is 0.1 μm or more, the high load charge / discharge cycle characteristics are improved by adsorbing the fluorine ions generated in the high load charge / discharge cycle of the power storage element. When X ₁ is 10.0 μm or less, the reaction area with the fluorine ions generated in the high load charge / discharge cycle of the power storage element increases, so that the adsorption of the fluorine ions can be efficiently performed.

The lithium compound contained in the positive electrode other than the positive electrode active material is preferably 0.5% by mass or more and 50% by mass or less, preferably 1.0% by mass or more and 25% by mass or less, based on the total mass of the positive electrode active material layer in the positive electrode. It is more preferably mass% or less. When the content of the lithium compound is 0.5% by mass or more, the reason is not necessarily clear, but the accuracy of state estimation of the non-aqueous lithium-type power storage element by the method of the present invention is high. When the content of the lithium compound is 0.5% by mass or more, the lithium compound such as lithium carbonate suppresses the decomposition reaction of the electrolytic solution solvent on the positive electrode in a high temperature environment, so that the high temperature durability is improved. The effect becomes remarkable at 5.5% by mass or more. Further, when the content of the lithium compound is 50% by mass or less, the electron conductivity between the positive electrode active materials is relatively small to be hindered by the lithium compound, so that high input / output characteristics are exhibited, and the content is 35% by mass or less. If there is, it is particularly preferable from the viewpoint of input / output characteristics. The combination of the lower limit and the upper limit of the content of the lithium compound can be arbitrary.

[Other optional components of the positive electrode active material layer]
The positive electrode active material layer in the present embodiment may contain an optional component such as a conductive filler, a binder, and a dispersion stabilizer, if necessary.
The conductive filler is not particularly limited, and for example, acetylene black, ketjen black, vapor-grown carbon fiber, graphite, carbon nanotubes, a mixture thereof and the like can be used.
The binder is not particularly limited, but for example, PVdF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), polyimide, latex, styrene-butadiene copolymer, fluororubber, acrylic copolymer and the like. Can be used.
The dispersion stabilizer is not particularly limited, but for example, PVP (polyvinylpyrrolidone), PVA (polyvinyl alcohol), a cellulose derivative and the like can be used.

[Positive current collector]
The material constituting the positive electrode current collector in the present embodiment is not particularly limited as long as it has high electron conductivity and does not deteriorate due to elution into the electrolytic solution and reaction with the electrolyte or ions, but is not particularly limited. Foil is preferred. Aluminum foil is more preferable as the positive electrode current collector in the non-aqueous lithium-type power storage element of the present embodiment.

The metal foil may be a normal metal foil having no irregularities or through holes, a metal foil having irregularities subjected to embossing, chemical etching, electrolytic precipitation, blasting, etc., expanded metal, punching metal, etc. , A metal foil having through holes such as an etching foil may be used.
In particular, from the viewpoint of ease of electrode production and high electron conductivity, the positive electrode current collector is preferably non-porous.
As used herein, the term "non-porous positive electrode current collector" means that lithium ions pass through the positive electrode current collector and lithium ions are generated on the front and back of the positive electrode, at least in the coated region of the positive electrode active material layer. It means a positive electrode current collector that does not have enough holes to make it uniform. Therefore, the non-pore-shaped positive electrode current collector has holes in the uncoated region of the positive electrode current collector having extremely small diameter or a small amount of holes and the positive electrode active material layer within the range in which the effect of the present invention is exhibited. It does not exclude the positive electrode current collector.
Further, it is more preferable that at least the region of the positive electrode current collector coated with the positive electrode active material layer is non-porous, and the surplus portion of the positive electrode current collector not coated with the positive electrode active material has holes. It may or may not be present.
The thickness of the positive electrode current collector is not particularly limited as long as the shape and strength of the positive electrode can be sufficiently maintained, but is preferably 1 to 100 μm, for example.

[Manufacturing of positive electrode precursor]
In the present embodiment, the positive electrode precursor to be the positive electrode of the non-aqueous lithium-type power storage element can be manufactured by a technique for manufacturing electrodes in known lithium ion batteries, electric double layer capacitors and the like. For example, activated carbon and a lithium transition metal compound as a positive electrode active material, a lithium compound used as necessary, and other optional components are dispersed or dissolved in water or an organic solvent to prepare a slurry coating liquid. A positive electrode precursor can be obtained by applying this coating liquid to one side or both sides of the positive electrode current collector to form a coating film and drying the coating liquid. Further, the obtained positive electrode precursor may be pressed to adjust the film thickness or bulk density of the positive electrode active material layer. Alternatively, without using a solvent, the activated carbon and the lithium transition metal compound as the positive electrode active material, and the lithium compound used as necessary, and other optional components are mixed in a dry manner, and the obtained mixture is pressed. After molding, it is also possible to attach it to the positive electrode current collector using a conductive adhesive.

The coating liquid of the positive electrode precursor was a dry blend of a part or all of various material powders including the positive electrode active material, and then water or an organic solvent and / or a binder or a dispersion stabilizer was dissolved or dispersed in them. Liquid or slurry substances may be added and prepared. Further, various material powders containing a positive electrode active material may be added to a liquid or slurry-like substance in which a binder or a dispersion stabilizer is dissolved or dispersed in water or an organic solvent to prepare a coating liquid. good. As the dry blending method, for example, a positive electrode active material and a lithium compound are premixed using a ball mill or the like, and if necessary, a conductive filler is premixed, and a premixed lithium compound having low conductivity is coated with the conductive filler. You may. This facilitates the decomposition of the lithium compound in the positive electrode precursor in the lithium doping step described later. When water is used as the solvent of the coating liquid, the coating liquid may become alkaline by adding the lithium compound, and therefore a pH adjuster may be added if necessary.
The preparation of the coating liquid for the positive electrode precursor is not particularly limited, but preferably a homodisper or a multi-axis disperser, a planetary mixer, a disperser such as a thin film swirling high-speed mixer or the like may be used. can.
The formation of the coating film of the positive electrode precursor is not particularly limited, but a coating machine such as a die coater or a comma coater, a knife coater, or a gravure coating machine can be preferably used. The coating film may be formed by a single-layer coating or a multi-layer coating. In the case of multi-layer coating, the coating liquid composition may be adjusted so that the content of the lithium compound in each layer of the coating film is different.

The drying of the coating film of the positive electrode precursor is not particularly limited, but a drying method such as hot air drying or infrared (IR) drying can be preferably used. The coating film may be dried at a single temperature, or may be dried at different temperatures in multiple stages. Further, the coating film may be dried by combining a plurality of drying methods. The drying temperature is preferably 25 ° C. or higher and 200 ° C. or lower, more preferably 40 ° C. or higher and 180 ° C. or lower, and further preferably 50 ° C. or higher and 160 ° C. or lower. When the drying temperature is 25 ° C. or higher, the solvent in the coating film can be sufficiently volatilized. On the other hand, when the drying temperature is 200 ° C. or lower, it is possible to suppress cracking of the coating film due to rapid volatilization of the solvent or uneven distribution of the binder due to migration, and oxidation of the positive electrode current collector or the positive electrode active material layer.

The press of the positive electrode precursor is not particularly limited, but a press machine such as a hydraulic press machine or a vacuum press machine can be preferably used. The film thickness, bulk density and electrode strength of the positive electrode active material layer can be adjusted by the press pressure, the gap, and the surface temperature of the press portion, which will be described later.
Further, the surface temperature of the pressed portion may be room temperature, or the pressed portion may be heated if necessary. The lower limit of the surface temperature of the pressed portion in the case of heating is preferably a melting point of minus 60 ° C. or higher, more preferably a melting point of −45 ° C. or higher, and further preferably a melting point of −30 ° C. or higher. On the other hand, the upper limit of the surface temperature of the pressed portion in the case of heating is preferably the melting point of the binder to be used plus 50 ° C. or lower, more preferably the melting point plus 30 ° C. or lower, and further preferably the melting point plus 20 ° C. or lower. For example, when PVdF (polyvinylidene fluoride: melting point 150 ° C.) is used as the binder, it is preferable to heat the surface of the pressed portion to 90 ° C. or higher and 200 ° C. or lower, more preferably 105 ° C. or higher and 180 ° C. or lower, and further. It is preferable to heat the surface of the press portion to 120 ° C. or higher and 170 ° C. or lower. When a styrene-butadiene copolymer (melting point 100 ° C.) is used as the binder, it is preferable to heat the surface of the pressed portion to 40 ° C. or higher and 150 ° C. or lower, and more preferably 55 ° C. or higher and 130 ° C. or lower. More preferably, the surface of the pressed portion is heated to 70 ° C. or higher and 120 ° C. or lower.
The melting point of the binder can be determined from the endothermic peak position of DSC (Differential Scanning Calorimetry). For example, using a differential scanning calorimeter "DSC7" manufactured by PerkinElmer, 10 mg of sample resin is set in a measurement cell, and the temperature rises from 30 ° C. to 250 ° C. at a temperature rise rate of 10 ° C./min in a nitrogen gas atmosphere. The temperature rises, and the heat absorption peak temperature in the temperature rise process becomes the melting point.
Further, the press may be performed a plurality of times while changing the conditions of the press pressure, the gap, the speed, and the surface temperature of the press portion.

The texture of the positive electrode active material layer is preferably 20 g · m ^{-2 or more and 150 g · m -2 or} less per one side of the positive electrode current collector, and more preferably 25 g · m ^-2 or more and 120 g · m ^-2 or less per one side. It is more preferably 30 g · m ^-2 or more and 80 g · m ^-2 or less. If the grain size is 20 g · m ^-2 or more, the deterioration of the resistance of the positive electrode can be suppressed to be smaller than the deterioration of the resistance of the negative electrode. It is possible to estimate, and the power storage element can develop a sufficient charge / discharge capacity. On the other hand, if the basis weight is 150 g · m ^-2 or less, the ion diffusion resistance in the electrode can be kept low, so that sufficient output characteristics can be obtained and the cell volume can be reduced, so that the energy can be reduced. The density can be increased. The upper and lower limits of the basis weight range of the positive electrode active material layer can be arbitrarily combined.

The film thickness of the positive electrode active material layer is preferably 20 μm or more and 200 μm or less per one side of the positive electrode current collector, more preferably 25 μm or more and 140 μm or less per one side, and further preferably 30 μm or more and 100 μm or less. When this film thickness is 20 μm or more, the resistance deterioration of the positive electrode can be suppressed to be smaller than the resistance deterioration of the negative electrode. Therefore, the discharge resistance and the charge resistance of the power storage element are estimated by the method of the present invention focusing on the deterioration of the negative electrode. It is possible, and the power storage element can develop a sufficient charge / discharge capacity. On the other hand, if this film thickness is 200 μm or less, the ion diffusion resistance in the electrode can be kept low, sufficient output characteristics can be obtained, and the cell volume can be reduced, so that the energy density can be increased. Can be done. The upper and lower limits of the film thickness range of the positive electrode active material layer can be arbitrarily combined. The film thickness of the positive electrode active material layer when the current collector has through holes or irregularities means the average value of the film thickness per surface of the portion of the current collector that does not have through holes or irregularities.

[Positive electrode after lithium doping process]
The bulk density of the positive electrode active material layer in the positive electrode after the lithium doping step described later is preferably 0.25 g / cm ³ or more, more preferably 0.30 g / cm ³ or more and 1.3 g / cm ³ or less. Is. When the bulk density of the positive electrode active material layer is 0.25 g / cm ³ or more, a high energy density can be exhibited and the miniaturization of the power storage element can be achieved. On the other hand, when the bulk density is 1.3 g / cm ³ or less, the diffusion of the electrolytic solution in the pores in the positive electrode active material layer is sufficient, and the resistance deterioration of the positive electrode can be suppressed to be smaller than the resistance deterioration of the negative electrode. By the method of the present invention focusing on the deterioration of the negative electrode, it is possible to estimate the discharge resistance and the charge resistance of the power storage element, and the power storage element can obtain high output characteristics.

[Method for measuring the amount of carbon material and lithium transition metal oxide in the positive electrode active material layer]
When the mass ratio of the carbon material contained in the positive electrode active material layer is A ₁ , the mass ratio of the lithium transition metal oxide is A ₂ , and the mass ratio of other components is A ₃ , the method for quantifying these values is particularly effective. Although not limited, it can be quantified by, for example, the following method.
The area of the positive electrode to be measured is not particularly limited, but is preferably 5 cm ² or more and 200 cm ² or less, and more preferably 25 cm ² or more and 150 cm ² or less, from the viewpoint of reducing variations in measurement. If the area is 5 cm ² or more, the reproducibility of the measurement is ensured. If the area is 200 cm ² or less, the handling of the sample is excellent.
First, the non-aqueous lithium-type power storage element is disassembled in an Ar box installed in a room at 23 ° C. and controlled at a dew point of −90 ° C. or lower and an oxygen concentration of 1 ppm or less, and the positive electrode is taken out. The removed positive electrode is immersed and washed with dimethyl carbonate (DMC), and then vacuum dried in a side box while maintaining no exposure to the atmosphere. The weight (M ₀ ) of the positive electrode obtained after vacuum drying is measured. Subsequently, the mixture is immersed in distilled water having 100 to 150 times the weight of the positive electrode for 3 days or more to elute components other than the carbon material and the lithium transition metal oxide into the water. It is preferable to cover the container so that the distilled water does not volatilize during the immersion. After soaking for 3 days or more, the positive electrode is taken out from the distilled water and vacuum dried in the same manner as above. The weight (M ₁ ) of the obtained positive electrode is measured. Subsequently, the positive electrode active material layer applied to one side or both sides of the positive electrode current collector is removed using a spatula, a brush, a brush, or the like. The weight (M ₂ ) of the remaining positive electrode current collector is measured, and A ₃ is calculated by the following equation (1).
A ₃ = (M ₀ -M ₁ ) / (M ₀ -M ₂ ) x 100 (1)

Subsequently, in order to calculate A ₁ and A ₂ , the TG curve of the positive electrode active material layer obtained by removing the alkali metal compound is measured under the following conditions.
・ Sample pan: Platinum ・ Gas: Air atmosphere or compressed air ・ Temperature rise rate: 0.5 ℃ / min or less ・ Temperature range: 25 ℃ ～ 500 ℃ or more ・ Melting point of lithium transition metal oxide -50 ℃ or less The mass of the obtained TG curve at 25 ° C. is defined as M3 _, and the mass at the initial temperature at which the mass reduction rate becomes _M3 × 0.01 / min or less at a temperature of 500 ° C. or higher is defined as _M4 .
All carbon materials are oxidized and burned by heating at a temperature of 500 ° C. or lower in an oxygen-containing atmosphere (for example, an atmospheric atmosphere). On the other hand, the mass of the lithium transition metal oxide does not decrease up to the temperature of minus 50 ° C., which is the melting point of the lithium transition metal oxide, even in an oxygen-containing atmosphere.
Therefore, the content A ₂ of the lithium transition metal oxide in the positive electrode active material layer can be calculated by the following equation (2).
A ₂ = (M ₄ / M ₃ ) × {1- (M ₀ − M ₁ ) / (M ₀ − M ₂ )} × 100 (2) Equation The content of carbon material in the positive electrode active material layer A ₁ Can be calculated by the following equation (3).
A ₁ = {(M ₃ -M ₄ ) / M ₃ } x {1- (M ₀ -M ₁ ) / (M ₀ -M ₂ )} x 100 (3)

[Negative electrode]
The negative electrode has a negative electrode current collector and a negative electrode active material layer existing on one side or both sides thereof.
The negative electrode active material layer contains a negative electrode active material capable of occluding and releasing lithium ions. The negative electrode active material layer may contain an optional component such as a conductive filler, a binder, and a dispersion stabilizer, if necessary, in addition to the negative electrode active material.

[Negative electrode active material]
As the negative electrode active material, a material capable of occluding and releasing lithium ions can be used. From the viewpoint of achieving both the output and the capacity of the power storage element and maintaining them within a wide temperature range, two types of negative electrode active materials may be used.
Specific examples of the negative electrode active material include carbon materials, titanium oxides, silicon, silicon oxides, silicon alloys, silicon compounds, tin and tin compounds. The content of the carbon material with respect to the total amount of the negative electrode active material is preferably 50% by mass or more, and more preferably 70% by mass or more. The content of the carbon material may be 100% by mass, but from the viewpoint of obtaining a good effect by using other materials in combination, for example, it is preferably 90% by mass or less, and more preferably 80% by mass or less. ..

The negative electrode active material is preferably doped with lithium ions. In the present specification, the lithium ion doped in the negative electrode active material mainly includes three forms.
The first form is lithium ion, which is preliminarily occluded as a design value in the negative electrode active material before manufacturing the non-aqueous lithium-type power storage element.
The second form is lithium ions stored in the negative electrode active material when a non-aqueous lithium-type power storage element is manufactured and shipped.
The third form is lithium ions occluded in the negative electrode active material after using the non-aqueous lithium-type power storage element as a device.
By doping the negative electrode active material with lithium ions, it is possible to satisfactorily control the capacity and operating voltage of the obtained non-aqueous lithium-type power storage element.

Examples of the carbon material include refractory carbon materials; easily graphitizable carbon materials; carbon black; carbon nanoparticles; activated carbon; artificial graphite; natural graphite; graphitized mesophase carbon spherules; graphite whiskers; polyacenese-based substances. Amorphous carbonaceous materials such as; petroleum-based pitches, coal-based pitches, mesocarbon microbeads, coke, carbonic materials such as synthetic resins (eg, phenolic resins, etc.) Carbonated materials obtained by heat treatment of precursors; full Thermal decomposition products of frill alcohol resin or novolak resin; fullerene; carbon nanophones; and composite carbon materials thereof can be mentioned.

In the present embodiment, the negative electrode active material layer preferably has a specific surface area of 4 m ² / g or more and 75 m ² / g or less calculated by the BET method based on the weight of the negative electrode active material. The lower limit of the specific surface area calculated by the BET method is more preferably 5 m ² / g or more, further preferably 6 m ² / g or more, and particularly preferably 7 m ² / g or more. The upper limit of the specific surface area calculated by the BET method is 60 m ² / g or less, more preferably 40 m ² / g or less, and particularly preferably 30 m ² / g or less.
Alternatively, the negative electrode active material layer comprises at least one selected from the group consisting of lithium titanate capable of occluding and releasing lithium ions and titanium oxide capable of occluding and releasing lithium ions as the negative electrode active material. It may be included. For example, lithium titanate is represented by the general formula Li _x T _y O ₄ (where x satisfies 0.8 ≦ x ≦ 1.4 and y satisfies 1.6 ≦ y ≦ 2.2). Will be done. For example, examples of titanium oxide include rutile-type titanium oxide and anatase-type titanium oxide. Among these, Li _4/3 Ti _5/3 O ₄ is preferred from the viewpoint that the increase in reaction resistance due to the insertion and desorption of Li ions is small and high output can be maintained even in a low temperature environment.

[Other optional components of the negative electrode active material layer]
The negative electrode active material layer according to the present embodiment may contain an optional component such as a conductive filler, a binder, and a dispersion stabilizer, in addition to the negative electrode active material, if necessary.
The type of the conductive filler is not particularly limited, and examples thereof include acetylene black, ketjen black, and vapor phase grown carbon fiber.
The binder is not particularly limited, but for example, PVdF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), polyimide, latex, styrene-butadiene copolymer, fluororubber, acrylic copolymer and the like. Can be used.
The dispersion stabilizer is not particularly limited, but for example, PVP (polyvinylpyrrolidone), PVA (polyvinyl alcohol), a cellulose derivative and the like can be used.

[Negative electrode current collector]
The material constituting the negative electrode current collector in the present invention is preferably a metal foil having high electron conductivity and not deteriorated by elution into a non-aqueous electrolyte solution and reaction with an electrolyte or ions. The metal foil is not particularly limited, and examples thereof include aluminum foil, copper foil, nickel foil, and stainless steel foil. Copper foil is preferable as the negative electrode current collector in the non-aqueous lithium power storage device of the present embodiment.
The metal foil may be a normal metal foil having no irregularities or through holes, a metal foil having irregularities subjected to embossing, chemical etching, electrolytic precipitation, blasting, etc., expanded metal, punching metal, etc. , A metal foil having through holes such as an etching foil may be used.
In particular, from the viewpoint of ease of electrode production and high electron conductivity, the negative electrode current collector in the present embodiment is preferably non-porous.
In the present specification, the “non-porous negative electrode current collector” means that lithium ions pass through the negative electrode current collector and the lithium ions are uniform on the front and back surfaces of the negative electrode, at least in the coated region of the negative electrode active material layer. It means a negative electrode current collector that does not have enough holes to be converted. Therefore, the non-pore-shaped negative electrode current collector has holes in the negative electrode current collector having extremely small diameter or a small amount of holes and in the uncoated region of the negative electrode active material layer within the range in which the effect of the present invention is exhibited. It does not exclude the negative electrode current collector. Further, it is more preferable that at least the region of the negative electrode current collector coated with the negative electrode active material layer is non-porous, and the surplus portion of the negative electrode current collector not coated with the negative electrode active material has holes. It may or may not be present.
The thickness of the negative electrode current collector is not particularly limited as long as the shape and strength of the negative electrode can be sufficiently maintained, but is preferably 1 to 100 μm, for example. When the negative electrode current collector has holes or irregularities, the thickness of the negative electrode current collector shall be measured based on the portion where the holes or irregularities do not exist.

[Manufacturing of negative electrode]
The negative electrode has a negative electrode active material layer on one side or both sides of the negative electrode current collector. In a typical embodiment, the negative electrode active material layer is fixed to the negative electrode current collector.
The negative electrode can be manufactured by a technique for manufacturing electrodes in known lithium ion batteries, electric double layer capacitors and the like. For example, various materials including the negative electrode active material are dispersed or dissolved in water or an organic solvent to prepare a slurry-like coating liquid, and this coating liquid is applied to one or both sides of the negative electrode current collector. A negative electrode can be obtained by forming a coating film and drying it. Further, the obtained negative electrode may be pressed to adjust the film thickness or bulk density of the negative electrode active material layer. Alternatively, a method in which various materials including a negative electrode active material are mixed in a dry manner without using a solvent, the obtained mixture is press-molded, and then attached to a negative electrode current collector using a conductive adhesive. Is also possible.

The coating liquid is a liquid or slurry in which a part or all of various material powders including the negative electrode active material is dry-blended, and then water or an organic solvent and / or a binder or a dispersion stabilizer is dissolved or dispersed therein. The substance may be added and prepared. Further, various material powders containing a negative electrode active material may be added to a liquid or slurry-like substance in which a binder or a dispersion stabilizer is dissolved or dispersed in water or an organic solvent to prepare a coating liquid. .. The preparation of the coating liquid is not particularly limited, but a homodisper or a multi-axis disperser, a planetary mixer, a disperser such as a thin film swirling high-speed mixer and the like can be preferably used.
The formation of the coating film is not particularly limited, but a coating machine such as a die coater, a comma coater, a knife coater, or a gravure coating machine can be preferably used. The coating film may be formed by a single-layer coating or a multi-layer coating.

The drying of the coating film is not particularly limited, but a drying method such as hot air drying or infrared (IR) drying can be preferably used. The coating film may be dried at a single temperature, or may be dried at different temperatures in multiple stages. Further, the coating film may be dried by combining a plurality of drying methods. The drying temperature is preferably 25 ° C. or higher and 200 ° C. or lower. The drying temperature is more preferably 40 ° C. or higher and 180 ° C. or lower, and further preferably 50 ° C. or higher and 160 ° C. or lower. When the drying temperature is 25 ° C. or higher, the solvent in the coating film can be sufficiently volatilized. On the other hand, when the drying temperature is 200 ° C. or lower, it is possible to suppress cracking of the coating film due to rapid volatilization of the solvent or uneven distribution of the binder due to migration, and oxidation of the negative electrode current collector or the negative electrode active material layer.

The press of the negative electrode is not particularly limited, but a press machine such as a hydraulic press machine or a vacuum press machine can be preferably used. The film thickness, bulk density, and electrode strength of the negative electrode active material layer can be adjusted by the press pressure, the gap, and the surface temperature of the press portion, which will be described later. The surface temperature of the pressed portion may be room temperature or may be heated if necessary. The lower limit of the surface temperature of the pressed portion in the case of heating is preferably a melting point of minus 60 ° C. or higher, more preferably a melting point of −45 ° C. or higher, and further preferably a melting point of −30 ° C. or higher. On the other hand, the upper limit of the surface temperature of the pressed portion in the case of heating is preferably the melting point of the binder to be used plus 50 ° C. or lower, more preferably the melting point plus 30 ° C. or lower, and further preferably the melting point plus 20 ° C. or lower. For example, when PVdF (polyvinylidene fluoride: melting point 150 ° C.) is used as the binder, it is preferable to heat the surface temperature of the pressed portion to 90 ° C. or higher and 200 ° C. or lower. The surface temperature of the pressed portion is more preferably 105 ° C. or higher and 180 ° C. or lower, and further preferably 120 ° C. or higher and 170 ° C. or lower. When a styrene-butadiene copolymer (melting point 100 ° C.) is used as the binder, it is preferable to heat the surface temperature of the pressed portion to 40 ° C. or higher and 150 ° C. or lower. The surface temperature of the pressed portion is more preferably 55 ° C. or higher and 130 ° C. or lower, and further preferably 70 ° C. or higher and 120 ° C. or lower.
The melting point of the binder can be determined from the endothermic peak position of DSC (Differential Scanning Calorimetry). For example, using a differential scanning calorimeter "DSC7" manufactured by PerkinElmer, 10 mg of sample resin is set in a measurement cell, and the temperature rises from 30 ° C. to 250 ° C. at a temperature rise rate of 10 ° C./min in a nitrogen gas atmosphere. The temperature rises, and the heat absorption peak temperature in the temperature rise process becomes the melting point.
Further, the press may be performed a plurality of times while changing the conditions of the press pressure, the gap, the speed, and the surface temperature of the press portion.

The texture of the negative electrode active material layer is preferably 10 g · m ^{-2 or more and 100 g · m -2 or} less per one side of the negative electrode current collector, and more preferably 12 g · m ^-2 or more and 80 g · m ^-2 or less per one side. It is more preferably 15 g · m ^-2 or more and 50 g · m ^-2 or less. When the basis weight is 10 g · m − ² or more, the high load charge / discharge characteristics of the power storage element can be improved. On the other hand, if the grain size is 100 g · m ^-2 or less, the resistance deterioration of the negative electrode progresses faster than the resistance deterioration of the positive electrode. It is possible to estimate the resistance, and the energy storage element can obtain sufficient output characteristics, reduce the cell volume, and increase the energy density. The upper and lower limits of the basis weight range of the negative electrode active material layer can be arbitrarily combined.
The film thickness of the negative electrode active material layer is preferably 10 μm or more and 150 μm or less per one side. The lower limit of the film thickness of the negative electrode active material layer is more preferably 12 μm or more, still more preferably 15 μm or more. The upper limit of the film thickness of the negative electrode active material layer is more preferably 120 μm or less, still more preferably 80 μm or less. When this film thickness is 10 μm or more, no streaks or the like are generated when the negative electrode active material layer is applied, and the coatability is excellent. On the other hand, if this film thickness is 150 μm or less, the resistance deterioration of the negative electrode progresses faster than the resistance deterioration of the positive electrode. Therefore, the discharge resistance and charge resistance of the power storage element are estimated by the method of the present invention focusing on the deterioration of the negative electrode. It is possible to achieve high energy density by reducing the cell volume. The film thickness of the negative electrode active material layer when the current collector has through holes or irregularities means the average value of the film thickness per surface of the portion of the current collector that does not have through holes or irregularities.
The bulk density of the negative electrode active material layer is preferably 0.30 g / cm ³ or more and 1.8 g / cm ³ or less, more preferably 0.40 g / cm ³ or more and 1.5 g / cm ³ or less, and further preferably 0. .45 g / cm ³ or more and 1.3 g / cm ³ or less. When the bulk density is 0.30 g / cm ³ or more, sufficient strength can be maintained and sufficient conductivity between the negative electrode active materials can be exhibited. Further, when the bulk density is 1.8 g / cm ³ or less, it is possible to secure pores in which ions can sufficiently diffuse in the negative electrode active material layer, and the resistance deterioration of the negative electrode progresses faster than the resistance deterioration of the positive electrode. Therefore, it is possible to estimate the discharge resistance and the charge resistance of the power storage element by the method of the present invention focusing on the deterioration of the negative electrode.

[Design of positive and negative electrodes]
In the present embodiment, when the positive electrode active material layer of the positive electrode is C ₁ (g / m ² ) and the negative electrode active material layer of the negative electrode is C ₂ (g / m ² ), C ₁ / C ₂ Is preferably 0.35 or more and 5.80 or less. It is more preferably 0.40 or more and 3.00 or less, and further preferably 0.60 or more and 2.50 or less. When C ₁ / C ₂ is 0.35 or more, the negative electrode potential can be lowered by sufficiently predoping lithium ions from the positive electrode precursor containing the lithium compound to the negative electrode, so that the energy density of the energy storage element is improved. can do. On the other hand, if C ₁ / C ₂ is 5.80 or less, the resistance deterioration of the negative electrode progresses faster than the resistance deterioration of the positive electrode. It is possible to estimate the charging resistance, and the surface activation reaction of the positive electrode active material by the doping reaction of the lithium compound contained in the positive electrode active material layer proceeds sufficiently, so that the capacity of the power storage element is improved and the output is increased. Can be expected.
When the thickness of the positive electrode active material layer of the positive electrode is D ₁ (μm) and the thickness of the negative electrode active material layer of the negative electrode is D ₂ (μm), D ₁ / D ₂ is 0.30 or more and 5.00 or less. It is preferably 0.70 or more and 3.50 or less, and further preferably 1.00 or more and 2.50 or less. When D ₁ / D ₂ is 0.30 or more, the lithium ion diffusion rate in the negative electrode active material layer with respect to the surface adsorption rate of lithium ions in the positive electrode active material layer increases, so that the output characteristics of the power storage element can be improved. On the other hand, if D ₁ / D ₂ is 5.00 or less, the resistance deterioration of the negative electrode progresses faster than the resistance deterioration of the positive electrode. Since the charging resistance can be estimated and the lithium ion diffusion rate in the positive electrode active material layer with respect to the insertion reaction of lithium ions in the negative electrode active material layer is increased, the input characteristics of the power storage element can be improved.

[Calculation of positive electrode active material layer weight]
In the case of a positive electrode precursor, a part of the positive electrode precursor is cut out into a predetermined area and the weight is measured. The area of the positive electrode to be measured is not particularly limited, but is preferably 5 cm ² or more and 200 cm ² or less, and more preferably 25 cm ² or more and 150 cm ² or less, from the viewpoint of reducing variations in measurement. If the area is 5 cm ² or more, the reproducibility of the measurement is ensured. If the area is 200 cm ² or less, the handling of the sample is excellent. Subsequently, the positive electrode active material layer of the positive electrode precursor is scraped off with a spatula, a brush, a brush, or the like, and the weight of the positive electrode current collector foil is measured. Assuming that the area of the cut-out positive electrode precursor is S _ZC (m ² ), the weight of the cut-out positive electrode precursor is M _{ZC 1} (g), and the weight of the positive electrode current collector foil is M ZC 2 (g), the positive electrode _activity of the positive electrode precursor is taken. The material layer C _Z1 can be calculated by the following formula (4).
C _Z1 (g · m ^-2 ) = (M _ZC1 -M _ZC2) / S _ZC formula (4)
The method of calculating the basis weight of the positive electrode active material in the case of the positive electrode that has undergone the lithium doping step is described below. In the argon box, the non-aqueous lithium-type power storage element whose voltage is adjusted to 2.9 V is disassembled to take out the electrode laminate, and the positive electrode is cut out from the electrode laminate and washed with an organic solvent. The organic solvent is not particularly limited as long as it can remove the electrolyte decomposition product deposited on the surface of the positive electrode, but the elution of the lithium compound is suppressed by using an organic solvent having a solubility of the lithium compound of 2% or less. As such an organic solvent, for example, a polar solvent such as methanol, ethanol, acetone, or methyl acetate is preferably used. The area of the positive electrode to be measured is not particularly limited, but is preferably 5 cm ² or more and 200 cm ² or less, and more preferably 25 cm ² or more and 150 cm ² or less, from the viewpoint of reducing variations in measurement. If the area is 5 cm ² or more, the reproducibility of the measurement is ensured. If the area is 200 cm ² or less, the handling of the sample is excellent.

The method for cleaning the positive electrode is to sufficiently immerse the positive electrode in an ethanol solution 50 to 100 times the weight of the positive electrode for 3 days or more. For example, it is preferable to cover the container so that the ethanol does not volatilize during the immersion. After soaking for 3 days or more, the positive electrode is removed from ethanol and vacuum dried. The vacuum drying conditions are such that the residual ethanol in the positive electrode is 1% by mass or less in the range of temperature: 100 to 200 ° C., pressure: 0 to 10 kPa, and time: 5 to 20 hours. The residual amount of ethanol can be quantified based on the calibration curve prepared in advance by measuring the GC / MS of the water after washing with distilled water, which will be described later.
The area of the positive electrode obtained after vacuum drying is defined as _XC (m ² ). All the positive electrode active material layers of the positive electrode are removed using a spatula, a brush, a brush, or the like, and the weight of the positive electrode active material layer is M _0xC (g), and the weight M _{x 2C} of the obtained positive electrode current collector is measured. Then, it is sufficiently immersed in distilled water having 100 to 150 times the weight of the measured positive electrode active material layer for 3 days or more. It is preferable to cover the container so that the distilled water does not volatilize during the immersion, and it is preferable to occasionally agitate the aqueous solution to promote the elution of the lithium compound. After soaking for 3 days or more, the positive electrode active material layer is taken out from distilled water, vacuum dried in the same manner as the above ethanol washing, and the weight M _{x 1C} (g) after vacuum drying is measured. The basis weight C _x 1 (g / m ² ) of the positive electrode active material layer can be calculated by the mathematical formula (5).
_{C x1} = (M _x1C -M _x2C ) / XC formula (5)

[Calculation of negative electrode active material layer grain]
In the case of the negative electrode before the liquid injection process, a part of the negative electrode is cut out to a predetermined area and the weight is measured. The area of the negative electrode to be measured is not particularly limited, but is preferably 5 cm ² or more and 200 cm ² or less, and more preferably 25 cm ² or more and 150 cm ² or less, from the viewpoint of reducing variations in measurement. If the area is 5 cm ² or more, the reproducibility of the measurement is ensured. If the area is 200 cm ² or less, the handling of the sample is excellent. Subsequently, the negative electrode active material layer in the negative electrode is scraped off with a spatula, a brush, a brush, or the like, and the weight of the negative electrode current collector foil is measured. Assuming that the area of the cut-out negative electrode is S _ZA (m ² ), the weight of the cut-out negative electrode is M _ZA1 (g), and the weight of the negative electrode current collector foil is M _{ZA 2} (g), the positive electrode active material layer of the positive electrode precursor is A. _Z1 can be calculated by the following formula (6).
A _Z1 (g · m ^-2 ) = (M _ZA1 -M ZA2 ₎ / S _ZA formula (6)
The method for quantifying the basis weight of the negative electrode active material layer in the case of the negative electrode that has undergone the lithium doping step is described below. The negative electrode is cut out from the electrode laminate in the argon box and washed with an organic solvent. The organic solvent used for cleaning is preferably a solvent that removes electrolyte decomposition products deposited on the surface of the negative electrode and reacts with lithium ions in the negative electrode, and is not particularly limited, but is limited to alcohols such as methanol, ethanol and isopropanol, or these. The mixed solvent of is preferably used.
The area of the negative electrode to be measured is not particularly limited, but is preferably 5 cm ² or more and 200 cm ² or less, and more preferably 25 cm ² or more and 150 cm ² or less, from the viewpoint of reducing variations in measurement. If the area is 5 cm ² or more, the reproducibility of the measurement is ensured. If the area is 200 cm ² or less, the handling of the sample is excellent.

The method for cleaning the negative electrode is to sufficiently immerse the negative electrode in an ethanol solution 50 to 100 times the weight of the negative electrode for 3 days or more. For example, it is preferable to cover the container so that the ethanol does not volatilize during the immersion. After soaking for 3 days or more, the negative electrode is removed from ethanol and vacuum dried. The vacuum drying conditions are such that the residual ethanol in the negative electrode is 1% by mass or less in the range of temperature: 100 to 200 ° C., pressure: 0 to 10 kPa, and time: 5 to 20 hours.
Regarding the residual amount of ethanol, after immersing the negative electrode after vacuum drying in an organic solvent such as dimethyl carbonate, diethyl carbonate, or ethylmethyl carbonate, the GC / MS of the organic solvent was measured, and the calibration curve prepared in advance was used as a basis. Can be quantified.
The area of the negative electrode obtained after vacuum drying is defined as X _A (m ² ). All the negative electrode active material layers of the negative electrode are removed using a spatula, a brush, a brush, or the like, and the weight M _0xA (g) of the negative electrode active material layer and the weight M _{x 2A} of the obtained negative electrode current collector are measured. Then, it is sufficiently immersed in distilled water having 100 to 150 times the weight of the measured negative electrode active material layer for 3 days or more. It is preferable to cover the container so that the distilled water does not volatilize during the immersion, and it is preferable to occasionally agitate the aqueous solution to promote the elution of the lithium compound. After soaking for 3 days or more, the negative electrode active material layer is taken out from the distilled water and vacuum dried in the same manner as the above ethanol washing. The weight M _{x 1A} (g) after vacuum drying is measured. The basis weight A _x1 (g / m ² ) of the negative electrode active material layer can be calculated by the mathematical formula (7).
_{A x1} = (M _x1A -M _x2A ) / XA formula (7)

[Electrolytic solution]
The electrolytic solution of the present embodiment is non-aqueous, that is, the electrolytic solution contains a non-aqueous solvent described later. The non-aqueous electrolyte solution preferably contains 0.5 mol / L or more of a lithium salt based on the total amount of the non-aqueous electrolyte solution. That is, the non-aqueous electrolyte solution preferably contains lithium ions as an electrolyte.

[Lithium salt]
The non-aqueous electrolyte solution of the present embodiment has, as lithium salts, for example, (LiN (SO ₂ F) ₂ ), LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiN (SO ₂ ). CF ₃ ) (SO ₂ C ₂ F ₅ ), LiN (SO ₂ CF ₃ ) (SO ₂ C ₂ F ₄ H), LiC (SO ₂ F) ₃ , LiC (SO ₂ CF ₃ ) ₃ , LiC (SO ₂ ) C ₂ F ₅ ) ₃ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiPF ₆ , LiBF ₄ , etc. can be used alone, or two or more of them may be mixed and used. The non-aqueous electrolyte solution preferably contains at least one selected from the group consisting of LiPF ₆ , LiN (SO ₂ F) ₂ and LiBF ₄ because of its ability to exhibit high conductivity, and LiPF ₆ and / or LiBF ₄ It is more preferable to contain LiPF ₆ and / or LiBF ₄ and LiN (SO ₂ F) ₂ .
The lithium salt concentration in the non-aqueous electrolyte solution is preferably 0.5 mol / L or more, more preferably 0.5 mol / L or more and 2.0 mol / L or less, based on the total amount of the non-aqueous electrolyte solution. .. When the lithium salt concentration is 0.5 mol / L or more, anions are sufficiently present, so that the capacity of the power storage element can be sufficiently increased. Further, when the lithium salt concentration is 2.0 mol / L or less, it is possible to prevent undissolved lithium salt from precipitating in the non-aqueous electrolytic solution and the viscosity of the electrolytic solution from becoming too high, resulting in a decrease in conductivity. It is preferable because it does not deteriorate the output characteristics.

[Non-aqueous solvent]
The non-aqueous electrolyte solution of the present embodiment contains a cyclic carbonate as a non-aqueous solvent. The inclusion of the cyclic carbonate in the non-aqueous electrolyte solution is advantageous in that it dissolves a lithium salt having a desired concentration and that an appropriate amount of the lithium compound is deposited in the positive electrode active material layer. Examples of the cyclic carbonate include ethylene carbonate (EC), propylene carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate and the like.
The total content of the cyclic carbonate is preferably 15% by mass or more, more preferably 20% by mass or more, based on the total amount of the non-aqueous electrolyte solution. When the total content is 15% by mass or more, it is possible to dissolve a lithium salt having a desired concentration, exhibit high lithium ion conductivity, and further deposit an appropriate amount of lithium compound on the positive electrode active material layer. It is possible to suppress the oxidative decomposition of the electrolytic solution.

The non-aqueous electrolyte solution of the present embodiment preferably contains dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC), which are chain carbonate compounds, as the non-aqueous solvent. The volume ratio (DMC / EMC) of the ethylmethyl carbonate to the dimethyl carbonate is preferably 0.5 or more and 8.0 or less, more preferably 0.8 or more and 6.0 or less, and 1.0 or more. It is more preferably 4.0 or less. When the DMC / EMC is 0.5 or more, the viscosity of the electrolytic solution can be reduced and high lithium ion conductivity can be exhibited. When DMC / EMC is 8.0 or less, the melting point of the mixed solvent can be kept low, and high input / output characteristics can be exhibited even in a low temperature environment.
Further, the non-aqueous electrolyte solution of the present embodiment may contain other chain carbonate as the non-aqueous solvent. Examples of other chain carbonates include dialkyl carbonate compounds typified by diethyl carbonate, dipropyl carbonate, dibutyl carbonate and the like. Dialkyl carbonate compounds are typically unsubstituted.
The lower limit of the total content of the chain carbonate is preferably 30% by mass or more, more preferably 35% by mass or more, and the upper limit is preferably 95% by mass or less, based on the total amount of the non-aqueous electrolyte solution. , More preferably 90% by mass or less. When the total content of the chain carbonate is 30% by mass or more, the viscosity of the electrolytic solution can be reduced and high lithium ion conductivity can be exhibited. When the total content is 95% by mass or less, the electrolytic solution can further contain the additives described later.

[Additive]
The non-aqueous electrolyte solution of the present embodiment may further contain an additive. The additive is not particularly limited, but for example, a thiophene compound, a cyclic sulfate compound, a sulton compound, the cyclic sulfite compound, cyclic phosphazene, acyclic fluoroether, fluorocyclic carbonate, cyclic carbonate, cyclic carboxylic acid ester, and the like. And cyclic acid anhydride and the like can be used alone, and two or more of these may be mixed.

[Separator]
The positive electrode precursor and the negative electrode are laminated or wound via a separator, and an electrode laminate or an electrode wound body having the positive electrode precursor, the negative electrode and the separator is formed.
As the separator, a polyethylene microporous film used for a lithium ion secondary battery, a polyolefin microporous film such as a polypropylene microporous film, or a cellulose non-woven paper or polyester type used for an electric double layer capacitor. A non-woven fabric containing a resin or the like can be used. A film made of organic or inorganic fine particles may be laminated as an insulating layer on one side or both sides of these separators. Further, organic or inorganic fine particles may be contained inside the separator.

The thickness of the separator is preferably 5 μm or more and 35 μm or less. A thickness of 5 μm or more is preferable because self-discharge due to a micro short circuit inside the non-aqueous lithium storage element tends to be small. On the other hand, a thickness of 35 μm or less is preferable because the input / output characteristics of the non-aqueous lithium storage element tend to be high.
The thickness of the film made of organic or inorganic fine particles is preferably 1 μm or more and 10 μm or less. It is preferable to make the film made of organic or inorganic fine particles having a thickness of 1 μm or more because self-discharge due to micro short circuit inside the non-aqueous lithium storage element tends to be small. On the other hand, a thickness of 10 μm or less is preferable because the input / output characteristics of the non-aqueous lithium storage element tend to be improved.

[Non-aqueous lithium-type power storage element]
As will be described later, the non-aqueous lithium storage element of the present embodiment is configured such that an electrode laminate or an electrode winding body is housed in an exterior body together with a non-aqueous electrolyte solution.

[assembly]
The electrode laminate obtained in the cell assembly step is a laminate obtained by laminating a positive electrode precursor and a negative electrode cut into a single-wafer shape via a separator, and connecting a positive electrode terminal and a negative electrode terminal to the laminate. By using the laminated electrode, the distance between the positive electrode and the negative electrode can be made uniform when the electrode is housed in the exterior body, so that the internal resistance can be reduced and the power storage element can be increased in output.
Further, the electrode winding body is formed by winding a positive electrode precursor and a negative electrode via a separator, and connecting a positive electrode terminal and a negative electrode terminal to the winding body. The shape of the electrode winding body may be cylindrical or flat, but it is preferably flat from the viewpoint of improving the filling rate of the power storage element at the time of packing. By using a wound electrode, the time required for the cell assembly process can be shortened, so that the production efficiency is improved.
The method of connecting the positive electrode terminal and the negative electrode terminal is not particularly limited, but a method such as resistance welding or ultrasonic welding is used.

[Exterior body]
As the exterior body, a metal can, a laminated packaging material, or the like can be used.
The metal can is preferably made of aluminum or an aluminum alloy. It is preferable that the lid of the metal can is provided with a safety valve. By installing a safety valve, gas can be released when the internal pressure of the battery rises due to gas generation. By using a metal can, the filling rate of the electrode laminate in the exterior body can be increased, so that the energy density can be improved.
As the laminated packaging material, a film obtained by laminating a metal foil and a resin film is preferable, and a three-layer structure composed of an outer layer resin film / metal foil / interior resin film is exemplified. The outer layer resin film is for preventing the metal foil from being damaged by contact or the like, and a resin such as nylon or polyester can be preferably used. The metal foil is for preventing the permeation of moisture and gas, and a foil of copper, aluminum, stainless steel or the like can be preferably used. Further, the interior resin film is intended to protect the metal foil from the non-aqueous electrolyte solution stored inside and to melt-seal the exterior body at the time of heat sealing, and polyolefins, acid-modified polyolefins and the like can be preferably used. By using the laminated packaging material, the heat dissipation of the power storage element can be improved, and the high temperature durability can be improved.

[Storage in the exterior]
It is preferable that the dried electrode laminated body or electrode wound body is housed in an exterior body typified by a metal can or a laminated packaging material, and sealed with only one opening left. In the case of an electrode winding body, it is preferable to form it flat on a press machine before storing it in the exterior body. At this time, it may be heated at the time of pressurization. After forming the wound body flat, it is stored in the outer body. From the viewpoint of improving the adhesion between the exterior body and the electrode unwound body, it is preferable to pressurize and heat the electrode again using a press machine after storage.
The sealing method of the exterior body is not particularly limited, but when a laminated packaging material is used, a method such as heat sealing or impulse sealing is used.
The direction in which the positive electrode terminal and the negative electrode terminal are taken out from the exterior body is not particularly limited. There is a method of taking out from both ends of the exterior body, or a method of taking out both the positive electrode terminal and the negative electrode terminal from one side.

[Drying]
It is preferable that the electrode laminated body or the electrode wound body housed in the outer body is dried to remove the residual solvent. The drying method is not limited, but the laminated body or the wound body is dried by vacuum drying or the like. The residual solvent is preferably 1.5% by mass or less per mass of the positive electrode active material layer or the negative electrode active material layer. If the residual solvent is more than 1.5% by mass, the solvent remains in the system and the self-discharge characteristics or the cycle characteristics are deteriorated, which is not preferable.

[Liquid injection, impregnation, sealing process]
After the assembly process is completed, the non-aqueous electrolyte solution is injected into the electrode laminate or the electrode winding body housed in the exterior body. After the completion of the liquid injection step, it is desirable to further impregnate and sufficiently immerse the positive electrode, the negative electrode, and the separator with a non-aqueous electrolyte solution. When the non-aqueous electrolyte solution is not immersed in at least a part of the positive electrode, the negative electrode, and the separator, the doping proceeds non-uniformly in the lithium doping step described later, so that the resistance of the obtained non-aqueous lithium storage element increases. It rises or becomes less durable. The impregnation method is not particularly limited, but for example, the electrode laminate or the electrode winding body after injection is installed in a decompression chamber with the outer body open, and the inside of the chamber is filled with a vacuum pump. It is possible to use a method of reducing the pressure and returning the pressure to atmospheric pressure again. After the impregnation step is completed, when the laminated packaging material is used, the electrode laminated body or the electrode wound body with the outer body open is sealed by sealing while reducing the pressure. When using a metal can, use a sealing means such as welding or caulking.

[Lithium dope process]
In the lithium doping step, preferably, a voltage is applied between the positive electrode precursor and the negative electrode to decompose the lithium compound, thereby decomposing the lithium compound in the positive electrode precursor and releasing lithium ions to release the lithium ion, and the negative electrode. By reducing the lithium ion in, the liotium ion is pre-doped into the negative electrode active material layer.
In this lithium doping step, gas such as CO ₂ is generated due to oxidative decomposition of the lithium compound in the positive electrode precursor. Therefore, when applying a voltage, it is preferable to take measures to release the generated gas to the outside of the exterior body. As this means, for example, a method of applying a voltage with a part of the exterior body opened; a state in which an appropriate gas discharge means such as a gas vent valve or a gas permeation film is previously installed in the part of the exterior body. A method of applying a voltage with the above;

In the lithium doping step, another doping method using a metallic lithium foil can be mentioned. Specifically, for example, a doping method in which a metallic lithium foil is adhered to a negative electrode active material by crimping and then the liquid is injected, or a method in which the negative electrode and the lithium foil are electrically short-circuited and then injected. When the state estimation method of the present invention is used, it can be estimated with high accuracy, especially when applied to a non-aqueous lithium storage element using a method of decomposing and doping a lithium compound in a positive electrode precursor. Although the reason is not clear, the non-aqueous lithium storage element using the doping method using lithium foil is used for a long period of time because the fine metallic lithium remaining at the time of doping is doped into the negative electrode. Since the deterioration of the negative electrode due to lithium deactivation is difficult to proceed and the resistance increases relatively easily due to the deterioration of the positive electrode, it is considered that the state estimation method focusing on the deterioration of the negative electrode as in the method of the present invention is not appropriate.

[Aging process]
After the lithium doping step is completed, it is preferable to perform aging on the electrode laminate or the electrode wound body. In the aging step, the solvent in the non-aqueous electrolyte solution is decomposed at the electrode-electrolyte solution interface, and a lithium ion-permeable solid polymer film is formed on the electrode.
The aging method is not particularly limited, and for example, a method of reacting a solvent in a non-aqueous electrolyte solution in a high temperature environment can be used.

[Degassing process]
After the aging step is completed, it is preferable to further degas to surely remove the gas remaining in the non-aqueous electrolyte solution, the positive electrode, and the negative electrode. In a state where gas remains in at least a part of the non-aqueous electrolyte solution, the positive electrode, and the negative electrode, ion conduction is inhibited, so that the resistance of the obtained non-aqueous lithium storage element increases.
The method for degassing is not particularly limited, but for example, the electrode laminate or the electrode winding body is installed in the decompression chamber with the exterior body opened, and the inside of the chamber is depressurized by using a vacuum pump. A method or the like can be used.

Hereinafter, examples and comparative examples will be shown to further clarify the features of the present invention. However, the present invention is not limited to the following examples.

<Example 1>
[Preparation of positive electrode]
52.3 parts by mass of commercially available steam-activated activated carbon, 5.2 parts by mass of LiFePO ₄ having an average particle size of 3.5 μm as a lithium transition metal oxide, and 30.0 parts by mass of lithium carbonate having an average particle size of 0.5 μm. , Ketjen Black is 3.0 parts by mass, PVP (polyvinylpyrrolidone) is 1.5 parts by mass, PVDF (polyvinylfluoride fluoride) is 8.0 parts by mass, and the weight ratio of solid content is 24.5%. NMP (N-methyl-2-pyrrolidone) is mixed as described above, and the mixture is mixed with a thin film swirling high-speed mixer "Fillmix (registered trademark)" manufactured by PRIMIX for 3 minutes at a peripheral speed of 20 m / s. It was dispersed to obtain a positive electrode coating liquid. _The ratio of the mass A1 of the activated carbon to the mass _A2 of the lithium transition metal oxide was 0.1.
Using a double-sided die coater manufactured by Toray Engineering Co., Ltd., apply a positive electrode coating solution to one or both sides of an aluminum foil with a thickness of 15 μm, and set the temperature of the drying oven to 70 ° C, 90 ° C, 110 ° C, and 130 ° C in that order. And then dried with an IR heater to obtain a positive electrode precursor. The positive electrode precursor was pressed using a roll press machine. The film thickness of the positive electrode active material layer was 70 μm per one side. As a result of calculating the basis weight, the basis weight of the positive electrode active material layer was 45 g · m ^-2 per side.

[Preparation of negative electrode active material]
A stainless steel bat containing 150 g of artificial graphite having an average particle size of 6.2 μm and a BET specific surface area of 7.2 m ² / g in a stainless steel mesh cage and 15 g of coal-based pitch (softening point: 65 ° C.). Both were placed in an electric furnace (effective size in the furnace 300 mm × 300 mm × 300 mm). The temperature of the cage and the vat was raised to 1,250 ° C. in a nitrogen atmosphere in 8 hours, and the temperature was kept at the same temperature for 4 hours to cause a thermal reaction to obtain a negative electrode active material A. The obtained negative electrode active material A was cooled to 60 ° C. by natural cooling, and then taken out from the electric furnace.

[Manufacturing of negative electrode]
A negative electrode was manufactured using the negative electrode active material A obtained above.
85 parts by mass of negative electrode active material A, 10 parts by mass of acetylene black, 5 parts by mass of PVdF (polyvinylidene fluoride), and NMP (N-methylpyrrolidone) are mixed, and the mixture is a thin film swirl type high speed manufactured by PRIMIX. Using a mixer fill mix, a coating liquid was obtained by dispersing under the condition of a peripheral speed of 15 m / s. The above coating liquid was applied to both sides of an electrolytic copper foil having a thickness of 10 μm and having no through holes using a die coater manufactured by Toray Engineering Co., Ltd. at a coating speed of 1 m / s, and dried at a drying temperature of 85 ° C. Obtained a negative electrode. The negative electrode was pressed using a roll press machine under the conditions of a pressure of 4 kN / cm and a surface temperature of the pressed portion of 25 ° C. The basis weight per one side of the negative electrode active material layer of the negative electrode was 30 g / m ² , and the film thickness was 40 μm.

[Preparation of electrolytic solution]
As an organic solvent, a mixed solvent of ethylene carbonate (EC): dimethyl carbonate (DMC): methyl ethyl carbonate (EMC) = 34: 44: 22 (volume ratio) was used, and LiN (SO ₂ F) was used with respect to the total electrolytic solution. Dissolve each electrolyte salt so that the concentration ratio of ₂ and LiPF ₆ is 25:75 (molar ratio) and the sum of the concentrations of LiN (SO ₂ F) ₂ and LiPF ₆ is 1.2 mol / L. A non-aqueous electrolyte solution was obtained.

[Assembly of power storage element]
The obtained negative electrode and double-sided positive electrode precursor were cut into 10 cm × 10 cm (100 cm ² ). A single-sided positive electrode precursor is used for the uppermost surface and the lowermost surface, and 21 double-sided negative electrodes and 20 double-sided positive electrode precursors are used. A laminated body was prepared by sandwiching the microporous membrane separator A.

[Welding of terminals]
Then, the negative electrode terminal and the positive electrode terminal were connected to the negative electrode and the positive electrode precursor by ultrasonic welding to form an electrode laminate. The electrode laminate was vacuum dried under the conditions of 80 ° C., 50 Pa, and 60 hr. This electrode laminate is inserted into an exterior body made of an aluminum laminate packaging material under a dry environment with a dew point of −45 ° C. Heat sealed.

[Liquid injection, impregnation, sealing process of power storage element]
About 80 g of the non-aqueous electrolyte solution 1 is injected into the electrode laminate housed in the aluminum laminate packaging material under atmospheric pressure in a dry air environment with a temperature of 25 ° C. and a dew point of -40 ° C. or less. An aqueous lithium-type power storage element was formed. Subsequently, the non-aqueous lithium-type power storage element was placed in the decompression chamber, the pressure was reduced from normal pressure to −87 kPa, the pressure was returned to atmospheric pressure, and the mixture was allowed to stand for 5 minutes. Then, the energy storage element was depressurized from normal pressure to −87 kPa, and then the process of returning to atmospheric pressure was repeated four times, and then the element was allowed to stand for 15 minutes. Further, the power storage element was depressurized from normal pressure to −91 kPa, and then returned to atmospheric pressure. Similarly, the steps of depressurizing the element and returning it to atmospheric pressure were repeated 7 times in total. (Reduced to -95, -96, -97, -81, -97, -97, -97 kPa, respectively). By the above steps, the electrode laminate was impregnated with the non-aqueous electrolyte solution.
Then, the non-aqueous lithium-type power storage element was placed in a vacuum sealing machine, and the aluminum laminate packaging material was sealed by sealing at 180 ° C. for 10 seconds at a pressure of 0.1 MPa with the pressure reduced to −95 kPa.

[Lithium dope process]
For the obtained non-aqueous lithium type power storage element, a charging / discharging device (TOSCAT-3100U) manufactured by Toyo System Co., Ltd. is used, and the voltage is fixed until the voltage reaches 4.4 V at a current value of 0.7 A in a 25 ° C environment. After the current charge, the initial charge was continuously performed by the method of continuing the 4.4 V constant voltage charge for 10 hours, and the negative electrode was lithium-doped.

[Aging process]
After lithium-doped non-aqueous lithium-type power storage element, constant current discharge is performed at 0.7 A at 0.7 A until the voltage reaches 3.0 V, and then constant current constant voltage charge is performed up to 4.0 V. The voltage was adjusted to 4.0 V by time. Subsequently, the non-aqueous lithium-type power storage element was stored in a constant temperature bath at 60 ° C. for 20 hours.

[Degassing process]
After the above additional charge / discharge step, a part of the aluminum laminated packaging material of the non-aqueous lithium-type power storage element was opened in a dry air environment having a temperature of 25 ° C. and a dew point of −40 ° C. Subsequently, the non-aqueous lithium-type power storage element is placed in the decompression chamber, and the pressure is reduced from atmospheric pressure to -80 kPa using a diaphragm pump (N816.3KT.45.18) manufactured by KNF for 3 minutes. The process of returning to atmospheric pressure over 3 minutes was repeated a total of 3 times. After that, a non-aqueous lithium-type power storage element is placed in a vacuum sealing machine, the pressure is reduced to -90 kPa, and then the aluminum laminate packaging material is sealed by sealing at 200 ° C. for 10 seconds at a pressure of 0.1 MPa to seal the non-aqueous lithium-based packaging material. The lithium-type power storage element A was completed.

[Measurement of discharge curve, measurement of voltage at which d ² V / d Q ² is maximized]
First, the non-aqueous lithium-type power storage element A before deterioration is charged with a constant current in a constant temperature bath set at 25 ° C. until the current value of 1C reaches 4.0V, and then 4.0V. Constant voltage charging to which a constant voltage is applied is performed for a total of 30 minutes. After that, when the power storage element A was subjected to constant current discharge with a current value of 1 C up to 2.0 V, the capacity was 1000 mAh. A discharge curve was obtained by plotting the cell voltage V (V) with respect to the cell capacity at this time. From this discharge curve, the first derivative dV / dQ and the second derivative d ² V / dQ ² were obtained, and the voltage V _{1C and 25 ° C.} at which the second derivative became maximum were obtained.
According to the same method as above, but the temperature is changed from 25 ° C to 60 ° C in 5 ° C increments, and the constant current discharge rate is also 1C, 5C, 10C, 25C, 50C, 75C, 100C, 125C, 150C, 175C, 200C. By changing, a total of 8 × 11 = 88 discharge curves are obtained, and the first derivative dV / dQ and the ^second derivative d2 V / dQ ² are obtained, respectively, and d ² V / dQ ² becomes the maximum. The voltage V at the time was calculated.

[Measurement of negative electrode potential]
The completed non-aqueous lithium type power storage element A is charged with a constant current until it reaches 4.0 V at a current value of 1 C, and then a constant current is charged until it reaches the _{initial V, 1 C, and 25 ° C.} at a current value of 1 C. After the discharge, a constant voltage discharge of V1C and a constant voltage of _{25 ° C.} was performed for a total of 30 minutes. This power storage element A is introduced into an argon box having a dew point of -60 ° C., the exterior body is opened, and the lithium reference electrode wrapped in the separator containing the above-mentioned non-aqueous electrolyte solution is introduced into the power storage element. It was brought into contact with the inner laminate. In this state, the negative electrode potential V (vsLi ⁺ / Li) was measured by measuring the potential difference between the negative electrode terminal and the lithium reference electrode with a tester.

[Measurement of discharge resistance and charge resistance]
The power storage element obtained in the above step reaches 4.0 V at a current value of 20 C using a charging / discharging device (5V, 360A) manufactured by Fujitsu Telecom Networks Co., Ltd. in a constant temperature bath set at 25 ° C. A constant current charge is performed until the current value is increased, and then a constant current charge of 4.0 V is applied for a total of 30 minutes. Then, a constant current discharge is performed up to 2.0 V at a current value of 50 C, and the discharge curve ( Time-voltage) was obtained. In this discharge curve, the voltage at the discharge time = 0 second obtained by extrapolating from the voltage values at the time points of the discharge time of 1 second and 2 seconds is defined as Eo, the voltage drop ΔE = 4.0-Eo, and. The discharge resistance was calculated by R = ΔE / (50C (current value A)).
By changing the voltage from 4.0 V to 2.2 V in 0.2 V increments, discharge resistance data with the voltage as a parameter was obtained.
The power storage element obtained in the above step reaches 2.0V at a current value of 20C using a charging / discharging device (5V, 360A) manufactured by Fujitsu Telecom Networks Co., Ltd. in a constant temperature bath set at 25 ° C. A constant current discharge is performed for a total of 30 minutes by applying a constant current of 2.0 V, followed by a constant current discharge of a current value of 50 C to 4.0 V, and the charging curve ( Time-voltage) was obtained. In this charging curve, the voltage at the charging time = 0 seconds obtained by extrapolating from the voltage values at the charging times of 1 second and 2 seconds is defined as Eo, and the voltage drop ΔE = Eo-2.0 and The charge resistance was calculated by R = ΔE / (50C (current value A)).
By changing the voltage from 2.0V to 3.8V in 0.2V increments, charging resistance data with the voltage as a parameter was obtained.

[Database group of voltage that maximizes d ² V / d Q ² ]
A plurality of non-aqueous lithium-type storage elements A (cells) are constantly charged with a current value of 100 C until the voltage reaches 4.0 V, and then constant voltage charging is performed for 10 minutes by applying a constant voltage of 4.0 V. .. After that, the cell is stored in an environment of 60 ° C. for one month, the discharge curve is measured, and the voltage at which d ² V / dQ ² is maximized is obtained under various temperature and / or discharge rate conditions. rice field. Further, the voltage of one of the power storage elements is 1C after 1 month of storage at 60 ° C., and the voltage V _{1 month, 1C, 25} when ^d2V / ^dQ2 of the discharge curve at 25 ° C. is maximized. The temperature was adjusted to _{° C.} , the element was disassembled, and the negative electrode potential was measured. For other power storage elements, the voltage was adjusted to 4.0 V and the storage test was continued. By repeating this every other month for half a year, a database group was obtained in which the voltage at which d ² V / dQ ² was maximized was arranged as the parameters of the negative electrode potential, the current, and the voltage.

[Database group of discharge resistance and charge resistance]
When obtaining the database group of the voltage that maximizes d ² V / d Q ² described above, the discharge resistance of the power storage element is obtained by obtaining data under various discharge resistance and charge resistance conditions every month of storage. And the charge resistance were arranged with the voltage of the power storage element and the negative potential as parameters, and a database group was obtained.

[Manufacturing a storage module using a non-aqueous lithium-type power storage element]
Twelve of the completed non-aqueous lithium-type power storage elements A connected in series,
Current recording / measuring unit that measures and records the current flowing through the 12-shift power storage element,
Voltage recording / measuring unit, which measures and records the voltage of 12 direct power storage elements,
A voltage sensor for each cell, and a temperature sensor for measuring the positive tab temperature of one cell every four cells,
A power storage module equipped with the above was manufactured as shown in FIG.

[Durability evaluation of power storage module, temperature, current, voltage measurement]
The durability evaluation of the power storage module was carried out in a constant temperature bath having a tank temperature of 30 ° C. A 3.6 kW constant power cycle was performed in which the power storage module was charged to an upper limit voltage of 48 V and discharged to a lower limit voltage of 24 V. A cycle pattern (FIG. 6) was carried out with a 15-minute rest at 46 V every 5 cycles. During this period, the current flowing through the module, the voltage of each cell, and the cell temperature of the four cells were measured, and the data was collected in 1-second increments. Next, charging and discharging were stopped for 21 hours. Even when charging / discharging was stopped for 21 hours, the temperature inside the constant temperature bath was maintained at 30 ° C. By repeating this 3-hour cycle and 21-hour charge / discharge stop, an environment in which a system equipped with a power storage module (for example, a power regeneration system or a power standardization system for transportation equipment) is operated for 3 hours and stopped for 21 hours. Was simulated. This test was continued for one year. The temperature was 40 ° C. at the start of the test, but increased to 50 ° C. one year later.

[Estimation of negative electrode potential, discharge resistance, charge resistance]
One cycle was taken out from the data of the cycle one year later, and the discharge curve was obtained by using the current and voltage data at the time of discharge at this time. From this discharge curve, the voltage at which d ² V / d Q ² was maximized was analyzed and obtained. The time average current at this time was 100 A, and the time average temperature was 50 ° C. When the voltage that maximizes d ² V / d Q ² and the data that is closest to the current and temperature data at that time are searched for in the voltage database group that maximizes d ² V / d Q ² , the negative potential is 0. It was estimated to be 259V. Furthermore, the discharge resistance of 4.0 V and the charge resistance of 2.0 V at the negative electrode potential estimated value of 0.259 V were estimated by referring to the data corresponding to the nearest negative electrode potential from the discharge resistance / charge resistance database. The discharge resistance was estimated to be 1.72 mΩ and the charge resistance was estimated to be 2.49 mΩ.

[Actual measurement of negative electrode potential, discharge resistance, charge resistance]
The power storage module that had been evaluated for durability for one year was disassembled, and the power storage element was taken out. When one of them, a discharge resistance of 4.0 V and a charge resistance of 2.0 V, was actually measured, the discharge resistance was 1.68 mΩ and the charge resistance was 2.45 mΩ.
Further, the power storage element is constantly charged in a constant temperature bath set at 25 ° C. until it reaches 4.0 V at a current value of 1 C, and then a constant voltage charge of 4.0 V is applied in total. After 30 minutes, the quadratic derivative d ² V / dQ ² is obtained from the discharge curve when constant current discharge is performed with a current value of 1 C up to 2.0 V, and the voltage V when the quadratic derivative becomes maximum. I asked for _W. The voltage of the power storage element A is constantly charged until it reaches 4.0 V at a current value of 1 C, then discharged at a constant current until it reaches this voltage V at a current value of 1 C, and then the constant voltage of V _W. A constant voltage discharge was carried out for a total of 30 minutes. This power storage element A is introduced into an argon box having a dew point of -60 ° C., the exterior body is opened, and the lithium reference electrode wrapped in the separator containing the above-mentioned non-aqueous electrolyte solution is introduced into the power storage element. It was brought into contact with the inner laminate. In this state, the potential difference between the negative electrode terminal and the lithium reference electrode was measured with a tester to measure the negative electrode potential (vsLi ⁺ / Li), which was 0.253V.

[Error of estimated value with respect to actual value]
The estimated error was obtained by dividing the estimated values of the negative electrode potential, the discharge resistance, and the charge resistance by the measured values, multiplying them by 100, and subtracting 100.
The estimation error of the negative electrode potential was (0.259 ÷ 0.253) × 100-100 = + 2.4%.
The estimation error of the discharge resistance was (1.72 ÷ 1.68) × 100-100 = 2.4%.
The estimation error of the charging resistance was (2.49 ÷ 2.45) × 100-100 = + 1.6%.

<Example 2>
The evaluation was carried out in the same manner as in Example 1 except that the steam-activated activated carbon was 38.3 parts by mass and LiFePO ₄ was 19.2 parts by mass in the preparation of the positive electrode of Example 1. The results are shown in Table 3.
<Example 3>
The evaluation was carried out in the same manner as in Example 1 except that the steam-activated activated carbon was 28.8 parts by mass and LiFePO ₄ was 28.8 parts by mass in the preparation of the positive electrode of Example 1. The results are shown in Table 3.
<Example 4>
Same as Example 1 except that the steam-activated activated carbon was 28.0 parts by mass and LiFePO ₄ was 34.5 parts by mass in the preparation of the positive electrode of Example 1, and lithium oxalate was used instead of lithium carbonate. Evaluated to. The results are shown in Table 3.
<Example 5>
The evaluation was carried out in the same manner as in Example 1 except that the steam-activated activated carbon was 16.4 parts by mass and LiFePO ₄ was 41.1 parts by mass in the preparation of the positive electrode of Example 1. The results are shown in Table 3.

< Reference example 6>
Except for the following steps, the power storage element and the module were assembled and evaluated in the same manner as in Example 1. The results are shown in Table 3.
[Preparation of positive electrode]
Commercially available steam-activated activated carbon is 38.3 parts by mass, LiFePO ₄ having an average particle diameter of 3.5 μm as a lithium transition metal oxide is 19.2 parts by mass, Ketjen Black is 3.0 parts by mass, and PVP (polyvinylidene). The amount was adjusted to 1.5 parts by mass and PVDF (polyvinylidene fluoride) was 8.0 parts by mass, and the amount was adjusted to 31.5 g · m ^-2 per one side of the positive electrode active material layer.
[Manufacturing of negative electrode]
A negative electrode was produced in the same manner as in Example 1 except that a copper foil having a thickness of 15 μm and a through hole of φ100 μm was used.
[Attachment of lithium foil to the negative electrode]
A Li metal leaf having a thickness of 15 μm cut out to a size of 9 cm × 9 cm was pressure-bonded to one side of the negative electrode prepared in the same manner as in Example 1 by a roll press and attached to the negative electrode.
[Lithium dope process]
For the obtained non-aqueous lithium type power storage element, a charging / discharging device (TOSCAT-3100U) manufactured by Toyo System Co., Ltd. is used, and the voltage is fixed until the voltage reaches 4.0 V at a current value of 0.7 A in a 25 ° C environment. After the current charge, the initial charge was continuously performed by a method of continuing 4.0 V constant voltage charge for 10 hours, and the negative electrode was lithium-doped.

< Reference example 7>
In the preparation of the positive electrode of Reference Example 6, the evaluation was carried out in the same manner as in Reference Example 6 except that the steam-activated activated carbon was 28.8 parts by mass and LiFePO ₄ was 28.8 parts by mass. The results are shown in Table 3.

<Comparative Example 1>
Except for the following steps, the power storage element and the module were assembled and evaluated in the same manner as in Example 1. The results are shown in Table 3.
[Measurement of discharge resistance and charge resistance]
The discharge resistance at 4.0 V and the charge resistance at 2.0 V of the power storage element before deterioration were measured.
[Measurement of negative electrode potential]
The negative electrode potential at 2.0 V of the power storage element before deterioration was measured in the same manner as in the above method.
[Database group of resistance deterioration coefficient]
The non-aqueous lithium power storage element A as a cell is constantly charged with a current value of 100 C until the voltage reaches 4.0 V, and then constant voltage charging is performed for 10 minutes by applying a constant voltage of 4.0 V. Then, the cell was stored in an environment of 40 ° C., and one month later, it was taken out from the environment of 40 ° C., and the discharge resistance at 4.0 V and the charge resistance at 2.0 V were measured by the same method as described above. Deterioration rate of resistance = resistance value after 1 month ÷ resistance value before deterioration. Then, after charging the cell voltage to 4.0 V in the above-mentioned charging step, the cell is stored again in an environment of 40 ° C. This one-month storage and resistance measurement was repeated for half a year, that is, six times. The obtained resistance deterioration rates are plotted against the square root of time, and the slopes of each are calculated by the least squares method to calculate the resistance deterioration coefficients α _{4.0 V and 40 °} C at a voltage of 4.0 V and a temperature of 40 ° C. did. This resistance deterioration coefficient was determined by using a plurality of non-aqueous lithium-type storage elements A (4.0V, 3.8V, 3.6V, 3.4V, 3.2V, 3.0V, 2.8V, 2. It was determined under 66 conditions of 6V, 2.4V, 2.2V, 2.0V) × (40, 42, 44, 46, 48, 50 ° C.). As a result, a database group of the discharge resistance deterioration coefficient and the charge resistance deterioration coefficient of the power storage element was obtained as the parameters of voltage and temperature.
[Database group of negative electrode potential rise]
In the high temperature storage durability test, the negative electrode potential of 2.0 V was measured, and a database group showing the increase transition by the parameters of time, temperature and voltage was obtained.
[Manufacturing a storage module using a non-aqueous lithium-type power storage element]
It was carried out in the same manner as in Example 1.

[Durability evaluation of power storage module, current temperature voltage measurement]
It was carried out in the same manner as in Example 1.
[Estimation of negative electrode potential]
From the data of the cycle of one year, the time transition of the voltage and temperature in which the power storage element was placed was obtained. Using the database group of the negative electrode potential rise, the negative electrode potential rise after one year of the cycle was estimated by integrating the negative electrode potential rise at each time to estimate the negative electrode potential rise value for one year. It was .134V.
[Estimation of discharge resistance and charge resistance]
From the data of the cycle of one year, the time transition of the voltage and temperature in which the power storage element was placed was obtained. Using the database group of deterioration coefficients for each of the discharge resistance and charge resistance, the resistance increase value for one year is estimated by integrating the resistance increase amount at each time, and the resistance value after one year of the cycle can be obtained. Estimated, the discharge resistance was 1.16 mΩ and the charge resistance was 1.41 mΩ.
[Actual measurement of negative electrode potential, discharge resistance, charge resistance]
The power storage module that had been evaluated for durability for one year was disassembled, and the power storage element was taken out. When one of them, a discharge resistance of 4.0 V and a charge resistance of 2.0 V, was actually measured, the discharge resistance was 1.68 mΩ and the charge resistance was 2.45 mΩ.
Further, after the voltage of one of the taken-out power storage elements is constantly charged until it reaches 4.0 V at a current value of 1 C, and then discharged at a constant current until it reaches 2.0 V at a current value of 1 C. , Constant voltage discharge to which a constant voltage of 2.0 V was applied was carried out for a total of 30 minutes. This power storage element is introduced into an argon box having a dew point of -60 ° C., the exterior body is opened, and the lithium reference electrode wrapped in the separator containing the above-mentioned non-aqueous electrolyte solution is introduced into the power storage element and inside the power storage element. Was brought into contact with the laminate of. In this state, the potential difference between the negative electrode terminal and the lithium reference electrode was measured with a tester to measure the negative electrode potential (vsLi ⁺ / Li), which was 0.253V.

<Comparative Example 2>
Table 3 shows the results of evaluation in the same manner as in Comparative Example 1 except that the steam-activated activated carbon was 28.8 parts by mass and LiFePO ₄ was 28.8 parts by mass in the preparation of the positive electrode of Comparative Example 1.

略語の説明：
Ａ１：活性炭量
Ａ２：酸化物量
ＬＦＰ：ＬｉＦｅＰＯ_４

Explanation of abbreviations:
A1: Amount of activated carbon A2: Amount of oxide LFP: LiFePO ₄

According to the above examples, by using the method, apparatus and system of the present invention, the state of the non-aqueous lithium power storage element in which activated carbon and a lithium transition metal oxide having an olivine structure are mixed in the positive electrode can be obtained with high accuracy. It was verified that it can be easily estimated.

The method, apparatus and system of the present invention can be suitably used for a non-aqueous lithium storage element in, for example, an application for assisting an instantaneous power peak in a hybrid drive system of an automobile.

1 Power storage element 2 Cell stack 3 End plate 4 Fastener 5 Tab terminal 6 Bus bar 7 Voltage measurement terminal 8 Temperature measurement terminal 9 Power storage module

Claims (18)

A method for estimating the state of a non-aqueous lithium-type power storage element including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution containing lithium ions.
The negative electrode has a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material provided on one side or both sides of the negative electrode current collector, and the negative electrode active material occludes lithium ions. And contains materials that can be released
The positive electrode has a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material provided on one side or both sides of the positive electrode current collector, and the positive electrode active material is activated carbon and lithium ion. Contains a lithium transition metal oxide with an olivine structure capable of storing and releasing.
The maximum is the quadratic derivative d ² V / dQ ² calculated from the discharge curve obtained by taking the capacitance Q when the non-aqueous lithium power storage element is discharged at a constant current on the horizontal axis and the voltage V on the vertical axis. As parameters, the voltage at the time of measuring the discharge curve, the current or power at the time of measuring the discharge curve, and the negative voltage of the non-aqueous lithium type power storage element are used as parameters, and a database group collected in advance is created and the non-voltage is in operation. The current, voltage, and temperature of the water-based lithium-type power storage element are measured, d ² V / dQ ² is calculated, and the voltage at which d ² V / dQ ² is maximized is used as the non-water-based lithium power storage element based on the database group. A method for estimating the state of a non-aqueous lithium-type power storage element, which comprises estimating the negative voltage potential of the element. A method for estimating the state of a non-aqueous lithium-type power storage element including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution containing lithium ions.
The negative electrode has a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material provided on one side or both sides of the negative electrode current collector, and the negative electrode active material occludes lithium ions. And contains materials that can be released
The positive electrode has a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material provided on one side or both sides of the positive electrode current collector, and the positive electrode active material is activated carbon and lithium ion. Contains a lithium transition metal oxide with an olivine structure capable of storing and releasing.
Further, the lithium compound other than the positive electrode active material is selected from lithium carbonate, lithium oxide, lithium hydroxide, lithium fluoride, lithium chloride, lithium oxalate, lithium iodide, lithium nitride, lithium oxalate, and lithium acetate. The positive electrode active material layer contains one or more of them.
A database group was created in which the discharge resistance and charge resistance of the non-aqueous lithium energy storage element were collected in advance with the voltage and negative potential of the non-aqueous lithium energy storage element as parameters, and the current of the non-aqueous lithium energy storage element in operation. And the voltage and temperature are measured, and the quadratic derivative d ² V / dQ ² is calculated from the discharge curve obtained by taking the capacity Q on the horizontal axis and the voltage V on the vertical axis, and d ² V / dQ ² is The non-aqueous lithium type is characterized in that the discharge resistance or the charge resistance of the non-aqueous lithium type energy storage element is estimated from the negative potential of the non-aqueous lithium type energy storage element estimated from the maximum voltage based on the database group. A method for estimating the state of a power storage element. The lithium transition metal oxide has the following formula:
Li _x2 FePO ₄ {In the formula, x2 satisfies 0.8 ≦ x2 ≦ 1.2. },
Li _x2 CoPO ₄ {In the formula, x2 satisfies 0.8 ≦ x2 ≦ 1.2. }, And Li _x2 MnPO ₄ {In the formula, x2 satisfies 0.8 ≦ x2 ≦ 1.2. },
The method for estimating the state of a non-aqueous lithium-type power storage element according to claim 1 or 2, which comprises at least one lithium transition metal oxide selected from the group consisting of. The item according to any one of claims 1 to 3, wherein the content of the lithium transition metal oxide is 1.0% by mass to 50.0% by mass based on the total mass of the positive electrode active material layer. A method for estimating the state of a non-aqueous lithium-type power storage element. When the mass ratio of the activated carbon in the positive electrode active material layer is A ₁ and the mass ratio of the lithium transition metal oxide is A ₂ , A ₂ / A ₁ is 0.1 or more and 2.5 or less. The method for estimating the state of the non-aqueous lithium-type power storage element according to any one of claims 1 to 4. Claim 1 in which the positive electrode contains at least one selected from the group consisting of lithium carbonate, lithium oxide, and lithium hydroxide in an amount of 0.2% by mass or more and 50% by mass or less based on the total amount of the positive electrode active material. The method for estimating the state of a non-aqueous lithium-type power storage element according to any one of 5 to 5. A state estimation device for a non-aqueous lithium storage element including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution containing lithium ions.
The negative electrode of the non-aqueous lithium-type power storage element has a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material provided on one side or both sides of the negative electrode current collector, and the negative electrode active material is provided. The material includes a material capable of storing and releasing lithium ions.
The positive electrode of the non-aqueous lithium-type power storage element has a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material provided on one side or both sides of the positive electrode current collector, and the positive electrode active material is provided. The material comprises activated carbon and a lithium transition metal oxide having an olivine structure capable of storing and releasing lithium ions, and the state estimator is:
The maximum is the quadratic derivative d ² V / dQ ² calculated from the discharge curve obtained by taking the capacitance Q when the non-aqueous lithium power storage element is discharged at a constant current on the horizontal axis and the voltage V on the vertical axis. The voltage is a storage unit having a database group collected in advance with the temperature at the time of measuring the discharge curve, the current or power at the time of measuring the discharge curve, and the negative voltage of the non-aqueous lithium type power storage element as parameters; and the non-aqueous system in operation. The d ² V / dQ ² is calculated from the measured values of the current, voltage and temperature of the lithium type power storage element, and the non-aqueous lithium type power storage is based on the database group from the voltage at which d ² V / dQ ² is maximized. Arithmetic processing unit that estimates the negative voltage potential of the element;
A state estimation device for a non-aqueous lithium-type power storage element. A state estimation device for a non-aqueous lithium storage element including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution containing lithium ions.
The negative electrode of the non-aqueous lithium-type power storage element has a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material provided on one side or both sides of the negative electrode current collector, and the negative electrode active material is provided. The material includes a material capable of storing and releasing lithium ions.
The positive electrode of the non-aqueous lithium power storage element has a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material provided on one side or both sides of the positive electrode current collector, and the positive electrode active material is provided. The material comprises activated carbon and a lithium transition metal oxide having an olivine structure capable of storing and releasing lithium ions .
Further, the lithium compound other than the positive electrode active material is selected from lithium carbonate, lithium oxide, lithium hydroxide, lithium fluoride, lithium chloride, lithium oxalate, lithium iodide, lithium nitride, lithium oxalate, and lithium acetate. The positive electrode active material layer contains one or more of them, and the state estimation device is:
A storage unit having a database group in which the discharge resistance and charge resistance of the non-aqueous lithium storage element are collected in advance with the voltage and negative potential of the non-aqueous lithium storage element as parameters; and the non-aqueous lithium storage element in operation. From the measured values of current, voltage and temperature, the quadratic derivative d ² V / dQ ² of the discharge curve obtained by taking the capacity Q on the horizontal axis and the voltage V on the vertical axis is calculated, and d ² V / dQ An arithmetic processing unit that estimates discharge resistance or charge resistance from the negative voltage of the power storage element estimated from the voltage at which ² is the maximum, based on the database group;
A state estimation device for a non-aqueous lithium-type power storage element. The lithium transition metal oxide has the following formula:
Li _x2 FePO ₄ {In the formula, x2 satisfies 0.8 ≦ x2 ≦ 1.2. },
Li _x2 CoPO ₄ {In the formula, x2 satisfies 0.8 ≦ x2 ≦ 1.2. }, And Li _x2 MnPO ₄ {In the formula, x2 satisfies 0.8 ≦ x2 ≦ 1.2. },
The state estimation device for a non-aqueous lithium storage element according to claim 7 or 8, which comprises at least one lithium transition metal oxide selected from the group consisting of. The item according to any one of claims 7 to 9, wherein the content of the lithium transition metal oxide is 1.0% by mass to 50.0% by mass based on the total mass of the positive electrode active material layer. A state estimation device for non-aqueous lithium-type power storage elements. When the mass ratio of the activated carbon in the positive electrode active material layer is A ₁ and the mass ratio of the lithium transition metal oxide is A ₂ , A ₂ / A ₁ is 0.1 or more and 2.5 or less. The state estimation device for the non-aqueous lithium-type power storage element according to any one of claims 7 to 10. 7. Claim 7 that the positive electrode contains at least one selected from the group consisting of lithium carbonate, lithium oxide, and lithium hydroxide in an amount of 0.2% by mass or more and 50% by mass or less with respect to the total amount of the positive electrode active material. The state estimation device for a non-aqueous lithium-type power storage element according to any one of 11 to 11. (A) A non-aqueous lithium power storage element including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolytic solution containing lithium ions, wherein the negative electrode is a negative electrode current collector and one or both sides of the negative electrode current collector. It has a negative electrode active material layer containing a negative electrode active material provided above, the negative electrode active material contains a material capable of storing and releasing lithium ions, and the positive electrode is a positive electrode current collector and the positive electrode collection. It has a positive electrode active material layer containing a positive electrode active material provided on one side or both sides of an electric body, and the positive electrode active material is lithium having an activated carbon and an olivine structure capable of storing and releasing lithium ions. A non-aqueous lithium-type power storage element containing a transition metal oxide; and (b) the state estimation device according to any one of claims 7 to 12;
System including. The above systems are a power storage module system, a power regeneration assist system, a power load leveling system, a non-disruptive power supply system, a contactless power supply system, an energy harvest system, a power storage system, an electric power steering system, an emergency power supply system, and an in-wheel motor system. The system according to claim 13, which is at least one selected from the group consisting of an idling stop system, a transportation equipment system, a quick charging system and a smart grid system. In addition to the non-aqueous lithium storage element and the state estimation device, the system
(C) A lead battery, a nickel hydrogen battery, a lithium ion secondary battery or a fuel cell connected in series or in parallel with the non-aqueous lithium power storage element;
13. The system of claim 13. The system is at least one selected from the group consisting of a power storage system, an electric power steering system, an emergency power supply system, an in-wheel motor system, an idling stop system, a transportation equipment system, a quick charging system and a smart grid system. The system according to claim 15. The system according to claim 16, wherein the system is a photovoltaic power storage system. 16. The system of claim 16, wherein the system is the transport equipment system and is an electric vehicle, a plug-in hybrid vehicle, a hybrid vehicle or an electric motorcycle.

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