Nonaqueous electrolytic solution and nonaqueous secondary battery

Abstract

The present invention provides a nonaqueous alkali metal ion battery comprising: a positive electrode which has a positive electrode current collector and a positive electrode active material layer formed on one or both surfaces thereof; a negative electrode which has a negative electrode current collector and a negative electrode active material layer formed on one or both surfaces thereof; and an alkali metal ion-containing nonaqueous electrolytic solution. The nonaqueous electrolytic solution contains a nitryl compound represented by R-CN (In the formula, R represents a halogenated alkylene group or an alkylene group having 1-4 carbon atoms) as a nonaqueous solvent in an amount of 5-95 vol%. A negative electrode active material in the negative electrode active material layer has an SEI on the surface thereof. In profile analysis of the SEI on the surface of the negative electrode in the thickness direction by XPS, when X1 (atomic% / min.) represents the detection ratio of C1s (carbon elements) in a region of sputtering time of 5-20 min., and X2 (atomic% / min.) represents the detection ratio of C1s (carbon element) in a region of sputtering time of 30-50 min., the conditions X1>0, X2>0, and 0.25<(X1-X2)<2.75 are satisfied.

Description

Non-aqueous electrolyte and non-aqueous secondary battery

[0001] The present invention relates to a non-aqueous electrolyte solution and a non-aqueous secondary battery, and more particularly to a non-aqueous alkali metal ion battery containing a non-aqueous electrolyte solution.

[0002] In recent years, from the perspectives of preserving the global environment, saving resources, and making effective use of energy, attention has been drawn to wind power generation power smoothing systems or late-night power storage systems, distributed home energy storage systems based on solar power generation technology, and energy storage systems for electric vehicles.

[0003] Lithium-ion secondary batteries are being developed as a candidate for use in these energy storage systems, and research is progressing daily to increase their energy density and improve their long-term durability in order to achieve the required performance.

[0004] Patent Document 1 discloses a lithium ion secondary battery that suppresses deterioration during charge / discharge cycles and has excellent output performance by forming a coating with excellent dissolution resistance on the surface of an electrode active material. Patent Document 2 discloses a lithium ion secondary battery that achieves both improved input / output characteristics and improved life characteristics by controlling the solid electrolyte interface (hereinafter referred to as SEI) formed on the negative electrode active material on the surface of the negative electrode active material layer to be thinner than the SEI formed on the negative electrode active material on the current collector side. Patent Document 3 discloses an electrolyte composition that improves the durability of lithium ion secondary batteries that operate at high cathode potentials.

[0005] International Publication No. 2020 / 054866 Japanese Patent Application Laid-Open No. 2015-138707 Japanese Patent Application Laid-Open No. 2019-528552

[0006] By incorporating a nitrile compound represented by the formula: R-CN (wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms) as a non-aqueous solvent in a non-aqueous electrolyte, the ionic conductivity of the non-aqueous electrolyte can be significantly increased, and as a result, the output characteristics of a non-aqueous alkali metal ion battery can be significantly improved. However, nitrile compounds represented by the formula: R-CN are susceptible to reduction reactions, and the SEI formed on the surface of the negative electrode active material of a non-aqueous alkali metal ion battery typically cannot suppress the reductive decomposition reaction of the nitrile compound that occurs on the negative electrode surface. Therefore, in order to use a nitrile compound as a solvent for a non-aqueous electrolyte, an SEI with excellent solubility resistance and physical strength, as shown in Patent Document 1, is required. However, such a strong SEI hinders ion intercalation / deintercalation reactions at the active material interface, leaving room for improvement in output characteristics.

[0007] Furthermore, in order to increase the capacity of a battery, a positive electrode and a negative electrode are stacked or wound, but when the outermost layer is a negative electrode and a negative electrode active material layer that does not face the positive electrode (a so-called non-facing negative electrode) is present, none of the above-mentioned documents mentions suppressing gas generation due to reductive decomposition of a non-aqueous electrolyte solution on the non-facing negative electrode, or suppressing gas generation due to decomposition of the negative electrode SEI itself formed on the negative electrode active material of the non-facing negative electrode.

[0008] Furthermore, nitrile compounds have high Lewis basicity, which promotes metal elution in the positive electrode active material, posing a challenge to improving charge-discharge cycle durability. Furthermore, a strong SEI is required to suppress metal elution, but this leads to a decrease in ionic conductivity in the positive electrode SEI. None of the above documents discusses the suppression of metal elution when using a nitrile compound as a non-aqueous solvent, the formation of a positive electrode SEI that simultaneously suppresses decomposition of the nitrile compound at the positive electrode active material interface and promotes lithium ion intercalation / deintercalation reactions, or the improvement of ionic conductivity in the positive electrode SEI. As a result, there are challenges in increasing the power output and improving the charge-discharge cycle durability of the resulting non-aqueous alkali metal ion battery.

[0009] The present invention has been made in view of the above-mentioned current situation. A first object of the present invention is to provide a nonaqueous alkali metal ion battery having high power output and excellent charge-discharge cycle characteristics by suppressing the decomposition reaction of a nitrile compound on the surface of a negative electrode active material, reducing the energy barrier of the solvation / desolvation process of alkali metal ions at the interface between a nonaqueous electrolyte solution and a negative electrode SEI, and further promoting the intercalation / deintercalation reaction of alkali metal ions at the interface between the negative electrode SEI and the negative electrode active material. A second object of the present invention is to provide a nonaqueous alkali metal ion battery having excellent charge-discharge cycle durability by suppressing the decomposition of a nonaqueous electrolyte solution at a non-opposing negative electrode and gas generation due to decomposition of the negative electrode SEI itself. A third object of the present invention is to provide a nonaqueous alkali metal ion battery having high power output and excellent charge-discharge cycle characteristics by suppressing metal elution from a positive electrode, reducing the energy barrier of the solvation / desolvation process of alkali metal ions at the interface between a nonaqueous electrolyte solution and a positive electrode SEI, and increasing the ionic conductivity in the positive electrode SEI.

[0010] One aspect of the present disclosure is as follows.

[0011] Examples of the first embodiment are listed below. <1> A non-aqueous alkali metal ion battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte solution containing alkali metal ions, wherein the positive electrode has a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, the negative electrode has a negative electrode current collector and a negative electrode active material layer provided on one or both sides of the negative electrode current collector, the non-aqueous electrolyte solution contains a nitrile compound represented by the formula: R-CN (wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms) as a non-aqueous solvent in a proportion of 5% to 95% by volume, the negative electrode active material contained in the negative electrode active material layer has a solid electrolyte interface (SEI) on its surface, and a depth profile analysis of the SEI on the negative electrode surface by X-ray photoelectron spectroscopy (XPS) shows that the negative electrode active material has a solid electrolyte interface (SEI) on its surface after sputtering for a period of 5 minutes to 20 minutes. A nonaqueous alkali metal ion battery in which, when the detection rate of C1s (elemental carbon) in the following region is X1 (atomic % / min), and the detection rate of C1s (elemental carbon) in the region for a sputtering time of 30 minutes to 50 minutes is X2 (atomic % / min), X1 > 0 and X2 > 0, and 0.25 < (X1 - X2) < 2.75. <2> The nonaqueous alkali metal ion battery according to item 1, in which, in a profile analysis of the SEI on the negative electrode surface in the depth direction, 0.35 < X1 < 2.85 and 0.10 < X2 < 0.80. <3> The nonaqueous alkali metal ion battery according to item 1 or 2, in which, in a profile analysis of the SEI on the negative electrode surface in the depth direction, the detection rate X3 of C1s (elemental carbon) at a sputtering time of 10 minutes is 57.5 atomic % or more and 90.5 atomic % or less. <4> The nonaqueous electrolyte solution is a compound represented by the formula: LiN(SO ２ C ｍ F ２ｍ＋１ ) ２ {wherein m is an integer of 0 to 8}. <5> The nonaqueous alkali metal ion battery according to any one of items 1 to 3, wherein the nonaqueous electrolyte solution contains an imide salt represented by the formula: LiPF ６ and LiPF based on the molar mass of the imide salt. ６The nonaqueous alkali metal ion battery according to item 4, wherein the content ratio of the formula (I) is 0.01 to 10.00. <6> The nonaqueous alkali metal ion battery according to any one of items 1 to 5, wherein the nonaqueous electrolyte solution contains vinylene carbonate in a ratio of 0.01 to 10.00 mass%. <7> The nonaqueous alkali metal ion battery according to item 6, wherein the nonaqueous electrolyte solution contains an acid anhydride. <8> The nonaqueous alkali metal ion battery according to item 7, wherein the content of the vinylene carbonate is greater than the content of the acid anhydride. <9> The nonaqueous electrolyte solution contains a compound represented by the following general formula (1): R1-A-R2 (1), wherein R1 and R2 each independently represent an alkyl group having 1 to 4 carbon atoms which may be substituted with an aryl group or a halogen atom; or a vinylidene group which may be substituted with a halogen atom; or an aryl group which may be substituted with an alkyl group or a halogen atom; or R1 and R2 are bonded to each other to form, together with A, a cyclic structure which may have an unsaturated bond. <10> The nonaqueous alkali metal ion battery according to item 9, wherein the content of the vinylene carbonate is greater than the content of the compound represented by general formula (1). <11> The nonaqueous electrolyte solution contains one of the following compounds 1 to 5: 1. a fused polycyclic heterocyclic compound, 2. the fused polycyclic heterocyclic ring contains a pyrimidine skeleton, 3. the fused polycyclic heterocyclic ring contains three or more nitrogen atoms, 4. the fused polycyclic heterocyclic ring contains five or more sp2 carbons, The nonaqueous alkali metal ion battery according to any one of items 1 to 10, containing one or more compounds having a structure satisfying the following: no hydrogen atom is bonded to the nitrogen atom in the fused polycyclic heterocycle. <12> The nonaqueous alkali metal ion battery according to any one of items 1 to 11, wherein the nonaqueous electrolyte contains a nonionic surfactant in a proportion of 0.1 mass % to 4.0 mass %. <13> The nonaqueous alkali metal ion battery according to item 12, wherein the nonionic surfactant is one selected from the group consisting of ethyl laurate, triamyl phosphate, tris(2-butoxyethyl) phosphate, and tris(2-ethylhexyl) phosphate. <14> The capacity per unit area of ​​the negative electrode is N (mAh / cm ２ ), the capacity per unit area of ​​the positive electrode is P (mAh / cm ２15. The nonaqueous alkali metal ion battery according to any one of items 1 to 14, wherein the alkali metal ion is one selected from the group consisting of lithium ions, sodium ions, and potassium ions. 16. The nonaqueous alkali metal ion battery according to any one of items 1 to 15, wherein, in an XPS analysis of the positive electrode surface, peaks attributable to S2p (elemental sulfur) are at least 166 eV and at most 172 eV and at most 162 eV and at most 166 eV, and wherein, when Cs1 (atomic %) is the relative element concentration of S2p at least 166 eV and at most 172 eV and Cs2 (atomic %) is at most 162 eV and at most 166 eV, Cs1 / Cs2 is 0.50 or more and 0.95 or less. <17> The nonaqueous alkali metal ion battery according to item 16, wherein, in an XPS analysis of the positive electrode surface, Cs1 is 0.30 or more and 1.10 or less and Cs2 is 0.50 or more and 1.20 or less. <18> The nonaqueous alkali metal ion battery according to any one of items 1 to 17, wherein a ratio A1 / B of a total mass A1 (g) of the negative electrode active material to a mass B (g) of the nonaqueous electrolyte solution is 0.1 or more and 0.8 or less. <19> The nonaqueous alkali metal ion battery according to any one of items 1 to 18, wherein a ratio A2 / B of a total mass A2 (g) of the positive electrode active material contained in the positive electrode active material layer to a mass B (g) of the nonaqueous electrolyte solution is 0.2 or more and 1.2 or less. <20> In a depth profile analysis of the SEI on the negative electrode surface by X-ray photoelectron spectroscopy (XPS), a sputtering time of 5 minutes to 20 minutes is used. 20. The nonaqueous alkali metal ion battery according to any one of items 1 to 19, wherein Z1 (atomic % / min) is the detection rate of one alkali metal element selected from Li, Na, and K in the following range, and Z2 (atomic % / min) is the detection rate of one alkali metal element selected from Li, Na, and K in the sputtering time range of 30 minutes to 50 minutes, Z1 < 0 and Z2 < 0, and −1.95 < (Z1 − Z2) < −0.11.<21> The nonaqueous alkali metal ion battery according to item 20, wherein in a depth direction profile analysis of the SEI on the negative electrode surface, Z1 satisfies -2.20 < Z1 < -0.15. <22> The nonaqueous alkali metal ion battery according to item 20 or 21, wherein in a depth direction profile analysis of the SEI on the negative electrode surface, Z2 satisfies -2.80 < Z2 < -0.05. <23> The nonaqueous alkali metal ion battery according to any one of items 20 to 22, wherein in the depth direction profile analysis of the SEI on the negative electrode surface by XPS, the detection ratio Z3 of alkali metal elements at a sputtering time of 10 minutes is 5.0 atomic% or more and 18.0 atomic% or less. <24> In the depth direction profile analysis of the SEI on the negative electrode surface by X-ray photoelectron spectroscopy (XPS), the detection ratio Z3 of alkali metal elements at a sputtering time of 5 minutes to 20 minutes is 5.0 atomic% or more and 18.0 atomic% or less. The nonaqueous alkali metal ion battery according to any one of items 1 to 22, wherein, when the detection rate of O1s (oxygen element) in the following region is Y1 (atomic % / min) and the detection rate of O1s (oxygen element) in the region of from 30 minutes to 50 minutes is Y2 (atomic % / min), Y1 < 0 and Y2 < 0, and -1.50 < (Y1 - Y2) < -0.12. <25> The nonaqueous alkali metal ion battery according to item 24, wherein, in a depth profile analysis of the SEI on the negative electrode surface, -1.50 < Y1 < -0.14. <26> The nonaqueous alkali metal ion battery according to item 24 or 25, wherein, in a depth profile analysis of the SEI on the negative electrode surface, -0.15 < Y2 < -0.02. <27> In the depth profile analysis of the SEI on the negative electrode surface by XPS, 27. The nonaqueous alkali metal ion battery according to any one of items 24 to 26, wherein a detection ratio Y3 of O1s (oxygen element) in the nonaqueous alkali metal ion battery is 3.8 atomic% or more and 25.5 atomic% or less.<28> The nonaqueous alkali metal ion battery according to any one of items 1 to 27, having a structure of an electrode laminate or electrode wound body using the positive electrode and the negative electrode, the outermost layer of which is the negative electrode, and having a non-opposing negative electrode portion that does not face the positive electrode, wherein the negative electrode active material of the non-opposing negative electrode has a solid electrolyte interface (SEI) on its surface, and in a depth profile analysis of the SEI on the negative electrode surface by X-ray photoelectron spectroscopy (XPS), when an average relative elemental concentration of C1s (elemental carbon) on the non-opposing negative electrode surface in a region for a sputtering time of 5 minutes to 20 minutes is W1 (atomic %) and an average relative elemental concentration of C1s (elemental carbon) on the negative electrode surface facing the positive electrode in a region for a sputtering time of 5 minutes to 20 minutes is W2 (atomic %), the relationship is 1.05<(W1 / W2)<1.25. <29> The nonaqueous alkali metal ion battery according to item 28, wherein a depth profile analysis of an SEI on the negative electrode surface satisfies 1.06≦(W1 / W2)≦1.24. <30> The nonaqueous alkali metal ion battery according to any one of items 1 to 29, wherein the positive electrode active material contained in the positive electrode active material layer has a solid electrolyte interface (SEI) on its surface, and a depth profile analysis of the SEI on the positive electrode surface by X-ray photoelectron spectroscopy (XPS) satisfies the following conditions: 0.04<Ci1<0.50 and 0.10<Ci2<0.80, where Ci1 (atomic %) is the average relative elemental concentration of S2p (elemental sulfur) with a binding energy of 166 eV to 172 eV and Ci2 (atomic %) is the average relative elemental concentration of S2p (elemental sulfur) with a binding energy of 162 eV to 166 eV, for a sputtering time of 2 minutes to 10 minutes. <31> The nonaqueous alkali metal ion battery according to item 30, wherein in a profile analysis of the SEI on the positive electrode surface in the depth direction, 0.5≦Ci1≦0.4. <32> The nonaqueous alkali metal ion battery according to item 30 or 31, wherein in a profile analysis of the SEI on the positive electrode surface in the depth direction, 0.2≦Ci2≦0.75. <33> The nonaqueous alkali metal ion battery according to any one of items 30 to 32, wherein in a profile analysis of the SEI on the positive electrode surface in the depth direction, 0.13<(Ci1 / Ci2)<0.88.<34> The nonaqueous alkali metal ion battery according to any one of items 1 to 33, wherein the positive electrode active material contained in the positive electrode active material layer has a solid electrolyte interface (SEI) on its surface, and in a depth profile analysis of the SEI on the positive electrode surface by X-ray photoelectron spectroscopy (XPS), when D1 (atomic % / min) is the detection rate of F1s (elemental fluorine) with a binding energy of 686 eV to 690 eV in a sputtering time range of 2 minutes to 10 minutes and D2 (atomic % / min) is the detection rate of F1s (elemental fluorine) with a binding energy of 683 eV to 686 eV in a sputtering time range of 2 minutes to 10 minutes, D1 < 0 and D2 > 0, and −2.00 < (D1 / D2) < −1.00. <35> The nonaqueous alkali metal ion battery according to item 34, wherein in a profile analysis of the SEI in the depth direction on the positive electrode surface, −0.45<D1<−0.20. <36> The nonaqueous alkali metal ion battery according to item 34 or 35, wherein in a profile analysis of the SEI in the depth direction on the positive electrode surface, 0.15<D2<0.30.

[0012] Examples of the second embodiment are listed below. <37> A non-aqueous alkali metal ion battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte solution containing alkali metal ions, wherein the positive electrode has a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, the negative electrode has a negative electrode current collector and a negative electrode active material layer provided on one or both sides of the negative electrode current collector, the non-aqueous electrolyte solution contains a nitrile compound represented by the formula: R-CN {wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms} in a proportion of 5% by volume to 95% by volume as a non-aqueous solvent, the negative electrode active material contained in the negative electrode active material layer has a solid electrolyte interface (SEI) on its surface, and a depth profile analysis of the SEI on the negative electrode surface by X-ray photoelectron spectroscopy (XPS) shows that the SEI is a nitrile compound having a thickness of 100 μm or more and ... A nonaqueous alkali metal ion battery in which, when Z1 (atomic % / min) is the detection rate of one alkali metal element selected from Li, Na, and K in the following range, and Z2 (atomic % / min) is the detection rate of one alkali metal element selected from Li, Na, and K in the sputtering time range of 30 minutes to 50 minutes, Z1 < 0 and Z2 < 0, and -1.95 < (Z1 - Z2) < -0.11. <38> The nonaqueous alkali metal ion battery according to item 37, in which, in a depth profile analysis of the SEI on the negative electrode surface, -2.20 < Z1 < -0.15. <39> The nonaqueous alkali metal ion battery according to item 37 or 38, in which, in a depth profile analysis of the SEI on the negative electrode surface, -2.80 < Z2 < -0.05. <40> The nonaqueous alkali metal ion battery according to any one of items 37 to 39, wherein in the depth profile analysis of the SEI on the negative electrode surface by XPS, a detection ratio Z3 of alkali metal elements (lithium element if the nonaqueous alkali metal ion battery is a lithium ion battery, sodium element if the nonaqueous alkali metal ion battery is a sodium ion battery, or potassium element if the nonaqueous alkali metal ion battery is a potassium ion battery) at a sputtering time of 10 minutes is 5.0 atomic % or more and 18.0 atomic % or less.

[0013] Examples of the third embodiment are listed below. <41> A non-aqueous alkali metal ion battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte solution containing alkali metal ions, wherein the positive electrode has a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, the negative electrode has a negative electrode current collector and a negative electrode active material layer provided on one or both sides of the negative electrode current collector, the non-aqueous electrolyte solution contains a nitrile compound represented by the formula: R-CN (wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms) as a non-aqueous solvent in a proportion of 5% to 95% by volume, the negative electrode active material contained in the negative electrode active material layer has a solid electrolyte interface (SEI) on its surface, and a depth profile analysis of the SEI on the negative electrode surface by X-ray photoelectron spectroscopy (XPS) shows that the negative electrode active material has a solid electrolyte interface (SEI) on its surface after sputtering for a period of 5 minutes to 20 minutes. A nonaqueous alkali metal ion battery in which, when the detection rate of O1s (oxygen element) in the following region is Y1 (atomic % / min.) and the detection rate of O1s (oxygen element) in the region of from 30 minutes to 50 minutes is Y2 (atomic % / min.), Y1 < 0 and Y2 < 0, and -1.50 < (Y1 - Y2) < -0.12. <42> The nonaqueous alkali metal ion battery according to item 41, in which, in a profile analysis of the SEI in the depth direction on the negative electrode surface, -1.50 < Y1 < -0.14. <43> The nonaqueous alkali metal ion battery according to item 41 or 42, in which, in a profile analysis of the SEI in the depth direction on the negative electrode surface, -0.15 < Y2 < -0.02. <44> In the profile analysis of the SEI in the depth direction by XPS, 44. The nonaqueous alkali metal ion battery according to any one of items 41 to 43, wherein a detection ratio Y3 of O1s (oxygen element) is 3.8 atomic% or more and 25.5 atomic% or less.

[0014] Examples of the fourth embodiment are listed below. <45> A non-aqueous alkali metal ion battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte solution containing alkali metal ions, wherein the positive electrode has a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, the negative electrode has a negative electrode current collector and a negative electrode active material layer provided on one or both sides of the negative electrode current collector, and has a structure of an electrode laminate or electrode wound body using the positive electrode and the negative electrode, the outermost layer of which is the negative electrode, and the negative electrode does not face the positive electrode. a non-aqueous alkali metal ion battery having a counter negative electrode portion, wherein the non-aqueous electrolyte solution contains a nitrile compound represented by the formula: R-CN (wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms) as a non-aqueous solvent in a proportion of 5 to 95 volume %; the negative electrode active material of the non-counter negative electrode has a solid electrolyte interface (SEI) on its surface; and in a depth profile analysis of the SEI on the negative electrode surface by X-ray photoelectron spectroscopy (XPS), when W1 (atomic %) is an average relative elemental concentration of C1s (elemental carbon) on the non-counter negative electrode surface in a region where a sputtering time is 5 to 20 minutes, and W2 (atomic %) is an average relative elemental concentration of C1s (elemental carbon) on the negative electrode surface facing the positive electrode in a region where a sputtering time is 5 to 20 minutes, the relationship is 1.05<(W1 / W2)<1.25. <46> The nonaqueous alkali metal ion battery according to item 45, wherein in a depth profile analysis of the SEI of the negative electrode, 1.06≦(W1 / W2)≦1.24.

[0015] Examples of the fifth embodiment are listed below. <47> A non-aqueous alkali metal ion battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte solution containing alkali metal ions, wherein the positive electrode has a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, the negative electrode has a negative electrode current collector and a negative electrode active material layer provided on one or both sides of the negative electrode current collector, the non-aqueous electrolyte solution contains a nitrile compound represented by the formula: R-CN (wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms) as a non-aqueous solvent in a proportion of 5% by volume to 95% by volume, the positive electrode active material contained in the positive electrode active material layer has a solid electrolyte interface (SEI) on its surface, and a depth profile analysis of the SEI on the positive electrode surface by X-ray photoelectron spectroscopy (XPS) shows that the positive electrode active material has a solid electrolyte interface (SEI) on its surface after sputtering for a period of 2 minutes to 10 minutes. A nonaqueous alkali metal ion battery, wherein Ci1 (atomic %) is the average relative element concentration of S2p (elemental sulfur) with a binding energy of 166 eV to 172 eV and Ci2 (atomic %) is the average relative element concentration of S2p (elemental sulfur) with a binding energy of 162 eV to 166 eV, and Ci2 (atomic %) satisfies the following conditions: 0.04 < Ci1 < 0.50 and 0.10 < Ci2 < 0.80. <48> The nonaqueous alkali metal ion battery according to item 47, wherein, in a depth profile analysis of the SEI on the positive electrode surface, 0.5 ≦ Ci1 ≦ 0.4. <49> The nonaqueous alkali metal ion battery according to item 47 or 48, wherein, in a depth profile analysis of the SEI on the positive electrode surface, 0.2 ≦ Ci2 ≦ 0.75. <50> The nonaqueous alkali metal ion battery according to any one of items 47 to 49, wherein in a profile analysis of the SEI on the positive electrode surface in the depth direction, 0.13<(Ci1 / Ci2)<0.88.

[0016] Examples of the sixth embodiment are listed below. <51> A non-aqueous alkali metal ion battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte solution containing alkali metal ions, wherein the positive electrode has a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, the negative electrode has a negative electrode current collector and a negative electrode active material layer provided on one or both sides of the negative electrode current collector, the non-aqueous electrolyte solution contains a nitrile compound represented by the formula: R-CN (wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms) as a non-aqueous solvent in a proportion of 5% by volume to 95% by volume, the positive electrode active material contained in the positive electrode active material layer has a solid electrolyte interface (SEI) on its surface, and a depth profile analysis of the SEI on the positive electrode surface by X-ray photoelectron spectroscopy (XPS) shows that the positive electrode active material has a solid electrolyte interface (SEI) on its surface after sputtering for a period of 2 minutes to 10 minutes. A nonaqueous alkali metal ion battery, wherein D1 (atomic % / min) is the detection rate of F1s (elemental fluorine) in the region below where the binding energy is 686 eV or more and 690 eV or less, and D2 (atomic % / min) is the detection rate of F1s (elemental fluorine) in the region below where the binding energy is 683 eV or more and 686 eV or less for a sputtering time of 2 minutes to 10 minutes, D1 < 0 and D2 > 0, and -2.00 < (D1 / D2) < -1.00. <52> The nonaqueous alkali metal ion battery according to item 51, wherein in a depth profile analysis of the SEI on the positive electrode surface, -0.45 < D1 < -0.20. <53> The nonaqueous alkali metal ion battery according to item 51 or 52, wherein in a depth profile analysis of the SEI on the positive electrode surface, 0.15 < D2 < 0.30.

[0017] Another aspect of the present disclosure is as follows: <54> A method for producing a nonaqueous alkali metal ion secondary battery including a positive electrode, a negative electrode, a nonaqueous electrolyte solution, and a separator, the method comprising: an assembling step of assembling a nonaqueous alkali metal ion secondary battery precursor including the positive electrode, the negative electrode, the nonaqueous electrolyte solution, and the separator; and an initial charge / discharge step of subjecting the nonaqueous alkali metal ion secondary battery precursor to an initial charge / discharge, wherein the positive electrode has a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, and the negative electrode has a negative electrode current collector and a negative electrode active material layer provided on one or both sides of the negative electrode current collector, and wherein a solid electrolyte interface (SEI) coating layer on a surface of a negative electrode active material included in the negative electrode active material layer has the following profile: In a depth profile analysis of the SEI coating layer on the surface of the negative electrode by X-ray photoelectron spectroscopy (XPS), it is found that where X1 (atomic % / min) is the detection ratio of C1s (carbon element) in the region of sputtering time from 30 min to 20 min, and X2 (atomic % / min) is the detection ratio of C1s (carbon element) in the region of sputtering time from 30 min to 50 min, X1 > 0 and X2 > 0, and 0.25 < (X1 - X2) < 2.75; the nonaqueous electrolyte solution contains, as a nonaqueous solvent, 5 vol % to 95 vol % of a nitrile compound represented by the formula: R-CN {wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms}, and vinylene carbonate; the initial charge / discharge step includes at least two successive initial charge steps, and the charge rate in each step is 0.01 mA / cm ２ ~4.00mA / cm ２ a charging rate in the second stage is higher than a charging rate in the first stage, and the charging temperature in each step is in the range of 25°C to 40°C, and the charging temperature in the second stage is 10°C to 15°C higher than the charging temperature in the first stage.

[0018] According to the present invention, it is possible to provide a nonaqueous alkali metal ion battery that suppresses the decomposition reaction of a nitrile compound and forms an SEI that promotes the intercalation and deintercalation of alkali metal ions at the active material interface, thereby achieving both high charge-discharge cycle durability and high output characteristics.

[0019] Fig. 1 is an XPS depth profile of the negative electrode surface of the nonaqueous alkali metal ion battery obtained in Example 1. Fig. 2 is an XPS depth profile of the negative electrode surface of the nonaqueous alkali metal ion battery obtained in Comparative Example 1. Fig. 3 is an XPS depth profile of the positive electrode surface of the nonaqueous alkali metal ion battery obtained in Example 26.

[0020] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described. The present invention is not limited to the present embodiment described below. At least one of the upper limit value and the lower limit value in each numerical range described in this specification may be arbitrarily combined, that is, any numerical range may be formed. At least one of the upper limit value and the lower limit value in each numerical range described in this specification may be replaced with the corresponding value described in the examples.

[0021] In one aspect of the present disclosure, a nonaqueous alkali metal ion battery is provided, which includes a positive electrode, a negative electrode, and a nonaqueous electrolyte solution containing alkali metal ions. It has been discovered that the nonaqueous alkali metal ion batteries according to the first to sixth embodiments described below can suppress the decomposition reaction of a nitrile compound and form a solid electrolyte interface (SEI) that promotes the insertion and removal of alkali metal ions at the active material interface, thereby achieving both high charge-discharge cycle durability and high output characteristics.

[0022] First Embodiment A nonaqueous alkali metal ion battery according to a first embodiment includes a positive electrode having a positive current collector and a positive electrode active material layer provided on one or both surfaces of the positive current collector, a negative electrode having a negative electrode current collector and a negative electrode active material layer provided on one or both surfaces of the negative electrode current collector, a nonaqueous electrolyte solution containing a nitrile compound represented by the formula: R-CN (wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms) as a nonaqueous solvent in a proportion of 5% to 95% by volume, a negative electrode active material contained in the negative electrode active material layer having a solid electrolyte interface (SEI) on its surface, and a depth profile analysis of the SEI on the negative electrode surface by X-ray photoelectron spectroscopy (XPS) in a region of a sputtering time of 5 to 20 minutes inclusive, wherein the detection ratio of C1s (elemental carbon) is X1 (atomic % / min.) and a depth profile analysis of the SEI on the negative electrode surface in a region of a sputtering time of 5 to 20 minutes inclusive, wherein the detection ratio of C1s is X1 (atomic % / min.) and a depth profile analysis of the SEI on the negative electrode surface in a region of a sputtering time of 30 minutes inclusive, wherein the detection ratio of C1s ...30 minutes inclusive, wherein the detection ratio of C1s is X1 (atomic % / min. When the detection rate of C1s (elemental carbon) in the region of 1000 to 50 min is X2 (atomic % / min), X1 > 0 and X2 > 0, and 0.25 < (X1 - X2) < 2.75. This suppresses the decomposition reaction of the nitrile compound and forms a solid electrolyte interface (SEI) that promotes the insertion and desorption of alkali metal ions at the active material interface, thereby achieving both high charge-discharge cycle durability and high output characteristics.

[0023] In the first embodiment, from the viewpoint of significantly achieving the effects of the present disclosure, in a profile analysis of the SEI on the surface of the negative electrode in the depth direction, it is preferable that 0.35 < X1 < 2.85 and / or 0.10 < X2 < 0.80 is satisfied, and it is more preferable that 0.35 < X1 < 2.85 and 0.10 < X2 < 0.80 are satisfied.

[0024] In the first embodiment, from the viewpoint of significantly achieving the effects of the present disclosure, in the profile analysis of the SEI on the negative electrode surface in the depth direction, the detection ratio X3 of C1s (carbon element) at a sputtering time of 10 minutes is preferably 57.5 atomic% or more and 90.5 atomic% or less.

[0025] Second Embodiment A nonaqueous alkali metal ion battery according to a second embodiment has a positive electrode having a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, a negative electrode having a negative electrode current collector and a negative electrode active material layer provided on one or both sides of the negative electrode current collector, a nonaqueous electrolyte solution containing a nitrile compound represented by the formula: R-CN (wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms) as a nonaqueous solvent in a proportion of 5% by volume to 95% by volume, a negative electrode active material contained in the negative electrode active material layer has a solid electrolyte interface (SEI) on its surface, and a depth profile analysis of the SEI on the negative electrode surface by X-ray photoelectron spectroscopy (XPS) shows that the SEI is a nitrile compound having a thickness of 100 μm or more and ... When the detection rate of one alkali metal element selected from Li, Na, and K in the following range is Z1 (atomic % / min.), and the detection rate of one alkali metal element selected from Li, Na, and K in the sputtering time range of 30 minutes to 50 minutes is Z2 (atomic % / min.), Z1 < 0 and Z2 < 0, and −1.95 < (Z1 − Z2) < −0.11. This suppresses the decomposition reaction of the nitrile compound and forms a solid electrolyte interface (SEI) that promotes the insertion and removal of alkali metal ions at the active material interface, thereby achieving both high charge / discharge cycle durability and high output characteristics.

[0026] In the second embodiment, from the viewpoint of significantly achieving the effects of the present disclosure, in the profile analysis of the SEI on the negative electrode surface in the depth direction, it is preferable that −2.20<Z1<−0.15 and / or −2.80<Z2<−0.05, and it is more preferable that −2.20<Z1<−0.15 and −2.80<Z2<−0.05 are satisfied.

[0027] In the second embodiment, from the viewpoint of significantly achieving the effects of the present disclosure, it is preferable that the detection ratio Z3 of the alkali metal element at a sputtering time of 10 minutes in the depth direction profile analysis of the SEI on the negative electrode surface by XPS be 5.0 atomic% or more and 18.0 atomic% or less. The alkali metal element may be, for example, lithium (Li) element when the nonaqueous alkali metal ion battery is a lithium ion battery, sodium (Na) element when the nonaqueous alkali metal ion battery is a sodium ion battery, or potassium (K) element when the nonaqueous alkali metal ion battery is a potassium ion battery.

[0028] Third Embodiment A nonaqueous alkali metal ion battery according to a third embodiment includes a positive electrode having a positive current collector and a positive electrode active material layer provided on one or both surfaces of the positive current collector, a negative electrode having a negative electrode current collector and a negative electrode active material layer provided on one or both surfaces of the negative electrode current collector, a nonaqueous electrolyte solution containing a nitrile compound represented by the formula: R-CN (wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms) as a nonaqueous solvent in a proportion of 5% to 95% by volume, a negative electrode active material contained in the negative electrode active material layer has a solid electrolyte interface (SEI) on its surface, and in a depth profile analysis of the SEI on the negative electrode surface by X-ray photoelectron spectroscopy (XPS), the detection ratio of O1s (oxygen element) in a region of 5 to 20 minutes inclusive in a sputtering time is Y1 (atomic % / min), and a detection ratio of O2s in a region of 30 minutes inclusive in a sputtering time is Y2 (atomic % / min). When the detection rate of O1s (oxygen element) in the region of 1000 to 50 min is Y2 (atomic % / min), Y1 < 0 and Y2 < 0, and -1.50 < (Y1 - Y2) < -0.12. This suppresses the decomposition reaction of the nitrile compound and forms a solid electrolyte interface (SEI) that promotes the insertion and removal of alkali metal ions at the active material interface, thereby achieving both high charge-discharge cycle durability and high output characteristics.

[0029] In the third embodiment, from the viewpoint of significantly achieving the effects of the present disclosure, in a profile analysis of the SEI on the negative electrode surface in the depth direction, it is preferable that −1.50<Y1<−0.14 and / or −0.15<Y2<−0.02 be satisfied, and it is more preferable that −1.50<Y1<−0.14 and −0.15<Y2<−0.02 be satisfied.

[0030] In the third embodiment, from the viewpoint of significantly achieving the effects of the present disclosure, in the profile analysis of the SEI on the negative electrode surface in the depth direction by the XPS, the detection ratio Y3 of O1s (oxygen element) at a sputtering time of 10 minutes is preferably 3.8 atomic% or more and 25.5 atomic% or less.

[0031] <Fourth embodiment> a non-aqueous alkali metal ion battery according to a fourth embodiment, the battery having a positive electrode including a positive current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector; a negative electrode including a negative electrode current collector and a negative electrode active material layer provided on one or both sides of the negative electrode current collector, the battery having a structure of an electrode laminate or an electrode wound body using the positive electrode and the negative electrode, the outermost layer of which is a negative electrode, and the battery having a non-opposing negative electrode portion that does not face the positive electrode; a non-aqueous electrolyte solution containing a nitrile compound represented by the formula: R-CN (wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms) as a non-aqueous solvent in a proportion of 5% by volume to 95% by volume; the negative electrode active material of the non-opposing negative electrode having a solid electrolyte interface (SEI) on its surface; and a depth profile analysis of the SEI on the negative electrode surface by X-ray photoelectron spectroscopy (XPS) showing that the SEI is a nitrile compound having a thickness of 100 μm or less after sputtering for 5 minutes. When the average relative element concentration of C1s (carbon element) on the non-opposing negative electrode surface in the region of from 5 minutes to 20 minutes is W1 (atomic %) and the average relative element concentration of C1s (carbon element) on the negative electrode surface facing the positive electrode in the region of from 5 minutes to 20 minutes is W2 (atomic %), the relationship is 1.05<(W1 / W2)<1.25. This suppresses the decomposition reaction of the nitrile compound and forms a solid electrolyte interface (SEI) that promotes the insertion and desorption of alkali metal ions at the active material interface, thereby achieving both high charge-discharge cycle durability and high output characteristics.

[0032] In the fourth embodiment, from the viewpoint of significantly achieving the effects of the present disclosure, it is preferable that 1.06≦(W1 / W2)≦1.24 be satisfied in the profile analysis of the SEI on the negative electrode surface in the depth direction.

[0033] Fifth Embodiment A nonaqueous alkali metal ion battery according to a fifth embodiment includes a positive electrode having a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, a negative electrode having a negative electrode current collector and a negative electrode active material layer provided on one or both sides of the negative electrode current collector, a nonaqueous electrolyte solution containing a nitrile compound represented by the formula: R-CN (wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms) as a nonaqueous solvent in a proportion of 5% by volume to 95% by volume, a positive electrode active material contained in the positive electrode active material layer has a solid electrolyte interface (SEI) on its surface, and a depth profile analysis of the SEI on the positive electrode surface by X-ray photoelectron spectroscopy (XPS) shows that the positive electrode active material has a solid electrolyte interface (SEI) on its surface after sputtering for a period of 2 minutes to 10 minutes. When the average relative element concentration of S2p (sulfur element) with a binding energy of 166 eV or more and 172 eV or less is Ci1 (atomic %) and the average relative element concentration of S2p (sulfur element) with a binding energy of 162 eV or more and 166 eV or less is Ci2 (atomic %), Ci1 satisfies 0.04 < Ci1 < 0.50 and 0.10 < Ci2 < 0.80. This suppresses the decomposition reaction of the nitrile compound and forms a solid electrolyte interface (SEI) that promotes the insertion and desorption of alkali metal ions at the active material interface, thereby achieving both high charge-discharge cycle durability and high output characteristics.

[0034] In the fifth embodiment, from the viewpoint of significantly achieving the effects of the present disclosure, in the profile analysis of the SEI on the positive electrode surface in the depth direction, it is preferable to satisfy any one of the following, and it is more preferable to satisfy all of the following: 0.5≦Ci1≦0.4 0.2≦Ci2≦0.75 0.13<(Ci1 / Ci2)<0.88.

[0035] Sixth Embodiment A nonaqueous alkali metal ion battery according to a sixth embodiment includes a positive electrode having a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, a negative electrode having a negative electrode current collector and a negative electrode active material layer provided on one or both sides of the negative electrode current collector, a nonaqueous electrolyte solution containing a nitrile compound represented by the formula: R-CN (wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms) as a nonaqueous solvent in a proportion of 5% by volume to 95% by volume, a positive electrode active material contained in the positive electrode active material layer has a solid electrolyte interface (SEI) on its surface, and a depth profile analysis of the SEI on the positive electrode surface by X-ray photoelectron spectroscopy (XPS) shows that the positive electrode active material has a solid electrolyte interface (SEI) on its surface after sputtering for a period of 2 minutes to 10 minutes. When the detection rate of F1s (elemental fluorine) in the region with a bond energy of 686 eV to 690 eV is defined as D1 (atomic % / min), and the detection rate of F1s (elemental fluorine) in the region with a bond energy of 683 eV to 686 eV in the region with a sputtering time of 2 minutes to 10 minutes is defined as D2 (atomic % / min), D1 < 0 and D2 > 0, and -2.00 < (D1 / D2) < -1.00. This suppresses the decomposition reaction of the nitrile compound and forms a solid electrolyte interface (SEI) that promotes the desorption and insertion of alkali metal ions at the active material interface, thereby achieving both high charge-discharge cycle durability and high output characteristics.

[0036] In the sixth embodiment, from the viewpoint of significantly exhibiting the effects of the present disclosure, in the profile analysis of the SEI on the positive electrode surface in the depth direction, it is preferable that −0.45<D1<−0.20 and / or 0.15<D2<0.30, and it is more preferable that both −0.45<D1<−0.20 and 0.15<D2<0.30 are satisfied.

[0037] The nonaqueous alkali metal ion batteries according to the first to sixth embodiments described above are interchangeable or can be combined with each other in terms of configuration or components. Common or preferred configurations or components of the nonaqueous alkali metal ion batteries according to the first to sixth embodiments will be described below.

[0038] <<Non-aqueous Electrolyte>> The term "non-aqueous electrolyte" refers to an electrolyte containing 1% by mass or less of water relative to the total amount of the non-aqueous electrolyte. It is preferable that the non-aqueous electrolyte contains as little water as possible, but it may contain a very small amount of water as long as it does not impede the solution of the problems of the present invention. The water content is 300 ppm by mass or less, preferably 200 ppm by mass or less, based on the total amount of the non-aqueous electrolyte. As long as the non-aqueous electrolyte has a configuration that achieves the problem of the present invention, the other components can be appropriately selected and applied from the constituent materials of known non-aqueous electrolytes used in non-aqueous alkali metal ion batteries.

[0039] The non-aqueous electrolyte solution may contain a non-aqueous solvent and a lithium salt, and may further contain various additives.

[0040] <Non-aqueous solvent> In the present disclosure, the term "non-aqueous solvent" refers to elements remaining in a non-aqueous electrolyte solution, excluding lithium salts and various additives. Examples of non-aqueous solvents include alcohols such as methanol and ethanol; aprotic solvents; and the like. Among these, aprotic solvents (polar aprotic solvents) are preferred as non-aqueous solvents. The non-aqueous solvent may contain a solvent other than an aprotic solvent, as long as it does not impede the solution of the problems of the present invention.

[0041] The non-aqueous solvent is characterized by containing a nitrile compound represented by the formula: R-CN (wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms). When the non-aqueous solvent contains a nitrile compound represented by the formula: R-CN, the ionic conductivity of the non-aqueous electrolyte can be significantly increased. Because nitrile compounds are easily reductively decomposed, when a nitrile compound is used as the non-aqueous solvent, it is preferable to use another solvent (for example, an aprotic solvent other than a nitrile compound) in combination with the nitrile compound and / or to add a predetermined additive.

[0042] The content of the nitrile compound is preferably 5% by volume or more and 95% by volume or less, more preferably 10% by volume or more and 80% by volume or less, and even more preferably 15% by volume or more and 70% by volume or less, relative to the total amount of the nonaqueous solvent. If the content of the nitrile compound is 5% by volume or more, the ionic conductivity of the nonaqueous electrolyte solution is increased, and the output characteristics of the nonaqueous alkali metal ion battery can be improved. If the content of the nitrile compound is 95% by volume or less, the charge-discharge cycle characteristics are excellent.

[0043] Examples of the nitrile compound include acetonitrile, propionitrile, butyronitrile, isobutyronitrile, pentanenitrile, 2-methylbutyronitrile, and 3-methylbutyronitrile.

[0044] Examples of aprotic solvents other than nitrile compounds include cyclic carbonates, chain carbonates, lactones, cyclic ethers, chain ethers, short-chain fatty acid esters, fluorinated ethers, ketones, and compounds in which some or all of the H atoms of the above compounds are substituted with halogen atoms. The non-aqueous electrolyte solution containing a cyclic carbonate and a chain carbonate is advantageous in that it dissolves lithium salts at a desired concentration and exhibits high ionic conductivity. Examples of cyclic carbonates include alkylene carbonate compounds such as ethylene carbonate, propylene carbonate, and butylene carbonate. Examples of chain carbonates include dialkyl carbonate compounds such as dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dipropyl carbonate, and dibutyl carbonate, and are preferably one or more selected from dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate.

[0045] Examples of the chain ether include dimethoxyethane, diethoxyethane, diethyl ether, 1,3-dioxolane, diglyme, triglyme, and tetraglyme, and preferably at least one selected from dimethoxyethane and diethoxyethane.

[0046] Examples of short-chain fatty acid esters include methyl acetate, methyl propionate, methyl isobutyrate, methyl butyrate, methyl isovalerate, methyl valerate, methyl pivalate, methyl hydroangelate, methyl caproate, ethyl acetate, ethyl propionate, ethyl isobutyrate, ethyl butyrate, ethyl isovalerate, ethyl valerate, ethyl pivalate, ethyl hydroangelate, ethyl caproate, propyl acetate, propyl propionate, propyl isobutyrate, propyl butyrate, propyl isovalerate, propyl valerate, propyl pivalate, propyl hydroangelate, propyl caproate, isopropyl acetate, isopropyl propionate, isopropyl isobutyrate, isopropyl butyrate, isopropyl isovalerate, isopropyl valerate, isopropyl pivalate, isopropyl hydroangelate, and isocaproate. Examples of the alkyl ester include propyl, butyl acetate, butyl propionate, butyl isobutyrate, butyl butyrate, butyl isovalerate, butyl valerate, butyl pivalate, butyl hydroangelate, butyl caproate, isobutyl acetate, isobutyl propionate, isobutyl isobutyrate, isobutyl butyrate, isobutyl isovalerate, isobutyl valerate, isobutyl pivalate, isobutyl hydroangelate, isobutyl caproate, tert-butyl acetate, tert-butyl propionate, tert-butyl isobutyrate, tert-butyl butyrate, tert-butyl isovalerate, tert-butyl valerate, tert-butyl pivalate, tert-butyl hydroangelate, and tert-butyl caproate, and preferably one or more selected from methyl acetate, methyl propionate, ethyl acetate, and ethyl propionate.

[0047] The aprotic solvents other than the nitrile compounds may be used alone or in combination of two or more.

[0048] The nonaqueous solvent preferably contains one or more of a cyclic carbonate and a chain carbonate in combination with the nitrile compound from the viewpoint of improving the stability of the nonaqueous electrolyte solution. From this viewpoint, the nonaqueous solvent preferably contains both a cyclic carbonate and a chain carbonate in combination with the nitrile compound.

[0049] <Alkali Metal Salt> The non-aqueous electrolyte solution may contain an alkali metal salt. Examples of the alkali metal salt include MN(SO ２ C ｍ F ２ｍ＋１ ) ２ Preferably, the imide salt is represented by the formula: {wherein M is one selected from Li, Na, and K, and m is an integer of 0 to 8}. The alkali metal salt may further include, in addition to the imide salt, one or more selected from fluorine-containing inorganic alkali metal salts, organic alkali metal salts, and other alkali metal salts.

[0050] Specific examples of imide salts include MN(SO ２ F) ２ {wherein M is one selected from Li, Na, and K}, and / or MN(SO ２ CF ３ ) ２ {wherein M is one selected from Li, Na and K}.

[0051] Since imide salts themselves have a relatively high decomposition temperature, the inclusion of imide salts as alkali metal salts in the nonaqueous electrolyte solution suppresses an increase in resistance during high-temperature storage. Furthermore, the inclusion of imide salts as alkali metal salts in the nonaqueous electrolyte solution reduces the viscosity of the nonaqueous electrolyte solution, thereby enabling the battery to exhibit excellent output performance, particularly in the low-temperature range.

[0052] The content of the imide salt is preferably 0.1% by mass to 40% by mass, more preferably 0.2% by mass to 30% by mass, and even more preferably 0.5% by mass to 20% by mass, relative to the total amount of the nonaqueous electrolyte solution. By keeping the content within this range, the ionic conductivity of the nonaqueous electrolyte solution is not reduced, and performance at low temperatures can be improved.

[0053] The non-aqueous electrolyte further contains MPF as an alkali metal salt. ６ {wherein M is one selected from Li, Na, and K}, and the molar mass ratio of the MPF to the imide salt is preferably 0.01 or more and 10.00 or less. ６When the content ratio of {wherein M is one selected from Li, Na, and K} is 0.01 or more, a passive film can be formed on the surface of the positive electrode current collector, and the corrosion reaction of the positive electrode current collector by the imide salt can be suppressed. ６ This can suppress the generation of HF due to the decomposition of the fluorine-containing compound, thereby improving the charge-discharge cycle characteristics.

[0054] Other alkali metal salts include, for example, MPO ２ F ２ , MC(SO ２ F) ３ , MC(SO ２ CF ３ ) ３ , MC(SO ２ C ２ F ５ ) ３ , MCF ３ SO ３ , M.C. ４ F ９ SO ３ , MAsF ６ , MB (C ２ O ４ ) ２ , MBF ２ (C ２ O ４ ), MBF ４ {wherein M is one selected from Li, Na, and K}.

[0055] The alkali metal salt concentration in the non-aqueous electrolyte is preferably 0.5 mol / L or more, more preferably 0.5 to 2.0 mol / L, as the total concentration of the alkali metal salts. If the alkali metal salt concentration is 0.5 mol / L or more, sufficient anions are present, making it easy to increase the battery capacity. If the alkali metal salt concentration is 2.0 mol / L or less, it is easy to prevent undissolved alkali metal salts from precipitating in the non-aqueous electrolyte and the viscosity of the non-aqueous electrolyte from becoming too high, making it difficult for the ionic conductivity to decrease, and therefore, making it difficult for the output characteristics to decrease.

[0056] In non-aqueous alkali metal ion batteries, the alkali metal ion used as the cation is one selected from the group consisting of lithium (Li) ions, sodium (Na) ions, and potassium (K) ions. In addition to the above-mentioned Li, Na, and K, rubidium (Rb) and cesium (Cs) may also be used as alkali metal elements of Group 1 elements. However, these elements are not preferred because they cause large volume changes when inserted into or removed from the carbon material of the negative electrode. If the alkali metal element used is Li, Na, or K, not only can ions be stably inserted into or removed from the carbon material of the negative electrode, but the solvation state of the ions in the non-aqueous electrolyte is equivalent, and the SEI formation process on the positive and negative electrodes proceeds via the same mechanism, so it is believed that similar results can be obtained. In one aspect of the present disclosure, the composition and structure of the SEI formed on the positive and negative electrodes are important for achieving both improved output characteristics and charge / discharge cycle characteristics, and the basic principle is the same whether the alkali metal ion is Li ion, Na ion, or K ion. When the alkali metal ions are Li ions, the present technology can be applied to a lithium ion battery; when the alkali metal ions are Na ions, the present technology can be applied to a sodium ion battery; and when the alkali metal ions are K ions, the present technology can be applied to a potassium ion battery.

[0057] <Various Additives> The non-aqueous electrolyte solution may further contain various additives.

[0058] When the non-aqueous electrolytic solution contains an acid anhydride, the content thereof is preferably in the range of 0.01% by mass or more and 10.00% by mass or less, more preferably 0.05% by mass or more and 1.00% by mass or less, and even more preferably 0.10% by mass or more and 0.50% by mass or less, relative to 100% by mass of the non-aqueous electrolytic solution.

[0059] The non-aqueous electrolyte preferably contains vinylene carbonate (VC). The nitrile compound used as the non-aqueous solvent of the non-aqueous electrolyte is susceptible to reduction reactions and preferably forms a strong SEI on the surface of the negative electrode active material. In addition to the VC consumed to form the SEI on the negative electrode during the initial charge, the non-aqueous electrolyte preferably contains VC to repair the SEI that is lost over the course of charge-discharge cycles.

[0060] The VC content is preferably in the range of 0.01% by mass to 10.00% by mass, more preferably 0.05% by mass to 1.00% by mass, and even more preferably 0.10% by mass to 0.50% by mass, per 100% by mass of the non-aqueous electrolyte solution. If the VC content is 0.01% by mass or more, a strong SEI can be formed on the surface of the negative electrode active material, improving the cycle durability of the non-aqueous alkali metal ion battery. If the VC content is 10.00% by mass or less, excessive SEI formation on the surface of the negative electrode active material can be suppressed, improving output characteristics.

[0061] Non-aqueous alkali metal ion batteries are stabilized by the decomposition of a portion of the non-aqueous electrolyte solution during initial charging, forming an SEI on the negative electrode surface. To more effectively strengthen this SEI, an acid anhydride can be added. When a nitrile compound is included as the non-aqueous solvent, the strength of the SEI tends to decrease with increasing temperature, but the addition of an acid anhydride promotes strengthening of the SEI. Therefore, the use of such an acid anhydride can effectively suppress the increase in internal resistance over time due to thermal history.

[0062] Specific examples of acid anhydrides include chain acid anhydrides such as acetic anhydride, propionic anhydride, and benzoic anhydride; cyclic acid anhydrides such as malonic anhydride, succinic anhydride, glutaric anhydride, maleic anhydride, phthalic anhydride, 1,2-cyclohexanedicarboxylic anhydride, 2,3-naphthalenedicarboxylic anhydride, and naphthalene-1,4,5,8-tetracarboxylic dianhydride; and mixed acid anhydrides having a structure formed by dehydration condensation of different types of acids, such as two different types of carboxylic acids or a carboxylic acid and a sulfonic acid. These may be used alone or in combination of two or more. Among these, cyclic acid anhydrides are preferred because they have a high reductive decomposition potential and can more effectively form an SEI on the negative electrode.

[0063] Since it is preferable for non-aqueous alkali metal ion batteries to strengthen the SEI before the reductive decomposition of the non-aqueous solvent, it is preferable for the acid anhydride to contain at least one cyclic acid anhydride that acts early during the first charge. These cyclic acid anhydrides may be contained alone or in combination. Alternatively, a cyclic acid anhydride other than these cyclic acid anhydrides may be contained. Furthermore, the cyclic acid anhydride preferably contains at least one of succinic anhydride, maleic anhydride, and phthalic anhydride. A non-aqueous electrolyte containing at least one of succinic anhydride, maleic anhydride, and phthalic anhydride can form a strong SEI on the negative electrode and more effectively suppress an increase in resistance during high-temperature heating. In particular, it is preferable for the electrolyte to contain succinic anhydride. This allows a strong SEI to be formed on the surface of the negative electrode active material more effectively while suppressing side reactions.

[0064] For the non-aqueous electrolyte solution, instead of the above-mentioned acid anhydride, a compound represented by the following general formula (1): R1-A-R2 (1) (wherein A is one of the following formulae (1-2) to (1-5): and R1 and R2 each independently represent an alkyl group having 1 to 4 carbon atoms which may be substituted with an aryl group or a halogen atom; or a vinylidene group which may be substituted with a halogen atom; or an aryl group which may be substituted with an alkyl group or a halogen atom; or R1 and R2 bond to each other to form, together with A, a cyclic structure which may have an unsaturated bond.}, together with VC, etc., can also be used.

[0065] Specific examples of the oxygen-sulfur-containing compound represented by general formula (1) include at least one selected from the group consisting of dimethyl sulfite, diethyl sulfite, dimethyl sulfoxide, sulfolane, 3-sulfolene, ethylene sulfite, propylene sulfite, 1,3-propene sultone, 1,3-propane sultone, diphenyl sulfone, phenyl vinyl sulfone, divinyl sulfone, methyl vinyl sulfone, ethyl vinyl sulfone, and 1,3,2-dioxathiane 2-oxide. Among these, from the viewpoint of suppressing or preventing a decrease in capacity during rapid charging of a nonaqueous secondary battery, dimethyl sulfite, diethyl sulfite, dimethyl sulfoxide, ethylene sulfite, propylene sulfite, and 1,3,2-dioxathiane 2-oxide are preferred, ethylene sulfite and / or 1,3,2-dioxathiane 2-oxide are more preferred, and ethylene sulfite is particularly preferred.

[0066] The content of VC is preferably greater than the content of the acid anhydride. When the compound represented by general formula (1) is used instead of the acid anhydride, the content of VC is preferably greater than the content of the compound represented by general formula (1).

[0067] The acid anhydride or the compound of general formula (1) triggers the SEI formation reaction and reacts cooperatively with VC to form a strong SEI on the surface of the negative electrode active material. It is believed that this strong SEI inhibits the reductive decomposition reaction of the nitrile compound, resulting in high charge-discharge cycle durability. By increasing the amount of VC mixed in the nonaqueous electrolyte solution relative to the amount of the acid anhydride or the compound of general formula (1), it is possible to allow VC to remain in the nonaqueous electrolyte solution even after conditioning of the lithium-ion battery is complete. During charge-discharge cycles, especially those under high-temperature conditions, the SEI on the surface of the negative electrode active material is prone to loss. The decomposition reaction of the nonaqueous electrolyte from this point onward is also believed to be one of the causes of deterioration of nonaqueous alkali metal-ion batteries. By allowing VC to remain in the nonaqueous electrolyte solution after conditioning, it is possible to appropriately repair the SEI loss that occurred during charge-discharge cycles, thereby improving charge-discharge cycle durability.

[0068] The nonaqueous electrolyte preferably contains a compound (fused polycyclic heterocyclic compound) having a structure satisfying the following 1 to 5: 1. A fused polycyclic heterocyclic compound; 2. The fused polycyclic heterocyclic compound contains a pyrimidine skeleton; 3. The fused polycyclic heterocyclic compound contains three or more nitrogen atoms; 4. The fused polycyclic heterocyclic compound contains five or more sp2 carbon atoms; and 5. No hydrogen atom is bonded to the nitrogen atom in the fused polycyclic heterocyclic compound. Purine derivatives are preferably used as such fused polycyclic heterocyclic compounds. Here, the purine derivative refers to a compound having a bicyclic heterocycle skeleton in which an imidazole ring is bonded to a pyrimidine skeleton. More preferably, the fused polycyclic heterocyclic compound is represented by the following general formulas (2-1) to (2-12): {wherein R forms a double bond with a C atom in the fused polycyclic heterocycle ２ , R ４ , R ６ represents an oxygen atom or a sulfur atom, and forms a single bond with a C atom in the fused polycyclic heterocycle. ２ , R ４ , R ６ and R bonded to a nitrogen atom in the fused polycyclic heterocycle. １ , R ３ , R ５ , R ７ represents an alkyl group having 1 to 4 carbon atoms, a haloalkyl group having 1 to 4 carbon atoms, an acylalkyl group having 1 to 4 carbon atoms, an allyl group, a propargyl group, a phenyl group, a benzyl group, a pyridyl group, an amino group, a pyrrolidylmethyl group, a trimethylsilyl group, a nitrile group, an acetyl group, a trifluoroacetyl group, a chloromethyl group, a methoxymethyl group, an isocyanomethyl group, a methylsulfonyl group, a 2-(trimethylsilyl)-ethoxycarbonyloxy group, a bis(N,N'-alkyl)aminomethyl group, a bis(N,N'-alkyl)aminoethyl group, an alkoxy group having 1 to 4 carbon atoms, a fluorine-substituted alkoxy group having 1 to 4 carbon atoms, a nitrile group, a nitro group, a halogen atom, a sugar residue, or a heterocyclic residue, provided that R forming a single bond with a carbon atom in the fused polycyclic heterocycle ２ , R ４ , R ６may be a hydrogen atom.} and isomers thereof.

[0069] Among the above formulas, the fused polycyclic heterocyclic compound is preferably at least one selected from the group consisting of compounds represented by formulas (2-2), (2-5), (2-8), and (2-12) and isomers thereof, more preferably a compound represented by formula (2-2), and even more preferably caffeine among the compounds represented by formula (2-2).

[0070] The content of the condensed polycyclic heterocyclic compound in the non-aqueous electrolyte is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, based on the total amount of the non-aqueous electrolyte. The condensed polycyclic heterocyclic compound suppresses the formation of complex cations formed from a transition metal and a nitrile compound. Therefore, a non-aqueous alkali metal ion battery containing the condensed polycyclic heterocyclic compound exhibits excellent load characteristics and suppresses the increase in internal resistance during repeated charge-discharge cycles. Furthermore, the content of the condensed polycyclic heterocyclic compound in the electrolyte is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less, and even more preferably 0.5% by mass or less, based on the total amount of the electrolyte. By adjusting the content of the condensed polycyclic heterocyclic compound within the above-mentioned range, the formation reaction of complex cations on the electrode surface can be suppressed without impairing the basic functions of the non-aqueous alkali metal ion battery, thereby reducing the increase in internal resistance during charge-discharge. By adjusting the electrolyte solution to fall within this range, the cycle performance, high output performance in a low-temperature environment, and all of the other battery characteristics of the resulting nonaqueous alkali metal ion battery can be further improved.

[0071] The non-aqueous electrolyte preferably contains a non-ionic surfactant in a proportion of 0.1% by mass or more and 4.0% by mass or less. Non-aqueous electrolytes containing nitrile compounds have high ionic conductivity, but their polarity is also high, resulting in reduced wettability to polyolefin separators. By including a non-ionic surfactant in the non-aqueous electrolyte, wettability to polyolefin separators can be improved, contributing to improved charge-discharge cycle durability. If the content of the non-ionic surfactant is 0.1% by mass or more, the wettability of the non-aqueous electrolyte to the polyolefin separator is enhanced, and if the content of the non-ionic surfactant is 4.0% by mass or less, the ionic conductivity of the non-aqueous electrolyte can be increased, thereby improving the output characteristics of non-aqueous alkali metal ion batteries.

[0072] Nonionic surfactants are compounds that contain one or more hydrophilic groups and one or more lipophilic groups in one molecule. Surfactants include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. Ionizable surfactants are limited to those that do not inhibit the insertion and desorption of alkali metal ions into the negative electrode. Furthermore, from the viewpoint of solubility in nonaqueous electrolytes, nonionic surfactants are preferred.

[0073] Nonionic surfactants include fatty acid ester compounds such as glycerin fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, and saturated fatty acid esters; ethyl diethyl phosphonoacetate {EDPA; (C ２ H ５ O) ２ (P=O)-CH ２ (C=O)OC ２ H ５}, tris(trifluoroethyl) phosphate {TFEP; (CF ３ CH ２ O) ３ P=O}, triphenyl phosphate {TPP; (C ６ H ５ O) ３ P=O}, triallyl phosphate {CH ２ =CHCH ２ O) ３P═O}, phosphate ester compounds such as triamyl phosphate, tris(2-butoxyethyl) phosphate, and tris(2-ethylhexyl) phosphate; ether compounds such as polyoxyethylene alkyl ethers, polyoxyalkylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polycyclic phenyl ethers, polyoxyethylene distyrenated phenyl ethers, and polyoxyethylene polyoxypropylene glycol; ester ether compounds such as fatty acid polyethylene glycols and polyoxyethylene sorbitan fatty acid esters; and alkanolamide compounds such as fatty acid alkanolamides. From the viewpoint of improving the stability of nonaqueous electrolytes, fatty acid ester compounds or phosphate ester compounds are preferred. Ethyl laurate is preferred as the fatty acid ester compound. Phosphate ester compounds are particularly preferred, and among them, at least one selected from the group consisting of triamyl phosphate, tris(2-butoxyethyl) phosphate, and tris(2-ethylhexyl) phosphate is more preferred, with tris(2-ethylhexyl) phosphate being particularly preferred.

[0074] The number of carbon atoms contained in at least one substituent constituting the hydrophobic portion of the nonionic surfactant is preferably 3 or more, more preferably 5 or more, and even more preferably 8 or more, from the viewpoint of reducing the surface tension of the nonaqueous electrolyte. Furthermore, from the viewpoint that a large number of carbon atoms in the substituent increases the boiling point of the compound and makes purification difficult, the number of carbon atoms contained in the substituent is preferably 25 or less, and even more preferably 20 or less. When the hydrocarbon chain of the substituent is branched, the total number of carbon atoms contained in the substituent is used. Specific examples of substituents having 3 or more carbon atoms include a propyl group, an isopropyl group, a butyl group, an isobutyl group, a s-butyl group, a t-butyl group, an amyl group, an isoamyl group, a s-amyl group, a t-amyl group, a 2-butoxyethyl group, a 2-ethylhexyl group, and a phenyl group.

[0075] Here, the surfactant content is the amount of the non-aqueous electrolyte at room temperature. １ H-NMR measurement (standard material (C ６ F ４ H ２) and calculate the surfactant content from the integrated value of the signal of each detected component).

[0076] <Positive Electrode> The positive electrode has a positive electrode current collector and a positive electrode active material layer provided on one or both surfaces of the positive electrode current collector.

[0077] (Positive Electrode Active Material Layer) The positive electrode active material layer contains a positive electrode active material containing a transition metal oxide, and may further contain optional components such as a conductive filler, a binder, and a dispersion stabilizer, as necessary.

[0078] (Positive electrode active material) The positive electrode active material includes a transition metal oxide capable of absorbing and releasing alkali metal ions. There are no particular limitations on the transition metal oxide used as the positive electrode active material. Examples of the transition metal oxide include oxides containing at least one element selected from the group consisting of cobalt, nickel, manganese, iron, vanadium, and chromium.

[0079] When the alkali metal ion is a lithium ion, specific examples of the transition metal oxide include the following: ｘ CoO ２ , Li ｘ NiO ２ , Li ｘ Ni ｙ M （１－ｙ） O ２ (wherein M is at least one element selected from the group consisting of Co, Mn, Al, Fe, Mg, and Ti, and y satisfies 0.03<y<0.97), Li ｘ MnO ２ , α-Li ｘ FeO ２ , Li ｘ VO ２ , Li ｘ CrO ２ , Li ｘ Mn （１－ｚ） Fe ｚ P.O. ４ (wherein z satisfies 0<z≦1), Li ｘ Mn ２ O ４ , Li ｘ M ｗ Mn （２－ｗ）O ４ (wherein M is at least one element selected from the group consisting of Co, Mn, Al, Fe, Mg, and Ti, and w satisfies 0.03<w<0.97), Li ｘ Ni ａ Co ｂ Al （１－ａ－ｂ） O ２ (wherein a and b satisfy 0.03<a<0.97 and 0.03<b<0.97), Li ｘ Ni ｃ Co ｄ Mn （１－ｃ－ｄ） O ２ (wherein c and d satisfy 0.03<c<0.97 and 0.03<d<0.97, and x satisfies 0≦x≦1), and the like.

[0080] When the alkali metal ion is a sodium ion, specific examples of the positive electrode active material include the following: ｘ M1 ｙ M2 ｚ O ２ (wherein M1 and M2 are each one selected from Fe, Mn, Co, Ni, Ti, Mg, Zn, Te, or Cu, and satisfy the conditions 0.1<y<0.9, 0.1<z<0.9, and 0.95<y+z<1.05), Na ｘ M1 ｃ M2 ｄ M3 （１－ｃ－ｄ） O ２ (wherein M1, M2 and M3 are each one selected from Fe, Mn, Co, Ni, Ti, Mg, Zn, Te or Cu, and c and d satisfy 0.03<c<0.97 and 0.03<d<0.97), Na ｘ M1O ２ (wherein M1 is one selected from Fe, Mn, Co, Ni, Ti, Mg, Zn, Te, or Cu), Na ｘ FePO ４ , Na ｘ (FeSO ４ ) ２ , Na ３ V ２ (P.O. ４ ) ３ , Na ｘ M1 [M2 (CN)６ ] （１－ｙ） ・ ｚ H ２ O (wherein M1 and M2 each represent one selected from Fe, Mn, Co, Ni, Ti, or Cu, satisfying 0≦y≦1.0 and 0≦z≦3.0, and each x independently satisfying 0≦x≦1).

[0081] Specific examples of sodium-containing transition metal oxides include Na ｘ Fe ０．５ Mn ０．５ O ２ , Na ｘ Fe ０．５ Co ０．５ O ２ , Na ｘ Fe ０．５ Ni ０．５ O ２ , Na ｘ Ni ０．５ Mn ０．５ O ２ , and Na ｘ FeO ２ (wherein each x independently satisfies 0≦x≦1), etc.

[0082] When the alkali metal ion is a potassium ion, specific examples of the positive electrode active material include: ｘ M1 ｙ M2 ｚ O ２ (wherein M1 and M2 are each one selected from Fe, Mn, Co, Ni, Ti, Mg, Zn, Te, or Cu, and satisfy the conditions 0.1<y<0.9, 0.1<z<0.9, and 0.95<y+z<1.05), K ｘ FePO ４ , K ｘ (FeSO ４ ) ２ , K ｘ M1 ｃ M2 ｄ M3 （１－ｃ－ｄ） O ２(wherein M1, M2, and M3 each represent one selected from Fe, Mn, Co, Ni, Ti, Mg, Zn, Te, or Cu, and c and d satisfy 0.03<c<0.97 and 0.03<d<0.97), K ｘ M1 [M2 (CN) ６ ] （１－ｙ） ・ ｚ H ２ O (wherein M1 and M2 each represent one selected from Fe, Mn, Co, Ni, Ti, or Cu, satisfying 0≦y≦1.0 and 0≦z≦3.0, and each x independently satisfying 0≦x≦1).

[0083] The average particle diameter of the positive electrode active material is preferably 0.1 to 20 μm. If the average particle diameter of the positive electrode active material is 0.1 μm or more, the density of the active material layer is high, and therefore the capacity per electrode volume tends to be high. If the average particle diameter of the positive electrode active material is small, durability may be reduced, but if the average particle diameter is 0.1 μm or more, durability is less likely to be reduced. If the average particle diameter of the positive electrode active material is 20 μm or less, it tends to be more suitable for high-speed charging and discharging. The average particle diameter of the positive electrode active material is more preferably 0.5 to 15 μm, and even more preferably 1 to 10 μm.

[0084] The average particle diameter of an active material refers to the particle diameter at the point where the cumulative curve is 50% when the particle size distribution is measured using a particle size distribution analyzer and the total volume is taken as 100% (i.e., the 50% diameter (median diameter)). This average particle diameter can be measured using a commercially available laser diffraction particle size distribution analyzer.

[0085] The content of the positive electrode active material in the positive electrode active material layer is preferably 70% by mass or more and 99% by mass or less, based on the total mass of the positive electrode active material layer. The lower limit of the content of the positive electrode active material is more preferably 80% by mass or more, and even more preferably 85% by mass or more. The upper limit of the content of the positive electrode active material is even more preferably 98% by mass or less. By having the content of the positive electrode active material in the positive electrode active material layer be 70% by mass or more and 99% by mass or less, favorable charge / discharge characteristics are exhibited.

[0086] (Positive electrode current collector) A material constituting the positive electrode current collector is preferably a material that has high electronic conductivity and is not easily deteriorated due to elution in the electrolytic solution, reaction with the electrolyte or ions, etc. The positive electrode current collector is preferably a metal foil, more preferably an aluminum foil.

[0087] The metal foil may be a flat metal foil having no irregularities or through holes, or may be a metal foil having irregularities that has been subjected to embossing, chemical etching, electrolytic deposition, blasting, or the like, or may be a metal foil having through holes such as expanded metal, punched metal, or etched foil.

[0088] The thickness of the positive electrode current collector is not limited as long as it can sufficiently maintain the shape and strength of the positive electrode, and is preferably, for example, 1 to 100 μm.

[0089] (Optional Components) The positive electrode active material layer may further contain optional components such as a conductive filler, a binder, and a dispersion stabilizer, as needed.

[0090] Examples of the conductive filler that can be used include acetylene black, ketjen black, vapor-grown carbon fiber, graphite, carbon nanotubes, graphene, and mixtures thereof. The amount of the conductive filler is preferably more than 0 parts by mass and not more than 20 parts by mass, more preferably more than 0 parts by mass and not more than 15 parts by mass, and even more preferably 1 part by mass or more and not more than 10 parts by mass, relative to 100 parts by mass of the positive electrode active material. When the mixed amount is 20 parts by mass or less, the content of the positive electrode active material in the positive electrode active material layer increases, making it easier to ensure the energy density per volume of the positive electrode active material layer.

[0091] Examples of binders that can be used include PVdF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), polyimide, latex, styrene-butadiene copolymer, fluororubber, and acrylic copolymer. The amount of binder is preferably 0 to 20 parts by mass, more preferably 1 to 15 parts by mass, and even more preferably 1 to 10 parts by mass, per 100 parts by mass of the positive electrode active material. If the amount of binder is 0 parts by mass or more, sufficient electrode strength is likely to be achieved. On the other hand, if the amount of binder is 20 parts by mass or less, the ingress and egress of ions into and diffusion from the positive electrode active material are less likely to be hindered, and therefore, high input / output characteristics are likely to be achieved.

[0092] Examples of the dispersion stabilizer that can be used include PVP (polyvinylpyrrolidone), PVA (polyvinyl alcohol), and cellulose derivatives. The amount of binder is preferably more than 0 parts by mass and not more than 10 parts by mass per 100 parts by mass of the positive electrode active material. If the amount of dispersion stabilizer is 10 parts by mass or less, the ingress and egress of ions into and diffusion from the positive electrode active material are less likely to be hindered, and therefore, high input / output characteristics are more likely to be exhibited.

[0093] (Physical Properties of Positive Electrode Active Material Layer) - Thickness - The thickness of the positive electrode active material layer is preferably 20 μm or more and 500 μm or less, more preferably 25 μm or more and 300 μm or less, and even more preferably 30 μm or more and 200 μm or less per side of the positive electrode current collector. If the thickness of the positive electrode active material layer is 20 μm or more, sufficient charge / discharge capacity is easily achieved. If the thickness of the positive electrode active material layer is 500 μm or less, the ion diffusion resistance within the electrode can be maintained low. Therefore, sufficient output characteristics are easily obtained. In addition, the cell volume can be reduced, making it easy to increase the energy density. Note that when the positive electrode current collector has through holes and / or irregularities, the thickness of the positive electrode active material layer refers to the average thickness per side of the portion of the positive electrode current collector that does not have through holes and / or irregularities.

[0094] -Bulk density- The bulk density of the positive electrode active material layer is preferably 1.5 g / cm ３ More preferably, 2.0 g / cm ３ 4.5g / cm or more ３The bulk density of the positive electrode active material layer is 1.5 g / cm or less. ３ If the bulk density of the positive electrode active material layer is 4.5 g / cm or more, a high energy density is easily achieved, and therefore, it is easy to achieve miniaturization of the electricity storage element. ３ If the thickness is equal to or less than this, the electrolyte solution will diffuse sufficiently in the pores in the positive electrode active material layer, and high output characteristics will be easily obtained.

[0095] (Production of Positive Electrode) The positive electrode has a positive electrode active material layer on one or both surfaces of a positive electrode current collector. Typically, the positive electrode active material layer is fixed to one or both surfaces of the positive electrode current collector.

[0096] The positive electrode can be manufactured using known electrode manufacturing techniques for non-aqueous alkali metal ion batteries. For example, a positive electrode active material and other optional components used as needed are dispersed or dissolved in water or an organic solvent (e.g., N-methyl-2-pyrrolidone, etc.) to prepare a slurry coating liquid, which is then applied to one or both sides of a positive electrode current collector to form a coating film, which is then dried to obtain a positive electrode. The resulting positive electrode may be pressed to adjust the film thickness and / or bulk density of the positive electrode active material layer. Alternatively, a method is possible in which the positive electrode active material and other optional components used as needed are dry-mixed without using a solvent, the resulting mixture is press-molded, and then attached to the positive electrode current collector using a conductive adhesive.

[0097] <Negative Electrode> The negative electrode has a negative electrode current collector and a negative electrode active material layer provided on one or both surfaces of the negative electrode current collector.

[0098] (Negative electrode current collector) The material constituting the negative electrode current collector is preferably a material that has high electronic conductivity and is resistant to degradation due to elution in the electrolytic solution and reaction with the electrolyte or ions. The negative electrode current collector is preferably a metal foil, and examples of such metal foils include aluminum foil, copper foil, nickel foil, and stainless steel foil. As the negative electrode current collector in a nonaqueous alkali metal ion battery, copper foil is preferred when the alkali metal ion is lithium ion, and aluminum foil is preferred when the alkali metal ion is sodium ion or potassium ion.

[0099] The metal foil may be a flat metal foil having no irregularities or through holes, or may be a metal foil having irregularities that has been subjected to embossing, chemical etching, electrolytic deposition, blasting, or the like, or may be a metal foil having through holes such as expanded metal, punched metal, or etched foil.

[0100] The thickness of the negative electrode current collector is not limited as long as it can sufficiently maintain the shape and strength of the negative electrode, and is preferably, for example, 1 to 100 μm.

[0101] (Negative Electrode Active Material Layer) The negative electrode active material layer is provided on one or both surfaces of the negative electrode current collector. The negative electrode active material layer contains a negative electrode active material, and may further contain optional components such as a conductive filler, a binder, and a dispersion stabilizer, as necessary.

[0102] (Negative Electrode Active Material) A material capable of absorbing and releasing alkali metal ions can be used as the negative electrode active material. Specifically, the negative electrode active material preferably includes a carbon material as the first negative electrode active material, and preferably includes one or more selected from the group consisting of silicon, silicon compounds, phosphorus, phosphorus compounds, tin, and tin compounds as the second negative electrode active material. The second negative electrode active material can form an alloy with alkali metal ions. Therefore, the second negative electrode active material is also called an "alloy-based active material."

[0103] (First Negative Electrode Active Material: Carbon Material) The negative electrode active material preferably contains a carbon material as the first negative electrode active material. Examples of the carbon material include amorphous or microcrystalline carbon materials, nanocarbons, and crystalline carbon materials. Examples of the amorphous or microcrystalline carbon materials include non-graphitizable carbon materials and graphitizable carbon materials. Examples of the nanocarbons include carbon nanoparticles, fullerenes, and graphene. Examples of the crystalline carbon materials include graphite. Examples of the graphite include artificial graphite, natural graphite, graphitized mesophase carbon spheres, graphite whiskers, and composite carbon materials thereof. Among these carbon materials, from the viewpoint of increasing the capacity of a non-aqueous alkali metal ion battery, when the alkali metal ion is lithium ion or potassium ion, graphite is preferred, and one or more selected from artificial graphite, natural graphite, graphitized mesophase carbon microspheres, graphite whiskers, and composite carbon materials thereof are preferably used. When the alkali metal ion is sodium ion, a non-graphitizable carbon material is preferably used.

[0104] (Second Negative Electrode Active Material: Alloy-Based Active Material) In addition to the first negative electrode active material described above, the negative electrode active material preferably includes, as a second negative electrode active material, one or more selected from the group consisting of silicon, a silicon compound, phosphorus, a phosphorus compound, tin, and a tin compound. In particular, when the alkali metal ion is a lithium ion or a potassium ion, the negative electrode active material preferably includes, as the second negative electrode active material, at least one of silicon and a silicon compound, and when the alkali metal ion is a sodium ion, the negative electrode active material preferably includes at least one of phosphorus and a phosphorus compound. Among these, the silicon compound is preferably a silicon oxide, and is represented by the formula: SiO ｘ {wherein x satisfies 0.01≦x≦2.} The tin compound is preferably a tin oxide, and more preferably tin dioxide (SnO ２ The second negative electrode active material may be in the form of a composite material in which it is combined with carbon or a carbonaceous material.

[0105] In the alloy-based active material that is the second negative electrode active material, the charge-discharge reaction of alkali metal ions proceeds on the high potential side and with gradual potential fluctuations, compared to, for example, graphite or a non-graphitizable carbon material that is the first negative electrode active material.

[0106] (Use ratio of first negative electrode active material and second negative electrode active material) Based on the total mass of the negative electrode active material layer, the ratio of the first negative electrode active material is preferably 70 parts by mass or more and 99 parts by mass or less, more preferably 80 parts by mass or more and 98 parts by mass or less, and even more preferably 85 parts by mass or more and 97 parts by mass or less.

[0107] From the viewpoint of increasing the capacity of the nonaqueous alkali metal ion battery, it is particularly preferable to use graphite as the first negative electrode active material and to set the concentration of the graphite contained in the negative electrode active material layer to the above-mentioned ratio based on the total mass of the negative electrode active material layer.

[0108] The proportion of the second negative electrode active material is preferably 0 parts by mass or more and 30 parts by mass or less, based on the total mass of the negative electrode active material layer. When the second negative electrode active material is in the form of a composite material of an alloy-based material and carbon or a carbonaceous material, the proportion of the second negative electrode active material is calculated based on the mass excluding the carbon or carbonaceous material.

[0109] It is preferable that the first negative electrode active material be contained in the above proportion (e.g., 70 parts by mass or more and 99 parts by mass or less) and the second negative electrode active material be contained in the above proportion (e.g., 0 parts by mass or more and 30 parts by mass or less) based on the total mass of the negative electrode active material layer. If the second negative electrode active material is 0 parts by mass or more, it is easy to make the negative electrode thin, thereby making it easy to increase the energy density of the non-aqueous alkali metal ion battery. In addition, it is easy to suppress a sudden voltage drop at the end of discharge of the non-aqueous alkali metal ion battery. If the second negative electrode active material is 30% or less, the irreversible capacity during the initial charge / discharge of the negative electrode can be reduced, and therefore the amount of lithium compound contained in the positive electrode precursor can be reduced. Therefore, it is easy to increase the energy density of the non-aqueous alkali metal ion battery.

[0110] The total content of the first and second negative electrode active materials in the negative electrode active material layer of the negative electrode is preferably 70 parts by mass or more, more preferably 80 parts by mass or more, based on the total mass of the negative electrode active material layer.

[0111] (Average particle diameter of negative electrode active material) The average particle diameter of the negative electrode active material is preferably 0.1 μm or more and 20 μm or less, with the lower limit being more preferably 0.5 μm or more, even more preferably 1 μm or more, and the upper limit being more preferably 18 μm or less, even more preferably 15 μm or less. If the average particle diameter is 0.1 μm or more, the contact area with the nonaqueous electrolyte increases, making it easier to reduce the resistance of the nonaqueous alkali metal ion battery. If the average particle diameter of the negative electrode active material is 20 μm or less, it is easier to thin the negative electrode active material layer, making it easier to improve the energy density of the nonaqueous alkali metal ion battery. The average particle diameter of the negative electrode active material can be measured in the same manner as the average particle diameter of the positive electrode active material.

[0112] The average particle size of the negative electrode active material can be adjusted by pulverizing it using a wet or dry jet mill with a built-in classifier, an agitator ball mill, etc. The pulverizer is equipped with a centrifugal classifier, and the fine particles pulverized in an inert gas environment such as nitrogen or argon can be collected with a cyclone or a dust collector.

[0113] (Optional Components) The negative electrode active material layer may contain optional components such as a conductive filler, a binder, and a dispersion stabilizer, as needed.

[0114] Examples of the conductive filler include acetylene black, ketjen black, vapor-grown carbon fiber, etc. The amount of the conductive filler is preferably more than 0 parts by mass and not more than 30 parts by mass, more preferably more than 0 parts by mass and not more than 20 parts by mass, and even more preferably more than 0 parts by mass and not more than 15 parts by mass, relative to 100 parts by mass of the negative electrode active material.

[0115] Examples of binders that can be used include PVdF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), polyimide, latex, styrene-butadiene copolymer, fluororubber, acrylic copolymer, polyacrylic acid, and polyglutamic acid. The amount of binder is preferably 1 part by mass or more and 20 parts by mass or less, more preferably 2 parts by mass or more and 15 parts by mass or less, and even more preferably 3 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the negative electrode active material. If the amount of binder is 1 part by mass or more, sufficient electrode strength is easily achieved. If the amount of binder is 20 parts by mass or less, the ingress and egress of alkali metal ions such as lithium ions into and from the negative electrode active material is less likely to be hindered, and therefore, high input / output characteristics are easily achieved.

[0116] Examples of the dispersion stabilizer that can be used include PVP (polyvinylpyrrolidone), PVA (polyvinyl alcohol), and cellulose derivatives. The amount of the binder is preferably 0 to 10 parts by mass per 100 parts by mass of the negative electrode active material. When the amount of the dispersion stabilizer is 10 parts by mass or less, the movement of alkali metal ions such as lithium ions into and out of the negative electrode active material is less likely to be inhibited, and high input / output characteristics are likely to be exhibited.

[0117] (Physical Properties of Negative Electrode Active Material Layer) —Thickness— The thickness of the negative electrode active material layer is preferably 5 μm or more and 500 μm or less per side of the negative electrode current collector. The lower limit of the thickness of the negative electrode active material layer is more preferably 10 μm or more, and even more preferably 20 μm or more. The upper limit of the thickness of the negative electrode active material layer is more preferably 300 μm or less, and even more preferably 200 μm or less. When the thickness of the negative electrode active material layer is 5 μm or more, streaks are less likely to occur when the negative electrode active material layer is applied, and therefore, excellent coatability is likely to be achieved. When the thickness of the negative electrode active material layer is 500 μm or less, a high energy density is likely to be achieved by reducing the cell volume. Note that, when the negative electrode current collector has through holes and / or irregularities, the thickness of the negative electrode active material layer refers to the average thickness of the negative electrode active material layer per side in a portion of the negative electrode current collector that does not have through holes and / or irregularities.

[0118] -Bulk density- The bulk density of the negative electrode active material layer is preferably 0.70 g / cm ３ 2.00g / cm or more３ or less, more preferably 0.80 g / cm ３ 1.70g / cm or more ３ More preferably, 0.90 g / cm ３ 1.60g / cm or more ３ The bulk density of the negative electrode active material layer is 0.70 g / cm or less. ３ If the bulk density of the negative electrode active material layer is 2.00 g / cm or more, sufficient strength can be easily maintained and electrical conductivity between the negative electrode active materials can be easily exhibited. ３ If the thickness is equal to or less than this, pores through which ions can be sufficiently diffused can be easily secured in the negative electrode active material layer.

[0119] (Production of Negative Electrode) The negative electrode has a negative electrode active material layer on one or both sides of a negative electrode current collector. Typically, the negative electrode active material layer is fixed to one or both sides of the negative electrode current collector. Such a negative electrode can be produced in the same manner as the production of a positive electrode, except that the constituent components are appropriately changed depending on the configuration of the negative electrode in the resulting nonaqueous alkali metal ion battery.

[0120] The negative electrode active material layer in which the contents of the first negative electrode active material and the second negative electrode active material are adjusted is produced, for example, through the steps of: selecting a desired material as the first negative electrode active material; selecting a desired material as the second negative electrode active material; and producing a negative electrode using the material selected as the first negative electrode active material and the material selected as the second negative electrode active material in predetermined amounts, each in consideration of the content ratio in the resulting negative electrode active material layer.

[0121] <<Electrode Stack or Electrode Wound Body>> A positive electrode and a negative electrode are generally stacked or wound with a separator interposed therebetween to form an electrode body (electrode stack or electrode wound body) having a positive electrode, a negative electrode, and a separator. In the electrode stack or electrode wound body, one or more positive electrodes and one or more negative electrodes may be used, and it is preferable that one or both of the outermost layers be a negative electrode.

[0122] <Separator> The separator may be a microporous polyethylene film, a microporous polypropylene film, or a nonwoven cellulose paper. A film composed of organic or inorganic fine particles may be laminated on one or both sides of the separator. The separator may also contain organic or inorganic fine particles.

[0123] The thickness of the separator is preferably 5 μm or more and 25 μm or less. When the thickness of the separator is 5 μm or more, self-discharge due to internal micro-short circuits tends to be reduced. When the thickness of the separator is 25 μm or less, the output characteristics of non-aqueous alkali metal ion batteries such as lithium ion secondary batteries tend to be improved.

[0124] The thickness of the film made of organic or inorganic fine particles is preferably 0.1 μm or more and 10 μm or less. When the thickness of the film made of organic or inorganic fine particles is 0.1 μm or more, self-discharge due to internal micro-short circuits tends to be reduced. When the thickness of the film made of organic or inorganic fine particles is 10 μm or less, the output characteristics of non-aqueous alkali metal ion batteries such as lithium ion secondary batteries tend to be improved.

[0125] The separator may contain an organic polymer that swells upon penetration of the non-aqueous electrolyte solution. Alternatively, an organic polymer may be used alone as a separator. The organic polymer preferably has good affinity with the non-aqueous electrolyte solution and gels upon penetration and swelling of the electrolyte solution. Suitable organic polymers include polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, and mixtures thereof, which tend to exhibit high lithium ion conductivity upon gelation.

[0126] The organic polymer can contain the electrolyte solution within the organic polymer, which is preferable from the viewpoint of safety because it has the effect of preventing the electrolyte solution from leaking out of the nonaqueous alkali metal ion battery when the exterior body is damaged.

[0127] One example of the present disclosure is a storage module including the nonaqueous alkali metal ion battery. Such a storage module is fabricated by a conventional method. The storage module can be configured, for example, by connecting multiple nonaqueous alkali metal ion batteries in series or in parallel.

[0128] This energy storage module is preferably incorporated into at least one system selected from the group consisting of a power regeneration assist system, a power load leveling system, an uninterruptible power supply system, a contactless power supply system, an energy harvesting system, an electric vehicle, a plug-in hybrid vehicle, a hybrid vehicle, an electric motorcycle, and a rapid charging system.

[0129] <<Method for Manufacturing a Non-Aqueous Alkali Metal Ion Battery>> A non-aqueous alkali metal ion battery according to one embodiment of the present disclosure can be manufactured by the following method using the above-described positive electrode and negative electrode: The method for manufacturing a non-aqueous alkali metal ion battery includes, in the order described above, (1) housing an electrode assembly including a positive electrode, a negative electrode, and a separator in an outer casing (cell assembly), (2) injecting a non-aqueous electrolyte solution into the outer casing (electrolyte injection), and (3) applying a voltage between the positive electrode and the negative electrode at a temperature of 20°C or higher and 80°C or lower to decompose the non-aqueous electrolyte solution and additives and form a solid electrolyte coating (SEI) on the surfaces of the positive electrode and the negative electrode (conditioning).

[0130] The nonaqueous alkali metal ion battery obtained by the manufacturing method including the above steps (1) to (3) is preferably a nonaqueous alkali metal ion secondary battery, from the viewpoint of significantly exhibiting the effects of the present disclosure.

[0131] In another aspect of the present disclosure, a method for manufacturing a non-aqueous alkali metal ion secondary battery including a positive electrode, a negative electrode, a non-aqueous electrolyte, and a separator is provided. A method for producing a non-aqueous alkali metal ion secondary battery according to another embodiment includes the following steps: an assembling step of assembling a non-aqueous alkali metal ion secondary battery precursor including: a positive electrode having a positive electrode current collector and a positive electrode active material layer provided on one or both surfaces of the positive electrode current collector; a negative electrode having a negative electrode current collector and a negative electrode active material layer provided on one or both surfaces of the negative electrode current collector; a non-aqueous electrolyte solution containing 5% by volume to 95% by volume of a nitrile compound represented by the formula: R-CN (wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms), as a non-aqueous solvent, and vinylene carbonate; and a first charge / discharge step of subjecting the non-aqueous alkali metal ion secondary battery precursor to a first charge / discharge, wherein a solid electrolyte interface (SEI) coating layer on the surface of the negative electrode active material included in the negative electrode active material layer has the following profile: In a profile analysis of the SEI coating layer on the surface of the negative electrode by X-ray photoelectron spectroscopy (XPS) in the depth direction, when the detection rate of C1s (elemental carbon) in the region where the sputtering time is 5 minutes or more and 20 minutes or less is X1 (atomic % / min), and the detection rate of C1s (elemental carbon) in the region where the sputtering time is 30 minutes or more and 50 minutes or less is X2 (atomic % / min), X1 > 0 and X2 > 0, and 0.25 < (X1 - X2) < 2.75; the initial charge / discharge process includes at least two successive initial charge processes, and the charge rate in each process is 0.01 mA / cm ２ ~4.00mA / cm ２ The charging rate in the second stage is higher than that in the first stage, the charging temperature in each stage is in the range of 25°C to 40°C, and the charging temperature in the second stage is 10°C to 15°C higher than that in the first stage.

[0132] Common or preferred configurations or steps in the method for producing a nonaqueous alkali metal ion battery including the above steps (1) to (3) and the method for producing a nonaqueous alkali metal ion secondary battery according to another embodiment will be described below.

[0133] <Cell Assembly> An electrode assembly is constructed using the above-described positive electrode, negative electrode, and separator. In assembling the electrode assembly, a positive electrode terminal and a negative electrode terminal are connected to a laminate formed by stacking the positive electrode and negative electrode cut into sheet shapes with a separator interposed therebetween to produce an electrode laminate. Alternatively, a positive electrode terminal and a negative electrode terminal are connected to a wound body formed by winding the positive electrode and negative electrode with a separator interposed therebetween to produce an electrode wound body. The shape of the electrode wound body may be cylindrical or flat.

[0134] The positive electrode terminal and the negative electrode terminal can be connected by, for example, resistance welding, ultrasonic welding, laser welding, or the like.

[0135] <Storage in Exterior Body> As the exterior body, a metal can, a laminated packaging material, etc. As the metal can, one made of aluminum is preferred.

[0136] <Injection of Electrolyte Solution, Fabrication of Non-Aqueous Alkali Metal Ion Battery> After assembly, a non-aqueous electrolyte solution is injected into the electrode body housed in the outer casing. After the injection, it is desirable to further impregnate the electrode body, so that the positive electrode, negative electrode, and separator are thoroughly soaked with the non-aqueous electrolyte solution. After the electrolyte solution is injected, the electrode stack is sealed while reducing the pressure while the outer casing is open, thereby producing a non-aqueous alkali metal ion battery or its precursor. In this case, it is preferable that the ratio A1 / B, where A1 (g) is the total mass of the negative electrode active material and B (g) is the mass of the non-aqueous electrolyte, is 0.1 or more and 0.8 or less. When A1 / B is 0.1 or more, excessive SEI formation on the surface of the negative electrode active material can be suppressed, thereby enabling high output. When A1 / B is 0.8 or less, SEI can be formed evenly on the surface of the negative electrode active material, improving charge / discharge cycle durability. Furthermore, it is preferable that the ratio A2 / B of the total mass A2 (g) of the positive electrode active material to the mass B (g) of the nonaqueous electrolyte is 0.2 or more and 1.2 or less. If A2 / B is 0.2 or more, excessive SEI formation on the surface of the positive electrode active material can be suppressed, thereby enabling high output. If A2 / B is 1.2 or less, SEI can be formed evenly on the surface of the positive electrode active material, improving charge / discharge cycle durability.

[0137] <Conditioning> Next, a conditioning step can be performed at a temperature of 20°C or higher and 80°C or lower. The conditioning step includes an initial charge / discharge step in which the nonaqueous alkali metal ion secondary battery precursor is subjected to an initial charge and an initial discharge. It is preferable to apply a voltage to the positive electrode and the negative electrode to decompose the solvent and additives in the nonaqueous electrolyte solution, thereby forming an SEI on the surfaces of the positive electrode and the negative electrode. From the viewpoint of producing a nonaqueous alkali metal ion battery or adjusting the concentration gradient of various components of the electrode SEI, which will be described later, to a predetermined state, for example, it is preferable to divide the conditioning into multiple stages, more preferably into at least two stages, and even more preferably to include at least two consecutive initial charge stages. Furthermore, in the multi-stage conditioning, it is preferable that the current rate during charging is different for each stage, and / or the conditioning temperature is different for each stage. In addition, when the initial charging process includes two consecutive stages, it is preferable that the current rate during charging is different for each stage and / or that the temperature is different for each stage. Furthermore, it is preferable that the charging rate in each stage of the conditioning or initial charging includes a step in which the rate in the later stage is higher than the rate in the previous stage, and at least one or both of the stages includes a step in which the charging rate is 0.01 mA / cm. ２ ~4.00mA / cm ２ Preferably, the conditioning temperature or initial charging temperature in each stage includes a step in which the temperature in the later stage is higher than the temperature in the previous stage, and at least one or both of the steps is preferably in the range of 25°C to 40°C. Preferably, the temperature in the second step is 10°C to 15°C higher than the temperature in the first step.

[0138] Specifically, two-stage charging is performed during the initial charge, and the C-rate and temperature can be changed between the first and second charging steps. This allows for a favorable SEI-forming reaction between the nonaqueous electrolyte and the active material (e.g., graphite, etc.), and the inclusion of preferred elemental components according to the SEI depth promotes the solvation and desolvation processes of alkali metal ions (e.g., Li, Na, K ions, etc.) at the electrolyte-SEI interface and promotes the insertion and desorption processes of alkali metal ions at the active material-SEI interface, thereby forming a strong SEI coating layer that can suppress decomposition of the nitrile compound, and improving the input / output characteristics of the nonaqueous alkali metal ion battery.

[0139] Nitrile compounds are highly Lewis basic and are thought to promote the elution of transition metals in the positive electrode active material. Forming a strong SEI on the surface of the positive electrode active material is thought to inhibit direct contact between the nitrile compound and the positive electrode active material, thereby suppressing the elution of transition metals. On the other hand, such an SEI is also thought to act as a barrier to ionic conduction between the nonaqueous electrolyte and the positive electrode active material. In other words, forming a strong SEI on the surface of the positive electrode active material can suppress the elution of transition metals and improve the charge-discharge cycle characteristics of nonaqueous alkali metal ion batteries. However, the strong SEI inhibits the intercalation and deintercalation reaction of alkali metal ions at the interface between the positive electrode active material and the SEI, resulting in a decrease in the output characteristics of nonaqueous alkali metal ion batteries.

[0140] Furthermore, nitrile compounds have a lower LUMO level than carbonate compounds commonly used as non-aqueous electrolytes in non-aqueous alkali metal ion batteries, making them more susceptible to reduction reactions. Therefore, it is believed that forming a strong SEI on the surface of the negative electrode active material can inhibit direct contact between the nitrile compound and the negative electrode active material, thereby suppressing reductive decomposition of the nitrile compound. On the other hand, it is believed that such an SEI acts as a barrier to ionic conduction between the non-aqueous electrolyte and the negative electrode active material, just like the positive electrode. In other words, forming a strong SEI on the surface of the negative electrode active material can suppress the reduction reaction of the nitrile compound and improve the charge / discharge cycle characteristics of non-aqueous alkali metal ion batteries. However, the tradeoff is that the strong SEI inhibits the intercalation and deintercalation reaction of lithium ions at the interface between the negative electrode active material and the SEI, thereby reducing the output characteristics of the non-aqueous alkali metal ion battery.

[0141] <Negative Electrode SEI Structure: Carbon Component> Regarding the structure of the SEI formed on the surface of the negative electrode, when a depth profile analysis of the SEI on the surface of the negative electrode by X-ray photoelectron spectroscopy (XPS) is performed, where X1 (atomic % / min) is the detection rate of C1s (elemental carbon) in a region where the sputtering time is 5 minutes or more and 20 minutes or less, and X2 (atomic % / min) is the detection rate of C1s (elemental carbon) in a region where the sputtering time is 30 minutes or more and 50 minutes or less, satisfying X1 > 0 and X2 > 0 and 0.25 < (X1 - X2) < 2.75 makes it possible to suppress the reduction reaction of the nitrile compound on the surface of the negative electrode active material without inhibiting ionic conduction at the interface between the nonaqueous electrolyte solution and the negative electrode SEI, and at the interface between the negative electrode SEI and the negative electrode active material. As a result, non-aqueous alkali metal ion batteries containing a nitrile compound as a solvent for a non-aqueous electrolyte solution can achieve both high charge / discharge cycle characteristics and high output characteristics. X1 > 0 and X2 > 0 mean that in the SEI configuration, the carbon component increases as one progresses deeper into the SEI (near the interface with the negative electrode active material), and the configuration approaches the components of carbon materials such as graphite, which are the negative electrode active material. Furthermore, 0.25 < (X1 - X2) < 2.75, i.e., X1 > X2, means that the structural change at the interface between the negative electrode SEI and the negative electrode active material is small, and the energy barrier when alkali metal ions move across this interface is small. In other words, it is thought that the intercalation / deintercalation reaction at the interface between the negative electrode active material and the SEI is promoted. The negative electrode SEI can be formed, for example, on the surface of the negative electrode current collector, the surface of the negative electrode active material layer, the surface of the negative electrode active material contained in the negative electrode active material layer, or the like, as long as a depth profile analysis of the SEI on the negative electrode surface can be performed, and it is preferable that it is formed at least on the surface of the negative electrode active material.

[0142] With respect to X1 and X2, it is preferable that 0.35<X1<2.85 and 0.10<X2<0.80 are satisfied, more preferably 0.40<X1<2.70 and 0.15<X2<0.70 are satisfied, further preferably 0.45<X1<2.50 and 0.20<X2<0.60 are satisfied, and further preferably 1.00<X1<2.40 and 0.25<X2<0.50 are satisfied. By adjusting the carbon component in the negative electrode SEI within the above ranges, it is thought that the ionic conductivity of the alkali metal ions in the SEI can be increased, and the energy barrier of the solvation / desolvation reaction of the alkali metal ions at the interface between the nonaqueous electrolyte and the negative electrode SEI can be reduced, and the energy barrier of the de-insertion reaction of the alkali metal ions at the interface between the negative electrode active material and the negative electrode SEI can be reduced.

[0143] Furthermore, in the depth profile analysis of the SEI on the negative electrode surface by XPS, it is preferable that the detection ratio X3 of C1s (carbon element) at a sputtering time of 10 minutes is 57.5 atomic% or more and 90.5 atomic% or less. If the detection ratio X3 of C1s (carbon element) at a sputtering time of 10 minutes is 57.5 atomic% or more, the structural change at the interface between the SEI and the negative electrode active material is reduced, and the energy barrier when alkali metal ions move across this interface is reduced. In other words, it is thought that the intercalation / deintercalation reaction at the interface between the negative electrode active material and the SEI is promoted. If the detection ratio X3 of C1s (carbon element) at a sputtering time of 10 minutes is 90.5 atomic% or less, the structural change at the interface between the SEI and the non-aqueous electrolyte is reduced. In other words, it is thought that the energy barrier for the solvation / desolvation reaction of alkali metal ions at the interface between the non-aqueous electrolyte and the SEI is reduced.

[0144] <Negative Electrode SEI Structure: Oxygen Component> Regarding the structure of the SEI formed on the surface of the negative electrode, when a depth profile analysis of the SEI on the surface of the negative electrode by X-ray photoelectron spectroscopy (XPS) is performed, the detection rate of O1s (oxygen element) in a region where the sputtering time is 5 minutes or more and 20 minutes or less is Y1 (atomic % / min), and the detection rate of O1s (oxygen element) in a region where the sputtering time is 30 minutes or more and 50 minutes or less is Y2 (atomic % / min), by satisfying Y1 < 0 and Y2 < 0 and -1.50 < (Y1 - Y2) < -0.12, the reduction reaction of the nitrile compound on the surface of the negative electrode active material can be suppressed without inhibiting ionic conduction at the interface between the nonaqueous electrolyte solution and the negative electrode SEI, and at the interface between the negative electrode SEI and the negative electrode active material. As a result, non-aqueous alkali metal ion batteries containing a nitrile compound as a solvent for a non-aqueous electrolyte solution can achieve both high charge / discharge cycle characteristics and high output characteristics. Y1<0 and Y2<0 mean that in the SEI configuration, the oxygen component is high in the shallow portion of the SEI (near the interface with the non-aqueous electrolyte solution) and decreases toward the depth. In other words, the SEI near the surface is structured similarly to the components of a highly polar non-aqueous electrolyte solution. Furthermore, -1.50<(Y1-Y2)<-0.12, i.e., Y1<Y2, means that the structural change at the interface between the SEI and the non-aqueous electrolyte solution is small, reducing the barrier to interfacial migration of alkali metal ions. In other words, it is believed that the solvation / desolvation process of alkali metal ions at the interface between the non-aqueous electrolyte solution and the SEI is promoted.

[0145] With respect to Y1 and Y2, it is preferable that −1.50<Y1<−0.14 and −0.15<Y2<−0.02, it is more preferable that −1.40<Y1<−0.20 and −0.13<Y2<−0.03, and it is even more preferable that −1.30<Y1<−0.30 and −0.11<Y2<−0.04.

[0146] Furthermore, in the depth profile analysis of the SEI on the negative electrode surface by XPS, it is preferable that the detection ratio Y3 of O1s (oxygen element) at a sputtering time of 10 minutes is 3.8 atomic% or more and 25.5 atomic% or less. If the detection ratio Y3 of O1s (oxygen element) at a sputtering time of 10 minutes is 3.8 atomic% or more, it means that the SEI contains a large number of oxygen atoms, and it is thought that the ionic conductivity of the alkali metal ions in the SEI is increased. If the detection ratio Y3 of O1s (oxygen element) at a sputtering time of 10 minutes is 25.5 atomic% or less, the structural change at the interface between the SEI and the non-aqueous electrolyte solution is reduced, that is, it is thought that the energy barrier of the solvation / desolvation process of the alkali metal ions at the interface between the non-aqueous electrolyte solution and the SEI is reduced.

[0147] <Negative Electrode SEI Structure: Alkali Metal Ion Component> Regarding the structure of the SEI formed on the negative electrode surface, when a depth profile analysis of the SEI on the negative electrode surface by X-ray photoelectron spectroscopy (XPS) was performed, the detection rate of one alkali metal element selected from Li, Na, and K in a sputtering time range of 5 minutes to 20 minutes was Z1 (atomic % / min), and the detection rate of one alkali metal element selected from Li, Na, and K in a sputtering time range of 30 minutes to 50 minutes was Z2 (atomic % / min), and by satisfying Z1 < 0 and Z2 < 0 and -1.95 < (Z1 - Z2) < -0.11, it is possible to suppress the reduction reaction of the nitrile compound on the surface of the negative electrode active material without inhibiting ionic conduction at the interface between the nonaqueous electrolyte solution and the negative electrode SEI and the interface between the negative electrode SEI and the negative electrode active material. As a result, a non-aqueous alkali metal ion battery containing a nitrile compound as a solvent for a non-aqueous electrolyte solution can achieve both high charge / discharge cycle characteristics and high output characteristics. Z1<0 and Z2<0 mean that in the SEI configuration, the concentration of alkali metal ions is high in the shallow part of the SEI (near the interface with the non-aqueous electrolyte solution) and decreases toward the depth. In other words, since the concentration of alkali metal ions is high near the SEI surface, solvation / desolvation reactions of alkali metal ions at the interface between the SEI and the non-aqueous electrolyte solution are likely to proceed, and the energy barrier related to ion conduction of alkali metal ions at this interface is thought to be reduced. Furthermore, the relationship -1.95<(Z1-Z2)<-0.11, i.e., Z1<Z2, is believed to increase the concentration of alkali metal ions near the SEI / non-aqueous electrolyte interface, lowering the energy barrier associated with solvation / desolvation, and to form a strong SEI deep within the SEI, thereby suppressing contact between the nitrile compound in the non-aqueous electrolyte and the negative electrode active material. In other words, it is possible to achieve both enhanced ionic conductivity of alkali metal ions to improve the output characteristics of non-aqueous alkali metal ion batteries and suppressed decomposition of the non-aqueous electrolyte, thereby achieving high charge / discharge cycle durability.Furthermore, with respect to Z1 and Z2, it is preferable that −2.20<Z1<−0.15 and −0.28<Z2<−0.05, and it is more preferable that −2.10<Z1<−0.18 and −0.27<Z2<−0.06.

[0148] Furthermore, in the depth profile analysis of the SEI on the negative electrode surface by the above-mentioned XPS, the detection ratio Z3 of the alkali metal element (lithium element if the non-aqueous alkali metal ion battery is a lithium ion battery, sodium element if the non-aqueous alkali metal ion battery, and potassium element if the non-aqueous alkali metal ion battery) at a sputtering time of 10 minutes is preferably 5.0 atomic% or more and 18.0 atomic% or less. If the detection ratio Z3 of the alkali metal element at a sputtering time of 10 minutes is 5.0 atomic% or more, this means that the SEI contains a large amount of alkali metal ions, and it is thought that the ionic conductivity of the alkali metal ions in the SEI is increased. If the detection ratio of the alkali metal element at a sputtering time of 10 minutes is 18.0 atomic% or less, a strong SEI is formed, which is thought to suppress the reduction reaction of the nitrile compound in the non-aqueous electrolyte and improve charge / discharge cycle durability.

[0149] <Structure of Non-Facing Negative Electrode SEI: Alkali Metal Ion Component> As described above, by stacking or winding a positive electrode and a negative electrode to form an electrode assembly, it is possible to increase the size of a non-aqueous alkali metal ion battery. In this case, when double-sided electrodes in which active material layers are coated on both sides of the current collectors of the positive and negative electrodes are used, the outermost layer of the electrode laminate or electrode wound assembly is a negative electrode active material layer that does not face the positive electrode active material layer (non-facing negative electrode active material layer), or a positive electrode active material layer that does not face the negative electrode active material layer (non-facing positive electrode active material layer). If the non-facing positive electrode active material layer is used as the outermost layer, the capacity of the positive electrode will be excessive relative to the capacity of the negative electrode, which may result in the deposition of alkali metal on the negative electrode. Therefore, it is preferable to form the electrode laminate or electrode wound assembly so that the outermost layer is a non-facing negative electrode active material layer, i.e., so that the outermost layer is a double-sided negative electrode.

[0150] On the other hand, when the outermost layer is a double-sided negative electrode, the non-opposing negative electrode active material layer does not directly participate in the charge and discharge of the battery because it does not face the positive electrode active material layer. However, the non-aqueous electrolyte may react with the non-opposing negative electrode active material layer, resulting in gas generation, etc. In this case, by controlling the state of the SEI in the non-opposing negative electrode active material layer, decomposition of the non-aqueous electrolyte can be suppressed, thereby suppressing gas generation, and by suppressing the potential increase of the outermost negative electrode, metal elution from the negative electrode current collector can be suppressed. Specifically, in a negative electrode disposed in the outermost layer of the electrode assembly, X-ray photoelectron spectroscopy (XPS) profile analysis of the depth direction of the SEI on the non-opposing negative electrode surface showed that the sputtering time was 5 minutes to 20 minutes. When the average relative element concentration of one alkali metal element selected from Li, Na, and K in the following region is V1 (atomic %), and the average relative element concentration of one alkali metal element selected from Li, Na, and K on the negative electrode surface facing the positive electrode is V2 (atomic %), it is preferable that 0.55 < (V1 / V2) < 0.95. A V1 / V2 ratio greater than 0.55 indicates a small potential gap between the non-countered negative electrode active material layer and the counter negative electrode active material layer on its back surface, and is thought to be able to suppress metal elution from the negative electrode current collector by suppressing a potential increase of the non-countered negative electrode. A V1 / V2 ratio less than 0.95 indicates a low alkali metal ion concentration in the non-countered negative electrode active material layer, and is thought to be able to suppress decomposition of the non-aqueous electrolyte on the non-countered negative electrode active material layer.

[0151] <Structure of Non-Facing Negative Electrode SEI: Carbon Component> In an X-ray photoelectron spectroscopy (XPS) profile analysis of the SEI on the non-facing negative electrode surface in the negative electrode disposed on the outermost layer of the electrode assembly, when the average relative elemental concentration of C1s (carbon element) in the region where the sputtering time is 5 minutes or more and 20 minutes or less is W1 (atomic %) and the average relative elemental concentration of C1s (carbon element) on the negative electrode surface facing the positive electrode in the region where the sputtering time is 5 minutes or more and 20 minutes or less is W2 (atomic %), it is preferable that 1.05 < (W1 / W2) < 1.25. A W1 / W2 ratio of greater than 1.05 indicates that excessive SEI formation on the non-facing negative electrode active material layer can be suppressed, and it is thought that gas generation due to thermal decomposition of the SEI can be suppressed. When W1 / W2 is smaller than 1.25, it can be determined that a strong SEI is formed on the non-opposing negative electrode active material layer, and it is considered that decomposition of the non-aqueous electrolyte solution on the non-opposing negative electrode active material layer can be suppressed. From this viewpoint, it is more preferable that W1 / W2 satisfies the relationship 1.06≦(W1 / W2)≦1.24.

[0152] <Surface structure of positive electrode SEI: sulfur component> In order to suppress metal elution from the transition metal oxide in the positive electrode, XPS analysis of the positive electrode surface shows peaks attributable to S2p (elemental sulfur) in the binding energy regions of 166 eV to 172 eV and 162 eV to 166 eV, respectively. When the relative element concentration Cs1 (atomic%) of S2p with a binding energy of 166 eV to 172 eV and the relative element concentration Cs2 (atomic%) of S2p with a binding energy of 162 eV to 166 eV are 0.50≦Cs1 / Cs2≦0.95, and more preferably 0.50<Cs1 / Cs2<0.95. The peak (Cs1) with a binding energy of 166 eV to 172 eV in the S2p spectrum corresponds to oxidized sulfur, and -S(═O) ２ - bonds, -O-S(=O)-O- bonds, etc. ２ F) ２ and LiN (SO ２ CF ３ ) ２On the other hand, the peak (Cs2) in the S2p spectrum with a binding energy of 162 eV to 166 eV is sulfur in a reduced state, and is not sulfur or Li. ２ S corresponds to this. In this way, by using oxidized and reduced sulfur elements as a protective coating on the positive electrode surface, a dense and strong SEI can be formed on the positive electrode surface, and it is thought that by suppressing contact between the nitrile compound and the positive electrode active material, metal elution from the positive electrode surface can be suppressed. From the same viewpoint as above, in XPS analysis of the positive electrode surface, Cs1 is preferably 0.30 or more and 1.10 or less, and / or Cs2 is preferably 0.50 or more and 1.20 or less.

[0153] <Internal structure of positive electrode SEI: sulfur component> In order to suppress metal elution from the transition metal oxide in the positive electrode and to increase the ionic conductivity of alkali metal ions in the positive electrode SEI, a sputtering time of 2 to 10 minutes was used in an X-ray photoelectron spectroscopy (XPS) profile analysis of the SEI on the positive electrode surface in the depth direction. When the average relative element concentration of S2p (sulfur element) with a binding energy of 166 eV or more and 172 eV or less is Ci1 (atomic %) and the average relative element concentration of S2p (sulfur element) with a binding energy of 162 eV or more and 166 eV or less is Ci2 (atomic %), it is preferable that Ci1 be 0.04 < Ci1 < 0.50 and 0.10 < Ci2 < 0.8, it is more preferable that 0.05 ≦ Ci1 ≦ 0.40 and 0.20 ≦ Ci2 ≦ 0.75, and / or it is preferable that 0.13 < (Ci1 / Ci2) < 0.88.

[0154] If 0.13<(Ci1 / Ci2), there is a large amount of oxidized sulfur in the positive electrode SEI, that is, there is a large amount of sulfur in the state of being bonded to oxygen (for example, -S(=O) ２ The nitrile compound is a sulfur compound containing a -O-S(=O)-O- bond and a -O-S(=O)-O- bond, which is thought to increase the ionic conductivity of alkali metal ions in the positive electrode SEI. If (Ci1 / Ci2) is less than 0.88, the amount of reduced sulfur components is high, forming a dense SEI structure that is thought to suppress contact between the nitrile compound and the positive electrode active material and to suppress metal elution from the positive electrode.

[0155] <Internal Structure of Positive Electrode SEI: Fluorine Component> Regarding the structure of the SEI formed on the positive electrode surface, in a depth profile analysis of the SEI on the positive electrode surface by X-ray photoelectron spectroscopy (XPS), when the detection rate of F1s (elemental fluorine) with a binding energy of 686 eV to 690 eV in a region where the sputtering time is 2 minutes to 10 minutes is defined as D1 (atomic % / min), and the detection rate of F1s (elemental fluorine) with a binding energy of 683 eV to 686 eV in a region where the sputtering time is 2 minutes to 10 minutes is defined as D2 (atomic % / min), by satisfying D1 < 0 and D2 > 0 and -2.00 < (D1 / D2) < -1.00, metal elution from the surface of the positive electrode active material can be suppressed without inhibiting ionic conduction at the interface between the nonaqueous electrolyte solution and the positive electrode SEI, and at the interface between the positive electrode SEI and the positive electrode active material. As a result, a non-aqueous alkali metal ion battery containing a nitrile compound as a solvent for a non-aqueous electrolyte solution can achieve both high charge / discharge cycle characteristics and high output characteristics.

[0156] The F1s peak with binding energy between 686 eV and 690 eV is LiPF ６ LiFSI, NaPF ６ , KPF ６ The peaks of fluorine derived from alkali metal electrolytes such as those mentioned above correspond to the peaks of fluorine, and the peaks of F1s from 683 eV to 686 eV correspond to ionic inorganic compounds such as LiF, NaF, and KF. D1<0 means that in the configuration of the SEI, in the shallow part of the SEI (near the interface with the non-aqueous electrolyte), there are many components containing highly dissociable alkali metal ions, and this component decreases as you move deeper. In other words, this means that the configuration near the surface of the SEI is close to the components of a highly polar non-aqueous electrolyte, and the ionic conductivity of the non-aqueous electrolyte and the positive electrode SEI interface can be increased. In this case, D1 is preferably -0.45<D1<-0.20.

[0157] Furthermore, D2 > 0 indicates that in the SEI configuration, the deeper into the SEI, the more components with low ionic dissociation properties of alkali metal ions are present. The proportion of this low-reactivity ionic inorganic compound is increased in the positive electrode SEI near the positive electrode active material, and by suppressing contact between the nitrile compound and the positive electrode active material, metal elution from the positive electrode active material surface can be suppressed. In this case, D2 is preferably 0.15 < D2 < 0.30. Furthermore, by satisfying -2.00 < (D1 / D2), metal elution from the positive electrode surface can be suppressed, and by satisfying (D1 / D2) < -1.00, the ionic conductivity of the interface between the nonaqueous electrolyte and the positive electrode SEI can be increased.

[0158] <<Capacity per unit area of ​​positive electrode and negative electrode>> The capacity per unit area of ​​the negative electrode is defined as N (mAh / cm ２ ), the capacity per unit area of ​​the positive electrode is P (mAh / cm ２ ), it is preferable to adjust the capacities of the positive and negative electrodes so that 1.11≦N / P≦1.35, more preferably 1.12≦N / P≦1.30, and even more preferably 1.13≦N / P≦1.25. In non-aqueous alkali metal ion batteries containing a nitrile compound as a solvent in the non-aqueous electrolyte, in order to suppress the reduction reaction of the nitrile compound on the surface of the negative electrode active material, a solvent or additive other than the nitrile compound in the non-aqueous electrolyte must be reacted on the surface of the negative electrode active material to form a strong SEI in the initial stage of the conditioning. Therefore, compared to non-aqueous alkali metal ion batteries not containing a nitrile compound in the non-aqueous electrolyte, the charge capacity to the negative electrode increases during the initial charge, and lithium dendrites may form on the surface of the negative electrode. In this case, an N / P ratio of 1.11 or higher means that the amount of lithium ions that can rapidly increase at the negative electrode increases, thereby suppressing the formation of lithium dendrites during the initial charge. If N / P is 1.35 or less, the capacity imbalance between the positive electrode and the negative electrode can be reduced, and the capacity decrease and gas generation during charge / discharge cycles can be suppressed.

[0159] <<Measurement of N and P>> Capacity per unit area of ​​negative electrode N (mAh / cm ２), and the capacity per unit area of ​​the positive electrode P (mAh / cm ２ The negative electrode and the positive electrode are placed on a surface having a certain area (S (cm ２ )) is used as the working electrode, metallic lithium is used as the counter electrode and reference electrode, and a non-aqueous solvent containing a lithium salt (for example, a non-aqueous solvent in which ethylene carbonate and ethyl methyl carbonate are mixed in a volume ratio of 1:2) is used as the electrolyte. ６ An electrochemical cell (half cell) is prepared using a non-aqueous electrolyte solution in which the above-mentioned compound is dissolved to a concentration of 1.0 mol / L. The negative electrode half cell is charged and discharged at a current value of 0.50 mA / cm in a 25°C environment using a charge / discharge device. ２ After constant current discharge was performed until the voltage value reached 0.01 V, the current value was increased to 0.01 mA / cm ２ The constant voltage discharge is performed until the total discharge capacity reaches the value Q. Ｎ (mAh), and Q Ｎ / S to obtain the capacity per unit area of ​​the negative electrode N (mAh / cm ２ For the positive electrode half cell, a charge / discharge device was used in an environment of 25°C, with a current value of 0.50 mA / cm ２ The voltage value is fully charged (for example, LiFePO ４ When LiCoO ２ , LiNi ａ Co ｂ Al （１－ａ－ｂ） O ２ (wherein a and b satisfy 0.03<a<0.97 and 0.03<b<0.97), LiNi ｃ Co ｄ Mn （１－ｃ－ｄ） O ２ (wherein c and d satisfy 0.03<c<0.97 and 0.03<d<0.97), LiMn （１－ｚ） Fe ｚ P.O. ４ (where z satisfies 0<z≦1) is used, the voltage is 4.2 V. After constant current charging was performed until the voltage reached 0.01 mA / cm ２ The constant voltage charge is performed until the battery reaches the capacity. The sum of the charge capacity during constant current charge and constant voltage charge is Q Ｐ(mAh), and Q Ｐ / S to the capacity per unit area of ​​the positive electrode P (mAh / cm ２ ) can be calculated.

[0160] Examples and comparative examples of the present invention will be described below, but the present invention is not limited to these examples and comparative examples.

[0161] <Production and Evaluation of Positive Electrode> LiFePO was used as the positive electrode active material. ４ 94.0 parts by mass of the powder, 3.0 parts by mass of acetylene black as a conductive filler, 3.0 parts by mass of PVdF (polyvinylidene fluoride) as a binder, and NMP (N-methylpyrrolidone) as an organic solvent were mixed to obtain a positive electrode slurry with a solids concentration of 45% by mass. The obtained positive electrode slurry was applied to both sides of a 15 μm thick aluminum foil as a positive electrode current collector, dried, and pressed to obtain a positive electrode 1. The thickness of the positive electrode active material layer of the positive electrode 1 was 65 μm per side, and the basis weight of the positive electrode active material layer per side was 145 g / m ２ The bulk density of the positive electrode active material layer was 2.23 g / cm ３ It was.

[0162] <Production and Evaluation of Negative Electrode> 97.0 parts by mass of artificial graphite as the negative electrode active material, 3.0 parts by mass of PVdF (polyvinylidene fluoride) as a binder, and NMP (N-methylpyrrolidone) were mixed to obtain a negative electrode slurry. The obtained negative electrode slurry was applied to both sides of a 10 μm-thick electrolytic copper foil as a negative electrode current collector, dried, and pressed to obtain a negative electrode 1. The thickness of the negative electrode active material layer per side of the obtained negative electrode 1 was 61 μm, and the basis weight of the negative electrode active material layer was 74 g / m ２ and the bulk density is 1.21 g / cm ３ It was.

[0163] <Measurement of N / P> The negative electrode half-cell using the negative electrode 1 and the positive electrode half-cell using the positive electrode 1 were each measured by the method described above, and the N / P was found to be 1.19.

[0164] <Preparation of Non-Aqueous Electrolyte Solution> Various non-aqueous solvents and various additives were mixed in an inert atmosphere so as to give predetermined concentrations, and various lithium salts were further added thereto so as to give predetermined concentrations, thereby preparing non-aqueous electrolyte solutions.

[0165] The abbreviations for the lithium salt, non-aqueous solvent, and additives in Table 1 have the following meanings. The parts by mass of the additives in Table 1 indicate the parts by mass relative to 100 parts by mass of the non-aqueous electrolyte excluding the additives. (Lithium salt) LiPF ６ : Lithium hexafluorophosphate LiFSI: Lithium bis(fluorosulfonyl)imide (non-aqueous solvent) AcN: Acetonitrile EMC: Ethyl methyl carbonate EC: Ethylene carbonate ES: Ethylene sulfite VC: Vinylene carbonate PN: Propionitrile (additive) SAH: Succinic anhydride PD: Pyridine CAF: 1,3,7-trimethylxanthine (caffeine) TOP: Tris(2-ethylhexyl) phosphate

[0166]

[0167] Example 1 <Production of a Non-Aqueous Alkali Metal Ion Battery> The positive electrode 1 was cut into 10 pieces measuring 3.0 cm x 5.0 cm, and the negative electrode 1 was cut into 11 pieces measuring 3.1 cm x 5.1 cm. A 15 μm thick microporous membrane was used as a separator, and the negative electrode 1, separator, positive electrode 1, separator, and negative electrode 1 were stacked in this order, with the negative electrode 1 being the outermost layer. A negative electrode terminal and a positive electrode terminal were then connected to the negative electrode 1 and positive electrode 1, respectively, by ultrasonic welding to form an electrode assembly. This electrode assembly was housed in an exterior housing made of aluminum laminate packaging, and three sides of the electrode terminal and bottom end of the exterior housing were heat-sealed at a sealing temperature of 180°C, a sealing time of 20 seconds, and a sealing pressure of 1.0 MPa. This was then vacuum-dried at a temperature of 60°C, a pressure of 50 Pa, and a drying time of 24 hours.

[0168] <Injection, Impregnation, and Sealing> Approximately 10 g of nonaqueous electrolyte solution 1 was injected into the electrode body housed in an aluminum laminate packaging material under atmospheric pressure, a temperature of 25°C, and a dry air environment with a dew point of -40°C or less. This was then placed in a reduced-pressure chamber, and the pressure was reduced from atmospheric pressure to -95 kPa, thereby impregnating the electrode body with nonaqueous electrolyte solution 1. At this time, the ratio A1 / B1 of the total mass A1 (2.422 g) of the negative electrode active material to the mass B (10 g) of the nonaqueous electrolyte solution 1 was 0.244, and the ratio A2 / B of the total mass A2 (4.35 g) of the positive electrode active material to the mass B of the nonaqueous electrolyte solution 1 was 0.435.

[0169] The electrode laminate impregnated with the nonaqueous electrolyte solution 1 and contained in the aluminum laminate packaging material was then placed in a vacuum sealing machine. The aluminum laminate packaging material was then sealed at 180°C for 10 seconds under a reduced pressure of -95 kPa and a pressure of 0.1 MPa. Two alkali metal ion batteries were produced using this method.

[0170] (Conditioning) The two obtained alkali metal ion batteries were left to stand for 48 hours in an environment of 25°C, so that the non-aqueous electrolyte solution was sufficiently impregnated into the electrode body. Thereafter, the alkali metal ion batteries were pressurized at a pressure of 50 kPa, and a current of 6 mA (0.02 mA / cm) was applied in a temperature environment of 25°C. ２ ) until the voltage reached 3.1 V. Subsequently, constant voltage charging was continued for 2 hours at a voltage of 3.1 V, which was designated as the first charge. Next, the ambient temperature was raised to 35°C, and a constant current of 600 mA (2.00 mA / cm ２ The battery was subjected to constant current charging at a current value of 100 mA / cm2 to a voltage of 3.7 V. Subsequently, constant voltage charging was continued for 2 hours at a voltage of 3.7 V, which was used as the second charge. Note that the current value in this disclosure is expressed as a current value per unit area (mA / cm2) based on the area per side of the positive electrode. ２ After the alkaline metal ion battery was charged, it was left standing in a 45°C environment for 24 hours, and then the temperature was lowered to 25°C, and a current value of 60 mA (0.20 mA / cm ２ ) to 2.0 V. Subsequently, in a 25°C environment, a constant current discharge of 60 mA (0.20 mA / cm ２) to 3.6 V, and constant voltage charging was continued for 2 hours while maintaining the voltage at 3.6 V, thereby conditioning the alkali metal ion battery.

[0171] X-ray Photoelectron Spectroscopy (XPS) One of the alkali metal ion batteries obtained after conditioning was disassembled under an argon atmosphere, and the negative electrode on the outermost layer of the electrode assembly and the opposing positive electrode were removed. The negative electrode and positive electrode were each immersed in a sufficient amount of dimethyl carbonate for 30 minutes for cleaning, and this procedure was repeated three times. After thorough air-drying, the cleaned negative electrode and positive electrode were cut into small pieces measuring 3 mm x 3 mm to prepare samples for XPS measurement. The obtained samples were subjected to XPS measurement under the following conditions without being exposed to the atmosphere. Measurement samples: opposing negative electrode, non-opposing negative electrode, and positive electrode. Equipment used: ULVAC-PHI VersaProbe II. Excitation source: mono. AlKα 20 kV x 5 mA 100 W Analysis size: 100 μmφ x 1.4 mm (100 μmφ X-ray beam oscillating at a width of 1.4 mm) Photoelectron take-off angle: 45° Capture range Survey scan: 0 to 1100 eV Narrow scan: C1s, O1s, Li1s, N1s, F1s, S2p Pass Energy Survey scan: 117.4 eV Narrow scan: 46.95 eV

[0172] The results of the XPS depth profile of the counter negative electrode of Example 1 are shown in Figure 1. Furthermore, for the C1s, O1s, and Li1s data, the C1s detection ratio X1, O1s detection ratio Y1, and Li1s detection ratio Z1 were calculated by the least squares method in the sputtering time range of 5 minutes to 20 minutes, and the C1s detection ratio X2, O1s detection ratio Y2, and Li1s detection ratio Z2 were calculated by the least squares method in the sputtering time range of 30 minutes to 50 minutes. For the XPS depth profiles of the counter negative electrode and the non-counter negative electrode, V1 and V2 were calculated from the average value of the relative element concentration of Li1s in the sputtering time range of 5 minutes to 20 minutes, and W1 and W2 were calculated from the average value of the relative element concentration of C1s. Cs1, Cs2, Ci1, Ci2, D1 and D2 were calculated from the surface XPS analysis and depth profile of the positive electrode.

[0173] <<Evaluation of Electrochemical Characteristics of Alkali Metal Ion Batteries>> (Evaluation of Output Characteristics) The remaining alkali metal ion battery obtained was subjected to constant current charging at a current value of 120 mA to 3.6 V in a 25°C environment, followed by constant voltage charging at a voltage of 3.6 V for 2 hours. Subsequently, it was discharged at a constant current value of 60 mA to 2.5 V. The discharge capacity Q1 at this time was 595 mAh. Subsequently, it was charged at a constant current and constant voltage to 3.6 V under the same conditions as above, and then discharged at a constant current value of 3000 mA to 2.5 V. The discharge capacity Q2 at this time was 454 mAh. From Q2 / Q1, the capacity retention rate in this output evaluation was calculated to be 76.3%. (Evaluation of High-Temperature Charge-Discharge Cycle Characteristics) The alkali metal ion battery was subjected to a charge-discharge cycle test at a 45°C environment under the following conditions. Charge conditions: 1500 mA, 3.5 V, constant current charge. Discharge conditions: 1500 mA, 2.0 V, constant current discharge. Resting conditions: 1 minute rest period after each charge and discharge. After 200 charge / discharge cycles, the 60 mA discharge capacity Q3 and the 3000 mA discharge capacity Q4 were measured under the same conditions as described above. The capacity retention rate was calculated as Q4 / Q3 to be 65.5%. The rate of change in output characteristics before and after each charge / discharge cycle was calculated as (Q4 / Q3) / (Q2 / Q1).

[0174] Positive electrodes 2 to 9 were fabricated in the same manner as the fabrication of positive electrode 1 described above, except for the changes in electrode design shown in Table 2.

[0175]

[0176] The nonaqueous alkali metal ion batteries of Examples 2 to 38 and Comparative Examples 1 to 16 were assembled in the same manner as Example 1 described above, except for the changes in the battery design shown in Table 3.

[0177]

[0178] Except for changing the conditioning conditions shown in Table 4, nonaqueous alkali metal ion batteries of Examples 2 to 38 and Comparative Examples 1 to 16 were fabricated in the same manner as in Example 1 described above.

[0179]

[0180] Tables 5 and 6 show the results of XPS analysis in the depth direction of the opposed negative electrodes, the non-opposing negative electrodes, the positive electrode surfaces, and the positive electrodes of the nonaqueous alkali metal ion batteries of Examples 1 to 38 and Comparative Examples 1 to 16. The XPS depth profile of the negative electrode surface of Example 1 is shown in Figure 1, the XPS depth profile of the negative electrode surface of Comparative Example 1 is shown in Figure 2, and the XPS depth profile of the positive electrode surface of Example 26 is shown in Figure 3.

[0181]

[0182]

[0183] Table 7 shows the results of the evaluation of the output characteristics of the nonaqueous alkali metal ion batteries of Examples 1 to 38 and Comparative Examples 1 to 16.

[0184]

[0185] In the present disclosure, it is believed that by dividing the first charging process during conditioning into two and changing the current rate and temperature between the first and second charges, a non-uniform profile could be formed in the depth direction of the negative electrode SEI of the opposing negative electrode. As can be seen from Figure 1, which shows the results of the XPS depth profile of Example 1, the element profile changes gradually over the sputtering time from 5 to 20 minutes, and the change becomes smaller between 30 and 50 minutes of sputtering. On the other hand, in Figure 2, which shows the results of the XPS depth profile of Comparative Example 1, it can be seen that the element profiles are constant at the 5-minute sputtering time stage and show a steep change between 0 and 5 minutes of sputtering. In the present disclosure, it is believed that the non-uniform SEI in the depth direction as shown in the graph of Figure 1 reduces the energy barriers in the solvation / desolvation process of alkali metal ions at the interface between the non-aqueous electrolyte solution and the SEI, and in the deintercalation process of alkali metal ions at the interface between the SEI and the negative electrode active material, and at the same time, the strong SEI successfully suppresses the reductive decomposition reaction of the nitrile compound. As a result, it is believed that a non-aqueous alkali metal ion battery with excellent output characteristics and charge / discharge cycle characteristics was obtained.

[0186] The nonaqueous alkali metal ion battery of the present invention can be suitably used as a nonaqueous alkali metal ion battery for power regeneration systems in automotive hybrid drive systems that require high output characteristics and charge / discharge cycle characteristics, power load leveling systems for natural power generation such as solar power generation and wind power generation and microgrids, uninterruptible power supply systems in factory production facilities, and contactless power supply systems aimed at leveling voltage fluctuations such as microwave power transmission and electrolytic resonance and storing energy. For example, a plurality of such nonaqueous alkali metal ion batteries can be connected in series or parallel to form a storage module. The nonaqueous alkali metal ion battery of the present invention is preferably used as a lithium ion battery, sodium ion battery, or potassium ion battery, because the effects of the present invention are maximized when used as such a battery.

Claims

1. A non-aqueous alkali metal ion battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte solution containing alkali metal ions, wherein the positive electrode has a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, the negative electrode has a negative electrode current collector and a negative electrode active material layer provided on one or both sides of the negative electrode current collector, the non-aqueous electrolyte solution contains a nitrile compound represented by the formula: R-CN (wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms) as a non-aqueous solvent in a proportion of 5 to 95 volume %, the negative electrode active material contained in the negative electrode active material layer having a solid electrolyte interface (SEI) on its surface, and a depth profile analysis of the SEI on the negative electrode surface by X-ray photoelectron spectroscopy (XPS) shows that the SEI is a nitrile compound having a thickness of 1 to 20 mm / s. A nonaqueous alkali metal ion battery in which X1 > 0 and X2 > 0, and 0.25 < (X1 - X2) < 2.75, is provided, where X1 (atomic % / min) is the detection ratio of C1s (elemental carbon) in the following region and X2 (atomic % / min) is the detection ratio of C1s (elemental carbon) in the region where the sputtering time is 30 minutes or more and 50 minutes or less.

2. The nonaqueous alkali metal ion battery according to claim 1, wherein in a profile analysis of the SEI on the surface of the negative electrode in the depth direction, X1 is 0.35<X1<2.85 and X2 is 0.10<X2<0.

80.

3. The nonaqueous alkali metal ion battery according to claim 1 or 2, wherein in a depth profile analysis of the SEI on the negative electrode surface, the detection ratio X3 of C1s (elemental carbon) for a sputtering time of 10 minutes is 57.5 atomic % or more and 90.5 atomic % or less.

4. The non-aqueous electrolyte solution has the formula: LiN(SO ２ C ｍ F ２ｍ＋１ ) ２ 3. The non-aqueous alkali metal ion battery according to claim 1, comprising an imide salt represented by the formula: {wherein m is an integer of 0 to 8}.

5. The non-aqueous electrolyte is LiPF ６ and LiPF based on the molar mass of the imide salt. ６ The nonaqueous alkali metal ion battery according to claim 4, wherein the content ratio of is 0.01 or more and 10.00 or less.

6. The non-aqueous alkali metal ion battery according to claim 1 or 2, wherein the non-aqueous electrolyte contains vinylene carbonate in a proportion of 0.01% by mass or more and 10.00% by mass or less.

7. The non-aqueous alkali metal ion battery according to claim 6, wherein the non-aqueous electrolyte contains an acid anhydride.

8. The nonaqueous alkali metal ion battery according to claim 7, wherein the content of said vinylene carbonate is greater than the content of said acid anhydride.

9. The non-aqueous electrolyte solution contains an element represented by the following general formula (1): R1-A-R2 (1) (wherein A is one of the following formulas (1-2) to (1-5): wherein R1 and R2 each independently represent an alkyl group having 1 to 4 carbon atoms which may be substituted with an aryl group or a halogen atom; or a vinylidene group which may be substituted with a halogen atom; or an aryl group which may be substituted with an alkyl group or a halogen atom; or R1 and R2 bond to each other to form, together with A, a cyclic structure which may have an unsaturated bond.

10. The nonaqueous alkali metal ion battery according to claim 9, wherein the content of said vinylene carbonate is greater than the content of said compound represented by general formula (1).

11. The nonaqueous alkali metal ion battery according to claim 1 or 2, wherein the nonaqueous electrolyte solution contains one or more compounds having a structure satisfying the following conditions 1 to 5:

1. a fused polycyclic heterocyclic compound, 2. the fused polycyclic heterocyclic ring contains a pyrimidine skeleton, 3. the fused polycyclic heterocyclic ring contains three or more nitrogen atoms, 4. the fused polycyclic heterocyclic ring contains five or more sp2 carbons, and 5. no hydrogen atom is bonded to the nitrogen atom in the fused polycyclic heterocyclic ring.

12. The non-aqueous alkali metal ion battery according to claim 1 or 2, wherein the non-aqueous electrolyte contains a nonionic surfactant in a proportion of 0.1% by mass or more and 4.0% by mass or less.

13. The nonaqueous alkali metal ion battery of claim 12, wherein the nonionic surfactant is one selected from the group consisting of ethyl laurate, triamyl phosphate, tris(2-butoxyethyl) phosphate, and tris(2-ethylhexyl) phosphate.

14. The capacity per unit area of ​​the negative electrode is N (mAh / cm ２ ), the capacity per unit area of ​​the positive electrode is P (mAh / cm ２ 3. The nonaqueous alkali metal ion battery according to claim 1, wherein N / P satisfies 1.11≦N / P≦1.

35.

15. The nonaqueous alkali metal ion battery according to claim 1 or 2, wherein the alkali metal ion is one selected from the group consisting of lithium ions, sodium ions, and potassium ions.

16. The nonaqueous alkali metal ion battery according to claim 1 or 2, wherein XPS analysis of the positive electrode surface shows peaks attributable to S2p (elemental sulfur) at 166 eV to 172 eV and at 162 eV to 166 eV, respectively, and wherein, when Cs1 (atomic %) is the relative element concentration of S2p at 166 eV to 172 eV and Cs2 (atomic %) is the relative element concentration of S2p at 162 eV to 166 eV, Cs1 / Cs2 is 0.50 to 0.

95.

17. The nonaqueous alkali metal ion battery according to claim 16, wherein, in an XPS analysis of the positive electrode surface, Cs1 is 0.30 or more and 1.10 or less, and Cs2 is 0.50 or more and 1.20 or less.

18. The nonaqueous alkali metal ion battery according to claim 1 or 2, wherein the ratio A1 / B of the total mass A1 (g) of the negative electrode active material to the mass B (g) of the nonaqueous electrolyte solution is 0.1 or more and 0.8 or less.

19. The nonaqueous alkali metal ion battery according to claim 1 or 2, wherein the ratio A2 / B of the total mass A2 (g) of the positive electrode active material contained in the positive electrode active material layer to the mass B (g) of the nonaqueous electrolyte solution is 0.2 or more and 1.2 or less.

20. The nonaqueous alkali metal ion battery according to claim 1 or 2, wherein, in a depth profile analysis of the SEI on the negative electrode surface by X-ray photoelectron spectroscopy (XPS), when the detection rate of one alkali metal element selected from Li, Na, and K in a sputtering time range of 5 minutes to 20 minutes is Z1 (atomic % / min.) and the detection rate of one alkali metal element selected from Li, Na, and K in a sputtering time range of 30 minutes to 50 minutes is Z2 (atomic % / min.), Z1 < 0 and Z2 < 0, and −1.95 < (Z1 − Z2) < −0.

11.

21. The nonaqueous alkali metal ion battery according to claim 20, wherein a depth profile analysis of the SEI on the negative electrode surface satisfies −2.20<Z1<−0.

15.

22. The nonaqueous alkali metal ion battery according to claim 20, wherein a depth profile analysis of the SEI on the negative electrode surface satisfies −2.80<Z2<−0.

05.

23. The nonaqueous alkali metal ion battery according to claim 20, wherein in the XPS profile analysis of the SEI on the negative electrode surface in the depth direction, the detection ratio Z3 of alkali metal elements after a sputtering time of 10 minutes is 5.0 atomic % or more and 18.0 atomic % or less.

24. The nonaqueous alkali metal ion battery according to claim 1 or 2, wherein, in a depth profile analysis of the SEI on the surface of the negative electrode by X-ray photoelectron spectroscopy (XPS), when the detection rate of O1s (elemental oxygen) in a sputtering time range of 5 minutes to 20 minutes is Y1 (atomic % / min.) and the detection rate of O1s (elemental oxygen) in a sputtering time range of 30 minutes to 50 minutes is Y2 (atomic % / min.), Y1 < 0 and Y2 < 0, and -1.50 < (Y1 - Y2) < -0.

12.

25. The nonaqueous alkali metal ion battery according to claim 24, wherein a depth profile analysis of the SEI on the negative electrode surface satisfies −1.50<Y1<−0.

14.

26. The nonaqueous alkali metal ion battery according to claim 24, wherein a depth profile analysis of the SEI on the negative electrode surface satisfies −0.15<Y2<−0.

02.

27. The nonaqueous alkali metal ion battery according to claim 24, wherein in the XPS profile analysis of the SEI on the negative electrode surface in the depth direction, the detection ratio Y3 of O1s (oxygen element) after a sputtering time of 10 minutes is 3.8 atomic % or more and 25.5 atomic % or less.

28. The nonaqueous alkali metal ion battery according to claim 1 or 2, having a structure of an electrode laminate or electrode wound body using the positive electrode and the negative electrode, the outermost layer of which is the negative electrode and which has a non-opposing negative electrode portion that does not face the positive electrode, the negative electrode active material of the non-opposing negative electrode having a solid electrolyte interface (SEI) on its surface, and in a depth profile analysis of the SEI on the negative electrode surface by X-ray photoelectron spectroscopy (XPS), when the average relative elemental concentration of C1s (carbon element) on the non-opposing negative electrode surface in a region where a sputtering time is 5 minutes or more and 20 minutes or less is W1 (atomic %) and the average relative elemental concentration of C1s (carbon element) on the negative electrode surface facing the positive electrode in a region where a sputtering time is 5 minutes or more and 20 minutes or less is W2 (atomic %), the relationship is 1.05<(W1 / W2)<1.

25.

29. The nonaqueous alkali metal ion battery according to claim 28, wherein in a profile analysis of the SEI on the surface of the negative electrode in the depth direction, 1.06≦(W1 / W2)≦1.

24.

30. The nonaqueous alkali metal ion battery according to claim 1 or 2, wherein the positive electrode active material contained in the positive electrode active material layer has a solid electrolyte interface (SEI) on its surface, and wherein a depth profile analysis of the SEI on the positive electrode surface by X-ray photoelectron spectroscopy (XPS) reveals that, for a sputtering time of 2 minutes or more and 10 minutes or less, where Ci1 (atomic %) is the average relative element concentration of S2p (elemental sulfur) with a binding energy of 166 eV to 172 eV and Ci2 (atomic %) is 0.04 < Ci1 < 0.50 and 0.10 < Ci2 < 0.

80.

31. The nonaqueous alkali metal ion battery according to claim 30, wherein in a profile analysis of the SEI in the depth direction on the positive electrode surface, 0.5≦Ci1≦0.

4.

32. The nonaqueous alkali metal ion battery according to claim 30, wherein in a depth profile analysis of the SEI on the positive electrode surface, 0.2≦Ci2≦0.

75.

33. The nonaqueous alkali metal ion battery according to claim 30, wherein a depth profile analysis of the SEI on the positive electrode surface satisfies 0.13<(Ci1 / Ci2)<0.

88.

34. The nonaqueous alkali metal ion battery according to claim 1 or 2, wherein the positive electrode active material contained in the positive electrode active material layer has a solid electrolyte interface (SEI) on its surface, and wherein, in a depth profile analysis of the SEI on the positive electrode surface by X-ray photoelectron spectroscopy (XPS), when the detection rate of F1s (elemental fluorine) with a binding energy of 686 eV to 690 eV in a sputtering time range of 2 minutes to 10 minutes is D1 (atomic % / min), and the detection rate of F1s (elemental fluorine) with a binding energy of 683 eV to 686 eV in a sputtering time range of 2 minutes to 10 minutes is D2 (atomic % / min), D1 < 0 and D2 > 0, and -2.00 < (D1 / D2) < -1.

00.

35. The nonaqueous alkali metal ion battery according to claim 34, wherein a depth profile analysis of the SEI on the positive electrode surface satisfies −0.45<D1<−0.

20.

36. The nonaqueous alkali metal ion battery according to claim 34, wherein in a depth profile analysis of the SEI on the positive electrode surface, 0.15<D2<0.

30.

37. A method for manufacturing a non-aqueous alkali metal ion secondary battery comprising a positive electrode, a negative electrode, a non-aqueous electrolyte, and a separator, the method comprising: an assembly step of assembling a non-aqueous alkali metal ion secondary battery precursor comprising the positive electrode, the negative electrode, the non-aqueous electrolyte, and the separator; and an initial charge / discharge step of subjecting the non-aqueous alkali metal ion secondary battery precursor to an initial charge / discharge, wherein the positive electrode comprises a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, and the negative electrode comprises a negative electrode current collector and a negative electrode active material layer provided on one or both sides of the negative electrode current collector, and wherein a solid electrolyte interface (SEI) coating layer on a surface of a negative electrode active material contained in the negative electrode active material layer has the following profile: In a depth profile analysis of the SEI coating layer on the surface of the negative electrode by X-ray photoelectron spectroscopy (XPS), the sputtering time is 5 minutes to 20 minutes. where X1 (atomic % / min) is the detection ratio of C1s (carbon element) in the region below and X2 (atomic % / min) is the detection ratio of C1s (carbon element) in the region where the sputtering time is 30 minutes or more and 50 minutes or less, X1 > 0 and X2 > 0, and 0.25 < (X1 - X2) < 2.75; the non-aqueous electrolyte solution contains, as a non-aqueous solvent, 5% by volume or more and 95% by volume or less of a nitrile compound represented by the formula: R-CN {wherein R is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms}, and vinylene carbonate; the initial charge / discharge step includes at least two successive initial charge steps, and the charge rate in each step is 0.01 mA / cm ２ ~4.00mA / cm ２ a charging rate in the second stage is higher than a charging rate in the first stage, and the charging temperature in each step is in the range of 25°C to 40°C, and the charging temperature in the second stage is 10°C to 15°C higher than the charging temperature in the first stage.

Images