Electrode, secondary battery, battery pack, vehicle and stationary power source

Abstract

To provide a secondary battery having an excellent charge / discharge cycle life, an electrode capable of implementing this secondary battery, and a battery pack having the secondary battery, a vehicle, and a stationary power source.SOLUTION: An electrode is provided that includes an electrode layer containing at least one of Li metal or Li alloy, and a film containing F, S, and N. The film containing F, S, and N covers at least a part of the surface of the electrode layer. The electrode satisfies the following formula (1). 1.5≤I1 / I2 (1). In the formula (1), I1 represents the intensity of a first peak P1 that appears in the range of 686 eV to 690 eV in the F1s spectrum by X-ray photoelectron spectroscopy, and I2 represents the intensity of a second peak P2 that appears in the range of 683 eV to 685 eV in the above-mentioned F1s spectrum.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] An embodiment of the present invention relates to an electrode, a secondary battery, a battery pack, a vehicle, and a stationary power source. [Background technology]

[0002] Batteries using metallic Li as the anode have attracted attention because they can achieve high energy density. On the other hand, ionic liquid electrolytes have been researched because they are non-volatile, non-flammable, and non-inflammable. However, there is a problem with ionic liquid electrolytes, in that an unstable coating is formed on the anode due to reductive decomposition at the anode, which leads to an increase in resistance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-197061 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to the embodiments, an object is to provide a secondary battery having an excellent charge / discharge cycle life, an electrode capable of realizing this secondary battery, and a battery pack, a vehicle, and a stationary power source each including the secondary battery. [Means for solving the problem]

[0005] According to an embodiment, an electrode is provided that includes an electrode layer containing at least one of Li metal or Li alloy, and a film containing F, S, and N. The film containing F, S, and N covers at least a part of the surface of the electrode layer. The electrode satisfies the following formula (1).

[0006] 1.5≦I1 / I2(1) In equation (1), I1 is the intensity of the first peak appearing in the range of 686 eV to 690 eV in the F1s spectrum by X-ray photoelectron spectroscopy, and I2 is the intensity of the second peak appearing in the range of 683 eV to 685 eV in the above-mentioned F1s spectrum.

[0007] According to an embodiment, a secondary battery is provided that includes a positive electrode, a negative electrode, and an electrolyte. The negative electrode is the electrode of the embodiment.

[0008] According to an embodiment, a battery pack including a secondary battery according to the embodiment is provided.

[0009] According to an embodiment, a vehicle including a battery pack according to an embodiment is provided. Also, according to an embodiment, a stationary power source including a battery pack according to an embodiment is provided. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view illustrating an example of a secondary battery according to an embodiment. [Diagram 2] 2 is an enlarged cross-sectional view of a portion A of the secondary battery shown in FIG. 1. [Diagram 3] FIG. 4 is a partially cutaway perspective view illustrating a schematic diagram of another example of a secondary battery according to an embodiment. [Figure 4] 4 is an enlarged cross-sectional view of part B of the secondary battery shown in FIG. 3. [Diagram 5] FIG. 1 is an exploded perspective view illustrating an example of a battery pack according to an embodiment. [Figure 6] 6 is a block diagram showing an example of an electric circuit of the battery pack shown in FIG. 5. [Figure 7] 1 is a cross-sectional view illustrating an example of a vehicle according to an embodiment. [Figure 8] FIG. 1 is a block diagram showing an example of a system including a stationary power supply according to an embodiment. [Figure 9] FIG. 1 shows an X-ray photoelectron spectroscopy spectrum of an electrode. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (First embodiment) The first embodiment relates to an electrode. The electrode includes an electrode layer containing at least one of Li metal or a Li alloy, and a film containing F, S, and N. The electrode also satisfies the following formula (1).

[0012] 1.5≦I1 / I2(1) In formula (1), I1 is the intensity of the first peak appearing in the range of 686 eV to 690 eV in the F1s spectrum by X-ray photoelectron spectroscopy (XPS), and I2 is the intensity of the second peak appearing in the range of 683 eV to 685 eV in the F1s spectrum by XPS.

[0013] The electrode can suppress the initial resistance and the increase in resistance, thereby improving the cycle life of the battery. Although the reason why the electrode suppresses the initial resistance and the increase in resistance is not clear, it is presumed to be due to the following mechanism.

[0014] The film containing F, S and N (hereinafter referred to as FSN-containing film) covers at least a part of the surface of the electrode layer, and therefore can constitute at least a part of the surface of the electrode. Therefore, it can be said that the above F1s spectrum is the F1s spectrum of the FSN-containing film. The first peak is derived from at least one of the bonds of C-F bond and SO2-F bond. On the other hand, the second peak is derived from Li-F bond. By making the ratio I1 / I2 of the intensity of the first peak to the intensity of the second peak 1.5 or more, the abundance ratio of the component having at least one of the bonds of C-F bond and SO2-F bond in the FSN-containing film can be made higher than the abundance ratio of the component having Li-F bond. Therefore, the resistance of the FSN-containing film can be reduced and the durability (stability) of the FSN-containing film can be increased. As a result, the electrode of the embodiment can improve the charge-discharge cycle life of the secondary battery. The upper limit value of the peak intensity ratio I1 / I2 can be set to, for example, 15. By setting the peak intensity ratio I1 / I2 to 15 or less, the effect of LiF in suppressing the reductive decomposition of an electrolyte (for example, a non-aqueous electrolyte such as an organic electrolyte) can be sufficiently obtained, so that gas generation and an increase in resistance can be suppressed.

[0015] A component having at least one of a C-F bond and an SO-F bond (hereinafter referred to as a first bond) may be, for example, a group containing the first bond, a functional group containing the first bond, a compound containing the first bond, etc. Also, the component containing the first bond may be an organic component.

[0016] The component having a Li-F bond (hereinafter, referred to as a second bond) may be, for example, a group containing a second bond, a functional group containing a second bond, or a compound containing a second bond. The component containing a second bond may be an inorganic component. A specific example of the component containing a second bond is LiF. The LiF film is dense. In addition, the LiF film is difficult to decompose and has high durability. Therefore, the resistance of the FSN-containing film can be reduced by making the peak intensity ratio I1 / I2 1.5 or more.

[0017] It is presumed that the N in the FSN-containing film has the effect of lowering the resistance of the FSN-containing film. For example, the N in the FSN-containing film is [N(FSO2)2] - , [N(CF3SO2)2] - etc. are provided.

[0018] The FSN-containing film can contain at least one type of atom selected from the group consisting of Li, C, O, Si, and Cl. Each atom can be contained in the FSN-containing film in the form of a simple element, a compound, or the like.

[0019] The structure of the FSN-containing film is not particularly limited. An example of the FSN-containing film includes a LiF film and an organic film containing F, S and N. It is preferable that the LiF film is disposed on the electrode layer side, and the organic film containing F, S and N is deposited on the LiF film.

[0020] The FSN-containing film may cover at least a part of the surface of the electrode layer. The surface of the electrode layer is, for example, a surface that contacts or faces a separator or another electrode. An example of the surface of the electrode layer is the main surface of the electrode layer. The FSN-containing film may be in direct contact with the electrode layer, or another layer or film may be interposed between the FSN-containing film and the electrode layer. An example of another layer or film is an oxide film that may be formed on the surface of the electrode layer. An example of an oxide film is a natural oxide film of lithium or the like.

[0021] The electrode layer can have a shape such as a sheet shape or a strip shape.

[0022] The electrode layer includes at least one of Li metal and Li alloy. Examples of Li alloy include alloys such as Li-Al, Li-Si, Li-Zn, and Li-Mg. The Li-Mg alloy can suppress Li dendrite precipitation. The molar ratio of Mg in the Li-Mg alloy is preferably in the range of 0.05 to 0.15. The Li metal may include elements other than Li as inevitable impurities.

[0023] The Li metal and the Li alloy can each have a foil shape.

[0024] The electrode may include a current collector. The current collector may be made of, for example, copper. The current collector may be in the form of a sheet such as a foil. An example of the current collector is copper foil.

[0025] The electrode can be obtained, for example, by fixing (for example, pressing) a foil containing at least one of Li metal and Li alloy to a current collector, and then charging and discharging a battery precursor (an uncharged battery) produced by the method described below under the conditions described below. The current collector can be omitted.

[0026] The details of the XPS analysis are described below.

[0027] When the electrode is incorporated in a battery, first, the electrode is removed from the battery by the following method.

[0028] The secondary battery is disassembled under an argon atmosphere, and the electrodes to be measured are taken out. The electrodes to be measured are washed with a solvent consisting of dimethyl carbonate under an argon atmosphere, vacuum dried, and then measured by the method described below.

[0029] The XPS device used may be a Quantera SXM manufactured by ULVAC-PHI, Inc., or a device with equivalent functions. Single crystal spectroscopic Al-Kα radiation (1486.6 eV) is used as the excitation X-ray source. The X-ray output is 4 kW (13 kV x 310 mA), the photoelectron detection angle is 45°, and the analysis area is approximately 4 mm x 0.2 mm. Scanning is performed at 0.10 eV / step.

[0030] FIG. 9 shows an example of an F1s spectrum by XPS measured under the above conditions. In FIG. 9, the horizontal axis is binding energy (eV) and the vertical axis is intensity (c / s). An example of the spectrum of the electrode of the embodiment is shown by a solid line as the spectrum of Example A. Also, the spectrum of Comparative Example A is shown by a dotted line. Here, background such as secondary electrons is removed by the Shirley method. Also, the binding energy (eV) on the horizontal axis of the F1s spectrum is corrected by adjusting the Li1s peak main to 55.0 eV.

[0031] In the spectrum of Example A, a first peak P1 appears at about 688 eV, and a second peak P2 appears at about 684 eV. The intensity I1 of the first peak P1 is about 1 (c / s), and the intensity I2 of the second peak P2 is about 0.1 (c / s). Therefore, the peak intensity ratio I1 / I2 is about 10, which satisfies 1.5 or more.

[0032] On the other hand, in the spectrum of Comparative Example A, a first peak P1 appears at about 689 eV, and a second peak P2 appears at about 684 eV. The intensity I1 of the first peak P1 is about 0.6 (c / s), and the intensity I2 of the second peak P2 is about 1 (c / s). Therefore, the peak intensity ratio I1 / I2 is about 0.6, which is smaller than 1.5.

[0033] Furthermore, the appearance of the first peak P1 in the F1s spectrum by XPS confirms that the coating contains S and F.

[0034] The presence of N in the coating can be confirmed by the appearance of a peak in the N1s spectrum by XPS.

[0035] The electrode of the first embodiment described above includes an electrode layer containing at least one of Li metal or a Li alloy, and a film containing F, S and N. In addition, the electrode satisfies the following formula (1).

[0036] 1.5≦I1 / I2(1) In formula (1), I1 is the intensity of the first peak appearing in the range of 686 eV to 690 eV in the F1s spectrum by XPS, and I2 is the intensity of the second peak appearing in the range of 683 eV to 685 eV in the F1s spectrum by XPS.

[0037] This electrode can suppress the initial resistance and the increase in resistance, thereby improving the cycle life of the battery. In addition, because it has a high energy density, it is suitable for stationary power sources and space applications. Second Embodiment The second embodiment relates to a secondary battery. The secondary battery is, for example, a non-aqueous electrolyte secondary battery. An example of the non-aqueous electrolyte secondary battery is a lithium secondary battery.

[0038] The secondary battery includes a positive electrode, a negative electrode, and an electrolyte. The electrode of the first embodiment is used for at least one of the positive electrode and the negative electrode. The secondary battery of the embodiment may include a separator and an exterior member in addition to the positive electrode, the negative electrode, and the electrolyte. The negative electrode, the positive electrode, and the separator can constitute an electrode group. The electrolyte can be held in the electrode group. The form of the electrode group is not particularly limited, and can be, for example, a stacked type, a wound type, or the like.

[0039] An example of a secondary battery using the electrode of the first embodiment as the negative electrode will be described below. (1) Positive electrode The positive electrode includes a positive electrode active material-containing layer that contains a positive electrode active material, and a positive electrode current collector that is in contact with the positive electrode active material-containing layer. The positive electrode active material-containing layer may be integrated with the positive electrode current collector. The positive electrode active material-containing layer may be a porous body.

[0040] The positive electrode active material may be a compound that absorbs and releases lithium ions. Examples of compounds that absorb and release lithium ions include metal oxides and lithium metal oxides. Each oxide can realize a high-voltage secondary battery. As the lithium metal oxide, lithium cobalt oxide (e.g., Li yCoO2, where 0 < y ≤ 1.1), lithium nickel cobalt manganese oxide (e.g., Li y Ni a Co b Mn c O2, where a + b + c = 1, 0 < a, 0 < b, 0 < c, 0 < y ≤ 1.1), lithium nickel cobalt aluminum oxide (e.g., Li y Ni a Co b Al c O2, where a + b + c = 1, 0 < a, 0 < b, 0 < c, 0 < y ≤ 1.1), lithium cobalt phosphate (e.g., Li y CoPO4, where 0 < y ≤ 1.1), lithium iron phosphate (e.g., Li y FePO4, where 0 < y ≤ 1.1), lithium iron fluoride sulfate (e.g., Li y FeSO4F, where 0 < y ≤ 1.1), lithium manganese iron phosphate (e.g., Li y Mn 1-a Fe a PO4: where 0 < a ≤ 0.5, 0 < y ≤ 1.1), lithium manganese oxide (e.g., Li y Mn2O4, where 0 < y ≤ 1.1), lithium nickel manganese oxide (e.g., Li y Ni 0.5 Mn 1.5 O4, where 0 < y ≤ 1.1), spinel-structured lithium nickel manganese oxide (e.g., Li x Ni a Mn 2-a O 4、 0.4 ≤ a ≤ 0.6, 0 ≤ x ≤ 1.1), etc.

[0041] More preferred cathode active materials are spinel-structured lithium nickel manganese oxide, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium cobalt phosphate, lithium manganese oxide, etc. The above cathode active materials can exhibit a high voltage of 4 V (vs. Li / Li + ) or higher.

[0042] The type of cathode active material to be used can be one type or two or more types.

[0043] The positive electrode active material-containing layer may contain a conductive agent. Examples of the conductive agent include carbon bodies such as carbon nanofibers, acetylene black, and graphite. The above-mentioned types of carbon bodies can improve the electronic network in the positive electrode. The conductive agent may be of one type or two or more types. The ratio of the conductive agent in the positive electrode active material-containing layer (excluding the weight of the non-aqueous electrolyte) is preferably 5% by weight or more and 40% by weight or less.

[0044] The positive electrode active material-containing layer may contain a binder. Examples of binders include polyethylene terephthalate, polysulfone, polyimide, cellulose, rubber, etc. The above-mentioned types of binders have excellent chemical stability against non-aqueous electrolytes. The ratio of the binder in the positive electrode active material-containing layer (excluding the weight of the non-aqueous electrolyte) is preferably 1% by weight or more and 10% by weight or less.

[0045] The positive electrode active material-containing layer may contain lithium ion conductive solid electrolyte particles. This can increase the ion conductivity of the positive electrode. Examples of the lithium ion conductive solid electrolyte include those described in (2) Electrolyte.

[0046] Examples of the positive electrode current collector include a porous body, mesh, or foil made of one or more metals selected from the group consisting of stainless steel, aluminum, and aluminum alloys. The thickness of the positive electrode current collector is preferably 10 μm or more and 20 μm or less. The porosity of the porous body is preferably 30% or more and 98% or less, and more preferably 50% or more and 60% or less. (2) Electrolyte The electrolyte is, for example, a non-aqueous electrolyte. For example, the non-aqueous electrolyte may include an ionic liquid. The ionic liquid may be composed of a cation and an anion.

[0047] The non-aqueous electrolyte may be, for example, a cationic component containing a sulfonium cation and [N(FSO2)2] - and [N(CF3SO2)2] -[N(FSO2)2] - and [N(CF3SO2)2] - are abbreviated as FSI anion and TFSI anion, respectively.

[0048] The FSI anion can increase the intensity of both the first and second peaks. Therefore, the FSI anion can increase the components containing the first bond (at least one of C-F bonds and SO2-F bonds) and the components containing the second bond (Li-F bond) in the FSN-containing membrane. In the presence of both the TFSI anion and the sulfonium cation, the FSI anion can generate the components containing the first bond rather than the components containing the second bond.

[0049] The anion component of the ionic liquid may contain FSI anion and TFSI anion. In this case, the molar ratio of FSI anion to the total number of moles of FSI anion and TFSI anion may be in the range of 0.3 to 0.6. By making the molar ratio 0.3 or more, the component containing the first bond in the FSN-containing film can be increased. On the other hand, by making the molar ratio 0.6 or less, the component containing the second bond in the FSN-containing film can be reduced.

[0050] An example of the sulfonium cation is a trialkylsulfonium cation. The trialkylsulfonium cation has a skeleton represented by the following formula (2) and is paired with an anion. Examples of the anion include the FSI anion and the TFSI anion. Formula (2)

[0051] [ka]

[0052] An example of a trialkylsulfonium cation is the trimethylsulfonium cation (S(CH3)3 +: abbreviation S111), triethylsulfonium cation (S(C2H5)3 + : abbreviation S222), diethylpropylsulfonium cation (S(C2H5)2(C3H7) + : abbreviation S223), methyl ethyl propyl sulfonium cation (S(CH3)(C2H5)(C3H7) + (abbreviated as S123). Triethylsulfonium cation (S222) is preferred. When the ionic liquid contains the S222 cation, the melting point of the ionic liquid is lowered and the ionic conductivity is increased. Furthermore, when the ionic liquid contains the S222 cation, the electrochemical window of the non-aqueous electrolyte is expanded, enabling the operation of a high-voltage secondary battery. The type of trialkylsulfonium cation used can be one or more types.

[0053] The cationic component of the ionic liquid may further include lithium ions. The lithium ions may be supplied, for example, from a lithium salt. The lithium salt is preferably LiN(FSO2)2 or LiN(CF3SO2)2. The type of lithium salt used may be one or more. The amount of lithium salt dissolved in the ionic liquid is preferably 0.3 mol / kg or more and 3 mol / kg or less. In this range, the interface resistance of the negative electrode such as metallic lithium can be reduced, so that it is possible to improve the large current characteristics, suppress dendrite precipitation, and improve the cycle life performance. LiN(FSO2)2 and LiN(CF3SO2)2 are abbreviated as LiFSI and LiTFSI, respectively.

[0054] The non-aqueous electrolyte may contain an organic fluorine compound. Examples of the organic fluorine compound include fluorinated esters and fluorinated ethers. Examples of the fluorinated esters include fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), and 2,2,2-trifluoroethyl methyl carbonate (TFEMC). Examples of the fluorinated ethers include 1,1,2,2-tetrafluoro 2,2,2-trifluoroethyl ether (HFE).

[0055] Other organic fluorine compounds include, for example, methyl 3,3,3-trifluoropropionate (FMP), 2,2,2-trifluoroethyl acetate (FEA), etc. The type of organic fluorine compound can be one or more types.

[0056] The content of the organic fluorine compound in the non-aqueous electrolyte can be, for example, from 0.1% by weight to 10% by weight.

[0057] The non-aqueous electrolyte may contain particles of a lithium ion conductive solid electrolyte. This improves the ion conductivity at low temperatures. The lithium ion conductive solid electrolyte has a lithium ion conductivity of 1x10 at 25°C. -4 S / cm or more, preferably 1×10 -3 It is desirable that it is S / cm or higher.

[0058] Examples of lithium ion conductive solid electrolytes include oxide solid electrolytes with a garnet structure and lithium phosphate solid electrolytes with a Nasicon structure.

[0059] Garnet-type oxide solid electrolytes have the advantage of being highly resistant to reduction and having a wide electrochemical window. The lithium ion conductivity at 25°C is 1×10 -3 As an example of an oxide solid electrolyte with a garnet structure of S / cm or more, La 5+x A x La 3-x M2O 12 (A is at least one selected from the group consisting of Ca, Sr and Ba, M is at least one selected from the group consisting of Nb and Ta, 0≦x≦0.5), Li3M 2-x L2O 12 (M is at least one selected from the group consisting of Ta and Nb, L may include Zr, 0≦x≦0.5), Li 7-3x Al x La3Zr3O 12 (0≦x≦0.5), Li7La3Zr2O 12 Li 6.25 Al 0.25La3Zr3O 12 , Li7La3Zr2O 12 Each of these materials has high ionic conductivity and is electrochemically stable, and therefore can realize a secondary battery excellent in discharge performance and cycle life performance.

[0060] Lithium ion conductivity at 25°C is 1x10 -4 Examples of lithium phosphate solid electrolytes with a Nasicon structure of 0.1 S / cm or more include those represented by LiM2(PO4)3 (where M is one or more selected from Si, Ti, Ge, Sr, Zr, Sn, Al, and Ca). 1+y Al x M 2―x It is preferably represented by (PO4)3 (wherein M is one or more selected from Si, Ti, Ge, Sr, Zr, and Ca, 0≦x≦1, 0≦y≦1). 1+x Al x Ge 2-x (PO4)3(0≦x≦0.5, 0≦y≦1), Li 1+x Al x Zr 2-x (PO4)3(0≦x≦0.5), Li 1+x Al x Ti 2-x (PO4)3 (0≦x≦0.5) is preferred because of its high ionic conductivity and high electrochemical stability, respectively.

[0061] The solid electrolyte may contain unavoidable impurities other than those listed above. The type of solid electrolyte used may be one or more types.

[0062] The non-aqueous electrolyte is preferably in contact with the positive electrode and the negative electrode, or is contained or held in the positive electrode, the negative electrode and the separator, which allows the charge / discharge reaction to occur smoothly.

[0063] The non-aqueous electrolyte is preferably in a liquid or gel state. A gel non-aqueous electrolyte can be obtained, for example, by adding a polymer material and a gelling agent to an ionic liquid to form a gel.

[0064] A method for identifying the components of a non-aqueous electrolyte will be described below by taking as an example a case in which the non-aqueous electrolyte is contained in a secondary battery.

[0065] First, a secondary battery containing a non-aqueous electrolyte to be measured is discharged at 1C until the battery voltage becomes 1.0V. The discharged secondary battery is disassembled in a glove box with an inert atmosphere. Next, the non-aqueous electrolyte contained in the battery and the electrode group is extracted. If the non-aqueous electrolyte can be taken out from the part where the battery is opened, the non-aqueous electrolyte is sampled as it is. On the other hand, if the non-aqueous electrolyte to be measured is held in the electrode group, the electrode group is further disassembled, and for example, a separator impregnated with the non-aqueous electrolyte is taken out. The non-aqueous electrolyte impregnated in the separator can be extracted using, for example, a centrifuge. In this way, the non-aqueous electrolyte can be sampled. In addition, when the amount of non-aqueous electrolyte contained in the secondary battery is small, the non-aqueous electrolyte can also be extracted by immersing the electrodes and the separator in an acetonitrile liquid. The weight of the acetonitrile liquid is measured before and after extraction, and the amount extracted can be calculated.

[0066] The thus obtained non-aqueous electrolyte sample is subjected to, for example, a gas chromatography-mass spectrometry (GC-MS) or nuclear magnetic resonance spectrometry (NMR) to perform composition analysis. In the analysis, first, the components contained in the non-aqueous electrolyte are identified. Then, a calibration curve for each component is prepared. When multiple types of components are contained, a calibration curve for each component is prepared. The composition of the non-aqueous electrolyte can be determined by comparing the prepared calibration curve with the peak intensity or area in the results obtained by measuring the non-aqueous electrolyte sample. (3) Separator The separator can be disposed on at least one surface of the positive electrode, on at least one surface of the negative electrode, or between the positive and negative electrodes. The separator may be in contact with the positive electrode, the negative electrode, or the positive and negative electrodes, or may be integrated with the positive electrode, the negative electrode, or the positive and negative electrodes.

[0067] Examples of the separator include nonwoven fabric, porous membrane, and lithium ion conductive solid electrolyte membrane. Examples of materials for forming the nonwoven fabric include polymer fibers such as cellulose, polyacrylonitrile (PAN), and polyimide, and inorganic fibers such as alumina and silica. Examples of materials for forming the porous membrane include polyethylene (PE), polypropylene (PP), and polyimide. When the viscosity of the ionic liquid is high, the porosity of the separator can be 60% or more and 80% or less. The thickness of the separator can be 5 μm or more and 50 μm or less.

[0068] It is preferable to coat at least one of the main surfaces of the separator, or the positive electrode surface and / or the negative electrode surface in contact with the separator, with inorganic oxide particles. Examples of inorganic oxide particles include alumina particles, titania particles, and lithium conductive solid electrolyte particles. The type of inorganic oxide particles used may be one or more types. Examples of lithium conductive solid electrolytes include those similar to those described in (2) Electrolyte.

[0069] The separator to be used may be of one type or two or more types. For example, a separator made of a lithium ion conductive solid electrolyte membrane and a separator made of a nonwoven fabric or a porous membrane may be stacked together. (4) Exterior materials The secondary battery may include an exterior member. The exterior member includes a container having an opening and a lid attached to the opening of the container. The lid may be a separate member from the container or may be integrated with the container. In addition, the exterior member is not limited to the structure shown in the drawings as long as it can accommodate the positive electrode, the negative electrode, the separator, and the non-aqueous electrolyte. Exterior members having shapes corresponding to rectangular, thin, cylindrical, and coin-shaped batteries may be used.

[0070] Materials constituting the exterior member include metals, laminate films, and the like.

[0071] Examples of metals include iron, stainless steel, aluminum, nickel, etc. When a metal can is used as the container, the plate thickness of the container is desirably 0.5 mm or less, and more preferably 0.3 mm or less.

[0072] Examples of the laminate film include multi-layer films in which aluminum foil or stainless steel foil is covered with a resin film. Polymers such as polypropylene (PP), polyethylene (PE), nylon, and polyethylene terephthalate (PET) can be used as the resin. The thickness of the laminate film is preferably 0.2 mm or less. <Manufacturing method> The secondary battery according to the embodiment can be manufactured, for example, as follows.

[0073] The method for producing a secondary battery includes preparing an electrode without an FSN-containing film as a negative electrode, preparing a positive electrode, preparing an electrolyte, housing the negative electrode and the positive electrode in an exterior member, injecting the electrolyte into the exterior member, sealing the exterior member to obtain a battery precursor, and charging and discharging the battery precursor multiple times.

[0074] As described above, the electrode without the FSN-containing film is prepared by fixing (for example, pressing) a foil containing at least one of Li metal and Li alloy to a current collector. Also, a foil containing at least one of Li metal and Li alloy may be used as the electrode.

[0075] The positive electrode is produced, for example, by the following method. A positive electrode active material, a conductive agent, and a binder are suspended in a solvent to prepare a slurry. This slurry is applied to one side or both sides of a current collector. The applied slurry is then dried to obtain a laminate of an active material-containing layer and a current collector. Then, this laminate is pressed. In this manner, a positive electrode is produced. Alternatively, the positive electrode may be produced by the following method. First, a positive electrode active material, a conductive agent, and a binder are mixed to obtain a mixture. Then, this mixture is formed into pellets. Then, these pellets are placed on a current collector to obtain a positive electrode.

[0076] As the electrolyte, a non-aqueous electrolyte containing an ionic liquid composed of a cationic component containing a sulfonium cation and an anionic component containing at least one of an FSI anion and a TFSI anion is prepared.

[0077] The multiple charge / discharge cycles are, for example, performed at a temperature between room temperature (e.g., 25° C.) and 45° C., and at a current rate between 0.2 C and 1 C. 1 C is the current value at which the nominal capacity of the secondary battery is discharged in one hour. By setting the charge / discharge temperature within the above range, the viscosity of the non-aqueous electrolyte containing the ionic liquid can be kept low, reducing the resistance, thereby suppressing the precipitation of Li dendrites. In addition, by setting the charge / discharge current rate within the above range, the reaction proceeds uniformly on the electrode surface, allowing the FSN-containing film to be formed uniformly.

[0078] By repeating charge and discharge at the above temperature and current rate multiple times, the FSN-containing film can be uniformly formed on the electrode surface. The number of charge and discharge cycles can be, for example, 2 to 10. The voltage range of charge and discharge can be the same from the first to the final cycle, but can also be different.

[0079] It is advisable to provide a rest period between charging and discharging. This allows the state inside the battery (inside the exterior material) to stabilize. The rest period can be between 10 minutes and 1 hour.

[0080] Before carrying out multiple charge / discharge cycles, the battery precursor may be subjected to a storage (aging) treatment.

[0081] According to the above method, the uniformity of the FSN-containing film can be increased while preventing the precipitation of Li dendrites, and therefore a secondary battery including the electrode of the embodiment can be manufactured.

[0082] Next, a secondary battery according to an embodiment will be described with reference to the drawings.

[0083] Fig. 1 is a cross-sectional view showing an example of a secondary battery according to an embodiment of the present invention, Fig. 2 is an enlarged cross-sectional view showing a portion A of the secondary battery shown in Fig. 1.

[0084] The secondary battery 100 shown in Figures 1 and 2 includes a bag-shaped exterior member 2 shown in Figures 1 and 2, an electrode group 1 shown in Figure 1, and a non-aqueous electrolyte (not shown). The electrode group 1 and the non-aqueous electrolyte are housed in the bag-shaped exterior member 2. The non-aqueous electrolyte (not shown) is held in the electrode group 1.

[0085] The bag-shaped exterior member 2 is made of a laminate film including two resin layers and a metal layer interposed between them.

[0086] As shown in Fig. 1, the electrode group 1 is a flat wound-type electrode group. As shown in Fig. 2, the flat wound-type electrode group 1 includes a negative electrode 3, a separator 4, and a positive electrode 5. The separator 4 is interposed between the negative electrode 3 and the positive electrode 5.

[0087] The negative electrode 3 includes a negative electrode current collector 3a and a negative electrode layer 3b. In the negative electrode 3, in a portion located at the outermost shell of the wound-type electrode group 1, the negative electrode layer 3b is formed only on the inner surface side of the negative electrode current collector 3a as shown in Fig. 2. In the other portions of the negative electrode 3, the negative electrode layer 3b is formed on both sides of the negative electrode current collector 3a.

[0088] The positive electrode 5 includes a positive electrode current collector 5a and a positive electrode mixture layer (positive electrode active material-containing layer) 5b formed on both sides of the positive electrode current collector 5a.

[0089] As shown in FIG. 1, the negative electrode terminal 6 and the positive electrode terminal 7 are located near the outer peripheral end of the wound electrode group 1. The negative electrode terminal 6 is connected to a portion located at the outermost shell of the negative electrode current collector 3a. The positive electrode terminal 7 is connected to a portion located at the outermost shell of the positive electrode current collector 5a. The negative electrode terminal 6 and the positive electrode terminal 7 extend to the outside from an opening of the bag-shaped exterior member 2. A thermoplastic resin layer is provided on the inner surface of the bag-shaped exterior member 2, and the opening is closed by heat sealing.

[0090] The secondary battery according to the embodiment is not limited to the secondary battery having the configuration shown in FIGS. 1 and 2, but may be a battery having the configuration shown in FIGS.

[0091] Fig. 3 is a partially cutaway perspective view showing a schematic diagram of another example of a secondary battery according to an embodiment of the present invention Fig. 4 is an enlarged cross-sectional view of part B of the secondary battery shown in Fig. 3. The secondary battery 100 shown in Figures 3 and 4 includes an electrode group 1 shown in Figures 3 and 4, an exterior member 2 shown in Figure 3, and a non-aqueous electrolyte (not shown). The electrode group 1 and the non-aqueous electrolyte are housed in the exterior member 2. The non-aqueous electrolyte is held in the electrode group 1.

[0092] The exterior member 2 is made of a laminate film including two resin layers and a metal layer interposed between them.

[0093] The electrode group 1 is a laminated type electrode group, as shown in Fig. 4. The laminated type electrode group 1 has a structure in which negative electrodes 3 and positive electrodes 5 are alternately laminated with separators 4 interposed therebetween.

[0094] The electrode group 1 includes a plurality of negative electrodes 3. Each of the plurality of negative electrodes 3 includes a negative electrode current collector 3a and a negative electrode layer 3b supported on both sides of the negative electrode current collector 3a. The electrode group 1 also includes a plurality of positive electrodes 5. Each of the plurality of positive electrodes 5 includes a positive electrode current collector 5a and a positive electrode mixture layer 5b supported on both sides of the positive electrode current collector 5a.

[0095] The negative electrode current collector 3a of each negative electrode 3 includes a portion 3c on one side of which the negative electrode layer 3b is not supported on any surface. This portion 3c serves as a negative electrode current collector tab. As shown in FIG. 4, the portion 3c serving as the negative electrode current collector tab does not overlap with the positive electrode 5. The multiple negative electrode current collector tabs (portions 3c) are electrically connected to a strip-shaped negative electrode terminal 6. The tip of the strip-shaped negative electrode terminal 6 is pulled out to the outside of the exterior member 2.

[0096] Although not shown, the positive electrode current collector 5a of each positive electrode 5 includes a portion on one side where the positive electrode mixture layer 5b is not supported on any surface. This portion serves as a positive electrode current collector tab. The positive electrode current collector tab does not overlap with the negative electrode 3. The positive electrode current collector tab is located on the opposite side of the electrode group 1 to the negative electrode current collector tab (portion 3c). The positive electrode current collector tab is electrically connected to a strip-shaped positive electrode terminal 7. The tip of the strip-shaped positive electrode terminal 7 is located on the opposite side to the negative electrode terminal 6, and is drawn out to the outside of the exterior member 2.

[0097] The secondary battery according to the embodiment described above includes the electrode of the first embodiment, and therefore it is possible to provide a secondary battery having low initial resistance, suppressed resistance increase, and excellent charge / discharge cycle performance. Third embodiment According to a third embodiment, a battery pack is provided. The battery pack includes the secondary battery according to the second embodiment. The battery pack may include one secondary battery according to the second embodiment, or may include a battery pack including a plurality of secondary batteries.

[0098] The battery pack according to the embodiment may further include a protection circuit. The protection circuit has a function of controlling charging and discharging of the secondary battery. Alternatively, a circuit included in a device (e.g., electronic device, automobile, etc.) that uses the battery pack as a power source may be used as the protection circuit for the battery pack.

[0099] The battery pack according to the embodiment may further include an external terminal for current flow. The external terminal for current flow is for outputting current from the secondary battery to the outside and / or for inputting current from the outside to the secondary battery. In other words, when the battery pack is used as a power source, a current is supplied to the outside through the external terminal for current flow. In addition, when the battery pack is charged, a charging current (including regenerative energy from the power of an automobile or the like) is supplied to the battery pack through the external terminal for current flow.

[0100] Next, an example of a battery pack according to an embodiment will be described with reference to the drawings.

[0101] Fig. 5 is a perspective view showing an example of a battery pack according to an embodiment, disassembled into parts, and Fig. 6 is a block diagram showing an example of an electric circuit of the battery pack shown in Fig. 5.

[0102] 5 and 6 show an example of a battery pack 50. This battery pack 50 includes a plurality of secondary batteries of the embodiment. A plurality of secondary batteries 51 are stacked such that the surfaces on which the negative electrode terminals and the positive electrode terminals are arranged are aligned at the same position, and are fastened with adhesive tape 52 to form an assembled battery 53. These secondary batteries 51 are electrically connected in series as shown in FIG.

[0103] The printed wiring board 54 is disposed opposite the surface on which the negative and positive terminals of the secondary battery 51 are disposed. A thermistor 55, a protective circuit 56, and an external terminal 57 for supplying electricity to an external device as an external terminal for supplying electricity are mounted on the printed wiring board 54 as shown in Fig. 6. An insulating plate (not shown) is attached to the surface of the printed wiring board 54 facing the assembled battery 53 to prevent unnecessary connection with the wiring of the assembled battery 53.

[0104] The positive electrode lead 58 is connected to a positive electrode terminal located on the bottom layer of the battery pack 53, and its tip is inserted into and electrically connected to a positive electrode connector 59 on the printed wiring board 54. The negative electrode lead 60 is connected to a negative electrode terminal located on the top layer of the battery pack 53, and its tip is inserted into and electrically connected to a negative electrode connector 61 on the printed wiring board 54. These connectors 59, 61 are connected to the protection circuit 56 through wires 62, 63 formed on the printed wiring board 54.

[0105] The thermistor 55 detects the temperature of the secondary battery 51, and the detection signal is sent to the protection circuit 56. The protection circuit 56 can cut off the positive side wiring 64a and the negative side wiring 64b between the protection circuit 56 and the terminal 57 for supplying electricity to an external device as an external terminal for supplying electricity under a predetermined condition. The predetermined condition is, for example, when the temperature detected by the thermistor 55 becomes equal to or higher than a predetermined temperature. Also, the predetermined condition is when overcharging, overdischarging, overcurrent, etc. of the secondary battery 51 is detected. This detection of overcharging, etc. is performed for each secondary battery 51 or for the entire secondary battery 51. When detecting each secondary battery 51, the battery voltage may be detected, or the positive electrode potential or the negative electrode potential may be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each secondary battery 51. In the case of FIG. 5 and FIG. 6, wiring 65 for voltage detection is connected to each secondary battery 51, and a detection signal is transmitted to the protection circuit 56 through these wirings 65.

[0106] Protective sheets 66 made of rubber or resin are disposed on the three side surfaces of the battery pack 53 except for the surfaces on which the positive and negative terminals protrude.

[0107] The battery pack 53 is stored in a storage container 67 together with the protective sheets 66 and the printed wiring board 54. That is, the protective sheets 66 are arranged on both inner surfaces in the long side direction and on the inner surface in the short side direction of the storage container 67, and the printed wiring board 54 is arranged on the inner surface on the opposite side in the short side direction. The battery pack 53 is located in a space surrounded by the protective sheets 66 and the printed wiring board 54. A lid 68 is attached to the top surface of the storage container 67.

[0108] Note that heat shrink tape may be used to secure the battery pack 53, instead of the adhesive tape 52. In this case, protective sheets are placed on both sides of the battery pack, the heat shrink tape is wrapped around it, and then the heat shrink tape is thermally shrunk to bind the battery pack.

[0109] 5 and 6 show a configuration in which the secondary batteries 51 are connected in series, but they may be connected in parallel to increase the battery capacity. Alternatively, a combination of series and parallel connections may be used. The assembled battery pack may be further connected in series or parallel.

[0110] 5 and 6 includes one battery pack, the battery pack according to the embodiment may include multiple battery packs. The multiple battery packs are electrically connected in series, in parallel, or in a combination of series and parallel connections.

[0111] The battery pack may be modified as appropriate depending on the application. The battery pack according to the present embodiment is suitable for use in applications that require excellent cycle performance when a large current is drawn. Specifically, the battery pack is used as a power source for digital cameras, or as a vehicle battery for, for example, two- to four-wheeled hybrid electric vehicles, two- to four-wheeled electric vehicles, power-assisted bicycles, or railroad vehicles (e.g., trains), or as a stationary battery. In particular, the battery pack is suitable for use as a large storage battery for stationary power storage systems or an on-board battery installed in a vehicle.

[0112] The battery pack according to the embodiment includes the secondary battery according to the embodiment, and therefore has excellent charge / discharge cycle performance. (Fourth embodiment) According to a fourth embodiment, a vehicle is provided. The vehicle is equipped with a battery pack according to the embodiment.

[0113] In the vehicle according to the embodiment, the battery pack recovers, for example, regenerative energy of the vehicle's motive power. The vehicle may include a mechanism for converting the kinetic energy of the vehicle into regenerative energy.

[0114] Examples of vehicles include, for example, two to four wheel hybrid electric vehicles, two to four wheel electric vehicles, power assisted bicycles, and rail vehicles.

[0115] The mounting position of the battery pack in the vehicle is not particularly limited. For example, when the battery pack is mounted in an automobile, the battery pack can be mounted in the engine compartment, the rear of the vehicle body, or under the seat of the vehicle.

[0116] The vehicle may be equipped with a plurality of battery packs. In this case, the battery packs may be electrically connected in series, electrically connected in parallel, or electrically connected in a combination of series and parallel connections.

[0117] Next, an example of a vehicle according to an embodiment will be described with reference to the drawings.

[0118] FIG. 7 is a cross-sectional view that illustrates an example of a vehicle according to the embodiment.

[0119] A vehicle 71 shown in Fig. 7 includes a vehicle body and a battery pack 72 according to the embodiment. In the example shown in Fig. 7, the vehicle 71 is a four-wheeled automobile.

[0120] The vehicle 71 may be equipped with a plurality of battery packs 72. In this case, the battery packs 72 may be connected in series, in parallel, or in a combination of series and parallel connections.

[0121] 7 illustrates an example in which the battery pack 72 is mounted in an engine room located at the front of the vehicle body. As described above, the battery pack 72 may be mounted, for example, at the rear of the vehicle body or under a seat. This battery pack 72 can be used as a power source for the vehicle. In addition, this battery pack 72 can recover regenerative energy for the vehicle's motive power.

[0122] The vehicle according to the embodiment is equipped with the battery pack according to the embodiment, and therefore, according to the embodiment, it is possible to provide a vehicle equipped with a battery pack having excellent charge / discharge cycle performance. Fifth embodiment According to the fifth embodiment, a stationary power source is provided. This stationary power source is equipped with a battery pack according to the embodiment. Note that this stationary power source may be equipped with a secondary battery or a battery pack according to the embodiment, instead of the battery pack according to the embodiment.

[0123] FIG. 8 is a block diagram showing an example of a system including a stationary power source according to the embodiment. FIG. 8 is a diagram showing an example of application to stationary power sources 112 and 123 as an example of use of the battery packs 300A and 300B according to the embodiment. In the example shown in FIG. 8, a system 110 in which the stationary power sources 112 and 123 are used is shown. The system 110 includes a power plant 111, a stationary power source 112, a consumer-side power system 113, and an energy management system (EMS) 115. In addition, a power grid 116 and a communication network 117 are formed in the system 110, and the power plant 111, the stationary power source 112, the consumer-side power system 113, and the EMS 115 are connected via the power grid 116 and the communication network 117. The EMS 115 uses the power grid 116 and the communication network 117 to perform control to stabilize the entire system 110.

[0124] The power plant 111 generates a large amount of power using fuel sources such as thermal power and atomic power. Power is supplied from the power plant 111 through a power grid 116 or the like. A battery pack 300A is mounted on the stationary power source 112. The battery pack 300A can store the power supplied from the power plant 111. The stationary power source 112 can supply the power stored in the battery pack 300A through the power grid 116 or the like. The system 110 is provided with a power conversion device 118. The power conversion device 118 includes a converter, an inverter, a transformer, and the like. Thus, the power conversion device 118 can perform conversion between direct current and alternating current, conversion between alternating currents having different frequencies, and voltage transformation (boosting and bucking), and the like. Thus, the power conversion device 118 can convert the power from the power plant 111 into power that can be stored in the battery pack 300A.

[0125] The consumer-side power system 113 includes a power system for a factory, a power system for a building, a power system for a home, etc. The consumer-side power system 113 includes a consumer-side EMS 121, a power conversion device 122, and a stationary power source 123. The stationary power source 123 is equipped with a battery pack 300B. The consumer-side EMS 121 performs control to stabilize the consumer-side power system 113.

[0126] The consumer-side power system 113 is supplied with power from the power plant 111 and power from the battery pack 300A through the power grid 116. The battery pack 300B can store the power supplied to the consumer-side power system 113. Similarly to the power conversion device 118, the power conversion device 122 includes a converter, an inverter, a transformer, and the like. Therefore, the power conversion device 122 can perform conversion between DC and AC, conversion between ACs with different frequencies, and voltage transformation (boost and step-down), etc. Therefore, the power conversion device 122 can convert the power supplied to the consumer-side power system 113 into power that can be stored in the battery pack 300B.

[0127] The power stored in the battery pack 300B can be used, for example, to charge a vehicle such as an electric car. The system 110 may also be provided with a natural energy source. In this case, the natural energy source generates power using natural energy such as wind power and solar power. Power is supplied from the natural energy source in addition to the power plant 111 through the power grid 116.

[0128] The stationary power source according to the embodiment includes the battery pack according to the embodiment. Therefore, according to the present embodiment, it is possible to provide a stationary power source including a battery pack having excellent charge / discharge cycle performance. EXAMPLES

[0129] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the embodiments described below. Example 1 The positive electrode active material was lithium nickel cobalt manganese oxide (LiNi 0.5 Co 0.3 Mn 0.2 O2) was used. 2 wt% acetylene black as a conductive agent, 6 wt% graphite powder, and 3 wt% PVdF as a binder were mixed with the positive electrode active material, and dispersed in n-methylpyrrolidone (NMP) solvent to prepare a slurry. The content of each component in the slurry is the value when the positive electrode active material-containing layer is taken as 100 wt%. The slurry was applied to a current collector made of aluminum foil with a thickness of 10 μm, dried, and pressed to prepare a positive electrode (density of the positive electrode active material-containing layer: 3.2 g / cm 3 ) was prepared.

[0130] The negative electrode was prepared by pressing a 20 μm-thick lithium metal foil onto a 6 μm-thick copper current collector foil.

[0131] The ionic liquid described below was prepared as a non-aqueous electrolyte. The ionic liquid was prepared by mixing and adjusting the molar fraction of triethylsulfonium salt represented by S222TFSI and lithium salt represented by LiFSI to be 1:1. The molar ratio of FSI anion to the total number of moles of TFSI anion and FSI anion was 0.5. As a separator, a 30 μm polyimide porous separator was prepared. An electrode group was produced by alternately stacking positive and negative electrodes with a separator between them. This electrode group was placed in a container made of an aluminum-containing laminate film with a thickness of 0.1 mm, and a battery precursor for a thin secondary battery with the structure shown in Figure 1 was produced. The size of the secondary battery was 7 mm x 40 mm x 60 mm. The capacity of the secondary battery was 2 Ah, the average voltage of the secondary battery was 3.6 V, and the weight of the secondary battery was 35 g.

[0132] The battery precursor of Example 1 was charged to 4.2 V at a constant current of 0.2 C (0.4 A) and then discharged to 3.0 V at 0.2 C (0.4 A) five times at 45° C. to produce a secondary battery. (Examples 2-10) A secondary battery was produced in the same manner as in Example 1, except that the molar ratio of the FSI anion in the ionic liquid, the charge / discharge temperature, the charge / discharge rate, and the number of charge / discharge cycles were set as shown in Table 1 below. Example 11 A battery precursor assembled in the same manner as in Example 1 was charged to 4.2 V at a constant current of 0.2 C (0.4 A) and then discharged to 2.8 V at 0.2 C (0.4 A) for five cycles at 45° C. to produce a secondary battery. Example 12 A secondary battery was produced in the same manner as in Example 1, except that the molar ratio of the FSI anion in the ionic liquid, the charge / discharge temperature, the charge / discharge rate, and the number of charge / discharge cycles were set as shown in Table 1 below. (Comparative Examples 1-3, 5) A secondary battery was produced in the same manner as in Example 1, except that the molar ratio of the FSI anion in the ionic liquid, the charge / discharge temperature, the charge / discharge rate, and the number of charge / discharge cycles were set as shown in Table 1 below. Comparative Example 4 The battery precursor assembled in the same manner as in Example 1 was used as a secondary battery without being charged or discharged.

[0133] Each secondary battery was charged at a constant current of 0.4 A at 25° C. up to 4.2 V, and then discharged at 0.4 A down to 3.0 V, and a charge-discharge cycle was repeated, and the number of cycles at which the capacity retention rate reached 80% was determined as the cycle life. The cycle life of Example 1 was set as 100, and the cycle life of the other Examples and Comparative Examples was expressed, and the results are shown in Table 1.

[0134] For the electrodes of the examples and comparative examples, it was confirmed by the above-mentioned method that a film containing F, S, and N was present on the surface of the electrode layer. Furthermore, the peak intensity ratio I1 / I2 in the F1s spectrum by XPS was measured by the above-mentioned method, and the results are shown in Table 1.

[0135] [Table 1]

[0136] As is clear from Table 1, the secondary batteries of Examples 1 to 12 in which the peak intensity ratio I1 / I2 is 1.5 or more have a longer charge / discharge cycle life than the secondary batteries of Comparative Examples 1 to 5 in which the peak intensity ratio I1 / I2 is less than 1.5.

[0137] In Comparative Example 1, in which the charge / discharge temperature was high, Comparative Example 2, in which the charge / discharge current rate was high, Comparative Example 3, in which the charge / discharge count was one, and Comparative Example 4, in which charge / discharge was not performed, the FSN-containing film was formed non-uniformly on the electrode surface, so that the peak intensity ratio I1 / I2 was smaller than 1.5. In Comparative Example 5, in which the molar ratio of FSI anion was small, the intensity of the second peak was large even though the charge / discharge conditions were appropriate, so that the peak intensity ratio I1 / I2 was smaller than 1.5.

[0138] According to at least one of the above-described embodiments or examples, the electrode includes an electrode layer containing at least one of Li metal or a Li alloy, and a film containing F, S, and N. The electrode also satisfies the following formula (1).

[0139] 1.5≦I1 / I2(1) In formula (1), I1 is the intensity of the first peak appearing in the range of 686 eV to 690 eV in the F1s spectrum by XPS, and I2 is the intensity of the second peak appearing in the range of 683 eV to 685 eV in the F1s spectrum by XPS.

[0140] The electrode can improve the charge / discharge cycle life.

[0141] The following describes the embodiments of the invention. <1> an electrode layer including at least one of Li metal and Li alloy; a film covering at least a portion of the surface of the electrode layer and containing F, S and N; An electrode that satisfies the following formula (1).

[0142] 1.5≦I1 / I2(1) In the formula (1), I1 is the intensity of the first peak appearing in the range of 686 eV to 690 eV in the F1s spectrum by X-ray photoelectron spectroscopy, and I2 is the intensity of the second peak appearing in the range of 683 eV to 685 eV in the F1s spectrum. <2> The intensity ratio, I1 / I2, is greater than or equal to 1.5 and less than or equal to 15. <1> The electrode according to claim 1. <3> A secondary battery including a positive electrode, a negative electrode, and an electrolyte, The negative electrode <1> or <2> A secondary battery comprising the electrode according to claim 1. <4> The electrolyte comprises a sulfonium cation and [N(FSO2)2] - and [N(CF3SO2)2] - and an anion consisting of at least one of <3> The secondary battery according to claim 1. <5> [N(FSO2)2] - and [N(CF3SO2)2] - [N(FSO2)2] for the sum of - The molar ratio of is in the range of 0.3 to 0.6. <4> The secondary battery according to claim 1. <6> <3> ~ <5> A battery pack comprising the secondary battery according to any one of claims 1 to 5. <7> An external terminal for supplying electricity; Protection circuit and Further comprising <6> The battery pack according to claim 1 . <8> A battery comprising a plurality of the secondary batteries, The secondary batteries are electrically connected in series, in parallel, or in a combination of series and parallel. <7> The battery pack according to claim 1 . <9> <6> ~ <8> A vehicle equipped with a battery pack according to any one of the preceding claims. <10> <6> ~ <8> 13. A stationary power source comprising the battery pack according to any one of claims 1 to 12.

[0143] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0144] Reference Signs List 1...electrode group, 2...exterior member, 3...negative electrode, 3a...negative electrode current collector, 3b...negative electrode layer, 3c...portion of negative electrode current collector, 4...separator, 5...positive electrode, 5a...positive electrode current collector, 5b...positive electrode active material-containing layer, 6...negative electrode terminal, 7...positive electrode terminal, 51...secondary battery, 52...adhesive tape, 53...battery pack, 54...printed wiring board, 55...thermistor, 56...protective circuit circuit), 57...current-carrying terminal, 58...positive lead, 59...positive connector, 60...negative lead, 61...negative connector, 62...wiring, 63...wiring, 64a...positive wiring, 64b...negative wiring, 65...wiring, 66...protective sheet, 67...storage container, 68...lid, 71...vehicle, 72...battery pack, 110...system, 111...power plant, 112...stationary power source, 113...consumer-side power system, 115...energy management system (EMS), 116...power grid, 117...communication network, 118...power conversion device, 121...consumer-side EMS, 122...power conversion device, 123...stationary power source.

Claims

1. an electrode layer including at least one of Li metal or Li alloy; a film covering at least a portion of the surface of the electrode layer and containing F, S and N; An electrode that satisfies the following formula (1). 1.5≦I １ / I ２ (1) In the formula (1), I １ is the intensity of the first peak appearing in the range of 686 eV to 690 eV in the F1s spectrum by X-ray photoelectron spectroscopy, and I ２ is the intensity of the second peak appearing in the range of 683 eV to 685 eV in the F1s spectrum.

2. I １ / I ２ 2. The electrode according to claim 1, wherein the intensity ratio expressed by is 1.5 or more and 15 or less.

3. A secondary battery including a positive electrode, a negative electrode, and an electrolyte, 3. A secondary battery, wherein the negative electrode is the electrode according to claim 1 or 2.

4. The electrolyte comprises a sulfonium cation and [N(FSO 2 ) 2 ] - and [N(CF 3 SO 2 ) 2 ] - and an anion consisting of at least one of the following:

5. [N(FSO 2 ) 2 ] - and [N(CF 3 SO 2 ) 2 ] - [N(FSO 2 ) 2 ] - The secondary battery according to claim 4 , wherein the molar ratio of is in the range of 0.3 to 0.

6.

6. A battery pack comprising the secondary battery according to claim 3.

7. An external terminal for supplying electricity; Protection circuit and The battery pack of claim 6 further comprising:

8. A battery comprising a plurality of the secondary batteries, The battery pack according to claim 7 , wherein the secondary batteries are electrically connected in series, in parallel, or in a combination of series and parallel.

9. A vehicle equipped with the battery pack according to claim 6.

10. A stationary power source comprising the battery pack according to claim 6.

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