Secondary battery, battery pack, and vehicle

Abstract

To provide a secondary battery that excels in a charge-discharge cycle life at high temperature, and a battery pack including the secondary battery, and a vehicle.SOLUTION: According to an embodiment, a secondary battery is provided that comprises a cathode, an anode, and a non-aqueous electrolyte. The cathode includes a cathode active material and a solid electrolyte. The cathode satisfies formula (1) in an S1s spectrum by hard X-ray photoelectron spectroscopy. Formula (1): B / A≤1 / 3, where A represents the intensity of a maximum peak in the S1s spectrum appearing in the range of binding energy from 2468 eV to 2474 eV inclusive, and B represents the intensity of a maximum peak in the S1s spectrum appearing in the range of binding energy from 2475 eV to 2483 eV inclusive.SELECTED DRAWING: Figure 10

Description

[Technical field]

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

[0002] Non-aqueous electrolyte batteries using lithium metal, lithium alloys, lithium compounds, or carbonaceous materials as the negative electrode are expected to have high energy density, and research and development is being conducted. 1 / 3 Co 1 / 3 Mn 1 / 3 Lithium ion batteries, which have a positive electrode containing O2 or LiMn2O4 and a negative electrode containing a carbonaceous material that absorbs and releases lithium, are widely used for portable devices.

[0003] It has been considered to include a sulfone-based compound or a sultone-based compound in the nonaqueous electrolyte of a nonaqueous electrolyte battery. A battery having a nonaqueous electrolyte containing a sulfone-based compound or a sultone-based compound has a problem with resistance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. WO2015 / 136688 [Patent Document 2] Special Publication No. 2015-522209 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a secondary battery having an excellent charge / discharge cycle life at high temperatures, and a battery pack and a vehicle each including the secondary battery. [Means for solving the problem]

[0006] According to an embodiment, a secondary battery is provided that includes a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode includes a positive electrode active material and a solid electrolyte. The positive electrode satisfies the following formula (1) in an S1s spectrum by hard X-ray photoelectron spectroscopy.

[0007] B / A≦1 / 3 (1) Here, A is the intensity of the maximum peak appearing in the binding energy range of 2468 eV to 2474 eV in the S1s spectrum, and B is the intensity of the maximum peak appearing in the binding energy range of 2475 eV to 2483 eV in the S1s spectrum.

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

[0009] Furthermore, according to the embodiment, a vehicle including a battery pack according to the embodiment is provided. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a partially cutaway cross-sectional view of a secondary battery according to the embodiment. [Diagram 2] FIG. 2 is a side view of the battery of FIG. 1 . [Diagram 3] 2 is a cross-sectional view of the secondary battery according to the embodiment, taken in a direction perpendicular to the terminal extending direction. [Figure 4] FIG. 4 is an enlarged cross-sectional view of part A in FIG. 3 . [Diagram 5] FIG. 2 is a perspective view showing an example of a battery pack including the secondary battery according to the embodiment; [Figure 6] FIG. 2 is an exploded perspective view of the battery pack according to the embodiment. [Figure 7] FIG. 7 is a block diagram showing an electrical circuit of the battery pack of FIG. 6. [Figure 8] 1 is a schematic diagram showing an example of a vehicle equipped with a secondary battery according to an embodiment; [Figure 9] FIG. 13 is a diagram illustrating another example of a vehicle according to an embodiment. [Figure 10] FIG. 2 is a diagram showing an example of an S1s spectrum by hard X-ray photoelectron spectroscopy of the positive electrode of the secondary battery of Example 1. [Figure 11] FIG. 2 is a diagram showing an example of an S1s spectrum by hard X-ray photoelectron spectroscopy of the positive electrode of the secondary battery of Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] First embodiment According to a first embodiment, a secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte is provided. The positive electrode includes a positive electrode active material and a solid electrolyte. The positive electrode satisfies the following formula (1) in an S1s spectrum by hard X-ray photoelectron spectroscopy (HAXPES).

[0012] B / A≦1 / 3 (1) Here, A is the intensity of the maximum peak appearing in the binding energy range of 2468 eV or more and 2474 eV or less in the S1s spectrum, and B is the intensity of the maximum peak appearing in the binding energy range of 2475 eV or more and 2483 eV or less in the S1s spectrum.

[0013] As a result of extensive research, the inventors have found that when the S1s spectrum measured by hard X-ray photoelectron spectroscopy satisfies formula (1), the resistance of the secondary battery can be reduced, and therefore the charge-discharge cycle life at high temperatures can be improved.

[0014] Hard X-ray photoelectron spectroscopy can confirm the bonding state of elements present near the surface of the positive electrode (for example, a region from the positive electrode surface to a depth of several tens of nm). The surface of the positive electrode is, for example, the surface of a layer containing a positive electrode active material. The S1s spectrum obtained by hard X-ray photoelectron spectroscopy shows the bonding state of S elements near the surface of the positive electrode (for example, a region from the positive electrode surface to a depth of several tens of nm). The maximum peak (hereinafter referred to as the first peak) appearing in the S1s spectrum where the binding energy is in the range of 2468 eV to 2474 eV is derived from a C-S bond. On the other hand, the maximum peak (hereinafter referred to as the second peak) appearing in the S1s spectrum where the binding energy is in the range of 2475 eV to 2483 eV is derived from an -SO x (SOx -SO x In the above formula, x is, for example, a value that satisfies x>0. x Examples include -SO3 (SO3 group) and -SO4 (SO4 group).

[0015] By making the ratio (B / A) of the second peak intensity B to the first peak intensity A 1 / 3 or less, the S-containing substances having CS bonds on the surface of the positive electrode and further inside the surface are converted into -SO x It can be contained in a larger amount than the S-containing material having the above bond. As a result, the high-temperature cycle life performance of the secondary battery can be improved by the mechanism speculated below. It is speculated that the reaction in which the S-containing material having the C-S bond is generated can suppress the reaction in which by-products such as lithium fluoride (LIF) are generated and mixed into the non-aqueous electrolyte. Therefore, it is speculated that the increase in resistance in a high-temperature environment can be suppressed, and the charge-discharge cycle life in a high-temperature environment can be improved. The lower limit of the ratio (B / A) can be set to a value greater than 0. The lower limit of the ratio (B / A) can be set to, for example, 1 / 50. This can improve the charge-discharge cycle life in a high-temperature environment. A more preferable range of the ratio (B / A) is 1 / 30 or more and 1 / 10 or less.

[0016] The positive electrode, the negative electrode, and the non-aqueous electrolyte will be described below. <Positive electrode> The positive electrode has a positive electrode current collector and a positive electrode active material-containing layer that is supported on one or both sides of the positive electrode current collector and contains a positive electrode active material and a solid electrolyte. The positive electrode active material-containing layer may contain a binder, a conductive agent, or a binder and a conductive agent.

[0017] Examples of the positive electrode active material include metal oxides. Examples of the metal oxides include lithium manganese composite oxides, lithium cobalt composite oxides, lithium nickel composite oxides, lithium nickel cobalt composite oxides, lithium cobalt aluminum composite oxides, lithium nickel aluminum composite oxides, lithium nickel cobalt manganese composite oxides, spinel-structured lithium manganese nickel composite oxides, and lithium manganese cobalt composite oxides. Further, examples of the metal oxides include composite oxides represented by the general formula Li x MO2 (0 < x ≦ 1, M contains at least one element selected from the group consisting of Ni, Co, and Mn), lithium-containing phosphate compounds having an olivine structure, iron fluorosulfate, and Li x Fe 1-a Mn a SO4F (0 < x ≦ 1, 0 ≦ a < 1), etc.

[0018] Examples of the lithium manganese composite oxide include, for example, Li x Mn2O4 (0 < x ≦ 1), Li x MnO2 (0 < x ≦ 1), etc.

[0019] Examples of the lithium cobalt composite oxide include, for example, Li x CoO2 (0 < x ≦ 1), etc.

[0020] Examples of the lithium nickel composite oxide include, for example, Li x NiO2; 0 < x ≦ 1), etc.

[0021] Examples of the lithium cobalt aluminum composite oxide include, for example, Li x Co 1-y Al y O2 (0 < x ≦ 1, 0 < y ≦ 1), etc.

[0022] Examples of the lithium nickel aluminum composite oxide include, for example, Li x Ni 1-y Al y O2 (0 < x ≦ 1, 0 < y ≦ 1), etc.

[0023] Examples of the lithium nickel cobalt composite oxide include, for example, Li x Ni 1-y-z Co y Mn z O2 (0 < x ≤ 1, 0 < y ≤ 1, 0 ≤ z ≤ 1, 0 < 1 - y - z < 1), and the like.

[0024] Examples of the lithium manganese cobalt composite oxide include, for example, Li x Mn y Co 1-y O2 (0 < x ≤ 1, 0 < y < 1), and the like.

[0025] Examples of the spinel structure lithium manganese nickel composite oxide include, for example, Li x Mn 2-y Ni y O4 (0 < x ≤ 1, 0 < y < 2), and the like.

[0026] Examples of the olivine structure lithium-containing phosphate compound include, for example, Li x FePO4 (0 < x ≤ 1), Li x Fe 1-y Mn y PO4 (0 < x ≤ 1, 0 ≤ y ≤ 1), Li x CoPO4 (0 < x ≤ 1), Li x MnPO4 (0 < x ≤ 1), and the like.

[0027] Examples of the iron fluoride sulfate include, for example, Li x FeSO4F (0 < x ≤ 1), and the like.

[0028] Examples of the lithium nickel cobalt manganese composite oxide include, for example, Li x Ni 1-y―z Co y Mn z O2 (0 < x ≤ 1.1, 0 < y ≤ 0.5, 0 < z ≤ 0.5, 0 < 1 - y - z < 1), and the like.

[0029] The type of the positive electrode active material to be used can be one type or two or more types.

[0030] General formula Li x Composite oxide represented by MO2 (0 < x ≤ 1, M contains at least one element selected from the group consisting of Ni, Co, and Mn), Li x Ni 1-y―z Co y Mn z O2 (0 < x ≤ 1.1, 0 < y ≤ 0.5, 0 < z ≤ 0.5, 0 < 1 - y - z < 1) can improve the energy density of the secondary battery.

[0031] The positive electrode active material particles may be in the form of primary particles, secondary particles in which the primary particles are aggregated, or a mixture of primary particles and secondary particles.

[0032] The average primary particle diameter of the positive electrode active material particles can be 0.05 μm or more and 5 μm or less, and a more preferable range is 0.05 μm or more and 3 μm or less. Also, the average secondary particle diameter of the positive electrode active material particles can be 3 μm or more and 20 μm or less.

[0033] The content of the positive electrode active material in the positive electrode active material-containing layer can be, for example, 80% by mass or more and 95% by mass or less.

[0034] The solid electrolyte can be, for example, a solid substance having Li ion conductivity. Having Li ion conductivity as used herein means exhibiting a lithium ion conductivity of 1 × 10 -6 S / cm or more at 25°C. The solid electrolyte can be an inorganic solid electrolyte. Examples of the inorganic solid electrolyte include oxide-based solid electrolytes and sulfide-based solid electrolytes. Specific examples of the inorganic solid electrolyte are as follows.

[0035] As the oxide-based solid electrolyte, it has a NASICON (Sodium (Na) Super Ionic Conductor) type structure and a general formula Li 1+xIt is preferable to use a lithium phosphate solid electrolyte represented by Mα2(PO4)3. Mα in the above general formula is, for example, one or more selected from the group consisting of titanium (Ti), germanium (Ge), strontium (Sr), zirconium (Zr), tin (Sn), aluminum (Al), and calcium (Ca). The subscript x is within the range of 0 ≦ x ≦ 2.

[0036] Specific examples of the lithium phosphate solid electrolyte having a NASICON-type structure include Li 1+x Al x Ti 2-x (PO4)3, an LATP compound represented by 0.1 ≦ x ≦ 0.5; Li 1+x Al y Mβ 2-y (PO4)3, a compound represented by Mβ being one or more selected from the group consisting of Ti, Ge, Sr, Zr, Sn, and Ca, and 0 ≦ x ≦ 1 and 0 ≦ y ≦ 1; Li 1+x Al x Ge 2-x (PO4)3, a compound represented by 0 ≦ x ≦ 2; and, Li 1+x Al x Zr 2-x (PO4)3, a compound represented by 0 ≦ x ≦ 2; Li 1+x+y Al x Mγ 2-x Si y P 3-y O 12 represented by Mγ being one or more selected from the group consisting of Ti and Ge, and 0 < x ≦ 2, 0 ≦ y < 3; Li 1+2x Zr 1-x Ca x (PO4)3, a compound represented by 0 ≦ x < 1 can be mentioned. Li 1+2x Zr 1-x Ca x (PO4)3, the compound represented by is also called LZCP, and as an example, Li 1.2 Zr 1.9 Ca 0.1 (PO4)3 and the like are available.

[0037] In addition, as the oxide-based solid electrolyte, in addition to the above lithium phosphate solid electrolyte, Li x POy N z and 2.6≦x≦3.5, 1.9≦y≦3.8, and 0.1≦z≦1.3. 2.9 PO 3.3 N 0.46 ); Garnet-type structure La 5+x A x La 3-x MδO 12 A is 1 or more selected from the group consisting of Ca, Sr, and Ba, Mδ is 1 or more selected from the group consisting of Nb and Ta, and 0≦x≦0.5; Li3Mδ 2-x L2O 12 wherein Mδ is at least one selected from the group consisting of Nb and Ta, and L may contain Zr, and 0≦x≦0.5; Li 7-3x Al x La3Zr3O 12 and 0≦x≦0.5; Li 5+x La3Mδ 2-x Zr x O 12 where Mδ is at least one selected from the group consisting of Nb and Ta, and 0≦x≦2. LLZ compounds (e.g., Li7La3Zr2O 12 ); and La 2 / 3-x Li x Examples of such compounds include those represented by TiO3, where x is 0.3≦x≦0.7.

[0038] One or more of the above compounds can be used as the solid electrolyte. Two or more of the above solid electrolytes can also be used. Li 1+x Al x Ti 2-x The LATP compound is represented by (PO4)3 and has a value of 0.1≦x≦0.5. 1+2x Zr 1-x Ca xThe LZCP compounds, represented by (PO4)3 and where 0≦x<1, can promote the decomposition reaction at the positive electrode of the non-aqueous electrolyte containing the sultone compound, and therefore can promote the reaction of forming S-containing substances with C-S bonds at the positive electrode. In addition, the LATP compounds and the LZCP compounds have a high affinity for water, and therefore tend to increase the water content of the positive electrode.

[0039] The content of the solid electrolyte in the positive electrode active material-containing layer can be, for example, from 0.5% by mass to 5.0% by mass.

[0040] The form of the solid electrolyte is not particularly limited, but may be, for example, granular, etc. The average particle size of the solid electrolyte particles may be, for example, 0.05 μm or more and 8 μm or less.

[0041] The conductive agent can increase the electronic conductivity of the positive electrode active material-containing layer and suppress the contact resistance with the current collector. Examples of the conductive agent include acetylene black, carbon black, graphite, etc. The type of the conductive agent can be one or more types.

[0042] The content of the conductive agent in the positive electrode active material-containing layer can be, for example, from 3% by mass to 18% by mass.

[0043] The binder can bind the active material and the conductive agent. Examples of the binder include polymers such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluorine-based rubber. The type of binder can be one or more types.

[0044] The content of the binder in the positive electrode active material-containing layer can be, for example, from 2% by mass to 7% by mass.

[0045] The positive electrode active material-containing layer may contain an S-containing substance. Examples of the S-containing substance include an S-containing substance having a C-S bond, -SO x (SO x This includes S-containing substances with CS bonds and -SO groups.x (SO x The S-containing material may have both a cation group and a cation group. The S-containing material may be present in at least a part of the surface of the positive electrode active material-containing layer, or may be present in at least a part of the surface layer portion including the surface of the positive electrode active material-containing layer. According to one example, the surface layer portion of the positive electrode active material-containing layer is a region from the surface of the positive electrode active material-containing layer to a depth detectable by HAXPES (e.g., several tens of nm). The form of the S-containing material is not particularly limited, but examples thereof include a film-like material and a layer-like material.

[0046] The positive electrode current collector is, for example, an aluminum foil or an aluminum alloy foil containing one or more elements selected from Mg, Ti, Zn, Ni, Cr, Mn, Fe, Cu, and Si.

[0047] The thickness of the aluminum foil or aluminum alloy foil is preferably 5 μm or more and 20 μm or less. The lower limit of the thickness can be 15 μm. The purity of the aluminum foil is preferably 99% by mass or more. The content of transition metals such as iron, copper, nickel, and chromium contained in the aluminum foil or aluminum alloy foil is preferably 1% by mass or less.

[0048] The positive electrode current collector may also include a portion on the surface of which the positive electrode active material-containing layer is not formed, and this portion can function as a positive electrode current collecting tab.

[0049] The positive electrode is produced, for example, by suspending a positive electrode active material, a solid electrolyte, a conductive agent, and a binder in a solvent, applying this suspension to a positive electrode current collector, drying, and pressing. <Negative electrode> The negative electrode has a negative electrode current collector and a negative electrode active material-containing layer that is supported on one or both sides of the negative electrode current collector and contains a negative electrode active material. The negative electrode active material-containing layer can contain a binder, a conductive agent, or both a binder and a conductive agent.

[0050] The negative electrode active material can occlude and release lithium ions. The type of negative electrode active material used can be one type or two or more types. Examples of the negative electrode active material include Si, lithium metal, carbon materials, lithium alloy materials, metal oxides, and metal sulfides.

[0051] Examples of carbon materials include graphite, carbon fiber, coke, and graphitizable carbon. Examples of metal sulfides include titanium sulfide, molybdenum sulfide, and iron sulfide. Examples of Li alloys include alloys containing at least one element selected from the group consisting of Si, Al, Sn, Zn, and Pb and Li.

[0052] The metal oxide can be, for example, a metal oxide that inserts and desorbs lithium ions at a potential of 0.5 V (vs. Li / Li + ) or more and 3.0 V (vs. Li / Li + ) or less. Examples of the above metal oxides include titanium-containing oxides and niobium-containing oxides. A secondary battery including a negative electrode containing a negative electrode active material containing at least one of a titanium-containing oxide or a niobium-containing oxide and a positive electrode containing a composite oxide represented by the general formula Li x MO2 (0 < x ≦ 1, M contains at least one element selected from the group consisting of Ni, Co, and Mn)) can achieve a high energy density. A more preferable negative electrode potential range is 0.7 (vs. Li / Li + ) or more and 2 V (vs. Li / Li + ) or less.

[0053] Examples of titanium-containing oxides include lithium titanium-containing oxides and titanium oxides. Examples of niobium-containing oxides include niobium titanium-containing oxides, niobium tungsten-containing oxides, and niobium titanium molybdenum-containing oxides.

[0054] Examples of lithium titanium-containing oxides include those having a spinel structure (for example, the general formula Li 4 / 3+a Ti 5 / 3 O4 (0 ≦ a ≦ 2)), those having a lamellar structure (for example, the general formula Li 2+aTi3O7(0≦a≦1)), Li 1+b Lithium titanium-containing oxide represented by Ti2O4 (0≦b≦1), Li 1.1+b Ti 1.8 Lithium titanium-containing oxide represented by O4 (0≦b≦1), Li 1.07+b Ti 1.86 Examples of the lithium-titanium-containing oxide include a lithium-titanium-containing oxide represented by O4 (0≦b≦1), and a lithium-titanium-containing composite oxide containing at least one element selected from the group consisting of Nb, Mo, W, P, V, Sn, Cu, Ni, and Fe.

[0055] In addition, examples of lithium titanium-containing oxides include Li 2+a A d Ti 6-b B b O 14ーc (A is one or more elements selected from Na, K, Mg, Ca, and Sr, B is a metal element other than Ti, and 0≦a≦5, 0≦b≦6, 0≦c≦0.6, and 0≦d≦3) are included. 2+a A d Ti 6-b B b O 14ーc has a crystal structure in the space group Cmca.

[0056] Another example of the lithium titanium-containing oxide is an orthorhombic titanium-containing oxide. 2+a M I 2-b Ti 6-c M II d O 14+σ In this case, the compound represented by M I is at least one selected from the group consisting of Sr, Ba, Ca, Mg, Na, Cs, Rb and K. IIis at least one selected from the group consisting of Zr, Sn, V, Nb, Ta, Mo, W, Y, Fe, Co, Cr, Mn, Ni, and Al. The subscripts in the composition formula are 0≦a≦6, 0≦b<2, 0≦c<6, 0≦d<6, and -0.5≦σ≦0.5. Specific examples of orthorhombic titanium-containing composite oxides include Li 2+a Na2Ti6O 14 (0≦a≦6).

[0057] Examples of titanium oxides include those with the general formula Li a Titanium oxides represented by TiO2 (0≦a≦2) are included. In this case, the composition formula before charging is TiO2. Examples of titanium oxides include titanium oxides with a monoclinic structure (bronze structure (B)), titanium oxides with a rutile structure, titanium oxides with anatase structure, etc. TiO2(B) with a monoclinic structure (bronze structure (B)) is preferred. Low-crystalline TiO2(B) with a heat treatment temperature of 300 to 600°C is also preferred.

[0058] Examples of the niobium-containing oxide include niobium oxide, niobium titanium-containing oxide, niobium tungsten-containing oxide, and niobium titanium molybdenum-containing oxide.

[0059] Examples of niobium oxides include Nb2O5.

[0060] Examples of niobium titanium oxides include monoclinic niobium titanium oxides, Ti2Nb2O9, Ti2Nb 10 O 29 , TiNb 14 O 37 , TiNb 24 O 62 The substituted niobium titanium composite oxides include those in which at least a portion of Nb and / or Ti is substituted with a different element. Examples of the substituting element include Na, K, Ca, Co, Ni, Si, P, V, Cr, Mo, Ta, Zr, Mn, Fe, Mg, B, Pb, and Al. The substituted niobium titanium composite oxides may contain one type of substituting element, or may contain two or more types of substituting elements.

[0061] Examples of monoclinic niobium titanium oxides include those represented by the general formula Li c TiNb d O7 (0≦c≦5, 1≦d≦4). A more preferred composition is TiNb2O7.

[0062] As an example of a monoclinic niobium titanium oxide, Li x Ti 1-y M1 y Nb 2-z M2 z O 7+δ Here, M1 is at least one selected from the group consisting of Zr, Si, and Sn. M2 is at least one selected from the group consisting of V, Ta, and Bi. The subscripts in the composition formula are 0≦x≦5, 0≦y<1, 0≦z<2, and -0.3≦δ≦0.3.

[0063] Another example of a monoclinic niobium titanium oxide is Ti 1-y M3 y+z Nb 2-z O 7-δ Here, M3 is at least one selected from Mg, Fe, Ni, Co, W, Ta, and Mo. The subscripts in the composition formula are 0≦y<1, 0≦z<2, and -0.3≦δ≦0.3.

[0064] Examples of niobium tungsten-containing oxides include Nb 14 W3O 44 , Nb 16 W5O 55 ,Nb 18 W8O 69 etc.

[0065] Examples of niobium titanium molybdenum-containing oxides include those having the general formula Li a Ti b Nb 2-2d Mo c+2d O 2b+5+3c(wherein the subscripts a, b, c, and d are preferably within the ranges of 0≦a≦b+4+3c, 0.3≦b≦1.6, 0.3≦c<1.6, and 0≦d<0.4, respectively), and a tetragonal titanium-niobium-molybdenum composite oxide represented by the general formula Li a M b NbMo c O d where M is one or more selected from the group consisting of Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y, and Si, and includes composite oxides in which 0≦a≦b+2+3c, 0≦b≦1.4, 0≦c≦0.5, and 2.33≦d / (1+b+c)≦2.50 are satisfied.

[0066] Li 4 / 3+a Ti 5 / 3 O4(0≦a≦2) or Li c TiNb d A negative electrode active material containing at least one of O7 (0≦c≦5, 1≦d≦4) can rapidly absorb and release lithium ions inside the active material and is electrochemically and chemically stable against a non-aqueous electrolyte, and therefore has excellent large-current discharge performance, rapid charge performance, and cycle life performance.

[0067] The negative electrode active material particles may be in the form of primary particles, or may be in the form of secondary particles formed by agglomeration of primary particles, or may be a mixture of primary particles and secondary particles.

[0068] The average particle size of the primary particles of the negative electrode active material is preferably in the range of 0.05 to 1 μm. This can improve the large current performance. In addition, the particle shape can be either granular or fibrous to obtain good performance. In addition, when the negative electrode active material forms secondary particles, the average particle size of the secondary particles is preferably 2 to 20 μm. This can increase the electrode density and improve the cycle life performance.

[0069] The content of the negative electrode active material in the negative electrode active material-containing layer can be, for example, from 80% by mass to 95% by mass.

[0070] The porosity of the negative electrode (excluding the current collector) is preferably in the range of 20 to 50%. This allows a high-density negative electrode to be obtained that has excellent affinity between the negative electrode and the non-aqueous electrolyte. The porosity is more preferably in the range of 25 to 40%.

[0071] The negative electrode active material-containing layer may contain a conductive agent. Examples of the conductive agent include carbon nanotubes, acetylene black, carbon black, coke (preferably with an average particle size of 10 μm or less at a heat treatment temperature of 800° C. to 2000° C.), carbon fiber, graphite, metal compound powders such as TiO, TiC, and TiN, and metal powders such as Al, Ni, Cu, and Fe. The conductive agent may be one or more kinds. By using carbon fiber with a fiber diameter of 1 μm or less, the electrode resistance is reduced and the cycle life performance is improved.

[0072] The content of the conductive agent in the negative electrode active material-containing layer can be, for example, from 1% by mass to 18% by mass.

[0073] The negative electrode active material-containing layer may contain a binder. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-based rubber, acrylic rubber, styrene butadiene rubber, core-shell binder, polyimide, and cellulose nanofiber. The type of binder may be one or more.

[0074] The content of the binder in the negative electrode active material-containing layer can be, for example, from 2% by mass to 7% by mass.

[0075] The negative electrode active material-containing layer may contain a solid electrolyte. The type, form, and other details of the solid electrolyte may be the same as those described for the positive electrode. The solid electrolyte contained in the positive electrode and the solid electrolyte contained in the negative electrode may be the same type or different from each other.

[0076] The content of the solid electrolyte in the negative electrode active material-containing layer can be, for example, from 0.5% by mass to 5.0% by mass.

[0077] The negative electrode current collector is different depending on the type of negative electrode active material. When Si, lithium alloy, or carbon material is used as the negative electrode active material, copper foil can be used for the negative electrode current collector. Lithium ions can be added to the negative electrode active material at 0.5 to 3.0 V (vs. Li / Li + When a metal oxide that is inserted and removed at a potential of 0.1 V is used, the negative electrode current collector can contain at least one of aluminum and an aluminum alloy. More preferred negative electrode current collectors are aluminum foil and aluminum alloy foil. The purity of the aluminum foil is preferably 99.99% by mass or more. The aluminum alloy is preferably an alloy containing elements such as magnesium, zinc, and silicon. On the other hand, the transition metals such as iron, copper, nickel, and chromium are preferably 100 ppm by mass or less.

[0078] The thickness of the negative electrode current collector is preferably 20 μm or less, and more preferably 15 μm or less.

[0079] The negative electrode is produced, for example, by suspending a negative electrode active material, a conductive agent, and a binder in a solvent, applying this suspension to a current collector, drying, and pressing. (Non-aqueous electrolyte) As the non-aqueous electrolyte, for example, a liquid non-aqueous electrolyte, a gel non-aqueous electrolyte, a solid non-aqueous electrolyte, or the like can be used.

[0080] The liquid nonaqueous electrolyte may include an organic solvent and an electrolyte salt. The electrolyte salt may be dissolved in the organic solvent and function as a solute. The concentration of the electrolyte salt may be, for example, 0.5 mol / L or more and 2.5 mol / L or less.

[0081] Examples of the electrolyte salt include lithium salts such as lithium perchlorate (LiClO4), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), and lithium bistrifluoromethylsulfonylimide (LiN(CF3SO2)2), and mixtures thereof. The electrolyte salt is preferably one that is difficult to oxidize even at high potentials, and LiPF6 is most preferred.

[0082] Examples of the organic solvent include cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), and vinylene carbonate (VC); chain carbonates such as diethyl carbonate (DEC), dimethyl carbonate (DMC), and methyl ethyl carbonate (MEC); cyclic ethers such as tetrahydrofuran (THF), 2-methyl tetrahydrofuran (2MeTHF), and dioxolane (DOX); chain ethers such as dimethoxyethane (DME) and diethoxyethane (DEE); γ-butyrolactone (GBL), acetonitrile (AN), sulfolane (SL), and ethyl propionate (ethyl propionate (EP), propyl propionate (PP), and ethyl butyrate (EB). These organic solvents can be used alone or as a mixed solvent.

[0083] The liquid nonaqueous electrolyte may contain a component other than the above (hereinafter referred to as the second component). Examples of the second component include a sultone compound, a phosphoric acid compound, and tetraethenylsilane. The second component may contribute to reducing the resistance of the secondary battery or improving the high-temperature life performance. The second component may also serve as an organic solvent, or may exist as a solute. The type of the second component may be one or more.

[0084] Examples of the sultone compound include 1,3-propane sultone (PS), 1,4-butane sultone, 1,3-propene sultone, and 2,4-butane sultone. The sultone compound may contain one selected from the group consisting of these compounds, or may contain two or more of them in combination. The sultone compound can cause a decomposition reaction before other non-aqueous electrolyte components (e.g., organic solvents) cause a decomposition reaction, thereby suppressing gas generation. 1,3-propane sultone can generate an S-containing substance having a C-S bond at the positive electrode by reacting with the positive electrode containing a solid electrolyte containing at least one of an LATP compound or an LZCP compound.

[0085] An example of a phosphate compound is lithium difluorophosphate (DFP), which can promote the formation of S-containing compounds with C-S bonds.

[0086] The content of at least one of the sultone compound and the phosphate compound in the liquid nonaqueous electrolyte can be, for example, 0.5% by mass to 5.0% by mass, in which case the high-temperature life performance can be improved.

[0087] The gelled non-aqueous electrolyte may be, for example, a composite of a liquid non-aqueous electrolyte and a polymeric material, such as polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyethylene oxide (PEO), or a mixture thereof.

[0088] Alternatively, as the nonaqueous electrolyte, in addition to liquid nonaqueous electrolytes and gel nonaqueous electrolytes, room temperature molten salts containing lithium ions (ionic melts), polymer solid electrolytes, inorganic solid electrolytes, and the like may be used.

[0089] 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 non-aqueous electrolyte. The secondary battery of the embodiment may include a positive electrode terminal and a negative electrode terminal. The negative electrode, the positive electrode, and the separator can constitute an electrode group. The non-aqueous electrolyte can be held in the electrode group. The shape of the electrode group is not particularly limited, and can be, for example, a stacked type or a wound type. The secondary battery of the embodiment can be applied to secondary batteries of various shapes such as a rectangular type, a cylindrical type, a flat type, a thin type, and a coin type. (Separator) The separator is disposed between the positive electrode and the negative electrode. A part of the separator may face or be in contact with only the positive electrode or only the negative electrode.

[0090] Examples of the separator include synthetic resin (for example, polyolefin such as polyethylene or polypropylene) nonwoven fabric, polyethylene porous film, polypropylene porous film, cellulose nonwoven fabric, and the like.

[0091] At least a portion of the surface of the separator may be covered with a layer containing inorganic particles such as alumina or a resin such as aramid. (Exterior materials) At least a positive electrode, a negative electrode, and a non-aqueous electrolyte are housed in the exterior member. The positive electrode and the negative electrode may be housed in the exterior member in the form of an electrode group with a separator or the like disposed between them.

[0092] The exterior member may be a metal container or a laminated film container.

[0093] The metal container may be a rectangular or cylindrical metal can made of aluminum, aluminum alloy, iron, stainless steel, etc. The metal container may be provided with a lid. The thickness of the container is preferably 0.5 mm or less, more preferably 0.3 mm or less.

[0094] The laminate film may be, for example, a multi-layer film in which an aluminum foil is coated 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. The purity of the aluminum foil is preferably 99.5% or more.

[0095] The metal can made of an aluminum alloy is preferably an alloy containing elements such as manganese, magnesium, zinc, and silicon with an aluminum purity of 99.8% or less. The strength of the metal can made of an aluminum alloy is dramatically increased, allowing the can wall thickness to be reduced. As a result, a battery that is thin, lightweight, high-power, and excellent in heat dissipation can be realized. (Negative terminal) The negative electrode terminal can be made of a material that is electrochemically stable at the Li absorption / release potential of the negative electrode active material and has electrical conductivity. Specifically, the material of the negative electrode terminal can be copper, nickel, stainless steel, aluminum, or an aluminum alloy containing at least one element selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si. The material of the negative electrode terminal is preferably aluminum or an aluminum alloy. The negative electrode terminal is preferably made of the same material as the negative electrode current collector in order to reduce the contact resistance with the negative electrode current collector. (Positive terminal) The positive electrode terminal has a potential range of 3V to 4.5V with respect to the redox potential of lithium (vs. Li / Li + ) and can be formed from a material that is electrically stable and conductive. Examples of the material for the positive electrode terminal include stainless steel, nickel, aluminum, and an aluminum alloy containing at least one element selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si. The positive electrode terminal is preferably formed from the same material as the positive electrode current collector in order to reduce the contact resistance with the positive electrode current collector.

[0096] The analysis of the positive electrode by HAXPES, the method for confirming S content, and the method for confirming sultone compounds are described below.

[0097] First, when the electrode to be measured (positive electrode or negative electrode) is incorporated in a battery, the electrode to be measured is removed from the battery as follows. First, the battery containing the electrode is disassembled in a glove box filled with argon. The electrode to be measured is removed from the disassembled battery. This electrode is washed with an appropriate solvent. For example, methyl ethyl carbonate can be used as the solvent used for washing. The washed electrode is vacuum dried. In this way, the electrode to be measured is obtained. <haxpes> The electrode (e.g., the positive electrode) extracted by the above method is attached to the HAXPES sample folder with carbon tape in a glove box filled with argon. The sample folder is placed in a transfer vessel, sealed, and the vessel is taken out of the glove box and attached to the sample inlet of the HAXPES device. By transferring the sample folder inside the device, the electrode sample is introduced into the device without being exposed to the atmosphere. HAXPES analysis is performed as follows. The energy is calibrated at Au4f7 / 2 (5870 eV) and then measurement is performed. The excitation energy is 5947.51 eV. The beam size is 20 μm vertical × 30 μm horizontal. The electron analyzer (Scienta Omicron R4000 L1) is set to 12 keV. The photoelectron detection angle is approximately 89° and the oblique incidence configuration is used. Charge neutralization is not used.

[0098] An example of an S1s spectrum obtained by HAXPES is shown in Figure 10. Figure 10 is an S1s spectrum obtained by HAXPES of the positive electrode of Example 1. The horizontal axis of the S1s spectrum represents binding energy (eV), and the vertical axis represents intensity (normalized).

[0099] In the S1s spectrum obtained by HAXPES, the line connecting the intensities of 2483 eV and 2468 eV is taken as the baseline. In the S1s spectrum shown in Figure 10, the baseline is indicated by the symbol L. Anything detected above the baseline is taken as a peak. The peak height (peak intensity) is the difference in intensity between the baseline and the peak top.

[0100] In the case of FIG. 10, since the number of peaks appearing in the range of the binding energy of 2468 eV or more and 2474 eV or less is one, this peak is taken as the maximum peak and the first peak. The intensity difference between the peak top of the first peak and the baseline L is the intensity (height) A of the first peak. On the other hand, in the range of the binding energy of 2475 eV or more and 2483 eV or less, a plurality of peaks appear. For each of these peaks, the intensity difference between the peak top and the baseline is obtained, the obtained values are compared, and the peak having the maximum intensity (maximum height) is taken as the maximum peak and the second peak. In the case of FIG. 10, the peak appearing at 2478 eV is the second peak. The peak intensity of the second peak is indicated by B.

[0101] Therefore, when there is one peak appearing in the binding energy range defined above, that peak is taken as the first peak or the second peak. Further, when there are a plurality of peaks appearing in the binding energy range defined above, the peak having the maximum intensity (maximum height) appearing in the range of the binding energy of 2468 eV or more and 2474 eV or less is taken as the maximum peak and the first peak. Also, the peak having the maximum intensity (maximum height) appearing in the range of the binding energy of 2475 eV or more and 2483 eV or less is taken as the maximum peak and the second peak. <Method for Confirming S-containing Substances> Whether or not an S-containing substance is present in the positive electrode active material-containing layer can be confirmed by whether or not a maximum peak is detected in the S1s spectrum obtained by HAXPES in the range of the binding energy of 2468 eV or more and 2483 eV or less. <Method for Confirming Sulfone Compounds> The non-aqueous electrolyte (for example, non-aqueous electrolyte solution) is diluted 20 times in volume with acetonitrile to obtain a measurement sample. By performing gas chromatography mass spectrometry (GC-MS) measurement on the measurement sample under the conditions shown in Table 1, the concentration (mass%) of propane sulfone in the non-aqueous electrolyte can be specified.

[0102]

Table 1

[0103] An example of a method for manufacturing the secondary battery according to the embodiment will be described below.

[0104] An example of a method for manufacturing a secondary battery includes preparing a positive electrode, preparing a negative electrode, preparing a non-aqueous electrolyte containing a sultone compound, housing the positive electrode and the negative electrode in an exterior member, drying the positive electrode and the negative electrode so that the moisture loss rate of the positive electrode is 30% by mass or more and 60% by mass or less, injecting the non-aqueous electrolyte into the exterior member, sealing the exterior member to obtain a battery precursor, subjecting the battery precursor to an initial charge and discharge, and subjecting the battery precursor to aging. After aging, generated gas can be removed from the battery as appropriate.

[0105] The positive electrode and the negative electrode can be prepared by, for example, the following method. For the positive electrode, first, an active material, a solid electrolyte, 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. Then, the applied slurry is dried to obtain a laminate of an active material-containing layer and a current collector. Then, the laminate is pressed. In this manner, a positive electrode is prepared. On the other hand, for the negative electrode, an 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. Then, the applied slurry is dried to obtain a laminate of an active material-containing layer and a current collector. Then, the laminate is pressed. In this manner, a negative electrode is prepared.

[0106] The drying of the positive electrode and the negative electrode housed in the exterior member is performed with a part of the exterior member open. The moisture loss rate of the positive electrode before and after drying can be 30% by mass or more and 60% by mass or less. By setting the moisture loss rate of the positive electrode due to drying to 30% by mass or more, the positive electrode can be dried appropriately. In addition, by setting the moisture loss rate of the positive electrode due to drying to 60% by mass or less, excessive drying of the positive electrode can be avoided. The sultone compound can be decomposed during the initial charge / discharge or in a subsequent process (e.g., aging). By setting the moisture loss rate of the positive electrode due to drying within the above range, the decomposition of the sultone compound can be promoted, and the sultone compound can be decomposed to C-S bonds to form an S-containing coating on the positive electrode active material-containing layer.

[0107] The moisture loss rate of the positive electrode can be measured by the Karl Fischer method with a moisture vaporizer. Cut the positive electrode before and after drying to obtain a pre-drying sample and a post-drying sample. The samples are collected so that the weight of the sample is in the range of 0.1 to 1 g. The weights of the obtained pre-drying sample and post-drying sample are measured. The weighted samples are placed on a boat of a moisture vaporizer and heated to 130°C. The amount of vaporized moisture is measured by the Karl Fischer method to determine the moisture content of the pre-drying sample and the post-drying sample. The moisture loss rate W (mass%) of the positive electrode is calculated using the obtained values ​​according to the following formula.

[0108] W=(Z2 / Z1)*100 W is the moisture loss rate (mass%) of the positive electrode due to drying, Z1 is the moisture content of the sample before drying, and Z2 is the moisture content of the sample after drying.

[0109] The drying temperature can be, for example, in the range of 80° C. to 150° C. When the drying temperature is 80° C. to 150° C., the drying time can be, for example, 1 hour to 72 hours. Furthermore, the drying can be performed by vacuum drying or reduced pressure drying.

[0110] The moisture loss rate of the positive electrode due to drying can be set within a predetermined range by adjusting, for example, the drying temperature, drying time, drying atmosphere, the type of positive electrode active material and solid electrolyte used in the positive electrode, and the like.

[0111] An example of a secondary battery according to an embodiment will be described with reference to FIGS.

[0112] 1 and 2 show an example of a secondary battery using a metal container.

[0113] The electrode group 1 is housed in a rectangular cylindrical metal container 2. The electrode group 1 has a structure in which a separator 5 is interposed between a positive electrode active material-containing layer of a positive electrode 3 and a negative electrode active material-containing layer of a negative electrode 4, and these are wound in a spiral shape to form a flat shape. The separator 5 covers the surface of the positive electrode active material-containing layer or the negative electrode active material-containing layer. As shown in FIG. 2, a strip-shaped positive electrode lead 6 is electrically connected to each of a plurality of points on the end of the positive electrode 3 located on the end face of the electrode group 1. In addition, a strip-shaped negative electrode lead 7 is electrically connected to each of a plurality of points on the end of the negative electrode 4 located on this end face. The plurality of positive electrode leads 6 are electrically connected to a positive electrode conductive tab 8 in a bundled state. The positive electrode lead 6 and the positive electrode conductive tab 8 constitute a positive electrode terminal. In addition, the negative electrode lead 7 is connected to a negative electrode conductive tab 9 in a bundled state. The negative electrode lead 7 and the negative electrode conductive tab 9 constitute a negative electrode terminal. A metallic sealing plate 10 is fixed to the opening of the metallic container 2 by welding or the like. The positive electrode conductive tab 8 and the negative electrode conductive tab 9 are each pulled out to the outside through an extraction hole provided in the sealing plate 10. The inner circumferential surface of each extraction hole in the sealing plate 10 is covered with an insulating member 11 to prevent a short circuit due to contact with the positive electrode conductive tab 8 and the negative electrode conductive tab 9.

[0114] 3 and 4 show an example of a secondary battery using an exterior member made of a laminate film.

[0115] As shown in FIG. 3 and FIG. 4, the flat wound electrode group 1 is housed in a bag-shaped exterior member 12 made of a laminate film in which a metal layer is interposed between two resin films. The flat wound electrode group 1 is formed by spirally winding a laminate in which a negative electrode 4, a separator 15, a positive electrode 3, and a separator 15 are laminated from the outside in this order, and press-molding the laminate. The outermost negative electrode 4 has a configuration in which a negative electrode active material-containing layer 4b containing a negative electrode active material is formed on one side of the inner surface side of a negative electrode current collector 4a as shown in FIG. 4, and the other negative electrodes 4 are configured by forming a negative electrode active material-containing layer 4b on both sides of a negative electrode current collector 4a. The positive electrode 3 is configured by forming a positive electrode active material-containing layer 3b on both sides of a positive electrode current collector 3a.

[0116] Near the outer peripheral end of the wound electrode group 1, the negative electrode terminal 13 is connected to the negative electrode current collector 4a of the outermost negative electrode 4, and the positive electrode terminal 14 is connected to the positive electrode current collector 3a of the inner positive electrode 3. These negative electrode terminal 13 and positive electrode terminal 14 extend outward from an opening of the bag-shaped exterior member 12. The opening of the bag-shaped exterior member 12 is heat-sealed to seal the wound electrode group 1. When heat-sealing, the negative electrode terminal 13 and positive electrode terminal 14 are sandwiched by the bag-shaped exterior member 12 at this opening.

[0117] The secondary battery of the embodiment described above includes a positive electrode containing a positive electrode active material and a solid electrolyte. The positive electrode satisfies the following formula (1) in an S1s spectrum by hard X-ray photoelectron spectroscopy.

[0118] B / A≦1 / 3 (1) Here, A is the intensity of the maximum peak appearing in the binding energy range of 2468 eV to 2474 eV in the S1s spectrum, and B is the intensity of the maximum peak appearing in the binding energy range of 2475 eV to 2483 eV in the S1s spectrum.

[0119] The secondary battery of the embodiment can achieve an excellent high-temperature charge-discharge cycle life. Second embodiment The battery pack of the second embodiment includes a plurality of the secondary batteries of the embodiment.

[0120] Examples of the assembled battery include one including a plurality of unit cells electrically connected in series and / or in parallel as a constituent unit, one including a first unit including a plurality of unit cells electrically connected in series or a second unit including a plurality of unit cells electrically connected in parallel, etc. The assembled battery may include at least one of these configurations.

[0121] Examples of the configuration in which a plurality of secondary batteries are electrically connected in series and / or in parallel include a configuration in which a plurality of batteries each having an exterior member are electrically connected in series and / or in parallel, and a configuration in which a plurality of electrode groups or bipolar electrode bodies housed in a common case are electrically connected in series and / or in parallel. A specific example of the former is a configuration in which the positive and negative terminals of a plurality of secondary batteries are connected by a metal bus bar (e.g., aluminum, nickel, copper). A specific example of the latter is a configuration in which a plurality of electrode groups or bipolar electrode bodies are housed in one case in a state in which they are electrochemically insulated by a partition wall, and these are electrically connected in series. In the case of a secondary battery, by setting the number of batteries electrically connected in series to the range of 5 to 7, the voltage compatibility with a lead-acid battery is improved. In order to further increase the voltage compatibility with a lead-acid battery, a configuration in which 5 or 6 unit cells are connected in series is preferable.

[0122] The case that houses the battery pack can be a metal can made of aluminum alloy, iron, stainless steel, etc., a plastic container, etc. The plate thickness of the container is preferably 0.5 mm or more.

[0123] An example of a battery pack will be described with reference to Fig. 5. Battery pack 200 shown in Fig. 5 includes a plurality of unit cells, each of which is a rectangular secondary battery 1001-1005 shown in Fig. 1. Positive electrode conductive tab 8 of battery 1001 and negative electrode conductive tab 9 of battery 1002 positioned adjacent thereto are electrically connected by a lead or bus bar 21. Furthermore, positive electrode conductive tab 8 of battery 1002 and negative electrode conductive tab 9 of battery 1003 positioned adjacent thereto are electrically connected by a lead or bus bar 21. In this manner, batteries 1001-1005 are connected in series.

[0124] The battery pack of the second embodiment described above includes the secondary batteries of the embodiment, and therefore can achieve an excellent high-temperature charge-discharge cycle life. [Third embodiment] The battery pack according to the third embodiment may include one or more secondary batteries (single cells) according to the embodiment. The secondary batteries may be electrically connected in series, in parallel, or in a combination of series and parallel to form a battery pack. The battery pack according to the embodiment may include a plurality of battery packs.

[0125] 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.

[0126] 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 inputting current to the secondary battery. In other words, when the battery pack is used as a power source, current is supplied to the outside through the external terminal for current flow. When charging the battery pack, a charging current (including regenerative energy of the power of a vehicle such as an automobile) is supplied to the battery pack through the external terminal for current flow.

[0127] Next, an example of a battery pack according to an embodiment will be described with reference to the drawings.

[0128] Fig. 6 is an exploded perspective view showing an example of a battery pack according to an embodiment of the present invention, and Fig. 7 is a block diagram showing an example of an electric circuit of the battery pack shown in Fig. 6.

[0129] The battery pack 300 shown in Figs. 6 and 7 includes a container 31, a lid 32, a protective sheet 33, a battery pack 200, a printed wiring board 34, wiring 35, and an insulating plate (not shown).

[0130] 6 is a bottomed, square container having a rectangular bottom. The container 31 is configured to be able to accommodate a protective sheet 33, a battery pack 200, a printed wiring board 34, and wiring 35. The lid 32 has a rectangular shape. The lid 32 covers the container 31 to accommodate the battery pack 200 and the like. Although not shown, the container 31 and the lid 32 are provided with openings or connection terminals for connection to an external device or the like.

[0131] The battery pack 200 includes a plurality of cells 100, a positive electrode lead 22, a negative electrode lead 23, and an adhesive tape 24.

[0132] At least one of the plurality of unit cells 100 is a secondary battery according to the embodiment. Each of the plurality of unit cells 100 is electrically connected in series as shown in FIG. 7. The plurality of unit cells 100 may be electrically connected in parallel, or may be connected in a combination of series and parallel connections. When the plurality of unit cells 100 are connected in parallel, the battery capacity is increased compared to when they are connected in series.

[0133] The adhesive tape 24 fastens the plurality of unit cells 100. The plurality of unit cells 100 may be fixed using heat shrink tape instead of the adhesive tape 24. In this case, the protective sheets 33 are disposed on both side surfaces of the battery pack 200, the heat shrink tape is wrapped around the battery pack 200, and the heat shrink tape is then thermally shrunk to bind the plurality of unit cells 100 together.

[0134] One end of the positive electrode lead 22 is connected to the battery pack 200. One end of the positive electrode lead 22 is electrically connected to the positive electrode of one or more cells 100. One end of the negative electrode lead 23 is connected to the battery pack 200. One end of the negative electrode lead 23 is electrically connected to the negative electrode of one or more cells 100.

[0135] The printed wiring board 34 is disposed along one of the short side surfaces of the inner surface of the container 31. The printed wiring board 34 includes a positive connector 342, a negative connector 343, a thermistor 345, a protection circuit 346, wiring 342a and 343a, an external terminal 350 for supplying electricity, a positive wiring (positive wiring) 348a, and a negative wiring (negative wiring) 348b. One main surface of the printed wiring board 34 faces one side of the battery pack 200. An insulating plate (not shown) is interposed between the printed wiring board 34 and the battery pack 200.

[0136] The other end 22a of the positive electrode lead 22 is electrically connected to the positive electrode connector 342. The other end 23a of the negative electrode lead 23 is electrically connected to the negative electrode connector 343.

[0137] The thermistor 345 is fixed to one main surface of the printed wiring board 34. The thermistor 345 detects the temperature of each of the cells 100, and transmits a detection signal to a protection circuit 346.

[0138] The external terminal 350 for current supply is fixed to the other main surface of the printed wiring board 34. The external terminal 350 for current supply is electrically connected to a device present outside the battery pack 300. The external terminal 350 for current supply includes a positive terminal 352 and a negative terminal 353.

[0139] The protection circuit 346 is fixed to the other main surface of the printed wiring board 34. The protection circuit 346 is connected to the positive terminal 352 via a positive wiring 348a. The protection circuit 346 is connected to the negative terminal 353 via a negative wiring 348b. The protection circuit 346 is also electrically connected to the positive electrode connector 342 via a wiring 342a. The protection circuit 346 is electrically connected to the negative electrode connector 343 via a wiring 343a. Furthermore, the protection circuit 346 is electrically connected to each of the plurality of single cells 100 via the wiring 35.

[0140] The protective sheet 33 is disposed on both inner surfaces in the long side direction of the container 31 and on the inner surface in the short side direction that faces the printed wiring board 34 via the battery pack 200. The protective sheet 33 is made of, for example, resin or rubber.

[0141] The protection circuit 346 controls charging and discharging of the multiple cells 100. In addition, the protection circuit 346 cuts off electrical connection between the protection circuit 346 and external terminals 350 (positive terminal 352, negative terminal 353) for supplying electricity to an external device, based on a detection signal transmitted from the thermistor 345, or a detection signal transmitted from each of the cells 100 or the battery pack 200.

[0142] An example of the detection signal transmitted from the thermistor 345 is a signal that detects that the temperature of the cell 100 is equal to or higher than a predetermined temperature. An example of the detection signal transmitted from each cell 100 or the battery pack 200 is a signal that detects overcharging, overdischarging, and overcurrent of the cell 100. When detecting overcharging or the like for each cell 100, 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 cell 100.

[0143] The protection circuit 346 may be a circuit included in a device (such as an electronic device or an automobile) that uses the battery pack 300 as a power source.

[0144] As described above, the battery pack 300 includes the external terminal 350 for current supply. Therefore, the battery pack 300 can output a current from the assembled battery 200 to an external device and input a current from the external device to the assembled battery 200 via the external terminal 350 for current supply. In other words, when the battery pack 300 is used as a power source, the current from the assembled battery 200 is supplied to the external device through the external terminal 350 for current supply. When the battery pack 300 is charged, a charging current from the external device is supplied to the battery pack 300 through the external terminal 350 for current supply. When the battery pack 300 is used as an in-vehicle battery, regenerative energy of the vehicle's power can be used as the charging current from the external device.

[0145] The battery pack 300 may include a plurality of assembled batteries 200. In this case, the plurality of assembled batteries 200 may be connected in series, in parallel, or in a combination of series and parallel connections. The printed wiring board 34 and the wiring 35 may be omitted. In this case, the positive electrode lead 22 and the negative electrode lead 23 may be used as a positive terminal and a negative terminal, respectively, of the external terminals for current supply.

[0146] Such a battery pack is used in applications that require excellent cycle performance, for example, when a large current is drawn. Specifically, the battery pack is used, for example, as a power source for electronic devices, a stationary battery, or an on-board battery for various vehicles (including a battery for railway vehicles). An example of the electronic device is a digital camera. The battery pack is particularly suitable for use as an on-board battery.

[0147] The battery pack according to the embodiment includes the secondary battery according to the embodiment or the battery pack according to the embodiment, and therefore, a battery pack having excellent cycle life performance at high temperatures can be realized.

[0148] [Fourth embodiment] According to a fourth embodiment, a vehicle is provided. The vehicle is equipped with a secondary battery, a battery assembly, or a battery pack according to the embodiment.

[0149] In the vehicle according to the fourth embodiment, the battery pack, for example, recovers regenerative energy of the vehicle's motive power. The vehicle may include a mechanism (for example, a regenerator) that converts the kinetic energy of the vehicle into regenerative energy.

[0150] Examples of the vehicle according to the fourth embodiment include a two-wheeled to four-wheeled hybrid electric vehicle, a two-wheeled to four-wheeled electric vehicle, an electric-assisted bicycle, and a railroad car.

[0151] The mounting position of the battery pack in the vehicle according to the fourth embodiment 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.

[0152] The vehicle according to the fourth embodiment may be equipped with a plurality of battery packs. In this case, the batteries included in each battery pack may be electrically connected in series, electrically connected in parallel, or electrically connected in a combination of series and parallel connections. For example, when each battery pack includes a battery pack, the battery packs may be electrically connected in series, electrically connected in parallel, or electrically connected in a combination of series and parallel connections. Alternatively, when each battery pack includes a single battery, the batteries may be electrically connected in series, electrically connected in parallel, or electrically connected in a combination of series and parallel connections.

[0153] Next, an example of a vehicle according to a fourth embodiment will be described with reference to the drawings.

[0154] FIG. 8 is a partial see-through view that illustrates an example of a vehicle according to the fourth embodiment.

[0155] A vehicle 400 shown in Fig. 8 includes a vehicle body 40 and a battery pack 300 according to the embodiment. In the example shown in Fig. 8, the vehicle 400 is a four-wheeled automobile.

[0156] The vehicle 400 may be equipped with a plurality of battery packs 300. In this case, the batteries (e.g., single cells or assembled batteries) included in the battery pack 300 may be connected in series, in parallel, or in a combination of series and parallel connections.

[0157] 8 illustrates an example in which the battery pack 300 is mounted in an engine room located in the front of the vehicle body 40. As described above, the battery pack 300 may be mounted, for example, in the rear of the vehicle body 40 or under a seat. This battery pack 300 can be used as a power source for the vehicle 400. In addition, this battery pack 300 can recover regenerative energy for the motive power of the vehicle 400.

[0158] Next, an embodiment of a vehicle according to a fifth embodiment will be described with reference to FIG.

[0159] Fig. 9 is a diagram illustrating an example of a control system for an electrical system in a vehicle according to an embodiment. A vehicle 400 illustrated in Fig. 9 is an electric vehicle.

[0160] The vehicle 400 shown in FIG. 9 comprises a vehicle body 40, a vehicle power supply 41, a vehicle ECU (ECU: Electric Control Unit) 42 which is a higher-level control device of the vehicle power supply 41, an external terminal (terminal for connecting to an external power supply) 43, an inverter 44, and a drive motor 45.

[0161] The vehicle 400 has a vehicle power supply 41 mounted, for example, in an engine compartment, the rear of the vehicle body, or under a seat. Note that in the vehicle 400 shown in Fig. 9, the mounting location of the vehicle power supply 41 is shown diagrammatically.

[0162] The vehicle power supply 41 includes a plurality of (eg, three) battery packs 300a, 300b, and 300c, a battery management unit (BMU) 411, and a communication bus 412.

[0163] The battery pack 300a includes an assembled battery 200a and an assembled battery monitoring device 301a (for example, VTM: Voltage Temperature Monitoring). The battery pack 300b includes an assembled battery 200b and an assembled battery monitoring device 301b. The battery pack 300c includes an assembled battery 200c and an assembled battery monitoring device 301c. The battery packs 300a to 300C are battery packs similar to the above-mentioned battery pack 300, and the assembled batteries 200a to 200c are assembled batteries similar to the above-mentioned battery pack 200. The assembled batteries 200a to 200c are electrically connected in series. The battery packs 300a, 300b, and 300c can be removed independently and replaced with another battery pack 300.

[0164] Each of the assembled batteries 200a to 200c includes a plurality of unit cells connected in series. At least one of the plurality of unit cells is the secondary battery according to the first embodiment. Each of the assembled batteries 200a to 200c is charged and discharged via a positive terminal 413 and a negative terminal 414.

[0165] The battery management device 411 communicates with the assembled battery monitoring devices 301a to 301c, and collects information on the voltage, temperature, and the like of each of the cells 100 included in the assembled batteries 200a to 200c included in the vehicle power supply 41. In this way, the battery management device 411 collects information on the maintenance of the vehicle power supply 41.

[0166] The battery management unit 411 and the assembled battery monitoring units 301a to 301c are connected via a communication bus 412. In the communication bus 412, one set of communication lines is shared by a plurality of nodes (the battery management unit 411 and one or more assembled battery monitoring units 301a to 301c). The communication bus 412 is a communication bus configured based on, for example, the CAN (Control Area Network) standard.

[0167] The battery pack monitoring devices 301a to 301c measure the voltage and temperature of each of the cells constituting the battery packs 200a to 200c based on commands communicated from the battery management device 411. However, the temperature can be measured at only a few points per battery pack, and it is not necessary to measure the temperatures of all the cells.

[0168] The vehicle power supply 41 may also have an electromagnetic contactor (for example, a switch device 415 shown in FIG. 9) that switches between the presence and absence of an electrical connection between the positive terminal 413 and the negative terminal 414. The switch device 415 includes a pre-charge switch (not shown) that is turned on when the assembled batteries 200a-200c are charged, and a main switch (not shown) that is turned on when the output from the assembled batteries 200a-200c is supplied to a load. Each of the pre-charge switch and the main switch includes a relay circuit (not shown) that is switched on or off by a signal supplied to a coil disposed in the vicinity of the switch element. The electromagnetic contactor such as the switch device 415 is controlled based on a control signal from the battery management device 411 or the vehicle ECU 42 that controls the operation of the entire vehicle 400.

[0169] The inverter 44 converts the input DC voltage into a three-phase alternating current (AC) high voltage for driving the motor. The three-phase output terminals of the inverter 44 are connected to the three-phase input terminals of the drive motor 45. The inverter 44 is controlled based on a control signal from the battery management device 411 or the vehicle ECU 42 for controlling the operation of the entire vehicle. By controlling the inverter 44, the output voltage from the inverter 44 is adjusted.

[0170] The drive motor 45 rotates by electric power supplied from the inverter 44. A driving force generated by the rotation of the drive motor 45 is transmitted to the axles and drive wheels W via, for example, a differential gear unit.

[0171] Although not shown, the vehicle 400 is also provided with a regenerative braking mechanism. The regenerative braking mechanism rotates the drive motor 45 when the vehicle 400 is braked, and converts kinetic energy into regenerative energy as electrical energy. The regenerative energy recovered by the regenerative braking mechanism is input to the inverter 44 and converted into a direct current. The converted direct current is input to the vehicle power supply 41.

[0172] One terminal of a connection line L1 is connected to the negative terminal 414 of the vehicle power supply 41. The other terminal of the connection line L1 is connected to a negative input terminal 417 of the inverter 44. A current detection unit (current detection circuit) 416 in the battery management device 411 is provided between the negative terminal 414 and the negative input terminal 417 on the connection line L1.

[0173] One terminal of a connection line L2 is connected to the positive electrode terminal 413 of the vehicle power supply 41. The other terminal of the connection line L2 is connected to a positive electrode input terminal 418 of the inverter 44. A switch device 415 is provided in the connection line L2 between the positive electrode terminal 413 and the positive electrode input terminal 418.

[0174] The external terminal 43 is connected to the battery management unit 411. The external terminal 43 can be connected to, for example, an external power source.

[0175] In response to operational inputs from the driver or the like, the vehicle ECU 42 coordinates with other management devices and control devices including the battery management device 411 to control the vehicle power supply 41, the switch device 415, the inverter 44, etc. Through the coordinated control of the vehicle ECU 42, etc., the output of power from the vehicle power supply 41 and the charging of the vehicle power supply 41 are controlled, and the entire vehicle 400 is managed. Data relating to the maintenance of the vehicle power supply 41, such as the remaining capacity of the vehicle power supply 41, is transferred between the battery management device 411 and the vehicle ECU 42 via a communication line.

[0176] The vehicle according to the fourth embodiment is equipped with the battery pack according to the embodiment, and therefore, a vehicle with excellent running performance in a wide temperature range from low to high can be realized. EXAMPLES

[0177] 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 <Preparation of positive electrode> The positive electrode active material is lithium nickel cobalt manganese composite oxide (LiNi 0.8 Co 0.1 Mn 0.1 O2) powder was prepared. Acetylene black was prepared as a conductive agent. Polyvinylidene fluoride (PVdF) was prepared as a binder. Li was prepared as a solid electrolyte. 1.3 Al 0.3 Ti 1.7 (PO4)3 particles were prepared. Next, the positive electrode active material, conductive agent, binder, and solid electrolyte were added to N-methylpyrrolidone (NMP) as a solvent in a ratio of 87 mass%:5 mass%:5 mass%:3 mass% and mixed to prepare a positive electrode slurry. This positive electrode slurry was applied to both sides of a current collector made of aluminum foil with a thickness of 15 μm. Next, the coating was dried in a thermostatic chamber at 120 ° C. to form a positive electrode active material-containing layer. The positive electrode active material-containing layer was pressed to obtain a positive electrode.

[0178] <Preparation of negative electrode> As a negative electrode active material, a monoclinic niobium titanium oxide (TiNb2O7) powder was prepared. The average secondary particle diameter of the niobium titanium oxide powder was 7.5 μm. The specific surface area of ​​the niobium titanium oxide powder was 4.0 m 2 / g. In addition, acetylene black was prepared as a conductive agent, and CMC and SBR were prepared as binders. Next, the negative electrode active material, conductive agent, CMC, and SBR were added to water as a solvent in a ratio of 91 mass %: 5.5 mass %: 1.5 mass %: 2 mass % and mixed to prepare a negative electrode slurry. This negative electrode slurry was applied to both sides of a current collector made of aluminum foil with a thickness of 15 μm. Next, the coating was dried in a thermostatic chamber at 120 ° C. to form a negative electrode active material-containing layer. The negative electrode active material-containing layer was pressed to obtain a negative electrode.

[0179] As the separator, a 12 μm-thick aramid-coated polyethylene nonwoven fabric was used.

[0180] The positive and negative electrodes were alternately stacked with a separator between them to produce a laminated electrode group, which was then housed in a pack (exterior member) made of a laminate film made of aluminum foil and polypropylene layers formed on both sides of the aluminum foil.

[0181] With a part of the exterior member left open, vacuum drying was carried out for 10 hours at 80° C. As a result, the moisture loss rate from the positive electrode before drying was 50% by mass.

[0182] Lithium hexafluorophosphate (LiPF6) was dissolved at a concentration of 1M (mol / L) in a mixed solvent of propylene carbonate (PC) and ethyl propionate (EP) in a volume ratio of 1:4. 1,3-propane sultone (PS) was added to this to give a concentration of 1 mass% to prepare a liquid non-aqueous electrolyte (non-aqueous electrolyte solution).

[0183] The liquid nonaqueous electrolyte was poured into the exterior member, and the exterior member was then sealed. After that, an initial charge / discharge and aging were performed to produce a flat nonaqueous electrolyte secondary battery with a capacity of 1.5 Ah. Example 2 A secondary battery was produced in the same manner as in Example 1, except that a negative electrode produced by the following method was used.

[0184] <Preparation of negative electrode> As a negative electrode active material, a monoclinic niobium titanium oxide (TiNb2O7) powder was prepared. The average secondary particle diameter of the niobium titanium oxide powder was 7.5 μm. The specific surface area of ​​the niobium titanium oxide powder was 4.0 m 2 The conductivity was 1.0 / g. Acetylene black was used as the conductive agent, and CMC and SBR were used as the binder. Li was used as the solid electrolyte. 1.3 Al 0.3 Ti 1.7 (PO4)3 particles were prepared. Next, the negative electrode active material, conductive agent, CMC, SBR, and solid electrolyte were added to water as a solvent in a ratio of 88 mass%:5 mass%:2 mass%:2 mass%:3 mass% and mixed to prepare a negative electrode slurry. This negative electrode slurry was applied to both sides of a current collector made of aluminum foil with a thickness of 15 μm. Next, the coating was dried in a thermostatic chamber at 120 ° C. to form a negative electrode active material-containing layer. The negative electrode active material-containing layer was pressed to obtain a negative electrode. Example 3 A secondary battery was fabricated in the same manner as in Example 2, except that the PS concentration in the liquid nonaqueous electrolyte (nonaqueous electrolytic solution) was changed to 3 mass %, and the vacuum drying with part of the exterior member open was changed to 80°C for 13 hours. Example 4 The solid electrolyte in the positive electrode is Li 1.2 Zr 1.9 Ca 0.1 A secondary battery was produced in the same manner as in Example 2, except that (PO4)3 was used. Example 5 Lithium hexafluorophosphate (LiPF6) was dissolved at a concentration of 1M (mol / L) in a mixed solvent in which propylene carbonate (PC) and ethyl propionate (EP) were mixed at a volume ratio of 1:4. 1,3-propane sultone (PS) was added to the mixture to a concentration of 1.0 mass% and lithium difluorophosphate (DFP) was added to a concentration of 1.0 mass% to prepare a liquid nonaqueous electrolyte (nonaqueous electrolyte solution). A secondary battery was produced in the same manner as in Example 2, except that the obtained liquid nonaqueous electrolyte (nonaqueous electrolyte solution) was used. Example 6 The positive electrode active material is LiNi 0.6 Co 0.2 Mn 0.2 A secondary battery was fabricated in the same manner as in Example 2, except that O2 was used. Example 7 The negative electrode active material is Ti2Nb 10 O 29 A secondary battery was produced in the same manner as in Example 2, except for changing the above. Example 8 A negative electrode without the addition of a solid electrolyte was prepared in the same manner as in Example 1, except that the negative electrode active material of the negative electrode was changed to TiO2(B).

[0185] Lithium hexafluorophosphate (LiPF6) was dissolved at a concentration of 1M (mol / L) in a mixed solvent of propylene carbonate (PC) and diethyl carbonate (DEC) in a volume ratio of 1:2. 1,3-propane sultone (PS) was added to this to give a concentration of 1 mass% to prepare a liquid nonaqueous electrolyte (nonaqueous electrolyte solution). A secondary battery was produced in the same manner as in Example 1, except that the obtained negative electrode and a liquid non-aqueous electrolyte (nonaqueous electrolytic solution) were used. Example 9 The negative electrode active material is Li4Ti5O 12 A negative electrode containing no solid electrolyte was produced in the same manner as in Example 1, except for changing the above.

[0186] A secondary battery was produced in the same manner as in Example 8, except that the obtained negative electrode was used. Comparative Example 1 The positive electrode active material is lithium nickel cobalt manganese composite oxide (LiNi 0.8 Co 0.1 Mn 0.1 O2) powder was prepared. Acetylene black was prepared as a conductive agent. Polyvinylidene fluoride (PVdF) was prepared as a binder. Next, the positive electrode active material, conductive agent, and binder were added to N-methylpyrrolidone (NMP) as a solvent in a ratio of 93.5 mass %: 4.6 mass %: 1.9 mass % and mixed to prepare a positive electrode slurry. This positive electrode slurry was applied to both sides of a current collector made of aluminum foil with a thickness of 15 μm. Next, the coating was dried in a thermostatic chamber at 120 ° C. to form a positive electrode active material-containing layer. The positive electrode active material-containing layer was pressed to obtain a positive electrode.

[0187] A secondary battery was fabricated in the same manner as in Example 1, except that the obtained positive electrode containing no solid electrolyte and a liquid nonaqueous electrolyte having the same composition as in Example 8 were used. Comparative Example 2 Lithium hexafluorophosphate (LiPF6) was dissolved at a concentration of 1M (mol / L) in a mixed solvent of propylene carbonate (PC) and ethyl propionate (EP) in a volume ratio of 1:4. Tris(trimethylsilyl)phosphate (TMSP) was added to this to a concentration of 1 mass% to prepare a liquid nonaqueous electrolyte (nonaqueous electrolyte solution). A secondary battery was fabricated in the same manner as in Example 2, except that the obtained liquid nonaqueous electrolyte was used. Comparative Example 3 Lithium hexafluorophosphate (LiPF6) was dissolved at a concentration of 1M (mol / L) in a mixed solvent of propylene carbonate (PC) and ethyl propionate (EP) in a volume ratio of 1:4. Lithium bisfluorosulfonylimide (LiN(FSO2)2:LiFSI) was added to this to a concentration of 1 mass% to prepare a liquid non-aqueous electrolyte (nonaqueous electrolyte solution).

[0188] A secondary battery was produced in the same manner as in Example 2, except that the obtained liquid nonaqueous electrolyte and a positive electrode (without adding a solid electrolyte) similar to that produced in Comparative Example 1 were used.

[0189] The composition of the positive electrode active material, the composition of the solid electrolyte contained in the positive electrode, the composition of the negative electrode active material, the composition of the solid electrolyte contained in the negative electrode, the composition of the nonaqueous solvent of the nonaqueous electrolyte, the additives for the nonaqueous electrolyte, and the lithium salt of the nonaqueous electrolyte for each of the examples and comparative examples are shown in Table 2. In the composition of the nonaqueous solvent of the nonaqueous electrolyte, PC:EP=1:4 indicates that the volume ratio of PC to EP is 1:4.

[0190] For the positive electrodes of the secondary batteries of Examples 1 to 9 and Comparative Examples 1 to 3, the peak ratios B / A in the S1s spectra by HAXPES were measured by the method described above, and the results (peak ratio (B / A), height (intensity) of maximum peak A, and height (intensity) of maximum peak B) are shown in Table 3. Note that, in each of Examples 1 to 9 and Comparative Examples 1 to 3, the number of peaks appearing in the binding energy range of 2468 eV or more and 2474 eV or less, and the number of peaks appearing in the binding energy range of 2475 eV to 2483 eV or less, were one each. Among these Examples and Comparative Examples, the S1s spectrum by HAXPES of the positive electrode of Example 1 is shown in FIG. 10, and the S1s spectrum by HAXPES of the positive electrode of Comparative Example 1 is shown in FIG. 11.

[0191] As is clear from a comparison between FIG. 10 and FIG. 11, the positive electrode of Example 1 contains more S-containing substances with C-S bonds than S-containing substances with -SO4 (SO4 group). From the peak ratio (B / A) values ​​in Table 3, it can be seen that the positive electrodes of Examples 2 to 9 also contain more S-containing substances with C-S bonds, as in Example 1. In addition, the S-containing substances were present in the surface layer portion, including the surface of the positive electrode active material-containing layer. The S-containing substances had a film-like or layer-like form. On the other hand, the positive electrodes of Comparative Examples 1 and 3 contained more S-containing substances with -SO3 (SO3 group) and -SO4 (SO4 group). The presence of S element could not be confirmed in the positive electrode of Comparative Example 2.

[0192] Table 3 shows the moisture reduction rate (mass%) of the positive electrode when the electrode group was dried for the secondary batteries of Examples 1 to 9 and Comparative Examples 1 to 3. The method for measuring the moisture reduction rate (mass%) is as described above. From the measurement results shown in Table 3, when the compositions of the positive electrode active material and the positive electrode solid electrolyte are the same, the moisture reduction rate varies little, for example, as shown in Examples 1, 2, 5, and 7. On the other hand, in Example 4, in which the composition of the positive electrode solid electrolyte is different from that of Example 2, and in Example 6, in which the composition of the positive electrode active material is different from that of Example 2, the moisture reduction rate tends to be smaller than that of Example 2. Although the drying conditions for the electrode groups of Comparative Examples 1 and 3 were the same as those of Example 1, the moisture reduction rate was small. This is because the positive electrodes of Comparative Examples 1 and 3 do not contain a solid electrolyte. Li 1+x Al x Ti 2-x (PO4)3, a compound with 0.1≦x≦0.5, Li 1+2x Zr 1-x Ca x This is because the compound represented by (PO4)3 where 0≦x<1 tends to increase the water content of the positive electrode.

[0193] The secondary batteries of Examples 1 to 9 and Comparative Examples 1 to 3 were subjected to a SOC 0-90% cycle test in an environment of 70°C. That is, in an environment of 70°C, constant current charging was performed at 1C, and then constant voltage charging at 2.83V was performed until the current value converged to 1 / 20C, and the state of charge (SOC) of the secondary battery was set to 90%. Next, constant voltage discharging was performed at 1C to 1.5Vcut, and the state of charge was set to 0%. The rest time between charging and discharging was set to 10 minutes. This charge / discharge cycle was repeated, and the number of cycles at which the discharge capacity retention rate became 80% when the discharge capacity retention rate of the first cycle was set to 100% was shown in Table 3 as the charge / discharge cycle life.

[0194] [Table 2]

[0195] [Table 3]

[0196] As is clear from Tables 2 and 3, the secondary batteries of Examples 1 to 9 are superior in cycle life at high temperatures compared to the secondary batteries of Comparative Examples 1 to 3. On the other hand, the cycle life at high temperatures is short in Comparative Examples 1 and 3 in which the peak ratio (B / A) is greater than 1 / 3, and Comparative Example 2 in which the peak ratio (B / A) is zero.

[0197] According to at least one of the secondary batteries of the embodiments or examples described above, the S1s spectrum by hard X-ray photoelectron spectroscopy satisfies the following formula (1), and therefore a secondary battery having an excellent high-temperature charge-discharge cycle life can be provided.

[0198] B / A≦1 / 3 (1) Here, A is the intensity of the maximum peak appearing in the binding energy range of 2468 eV to 2474 eV in the S1s spectrum, and B is the intensity of the maximum peak appearing in the binding energy range of 2475 eV to 2483 eV in the S1s spectrum.

[0199] 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 novel 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 included in the scope of the invention and its equivalents described in the claims.

[0200] The invention according to the embodiment will be described below. <1> a positive electrode including a positive electrode active material and a solid electrolyte; A negative electrode; and a non-aqueous electrolyte. The positive electrode of the secondary battery satisfies the following formula (1) in an S1s spectrum by hard X-ray photoelectron spectroscopy:

[0201] B / A≦1 / 3 (1) However, A is the intensity of the maximum peak appearing in the range of binding energy of 2468 eV or more and 2474 eV or less in the S1s spectrum, and B is the intensity of the maximum peak appearing in the range of binding energy of 2475 eV or more and 2483 eV or less in the S1s spectrum. <2> The non-aqueous electrolyte contains a sultone compound, and the secondary battery according to <1>. <3> The sultone compound contains 1,3-propane sultone, and the secondary battery according to <1> or <2>. <4> The positive electrode includes a positive electrode active material-containing layer containing the positive electrode active material and the solid electrolyte, and an S-containing substance present on at least a part of the surface of the positive electrode active material-containing layer, and the secondary battery according to any one of <1> to <3>. <5> The positive electrode active material contains a composite oxide represented by the general formula Li x MO2, where 0 < x ≦ 1 in the general formula, and M contains at least one element selected from the group consisting of Ni, Co, and Mn, and the secondary battery according to any one of <1> to <4>. <6> The solid electrolyte is a compound represented by Li 1+x Al x Ti 2-x (PO4)3 with 0.1 ≦ x ≦ 0.5, or a compound represented by Li 1+2x Zr 1-x Ca x (PO4)3 with 0 ≦ x < 1, and the secondary battery according to any one of <1> to <5>. <7> The negative electrode includes a negative electrode active material containing at least one selected from the group consisting of Si, a carbon material, lithium titanate, a titanium-containing oxide, a niobium-titanium-containing oxide, and a niobium-containing oxide, and the secondary battery according to any one of <1> to <6>. <8> A battery pack including the secondary battery according to any one of <1> to <7>. <9> External terminals for energization, A protection circuit Further comprising <8> The battery pack according to claim 1 . <10> 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. <8> or <9> The battery pack according to claim 1 . <11> <8> ~ <10> A vehicle equipped with a battery pack according to any one of the items above. <12> A mechanism for converting the kinetic energy of the vehicle into regenerative energy is included. <11> A vehicle as described in. [Explanation of symbols]

[0202] Reference Signs List 1...electrode group, 2...container (exterior member), 3...positive electrode, 3a...positive electrode current collector, 3b...positive electrode active material-containing layer, 4...negative electrode, 4a...negative electrode current collector, 4b...negative electrode active material-containing layer, 5...separator, 6...positive electrode lead, 7...negative electrode lead, 8...positive electrode conductive tab, 9...negative electrode conductive tab, 10...sealing plate, 11...insulating member, 12...exterior member, 13...negative electrode terminal, 14...positive electrode terminal, 200...battery assembly, 1001 to 1005...secondary battery, 21...lead (bus bar), 300...battery pack, 100...unit cell, 200...assembly Battery, 34...printed wiring board, 345...thermistor, 346...protection circuit, 350...external terminal for current supply, 40...vehicle body, 300...battery pack, 400...vehicle, 41...vehicle power supply, 411...battery management device, 412...communication bus, 300a-c...battery packs, 301a-c...battery assembly monitoring device, 200a-c...battery assembly, 413...positive terminal, 414...negative terminal, 44...inverter, 45...drive motor, 43...external terminal, 42...vehicle ECU, L1, L2...connection lines, W...drive wheels.< / haxpes>

Claims

1. a positive electrode including a positive electrode active material and a solid electrolyte; A negative electrode; and a non-aqueous electrolyte. The positive electrode satisfies the following formula (1) in an S1s spectrum by hard X-ray photoelectron spectroscopy: B / A≦1 / 3 (1) Here, A is the intensity of the maximum peak appearing in the binding energy range of 2468 eV or more and 2474 eV or less in the S1s spectrum, and B is the intensity of the maximum peak appearing in the binding energy range of 2475 eV or more and 2483 eV or less in the S1s spectrum.

2. The secondary battery according to claim 1 , wherein the non-aqueous electrolyte contains a sultone compound.

3. The secondary battery according to claim 2 , wherein the sultone compound includes 1,3-propane sultone.

4. 2. The secondary battery according to claim 1, wherein the positive electrode comprises a positive electrode active material-containing layer containing the positive electrode active material and the solid electrolyte, and an S-containing substance present on at least a portion of a surface of the positive electrode active material-containing layer.

5. The positive electrode active material has the general formula Li x M.O. 2 wherein, in the general formula, 0<x≦1, and M includes at least one element selected from the group consisting of Ni, Co, and Mn.

6. The solid electrolyte is Li 1+x A x Ti 2-x (P.O. 4 ) 3 and 0.1≦x≦0.5, or Li 1+2x Zr 1-x Ca x (P.O. 4 ) 3 The secondary battery according to claim 4 , comprising at least one compound represented by the formula:

7. 2. The secondary battery according to claim 1, wherein the negative electrode comprises a negative electrode active material comprising at least one selected from the group consisting of Si, a carbon material, a lithium titanium oxide, a titanium-containing oxide, a niobium titanium-containing oxide, and a niobium-containing oxide.

8. A battery pack comprising the secondary battery according to any one of claims 1 to 7.

9. An external terminal for supplying electricity; Protection circuit and The battery pack of claim 8 further comprising:

10. A battery comprising a plurality of the secondary batteries, The battery pack according to claim 9 , wherein the secondary batteries are electrically connected in series, in parallel, or in a combination of series and parallel.

11. A vehicle equipped with the battery pack according to claim 8.

12. The vehicle of claim 11, further comprising a mechanism for converting kinetic energy of the vehicle into regenerative energy.

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