Secondary batteries, battery packs, and vehicles

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] Embodiments of the present invention relate to a secondary battery, a battery pack, and a vehicle. [Background technology]

[0002] Non-aqueous electrolyte batteries using lithium metal, lithium alloy, lithium compound, or carbonaceous material as the negative electrode are expected to be high-energy-density batteries, and research and development are progressing. To date, LiCoO2 and LiNi have been used as active materials. 1 / 3 Co 1 / 3 Mn 1 / 3 Lithium-ion batteries, which comprise a positive electrode containing O2 or LiMn2O4 and a negative electrode containing a carbonaceous material that intercalates and releases lithium, are widely used in portable devices.

[0003] The inclusion of sulfone compounds or sultone compounds in the non-aqueous electrolyte of non-aqueous electrolyte batteries is being considered. Batteries equipped with non-aqueous electrolytes containing sulfone or sultone compounds have resistance issues. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. WO2015 / 136688 [Patent Document 2] Special Publication No. 2015-522209 [Overview of the project] [Problems that the invention aims to solve]

[0005] The present invention aims to provide a secondary battery with excellent charge-discharge cycle life at high temperatures, a battery pack including the secondary battery, and a vehicle. [Means for solving the problem]

[0006] According to the embodiment, a secondary battery is provided that comprises 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 equation (1) in the S1s spectrum obtained by hard X-ray photoelectron spectroscopy.

[0007] 1 / 50≦ B / A ≤ 1 / 3 (1) However, A has a binding energy of 2468 eV or more and 2474 eV in the S1s spectrum. This is the intensity of the maximum peak appearing in this range, where B is the binding energy in the S1s spectrum. This represents the intensity of the maximum peak appearing in the range of 2475 eV to 2483 eV.

[0008] Furthermore, according to the embodiment, a battery pack including a 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 explanation of the drawing]

[0010] [Figure 1] A partially cutaway cross-sectional view of a secondary battery according to an embodiment. [Figure 2] Side view of the battery in Figure 1. [Figure 3] A cross-sectional view of the secondary battery of the embodiment, cut in a direction perpendicular to the terminal extension direction. [Figure 4] Enlarged cross-sectional view of section A in Figure 3. [Figure 5] A perspective view showing an example of a battery pack including a secondary battery of an embodiment. [Figure 6] An exploded perspective view of the battery pack of the embodiment. [Figure 7] A block diagram showing the electrical circuit of the battery pack in Figure 6. [Figure 8] A schematic diagram showing an example of a vehicle equipped with a secondary battery according to the embodiment. [Figure 9] A schematic diagram showing another example of a vehicle according to the embodiment. [Figure 10]This figure shows an example of the S1s spectrum obtained by hard X-ray photoelectron spectroscopy of the positive electrode of the secondary battery in Example 1. [Figure 11] This figure shows an example of the S1s spectrum obtained by hard X-ray photoelectron spectroscopy of the positive electrode of the secondary battery of Comparative Example 1. [Modes for carrying out the invention]

[0011] First Embodiment According to the first embodiment, a secondary battery is provided comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode comprises a positive electrode active material and a solid electrolyte. The positive electrode satisfies equation (1) below in the S1s spectrum obtained by hard X-ray photoelectron spectroscopy (HAXPES).

[0012] B / A ≤ 1 / 3 (1) However, A is the intensity of the maximum peak appearing in the S1s spectrum where the binding energy is between 2468 eV and 2474 eV, and B is the intensity of the maximum peak appearing in the S1s spectrum where the binding energy is between 2475 eV and 2483 eV.

[0013] As a result of diligent research, the inventors have found that by satisfying equation (1) in the S1s spectrum obtained by hard X-ray photoelectron spectroscopy, the resistance of the secondary battery can be lowered, thereby improving the charge-discharge cycle life at high temperatures.

[0014] Hard X-ray photoelectron spectroscopy can be used to confirm the bonding state of elements near the surface of the positive electrode (for example, in the region from the positive electrode surface to a depth of several tens of nanometers). The surface of the positive electrode is, for example, the surface of the positive electrode active material-containing layer. The S1s spectrum obtained by hard X-ray photoelectron spectroscopy shows the bonding state of the S element near the surface of the positive electrode (for example, in the region from the positive electrode surface to a depth of several tens of nanometers). The maximum peak (hereinafter referred to as the first peak) that appears in the bond energy range of 2468 eV to 2474 eV in the S1s spectrum originates from the CS bond. On the other hand, the maximum peak (hereinafter referred to as the second peak) that appears in the bond energy range of 2475 eV to 2483 eV in the S1s spectrum is -SO x (SO x Derived from (base). -SO x In this case, x is, for example, a value that satisfies x > 0. -SO x Examples include -SO3 (SO3 group) and -SO4 (SO4 group).

[0015] By making the ratio of the intensity B of the second peak to the intensity A of the first peak (B / A) 1 / 3 or less, S-containing material with CS bonds is formed on the surface of the positive electrode and further inside, resulting in -SO x It is possible to include more sulfur than sulfur-containing materials that have a CS bond. As a result, the high-temperature cycle life performance of secondary batteries can be improved by the mechanism hypothesized below. It is hypothesized that the reaction that generates sulfur-containing materials with a CS bond can suppress the reaction that produces by-products such as lithium fluoride (LIF) and mixes them into the non-aqueous electrolyte. Therefore, it is hypothesized that the increase in resistance under high-temperature conditions can be suppressed, and the charge-discharge cycle life under high-temperature conditions can be improved. The lower limit of the ratio (B / A) can be a value greater than 0. For example, the lower limit of the ratio (B / A) can be 1 / 50. This makes it possible to achieve excellent charge-discharge cycle life under high-temperature conditions. A more preferable range for the ratio (B / A) is 1 / 30 or more and 1 / 10 or less.

[0016] The following describes the positive electrode, negative electrode, and non-aqueous electrolyte. <Positive electrode> The positive electrode has a positive electrode current collector and a positive electrode active material-containing layer carried on one or both sides of the positive electrode current collector and containing a positive electrode active material and a solid electrolyte. The positive electrode active material-containing layer may contain a binder, a conductive agent, or both 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, fluorinated iron sulfate, 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), etc.

[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), etc.

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

[0026] Examples of the olivine - structured 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), etc.

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

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

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

[0030] General formula Li x Composite oxides 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 or secondary particles in which the primary particles are aggregated. Also, the primary particles and secondary particles may be mixed.

[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 referred to here means showing 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 is preferable to use a lithium phosphate solid electrolyte having a NASICON (Sodium (Na) Super Ionic Conductor) type structure and represented by the general formula Li 1+x Mα2(PO4)3. In the above general formula, Mα 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 LATP compounds represented by Li 1+x Al x Ti 2-x (PO4)3 with 0.1 ≦ x ≦ 0.5; compounds represented by Li 1+x Al y Mβ 2-y (PO4)3 where Mβ is one or more selected from the group consisting of Ti, Ge, Sr, Zr, Sn, and Ca and 0 ≦ x ≦ 1 and 0 ≦ y ≦ 1; compounds represented by Li 1+x Al x Ge 2-x (PO4)3 with 0 ≦ x ≦ 2; and compounds represented by Li 1+x Al x Zr 2-x (PO4)3 with 0 ≦ x ≦ 2; Li 1+x+y Al x Mγ 2-x Si y P 3-y O 12 where Mγ is one or more selected from the group consisting of Ti and Ge and 0 < x ≦ 2, 0 ≦ y < 3; compounds represented by Li 1+2x Zr 1-x Ca x (PO4)3 with 0 ≦ x < 1 can be mentioned. The compound represented by Li 1+2x Zr 1-x Ca x (PO4)3 is also called LZCP, and examples include Li 1.2 Zr 1.9 Ca 0.1 (PO4)3 and the like.

[0037] In addition to the above lithium phosphate solid electrolyte, as the oxide-based solid electrolyte, there are also Li x PO y N z represented by 2.6 ≦ x ≦ 3.5, 1.9 ≦ y ≦ 3.8, and 0.1 ≦ z ≦ 1.3, an amorphous LIPON compound (for example, Li 2.9 PO 3.3 N 0.46 ); a garnet-type structure La 5+x A x La 3-x Mδ2O 12 represented by A is one or more selected from the group consisting of Ca, Sr, and Ba, Mδ is one or more selected from the group consisting of Nb and Ta, and 0 ≦ x ≦ 0.5; Li3Mδ 2-x L2O 12 represented by Mδ is one or more selected from the group consisting of Nb and Ta, L may contain Zr, and 0 ≦ x ≦ 0.5; Li 7-3x Al x La3Zr3O 12 represented by 0 ≦ x ≦ 0.5; Li 5+x La3Mδ 2-x Zr x O 12 represented by Mδ is one or more selected from the group consisting of Nb and Ta, and 0 ≦ x ≦ 2, an LLZ compound (for example, Li7La3Zr2O 12 ); and a compound having a perovskite-type structure and represented by La 2 / 3-x Li x TiO3 and 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 may be used. Li 1+x Al x Ti 2-x (PO4)3 represented by 0.1 ≦ x ≦ 0.5, an LATP compound, and Li 1+2x 0]Zr 1-x Ca xLZCP compounds, represented as (PO4)3 and satisfying the condition 0 ≤ x < 1, can promote the decomposition reaction of non-aqueous electrolytes containing sultone compounds at the positive electrode, thereby promoting the formation of sulfur-containing substances with CS bonds at the positive electrode. Furthermore, LATP compounds and LZCP compounds have a high affinity for water and tend to increase the water content of the positive electrode.

[0039] The solid electrolyte content in the positive electrode active material-containing layer can be, for example, 0.5% by mass or more and 5.0% by mass or less.

[0040] The form of the solid electrolyte is not particularly limited, but it can be granular, for example. The average particle size of the solid electrolyte particles can be, for example, between 0.05 μm and 8 μm.

[0041] The conductive agent enhances the electronic conductivity of the positive electrode active material-containing layer and can reduce contact resistance with the current collector. Examples of conductive agents include acetylene black, carbon black, and graphite. One or more types of conductive agents may be used.

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

[0043] A binder can bond the active material and the conductive agent. Examples of binders include polymers such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluorinated rubber. One or more types of binders may be used.

[0044] The binder content of the positive electrode active material layer can be, for example, 2% by mass or more and 7% by mass or less.

[0045] The positive electrode active material layer may contain sulfur-containing materials. Examples of sulfur-containing materials include sulfur-containing materials with CS bonds, and -SO4. x (SO x It contains an S-containing substance having a CS bond and -SOx (SO x The material may have both the base and the S content. The S content may be present on at least a portion of the surface of the positive electrode active material containing layer, or on at least a portion of the surface layer including the surface of the positive electrode active material containing layer. The surface layer of the positive electrode active material containing layer is, for example, the region from the surface of the positive electrode active material containing layer to a depth detectable by HAXPES (e.g., several tens of nanometers). The form of the S content is not particularly limited, but examples include film-like materials and layer-like materials.

[0046] The positive electrode current collector is, for example, aluminum foil, or 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 in the aluminum foil or aluminum alloy foil is preferably 1% by mass or less.

[0048] Furthermore, the positive electrode current collector may include portions on its surface where the positive electrode active material-containing layer is not formed. These portions can function as positive electrode current collector tabs.

[0049] The positive electrode is manufactured, 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 it, and pressing it. <Negative electrode> The negative electrode comprises a negative electrode current collector and a negative electrode active material-containing layer supported on one or both sides of the negative electrode current collector, which contains the negative electrode active material. The negative electrode active material-containing layer may contain a binder, a conductive agent, or both a binder and a conductive agent.

[0050] The negative electrode active material can intercalate and deintercalate lithium ions. The type of negative electrode active material used can be one kind or two or more kinds. 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 the titanium-containing oxide or the 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 oxide represented as Ti2O4 (0 ≤ b ≤ 1), Li 1.1+b Ti 1.8 Lithium titanium oxide represented as O4(0≦b≦1), Li 1.07+b Ti 1.86 Examples include lithium titanium-containing oxides represented as O4 (0 ≤ b ≤ 1), and lithium titanium-containing composite oxides containing at least one element selected from the group consisting of Nb, Mo, W, P, V, Sn, Cu, Ni, and Fe.

[0055] Furthermore, Li is an example of a lithium titanium-containing oxide. 2+a A d Ti 6-b B b O 14ーc This includes lithium titanium-containing composite oxides represented by (A is one or more elements selected from Na, K, Mg, Ca, Sr, B is a metallic element other than Ti, 0≦a≦5, 0≦b≦6, 0≦c≦0.6, 0≦d≦3). 2+a A d Ti 6-b B b O 14ーc It has a crystal structure of space group Cmca.

[0056] Another example of lithium titanium-containing oxides is orthorhombic titanium-containing oxides. 2+a M I 2-b Ti 6-c M II d O 14+σ Examples of compounds represented by are given. Here, M I It 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. In the composition formula, each subscript has the following properties: 0≦a≦6, 0≦b<2, 0≦c<6, 0≦d<6, -0.5≦σ≦0.5. As a specific example of an orthorhombic titanium-containing composite oxide, Li 2+a Na2Li6O 14 (0 ≤ a ≤ 6) is one example.

[0057] Examples of titanium oxides include those with the general formula Li a This includes titanium oxides represented as TiO2(0≦a≦2). In this case, the compositional formula before charging is TiO2. Examples of titanium oxides include monoclinic (bronze structure (B)) titanium oxide, rutile structure titanium oxide, anatase structure titanium oxide, etc. Monoclinic (bronze structure (B)) TiO2(B) is preferred. Low crystallinity TiO2(B) with a heat treatment temperature of 300~600℃ is also preferred.

[0058] Examples of niobium-containing oxides 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-containing oxides include monoclinic niobium-titanium-containing oxides, Ti2Nb2O9, and Ti2Nb 10 O 29 TiNb 14 O 37 TiNb 24 O 62 This includes substituted niobium titanium composite oxides in which at least a portion of Nb and / or Ti is substituted with a different element. Examples of substituted elements include Na, K, Ca, Co, Ni, Si, P, V, Cr, Mo, Ta, Zr, Mn, Fe, Mg, B, Pb, and Al. A substituted niobium titanium composite oxide may contain one substituted element or two or more substituted elements.

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

[0062] As an example of a monoclinic niobium-titanium-containing oxide, Li x Ti 1-y M1 y Nb 2-z M2 z O 7+δ A compound represented by the formula is shown below. 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 empirical formula represent 0≦x≦5, 0≦y<1, 0≦z<2, and -0.3≦δ≦0.3.

[0063] Other examples of monoclinic niobium-titanium-containing oxides include Ti 1-y M3 y+z Nb 2-z O 7-δ A compound represented by the formula is shown below. Here, M3 is at least one selected from Mg, Fe, Ni, Co, W, Ta, and Mo. In the compositional formula, each subscript has the following properties: 0≦y<1, 0≦z<2, -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 These are some examples.

[0065] Examples of niobium titanium molybdenum-containing oxides include those with the general formula Li a Ti b Nb 2-2d Mo c+2d O 2b+5+3cA tetragonal titanium-niobium-molybdenum composite oxide represented by the general formula Li (preferably with subscripts a, b, c, and d within the ranges 0≦a≦b+4+3c, 0.3≦b≦1.6, 0.3≦c<1.6, and 0≦d<0.4, respectively), with the general formula Li a M b NbMo c O d It is expressed as such, 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 such as 0≦a≦b+2+3c, 0≦b≦1.4, 0≦c≦0.5, and 2.33≦d / (1+b+c)≦2.50.

[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 intercept and deintercept lithium ions within the active material and is electrochemically and chemically stable with respect to non-aqueous electrolytes, thus exhibiting excellent high-current discharge performance, rapid charging performance, and cycle life performance.

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

[0068] It is preferable to have an average particle size of the primary particles of the negative electrode active material in the range of 0.05 to 1 μm. This improves high-current performance. Good performance can be obtained with either granular or fibrous particle shapes. Furthermore, if the negative electrode active material forms secondary particles, an average particle diameter of 2 to 20 μm is preferable for the secondary particles. This allows for a higher electrode density and improves cycle life performance.

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

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

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

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

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

[0074] The binder content of the negative electrode active material layer can be, for example, 2% by mass or more and 7% by mass or less.

[0075] The negative electrode active material layer may contain a solid electrolyte. Details regarding the type and form of the solid electrolyte are similar to those described for the positive electrode. The solid electrolytes in the positive electrode and the negative electrode may be of the same type or different from each other.

[0076] The solid electrolyte content in the negative electrode active material-containing layer can be, for example, 0.5% by mass or more and 5.0% by mass or less.

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

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

[0079] The negative electrode is manufactured, 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 it, and pressing it. (Non-aqueous electrolytes) As non-aqueous electrolytes, for example, liquid non-aqueous electrolytes, gel-type non-aqueous electrolytes, solid non-aqueous electrolytes, etc., can be used.

[0080] Liquid non-aqueous electrolytes may contain an organic solvent and an electrolyte salt. The electrolyte salt can dissolve in the organic solvent and function as a solute. The concentration of the electrolyte salt can be, for example, between 0.5 mol / L and 2.5 mol / L.

[0081] Examples of electrolyte salts include lithium salts such as lithium perchlorate (LiClO4), lithium hexafluoride phosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium arsenide hexafluoride (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), and lithium bistrifluoromethylsulfonylimide (LiN(CF3SO2)2), as well as mixtures thereof. The electrolyte salt is preferably resistant to oxidation even at high potentials, with LiPF6 being the most preferred.

[0082] Examples of organic solvents include cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), and vinylene carbonate (VC); linear 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); linear ethers such as dimethoxyethane (DME) and diethoxyethane (DEE); γ-butyrolactone (GBL), acetonitrile (AN), sulfolane (SL), and ethyl propionate (ethyl These include organic solvents (propionate; EP), propyl propionate (PP), and ethyl butyrate (EB). These organic solvents can be used individually or as mixed solvents.

[0083] The liquid non-aqueous electrolyte may contain components other than those listed above (hereinafter referred to as the second component). Examples of the second component include sultone compounds, phosphate compounds, and tetraethenylsilane. The second component may contribute to reducing the resistance of secondary batteries or improving their high-temperature lifespan. The second component may also function as an organic solvent or exist as a solute. There may be one or more types of the second component.

[0084] Examples of sultone compounds include 1,3-propanesultone (PS), 1,4-butanesultone, 1,3-propensultone, and 2,4-butanesultone. The sultone compound may consist of one selected from the group of these compounds, or it may consist of a mixture of two or more. Since the sultone compound can undergo decomposition before other non-aqueous electrolyte components (e.g., organic solvents) undergo decomposition reactions, gas generation can be suppressed. 1,3-propanesultone can react with a positive electrode containing a solid electrolyte that includes at least one of LATP compounds or LZCP compounds to produce an S-containing substance with a CS bond at the positive electrode.

[0085] Examples of phosphate compounds include lithium difluorophosphate (DFP). Lithium difluorophosphate can promote the formation of sulfur-containing compounds with CS bonds.

[0086] The content of at least one of the sultone compound or phosphate compound in the liquid non-aqueous electrolyte can be, for example, 0.5% by mass or more and 5.0% by mass or less. Setting it within this range can improve high-temperature lifetime performance.

[0087] Gel-like non-aqueous electrolytes can be, for example, composites of liquid non-aqueous electrolytes and polymer materials. Examples of polymer materials include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyethylene oxide (PEO), or mixtures thereof.

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

[0089] The secondary battery of this embodiment may include a separator and an outer casing in addition to a positive electrode, a negative electrode, and a non-aqueous electrolyte. Furthermore, the secondary battery of this embodiment may include a positive electrode terminal and a negative electrode terminal. The negative electrode, positive electrode, and separator can constitute an electrode group. The non-aqueous electrolyte can be held within the electrode group. The form of the electrode group is not particularly limited and can be, for example, a stacked type or a wound type. The secondary battery of this embodiment can be applied to various forms of secondary batteries, such as prismatic, cylindrical, flat, thin, and coin-type batteries. (Separator) The separator is placed between the positive and negative electrodes. A portion of the separator may face or be in contact with only the positive electrode, or only the negative electrode.

[0090] Examples of separators include nonwoven fabrics made of synthetic resins (e.g., polyolefins such as polyethylene and polypropylene), porous polyethylene films, porous polypropylene films, and nonwoven fabrics made of cellulose.

[0091] The separator may have at least a portion of its surface covered with a layer containing inorganic particles such as alumina or a resin such as aramid. (Exterior components) The outer casing contains at least a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive and negative electrodes may be housed within the outer casing in the form of an electrode group, with a separator or the like placed between them.

[0092] Metal containers and laminate film containers can be used for the exterior components.

[0093] As for the metal container, metal cans made of aluminum, aluminum alloy, iron, stainless steel, etc., in square or cylindrical shapes can be used. The metal container may be equipped with a lid. Furthermore, the thickness of the container plate should preferably be 0.5 mm or less, and more preferably 0.3 mm or less.

[0094] Examples of laminate films include multilayer films in which 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. Furthermore, the thickness of the laminate film is preferably 0.2 mm or less. The purity of the aluminum foil is preferably 99.5% or higher.

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

[0096] The following describes the analysis of the cathode using HAXPES, the method for identifying sulfur-containing substances, and the method for identifying slutone compounds.

[0097] First, if the electrode to be measured (positive or negative electrode) is incorporated into a battery, remove the electrode from the battery as follows: First, disassemble the battery containing the electrode in a glove box filled with argon. Remove the electrode to be measured from the disassembled battery. Wash this electrode with a suitable solvent. For example, methyl ethyl carbonate can be used as the solvent for washing. Vacuum dry the washed electrode. Thus, obtain the electrode for measurement. <haxpes> The electrode (e.g., positive electrode) extracted using the method described above 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 removed from the glove box and attached to the sample inlet of the HAXPES instrument. By transferring the sample folder within the instrument, the electrode sample is introduced into the instrument without exposure to air. The HAXPES analysis is performed as follows: The energy is calibrated with Au4f7 / 2 (5870eV) before measurement. The excitation energy is set to 5947.51eV. The beam size is 20μm vertically × 30μm horizontally. The electron analyzer (Scienta Omicron R4000 L1) is set to 12keV. The photoelectron detection angle is set to an oblique incidence configuration of approximately 89°. Charge neutralization is not used.

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

[0099] In the S1s spectrum obtained by HAXPES, the line connecting the intensities of 2483 eV and 2468 eV is used as the baseline. In the S1s spectrum shown in Figure 10, the baseline is indicated by the symbol L. Peaks are defined as those detected above the baseline. 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 where the binding energy appears in the range 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 where the binding energy is 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. Also, 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 where the binding energy is 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 where the binding energy is 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> To confirm whether an S-containing substance exists in the positive electrode active material-containing layer, it can be confirmed by whether a maximum peak is detected in the S1s spectrum obtained by HAXPES in the range where the binding energy is 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; Gas Chromatography Mass Spectrometry) 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 a secondary battery according to the embodiment is described below.

[0104] An example of a secondary battery manufacturing method includes preparing a positive electrode, preparing a negative electrode, preparing a non-aqueous electrolyte containing a sultone compound, housing the positive and negative electrodes in an outer casing, drying the positive and negative electrodes so that the moisture loss rate of the positive electrode is between 30% and 60% by mass, injecting the non-aqueous electrolyte into the outer casing, sealing the outer casing to obtain a battery precursor, performing the initial charge and discharge on the battery precursor, and aging the battery precursor. After aging, any gases generated can be removed from the battery as appropriate.

[0105] The positive and negative electrodes can be manufactured, for example, by the following methods. For the positive electrode, first, an active material, solid electrolyte, conductive agent, and binder are suspended in a solvent to prepare a slurry. This slurry is applied to one side or both sides of the current collector. Next, the applied slurry is dried to obtain a laminate of the active material-containing layer and the current collector. Then, this laminate is pressed. In this way, the positive electrode is manufactured. On the other hand, for the negative electrode, an active material, conductive agent, and binder are suspended in a solvent to prepare a slurry. This slurry is applied to one side or both sides of the current collector. Next, the applied slurry is dried to obtain a laminate of the active material-containing layer and the current collector. Then, this laminate is pressed. In this way, the negative electrode is manufactured.

[0106] The drying of the positive and negative electrodes housed in the outer casing is performed with a portion of the outer casing open. The moisture loss rate of the positive electrode before and after drying can be set to 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. Furthermore, 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 slutone compound may decompose during the initial charge / discharge or in subsequent processes (e.g., aging). By setting the moisture loss rate of the positive electrode due to drying within the above range, the decomposition of the slutone compound can be promoted, so that the slutone compound can be decomposed to CS bonds and an S-containing film can be formed on the positive electrode active material-containing layer.

[0107] The moisture loss rate of the positive electrode can be measured using the Karl Fischer method with a moisture vaporizer. The positive electrode is cut before and after drying to obtain pre-drying and post-drying samples. Samples are taken so that their weight falls within the range of 0.1 to 1 g. The weight of each pre-drying and post-drying sample is measured. The weighed samples are placed in the boat of the moisture vaporizer and heated to 130°C. The amount of vaporized water is measured using the Karl Fischer method to determine the moisture content of the pre-drying and post-drying samples. Using the obtained values, the moisture loss rate W (mass%) of the positive electrode is calculated using the following formula.

[0108] W = (Z2 / Z1) * 100 W is the percentage of moisture loss in the positive electrode due to drying (mass %), 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. If the drying temperature is between 80°C and 150°C, the drying time can be, for example, between 1 hour and 72 hours. Drying can also be carried out by vacuum drying or reduced-pressure drying.

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

[0111] An example of a secondary battery according to the embodiment will be described with reference to Figures 1 to 5.

[0112] Figures 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 the positive electrode 3's positive electrode active material-containing layer and the negative electrode 4's negative electrode active material-containing layer, and these are wound in a spiral shape to form a flattened shape. The separator 5 covers the surface of either the positive electrode active material-containing layer or the negative electrode active material-containing layer. As shown in Figure 2, multiple strip-shaped positive electrode leads 6 are electrically connected to each of the multiple points on the end of the positive electrode 3 located at the end face of the electrode group 1. Similarly, multiple strip-shaped negative electrode leads 7 are electrically connected to each of the multiple points on the end of the negative electrode 4 located at the same end face. These multiple positive electrode leads 6 are bundled together and electrically connected to a positive electrode conductive tab 8. The positive electrode terminal is formed from the positive electrode leads 6 and the positive electrode conductive tab 8. The negative electrode leads 7 are bundled together and connected to a negative electrode conductive tab 9. The negative electrode terminal is formed from the negative electrode leads 7 and the negative electrode conductive tab 9. The metal sealing plate 10 is fixed to the opening of the metal 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 outlet holes provided in the sealing plate 10. The inner circumferential surface of each outlet hole in the sealing plate 10 is covered with an insulating member 11 to prevent short circuits caused by contact with the positive electrode conductive tab 8 and the negative electrode conductive tab 9.

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

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

[0116] Near the outer edge 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 terminals 13 and positive electrode terminals 14 extend outward from the opening of the bag-shaped outer casing member 12. The wound electrode group 1 is sealed by heat sealing the opening of the bag-shaped outer casing member 12. When heat sealing, the negative electrode terminals 13 and positive electrode terminals 14 are sandwiched by the bag-shaped outer casing member 12 at this opening.

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

[0118] B / A ≤ 1 / 3 (1) However, A is the intensity of the maximum peak appearing in the S1s spectrum with a binding energy between 2468 eV and 2474 eV, and B is the intensity of the maximum peak appearing in the S1s spectrum with a binding energy between 2475 eV and 2483 eV.

[0119] According to the secondary battery of this embodiment, an excellent high-temperature charge-discharge cycle life can be achieved. Second Embodiment The battery pack of the second embodiment includes a plurality of secondary batteries of the embodiment.

[0120] Examples of battery packs include those that include multiple unit cells electrically connected in series and / or parallel as constituent units, and those that include a first unit consisting of multiple unit cells electrically connected in series or a second unit consisting of multiple unit cells electrically connected in parallel. A battery pack may include at least one of these configurations.

[0121] Examples of configurations for electrically connecting multiple secondary batteries in series and / or parallel include connecting multiple batteries, each equipped with an external casing, in series and / or parallel, and connecting multiple electrode groups or bipolar electrode bodies housed in a common housing in series and / or parallel. A specific example of the former is connecting the positive and negative terminals of multiple secondary batteries with a metal busbar (e.g., aluminum, nickel, or copper). A specific example of the latter is housing multiple electrode groups or bipolar electrode bodies in a single housing, electrochemically insulated by partitions, and connecting them electrically in series. In the case of secondary batteries, voltage compatibility with lead-acid batteries is improved by setting the number of batteries electrically connected in series to a range of 5 to 7. To further improve voltage compatibility with lead-acid batteries, a configuration in which 5 or 6 unit cells are connected in series is preferred.

[0122] The housing for the battery pack can be made of metal cans made of aluminum alloy, iron, stainless steel, or other materials, or plastic containers. Furthermore, the thickness of the container should preferably be 0.5 mm or more.

[0123] An example of a battery pack will be explained with reference to Figure 5. The battery pack 200 shown in Figure 5 comprises multiple rectangular secondary batteries 1001 to 1005, shown in Figure 1, as unit cells. The positive electrode conductive tab 8 of battery 1001 and the negative electrode conductive tab 9 of battery 1002 located next to it are electrically connected by leads or busbars 21. Furthermore, the positive electrode conductive tab 8 of battery 1002 and the negative electrode conductive tab 9 of battery 1003 located next to it are electrically connected by leads or busbars 21. In this way, batteries 1001 to 1005 are connected in series.

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

[0125] The battery pack according to this embodiment may further include a protection circuit. The protection circuit has the function of controlling the charging and discharging of the secondary battery. Alternatively, a circuit included in a device that uses the battery pack as a power source (e.g., electronic equipment, automobile, etc.) can be used as the protection circuit for the battery pack.

[0126] Furthermore, the battery pack according to this embodiment may also be further equipped with external terminals for power supply. These external terminals are for outputting current from the secondary battery to the outside and for 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 terminals. Also, when charging the battery pack, the charging current (including regenerative energy from the power of a vehicle such as an automobile) is supplied to the battery pack through the external terminals.

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

[0128] Figure 6 is an exploded perspective view schematically showing an example of a battery pack according to the embodiment. Figure 7 is a block diagram showing an example of the electrical circuit of the battery pack shown in Figure 6.

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

[0130] The container 31 shown in Figure 6 is a bottomed rectangular container with a rectangular base. The container 31 is configured to accommodate a protective sheet 33, a battery pack 200, a printed circuit board 34, and wiring 35. The lid 32 has a rectangular shape. The lid 32 covers the container 31, thereby housing the battery pack 200 and the other components. The container 31 and the lid 32 are provided with openings or connection terminals for connecting to external devices, etc., although these are not shown in the figures.

[0131] The battery pack 200 comprises multiple individual cells 100, a positive electrode lead 22, a negative electrode lead 23, and an adhesive tape 24.

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

[0133] The adhesive tape 24 fastens multiple single cells 100 together. Alternatively, heat-shrinkable tape may be used to secure the multiple single cells 100 instead of the adhesive tape 24. In this case, protective sheets 33 are placed on both sides of the battery pack 200, the heat-shrinkable tape is wrapped around it, and then the heat-shrinkable tape is heat-shrinked to bundle the multiple single cells 100 together.

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

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

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

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

[0138] The external power supply terminal 350 is fixed to the other main surface of the printed circuit board 34. The external power supply terminal 350 is electrically connected to equipment located outside the battery pack 300. The external power supply terminal 350 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 circuit board 34. The protection circuit 346 is connected to the positive terminal 352 via the positive side wiring 348a. The protection circuit 346 is connected to the negative terminal 353 via the negative side wiring 348b. The protection circuit 346 is also electrically connected to the positive side connector 342 via wiring 342a. The protection circuit 346 is also electrically connected to the negative side connector 343 via wiring 343a. Furthermore, the protection circuit 346 is electrically connected to each of the multiple single cells 100 via wiring 35.

[0140] The protective sheet 33 is positioned on both inner surfaces in the long-side direction of the housing container 31 and on the inner surface in the short-side direction facing the printed circuit 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 the charging and discharging of multiple single cells 100. The protection circuit 346 also disconnects the electrical connection between the protection circuit 346 and the external terminals 350 (positive terminal 352, negative terminal 353) for supplying power to external devices, based on a detection signal transmitted from the thermistor 345 or a detection signal transmitted from an individual single cell 100 or a battery pack 200.

[0142] An example of a detection signal transmitted from the thermistor 345 is a signal indicating that the temperature of a single cell 100 is above a predetermined temperature. An example of a detection signal transmitted from an individual single cell 100 or a battery pack 200 is a signal indicating that overcharging, over-discharging, or overcurrent has been detected in a single cell 100. When detecting overcharging, etc., in an individual single cell 100, the battery voltage may be detected, or the positive electrode potential or negative electrode potential may be detected. In the latter case, a lithium electrode to be used as a reference electrode is inserted into each individual single cell 100.

[0143] Furthermore, the protection circuit 346 may be a circuit included in a device that uses the battery pack 300 as a power source (for example, an electronic device, an automobile, etc.).

[0144] Furthermore, as described above, the battery pack 300 is equipped with an external terminal 350 for power supply. Therefore, the battery pack 300 can output current from the battery pack 200 to an external device via the external terminal 350, and can also input current from an external device to the battery pack 200. In other words, when the battery pack 300 is used as a power source, current from the battery pack 200 is supplied to the external device through the external terminal 350. Also, when charging the battery pack 300, charging current from an external device is supplied to the battery pack 300 through the external terminal 350. When this battery pack 300 is used as an on-board battery, the regenerative energy of the vehicle's power can be used as the charging current from the external device.

[0145] The battery pack 300 may comprise multiple battery packs 200. In this case, the multiple battery packs 200 may be connected in series, in parallel, or in a combination of series and parallel connections. The printed circuit board 34 and wiring 35 may also be omitted. In this case, the positive lead 22 and the negative lead 23 may be used as the positive and negative terminals of the external terminals for energization, respectively.

[0146] Such battery packs are used in applications where excellent cycle performance is required, for example, when drawing high currents. Specifically, these battery packs are used as power supplies for electronic devices, stationary batteries, and on-board batteries for various vehicles (including batteries for railway vehicles). Examples of electronic devices include digital cameras. These battery packs are particularly suitable for use as on-board batteries.

[0147] The battery pack according to this embodiment comprises a secondary battery or a battery pack according to this embodiment. Therefore, a battery pack with excellent cycle life performance at high temperatures can be realized.

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

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

[0150] Examples of vehicles according to the fourth embodiment include, for example, two-wheeled to four-wheeled hybrid electric vehicles, two-wheeled to four-wheeled electric vehicles, electric assist bicycles, and railway vehicles.

[0151] The mounting location 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, it can be mounted in the engine compartment, at the rear of the vehicle, or under the seats.

[0152] The vehicle according to the fourth embodiment may be equipped with multiple battery packs. In this case, the batteries contained 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, if each battery pack contains 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, if each battery pack contains 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 the fourth embodiment will be described with reference to the drawings.

[0154] Figure 8 is a schematic partial transparency diagram showing an example of a vehicle according to the fourth embodiment.

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

[0156] This vehicle 400 may be equipped with multiple battery packs 300. In this case, the batteries contained in the battery pack 300 (for example, single cells or battery packs) may be connected in series, in parallel, or in a combination of series and parallel connections.

[0157] Figure 8 illustrates an example in which the battery pack 300 is mounted in the engine compartment located in front of the vehicle body 40. As described above, the battery pack 300 may also be mounted, for example, in the rear of the vehicle body 40 or under the seats. 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 from the vehicle 400's power.

[0158] Next, an embodiment of the vehicle according to the fifth embodiment will be described with reference to Figure 9.

[0159] Figure 9 is a schematic diagram showing an example of a control system for the electrical system in a vehicle according to the embodiment. The vehicle 400 shown in Figure 9 is an electric vehicle.

[0160] The vehicle 400 shown in Figure 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 for 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] Vehicle 400 has its vehicle power supply 41 mounted, for example, in the engine compartment, at the rear of the vehicle body, or under the seats. Note that in the vehicle 400 shown in Figure 9, the mounting location of the vehicle power supply 41 is shown in a schematic manner.

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

[0163] Battery pack 300a comprises a battery pack 200a and a battery pack monitoring device 301a (e.g., VTM: Voltage Temperature Monitoring). Battery pack 300b comprises a battery pack 200b and a battery pack monitoring device 301b. Battery pack 300c comprises a battery pack 200c and a battery pack monitoring device 301c. Battery packs 300a to 300C are battery packs similar to the aforementioned battery pack 300, and battery packs 200a to 200c are battery packs similar to the aforementioned battery pack 200. Battery packs 200a to 200c are electrically connected in series. Battery packs 300a, 300b, and 300c can each be independently removed and replaced with another battery pack 300.

[0164] Each of the battery packs 200a to 200c comprises multiple single cells connected in series. At least one of the multiple single cells is a secondary battery according to the first embodiment. Each of the battery packs 200a to 200c is charged and discharged through a positive terminal 413 and a negative terminal 414.

[0165] The battery management device 411 communicates with the battery pack monitoring devices 301a to 301c and collects information such as voltage and temperature for each of the single cells 100 included in the battery packs 200a to 200c included in the vehicle power supply 41. In this way, the battery management device 411 collects information related to the maintenance of the vehicle power supply 41.

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

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

[0168] The vehicle power supply 41 may also have an electromagnetic contactor (for example, a switch device 415 shown in Figure 9) that switches the presence or 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 turns on when charging is performed on the battery packs 200a to 200c, and a main switch (not shown) that turns on when the output from the battery packs 200a to 200c is supplied to the 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 located near the switch element. Electromagnetic contactors such as the switch device 415 are 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 high voltage of three-phase alternating current (AC) for motor drive. 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 control signals 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 using power supplied from the inverter 44. The driving force generated by the rotation of the drive motor 45 is transmitted to the axle and drive wheels W, for example, via a differential gear unit.

[0171] Although not shown in the diagram, vehicle 400 is also equipped with a regenerative braking mechanism. The regenerative braking mechanism rotates the drive motor 45 when vehicle 400 is braked, converting 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 DC current. The converted DC current is input to the vehicle power supply 41.

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

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

[0174] External terminal 43 is connected to battery management device 411. External terminal 43 can be connected to an external power supply, for example.

[0175] The vehicle ECU 42, in response to operational inputs from the driver and others, coordinates control of the vehicle power supply 41, switch device 415, inverter 44, etc., together with other management and control devices, including the battery management device 411. 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 related 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 a battery pack according to the embodiment. Therefore, it is possible to realize a vehicle with excellent driving performance over a wide temperature range from low to high temperatures. [Examples]

[0177] The embodiments of the present invention will be described in detail below with reference to the drawings, but the present invention is not limited to the embodiments described below. (Example 1) <Fabrication of the positive electrode> As the positive electrode active material, 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 used as the 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 mixed with N-methylpyrrolidone (NMP) as a solvent in a ratio of 87% by mass:5% by mass:5% by mass:3% by mass 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. The coating was then dried in a constant temperature bath at 120°C to form a positive electrode active material-containing layer. The positive electrode active material-containing layer was pressed to obtain the positive electrode.

[0178] <Fabrication of the negative electrode> Monoclinic niobium titanium oxide (TiNb2O7) powder was prepared as the negative electrode active material. The average secondary particle size of the niobium titanium oxide powder was 7.5 μm. The specific surface area of ​​the niobium titanium oxide powder was 4.0 m². 2 The concentration was / g. 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% by mass:5.5% by mass:1.5% by mass:2% by 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. Then, the coating was dried in a constant temperature bath at 120°C to form a negative electrode active material-containing layer. The negative electrode active material-containing layer was pressed to obtain the negative electrode.

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

[0180] A laminated electrode group was fabricated by alternately stacking positive and negative electrodes with a separator placed between them. This electrode group was then housed in a pack (outer packaging) made of a laminate film composed of aluminum foil and polypropylene layers formed on both sides of it.

[0181] Vacuum drying was performed at 80°C for 10 hours with a portion of the exterior material open. As a result, the moisture content reduction from the positive electrode before drying was 50% by mass.

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

[0183] After injecting a liquid non-aqueous electrolyte into the outer casing, the casing was sealed. Subsequently, a flat-shaped non-aqueous electrolyte secondary battery with a capacity of 1.5 Ah was fabricated by performing initial charge-discharge and aging. (Example 2) A secondary battery was fabricated in the same manner as in Example 1, except that the negative electrode prepared by the following method was used.

[0184] <Fabrication of the negative electrode> Monoclinic niobium titanium oxide (TiNb2O7) powder was prepared as the negative electrode active material. The average secondary particle size of the niobium titanium oxide powder was 7.5 μm. The specific surface area of ​​the niobium titanium oxide powder was 4.0 m². 2 The concentration was / g. Acetylene black was prepared as the conductive agent, and CMC and SBR were prepared as binders. 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% by mass:5% by mass:2% by mass:2% by mass:3% by 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. Then, the coating was dried in a constant temperature bath at 120°C to form a negative electrode active material-containing layer. The negative electrode active material-containing layer was pressed to obtain the negative electrode. (Example 3) A secondary battery was fabricated in the same manner as in Example 2, except that the PS concentration of the liquid non-aqueous electrolyte (non-aqueous electrolyte solution) was changed to 3% by mass, and the vacuum drying with a portion of the exterior components open was changed to 13 hours at 80°C. (Example 4) The solid electrolyte contained in the positive electrode is Li 1.2 Zr 1.9 Ca 0.1 A secondary battery was fabricated in the same manner as in Example 2, except that the material was changed to (PO4)3. (Example 5) Lithium hexafluoride phosphate (LiPF6) was dissolved at a concentration of 1 M (mol / L) in a mixed solvent of propylene carbonate (PC) and ethyl propionate (EP) in a volume ratio of 1:4. 1,3-propanesultone (PS) and lithium difluorophosphate (DFP) were added to this mixture to a concentration of 1.0% by mass, thereby preparing a liquid non-aqueous electrolyte. A secondary battery was fabricated in the same manner as in Example 2, except that the obtained liquid non-aqueous electrolyte 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 the O2 was changed to O2. (Example 7) The negative electrode active material is Ti2Nb 10 O 29 The secondary battery was fabricated in the same manner as in Example 2, except for the change made to [specific component]. (Example 8) A negative electrode without a solid electrolyte was fabricated in the same manner as in Example 1, except that the negative electrode active material was changed to TiO2(B).

[0185] Furthermore, lithium hexafluoride phosphate (LiPF6) was dissolved at a concentration of 1 M (mol / L) in a mixed solvent of propylene carbonate (PC) and diethyl carbonate (DEC) in a volume ratio of 1:2. 1,3-propanesultone (PS) was then added to this solution to a concentration of 1% by mass to prepare a liquid non-aqueous electrolyte (non-aqueous electrolyte solution). A secondary battery was fabricated in the same manner as in Example 1, except that the obtained negative electrode and liquid non-aqueous electrolyte (non-aqueous electrolyte solution) were used. (Example 9) The negative electrode active material is Li4Ti5O 12 A negative electrode without a solid electrolyte was prepared in the same manner as in Example 1, except for the change made to [specific component].

[0186] A secondary battery was fabricated in the same manner as in Example 8, except that the obtained negative electrode was used. (Comparative Example 1) As the positive electrode active material, 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% by mass:4.6% by mass:1.9% by 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. Then, the coating was dried in a constant temperature bath at 120°C to form a positive electrode active material-containing layer. The positive electrode active material-containing layer was pressed to obtain the positive electrode.

[0187] A secondary battery was fabricated in the same manner as in Example 1, except that the resulting positive electrode without added solid electrolyte and a liquid non-aqueous electrolyte having the same composition as in Example 8 were used. (Comparative Example 2) Lithium hexafluoride phosphate (LiPF6) was dissolved at a concentration of 1 M (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 solution to a concentration of 1% by mass to prepare a liquid non-aqueous electrolyte (non-aqueous electrolyte solution). A secondary battery was prepared in the same manner as in Example 2, except that the obtained liquid non-aqueous electrolyte was used. (Comparative Example 3) Lithium hexafluoride phosphate (LiPF6) was dissolved at a concentration of 1 M (mol / L) in a mixed solvent of propylene carbonate (PC) and ethyl propionate (EP) in a volume ratio of 1:4. To this, lithium bisfluorosulfonyliimide (LiN(FSO2)2:LiFSI) was added to a concentration of 1% by mass to prepare a liquid non-aqueous electrolyte (non-aqueous electrolyte solution).

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

[0189] Table 2 shows 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 non-aqueous solvent of the non-aqueous electrolyte, the additives of the non-aqueous electrolyte, and the lithium salt of the non-aqueous electrolyte for each of the examples and comparative examples. In the composition of the non-aqueous solvent of the non-aqueous electrolyte, PC:EP = 1:4 indicates that the volume ratio of PC to EP is 1:4.

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

[0191] As is clear from the comparison between FIGS. 10 and 11, in the positive electrode of Example 1, S-containing substances having a C-S bond are present more than S-containing substances having -SO4 (SO4 group). From the values of the peak ratio (B / A) in Table 3, it can be seen that the positive electrodes of Examples 2 to 9 also have a large amount of S-containing substances having a C-S bond, similar to 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 layered form. On the other hand, in the positive electrodes of Comparative Examples 1 and 3, a large amount of S-containing substances having -SO3 (SO3 group) and -SO4 (SO4 group) were present. In the positive electrode of Comparative Example 2, the presence of S element could not be confirmed.

[0192] Table 3 shows the moisture loss rate (mass%) of the positive electrode during electrode group drying for the secondary batteries of Examples 1-9 and Comparative Examples 1-3. The method for measuring the moisture loss rate (mass%) is as described above. From the measurement results shown in Table 3, when the composition of the positive electrode active material and the solid electrolyte of the positive electrode are the same, the variation in the moisture loss rate is small, as shown in Examples 1, 2, 5, and 7. On the other hand, in Example 4, where the composition of the solid electrolyte of the positive electrode is different from that of Example 2, and in Example 6, where the composition of the positive electrode active material is different from that of Example 2, a tendency for the moisture loss rate to be smaller than that of Example 2 is observed. Although the drying conditions for the electrode groups of Comparative Examples 1 and 3 were the same as in Example 1, the moisture loss 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 A compound represented as (PO4)3 with 0.1 ≤ x ≤ 0.5, Li 1+2x Zr 1-x Ca x This is because compounds represented as (PO4)3 and satisfying the condition 0 ≤ x < 1 tend to increase the water content at the positive electrode.

[0193] For the secondary batteries of Examples 1-9 and Comparative Examples 1-3, a SOC 0-90% cycle test was performed in an environment of 70°C. Specifically, in an environment of 70°C, constant current charging was performed at 1C, followed by constant voltage charging at 2.83V until the current value converged to 1 / 20C, bringing the state of charge (SOC) of the secondary battery to 90%. Next, constant voltage discharge was performed at 1C until 1.5V cut, bringing the charge state to 0%. The rest period between charging and discharging was set to 10 min. This charge-discharge cycle was repeated, and the number of cycles at which the discharge capacity retention rate became 80% (with the discharge capacity retention rate of the first cycle being 100%) was defined as the charge-discharge cycle life and is listed in Table 3.

[0194] [Table 2]

[0195] [Table 3]

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

[0197] According to at least one embodiment or example of the secondary battery described above, the S1s spectrum obtained by hard X-ray photoelectron spectroscopy satisfies equation (1) below. Therefore, a secondary battery with excellent high-temperature charge-discharge cycle life can be provided.

[0198] B / A ≤ 1 / 3 (1) However, A is the intensity of the maximum peak appearing in the S1s spectrum with a binding energy between 2468 eV and 2474 eV, and B is the intensity of the maximum peak appearing in the S1s spectrum with a binding energy between 2475 eV and 2483 eV.

[0199] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents.

[0200] The invention according to the embodiment is described below. <1> A positive electrode comprising a positive electrode active material and a solid electrolyte, The negative electrode and, It comprises a non-aqueous electrolyte, The positive electrode is a secondary battery that satisfies equation (1) below in the S1s spectrum obtained 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 is the secondary battery according to <1>, which contains a sultone compound. <3> The sultone compound is the secondary battery according to <1> or <2>, which contains 1,3-propane sultone. <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 is 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[[ID=1十七]] x MO2, and in the general formula, 0 < x ≦ 1, and M contains at least one element selected from the group consisting of Ni, Co, and Mn, and is 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 and 0.1 ≦ x ≦ 0.5, or at least one of compounds represented by Li 1+2x Zr 1-x [[ID=三十二]]Ca x (PO4)3 and 0 ≦ x < 1, and is 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 is 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 The battery pack according to <8>, further comprising <10> comprising a plurality of said secondary batteries, The battery pack according to <8> or <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 any one of <8> to <10>. <12> The vehicle according to <11>, including a mechanism for converting the kinetic energy of the vehicle into regenerative energy.

Explanation of Reference Numerals

[0202] 1... electrode group, 2... container (outer 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... outer member, 13... negative electrode terminal, 14... positive electrode terminal, 200... assembled battery, 1001 - 1005... secondary battery, 21... lead (bus bar), 300... battery pack, 100... unit cell, 200... assembled battery, 34... printed wiring board, 345... thermistor, 346... protection circuit, 350... external terminal for energization, 40... vehicle body, 300... battery pack, 400... vehicle, 41... vehicle power source, 411... battery management device, 412... communication bus, 300a - c... battery packs, 301a - c... assembled battery monitoring devices, 200a - c... assembled batteries, 413... positive electrode terminal, 414... negative electrode terminal, 44... inverter, 45... drive motor, 43... external terminal, 42... vehicle ECU, L1, L2... connection lines, W... drive wheel.< / haxpes>

Claims

1. A positive electrode comprising a positive electrode active material and a solid electrolyte, The negative electrode and, It comprises a non-aqueous electrolyte, The positive electrode is a secondary battery that satisfies equation (1) below in the S1s spectrum obtained by hard X-ray photoelectron spectroscopy. 1 / 50 ≤ B / A ≤ 1 / 3 (1) However, A is the intensity of the maximum peak appearing in the S1s spectrum with a binding energy of 2468 eV or more and 2474 eV or less, and B is the intensity of the maximum peak appearing in the S1s spectrum with a binding energy of 2475 eV or more and 2483 eV or less.

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

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

4. 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 the surface of the positive electrode active material-containing layer.

5. The positive electrode active material is of the general formula Li x MO 2 The secondary battery according to claim 4, comprising a composite oxide represented by the general formula, wherein in the general formula, 0 < x ≤ 1, and M comprises at least one element selected from the group consisting of Ni, Co, and Mn.

6. The solid electrolyte is Li 1+x Al x Ti 2-x (PO 4 ) 3 It is expressed as 0.1 ≤ x ≤ 0.

5. A compound or Li 1+2x Zr 1-x Ca x (PO 4 ) 3 The secondary battery according to claim 4, comprising at least one of the compounds represented by 0 ≦ x < 1.

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

8. A secondary battery according to any one of claims 1 to 7, External terminals for power supply, A battery pack equipped with a protection circuit.

9. The device comprises multiple secondary batteries, The battery pack according to claim 8, wherein the secondary batteries are electrically connected in series, in parallel, or in a combination of series and parallel.

10. A vehicle equipped with the battery pack described in claim 8.

11. The vehicle according to claim 10, comprising a mechanism for converting the kinetic energy of the vehicle into regenerative energy and supplying a charging current to the battery pack through the external terminal for energization.

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