Composite, positive electrode composite material, positive electrode for lithium ion battery, lithium ion battery, method for producing composite, use of activated carbon, and method for producing activated carbon

Abstract

A composite containing an activated carbon having a specific surface area of 1400 m2 / g or more and satisfying one or both of the following conditions (A) and (B), and elemental sulfur and / or a discharge product of the elemental sulfur. (A) The peak width of the D band in the Raman spectrum of the activated carbon is 100 cm-1 or less. (B) The peak width of the G band in the Raman spectrum of the activated carbon is 70 cm-1 or less.

Description

Technical Field

[0001] This invention relates to composites, positive electrode composite materials, positive electrodes for lithium-ion batteries, lithium-ion batteries, manufacturing methods of composites, uses of activated carbon, and manufacturing methods of activated carbon.

[0002] Specifically, the present invention relates to a composite material capable of imparting excellent rate characteristics to lithium-ion batteries and having a low environmental impact during manufacturing, a positive electrode composite material, a positive electrode for lithium-ion batteries, a lithium-ion battery, a method for manufacturing the composite material, the use of activated carbon, and a method for manufacturing activated carbon. Background Technology

[0003] Regarding the capacity of all-solid-state lithium-ion batteries, the method of using sulfur as the positive electrode has been studied for its theoretically high capacity. However, sulfur has low electronic conductivity and lithium-ion conductivity, resulting in a technical problem of low discharge capacity (poor rate performance) at high current densities.

[0004] In Patent Document 1, a cathode composite material comprising a solid electrolyte and a sulfur-based active material is proposed as a cathode composite material for all-solid-state lithium-ion batteries. The solid electrolyte comprises Li or Na, S, and a halogen element selected from the group consisting of I, Br, Cl, and F. Here, the sulfur-based active material is used in combination with Ketjen black or activated carbon obtained through alkali activation.

[0005] In addition, although not for battery applications, there are reports of techniques for obtaining activated carbon by activation under pressure for purposes such as improving ethanol adsorption capacity (Non-Patent Literature 1, 2).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2014-011033

[0009] Non-patent literature

[0010] Non-patent literature 1: "Pressurized physical activation: A simple production method for activated carbon with a highly developed pore structure", Carbon, 183 (2021), pp. 735-742.

[0011] Non-Patent Literature 2: "Study on the applicability of pressurized physically activated carbon as an adsorbent in adsorption heat pumps", RSC Adv., 2022, 12, pp. 2558-2563. Summary of the Invention

[0012] However, in the prior art, represented by Patent Document 1, there is room for further improvement from the perspectives of improving the rate characteristics of lithium-ion batteries and reducing the environmental impact during manufacturing.

[0013] One of the objectives of this invention is to provide a composite material, a positive electrode composite material, a positive electrode for lithium-ion batteries, a lithium-ion battery, a method for manufacturing the composite material, the use of activated carbon, and a method for manufacturing activated carbon that can impart excellent rate characteristics to lithium-ion batteries and have a low environmental impact during manufacturing.

[0014] The inventors conducted in-depth research and found that the composite of activated carbon and sulfur activated under specific conditions can impart excellent rate performance to lithium-ion batteries, and the environmental impact during manufacturing is relatively small, thus completing the present invention.

[0015] According to the present invention, the following composites, etc., can be provided.

[0016] 1. A composite comprising:

[0017] Specific surface area is 1400 m² 2 Activated carbon of / g or above that meets one or both of the following conditions (A) and (B), and

[0018] At least one of elemental sulfur and its discharge products.

[0019] (A) The peak width of band D in the Raman spectrum of the activated carbon is 100 cm⁻¹. -1 the following.

[0020] (B) The peak width of the G band in the Raman spectrum of the activated carbon is 70 cm⁻¹. -1 the following.

[0021] 2. The composite as described in 1, wherein the activated carbon satisfies conditions (A) and (B).

[0022] 3. The composite as described in 1 or 2, wherein the activated carbon has a micropore capacity of 0.5 cc / g or higher.

[0023] 4. The composite as described in any one of 1 to 3, wherein the average pore width of the activated carbon is less than 1.55 nm.

[0024] 5. The composite as described in any one of 1 to 4, comprising, relative to 100 parts by mass of the activated carbon, 150 to 600 parts by mass of the elemental sulfur and the discharge products of the elemental sulfur.

[0025] 6. A positive electrode composite material comprising the composite of any one of 1 to 5, and a sulfide solid electrolyte.

[0026] 7. A positive electrode composite material comprising a composite and a sulfide solid electrolyte, said composite comprising a specific surface area of ​​1400 m². 2 The activated carbon of 1 g or more, and at least one of elemental sulfur and its discharge products,

[0027] The positive electrode composite material satisfies one or both of the following conditions (A') and (B').

[0028] (A') The peak width of the D band in the Raman spectrum of the cathode composite material is 100 cm⁻¹. -1 the following.

[0029] (B') The peak width of the G band in the Raman spectrum of the positive electrode composite material is 90 cm⁻¹. -1 the following.

[0030] 8. The positive electrode composite material as described in 7, wherein the positive electrode composite material satisfies conditions (A') and (B').

[0031] 9. The positive electrode composite material as described in any one of 6 to 8, wherein the sulfide solid electrolyte comprises at least lithium atoms, phosphorus atoms, sulfur atoms and halogen atoms.

[0032] 10. The positive electrode composite material according to any one of 6 to 9, comprising more than 40% by mass of the elemental sulfur and the discharge products of elemental sulfur.

[0033] 11. A positive electrode for a lithium-ion battery, comprising any one of the positive electrode composite materials described in any one of the following: 6 to 10.

[0034] 12. A lithium-ion battery comprising the positive electrode for a lithium-ion battery as described in 11.

[0035] 13. A method for manufacturing a composite, comprising:

[0036] Gas activation of activated carbon under pressure; and

[0037] The activated carbon is combined with at least one of elemental sulfur and the discharge products of elemental sulfur.

[0038] 14. A method for manufacturing a composite, comprising: combining activated carbon that has been gas-activated under pressure with at least one of elemental sulfur and discharge products of elemental sulfur.

[0039] 15. The method for manufacturing the composite as described in 13 or 14, wherein the gas activation is carried out at a pressure of 2 atmospheres or more.

[0040] 16. A method for manufacturing a composite, comprising: taking a composite with a specific surface area of ​​1400 m² 2 Activated carbon of 6g or more that meets one or both of the following conditions (A) and (B) is compounded with at least one of elemental sulfur and the discharge products of elemental sulfur.

[0041] (A) The peak width of band D in the Raman spectrum of the activated carbon is 100 cm⁻¹. -1 the following.

[0042] (B) The peak width of the G band in the Raman spectrum of the activated carbon is 70 cm⁻¹. -1 the following.

[0043] 17. A composite manufactured by the method for manufacturing a composite according to any one of 13 to 16.

[0044] 18. The use of activated carbon for a specific surface area of ​​1400 m² 2 The use of activated carbon of 6 g or more that meets one or both of the following conditions (A) and (B) combined with at least one of elemental sulfur and the discharge products of elemental sulfur.

[0045] (A) The peak width of band D in the Raman spectrum of the activated carbon is 100 cm⁻¹. -1 the following.

[0046] (B) The peak width of the G band in the Raman spectrum of the activated carbon is 70 cm⁻¹. -1 the following.

[0047] 19. Use of activated carbon for the purpose of combining activated carbon that has been gas-activated under pressure with at least one of elemental sulfur and discharge products of elemental sulfur.

[0048] 20. A method for manufacturing activated carbon, the activated carbon being used for compounding with at least one of elemental sulfur and discharge products of elemental sulfur.

[0049] This includes gas activation of activated carbon under pressure.

[0050] 21. The method for manufacturing activated carbon as described in 20, wherein the gas activation is carried out at a pressure of 2 atmospheres or more.

[0051] According to the present invention, it is possible to provide a composite material that imparts excellent rate characteristics to lithium-ion batteries and has a low environmental impact during manufacturing, a positive electrode composite material, a positive electrode for lithium-ion batteries, a lithium-ion battery, a method for manufacturing the composite material, the use of activated carbon, and a method for manufacturing activated carbon. Attached Figure Description

[0052] Figure 1 This is the Raman spectrum (raw data) of Example 1.

[0053] Figure 2 This graph illustrates an example of how to determine the peak widths of the D and G bands in a Raman spectrum. The solid line represents the Raman spectrum (raw data), the dotted line represents the smoothed Raman spectrum, and the dashed line represents the differential curve. The scale on the right side of the graph corresponds to the differential curve. Detailed Implementation

[0054] The following describes in detail the composite, positive electrode composite material, positive electrode for lithium-ion batteries, lithium-ion batteries, manufacturing method of the composite, activated carbon, and manufacturing method of activated carbon of the present invention.

[0055] Furthermore, in this specification, "x~y" represents a numerical range of "above x and below y". The upper and lower limits of the numerical range can be combined arbitrarily.

[0056] 1. Composite and method for manufacturing composite

[0057] A composite of one aspect of the present invention comprises:

[0058] Specific surface area is 1400 m² 2 Activated carbon of / g or above that meets one or both of the following conditions (A) and (B), and

[0059] At least one of elemental sulfur and its discharge products.

[0060] (A) The peak width of band D in the Raman spectrum of the activated carbon is 100 cm⁻¹. -1 the following.

[0061] (B) The peak width of the G band in the Raman spectrum of the activated carbon is 70 cm⁻¹. -1 the following.

[0062] According to the composite of this scheme, it is possible to obtain the effect of giving lithium-ion batteries excellent rate characteristics and low environmental impact during manufacturing.

[0063] The alkali-activated activated carbon used in Patent Document 1 generates a large amount of alkali as waste during manufacturing, resulting in a significant environmental impact and high manufacturing costs due to wastewater treatment expenses. Compared to alkali-activated activated carbon, the activated carbon used in this solution not only reduces the environmental impact and manufacturing costs but also significantly improves the rate performance of lithium-ion batteries. In particular, it exhibits superior rate performance compared to alkali-activated activated carbon with the same specific surface area. The reasons for this rate performance effect may not be explicit, but can be inferred as follows.

[0064] First, by making the specific surface area of ​​activated carbon 1400 m² 2 With a density of 1 g or more, elemental sulfur or its discharge products can be arranged more thinly and uniformly on carbon materials, enabling uniform electron supply and high battery performance.

[0065] Regarding condition (A), the peak width of band D in the Raman spectrum is estimated to be 100 cm⁻¹. -1 The activated carbon described below has fewer defect types and fewer sites for capturing lithium ions. This effect is achieved with a specific surface area of ​​1400 m². 2 The synergistic effect of / g and above gives lithium-ion batteries excellent rate performance.

[0066] Furthermore, regarding condition (B), it is assumed that the peak width of the G band in the Raman spectrum is 70 cm⁻¹. -1 The localized graphite structures in the following activated carbons are all grown in a textured manner, presumably exhibiting excellent electronic conductivity, chemical stability, and lithium conduction via the graphite interlayers, all attributed to the graphite structure. This effect is consistent with a specific surface area of ​​1400 m². 2 The synergistic effect of / g and above gives lithium-ion batteries excellent rate performance.

[0067] (Activated carbon)

[0068] In one embodiment, the peak width of the D band in the Raman spectrum of activated carbon is 10–100 cm⁻¹. -1 10-99cm -1 20-95cm -1 Or 50-90cm -1 .

[0069] If the half-width of the D-band is 100cm -1 The activated carbon has fewer types of defects and fewer sites for capturing lithium ions. Therefore, when this activated carbon is used in batteries, it is expected that the resistance during lithium ion conduction will be reduced.

[0070] Additionally, the D-band is typically at 1350cm. -1 The peak with the greatest intensity is located nearby. 1350cm -1"Nearby" is, for example, 1350±50cm. -1 1350±30cm -1 Or 1350±20cm -1 The range.

[0071] The peak width of the D band in the Raman spectrum of activated carbon is a value measured by the method described in the examples.

[0072] In one embodiment, the peak width of the G band in the Raman spectrum of activated carbon is 10–70 cm⁻¹. -1 20-65cm -1 Or 30-60cm -1 .

[0073] If the peak width of the G band is 70cm -1 The following theory suggests that the graphite structure of activated carbon is homogeneous, which can be expected to provide high conductivity and lithium conduction between graphite layers.

[0074] The G-band is typically at 1580cm. -1 The peak with the greatest intensity is located nearby. 1580cm -1 "Nearby" is, for example, 1580±50cm -1 1580±30cm -1 Or 1580±20cm -1 The range.

[0075] The peak width of the G band in the Raman spectrum of activated carbon is a value measured by the method described in the examples.

[0076] In one embodiment, the activated carbon satisfies conditions (A) and (B). Consequently, the activated carbon has fewer lithium-capturing sites and higher conductivity and lithium conductivity, allowing it to perform better as a conductive aid in the battery, which is crucial for the conduction of ions and electrons. As a result, it imparts superior rate performance to the lithium-ion battery.

[0077] In one embodiment, the specific surface area of ​​the activated carbon is 1400–6000 m². 2 / g. By making the specific surface area 1400m² 2 With a specific surface area of ​​1600 m² or more, elemental sulfur or its discharge products can be more thinly and uniformly distributed in carbon materials, allowing for a more uniform supply of electrons and resulting in higher battery performance. From this perspective, a specific surface area of ​​1600 m² is preferred. 2 / g or more, preferably 2000m 2 / g or more, further preferably 2200m 2 / g or more. By achieving a specific surface area of ​​6000m² 2 / g or less, 5000m 2 / g or less, 4000m 2 / g or less, 3500m 2 / g or less, and then 3000m 2 When the yield is below / g, the yield of activated carbon is higher and the productivity is excellent.

[0078] The specific surface area of ​​the activated carbon is a value measured by the method described in the examples.

[0079] In one embodiment, the micropore capacity of the activated carbon is 0.5 cc / g or more. This increases the amount of sulfur that can be retained in the activated carbon in the form of tiny domains, allowing for increased sulfur usage in the charge-discharge reaction and thus improving the battery's energy density. From this perspective, the micropore capacity of the activated carbon is more preferably 0.6 cc / g or more, and even more preferably 0.7 cc / g or more. Furthermore, the micropore capacity is more preferably 0.8 cc / g or more, and 0.9 cc / g or more. The micropore capacity of the activated carbon is typically 3.0 cc / g or less.

[0080] The pore capacity of the activated carbon is a value measured by the method described in the examples.

[0081] In one embodiment, the average pore width of the activated carbon is 1.55 nm or less. This disperses the sulfur held in the activated carbon in a smaller domain, thereby uniformly imparting electronic conductivity. As a result, electrochemical reactions involving sulfur become easier to occur, thereby increasing sulfur utilization and improving the energy density of the battery. From this viewpoint, the average pore width of the activated carbon is preferably 1.50 nm or less, and more preferably 1.40 nm or less.

[0082] The average pore width of the activated carbon is determined by the method described in the examples (α). s The value measured by (method).

[0083] (Elemental sulfur and its discharge products)

[0084] There is no particular limitation on elemental sulfur (sulfur), but a purity of 95% by mass or more is preferred, 96% by mass or more is more preferred, and 97% by mass or more is particularly preferred.

[0085] Examples of crystal systems for elemental sulfur include α-sulfur (orthorhombic), β-sulfur (monoclinic), γ-sulfur (monoclinic), and amorphous sulfur. These can be used individually or in combination. Elemental sulfur becomes a molten liquid upon heating.

[0086] Elemental sulfur is partially or completely converted into discharge products during the battery reaction. Therefore, in the composite of one embodiment, discharge products of elemental sulfur are present. In the presence of discharge products, the amount of sulfur contained in the composite is set as the sum of the amount of elemental sulfur and the sulfur contained in the discharge products.

[0087] Examples of discharge products of elemental sulfur include Li2S in its fully discharged state and lithium polysulfides such as Li2S2, Li2S4, Li2S6, and Li2S8, which are intermediate stages of the discharge process.

[0088] In one embodiment, in the composite, some or all of the elemental sulfur is attached (impregnated) within the pores of the activated carbon. Furthermore, elemental sulfur not impregnated within the pores exists in a manner that coats some or all of the activated carbon. Whether sulfur is impregnated within the pores of the activated carbon can be confirmed by analyzing the particle cross-section of the activated carbon using elemental mapping analytical methods such as SEM-EDS and TEM-EDX, and evaluating the overlap between the elements originating from the activated carbon and the sulfur element.

[0089] In one embodiment, the composite contains a high content of elemental sulfur, thus elemental sulfur is also present outside the pores of the activated carbon. In this case, the composite can be in the form of granules, but it can also be pulverized by mechanical crushing.

[0090] In one embodiment, the composite contains, relative to 100 parts by mass of activated carbon, 150–600 parts by mass, 200–550 parts by mass, or 220–500 parts by mass (calculated as sulfur) of elemental sulfur and discharge products of elemental sulfur. If the content is 600 parts by mass or less, the sulfur in the activated carbon can be uniformly imparted with conductivity, and higher battery performance can be expected when the composite material is manufactured. If the content is 150 parts by mass or more, sufficient sulfur content can be ensured, and electrode materials with higher energy density can be obtained.

[0091] The method for manufacturing the composite of one aspect of the present invention described above is not particularly limited.

[0092] In one embodiment, the composite of one aspect of the present invention is a composite manufactured by any one of the manufacturing methods of the composites of the first to third aspects of the present invention described below. Furthermore, the matters described for any of the first to third aspects can be appropriately combined with other aspects.

[0093] A method for manufacturing a composite according to one aspect of the present invention (also referred to as "the first aspect") includes: gas activation of activated carbon under pressure; and composite of the activated carbon with at least one of elemental sulfur and discharge products of elemental sulfur.

[0094] There are no particular limitations on the activated carbon used for activation treatment. Examples include activated carbon derived from phenolic resin obtained by carbonizing spherical phenolic resin, charcoal, bamboo charcoal, coconut shell charcoal, etc., which are carbonized from plants, carbon derived from petroleum pitch, carbon derived from coal pitch, carbon derived from rayon, carbon derived from acrylonitrile, etc.

[0095] Activated carbon derived from phenolic resins has a high carbon residue and is a synthetic resin raw material, thus offering high structural controllability and is therefore preferred. Furthermore, plant-derived carbon compounds are expected to exhibit a layered structure characteristic of plant-derived materials, and since they absorb carbon dioxide from the atmosphere during plant cultivation, they are also preferred from a decarbonization perspective. Additionally, carbon derived from petroleum asphalt and coal tar pitch has the advantage of being readily available in large quantities at low cost.

[0096] Examples of gases used for gas activation include carbon dioxide, water vapor, and air.

[0097] By using carbon dioxide as a gas, the activation effect is mild and the degree of activation is easy to control.

[0098] When using carbon dioxide, the concentration of carbon dioxide in the gas is, for example, 50 to 100% by volume.

[0099] Furthermore, water vapor and air are gases that are more readily available at lower costs, allowing for further cost reduction. Multiple gases can also be combined as gases for gas activation.

[0100] In one embodiment, the gas activation of activated carbon is carried out at a pressure of more than 2 atmospheres absolute pressure.

[0101] In one embodiment, the gas activation of activated carbon is carried out under an absolute pressure of 2 to 100 atmospheres, 3 to 10 atmospheres, or 5 to 9 atmospheres.

[0102] If the absolute pressure is above 2 atmospheres, gas activation proceeds uniformly into the micro-domains inside the carbon particles, resulting in activated carbon with a high specific surface area. If the absolute pressure is below 100 atmospheres, an electric furnace capable of simultaneous pressurization and heating can be preferred, especially if the absolute pressure is below 10 atmospheres (or less than 10 atmospheres), which can keep equipment costs relatively low.

[0103] In one embodiment, the activation treatment time is more than 0 minutes and less than 99 hours, more than 1 minute and less than 24 hours, or more than 5 minutes and less than 8 hours.

[0104] The activation temperature can be appropriately set according to the type of gas, pressure, etc., preferably above 600°C, and more preferably above 700°C. Furthermore, it is preferably below 1200°C, and more preferably below 1100°C. If the temperature is above 600°C, activation is carried out appropriately; if the temperature is below 1200°C, energy consumption is relatively low, and the furnace can be manufactured with relatively inexpensive raw materials, thus resulting in high economic efficiency.

[0105] By subjecting activated carbon to gas activation under pressure, activated carbon with a specific surface area of ​​1400 m² can be obtained. 2 Activated carbon of / g or more that meets one or both of conditions (A) and (B).

[0106] The activated carbon is combined with at least one of elemental sulfur and the discharge products of elemental sulfur.

[0107] Here, "composite" refers to attaching at least one of elemental sulfur and its discharge products to the surface of activated carbon (both the inner and outer surfaces of the pores). This can be achieved by coating the surface of activated carbon with at least one of elemental sulfur and its discharge products.

[0108] There are no particular limitations on the method of compounding. For example, one could cite a method of mixing activated carbon with at least one of elemental sulfur and the discharge products of elemental sulfur and then heating it.

[0109] The heating temperature is not particularly limited, but can be, for example, 130–445°C, 140–400°C, or 150–350°C. If the heating temperature is above 130°C, since it exceeds the melting point of elemental sulfur (115°C), the sulfur melts, and impregnation into the activated carbon can be expected. The upper limit of the heating temperature is preferably below or below the boiling point of elemental sulfur (445°C). In addition, lithium polysulfides and lithium sulfides, which are discharge products of elemental sulfur, have high melting points, so the temperature can be set to a higher temperature, exceeding 445°C.

[0110] There is no particular limitation on the heating time, for example, it can be 0.1 to 99 hours, 1 to 24 hours, or 2 to 8 hours.

[0111] The method for manufacturing the composite of another aspect of the present invention (also referred to as "the second aspect") includes: combining activated carbon that has been gas-activated under pressure with at least one of elemental sulfur and the discharge products of elemental sulfur.

[0112] Another aspect of the present invention (also referred to as "the third aspect") includes a method for manufacturing a composite with a specific surface area of ​​1400 m². 2 Activated carbon of 6g or more that meets one or both of conditions (A) and (B) is compounded with elemental sulfur and at least one of the discharge products of elemental sulfur.

[0113] 2. Uses and manufacturing methods of activated carbon

[0114] One aspect of the activated carbon of the present invention is its use in compounding with at least one of elemental sulfur and discharge products of elemental sulfur. Here, the activated carbon has a specific surface area of ​​1400 m². 2Activated carbon of / g or more that meets one or both of conditions (A) and (B), or activated carbon that has undergone gas activation under pressure.

[0115] One aspect of the present invention is a method for manufacturing activated carbon for use in compounding with at least one of elemental sulfur and discharge products of elemental sulfur, comprising gas activation of activated carbon under pressure.

[0116] Regarding the uses of these activated carbons and the methods for manufacturing activated carbons, the description of "1. Composites and methods for manufacturing composites" can be appropriately cited.

[0117] 3. Positive electrode composite material

[0118] One aspect of the positive electrode composite material of the present invention comprises a composite of the present invention and a sulfide solid electrolyte. This results in excellent rate performance for lithium-ion batteries while minimizing environmental impact during manufacturing.

[0119] Another embodiment of the present invention comprises a positive electrode composite material containing a composite and a sulfide solid electrolyte.

[0120] The composite contains a specific surface area of ​​1400 m². 2 The activated carbon of 1 g or more, and at least one of elemental sulfur and its discharge products,

[0121] The positive electrode composite material satisfies one or both of the following conditions (A') and (B').

[0122] (A') The peak width of the D band in the Raman spectrum of the cathode composite material is 100 cm⁻¹. -1 the following.

[0123] (B') The peak width of the G band in the Raman spectrum of the positive electrode composite material is 90 cm⁻¹. -1 the following.

[0124] This results in lithium-ion batteries having excellent rate performance while minimizing environmental impact during manufacturing.

[0125] The Raman spectrum of the cathode composite material is the Raman spectrum measured from the cathode composite material. The D and G bands in the Raman spectrum of the cathode composite material can also be referred to as the D and G bands originating from the activated carbon contained in the cathode composite material, and have the same technical significance.

[0126] In one embodiment, the peak width of the D band in the Raman spectrum of the cathode composite material is 10–100 cm⁻¹. -1 10-99cm -1 20-95cm -1Or 55-90cm -1 .

[0127] If the peak width of the D band is 100cm -1 The activated carbon contained in the cathode composite material has fewer types of defects and fewer sites for capturing lithium ions. Therefore, when this cathode composite material is used in a battery, it is expected that the resistance during lithium ion conduction will be reduced.

[0128] The peak width of the D band in the Raman spectrum of the cathode composite material is a value measured by the method described in the examples.

[0129] In one embodiment, the peak width of the G band in the Raman spectrum of the cathode composite material is 10–90 cm⁻¹. -1 20-80cm -1 Or 30-70cm -1 .

[0130] If the peak width of the G band is 90cm -1 Therefore, it can be assumed that the graphite structure of the activated carbon contained in the cathode composite material is homogeneously formed, and high conductivity and lithium conduction between graphite layers can be expected.

[0131] The peak width of the G band in the Raman spectrum of the cathode composite material is a value measured by the method described in the examples.

[0132] In one embodiment, the cathode composite material satisfies conditions (A') and (B'). Consequently, the activated carbon contained in the cathode composite material has fewer lithium-capturing sites and higher conductivity and lithium conductivity, thus exhibiting superior performance as a conductive aid within the battery, crucial for ion and electron conduction. As a result, the lithium-ion battery is endowed with superior rate performance.

[0133] The following provides a more detailed description of one and other cathode composite materials of the present invention.

[0134] (Sulfide solid electrolyte)

[0135] A sulfide solid electrolyte is a solid electrolyte that contains at least sulfur atoms and exhibits ionic conductivity caused by the contained metal atoms; it is a solid electrolyte that, in addition to sulfur atoms, preferably contains lithium atoms and phosphorus atoms, more preferably contains lithium atoms, phosphorus atoms and halogen atoms, and has ionic conductivity caused by lithium atoms.

[0136] In one embodiment, the solid electrolyte comprises at least lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms.

[0137] In one embodiment, the solid electrolyte comprises lithium atoms, phosphorus atoms, sulfur atoms, bromine atoms, and iodine atoms.

[0138] As a sulfide solid electrolyte, it can be either an amorphous sulfide solid electrolyte or a crystalline sulfide solid electrolyte.

[0139] (Amorphous sulfide solid electrolyte)

[0140] As an amorphous sulfide solid electrolyte, any electrolyte that contains at least sulfur atoms and exhibits ionic conductivity caused by the contained metal atoms can be used without particular restrictions. Representative amorphous sulfide solid electrolytes include, for example, solid electrolytes containing sulfur atoms, lithium atoms, and phosphorus atoms such as Li2S-P2S5 composed of lithium sulfide and phosphorus sulfide; solid electrolytes composed of lithium sulfide, phosphorus sulfide, and lithium halide such as Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, and Li2S-P2S5-LiI-LiBr; and solid electrolytes that also contain other elements such as oxygen and silicon, such as Li2S-P2S5-Li2O-LiI and Li2S-SiS2-P2S5-LiI. From the viewpoint of obtaining higher ionic conductivity, solid electrolytes composed of lithium sulfide, phosphorus sulfide and lithium halide, such as Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr and Li2S-P2S5-LiI-LiBr, are preferred.

[0141] The types of elements constituting amorphous sulfide solid electrolytes can be identified, for example, by using an ICP-based luminescence spectrophotometer.

[0142] When the amorphous sulfide solid electrolyte has at least Li2S-P2S5, from the viewpoint of high chemical stability and higher ionic conductivity, the molar ratio of Li2S to P2S5 is preferably 30-85:15-70, more preferably 40-80:20-60, and even more preferably 45-78:22-55.

[0143] In the case of an amorphous sulfide solid electrolyte, such as Li₂S-P₂S₅-LiI-LiBr, the total content of lithium sulfide and phosphorus pentasulfide is preferably 30-95 mol%, more preferably 35-90 mol%, and even more preferably 40-85 mol%. Furthermore, the ratio of lithium bromide to the total content of lithium bromide and lithium iodide is preferably 1-99 mol%, more preferably 20-90 mol%, even more preferably 40-80 mol%, and particularly preferably 50-70 mol%.

[0144] Furthermore, there are no particular limitations on the shape of the amorphous sulfide solid electrolyte; for example, particulate form can be cited. The average particle size (D) of the particulate amorphous sulfide solid electrolyte... 50For example, it can exemplify the range of 0.01μm to 500μm and 0.1 to 200μm.

[0145] In this specification, the average particle size (D) 50 The particle size distribution is the particle size that accumulates sequentially from the smallest particle to reach 50% of the total when plotting the cumulative particle size distribution curve. The volume distribution is, for example, the average particle size that can be measured using a laser diffraction / scattering particle size distribution measurement device.

[0146] (Crystall sulfide solid electrolyte)

[0147] As a crystalline sulfide solid electrolyte, for example, it can be a so-called glass ceramic obtained by heating the above-mentioned amorphous sulfide solid electrolyte to above the crystallization temperature, and a sulfide solid electrolyte having the following crystal structure can be used.

[0148] Crystal structures that can be possessed by crystalline sulfide solid electrolytes containing lithium, sulfur, and phosphorus atoms include Li3PS4, Li4P2S6, Li7PS6, and Li7P3S6. 11 Crystal structures, crystal structures with peaks around 2θ = 20.2° and around 23.6° (e.g., Japanese Patent Application Publication No. 2013-16423), etc.

[0149] Furthermore, as a crystalline sulfide solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, the aforementioned Li... 4-x Ge 1-x P x S4 type sulfide crystalline lithium superionic conductor thio-LISICON Region II crystal structure, and Li 4-x Ge 1-x P x S4 type sulfide crystalline lithium superionic conductors with similar crystal structures to the thio-LISICON Region II type.

[0150] In X-ray diffraction measurements using CuKα rays, the diffraction peaks of the Li3PS4 crystal structure appear, for example, near 2θ = 17.5°, 18.3°, 26.1°, 27.3°, and 30.0°; the diffraction peaks of the Li4P2S6 crystal structure appear, for example, near 2θ = 16.9°, 27.1°, and 32.5°; the diffraction peaks of the Li7PS6 crystal structure appear, for example, near 2θ = 15.3°, 25.2°, 29.6°, and 31.0°; and the diffraction peaks of the Li7P3S... 11Diffraction peaks of the crystal structure appear, for example, near 2θ = 17.8°, 18.5°, 19.7°, 21.8°, 23.7°, 25.9°, 29.6°, 30.0°, Li 4-x Ge 1-x P x Diffraction peaks of the crystal structure of the thio-LISICON Region II type of the lithium superionic conductor of the S4 class appear, for example, near 2θ = 20.1°, 23.9°, 29.5°, and are related to Li 4-x Ge 1-x P x Diffraction peaks of a crystal structure similar to the thio-LISICON Region II type of the lithium superionic conductor of the S4 class appear, for example, near 2θ = 20.2°, 23.6°. Additionally, these peak positions can fluctuate within a range of ±0.5°.

[0151] Furthermore, as the crystal structure of the crystalline sulfide solid electrolyte, a thiogermanate-type crystal structure can also be cited. As the thiogermanate-type crystal structure, for example, a Li7PS6 crystal structure can be cited; crystal structures represented by the composition formula Li 7-x P 1-y Si y S6 and Li 7+x P 1-y Si y S6 (where x is -0.6 to 0.6 and y is 0.1 to 0.6); crystal structures represented by Li 7-x-2y PS 6-x-y Cl x (0.8 ≤ x ≤ 1.7, 0 < y ≤ -0.25x + 0.5); crystal structures represented by Li 7-x PS 6-x Ha x (where Ha is Cl or Br, and x is preferably 0.2 to 1.8).

[0152] Among the above crystal structures, as the crystal structure of the crystalline sulfide solid electrolyte, a Li3PS4 crystal structure, a thio-LISICON Region II type crystal structure, and a thiogermanate-type crystal structure are preferred.

[0153] The shape of the crystalline sulfide solid electrolyte is not particularly limited, and for example, a particulate shape can be cited. The average particle diameter (D 50 ) of the particulate crystalline sulfide solid electrolyte is, similar to the average particle diameter (D 50 ) of the aforementioned amorphous sulfide solid electrolyte, for example, within the range of 0.01 μm to 500 μm, 0.1 to 200 μm.

[0154] In one embodiment, the cathode composite material comprises at least 40% by mass of elemental sulfur and its discharge products. Here, the elemental sulfur and its discharge products are derived from the composite material.

[0155] In one embodiment, the cathode composite material comprises 40–90% by mass, 40–70% by mass, or 40–60% by mass of elemental sulfur and its discharge products, converted from sulfur. Here, the elemental sulfur and its discharge products originate from the aforementioned composite.

[0156] 3. Positive electrode for lithium-ion batteries and lithium-ion batteries

[0157] The positive electrode for a lithium-ion battery according to one aspect of the present invention comprises one or more selected from the group consisting of the positive electrode composite material of one aspect of the present invention and the positive electrode composite material of other aspects of the present invention.

[0158] The positive electrode for lithium-ion batteries according to this scheme can impart excellent rate performance to lithium-ion batteries while minimizing environmental impact during manufacturing.

[0159] One aspect of the present invention is a lithium-ion battery comprising a positive electrode for a lithium-ion battery according to one aspect of the present invention.

[0160] The lithium-ion battery based on this solution can achieve excellent rate performance and a low environmental impact during manufacturing.

[0161] The positive electrode composite material can be used as the positive electrode layer of a lithium-ion battery. In this case, other components of the lithium-ion battery can use those known in the art, and a negative electrode layer in which lithium ions are not contained can be selected.

[0162] Furthermore, the negative electrode active material contained in the negative electrode layer of a lithium-ion battery can be defined as "a negative electrode active material containing lithium ions". Additionally, the negative electrode active material contained in the negative electrode layer of a lithium-ion battery can also be "a negative electrode active material that supplies lithium ions to the positive electrode".

[0163] There are no particular restrictions on the negative electrode of a lithium-ion battery, as long as it can be used in a conventional battery. The negative electrode can also be made of a composite material obtained by mixing the negative electrode active material with a solid electrolyte.

[0164] Commercially available materials can be used as the negative electrode active material. For example, carbon materials, Sn metal, In metal, Si metal, Li metal, and alloys of these metals can be used. Specifically, examples include natural graphite or various types of graphite, lithium titanate, metal powders such as Si, Sn, Al, Sb, Zn, and Bi, metal alloys such as SiAl, Sn5Cu6, Sn2Co, and Sn2Fe, and other amorphous alloys or coated alloys. There are no particular restrictions on particle size; materials with an average particle size of several μm to 80 μm can be appropriately used.

[0165] There are no particular limitations on the electrolyte layer, and known electrolyte layers can be used. For example, oxide solid electrolytes, sulfide solid electrolytes, and polymer electrolytes are preferred, and from the viewpoint of ionic conductivity, sulfide solid electrolytes are more preferred. This sulfide solid electrolyte is preferably an electrolyte used in the above-mentioned positive electrode composite material.

[0166] There are no particular limitations on the manufacturing method of lithium-ion batteries. For example, the following methods can be used: forming a sheet by forming a positive electrode layer on a positive current collector, forming a solid electrolyte layer on the sheet, stacking a sheet with a negative electrode layer formed on a negative current collector beforehand, and applying pressure, wherein the positive electrode layer is composed of one or more selected from the group consisting of a positive electrode composite material of one embodiment of the present invention and positive electrode composite materials of other embodiments of the present invention.

[0167] Example

[0168] The following describes embodiments of the present invention, but the present invention is not limited to these embodiments.

[0169] (Example 1)

[0170] (1) Production of activated carbon

[0171] Spherical phenolic resin (manufactured by Asahi Organics Co., Ltd., particle size 17 μm) was carbonized in a tubular electric furnace at a temperature of 600°C (200 mL / min) at a rate of 5°C / min under a flowing nitrogen atmosphere, and then held for 1 hour to obtain carbon derived from phenolic resin (activated carbon before activation).

[0172] The carbon derived from phenolic resin was pressurized to 1.0 MPa (10 atmospheres) in a tubular electric furnace at a carbon dioxide flow rate of 100-200 mL / min, heated to 1000℃ at a rate of 5℃ / min, and activated for 1 hour to obtain activated carbon-1.

[0173] (2) Fabrication of the composite

[0174] Activated carbon-1 and elemental sulfur (S) were added (mixed) in a glass bottle at a weight ratio of 1:5 and sealed into a SUS tube container. The mixture was heated in an electric furnace at 150°C for 6 hours and then at 300°C for 2.75 hours to obtain a composite of activated carbon and elemental sulfur (powder).

[0175] (3) Preparation of solid electrolytes

[0176] 0.4127 g of lithium sulfide, 0.6655 g of phosphorus pentasulfide, 0.2137 g of lithium iodide, 0.2080 g of lithium bromide, and 10 zirconia balls with a diameter of 10 mm were added to a 45 mL zirconia container and sealed. The mixture was mechanically ground using a planetary ball mill (FRITSCH, model P-7) at 370 rpm for 40 hours to obtain a powder. The powder was then heated at 195°C for 3 hours to obtain a solid electrolyte.

[0177] (4) Fabrication of positive electrode composite materials

[0178] 0.2 g of the composite obtained through the above steps and 0.2 g of the solid electrolyte obtained through the above steps were added together with 10 zirconia balls with a diameter of 10 mm into a 45 mL zirconia container and sealed. The mixture was then pulverized using a planetary ball mill (FRITSCH, model P-7) at 370 rpm at room temperature for 20 hours to obtain the cathode composite material (powder).

[0179] (5) Fabrication of lithium-ion batteries (all solid-state)

[0180] The 100 mg of solid electrolyte prepared above was placed into a MACOR (glass-ceramic) cylinder with a diameter of 10 mm and pressurized. The positive electrode composite material prepared above, with a sulfur content of 1.75 mg, was added to the pressurized surface and pressurized again. By placing indium foil and lithium foil on the pressurized surface opposite to that of the positive electrode composite material and pressing them, an all-solid-state battery was fabricated.

[0181] (Example 2)

[0182] Except that activated carbon-2 obtained by the following steps is used instead of activated carbon-1, the composite, solid electrolyte, positive electrode composite material and lithium-ion battery are prepared in the same manner as (2) to (5) of Example 1.

[0183] <Preparation of Activated Carbon-2>

[0184] Spherical phenolic resin (manufactured by Asahi Organics Co., Ltd., particle size 17 μm) was carbonized in a tubular electric furnace at a temperature of 600°C (200 mL / min) at a rate of 5°C / min under a flowing nitrogen atmosphere, and then held for 1 hour to obtain carbon derived from phenolic resin (activated carbon before activation).

[0185] The carbon derived from phenolic resin was pressurized to 1.0 MPa in a tubular electric furnace at a carbon dioxide flow rate of 100-200 mL / min, heated to 1000 °C at a rate of 5 °C / min, and activated for 0.5 hours to obtain activated carbon-2.

[0186] (Example 3)

[0187] Except that activated carbon-3 obtained by the following steps is used instead of activated carbon-1, the composite, solid electrolyte, positive electrode composite material and lithium-ion battery are prepared in the same manner as (2) to (5) of Example 1.

[0188] <Preparation of Activated Carbon-3>

[0189] Spherical phenolic resin (manufactured by Asahi Organics Co., Ltd., particle size 8 μm) was carbonized in a tubular electric furnace at a temperature of 600°C (200 mL / min) and 5°C / min, and held for 1 hour to obtain carbon derived from phenolic resin (activated carbon before activation).

[0190] The carbon derived from phenolic resin was pressurized to 0.5 MPa (5 atmospheres) using a tubular electric furnace, heated to 850°C at a rate of 5°C / min, and activated for 45 minutes to obtain activated carbon.

[0191] (Comparative Example 1)

[0192] Except that activated carbon-3 obtained by the following steps is used instead of activated carbon-1, the composite, solid electrolyte, positive electrode composite material and lithium-ion battery are prepared in the same manner as (2) to (5) of Example 1.

[0193] <Preparation of Activated Carbon-3>

[0194] Spherical phenolic resin (spherical phenolic resin BEAPS, manufactured by Asahi Organics Co., Ltd., particle size 8 μm) was carbonized in a tubular electric furnace at a temperature of 5 °C / min and a flowing nitrogen atmosphere (200 mL / min) to 600 °C, and then held for 1 hour to obtain carbon derived from phenolic resin (activated carbon before activation).

[0195] The carbon derived from phenolic resin and six times the amount of potassium hydroxide were placed in a Ni crucible and then placed in a stainless steel container. The mixture was activated by heating the crucible to 700°C at 5°C / min under a flowing nitrogen atmosphere (100 mL / min) and holding it for 1 hour. After neutralization with hydrochloric acid, the mixture was washed with water until the pH reached 7 and then dried to obtain activated carbon-3.

[0196] (Comparative Example 2)

[0197] Except for using Ketjen Black (manufactured by Lion Specialty Chemicals Co., Ltd., "KB600JD") instead of activated carbon-1, the composite, solid electrolyte, positive electrode composite material and lithium-ion battery were prepared in the same manner as in Examples 1 (2) to (5).

[0198] [Measurement and Evaluation Methods]

[0199] (1) Measurement of specific surface area, pore volume and average pore width

[0200] For the specific surface area, pore capacity (micropore capacity), and average pore width of the activated carbon (activated carbon, Ketjen Black in Comparative Example 2, hereinafter the same) used in the preparation of the composite, refer to Carbon 1997 No. 197 159-166, and use the Quantacrome Autosorb-3 micropore distribution measuring device or the Anton Paar Nova device to measure the nitrogen adsorption isotherm, using α s The method is used for analysis.

[0201] In addition, to unify the analysis results, α s The analysis of external particles and mesoporous structures in the method was performed in all samples at α s Implemented within the range of 1 to 2.

[0202] (2) Raman measurement

[0203] (2-1)

[0204] The Raman spectra of activated carbon (individual) used in the fabrication of the composite were measured. Measurement conditions are as follows. Additionally, different particles were randomly selected for measurements at N=5, and their average spectra were used as the Raman spectra (raw data) for peak width calculation.

[0205] <Measurement Conditions>

[0206] Device: DXR2 (Thermo Fisher Scientific Co., Ltd.)

[0207] Exposure time: 10 seconds

[0208] Total number of times: 20

[0209] Background: 20 times

[0210] Laser wavelength: 532nm

[0211] Laser power: 2.0mW

[0212] Pinhole: 25μm pinhole

[0213] Resolution: HIGH RES GRATING

[0214] Measurement range: 50~1800cm -1

[0215] Measurement magnification: 50x objective lens

[0216] Regarding the peak width of the D band in the Raman spectrum, for 700–1475 cm⁻¹ -1 The Raman spectrum within the range is differentiated and its widths (maximum and minimum values) are defined. Furthermore, the peak width of the G band in the Raman spectrum is defined for the range of 1475–1800 cm⁻¹. -1 Differentiate the Raman spectrum within the range and set the width of the maximum and minimum values ​​within that range.

[0217] The following description uses the Raman spectrum of Example 1 as an example and refers to the accompanying drawings. Figure 1 This is the Raman spectrum (raw data) of Example 1. Figure 2 This is a diagram illustrating an example of how to determine the peak widths of the D and G bands in a Raman spectrum. Figure 2 In the graph, solid lines represent Raman spectra (raw data), dotted lines represent smoothed Raman spectra, and dashed lines represent differential curves. The scale on the right side of the graph corresponds to the differential curves. a represents the peak width of band D, and b represents the peak width of band G.

[0218] First, use 700 cm⁻¹ outside the peak range. -1 and 1800cm -1 value pairs Figure 1 (and Figure 2 The Raman spectrum (raw data) shown by the solid line in the figure is subjected to background processing (straight line method).

[0219] Next, as Figure 2 As shown, the Raman spectrum (raw data) is smoothed using a moving average to obtain the smoothed Raman spectrum.

[0220] Next, the smoothed Raman spectrum is differentiated to obtain the differential curve.

[0221] The 700–1475 cm value in the differential curve -1 The width 'a' of the maximum and minimum values ​​within the range is taken as the peak width of the D band. Furthermore, the 1475–1800 cm⁻¹ range of the differential curve is used as the peak width.-1 The width b of the range of maximum and minimum values ​​is set as the peak width of the G-band.

[0222] (2-2)

[0223] The Raman spectrum of the cathode composite material was measured. The measurement conditions are as follows. Furthermore, these conditions allow for measurement while suppressing the laser energy and the reaction with sulfur and solid electrolyte contained in the cathode composite material. Different particles were randomly selected and measured at N=10. Their average spectra were used as the Raman spectrum (raw data) for peak width calculation.

[0224] Furthermore, when measuring easily deteriorated materials, the laser output (laser power) can be adjusted within the range of 0.1 to 0.5 mW for measurement.

[0225] <Measurement Conditions>

[0226] Device: DXR2 (Thermo Fisher Scientific Co., Ltd.)

[0227] Exposure time: 5 seconds

[0228] Total number of times: 5

[0229] Background: 20 times

[0230] Laser wavelength: 532nm

[0231] Laser power: 0.5mW

[0232] Pinhole: 50μm pinhole

[0233] Resolution: HIGH RES GRATING

[0234] Measurement range: 50~1800cm -1

[0235] Measurement magnification: 100x objective lens

[0236] Similarly to “(2-1)” above, the peak widths of the D and G bands in the Raman spectrum of the cathode composite material are determined.

[0237] (2-3)

[0238] Furthermore, when the sensitivity of direct Raman analysis of the cathode composite material is insufficient, the activated carbon constituting the cathode composite material can be separated from it (removing solid electrolyte and sulfur), allowing Raman measurement to be performed using only the activated carbon. The measurement conditions in this case are the same as described in "(2-1)" above. When separating the activated carbon from the cathode composite material, the solid electrolyte is dissolved and removed (washing) using polar solvents such as water or ethanol, and then sulfur is removed by heating at a temperature below 600°C and at which sulfur vaporization occurs, thereby separating only the activated carbon.

[0239] (3) Evaluation of battery characteristics (rate characteristics)

[0240] Constant current charge-discharge tests were conducted on the all-solid-state batteries obtained in the examples and comparative examples. The cutoff potential for the constant current test was set to 0.8-2.2V vs. Li-In, and the current density in each cycle was set to the conditions shown in Table 1.

[0241] [Table 1]

[0242]

[0243] The discharge capacity per 1g of sulfur in the 2nd, 5th and 6th cycles was calculated.

[0244] The results are shown in Table 2.

[0245] [Table 2]

[0246]

[0247] As shown in Table 2, compared with Comparative Examples 1 and 2, Examples 1 and 2 maintained a higher discharge capacity and had excellent rate performance.

[0248] The embodiments and / or examples of the present invention have been described in detail above. However, those skilled in the art can readily make many modifications to these illustrated embodiments and / or examples without departing substantially from the new teachings and effects of the present invention. Therefore, these many modifications are included within the scope of the present invention.

[0249] This application cites all documents recorded in this specification and the contents of the application that form the basis of the priority claim under the Paris Convention.

Claims

1. A composite, characterized in that, Include: Specific surface area is 1400 m² 2 Activated carbon of / g or above that meets one or both of the following conditions (A) and (B), and At least one of elemental sulfur and its discharge products. (A) The peak width of band D in the Raman spectrum of the activated carbon is 100 cm⁻¹. -1 the following; (B) The peak width of the G band in the Raman spectrum of the activated carbon is 70 cm⁻¹. -1 the following.

2. The composite as described in claim 1, characterized in that, The activated carbon satisfies conditions (A) and (B).

3. The composite as described in claim 1 or 2, characterized in that, The activated carbon has a micropore capacity of 0.5 cc / g or higher.

4. The composite as described in any one of claims 1 to 3, characterized in that, The average pore width of the activated carbon is less than 1.55 nm.

5. The composite as described in any one of claims 1 to 4, characterized in that, The activated carbon contains, relative to 100 parts by mass, 150 to 600 parts by mass of elemental sulfur and the discharge products of elemental sulfur.

6. A positive electrode composite material, characterized in that, It comprises the composite and sulfide solid electrolyte as described in any one of claims 1 to 5.

7. A positive electrode composite material, characterized in that, It comprises a complex and a sulfide solid electrolyte, the complex comprising a specific surface area of ​​1400 m². 2 The activated carbon of 1 g or more, and at least one of elemental sulfur and its discharge products, The positive electrode composite material satisfies one or both of the following conditions (A') and (B'): (A') The peak width of the D band in the Raman spectrum of the cathode composite material is 100 cm⁻¹. -1 the following; (B') The peak width of the G band in the Raman spectrum of the positive electrode composite material is 90 cm⁻¹. -1 the following.

8. The positive electrode composite material as described in claim 7, characterized in that, The positive electrode composite material satisfies conditions (A') and (B').

9. The positive electrode composite material according to any one of claims 6 to 8, characterized in that, The sulfide solid electrolyte contains at least lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms.

10. The positive electrode composite material according to any one of claims 6 to 9, characterized in that, The discharge products of the elemental sulfur, which contain at least 40% by mass (calculated as sulfur), are included.

11. A positive electrode for a lithium-ion battery, characterized in that, The positive electrode composite material comprising any one of claims 6 to 10.

12. A lithium-ion battery, characterized in that, It includes the positive electrode for a lithium-ion battery as described in claim 11.

13. A method for manufacturing a composite, characterized in that, include: Gas activation of activated carbon under pressure; as well as The activated carbon is combined with at least one of elemental sulfur and the discharge products of elemental sulfur.

14. A method for manufacturing a composite, characterized in that, include: The activated carbon that has undergone gas activation under pressure is combined with at least one of elemental sulfur and the discharge products of elemental sulfur.

15. The method for manufacturing the composite as described in claim 13 or 14, characterized in that, The gas activation is carried out at a pressure of more than 2 atmospheres of absolute pressure.

16. A method for manufacturing a composite, characterized in that, include: With a specific surface area of ​​1400 m² 2 Activated carbon of / g or above that meets one or both of the following conditions (A) and (B) is compounded with at least one of elemental sulfur and the discharge products of elemental sulfur. (A) The peak width of band D in the Raman spectrum of the activated carbon is 100 cm⁻¹. -1 the following; (B) The peak width of the G band in the Raman spectrum of the activated carbon is 70 cm⁻¹. -1 the following.

17. A composite, characterized in that, Manufactured by the method of manufacturing the composite according to any one of claims 13 to 16.

18. A use of activated carbon, characterized in that, Used for a specific surface area of ​​1400 m² 2 The use of activated carbon of 6 g or more that meets one or both of the following conditions (A) and (B) and is compounded with at least one of elemental sulfur and the discharge products of elemental sulfur. (A) The peak width of band D in the Raman spectrum of the activated carbon is 100 cm⁻¹. -1 the following; (B) The peak width of the G band in the Raman spectrum of the activated carbon is 70 cm⁻¹. -1 the following.

19. An application of activated carbon, characterized in that, Used for combining activated carbon that has been gas-activated under pressure with at least one of elemental sulfur and the discharge products of elemental sulfur.

20. A method for manufacturing activated carbon, wherein the activated carbon is used for compounding with at least one of elemental sulfur and discharge products of elemental sulfur, characterized in that, This includes gas activation of activated carbon under pressure.

21. The method for manufacturing activated carbon as described in claim 20, characterized in that, The gas activation is carried out at a pressure of more than 2 atmospheres of absolute pressure.

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