Electrode active material and manufacturing method therefor, electrode mixture, and battery

Abstract

To provide an electrode active material comprising hard carbon and capable of improving capacity at low potential and a manufacturing method therefor, an electrode mixture comprising such an electrode active material, and a battery comprising such an electrode mixture.SOLUTION: Hard carbon comprised in an electrode active material of the present disclosure has a G'-band, a G-band, and a D-band in a Raman spectrum. The ratio IG' / IG of intensity IG' of the G'-band to intensity IG of the G-band is 0.05 or more. The half-width HwD of the D-band is 50 or more and 160 or less. A method for manufacturing the electrode active material of the present disclosure comprises the following steps: providing a raw material comprising carbon; and firing to carbonize the raw material under an inert atmosphere comprising more than 0% and less than 1.0% of air.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an electrode active material, a method for manufacturing the same, an electrode binder, and a battery.

Background Art

[0002] As disclosed in Patent Documents 1 and 2, batteries containing hard carbon as a negative electrode active material have been developed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a battery containing hard carbon as an electrode active material, there is room for improvement in the capacity at a low potential.

[0005] The present disclosure aims to provide an electrode active material containing hard carbon and capable of improving the capacity at a low potential, a method for manufacturing the same, an electrode binder containing such an electrode active material, and a battery containing such an electrode binder.

Means for Solving the Problems

[0006] The present inventors have found that the above problems can be solved by the following means. <Aspect 1> An electrode active material containing hard carbon, wherein the hard carbon has a G' band, a G band, and a D band in a Raman spectrum, the intensity I of the G' band G’ of the intensity I of the G bandG Ratio I with respect to G’ / I G is 0.05 or more and the half-value width Hw of the D band D is 50 or more and 160 or less, Electrode active material. <Aspect 2> The half-value width Hw of the D band D is 90 or more and 130 or less, the electrode active material according to Aspect 1. <Aspect 3> The intensity I of the D band D of the intensity I of the G band G Ratio I with respect to D / I G is 1.0 or more and 1.6 or less, the electrode active material according to Aspect 1 or 2. <Aspect 4> The intensity I of the D band D of the intensity I of the G band G Ratio I with respect to D / I G is 1.2 or more and 1.4 or less, the electrode active material according to Aspect 3. <Aspect 5> An electrode composite material containing the electrode active material according to any one of Aspects 1 to 4. <Aspect 6> Having a negative electrode current collector layer, a negative electrode active material layer, an electrolyte layer, a positive electrode active material layer, and a positive electrode current collector layer in this order, and either one of the negative electrode active material layer and the positive electrode active material layer contains the electrode composite material according to Aspect 5, Battery. <Aspect 7> The battery according to Aspect 6, wherein the negative electrode active material layer contains the electrode composite material according to Aspect 5. <Aspect 8> The battery according to Aspect 6 or 7, wherein the electrolyte layer is a sodium ion battery having sodium ions. <Aspect 9> The battery according to Aspect 8, wherein the electrolyte layer is a liquid-based battery containing an electrolyte having sodium ions. <Aspect 10> The battery according to aspect 8, which is a solid battery in which the electrolyte layer contains a solid electrolyte having sodium ions. <Aspect 11> The method for producing an electrode active material according to any one of aspects 1 to 4, including the following steps: Providing a raw material containing carbon, and Baking and carbonizing the raw material in an inert atmosphere containing more than 0% and less than 1.0% of air.

Advantages of the Invention

[0007] According to the present disclosure, it is possible to provide an electrode active material containing hard carbon and capable of improving the capacity at a low potential, a method for producing the same, an electrode composite material containing such an electrode active material, and a battery containing such an electrode composite material.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure will be described in detail. Note that the present disclosure is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the disclosure.

[0010] 《Electrode Active Material》 The electrode active material of the present disclosure contains hard carbon, and the hard carbon has a G' band, a G band, and a D band in the Raman spectrum. The intensity I of the G' band G’ of the G band intensity IG Ratio I with respect to G’ / I G is 0.05 or more. The half-value width Hw of the D band D is 50 or more and 160 or less.

[0011] Conventionally, in order to specify the structure of hard carbon, measurement by Raman spectroscopy has been performed. In this regard, the present inventors have unexpectedly found that an electrode active material containing hard carbon having a G’ band of a predetermined size (referred to as “2D band” in Patent Document 2) in the Raman spectrum and having an appropriate half-value width of the D band can improve the capacity of the battery at a low potential.

[0012] Hard carbon does not have a structure in which graphene is regularly stacked like graphite, but has a structure in which graphene is irregularly aggregated. On the other hand, the G’ band is due to the stacked structure of graphene. That is, the fact that the electrode active material of the present disclosure has a G’ band suggests that the electrode active material of the present disclosure has a minute stacked structure of graphene (nanographite structure).

[0013] The half-value width of the D band is due to the defects in the structure of crystallites. For example, a small half-value width of the D band in the electrode active material suggests that there are few defects in the structure of crystallites.

[0014] That is, it is presumed that an electrode active material having a nanographite structure and having appropriate defects in the structure of crystallites can improve the capacity of the battery at a low potential.

[0015] Regarding the present disclosure, the “electrode active material” can be used as both the “positive electrode active material” and the “negative electrode active material”, and is particularly used as the “negative electrode active material”.

[0016] The electrode active material of the present disclosure contains hard carbon. The content of hard carbon with respect to the total amount of the electrode active material may be 50% by mass or more, 70% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more, and may be 100% by mass. That is, the electrode active material may be hard carbon. The average particle size of the hard carbon is not particularly limited, but can be, for example, in the range of 50 nm to 100 μm.

[0017] Hard carbon has a G' band, a G band, and a D band in the Raman spectrum.

[0018] Regarding the present disclosure, in the Raman spectrum of the electrode active material, -1 , 1600 cm -1 , and 1350 cm -1 The peaks confirmed in the vicinity can be respectively determined to be the G' band, the G band, and the D band.

[0019] The ratio I G’ of the intensity of the G' band to the intensity I G of the G band is 0.05 or more. This ratio I G’ / I G is 0.05 or more. This ratio I G’ / I G may be 0.05 or more, 0.1 or more, 0.2 or more, or 0.3 or more, and may be 1.0 or less, 0.8 or less, 0.5 or less, or 0.4 or less. In particular, this ratio I G’ / I G may be 0.3 or more and 0.4 or less.

[0020] Note that since the G' band is due to the number of graphene layers, that is, the stacked structure, and the G band is due to the planar structure derived from the sp 2 orbital, I G’ / I G means the ratio of the stacked structure of the electrode active material to the planar structure.

[0021] The full width at half maximum Hw D of the D band is 50 or more and 160 or less. The full width at half maximum HwD may be 60 or more, 70 or more, 80 or more, or 90 or more, and may be 150 or less, 140 or less, or 130 or less. In particular, the full width at half maximum Hw D may be 90 or more and 130 or less.

[0022] The intensity I of the D band D of the intensity I of the G band G The ratio I D / I G may be 1.0 or more and 1.6 or less. This ratio I D / I G may be 1.1 or more, or 1.2 or more, and may be 1.5 or less, or 1.4 or less. In particular, this ratio I D / I G may be 1.2 or more and 1.4 or less.

[0023] Note that since the D band is caused by a structure derived from the sp 3 orbital and the G band is caused by a structure derived from the sp 2 orbital, I D / I G represents the ratio of the structure derived from the sp 3 orbital of the electrode active material to the structure derived from the sp 2 orbital. A small I D / I G means that there is a large amount of the structure derived from the sp 2 orbital, that is, the graphite structure, and a large I D / I G means that there is a small amount of the graphite structure.

[0024] The Raman spectrum of the electrode active material of the present disclosure can be obtained by Raman spectroscopy (wavelength 532 nm). The baseline of the Raman spectrum can be set, for example, by performing baseline analysis using Spectrum Manager of JASCO Corporation.

[0025] The electrode active material of the present disclosure may be, for example, a commercially available hard carbon fired in an inert atmosphere, or particularly may be one produced by the method for producing an electrode active material described below.

[0026] 《Method for Producing Electrode Active Material》 The method of the present disclosure for producing an electrode active material includes the following steps: providing a raw material containing carbon, and firing and carbonizing the raw material in an inert atmosphere containing more than 0% and less than 1.0% of air.

[0027] Conventionally, a method of carbonizing a raw material containing carbon by firing it in an inert atmosphere has been generally adopted. In this regard, the present inventors unexpectedly found that the electrode active material of the present disclosure can be obtained by firing and carbonizing a raw material containing carbon in an inert atmosphere containing a trace amount of air. Although not limited to theory, this is considered to be due to the fact that oxygen contained in the air preferentially oxidizes and removes parts other than nanographite, increasing the proportion of the nanographite part in the obtained carbon material.

[0028] The method of the present disclosure includes providing a raw material containing carbon.

[0029] The raw material containing carbon is not particularly limited as long as it can produce hard carbon. For example, the raw material containing carbon may be an organic compound such as alcohol such as ethanol, phenols, and aldehydes such as formaldehyde, a phenol resin, a resin such as polyacrylonitrile and polyimide, and a woody material such as coconut shell. These raw materials may be used alone or in combination of multiple types.

[0030] The method of the present disclosure includes firing and carbonizing a raw material containing carbon in an inert atmosphere containing more than 0% and less than 1.0% of air. In the method of the present disclosure, the proportion of air contained in the inert atmosphere may be 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, or 0.5% or more, and may be 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, or 0.5% or less.

[0031] The firing temperature is not particularly limited. The firing temperature may be, for example, 1000 °C or higher, 1100 °C or higher, 1200 °C or higher, 1300 °C or higher, 1400 °C or higher, or 1500 °C or higher, and may be 2000 °C or lower, 1900 °C or lower, 1800 °C or lower, 1700 °C or lower, 1600 °C or lower, or 1500 °C or lower.

[0032] The firing time may be 0.1 hour or longer, 0.5 hour or longer, 1 hour or longer, or 2 hours or longer, and may be 5 hours or shorter, 4 hours or shorter, 3 hours or shorter, or 2 hours or shorter.

[0033] 《Electrode composite material》 The electrode composite material of the present disclosure contains the electrode active material of the present disclosure. The electrode composite material of the present disclosure may optionally contain a conductive assistant and a binder. When the battery containing the electrode composite material of the present disclosure is a solid battery, the electrode composite material of the present disclosure may optionally contain a solid electrolyte.

[0034] Regarding the present disclosure, "electrode composite material" means a composition that can form an electrode active material layer as it is or by further containing other components. Also, regarding the present disclosure, "electrode composite material slurry" means a slurry that contains a dispersion medium in addition to the "electrode composite material" and can form an electrode active material layer by coating and drying.

[0035] 〈Electrode active material〉 Regarding the electrode active material, reference can be made to the above description regarding the electrode active material of the present disclosure. The electrode composite material of the present disclosure may contain the electrode active material in an amount of 50% by mass or more or 70% by mass or more, and 99% by mass or less or 95% by mass or less.

[0036] 〈Conductive assistant〉 The conductive aid may be, for example, a carbon material, a metal material, or the like. Specific examples of the carbon material include carbon blacks such as acetylene black, ketjen black, furnace black, thermal black; carbon fibers such as VGCF; graphite; hard carbon; coke and the like. Examples of the metal material include Fe, Cu, Ni, Al, etc. The content of the conductive aid in the negative electrode composite material is not particularly limited and may be appropriately determined according to the intended conductivity.

[0037] 〈Binder〉 As the binder, a chemically and electrically stable one may be used. Specific examples of the binder include, for example, fluorine-based binders such as polyvinylidene fluoride (PVdF)-based binders, polytetrafluoroethylene (PTFE)-based binders, rubber-based binders such as styrene-butadiene rubber (SBR)-based binders, olefin-based binders such as polypropylene (PP)-based binders, polyethylene (PE)-based binders, cellulose-based binders such as carboxymethyl cellulose (CMC)-based binders, or polyacrylic acid (PAA)-based binders. The content of the binder in the electrode composite material is not particularly limited and may be appropriately determined according to the intended binding property.

[0038] 〈Solid Electrolyte〉 The solid electrolyte may be an inorganic solid electrolyte. Examples of the inorganic solid electrolyte include, for example, oxide solid electrolytes, sulfide solid electrolytes. Examples of the oxide solid electrolyte include, for example, NASION-based compounds such as Na3Zr2Si2PO 12 etc., β-alumina (Na2O-11Al2O3). Examples of the sulfide solid electrolyte include, for example, Na2S-P2S5. The shape of the solid electrolyte may be, for example, particulate.

[0039] 《Battery》 As illustrated in FIG. 1, the battery 100 of the present disclosure has a negative electrode current collector layer 110, a negative electrode active material layer 120, an electrolyte layer 130, a positive electrode active material layer 140, and a positive electrode current collector layer 150 in this order, and either the negative electrode active material layer or the positive electrode active material layer contains the electrode composite material of the present disclosure.

[0040] The battery of the present disclosure may be a primary battery, or may be a secondary battery such as a lithium ion battery and a sodium ion battery. In particular, the battery of the present disclosure may be a sodium ion battery. The electrolyte layer of the sodium ion battery may have sodium ions.

[0041] The battery of the present disclosure may be a liquid battery or a solid battery. Regarding the present disclosure, "solid battery" means a battery that uses at least a solid electrolyte as an electrolyte. Therefore, the solid battery may use a combination of a solid electrolyte and a liquid electrolyte as the electrolyte. Further, the solid battery of the present disclosure may be an all-solid battery, that is, a battery that uses only a solid electrolyte as an electrolyte. The electrolyte layer of the liquid battery may contain an electrolyte solution having sodium ions. The electrolyte layer of the solid battery may contain a solid electrolyte having sodium ions.

[0042] Hereinafter, by way of example, the materials constituting the battery of the present disclosure will be described when the battery of the present disclosure is a sodium ion battery.

[0043] 〈Negative electrode current collector layer〉 Examples of the material of the negative electrode current collector layer include SUS, aluminum, copper, nickel, carbon, and the like.

[0044] The negative electrode current collector layer may be, for example, in the form of a foil, a mesh, or a porous material.

[0045] 〈Negative electrode active material layer〉 The negative electrode active material layer contains a negative electrode active material and, optionally, a negative electrode composite material containing a solid electrolyte, a conductive assistant, and a binder. In particular, the negative electrode composite material may be the electrode composite material of the present disclosure. That is, the negative electrode active material layer may contain the electrode composite material of the present disclosure. For the electrode composite material of the present disclosure, reference can be made to the above description regarding the electrode composite material of the present disclosure.

[0046] The negative electrode active material layer may have a certain thickness. The thickness of the negative electrode active material layer is not particularly limited, and may be, for example, 0.1 μm or more and 1 mm or less.

[0047] 〈Electrolyte layer〉 When the battery of the present disclosure is a liquid battery, the electrolyte layer may be formed by the separator being impregnated with the electrolytic solution.

[0048] (Separator) The material of the separator is not particularly limited as long as it has a function of electrically separating the negative electrode active material layer and the positive electrode active material layer. Examples include porous sheets made of resins such as polyethylene (PE), polypropylene (PP), polyester, cellulose, and polyamide, non-woven fabrics such as non-woven fabrics and glass fiber non-woven fabrics, and porous insulating materials such as these, or combinations thereof. The thickness of the separator is not particularly limited and may be, for example, 5 μm or more and 1 mm or less.

[0049] (Electrolytic solution) The electrolytic solution may contain a sodium salt and a non-aqueous solvent. Examples of the sodium salt include inorganic sodium salts such as NaPF6, NaBF4, NaClO4, and NaAsF6; and organic sodium salts such as NaCF3SO3, NaN(CF3SO2)2, NaN(C2F5SO2)2, NaN(FSO2)2, and NaC(CF3SO2)3.

[0050] The non-aqueous solvent is not particularly limited as long as it can dissolve the sodium salt. For example, as the high dielectric constant solvent, cyclic esters (cyclic carbonates) such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), γ-butyrolactone, sulfolane, N-methyl-2-pyrrolidone (NMP), 1,3-dimethyl-2-imidazolidinone (DMI), etc. can be mentioned. On the other hand, as the low viscosity solvent, chain esters (chain carbonates) such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), acetates such as methyl acetate, ethyl acetate, ethers such as 2-methyltetrahydrofuran, etc. can be mentioned. A mixed solvent obtained by mixing a high dielectric constant solvent and a low viscosity solvent may also be used.

[0051] When the battery of the present disclosure is a solid battery, the electrolyte layer contains a solid electrolyte and may optionally contain a conductive aid and a binder.

[0052] Regarding the solid electrolyte, the conductive aid, and the binder, the above description regarding the electrode composite material of the present disclosure can be referred to.

[0053] 〈Positive electrode active material layer〉 The positive electrode active material layer contains a positive electrode active material and may optionally contain a conductive aid and a binder. When the battery of the present disclosure is a solid battery, the positive electrode active material layer may optionally contain a solid electrolyte.

[0054] When the negative electrode active material layer contains the electrode composite material of the present disclosure, examples of the positive electrode active material include Na-containing oxides such as layered active materials, spinel-type active materials, and olivine-type active materials. Specifically, NaFeO2, NaNiO2, NaCoO2, NaMnO2, NaVO2, Na(Ni X Mn 1-X )O2(0 < X < 1), Na(Fe X Mn 1-X)Examples include O2 (0 < X < 1), NaVPO4F, Na2FePO4F, Na3V2(PO4)3, etc. The shape of the positive electrode active material is not particularly limited. The positive electrode active material may be particulate. In this case, its average particle size may be, for example, 1 nm or more or 10 nm or more, and may be 100 μm or less or 30 μm or less. The higher the content of the positive electrode active material in the positive electrode active material layer, the higher the capacity of the positive electrode. The positive electrode active material layer may contain the positive electrode active material, for example, at 50 mass% or more or 70 mass% or more, and 99 mass% or less or 95 mass% or less.

[0055] Regarding the conductive assistant, binder, and solid electrolyte, reference can be made to the above description of the electrode composite material of the present disclosure.

[0056] The positive electrode active material layer may have a certain thickness. The thickness of the positive electrode active material layer is not particularly limited, but may be, for example, 0.1 μm or more and 1 mm or less.

[0057] 〈Positive electrode current collector layer〉 Examples of the material of the positive electrode current collector layer include SUS, aluminum, nickel, iron, titanium, carbon, etc.

[0058] The positive electrode current collector layer may be, for example, in the form of a foil, mesh, or porous shape, etc.

[0059] In addition, for example, when the battery of the present disclosure is a battery other than a sodium ion battery, various materials commonly used in the battery can be used.

[0060] 〈Other configurations〉 The battery of the present disclosure may include a battery case that houses each layer of the battery, and terminals connected to a current collector, etc. Further, the battery of the present disclosure may include a restraining member that restrains each layer along the stacking direction in order to reduce the contact resistance. For these, those similar to the conventional ones may be used.

[0061] Examples of the shape of the battery of the present disclosure include coin type, laminate type, cylindrical type, and square type, etc.

[0062] "Method for Manufacturing a Battery" The method of the present disclosure for manufacturing a battery may include forming an electrode active material layer containing the electrode composite material of the present disclosure.

[0063] The method for forming the electrode active material layer may include providing an electrode composite material slurry containing the electrode composite material of the present disclosure and a dispersion medium, applying the electrode composite material slurry to a substrate, and drying and removing the dispersion medium.

[0064] Regarding the electrode composite material, reference may be made to the above description of the electrode composite material of the present disclosure.

[0065] The dispersion medium is not particularly limited, and examples include alcohol, glycol, cellosolve, amine, ketone, carboxylic acid amide, phosphoric acid amide, sulfoxide, carboxylic acid ester, phosphoric acid ester, ether, nitrile, etc. Specifically, ethanol, 2-propanol, methyl ethyl ketone, N-2-methylpyrrolidone are exemplified.

[0066] The substrate is not particularly limited, but when the negative electrode active material layer contains the electrode composite material of the present disclosure, it may be, for example, a negative electrode current collector layer.

[0067] The drying temperature, drying time, etc. can be appropriately designed according to the boiling point and usage amount of the dispersion medium, etc.

Example

[0068] "Production Example 1" 〈Production of Electrode Active Material〉 A commercially available spherical phenol resin as a raw material containing carbon was calcined and carbonized at 1500 °C for 2 hours in an argon atmosphere mixed with 0.5% air to produce hard carbon. Thereby, the electrode active material of Production Example 1 was obtained.

[0069] "Production Example 2" As a raw material containing carbon, the electrode active material of Production Example 2 was obtained in the same manner as in Production Example 1, except that commercially available coconut shell chips were used.

[0070] 《Production Example 3》 The carbon material Kuraray (manufactured by Kuraray Co., Ltd.) was fired at 2000 ° C in an argon atmosphere. Thereby, the electrode active material of Production Example 3 was obtained.

[0071] 《Comparative Production Example 1》 The carbon material Carbotron PS (F) type (manufactured by Kuraray Co., Ltd.) was fired at 1200 ° C in an argon atmosphere. Thereby, the electrode active material of Comparative Production Example 1 was obtained.

[0072] 《Comparative Production Example 2》 The electrode active material of Comparative Production Example 2 was obtained in the same manner as in Comparative Production Example 1, except that the firing temperature was 1500 ° C.

[0073] 《Example 1》 〈Preparation of electrode composite material〉 The electrode active material of Production Example 1 as a negative electrode active material and polyvinylidene fluoride (PVdF) as a binder were dispersed in N-methyl-2-pyrrolidone (NMP) so that the mass ratio was 95: 5, and stirred and mixed at 2000 rpm for 10 minutes. Thereby, a slurry-like electrode composite material (electrode composite material slurry) as a negative electrode composite material was obtained.

[0074] 〈Formation of electrode active material layer〉 The obtained electrode composite material slurry was applied onto an aluminum (Al) current collector foil as a negative electrode current collector layer using a 75 μm bar coater and dried at 80 ° C for 30 minutes. After punching out a laminate of the negative electrode current collector layer and the electrode active material layer as the negative electrode active material layer into φ16 mm, it was compression molded by a press machine so that the electrode density became 1.0 g / cc. Thereby, an electrode active material layer as a negative electrode active material layer was formed on the negative electrode current collector layer.

[0075] 〈Fabrication of evaluation cell〉 A negative electrode was fabricated as a laminate of a negative current collector layer and an electrode active material layer serving as a negative electrode active material layer. A 2032-type coin cell was fabricated using metallic sodium (Na) as the counter electrode, a 50-μm glass separator as the separator, and 1 M NaPF6 in EC:DMC = 1:1 (volume ratio) as the electrolyte.

[0076] 《Evaluation》 〈Measurement by Raman spectroscopy〉 Raman spectra of each example were obtained by Raman spectroscopy measurement (wavelength 532 nm). The baseline of the Raman spectrum was set by performing baseline analysis using the Spectrum Manager of JASCO Corporation.

[0077] 〈Charge-discharge test〉 A charge-discharge test was performed at 25°C in a voltage range of 0.01 - 1.5 V and a current value of 0.1C to evaluate the Na insertion capacity (charge capacity) and Na desorption capacity (discharge capacity) of the coin cell. Among the obtained Na insertion capacities, the low-potential capacity, that is, the capacity in the range of 0.05 - 0.01 V (vs. Na / Na + ) was calculated and taken as the capacity below 0.05 V (vs. Na / Na + ).

[0078] 《Examples 2 - 4 and Comparative Examples 1 - 5》

[0079] In the preparation process of the electrode composite, evaluation cells of Examples 2 - 4 and Comparative Examples 1 - 5 were obtained and evaluated in the same manner as in Example 1, except that the type of the electrode active material was changed as shown in Table 1.

[0080] 《Results》 The Raman spectra of Example 1 and Comparative Example 3 obtained by Raman spectroscopy are shown in FIGS. 2 and 3 (FIG. 2: Example 1, FIG. 3: Comparative Example 3). Also, the ratio I G’ of the intensity I G of the G' band to the intensity I G’ of the G band, the full width at half maximum Hw G of the D band, and the ratio I D of the intensity I D of the D band to the intensity IG Ratio I with respect to D / I G is shown in Table 1. Further, the results of the charge-discharge test are shown in Table 1 and FIG. 4.

[0081]

Table 1

[0082] As shown in FIG. 2, in the electrode active material of the present disclosure according to the example, in the Raman spectrum, it was confirmed that there is a G' band in the vicinity of 2800 to 2600 cm -1 . On the other hand, in the electrode active material according to the comparative example, the G' band was not confirmed in the Raman spectrum.

[0083] As shown in Table 1 and FIG. 4, for I G’ / I G , and the half-value width Hw of the D band D in the cells of the examples within the scope of the present disclosure, the capacity at a low potential was large. In particular, in the cells of Examples 1 and 2 where the half-value width Hw D is 90 or more and 130 or less, the capacity at a low potential was even larger.

Explanation of symbols

[0084] 100 Battery 110 Negative electrode current collector layer 120 Negative electrode active material layer 130 Electrolyte layer 140 Positive electrode active material layer 150 Positive electrode current collector layer

Claims

1. An electrode active material containing hard carbon, wherein the hard carbon has a G' band, a G band, and a D band in a Raman spectrum, The intensity I of the G' band Ｇ’ of the G band Ｇ The ratio I Ｇ’ / I Ｇ is 0.05 or more, and The half-value width Hw of the D band Ｄ is 50 or more and 160 or less, the electrode active material.

2. The half-value width Hw of the D band Ｄ is 90 or more and 130 or less, and the electrode active material according to claim 1.

3. The intensity I of the D band Ｄ and the intensity I of the G band Ｇ The ratio I Ｄ / I Ｇ is 1.0 or more and 1.6 or less, and the electrode active material according to claim 1.

4. The intensity I of the D band Ｄ and the intensity I of the G band Ｇ The ratio I Ｄ / I Ｇ is 1.2 or more and 1.4 or less. The electrode active material according to claim 3

5. An electrode composite material containing the electrode active material according to any one of Claims 1 to 4.

6. Having a negative electrode current collector layer, a negative electrode active material layer, an electrolyte layer, a positive electrode active material layer, and a positive electrode current collector layer in this order, and either the negative electrode active material layer or the positive electrode active material layer contains the electrode composite material according to Claim 5, a battery.

7. The battery according to Claim 6, wherein the negative electrode active material layer contains the electrode composite material according to Claim 5.

8. The battery according to Claim 6, which is a sodium ion battery having sodium ions in the electrolyte layer.

9. The battery according to Claim 8, which is a liquid battery in which the electrolyte layer contains an electrolytic solution having sodium ions.

10. The battery according to Claim 8, which is a solid battery in which the electrolyte layer contains a solid electrolyte having sodium ions.

11. A method for manufacturing the electrode active material according to any one of Claims 1 to 4, including the following steps: providing a raw material containing carbon, and firing and carbonizing the raw material in an inert atmosphere containing more than 0% and less than 1.0% of air.

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