JPWO2013145925A1 - Negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, lithium ion secondary battery, and production method thereof - Google Patents

Abstract

Provided is a negative electrode material for a lithium ion secondary battery that has both resistance to dissolution and lithium ion conductivity while suppressing capacity deterioration due to reductive decomposition of an electrolytic solution. A negative electrode material for a lithium ion secondary battery comprising a negative electrode active material and a coating formed on the surface of the negative electrode active material, wherein the coating is bound to the negative electrode active material, The negative electrode active material contains carbon element and oxygen element, and the ratio (O / C ratio) of the carbon element concentration to the oxygen element concentration of the negative electrode active material determined by XPS measurement is The negative electrode material for lithium ion secondary batteries which is 2.5 or more. (In (Formula 1), R11, R12, R13, and R14 are functional groups containing at least one of carbon, oxygen, nitrogen, silicon, and phosphorus. At least one of R11, R12, R13, and R14 is And a bonding group that binds to the negative electrode active material.)

Description

  The present invention relates to a negative electrode material for a lithium ion secondary battery, a negative electrode for a lithium ion secondary battery, a lithium ion secondary battery, and methods for producing them.

  From the viewpoints of environmental protection and energy saving, hybrid vehicles using both an engine and a motor as a power source have been developed and commercialized. A secondary battery capable of repeatedly charging and discharging electricity as an energy source of this hybrid vehicle is an essential technology.

  Among them, the lithium ion battery is a battery having a high operating voltage and a high energy density that easily obtains a high output, and is becoming increasingly important as a power source for a hybrid vehicle in the future. Lithium ion secondary batteries have a problem in that the electrolyte is reduced and decomposed at the time of initial charge, whereby an organic film is formed on the carbon surface, which is the active material of the negative electrode, resulting in a decrease in capacity and an increase in internal resistance. there were.

  Conventionally, as a countermeasure against the above-mentioned problems, a countermeasure has been proposed in which a compound such as vinylene carbonate is added to an electrolyte solution to form an organic film on the carbon surface.

  However, since the organic film derived from the additive is not chemically adsorbed on the carbon surface, there is a problem that the solubility in a solvent is low and the durability of the film is low. In addition, when stored at a high temperature in a fully charged state, the film resistance increases, making it difficult for lithium ions to move, making it difficult to use at high rates. Furthermore, when the charge / discharge cycle is repeated, the coating is damaged without being able to follow the expansion and contraction of the carbon, and there is a problem that the newly formed active carbon surface reacts with the electrolyte and the capacity deterioration proceeds. .

  As an alternative method, a method of coating the carbon surface with amorphous carbon or an organic polymer has been proposed and has been effective. Since the active site of the reductive decomposition of the electrolytic solution existing on the active material surface is covered, the first irreversible capacity can be suppressed.

  For example, in Non-Patent Documents 1 and 2, an amorphous carbon layer is formed on the surface by heating natural graphite in a 1000 ° C. hydrocarbon gas to suppress reductive decomposition of the electrolytic solution. In Non-Patent Document 3, a mixture of a polymer and artificial graphite is sintered under vacuum at 100 ° C. for 10-12 hours to form a polymer coating layer on the active material, thereby suppressing the initial irreversible capacity. Yes. Compared with the amorphous coating, surface treatment can be performed at low cost.

  In patent document 1, the technique which suppresses the fall rate of the capacity | capacitance maintenance factor after 1 time charging / discharging by processing a carbon fiber with a silane coupling agent is proposed.

  Patent Document 2 proposes a technique for modifying the surface of a silicon oxide surface with a terminal hydrolyzable modified silicone.

  Non-Patent Document 4 succeeds in significantly reducing the initial irreversible capacity by performing silane coupling treatment after vapor-phase oxidation of carbon in a 1000 ° C. argon atmosphere.

JP-A-8-273660 JP 2011-014298 A

Journal of The Electrochemical Society, 147 (4), 1245-1250 (2000) Journal of The Electrochemical Society, 149 (4), A499-A503 (2002) Electrochemical and Solid-State Letters, 3 (4), 171-173 (2000) Journal of Power Sources, 97-98, 126-128 (2001)

  Amorphous carbon coating will not solve the problem by adding a compound such as vinylene carbonate to the electrolyte solution because an uncoated active part remains if the coating amount is small, and it must be used in combination with an additive. . Moreover, when there is much coating amount with an amorphous carbon, there exists a subject that interface resistance increases.

  In addition, since the polymer coating is not chemically bonded to the surface of the coated graphite, the problem of low solvent solubility cannot be solved. If the molecular weight of the coating molecule is increased to improve dissolution resistance, lithium ion conduction There was a problem that became difficult.

  Since films and polymers made of additives do not form bonds with the carbon surface, especially when stored at high temperatures, the electrolyte solution penetrates the coating layer and the coating layer swells, so that the electrolyte solution contains highly active carbon. Contact the outermost surface.

  In the silane coupling agent treatment of carbon as in Patent Document 1 and Patent Document 2, since the silane coupling agent can be chemically bonded to the carbon surface, an improvement in dissolution resistance can be expected. However, when the number of binding sites on the carbon surface is small, sufficient coating cannot be performed, and the electrolytic solution is reduced and decomposed in the uncoated portion, increasing the irreversible capacity.

  In the oxidation treatment using a gas phase as in Non-Patent Document 1, graphite is treated in a high-temperature gas and oxygen-containing functional groups are attached to the graphite surface, and oxidation occurs at the interface between the gas and the solid. May be uniform. The present invention relates to a negative electrode material for a lithium ion secondary battery, a negative electrode for a lithium ion secondary battery, a lithium ion secondary battery, and a lithium ion secondary battery that are compatible with lithium ion conductivity while suppressing capacity deterioration due to reductive decomposition of the electrolyte. An object is to provide a manufacturing method.

The features of the present invention are, for example, as follows.
A negative electrode material for a lithium ion secondary battery comprising a negative electrode active material and a coating formed on the surface of the negative electrode active material, wherein the coating is bound to the negative electrode active material, The negative electrode active material contains carbon element and oxygen element, and the ratio (O / C ratio) of the carbon element concentration to the oxygen element concentration of the negative electrode active material determined by XPS measurement is The negative electrode material for lithium ion secondary batteries which is 2.5 or more.

(In (Formula 1), R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are functional groups containing at least one of carbon, oxygen, nitrogen, silicon and phosphorus. R ₁₁ , R ₁₂ , R ₁₃ , At least one of R ₁₄ is a linking group that binds to the negative electrode active material.)
In the above, the bonding group is a negative electrode material for a lithium ion secondary battery that is any one or more of (Formula 2), (Formula 3), and (Formula 4).

(In (Formula 2), R ₂₁ is an alkyl group having 1 to 10 carbon atoms. In (Formula 3), R ₃₁ is a halogen element or an alkyl halide having 1 to 10 carbon atoms. (Formula 4) R ₄₁ , R ₄₂ and R ₄₃ are functional groups composed of at least one of carbon, oxygen, nitrogen, silicon and phosphorus elements.)
In the above, R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₄₁ , R ₄₂ , R ₄₃ are hydrogen group, alkyl group having 1 to 10 carbon atoms, hydroxyl group, phenyl group, polyalkylene oxide group, polysiloxane. A negative electrode material for a lithium ion secondary battery, which is one or more of a group, an alkyl group, a polyphosphazene group, or the bonding group.

  In the above, the negative electrode material for lithium ion secondary batteries whose O / C ratio is 2.5 or more and 30 or less.

  In the above, the negative electrode material for lithium ion secondary batteries whose O / C ratio is 4.0 or more and 7.0 or less.

In the above, R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₄₁ , R ₄₂ , R ₄₃ represent (Formula 5), (Formula 6), (Formula 7), (Formula 8), or A negative electrode material for a lithium ion secondary battery.

(In (Formula 5), R ₅₁ , R ₅₂ , and R ₅₃ are hydrogen or an alkyl group having 1 to 18 carbon atoms, and n is 1 or more and 100 or less. In (Formula 6), R ₆₁ is: Hydrogen or an alkyl group having 1 to 18 carbon atoms, and m is 1 to 100. In Formula 7, R ₇₁ is hydrogen or an alkyl group having 1 to 18 carbon atoms, and m is 1 And in the formula (8), R ₈₁ , R ₈₂ , and R ₈₃ are hydrogen or an alkyl group having 1 to 18 carbon atoms, and l is 1 or more and 100 or less.
In the above, the negative electrode active material is a negative electrode material for a lithium ion secondary battery, which is natural graphite.

  In the above, the negative electrode active material is a negative electrode material for a lithium ion secondary battery that has been oxidized.

  In the above, the coating agent is a negative electrode for a lithium ion secondary battery that is any one or more of (Formula 9), (Formula 10), (Formula 11), (Formula 12), (Formula 13), and (Formula 14). Wood.

  In the above, for the lithium ion secondary battery, the coating agent is any two or more of (Formula 9), (Formula 10), (Formula 11), (Formula 12), (Formula 13), and (Formula 14). Negative electrode material.

  The negative electrode for lithium ion secondary batteries which has said negative electrode material for lithium ion secondary batteries.

  The lithium ion secondary battery which has said negative electrode for lithium ion secondary batteries.

  A negative electrode material for a lithium ion secondary battery having a negative electrode active material and a coating agent formed on the surface of the negative electrode active material, wherein the coating agent is bonded to the negative electrode active material, A method for producing a negative electrode material for a lithium ion secondary battery, which is at least one compound represented by (Formula 1), and the negative electrode active material is oxidized in an oxidation treatment step for 2 hours or more.

(In (Formula 1), R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are functional groups containing at least one of carbon, oxygen, nitrogen, silicon and phosphorus. R ₁₁ , R ₁₂ , R ₁₃ , At least one of R ₁₄ is a linking group that binds to the negative electrode active material.)

  According to the present invention, a negative electrode material for a lithium ion secondary battery, a negative electrode for a lithium ion secondary battery, and a lithium ion secondary battery that achieve both dissolution resistance and lithium ion conductivity while suppressing capacity deterioration due to reductive decomposition of the electrolytic solution Batteries and methods for manufacturing them can be provided. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

The figure which represents typically the internal structure of the battery which concerns on one Embodiment of this invention. FIG. 3 is a schematic diagram of the bonding between the negative electrode active material and the coating agent. FIG. 3 is a schematic diagram of the bonding between the negative electrode active material and the coating agent.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description shows specific examples of the contents of the present invention, and the present invention is not limited to these descriptions. Various modifications by those skilled in the art are within the scope of the technical idea disclosed in this specification. Changes and modifications are possible. In all the drawings for explaining the present invention, components having the same function are denoted by the same reference numerals, and repeated description thereof may be omitted.

  FIG. 1 is a diagram schematically showing the internal structure of a battery according to an embodiment of the present invention. A battery 1 according to an embodiment of the present invention shown in FIG. 1 includes a positive electrode 10, a separator 11, a negative electrode 12, a battery can 13, a positive electrode current collecting tab 14, a negative electrode current collecting tab 15, an inner lid 16, an internal pressure release valve 17, It comprises a gasket 18, a positive temperature coefficient (PTC) resistance element 19, a battery lid 20, and an axis 21. The battery lid 20 is an integrated part composed of the inner lid 16, the internal pressure release valve 17, the gasket 18, and the PTC resistance element 19. A positive electrode 10, a separator 11, and a negative electrode 12 are wound around the shaft center 21.

  The separator 11 is inserted between the positive electrode 10 and the negative electrode 12 to produce an electrode group wound around the axis 21. As the axis 21, any known one can be used as long as it can support the positive electrode 10, the separator 11, and the negative electrode 12. In addition to the cylindrical shape shown in FIG. 1, the electrode group has various shapes such as a laminate of strip electrodes, or a positive electrode 10 and a negative electrode 12 wound in an arbitrary shape such as a flat shape. Can do. The shape of the battery can 13 may be selected from shapes such as a cylindrical shape, a flat oval shape, a flat oval shape, and a square shape according to the shape of the electrode group.

  The material of the battery can 13 is selected from materials that are corrosion resistant to the non-aqueous electrolyte, such as aluminum, stainless steel, and nickel-plated steel. Further, when the battery can 13 is electrically connected to the positive electrode 10 or the negative electrode 12, the material is not deteriorated due to corrosion of the battery can 13 or alloying with lithium ions in the portion in contact with the nonaqueous electrolyte. Thus, the material of the battery container 13 is selected.

  The electrode group is housed in the battery can 13, the negative electrode current collecting tab 15 is connected to the inner wall of the battery can 13, and the positive electrode current collecting tab 14 is connected to the bottom surface of the battery lid 20. The electrolyte is injected into the battery can 13 before the battery is sealed. As a method for injecting the electrolyte, there are a method of adding directly to the electrode group in a state where the battery cover 20 is released, or a method of adding from an injection port installed in the battery cover 20.

  Thereafter, the battery lid 20 is brought into close contact with the battery can 13 to seal the entire battery. If there is an electrolyte inlet, seal it as well. As a method for sealing the battery, there are known techniques such as welding and caulking.

  The lithium ion secondary battery according to an embodiment of the present invention can be manufactured by, for example, disposing the following negative electrode and positive electrode facing each other via a separator and injecting an electrolyte. The structure of the lithium ion battery according to an embodiment of the present invention is not particularly limited. Usually, the positive electrode and the negative electrode and the separator separating them are wound into a wound electrode group, or the positive electrode, the negative electrode, and the separator are combined. A stacked electrode group can be formed by stacking.

<Negative electrode>
The negative electrode in the present invention is formed by applying a negative electrode mixture layer comprising a negative electrode material (with a coating material formed on the surface of a negative electrode active material) and a binder onto a copper foil as a current collector. Is done. Further, a conductive agent may be further added to the negative electrode mixture layer in order to reduce electronic resistance.

  As a method for coating a negative electrode of a lithium ion secondary battery, a method in which an active material is coated with a polymer and then fired at a high temperature to form an amorphous carbon layer, or an amorphous material is formed on the surface of the active material in a high-temperature gas. There have been proposed a method of sintering the surface, a method of coating the surface with a conductive polymer or a general-purpose polymer at room temperature, and the like. However, there are still problems in processing such as difficulty in coexistence with output characteristics, increase in cost due to long-time high-temperature treatment, and difficulty in uniform coating.

  In response to this problem, a method has been proposed in which the negative electrode active material is coated with a silane coupling agent. However, since the silane coupling reaction is a reaction between the surface of the negative electrode active material and the silane coupling agent, the amount of binding between the negative electrode active material and the coating agent, that is, the strength of the coating is the same as the state of the negative electrode surface. It is greatly influenced.

  In particular, it has been found that a sufficient coating layer cannot be formed by a silane coupling agent on a negative electrode active material having a small amount of oxygen on the surface and a negative electrode active material having a variation in the amount of oxygen.

  In one embodiment of the present invention, an oxygen-containing functional group such as a hydroxyl group, a carboxyl group, or a lactone group is introduced into the surface of the negative electrode active material as a pretreatment for performing a reactive organosilicon compound treatment on the surface of the negative electrode active material. By performing the oxidation treatment, the reaction between the hydrolyzable group of the reactive organosilicon compound and the surface of the active material was promoted, and the coating amount could be increased.

  The negative electrode material that has been subjected to such oxidation treatment and covered a part or all of the surface of the negative electrode active material can be expressed, for example, as follows. A negative electrode material having a negative electrode active material and a coating agent formed on the surface of the negative electrode active material, wherein the coating agent is bonded to the negative electrode active material, and the coating agent is at least represented by the following (formula 1): A negative electrode material which is a kind of compound, the negative electrode active material contains carbon element and oxygen element, and the ratio of the carbon element concentration to the oxygen element concentration of the negative electrode active material determined by XPS measurement is 2.5 or more.

In (Formula 1), R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are functional groups containing at least one of carbon, oxygen, nitrogen, silicon and phosphorus. At least one of R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ is a linking group that binds to the negative electrode active material.

  The coating agent represented by (Formula 1) has a bonding group that can bond to oxygen on the surface of the negative electrode active material. The coating agent and the negative electrode active material are bonded by a coupling reaction. Since the coating agent is bonded to the negative electrode active material and the active material through a covalent bond, the coating has high solvent resistance. Since the silane coupling reaction is a reaction between oxygen on the surface of the negative electrode active material and the binding group of the coating agent, the amount of binding between the negative electrode active material and the coating agent, that is, the strength of the coating, is the state of the negative electrode surface. It is greatly influenced.

<Coating group of coating agent>
The binding group of the coating agent is a functional group that can bind to oxygen on the negative electrode. For example, (Expression 2), (Expression 3), (Expression 4), and the like can be used, but the present invention is not limited thereto.

In (Formula 2), R ₂₁ is an alkyl group having 1 to 10 carbon atoms. For bonding with oxygen on the surface of the negative electrode active material, the number of carbon atoms is preferably as small as possible, and the number of carbon atoms is most preferably 1 or 2.

In (Formula 3), R ₃₁ is a halogen element or an alkyl halide having 1 to 10 carbon atoms. For bonding with oxygen on the surface of the negative electrode active material, the number of carbon atoms is preferably as small as possible, and the number of carbon atoms is most preferably 1 or 2.

In (Formula 4), R ₄₁ , R ₄₂ , and R ₄₃ are functional groups composed of at least one of carbon, oxygen, nitrogen, silicon, and phosphorus elements. The structure of —NH—Si is important for bonding with oxygen on the surface of the negative electrode active material, and R ₄₁ , R ₄₂ , and R ₄₃ are not particularly limited. From the viewpoint of lithium ion conductivity, a polyalkylene oxide group, a polysiloxane group, a polyphosphazene group, and the like are preferable.

In (Formula 4), when R ₄₁ , R ₄₂ and R ₄₃ are carbon chains, the number of carbon atoms is preferably large. 1-18 are preferable and, as for carbon number of a carbon chain, 6-18 are more preferable. By setting the carbon number to be large, the graphite surface can be coated with a small amount of the silane coupling agent, so that the contact between the electrolytic solution and the carbon surface can be effectively prevented. In addition, when the number of carbon atoms is 18 or more, graphite coated with a silane coupling agent tends to aggregate, and when an electrode is produced using the aggregated graphite, there is an adverse effect of damaging the copper foil when the electrode is pressed. Occur.

  Oxygen present on the negative electrode active material is an oxygen-containing functional group such as a hydroxyl group, a carboxyl group, or a lactone group. Such oxygen-containing functional groups are randomly present on the surface of the negative electrode active material such as carbon. The amount of the oxygen-containing functional group varies greatly depending on the negative electrode active material species or the production area. For this reason, in order to form a sufficient coating layer on the surface of the negative electrode active material, it is considered that a sufficient amount of oxygen-containing functional groups is required on the surface of the negative electrode active material.

<Introduction method of bonding group>
In one embodiment of the present invention, the method for introducing a sufficient amount of oxygen-containing functional groups onto the carbon surface includes oxidation treatment. The oxidation treatment step is not particularly limited, but gas phase oxidation is performed by heating in an oxygen atmosphere, oxidation in the presence of a catalyst such as hydrogen peroxide, hydrochloric acid, sulfuric acid, nitric acid, permanganic acid, perchloric acid, or those Liquid phase oxidation that oxidizes in a solution obtained by adding a salt to the acid, and chemically bond one or more oxygen-containing functional groups such as hydroxyl group, carboxyl group, lactone group and the like with a carbon material in one molecule. A method of applying a carbon surface coating with a treating agent having a molecular structure to be obtained is applicable. As a result of investigating that the carbon structure does not change and the reproducibility of the introduction amount of the functional group, it was concluded that liquid phase oxidation is the most preferred embodiment.

<Measurement method>
The oxygen-containing functional group on the negative electrode active material can be measured by XPS measurement (X-ray Photoelectron Spectroscopy). A sufficient amount of oxygen-containing functional group has a value of 2.5 or more in the ratio of the carbon element concentration to the oxygen element concentration (hereinafter referred to as O / C ratio) of the negative electrode active material determined by XPS measurement. It is. The value is preferably 2.5 or more and 30 or less, and more preferably 4.0 or more and 7.0 or less. When the value of the O / C ratio is 2.5 or less, the number of bonding groups is small, and a sufficient bonding amount cannot be ensured between the negative electrode active material and the coating agent. Further, when the O / C ratio is 30 or more, the amount of oxidation on the surface of the negative electrode active material is large, which may affect the structure of the negative electrode active material. The O / C ratio value is preferably 4.0 or more and 7.0 or less from the balance between securing the bonding amount between the negative electrode active material and the coating agent and the structural collapse of the negative electrode active material. The O / C ratio can be calculated by measuring the O1s peak and C1s peak intensity ratio (hereinafter referred to as O / C ratio) by XPS measurement and using the integrated value of the peak.

  A state in which a negative electrode active material having an O / C ratio of 2.5 or more is coated with a coating agent is detected by measuring a carbon (aromatic ring) -oxygen-silicon bond on the negative electrode active material by XPS measurement. be able to. A carbon (aromatic ring) -oxygen-silicon bond is formed by combining the carbon element of the negative electrode active material and the coating agent.

  When sufficient oxygen is present on the negative electrode active material (the value of the O / C ratio is 2.5 or more) and a sufficient bond is formed, the peak corresponding to the carbon (aromatic ring) -oxygen-silicon bond is 531. Appears around .6 eV. The ratio of the peak area of the carbon (aromatic ring) -oxygen-silicon bond in the integrated value of the peak areas of 528 eV to 536 eV of the oxygen 1s orbital is a value of 1 or more and 90 or less. Further, when the amount of bonding is large and this is a preferable state, this value is 10 or more and 75 or less.

<Negative electrode active material>
The material used as the negative electrode active material includes natural graphite, a composite carbonaceous material in which a film formed by a dry CVD (Chemical Vapor Deposition) method or a wet spray method is formed on natural graphite, a resin raw material such as epoxy or phenol, or Carbonaceous materials such as artificial graphite and amorphous carbon materials produced by firing from pitch-based materials obtained from petroleum or coal, or lithium and compounds formed with lithium and inserted into the crystal gaps Oxides or nitrides of Group 4 elements such as silicon and tin that can be occluded and released can be used. In particular, the carbonaceous material is a material having high conductivity, and excellent in terms of low temperature characteristics and cycle stability. Among the carbonaceous materials, a material having a wide carbon network surface layer (d ₀₀₂ ) is excellent in rapid charge / discharge and low temperature characteristics, and is suitable. However, since a material having a wide d ₀₀₂ may have a reduced capacity and a low charge / discharge efficiency at the initial stage of charging, d ₀₀₂ is preferably 0.390 nm or less. May be called. Furthermore, a carbonaceous material having high conductivity such as graphite, amorphous, activated carbon or the like may be mixed to constitute the electrode. Alternatively, a material having the characteristics shown in (1) to (3) below may be used as the graphite material.
(1) peak in the range of 1300～1400Cm ^-1 measured by Raman spectrum intensity (I _D) and the peak intensity in the range of 1580～1620Cm ^-1 as measured by Raman spectroscopy spectra (I _G) and the The R value (I _D / I _G ), which is an intensity ratio, is 0.20 or more and 0.40 or less. (2) The peak half-value width Δ value in the range of 1300 to 1400 cm ⁻¹ measured by a Raman spectrum is 40 cm ^-1 or more 100 cm ^-1 or less (3) the intensity ratio X values of the peak intensity of the (110) plane in X-ray diffraction (I ₍₁₁₀₎₎ and (004) plane peak intensity (I ₍₀₀₄₎₎ (I ₍₁₁₀₎ / I ₍₀₀₄₎ ) is 0.10 or more and 0.45 or less The amount of oxygen on the negative electrode active material can be increased by oxidation treatment. For this reason, even a negative electrode active material having a large surface variation, such as natural graphite, can be uniformly coated with a sufficient coating agent.

  Since it is a linking group as described above that forms a bond with the negative electrode active material, groups other than the linking group are not particularly limited. Examples of groups other than the linking group include a hydrogen group, an alkyl group having 1 to 10 carbon atoms, a hydroxyl group, a phenyl group, a polyalkylene oxide group, a polysiloxane group, an alkyl group, and a polyphosphazene group.

  Examples of the polysiloxane group include (Formula 5), examples of the polyalkylene oxide group include (Formula 6) and (Formula 7), and examples of the alkyl group include (Formula 8).

In (Formula 5), R ₅₁ , R ₅₂ , and R ₅₃ are hydrogen or an alkyl group having 1 to 10 carbon atoms, and n is 1 or more and 100 or less.

In (Formula 6), R ₆₁ is hydrogen or an alkyl group having 1 to 10 carbon atoms, and m is 1 or more and 100 or less.

In (Formula 7), R ₇₁ is hydrogen or an alkyl group having 1 to 10 carbon atoms, and m is 1 or more and 100 or less.

In (Formula 8), R ₈₁ , R ₈₂ , and R ₈₃ are hydrogen or an alkyl group having 1 to 10 carbon atoms, and 1 is 1 or more and 100 or less.

  As the alkyl group, the number of carbon atoms is not particularly limited, but 1 to 20 is preferable from the viewpoint of lithium ion conductivity. n, m, and l are 1 or more and 100 or less. From the viewpoint of lithium ion conductivity, 1 to 20 is preferable.

  From the viewpoint of lithium ion conductivity, oxygen-containing groups such as polyalkylene oxide groups, polysiloxane groups, and polyphosphazene groups are preferred. When lithium ions are occluded in the coated negative electrode active material, the lithium ions move to the negative electrode active material through the coating. Oxygen in the polyalkylene oxide group, polysiloxane group, and polyphosphazene group draws only lithium ions from lithium ions solvated in the electrolytic solution, and retains lithium ions in the oxygen portion. Lithium ions move to the adjacent oxygen in the polyalkylene oxide group, polysiloxane group, and polyphosphazene group, and are occluded by the negative electrode active material.

<Additional concentration of coating agent>
The amount of the reactive organosilicon compound that is the surface treatment agent used in one embodiment of the present invention is not particularly limited, but is preferably determined in consideration of the specific surface area S of the carbon powder to be used. That is, the processing agent varies depending on the type, it is estimated that roughly per 1g can cover the area from 100 m ² 600 meters ² [S = (m ² / g) to] Therefore, the specific surface area of the carbon powder to be used Assuming that A (m ² / g), the amount of A / S (g) treating agent is preferably used as one standard per gram of carbon powder. However, the irreversible capacity can be significantly reduced even with the use amount in which the entire surface area of the carbon powder cannot be coated with the treatment agent. More specifically, the amount of the treatment agent is preferably 0.01 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, with respect to 100 parts by weight of the carbon powder used. Particularly preferred is 0.5 to 1 part by weight.

  Whether or not an appropriate amount of treatment agent has been coated can also be confirmed using the integrated value of the peak intensity of XPS. When the coated graphite powder is measured by XPS, peaks corresponding to carbon, oxygen, and silicon, which are elements constituting the silane coupling agent, are observed. The peaks of carbon and oxygen are superimposed with the peaks of oxygen-containing functional groups present in a trace amount on the graphite and graphite surfaces. On the other hand, since the silicon peak is observed only in the coated graphite, the coating amount of the silane coupling agent can be estimated from the silicon peak intensity. The peak intensity can be quantified by a peak area which is an integrated value of peaks. The Si / C ratio, which is the ratio of the peak area of 100 eV to 104 eV of silicon 1s orbital and the peak area of 527.5 eV to 536.5 eV of oxygen 1s orbital, represents the concentration of the silane coupling agent relative to graphite. % To 10% is preferable, more preferably 0.2% to 5%, and particularly preferably 0.3% to 2.5%.

  In addition, the method of treating the active material with the treatment agent is not particularly limited, but after adding a required amount of water or a mixture of water and alcohol to hydrolyze a part or the whole of the active material powder and mixing it. And a method of filtering and drying in a heating oven.

The reactive organosilicon compound that is the surface treating agent used in one embodiment of the present invention may be used alone or in combination of two or more. For example, surface treatment with a silane or siloxane represented by the average formula _Ch H _i Si ₂ O _j N _k (h, i, j is a positive number, k is 0 or a positive number) and (jh) is greater than 0 After that, it is also possible to perform surface treatment with the reactive organosilicon compounds represented by (Formula 1) to (Formula 14).

<Binder>
As the binder, any material may be used as long as the material constituting the negative electrode and the current collector for the negative electrode are brought into close contact with each other. For example, a homopolymer or copolymer such as vinylidene fluoride, tetrafluoroethylene, acrylonitrile, ethylene oxide, styrene- Examples thereof include butadiene rubber. The conductive agent is, for example, a carbon material such as carbon black, graphite, carbon fiber, and metal carbide, and each may be used alone or in combination.

<Positive electrode>
The positive electrode is formed by applying a positive electrode mixture layer composed of a positive electrode active material, an electronic conductive material and a binder onto an aluminum foil as a current collector. Moreover, you may add a electrically conductive agent to the positive mix layer for reduction of electronic resistance. The positive electrode active material in the composition formula _{Li α Mn x M1 y M2 z} O 2 ( wherein, M1 is at least one selected Co, from Ni, M2 is, Co, Ni, Al, B , Fe, Mg, Cr At least one selected from x + y + z = 1, 0 <α <1.2, 0.2 ≦ x ≦ 0.6, 0.2 ≦ y ≦ 0.4, 0.05 ≦ z ≦ 0.4. ) Is preferable. Among these, it is more preferable that M1 is Ni or Co and M2 is Co or Ni. LiMn _1/3 Ni _1/3 Co _1/3 O ₂ is more preferable. In the composition, if Ni is increased, the capacity can be increased, if Co is increased, the output at a low temperature can be improved, and if Mn is increased, the material cost can be suppressed. In addition, the additive element is effective in stabilizing the cycle characteristics. In addition, the general formula LiM _x PO ₄ (M: Fe or Mn, 0.01 ≦ X ≦ 0.4) and LiMn _1-x M _x PO ₄ (M: divalent cation other than Mn, 0.01 ≦ An orthorhombic phosphate compound having symmetry of the space group Pmnb where X ≦ 0.4) may be used. In particular, LiMn _1/3 Ni _1/3 Co _1/3 O ₂ has high low-temperature characteristics and high cycle stability, and is suitable as a lithium battery material for hybrid vehicles (HEV). The binder may be any material as long as the material constituting the positive electrode and the current collector for the positive electrode are in close contact with each other. For example, a homopolymer or copolymer such as vinylidene fluoride, tetrafluoroethylene, acrylonitrile, ethylene oxide, styrene- Examples thereof include butadiene rubber. The conductive agent is, for example, a carbon material such as carbon black, graphite, carbon fiber, and metal carbide, and each may be used alone or in combination.

<Separator>
The separator 11 is inserted between the positive electrode 10 and the negative electrode 12 produced by the above method to prevent a short circuit between the positive electrode 10 and the negative electrode 12. The separator 11 can be a polyolefin polymer sheet made of polyethylene, polypropylene, or the like, or a two-layer structure in which a polyolefin polymer and a fluorine polymer sheet typified by tetrafluoropolyethylene are welded. It is. A mixture of ceramics and a binder may be formed in a thin layer on the surface of the separator 11 so that the separator 11 does not shrink when the battery temperature increases. Since these separators 11 need to allow lithium ions to permeate during charging and discharging of the battery, they can be used for lithium ion batteries as long as the pore diameter is generally 0.01 to 10 μm and the porosity is 20 to 90%. .

<Electrolyte>
As a representative example of an electrolyte solution that can be used in an embodiment of the present invention, a solvent obtained by mixing ethylene carbonate with dimethyl carbonate, diethyl carbonate, or ethyl methyl carbonate, lithium hexafluorophosphate (LiPF ₆ ) as an electrolyte, Alternatively, there is a solution in which lithium borofluoride (LiBF ₄ ) is dissolved. The present invention is not limited to the type of solvent and electrolyte, and the mixing ratio of solvents, and other electrolytes can be used.

  Examples of non-aqueous solvents that can be used in the electrolyte include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, γ-butyrolactone, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, 1,2-dimethoxyethane, 2 -Methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, methyl propionate, ethyl propionate, phosphate triester, trimethoxymethane, dioxolane, diethyl ether, sulfolane, 3-methyl-2- There are nonaqueous solvents such as oxazolidinone, tetrahydrofuran, 1,2-diethoxyethane, chloroethylene carbonate, or chloropropylene carbonate. Other solvents may be used as long as they do not decompose on the positive electrode 10 or the negative electrode 12 incorporated in the battery of the present invention.

In addition, examples of the _{electrolyte, LiPF 6, LiBF 4, LiClO} 4, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, or imide salts such as lithium represented by lithium trifluoromethane sulfonimide, multi There are different types of lithium salts. A nonaqueous electrolytic solution obtained by dissolving these salts in the above-mentioned solvent can be used as a battery electrolytic solution. An electrolyte other than this may be used as long as it does not decompose on the positive electrode 10 and the negative electrode 12 included in the battery according to the present embodiment.

  When a solid polymer electrolyte (polymer electrolyte) is used, an ion conductive polymer such as polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, polyhexafluoropropylene, and polyethylene oxide can be used for the electrolyte. When these solid polymer electrolytes are used, there is an advantage that the separator 11 can be omitted.

Furthermore, an ionic liquid can be used. For example, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4), mixed complex of lithium salt LiN (SO ₂ CF ₃ ) ₂ (LiTFSI), triglyme and tetraglyme, cyclic quaternary ammonium cation (N-methyl) -N-propylpyrrolidinium is exemplified) and an imide-based anion (bis (fluorosulfonyl) imide is exemplified), and a combination that does not decompose at the positive electrode 10 and the negative electrode 12 is selected, and according to this embodiment. Can be used for batteries.

  A lithium ion battery according to an embodiment of the present invention can be manufactured by, for example, disposing the above-described negative electrode and positive electrode facing each other via a separator and injecting an electrolyte. The structure of the lithium ion battery according to an embodiment of the present invention is not particularly limited. Usually, the positive electrode and the negative electrode and the separator separating them are wound into a wound electrode group, or the positive electrode, the negative electrode, and the separator are combined. A stacked electrode group can be formed by stacking.

  Hereinafter, modes for carrying out the present invention will be described with reference to specific examples.

<Coated negative electrode active material>
100 g of natural graphite as a negative electrode active material was dispersed in 500 ml of 30% hydrogen peroxide and stirred for 10 hours. The active material washed with pure water and filtered was dried in a vacuum atmosphere at 120 ° C. for 5 hours.

  10 g of the obtained active material was dispersed in 30 ml of a water: ethanol mixed solvent (volume ratio 1: 9), and 0.1 g of a reactive organosilicon compound represented by the following (formula 9) was added dropwise with stirring. Table 1 shows the weight concentration of the silane coupling agent with respect to 1 g of carbon.

  After stirring at room temperature for 1 hour, the filtered solid is washed 5 times with ethanol, dried in a vacuum atmosphere at 60 ° C. for 12 hours, sized with a sieve having a mesh pore of 50 μm, and reacted with a reactive organosilicon compound. A coated carbon composite material was obtained.

Regarding the presence of the reactive organosilicon compound coated on the negative electrode active material, the characteristics derived from the bond between the oxygen-containing functional group present on the carbon and the reactive silicon compound were measured by measuring the transmission infrared absorption spectrum. This can be confirmed by observing typical stretching vibration. In this example, the stretching vibration of Si—O was confirmed near 1115 cm ⁻¹ , and it was confirmed that a covalent bond was formed.

<Creation of battery>
First, LiMn _1/3 Ni _1/3 Co _1/3 O ₂ is used as the positive electrode active material, carbon black (CB1) and graphite (GF2) are used as the electronic conductive material, and polyvinylidene fluoride (PVDF) is used as the binder. And the solid content weight at the time of drying is NMP (as a solvent so that the ratio of LiMn _1/3 Ni _1/3 Co _1/3 O ₂ : CB1: GF2: PVDF = 86: 9: 2: 3 A positive electrode material paste was prepared using (N-methylpyrrolidone).

  This positive electrode material paste was applied to an aluminum foil to be the positive electrode current collector 1, dried at 80 ° C., pressed with a pressure roller, and dried at 120 ° C. to form a positive electrode mixture layer on the positive electrode current collector.

  Next, using the coated negative electrode active material, using SBR as the binder and CMC as the thickener, the solid content weight at the time of drying was as follows: coated negative electrode active material: CMC: SBR = 97: 1.5: 1.5 A negative electrode material paste was prepared using water as a solvent so as to achieve a ratio.

  This negative electrode material paste was applied to a copper foil serving as a negative electrode current collector, dried at 80 ° C., pressed with a pressure roller, and dried at 120 ° C. to form a negative electrode mixture layer on the negative electrode current collector.

As an electrolytic solution, a solvent was mixed at a volume composition ratio EC: DMC: EMC = 20: 40: 40, and 1M LiPF ₆ was dissolved as a lithium salt to prepare an electrolytic solution.

  A separator and a lithium reference electrode were sandwiched between the prepared electrodes, and an electrolytic solution was injected to prepare a tripolar battery.

<Battery evaluation>
The capacity maintenance rate and rate characteristics of the tripolar battery after the first, 50 cycles, 100 cycles, and 200 cycles, and the oxygen-containing functional group amount were evaluated by the following procedures.

<Initialization>
The battery was charged at a constant current of 0.3 C to 4.1 V, charged at a constant voltage of 4.1 V until the current value reached 20 mA, and after 30 minutes of operation stop, discharged at 0.3 C to 3.0 V. The initial discharge capacity relative to the initial charge capacity is defined as the initial charge / discharge efficiency, and the results are shown in Table 1. This operation was repeated 5 times.

<Cycle capacity maintenance rate evaluation method>
Then, 50 cycles, 100 cycles, and 200 cycles charge / discharge were repeated at 1C. The discharge capacity after each cycle relative to the initial capacity is defined as the capacity maintenance rate, and the results are shown in Table 1.

<High temperature storage capacity maintenance rate evaluation method>
The battery after initialization was stored in a thermostat at 50 ° C. for 3 months. The ratio of the discharge capacity after storage to the discharge capacity at the fifth initialization is defined as the capacity retention rate, and the results are shown in Table 1.

<Method for evaluating oxygen-containing functional group amount>
XPS measurement of the active material after the oxidation treatment was performed, and the O1s peak and C1s peak intensity ratio (hereinafter referred to as O / C ratio) was calculated. For the calculation of the O / C ratio, the integrated value of the peak was used.

<Evaluation method of coating amount>
Si / C was calculated by XPS measurement of the negative electrode active material after coating with the coating material. Si / C was calculated from the ratio of the integrated value of the peak area of 100 eV to 104 eV of the silicon 1s orbital and the integrated value of the peak area of 527.5 eV to 536.5 eV of the oxygen 1s orbital measured by XPS measurement.

  In Example 1, instead of (Formula 9), a battery was produced and evaluated in the same manner as in Example 1 except that a reactive organosilicon compound represented by the following (Formula 10) was used. The results are shown in Table 1.

In this example, when a transmission infrared absorption spectrum was measured, stretching vibration of Si—O was confirmed near 1115 cm ⁻¹ , and it was confirmed that a covalent bond was formed. FIG. 2 shows a schematic view of the bonding between the negative electrode active material and the coating material corresponding to Example 2.

  In Example 1, a battery was produced and evaluated in the same manner as in Example 1 except that a reactive organosilicon compound represented by the following (Formula 11) was used instead of (Formula 9). The results are shown in Table 1.

In this example, when a transmission infrared absorption spectrum was measured, stretching vibration of Si—O was confirmed near 1115 cm ⁻¹ , and it was confirmed that a covalent bond was formed.

  100 g of natural graphite as a negative electrode active material was dispersed in 500 ml of 30% hydrogen peroxide and stirred for 10 hours. The active material washed with pure water and filtered was dried in a vacuum atmosphere at 120 ° C. for 5 hours.

  20 g of the obtained active material was dispersed in 60 ml of xylene, and 0.2 g of a reactive organosilicon compound represented by the following (formula 12) was added dropwise with stirring. After stirring at room temperature for 1 hour, the filtered solid was washed 5 times with ethanol and dried in a vacuum atmosphere at 60 ° C. for 12 hours to obtain a carbon composite material coated with a reactive organosilicon compound.

When the transmission infrared absorption spectrum of the carbon composite particles treated with the organosilicon compound represented by (Formula 12) was measured, the stretching vibration of Si—O was confirmed in the vicinity of 1115 cm ⁻¹ , and a covalent bond was formed. Confirmed that.

  10 g of the obtained active material was dispersed in 30 ml of a water: ethanol mixed solvent (volume ratio 1: 9), and 0.1 g of the reactive organosilicon compound represented by (formula 9) was added dropwise with stirring. After stirring at room temperature for 1 hour, the filtered solid is washed 5 times with ethanol, dried in a vacuum atmosphere at 60 ° C. for 12 hours, sized with a sieve having a mesh pore of 50 μm, and reacted with a reactive organosilicon compound. A coated carbon composite material was obtained.

In this example, when a transmission infrared absorption spectrum was measured, stretching vibration of Si—O was confirmed near 1115 cm ⁻¹ , and it was confirmed that a covalent bond was formed. Using the above active material, a battery was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

  In Example 4, a battery was produced and evaluated in the same manner as in Example 4 except that the reactive organosilicon compound represented by (Formula 10) was used instead of (Formula 9). The results are shown in Table 1.

In this example, when a transmission infrared absorption spectrum was measured, stretching vibration of Si—O was confirmed near 1115 cm ⁻¹ , and it was confirmed that a covalent bond was formed. Using the above active material, a battery was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

  FIG. 3 shows a schematic diagram of the binding between the negative electrode active material and the coating material corresponding to Example 5. In FIG. 3, a first coating layer corresponding to (Equation 12) is formed on the surface of the carbon particles, and a second coating layer corresponding to (Equation 10) is formed on the surface of the first coating layer. In other words, two types of (Formula 10) and (Formula 12) are used as the coating agent.

  In Example 4, a battery was produced and evaluated in the same manner as in Example 4 except that the reactive organosilicon compound represented by (Formula 11) was used instead of (Formula 9). The results are shown in Table 1.

In this example, when a transmission infrared absorption spectrum was measured, stretching vibration of Si—O was confirmed near 1115 cm ⁻¹ , and it was confirmed that a covalent bond was formed. Using the above active material, a battery was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

  In Example 1, a battery was produced and evaluated in the same manner as in Example 1 except that the oxidation treatment time was 5 hours.

  In Example 1, a battery was produced and evaluated in the same manner as in Example 1 except that the oxidation treatment time was 20 hours.

  In Example 1, a battery was produced and evaluated in the same manner as in Example 1 except that artificial graphite was used.

  In Example 1, a battery was produced and evaluated in the same manner as in Example 1 except that (Equation 13) was used instead of (Equation 9).

  In Example 1, a battery was produced and evaluated in the same manner as in Example 1 except that (Expression 14) was used instead of (Expression 9).

  In Example 11, a battery was produced and evaluated in the same manner as in Example 11 except that the coating material concentration was 0.08%.

  In Example 11, a battery was produced and evaluated in the same manner as in Example 11 except that the coating material concentration was 0.5%.

  In Example 11, a battery was produced and evaluated in the same manner as in Example 11 except that the coating material concentration was 0.8%.

[Comparative Example 1]
In Example 1, a battery was prepared and evaluated in the same manner as in Example 1 except that an active material that was not subjected to oxidation treatment or coating treatment was used. The results are shown in Table 1.

[Comparative Example 2]
In Example 1, the battery was fabricated and evaluated in the same manner as in Example 1 except that the oxidation treatment time of the active material was changed to 1 hour and an active material that was not subjected to coating treatment was used. The results are shown in Table 1.

[Comparative Example 3]
In Example 1, the battery was fabricated and evaluated in the same manner as in Example 1 except that the oxidation treatment time of the active material was changed to 5 hours and an active material that was not subjected to coating treatment was used. The results are shown in Table 1.

[Comparative Example 4]
In Example 1, the battery was fabricated and evaluated in the same manner as in Example 1 except that the active material oxidation treatment time was changed to 20 hours and an active material that was not subjected to coating treatment was used. The results are shown in Table 1.

[Comparative Example 5]
In Example 1, a battery was produced and evaluated in the same manner as in Example 1 except that the oxidation treatment time was 1 hour.

[Comparative Example 6]
In Comparative Example 1, a battery was prepared and evaluated in the same manner as in Comparative Example 1 except that artificial graphite was used as the negative electrode active material.

[Comparative Example 7]
In Comparative Example 5, a battery was prepared and evaluated in the same manner as in Comparative Example 5 except that artificial graphite was used as the negative electrode active material.

<Discussion>
The batteries described in Examples 1 to 8, in which the negative active material was oxidized and then coated with a reactive organosilicon compound, were compared to the battery described in Comparative Example 1 that was not subjected to oxidation and coating. It can be seen that the capacity deterioration is small.

  In Comparative Examples 2 to 4 where only the oxidation treatment is performed, the initial charge / discharge efficiency is reduced. This is presumably because the oxygen-containing functional group inserted on the active material surface is reduced and decomposed on the negative electrode surface during charging, causing irreversible capacity.

  Moreover, in the comparative example 5 which performed oxidation treatment for 1 hour, it turns out that the value of O / C ratio is not enough with 1.23. From this, it can be seen that in the present experimental environment, the oxidation treatment is preferably performed for 2 to 3 hours or more, and the value of the O / C ratio is preferably 2.5 or more. It is considered that the time can be shortened by an efficient oxidation treatment.

  After the oxidation treatment, Examples 4 to 6 in which the treatment with the reactive organosilicon compound represented by (Formula 12) and the coating treatment with (Formula 9) to (Formula 11) are performed are the best charge / discharge The characteristics are shown. By pretreating with (Formula 12) to form the first coating layer, the reaction site with the reactive organosilicon compound increases, and the second coating layer made of the reactive organosilicon compound increases. Seem.

  Examples 1-8 and Comparative Examples 1-5 are comparisons when natural graphite is used as the negative electrode active material, but in comparison between Example 9 and Comparative Examples 6-7 using artificial graphite as the negative electrode active material. Also, the same tendency as in the case of using natural graphite as the negative electrode active material was observed.

  Examples 12 to 14 are examples in which the concentration of the coating material was changed to 0.08, 0.5, and 0.8 wt%. The capacity retention rate increased by increasing the concentration of the coating material from 0.08 wt% to 0.5 wt% (Table 1). However, the capacity retention rate at 0.8 wt% was lower than that at 0.5 wt%.

  Examples 10, 1, and 11 are examples using the covering materials represented by Formula 13, Formula 9, and Formula 14, respectively. In Formula 13, Formula 9, and Formula 14, the carbon number of the carbon chain bonded to the Si element is 6, 12, and 18, respectively. It was found that the capacity retention rate increased with increasing carbon number.

DESCRIPTION OF SYMBOLS 10 Positive electrode 11 Separator 12 Negative electrode 13 Battery can 14 Positive electrode tab 15 Negative electrode tab 16 Inner cover 17 Internal pressure release valve 18 Gasket 19 PTC element 20 Battery cover 21 Axle core

Claims (15)

A negative electrode active material;
A negative electrode material for a lithium ion secondary battery having a coating formed on the surface of the negative electrode active material,
The coating agent is bound to the negative electrode active material,
The coating agent is at least one compound represented by the following (formula 1):
The negative electrode active material contains a carbon element and an oxygen element,
The negative electrode material for a lithium ion secondary battery, wherein the ratio of the carbon element concentration to the oxygen element concentration (O / C ratio) of the negative electrode active material determined by XPS measurement is 2.5 or more.

(In (Formula 1), R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are functional groups containing at least one of carbon, oxygen, nitrogen, silicon and phosphorus. R ₁₁ , R ₁₂ , R ₁₃ , At least one of R ₁₄ is a linking group that binds to the negative electrode active material.) In claim 1,
The bonding group is a negative electrode material for a lithium ion secondary battery that is any one or more of (Formula 2), (Formula 3), and (Formula 4).

(In (Formula 2), R < ₂₁ > is a C1-C18 alkyl group.
In (Formula 3), R ₃₁ is a halogen element or an alkyl halide having 1 to 18 carbon atoms.
In (Formula 4), R ₄₁ , R ₄₂ , and R ₄₃ are functional groups composed of at least one of carbon, oxygen, nitrogen, silicon, and phosphorus elements. ) In claim 1 or 2,
R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₄₁ , R ₄₂ and R ₄₃ are a hydrogen group, an alkyl group having 1 to 18 carbon atoms, a hydroxyl group, a phenyl group, a polyalkylene oxide group, a polysiloxane group, an alkyl group. A negative electrode material for a lithium ion secondary battery, which is a group, a polyphosphazene group, or one or more of the above bonding groups. In any of claims 1 to 3,
The negative electrode material for a lithium ion secondary battery, wherein the O / C ratio is 2.5 or more and 30 or less. In claim 4,
The negative electrode material for a lithium ion secondary battery, wherein the O / C ratio is 4.0 or more and 7.0 or less. In any one of Claims 1 thru | or 5,
The said covering material is a lithium ion secondary battery made to react 0.1 weight% or more and 0.8 weight% or less with respect to the said negative electrode active material. In any of claims 2 to 6,
R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₄₁ , R ₄₂ , and R ₄₃ are either (Formula 5), (Formula 6), (Formula 7), (Formula 8), or any of the above-mentioned linking groups. A negative electrode material for a lithium ion secondary battery.

In (Equation _{(5), R 51, R 52} , R 53 is hydrogen or an alkyl group having 1 to 18 carbon atoms, n represents 100 or less 1 or more.
In (Formula 6), R ₆₁ is hydrogen or an alkyl group having 1 to 18 carbon atoms, and m is 1 or more and 100 or less.
In (Formula 7), R ₇₁ is hydrogen or an alkyl group having 1 to 18 carbon atoms, and m is 1 or more and 100 or less.
In (Formula 8), R ₈₁ , R ₈₂ , and R ₈₃ are hydrogen or an alkyl group having 1 to 18 carbon atoms, and 1 is 1 or more and 100 or less. ) In any one of Claims 1 thru | or 7,
The negative electrode active material is a negative electrode material for a lithium ion secondary battery, which is natural graphite. In any of claims 1 to 8,
The negative electrode active material is a negative electrode material for a lithium ion secondary battery that has been oxidized. In any one of Claim 1 thru | or 9,
The ratio of the silicon element concentration to the carbon element concentration (Si / C ratio) on the surface of the negative electrode material for a lithium ion secondary battery determined by XPS measurement is 0.1% or more and 10% or less. Negative electrode material. In any one of Claims 1 thru | or 10,
The said coating agent is a negative electrode material for lithium ion secondary batteries which is any one or more of (Formula 9), (Formula 10), (Formula 11), (Formula 12), (Formula 13), and (Formula 14).

In claim 11,
The said coating agent is a negative electrode material for lithium ion secondary batteries which is any 2 or more types of (Formula 9), (Formula 10), (Formula 11), (Formula 12), (Formula 13), (Formula 14) .   The negative electrode for lithium ion secondary batteries which has the negative electrode material for lithium ion secondary batteries in any one of Claims 1 thru | or 12.   The lithium ion secondary battery which has a negative electrode for lithium ion secondary batteries of Claim 13. A method for producing a negative electrode material for a lithium ion secondary battery, comprising: a negative electrode active material; and a coating formed on a surface of the negative electrode active material,
The coating agent is bound to the negative electrode active material,
The coating agent is at least one compound represented by the following (formula 1):
The said negative electrode active material is a manufacturing method of the negative electrode material for lithium ion secondary batteries which is oxidized by the oxidation process process for 2 hours or more.

(In (Formula 1), R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are functional groups containing at least one of carbon, oxygen, nitrogen, silicon and phosphorus. R ₁₁ , R ₁₂ , R ₁₃ , At least one of R ₁₄ is a linking group that binds to the negative electrode active material.)

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