Composite carbonaceous conductive material, positive electrode, non-aqueous electrolyte rechargeable battery, solid rechargeable battery, and method for preparing composite carbonaceous conductive material

Abstract

Provided are a composite carbonaceous conductive material, a positive electrode, a non-aqueous electrolyte rechargeable battery, a solid rechargeable battery, and a method of preparing the composite carbonaceous conductive material, the carbonaceous conductive material including a carbon nanotube and a coating layer on a surface of the carbon nanotube, the coating layer including a nitrogen element (N), a boron element (B), and an oxygen element (O). The weight ratio (B / N ratio) of the content (e.g., amount) of elemental boron (B) to the content (e.g., amount) of elemental nitrogen (N) in the coating is greater than or equal to about 0.7 and less than or equal to about 1.3 based on the total 100 wt% of the composite carbonaceous conductive material, and the content (e.g., amount) of elemental boron (B) in the coating is greater than or equal to about 1.0 wt% and less than or equal to about 21 wt%.

Description

Technical Field

[0001] According to one or more embodiments, the present disclosure relates to a composite carbonaceous conductive material and a non-aqueous electrolyte rechargeable battery. Background Art

[0002] Non-aqueous electrolyte rechargeable batteries, including rechargeable lithium-ion batteries, are widely used as power sources for smartphones, laptop computers, and the like. Recently, non-aqueous electrolyte rechargeable batteries have been developed for large-scale applications, such as in automobiles. These batteries (e.g., automotive batteries) are now designed for higher capacity and output, requiring higher voltages.

[0003] A positive electrode for a rechargeable lithium ion battery contains a positive electrode active material as a main component, and contains a carbonaceous conductive material such as carbon nanotubes to enhance electron conductivity and the like.

[0004] In high-voltage batteries, the positive electrode is at a high potential and exposed to a strong oxidizing environment. If the carbonaceous conductive material in the positive electrode is placed in this high-potential environment, it may degrade or undergo undesirable side reactions (for example, with the non-aqueous electrolyte in rechargeable lithium-ion batteries), generating oxidation currents that do not contribute to battery performance, thereby degrading overall battery performance.

[0005] Therefore, as described in Japanese Patent Publication No. 2004-099355 (Patent Document 1) and / or Japanese Patent Publication No. 2023-155562 (Patent Document 2), in order to suppress or reduce degradation or side reactions of the carbonaceous conductive material, a method involving a coating layer covering the surface of the carbonaceous conductive material is being considered. The entire contents of each of Patent Document 1 and Patent Document 2 are incorporated herein by reference.

[0006] The information disclosed in this Background section is provided to enhance understanding of the background of the disclosure and may contain information that does not constitute prior art. Summary of the Invention

[0007] However, the methods described in Patent Documents 1 or 2 may not be able to sufficiently suppress or reduce degradation and side reactions of the carbonaceous conductive material, particularly in a high voltage environment, which refers to a voltage exceeding about 4.5V or even about 5.0V, for example.

[0008] Aspects of the present disclosure have been made in consideration of the above-mentioned difficulties or problems, and aim to provide a carbonaceous conductive material capable of substantially suppressing or reducing degradation and / or undesirable side reactions in a high-voltage environment. This is intended to substantially suppress or reduce the generation of oxidation current even when the positive electrode of a high-voltage battery is in a high-potential state and exposed to a strongly oxidizing environment.

[0009] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the disclosed presented embodiments.

[0010] One or more embodiments of the present disclosure include a composite carbonaceous conductive material including carbon nanotubes and a coating on the surface of the carbon nanotubes, The coating includes nitrogen (N), boron (B) and oxygen (O). A weight ratio (B / N ratio) of the content (eg, amount) of the boron element (B) to the content (eg, amount) of the nitrogen element (N) in the coating layer may be greater than or equal to about 0.7 and less than or equal to about 1.3, and The content (eg, amount) of the boron element (B) in the coating layer may be greater than or equal to about 1.0 wt % and less than or equal to about 21 wt % based on 100 wt % of the total amount of the composite carbonaceous conductive material.

[0011] In one or more embodiments, the total (sum) content (e.g., amount) of nitrogen element (N) and boron element (B) contained in the coating layer may be greater than or equal to about 2.0 wt % and less than or equal to about 50.0 wt % based on 100 wt % of the total amount of the composite carbonaceous conductive material.

[0012] In one or more embodiments, the coating may include boron nitride.

[0013] In one or more embodiments, the coating may include boron (B) in an amount greater than or equal to about 2 wt % and less than or equal to about 15 wt % based on 100 wt % of the total amount of the composite carbonaceous conductive material.

[0014] In one or more embodiments, the coating may include boron (B) in an amount greater than about 3.6 wt % and less than or equal to about 10 wt % based on 100 wt % of the total amount of the composite carbonaceous conductive material.

[0015] In one or more embodiments, a ratio of the sum of the content (e.g., amount) of the boron element (B) and the content (e.g., amount) of the nitrogen element (N) to the content (e.g., amount) of the oxygen element (O) ((B+N) / O ratio) may be greater than or equal to about 0.5 and less than or equal to about 8.0.

[0016] In one or more embodiments, the coating may have a thickness greater than or equal to about 0.3 nanometers (nm) and less than or equal to about 20 nm.

[0017] One or more embodiments of the present disclosure include a positive electrode for a rechargeable battery, the positive electrode including a positive electrode active material and a conductive material, The conductive material is the composite carbonaceous conductive material described herein.

[0018] In one or more embodiments, the positive electrode may include a sulfide solid electrolyte.

[0019] One or more embodiments of the present invention include a nonaqueous electrolyte rechargeable battery comprising a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte, Here, the positive electrode is the positive electrode described herein.

[0020] In one or more embodiments, the non-aqueous electrolyte rechargeable battery can be charged and discharged at a voltage greater than about 4.5 volts (V).

[0021] One or more embodiments of the present disclosure include a solid rechargeable battery comprising a positive electrode, a negative electrode, and a solid electrolyte layer, Here, the positive electrode is the positive electrode described herein.

[0022] In one or more embodiments, the solid electrolyte layer includes a sulfide solid electrolyte.

[0023] In one or more embodiments, the solid rechargeable battery can be charged and discharged at voltages greater than about 4.5V.

[0024] One or more embodiments of the present disclosure include a method for preparing a composite carbonaceous conductive material, the method comprising providing carbon nanotubes and a precursor layer comprising boron oxide, the boron oxide covering at least a portion of a surface of the carbon nanotube, for example, a precursor layer formation process, in which the precursor layer is formed to cover a portion or the entire surface of the carbon nanotube. The method further comprises nitriding the boron oxide to form the precursor layer into a coating, the coating comprising boron (B) and nitrogen (N), for example, a nitriding process, in which the boron oxide forming the precursor layer is nitrided to form the precursor layer into a coating comprising boron and nitrogen.

[0025] In one or more embodiments, the weight ratio of the content (e.g., amount) of the boron element (B) to the content (e.g., amount) of the nitrogen element (N) in the coating (B / N ratio) may be greater than or equal to about 0.7 and less than or equal to about 1.3, and based on the total amount 100wt% of the composite carbonaceous conductive material, the content (e.g., amount) of the boron element (B) in the coating may be greater than or equal to about 1.0wt% and less than or equal to about 21wt%.

[0026] In one or more embodiments, the step of providing the precursor layer may include: immersing at least one surface of the carbon nanotube in a solution including the boron element (B); or coating the solution including the boron element (B) on at least one surface of the carbon nanotube. For example, the precursor layer formation process may include immersing the surface of the carbon nanotube in a solution including the boron element (B), or coating the surface of the carbon nanotube with the solution including the boron element (B).

[0027] In one or more embodiments, the coating may include boron nitride.

[0028] In one or more embodiments, the coating may have a thickness greater than or equal to about 0.3 nm and less than or equal to about 20 nm.

[0029] One or more embodiments of the present disclosure include a composite carbonaceous conductive material comprising carbon nanotubes and a coating on the surface of the carbon nanotubes. The coating includes nitrogen (N), boron (B), and oxygen (O). The weight ratio of boron to nitrogen (B / N ratio) in the coating is between about 0.7 and about 1.3, and the boron content is between about 1.0 wt% and about 21 wt% of the total composite carbonaceous conductive material.

[0030] In some embodiments, the total amount of nitrogen and boron in the coating is between about 2.0 wt% and about 50.0 wt% of the composite carbonaceous conductive material. The coating may include boron nitride. The boron content of the coating may be in the range of about 2 wt% to about 15 wt% or about 3.6 wt% to about 10 wt% of the composite carbonaceous conductive material. Additionally, the ratio of the sum of boron and nitrogen to oxygen ((B+N) / O ratio) is between about 0.5 and about 8.0, and the coating thickness is between about 0.3 nm and about 20 nm.

[0031] The disclosure also includes a positive electrode for a rechargeable battery, the positive electrode comprising a positive electrode active material and a composite carbonaceous conductive material. The positive electrode may also comprise a sulfide solid electrolyte. A non-aqueous electrolyte rechargeable battery is described, comprising a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte, wherein the positive electrode is the positive electrode described herein. The battery can be charged and discharged at a voltage greater than about 4.5V.

[0032] Furthermore, a solid rechargeable battery comprising a positive electrode, a negative electrode, and a solid electrolyte layer is disclosed, wherein the positive electrode is as described, the solid electrolyte layer may comprise a sulfide solid electrolyte, and the battery can be charged and discharged at a voltage greater than about 4.5V.

[0033] A method for preparing a composite carbonaceous conductive material is also provided. The method includes forming a boron oxide precursor layer on carbon nanotubes and then nitriding the boron oxide to form a coating comprising boron and nitrogen. The coating has a boron to nitrogen weight ratio (B / N ratio) between about 0.7 and about 1.3, and a boron content between about 1.0 wt% and about 21 wt% of the composite carbonaceous conductive material.

[0034] The precursor layer can be formed by immersing the carbon nanotubes in a solution containing boron or by coating the solution on the surface of the carbon nanotubes. The coating layer can include boron nitride and its thickness can be in the range of about 0.3 nm to about 20 nm.

[0035] According to the present disclosure, the composite carbonaceous conductive material can effectively inhibit or reduce degradation and side reactions in a high voltage environment, thereby improving battery performance.

[0036] According to the present disclosure, even when the positive electrode of a high-voltage battery is in a high-potential state and exposed to a strong oxidizing environment, a carbonaceous conductive material can be provided that can fully suppress or reduce the degradation and side reactions of the carbonaceous conductive material and fully suppress or reduce the generation of oxidation current under a high-voltage environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a schematic diagram illustrating a non-aqueous electrolyte rechargeable battery according to some example embodiments.

[0038] Figure 2 is a cross-sectional view of an all-solid-state rechargeable battery according to some example embodiments. DETAILED DESCRIPTION

[0039] In order to fully understand the structure and effect of the present disclosure, one or more embodiments will be described in more detail with reference to the accompanying drawings so that those skilled in the art can easily implement them. However, it should be noted that the present disclosure is not limited to the following example embodiments and can be implemented and embodied in many different forms and is not to be construed as being limited to the example embodiments set forth herein. On the contrary, the example embodiments are provided only to disclose the present disclosure and to fully inform those skilled in the art of the scope of the present disclosure.

[0040] The terms used herein are for describing the embodiments only and are not intended to limit the present disclosure.Unless the context clearly dictates otherwise, a singular expression includes a plural expression.

[0041] As used herein, "combinations thereof" refers to mixtures, laminates, composites, copolymers, alloys, blends, reaction products, and the like, of the components.

[0042] Here, it should be understood that terms such as "comprising," "including," "having," and / or variations thereof are intended to indicate the presence of a particular feature, number, step (e.g., action or task), element, and / or combination thereof (e.g., any suitable combination), but do not preclude the presence or addition of one or more other features, numbers, steps (e.g., actions or tasks), elements, and / or combinations thereof (e.g., any suitable combination). Additionally, the terms "comprising," "including," "having," or other similar terms encompass or support the terms "consisting of" and "consisting essentially of," indicating the presence of the recited features, integers, steps, operations, elements, and / or components, while the absence or substantial absence of other features, integers, steps, operations, elements, components, and / or groups thereof. Furthermore, in this context, "consisting essentially of" indicates that any additional components will not materially affect the chemical, physical, optical, or electrical properties of the semiconductor film.

[0043] It will be understood that although the terms "first," "second," "third," etc. may be used herein to describe one or more suitable elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Thus, a first element, first component, first region, first layer, or first part described herein may be referred to as a second element, second component, second region, second layer, or second part without departing from the teachings set forth herein.

[0044] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. If (for example, when) expressions such as "at least one of," "one of," and "selected from" precede or follow a list of elements, they modify the entire list of elements and do not modify the individual elements in the list. For example, the expressions "at least one of a through c," "at least one of a, b, or c," and "at least one of a, b, and / or c" can indicate only a, only b, only c, both a and b (e.g., simultaneously), both a and c (e.g., simultaneously), both b and c (e.g., simultaneously), all of a, b, and c, or variations thereof.

[0045] In the drawings, the thickness of layers, films, panels, regions, etc., is exaggerated for clarity, and like reference numerals denote like elements throughout, and their repeated description may not be provided in the specification. It will be understood that if (for example, when) an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element, or intervening elements may be present. In contrast, if (for example, when) an element is referred to as being "directly on" another element, there are no intervening elements present.

[0046] In some embodiments, the “layer” herein includes not only a shape formed on the entire surface if (for example, when) viewed from a plan view, but also a shape formed on a partial surface.

[0047] Here, unless otherwise specifically stated, the phrase "A or B" should not be interpreted as having an exclusive meaning. For example, the phrase "A or B" may mean "A but not B", "B but not A", and "A and B", etc.

[0048] The term "metal" is interpreted as a concept that includes common metals, transition metals, and metalloids (semimetals).

[0049] Spatially relative terms such as “under,” “beneath,” “lower,” “above,” “upper,” etc. may be used herein to easily describe the relationship of one element or feature to another. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the drawings. For example, if (e.g., when) the device in the drawings is turned over, an element described as “under” or “beneath” other elements or features would be oriented “above” the other elements or features. Thus, the example term “under” can encompass both (e.g., simultaneously) above and below orientations. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative terms used herein may be interpreted accordingly.

[0050] The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present disclosure. Unless otherwise defined, all terms used herein (including chemical, technical, and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. It will also be understood that terms (such as those defined in common dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present disclosure, and should not be interpreted in an idealized or overly formal sense.

[0051] Example embodiments are described herein with reference to cross-sectional illustrations that are schematic representations of idealized embodiments. As such, variations from the illustrated shapes due to, for example, manufacturing techniques and / or tolerances are to be expected. Therefore, the embodiments described herein should not be construed as limited to the specific shapes of regions as illustrated, but rather include deviations in shape due to, for example, manufacturing. For example, a region illustrated or described as flat may typically have rough and / or nonlinear features. Furthermore, sharp angles illustrated may be rounded (rounded). Accordingly, the regions illustrated in the drawings are schematic in nature, and their shapes are not intended to illustrate the precise shape of the region and are not intended to limit the scope of the presented claims.

[0052] The term "may" will be understood to refer to "one or more embodiments of the present disclosure," some of which include the described elements, and some of which exclude the elements and / or include optional elements. Similarly, optional language such as "or" refers to "one or more embodiments of the present disclosure," each of which includes the corresponding listed items.

[0053] In the context of this application and unless defined otherwise, the term "use" and variations thereof may be considered synonymous with the term "utilize" or variations thereof, respectively.

[0054] Hereinafter, one or more embodiments of a rechargeable battery are described.

[0055] 1. Basic structure of rechargeable battery A rechargeable battery according to some example embodiments may be a rechargeable lithium ion battery including a positive electrode, a negative electrode, a separator, a non-aqueous electrolyte, and a case accommodating the same therein.

[0056] The shape of the rechargeable lithium ion battery is not particularly limited, but may be any shape such as a cylinder, a square, a laminate, or a button.

[0057] In the following, reference is made to Figure 1 A non-aqueous electrolyte rechargeable battery according to some example embodiments is described.

[0058] Figure 1 is a schematic diagram illustrating a non-aqueous electrolyte rechargeable battery according to some example embodiments.

[0059] Reference Figure 1A rechargeable lithium battery 100 according to some example embodiments includes a battery cell including a positive electrode 114, a negative electrode 112 opposite to (e.g., facing) the positive electrode 114, a separator 113 between the positive electrode 114 and the negative electrode 112, an electrolyte for a rechargeable lithium battery impregnating the positive electrode 114, the negative electrode 112, and the separator 113, a battery case 120 accommodating the battery cell, and a sealing member 140 sealing the battery case 120.

[0060] The rechargeable battery according to some example embodiments may be an all-solid-state rechargeable battery including a positive electrode, a negative electrode, and a solid electrolyte layer between the positive and negative electrodes. The all-solid-state rechargeable battery may also be referred to as an all-solid-state battery or an all-solid-state rechargeable lithium battery.

[0061] Figure 2 is a cross-sectional view of an all-solid-state rechargeable battery according to some example embodiments. Figure 2 The all-solid-state rechargeable battery 200 may have a structure in which an electrode assembly is housed in a case such as a pouch, in which a negative electrode 220 including a negative electrode current collector 221 and a negative electrode active material layer 223, a solid electrolyte layer 230, and a positive electrode 210 including a positive electrode active material layer 213 and a positive electrode current collector 211 are stacked. The all-solid-state rechargeable battery 100 may further include an elastic layer 250 on the outside of at least one of the positive electrode 210 and the negative electrode 220. Figure 2 One electrode assembly including the negative electrode 220 , the solid electrolyte layer 230 , and the positive electrode 210 is shown, but an all-solid-state battery may be manufactured by stacking two or more electrode assemblies.

[0062] 1-1. Positive electrode The positive electrode may include a positive electrode current collector and a positive electrode mixed layer formed on the positive electrode current collector.

[0063] The positive electrode current collector may be any conductor that is an electrical (electronic) conductor and may be, for example, plate-shaped and / or film-shaped. In one or more embodiments, the positive electrode current collector may be made of aluminum, stainless steel, nickel-plated steel, or the like.

[0064] The positive electrode mixed layer may include a positive electrode active material, and may further include a conductive agent (electrical conductor) and a positive electrode binder.

[0065] The positive electrode active material may be, for example, a transition metal oxide and / or solid solution oxide including (e.g., containing) lithium, and is not particularly limited as long as it is a material capable of electrochemically intercalating and deintercalating lithium ions. The shape of the positive electrode active material is not particularly limited and may be in the form of particles.

[0066] Examples of lithium-containing transition metal oxides may include Li 1.0 Ni 0.88 Co 0.1 Al 0.01 Mg 0.0102 In some embodiments, the lithium-containing transition metal oxide may include Li·Co composite oxides (such as LiCoO2), Li·Ni·Co-Mn composite oxides (such as LiNi x Co y Mn z O2, etc.), Li-Ni composite oxides (such as LiNiO2, etc.) or Li-Mn composite oxides (such as LiMn2O4, etc.). Examples of solid solution oxides may include Li a Mn x Co y Ni z O2 (1.150≤a≤1.430, 0.45≤x≤0.6, 0.10≤y≤0.15, 0.20≤z≤0.28), LiMn 1.5 Ni 0.5 O4, etc. The content (e.g., amount) (content (e.g., amount) ratio) of the positive electrode active material is not particularly limited, and any content (e.g., amount) applicable to the positive electrode mixed layer of a non-aqueous electrolyte rechargeable battery is sufficient. Furthermore, these compounds may be used alone, or a plurality of types (species) may be mixed and used.

[0067] The positive electrode mixture layer according to the present embodiment includes, as a conductive material, a composite carbonaceous conductive material described in more detail later.

[0068] Examples of the conductive material may include at least one selected from carbon black, natural graphite, artificial graphite, fibrous carbon, and flaky carbon, in addition to the composite carbonaceous conductive material described in more detail.

[0069] Examples of carbon black may include furnace black, channel black, thermal black, Ketjen black, and acetylene black.

[0070] Examples of the fibrous carbon include carbon nanotubes, carbon nanofibers, and the like, and examples of the flaky carbon may include graphene and the like.

[0071] The content (e.g., amount) of the conductive material in the positive electrode mixed layer is not particularly limited, but from the viewpoint of achieving (e.g., simultaneously) both conductivity and battery capacity, the content (e.g., amount) of the conductive material may be greater than or equal to about 0.005 wt % and less than or equal to about 5 wt %, greater than or equal to about 0.1 wt % and less than or equal to about 3 wt %, and greater than or equal to about 0.1 wt % and less than or equal to about 2 wt %, based on the total weight of the positive electrode mixed layer.

[0072] If (for example, when) the positive electrode includes a plurality of types (kinds) of conductive materials, the content (for example, amount) of the conductive material is the total content (for example, amount) of the plurality of types (kinds) of conductive materials.

[0073] Examples of the positive electrode binder may include fluorine-containing resins (such as polyvinylidene fluoride), ethylene-containing resins (such as styrene-butadiene rubber and ethylene-propylene-diene terpolymer), acrylonitrile-butadiene rubber, fluororubber, polyvinyl acetate, polymethyl methacrylate, polyethylene, polyvinyl alcohol, carboxymethyl cellulose or a carboxymethyl cellulose derivative (such as a salt of carboxymethyl cellulose), or nitrocellulose.

[0074] The positive electrode binder may be any binder capable of bonding the positive electrode current collector and the conductive material on the positive electrode current collector, and is not particularly limited.

[0075] 1-2. Negative electrode The negative electrode includes a negative electrode current collector and a negative electrode mixed layer formed on the negative electrode current collector.

[0076] The negative electrode current collector may be any conductor that is an electrical conductor, and may be, for example, plate-shaped and / or film-shaped, and may include (consist of) copper, stainless steel, nickel-plated steel, or the like.

[0077] The negative electrode mixed layer includes a negative electrode active material, and may additionally include a conductive material and a negative electrode binder.

[0078] The negative electrode active material is not particularly limited as long as it can electrochemically intercalate and deintercalate lithium ions, and examples thereof include graphite active materials (artificial graphite, natural graphite, a mixture of artificial graphite and natural graphite, natural graphite coated with artificial graphite, etc.), Si-based active materials or Sn-based active materials (for example, a mixture of particles of silicon (Si) or tin (Sn) or their oxides and a graphite active material, particles of silicon or tin, an alloy using silicon or tin as a matrix material), compounds of metallic lithium and metallic titanium oxides (such as Li4Ti5O 12 ), lithium nitride, etc.

[0079] As the negative electrode active material, one type (kind) among the aforementioned may be used, or two or more types (kinds) may be used in combination. In one or more embodiments, silicon oxide is composed of SiO x (0≤x≤2) represents.

[0080] The conductive material is not particularly limited as long as it serves to increase the conductivity of the cathode, and for example, substantially the same materials as those described for the positive electrode can be used.

[0081] The content (e.g., amount) of the conductive material in the negative electrode mixed layer is not particularly limited, but from the viewpoint of achieving (e.g., simultaneously) both conductivity and battery capacity, the content (e.g., amount) of the conductive material may be greater than or equal to about 0.005 wt % and less than or equal to about 5 wt % (e.g., greater than or equal to about 0.1 wt % and less than or equal to about 3 wt %) based on the total weight of the total negative electrode mixed layer. As the negative electrode binder, any binder capable of binding the negative electrode active material and the conductive material to the negative electrode current collector may be used without particular limitation.

[0082] The negative electrode binder may include, for example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), styrene butadiene copolymer (SBR), a metal salt of carboxymethyl cellulose (CMC), etc. One type (kind) of binder may be used alone, or two or more types (kinds) may be used.

[0083] 1-3. Diaphragm The separator is not particularly limited, and any separator can be used as long as it is used as a separator for a rechargeable lithium ion battery. The separator can be a porous film or nonwoven fabric having excellent or suitable high-rate discharge performance, which can be used alone or in combination with other materials.

[0084] Examples of the resin constituting the diaphragm may include polyolefin resins (such as polyethylene and polypropylene), polyester resins (such as polyethylene terephthalate and polybutylene terephthalate), polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-perfluorovinyl ether copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-vinyl fluoride copolymer, vinylidene fluoride-hexafluoroacetone copolymer, vinylidene fluoride-ethylene copolymer, vinylidene fluoride-propylene copolymer, vinylidene fluoride-vinylidene fluoride-trifluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-ethylene-tetrafluoroethylene copolymer or vinylidene fluoride-ethylene-tetrafluoroethylene copolymer.

[0085] In contrast, the porosity of the separator is not particularly limited, and may be any suitable porosity for a separator used in a rechargeable lithium ion battery.

[0086] The separator may further include a surface layer coating the surface of the aforementioned porous film or nonwoven fabric. The surface layer may include an adhesive for fixing the battery element by adhering to the electrode. Examples of adhesives may include vinylidene fluoride-hexafluoropropylene copolymers, acid-modified products of vinylidene fluoride polymers, and styrene-(meth)acrylate copolymers.

[0087] 1-4. Non-aqueous electrolyte For non-aqueous electrolytes, non-aqueous electrolytes conventionally used for rechargeable lithium ion batteries can be used without particular limitation. The non-aqueous electrolyte may have a composition in which an electrolyte salt is included (contained) in a non-aqueous solvent as a solvent of the electrolyte solution.

[0088] The non-aqueous solvent may include, for example, cyclic carbonates (such as propylene carbonate, ethylene carbonate, butylene carbonate, chloroethylene carbonate, fluoroethylene carbonate or vinylene carbonate), cyclic esters (such as γ-butyrolactone or γ-valerolactone), linear carbonates (such as dimethyl carbonate, diethyl carbonate or methyl ethyl carbonate), linear esters (such as methyl formate, methyl acetate, methyl butyrate, ethyl propionate or propyl propionate), ethers (such as tetrahydrofuran or its derivatives, 1,3-dioxane, 1,4-dioxane, 1,2-dimethane, 1,2-dimethoxyethane, 1,4-dibutoxyethane, methyl diglycol dimethyl ether, ethylene glycol monopropyl ether or propylene glycol monopropyl ether), nitriles (such as acetonitrile and benzonitrile), dioxolane or its derivatives, ethylene sulfide, sulfolane, sultone or its derivatives, and they may be used alone or as a mixture of two or more.

[0089] On the contrary, if (for example, when) two or more non-aqueous solvents are mixed and used, the mixing ratio of the various non-aqueous solvents may be a mixing ratio suitable for rechargeable lithium ion batteries.

[0090] Examples of the electrolyte salt may include inorganic ionic salts containing lithium (Li), sodium (Na) or potassium (K) (such as LiClO4, LiBF4, LiAsF6, LiPF6, LIPF 6-x (CnF 2n+1 ) x [provided that 1 < x < 6, n = 1 or 2], LiSCN, LiBr, LiI, Li2SO4, Li2B 10 Cl 10 , NaClO4, NaI, NaSCN, NaBr, KClO4, or KSCN) and organic ionic salts (such as LiCF3SO3, LiN(CF3SO2)2, LiN(C2F5SO2)2, LiN(CF3SO2)(C4F9SO2), LiC(CF3SO2)3, LiC(C2F5SO2)3, (CH3)4NBF4, (CH3)4NBr, (C2H5)4NClO4, (C2H5)4NI, (C3H7)4NBr, (n-C4H9)4NClO4, (n-C4H9)4NI, (C2H5)4N-maleate, (C2H5)4N-benzoate, (C2H5)4N-phthalate, lithium stearyl sulfate, lithium octyl sulfate or lithium dodecylbenzenesulfonate), and these ionic compounds may be used alone or as a mixture of two or more.

[0091] Rather, the concentration of the electrolyte salt may be substantially the same as that of the electrolyte salt in a non-aqueous electrolyte used in a suitable rechargeable lithium ion battery without particular limitation.

[0092] In one or more embodiments, the non-aqueous electrolyte may include the aforementioned lithium compound (electrolyte salt) at a concentration greater than or equal to about 0.8 molarity (M) and less than or equal to about 1.5M.

[0093] In one or more embodiments, one or more suitable additives may be added to the non-aqueous electrolyte.

[0094] Examples of such additives may include additives suitable for negative electrodes, additives suitable for positive electrodes, ester additives, carbonate additives, sulfate additives, phosphate additives, borate additives, acid anhydride additives, and electrolyte additives.

[0095] One kind of these may be added to the non-aqueous electrolyte, or a plurality of types (kinds) of additives may be added to the non-aqueous electrolyte.

[0096] 2. Characteristics of the non-aqueous electrolyte rechargeable battery according to this embodiment Hereinafter, the configuration of the nonaqueous electrolyte rechargeable battery according to the present embodiment is described.

[0097] The positive electrode mixed layer of the nonaqueous electrolyte rechargeable battery according to the present embodiment includes a composite carbon-based conductive material as a conductive material. For example, the composite carbon-based conductive material may be the only conductive material.

[0098] The composite carbonaceous conductive material includes carbon nanotubes and a coating on the surface of the carbon nanotubes. For example, the carbon nanotubes and the coating on the surface of the carbon nanotubes can be combined to form a whole.

[0099] There are no particular limitations on the carbon nanotubes, and one or more suitable types (species) can be used as long as they can be used as a conductive material in a rechargeable battery. For example, single-walled carbon nanotubes or multi-walled carbon nanotubes having a two-layer or more-layer structure can be used as the carbon nanotubes.

[0100] As carbon nanotubes included in the composite carbonaceous conductive material, commercially available products can be widely used. The outer diameter of the carbon nanotubes can be between about 0.4 nm and about 50 nm, as this range can enhance conductivity. Furthermore, the length of the carbon nanotubes can be between about 100 nm and about 5 mm (e.g., between about 1 μm and about 3 mm). Within this range, the formation of conductive paths in the positive electrode mixed layer can be enhanced or improved.

[0101] The coating layer may include nitrogen (N) and boron (B), and the weight ratio of the content (e.g., amount) of the boron (B) element to the content (e.g., amount) of the nitrogen (N) element in the coating layer (B / N ratio) may be greater than or equal to about 0.7 and less than or equal to about 1.3. The B / N weight ratio may be greater than or equal to about 0.7 and less than or equal to about 0.9 (e.g., greater than or equal to about 0.7 and less than or equal to about 0.85).

[0102] The coating layer may further include oxygen (O), and the weight ratio of the content (e.g., amount) of the boron (B) and nitrogen (N) elements to the content (e.g., amount) of the oxygen (O) element ((B+N) / O ratio) in the composite carbonaceous conductive material may be selected or adjusted to be greater than or equal to about 0.5 and less than or equal to about 8.0. The (B+N) / O weight ratio may be greater than or equal to about 0.7 and less than or equal to about 3.0 (e.g., greater than or equal to about 1.0 and less than or equal to about 2.5).

[0103] It is considered that if (eg, when) a coating layer of the composite carbonaceous conductive material according to the present embodiment is formed, oxygen elements may be derived from boric acid originally added to the carbon nanotubes.

[0104] Examples of such a coating may include, for example, a coating including boron nitride and, for example, a coating formed of chemically stable boron nitride.

[0105] The coating may be a single layer or a multilayer. For example, if (eg, when) the coating includes boron nitride, the boron nitride is believed to be in the energetically very stable form of hexagonal boron nitride (h-BN).

[0106] In one or more embodiments, h-BN may have a layered structure, for example, substantially similar to graphite or carbon nanotubes, and if (for example, when) the amount of boron nitride included in the coating is relatively large, the coating may have a multilayer structure due to the structure of the boron nitride.

[0107] The content (eg, amount) of the boron element (B) included in the coating layer may be greater than or equal to about 1.0 wt % and less than or equal to about 21 wt % based on 100 wt % of the total amount of the composite carbonaceous conductive material.

[0108] The content (e.g., amount) of the boron element (B) included in the coating layer may be greater than or equal to about 2.0 wt % and less than or equal to about 15 wt %, greater than or equal to about 2.5 wt % and less than or equal to about 15 wt %, greater than or equal to about 3.6 wt % and less than or equal to about 10 wt %, or greater than or equal to about 3.6 wt % and less than or equal to about 4.5 wt %, based on 100 wt % of the total amount of the composite carbonaceous conductive material.

[0109] The total content (eg, total amount) of boron element (B) and nitrogen element (N) contained in the coating layer may be greater than or equal to about 2 wt % and less than or equal to about 50 wt % based on 100 wt % of the total amount of the composite carbonaceous conductive material.

[0110] For example, if (e.g., when) the coating is formed of boron nitride alone as described herein, the total content (e.g., total amount) (e.g., sum) of boron element (B) and nitrogen element (N) contained in the coating can be greater than or equal to about 5.8 wt % and less than or equal to about 48 wt %, based on 100 wt % of the total amount of the composite carbonaceous conductive material.

[0111] The coating may have a thickness of greater than or equal to about 0.3 nm and less than or equal to about 20 nm, greater than or equal to about 0.3 nm and less than or equal to about 18 nm, greater than or equal to about 0.3 nm and less than or equal to about 17 nm, or greater than or equal to about 0.3 nm and less than or equal to about 10 nm.

[0112] In some embodiments, if (for example, when) the coating layer is formed of an insulating material such as boron nitride, the conductivity of the positive electrode mixed layer may be sufficiently maintained by setting the thickness of the coating layer to about 20 nm.

[0113] In some embodiments, by making the thickness of the coating layer 0.3 nm or more, it is possible to sufficiently exert the suppression or reduction of degradation of the carbon nanotubes or undesirable side reactions with other battery components (such as an electrolyte).

[0114] In one or more embodiments, a thickness of 0.3 nm may be substantially about the same as the thickness of a layer of h-BN, which is adapted to have a hexagonal crystal structure substantially the same as graphite.

[0115] If (eg, when) a coating is formed, the thickness of the coating can be controlled or selected, for example, by varying the amount of boric acid added to the carbon nanotubes.

[0116] The coating may be formed in an island shape on a portion of the surface of the carbon nanotube, but it is desirable to coat the entire surface of the carbon nanotube uniformly (eg, substantially uniformly) to such an extent that the carbon nanotube does not come into direct contact with the nonaqueous electrolyte or solid electrolyte.

[0117] It may be desirable to adjust the content (e.g., amount) of the composite carbonaceous conductive material in the positive electrode mixed layer so that the content (e.g., amount) of the entire conductive material is within the range of the total content (e.g., total amount) of the conductive material in the positive electrode mixed layer described herein. In one or more embodiments, from a manufacturing cost perspective, the content (e.g., amount) of the composite carbonaceous conductive material in the positive electrode mixed layer may be greater than or equal to about 0.005 wt % and less than or equal to about 3.0 wt % (e.g., greater than or equal to about 0.005 wt % and less than or equal to about 2.0 wt %).

[0118] 3. Method for manufacturing a non-aqueous electrolyte rechargeable battery Next, a method for manufacturing a nonaqueous electrolyte rechargeable battery according to the present embodiment is described.

[0119] 3-1. Method for preparing composite carbonaceous conductive material The composite carbonaceous conductive material can be prepared, for example, by a method comprising providing carbon nanotubes and a precursor layer containing boron oxide, wherein the boron oxide covers at least a portion of the surface of the carbon nanotubes (e.g., a precursor layer formation process in which a precursor layer of boron oxide is formed to cover a portion or the entire surface of the carbon nanotubes). In one or more embodiments, the boron oxide can cover a portion (e.g., a part) of the surface of the carbon nanotubes, or can cover the entire (e.g., all) surface of the carbon nanotubes.

[0120] The method includes providing nitridation to the boron oxide to form the precursor layer into a coating layer including boron element (B) and nitrogen element (N) (e.g., a nitridation process in which the boron oxide forming the precursor layer is subjected to nitridation to form the precursor layer into a coating layer including boron element (B) and nitrogen element (N)).

[0121] For example, a method for preparing a composite carbonaceous conductive material includes providing carbon nanotubes and a precursor layer containing boron oxide, wherein the boron oxide covers at least a portion of a surface of the carbon nanotubes; and nitriding the boron oxide to form a coating on the carbon nanotubes, wherein the coating contains boron (B) and nitrogen (N).

[0122] The method (eg, precursor layer formation process) may include, for example, immersing at least one surface (eg, on the surface) of the carbon nanotube in a solution including elemental boron (B), or coating a solution including elemental boron (B) on the surface of the carbon nanotube.

[0123] The carbon nanotubes attached to the surface of the solution in this manner can be dried, for example, by natural drying to form a precursor layer. The phrase "natural drying" may refer to a process that does not use heat, air flow, and / or vacuum.

[0124] In one or more embodiments, the solution containing the boron element (B) is not particularly limited, but examples thereof include compounds containing boron dissolved in an appropriate or suitable solvent. Examples of the compound containing boron include boric acid.

[0125] In some embodiments, as a solvent for dissolving boric acid, examples thereof include solvents that may volatilize by natural drying (such as ethanol), but it is certainly not limited to combinations thereof.

[0126] The precursor layer can be stably supported on the surface of the carbon nanotubes after, for example, natural drying as described above or heating in an inert gas atmosphere such as argon instead of natural drying.

[0127] The heating temperature and heating time thereof may be appropriately or suitably changed, but for example, it is desirable to heat at a temperature of about 200° C. or higher and about 600° C. or lower for about 5 minutes or higher and about 60 minutes or lower (for example, heating at about 300° C. or higher and about 500° C. or lower for about 15 minutes or higher and about 45 minutes or lower).

[0128] The precursor layer formed on the surface of the carbon nanotube in the manner described herein includes boron oxide, and thus a coating is formed by performing a nitridation process (eg, nitridation) to add nitride to the boron oxide.

[0129] The nitridation process may be performed by heating the precursor layer mentioned herein in an atmosphere including (contains) a gas such as an ammonia gas.

[0130] The heating temperature and heating time thereof may be appropriately or suitably changed, but for example, it is desirable to continue at a temperature of greater than or equal to about 800° C. and less than or equal to about 1500° C. for greater than or equal to about 5 minutes and less than or equal to about 90 minutes (for example, at greater than or equal to about 1000° C. and less than or equal to about 1200° C. for greater than or equal to about 15 minutes and less than or equal to about 60 minutes).

[0131] 3-2. Method for manufacturing positive electrode Make the positive electrode, for example, as follows: First, the composite carbonaceous conductive material manufactured as described herein, the positive electrode active material, and the positive electrode binder are mixed and dispersed in a positive electrode slurry solvent in a desired or appropriate ratio to form a positive electrode slurry.

[0132] Next, the positive electrode slurry is coated on a positive electrode current collector and dried to form a positive electrode mixed layer.

[0133] In some embodiments, the coating method is not particularly limited. The coating method can be, for example, a doctor blade coating method, a gravure coating method, a reverse roll coating method, or a slot die coating method. Each coating method can also be carried out by the same method.

[0134] Next, the positive electrode material mixed layer may be pressed to a desired or appropriate density using a press, thereby manufacturing a positive electrode.

[0135] 3-3. Method for manufacturing negative electrode The negative electrode can also be manufactured in essentially the same manner as the positive electrode.

[0136] First, a negative electrode slurry is prepared by dispersing a mixture of materials constituting a negative electrode mixture layer in a solvent for a negative electrode slurry.

[0137] Then, the negative electrode slurry is coated on a negative electrode current collector and dried to form a negative electrode mixed layer.

[0138] Subsequently, the negative electrode mixed layer is pressed to a desired or appropriate density using a pressing machine.

[0139] Thus, a negative electrode was manufactured.

[0140] 3-4. Method for manufacturing a non-aqueous electrolyte rechargeable battery Subsequently, an electrode structure is manufactured by sandwiching the separator between the positive electrode and the negative electrode.

[0141] The electrode structure is then processed into a desired or suitable shape (eg, cylindrical, prismatic, laminated, button-shaped, etc.) and inserted into a container of the described shape.

[0142] Then, by injecting a non-aqueous electrolyte into the container, the electrolyte is allowed to permeate into the pores in the separator and the gaps between the positive electrode and the negative electrode.

[0143] By means of the described process, rechargeable lithium-ion batteries can be manufactured.

[0144] 4. Effects of this embodiment According to the non-aqueous electrolyte rechargeable battery constructed as described herein, even when (for example, when) the positive electrode in a high-voltage battery is in a high-potential state and is placed in a strongly oxidizing environment, a composite carbonaceous conductive material, a positive electrode for a rechargeable battery, and a non-aqueous electrolyte rechargeable battery can be provided that can sufficiently suppress or reduce the degradation and side reactions of the carbonaceous conductive material in a high-voltage environment and sufficiently suppress or reduce the generation of oxidation current.

[0145] 5. Another embodiment of the present disclosure The present disclosure is not limited to the aforementioned embodiments.

[0146] In the aforementioned embodiments, the composite carbonaceous conductive material is included in the positive electrode mixture layer, but the composite carbonaceous conductive material according to some example embodiments may be included in another layer constituting a rechargeable battery (eg, a protective layer protecting the negative electrode mixture layer or the positive electrode mixture layer).

[0147] In some embodiments, in the aforementioned embodiments, the case of a non-aqueous electrolyte rechargeable battery having a separator and an electrolyte has been described as an example of a rechargeable battery, but the present disclosure is not limited thereto, and the composite carbonaceous conductive material according to the present disclosure can be widely used as a conductive material in a semi-solid battery having a gel-type (quasi) electrolyte, a solid battery having a solid electrolyte layer made of a sulfide solid electrolyte, etc., an all-solid-state battery that does not include an electrolyte at all, and the like.

[0148] Terms such as "substantially," "about," and "approximately" are used as relative terms rather than as terms of degree, and are intended to account for the inherent deviations in measured or calculated values that one of ordinary skill in the art would recognize. They may include the stated value and an acceptable range of deviation as determined by one of ordinary skill in the art, taking into account the limitations and errors associated with the measurement of that quantity. For example, "about" may refer to one or more standard deviations, or ±30%, ±20%, ±10%, ±5% of the stated value.

[0149] The numerical ranges disclosed herein include and are intended to disclose all subranges encompassed by the same numerical precision. For example, a range of "1.0 to 10.0" includes all subranges having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as 2.4 to 7.6. Applicants therefore reserve the right to amend this specification and claims to explicitly recite any subranges encompassed within the ranges explicitly recited herein.

[0150] In some embodiments, the present disclosure is not limited to these embodiments, and one or more suitable modifications are possible without departing from the scope of the present disclosure.

[0151] Example Hereinafter, the present disclosure will be described in more detail using specific examples. However, the following examples are merely examples of the present disclosure, and the present disclosure is not limited to the following examples.

[0152] In the following examples, first, composite carbonaceous conductive materials were produced having the properties shown in Table 1. Using these, nonaqueous electrolyte rechargeable batteries and solid rechargeable batteries were produced, and the generation of oxidation current was investigated for each of the produced batteries.

[0153] Preparation of composite carbonaceous conductive materials Example 1 First, 0.48 grams (g) of boric acid was dispersed in 10 milliliters (mL) of ethanol to prepare a boric acid-ethanol solution. Subsequently, 450 milligrams (mg) of multi-walled carbon nanotubes (MWCNTs) manufactured by Sigma-Aldrich Co., Ltd. were added to the boric acid-ethanol solution and then naturally dried at room temperature overnight while stirring to produce boric acid-loaded MWCNTs.

[0154] Next, the temperature was raised to 400 °C in an argon atmosphere in a tube electric furnace and then maintained for 30 min to prepare MWCNTs loaded with boron oxide.

[0155] The boron oxide-supported MWCNTs were then coated with boron nitride by nitriding (nitridation treatment) at 1100° C. for 40 minutes in a mixed gas having an ammonia / argon ratio (eg, amount) of 1:4 to produce a composite carbonaceous conductive material (A).

[0156] Example 2 10 mg of the MWCNT of Example 1 was dispersed in 140 mL of 2-propanol, filtered on a membrane filter, vacuum dried at 120° C., and then punched into a Φ11 mm circle (eg, a circle having a diameter of about 11 millimeters (mm)) to obtain a MWCNT membrane.

[0157] Subsequently, a self-supporting film-type (quasi) composite carbonaceous conductive material (B) was obtained in substantially the same manner as in Example 1, except that the MWCNT film was immersed in a boric acid aqueous solution prepared by dispersing 0.48 g of boric acid in 10 mL of water for 85 minutes to prepare a MWCNT film loaded with boric acid.

[0158] Example 3 A composite carbonaceous conductive material (C) was obtained in substantially the same manner as in Example 1, except that the content (eg, amount) of MWCNT was changed to 230 mg.

[0159] Example 4 A composite carbonaceous conductive material (D) was obtained in substantially the same manner as in Example 1, except that the content (eg, amount) of MWCNT was changed to 90.5 mg.

[0160] Comparative Example 1 The composite carbonaceous conductive material is uncoated multi-walled carbon nanotubes (MWCNTs).

[0161] Comparative Example 2 A composite carbonaceous conductive material (E) was obtained in substantially the same manner as in Example 1, except that the content (eg, amount) of MWCNT was changed to 22.7 mg.

[0162] Evaluation of composite carbonaceous conductive materials The composite carbonaceous conductive materials of Examples 1 to 4 and Comparative Examples 1 and 2 were evaluated as follows.

[0163] Elemental analysis Each of the composite carbonaceous conductive materials was quantitatively analyzed by measuring the amount of each boron and nitrogen according to JIS K0152:2014 using an X-ray photoelectron spectroscopy apparatus (XPS, ESCALAB 250Xi manufactured by Thermo Fisher Scientific).

[0164] As a result of quantitative analysis, it was confirmed that the coating layer of each composite carbonaceous conductive material included boron element, nitrogen element, and oxygen (composed of boron element, nitrogen element, and oxygen), and the content (e.g., amount) of the boron element, the content (e.g., amount) of the nitrogen element, the content (e.g., amount) of the oxygen element, and the total content (e.g., total amount) of the nitrogen element and the boron element in the composite carbonaceous conductive material are shown in Table 1.

[0165] In contrast, oxygen is contained in the carbon nanotubes as well as the coating, but nitrogen and boron are contained only in the coating.

[0166] In some embodiments, it was observed by XPS that in the coating, some of the constituent elements of the coating were chemically bonded between the carbon nanotubes to support them.

[0167] As an example of chemical bonds, in addition to the covalent bond (NC) between the nitrogen element constituting the coating and the carbon element constituting the CNT, based on information such as the ratio of the covalent bond between boron and oxygen (BO) and the covalent bond between oxygen and carbon (OC), it is inferred that the chemical bond includes a bond mediated by oxygen between boron and carbon (BOC).

[0168] Coating thickness measurement The coating thickness of each of the composite carbonaceous conductive materials was measured as follows.

[0169] First, images of the composite carbonaceous conductive material were taken by transmission electron microscopy (TEM), and elemental mapping images were taken by electron energy loss spectroscopy (EELS).

[0170] Here, a field emission type transmission electron microscope (JEM-ARM200F, JOEL Co., Ltd.) and an electron energy loss spectrometer (GIF QUANTUM ER, Gatan, Inc.) were used.

[0171] Among the composite carbonaceous conductive materials included in these TEM images, the thickness of the coating layer of the composite carbonaceous conductive material that can be identified from the transmission observation image and the element mapping image was measured at 10 locations, and the average value of these was regarded as the thickness of the coating layer.

[0172] Evaluation of Sheet Resistance As described herein, 5 mg of any of the types (species) of carbonaceous conductive materials according to Examples 1, 3, and 4, and Comparative Examples 1 and 2, was dispersed in 30 mL of an aqueous sodium dodecylbenzenesulfonate (SDBS) solution, and then suction filtered through a membrane filter. The carbonaceous conductive materials according to Example 1 and Comparative Example 1 were peeled from the membrane filter, vacuum-dried at 120°C, and cut into 11 mm Ø circular pieces to obtain self-supporting membranes.

[0173] The carbonaceous conductive materials according to Examples 3 and 4, as well as Comparative Example 2, were not removed from the membrane filters but were naturally dried at room temperature to prepare samples for sheet resistance measurement. The sheet resistance (e.g., surface resistivity) of these membrane samples and the membrane of Example 2 was measured using a four-probe method using a voltage-current generator (2400 Series Source Meter, Keithley Instruments, LLC) and compared. The results are shown in Table 1.

[0174] Evaluation of voltage resistance: Cyclic voltammetry (CV) measurements (1 and 2): Non-aqueous electrolyte Fabrication of positive electrode free-standing films for evaluation As described herein, 5 mg of any type (species) of carbonaceous conductive material (carbon nanotubes (MWCNTs) without coating) according to Example 1, Example 2, and Comparative Example 1 was dispersed in 30 mL of a 0.5 wt % SDBS aqueous solution, suction filtered on a membrane filter, vacuum dried at 120° C., and cut into a circular shape with a diameter of 11 mm to obtain a self-supporting film, which was used as a positive electrode for CV (1) evaluation.

[0175] Manufacturing of counter electrodes, electrolytes, and button cells for CV (1) A porous separator made of polypropylene and a counter electrode made of metallic lithium were cut into sizes suitable for button cells.

[0176] As shown in Table 1, each of coin cells (2032) of Examples 1 and 2 for CV (1) evaluation and Comparative Example 1 was manufactured by using an electrolyte prepared by dissolving 1.0 molar concentration (M) of LiPF6 in a mixed solvent of ethylene carbonate / diethyl carbonate at a volume ratio of 50 / 50, a positive electrode for CV evaluation, and the aforementioned separator and counter electrode.

[0177] Fabrication of electrolyte and button cell for CV (2) Each coin cell (2032) according to Example 2 and Comparative Example 1 for CV (2) evaluation shown in Table 1 was manufactured in substantially the same manner as in the CV (1) evaluation, except that an electrolyte prepared by dissolving 1.3 M LiPF6 in a mixed solvent of ethylene carbonate / propylene carbonate / ethyl propionate in a volume ratio of 10 / 15 / 75 and the self-supporting film of the composite carbonaceous conductive material of Example 2 were used as the positive electrode.

[0178] CV measurements 1 and 2 The current of each of the batteries of Examples 1 and 2 used in CV Evaluations 1 and 2, and Comparative Example 1, was measured by injecting oxidation-reduction potentials in the range of 3.0 V to 5.0 V (vs. Li) at 5 millivolts per minute (mV / min) using a VMP-3 potentiostat, a CV measurement device manufactured by BioLogic, to compare the current at 5 V. The results are shown in Table 1.

[0179] Evaluation of voltage resistance: Cyclic voltammetry (CV) measurement (3): Solid electrolyte Preparation of positive electrode pellets for evaluation Any one of the carbonaceous conductive materials of Example 3 and Comparative Example 1 was mixed with a sulfide solid electrolyte (Li6PS5Cl) at a solid weight ratio of 5:95 using a dry mixer (FM3 mixer manufactured by Nippon Coke & Engineering Co., Ltd.) at 2000 rpm for 3 minutes, and then made into pellets of 10 mm (Φ) × 0.1 mm (thickness) by using a powder molding press (Lan press, Labonect Co., Ltd.) under a pressure of 15 MPa, which were used as positive electrode pellets for CV (2) evaluation.

[0180] Preparation of diaphragm pellets for evaluation The sulfide solid electrolyte (Li6PS5Cl) was fabricated into pellets of 10 mm (Φ) × 0.5 mm (thickness) by using a powder molding machine under a pressure of 15 MPa to obtain soluble solid electrolyte layer pellets for CV evaluation.

[0181] Fabrication of CV (3) cells for evaluation The positive electrode pellets and solid electrolyte layer pellets for CV Evaluation 2 were used together with metallic lithium punched into a size of 10 mm Φ as a counter electrode, and then sequentially placed in a solid battery cell case (KP-Solid Battery, Hohsen Corp.) and pressed under a pressure of 20 megapascals (MPa) to produce the batteries of Example 3 for CV Evaluation 3 and Comparative Example 1 shown in Table 1.

[0182] CV measurement 3 The current of each of the batteries in Example 3 for CV Evaluation 3 and Comparative Example 1 was measured by injecting oxidation·reduction potentials in the range of 1.1 V to 6.0 V (vs. Li) at a scan rate of 5 mV / min using a CV measurement apparatus VMP-3 potentiostat manufactured by BioLogic to compare the current at 6 V.

[0183] For Example 1, Example 2, Example 3, Example 4, and Comparative Examples 1 and 2, the results are shown in Table 1 using the following headings: H1: Composite carbon conductive material H2: Boron content (wt%) H3: Nitrogen content (wt%) H4: oxygen content (wt%) H5: B / N weight ratio H6: Total amount of boron + nitrogen (wt%) H7: (B+N) / O weight ratio H8: coating thickness (nm) H9, H10, H11: Oxidation current density (mA / cm) from CV evaluations 1, 2, and 3, respectively 2 ) voltage resistance H12: Sheet resistance, in ohms / square (Ω / sq) Table 1

[0184] Thinking about Examples and Comparative Examples Referring to the results in Table 1, in Examples 1 to 3, the oxidation current was suppressed or reduced in both CV Evaluations 1 and 2 using liquid / non-aqueous electrolytes and in CV Evaluation 3 using a solid electrolyte, compared to Comparative Example 1 which does not contain boron nitride.

[0185] In some embodiments, the oxidation current density for non-aqueous electrolyte rechargeable batteries is about 1 mA / cm². 2 ) to about 1.5 mA / cm 2 or about 1.2 mA / cm 2 to about 1.5 mA / cm 2 .

[0186] In some embodiments, the sheet resistance (e.g., surface resistivity) of the non-aqueous electrolyte rechargeable battery is from about 5 ohms / square (Ω / sq) to about 130 Ω / sq, from about 5 Ω / sq to about 32 Ω / sq, from about 5 Ω / sq to about 15 Ω / sq, or from about 5 Ω / sq to about 7 Ω / sq.

[0187] This effect is likely due to the formation of a coating comprising an electrochemically very stable boron nitride material on the surface of the carbon nanotubes.

[0188] In contrast, Comparative Example 2 using a composite carbonaceous conductive material including more than 21 wt % of a boron element exhibited a sheet resistance 100 times higher than that of Comparative Example 1, resulting in being unusable as a conductive material.

[0189] As a result of the foregoing observations, it was confirmed that the embodiments of the present disclosure suppress or reduce the side reaction between the carbonaceous conductive material and the electrolyte by forming a coating having set or predetermined amounts of boron and nitrogen elements on the carbonaceous conductive material, and maintain the conductivity of the conductive material.

[0190] For example, the preparation of a composite carbonaceous conductive material involves dispersing boric acid in ethanol, adding multi-walled carbon nanotubes (MWCNTs), and drying the mixture to load the MWCNTs with boric acid. The loaded MWCNTs are then heated to form boron oxide and then nitrided at high temperature to coat them with boron nitride, resulting in the composite carbonaceous conductive material. Variations on this process include changing the amount of MWCNTs or using different solvents and drying methods to produce films or other forms of the material.

[0191] Elemental analysis evaluated the composite material, confirming the presence of boron, nitrogen, and oxygen in the coating. Transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) were used to measure the coating thickness. Sheet resistance and voltage withstand tests demonstrated that the boron nitride coating effectively suppressed oxidation current and maintained electrical conductivity, even under high voltage conditions.

[0192] Comparative examples without boron nitride coating or with excessive boron content exhibited higher sheet resistance and poorer performance. The results show that the composite carbonaceous conductive material according to embodiments of the present invention can significantly reduce side reactions and improve the stability and performance of rechargeable batteries.

[0193] The battery manufacturing apparatus, battery management system (BMS) apparatus, and / or any other related apparatus or components according to the embodiments of the present disclosure described herein can be implemented using any suitable hardware, firmware (e.g., an application-specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, the components of the apparatus may be formed on a single integrated circuit (IC) chip or on separate IC chips. Furthermore, the components of the apparatus may be implemented on a flexible printed circuit film, a tape carrier package (TCP), a printed circuit board (PCB), or formed on a substrate. Furthermore, the components of the apparatus may be processes or threads running on one or more processors in one or more computing devices that execute computer program instructions and interact with other system components to perform the functions described herein. The computer program instructions are stored in a memory, which may be implemented in the computing device using standard memory devices (such as, for example, random access memory (RAM)). The computer program instructions may also be stored in other non-transitory computer-readable media (such as, for example, CD-ROMs, flash drives, etc.). Furthermore, those skilled in the art will appreciate that the functionality of computing devices may be combined or integrated into a single computing device, or the functionality of a particular computing device may be distributed across one or more other computing devices without departing from the scope of the present disclosure.

[0194] Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments.

[0195] While the present disclosure has been described in conjunction with what are presently considered to be practical example embodiments, it will be understood that the present disclosure is not limited to the disclosed embodiments, but is intended to cover one or more suitable modifications and equivalent arrangements included within the spirit and scope of the appended claims and their equivalents.

Claims

1. A conductive material, comprising: carbon nanotubes, and coating, on the surface of the carbon nanotubes, Wherein, the coating comprises nitrogen, boron and oxygen elements, The weight ratio of the amount of the boron element to the amount of the nitrogen element is greater than or equal to 0.7 and less than or equal to 1.3, and Based on 100 wt % of the total amount of the conductive material, the amount of the boron element is greater than or equal to 1.0 wt % and less than or equal to 21 wt %. Wherein, the conductive material is a composite carbonaceous conductive material.

2. The conductive material according to claim 1, wherein Based on 100 wt % of the total amount of the conductive material, the total amount of the nitrogen element and the boron element is greater than or equal to 2.0 wt % and less than or equal to 50.0 wt %.

3. The conductive material according to claim 1, wherein The coating includes boron nitride. The conductive material according to claim 1 , wherein Based on 100 wt % of the total amount of the conductive material, the amount of the boron element is greater than or equal to 2 wt % and less than or equal to 15 wt %. The conductive material according to claim 1 , wherein Based on 100 wt % of the total amount of the conductive material, the amount of the boron element is greater than 3.6 wt % and less than or equal to 10 wt %. The conductive material according to claim 1 , wherein A weight ratio of the sum of the amount of the boron element and the amount of the nitrogen element to the amount of the oxygen element is greater than or equal to 0.5 and less than or equal to 8.

0.

7. The conductive material according to claim 1, wherein The thickness of the coating layer is greater than or equal to 0.3 nm and less than or equal to 20 nm.

8. A positive electrode, comprising: Positive electrode active material; as well as Conductive materials, wherein the conductive material is the conductive material according to any one of claims 1 to 7, and The positive electrode is a positive electrode for a rechargeable battery.

9. The positive electrode according to claim 8, wherein The positive electrode also includes a sulfide solid electrolyte.

10. A rechargeable battery, comprising: positive electrode; negative electrode; diaphragm; as well as non-aqueous electrolyte, wherein the positive electrode is the positive electrode according to claim 8 or 9, and Wherein, the rechargeable battery is a non-aqueous electrolyte rechargeable battery.

11. The rechargeable battery according to claim 10, wherein The rechargeable battery is charged and discharged at a voltage greater than 4.5V.

12. The rechargeable battery according to claim 10, wherein The rechargeable battery has a current of 1 mA / cm 2 Up to 1.5 mA / cm 2 oxidation current density.

13. The rechargeable battery according to claim 10, wherein The rechargeable battery has a sheet resistance of 5 Ω / sq to 7 Ω / sq.

14. A solid rechargeable battery, comprising: positive electrode; negative electrode; as well as solid electrolyte layer, Wherein, the positive electrode is the positive electrode according to claim 8.

15. The solid rechargeable battery according to claim 14, wherein The solid electrolyte layer includes a sulfide solid electrolyte.

16. The solid rechargeable battery according to claim 14, wherein The solid rechargeable battery is charged and discharged at a voltage greater than 4.5V.

17. A method comprising the steps of: providing carbon nanotubes and a precursor layer comprising boron oxide, the boron oxide covering at least a portion of a surface of the carbon nanotubes; as well as nitriding the boron oxide to form a coating on the carbon nanotubes, the coating comprising boron and nitrogen elements, wherein the weight ratio of the amount of the boron element to the amount of the nitrogen element is greater than or equal to 0.7 and less than or equal to 1.3, Based on 100wt% of the total amount of the composite carbonaceous conductive material, the amount of the boron element is greater than or equal to 1.0wt% and less than or equal to 21wt%, and Wherein, the method is a method for preparing the composite carbonaceous conductive material.

18. The method according to claim 17, wherein The step of providing the precursor layer comprises: immersing at least one surface of the carbon nanotube in a solution comprising the boron element; or The solution including the boron element is coated on the at least one surface of the carbon nanotube.

19. The method according to claim 17, wherein The coating includes boron nitride.

20. The method according to claim 17, wherein The thickness of the coating layer is greater than or equal to 0.3 nm and less than or equal to 20 nm.

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