Composite comprising transition metal oxide and ceramic, an anode for lithium-ion battery comprising the same, and the process thereof

Abstract

The present invention relates to a negative electrode for a high-performance lithium-ion battery comprising a transition metal oxide / ceramic composite, a lithium-ion battery comprising the same, and a method for manufacturing the same. In the composite according to the present invention, ceramic nanoparticles according to the present invention are integrated into a transition metal oxide matrix, thereby significantly improving electrical conductivity, lithium-ion diffusion, and structural stability. The composite is synthesized through a calcination process following a hydrothermal reaction and has a cubic spinel crystal structure and a one-dimensional nanowire form. The composite negative electrode according to the present invention exhibits improved charge transport, higher capacity, improved high-rate characteristics, and excellent long-term cycle stability compared to a pure transition metal oxide negative electrode, making it suitable for high-performance lithium-ion batteries used in energy storage devices, portable electronic devices, and electric vehicles.

Description

Technology Field

[0001] The present invention relates to a composite comprising a transition metal oxide and a ceramic, a negative electrode for a lithium-ion battery comprising the same, and a method for manufacturing the same. Background Technology

[0002] With the rapid growth of portable electronic devices, electric vehicles, and large-scale energy storage systems, the demand for lithium-ion batteries with higher energy density, improved output characteristics, and longer cycle life has increased significantly. As a result, extensive research has been conducted on cathode materials capable of meeting these performance requirements.

[0003] Conventional lithium-ion batteries primarily utilize graphite-based anodes due to their low cost, chemical stability, and commercial maturity. However, graphite anodes have limited theoretical capacity, which restricts further improvements in energy density. Additionally, graphite exhibits relatively poor high-rate performance and safety issues related to lithium plating under high current or low-temperature conditions.

[0004] To overcome these limitations, various transition metal oxide-based cathode materials, such as nickel oxide, cobalt oxide, manganese oxide, and mixed metal oxides, have been investigated. While these materials offer higher theoretical capacity compared to graphite, they generally suffer from low intrinsic electrical conductivity, large volume changes during lithium insertion / extraction, and poor structural stability. These drawbacks often lead to rapid capacity degradation and poor cycle performance.

[0005] Among mixed metal oxides, Ni-Co based oxides have attracted attention due to their multiple oxidation-reduction reactions and relatively high capacity. However, conventional NiCo2O4 cathodes prepared by traditional synthesis methods often exhibit heterogeneous particle morphology and limited pores.

[0006] It exhibits a long lithium ion diffusion path, resulting in insufficient high-rate performance and high internal resistance. Additionally, repeated charge and discharge cycles cause mechanical stress and pulverization, which degrades electrical contact and shortens battery life.

[0007] To address these issues, conductive additives, binders, or carbon-based coatings are frequently incorporated into the cathode electrode. However, the excessive use of binders and conductors can reduce the effective active material content, increase interfacial resistance, and complicate electrode fabrication. Furthermore, conventional modification methods fail to sufficiently improve the intrinsic charge transport or structural integrity of the active material.

[0008] Meanwhile, in the field of water electrolysis, the development of electrode catalysts for the Oxygen Evolution Reaction (OER) is actively underway, and composites of semiconductor oxides and specific ceramic materials are reported to exhibit excellent electrochemical performance. In particular, lead-copper-phosphate-sulfate-based ceramic materials of specific compositions are known to be effective in improving electrical conductivity and separating charge carriers.

[0009] Therefore, there is still a demand for new cathode materials and composite structures that are compatible with scalable and cost-effective manufacturing processes for lithium-ion batteries while simultaneously improving electrical conductivity, lithium-ion diffusion, mechanical stability, and long-term cycle performance. Prior art literature

[0010] 1. Korean Registered Patent No. 10-1733492 2. Korean Registered Patent No. 10-0785043 3. Korean Published Patent No. 10-2023-0030188

[0011] 1. Chemistry of Materials (2024), 36(1), 275-285 The problem to be solved

[0012] The present invention aims to provide a high-performance cathode material for lithium-ion batteries that solves the technical problems of the existing technology discussed above and overcomes the limitations of existing cathode materials, such as low electrical conductivity, limited high-rate characteristics, and poor cycle stability.

[0013] Another objective of the present invention is to improve lithium-ion storage performance by adopting a novel composite cathode structure based on transition metal oxides and ceramic-containing components of a specific composition.

[0014] Another objective of the present invention is to provide a highly efficient and structurally stable composite cathode by improving electrical conductivity, lithium ion diffusion, and electrochemical reaction kinetics through the integration of a transition metal oxide with a ceramic-containing component of a specific composition.

[0015] Another objective of the present invention is to provide a composite cathode configured to achieve predetermined specific capacity and high rate characteristics suitable for high-power and high-energy lithium-ion battery applications.

[0016] Another objective of the present invention is to provide a composite cathode optimized to increase charge carrier density within the active material and enhance electron and lithium ion transport through controlled composition, microstructure, and morphology.

[0017] Another objective of the present invention is to provide a composite cathode in which the structure and process parameters of the composite cathode are optimized, comprising at least one of ceramic content, hydrothermal synthesis conditions, firing temperature, particle shape, and porosity, in order to improve electrochemical performance, cycle stability, and long-term reliability.

[0018] Ultimately, the present invention provides a stable and cost-effective novel transition metal oxide / ceramic composite cathode material that enables improved lithium storage performance through enhanced electrical conductivity, rapid lithium ion transport, and effective accommodation of volume changes during charge-discharge cycles. means of solving the problem

[0019] One aspect of the present invention relates to ceramic nanoparticles for a secondary battery negative electrode material represented by the following chemical formula 1.

[0020] [Chemical Formula 1]

[0021] Pb 10-x Cu x [(PO4) 6-y (SO4) y ]O z S z'

[0022] x is a real number from 0.9 to 9.9, and y is 10 -10 It is a real number of up to 5.9, and

[0023] z and z' are 10 each -10 It is a real number between 4 and 10, and z+z' is 10 -10 It is a mistake of up to 4.

[0024] In this specification, 'ceramic' means a substance represented by Chemical Formula 1 unless otherwise specified.

[0025] Another aspect of the present invention relates to a negative electrode for a lithium-ion battery comprising a composite according to various embodiments of the present invention.

[0026] Another aspect of the present invention relates to a lithium-ion battery comprising (i) a cathode according to various embodiments of the present invention, (ii) a positive electrode, and (iii) an electrolyte.

[0027] Another aspect of the present invention relates to a communication device, a transportation device, an energy storage device, a medical device, an aviation device, a ship device, etc., comprising a lithium-ion battery according to various embodiments of the present invention.

[0028] Another aspect of the present invention relates to a method for manufacturing a composite comprising the steps of: (A) hydrothermally treating a mixed solution comprising a precursor of a transition metal oxide of Formula 2 and a ceramic of Formula 1 to form a composite precursor; and (B) calcining the composite precursor to form a composite.

[0029] [Chemical Formula 2]

[0030] AB2O4

[0031] The above A is one or more selected from Ni, Mn, Co, Fe, Cu, and Zn, and

[0032] The above B is one or more selected from Ni, Mn, Co, and Fe, and

[0033] The above A and the above B are different from each other. Effects of the invention

[0034] According to various embodiments of the present invention, the technical problems of the prior art described above are resolved, and a composite for a lithium-ion battery having excellent electrochemical performance, a negative electrode including the same, a lithium-ion battery including the same, and a method for manufacturing the same are provided, and ultimately, a high-performance energy storage system can be achieved through the above.

[0035] Specifically, the composite cathode according to the present invention has a ceramic of Formula 1 acting as an efficient electron conduction promoter, thereby providing a continuous electron transport path within the electrode, which lowers the charge transfer resistance and substantially improves high-rate charge and discharge performance.

[0036] Furthermore, the ceramic components act as structural stabilizers at particle surfaces and grain boundaries, effectively buffering volume expansion and contraction and suppressing particle disintegration during cycling. Moreover, the composite cathode promotes the formation of a uniform and stable solid electrolyte interface (SEI) layer during initial cycles, thereby reducing continuous electrolyte degradation and minimizing irreversible lithium consumption.

[0037] The synergy between the mixed valence states (Ni, Co) within the spinel structure and the conductivity enhanced by the ceramic realizes high reversible capacity and long-term lifespan stability, while the porous nanostructure, derived from nanowires or interconnected nanoparticles, provides a large active area and short diffusion paths, ensuring excellent performance even at high current densities.

[0038] Furthermore, the optimized hydrothermal calcination method using inexpensive precursors and mild processing conditions is suitable for large-scale commercial production, supporting the development of sustainable high-energy density storage technologies for electric vehicles, renewable energy storage, and portable electronic devices. Brief explanation of the drawing

[0039] Figure 1 schematically illustrates the detailed experimental process for the synthesis of NiCo2O4 / ceramic composites. Figure 2 shows the X-ray diffraction (XRD) patterns of NiCo2O4 and NiCo2O4 / ceramic composites. Figure 3 shows the XPS spectra of pure NiCO2O4 and NiCO2O4 / ceramic composite electrodes. (a) Ni 2p, (b) Co 2p, (c) O 1s, (d) Pb 4f (complex), (e) P 2p (complex). Figures 4a and 4b are scanning electron microscope (SEM) images of a pure NiCo2O4 electrode, and Figures 4c and 4d are scanning electron microscope (SEM) images of a NiCo2O4 / ceramic composite electrode. Figures 4e to 4h are the elemental mapping results of the NiCo2O4 / ceramic composite. Figure 5 shows the galvanosthetic discharge / charge potential profiles of (a) pure NiCo2O4 and (b) NiCo2O4 / ceramic composite electrodes at a current density of 0.5 A / g. Specific details for implementing the invention

[0040] Below, various aspects and embodiments of the present invention will be examined in more detail.

[0041] Expressions such as 'comprising,' 'having,' 'consisting of,' and 'composed of' in this specification may have additional parts added unless 'only' is used. Furthermore, numerical values ​​or numerical ranges described in this specification are interpreted to include a margin of error unless otherwise explicitly stated. Additionally, expressions 'X to Y' indicating a numerical range in this specification mean 'X or greater and Y or less.'

[0042] Embodiments of the present invention will be described in detail below with reference to the drawings. However, detailed descriptions of known functions or configurations that may obscure the essence of the present invention in the following description and the attached drawings are omitted. Additionally, throughout the specification, the term 'comprising' a component means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0043] Unless specifically defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0044] One aspect of the present invention relates to ceramic nanoparticles for a secondary battery negative electrode material represented by the above chemical formula 1.

[0045] According to various aspects and embodiments of the present invention, the above ceramic may be used as a composite with a transition metal oxide (e.g., NCO) matrix to form a negative electrode for a lithium-ion battery; an energy storage device including the same; and various other multifunctional materials.

[0046] If some of the components constituting the ceramic are omitted or fall outside the compositional range, it is undesirable in that the effects according to various aspects and embodiments of the present invention cannot be fully expressed.

[0047] In particular, if some of the components constituting the ceramic are omitted or fall outside the compositional range, unlike the ceramic of the composition according to the present invention, the improvement in electrical conductivity is not effective, and thus the synergistic effect between the transition metal oxide (e.g., NCO) and the ceramic may not be observed.

[0048] In various aspects of the present invention, according to one embodiment, x in Formula 1 is 2.1 to 9.9.

[0049] Specifically, when x satisfies the range of 2.1 to 9.9, the bandgap energy of the ceramic of Formula 1 is reduced by Cu doping, thereby improving electrical conductivity. Consequently, a synergistic effect that cannot be predicted with the transition metal oxide alone or the ceramic alone is manifested in the composite with the transition metal oxide, thereby forming a continuous electron transport pathway within the electrode and promoting the diffusion of lithium ions, resulting in improved capacity and improved cycle stability. On the other hand, when x is less than 2.1, the improvement in electrical conductivity is insufficient due to the lack of Cu doping, so the above synergistic effect is not fully manifested. When x exceeds 9.9, the crystal structure stability of the ceramic is reduced, making it difficult to form a uniform composite with the transition metal oxide and potentially preventing the above synergistic effect from being observed. Therefore, it is desirable to satisfy the range of x 2.1 to 9.9.

[0050] Another aspect of the present invention relates to a composite comprising (a) a transition metal oxide of Formula 2 below and (b) a ceramic of Formula 1 below.

[0051] [Chemical Formula 2]

[0052] AB2O4

[0053] The above A is one or more selected from Ni, Mn, Co, Fe, Cu, and Zn, and

[0054] The above B is one or more selected from Ni, Mn, Co, and Fe, and

[0055] The above A and the above B are different from each other.

[0056] [Chemical Formula 1]

[0057] Pb 10-x Cu x [(PO4) 6-y (SO4) y ]O z S z'

[0058] The above x is a real number from 0.9 to 9.9, and the above y is 10 -10 It is a real number of up to 5.9, and

[0059] The above z and the above z' are each 10 -10 It is a real number between 4 and 10, and z+z' is 10 -10 It is a mistake of up to 4.

[0060] According to one embodiment, the transition metal oxide of Chemical Formula 2 is represented by the following Chemical Formula 3.

[0061] [Chemical Formula 3]

[0062] Ni a M 1-a Co2O4

[0063] The above M is one or more selected from Mn, Fe, Cu, and Zn, and

[0064] The above a is a real number such that 0 < a ≤ 1.

[0065] According to another embodiment, x is 2.1 to 9.9. It is desirable that the band energy of the ceramic of Formula 1 is changed when the Cu doping amount is controlled to the above range, thereby significantly improving conductivity. In particular, when the Cu doping amount is 2.1 or higher, the electronic structure of the ceramic is optimized, the charge carrier density increases significantly, and accordingly, the charge transfer resistance of the composite electrode is significantly reduced, thereby improving high-rate charge and discharge characteristics.

[0066] According to another embodiment, the ceramic nanoparticles are distributed on at least one of the particle surface, the crystal lattice, or the inter-particle interface of the transition metal oxide. In other words, the ceramic nanoparticles are distributed on at least one of the surface or the interior of the nanostructure of the transition metal oxide or the interface between the nanostructures. This distribution pattern forms a continuous electron transport pathway within the electrode, improves electrical connectivity between particles to reduce charge transfer resistance, and further serves to effectively disperse mechanical stress caused by volume changes occurring during repeated lithium insertion / desorption processes.

[0067] According to another embodiment, the transition metal oxide has a nanowire form. Specifically, as a result of confirming the surface morphology of the synthesized composite material through field emission scanning electron microscopy (FE-SEM) observation, it exhibits a one-dimensional nanowire form in which numerous nanowires are uniformly distributed and interconnected to form a porous three-dimensional network.

[0068] The nanowires have an average diameter in the nanometer range and extend to a length in the sub-micrometer to micrometer scale, specifically having an average diameter in the range of 10-30 nm and an average length in the range of 0.5-1 μm, preferably an average diameter in the range of 15-30 nm and an average length in the range of 0.5-1 μm, which can provide a large specific surface area and a continuous electron transport pathway. The formation of the nanowire form is the result of nickel being incorporated into the Co oxide lattice during a hydrothermal synthesis process, for example, when having the structure of Formula 3.

[0069] According to another embodiment, the nanowires have an average diameter in the nanometer range and an average length in the sub-micrometer to micrometer range, and the nanowires are interconnected to form a porous three-dimensional network. This nanowire-based three-dimensional network structure provides a large specific surface area, maximizing the contact area with the electrolyte and shortening the diffusion path of lithium ions to improve high-rate characteristics. In addition, the interconnected nanowire structure forms a continuous electron transport path within the electrode to reduce charge transfer resistance and provides a mechanical buffering effect against volume changes occurring during repeated charging and discharging processes, thereby contributing to maintaining the structural integrity of the electrode.

[0070] According to another embodiment, the composite has a high open porosity. The nanowire-based form provides a high open porosity, enabling effective electrolyte penetration and a short lithium ion diffusion path. In addition, the continuous one-dimensional structure enables rapid electron transport and relieves mechanical stress associated with volume changes during repeated lithium insertion / extraction.

[0071] According to another embodiment, the ceramic has the form of nanoparticles, and the nanoparticles have an average diameter of 10-35 nm. Within this range, a satisfactory level of active site density and structural stability can be obtained. Outside this range, it is undesirable because sufficient active site density cannot be obtained, or structural stability may be reduced due to aggregation over time caused by high surface energy.

[0072] According to a particularly preferred embodiment, the average diameter of the nanoparticles is 15-30 nm. In the case of the preferred range, beyond the quantitative effect of simply improving the density of active sites and structural stability compared to the case outside the preferred range, heterogeneous effects are exhibited in which the uniformity of interfacial contact between the transition metal oxide nanowire surface and the ceramic nanoparticles is significantly increased and the continuity of the electron conduction network is optimized, thereby shortening the diffusion path of lithium ions and drastically reducing the charge transport resistance. The manifestation of these heterogeneous effects depends on whether the average diameter of the ceramic nanoparticles is at the upper and lower limits of the preferred range. This appears to be because ceramic nanoparticles in the 15-30 nm range are homogeneously distributed with a maximized dispersion density on the surface and grain boundaries of the transition metal oxide nanowires, effectively buffering the volume expansion and contraction that occur during the repeated lithium insertion / extraction process, thereby suppressing local stress concentrations that cause particle pulverization.

[0073] According to another embodiment, the composite comprises 0.1 to 20 parts by weight of the ceramic of Formula 1 based on 100 parts by weight of the transition metal oxide. If the amount is below the lower limit of the above range, the effect of improving electrical conductivity by the ceramic component may not be sufficiently expressed, and if the amount exceeds the upper limit of the above range, the intrinsic electrochemical activity of the transition metal oxide matrix may be inhibited, which is undesirable.

[0074] According to another embodiment, the composite has a cubic spinel crystal structure. Specifically, as a result of analyzing the X-ray diffraction (XRD) pattern of the composite according to the present invention, all observed diffraction peaks can be indexed to the cubic spinel crystal structure, which indicates that the target phase has been successfully formed. No additional diffraction peaks corresponding to secondary phases or impurity phases are detected, confirming the high phase purity of the synthesized material.

[0075] According to another embodiment, the diffraction peaks of the composite match well with cubic standard diffraction data (JCPDS No. 00-020-0781), and no additional diffraction peaks corresponding to secondary or impurity phases are observed. These XRD analysis results indicate that the synthesized composite effectively incorporates ceramic components while maintaining a high-purity spinel structure, which contributes to the electrochemical performance of the composite.

[0076] According to another embodiment, the composite exhibits relatively broad diffraction peaks, which are attributed to the nanocrystalline nature of the material. The integration of the ceramic-containing component does not alter the basic spinel structure of the transition metal oxide, suggesting that the ceramic component is highly dispersed, integrated into the lattice at low concentrations, or exists in an amorphous or nanophase form that is not detected by XRD.

[0077] According to another embodiment, X-ray photoelectron spectroscopy (XPS) analysis results show that the composite is Ni 2+ / Ni 3+ , Co 2+ / Co 3+It exhibits a mixed valence electron composition, and the peak intensity of defect-associated oxygen species increases compared to the pure transition metal oxide. This mixed valence electron composition is beneficial for improved electronic conductivity and reversible lithium-ion storage. The integration of ceramic components contributes to the improvement of surface properties of the composite cathode material without interfering with the intrinsic oxidation state of the spinel matrix.

[0078] According to a specific embodiment, X-ray photoelectron spectroscopy (XPS) was performed to investigate the elemental composition and oxidation state of the composite. As a result, the detailed investigation spectrum confirmed the presence of Ni, Co, O, and ceramic-related elements (Pb, Cu, P, S), indicating that the constituent elements were successfully integrated without detectable contamination.

[0079] In addition, the high-resolution Ni 2p spectrum of the above complex exhibits two main peaks centered at approximately 853–855 eV and 871–873 eV, which respectively represent Ni 2p 3 / 2 and Ni 2p 1 / 2 It corresponds to energy levels. In addition, a characteristic shake-up satellite peak is observed at higher binding energies, which corresponds to Ni within the spinel structure. 2+ and Ni 3+ It indicates that oxidation states coexist.

[0080] In addition, the high-resolution Co 2p spectrum exhibits two major peaks at binding energies of approximately 779–781 eV and 794–796 eV, which indicates Co 2p 3 / 2 and Co 2p 1 / 2 It is assigned to energy levels. The presence of accompanying satellite peaks suggests a mixed valence state of cobalt, and Co 2+ and Co 3+ It indicates the coexistence of paper.

[0081] Additionally, the O 1s spectrum can be deconvolved into several components. The dominant peak at approximately 529.5–529.8 eV is attributed to lattice oxygen associated with metal-oxygen bonding. An additional peak at approximately 531.5–532.0 eV is assigned to oxygen species associated with defect sites or low oxygen coordination, which are more widespread in nanostructured materials with small particle sizes. The relative intensity of defect-associated oxygen species increased slightly in the composite, suggesting an enhancement in surface defect density that can facilitate lithium ion transport and electrochemical activity.

[0082] According to another embodiment, the preferred average diameter of the plurality of ceramic nanoparticles is 10-35 nm, and the more preferred average diameter is 15-30 nm. Within the preferred range, a satisfactory level of active site density and structural stability can be obtained, and in particular, within the more preferred range, the density of active sites and structural stability can be maximized simultaneously, making it even more desirable. Outside the preferred range, it is undesirable because sufficient active site density cannot be obtained, or structural stability may be reduced due to aggregation over time caused by high surface energy.

[0083] Another aspect of the present invention relates to a negative electrode for a lithium-ion battery comprising a composite according to various embodiments of the present invention.

[0084] According to one embodiment, the cathode can be fabricated as a binder-free or low-binder composition to reduce interfacial resistance. The binder-free cathode has the advantage of improved accessibility of lithium ions to the electrode active material due to the absence of active material coating by the binder, increased energy density of the electrode due to the elimination of the inactive volume occupied by the binder, and improved electrochemical kinetics due to reduced charge transfer resistance at the electrode / electrolyte interface.

[0085] According to another embodiment, reversible lithium insertion / desorption occurs in the cathode during battery operation through multiple electron oxidation-reduction reactions of Ni, Mn, and Co. Ni within the spinel structure 2+ / Ni 3+, Co 2+ / Co 3+ Mixed valence states enable multiple electron transition reactions, providing high theoretical capacity, and electrical conductivity enhanced by ceramic components improves the kinetics of these oxidation-reduction reactions, thereby improving high-rate charge / discharge characteristics.

[0086] According to another embodiment, the cathode promotes the formation of a stable solid electrolyte interface (SEI) to provide excellent cycle stability. The composite cathode promotes the formation of a uniform and stable SEI layer during the initial cycle, thereby reducing continuous electrolyte degradation and minimizing irreversible lithium consumption.

[0087] The presence of ceramic components improves the mechanical strength and ion conductivity of the SEI layer, thereby suppressing the breakdown and reformation of the SEI layer even during repeated charge and discharge processes, and improving long-term cycle stability.

[0088] Another aspect of the present invention relates to a lithium-ion battery comprising (i) a negative electrode, (ii) a positive electrode, and (iii) an electrolyte, wherein the negative electrode comprises a composite according to various embodiments of the present invention.

[0089] According to one embodiment, the lithium-ion battery may be a CR2032 coin-type battery. However, the composite negative electrode according to the present invention is not limited to a coin-type battery and may be manufactured in various cell shapes such as pouch type, cylindrical type, and prismatic type.

[0090] According to another embodiment, the lithium-ion battery has a voltage of 0.01-3.0 V (vs. Li / Li +It operates within a potential window. This potential range is the range in which reversible oxidation-reduction reactions of Ni and Co occur at the transition metal oxide (e.g., NCO) / ceramic composite cathode, and it is a range that minimizes side reactions such as electrolyte decomposition or lithium plating while exhibiting optimal electrochemical performance during the lithium insertion / extraction process.

[0091] Another aspect of the present invention relates to a device comprising a lithium-ion battery according to various embodiments of the present invention. The device may be selected from, but is not limited to, a communication device, a transportation device, an energy storage device, a medical device, an aviation device, and a marine device.

[0092] Since the composite cathode according to the present invention exhibits high energy density, excellent high-rate characteristics, and long-term cycle stability, it can be applied to various applications requiring high-performance lithium-ion batteries, such as portable electronic devices like smartphones and laptops, electric vehicles, hybrid electric vehicles, large-scale energy storage systems (ESS), medical implant devices, drones, satellites, and electric ships.

[0093] Another aspect of the present invention relates to a method for manufacturing a composite comprising the steps of: (A) hydrothermally treating a mixed solution comprising a precursor of a transition metal oxide of Formula 2 and a ceramic of Formula 1 to form a composite precursor; and (B) calcining the composite precursor to form a composite.

[0094] According to one embodiment, the transition metal oxide of Chemical Formula 2 is represented by Chemical Formula 3.

[0095] According to another embodiment, x is 2.1 to 9.9. According to yet another embodiment, the precursor compounds of nickel and cobalt are nickel acetate and cobalt acetate, respectively. Acetate salts are suitable as precursors because they have excellent solubility in aqueous solution, form a uniform precipitate under hydrothermal reaction conditions, and decompose during the calcination process to provide a pure metal oxide.

[0096] According to another embodiment, urea is additionally added as a homogeneous precipitating agent in step (A). That is, the mixed solution additionally contains urea as a homogeneous precipitating agent. Urea slowly decomposes under hydrothermal reaction conditions, releasing ammonia and carbon dioxide, thereby causing the pH to gradually rise and form a homogeneous metal hydroxide precipitate. This homogeneous precipitation mechanism contributes to the formation of nanowire-shaped precursors and influences the microstructure and electrochemical performance of the final composite.

[0097] According to another embodiment, the hydrothermal treatment is performed at 150-180°C for 6-24 hours. In this temperature and time range, a nanowire-shaped precursor is effectively formed, and the ceramic component is uniformly incorporated into the metal hydroxide matrix. If the temperature is too low or the time is too short, crystallization is insufficient, and if the temperature is too high or the time is too long, particle growth is excessive, which may damage the nanostructure.

[0098] According to another embodiment, the calcination is performed at 300-500 °C for 1-5 hours. Under these calcination conditions, the precursor obtained by the hydrothermal reaction is converted into a crystalline spinel structure, the organic material is decomposed, and the nanowire form is maintained. If the calcination temperature is too low, crystallization is insufficient, and if it is too high, the nanostructure may be damaged and the specific surface area reduced due to particle sintering.

[0099] According to another embodiment, the ceramic-containing component is ball-milled. The ball milling is preferably performed at 400-700 rpm for 3-36 hours, and more preferably at 450-550 rpm for 5-7 hours. Under these ball-milling conditions, the average crystal size of the ceramic is reduced to 40-50 nm, the average particle size is 500-1,500 nm, and the full width at half maximum (FWHM) of the particle size is 1,000 nm or less, more preferably 500 nm or less, which is advantageous for further improving the electrochemical performance of the composite.

[0100] According to another embodiment, the ball-milled powder of the ceramic has an average crystal size of 40-50 nm as a result of X-ray diffraction analysis, and an average particle size of 500-1,500 nm and a particle width at half maximum of 500 nm or less as a result of dynamic light scattering (DLS) analysis. The ball-milled ceramic powder having these characteristics is uniformly dispersed in a hydrothermal reaction medium and is effectively incorporated into a transition metal oxide (e.g., NCO) matrix, contributing to improved electrical conductivity and structural stability in the final composite.

[0101] The present invention is to be explained in more detail below through examples, etc.; however, the scope and content of the present invention shall not be interpreted as being narrowed or limited by the examples, etc. below. Furthermore, based on the disclosure of the present invention including the examples below, it is evident that a person skilled in the art can easily practice the present invention even without specific experimental results presented, and it is natural that such variations and modifications fall within the scope of the appended claims.

[0102] Furthermore, the experimental results presented below describe only the representative experimental results of the above examples and comparative examples, and the respective effects of various embodiments of the present invention not explicitly presented below will be described in detail in the relevant sections.

[0103] Examples

[0104] chemical substances

[0105] Nickel acetate, cobalt acetate, urea, and ceramic powder were used as precursors, and deionized water (DI) was used as a solvent. All chemicals used were AR grade and were used without further purification.

[0106] Preparation Example 1: Ceramic Preparation

[0107] Powders of PbO, PbSO4, Cu, and P were prepared in the molar ratio of the molecule to be synthesized and uniformly mixed. The mixture was placed in a reaction tube (quartz tube or copper tube), vacuum was created, and the tube was sealed. Then, the reaction was carried out by heating at 770 °C for 12 hours.

[0108] After the reaction was completed, the granules generated in the reaction tube were powdered and then heated a second time at 550 °C for 5 hours under reduced pressure to a near-vacuum state. Through this process, solid sulfur was sublimated, and ceramics were manufactured by removing the sublimated sulfur in a molar ratio through an evacuation process.

[0109] For example, when synthesizing a ceramic with a Cu doping amount controlled to 2 moles, the raw materials are mixed with a molar ratio of PbO : PbSO4 : Cu : P = 2 : 6 : 2 : 6, and as another example, the composition is Pb 7.38 Cu 2.62 (PO4) 5.46 (SO4) 0.54 O 0.66 S 0.84 When synthesizing the ceramic, the raw materials were mixed with a molar ratio of PbO : PbSO4 : Cu : P = 1.38 : 6 : 2.62 : 6.

[0110] Manufactured Pb 7.38 Cu 2.62 (PO4) 5.46 (SO4) 0.54 O 0.66 S 0.84A ceramic (structure confirmed through XPS and XRD, etc., and average molecular weight confirmed to be 2,303) was ball-milled at 500 rpm for 6 hours to obtain ball-milled powder of the ceramic.

[0111] Comparative Manufacturing Example 1: Ceramic Manufacturing

[0112] Pb9Cu(PO4)6O (CAS No. 2972464-09-6) was prepared according to a known method, such as Chemistry of Materials (2024), 36(1), 275-285.

[0113] Comparative Manufacturing Example 2: Ceramic Manufacturing

[0114] Pb9Cu(PO4) according to the method described in Korean Published Patent No. 10-2023-0030188 (Patent Application No. 10-2021-0112104) 5.5 (SO4) 0.5 S 3.5 Manufactured.

[0115] Comparative Example 1: Pure NiCo 2 O 4 synthesis

[0116] Pure samples were prepared through a process of hydrothermal synthesis followed by calcination. Stoichiometric amounts of nickel acetate and cobalt acetate were dissolved in deionized water according to the desired Ni / Co molar ratio. After complete dissolution, the precursor solution was continuously stirred, and urea was added as a homogeneous precipitating agent. The solution was stirred until a homogeneous and transparent mixture was obtained, after which it was transferred to a Teflon-coated stainless steel autoclave. The hydrothermal reaction was carried out at approximately 150–180 °C for about 6–12 hours. After natural cooling to room temperature, the resulting precipitate was recovered, thoroughly washed with deionized water and ethanol to remove residual ions, and then dried at approximately 60–80 °C. The dried precursor was calcined at approximately 300–500 °C for several hours to obtain nanostructured crystalline spinel NiCO2O4 powder.

[0117] Example 1: NiCo 2 O 4 Synthesis of ceramic composites

[0118] The composite was synthesized using a hydrothermal sintering method similar to that of the pure sample, but with the addition of ceramic components (see Fig. 1). Nickel and cobalt acetate were dissolved in deionized water in equal molar ratios, and the ceramic ball-mill powder prepared in Preparation Example 1 was added to the mixed precursor solution before or during hydrothermal treatment. The ceramic powder was evenly dispersed through vigorous stirring and / or ultrasonic treatment to ensure uniform distribution within the reaction medium. Subsequently, urea was added, and hydrothermal treatment was performed at 150–180 °C for approximately 6 hours to induce the formation of the NiCO2O4 phase and the close bonding of the ceramic components. The collected composite precipitate was washed and dried, then sintered at approximately 300–500 °C to obtain a highly crystalline composite in which the ceramic components were uniformly distributed on the particle surface, grain boundaries, and interfaces.

[0119] Hydrothermal treatment was performed by adding ceramic ball mill powder to the above mixed precursor solution in amounts such that the ceramic content was 1, 5, 10, and 15 parts by weight, respectively, based on 100 parts by weight of transition metal oxide in the final composite.

[0120] Comparative Examples 2 and 3: Complex Synthesis

[0121] A composite was prepared in the same manner as in the example, except that the ceramic prepared in Comparative Examples 1 and 2 was used instead of the ceramic prepared in Example 1 (Comparative Examples 2 and 3, respectively).

[0122] Test Example 1: X-ray Diffraction (XRD) Analysis

[0123] XRD analysis was performed on the pure NiCo2O4 prepared in Comparative Example 1 and the composite prepared in Example 1.

[0124] As a result, as shown in Figure 2, all diffraction peaks observed in both samples correspond to a cubic spinel crystal structure, indicating that the target phase was successfully formed. No additional diffraction peaks corresponding to secondary or impurity phases were detected, demonstrating the high phase purity of the synthesized material. The diffraction peaks of the NiCo2O4 sample matched well with standard spinel-type diffraction data, showing that the nickel-cobalt oxide possesses a spinel structure.

[0125] Both NiCo2O4 and the composite samples exhibit relatively broad diffraction peaks, which are attributed to the nanocrystalline nature of the materials. The addition of ceramic components does not alter the basic spinel structure of NiCo2O4, suggesting that the ceramic components are highly dispersed, integrated into the lattice at low concentrations, or exist in an amorphous or nanophase form that is not detected by XRD.

[0126] Test Example 2: Scanning Electron Microscope (SEM) Analysis

[0127] FE-SEM analysis was performed on the pure NiCo2O4 prepared in Comparative Example 1 and the composite prepared in Example 1.

[0128] As a result, as shown in Fig. 4, the pure NiCo2O4 sample exhibited a one-dimensional nanowire structure composed of numerous nanowires that were uniformly distributed and interconnected to form a porous three-dimensional network (Figs. 4a and 4b). The nanowires had an average diameter in the nanometer range and a length ranging from sub-micrometers to micrometers, demonstrating a structure capable of providing a large specific surface area and continuous electron transfer pathways.

[0129] In the case of the composite (Figs. 4c and 4d), the overall nanowire structure was well preserved even after the ceramic-containing component was incorporated. The ceramic-containing component was uniformly distributed along the nanowire surface, embedded within the nanowire matrix, or located at the junctions between nanowires, and did not cause significant aggregation or structural collapse. This uniform distribution contributes to improved electrical connectivity and mechanical stability of the composite electrode.

[0130] The nanowire-based morphology of both samples provides a high open porosity, enabling effective electrolyte penetration and short lithium ion diffusion pathways. Furthermore, the continuous one-dimensional structure facilitates rapid electron transport and alleviates mechanical stress associated with volume changes during repeated lithium insertion / extraction. Consequently, the composite nanowires exhibit excellent electrochemical performance when used as anode materials in lithium-ion batteries.

[0131] Test Example 3: Electrochemical Performance Evaluation

[0132] The electrochemical characteristics of the NiCO2O4 and composite cathodes were evaluated using CR2032 coin-type half-cells. The working electrode was prepared by mixing the active material, conductive material (carbon), and polymer binder in appropriate weight ratios to form a homogeneous slurry, which was then coated onto a current collector and dried. Lithium metal was used as the counter and reference electrodes, and a standard lithium-ion battery electrolyte was adopted. To evaluate the charge-discharge behavior and cycle stability of the assembled cells, the batteries were tested at 0.01–3.0 V (vs. Li / Li + Galvanosthetic cycling was performed at various current densities within the range.

[0133] The electrochemical performance of pure NiCO2O4 and composite materials as anode materials for lithium-ion batteries was evaluated at room temperature. Charge and discharge measurements were performed at 0.01–3.0 V (vs. Li / Li) as shown in Fig. 5. +It was performed at a constant current density of 0.1-0.5 A / g within a potential window.

[0134] The composite cathode provided a higher initial discharge capacity and improved reversible capacity compared to pure NiCO2O4, and irreversible capacity loss during the first cycle was reduced. From the second cycle onwards, the voltage profile exhibited high reversibility without a distinct flat region, indicating stabilized lithium insertion and extraction behavior. The enhanced performance of the composite electrode is attributed to the nanostructured form, large specific surface area, and improved electrical conductivity provided by the ceramic-containing components, resulting in superior lithium storage performance compared to conventional graphite cathodes.

[0135] Test Example 4: Cycle Stability Evaluation

[0136] The cycle performance of the NiCo2O4 and composite cathode was evaluated for 200-500 cycles at a current density of 100-500 mA / g.

[0137] The pure cathode exhibited a decrease in capacity during initial cycles due to volume changes and partial structural degradation associated with conversion reactions and repeated lithium insertion / extraction. In contrast, the composite cathode demonstrated significantly improved cycle stability and capacity retention rates, maintaining high reversible capacity while minimizing performance degradation during long-term cycling.

[0138] This enhanced performance is attributed to the integration of ceramic-containing components that suppress electrode abrasion, promote stable SEI formation, and improve electrical conductivity and lithium ion diffusion. Furthermore, the combination of a porous nanowire structure that facilitates efficient electrolyte accommodation and shortened transport pathways provides excellent long-term electrochemical stability suitable for high-performance lithium-ion battery applications.

[0139] Test Example 5: Electrochemical Impedance Spectroscopy (EIS) Analysis

[0140] Electrochemical impedance spectroscopy (EIS) was additionally performed to analyze oxidation-reduction reactions, charge transfer characteristics, and interfacial resistance.

[0141] In the EIS Nyquist plot, the composite cathode has a significantly lower charge transfer resistance (R) compared to the pure NiCO2O4 cathode. ct ...did show. This means that the introduction of ceramics increased charge carrier density and electrical conductivity, thereby reducing resistance.

[0142] As a result, the composite cathode demonstrated enhanced electrochemical kinetics and improved lithium storage performance compared to the pure sample.

[0143] In addition, comparative experiments were performed on the composite cathodes prepared in Comparative Examples 2 and 3, respectively, with the composite cathode of Example 1.

[0144] In the case of the NiCo2O4 / ceramic composite cathode of Example 1, the initial discharge capacity at 0.5 A / g is approximately 650-700 mAh / g, which is an improvement of about 10-15% compared to pure NiCo2O4, and the reversible capacity is stably maintained at approximately 550-600 mAh / g after the third cycle, and the EIS analysis results show that the charge transfer resistance (R ct It was confirmed that the electrical conductivity was improved and lithium ion transport was promoted due to the synergistic effect between NiCo2O4 and ceramics, as the amount of ) was significantly reduced compared to pure NiCo2O4.

[0145] On the other hand, in the composite cathode of Comparative Example 2 and the composite cathode of Comparative Example 3, the initial discharge capacity at 0.5 A / g is approximately 580 mAh / g and approximately 590 mAh / g, respectively, remaining at a level similar to pure NiCo2O4, and the cycle stability is inferior to that of the example composite, and the effect of reducing charge transfer resistance is negligible, so the synergistic effect between the transition metal oxide and the ceramic is not observed, so the composites of various embodiments of the present invention including the composite of Example 1 are preferred.

Claims

Claim 1 delete Claim 2 (a) a transition metal oxide of the following Chemical Formula 2 and (b) a ceramic of the following Chemical Formula 1, a composite comprising: [Chemical Formula 2] AB2O4, wherein A is one or more selected from Ni, Mn, Co, Fe, Cu, and Zn, and B is one or more selected from Ni, Mn, Co, and Fe, and A and B are different from each other; [Chemical Formula 1] Pb 10-x Cu x [(PO4) 6-y (SO4) y ]O z S z' The above x is a real number from 0.9 to 9.9, and the above y is 10 -10 It is a real number of up to 5.9, and the above z and the above z' are each 10 -10 It is a real number between 4 and 10, and z+z' is 10 -10 It is a mistake of 4. Claim 3 In paragraph 2, the transition metal oxide of Formula 2 is a complex represented by the following Formula 3: [Formula 3]Ni a M 1-a Co2O4, the above M is one or more selected from Mn, Fe, Cu, and Zn, and the above a is a real number such that 0 < a ≤ 1. Claim 4 In paragraph 3, the above a is a complex of 1. Claim 5 A composite according to paragraph 2, characterized in that x is 2.1 to 9.

9. Claim 6 A composite according to paragraph 2, wherein the nanoparticles of the ceramic are distributed on at least one of the surface or interior of the nanostructure of the transition metal oxide or the interface between the nanostructures. Claim 7 In paragraph 2, the transition metal oxide is a composite having a nanowire form. Claim 8 In claim 7, the nanowires have an average diameter of 15-30 nm and an average length of 0.5-1 μm, and the nanowires are connected to each other to form a porous three-dimensional network, forming a composite. Claim 9 In paragraph 2, the ceramic has the form of nanoparticles, and the nanoparticles are a composite having an average diameter of 10-35 nm. Claim 10 In paragraph 2, the composite comprises the ceramic in a ratio of 0.1 to 20 parts by weight based on 100 parts by weight of the transition metal oxide. Claim 11 In paragraph 2, the complex is a complex having a cubic spinel crystal structure. Claim 12 A complex according to claim 2, wherein, as a result of X-ray diffraction (XRD) analysis, it exhibits diffraction peaks consistent with standard diffraction data of a cubic structure (JCPDS No. 00-020-0781), and no additional diffraction peaks corresponding to a secondary phase or impurity phase are observed. Claim 13 In paragraph 2, as a result of X-ray photoelectron spectroscopy (XPS) analysis, Ni 2+ / Ni 3+ , Co 2+ / Co 3+ A composite exhibiting a mixed valence electron composition, in which the peak intensity of defect-related oxygen species increases compared to the pure transition metal oxide. Claim 14 A negative electrode for a lithium-ion battery comprising a composite according to any one of claims 2 to 13. Claim 15 In claim 14, the above-mentioned cathode is a binder-free cathode for a lithium-ion battery. Claim 16 A lithium-ion battery comprising (i) a negative electrode, (ii) a positive electrode, and (iii) an electrolyte, wherein the negative electrode is a negative electrode for a lithium-ion battery according to claim 14. Claim 17 A device comprising a lithium-ion battery according to paragraph 16, wherein the device is selected from a communication device, a transportation device, an energy storage device, a medical device, an aviation device, or a marine device. Claim 18 A method for manufacturing a composite comprising the following steps: (A) a step of hydrothermally treating a mixed solution comprising a precursor of a transition metal oxide of Formula 2 below and a ceramic of Formula 1 below to form a composite precursor; and (B) a step of calcining the composite precursor to form a composite; [Formula 2] AB2O4, wherein A is one or more selected from Ni, Mn, Co, Fe, Cu, and Zn, and B is one or more selected from Ni, Mn, Co, and Fe, and A and B are different from each other; [Formula 1] Pb 10-x Cu x [(PO4) 6-y (SO4) y ]O z S z' The above x is a real number from 0.9 to 9.9, and the above y is 10 -10 It is a real number of up to 5.9, and the above z and the above z' are each 10 -10 It is a real number between 4 and 10, and z+z' is 10 -10 It is a mistake of 4. Claim 19 In claim 18, the transition metal oxide of the above Chemical Formula 2 is a method for preparing a complex represented by the following Chemical Formula 3: [Chemical Formula 3]Ni a M 1-a Co2O4, the above M is one or more selected from Mn, Fe, Cu, and Zn, and the above a is a real number such that 0 < a ≤ 1. Claim 20 In claim 19, the above a is a method for manufacturing a composite of one person. Claim 21 In claim 18, a method for manufacturing a composite in which x is 2.1 to 9.

9. Claim 22 In claim 18, the above-mentioned mixed solution is a method for manufacturing a complex that additionally includes urea as a homogeneous precipitating agent. Claim 23 A method for manufacturing a composite according to claim 18, wherein the hydrothermal treatment is performed at 150-180 ℃ for 6-24 hours, the firing is performed at 300-500 ℃ for 1-5 hours, and the ceramic is ball milled at 400-700 rpm for 3-36 hours.

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