Boron-modified high-voltage spinel LNMO cathode material

Abstract

This invention provides an LNMO microparticle material comprising microcrystals, crystals, and secondary particles, wherein the secondary particles are composed of a large number of crystals, and the crystals are composed of a large number of microcrystals, wherein the D0 of the secondary particles, as measured by laser diffraction according to ISO 13320:2020, is... 50 The particle size is from 3.0 µm to 25 µm, and wherein, as measured by scanning electron microscopy (SEM), the D of the crystal is... 50 The particle size is from 0.3 µm to 7.0 µm, and the LNMO particulate material is boron-modified. In other aspects, the present invention also provides a method for manufacturing boron-modified lithium nickel manganese oxide (LNMO) particulate material, and boron-modified LNMO materials obtainable by the method according to the invention.

Description

[0001] This invention relates to the design of the morphology and performance improvement of high-voltage spinel lithium nickel manganese oxide (LNMO) cathode active materials for secondary lithium-ion batteries through boron modification. Therefore, this invention relates to boron-modified LNMO materials, such as high-voltage spinel LNMO cathode materials. This invention also provides a method for manufacturing boron-modified LNMO materials.

[0002] Description of background technology

[0003] The growing market for rechargeable Li-ion batteries (LIBs) in electric vehicles, renewable energy, and consumer electronics necessitates the development of advanced batteries that are safe, cost-effective, and possess high energy and power densities. In this regard, lithium-ion batteries have dominated the market for portable electronic applications due to their superior energy and power density capabilities. Current trends are shifting towards the electrification of transportation and the development of large-scale energy storage systems (ESS) for various applications. Unfortunately, current lithium-ion batteries still suffer from poor safety, low energy density, and low power density, which severely hinders their widespread adoption in electric vehicles.

[0004] Currently, several materials, including LiCoO2, LiNiO2, LiMn2O4, and LiNi 0.8 Co 0.15 Al 0.05 O2 and LiNi 0.8 Mn 0.1 Co 0.1 O2 has been developed and used as a cathode material for lithium-ion batteries. However, these intercalated materials exhibit severe capacity decay and several safety issues.

[0005] Several reasons have been identified for this capacity decay and safety issue, including electrolyte degradation at higher cutoff voltages (>4.5V), structural instability, and the dissolution of metal ions in the electrolyte due to HF generation. Among the materials being developed for lithium-ion batteries, high-voltage spinel LiNi1 is... 0.5 Mn 1.5 O4 (LNMO) is a promising cathode material due to its high energy density and high power density, boasting a high theoretical capacity (~147 mAh g⁻¹) and a high operating voltage (~4.7 V, relative to Li₂). +The degradation of LNMO cathode materials is caused by the decomposition of the electrolyte at high operating voltages and temperatures (>45°C), resulting in poor cycle performance. This is due to parasitic reactions on the material surface, leading to rapid capacity decay. To alleviate LNMO-related problems, researchers have employed several methods, including morphology and particle size control, structural disorder and lithium concentration regulation, Mn / Ni cation doping, and surface modification. Surface modification has been widely recognized as a promising method for improving the performance of LNMO cathode materials.

[0006] Several material categories have been reported as coating materials, including oxides (ZrO2, SiO2, MgO, TiO2, SiO2, Al2O3) and ion conductors (Li7La3Zr2O). 12 Li 3x La 2 / 3-x TiO3, Li 1.3 Al 0.3 Ti 1.7 (PO4)3), conductive polymers, and conductive carbon. All these coating materials reduce undesirable side reactions between the electrolyte and the cathode material, thus improving the performance of these materials. Among these categories of coating materials, oxide coatings are simple and inexpensive, and have shown promising results in improving the performance of cathode materials operating under various conditions. These oxide coatings prevent undesirable side reactions between the cathode material surface and the electrolyte, resulting in improved structural stability and capacity retention. Recently, reports of ZrO2 coatings on LNMO and lithium-rich oxide materials have shown extremely high rate performance, although the reasons for such high performance are not yet fully understood. Unfortunately, most of these surface modification methods are not commercially feasible for large-scale production, and it is difficult to control the thickness and uniformity of these coatings. Most of these coatings may also enhance interfacial impedance, which hinders the migration of Li ions during insertion and extraction.

[0007] Therefore, there is a need in the field for high-voltage cathode materials with high theoretical capacity and high operating voltage, which exhibit improved cycle performance and capacity retention. Invention Overview

[0009] This invention addresses these problems in the prior art by providing a boron-modified lithium nickel manganese oxide (LNMO) material with a specific particle morphology as described herein.

[0010] Therefore, in a first aspect, an LNMO microparticle material comprising secondary particles is provided, wherein the secondary particles are composed of a large number of crystals, and the crystals are composed of a large number of microcrystals.

[0011] The D of the secondary particles, as measured by laser diffraction according to ISO 13320:2020, is...50 The particle size is from 3.0 µm to 25 µm; and wherein, as measured by scanning electron microscopy (SEM), the D of the crystal is... 50 The particle size is from 0.3 µm to 7.0 µm; and wherein the LNMO microparticle material is boron modified.

[0012] The present invention has also found that the boron-modified LNMO microparticle material of the present invention can be advantageously used as a cathode material in lithium-ion batteries.

[0013] In a second aspect, the present invention provides a method for manufacturing boron-modified lithium nickel manganese oxide (LNMO) particulate materials, the method comprising the following steps:

[0014] (a) Mixing particulate LNMO material with a solution of boric acid in an aqueous solvent,

[0015] (b) Remove the aqueous solvent to obtain a dry mixture.

[0016] (c) The mixture is calcined in an oxygen-containing atmosphere at a temperature of 700°C to 1100°C to form boron-modified LNMO microparticle material.

[0017] Thirdly, the present invention provides a boron-modified LNMO material that can be obtained by the method described in the present invention. Invention Details

[0019] Boron-modified lithium nickel manganese oxide (LNMO) particulate materials

[0020] In a first aspect, the present invention provides a boron (B)-modified lithium nickel manganese oxide (LNMO) microparticle material comprising secondary particles, wherein the secondary particles are composed of a large number of crystals, and the crystals are composed of a large number of microcrystals, such as... Figure 1 As illustrated herein. Although the invention is described below with respect to LNMO materials, preferably cobalt-free (Co) LNMO materials with B modification, the invention is applicable to any LNMXO cathode active spinel-type material having a similar crystal structure, wherein X comprises one or more elements as defined herein, and wherein X may partially replace Ni and / or Mn in the LNMO material.

[0021] This invention achieves boron modification of LNMO microparticles through high-temperature synthesis using LNMO microparticles and boric acid as the boron source, which will also be referred to as "boron treatment". As described herein, during this high-temperature synthesis, boron is expected to act as a modifying element, resulting in a boron phase at and / or within the grain boundaries of the LNMO microparticles. Boron may also exist as a bulk dopant or surface dopant within the material, or may form a separate phase along the grain boundaries, a surface coating, or simply as a flux, or any combination thereof. Therefore, the boron modification of this invention involves introducing boron (B) into the grain boundaries, surface phase, or surface and bulk phase of the LNMO material. Boron may exist as a B-based inorganic compound, including B₂O₃, Li₂B₄O₇, LiBO₂, Li₂B₂O₅, LiB₅O₈, or LiB₃O₅. B may also exist as a Li-BO glassy phase or as an amorphous phase.

[0022] However, the treatment can also result in boron presence within the grain boundaries of LNMO materials, leading to boron segregation in different grains. Therefore, even though the modification may be termed "surface modification," this does not preclude the possibility that the modification can also exist at the grain boundaries or within the secondary particles. Thus, within the scope of this invention, boron modification is not merely surface modification, but can also achieve boron doping within secondary particles or segregation at grain boundaries. Typically, boron modification is uniformly distributed on the surface of the particles.

[0023] The boron-modified lithium nickel manganese oxide (LNMO) material of the present invention is typically a cobalt-free lithium nickel manganese mixed oxide, which may contain additional elements, such as one or more elements selected from Mg, Ca, Zn, Fe, Al, Ti, Mo, W, Ta, Zr, B, Si, Cr, and Cu. These elements (multiple elements) may be present in the LNMO material, or may partially replace Ni and / or Mn in the LNMO material, in addition to Ni and Mn. Therefore, the LNMO material of the present invention can also be defined as an LNMXO material, where X is one or more elements as defined above. In this embodiment, the LNMXO material can also be defined by the following formula:

[0024] (i)LiNi 0.5-a X a Mn 1.5 O4, or

[0025] (ii)LiNi 0.5 X a Mn 1.5-a O4,

[0026] Where a is 0 to 0.1, preferably 0.01 to 0.06.

[0027] Most preferably, the LNMO material is high-voltage spinel LiNi. 0.5 Mn1.5 O4 material. The LNMO material of this invention is suitable for use as a positive electrode active material in secondary lithium-ion batteries. The morphology of the sample can be examined using a scanning electron microscope (SEM), and the type, content, and distribution of elements in the LNMO material can be examined using an energy-dispersive spectroscopy (EDS) instrument.

[0028] The microparticle structure of LNMO materials Figure 1 The diagram illustrates this. As shown, the LNMO particulate material comprises secondary particles, which are composed of a large number of relatively small crystals. These crystals consist of a large number of microcrystals.

[0029] The secondary particles are typically spherical. Preferably, the sphericity of the secondary particles is 1.0 to 0.70, more preferably 0.99 to 0.80, and even more preferably 0.98 to 0.90. The sphericity can be determined by methods well known in the art, and is preferably determined by the cross-section of the secondary particles.

[0030] As measured by laser diffraction according to ISO 13320:2020, the D of secondary particles... 50 The particle size is from 3.0 µm to 25 µm, and preferably from 5.0 µm to 20 µm, and more preferably greater than 5.0 µm, 6.0 µm, 7.0 µm, 8.0 µm, 10 µm or 12 µm, and more preferably less than 18 µm, 16 µm or 14 µm.

[0031] As measured by scanning electron microscopy (SEM), crystals can also be called "primary particles," and their D... 50 The particle size is from 0.3 µm to 7.0 µm, and preferably from 0.5 µm to 5.0 µm, and more preferably greater than 1.0 µm, 1.5 µm or 2.0 µm, and more preferably less than 6.0 µm, 5.0 µm or 4.0 µm.

[0032] As determined by XRD Rietveld refinement (Rietveld, HM (1969). “A profile refinement method for nuclear and magnetic structures”. Journal of Applied Crystallography. 2 (2): 65-71), the crystallite size is 90 nm to 600 nm, preferably 100 nm to 500 nm, and more preferably 200 nm to 450 nm. XRD measurements were performed using a Bruker D8 X-ray diffraction analyzer (Bruker, Germany). The crystallite shape is typically tetrahedral, octahedral, and / or truncated octahedral, or a mixture thereof. Using the methods described below, boron-modified LNMO crystallites can be transformed into a mixture of tetrahedral, octahedral, and (truncated) octahedral shapes, which improves the electrochemical properties of the material by providing a more stable surface.

[0033] Boron-modified LNMO materials typically have the space group Fd-3m cubic phase and are also referred to in the art as "disordered spinel" materials. Alternatively, the materials may also have the space group P4332, which is referred to in the art as "ordered spinel" materials. Typically, trace amounts of Li can be detected in both materials. x Ni 1-x O, due to the absence of nickel or oxygen, is frequently found in disordered LNMO materials. This impurity phase can be eliminated by synthesizing non-stoichiometric spinel LNMO materials. Stoichiometric spinel is generally defined in this art as LiNi. 0.5 Mn 1.5 O4 (with space group P4332 in XRD analysis, also commonly referred to in the art as "ordered LNMO"). Depending on the starting materials and method conditions, the particulate materials of the present invention can also form non-stoichiometric compositions (with Fd-3m structures in XRD analysis, commonly referred to as "disordered LNMO"). Disordered materials can be defined by the following formula:

[0034] (I)LiNi 0.5-x Mn 1.5+x O4 (nickel deficiency)

[0035] (II) LiNi 0.5-x Mn 1.5+x O 4-d (Nickel deficiency and oxygen deficiency)

[0036] (III) LiNi 0.5 Mn 1.5 O 4-d (Hypoxia)

[0037] Where d and x are typically independent and range from 0 to 0.1, preferably from 0.01 to 0.06.

[0038] The crystal structure of LNMO materials can be analyzed by XRD measurement and Bruker D8 X-ray diffraction analysis (Bruker, Germany).

[0039] The present invention unexpectedly discovered that boron treatment of LMNO materials as described herein significantly improves the stability of the materials in half-cells and further enhances their rate performance and capacity retention performance.

[0040] In a preferred embodiment, the boron modification is B2O3 and / or Li2B4O7 modification or contains B2O3 and / or Li2B4O7 modification. Therefore, the modification comprises B2O3 and / or Li2B4O7 and / or a glass-like phase, and preferably consists of B2O3 and / or Li2B4O7 and / or a glass-like phase. Depending on the coating method, the modification may also consist of other lithium borate phases or mixtures thereof, or contain other lithium borate phases or mixtures thereof. Using the methods described below, B can be uniformly dispersed on the surface of the LNMO material, resulting in uniform particles with small differences in particle size and B content between particles.

[0041] Because the boron content (or amount of boric acid) has a significant impact on the morphology of LNMO materials, the amount of boric acid used in the LNMO materials of this invention is limited, and is typically 0.01 to 4.0% by weight, and preferably 0.05% to 3.0% by weight, based on the weight of the LNMO material. Most preferably, the amount of boric acid used is 0.05 to 2.5% by weight, such as 0.05 to 2.0% by weight, based on the weight of the LNMO material. Since the amount of inactive boron in the material is relatively high, if the amount of boron exceeds the upper limit, the capacity of the material may decrease. Conversely, if the amount of boron in the LNMO material is below the lower limit, the cycling performance and stability of the material may not improve, and the desired effect may not be achieved.

[0042] Alternatively, the amount of boron present in the LNMO material of the present invention can be calculated as the molar ratio of B to the transition metals nickel and manganese. Therefore, the molar ratio of B / (Ni+Mn) is preferably from 0.0003:0.04 to 0.0004:0.03, and more preferably 0.0006:0.025. The elemental content and molar ratio can be analyzed and calculated using inductively coupled plasma optical emission spectrometry (ICP-OES).

[0043] This invention unexpectedly reveals that the size and shape of boron-modified particles can be advantageously controlled by the calcination temperature and the amount of boron present in the boron-modified LNMO material. Since boron significantly increases crystallite growth, particle size and morphology can be modified and controlled based on the amount of boron. Furthermore, boron is believed to act as a flux between LNMO particles, thus stabilizing particle integrity and achieving improved material stability.

[0044] from Figure 2 It is evident that higher calcination temperatures result in significantly larger crystal sizes in B-LNMO materials. Therefore, heat treatment temperatures of 700°C or lower yield primary crystals in the 90-140 nm range, while temperatures of approximately 900°C or higher produce even larger primary crystals, as described above. Thus, the properties of boron-modified materials can be advantageously designed by utilizing the amount of boric acid in the boron-modified particles and the calcination temperature.

[0045] The large secondary particles of the material in this invention result in high tap density and low specific surface area. The low specific surface area of ​​the boron-modified LNMO of this invention can further improve cycle stability by reducing oxidative decomposition of the electrolyte and dissolution of metal ions from the cathode material, forming a more stable LNMO / electrolyte interface. Furthermore, the particulate material exhibits high particle density and low porosity.

[0046] Therefore, as determined by Brunauer-Emmett-Teller (BET) surface area analysis, the specific surface area of ​​LNMO microparticles is preferably 0.1 to 0.5 m². 2 / g.

[0047] The tap density of the LNMO microparticle material according to the present invention is typically higher than 2.0 g·cm³. -3 Furthermore, it can achieve a value close to the theoretical maximum value for the packing of spherical particles of the same size, approximately 3.3 g·cm³. -3 Furthermore, the tap density can be even higher, depending on the particle size distribution. Therefore, as determined according to ASTM B527-20, the tap density of the particulate material of the present invention is preferably 2.2 to 3.0 g·cm³. -3 More preferably 2.4 to 2.8 g·cm³ -3 The optimal value is approximately 2.6 g·cm³. -3 .

[0048] The boron-modified LNMO material of the present invention can be advantageously used as a stable and high-capacity cathode material in Li-ion batteries.

[0049] Method for manufacturing boron-modified LNMO particulate materials

[0050] The boron-modified particulate LNMO material of the present invention can be obtained by a method in which the particulate LNMO material (also referred to herein as precursor material or LNMO precursor) is mixed with a boron (B) source and subsequently calcined. This method is carried out by a wet process, i.e., a solution-based process, by a semi-dry (initial wet) process in which only a small amount of solvent is used, and by a dry process.

[0051] In the wet process, the B source is typically provided as a solution, which is mixed with a solution or slurry of LNMO in a solvent. The wet process generally includes the following steps (a) to (d):

[0052] (a1) Mix the particulate LNMO material with an aqueous solvent;

[0053] (a2) Provide a solution of boric acid in an aqueous solvent;

[0054] (b) Mix the LNMO material with a boric acid solution;

[0055] (c) Remove the aqueous solvent to obtain a dry mixture;

[0056] (d) The mixture was calcined in an oxygen-containing atmosphere at a temperature of 700°C to 1100°C to form boron-modified LNMO microparticles.

[0057] The semi-dry process typically includes the following steps (a) to (d):

[0058] (a1) Provides particulate LNMO materials in powder form;

[0059] (a2) Provide a solution of boric acid in an aqueous solvent;

[0060] (b) While mixing, add boric acid solution to the LNMO material;

[0061] (c) Remove the aqueous solvent to obtain a dry mixture;

[0062] (d) The mixture was calcined in an oxygen-containing atmosphere at a temperature of 700°C to 1100°C to form boron-modified LNMO microparticles.

[0063] Dry processing typically includes the following steps (a) through (d):

[0064] (a1) Provides particulate LNMO materials in powder form;

[0065] (b) While mixing, dry boric acid is added to the LNMO material;

[0066] (d) The mixture was calcined in an oxygen-containing atmosphere at a temperature of 700°C to 1100°C to form boron-modified LNMO microparticles.

[0067] As described above, while the boron (B) source is typically boric acid, other boron-containing compounds may be used instead of boric acid, or other boron-containing compounds may be used in addition to boric acid. Suitable boron-containing compounds for use as a boron source in the methods of this invention include, but are not limited to, one or more of boron trifluoride (BF3), boron phosphate (BPO4), or borane (B2H6). Additionally, organoboron compounds, including, for example, triethyl borate, diethyl borate, diethyl borate, ethyl borate, tetraethyl borate, borate ester complexes, borate diesters, and boron ethoxide compounds, may also be used as boron sources.

[0068] The solvent used in steps (a1) and / or (a2) is typically water, but can also be any solvent suitable for dissolving the boron source, such as boric acid. Therefore, organic solvents, such as ethanol or isopropanol, or mixtures of water with (a variety of) organic solvents, can also be used, provided the reaction conditions are adjusted accordingly.

[0069] In the wet process, the concentration of the boric acid solution is typically from 5.0 g / L to 160 g / L, and preferably from 60 g / L to 160 g / L. Furthermore, in the wet process, the total amount of solvent used per unit volume of LNMO material is typically from 3 to 12 l (solvent) / kg (LNMO), preferably from 4 to 10 l / kg, more preferably from 4 to 8 l / kg, and optimally from about 5.0 l / kg.

[0070] Conversely, in the semi-dry process, the concentration of the boric acid solution is typically from 10.0 g / L to 300 g / L, and preferably from 15 g / L to 250 g / L. If the concentration of the boric acid solution is higher than these upper limits, a uniform distribution of boron on the LNMO surface may not be achieved. If the concentration of the boric acid solution is lower than these lower limits, the beneficial effects of improved rate stability and electrochemical performance may not be achieved. Furthermore, in the semi-dry process, the total amount of solvent used per unit volume of LNMO material is typically 0.5 to 3.0 l (solvent) / kg (LNMO), preferably 0.6 to 2.0 l / kg, more preferably 0.8 to 1.5 l / kg, and optimally about 1 l / kg.

[0071] The LNMO material used in step (a) can be synthesized at 700°C, or even at lower temperatures of 400-700°C.

[0072] Steps (a) and (b) are typically performed at temperatures ranging from 0°C to 90°C, such as at room temperature of 20-25°C, or at temperatures ranging from 40°C to 60°C.

[0073] In the semi-dry process, boric acid solution is usually added dropwise to LNMO powder and mixed simultaneously to obtain a mud-like mixture, i.e., a semi-dry mixture.

[0074] Step (b) typically involves mixing the boric acid solution and the LNMO precursor. Mixing can be carried out at the aforementioned temperatures, for example, with continuous stirring for 1–12 hours, such as 2–6 hours. In a semi-dry process, stirring can continue until the boric acid solution is completely added.

[0075] In the wet process, the solvent is typically removed in step (c) by evaporation under atmospheric or reduced pressure, such as in a rotary evaporator, for example, at 100 to 400 mbar. Depending on the solvent used, solvent removal is typically carried out at room temperature, such as 20-25°C, or at elevated temperatures, such as 30°C to 90°C.

[0076] Drying is routinely carried out at a temperature above the boiling point of the solvent used in the method. In the case of water, drying is typically carried out at a temperature of 100°C to 150°C, for example, 100°C to 120°C, until complete removal of the solvent is achieved.

[0077] In a further embodiment, the method may also include a pre-calcination step, in which the mixture obtained in step (b) is treated at a temperature of 250°C to below 700°C for 2-8 hours. The pre-calcination temperature is typically lower than the temperature used in the subsequent calcination step (d).

[0078] The oxygen-containing atmosphere in step (d) is usually air, but it can also be any oxygen-containing atmosphere, including pure oxygen.

[0079] Calcination (step (d)) is typically carried out at 700°C to 1100°C, preferably at 750°C to 1000°C, and more preferably at about 900°C. During the heat treatment, LNMO crystallizes, and boric acid may decompose and react with the LNMO surface to achieve boron modification. It has been unexpectedly discovered that the size and shape of the boron-modified particles can be advantageously controlled using the calcination temperature. Furthermore, the growth of primary crystals with specific shapes during heat treatment results in excellent electrochemical performance. Figure 2 It is evident that higher calcination temperatures result in larger crystal sizes. Therefore, calcination temperatures of 800°C to 1000°C produce secondary particles composed of larger crystals; while temperatures of 700°C or lower yield secondary particles composed of nano-sized (primary) crystals. Thus, the properties of boron-modified materials can be advantageously controlled by calcination temperature.

[0080] Temperatures above 900°C can lead to the formation of oxygen-deficient phases. These oxygen-deficient phases often contain undesirable amounts of NiO or Li. x Ni 1-xO (x is typically 0 to 0.1), indicating partial decomposition of LNMO, which may result in lower capacity of the generated particulate material. Subsequent annealing at lower temperatures, such as 600°C to 800°C, preferably 650°C to 750°C, for example, around 700°C, can lead to the reintegration of oxygen into the lattice and the reintegration of the separated NiO phase to form LNMO with the P4332 space group, resulting in greater capacity. Furthermore, as mentioned above, LNMO with the Fd-3m space group can form a Ni-deficient phase. Therefore, performing an annealing step after the calcination step is likely desirable.

[0081] Calcination is usually carried out for 2 to 24 hours, preferably 6 to 20 hours, and most preferably 8 to 16 hours.

[0082] In an alternative embodiment, the method of the present invention relates to a lithium-free (Li) precursor material mixed with a boron source as described above. In this embodiment, the mixture of the lithium-free precursor material and the boron source is subsequently treated with a lithium (Li) source.

[0083] Therefore, this alternative method for manufacturing boron-modified lithium nickel manganese oxide (LNMO) particulate materials typically includes the following steps:

[0084] (a) Mixing a nickel-manganese-containing particulate precursor material with a solution of boric acid in water or an aqueous solvent;

[0085] (b) Remove water or aqueous solvent to obtain a dry mixture;

[0086] (c) Add a lithium source (e.g., lithium hydroxide and / or lithium carbonate) to the dried mixture obtained in step (b); and

[0087] (d) The mixture was calcined in an oxygen-containing atmosphere at a temperature of 700°C to 1100°C to form boron-modified LNMO microparticles.

[0088] In this embodiment, a lithium-free precursor material can be used. The (typically lithium-free) nickel-manganese precursor material may contain transition metals, i.e., nickel and manganese-containing carbonates, oxides, or hydroxides, such as nickel-manganese carbonates, nickel-manganese oxides, or nickel-manganese hydroxides, which may contain additional elements as described above. The precursor material can be obtained substantially by methods described herein, such as spray drying, hydrothermal methods, or co-precipitation. The precursor material is mixed with a boron source as described above. The resulting mixture is then mixed with a lithium source, such as lithium carbonate or lithium hydroxide, and calcined as described above. Therefore, for steps (c) and (d), the above description of the method of the present invention for obtaining B-modified particulate material using a lithium-containing LNMO precursor material is applied in the same manner to this alternative embodiment using a (typically lithium-free) precursor, wherein the Li source is added only in a subsequent step after mixing the precursor material with the B source. Furthermore, an additional heat treatment step may be performed after step (b), typically carried out at a temperature in the range of 300-700°C for 4-12 hours.

[0089] Preparation of LNMO precursor materials

[0090] There are no particular limitations on the LNMO precursor materials used in the above methods, and they can be obtained by methods described in the art, such as spray drying, hydrothermal methods, or coprecipitation. Coprecipitation is a feasible commercial method with benefits such as scalability, allowing control over particle size and morphology, and low cost, and is therefore preferred for the preparation of LNMO precursor materials.

[0091] In addition to these methods, combinatorial methods are described, in which a precursor, such as a transition metal carbonate, oxide, or hydroxide, is prepared by co-precipitation and then reacted with a stoichiometric amount of a lithium compound to generate the final product. Co-precipitation can be carried out with or without an additional cryogenic heating step, typically at temperatures between 300 and 600°C. Such a cryogenic heating step is necessary for the formation of oxides. In lithium-ion battery materials, co-precipitation is currently widely used to manufacture transition metal hydroxide precursors. However, alternatively, co-precipitation using carbonate precursors can be used.

[0092] For example, LNMO precursor materials can be obtained by batch or continuous co-precipitation methods.

[0093] For example, DE102023116756.1 describes a continuous co-precipitation method. In a first method step, an aqueous solution of a transition metal salt is continuously mixed with an aqueous solution of a carbonate in a continuously stirred reactor in the presence of an aqueous solution of an organic additive. Continuous mixing results in the continuous precipitation of the transition metal carbonate in the reactor. Thus, the precipitated transition metal carbonate exists in the reactor as a solid suspension and can be continuously removed.

[0094] In a preferred embodiment, the co-precipitation method includes the following steps:

[0095] (i) Provide a solution containing ammonia, manganese salt, and nickel salt to obtain a nickel-manganese hydroxide precursor.

[0096] (ii) Mix the nickel-manganese hydroxide precursor with lithium hydroxide, and

[0097] (iii) Calcine at 400°C to 900°C for 6-20 hours in an oxygen-containing atmosphere.

[0098] There are no particular limitations on the manganese and / or nickel salts, and any salt can be sufficient to be water-soluble as a solution under the reaction conditions applied during the coprecipitation process. Typically, at least one of the manganese and nickel salts is a nitrate or a sulfate, with nitrates being particularly preferred.

[0099] Nickel and manganese salts are typically used in a specific ratio to achieve a Mn / Ni stoichiometry of 4:1 to 2:1, such as about 3:1. Alternatively, nickel and manganese salts are typically used in a specific ratio to achieve a N... i0.5-x Mn 0.5+x The stoichiometry, where x is between 0 and 0.6.

[0100] Typical methods include LNMO precursor materials, such as those derived from Ni. 0.25 Mn 0.75 The hydroxide precursor obtained from (OH)₂ is impregnated with LiOH, such as LiOH·H₂O, and heated at a temperature of 400°C to 700°C, for example, about 450°C, for 2-10 hours, such as about 6 hours. In a preferred embodiment, boric acid is provided as a solution and added to the LNMO material. The material mixture can be heated to 700-1100°C, most preferably at about 850°C to 900°C for 6-16 hours, such as about 12 hours.

[0101] The LNMO precursor material obtained by the above method is preferably a particulate material containing D 50 The particle size is 4 µm to 30 µm, preferably 7 µm to 20 µm spherical particles.

[0102] Therefore, on the other hand, the present invention provides a boron-modified LNMO material, such as B2O3 or Li2B4O7 modified material, which can be obtained by the methods described herein, preferably by the co-precipitation method described herein.

[0103] Attached Figure Description

[0104] Figure 1Schematic illustration of boron-modified LNMO secondary particles, which are composed of crystals and microcrystals.

[0105] Figure 2 SEM images of boron-free (BF1) and boron-modified LNMO particles synthesized at heat treatment temperatures of 300°C (B1) and 900°C (B2).

[0106] Figure 3 SEM images of boron-free (BF2 and BF3) and boron-modified (B3-B10) LNMO materials synthesized at 850°C and 900°C using different amounts of boric acid.

[0107] Figure 4 SEM images of boron-free (BF2, BF3, and BF4) and boron-modified (0.125 wt%) LNMO (B11-B14) materials synthesized at different heat treatment temperatures (850-1000°C).

[0108] Figure 5 XRD patterns of boron-free (BF1) and boron-modified (B1 and B2) LNMO materials.

[0109] Figure 6 Rate performance and cycling performance of boron-free (BF1) and boron-modified (B1 and B2) LNMO materials.

[0110] Figure 7 Comparison of charge-discharge curves of boron-free (BF1) and boron-modified (B1 and B2) LNMO materials. Example

[0111] The present invention will be further illustrated and described below through non-limiting experimental embodiments.

[0112] The following lists the acronyms for boron-free LNMO (BF-LNMO) materials and synthesized boron-modified materials (B-LNMO), as described in the examples below. The numbers next to the acronyms indicate different samples synthesized under different synthesis conditions (temperature or degree of boron modification).

[0113] Methods / Materials acronym sample LNMO without B*(BF-LNMO) BF BF1-BF4 B-modified LNMO (B-LNMO) B B1-B14

[0114] *Comparative materials for reference purposes

[0115] Example 1 - Precursor Synthesis

[0116] High-density LiNi was synthesized using a two-step method. 0.5 Mn 1.5O4 (LNMO): (1) Precursor synthesis; (2) Precursor lithiation. First, the precursor Ni was synthesized in a continuously stirred reactor (CSTR) using a co-precipitation technique. 0.25 Mn 0.75 (OH)₂. This involves using an aqueous solution containing ammonia, nickel nitrate, and manganese nitrate, maintaining a 3 / 1 Mn / Ni ratio. Co-precipitation yields dense, spherical particles with micron-sized particles. Subsequently, the synthesized precursor is mixed with lithium hydroxide and calcined in ambient air at 450–700 °C for 6–20 hours for different sample materials, yielding LNMO. This LNMO precursor material is then used to synthesize B-modified LNMO materials.

[0117] Example 2 - Boron Treatment

[0118] 2.1 Wet coating method

[0119] First, 70 mL of distilled water (DI) was transferred to a beaker (solution 1) and heated to 70°C with continuous stirring. Then, 10 g of LNMO was added to solution 1. Simultaneously, 20 mL of DI was added to another beaker (solution 2) at 60°C and stirred for 15 minutes. Next, boric acid (H3BO3) corresponding to the target amount of B in B-LNMO was added to solution 2 and stirred for another 30 minutes. Finally, the boric acid solution (solution 2) was added dropwise to solution 1. The temperature was raised to 70°C, and the LNMO / H3BO3 was stirred for approximately 6 hours. The solution was then transferred to a rotary evaporator (Büchi) to remove the DI water. The rotary evaporator water bath temperature was set to 70°C, and a pressure of 220 mbar was applied to remove the DI water. The LNMO / H3BO3 was then transferred to a drying oven set at 120°C and left overnight. Finally, LNMO / H3BO3 was heat-treated at different temperatures (800℃, 850℃, 900℃, and 1000℃) to synthesize B-LNMO materials. For B-free LNMO (BF-LNMO) materials, LNMO was heat-treated only at 800℃, 850℃, 900℃, and 1000℃.

[0120] 2.2 Semi-dry method (initial wet method)

[0121] First, a boric acid solution was prepared by adding boric acid to DI water and stirring continuously at 70°C for 15 minutes. The amount of boric acid was adjusted to meet the boron (B) content required for the B-modified LNMO material. Furthermore, the total solvent used for each volume of LNMO material was 1 L / kg. Simultaneously, 5 g of LNMO material was placed in a mortar and pestle. Then, while continuously stirring, the boric acid solution was added dropwise to the dried LNMO material to ensure uniform distribution of H3BO3 on the LNMO particles. This process yielded a clay-like material. The LNMO / H3BO3 mixture was then dried overnight in an oven at 120°C to remove the solvent. Finally, the LNMO / H3BO3 was heat-treated at different temperatures (800°C, 850°C, 900°C, and 1000°C) to synthesize the B-modified LNMO material, achieving the desired modification. For boron-free LNMO (BF-LNMO) materials, LNMO is heat-treated only at 800℃, 850℃, 900℃ and 1000℃.

[0122] 2.3 Dry coating method

[0123] In this method, LNMO material is manually mixed with boric acid. The amount of boric acid is adjusted to obtain the boron (B) content required for B-modified LNMO material. Subsequently, LNMO / H3BO3 is heat-treated at different temperatures (800℃, 850℃, 900℃, and 1000℃) to synthesize B-modified LNMO material, achieving the desired modification.

[0124] Example 3 - SEM imaging of B-modified LNMO material

[0125] Figure 2 SEM images of boron-free LNMO (BF-LNMO) and boron-modified LNMO (B-LNMO) materials synthesized at different synthesis temperatures using the wet coating method described in Example 2.1 were compared. The BF1 and B1 materials showed very similar morphologies, and no differences were found even after boric acid treatment. Here, the BF1 material was synthesized at 700 °C, subsequently treated with boric acid, and calcined at 300-400 °C for 6 hours to form the B1 material. Furthermore, as listed in Table 2, the crystallite size and lattice parameters were also very similar. On the other hand, increasing the calcination temperature of the B-LNMO material (B2) to 900 °C significantly affected the morphology of the material. The primary crystals increased significantly in size, ranging from 1.5 to 7 µm. The larger primary crystals also led to a decrease in the material surface area.

[0126] Figure 3SEM images of BF-LNMO and B-LNMO materials synthesized with different amounts of boric acid, as well as those synthesized at 850℃ and 900℃, were compared. It can be seen that the BF-LNMO material contains many small primary crystals, and the addition of even a small amount of boric acid (even 0.125 wt%) significantly affects the size and shape of the primary crystals. Furthermore, with the addition of boric acid, the primary crystals exhibit a mixture of tetrahedral, octahedral, and truncated octahedral shapes. As seen in the B8, B9, and B10 materials, increasing the synthesis temperature and the amount of boric acid slightly alters the shape of the primary crystals, transforming them into randomly shaped primary crystals. Therefore, it can be observed that lower temperatures and lower amounts of boric acid tend to form a mixture of tetrahedral, octahedral, and truncated octahedral primary particles, while higher synthesis temperatures and higher amounts of boric acid result in randomly shaped primary crystals.

[0127] Because lower temperatures and lower amounts of boric acid resulted in primary particles with tetrahedral, octahedral, and truncated octahedral shapes, BF-LNMO and B-LNMO (0.125 wt% H3BO3) were synthesized at different heat treatment temperatures. Figure 4 SEM images were compared. It can be seen that BF-LNMO and B-LNMO materials exhibit completely different morphologies, especially related to the morphology of the primary crystals. First, it is clear that even a small amount of boric acid (0.125 wt%) has a significant impact on the morphology of the materials. With increasing synthesis temperature, BF-LNMO materials show larger primary grains. On the other hand, B-LNMO materials show a mixture of tetrahedral, octahedral, and truncated octahedral primary crystals. Lower synthesis temperatures of around 850 °C yield smaller primary crystals. However, increasing the synthesis temperature to 900 °C (BM12) and above significantly increases the size of the primary crystals. B14 materials synthesized at 1000 °C show much larger primary crystals; however, the secondary grains still remain large spherical particles.

[0128] Furthermore, the primary particles (B2) of B-LNMO synthesized at temperatures above 700°C transform into a mixture of tetrahedral, octahedral, and (truncated) octahedral shapes. Figure 3 , 4 It is known that it provides more stable surface-enhanced electrochemical properties.

[0129] Furthermore, by controlling the synthesis conditions (calcination temperature and B concentration), the size of the primary crystals can be controlled. Figure 3 , 4 Therefore, the physical and electrochemical properties of B-LNMO can be controlled over a wide range.

[0130] Larger secondary particles result in high tap density and low specific surface area (0.2 m² for B-LNMO). 2 g -1 The lower specific surface area of ​​B-LNMO can also improve cycle stability by reducing the oxidative decomposition of the electrolyte and the dissolution of metal ions from the cathode material, resulting in a more stable LNMO / electrolyte interface.

[0131] Example 4 – XRD Measurement of B-Modified LNMO Material

[0132] The LNMO materials prepared in Examples 2.1, 2.2 and 2.3 were analyzed by XRD measurement.

[0133] Figure 5 The illustrations show the XRD patterns of the BF-LNMO (BF1) and B-LNMO materials (B1-B2) prepared in Example 2.1. Depending on the synthesis conditions, they can be identified as P4332 or Fd3̅m cubic phases. BF1 and B1 synthesized at 700°C, as well as B1 heat-treated at 300-400°C after boron treatment, can be identified as P4332 because superlattice peaks are clearly visible. On the other hand, B2 synthesized at 900°C can be identified as an Fd3̅m cubic phase because no superlattice peaks were observed. Furthermore, trace amounts of NiO or Li were detected in the B2 material synthesized at 900°C. x Ni 1-x O, which is typically found in LNMO materials synthesized at temperatures above 700°C due to a lack of nickel or oxygen.

[0134] Table 1 presents the ICP results for BF-LNMO (BF1) and B-LNMO materials (B1), confirming their near-stoichiometric composition (Mn / Ni≈3 / 1). Both BF-LNMO and B-LNMO materials exhibit a spherical morphology with micron-sized secondary particles. 50 They are approximately 14 µm and 17.5 µm, respectively.

[0135] Table 1: ICP analysis results of B-free LNMO and B-modified LNMO (B-LNMO).

[0136]

[0137] The crystallite size of BF-LNMO (BF1) is approximately 116.3 nm, while that of B-LNMO (B1) calcined at 300°C is approximately 117.4 nm. However, at higher synthesis temperatures, the crystallite size increases significantly (but is controllable). Furthermore, the lattice parameters and cell volume of the B-LNMO material (B2) synthesized at 900°C show a slight increase. Refined parameters and particle size are listed in Table 2.

[0138] Table 2: Rietveld refinement parameters and particle size distribution of BF and B-LNMO.

[0139]

[0140] Example 5 - Electrochemical Results

[0141] All electrochemical measurements were performed using a standard electrolyte (1M LiPF6 EC: DMC 1:1 wt%) without any stabilizing additives. The active material loading was 9-10 mg cm⁻¹. -2 All measurements were performed in a coin cell (CR2023) configuration. Lithium metal (450 µm) was used as the counter electrode, and two glass fiber sheets were used as the separator. 150 µl of electrolyte was used for all cells, and all half-cell measurements were performed at 25 °C.

[0142] Figure 6 The figure illustrates a comparison of the rate performance of BF-LNMO (BF1) and B-LNMO (B1 and B2). Clearly, BF1 and B1 exhibit slightly higher discharge capacities at low C rates compared to B2. The lower initial discharge capacity of B2 is primarily due to the presence of electrochemically inert rock salt Li. x Ni 1-x The presence of an O impurity phase leads to a lower initial discharge capacity due to the electrochemically inert phase. Furthermore, applying an additional annealing treatment of approximately 700°C to these materials reduces the impurity phase, resulting in a higher initial discharge capacity. However, it can be observed that B-LNMO materials exhibit significantly better rate performance compared to BF-LNMO. Moreover, B-LNMO (B2), synthesized at 900°C, exhibits the best rate performance, even with significantly larger primary crystal sizes. This trend is similar when the materials are cycled at 1C. B2 shows the highest discharge capacity and best stability. BF-LNMO (BF1) shows lower discharge capacity and lower stability. Therefore, it can be concluded that B-modified materials have faster kinetics and higher stability compared to B-free LNMO materials.

[0143] In addition, by measuring rate performance, cycle performance, and half-cell performance (LNMO relative to Li / Li), + The electrochemical performance of the B-LNMO material prepared in Example 2.1 was analyzed by using the constant current charge / discharge curves in the figure.

[0144] Figure 7Compare the charge and discharge curves of BF1, B1, and B2 materials. XRD patterns show that materials BF1 and B1 can be labeled P4332, which is commonly referred to as ordered LNMO in the literature. Such materials exhibit high charge and discharge performance at approximately 4.7 V (relative to Li / Li). + B1 exhibits a single high-voltage plateau at approximately 4.0 V. On the other hand, B2, belonging to the Fd3̅m space group, is commonly referred to as disordered LNMO and shows an additional low-voltage plateau at around 4.0 V. Therefore, materials BF1 and B1 show a single high-voltage plateau at approximately 4.7 V. Furthermore, it can be seen that B1 exhibits a higher initial discharge capacity compared to BF1. B modification results in a higher discharge capacity. The B2 material also exhibits a 4.0 V plateau, which represents Mn. 3+ / Mn 4+ The redox pair is due to oxygen loss from the LNMO structure during high-temperature synthesis. Compared to BF1 and B1, the B2 material exhibits a slightly lower initial discharge capacity. The lower capacity is attributed to the electrochemically inert rock salt Li in the B2 material. x Ni 1-x The presence of the O impurity phase.

[0145] In summary, experiments demonstrate that boron modification of LNMO materials significantly improves their stability in half-cells. Furthermore, compared to B-LNMO (B1) synthesized at 700 °C, B-LNMO material (B2) synthesized at 900 °C exhibits even better rate performance and cycling stability. Therefore, due to boron treatment, specific primary particle shape, and design, the novel boron-modified LNMO materials according to the present invention demonstrate significantly enhanced stability. Compared to BF-LNMO, B-LNMO exhibits superior rate performance and long-term cycling performance.

Claims

1. A lithium nickel manganese oxide (LNMO) particulate material, wherein the LNMO particulate material comprises secondary particles. The secondary particles are composed of a large number of crystals, and the crystals are composed of a large number of microcrystals. The D of the secondary particles, as measured by laser diffraction according to ISO 13320:2020, is... 50 The particle size ranges from 3.0 µm to 25 µm, and The D of the crystal, as measured by scanning electron microscopy (SEM), is among them. 50 The particle size ranges from 0.3 µm to 7.0 µm, and in, The LNMO microparticle material is boron modified.

2. The LNMO microparticle material according to claim 1, wherein the D0 of the secondary particles, as measured by laser diffraction according to ISO 13320:2020, is... 50 The particle size ranges from 5.0 µm to 20 µm.

3. The LNMO microparticle material according to claim 1 or 2, wherein the D of the crystal, as measured by SEM, is... 50 The particle size ranges from 1.0 µm to 5.0 µm.

4. The LNMO microparticle material according to any one of the preceding claims, wherein the crystallite size is 90 nm to 600 nm, as measured by XRD Rietveld refinement.

5. The LNMO particulate material according to any one of the preceding claims, wherein the boron modification comprises B2O3 or Li2B4O7.

6. The LNMO particulate material according to any one of the preceding claims, wherein the molar ratio of B / (Ni+Mn) is 0.0003-0.

04.

7. Use of the LNMO particulate material according to any one of the preceding claims as a positive electrode material in a lithium-ion battery.

8. A method for manufacturing boron-modified lithium nickel manganese oxide (LNMO) particulate materials, the method comprising the following steps: (a) Mixing particulate LNMO material with a solution of boric acid in an aqueous solvent, (b) Remove the aqueous solvent to obtain a dry mixture. (c) The mixture is calcined in an oxygen-containing atmosphere at a temperature of 700°C to 1100°C to form boron-modified LNMO particulate material.

9. The method of claim 8, wherein the method further comprises a pre-calcination step of treating the mixture of step (b) at a temperature of 300°C to below 700°C for 2 to 8 hours.

10. The method according to claim 8 or 9, wherein the calcination step (c) is carried out at a temperature of 800°C to 1000°C for 6 to 20 hours.

11. The method according to any one of claims 8-10, wherein the mixing in step (a) is carried out at a temperature of 25°C to 90°C.

12. A boron-modified LNMO material, which can be obtained by the method according to any one of claims 8-11.

13. The use of the LNMO particulate material according to any one of claims 1-6, the use of the LNMO particulate material according to claim 7, the method according to any one of claims 8-11, or the boron-modified LNMO material according to claim 12, wherein the space group of the boron-modified LNMO material is Fd-3m cubic phase.

14. The LNMO particulate material according to any one of claims 1-6 or 12-13, the use of the LNMO particulate material according to claim 7, the method according to any one of claims 8-11, or the boron-modified LNMO material according to claims 12-13, wherein the LNMO particulate material is defined by the following formula: LiNi 0.5-x Mn 1.5+x O4, Where x is 0 to 0.1, preferably 0.01 to 0.06.

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