Positive electrode active material and its preparation method, positive electrode plate, and secondary battery

Abstract

This application relates to a positive electrode active material, a method for preparing the same, a positive electrode plate, and a secondary battery. The compositional chemical formula of the positive electrode active material is Li x Na 1-x A y B 1-y O 2-n D n where A is selected from the composition of Ni and Mn, B is selected from at least one non-alkali metal positive valence element other than Ni, Mn, Co, and S, D is selected from F and / or S, 0.8 ≦ x ≦ 0.92, 0.90 ≦ y < 1.0, 0 < n ≦ 0.2, and in the Raman spectrum of the positive electrode active material, the difference in the peak positions of the Ni-O bond and the Mn-O bond is greater than 80 cm -1 and less than 110 cm -1 . The positive electrode active material not only has high specific capacity and high cycle stability in the high voltage region, but also has a low cost. Therefore, the prepared secondary battery has high cost performance.

Description

[Technical Field]

[0001] The present application relates to the field of lithium ion battery technology, and in particular to a positive electrode active material and a preparation method thereof, a positive electrode plate, and a secondary battery. [Background technology]

[0002] The main body of a lithium-ion battery is composed of four parts: a positive electrode, a negative electrode, a separator, and an electrolyte. The performance of the positive electrode material plays a crucial role in the performance of the battery. Therefore, the eternal theme in the development of positive electrode materials is to improve the performance of positive electrode materials, such as specific capacity, power performance, and voltage, while also reducing costs.

[0003] From the perspective of crystal structure, positive electrode materials for lithium-ion batteries mainly include olivine-structured phosphate-based and layered transition metal oxide-based materials. Phosphate-based materials, such as lithium iron phosphate, are low cost but have limitations in energy density and power performance. Layered transition metal oxide-based materials have high energy density and excellent power performance but are relatively expensive. Spinel-based positive electrode materials, such as lithium manganese oxide, also exist, but have low energy density and poor high-temperature performance.

[0004] From the viewpoint of elemental composition, traditional ternary cathode materials have excellent stability and rate performance, but further cost reduction is difficult. Therefore, there is a need to continuously develop new high-energy, low-cost cathode materials for use in lithium-ion batteries. Summary of the Invention [Problem to be solved by the invention]

[0005] In view of this, it is necessary to provide a positive electrode active material and a preparation method thereof, a positive electrode plate, and a secondary battery that address the above-mentioned problems. The positive electrode active material not only has a high specific capacity and high cycle stability in a high voltage range, but also has low cost, so that the secondary battery produced thereby has high cost performance. [Means for solving the problem]

[0006] The compositional chemical formula is LiNa 1-x A y B 1-y O 2-n D n is a cathode active material, where A is selected from a composition of Ni and Mn, B is selected from at least one non-alkali metal positive valence element other than Ni, Mn, Co, and S, D is selected from F and / or S, 0.8 ≦ x ≦ 0.92, 0.90 ≦ y < 1.0, 0 < n ≦ 0.2, and in the Raman spectrum of the cathode active material, the difference in the peak positions of the Ni-O bond and the Mn-O bond is greater than 80 cm -1 and less than 110 cm -1 to provide a cathode active material.

[0007]

[0008] In one embodiment, the molar ratio of Ni to Mn is 3:7 - 1:1.

[0009]

[0010] In one embodiment, B is selected from at least one of Mg, Al, Zr, Ce, Cr, La, P, Ti, Ta, Nb, W, and Mo.

[0011]

[0012]

[0013] In one embodiment, B contains at least Nb or Mo, and D contains at least F. -1 In one embodiment, the crystal structure of the cathode active material is a lithiated spinel-layered composite crystal structure. -1 ​When it is larger than, the coating layer is selected from at least one of an inert oxide coating layer, a phosphate coating layer, and a fluoride coating layer.

[0013] In one embodiment, the positive electrode active material has a difference in peak positions of Ni-O bond and Mn-O bond in the Raman spectrum of 80 cm -1 Larger and 100 cm -1 When it is below, the coating layer is selected from a lithium-containing transition metal oxide coating layer.

[0014] In one embodiment, the coating amount of the coating layer is 0.5 wt%-1 wt% of the mass of the positive electrode active material, and / or, the inert oxide coating layer Inactive oxides in is selected from a composite of Al2O3 and TiO2, and / or, the lithium-containing transition metal oxide coating layer Lithium-containing transition metal oxides in is Li 1+a ZrO 2+a selected from, provided that 0 < a ≦ 1.0, and / or, the fluoride coating layer Fluoride in is selected from MgF2.

[0015] As described above, the method for preparing the positive electrode active material is a step of preparing a Ni, Mn composite metal salt precursor, Li x Na 1-x A y B 1-y O 2-n D n Based on, 0.8 ≦ x ≦ 0.92, 0.90 ≦ y < 1.0, 0 < n ≦ 0.2, mixing the Ni, Mn composite metal salt precursor with a lithium salt, a sodium salt, and an inorganic salt containing any non-alkali metal positive valence element other than Ni, Mn, Co, and S to obtain a mixture, provided that at least one of the lithium salt, the sodium salt, and the inorganic salt contains a negative valence element D, and D is selected from F and / or S, a step of sintering the mixture at 300°C - 500°C to obtain a positive electrode active material, and includes.

[0016] In one embodiment, the molar ratio of Ni to Mn in the Ni, Mn composite metal salt precursor is 3:7-1:1; And / or the molar amount of lithium in the lithium salt exceeds the standard by up to 5 mol%; And / or the sintering time is 10h-30h.

[0017] In one embodiment, the lithium salt is selected from at least two of lithium carbonate, lithium hydroxide, lithium oxalate, lithium nitrate, and lithium fluoride; And / or, the sodium salt is selected from at least one of sodium carbonate, sodium oxalate, and sodium sulfide.

[0018] In one embodiment, when the lithium salt is selected from the composition of lithium carbonate and lithium oxalate, the molar ratio of the lithium carbonate to the lithium oxalate is 1:2-2:1.

[0019] In one embodiment, the mixture is sintered at 300°C-500°C for 10h-30h, followed by a coating treatment at a temperature of 300°C-400°C.

[0020] The present invention provides a positive electrode plate comprising a positive electrode current collector and a positive electrode material layer provided on the surface of the positive electrode current collector, the positive electrode material layer including the positive electrode active material as described above.

[0021] As described above, a secondary battery including a positive electrode plate is provided. [Effects of the Invention]

[0022] The positive electrode active material described in the present application is adjusted so that the sum of the atomic weights of Li and Na and the sum of the atomic weights of A and B are the same, 1:1, and the difference in peak position between the Ni-O bond and the Mn-O bond is 80 cm -1 Larger than 110cm -1As can be seen from the smaller than , the synergistic effect of the specific blending ratios of A and B, oxygen element, and negative valence element D can impart localized cation disorder to the positive electrode active material, while also providing functional properties such as high specific capacity and high-rate capability. Furthermore, the structural stability of the positive electrode active material is improved, the effects of interfacial side reactions are reduced, and the ionic conductivity is improved, thereby improving the cycle stability of the positive electrode active material and achieving a balance between specific capacity and stability. As a result, the positive electrode active material can achieve both high specific capacity and high cycle stability in the high-voltage range. Furthermore, the positive electrode active material can also reduce the watt-hour cost by approximately 5%.

[0023] Therefore, the cathode active material described in the present application exhibits high energy density and high cost performance. When used to prepare a cathode plate and construct a secondary battery, the secondary battery can have better electrical performance and higher cost performance, thereby contributing to improving the market competitiveness of the cathode active material. [Brief explanation of the drawings]

[0024] [Figure 1] 1 shows an EDS (Energy Dispersive Spectrometer) energy spectrum of the positive electrode active material prepared in Example 1. [Figure 2] FIG. 1 is a comparative diagram of Raman spectra of the positive electrode active material prepared in Example 1 and conventional spinel-type LiNi0.5Mn1.5O4, where a is the Raman spectrum of the positive electrode active material prepared in Example 1, and b is the Raman spectrum of the conventional spinel-type LiNi0.5Mn1.5O4. [Figure 3] 1 shows XRD (X-ray diffraction) patterns of the positive electrode active materials prepared in Examples 1, 2, and 12, where a is the diffraction pattern of the positive electrode active material prepared in Example 1, b is the diffraction pattern of the positive electrode active material prepared in Example 2, and c is the diffraction pattern of the positive electrode active material prepared in Example 12. [Figure 4] FIG. 1 is a comparison diagram of charge-discharge curves at an initial current of 40 mA g-1 for the positive electrode active material prepared in Example 1, a conventional ternary layered LiNi0.5Mn0.5O2, and a conventional spinel-type LiNi0.5Mn1.5O4, where a is the positive electrode active material prepared in Example 1, b is the conventional ternary layered LiNi0.5Mn0.5O2, and c is the conventional spinel-type LiNi0.5Mn1.5O4. [Figure 5] 1 shows charge-discharge curves of Sample 1, where a is the initial charge-discharge curve at 2.5V-4.7V and 0.2C, and b is the charge-discharge curve at 2.5V-4.7V and 0.5C. [Figure 6] 1 shows charge-discharge curves of Sample 2, where a is the initial charge-discharge curve at 2.5V-4.7V and 0.2C, and b is the charge-discharge curve at 2.5V-4.7V and 0.5C. [Figure 7] 1 shows charge-discharge curves of Sample 16, where a is the initial charge-discharge curve at 2.5V-4.7V and 0.2C, and b is the charge-discharge curve at 2.5V-4.7V and 0.5C. [Figure 8] 1 shows charge-discharge curves of Sample 17, where a is the initial charge-discharge curve at 2.5V-4.7V and 0.2C, and b is the charge-discharge curve at 2.5V-4.7V and 0.5C. DETAILED DESCRIPTION OF THE INVENTION

[0025] In the following, the present application will be described in more detail to facilitate understanding of the present application. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples set forth herein. Rather, these embodiments or examples are provided to provide a more thorough and complete understanding of the subject matter set forth herein.

[0026] All technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application pertains, unless otherwise specifically defined. The terms used in this application specification are used only for the purpose of explaining specific embodiments or examples, and are not intended to limit this application.

[0027] This application provides a cathode active material with the composition chemical formula Li x Na 1-x A y B 1-y O 2-n D n where A is selected from compositions of Ni and Mn, B is selected from at least one non-alkali metal positive valence element other than Ni, Mn, Co, and S, D is selected from F and / or S, 0.8 ≦ x ≦ 0.92, 0.90 ≦ y < 1.0, 0 < n ≦ 0.2, and in the Raman spectrum of the cathode active material, the difference in peak positions between the Ni-O bond and the Mn-O bond is greater than 80 cm -1 and less than 110 cm -1 .

[0028] The cathode active material is adjusted so that the sum of the atomic weights of Li and Na is the same as the sum of the atomic weights of A and B and is 1:1, and the difference in peak positions between the Ni-O bond and the Mn-O bond is greater than 80 cm -1 and less than 110 cm -1As can be seen from the smaller value, the synergistic effect of the specific blending ratios of A, B, oxygen, and negative valence element D can impart localized cation disorder to the positive electrode active material, thereby enabling the positive electrode active material to possess functional properties such as high specific capacity and high-rate performance. Furthermore, the structural stability of the positive electrode active material, the effects of interfacial side reactions, and the ionic conductivity can be improved, thereby improving the cycle stability of the positive electrode active material and achieving a balance between specific capacity and stability. As a result, the positive electrode active material can exhibit both high specific capacity and high cycle stability in the high-voltage range. Furthermore, the positive electrode active material can also reduce the watt-hour cost by approximately 5%. Therefore, the positive electrode active material described herein exhibits high energy density and excellent cost performance.

[0029] Preferably, the molar ratio of Ni to Mn in the positive electrode active material is 3:7-1:1, so that the nickel content of the positive electrode active material is lower than that of traditional ternary materials. This not only achieves higher safety and lower costs for the positive electrode active material, but also ensures the voltage platform and rate performance of the positive electrode active material and suppresses its voltage decay.

[0030] More preferably, the molar ratio of Ni to Mn includes, but is not limited to, 3:7, 2:3, 9:11, or 1:1.

[0031] In the specific compounding ratio according to the composition formula of the present application, B stabilizes the structure and reduces interfacial side reactions, which are advantageous in improving the cycle stability of the positive electrode active material, reducing gas generation in the battery, slowing down the growth of direct current internal resistance (DCIR), and improving the high-temperature storage life.

[0032] Preferably, B is selected from at least one of Mg, Al, Zr, Ce, Cr, La, P, Ti, Ta, Nb, W, Mo, and Te.

[0033] In the positive electrode active material, B may be present in various forms such as doping, coating, or a combination of doping and coating, and the present application does not limit the present invention.

[0034] When B is present in the form of doping, B is preferably at least one of Al, Cr, and Ti, which easily enters the crystal lattice and is advantageous for strengthening Ni-O bonds and Mn-O bonds; B is preferably at least one of Zr, La, and P, which easily concentrates in the subsurface layer and is advantageous for preventing electrolyte erosion; and B is preferably at least one of Ta, Nb, W, Mo, Te, and Ce, which easily concentrates in the grain boundaries and is advantageous for improving interface stability.

[0035] When B is present in the form of a coating, the positive electrode active material has a secondary particle structure formed by aggregation of primary particles, and B is more concentrated on the surface of the secondary particles, which is advantageous for improving interface stability and ionic conductivity.

[0036] Furthermore, B is preferably a high-valence element with a valence of +5 or higher. On the one hand, high-valence elements have a high bond energy with oxygen, which is advantageous for strengthening the stability of the anion frame during charge and discharge processes. On the other hand, by lowering the valence state of Mn, Mn can also provide part of the capacity, thereby compensating for capacity loss due to reduced oxygen ion activity. In addition, high-valence elements contribute to adjusting the size of primary particles and improving the microstructure of the positive electrode active material.

[0037] In the specific compounding ratio according to the composition formula of this application, F and S can exist in various forms, such as doping and coating. However, doping with F can reduce the energy barrier and disorder of the reaction process. Since the electronegativity of F is stronger than that of oxygen ions, the binding energy with cations is higher. Doping with F can also improve the interface stability and strengthen the frame stability of the material. Coating with F can prevent F ions from penetrating the electrolyte to some extent, improving the long-term cycle stability of the battery. Although doping with S has limited effect on the disorder of the material, S can supply electrons to oxygen ions at high voltage, suppress the generation of oxygen due to excessive oxidation of oxygen ions, and avoid the attenuation of the positive electrode material and the oxidative decomposition of the electrolyte. Therefore, doping and coating with S can also stabilize the anion frame.

[0038] More preferably, in the positive electrode active material, B contains at least Nb or Mo, and D contains at least F, which is advantageous for further improving the interface stability and makes the positive electrode active material have better cycle stability in a high voltage region.

[0039] In one embodiment, the crystalline structure of the positive electrode active material is a lithiated spinel-layered composite crystalline structure.

[0040] In another embodiment, the surface of the crystalline structure of the positive electrode active material further has a coating layer selected from at least one of an inert oxide coating layer, a lithium-containing transition metal oxide coating layer, a phosphate coating layer, and a fluoride coating layer, which helps reduce erosion by the electrolyte during cycling of the positive electrode active material, protect the surface structure from damage, and improve long-term cycle stability.

[0041] The positive electrode active material has a Raman spectrum in which the difference in peak position between the Ni-O bond and the Mn-O bond is 110 cm -1 Smaller than 100cm -1 When it is larger than , the disorder is high and the structural stability is high, discharge capacity and rate performance improvement It is advantageous for [description of advantage], and the coating layer is preferably at least one of an inert oxide coating layer, a phosphate coating layer, and a fluoride coating layer, which can effectively weaken the interfacial side reaction of the material surface caused by the erosion of the electrolyte and improve the stability of the battery system.

[0042] When the difference in the peak positions of the Ni-O bond and the Mn-O bond in the Raman spectrum of the positive electrode active material is greater than 80 cm -1 and less than or equal to 100 cm -1 the disorder is appropriate, and it has a similarly high structural stability. The coating layer is preferably a lithium-containing transition metal oxide coating layer, which can improve the interfacial stability, reduce the interfacial side reaction, and effectively enhance the lithium ion transport ability of the material, contributing to further improvement in the performance of capacity and rate performance.

[0043] Preferably, the coating amount of the coating layer is 0.5 wt% - 1 wt% of the mass of the positive electrode active material.

[0044] Specifically, the inert oxide coating layer Inactive oxides in is preferably a composite of Al2O3 and TiO2, and / or the lithium-containing transition metal oxide coating layer Lithium-containing transition metal oxides in is preferably Li 1+a ZrO 2+a where 0 < a ≤ 1.0, and / or the fluoride coating layer Fluoride in is preferably MgF2.

[0045] Therefore, the positive electrode active material not only has high specific capacity and high cycle stability in the high voltage region, but also has low cost, showing high energy density and high cost performance, and the positive electrode active material will have higher market competitiveness.

[0046] This application provides a method for preparing a positive electrode active material as described above. This preparation method includes: S1 for preparing a Ni, Mn composite metal salt precursor, and Li x Na 1-x A y B 1-y O2-n D n 、Based on 0.8 ≦ x ≦ 0.92, 0.90 ≦ y < 1.0, and 0 < n ≦ 0.2, the Ni, Mn composite metal salt precursor is mixed with a lithium salt, a sodium salt, and an inorganic salt containing any non-alkali metal positive valence element other than Ni, Mn, Co, and S to obtain a mixture, which is S2. However, at least one of the lithium salt, the sodium salt, and the inorganic salt contains a negative valence element D, and D is selected from F and / or S. S2, Sintering the mixture at 300°C - 500°C to obtain a positive electrode active material, which is S3. It includes.

[0047] In step S1, the method for preparing the Ni, Mn composite metal salt precursor adopts the conventional preparation process, including but not limited to the coprecipitation method. The present application will not explain this further. Those skilled in the art can select it by themselves according to the actual preparation needs.

[0048] Preferably, the molar ratio of Ni to Mn in the Ni, Mn composite metal salt precursor is 3:7 - 1:1.

[0049] In step S2, by adopting two types of alkali metal salts, lithium salt and sodium salt, for compounding, the melting temperature of the system is lowered, which helps to promote sufficient fusion and reaction between the alkali metal and the transition metal salt under low-temperature conditions, not only improving the structural consistency and stability, but also ensuring that the system at the sintering temperature of 300°C - 500°C has a certain degree of local cation disorder, and thus ensuring the characteristics of its high capacity and high voltage stability.

[0050] Considering that there is a certain degree of lithium loss during the preparation, the molar amount of lithium in the lithium salt preferably exceeds the standard by within 5 mol%.

[0051] Specifically, the lithium salt is selected from at least two of lithium carbonate, lithium hydroxide, lithium oxalate, lithium nitrate, and lithium fluoride. The fusion system of different lithium salts has a lower melting point than a single lithium salt, which is advantageous in shortening the sintering time; and the flexibly combining various lithium salts to obtain a mixed lithium salt system with different melting points can achieve the effect of adjusting the disorder of the material.

[0052] When lithium carbonate is preferably used as the main lithium salt, lithium carbonate decomposes slowly at a sintering temperature of 300°C-500°C, has high decomposition energy, and the reaction system energy is insufficient to rapidly convert the cations from a disordered state to an ordered state. Therefore, by setting the sintering time to 10 hours-30 hours, the lithium carbonate can be completely reacted without reducing the disorder of the cations, and the prepared positive electrode active material can be ensured to have a high degree of disorder.

[0053] More preferably, the lithium salt is selected from a composition of lithium carbonate and lithium oxalate, and the molar ratio of the lithium carbonate to the lithium oxalate is 1:2-2:1, which can provide a positive electrode active material with better performance.

[0054] The sodium salt is selected from at least one of sodium carbonate, sodium oxalate, and sodium sulfide, and is preferably sodium oxalate. The lithium salt and sodium salt have low melting points, which can effectively reduce the sintering temperature, improve the disorder of the material, and promote the rapid penetration of alkali metal, effectively reducing the amount of residual alkali on the surface of the sample after one sintering, thereby meeting the industrial practical requirements. "Gelling" or "jellying" during the homogenization process This can solve the processing problems.

[0055] In step S3, the sintering temperature is adjusted to allow the Li, Na alkali metals to fully penetrate into the Ni, Mn composite metal salt precursor and react uniformly, thereby reducing lithium loss and ensuring a certain degree of cation disorder, thereby making the local cations in the positive electrode active material disordered and improving the performance of the positive electrode active material. Preferably, the sintering temperature is 350°C-400°C or 400°C-450°C.

[0056] Preferably, the sintering time is 10 hours to 30 hours, more preferably 15 hours to 25 hours, so that the positive electrode active material can have a more suitable disorder.

[0057] In one embodiment, the mixture is sintered at 300°C-500°C for 10h-30h, and then washed and / or secondary sintered to remove alkaline impurities remaining on the surface of the sintered product; In another embodiment, the mixture is sintered at 300°C-500°C for 10h-30h, followed by a coating treatment at a temperature of 300°C-400°C.

[0058] When lithium remains on the surface of the sintered product, the coating treatment can directly coat the remaining lithium with a lithium-containing transition metal oxide, thereby achieving direct conversion and utilization of the remaining lithium.

[0059] After sintering the mixture, cleaning or secondary sintering may be performed first, and then the coating treatment may be performed, or the coating treatment may be performed directly after sintering the mixture; this application is not limited thereto.

[0060] The prepared positive electrode active material contained Li and Na of atom mole Sum of quantities, A and B atom mole Sum of quantities, negative valence atoms mole It can be seen that the ratio of the sum of the quantities varies within ±3% from the theoretical value of 1:1:2.

[0061] The present application further provides a positive electrode plate including a positive electrode current collector and a positive electrode material layer provided on a surface of the positive electrode current collector, the positive electrode material layer including the above-described positive electrode active material.

[0062] In one embodiment, the positive electrode material layer further comprises a conductive agent and an adhesive.

[0063] The present application further provides a secondary battery including the positive electrode plate as described above.

[0064] In one embodiment, the secondary battery further comprises a negative electrode plate, a separator, and an electrolyte.

[0065] The positive electrode active material, the preparation method thereof, the positive electrode plate, and the secondary battery will be further described below with reference to the following specific examples.

[0066] Example 1

[0067] Coprecipitation method was used to prepare Ni composite metal salt precursors 0.3 Mn 0.7 (OH)2 was prepared.

[0068] Li 0.9 Na 0.1 (Ni 0.3 Mn 0.7 ) 0.98 Nb 0.02 O 1.8 F 0.2 Based on the stoichiometric ratio of Ni 0.3 Mn 0.7 (OH)2 was thoroughly mixed with Li2CO3, LiF, Na2C2O4, and Nb2O5 to obtain a mixture, where the total molar amount of Li in Li2CO3 and LiF exceeded the standard by 3 mol%.

[0069] The mixture was sintered in an air atmosphere at 425°C for 25 hours. After sintering was complete, the sintered material was washed to remove any remaining alkaline impurities on the surface and then dried in an air atmosphere. The washed material was then mixed with Al2O3 and subjected to a coating process at 350°C to obtain a cathode active material with an Al2O3 coating layer. The amount of Al2O3 coating was 0.5 wt% of the mass of the cathode active material.

[0070] The prepared positive electrode active material was subjected to EDS spectroscopy, and the results are shown in Figure 1. Since the mass fraction of lithium element cannot be accurately determined by EDS, the ICP elemental analysis in Table 1 (Note: EDS and ICP (Inductively Coupled Plasma) (There are differences in the calculation method of element mass ratios between the two methods; EDS uses the mass ratio of the selected element as 100%, while ICP uses the total mass of the entire sample shown in the molecular formula as 100%). The atomic weight ratio was converted according to the mass ratio of each element, and the difference between the composition of each element and the atomic weight ratio of the theoretically complete element was within ±3%. Therefore, the prepared positive electrode active material was a Li with an Al2O3 coating layer. 0.9 Na 0.1 (Ni 0.3 Mn 0.7 ) 0.98 Nb 0.02 O 1.8 F 0.2 It was proved that this coincides with the design value.

[0071] The prepared positive electrode active material was compared with the conventional spinel-type LiNi 0.5 Mn 1.5 The Raman spectra of the prepared cathode active material were compared with those of the conventional spinel-type LiNiO4. The results are shown in Fig. 2, where a is the Raman spectrum of the prepared cathode active material, and b is the Raman spectrum of the conventional spinel-type LiNiO4. 0.5 Mn 1.5 As can be seen from Figure 2, the peak position of the Ni-O bond in the prepared positive electrode active material is 475 cm -1 and the conventional spinel-type LiNi 0.5 Mn 1.5 Compared with O4, the peak position of the Ni-O bond remains almost unchanged, while the peak position of the Mn-O bond is at 567 cm -1There is a clear shift, and the peak position moves significantly to the left, approaching the Ni-O bond and forming a large combined peak that is almost the same as the Ni-O bond peak. This proves that the difference in the relative positions of Mn, Ni, and lithium becomes smaller, and the disorder decreases. At this time, the difference in the peak positions of the Ni-O bond and the M-O bond is about 90 cm. -1 and the conventional spinel-type LiNi 0.5 Mn 1.5 Approximately 50cm longer than O4 -1 This lowers the distribution of nickel compared to conventional spinel materials. Furthermore, in conventional layered materials, nickel is alternately distributed in manganese and transition metal layers, and the relative distribution of nickel and lithium is not significantly different. Conventional layered materials The Ni-O bond and the Mn-O bond usually form a single combined peak, making it difficult to distinguish them. However, the difference in peak positions between the Ni-O bond and the Mn-O bond in the positive electrode active material prepared in this example was approximately 90 cm. -1 This is distinct from conventional ordered layered materials, demonstrating that this example is a lithiated spinel-layered composite structure material with local cation disorder characteristics, and can simultaneously provide the high stability of a spinel structure and the high capacity characteristics of a layered structure.

[0072] The prepared positive electrode active material was subjected to an X-ray diffraction test, and the results are shown in FIG.

[0073] The prepared positive electrode active material and the conventional ternary layered LiNi 0.5 Mn 0.5 O2 and conventional spinel-type LiNi 0.5 Mn 1.5 A comparative analysis of the charge and discharge performance was conducted between O4 and O5, and the results are shown in Figure 4.

[0074] Example 2

[0075] Example 2 is a composite metal salt precursor Ni 0.4 Mn 0.6 (OH)2 was prepared and Li 0.9 Na 0.1 (Ni 0.4 Mn 0.6 )0.98 Nb 0.02 O 1.8 F 0.2 This example differs from Example 1 in that the positive electrode active material was prepared based on the stoichiometric ratio of

[0076] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 106 cm -1 It was found that...

[0077] The prepared positive electrode active material was subjected to an X-ray diffraction test, and the results are shown in FIG.

[0078] Example 3

[0079] Example 3 is a composite metal salt precursor Ni 0.45 Mn 0.55 (OH)2 was prepared and Li 0.9 Na 0.1 (Ni 0.45 Mn 0.55 ) 0.98 Nb 0.02 O 1.8 F 0.2 This example differs from Example 1 in that the positive electrode active material was prepared based on the stoichiometric ratio of

[0080] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.9 Na 0.1 (Ni 0.45 Mn 0.55 ) 0.98 Nb 0.02 O 1.8 F 0.2The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 103 cm -1 It was found that...

[0081] Example 4

[0082] Example 4 is a composite metal salt precursor Ni 0.5 Mn 0.5 (OH)2 was prepared and Li 0.9 Na 0.1 (Ni 0.5 Mn 0.5 ) 0.98 Nb 0.02 O 1.8 F 0.2 This example differs from Example 1 in that the positive electrode active material was prepared based on the stoichiometric ratio of

[0083] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.9 Na 0.1 (Ni 0.5 Mn 0.5 ) 0.98 Nb 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 105 cm -1 It was found that...

[0084] Example 5

[0085] Coprecipitation method was used to prepare Ni composite metal salt precursors 0.4 Mn 0.6 (OH)2 was prepared.

[0086] Li 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 Based on the stoichiometric ratio of Ni 0.4Mn 0.6 (OH)2 was thoroughly mixed with Li2CO3, Li2C2O4, LiF, Na2C2O4, and Nb2O5 to obtain a mixture, where the total molar amount of Li in Li2CO3, Li2C2O4, and LiF exceeded the standard by 3 mol%, and the molar ratio of Li2CO3 to Li2C2O4 was 2:1.

[0087] The mixture was sintered in an air atmosphere at 425°C for 20 hours. After sintering was complete, the sintered material was washed to remove any remaining alkaline impurities on the surface and then dried in an air atmosphere. The washed material was then mixed with Al2O3 and subjected to a coating process at 350°C to obtain a cathode active material with an Al2O3 coating layer. The amount of Al2O3 coating was 0.5 wt% of the mass of the cathode active material.

[0088] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak position between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 101 cm -1 It was found that...

[0089] Example 6

[0090] Coprecipitation method was used to prepare Ni composite metal salt precursors 0.4 Mn 0.6 (OH)2 was prepared.

[0091] Li 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.1 S 0.1 Based on the stoichiometric ratio of Ni 0.4 Mn 0.6(OH)2 was thoroughly mixed with Li2CO3, LiF, Na2C2O4, Nb2O5, and Na2S to obtain a mixture, where the total molar amount of Li in Li2CO3 and LiF exceeded the standard by 3 mol%.

[0092] The mixture was sintered in an air atmosphere at 425°C for 20 hours. After sintering was complete, the sintered material was washed to remove any remaining alkaline impurities on the surface and then dried in an air atmosphere. The washed material was then mixed with Al2O3 and subjected to a coating process at 350°C to obtain a cathode active material with an Al2O3 coating layer. The amount of Al2O3 coating was 0.5 wt% of the mass of the cathode active material.

[0093] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.1 S 0.1 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 102 cm -1 It was found that...

[0094] Example 7

[0095] Coprecipitation method was used to prepare Ni composite metal salt precursors 0.4 Mn 0.6 (OH)2 was prepared.

[0096] Li 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Mo 0.02 O 1.8 F 0.2 Based on the stoichiometric ratio of Ni 0.4 Mn 0.6(OH)2 was thoroughly mixed with Li2CO3, LiF, Na2C2O4, and Mo2O5 to obtain a mixture, where the total molar amount of Li in Li2CO3 and LiF exceeded the standard by 3 mol%.

[0097] The mixture was sintered in an air atmosphere at 425°C for 20 hours. After sintering was complete, the sintered material was washed to remove any remaining alkaline impurities on the surface and then dried in an air atmosphere. The washed material was then mixed with Al2O3 and subjected to a coating process at 350°C to obtain a cathode active material with an Al2O3 coating layer. The amount of Al2O3 coating was 0.5 wt% of the mass of the cathode active material.

[0098] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Mo 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 103 cm -1 It was found that...

[0099] Example 8

[0100] Coprecipitation method was used to prepare Ni composite metal salt precursors 0.4 Mn 0.6 (OH)2 was prepared.

[0101] Li 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.9 Mo 0.02 Nb 0.02 Te 0.02 Ti 0.02 Al 0.02 O 1.8 F 0.2 Based on the stoichiometric ratio of Ni 0.4 Mn 0.6(OH)2 was thoroughly mixed with Li2CO3, LiF, Na2C2O4, Mo2O5, Nb2O5, TeO2, and TiO2 to obtain a mixture, where the total molar amount of Li in Li2CO3 and LiF exceeded the standard by 3 mol%.

[0102] The mixture was sintered in an air atmosphere at 425°C for 22 hours. After sintering was complete, the sintered material was washed to remove any remaining alkaline impurities on the surface and then dried in an air atmosphere. The washed material was then mixed with Al2O3 and subjected to a coating process at 350°C to obtain a cathode active material with an Al2O3 coating layer. The amount of Al2O3 coating was 0.5 wt% of the mass of the cathode active material.

[0103] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.9 Mo 0.02 Nb 0.02 Te 0.02 Ti 0.02 Al 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 106 cm -1 It was found that...

[0104] Example 9

[0105] Coprecipitation method was used to prepare Ni composite metal salt precursors 0.4 Mn 0.6 (OH)2 was prepared.

[0106] Li 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 Based on the stoichiometric ratio of Ni 0.4 Mn 0.6(OH)2 was thoroughly mixed with Li2CO3, LiF, Na2C2O4, and Nb2O5 to obtain a mixture, where the total molar amount of Li in Li2CO3 and LiF exceeded the standard by 3 mol%.

[0107] The mixture was sintered in an air atmosphere at 425°C for 22 hours. After sintering was completed, the sintered material was washed to remove alkaline impurities remaining on the surface, dried in an air atmosphere, and then subjected to secondary sintering at 350°C to obtain a positive electrode active material.

[0108] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material contained Li 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 96 cm -1 It was found that...

[0109] Example 10

[0110] Coprecipitation method was used to prepare Ni composite metal salt precursors 0.4 Mn 0.6 (OH)2 was prepared.

[0111] Li 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 Based on the stoichiometric ratio of Ni 0.4 Mn 0.6 (OH)2 was thoroughly mixed with Li2CO3, LiF, Na2C2O4, and Nb2O5 to obtain a mixture, where the total molar amount of Li in Li2CO3 and LiF exceeded the standard by 3 mol%.

[0112] The mixture was placed in an air atmosphere and sintered at 425°C for 20 hours. After sintering was complete, the sintered material was washed to remove any remaining alkaline impurities on the surface and then dried in an air atmosphere. The washed material was then mixed with Al2O3 and MgF2 and subjected to a coating process at 350°C to obtain a cathode active material with an Al2O3 coating layer and an MgF2 coating layer. The Al2O3 coating amount was 0.5 wt% of the cathode active material's mass, and the MgF2 coating amount was 0.5 wt% of the cathode active material's mass.

[0113] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with Al2O3 and MgF2 coating layers. 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 103 cm -1 It was found that...

[0114] Example 11

[0115] Coprecipitation method was used to prepare Ni composite metal salt precursors 0.4 Mn 0.6 (OH)2 was prepared.

[0116] Li 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 Based on the stoichiometric ratio of Ni 0.4 Mn 0.6 (OH)2 was thoroughly mixed with Li2CO3, LiF, Na2C2O4, and Nb2O5 to obtain a mixture, where the total molar amount of Li in Li2CO3 and LiF exceeded the standard by 3 mol%.

[0117] The mixture was sintered in an air atmosphere at 425°C for 20 hours. After sintering was complete, the sintered material was washed to remove any remaining alkaline impurities on the surface and then dried in an air atmosphere. The washed material was then mixed with MgF2 and Li2ZrO3 and subjected to a coating process at 350°C to obtain a cathode active material with an MgF2 coating layer and a Li2ZrO3 coating layer. The coating amount of MgF2 was 0.5 wt% of the mass of the cathode active material, and the coating amount of Li2ZrO3 was 0.5 wt% of the mass of the cathode active material.

[0118] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with MgF2 and Li2ZrO3 coating layers. 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 100 cm -1 It was found that...

[0119] Example 12

[0120] Coprecipitation method was used to prepare Ni composite metal salt precursors 0.4 Mn 0.6 (OH)2 was prepared.

[0121] Li 0.8 Na 0.2 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 Based on the stoichiometric ratio of Ni 0.4 Mn 0.6 (OH)2 was thoroughly mixed with Li2CO3, LiF, Na2C2O4, and Nb2O5 to obtain a mixture, where the total molar amount of Li in Li2CO3 and LiF exceeded the standard by 3 mol%.

[0122] The mixture was sintered in an air atmosphere at 425°C for 22 hours. After sintering was complete, the sintered material was washed to remove any remaining alkaline impurities on the surface and then dried in an air atmosphere. The washed material was then mixed with Al2O3 and subjected to a coating process at 350°C to obtain a cathode active material with an Al2O3 coating layer. The amount of Al2O3 coating was 0.5 wt% of the mass of the cathode active material.

[0123] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.8 Na 0.2 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak position between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 101 cm -1 It was found that...

[0124] The prepared positive electrode active material was subjected to an X-ray diffraction test, and the results are shown in FIG.

[0125] Example 13

[0126] Example 13 differs from Example 2 in that the sintering temperature was 450°C.

[0127] Based on the EDS spectrum and ICP analysis, the chemical composition of the prepared positive electrode active material was Li 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 106 cm -1 It was found that...

[0128] Example 14

[0129] In Example 14, the composite metal salt precursor prepared was Ni 0.2 Mn 0.8 It differs from Example 2 in that it was (OH)2.

[0130] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.9 Na 0.1 (Ni 0.2 Mn 0.8 ) 0.98 Nb 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 102 cm -1 It was found that...

[0131] Example 15

[0132] Coprecipitation method was used to prepare Ni composite metal salt precursors 0.4 Mn 0.6 (OH)2 was prepared.

[0133] Li 0.92 Na 0.02 (Ni 0.4 Mn 0.6 ) 0.9 Nb 0.05 Al 0.05 O 1.9 F 0.1 Based on the stoichiometric ratio of Ni 0.4 Mn 0.6 (OH)2 was thoroughly mixed with Li2CO3, Li2C2O4, LiF, Na2C2O4, and Nb2O5 to obtain a mixture, where the total molar amount of Li in Li2CO3, Li2C2O4, and LiF exceeded the standard by 5 mol%, and the molar ratio of Li2CO3 to Li2C2O4 was 1:2.

[0134] The mixture was sintered in an air atmosphere at 350°C for 30 hours. After sintering was complete, the sintered material was washed to remove any remaining alkaline impurities on the surface and then dried in an air atmosphere. The washed material was then mixed with Al2O3 and subjected to a coating process at 300°C to obtain a cathode active material with an Al2O3 coating layer. The amount of Al2O3 coating was 0.5 wt% of the mass of the cathode active material.

[0135] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.92 Na 0.02 (Ni 0.4 Mn 0.6 ) 0.9 Nb 0.05 Al 0.05 O 1.9 F 0.1 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 103 cm -1 It was found that...

[0136] As can be seen from FIG. 3, the position of the diffraction peak of the positive electrode active material prepared in Example 1 is the same as that of the conventional positive electrode material having a spinel structure. However, the crystallinity is much lower than that of the conventional spinel obtained by high-temperature sintering, and the half-width of the characteristic peak is significantly wider, which proves that the positive electrode active material has a spinel structure. ,So The location of the main peak The two highest intensity peaks at 2-θ angles of 17-20° and approximately 44° correspond to the positions of the (003) and (104) peaks of the layered cathode, respectively. The agreement between the two peaks demonstrates that the cathode has a layered crystalline structure. However, the two split peaks of the layered cathode, located at the diffraction angles of (006) / (102) and (108) / (110), are not significantly separated, demonstrating that the cathode is not a conventional layered cathode with highly ordered cations. These two split peaks are expressed as a single combined peak due to cation disorder. Therefore, Figure 3 demonstrates that the cathode active material provided by the present solution has the characteristics of localized cation disorder.

[0137] Furthermore, comparing the diffraction patterns of the positive electrode active materials prepared in Examples 1, 2, and 12 in FIG. 3 reveals that the positive electrode active materials prepared in Examples 1, 2, and 12 have similar characteristic peak positions and relative intensities. Comparing the positive electrode active materials prepared in Examples 2 and 12, it reveals that increasing the Na content from 10 mol % to 20 mol % reveals a characteristic peak at 15°-17°. Thus, the characteristic peak of the Na phase observed varies depending on the Na content in the positive electrode active material described herein.

[0138] Figure 4 shows 2.5V-4.7V vs Li / Li + So, the first time it was 40mAg -1 The positive electrode active material prepared in Example 1 was charged and discharged at a discharge voltage of 3.0 V to 2.5 V, and the ... -1 ) significantly higher than discharge capacity Amount Yes, capacity >8mAhg -1 Therefore, this material is a spinel structure Mn 4+ This proves that the cathode active material has the electrochemical property of reducing Mn to low-valent Mn ions to provide capacity, and at the same time, the initial discharge curve between 3.5 V and 4.5 V shows not a platform-like two-phase reaction curve of spinel but a prominent upward-opening parabolic ramp discharge curve of a roughly layered solid-solution reaction, proving that this material also possesses the characteristics of a layered structure. Therefore, Figure 4 further proves that the cathode active material provided by this solution has the characteristics of local cation disorder.

[0139] Comparative Example 1

[0140] Comparative Example 1 differs from Example 1 in that no Na2C2O4 is added for sintering.

[0141] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li(Ni) with an Al2O3 coating layer. 0.3 Mn 0.7 )0.98 Nb 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak position between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 116 cm -1 It was found that...

[0142] Comparative Example 2

[0143] Comparative Example 2 differs from Example 2 in that no Na2C2O4 is added for sintering.

[0144] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li(Ni) with an Al2O3 coating layer. 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 118 cm -1 It was found that...

[0145] Comparative Example 3

[0146] Comparative Example 3 differs from Example 4 in that no Na2C2O4 is added for sintering.

[0147] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li(Ni) with an Al2O3 coating layer. 0.5 Mn 0.5 ) 0.98 Nb 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 126 cm -1 It was found that...

[0148] Comparative Example 4

[0149] Comparative Example 4 differs from Example 2 in that the sintering temperature was 600°C.

[0150] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 65 cm -1 It was found that...

[0151] Comparative Example 5

[0152] Comparative Example 5 differs from Example 2 in that no LiF is added for sintering.

[0153] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 121 cm -1 It was found that...

[0154] Comparative Example 6

[0155] Comparative Example 6 differs from Example 2 in that no Nb2O5 is added for sintering.

[0156] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.9 Na 0.1 Ni 0.4 Mn 0.6 O1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 125 cm -1 It was found that...

[0157] Comparative Example 7

[0158] Comparative Example 7 is Li 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.8 Nb 0.1 Al 0.1 O 1.8 F 0.2 Based on the stoichiometric ratio of Ni 0.4 Mn 0.6 This example differs from Example 2 in that (OH)2 was mixed with Li2CO3, LiF, Na2C2O4, and Nb2O5 and sintered.

[0159] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.8 Nb 0.1 Al 0.1 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 128 cm -1 It was found that...

[0160] Comparative Example 8

[0161] Comparative Example 8 is Li 0.7 Na 0.3 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 Based on the stoichiometric ratio of Ni 0.4 Mn 0.6This example differs from Example 2 in that (OH)2 was mixed with Li2CO3, LiF, Na2C2O4, and Nb2O5 and sintered.

[0162] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.7 Na 0.3 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 126 cm -1 It was found that...

[0163] Comparative Example 9

[0164] Comparative Example 9 is Li 0.98 Na 0.02 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 Based on the stoichiometric ratio of Ni 0.4 Mn 0.6 This example differs from Example 2 in that (OH)2 was mixed with Li2CO3, LiF, Na2C2O4, and Nb2O5 and sintered.

[0165] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.98 Na 0.02 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 118 cm -1 It was found that...

[0166] Comparative Example 10

[0167] Comparative Example 10 is Li 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.5 F 0.5 Based on the stoichiometric ratio of Ni 0.4 Mn 0.6 This example differs from Example 2 in that (OH)2 was mixed with Li2CO3, LiF, Na2C2O4, and Nb2O5 and sintered.

[0168] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.9 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.5 F 0.5 The Raman spectrum analysis revealed that the difference in peak position between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 116 cm -1 It was found that...

[0169] Comparative Example 11

[0170] Comparative Example 11 is Li 1.1 Na 0.1 (Ni 0.4 Mn 0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 Based on the stoichiometric ratio of Ni 0.4 Mn 0.6 This example differs from Example 2 in that (OH)2 was mixed with Li2CO3, LiF, Na2C2O4, and Nb2O5 and sintered.

[0171] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 1.1 Na 0.1 (Ni 0.4 Mn0.6 ) 0.98 Nb 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak positions between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 73 cm -1 This was found to be due to the fact that the lithium loading was too high, causing the material to transition from a disordered to an ordered state more quickly, resulting in a significant decrease in disorder under the same sintering conditions.

[0172] Comparative Example 12

[0173] Comparative Example 12 is Li 0.9 Na 0.1 (Ni 0.4 Mn 0.6 )1Nb 0.02 O 1.8 F 0.2 Based on the stoichiometric ratio of Ni 0.4 Mn 0.6 This example differs from Example 2 in that (OH)2 was mixed with Li2CO3, LiF, Na2C2O4, and Nb2O5 and sintered.

[0174] Based on the EDS spectrum and ICP analysis, the prepared positive electrode active material was Li with an Al2O3 coating layer. 0.9 Na 0.1 (Ni 0.4 Mn 0.6 )1Nb 0.02 O 1.8 F 0.2 The Raman spectrum analysis revealed that the difference in peak position between the Ni-O bond and the Mn-O bond in the prepared positive electrode active material was approximately 116 cm -1 It was found that...

[0175] The ICP analysis results of the positive electrode active materials prepared in Examples 1 to 15 and Comparative Examples 1 to 12 are shown in Table 1. Table 1 shows the mass fraction of each element in the positive electrode active material (the remainder is the mass fraction of oxygen element), and the sum of the mass fraction of each element and the mass fraction of oxygen element is set to 100%. [Table 1]

[0176] According to Table 1, the mass ratio of each element corresponds to the corresponding atomic mole The ratio of the amount of each element in the positive electrode active material is converted to the atomic ratio of the theoretically complete element. mole Since the difference between the amount and the blending ratio was within ±3%, it was proven that a positive electrode active material that matched the designed value had been prepared.

[0177] Application of the Example

[0178] The positive electrode active materials prepared in Examples 1 to 15 were used in turn to prepare secondary battery samples 1 to 15.

[0179] Application of comparative examples

[0180] The positive electrode active materials prepared in Comparative Examples 1 to 12 were used in turn to prepare secondary battery samples 16 to 27.

[0181] The above samples were prepared using the same preparation method. Specifically, the positive electrode active material was a conductive material Super-P and the adhesive PVDF. (Poly(vinylidene fluoride)) and mixed in a mass ratio of 92:4:4, and an appropriate amount of NMP (N-methylpyrrolidone) The solution was added to form a slurry, which was then applied to aluminum foil and dried. After that, it was baked in a vacuum oven at 150°C for 12 hours. Then, a secondary battery was assembled using metallic lithium as the anode and 1 mol / L LiPF6 at a volume ratio of EC (Ethylene Carbonate) :EMC (Ethyl Methyl Carbonate) The electrolyte was prepared by dissolving the solution in a mixed organic solvent with a ratio of 0.1:0.2:0.7 in an Ar gas atmosphere in a glove box, and a CR2032 button battery was assembled.

[0182] Adopts constant current / constant voltage charge + constant current discharge charge / discharge mode, 1C=200mAg -1At two current densities, 0.2C and 0.5C, performance tests were carried out on Samples 1, 2, 16, and 17 in a voltage window of 2.5V-4.7V, and the test results are shown in Figures 5 to 8. Figures 5 to 8 show that Samples 1 and 2 have significantly higher discharge capacities than Samples 16 and 17.

[0183] Adopts constant current / constant voltage charge + constant current discharge charge / discharge mode, 1C=200mAg -1 The initial charge-discharge activation and scaling tests were performed on samples 1 to 27 at a current density of 0.2C and a voltage window of 2.5V-4.7V. Then, 100 cycle tests were performed at 0.5C and 2.5V-4.5V. The test results are shown in Table 2. The initial coulombic efficiency is a performance index used to quantify the anode material of lithium-ion batteries and is defined as the ratio of the discharge capacity to the charge capacity of a lithium-ion battery in the first charge-discharge cycle. Battery capacity is the amount of electricity discharged from a battery under certain conditions (discharge rate, temperature, end voltage, etc.). [Table 2]

[0184] From Table 2, it can be seen that the secondary battery prepared using the positive electrode active material provided by the present application has a high capacity retention rate of at least about 91% after 100 cycles at 0.5C at 2.5V-4.7V, and thus not only has a high specific capacity and high cycle stability in the high voltage range, but also has low cost, making it highly cost-effective.

[0185] As is clear from Comparative Examples 1 to 3, 5 to 10, and 12, the difference in peak position between the Ni-O bond and the Mn-O bond is 110 cm -1The difference in the peak positions of the Ni-O bond and the Mn-O bond is larger than 80 cm. As a result, the disorder of the material becomes excessively high, which intensifies the interfacial side reaction and reduces the compaction density of the prepared electrode plate, resulting in a decrease in the stability of the battery and poor practicality. As is clear from Comparative Examples 4 and 11, the difference in the peak positions of the Ni-O bond and the Mn-O bond is 80 cm. -1 The size is smaller than that of the conventional battery, and the disorder of the material is too low. As a result, the structural stability of the material is poor at high voltages, and the power performance is obviously reduced, so the battery capacity at high magnification is not sufficient.

[0186] The technical features of the above-described embodiments can be combined in any manner, and all possible combinations of the technical features in the above-described embodiments are not listed for the sake of brevity, but as long as there is no contradiction in the combination of these technical features, they should be considered to be within the technical scope recorded in this specification.

[0187] The above examples merely represent some embodiments of the present application that are specifically and in detail described, and should not be understood as limiting the scope of the present application. It should be noted that a person skilled in the art can make some modifications and improvements without departing from the concept of the present application, and all of these modifications and improvements belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

[0188] This application claims priority to a Chinese patent application bearing application number CN202310809840.1 and entitled "Positive electrode active material and preparation method thereof, positive electrode plate, and secondary battery," filed with the State Intellectual Property Office of China on July 4, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. The chemical formula is Li ｘ Na １－ｘ A ｙ B １－ｙ O ２－ｎ D ｎ A positive electrode active material is a positive electrode active material, wherein A is selected from a composition of Ni and Mn, B is selected from at least one non-alkali metal positive valence element other than Ni, Mn, Co, and S, and D is selected from F and / or S, and 0.8≦x≦0.92, 0.90≦y<1.0, and 0<n≦0.2 are satisfied. In the positive electrode active material, the difference in peak positions of the Ni—O bond and the Mn—O bond in the Raman spectrum is 80 cm. －１ Larger than 110cm －１ The positive electrode active material is smaller than

2. 2. The positive electrode active material according to claim 1, wherein the molar ratio of Ni to Mn is 3:7-1:

1.

3. 3. The positive electrode active material according to claim 1, wherein B is selected from at least one of Mg, Al, Zr, Ce, Cr, La, P, Ti, Ta, Nb, W, Mo, and Te.

4. 4. The positive electrode active material according to claim 1, wherein the B is present in the form of a dopant and is selected from at least one of Al, Cr, and Ti.

5. 4. The positive electrode active material according to claim 1, wherein the B is present in a doped form and is selected from at least one of Zr, La, and P.

6. 4. The positive electrode active material according to claim 1, wherein the B is present in a doped form and is selected from at least one of Ta, Nb, W, Mo, Te, and Ce.

7. 4. The positive electrode active material according to claim 1, wherein the B is selected from elements with a valence of +5 or higher.

8. 8. The positive electrode active material according to claim 1, wherein B contains at least Nb or Mo, and D contains at least F.

9. 9. The positive electrode active material according to claim 1, wherein the crystal structure of the positive electrode active material is a lithiated spinel-layered composite crystal structure.

10. 10. The cathode active material according to claim 9, wherein a surface of the crystalline structure of the cathode active material further has a coating layer, and the coating layer is selected from at least one of an inert oxide coating layer, a lithium-containing transition metal oxide coating layer, a phosphate coating layer, and a fluoride coating layer.

11. The positive electrode active material has a Raman spectrum in which the difference in peak position between the Ni—O bond and the Mn—O bond is 110 cm －１ Smaller than 100cm －１ 11. The positive electrode active material according to claim 10, wherein when the σ is greater than 1, the coating layer is selected from at least one of an inert oxide coating layer, a phosphate coating layer, and a fluoride coating layer.

12. The positive electrode active material has a Raman spectrum in which the difference in peak position between the Ni—O bond and the Mn—O bond is 80 cm －１ Larger than 100cm －１ The positive electrode active material according to claim 10 , wherein the coating layer is selected from a lithium-containing transition metal oxide coating layer when:

13. The positive electrode active material according to any one of claims 10 to 12, wherein the coating amount of the coating layer is 0.5 wt% to 1 wt% of the mass of the positive electrode active material.

14. The inert oxide coating layer is Al ２ O ３ and TiO ２ The positive electrode active material according to any one of claims 10 to 13, wherein the positive electrode active material is selected from the group consisting of a compound of the formula:

15. The lithium-containing transition metal oxide coating layer is １＋ａ ZrO ２＋ａ The positive electrode active material according to claim 10 , wherein a is selected from the following:

16. The fluoride coating layer is MgF ２ The positive electrode active material according to any one of claims 10 to 15, selected from the group consisting of:

17. preparing a Ni, Mn composite metal salt precursor; Li ｘ Na １－ｘ A ｙ B １－ｙ O ２－ｎ D ｎ , 0.8≦x≦0.92, 0.90≦y<1.0, 0<n≦0.2, mixing the Ni, Mn composite metal salt precursor with a lithium salt, a sodium salt, and an inorganic salt containing any non-alkali metal positive valence element other than Ni, Mn, Co, and S to obtain a mixture, with the proviso that at least one of the lithium salt, the sodium salt, and the inorganic salt contains a negative valence element D, and D is selected from F and / or S; sintering the mixture at 300°C to 500°C to obtain a positive electrode active material.

18. 18. The method for preparing a positive electrode active material according to claim 17, wherein the molar ratio of Ni to Mn in the Ni, Mn composite metal salt precursor is 3:7-1:

1.

19. 19. The method for preparing a positive electrode active material according to claim 17 or 18, wherein the molar amount of lithium in the lithium salt exceeds the reference by up to 5 mol%.

20. The method for preparing a positive electrode active material according to any one of claims 17 to 19, wherein the sintering time is 10h-30h.

21. The method for preparing a positive electrode active material according to any one of claims 17 to 20, wherein the lithium salt is selected from at least two of lithium carbonate, lithium hydroxide, lithium oxalate, lithium nitrate, and lithium fluoride.

22. The method for preparing a positive electrode active material according to any one of claims 17 to 21, wherein the sodium salt is selected from at least one of sodium carbonate, sodium oxalate, and sodium sulfide.

23. 22. The method for preparing a cathode active material of claim 21, wherein when the lithium salt is selected from the composition of lithium carbonate and lithium oxalate, the molar ratio of the lithium carbonate to the lithium oxalate is 1:2-2:

1.

24. The method for preparing a positive electrode active material according to any one of claims 17 to 23, further comprising sintering the mixture at 300 ° C.-500 ° C. for 10h-30h, followed by a coating treatment at a temperature of 300 ° C.-400 ° C.

25. 25. The method for preparing a positive electrode active material according to claim 24, wherein the sintering temperature is 350°C-400°C.

26. 25. The method for preparing a positive electrode active material according to claim 24, wherein the sintering temperature is 400°C-450°C.

27. The method for preparing a positive electrode active material according to any one of claims 24 to 26, wherein the sintering time is 15h-25h.

28. The method for preparing a positive electrode active material according to any one of claims 24 to 26, wherein, when lithium remains on the surface of the sintered product, the remaining lithium is directly coated with a lithium-containing transition metal oxide by the coating treatment.

29. A positive electrode plate comprising: a positive electrode current collector; and a positive electrode material layer provided on a surface of the positive electrode current collector, the positive electrode material layer including the positive electrode active material according to any one of claims 1 to 16.

30. 30. The positive electrode plate according to claim 29, wherein the positive electrode material layer further comprises a conductive agent and an adhesive.

31. A secondary battery comprising the positive electrode plate according to claim 29 or 30.

32. 32. The secondary battery of claim 31, further comprising a negative electrode plate, a separator, and an electrolyte.

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