High-performance lithium manganate cathode material with a low oxygen vacancy rate and method for manufacturing the same

Abstract

A high-performance lithium manganese oxide cathode material with a low oxygen vacancy rate, characterized by an oxygen vacancy content range of 10 to 10,000 ppm after being defined by electron paramagnetic resonance spectroscopy, is obtained. The manufacturing method of this cathode material includes the steps of mixing a Li-source compound, a Mn-source compound, and a compound containing a flux element and performing primary calcination in an air atmosphere, and mixing the primary calcination product with a compound containing monovalent metal ions and performing secondary calcination in an air atmosphere at a lower temperature than the primary calcination, followed by cooling and pulverization. The obtained high-performance lithium manganese oxide cathode material has an oxygen vacancy content reduced to 1080 ppm and a Mn elution amount reduced to 23 ppm, significantly improving high-temperature cycling and storage performance, and this product can be relatively well applied to power terminal fields such as passenger cars, electric bicycles, and power tools.

Description

[Technical Field]

[0001] This invention belongs to the field of lithium-ion battery cathode materials, and more particularly to a high-performance lithium manganese oxide cathode material with a low oxygen vacancy rate and a method for producing the same. [Background technology]

[0002] Lithium manganese oxide (LiMn2O4) is a commonly used cathode material. Its low cost, ease of synthesis, and good low-temperature performance have led to its widespread application in lithium-ion batteries. The crystalline structure of lithium manganese oxide belongs to the cubic system, with a space group of Fd3m. In common synthesis processes within the industry, crystalline defects generally occur. For example, if the reaction rate in the sintering process is too fast or oxygen penetration is insufficient, oxygen vacancies result from the absence of internal oxygen atoms. Such structural defects weaken the bond energy between metal atoms and oxygen atoms, promoting the dissolution of trivalent manganese from the spinel structure, leading to disproportionation effects that dissolve manganese and consume the cathode active material, thus reducing battery performance and lifespan. Therefore, oxygen vacancies in lithium manganese oxide crystals are a significant factor influencing performance degradation. Process optimization measures are necessary to reduce the proportion of oxygen vacancies and achieve high performance for successful application in the power sector.

[0003] Patent document CN108091858A discloses a lithium-rich cathode material doped with lithium manganate at the Li-O position and a method for producing the same. The lithium-rich cathode material is doped and modified by doping with an elemental lithium compound, and the elemental lithium compound doped at the Li position is doped with N and P at the Li position, and / or the elemental lithium compound doped at the O position is doped with F and Cl at the O position, thereby forming a strong covalent bond or a portion of Mn 4+It is reduced to reduce the charge compensation of oxygen atoms in the charge-discharge process and reduce the generation of oxygen vacancies. However, what is reduced in this patent is the oxygen vacancies generated in the charge-discharge process of layered lithium manganate with the molecular formula Li2MnO3, which is different in that the present invention solves the oxygen vacancies in the crystal structure itself, and the manufacturing process is complicated.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technical problem to be solved by the present invention is to overcome the above-mentioned deficiencies and defects mentioned in the background art, reduce the proportion of oxygen vacancies in the conventional lithium manganate cathode material, and provide a high-performance lithium manganate cathode material with a low proportion of oxygen vacancies and a manufacturing method thereof.

[0005] In order to reduce the influence of oxygen vacancies in lithium manganate crystals on battery performance, it can be optimized by controlling the heat treatment process of the material and adding an appropriate amount of additives. For example, by using appropriate high-temperature firing parameters and adding metal compounds for doping, etc., the proportion of oxygen vacancies and the Mn elution amount in lithium manganate crystals can be effectively reduced, and its electrochemical performance can be improved.

Means for Solving the Problems

[0006] In order to solve the above technical problems, the technical solution proposed by the present invention is as follows.

[0007] A high-performance lithium manganate cathode material with a low proportion of oxygen vacancies, wherein the high-performance lithium manganate cathode material is characterized by electron paramagnetic resonance spectroscopy, and its oxygen vacancy content is 10-10000 ppm, indicating that the number of vacancies per 1000 oxygen atoms is 0.01-10.

[0008] The oxygen vacancy content can be characterized by EPR (Electron Paramagnetic Resonance Spectroscopy). In lithium manganese oxide crystals, oxygen deficiency causes the generation of unpaired electrons by inducing hole formation and changes in the redox state of manganese ions. By using EPR technology, the characteristic spectral lines of these unpaired electrons can be detected, and the presence and content of oxygen vacancies can be quantitatively detected by the internal standard method. At the same time, oxygen vacancies cause a small plateau phenomenon at the end of the discharge curve during the electrical performance test of the product, and the oxygen deficiency situation is determined by the proportion of the capacity below 3.5V in the first discharge curve when characterizing the product to account for the total discharge capacity.

[0009] Regarding the above high-performance lithium manganese oxide cathode material, preferably, the molecular formula of the high-performance lithium manganese oxide cathode material is Li 1+x (M1) y (M2) z Mn 2-x-y-z O4, where 0 < x < 0.15, 0 < y < 0.15, 0 < z < 0.15, M1 is at least one of the monovalent metal elements K, Na, Li, and M2 is at least one of B, Nb, Mo, V.

[0010] Preferably, the Mn elution amount of the high-performance lithium manganese oxide cathode material is ≤100 ppm.

[0011] Preferably, the tap density of the high-performance lithium manganese oxide cathode material is ≥1.6 g / cm 3 and the specific surface area is 0.15 - 1.20 m 2 / g, the particle size D50 is 10 - 20 μm, and the span value is 0.5 - 1.20.

[0012] Based on the overall inventive concept, the present invention further provides a method for manufacturing the above high-performance lithium manganese oxide cathode material with a low proportion of oxygen vacancies. This manufacturing method includes: Step (1) of uniformly mixing a Li source compound, a Mn source compound, and a compound containing a flux element in a stoichiometric ratio to obtain a primary mixture, Step (2) of subjecting the primary mixture to primary firing, cooling, and pulverization in an air atmosphere to obtain a primary fired product; Step (3) of mixing the primary fired product and a compound containing a monovalent metal ion to obtain a secondary mixture; Step (4) of subjecting the secondary mixture to secondary firing in an air atmosphere, setting the temperature of the secondary firing to be lower than that of the primary firing, cooling, and pulverizing to obtain the high-performance lithium manganate cathode material.

[0013] The high-performance lithium manganate of the present invention dopes a flux substance during the first sintering, introduces a flux element (M2 element) for doping, melts the grain boundaries inside and on the surface of the lithium manganate particles, confines the atoms in the crystal to form a dense network structure, thereby effectively reducing the formation of oxygen vacancies. The secondary sintering adds a monovalent metal cation compound for doping to reduce the manganese elution formed by the disproportionation reaction of trivalent manganese, controls the secondary sintering temperature to be relatively low, forms an annealing part, which is advantageous for repairing the internal defects of the lattice in the sintering process, reduces the oxygen vacancy content, and obtains the final high-performance lithium manganate cathode material. The molecular formula of this high-performance lithium manganate cathode material is Li 1+x (M1) y (M2) z Mn 2-x-y-z O4, where 0 < x < 0.15, 0 < y < 0.15, 0 < z < 0.15, M1 is at least one of the monovalent metal elements K, Na, Li, and M2 is at least one of B, Nb, Mo, V.

[0014] Preferably, in step (1) of the above manufacturing method, the Li source compound is at least one of LiCO3, LiOH, and LiCl, and the Mn source compound is at least one of MnO2, Mn2O3, Mn3O4, MnCO3, and Mn5O8.

[0015] Preferably, in step (1), the compound containing the flux element is at least one of an oxide, hydroxide, phosphate, carbonate, hydroxyl oxide, or alkali containing the flux element, and the flux element is at least one of B, Nb, Mo, or V.

[0016] Preferably, in step (2), the primary firing temperature is 750 to 1100°C, the heating rate is 1 to 5°C / min, the firing time is 2 to 20 hours, and the amount of air permeation in the air atmosphere is 0.1 to 3 m³ for every 1 kg of primary mixture fired. 3 The value is / h, and the particle size D50 of the primary calcination product after grinding is 10-20 μm.

[0017] Preferably, in step (3), the compound containing the monovalent metal ion is at least one of an oxide, hydroxide, phosphate, carbonate, hydroxyl oxide, or alkali containing a monovalent metal element, and the monovalent metal element is at least one of Li, Na, and K.

[0018] Preferably, in step (4), the temperature of the secondary firing is 500 to 750°C, the time is 2 to 15 hours, and the amount of air permeation in the air atmosphere is 0.1 to 3 m³ for every 1 kg of the primary mixture fired. 3 The value is / h, and the particle size D50 of the secondary calcination product after grinding is 10-20 μm. [Effects of the Invention]

[0019] Compared to conventional technology, the advantages of the present invention are as follows:

[0020] (1) In this invention, a flux element (M2 element) compound is incorporated during the initial sintering. Through the action of the flux element, lithium and the flux element penetrate into the manganese source matrix particles, and at high temperatures, lithium manganate particles are formed around the manganese source particle matrix. This flux element has a relatively low melting point and adhesive strength, melting the grain boundaries inside and on the surface of the lithium manganate particles, trapping atoms in the crystal and forming a tight network structure, thereby effectively reducing the formation of oxygen vacancies. When secondary sintering is performed, a compound containing monovalent metal ions (M1 element) is incorporated at a relatively low temperature to balance the total valence of Mn, allowing oxygen vacancies in the manganese source matrix to be repaired at low temperatures, thereby significantly improving its cycle and storage performance. This flux element and monovalent metal cation compound are compounded after two sinterings, concentrating fine powder particles or fine particles and making them easier to fix on the surface of larger particles. This results in high particle size concentration, reduced specific surface area, reduced direct contact between the cathode material and the electrolyte, which is advantageous for the stability of the material structure in long-cycle processes.

[0021] (2) The manufacturing method of the present invention reduces the oxygen vacancy content in the high-performance lithium manganate cathode material obtained from 38,140 ppm to 1,080 ppm and reduces the amount of Mn eluted from about 203 ppm to 23 ppm, thereby significantly improving high-temperature cycling and storage performance, and making this product relatively easy to apply to power terminal fields such as passenger cars, electric bicycles, and power tools. [Brief explanation of the drawing]

[0022] To more clearly illustrate embodiments of the present invention or technical concepts in the prior art, the following briefly introduces the drawings that may be used in the embodiments or prior art descriptions. Obviously, the drawings in the following description are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these without expending any creative effort. [Figure 1] This is the XRD spectrum of the high-performance lithium manganate synthesized in Example 1. [Figure 2] This is the SEM spectrum of the high-performance lithium manganate synthesized in Example 1. [Figure 3] This is a particle size distribution diagram of the high-performance lithium manganate synthesized in Example 1. [Figure 4] This is a capacity decay curve diagram of the high-performance lithium manganate synthesized in Example 1 under room temperature (25°C) cycling. [Figure 5] This is a capacity decay curve diagram of the high-performance lithium manganate synthesized in Example 1 under high-temperature (45°C) cycling. [Figure 6] This is the SEM spectrum of the high-performance lithium manganate synthesized in Example 2. [Figure 7] This is the SEM spectrum of the high-performance lithium manganate synthesized in Example 3. [Figure 8] This is the SEM spectrum of the high-performance lithium manganate synthesized in Example 4. [Modes for carrying out the invention]

[0023] To facilitate understanding of the present invention, the present invention will be described more comprehensively and in detail below by combining the specification drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0024] Unless otherwise defined, all technical terms used herein have the same meaning as those generally understood by those skilled in the art. The technical terms used herein are solely for the purpose of describing the objectives of the specific embodiments and are not intended to limit the scope of protection of the invention.

[0025] Unless otherwise specified, the various raw materials, reagents, instruments, and apparatus used in this invention can all be purchased on the market or manufactured by conventional methods.

[0026] Example 1: A high-performance lithium manganate cathode material with a low oxygen vacancy rate, and its molecular formula is Li 1.075 Na0.008 Mn 1.912 B 0.005 It is O4.

[0027] The method for producing the high-performance lithium manganese oxide cathode material of this embodiment includes the following steps.

[0028] (1) Li 1.075 Mn 1.912 B 0.005 After designing and calculating the mixing ratio using the stoichiometric ratio, 10 kg of manganese source raw material Mn3O4, 2.679 kg of lithium carbonate, and 20.8 g of flux element compound H3BO3 were added to a high-speed mixer and mixed at 500 rpm for 5 minutes, then further mixed at 1500 rpm for 20 minutes. After mixing was complete, white spots were visually confirmed to obtain the mixture. (2) A box-type atmosphere furnace is used, the mixture obtained in step (1) is placed in a sagger, the filling amount is 50% of the sagger's capacity, the sagger is placed in the sintering equipment, the air atmosphere is ventilated, and the ventilation rate is 1 m 3 / h / kg of mixture (1 m³ per 1 kg of mixture to be sintered) 3 The airflow rate is set to / h, the temperature is raised to 850°C at a rate of 2.5°C / min, then maintained at a constant temperature for 10 hours, after which it is allowed to cool naturally to room temperature and removed from the furnace. (3) The mixture sintered in step (2) is rolled and then pulverized with a jet mill grinding machine, filtered through a 300 mesh to remove sieved material, and a powder of 12 μm or less is obtained, i.e., the primary calcination product is obtained. (4) Take 10 kg of the primary calcination product, weigh 28.5 g of the compound Na2CO3 containing monovalent metal ions, put it into the high-speed mixer of the mixing equipment, mix first at a low speed of 400 rpm for 5 minutes, and then mix at 1500 rpm for 15 minutes to obtain the mixture. (5) The mixture obtained in step (4) was calcined at 700°C for 5 hours, cooled to room temperature, pulverized, and sieved through a 300-mesh sieve to obtain the final sample, i.e., the final lithium manganate product. A sample was taken and subjected to XRD testing to obtain the compound phase, and the XRD spectrum is shown in Figure 1.

[0029] As can be seen from Figure 1, the product obtained in this embodiment was found to be free of impurities in the physical phase and to have excellent crystallinity, as detected by XRD.

[0030] The final sample produced in this embodiment was scanned using an electron microscope scanner (SEM). As shown in Figure 2, the primary particles were uniform, no fine powder particles were attached to the surface, and the tap density was 2.2 g / cm³. 3 It has a relatively high tap density, a dense internal structure, and a specific surface area of ​​0.21 m². 2 The value is / g, particle size D50 = 12 μm, and span[(D90-D10) / D50] value is 0.96.

[0031] In this embodiment, the high-performance lithium manganese oxide product synthesized was used as the positive electrode and assembled into a CR2032 button cell, and its initial charge-discharge capacity was evaluated. The positive electrode was manufactured by mixing high-performance lithium manganese oxide, SP (conductive carbon black), and PVDF (adhesive) in a mass ratio of 92.5:0.5:0.25, uniformly coating it onto aluminum foil, drying, rolling, and cutting it to produce the positive electrode plate. A metallic lithium sheet was used as the negative electrode plate. The batteries were assembled and sealed in a glove box, left for 10 hours to activate, and then tested in a Shinwei 5V, 5mA test cabinet. The initial charge-discharge cycle was performed in a voltage range of 3.0~4.3V and 0.1C to determine the initial cycle capacity. As shown in Figure 3, the initial discharge capacity reached 107.5mAh / g, the initial efficiency reached 98%, the proportion of the initial discharge capacity below 3.5V to the total discharge capacity was 0.21%, and the 1C / 0.1C ratio reached 98%, indicating excellent multiplier performance. The fabricated button batteries were simultaneously characterized for Mn elution. After being left to stand and activated for 10 hours, they were charged and discharged for one week, then fully charged. The batteries were disassembled, the positive electrode plate was placed in a 5 mL plastic bottle, 4 mL of electrolyte was added, and the plastic bottle was stored in a 60°C oven for two weeks. The electrolyte was extracted with a syringe, filtered, diluted after acid treatment, and the Mn content was tested by ICP to obtain the amount of Mn eluted. In this example, the amount of Mn eluted was measured to be 23 ppm using the above method.

[0032] In this embodiment, the high-performance lithium manganese oxide synthesized was used as the positive electrode and assembled into a 053048A type pouch cell. The positive electrode slurry was prepared using high-performance lithium manganese oxide:SP (conductive carbon black):PVDF (adhesive) = 93.5:3.25:3.25, and the negative electrode slurry was prepared using FSN-1 (Shanghai Shanshan artificial graphite):SP (conductive carbon black):CMC:SBR = 94.8:1.5:1.7:2.0. The positive electrode slurry was uniformly applied to aluminum foil, and the negative electrode slurry was uniformly applied to copper foil. After sheet formation, assembly, liquid injection, and chemical conversion, the cells were tested in a Xinwei test cabinet with a voltage test range of 3.0~4.2V. Cycle performance was tested at room temperature (25°C) and high temperature (45°C). Figure 4 shows the charge-discharge cycle decay curve at room temperature (25°C), and the capacity retention rate after 1000 cycles reached 86.2%. Figure 5 shows the charge-discharge cycle curve spectrum at a high temperature of 45°C, where the capacity retention rate reached 73% after 800 cycles.

[0033] The high-performance lithium manganate synthesized in this example was characterized by oxygen vacancy analysis using EPR, and its oxygen vacancy content was 1080 ppm.

[0034] Example 2: The high-performance lithium manganate cathode material of the present invention, which has a low oxygen vacancy ratio, has the molecular formula Li 1.065 Li 0.009 Mn 1.925 Mo 0.001 Characterized by O4

[0035] The method for producing the high-performance lithium manganese oxide cathode material of this embodiment includes the following steps.

[0036] Li 1.065 Mn 1.925 Mo 0.001After designing and calculating the mixing ratio, 10 kg of manganese source raw material Mn3O4, 2.636 kg of battery-grade lithium carbonate, and 9.6 g of compound MoO3 containing flux elements were weighed and added to the high-speed mixer of the mixing equipment. The parameters for mixing and sintering were consistent with those of Example 1. After obtaining the primary calcination product, 14.4 g of compound LiOH containing monovalent metal ions was added to 10 kg of the primary calcination product and thoroughly mixed. After adding to the high-speed mixer of the mixing equipment, the parameters for mixing and sintering were consistent with those of Example 1. The final sample, i.e., high-performance lithium manganese oxide cathode material, was obtained.

[0037] The relevant performance of the high-performance lithium manganese oxide cathode material of this example was tested according to the same method as in Example 1, and the oxygen vacancy content of the final product, as characterized by EPR, was 1530 ppm. The final sample produced in this example was scanned using an electron microscope scanner, and the results, as shown in Figure 6, showed that the primary particles were uniform, no fine powder particles adhered to the surface, and the tap density of the material was 2.2 g / cm³. 3 The specific surface area is 0.50 m². 2 The particle size is D50 = 11.3 μm, and the span [(D90-D10) / D50] value is 0.92. The manufactured button cell was charged and discharged at a voltage range of 3.0~4.3V and 0.1C. The initial discharge capacity reached 112.5 mAh / g, the initial efficiency reached 97%, and the proportion of the initial discharge capacity below 3.5V to the total discharge capacity was 0.36%. The amount of Mn eluted, according to the Mn elution characterization, was 42 ppm. The manufactured pouch cells were tested at a voltage test range of 3.0~4.2V, achieving a 1C / 0.1C ratio of 99%. The capacity retention rate after 1000 cycles at room temperature was 84%, and at a high temperature of 45°C, the capacity retention rate after 800 cycles reached 76%.

[0038] Example 3: The high-performance lithium manganate cathode material of the present invention, which has a low oxygen vacancy ratio, has the molecular formula Li 1.045 Na 0.007 Mn 1.942 Nb 0.006 Characterized by O4

[0039] The method for producing the high-performance lithium manganese oxide cathode material of this embodiment includes the following steps.

[0040] Li 1.045 Mn 1.942 Nb 0.006 After designing and calculating the mixing ratio, 10 kg of manganese source raw material MnO2, 2.20 kg of battery-grade lithium carbonate, and 45 g of the flux element compound Nb2O5 were weighed and added to the high-speed mixer of the mixing equipment. The parameters for mixing and sintering were consistent with those of Example 1. After obtaining the primary calcination product, 10 kg of the primary calcination product was mixed with 16 g of the monovalent metal ion compound Na2CO3, and after thorough mixing, it was added to the high-speed mixer of the mixing equipment. The parameters for mixing and sintering were consistent with those of Example 1. The final sample, i.e., high-performance lithium manganese oxide cathode material, was obtained.

[0041] The relevant performance of the high-performance lithium manganese oxide cathode material of this example was tested according to the same method as in Example 1, and the oxygen vacancy content of the final product, as characterized by EPR, was 2340 ppm. The final sample produced in this example was scanned using an electron microscope scanner, and the results, as shown in Figure 7, show that the primary particles are uniform and the tap density of the material is 2.1 g / cm³. 3 The specific surface area is 0.68 m². 2 The manufactured button cell was charged and discharged at a voltage range of 3.0~4.3V and 0.1C. The initial discharge capacity reached 116.3mAh / g, the initial efficiency reached 95%, and the proportion of the initial discharge capacity below 3.5V to the total discharge capacity was 0.64%. In the Mn elution test, the elution amount was 51ppm. The manufactured pouch cell was tested at a voltage test range of 3.0~4.2V, the 1C / 0.1C ratio reached 99%, the capacity retention rate after 1000 cycles at room temperature was 82%, and the capacity retention rate after 800 cycles at a high temperature of 45°C reached 75%.

[0042] Example 4: The high-performance lithium manganate cathode material of the present invention, which has a low oxygen vacancy ratio, has the molecular formula Li 1.055 K 0.008 Mn 1.932 V 0.005 Characterized by O4

[0043] The method for producing the high-performance lithium manganese oxide cathode material of this embodiment includes the following steps.

[0044] Li 1.055 Mn 1.932 V 0.005 After designing and calculating the mixing ratio, 10 kg of manganese source raw material Mn3O4, 2.602 kg of battery-grade lithium carbonate, and 30.20 g of the flux element compound V2O5 were weighed and added to the high-speed mixer of the mixing equipment. The parameters for mixing and sintering were all the same as in Example 1. After obtaining the primary calcination product, 29.81 g of the monovalent metal ion compound KOH was added to 10 kg of the primary calcination product and mixed thoroughly. After adding to the high-speed mixer of the mixing equipment, the parameters for mixing and sintering were all the same as in Example 1. The final sample, i.e., high-performance lithium manganese oxide cathode material, was obtained.

[0045] The relevant performance of the high-performance lithium manganese oxide cathode material of this example was tested according to the same method as in Example 1, and the oxygen vacancy content of the final product, as characterized by EPR, was 3500 ppm. The final sample produced in this example was scanned using an electron microscope scanner, and the results, as shown in Figure 8, show that the primary particles are uniform and the tap density of the material is 2.1 g / cm³. 3 The specific surface area is 0.32 m². 2The manufactured button cell was charged and discharged at a voltage range of 3.0~4.3V and 0.1C. The initial discharge capacity reached 117.8mAh / g, the initial efficiency reached 97.5%, and the proportion of the initial discharge capacity below 3.5V to the total discharge capacity was 0.47%. In the Mn elution test, the elution amount was 62ppm. The manufactured pouch cell was tested at a voltage test range of 3.0~4.2V, the 1C / 0.1C ratio reached 99%, the capacity retention rate after 1000 cycles at room temperature was 83%, and the capacity retention rate after 800 cycles at a high temperature of 45°C reached 74%.

[0046] Comparative Example 1: The only difference between the method for producing the high-performance lithium manganese oxide cathode material in this comparative example and Example 1 is that H3BO3 is not added in step (1).

[0047] Using the same evaluation method as in Example 1, the oxygen vacancy content of the final product of Comparative Example 1, as determined by EPR characterization, was 14,500 ppm. The tap density of the material was 2.1 g / cm³. 3 The specific surface area is 0.65 m². 2 The values ​​are / g, particle size D50 = 14μm, span[(D90-D10) / D50] value is 1.15, and the manufactured button battery was charged and discharged in the voltage range of 3.0~4.3V and 0.1C. The initial discharge capacity reached 102.6mAh / g, the initial efficiency was 93%, the proportion of the initial discharge capacity below 3.5V to the total discharge capacity was 1.05%, and the 1C / 0.1C ratio was 92%. The Mn elution amount was 155ppm.

[0048] The cells were assembled into 053048A pouch cells and tested within a voltage test range of 3.0 to 4.2V. Cycle performance was tested at ambient temperature (25°C) and high temperature (45°C). At ambient temperature (25°C), the charge-discharge cycle decay curve showed a capacity retention rate of 70% after 1000 cycles and 65% after 800 cycles.

[0049] Comparative Example 2: The method for producing the high-performance lithium manganese oxide cathode material in this comparative example differs from that of Example 1 only in step (4). The specific operation of step (4) is to put 10 kg of the primary calcination product into a high-speed mixer of a mixing device, mix it at a low speed of 400 rpm for 5 minutes without adding Na2CO3, and then mix it at 1500 rpm for 15 minutes to obtain the material to be secondary sintered.

[0050] Using the same evaluation method as in Example 1, the oxygen vacancy content of the final product of Comparative Example 2, as determined by EPR characterization, was 28,260 ppm. The tap density of the material was 1.9 g / cm³. 3 The specific surface area is 0.58 m². 2 The manufactured button cell was charged and discharged at a voltage range of 3.0~4.3V and 0.1C. The initial discharge capacity was 106.0mAh / g, the initial efficiency was 93.3%, and the proportion of the initial discharge capacity below 3.5V to the total discharge capacity was 1.33%. In the Mn elution test, the 053048A type pouch cell manufactured with an elution amount of 125ppm was tested at a voltage test range of 3.0~4.2V, the 1C / 0.1C ratio reached 92%, the capacity retention rate after 1000 cycles at room temperature was 73%, and the capacity retention rate after 800 cycles at a high temperature of 45°C was 60%.

[0051] Comparative Example 3: The method for producing the high-performance lithium manganese oxide cathode material in this comparative example is the same as the method in Example 1, that is, the methods in steps (1) and (4) are different, and the difference is that H3BO3 is not added in step (1) and Na2CO3 is not added in step (4).

[0052] Using the same evaluation method as in Example 1, the oxygen vacancy content of the final product of Comparative Example 3, as determined by EPR characterization, was 38140 ppm. The tap density of the material was 1.9 g / cm³. 3 The specific surface area is 0.70 m². 2The manufactured button cell was charged and discharged at a voltage range of 3.0~4.3V and 0.1C. The initial discharge capacity reached 105.2mAh / g, the initial efficiency reached 91%, and the proportion of the initial discharge capacity below 3.5V to the total discharge capacity was 1.78%. In the Mn elution test, the 053048A type pouch cell manufactured with an elution amount of 203ppm was tested at a voltage test range of 3.0~4.2V, the 1C / 0.1C ratio reached 95%, the capacity retention rate after 1000 cycles at room temperature was 60%, and the capacity retention rate after 800 cycles at a high temperature of 45℃ was 53%.

Claims

1. A high-performance lithium manganese oxide cathode material with a low oxygen vacancy ratio, wherein the high-performance lithium manganese oxide cathode material is characterized by having an oxygen vacancy content of 10 to 10,000 ppm after being characterized by electron paramagnetic resonance spectroscopy.

2. The molecular formula of the high-performance lithium manganate cathode material is Li １＋ｘ (M １ ) ｙ (M ２ ) ｚ Mn ２－ｘ－ｙ－ｚ O ４ , where 0 < x < 0.15, 0 < y < 0.15, 0 < z < 0.15, and M １ is at least one of the monovalent metal elements K, Na, and Li, and M ２ is at least one of the flux elements B, Nb, Mo, and V. The high-performance lithium manganate cathode material according to claim 1, characterized in that.

3. The high-performance lithium manganate cathode material according to claim 1, characterized in that the amount of Mn eluted from the high-performance lithium manganate cathode material is ≤ 100 ppm.

4. The tap density of the aforementioned high-performance lithium manganate cathode material is ≥ 1.6 g / cm³. ３ The specific surface area is 0.15 to 1.20 m². ２ The high-performance lithium manganese oxide cathode material according to any one of claims 1 to 3, characterized in that the density is / g, the particle size D50 is 10 to 20 μm, and the span value is 0.50 to 1.

20.

5. A method for producing a high-performance lithium manganate cathode material with a low oxygen vacancy ratio according to any one of claims 1 to 4, Step (1) involves uniformly mixing a Li-source compound, a Mn-source compound, and a compound containing a flux element in stoichiometric ratios to obtain a primary mixture. Step (2) involves first calcining the primary mixture in an air atmosphere, cooling and grinding it to obtain a primary calcination product. Step (3) involves mixing the primary calcination product with a compound containing monovalent metal ions to obtain a secondary mixture. A manufacturing method characterized by comprising step (4) of second calcining the secondary mixture in an air atmosphere, lowering the temperature of the second calcination to that of the primary calcination, cooling and pulverizing to obtain a secondary calcination product which is the high-performance lithium manganese cathode material.

6. In step (1), the Li source compound is LiCO ３ The Mn source compound is at least one of LiOH and LiCl, and the Mn source compound is MnO ２ Mn ２ O ３ Mn ３ O ４ MnCO ３ Mn ５ O ８ The manufacturing method according to claim 5, characterized in that it is at least one of the following.

7. The manufacturing method according to claim 5, characterized in that, in step (1), the compound containing the flux element is at least one of an oxide, hydroxide, phosphate, carbonate, hydroxyl oxide, or alkali containing the flux element, and the flux element is at least one of B, Nb, Mo, or V.

8. In step (2), the primary firing temperature is 750 to 1100°C, the heating rate is 1 to 5°C / min, the firing time is 2 to 20 hours, and for every 1 kg of primary mixture fired, the amount of air permeation in the air atmosphere is 0.1 to 3 m ３ The manufacturing method according to claim 5, characterized in that the ratio is / h and the particle size D50 of the primary calcination product after grinding is 10 to 20 μm.

9. The manufacturing method according to claim 5, characterized in that, in step (3), the compound containing the monovalent metal ion is at least one of an oxide, hydroxide, phosphate, carbonate, hydroxyl oxide, or alkali containing a monovalent metal element, and the monovalent metal element is at least one of Li, Na, and K.

10. In step (4), the temperature of the secondary firing is 500 to 750°C, the time is 2 to 15 hours, and the amount of air permeation in the air atmosphere is 0.1 to 3 m³ for every 1 kg of the secondary mixture fired. ３ The manufacturing method according to any one of claims 5 to 9, characterized in that the ratio is / h and the particle size D50 of the secondary calcination product after grinding is 10 to 20 μm.

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