Glassy indium-yttrium oxide modified ternary layered oxide positive electrode material and preparation method thereof

Abstract

The application discloses a glassy indium yttrium oxide modified ternary layered oxide positive electrode material and a preparation method thereof. The preparation method comprises the following steps: (1) uniformly mixing and grinding N-vinylamide polymer, indium acetate, yttrium acetate and a ternary layered oxide positive electrode material to form a uniform mixed powder; (2) mixing the mixed powder with ultrapure water to form a suspension, and then performing ultrasonic dispersion; (3) heating and evaporating the sample after ultrasonic dispersion; (4) sintering the sample after evaporation, and naturally cooling the sintered product to room temperature; (5) grinding, washing and drying the sintered product, and then grinding and sieving the sintered product again to obtain a final product. The inner core structure of the obtained positive electrode material is a ternary layered oxide positive electrode material, and the outer layer is a glassy indium yttrium oxide coating layer derived in situ. The method improves the capacity stability and voltage attenuation problems of the ternary layered oxide positive electrode material in the cycle process, improves the rate performance of the material, and is suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery cathode material preparation technology, specifically to a glassy indium yttrium oxide modified ternary layered oxide cathode material and its preparation method. Background Technology

[0002] Lithium-ion rechargeable batteries occupy an important position in consumer electronics and power battery fields due to their high energy density, portability, and stability. However, their actual energy density is usually between 300 Wh / kg and 400 Wh / kg, mainly limited by the development of positive and negative electrode materials. Among them, the low capacity and energy density of positive electrode materials are particularly prominent, becoming a key factor restricting battery development. Although practical lithium cobalt oxide and lithium iron phosphate positive electrode material systems have been widely used, their capacity still cannot meet the demand. Ternary oxide positive electrode materials, with specific capacities as high as 200 mAh / g to 300 mAh / g and high operating voltages, have attracted widespread attention and are expected to break through existing bottlenecks to achieve ultra-high energy density. However, they face problems such as oxygen loss, irreversible crystal phase transformation, dissolution of transition metal ions, electrolyte decomposition, and gas escape during charge and discharge, resulting in poor cycle capacity and voltage stability. At the same time, their rate performance and coulombic efficiency are also low, which seriously restricts practical applications. To improve stability, researchers have carried out a lot of doping and coating modification work: for example, Lun et al. found that fluorine doping can suppress Mn 3+ The Jahn-Teller distortion promotes orbital rearrangement and increases the redox involvement of manganese, thereby improving the overall capacity; Guo et al. achieved a capacity of 217 mAh g at 0.5 C rate by co-doping with fluorine and aluminum. -1 The capacity was maintained at 88.21% after 150 cycles, and it still retained 157 mAh g at 10 C. -1 Specific capacity. Heterogeneous structure coating is also a common method; Ma et al. utilized Al 3+ Chemical conversion in phosphate buffer constructed a highly uniform AlPO4 coating layer on the material surface, enabling the material to withstand 30 mAg. -1 A current density of 282.1 mAh g was obtained. -1 The discharge specific capacity; in 2018, Zhang et al. constructed a 14 nm thick Li4Mn5O... 12The spinel coating effectively reduces activation and oxygen loss in the material during the initial charge above 4.5 V, improving coulombic efficiency and significantly enhancing cycle stability and rate performance, resulting in a capacity retention of 83.1% after 300 cycles at 0.1 C. However, single doping or coating modifications have limited effects and cannot simultaneously address the differences in structural and performance degradation mechanisms driven by different surface and bulk structural characteristics. This leads to performance limitations in practical applications, and the material is still some distance from fully meeting application requirements. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a glassy indium yttrium oxide modified ternary layered oxide cathode material with excellent electrochemical performance and cycle stability, and its preparation method. The preparation method is simple, energy-efficient, and suitable for large-scale production, and is expected to promote the practical application of ternary layered oxide cathode materials.

[0004] To solve the above-mentioned technical problems, the technical solution proposed by this invention is: a method for preparing a glassy indium yttrium oxide modified ternary layered oxide cathode material, comprising the following steps:

[0005] (1) N-vinylamide polymer, indium acetate, yttrium acetate and ternary layered oxide cathode material are mixed and ground to form a uniform mixed powder;

[0006] (2) The mixed powder is mixed with ultrapure water to form a suspension and then ultrasonically dispersed;

[0007] (3) Heat and evaporate the ultrasonically dispersed sample;

[0008] (4) The sample after evaporation is sintered and then naturally cooled to room temperature to obtain the sintered product;

[0009] (5) After grinding, washing and drying the sintered product, grind and sieve it again to obtain the final product.

[0010] In the above-mentioned method for preparing glassy indium yttrium oxide modified ternary layered oxide cathode material, preferably, in step (1), the N-vinylamide polymer is polyvinylpyrrolidone or polyvinylcaprolactam.

[0011] In the above-mentioned method for preparing glassy indium yttrium oxide modified ternary layered oxide cathode material, preferably, in step (1), the mass ratio of the N-vinylamide polymer, indium acetate, yttrium acetate and ternary layered oxide cathode material is 0.01~0.02:0.009~0.018:0.001~0.002:1.

[0012] In the above-mentioned method for preparing glassy indium yttrium oxide modified ternary layered oxide cathode material, preferably, the cathode material is a lithium-rich manganese-based or high-nickel ternary cathode material.

[0013] In the above-mentioned method for preparing glassy indium yttrium oxide modified ternary layered oxide cathode material, preferably, step (3) involves adding the ultrasonically dispersed sample into a split-type flask and then installing it on a heating device for heating and evaporation; the heating device is one of water bath heating, heating jacket heating, magnetic stirring heating, or rotary evaporator heating device.

[0014] In the above-mentioned method for preparing glassy indium yttrium oxide modified ternary layered oxide cathode material, preferably, in step (3), the evaporation conditions are a temperature of 100℃~150℃ and a rotation speed of 10r / min~60r / min.

[0015] In the above-mentioned method for preparing glassy indium yttrium oxide modified ternary layered oxide cathode material, preferably, in step (4), the sintering heating rate is 1℃ / min~15℃ / min, the sintering temperature is 500℃, and the sintering time is 5h.

[0016] In the above-mentioned method for preparing glassy indium yttrium oxide modified ternary layered oxide cathode material, preferably, in step (5), the drying temperature is 60°C and the drying time is 1h to 6h.

[0017] As a general technical concept, the present invention also provides a method for preparing the above-mentioned glassy indium yttrium oxide modified ternary layered oxide cathode material, resulting in a glassy indium yttrium oxide modified ternary layered oxide cathode material.

[0018] Preferably, in the above-mentioned glassy indium yttrium oxide modified ternary layered oxide cathode material, the core structure of the glassy indium yttrium oxide modified ternary layered oxide cathode material is a ternary layered oxide cathode material, and the outer layer is a glassy indium yttrium oxide coating layer obtained in situ.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] Synergistic Modification Process and Structural Optimization: This invention employs N-vinylamide polymers, indium acetate, and yttrium acetate to synergistically modify ternary layered oxide cathode materials. The N-vinylamide polymers effectively increase the surface activity of the ternary cathode material and promote the uniform adhesion of indium acetate and yttrium acetate. Rotary evaporation technology ensures sufficient dispersion of each component in the liquid phase, guaranteeing the uniformity of subsequent coating. Through high-temperature heat treatment, the N-vinylamide polymers decompose into gases such as carbon dioxide, water vapor, and nitrogen dioxide, which are then released. Simultaneously, indium acetate and yttrium acetate decompose to generate oxides with strong interfacial bonding to the ternary layered oxide cathode material. Ultimately, a glassy indium yttrium oxide-coated ternary layered oxide cathode material is successfully prepared.

[0021] Significantly Enhanced Electrochemical Performance: The obtained glassy indium yttrium oxide (IYO) coating significantly improves the surface structural stability of the material, effectively suppressing oxygen loss, transition metal ion dissolution, and electrolyte decomposition under high voltage, thereby greatly improving cycle stability. The coating exhibits high interface compatibility with the substrate, providing not only a stable interface but also facilitating rapid lithium-ion intercalation / deintercalation, thus enhancing ionic conductivity. Combined with the coating's own high electronic conductivity, these factors collectively significantly improve the material's rate performance.

[0022] The method is simple and offers outstanding comprehensive benefits: This preparation method is a one-step synthesis process that only requires calcination at 500℃ for 5 hours. It has the advantages of simple process, low energy consumption, and low cost, making it very suitable for large-scale industrial production. Under the comprehensive effect of the glassy indium yttrium oxide coating, the modified material exhibits optimized reaction kinetics, suppressed voltage decay, and alleviated crystal phase transformation and transition metal dissolution problems. Ultimately, it achieves a comprehensive improvement in cycle stability, rate performance, and voltage stability, resulting in excellent overall electrochemical performance. Attached Figure Description

[0023] Figure 1 This is a scanning electron microscope (SEM) image of the unmodified ternary layered oxide cathode material prepared in Comparative Example 1 of this invention, wherein... Figure 1 (a) Figure 1 (b) Figure 1 (c) are scanning electron microscope images magnified 10K, 30K, and 50K times, respectively.

[0024] Figure 2 This is a scanning electron microscope (SEM) image of the glassy indium yttrium oxide-modified ternary layered oxide cathode material prepared in Example 1 of this invention. Figure 2 (a) Figure 2 (b) Figure 2 (c) are scanning electron microscope images magnified 10K, 30K, and 50K times, respectively.

[0025] Figure 3The images show the first charge-discharge cycles at 0.2C for the batteries prepared in Example 3 and Comparative Example 1 of this invention.

[0026] Figure 4 The images show the capacity cycling curves of the batteries prepared in Examples 1-3 and Comparative Examples 1-4 of this invention at 1C.

[0027] Figure 5 The capacity cycle curves of the batteries prepared in Examples 1-3 and Comparative Examples 1-4 of this invention are obtained by continuous discharge at 0.2C, 0.5C, 1C, 2C, 5C, and 0.2C, with ten charge-discharge cycles at each rate.

[0028] Figure 6 The images show the first charge-discharge cycles at 0.2C for the batteries prepared in Example 4 and Comparative Example 5 of this invention.

[0029] Figure 7 This is a capacity cycling curve at 1C for the batteries prepared in Example 4 and Comparative Example 5 of the present invention.

[0030] Figure 8 This is a schematic diagram of the glassy indium yttrium oxide modified ternary layered oxide cathode material model obtained in Examples 1-4 of the present invention. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. Unless otherwise specified, the raw materials and instruments used in the following embodiments are commercially available. The room temperature conditions in the following embodiments are all between 20°C and 30°C.

[0032] In this invention, the source of the ternary layered oxide cathode material is not limited; it can be purchased through commercial channels or prepared using methods known in the art.

[0033] Example 1:

[0034] A method for preparing a glassy indium yttrium oxide-modified ternary layered oxide (lithium-rich manganese-based) cathode material according to the present invention includes the following steps:

[0035] (1) Place 0.05g polyvinylpyrrolidone, 0.045g indium acetate, 0.005g yttrium acetate and 5.0g lithium-rich manganese-based cathode material in a ball mill jar and grind at 350rpm for 1h.

[0036] (2) Take out the ground mixture and mix it with 400ml of ultrapure water. Transfer the mixed liquid to a split single-necked flask and then put it into an ultrasonic cleaner for ultrasonic treatment for 10min to fully disperse and mix the polyvinylpyrrolidone, indium acetate, yttrium acetate and lithium-rich manganese-based cathode material.

[0037] (3) The single-necked flask containing the mixed sample after ultrasonic treatment is installed on a rotary evaporator and the water in the flask is evaporated to dryness at 120℃ and 40r / min.

[0038] (4) Take out the dried sample and transfer it to a crucible. Then put the crucible containing the mixture into a muffle furnace. The muffle furnace is heated to 500°C at 10°C / min and held for 5 hours. Then it is naturally cooled to room temperature to obtain the sintered product.

[0039] (5) Grind the obtained sintered product, wash it three times with deionized water, dry it in a forced-air drying oven at 60°C for 3 hours, and then grind it again through a 200-mesh sieve to obtain the final product.

[0040] A glassy indium yttrium oxide modified ternary layered oxide (lithium-rich manganese-based) cathode material was prepared by the preparation method of Example 1.

[0041] The core structure of this glassy indium yttrium oxide modified ternary layered oxide (lithium-rich manganese-based) cathode material is a lithium-rich manganese-based cathode material, and the outer layer is a glassy indium yttrium oxide coating layer obtained in situ.

[0042] Example 2:

[0043] A method for preparing a glassy indium yttrium oxide-modified ternary layered oxide (lithium-rich manganese-based) cathode material according to the present invention includes the following steps:

[0044] (1) Place 0.1g polyvinyl caprolactam, 0.09g indium acetate, 0.01g yttrium acetate and 5.0g lithium-rich manganese-based cathode material in a ball mill jar and grind at 350rpm for 1h.

[0045] (2) Take out the ground mixture and mix it with 400ml of ultrapure water. Transfer the mixed liquid to a split single-necked flask and then put it into an ultrasonic cleaner for ultrasonic treatment for 10min to fully disperse and mix the polyvinyl caprolactam, indium acetate, yttrium acetate and lithium-rich manganese-based cathode material.

[0046] (3) The single-necked flask containing the mixed sample after ultrasonic treatment is installed on a rotary evaporator and the water in the flask is evaporated to dryness at 120℃ and 40r / min.

[0047] (4) Take out the dried sample and transfer it to a crucible. Then put the crucible containing the mixture into a muffle furnace. The muffle furnace is heated to 500°C at 10°C / min and held for 5 hours. Then it is naturally cooled to room temperature to obtain the sintered product.

[0048] (5) Grind the obtained sintered product, wash it three times with deionized water, dry it in a forced-air drying oven at 60°C for 3 hours, and then grind it again through a 200-mesh sieve to obtain the final product.

[0049] A glassy indium yttrium oxide modified ternary layered oxide (lithium-rich manganese-based) cathode material was prepared by the preparation method of Example 2.

[0050] The core structure of this glassy indium yttrium oxide modified ternary layered oxide (lithium-rich manganese-based) cathode material is a lithium-rich manganese-based cathode material, and the outer layer is a glassy indium yttrium oxide coating layer obtained in situ.

[0051] Example 3:

[0052] A method for preparing a glassy indium yttrium oxide-modified ternary layered oxide (lithium-rich manganese-based) cathode material according to the present invention includes the following steps:

[0053] (1) Place 0.1g polyvinylpyrrolidone, 0.09g indium acetate, 0.01g yttrium acetate and 5.0g lithium-rich manganese-based cathode material in a ball mill jar and grind at 350rpm for 1h.

[0054] (2) Take out the ground mixture and mix it with 400ml of ultrapure water. Transfer the mixed liquid to a split single-necked flask and then put it into an ultrasonic cleaner for ultrasonic treatment for 10min to fully disperse and mix the polyvinylpyrrolidone, indium acetate, yttrium acetate and lithium-rich manganese-based cathode material.

[0055] (3) The single-necked flask containing the mixed sample after ultrasonic treatment is installed on a rotary evaporator and the water in the flask is evaporated to dryness at 120℃ and 40r / min.

[0056] (4) Take out the dried sample and transfer it to a crucible. Then put the crucible containing the mixture into a muffle furnace. The muffle furnace is heated to 500°C at 10°C / min and held for 5 hours. Then it is naturally cooled to room temperature to obtain the sintered product.

[0057] (5) Grind the obtained sintered product, wash it three times with deionized water, dry it in a forced-air drying oven at 60°C for 3 hours, and then grind it again through a 200-mesh sieve to obtain the final product.

[0058] A glassy indium yttrium oxide modified ternary layered oxide (lithium-rich manganese-based) cathode material was prepared by the preparation method of Example 3.

[0059] The core structure of this glassy indium yttrium oxide modified ternary layered oxide (lithium-rich manganese-based) cathode material is a lithium-rich manganese-based cathode material, and the outer layer is a glassy indium yttrium oxide coating layer obtained in situ.

[0060] Example 4:

[0061] A method for preparing a glassy indium yttrium oxide-modified ternary layered oxide (high-nickel) cathode material according to the present invention includes the following steps:

[0062] (1) Place 0.1g polyvinylpyrrolidone, 0.09g indium acetate, 0.01g yttrium acetate and 5.0g high-nickel ternary layered cathode material in a ball mill jar and grind at 350rpm for 1h.

[0063] (2) Take out the ground mixture and mix it with 400ml of ultrapure water. Transfer the mixed liquid to a split single-necked flask and then put it into an ultrasonic cleaner for ultrasonic treatment for 10 minutes to fully disperse and mix the polyvinylpyrrolidone, indium acetate, yttrium acetate and high nickel ternary layered cathode material.

[0064] (3) The single-necked flask containing the mixed sample after ultrasonic treatment is installed on a rotary evaporator and the water in the flask is evaporated to dryness at 120℃ and 40r / min.

[0065] (4) Take out the dried sample and transfer it to a crucible. Then put the crucible containing the mixture into a muffle furnace. The muffle furnace is heated to 500°C at 10°C / min and held for 5 hours. Then it is naturally cooled to room temperature to obtain the sintered product.

[0066] (5) Grind the obtained sintered product, wash it three times with deionized water, dry it in a forced-air drying oven at 60°C for 3 hours, and then grind it again through a 200-mesh sieve to obtain the final product.

[0067] A glassy indium yttrium oxide modified ternary layered oxide (high nickel) cathode material was prepared by the preparation method of Example 4.

[0068] The core structure of this glassy indium yttrium oxide modified ternary layered oxide (high nickel) cathode material is a high nickel ternary layered cathode material, and the outer layer is a glassy indium yttrium oxide coating layer obtained in situ.

[0069] Comparative Example 1:

[0070] An unmodified ternary layered oxide cathode material differs from Example 1 in that indium yttrium is not added to modify the ternary cathode material, while the remaining steps are the same as in Example 1.

[0071] Comparative Example 2:

[0072] A method for preparing a modified ternary layered oxide cathode material with glassy coating and only indium doping, comprising the following steps:

[0073] (1) Place 0.1g polyvinylpyrrolidone, 0.09g indium acetate and 5.0g lithium-rich manganese-based cathode material in a ball mill jar and grind at 350rpm for 1h.

[0074] (2) Take out the ground mixture and mix it with 400ml of ultrapure water. Transfer the mixed liquid to a split single-necked flask and then put it into an ultrasonic cleaner for ultrasonic treatment for 10min to fully disperse and mix the polyvinylpyrrolidone, indium acetate and lithium-rich manganese-based cathode material.

[0075] (3) The single-necked flask containing the mixed sample after ultrasonic treatment is installed on a rotary evaporator and the water in the flask is evaporated to dryness at 120℃ and 40r / min.

[0076] (4) Take out the dried sample and transfer it to a crucible. Then put the crucible containing the mixture into a muffle furnace. The muffle furnace is heated to 500°C at 10°C / min and held for 5 hours. Then it is naturally cooled to room temperature to obtain the sintered product.

[0077] (5) Grind the obtained sintered product, wash it three times with deionized water, dry it in a forced-air drying oven at 60°C for 3 hours, and then grind it again through a 200-mesh sieve to obtain the final product.

[0078] A modified ternary layered oxide cathode material with glassy coating and only indium doped was prepared by the preparation method of Comparative Example 2.

[0079] The core structure of this modified ternary layered oxide cathode material is a lithium-rich manganese-based cathode material, and the outer layer is an in-situ derived glassy indium oxide coating layer.

[0080] Comparative Example 3:

[0081] A method for preparing a modified ternary layered oxide cathode material with glassy coating and only yttrium doping, comprising the following steps:

[0082] (1) Place 0.1g polyvinylpyrrolidone, 0.01g yttrium acetate and 5.0g lithium-rich manganese-based cathode material in a ball mill jar and grind at 350rpm for 1h.

[0083] (2) Take out the ground mixture and mix it with 400ml of ultrapure water. Transfer the mixed liquid to a split single-necked flask and then put it into an ultrasonic cleaner for ultrasonic treatment for 10 minutes to fully disperse and mix the polyvinylpyrrolidone, yttrium acetate and lithium-rich manganese-based cathode material.

[0084] (3) The single-necked flask containing the mixed sample after ultrasonic treatment is installed on a rotary evaporator and the water in the flask is evaporated to dryness at 120℃ and 40r / min.

[0085] (4) Take out the dried sample and transfer it to a crucible. Then put the crucible containing the mixture into a muffle furnace. The muffle furnace is heated to 500°C at 10°C / min and held for 5 hours. Then it is naturally cooled to room temperature to obtain the sintered product.

[0086] (5) Grind the obtained sintered product, wash it three times with deionized water, dry it in a forced-air drying oven at 60°C for 3 hours, and then grind it again through a 200-mesh sieve to obtain the final product.

[0087] A modified ternary layered oxide cathode material with glassy coating and only yttrium doping was prepared by the method of Comparative Example 3.

[0088] The core structure of this modified ternary layered oxide cathode material is a lithium-rich manganese-based cathode material, and the outer layer is a glassy yttrium oxide coating layer obtained in situ.

[0089] Comparative Example 4:

[0090] A method for preparing a modified ternary layered oxide cathode material doped only with indium yttrium without glassy coating includes the following steps:

[0091] (1) Place 0.09g indium acetate, 0.01g yttrium acetate and 5.0g high-nickel ternary layered cathode material in a ball mill jar and grind at 350rpm for 1h.

[0092] (2) Take out the ground mixture and mix it with 400ml of ultrapure water. Transfer the mixed liquid to a split single-necked flask and then put it into an ultrasonic cleaner for ultrasonic treatment for 10 minutes to fully disperse and mix the indium acetate, yttrium acetate and high nickel cathode material.

[0093] (3) The single-necked flask containing the mixed sample after ultrasonic treatment is installed on a rotary evaporator and the water in the flask is evaporated to dryness at 120℃ and 40r / min.

[0094] (4) Take out the dried sample and transfer it to a crucible. Then put the crucible containing the mixture into a muffle furnace. The muffle furnace is heated to 500°C at 10°C / min and held for 5 hours. Then it is naturally cooled to room temperature to obtain the sintered product.

[0095] (5) Grind the obtained sintered product, wash it three times with deionized water, dry it in a forced-air drying oven at 60°C for 3 hours, and then grind it again through a 200-mesh sieve to obtain the final product.

[0096] A modified ternary layered oxide cathode material, doped only with indium yttrium without glassy coating, was prepared by the method of Comparative Example 4.

[0097] The core structure of this modified ternary layered oxide cathode material is a high-nickel cathode material, and the outer layer is an in-situ derived indium yttrium oxide coating layer.

[0098] Comparative Example 5:

[0099] An unmodified ternary cathode material, with a high-nickel ternary layered cathode material as the core, differs from Example 4 in that it does not have indium yttrium added for modification, while the remaining steps are the same as in Example 4.

[0100] Electrochemical performance testing method: A 5% (w / w) PVDF solution was prepared by dissolving polyvinylidene fluoride (PVDF) in N-methylpyrrolidone and stirring until homogeneous. The positive electrode material, conductive carbon black SP, and the PVDF solution prepared in the examples and comparative examples were mixed and ground in a mass ratio of 8:1:1. The mixture was then homogenized in a homogenizer for 10 minutes to obtain a viscous positive electrode slurry. The positive electrode slurry was evenly coated onto aluminum foil using a 100-mesh scraper, vacuum dried at 110°C for 12 hours, and then rolled using a roller press to obtain the positive electrode sheet. The positive electrode sheet was punched into 12mm round pieces using a punching machine, weighed, and placed in a glove box for assembly into 2016-type button batteries. A Celgard 2400 separator was used, and the electrolyte consisted of 1.2 M lithium hexafluorophosphate, with a solvent of ethylene carbonate: methyl ethyl carbonate = 3:7, and 1% lithium difluorooxalate borate additive was added. The assembled button batteries were allowed to stand for 12 hours before electrochemical performance testing. The electrochemical performance results of the examples and comparative examples are compared in Table 1.

[0101]

[0102] As shown in Table 1, the glassy indium yttrium oxide modified ternary layered oxide (lithium-rich manganese-based) cathode material prepared by synergistic modification with polyvinylpyrrolidone, indium acetate and yttrium acetate in Example 1 has an initial discharge specific capacity of 250.61 mAh / g at 0.2C. After two cycles of activation at 0.2C, the discharge specific capacity in the third cycle is 220.28 mAh / g. The cathode material has a cycle specific capacity of 121.74 mAh / g after 500 cycles at 1C, with a capacity retention rate of 55.27% and a voltage retention rate of 70.38%. The average discharge specific capacity at 5C is 90.93 mAh / g.

[0103] Example 2 uses polyvinyl caprolactam, indium acetate and yttrium acetate to synergistically modify the glassy indium yttrium oxide modified ternary layered oxide (lithium-rich manganese-based) cathode material. The initial discharge specific capacity at 0.2C is 196.88 mAh / g. After two cycles at 0.2C for activation, the discharge specific capacity in the third cycle is 155.11 mAh / g. The cathode material has a cycle specific capacity of 140.45 mAh / g after 500 cycles at 1C, with a capacity retention rate of 90.55% and a voltage retention rate of 71.88%. The average discharge specific capacity at 5C is 100.48 mAh / g.

[0104] Example 3 describes a glassy indium yttrium oxide-modified ternary layered oxide (lithium-rich manganese-based) cathode material prepared by synergistic modification with polyvinylpyrrolidone, indium acetate, and yttrium acetate. The initial discharge specific capacity at 0.2C was 237.7 mAh / g. After two cycles at 0.2C for activation, the discharge specific capacity in the third cycle was 207.55 mAh / g. The cathode material had a cycle specific capacity of 180.43 mAh / g after 500 cycles at 1C, with a capacity retention rate of 86.93% and a voltage retention rate of 82.57%. The average discharge specific capacity at 5C was 122.90 mAh / g.

[0105] Example 4 describes a glassy indium yttrium oxide-modified ternary layered oxide (high-nickel) cathode material prepared by synergistic modification with polyvinylpyrrolidone, indium acetate, and yttrium acetate. The initial discharge specific capacity at 0.2C was 139.15 mAh / g. After two cycles at 0.2C for activation, the discharge specific capacity in the third cycle was 111.41 mAh / g. After 500 cycles at 1C, the cathode material had a cycle specific capacity of 100.66 mAh / g, with a capacity retention rate of 90.35% and a voltage retention rate of 99.50%.

[0106] The unmodified ternary layered oxide cathode material prepared in Comparative Example 1 had an initial discharge capacity of 252.08 mAh / g at 0.2C. After two cycles of activation at 0.2C, the discharge specific capacity in the third cycle was 173.97 mAh / g. The cathode material had a cycle specific capacity of 84.4 mAh / g after 500 cycles at 1C, with a capacity retention rate of 48.51% and a voltage retention rate of 81.85%. The average discharge specific capacity at 5C was 62.88 mAh / g.

[0107] The modified ternary layered oxide cathode material with glassy coating and only indium doping prepared in Comparative Example 2 had an initial discharge capacity of 220.57 mAh / g at 0.2C. After two cycles of activation at 0.2C, the discharge specific capacity in the third cycle was 153.47 mAh / g. The cathode material had a cycle specific capacity of 136.46 mAh / g after 500 cycles at 1C, with a capacity retention rate of 88.92% and a voltage retention rate of 86.2%. The average discharge specific capacity at 5C was 85.79 mAh / g.

[0108] The modified ternary layered oxide cathode material with glassy coating and only yttrium doping prepared in Comparative Example 3 had an initial discharge capacity of 182.94 mAh / g at 0.2C. After two cycles of activation at 0.2C, the discharge specific capacity in the third cycle was 128.33 mAh / g. The cathode material had a cycle specific capacity of 89 mAh / g after 500 cycles at 1C, with a capacity retention rate of 69.35% and a voltage retention rate of 86.49%. The average discharge specific capacity at 5C was 79.85 mAh / g.

[0109] The modified ternary layered oxide cathode material prepared in Comparative Example 4, which is doped with only indium yttrium and not glassy, ​​has an initial discharge capacity of 224.28 mAh / g at 0.2C. After two cycles at 0.2C for activation, the discharge capacity in the third cycle is 160.33 mAh / g. The cathode material has a cycle capacity of 125.61 mAh / g after 500 cycles at 1C, with a capacity retention of 78.34% and a voltage retention of 85.92%. The average discharge capacity at 5C is 92.77 mAh / g.

[0110] The unmodified ternary cathode material prepared in Comparative Example 5 had an initial discharge capacity of 126.12 mAh / g at 0.2C. After two cycles at 0.2C for activation, the discharge capacity in the third cycle was 95.27 mAh / g. After 500 cycles at 1C, the cathode material had a cycle capacity of 76.11 mAh / g, a capacity retention rate of 79.89%, and a voltage retention rate of 100%.

[0111] like Figure 1 , Figure 2 As shown in the image, scanning electron microscopy reveals that the cathode material prepared in Example 1 is a secondary sphere formed by the accumulation of tiny primary particles. The primary particles have smooth surfaces, but after modification, the material surface becomes rough, and the loose, porous structure becomes dense.

[0112] from Figure 4 , Figure 5 The cycle performance curves shown indicate that, at room temperature (25°C), when the assembled coin cells are subjected to constant current charge-discharge and rate performance tests at a specific current density, the cutoff voltage range is 2.0V~4.8V (vs Li). + / Li).

[0113] Combining Table 1 and Figure 4 , Figure 5 and Figure 7 It can be seen that the discharge specific capacity and cycle capacity of the ternary layered oxide cathode material modified by N-vinylamide polymers, indium acetate and yttrium acetate synergistically are significantly improved under high current. This is due to the high ionic conductivity and electronic conductivity of the coating layer generated in situ, which improves the reaction kinetics of the material under the combined effect. At the same time, the voltage decay is also suppressed to a certain extent, indicating that the crystal phase transformation in the material is suppressed. The glassy indium yttrium oxide coating layer also helps to improve the problem of transition metal ion dissolution in the cathode material. The cycle stability of the cathode material is significantly improved, and the electrochemical performance of the material is thus comprehensively improved.

[0114] from Figure 7 The cycle performance curves shown indicate that at room temperature (25°C), when the assembled coin cell is subjected to constant current charge-discharge at a specific current density, the cutoff voltage range is 2.8V~4.3V (vs Li). + / Li).

[0115] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for preparing a glassy indium yttrium oxide-modified ternary layered oxide cathode material, characterized in that, Includes the following steps: (1) N-vinylamide polymer, indium acetate, yttrium acetate and ternary layered oxide cathode material are mixed and ground to form a uniform mixed powder; the N-vinylamide polymer is polyvinylpyrrolidone or polyvinylcaprolactam, and the mass ratio of the N-vinylamide polymer, indium acetate, yttrium acetate and ternary layered oxide cathode material is 0.01~0.02:0.009~0.018:0.001~0.002:1; (2) The mixed powder is mixed with ultrapure water to form a suspension and then ultrasonically dispersed; (3) Heat and evaporate the ultrasonically dispersed sample; (4) The sample after evaporation is sintered and then naturally cooled to room temperature to obtain the sintered product; The sintering heating rate is 1℃ / min~15℃ / min, the sintering temperature is 500℃, and the sintering time is 5h; (5) After grinding, washing and drying the sintered product, grind and sieve it again to obtain the final product.

2. The method for preparing the glassy indium yttrium oxide modified ternary layered oxide cathode material according to claim 1, characterized in that... The cathode material is a lithium-rich manganese-based or high-nickel ternary cathode material.

3. The method for preparing the glassy indium yttrium oxide modified ternary layered oxide cathode material according to claim 1, characterized in that, Step (3) involves adding the ultrasonically dispersed sample into a split-type flask and then installing it onto a heating device for heating and evaporation; the heating device is one of water bath heating, heating jacket heating, magnetic stirring heating, or rotary evaporator heating device.

4. The method for preparing the glassy indium yttrium oxide modified ternary layered oxide cathode material according to claim 3, characterized in that, In step (3), the evaporation conditions are a temperature of 100℃~150℃ and a rotation speed of 10r / min~60r / min.

5. The method for preparing the glassy indium yttrium oxide-modified ternary layered oxide cathode material according to claim 1, characterized in that, In step (5), the drying temperature is 60°C and the drying time is 1h to 6h.

6. A glassy indium yttrium oxide-modified ternary layered oxide cathode material, characterized in that, It is prepared by any one of claims 1 to 5.

7. The glassy indium yttrium oxide-modified ternary layered oxide cathode material according to claim 6, characterized in that, The core structure of the glassy indium yttrium oxide modified ternary layered oxide cathode material is a ternary layered oxide cathode material, and the outer layer is a glassy indium yttrium oxide coating layer obtained in situ.

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