Lithium cobalt oxide positive electrode material and preparation method thereof
By polishing and compounding the surface of lithium cobalt oxide positive electrode materials, highly conductive and active lithium cobalt oxide positive electrode materials were prepared, which solved the problem of insufficient battery life of drones and achieved high specific capacity and deep discharge effects, making it suitable for high energy density lithium metal batteries.
Patent Information
- Application Number
- CN202510597576.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-09
- Publication Date
- 2025-09-26
AI Technical Summary
Existing drone batteries have insufficient battery life and low payload capacity, making it difficult to meet the needs of large-scale and long-distance distribution network inspections and other special scenarios. Traditional lithium-ion batteries also have low capacity and energy density, and cannot meet long-term battery life requirements.
Cerium oxide-doped ferric oxide magnetic particles are used as surface polishing powder for lithium cobalt oxide positive electrode materials, combined with aqueous ethanol as a sacrificial homogenizer, and different lithium cobalt oxides are surface polished and compounded through a ball milling process to prepare highly conductive and highly active lithium cobalt oxide positive electrode materials.
The prepared lithium cobalt oxide positive electrode material has a high specific capacity and can be deeply discharged, which solves the problems of low capacity and insufficient deep discharge, improves the energy density and electrochemical activity of the battery, and is suitable for high energy density lithium metal batteries.
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Figure CN120698515A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of electrochemical energy storage, and in particular to a lithium cobalt oxide positive electrode material and a preparation method thereof. Background Art
[0002] Currently, small and medium-sized battery-powered drones are widely used in a variety of scenarios, including surveying, exploration, bridge construction, and natural disaster response. As a crucial component of the power grid, the distribution network serves as a crucial link between the transmission network and users. Regular inspections of distribution lines, along with timely monitoring of their operational status, surrounding environment, and protected areas, are essential for ensuring the normal operation of the power grid and ensuring power supply security. Currently, overhead distribution lines in suburban, rural, and mountainous areas face long lines, complex road conditions, and inconvenient inspection and maintenance by local teams. Intelligent inspection methods, such as drone inspections, offer superior autonomy and high quality, significantly improving the safety and reliability of inspections. Replacing traditional manual inspections with drone inspections has become a growing trend. However, current drones still face challenges with insufficient battery life and payload capacity, making them difficult to meet for large-scale and long-distance distribution network inspections and other specialized applications. Therefore, the development of drone batteries that can meet these diverse needs is urgently needed.
[0003] At present, lithium cobalt oxide, lithium iron phosphate, and ternary cathode materials (such as NCM-811, NCM-622, NCM-532, etc.) have been widely developed and commercialized. However, due to limited capacity, it is difficult to develop high-energy-density lithium metal batteries through these materials. In addition, due to the inability to perform deep discharge, the traditional lithium-ion battery system not only has a relatively low specific capacity, but also has a low energy density, making it difficult to meet the needs of more drone scenarios that require long endurance. Therefore, it is urgent to develop high-capacity, deeply dischargeable cathode materials that can meet the design requirements of high-energy-density lithium metal batteries. Summary of the Invention
[0004] In view of the above shortcomings, the present invention provides a method for preparing a lithium cobalt oxide positive electrode material, which has high capacity and can be deeply discharged. The specific technical solution is as follows:
[0005] A method for preparing a lithium cobalt oxide positive electrode material comprises the following steps:
[0006] (1) Preparation of magnetic polishing powder, comprising:
[0007] S1. Take iron nitrate and cerium nitrate, add to the graphene oxide dispersion, stir and mix evenly, and dry to obtain a mixture; ignite the mixture using a flame and burn it in air until the flame is extinguished to obtain a magnetic polishing powder precursor;
[0008] S2. A magnetic polishing powder precursor was added to the starch dispersion, heated and stirred until completely solidified, and freeze-dried to obtain a dry mixture; the mixture was first calcined in an argon atmosphere and then calcined a second time in air to obtain a magnetic polishing powder;
[0009] (2) ball milling high-rate lithium cobalt oxide and magnetic polishing powder for a period of time, and then removing the magnetic polishing powder using a magnet to obtain pretreated high-rate lithium cobalt oxide;
[0010] (3) ball milling high-voltage lithium cobalt oxide and magnetic polishing powder for a period of time, and then removing the magnetic polishing powder using a magnet to obtain pretreated high-voltage lithium cobalt oxide;
[0011] (4) The high-rate lithium cobalt oxide pretreated in step (2), the high-voltage lithium cobalt oxide pretreated in step (3), and carbon nanotubes are added to a ball mill, and a small amount of mixed solvent is added to obtain a solid-liquid mixture. After ball milling for a period of time, the mixture is dried to obtain a lithium cobalt oxide positive electrode material.
[0012] The technical solution of the present invention is based on the following technical principles: by constructing cerium oxide-doped ferric oxide magnetic particles as magnetic polishing powder for surface polishing of lithium cobalt oxide positive electrode materials, and using aqueous ethanol as a sacrificial homogenizer, two different lithium cobalt oxides are surface polished, modified and composited through a simple ball milling process to achieve the "synergistic effect" of the two different lithium cobalt oxides, thereby obtaining a highly conductive and highly active lithium cobalt oxide positive electrode material.
[0013] Preferably, in the above-mentioned method for preparing the lithium cobalt oxide positive electrode material, in the step (1), the mass ratio of ferric nitrate to cerium nitrate is 10:1 to 12:1, the concentration of the graphene oxide dispersion is 10 to 12 g / L, and the volume ratio of the total mass ratio of ferric nitrate and cerium nitrate to the graphene oxide dispersion is 12 g:0.8 to 1.2 L.
[0014] Preferably, in the above-mentioned method for preparing lithium cobalt oxide positive electrode material, in step (1), the concentration of the starch dispersion is 130-150 g / L, and the ratio of the magnetic polishing powder precursor to the starch dispersion is 1 g:8-12 mL.
[0015] Preferably, in the above-mentioned method for preparing the lithium cobalt oxide positive electrode material, in step (1), the temperature of the first calcination is 800-1000°C, and the calcination time is 1-3 hours; the temperature of the second calcination is 200-300°C, and the calcination time is 4-6 hours.
[0016] Preferably, in the above-mentioned method for preparing the lithium cobalt oxide positive electrode material, in the step (2), the D50 of the high-rate lithium cobalt oxide is 5 to 8 μm, the mass ratio of the high-rate lithium cobalt oxide to the magnetic polishing powder is 25:3 to 50:3, and the high-rate lithium cobalt oxide is a commercially available product; the ball milling speed is 400 to 600 rpm, and the ball milling time is 60 to 90 min.
[0017] Preferably, in the above-mentioned method for preparing the lithium cobalt oxide positive electrode material, in the step (3), the D50 of the high-voltage lithium cobalt oxide is 12 to 20 μm, the mass ratio of the high-voltage lithium cobalt oxide to the magnetic polishing powder is 25:3 to 50:3, and the high-voltage lithium cobalt oxide is a commercially available product; the ball milling speed is 400 to 600 rpm, and the ball milling time is 60 to 90 min.
[0018] Preferably, in the above-mentioned method for preparing the lithium cobalt oxide positive electrode material, in the step (4), the mass ratio of the pretreated high-rate type lithium cobalt oxide to the pretreated high-voltage type lithium cobalt oxide is 5:1 to 1:5, and the amount of carbon nanotubes used is 2.5 to 5% of the total mass of the pretreated high-rate type lithium cobalt oxide and the pretreated high-voltage type lithium cobalt oxide.
[0019] Preferably, in the above-mentioned method for preparing the lithium cobalt oxide positive electrode material, in step (4), the mixed solvent is water and ethanol, the volume ratio of water to ethanol is 1:90 to 1:110, and the solid-liquid ratio in the solid-liquid mixture is 12.6g:5 to 10mL.
[0020] Preferably, in the above-mentioned method for preparing the lithium cobalt oxide positive electrode material, in the step (4), the ball milling speed is 400-600 rpm, the ball milling time is 120-180 min, the drying temperature is 60° C.-80° C., and the drying time is 16-20 h.
[0021] In the preparation method of the lithium cobalt oxide positive electrode material of the present invention, first, a smaller high-rate type lithium cobalt oxide and a larger high-voltage type lithium cobalt oxide are selected for compounding, and the difference in size is used to better achieve effective contact between spherical particles, achieve "synergistic effect", and effectively improve the electrochemical activity of lithium cobalt oxide. At the same time, the surface of the lithium cobalt oxide is polished by a magnetic polishing powder ball milling process to remove inactive structures or unstable structures on the surface, thereby further enhancing the direct contact between the particles. In addition, in order to better achieve the composite of two different lithium cobalt oxides and the tight coating of lithium cobalt oxide by carbon nanotubes, the present invention uses ethanol containing a small amount of water as a sacrificial homogenizer, which can not only effectively promote the uniform mixing of the three materials in the solid state, but also can achieve the interaction between different materials by causing changes in the components of the mixed solvent through the transfer of solvent at a lower temperature, thereby ensuring the formation of a more uniform composite, effectively improving the conductivity of lithium cobalt oxide, and thus improving the electrochemical activity of lithium cobalt oxide.
[0022] On the other hand, the present invention also provides a lithium cobalt oxide positive electrode material, which is prepared by the above-mentioned preparation method.
[0023] Compared with the prior art, the present invention has the following beneficial effects:
[0024] 1. The lithium cobalt oxide positive electrode material prepared by the preparation method of the present invention has high conductivity and obtains a high specific capacity of 710 to 860 mAh / g; it can achieve deep discharge with a discharge voltage range of 0 to 3.3 V, thus solving the problems of low capacity of the positive electrode material and insufficient deep discharge.
[0025] 2. In the preparation method of the present invention, the constructed cerium oxide-doped ferric oxide magnetic particles are used as magnetic polishing powder for surface polishing of lithium cobalt oxide positive electrode materials, and aqueous ethanol is used as a sacrificial homogenizer. Two different lithium cobalt oxides are surface polished, modified and compounded through a simple ball milling process to achieve the "synergistic effect" of the two different lithium cobalt oxides, thereby obtaining a highly conductive and highly active lithium cobalt oxide positive electrode material.
[0026] 3. The preparation method of the present invention is simple to operate, highly efficient, has low energy consumption, and uses conventional equipment. The raw materials, reagents, and equipment used in the preparation of magnetic polishing powder, pretreatment of commercially purchased high-rate lithium cobalt oxide, pretreatment of commercially purchased high-voltage lithium cobalt oxide, and mixing of two lithium cobalt oxide samples can all be obtained commercially, are widely available, and are low in cost, which is conducive to large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can derive other drawings based on these drawings without inventive effort.
[0028] Figure 1 This is an SEM image of the lithium cobalt oxide positive electrode material prepared in Example 1;
[0029] Figure 2 is the XRD pattern of commercially available lithium cobalt oxide sample 1;
[0030] Figure 3 This is the XRD pattern of commercially available lithium cobalt oxide sample 2;
[0031] Figure 4 XRD pattern of the lithium cobalt oxide positive electrode material prepared in Example 1;
[0032] Figure 5 This is the XPS graph of the lithium cobalt oxide positive electrode material prepared in Example 1;
[0033] Figure 6 This is the constant current charge and discharge (GCD) curve of the lithium cobalt oxide positive electrode material prepared in Example 1;
[0034] Figure 7 is the GCD curve of commercially available lithium cobalt oxide sample 1;
[0035] Figure 8 is the GCD curve of commercially available lithium cobalt oxide sample 2;
[0036] Figure 9 This is the GCD curve of the lithium cobalt oxide positive electrode material prepared in Comparative Example 1;
[0037] Figure 10 This is the GCD curve of the lithium cobalt oxide positive electrode material prepared in Comparative Example 2;
[0038] Figure 11 This is the GCD curve of the lithium cobalt oxide positive electrode material prepared in Comparative Example 3. DETAILED DESCRIPTION
[0039] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited by the specific embodiments. Unless otherwise defined, all technical terms used hereinafter have the same meaning as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or can be prepared by existing methods.
[0040] The commercially purchased lithium cobalt oxide sample 1 is a high-rate lithium cobalt oxide with a D50 of 5 to 8 μm (manufacturer: CLOUD, model: MA-EN-CA-0005); the commercially purchased lithium cobalt oxide sample 2 is a high-voltage lithium cobalt oxide with a D50 of 12 to 20 μm (manufacturer: CLOUD, model: MA-EN-CA-0006); the carbon nanotubes are multi-walled carbon nanotubes (manufacturer: CLOUD, MA-EN-CO-0012).
[0041] Example 1
[0042] A method for preparing a lithium cobalt oxide positive electrode material comprises the following steps:
[0043] (1) Preparation of magnetic polishing powder:
[0044] Add 11g of ferric nitrate and 1g of cerium nitrate to 1L of 11g / L graphene oxide dispersion, stir until thoroughly mixed, and then dry in an oven. After drying, remove the mixture, ignite it with a flame, and burn it in air until the flame extinguishes, obtaining a magnetic polishing powder precursor.
[0045] Take 5g of magnetic polishing powder precursor and add it to 50mL of 140g / L starch dispersion. Heat with stirring until completely solidified and then freeze-dry. Then place the dried mixture in an argon-protected tubular furnace at 800℃ for the first high-temperature calcination for 2h, and then calcine it at 300℃ for a second time in air for 4h to obtain magnetic polishing powder.
[0046] (2) Pretreatment of commercially available lithium cobalt oxide sample 1:
[0047] 50 g of commercially available lithium cobalt oxide sample 1 was added to a ball mill, and 5 g of magnetic polishing powder was added. The mixture was ball milled at 600 rpm for 60 min, and the magnetic polishing powder was transferred using a magnet to obtain pretreated sample 1 for later use.
[0048] (3) Pretreatment of commercially available lithium cobalt oxide sample 1:
[0049] 50 g of commercially available lithium cobalt oxide sample 2 was added to a ball mill, and 5 g of magnetic polishing powder was added. The mixture was ball milled at 600 rpm for 60 min, and the magnetic polishing powder was transferred using a magnet to obtain pretreated sample 2 for later use.
[0050] (4) Mixing of two lithium cobalt oxide samples:
[0051] Take 6 g of pretreated commercially purchased lithium cobalt oxide sample 1, 6 g of commercially purchased lithium cobalt oxide sample 2, and 0.6 g of carbon nanotubes, add them to a ball mill, and then add 5 mL of a mixed solvent of water and ethanol with a volume ratio of 1:100. After ball milling at a speed of 600 rpm for 120 minutes, place it in an 80°C forced air drying oven and dry it for 16 hours to obtain a lithium cobalt oxide positive electrode material.
[0052] Example 2
[0053] A method for preparing a lithium cobalt oxide positive electrode material comprises the following steps:
[0054] (1) Preparation of magnetic polishing powder:
[0055] 11g of ferric nitrate and 1g of cerium nitrate were added to 1L of an 11g / L graphene oxide dispersion, stirred until uniformly mixed, and then dried in an oven. After drying, the mixture was removed and ignited with a flame, burning in air until the flame extinguished, yielding a magnetic polishing powder precursor.
[0056] Take 5g of magnetic polishing powder precursor and add it to 50mL of 140g / L starch dispersion. Heat it with stirring until it is completely solidified and then freeze-dry it. Then place the dried mixture in an argon-protected tubular furnace at 800℃ for the first high-temperature calcination for 2h, and then calcine it at 300℃ for a second time in air for 4h to obtain magnetic polishing powder.
[0057] (2) Pretreatment of commercially available lithium cobalt oxide sample 1:
[0058] 50 g of commercially available lithium cobalt oxide sample 1 was added to a ball mill, and 4 g of magnetic polishing powder was added. The mixture was ball milled at 500 rpm for 80 min, and the magnetic polishing powder was transferred using a magnet to obtain pretreated sample 1 for later use.
[0059] (3) Pretreatment of commercially available lithium cobalt oxide sample 2:
[0060] 50 g of commercially available lithium cobalt oxide sample 2 was added to a ball mill, and 4 g of magnetic polishing powder was added. The mixture was ball milled at 500 rpm for 80 min, and the magnetic polishing powder was transferred using a magnet to obtain pretreated sample 2 for later use.
[0061] (4) Mixing of two lithium cobalt oxide samples:
[0062] Take 10g of pretreated sample 1, 2g of pretreated sample 2, and 0.6g of carbon nanotubes, add them to a ball mill, then add 5mL of a mixed solvent of water and ethanol with a volume ratio of 1:100, ball mill for 120min at a speed of 500rpm, place it in an 80℃ forced air drying oven and dry it for 16h, and ball mill for 120min to obtain lithium cobalt oxide positive electrode material for standby use.
[0063] Example 3
[0064] A method for preparing a lithium cobalt oxide positive electrode material comprises the following steps:
[0065] (1) Preparation of magnetic polishing powder:
[0066] 11g of ferric nitrate and 1g of cerium nitrate were added to 1L of an 11g / L graphene oxide dispersion, stirred until uniformly mixed, and then dried in an oven. After drying, the mixture was removed and ignited with a flame, burning in air until the flame extinguished, yielding a magnetic polishing powder precursor.
[0067] Take 5g of magnetic polishing powder precursor and add it to 50mL of 140g / L starch dispersion. Heat it with stirring until it is completely solidified and then freeze-dry it. Then place the dried mixture in an argon-protected tubular furnace at 800℃ for the first high-temperature calcination for 2h, and then calcine it at 300℃ for a second time in air for 4h to obtain magnetic polishing powder.
[0068] (2) Pretreatment of commercially available lithium cobalt oxide sample 1:
[0069] 50 g of commercially available lithium cobalt oxide sample 1 was added to a ball mill, and 5 g of magnetic polishing powder was added. The mixture was ball milled at 600 rpm for 60 min, and the magnetic polishing powder was transferred using a magnet to obtain pretreated sample 1 for later use.
[0070] (3) Pretreatment of commercially available lithium cobalt oxide sample 2:
[0071] 50 g of commercially available lithium cobalt oxide sample 2 was added to a ball mill, and 5 g of magnetic polishing powder was added. The mixture was ball milled at 600 rpm for 60 min, and the magnetic polishing powder was transferred using a magnet to obtain pretreated sample 2 for later use.
[0072] (4) Mixing of two lithium cobalt oxide samples:
[0073] Take 2g of pretreated sample 1, 10g of pretreated sample 2, and 0.6g of carbon nanotubes, add them to a ball mill, and then add 8mL of a mixed solvent of water and ethanol with a volume ratio of 1:90. After ball milling at a speed of 600rpm for 120min, place it in an 80℃ forced air drying oven and dry it for 20h to obtain lithium cobalt oxide positive electrode material.
[0074] Example 4
[0075] A method for preparing a lithium cobalt oxide positive electrode material comprises the following steps:
[0076] (1) Preparation of magnetic polishing powder:
[0077] 11g of ferric nitrate and 1g of cerium nitrate were added to 1L of an 11g / L graphene oxide dispersion, stirred until uniformly mixed, and then dried in an oven. After drying, the mixture was removed and ignited with a flame, burning in air until the flame extinguished, yielding a magnetic polishing powder precursor.
[0078] Take 5g of magnetic polishing powder precursor and add it to 50mL of 140g / L starch dispersion. Heat it with stirring until it is completely solidified and then freeze-dry it. Then place the dried mixture in an argon-protected tubular furnace at 800℃ for the first high-temperature calcination for 2h, and then calcine it at 300℃ for a second time in air for 4h to obtain magnetic polishing powder.
[0079] (2) Pretreatment of commercially available lithium cobalt oxide sample 1:
[0080] 50 g of commercially available lithium cobalt oxide sample 1 was added to a ball mill, and 5 g of magnetic polishing powder was added. The mixture was ball milled at 600 rpm for 60 min, and the magnetic polishing powder was transferred using a magnet to obtain pretreated sample 1 for later use.
[0081] (3) Pretreatment of commercially available lithium cobalt oxide sample 2:
[0082] 50 g of commercially available lithium cobalt oxide sample 2 was added to a ball mill, and 5 g of magnetic polishing powder was added. The mixture was ball milled at 600 rpm for 60 min, and the magnetic polishing powder was transferred using a magnet to obtain pretreated sample 2 for later use.
[0083] (4) Mixing of two lithium cobalt oxide samples:
[0084] Take 6 g of pretreated sample 1, 6 g of pretreated sample 2, and 0.3 g of carbon nanotubes, add them to a ball mill, and then add 5 mL of a mixed solvent of water and ethanol with a volume ratio of 1:100. After ball milling at a speed of 600 rpm for 120 minutes, place it in an 80°C forced air drying oven and dry it for 20 hours to obtain a lithium cobalt oxide positive electrode material.
[0085] Example 5
[0086] A method for preparing a lithium cobalt oxide positive electrode material comprises the following steps:
[0087] (1) Preparation of magnetic polishing powder:
[0088] 11g of ferric nitrate and 1g of cerium nitrate were added to 1L of an 11g / L graphene oxide dispersion, stirred until uniformly mixed, and then dried in an oven. After drying, the mixture was removed and ignited with a flame, burning in air until the flame extinguished, yielding a magnetic polishing powder precursor.
[0089] Take 5g of magnetic polishing powder precursor and add it to 50mL of 140g / L starch dispersion. Heat it with stirring until it is completely solidified and then freeze-dry it. Then place the dried mixture in an argon-protected tubular furnace at 800℃ for the first high-temperature calcination for 2h, and then calcine it at 300℃ for a second time in air for 4h to obtain magnetic polishing powder.
[0090] (2) Pretreatment of commercially available lithium cobalt oxide sample 1:
[0091] 50 g of commercially available lithium cobalt oxide sample 1 was added to a ball mill, and 5 g of magnetic polishing powder was added. The mixture was ball milled at 600 rpm for 60 min, and the magnetic polishing powder was transferred using a magnet to obtain pretreated sample 1 for later use.
[0092] (3) Pretreatment of commercially available lithium cobalt oxide sample 2:
[0093] 50 g of commercially available lithium cobalt oxide sample 2 was added to a ball mill, and 5 g of magnetic polishing powder was added. The mixture was ball milled at 600 rpm for 60 min, and the magnetic polishing powder was transferred using a magnet to obtain pretreated sample 2 for later use.
[0094] (4) Mixing of two lithium cobalt oxide samples:
[0095] Take 4 g of pretreated sample 1, 8 g of pretreated sample 2, and 0.6 g of carbon nanotubes, add them to a ball mill, and then add 5 mL of a mixed solvent of water and ethanol with a volume ratio of 1:100. After ball milling at a speed of 600 rpm for 120 minutes, place it in an 80°C forced air drying oven and dry it for 16 hours to obtain a lithium cobalt oxide positive electrode material.
[0096] Comparative Example 1
[0097] A method for preparing a lithium cobalt oxide positive electrode material comprises the following steps:
[0098] (1) Pretreatment of commercially available lithium cobalt oxide sample 1:
[0099] 50 g of commercially available lithium cobalt oxide sample 1 was added to a ball mill and ball milled at 600 rpm for 60 min to obtain pretreated sample 1 for later use.
[0100] (2) Pretreatment of commercially available lithium cobalt oxide sample 2:
[0101] 50 g of commercially available lithium cobalt oxide sample 2 was added to a ball mill and ball milled at 600 rpm for 60 min to obtain pretreated sample 2 for later use.
[0102] (3) Mixing of two lithium cobalt oxide samples:
[0103] Take 6 g of pretreated sample 1, 6 g of pretreated sample 2, and 0.6 g of carbon nanotubes, add them to a ball mill, and then add 5 mL of a mixed solvent of water and ethanol with a volume ratio of 1:100. After ball milling at a speed of 600 rpm for 120 minutes, place it in an 80°C forced air drying oven and dry it for 16 hours to obtain a lithium cobalt oxide positive electrode material.
[0104] Comparative Example 2
[0105] A method for preparing a lithium cobalt oxide positive electrode material comprises the following steps:
[0106] (1) Preparation of magnetic polishing powder:
[0107] 11g of ferric nitrate and 1g of cerium nitrate were added to 1L of an 11g / L graphene oxide dispersion, stirred until uniformly mixed, and then dried in an oven. After drying, the mixture was removed and ignited with a flame, burning in air until the flame extinguished, yielding a magnetic polishing powder precursor.
[0108] Take 5g of magnetic polishing powder precursor and add it to 50mL of 140g / L starch dispersion. Heat it with stirring until it is completely solidified and then freeze-dry it. Then place the dried mixture in an argon-protected tubular furnace at 800℃ for the first high-temperature calcination for 2h, and then calcine it at 300℃ for a second time in air for 4h to obtain magnetic polishing powder.
[0109] (2) Pretreatment of commercially available lithium cobalt oxide sample 1:
[0110] 50 g of commercially available lithium cobalt oxide sample 1 was added to a ball mill, and 5 g of magnetic polishing powder was added. The mixture was ball milled at 600 rpm for 60 min, and the magnetic polishing powder was transferred using a magnet to obtain pretreated sample 1 for later use.
[0111] (3) Pretreatment of commercially available lithium cobalt oxide sample 2:
[0112] 50 g of commercially available lithium cobalt oxide sample 2 was added to a ball mill, and 5 g of magnetic polishing powder was added. The mixture was ball milled at 600 rpm for 60 min, and the magnetic polishing powder was transferred using a magnet to obtain pretreated sample 2 for later use.
[0113] (4) Mixing of two lithium cobalt oxide samples:
[0114] 6 g of pretreated sample 1, 6 g of pretreated sample 2, and 0.6 g of carbon nanotubes were added to a ball mill, ball milled at 600 rpm for 120 min, and then dried in an 80° C. forced air drying oven for 16 h to obtain a lithium cobalt oxide positive electrode material for later use.
[0115] Comparative Example 3
[0116] A method for preparing a lithium cobalt oxide positive electrode material comprises the following steps:
[0117] (1) Preparation of magnetic polishing powder:
[0118] 11g of ferric nitrate was added to 1L of 11g / L graphene oxide dispersion, stirred until uniformly mixed, and then dried in an oven. After drying, the mixture was removed and ignited with a flame, burning in air until the flame extinguished, yielding a magnetic polishing powder precursor.
[0119] Take 5g of magnetic polishing powder precursor and add it to 50mL of 140g / L starch dispersion. Heat it with stirring until it is completely solidified and then freeze-dry it. Then place the dried mixture in an argon-protected tubular furnace at 800℃ for the first high-temperature calcination for 2h, and then calcine it at 300℃ for a second time in air for 4h to obtain magnetic polishing powder.
[0120] (2) Pretreatment of commercially available lithium cobalt oxide sample 1:
[0121] 50 g of commercially available lithium cobalt oxide sample 1 was added to a ball mill, and 5 g of magnetic polishing powder was added. The mixture was ball milled at 600 rpm for 60 min, and the magnetic polishing powder was transferred using a magnet to obtain pretreated sample 1 for later use.
[0122] (3) Pretreatment of commercially available lithium cobalt oxide sample 2:
[0123] 50 g of commercially available lithium cobalt oxide sample 2 was added to a ball mill, and 5 g of magnetic polishing powder was added. After ball milling at 600 rpm for 60 min, the magnetic polishing powder was transferred using a magnet to obtain pretreated sample 2 for later use.
[0124] (4) Mixing of two lithium cobalt oxide samples:
[0125] Take 6 g of pretreated commercially purchased lithium cobalt oxide sample 1, 6 g of commercially purchased lithium cobalt oxide sample 2, and 0.6 g of carbon nanotubes, add them to a ball mill, and then add 5 mL of a mixed solvent of water and ethanol with a volume ratio of 1:100. After ball milling at a speed of 600 rpm for 120 minutes, place it in an 80°C forced air drying oven and dry it for 16 hours to obtain a lithium cobalt oxide positive electrode material for later use.
[0126] Among them, (1) the specific composition of the lithium ion battery is:
[0127] Positive electrode sheet: Commercially purchased lithium cobalt oxide and the positive electrode materials provided in the examples and comparative examples were used as positive electrode active materials. The positive electrode active materials were mechanically mixed with a binder (PVDF) and a conductive agent (conductive carbon black) in a mass ratio of 8:1:1 to obtain a negative electrode slurry. The negative electrode slurry was coated on the surface of a copper foil and dried at 80°C for 12 hours to obtain a positive electrode sheet;
[0128] Negative electrode: lithium metal sheet;
[0129] Electrolyte: EC, DMC and EMC were used as a mixed solvent in a volume ratio of 1:1:1, and LiPF6 was added to form a 1 mol / L LiPF6 electrolyte;
[0130] Diaphragm: 2320 separator, the main components include polyethylene (PE), aluminum oxide (as part of the ceramic coating) and polyvinylidene fluoride (PVDF);
[0131] Lithium-ion battery assembly: button-type lithium-ion batteries are assembled in an inert atmosphere glove box in the order of spring-gasket-negative electrode sheet-diaphragm-positive electrode sheet;
[0132] (2) GCD test:
[0133] The assembled button lithium-ion battery was subjected to GCD test in the voltage range of 0-3.3 V and a current density of 1 A / g.
[0134] Figure 1 This is the SEM image of the lithium cobalt oxide positive electrode material prepared in Example 1. Figure 1 It can be seen from the graph that the surface of the lithium cobalt oxide particles prepared in Example 1 is round and tightly wrapped with carbon nanotubes, indicating that the method of the present invention has obvious effects in surface polishing and coating. Figure 2 It can be seen that the characteristic diffraction peaks presented are all characteristic peaks of lithium cobalt oxide, and the peaks are sharp, indicating that the purchased lithium cobalt oxide sample 1 has high crystallinity. Figure 3 It can be seen that the characteristic diffraction peaks presented are all characteristic peaks of lithium cobalt oxide, and the peaks are sharp, indicating that the purchased lithium cobalt oxide sample 2 has a high degree of crystallinity. Figure 4It can be seen that the characteristic diffraction peaks presented are all characteristic peaks of lithium cobalt oxide, and the peaks are sharp, indicating that the crystallinity of the lithium cobalt oxide sample prepared in Example 1 is high and will not affect its crystallinity. Figure 5 It can be seen from the figure that the lithium cobalt oxide sample prepared in Example 1 is composed of Co, Li, O, and C, indicating that the surface of the lithium cobalt oxide has been successfully coated with carbon nanotubes.
[0135] from Figure 6 It can be seen that the discharge capacity of the lithium cobalt oxide positive electrode material prepared in Example 1 is 835 mAh / g. Figure 7 It can be seen that the discharge capacity of commercially purchased lithium cobalt oxide sample 2 is 595 mAh / g. Figure 8 It can be seen that the discharge capacity of commercially purchased lithium cobalt oxide sample 1 is 170 mAh / g. Figure 9 It can be seen that the discharge capacity of the lithium cobalt oxide positive electrode material prepared in Comparative Example 1 is 574 mAh / g. Figure 10 It can be seen that the discharge capacity of the lithium cobalt oxide positive electrode material prepared in Comparative Example 2 is 397.5 mAh / g. Figure 11 As can be seen from the table, the discharge specific capacity of the lithium cobalt oxide positive electrode material prepared in Comparative Example 3 is 661 mAh / g. The specific capacities of the various examples and comparative examples are shown in Table 1.
[0136] Table 1 Specific capacity of each sample
[0137]
[0138]
[0139] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.
Claims
1. A method for preparing a lithium cobalt oxide positive electrode material, characterized in that: The following steps are involved: (1) Preparation of magnetic polishing powder, comprising: S1. Take iron nitrate and cerium nitrate, add to the graphene oxide dispersion, stir and mix evenly, and dry to obtain a mixture; ignite the mixture using a flame and burn it in air until the flame is extinguished to obtain a magnetic polishing powder precursor; S2. A magnetic polishing powder precursor was added to the starch dispersion, heated and stirred until completely solidified, and freeze-dried to obtain a dry mixture; the mixture was first calcined in an argon atmosphere and then calcined a second time in air to obtain a magnetic polishing powder; (2) ball milling high-rate lithium cobalt oxide and magnetic polishing powder for a period of time, and then removing the magnetic polishing powder using a magnet to obtain pretreated high-rate lithium cobalt oxide; (3) ball milling high-voltage lithium cobalt oxide and magnetic polishing powder for a period of time, and then removing the magnetic polishing powder using a magnet to obtain pretreated high-voltage lithium cobalt oxide; (4) The high-rate lithium cobalt oxide pretreated in step (2), the high-voltage lithium cobalt oxide pretreated in step (3), and carbon nanotubes are added to a ball mill, and a small amount of mixed solvent is added to obtain a solid-liquid mixture. After ball milling for a period of time, the mixture is dried to obtain a lithium cobalt oxide positive electrode material.
2. The method for preparing a lithium cobalt oxide positive electrode material according to claim 1, wherein: In the step (1), the mass ratio of ferric nitrate to cerium nitrate is 10:1 to 12:1, the concentration of the graphene oxide dispersion is 10 to 12 g / L, and the volume ratio of the total mass ratio of ferric nitrate and cerium nitrate to the graphene oxide dispersion is 12 g:0.8 to 1.2 L.
3. The method for preparing a lithium cobalt oxide positive electrode material according to claim 1, wherein: In the step (1), the concentration of the starch dispersion is 130-150 g / L, and the ratio of the magnetic polishing powder precursor to the starch dispersion is 1 g:8-12 mL.
4. The method for preparing a lithium cobalt oxide positive electrode material according to claim 1, wherein: In the step (1), the temperature of the first calcination is 800-1000° C., and the calcination time is 1-3 hours; the temperature of the second calcination is 200-300° C., and the calcination time is 4-6 hours.
5. The method for preparing a lithium cobalt oxide positive electrode material according to claim 1, wherein: In the step (2), the D50 of the high-rate lithium cobalt oxide is 5 to 8 μm, the mass ratio of the high-rate lithium cobalt oxide to the magnetic polishing powder is 25:3 to 50:3, the ball milling speed is 400 to 600 rpm, and the ball milling time is 60 to 90 min.
6. The method for preparing a lithium cobalt oxide positive electrode material according to claim 1, wherein: In the step (3), the D50 of the high-voltage lithium cobalt oxide is 12 to 20 μm, the mass ratio of the high-voltage lithium cobalt oxide to the magnetic polishing powder is 25:3 to 50:3, the ball milling speed is 400 to 600 rpm, and the ball milling time is 60 to 90 min.
7. The method for preparing a lithium cobalt oxide positive electrode material according to claim 1, wherein: In the step (4), the mass ratio of the pretreated high-rate lithium cobalt oxide to the pretreated high-voltage lithium cobalt oxide is 5:1 to 1:5, and the amount of carbon nanotubes used is 2.5 to 5% of the total mass of the pretreated high-rate lithium cobalt oxide and the pretreated high-voltage lithium cobalt oxide.
8. The method for preparing a lithium cobalt oxide positive electrode material according to claim 1, wherein: In the step (4), the mixed solvent is water and ethanol, the volume ratio of water to ethanol is 1:90 to 1:110, and the solid-liquid ratio in the solid-liquid mixture is 12.6 g: 5 to 10 mL.
9. The method for preparing a lithium cobalt oxide positive electrode material according to claim 1, wherein: In the step (4), the ball milling speed is 400-600 rpm, the ball milling time is 120-180 min, the drying temperature is 60° C.-80° C., and the drying time is 16-20 h.
10. A lithium cobalt oxide positive electrode material, characterized in that: The lithium cobalt oxide positive electrode material is prepared by the preparation method according to any one of claims 1 to 9.