A sheet-like porous cobalt chloride, single-crystal cobalt tetroxide, single-crystal lithium cobalt oxide, their preparation methods and applications

Abstract

This invention discloses a sheet-like porous cobalt chloride, a single-crystal cobalt tetroxide, a single-crystal lithium cobalt oxide, and their preparation methods and applications, belonging to the field of battery materials technology. The chemical formula of the sheet-like porous cobalt chloride is M. x Co 1‑x Cl2, 0≤x≤0.5, M is a metallic element other than cobalt; the tap density of this sheet-like porous cobalt chloride is not less than 1 g / cm³. 3 Specific surface area not less than 1.8m² 2 / g、D v10 Not less than 4.5μm, D v50 Not less than 8.5μm, D v90 The diameter is not less than 20 μm. This sheet-like porous cobalt chloride has a high tap density, a large specific surface area and pore volume, and a relatively uniform pore size, which is beneficial to increasing sintering activity. Moreover, when it is mixed with lithium source for calcination, its sheet-like porous structure is also conducive to the uniform diffusion of lithium ions into the bulk phase of the material, making the lithium ion distribution more uniform, which in turn helps to improve the electrochemical performance of the cathode material and the battery.

Description

Technical Field

[0001] This invention relates to the field of battery materials technology, and more specifically, to a sheet-like porous cobalt chloride, a single-crystal cobalt tetroxide, a single-crystal lithium cobalt oxide, and their preparation methods and applications. Background Technology

[0002] In recent years, with the continuous development of new energy battery materials, the types, morphology control, and structural control of precursor materials have become increasingly diverse. To meet the electrical performance requirements of different cathode materials, the synthesis requirements for precursor materials are also constantly changing, among which porous sheet-like precursors are highly sought after. However, porous sheet-like precursor materials are difficult to synthesize through co-precipitation. In most cases, existing technologies can only use template methods for synthesis, but this method has drawbacks such as complex processes, high costs, and difficulty in industrialization. Currently, there is no existing technology for sheet-like porous cobalt chloride.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The present invention aims to provide a sheet-like porous cobalt chloride, a single-crystal cobalt tetroxide, a single-crystal lithium cobalt oxide, and their preparation methods and applications, so as to solve or improve the above-mentioned technical problems.

[0005] This invention can be implemented as follows:

[0006] In a first aspect, the present invention provides a sheet-like porous cobalt chloride, the chemical formula of which is M x Co 1-x Cl2, 0≤x≤0.5, M is a metallic element other than cobalt;

[0007] Flaky porous cobalt chloride has at least one of the following characteristics:

[0008] Feature 1: The tap density of the sheet-like porous cobalt chloride is not less than 1 g / cm³. 3 ;

[0009] Feature 2: The specific surface area of ​​the plate-like porous cobalt chloride is not less than 1.8 m². 2 / g;

[0010] Feature 3: D of plate-like porous cobalt chloride v10 Not less than 4.5μm;

[0011] Feature 4: D of plate-like porous cobalt chloride v50 Not less than 8.5μm;

[0012] Feature 5: D of plate-like porous cobalt chloride v90 Not less than 20μm;

[0013] Feature 6: The pore volume of the sheet-like porous cobalt chloride is not less than 0.10 cm³.3 / g.

[0014] In an optional implementation, 0 ≤ x ≤ 0.04.

[0015] In an optional embodiment, M includes at least one of Al, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Sn, Zr, Mo, Nb, Y, W, In, and Ge.

[0016] Secondly, the present invention provides a method for preparing sheet-like porous cobalt chloride as described in the foregoing embodiments, comprising the following steps: spray drying a metal mixture matching M and Co in a preset chemical formula to obtain a precursor with a hollow structure; sintering the precursor to obtain sheet-like porous cobalt chloride.

[0017] In an optional embodiment, the metals in the metal mixture are all derived from chloride salts.

[0018] In an optional embodiment, the total concentration of metal salts in the metal mixture is 1 mol / L to 3 mol / L.

[0019] In an optional embodiment, the spray drying temperature is 150°C to 350°C.

[0020] In an optional embodiment, the spray drying temperature is 240°C to 260°C.

[0021] In an optional embodiment, the D of the dried material obtained after spray drying 50 The size ranges from 4μm to 25μm.

[0022] In an optional embodiment, the sintering temperature is 400℃~580℃ and the sintering time is 0.5h~12h.

[0023] In an optional embodiment, the sintering temperature is not lower than 500°C and not lower than 580°C, and the sintering time is 2h to 5h.

[0024] In an optional embodiment, the heating rate during sintering is 4°C / min to 6°C / min.

[0025] Thirdly, the present invention provides a single-crystal cobalt tetroxide, which is obtained by sintering the sheet-like porous cobalt chloride of the aforementioned embodiments at a temperature of not less than 580°C.

[0026] Fourthly, the present invention provides a single-crystal lithium cobalt oxide, wherein the raw materials for preparing the single-crystal lithium cobalt oxide include the sheet-like porous cobalt chloride of the aforementioned embodiments and / or the single-crystal cobalt tetroxide of the aforementioned embodiments.

[0027] Fifthly, the present invention provides a method for preparing single-crystal lithium cobalt oxide according to the foregoing embodiments, comprising the following steps: mixing a cobalt source and a lithium source and then calcining them; wherein the cobalt source includes the sheet-like porous cobalt chloride of the foregoing embodiments and / or the single-crystal cobalt tetroxide of the foregoing embodiments.

[0028] In an optional embodiment, the molar ratio of cobalt in the cobalt source to lithium in the lithium source is 1:1 to 1:1.05.

[0029] In an optional embodiment, the calcination temperature is 800℃~1100℃, and the calcination time is 4h~20h.

[0030] In an optional embodiment, the calcination temperature is 900°C to 950°C.

[0031] In a sixth aspect, the present invention provides a positive electrode sheet, wherein the active material in the positive electrode sheet includes the single-crystal lithium cobalt oxide of the aforementioned embodiments.

[0032] In a seventh aspect, the present invention provides a battery comprising the positive electrode sheet of the aforementioned embodiments.

[0033] The beneficial effects of this invention include:

[0034] This invention proposes for the first time a cobalt chloride with a sheet-like porous structure and its preparation method. The sheet-like porous cobalt chloride has a high tap density, a large specific surface area and pore volume, and a relatively uniform pore size, which is beneficial to increasing sintering activity. Furthermore, when mixed with a lithium source for calcination, its sheet-like porous structure is also conducive to the uniform diffusion of lithium ions into the bulk phase of the material, making the lithium ion distribution more uniform, thereby improving the electrochemical performance of the cathode material and the battery. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is an SEM image of the dried material obtained by spray drying in Example 1;

[0037] Figure 2 This is a SEM image of the sheet-like porous cobalt chloride obtained by sintering in Example 1;

[0038] Figure 3 The images show the XRD patterns of the material before and after sintering in Example 1.

[0039] Figure 4The image shows a SEM image of the lithium cobalt oxide cathode material prepared in Example 1.

[0040] Figure 5 The image shows the XRD pattern of the lithium cobalt oxide cathode material prepared in Example 1. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0042] The following provides a detailed description of the sheet-like porous cobalt chloride, single-crystal cobalt tetroxide, single-crystal lithium cobalt oxide, their preparation methods, and applications provided by the invention.

[0043] This invention proposes a sheet-like porous cobalt chloride, the chemical formula of which is M. x Co 1-x Cl2, 0≤x≤0.5, M is a metallic element other than cobalt.

[0044] In some alternative implementations, x can be 0, 0.1, 0.2, 0.3, 0.4, or 0.5, or other values ​​within the range of 0 to 0.5. In some implementations, 0 ≤ x ≤ 0.04, such as x can be 0, 0.01, 0.02, 0.03, or 0.04.

[0045] In some alternative embodiments, the sheet-like porous cobalt chloride may contain a small amount of water of crystallization. In some alternative embodiments, M may, by way of example but not limitation, include at least one of Al, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Sn, Zr, Mo, Nb, Y, W, In, and Ge.

[0046] In some embodiments, the tap density (TD) of the sheet-like porous cobalt chloride is not less than 1 g / cm³. 3 For example, it can be 1.14 g / cm³ 3 ~1.68g / cm 3 For example, it can be 1.14 g / cm³. 3 1.21 g / cm 3 1.22g / cm 3 1.29g / cm 3 1.35g / cm 3 Or 1.78g / cm 3 The value can also be 1.14 g / cm³. 3 ~1.68g / cm 3 Other values ​​within the range.

[0047] In some embodiments, the specific surface area (BET) of the sheet-like porous cobalt chloride is not less than 1.8 m². 2 / g, such as 1.95g / cm³ 3 ~3.45g / cm 3 For example, it can be 1.95 g / cm³. 3 2.10 g / cm 3 2.14 g / cm 3 2.44 g / cm 3 2.52g / cm 3 Or 3.45g / cm 3 The value can also be 1.95 g / cm³. 3 ~3.45g / cm 3 Other values ​​within the range.

[0048] In some embodiments, the D of sheet-like porous cobalt chloride v10 It should not be less than 4.5μm, but can be between 4.52μm and 12.13μm, for example, 4.52μm, 7.14μm, 8.40μm, 8.59μm, 10.58μm, 11.42μm or 12.13μm, or other values ​​within the range of 4.52μm to 12.13μm.

[0049] In some embodiments, the D of sheet-like porous cobalt chloride v50 It should not be less than 8.5 μm, but can be between 8.61 μm and 20.51 μm, for example, it can be 8.61 μm, 10.44 μm, 12.61 μm, 15.73 μm, 16.86 μm, 18.85 μm or 20.51 μm, or other values ​​within the range of 8.61 μm to 20.51 μm.

[0050] In some embodiments, the D of sheet-like porous cobalt chloride v90 Not less than 20μm, such as 22.34μm to 60.68μm, for example, 22.34μm, 40.48μm, 40.71μm, 55.72μm, 58.67μm, 60.59μm or 60.68μm, or other values ​​within the range of 22.34μm to 60.68μm.

[0051] In some embodiments, the pore volume of the sheet-like porous cobalt chloride is not less than 0.10 cm³. 3 / g, such as 0.16cm 3 / g~0.31cm 3 / g, for example, can be 0.16cm 3 / g, 0.2cm 3 / g, 0.24cm 3 / g, 0.26cm 3 / g, 0.28cm 3 / g or 0.31cm 3 / g, etc., can also be 0.16cm. 3 / g~0.31cm 3 Other values ​​within the / g range.

[0052] As mentioned above, the sheet-like porous cobalt chloride provided by this invention has a high tap density, a large specific surface area and pore volume, and a relatively uniform pore size, which is beneficial to increasing sintering activity. Furthermore, when mixed with a lithium source for calcination, the sheet-like porous structure also facilitates the uniform diffusion of lithium ions into the bulk phase of the material, making the lithium ion distribution more uniform, which in turn helps to improve the electrochemical performance of the cathode material and the battery.

[0053] Accordingly, the present invention also provides a method for preparing the above-mentioned sheet-like porous cobalt chloride, which may include the following steps: spray drying a metal mixture that matches M and Co in the chemical formula according to a preset chemical formula to obtain a precursor with a hollow structure; sintering the precursor to obtain sheet-like porous cobalt chloride.

[0054] In practical operation, the metal mixture can be prepared according to the preset molar ratio of M to Co in the chemical formula and the specific element used in M.

[0055] The metals in the above-mentioned metal mixtures all originate from chloride salts.

[0056] In some optional embodiments, the total concentration of metal salts in the metal mixture can be 1 mol / L to 3 mol / L, such as 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L or 3 mol / L, or other values ​​within the range of 1 mol / L to 3 mol / L.

[0057] In some optional embodiments, the spray drying temperature can be between 150°C and 350°C, such as 150°C, 180°C, 200°C, 220°C, 250°C, 280°C, 300°C, 320°C, or 350°C, or other values ​​within the range of 150°C to 350°C. In some more typical embodiments, the spray drying temperature is between 240°C and 260°C, such as 240°C, 245°C, 250°C, 255°C, or 260°C.

[0058] If the spray drying temperature is below 150℃, it is not conducive to the evaporation of moisture from the material; if the spray drying temperature is above 350℃, the spray energy consumption increases, the equipment capacity is limited, and a transition phase of a mixture of cobalt chloride and cobalt tetroxide will be obtained, with low purity.

[0059] D of the dried material obtained after spray drying 50 The value can be 4μm to 25μm, such as 4μm, 6μm, 10μm, 15μm, 20μm or 25μm, or other values ​​within the range of 4μm to 25μm.

[0060] As mentioned above, the dried material obtained by spray drying has advantages such as good consistency, high purity, few impurities, high crystallinity and low moisture content, and the dried material has a hollow structure.

[0061] In some alternative embodiments, the sintering temperature is 400℃~580℃ and the sintering time is 0.5h~12h.

[0062] The sintering temperature can be, for example, 400℃, 420℃, 450℃, 480℃, 500℃, 520℃, 550℃, 570℃, or 580℃, or other values ​​within the range of 400℃ to 580℃. In some typical embodiments, the sintering temperature is not lower than 500℃ and not lower than 580℃. At a sintering temperature of 580℃, the sintered material contains, in addition to flake-like porous cobalt chloride, a small amount of cobalt tetroxide. It should be emphasized that if the sintering temperature is too low, flake-like porous chloride will not be obtained. This is because, at too low a sintering temperature, the corresponding sintered material retains the spherical morphology after spraying and does not break down.

[0063] The sintering time can be, for example, 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, or 12h, or other values ​​within the range of 0.5h to 12h. In some typical embodiments, the sintering time is 2h to 5h.

[0064] In some optional embodiments, the heating rate during sintering can be 4℃ / min to 6℃ / min, such as 4℃ / min, 4.5℃ / min, 5℃ / min, 5.5℃ / min, or 6℃ / min, or other values ​​within the range of 4℃ / min to 6℃ / min. In some more typical embodiments, the heating rate during sintering is 5℃ / min.

[0065] If the heating rate is too high, the sintered material will agglomerate severely, affecting the flow of the material; if the heating rate is too low, the heating time will be slow and the efficiency will be low.

[0066] Continuing from the above, the metal mixture is first spray-dried to obtain a dried material with a hollow spherical structure. This dried material is then sintered under the aforementioned conditions. When the sintering temperature rises to a certain level, a pressure difference is generated inside and outside the hollow spherical structure, causing it to break and collapse, forming a porous sheet-like structure. The main reasons for this pressure difference include: as the temperature increases, the internal pressure of the hollow spherical structure increases, simultaneously generating gas that escapes outwards, ultimately causing the hollow spherical structure to collapse into a sheet-like structure.

[0067] The method for preparing sheet-like porous cobalt chloride provided by this invention is simple, has a short process, low production cost, is easy to industrialize, and can be mass-produced efficiently and quickly, making it economical and efficient.

[0068] In addition, the present invention provides a single-crystal cobalt tetroxide, which is obtained by sintering the above-mentioned sheet-like porous cobalt chloride at a temperature of not less than 580°C.

[0069] By sintering sheet-like porous cobalt chloride at the above temperature, the sheet-like porous cobalt chloride can be oxidized to produce cobalt tetroxide.

[0070] In other embodiments, the precursor with the hollow structure described above can be obtained directly by sintering at a temperature of not less than 580°C, and the heating rate of the sintering process can be 4°C / min to 6°C / min.

[0071] In addition, the present invention provides a single-crystal lithium cobalt oxide, the raw materials for preparing the single-crystal lithium cobalt oxide including the sheet-like porous cobalt chloride of the aforementioned embodiments and / or the single-crystal cobalt tetroxide of the aforementioned embodiments.

[0072] Accordingly, the present invention also provides a method for preparing the above-mentioned single-crystal lithium cobalt oxide, which may include the following steps: mixing a cobalt source and a lithium source and then calcining them; wherein the cobalt source includes the above-mentioned sheet-like porous cobalt chloride and / or the above-mentioned single-crystal cobalt tetroxide.

[0073] For example, in some embodiments, the cobalt source is only sheet-like porous cobalt chloride; in other embodiments, the cobalt source is only single-crystal cobalt tetroxide; and in still other embodiments, the cobalt source contains both sheet-like porous cobalt chloride and single-crystal cobalt tetroxide.

[0074] In some alternative implementations, the molar ratio of cobalt in the cobalt source to lithium in the lithium source can be from 1:1 to 1:1.05, such as 1:1, 1:1.01, 1:1.02, 1:1.03, 1:1.04 or 1:1.05, or other values ​​within the range of 1:1 to 1:1.05.

[0075] In some optional embodiments, the calcination temperature is 800℃ to 1100℃, such as 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, or 1100℃, or other values ​​within the range of 800℃ to 1100℃. In some more typical embodiments, the calcination temperature is 900℃ to 950℃.

[0076] In some optional embodiments, the calcination time is 4h to 20h, such as 4h, 8h, 12h, 16h or 20h, or other values ​​within the range of 4h to 20h.

[0077] By using sheet-like porous cobalt chloride in the cobalt source, the calcination activity can be improved during the calcination process, allowing lithium ions to diffuse more evenly into the bulk phase of the material, resulting in a more uniform distribution of lithium ions and thus obtaining a lithium cobalt oxide cathode material with uniform chemical element distribution.

[0078] In some implementations, the 0.2C discharge capacity of monocrystalline lithium cobalt oxide is not less than 172 mAh / g, such as 172.51 mAh / g to 181.02 mAh / g.

[0079] In some implementations, the 0.33C discharge capacity of monocrystalline lithium cobalt oxide is not less than 168 mAh / g, such as 168.06 mAh / g to 179.11 mAh / g.

[0080] In some implementations, the capacity retention of single-crystal lithium cobalt oxide after 200 cycles at 0.33C is not less than 83%, such as 83.06% to 89.56%.

[0081] In addition, the present invention also provides a positive electrode sheet in which the active material includes the above-mentioned single-crystal lithium cobalt oxide.

[0082] The present invention also provides a battery cell comprising the above-mentioned positive electrode sheet.

[0083] For example, the aforementioned battery cells can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft.

[0084] The present invention also provides a battery comprising the above-described battery cell. This battery can be a lithium-ion battery, a sodium-ion battery, or the like.

[0085] The present invention also provides an electrical device comprising the aforementioned battery cell and / or battery. As examples, the electrical device may include, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys may include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., while spacecraft may include airplanes, rockets, space shuttles, and spacecraft, etc.

[0086] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0087] Example 1

[0088] This embodiment provides a single-crystal lithium cobalt oxide, the preparation method of which includes:

[0089] S1: Preparation of sheet-like porous cobalt chloride.

[0090] S11: Prepare a 3 mol / L cobalt chloride metal solution.

[0091] S12: Spray dry the cobalt chloride molten metal at 260°C until the dried material reaches D... 50 It is 15μm.

[0092] The scanning electron microscope image of the dried material is as follows: Figure 1 As shown, by Figure 1 It can be seen that the spray-dried material has good sphericity and a hollow structure. The XRD pattern of the dried material is shown below. Figure 3 As shown.

[0093] S13: Take 2 kg of the above-mentioned dried material and put it into a sagger. Then, sinter it at high temperature in a box furnace at a heating rate of 5℃ / min. Heat it to 580℃ and hold it for 3 hours to finally obtain a sheet-like porous cobalt chloride material (chemical formula: CoCl2).

[0094] Scanning electron microscope image of the sintered product after sintering is shown below. Figure 2 As shown, the XRD pattern is as follows Figure 3 As shown. From Figure 3 It can be seen that the material obtained by spraying has good crystallinity and is cobalt chloride material; the sintered material is in the form of flakes, which is unoxidized cobalt chloride mixed with trace amounts of cobalt oxide. Because at 580℃, it is just close to the temperature node where cobalt chloride is oxidized to cobalt tetroxide, so a peak of trace cobalt tetroxide appears in the XRD.

[0095] S2: Preparation of single-crystal lithium cobalt oxide.

[0096] The above sintered product was mixed with lithium carbonate (the molar ratio of Co in the sintered product to Li in the lithium carbonate was 1:1.05) to obtain a mixture; the mixture was calcined at 900℃ for 6 hours to obtain a single-crystal lithium cobalt oxide cathode material.

[0097] SEM image of the lithium cobalt oxide cathode material is as follows: Figure 4 As shown, the XRD pattern of this lithium cobalt oxide cathode material is as follows: Figure 5 As shown.

[0098] Example 2

[0099] This embodiment provides a single-crystal lithium cobalt oxide, the preparation method of which includes:

[0100] S1: Preparation of sheet-like porous cobalt chloride.

[0101] S11: Prepare a metal mixture with a total metal concentration of 3 mol / L. The metal elements in the metal mixture are Al and Co, with a molar ratio of Al to Co of 2:98. Al is provided by aluminum chloride and Co is provided by cobalt chloride.

[0102] S12: Spray dry the cobalt chloride molten metal at 260°C until the dried material reaches D... 50 It is 20μm.

[0103] S13: Take 2 kg of the above-mentioned dried material and place it in a crucible. Perform high-temperature sintering in a box furnace at a heating rate of 5℃ / min, raising the temperature to 520℃ and holding for 3 hours to finally obtain a sheet-like porous cobalt chloride material (chemical formula: Al). 0.02 Co 0.98 Cl2).

[0104] S2: Preparation of single-crystal lithium cobalt oxide.

[0105] The above sintered product was mixed with lithium carbonate (the molar ratio of Co in the sintered product to Li in the lithium carbonate was 1:1.05) to obtain a mixture; the mixture was calcined at 910℃ for 6 hours to obtain a single-crystal lithium cobalt oxide cathode material.

[0106] Example 3

[0107] This embodiment provides a single-crystal lithium cobalt oxide, the preparation method of which includes:

[0108] S1: Preparation of sheet-like porous cobalt chloride.

[0109] S11: Prepare a metal mixture with a total metal concentration of 2.5 mol / L. The metal elements in the metal mixture are Ni and Co. The molar ratio of Ni to Co in the metal mixture is 4:96. Ni is provided by nickel chloride and Co is provided by cobalt chloride.

[0110] S12: Spray dry the cobalt chloride molten metal at 250°C until the dried material reaches D... 50 It is 10μm.

[0111] S13: Take 2 kg of the above-mentioned dried material and place it in a crucible. Perform high-temperature sintering in a box furnace at a heating rate of 5℃ / min, raising the temperature to 550℃ and holding for 3 hours to finally obtain a sheet-like porous cobalt chloride material (chemical formula: Ni). 0.04 Co 0.96 Cl2).

[0112] S2: Preparation of single-crystal lithium cobalt oxide.

[0113] The above sintered product was mixed with lithium carbonate (the molar ratio of Co in the sintered product to Li in the lithium carbonate was 1:1.05) to obtain a mixture; the mixture was calcined at 900℃ for 6 hours to obtain a single-crystal lithium cobalt oxide cathode material.

[0114] Example 4

[0115] This embodiment provides a single-crystal lithium cobalt oxide, the preparation method of which includes:

[0116] S1: Preparation of sheet-like porous cobalt chloride.

[0117] S11: Prepare a metal mixture with a total metal concentration of 2.5 mol / L. The metal elements in the metal mixture are Ni, Mn and Co. The molar ratio of Ni, Mn and Co in the metal mixture is 4:4:92. Ni is provided by nickel chloride, Mn is provided by manganese chloride and Co is provided by cobalt chloride.

[0118] S12: Spray dry the cobalt chloride molten metal at 240℃ until the dried material reaches D... 50 It is 12μm.

[0119] S13: Take 2 kg of the above-mentioned dried material and place it in a crucible. Perform high-temperature sintering in a box furnace at a heating rate of 5℃ / min, raising the temperature to 500℃ and holding for 2 hours to finally obtain a sheet-like porous cobalt chloride material (chemical formula: Ni). 0.04 Mn 0.04 Co 0.92 Cl2).

[0120] S2: Preparation of single-crystal lithium cobalt oxide.

[0121] The above sintered product was mixed with lithium carbonate (the molar ratio of Co in the sintered product to Li in the lithium carbonate was 1:1.05) to obtain a mixture; the mixture was calcined at 930°C for 6 hours to obtain a single-crystal lithium cobalt oxide cathode material.

[0122] Example 5

[0123] This embodiment provides a single-crystal lithium cobalt oxide, the preparation method of which includes:

[0124] S1: Preparation of sheet-like porous cobalt chloride.

[0125] S11: Prepare a metal mixture with a total metal concentration of 2.2 mol / L. The metal elements in the metal mixture are Ni, Mn, Co and Mg. The molar ratio of Ni, Mn, Co and Mg in the metal mixture is 4:4:90:2. Ni is provided by nickel chloride, Mn is provided by manganese chloride, Co is provided by cobalt chloride and Mg is provided by magnesium chloride.

[0126] S12: Spray dry the cobalt chloride molten metal at 240℃ until the dried material reaches D... 50 It is 20μm.

[0127] S13: Take 2 kg of the above-mentioned dried material and place it in a crucible. Perform high-temperature sintering in a box furnace at a heating rate of 5℃ / min, raising the temperature to 500℃ and holding for 5 hours to finally obtain a sheet-like porous cobalt chloride material (chemical formula: Ni). 0.04 Mn 0.04 Co 0.90 Mg 0.02 Cl2).

[0128] S2: Preparation of single-crystal lithium cobalt oxide.

[0129] The above sintered product was mixed with lithium carbonate (the molar ratio of Co in the sintered product to Li in the lithium carbonate was 1:1.05) to obtain a mixture; the mixture was calcined at 950°C for 6 hours to obtain a single-crystal lithium cobalt oxide cathode material.

[0130] Example 6

[0131] This embodiment provides a single-crystal lithium cobalt oxide, the preparation method of which includes:

[0132] S1: Preparation of sheet-like porous cobalt chloride.

[0133] S11: Prepare a 2 mol / L cobalt chloride metal solution.

[0134] S12: Spray dry the cobalt chloride molten metal at 240℃ until the dried material reaches D... 50 It is 10μm.

[0135] S13: Take 2 kg of the above-mentioned dried material and put it into a sagger. Then, sinter it at high temperature in a box furnace at a heating rate of 4℃ / min. Heat it to 560℃ and hold it for 5 hours to finally obtain a sheet-like porous cobalt chloride material (chemical formula: CoCl2).

[0136] S2: Preparation of single-crystal lithium cobalt oxide.

[0137] The above sintered product was mixed with lithium carbonate (the molar ratio of Co in the sintered product to Li in the lithium carbonate was 1:1 to obtain a mixture); the mixture was calcined at 800℃ for 20h to obtain a single-crystal lithium cobalt oxide cathode material.

[0138] Example 7

[0139] This embodiment provides a single-crystal lithium cobalt oxide, the preparation method of which includes:

[0140] S1: Preparation of sheet-like porous cobalt chloride.

[0141] S11: Prepare a 2.5 mol / L cobalt chloride metal solution.

[0142] S12: Spray dry the cobalt chloride molten metal at 250°C until the dried material reaches D... 50 It is 20μm.

[0143] S13: Take 2 kg of the above-mentioned dried material and put it into a sagger. Then, sinter it at high temperature in a box furnace at a heating rate of 6℃ / min. Heat it to 580℃ and hold it for 0.5 h to finally obtain a sheet-like porous cobalt chloride material (chemical formula: CoCl2).

[0144] S2: Preparation of single-crystal lithium cobalt oxide.

[0145] The above sintered product was mixed with lithium carbonate (the molar ratio of Co in the sintered product to Li in the lithium carbonate was 1:1.02) to obtain a mixture; the mixture was calcined at 1100℃ for 4 hours to obtain a single-crystal lithium cobalt oxide cathode material.

[0146] Comparative Example 1

[0147] The difference between this comparative example and Example 1 is that the spray drying temperature is 120°C.

[0148] Comparative Example 2

[0149] The difference between this comparative example and Example 1 is that the spray drying temperature is 400°C.

[0150] Comparative Example 3

[0151] The difference between this comparative example and Example 1 is that the sintering temperature is 350°C.

[0152] Comparative Example 4

[0153] The difference between this comparative example and Example 1 is that the heating rate during sintering is 10°C / min.

[0154] Comparative Example 5

[0155] The difference between this comparative example and Example 1 is that ordinary cobalt chloride powder (particle size of 15 μm) is used instead of flaky porous cobalt chloride.

[0156] Experimental Example 1

[0157] The tap density, specific surface area, particle size distribution, and pore volume of the sheet-like porous cobalt chloride obtained in step S1 of Examples 1 to 7 and the material obtained in step S1 of Comparative Example 3 were tested, and the results are shown in Table 1.

[0158] Table 1 Test Results

[0159] <![CDATA[TD(g / cm 3 )]]> <![CDATA[BET(m 2 / g)]]> <![CDATA[D V10 (μm)]]> <![CDATA[D V50 (μm)]]> <![CDATA[D V90 (μm)]]> <![CDATA[Pore volume (cm 3 / g)]]> Example 1 1.21 2.10 7.14 12.61 40.48 0.20 Example 2 1.14 1.95 8.59 15.73 60.59 0.16 Example 3 1.22 2.14 4.52 8.61 22.34 0.24 Example 4 1.35 2.52 8.40 10.44 40.71 0.28 Example 5 1.29 2.44 11.42 18.85 60.68 0.26 Example 6 1.35 3.45 10.58 16.86 55.72 0.31 Example 7 1.68 2.87 12.13 20.51 58.67 0.28 Comparative Example 3 2.21 0.82 12.48 15.29 40.25 0.08

[0160] Experimental Example 2

[0161] The lithium cobalt oxide prepared in steps S2 of Examples 1-7 and Comparative Examples 1-5 can be used as positive electrode materials to assemble full cells. The above positive electrode material, along with the conductive agent Super P and the binder polyvinylidene fluoride (PVDF), is dispersed in NMP solvent at a mass ratio of 96:2:2 and stirred until homogeneous to obtain an electrode slurry. The electrode slurry is coated onto an aluminum foil surface, vacuum baked at 120°C for 12 hours, rolled, and cut to obtain a positive electrode sheet. A graphite negative electrode is then used, along with a 1 mol / L LiPF6 / (EC+DEC+DMC) electrolyte (volume ratio 1:1:1) and a PP / PE / PP three-layer separator to fabricate a pouch cell. Charge-discharge tests were conducted at 25°C under conditions of 4.48V / 0.2C and 0.33C, and the results are shown in Table 2.

[0162] Table 2 Test Results

[0163]

[0164]

[0165] As can be seen from Table 2, the battery prepared by the lithium cobalt oxide cathode material provided in the embodiments of the present invention has better discharge capacity and capacity retention rate than the battery prepared by the lithium cobalt oxide cathode material provided in the comparative example.

[0166] In summary, the sheet-like porous cobalt chloride provided by this invention has a high tap density, a large specific surface area and porosity, and relatively uniform pore size, which is beneficial to increasing sintering activity. Furthermore, when mixed with a lithium source for calcination, its sheet-like porous structure is also conducive to the uniform diffusion of lithium ions into the bulk phase of the material, making the lithium ion distribution more uniform, which in turn helps to improve the electrochemical performance of the cathode material and the battery.

[0167] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A sheet-like porous cobalt chloride, characterized in that, The chemical formula of the sheet-like porous cobalt chloride is M. x Co 1-x Cl2, 0 < x ≤ 0.5, M is a metallic element other than cobalt; The sheet-like porous cobalt chloride has at least one of the following characteristics: Feature 1: The tap density of the sheet-like porous cobalt chloride is not less than 1 g / cm³. 3 ; Feature 2: The specific surface area of ​​the sheet-like porous cobalt chloride is not less than 1.8 m². 2 / g; Feature 3: The D of the sheet-like porous cobalt chloride v10 Not less than 4.5μm; Feature 4: The D of the sheet-like porous cobalt chloride v50 Not less than 8.5μm; Feature 5: The D of the sheet-like porous cobalt chloride v90 Not less than 20μm; Feature 6: The pore volume of the sheet-like porous cobalt chloride is not less than 0.10 cm³. 3 / g.

2. The sheet-like porous cobalt chloride according to claim 1, characterized in that, 0＜x≤0.04。 3. The sheet-like porous cobalt chloride according to claim 1 or 2, characterized in that, M includes at least one of Al, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Sn, Zr, Mo, Nb, Y, W, In, and Ge.

4. A method for preparing sheet-like porous cobalt chloride as described in any one of claims 1 to 3, characterized in that, Includes the following steps: According to the preset chemical formula, the metal mixture that matches M and Co in the chemical formula is spray-dried to obtain a precursor with a hollow structure. The precursor is sintered to obtain the sheet-like porous cobalt chloride.

5. The preparation method according to claim 4, characterized in that, The metals in the metal mixture are all derived from chloride salts.

6. The preparation method according to claim 5, characterized in that, The total concentration of metal salts in the metal mixture is 1 mol / L to 3 mol / L.

7. The preparation method according to claim 4, characterized in that, The spray drying temperature is 150℃~350℃.

8. The preparation method according to claim 7, characterized in that, The spray drying temperature is 240℃~260℃.

9. The preparation method according to claim 4, characterized in that, D of the dried material obtained after spray drying 50 The size ranges from 4μm to 25μm.

10. The preparation method according to claim 4, characterized in that, The sintering temperature is 400℃~580℃, and the sintering time is 0.5h~12h.

11. The preparation method according to claim 10, characterized in that, The sintering temperature is not lower than 500℃ and not lower than 580℃, and the sintering time is 2h~5h.

12. The preparation method according to claim 10, characterized in that, The heating rate during sintering is 4℃ / min to 6℃ / min.

13. A single-crystal cobalt tetroxide, characterized in that, The single-crystal cobalt tetroxide is obtained by sintering the sheet-like porous cobalt chloride as described in any one of claims 1 to 3 at a temperature not lower than 580°C.

14. A single-crystal lithium cobalt oxide, characterized in that, The raw materials for preparing the monocrystalline lithium cobalt oxide include the sheet-like porous cobalt chloride as described in any one of claims 1 to 3 and / or the monocrystalline cobalt tetroxide as described in claim 13.

15. A method for preparing single-crystal lithium cobalt oxide as described in claim 14, characterized in that, The method includes the following steps: calcining a mixture of a cobalt source and a lithium source; wherein the cobalt source includes the sheet-like porous cobalt chloride as described in any one of claims 1 to 3 and / or the single-crystal cobalt tetroxide as described in claim 13.

16. The preparation method according to claim 15, characterized in that, The molar ratio of cobalt in the cobalt source to lithium in the lithium source is from 1:1 to 1:1.

05.

17. The preparation method according to claim 15, characterized in that, The calcination temperature is 800℃~1100℃, and the calcination time is 4h~20h.

18. The preparation method according to claim 17, characterized in that, The calcination temperature is 900℃~950℃.

19. A positive electrode plate, characterized in that, The active material in the positive electrode includes the single-crystal lithium cobalt oxide as described in claim 14.

20. A battery, characterized in that, The battery contains the positive electrode sheet as described in claim 19.

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