Preparation method of lithium vanadium phosphate cathode material with high tap density

Abstract

The present invention relates to the field of chemical engineering technology, and specifically relates to a preparation method of a lithium vanadium phosphate cathode material with high tap density. The method comprises the following steps: taking a quantitative amount of ammonium metavanadate and placing it in deionized water, adding ammonia water with a concentration of 25-35%, and then stirring to obtain a light yellow transparent solution; drying the obtained light yellow transparent solution to obtain a vanadium-containing powder; performing heat treatment on the vanadium-containing powder to obtain vanadium pentoxide particles; mixing the above vanadium pentoxide with lithium carbonate, ammonium dihydrogen phosphate, and sucrose, and ball milling for 10-15 h to obtain a precursor; wherein, the molar ratio of vanadium pentoxide, lithium carbonate, ammonium dihydrogen phosphate, and sucrose is: 2:(3.0-3.05):3:(0.66-0.83); roasting the above precursor in a roasting furnace, and after the roasting is completed, cooling it to room temperature with the furnace, taking out the roasted material and grinding it into powder to obtain the lithium vanadium phosphate material with high tap density.

Description

Technical Field

[0001] The present invention relates to the field of chemical engineering technology, and particularly to a preparation method of a lithium vanadium phosphate cathode material with high tap density. Background Art

[0002] Lithium-ion batteries have a series of advantages such as high voltage, high unit energy, long cycle life, and low self-discharge rate. Since Sony successfully achieved commercial production in 1990, lithium-ion batteries have been widely used in various portable electronic products. Moreover, lithium-ion batteries also have great application prospects as power sources for electric vehicles (EVs) and hybrid electric vehicles (HEVs). However, electric vehicle batteries and energy storage batteries, which have received high attention for solving energy and environmental problems, have put forward higher requirements for current lithium-ion batteries, which also pose higher requirements for the anode and cathode materials that restrict the performance and cost of lithium-ion batteries. The lithium vanadium phosphate cathode material not only has advantages such as good cycling performance, safety and stability, and a wide applicable temperature range, but also has a very high voltage platform and electrochemical capacity (3.0 - 4.3V, theoretical capacity 133mAh / g; 3.0 - 4.8V, theoretical capacity up to 197mAh / g), and is a new generation of lithium-ion battery cathode material with great potential. At present, there is an obvious drawback of the lithium vanadium phosphate cathode material, that is, the tap density is relatively low. The tap density of lithium vanadium phosphate is generally about 1.0g / cm3, and for the carbon-coated lithium vanadium phosphate, its tap density is even lower, generally around 0.8g / cm3. This seriously restricts the further development of lithium vanadium phosphate. At present, there are many methods for preparing Li3V2(PO4)3, and different preparation methods have a great influence on the tap density of Li3V2(PO4)3. Irregular powder particles cannot be closely packed. If the synthesized Li3V2(PO4)3 powder particles have an irregular morphology, it will cause the tap density of the product to be very low. Summary of the Invention

[0003] In order to solve the technical problems existing in the above-mentioned prior art, the present invention provides a preparation method of a lithium vanadium phosphate cathode material with high tap density.

[0004] To achieve the above object, the embodiments of the present invention provide the following technical solutions:

[0005] In a first aspect, in an embodiment provided by the present invention, a preparation method of a lithium vanadium phosphate cathode material with high tap density is provided, and the method includes the following steps:

[0006] Take a quantitative amount of ammonium metavanadate (APV) and place it in deionized water, add ammonia water with a concentration of 25 - 35%, and then stir to obtain a light yellow transparent solution;

[0007] Dry the obtained light yellow transparent solution to obtain a vanadium-containing powder;

[0008] The vanadium-containing powder is heat-treated to obtain vanadium pentoxide particles;

[0009] The above-mentioned vanadium pentoxide is mixed with lithium carbonate, ammonium dihydrogen phosphate, and sucrose, and ball-milled for 10-15 h to obtain a precursor; wherein, the molar ratio of vanadium pentoxide, lithium carbonate, ammonium dihydrogen phosphate, and sucrose is: 2:(3.0-3.05):3:(0.66-0.83);

[0010] The above-mentioned precursor is calcined in a roasting furnace, and after the calcination is completed, it is cooled to room temperature with the furnace, and the calcined material is taken out and ground into powder to obtain lithium vanadium phosphate material with high tap density.

[0011] As a further scheme of the present invention, a quantitative amount of ammonium metavanadate is placed in deionized water, ammonia water with a concentration of 25-35% is added, and then stirred to obtain a light yellow transparent solution, including:

[0012] A quantitative amount of ammonium metavanadate is placed in deionized water, ammonia water with a concentration of 25-35% is added, and then stirred for 20-30 minutes to obtain a light yellow transparent solution.

[0013] As a further scheme of the present invention, a quantitative amount of ammonium metavanadate is placed in deionized water, ammonia water with a concentration of 25-35% is added, and then stirred to obtain a light yellow transparent solution, including:

[0014] The addition amount of ammonia water is calculated according to the molar ratio NH3 / V = 1.3-1.5, and the dissolution reaction needs to be carried out under the condition of a water bath at 65-85 °C.

[0015] As a further scheme of the present invention, the obtained light yellow transparent solution is dried to obtain a vanadium-containing powder; including:

[0016] The light yellow transparent solution is dried with a spray dryer.

[0017] As a further scheme of the present invention, the feeding speed of the spray dryer is 200-300 mL / h, and the air inlet temperature is controlled at 150-200 °C.

[0018] As a further scheme of the present invention, the vanadium-containing powder is heat-treated to obtain vanadium pentoxide particles, including:

[0019] The vanadium-containing powder is heat-treated with a muffle furnace, and the heat treatment is carried out in an air or oxygen atmosphere.

[0020] As a further scheme of the present invention, the heat treatment temperature is 550 °C-600 °C, and the holding time is 4-6 h.

[0021] As a further scheme of the present invention, the roasting furnace is a vacuum tube furnace.

[0022] As a further aspect of the present invention, the precursor is calcined in a calcination furnace, including:

[0023] Under an argon atmosphere, calcine at 350 - 400 °C for 3 - 5 h, then raise the temperature to 750 - 800 °C and calcine for 8 - 10 h. After the calcination is completed, cool it to room temperature with the furnace.

[0024] As a further aspect of the present invention, the above-mentioned precursor is calcined in a calcination furnace, and after the calcination is completed, it is cooled to room temperature with the furnace, and then the calcined material is taken out and ground into powder to obtain a lithium vanadium phosphate material with a high tap density, including:

[0025] The powder is passed through a 110 - 130 mesh sieve to obtain a lithium vanadium phosphate material with a high tap density.

[0026] The technical solution provided by the present invention has the following beneficial effects: Ammonium metavanadate (APV) is used as the vanadium source, and spherical vanadium pentoxide particles are obtained through reverse dissolution with ammonia - spray drying granulation - calcination treatment. After mixing it with lithium carbonate, ammonium dihydrogen phosphate, and sucrose and then calcining, a lithium vanadium phosphate material with a relatively high tap density is obtained. The present invention adopts a method of pretreating the vanadium source and prepares lithium vanadium phosphate particles with a high tap density and good electrochemical performance through solid - phase sintering. The preparation process of the present invention is simple, the condition control is convenient, the production cost is low, and it is suitable for industrial application.

[0027] These aspects or other aspects of the present invention will be more clearly understood in the following description of the embodiments. It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present invention. Brief Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other embodiments can be obtained based on these drawings without creative efforts.

[0029] Figure 1 It is a comparison chart of the first - cycle charge - discharge performance of lithium vanadium phosphate prepared in Example 6 (L - 1) and Comparative Example 1 (D - 1) of the present invention. Detailed Embodiments

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] The flowcharts shown in the accompanying drawings are only illustrative examples, and do not necessarily include all contents and operations / steps, nor do they necessarily need to be executed in the described order. For example, some operations / steps can be decomposed, combined or partially merged, so the actual execution order may change according to the actual situation.

[0032] The present invention provides a preparation method for a lithium vanadium phosphate cathode material with high tap density. The preparation method for the lithium vanadium phosphate cathode material with high tap density includes the following steps:

[0033] Step S1: Take a quantitative amount of ammonium polyvanadate (APV) and place it in deionized water. Add ammonia water with a concentration of 25-35%, and then stir to obtain a light yellow transparent solution.

[0034] The above step S1: Take a quantitative amount of ammonium polyvanadate and place it in deionized water. Add ammonia water with a concentration of 25-35%, and then stir to obtain a light yellow transparent solution, includes:

[0035] Take a quantitative amount of ammonium polyvanadate and place it in deionized water. Add ammonia water with a concentration of 25-35%, and then stir for 20-30 minutes to obtain a light yellow transparent solution.

[0036] In the embodiment of the present invention, the above step S1: Take a quantitative amount of ammonium polyvanadate and place it in deionized water. Add ammonia water with a concentration of 25-35%, and then stir to obtain a light yellow transparent solution, includes:

[0037] The addition amount of ammonia water is calculated according to the molar ratio NH3 / V = 1.3-1.5, and the dissolution reaction needs to be carried out under the condition of a water bath at 65-85°C.

[0038] Step S2: Dry the obtained light yellow transparent solution to obtain a vanadium-containing powder.

[0039] It should be noted that the obtained vanadium-containing powder is spherical.

[0040] In the embodiment of the present invention, the above drying the obtained light yellow transparent solution to obtain a vanadium-containing powder; includes:

[0041] Dry the light yellow transparent solution with a spray dryer.

[0042] In the embodiment of the present invention, the feeding speed of the spray dryer is 200 - 300 mL / h, and the air inlet temperature is controlled at 150 - 200 °C.

[0043] Step S3: Heat-treat the vanadium-containing powder to obtain vanadium pentoxide particles.

[0044] The vanadium pentoxide particles are spherical.

[0045] In the embodiment of the present invention, Step S3: Heat-treat the vanadium-containing powder to obtain vanadium pentoxide particles, including:

[0046] Heat-treat the vanadium-containing powder using a muffle furnace, and perform the heat treatment in an air or oxygen atmosphere.

[0047] In the embodiment of the present invention, the heat treatment temperature is 550 °C - 600 °C, and the heat preservation time is 4 - 6 h.

[0048] Step S4: Mix the above-mentioned vanadium pentoxide with lithium carbonate, ammonium dihydrogen phosphate, and sucrose, and ball mill for 10 - 15 h to obtain a precursor; wherein, the molar ratio of vanadium pentoxide, lithium carbonate, ammonium dihydrogen phosphate, and sucrose is: 2:(3.0 - 3.05):3:(0.66 - 0.83).

[0049] Step S5: Roast the above-mentioned precursor in a roasting furnace, and after the roasting is completed, cool it to room temperature with the furnace, take out the roasted material and grind it into powder to obtain the lithium vanadium phosphate material with high tap density.

[0050] In the embodiment of the present invention, the roasting furnace can be a vacuum tube furnace.

[0051] In the embodiment of the present invention, the precursor is roasted in an argon atmosphere.

[0052] In the embodiment of the present invention, roasting the precursor in a roasting furnace includes:

[0053] In an argon atmosphere, roast at 350 - 400 °C for 3 - 5 h, then raise the temperature to 750 - 800 °C and roast for 8 - 10 h. After the roasting is completed, cool it to room temperature with the furnace.

[0054] Step S5 further includes passing the powder through a 110 - 130 mesh sieve to obtain the lithium vanadium phosphate material with high tap density.

[0055] The present invention uses ammonium metavanadate (APV) as the vanadium source. Through the processes of back dissolution with ammonia water, granulation by a spray dryer, and calcination, spherical vanadium pentoxide particles are obtained. After mixing them with lithium carbonate, ammonium dihydrogen phosphate, and sucrose and then roasting, a lithium vanadium phosphate material with a relatively high tapped density is obtained. The present invention adopts a method of pretreating the vanadium source and prepares lithium vanadium phosphate particles with a relatively high tapped density and good electrochemical performance through solid-phase sintering. The preparation process is simple, the condition control is convenient, the production cost is low, and it is suitable for industrial application.

[0056] Example 1

[0057] A preparation method of a lithium vanadium phosphate cathode material with a high tapped density includes the following steps:

[0058] Step S1: Take a quantitative amount of ammonium metavanadate (APV) and place it in deionized water. Add ammonia water with a concentration of 35%, and then stir to obtain a light yellow transparent solution.

[0059] The step S1: Take a quantitative amount of ammonium metavanadate and place it in deionized water. Add ammonia water with a concentration of 35%, and then stir to obtain a light yellow transparent solution, includes:

[0060] Take a quantitative amount of ammonium metavanadate and place it in deionized water. Add ammonia water with a concentration of 35%, and then stir for 20 - 30 minutes to obtain a light yellow transparent solution.

[0061] The step S1: Take a quantitative amount of ammonium metavanadate and place it in deionized water. Add ammonia water with a concentration of 35%, and then stir to obtain a light yellow transparent solution, includes:

[0062] The addition amount of ammonia water is calculated according to the molar ratio NH3 / V = 1.5, and the dissolution reaction needs to be carried out under the condition of a water bath at 75°C.

[0063] Step S2: Dry the obtained light yellow transparent solution to obtain a vanadium-containing powder.

[0064] It should be noted that the obtained vanadium-containing powder is spherical.

[0065] In the embodiment of the present invention, the drying of the obtained light yellow transparent solution to obtain a vanadium-containing powder includes:

[0066] Dry the light yellow transparent solution with a spray dryer.

[0067] In the embodiment of the present invention, the feeding speed of the spray dryer is 300 mL / h, and the air inlet temperature is controlled at 200°C.

[0068] Step S3: Heat-treat the vanadium-containing powder to obtain vanadium pentoxide particles.

[0069] The vanadium pentoxide particles are spherical.

[0070] In an embodiment of the present invention, step S3 of heat-treating the vanadium-containing powder to obtain vanadium pentoxide particles includes:

[0071] The vanadium-containing powder is heat-treated using a muffle furnace and heat-treated in an air or oxygen atmosphere.

[0072] In an embodiment of the present invention, the heat treatment temperature is 600 °C and the heat preservation time is 6 h.

[0073] Step S4: Mix the above-mentioned vanadium pentoxide with lithium carbonate, ammonium dihydrogen phosphate, and sucrose, and ball mill for 15 h to obtain a precursor; the molar ratio of vanadium pentoxide, lithium carbonate, ammonium dihydrogen phosphate, and sucrose is: 2:3.05:3:0.83.

[0074] Step S5: Roast the above-mentioned precursor in a roasting furnace, and after roasting is completed, cool it to room temperature with the furnace, take out the roasted material and grind it into powder to obtain a lithium vanadium phosphate material with high tap density.

[0075] In an embodiment of the present invention, the roasting furnace can be a vacuum tube furnace.

[0076] In an embodiment of the present invention, the precursor is roasted in an argon atmosphere.

[0077] In an embodiment of the present invention, roasting the precursor in a roasting furnace includes:

[0078] In an argon atmosphere, roast at 400 °C for 5 h, then raise the temperature to 800 °C and roast for 10 h. After roasting is completed, cool it to room temperature with the furnace.

[0079] Step S5 further includes passing the powder through a 130-mesh sieve to obtain a lithium vanadium phosphate material with high tap density.

[0080] Example 2

[0081] A method for preparing a lithium vanadium phosphate cathode material with high tap density includes the following steps:

[0082] Step S1: Take a quantitative amount of ammonium polyvanadate (APV) and place it in deionized water, add ammonia water with a concentration of 25%, and then stir to obtain a light yellow transparent solution.

[0083] Step S1 of taking a quantitative amount of ammonium polyvanadate and placing it in deionized water, adding ammonia water with a concentration of 25%, and then stirring to obtain a light yellow transparent solution includes:

[0084] Take a quantitative amount of ammonium polyvanadate and place it in deionized water, add ammonia water with a concentration of 25%, and then stir for 20 - 30 minutes to obtain a light yellow transparent solution.

[0085] Step S1: Weigh a certain amount of ammonium metavanadate and place it in deionized water. Add ammonia water with a concentration of 25%, and then stir to obtain a pale yellow transparent solution, including:

[0086] The addition amount of ammonia water is calculated according to the molar ratio NH3 / V = 1.3, and the dissolution reaction needs to be carried out under the condition of a water bath at 65°C.

[0087] Step S2: Dry the obtained pale yellow transparent solution to obtain a vanadium-containing powder.

[0088] It should be noted that the obtained vanadium-containing powder is spherical.

[0089] In the embodiment of the present invention, drying the obtained pale yellow transparent solution to obtain a vanadium-containing powder includes:

[0090] Dry the pale yellow transparent solution with a spray dryer.

[0091] In the embodiment of the present invention, the feeding speed of the spray dryer is 200 mL / h, and the air inlet temperature is controlled at 150°C.

[0092] Step S3: Heat-treat the vanadium-containing powder to obtain vanadium pentoxide particles.

[0093] The vanadium pentoxide particles are spherical.

[0094] In the embodiment of the present invention, step S3: heat-treat the vanadium-containing powder to obtain vanadium pentoxide particles, including:

[0095] Heat-treat the vanadium-containing powder with a muffle furnace, and carry out the heat treatment in an air or oxygen atmosphere.

[0096] In the embodiment of the present invention, the heat treatment temperature is 550°C, and the holding time is 4 h.

[0097] Step S4: Mix the above vanadium pentoxide with lithium carbonate, ammonium dihydrogen phosphate, and sucrose, and ball mill for 10 - 15 h to obtain a precursor; the molar ratio of vanadium pentoxide, lithium carbonate, ammonium dihydrogen phosphate, and sucrose is: 2:3.0:3:0.66.

[0098] Step S5: Roast the above precursor in a roasting furnace, and after the roasting is completed, cool it to room temperature with the furnace, take out the roasted material and grind it into powder to obtain a lithium vanadium phosphate material with a high tap density.

[0099] In the embodiment of the present invention, the roasting furnace can be a vacuum tube furnace.

[0100] In the embodiment of the present invention, the precursor is roasted in an argon atmosphere.

[0101] In the embodiment of the present invention, the roasting in the precursor roasting furnace includes:

[0102] Roast at 350 °C for 3 h in an argon atmosphere, then raise the temperature to 750 °C and roast for 8 h. After roasting, cool to room temperature with the furnace.

[0103] Step S5 further includes passing the powder through a 110-mesh sieve to obtain lithium vanadium phosphate with a high tap density.

[0104] Example 3

[0105] A preparation method of a lithium vanadium phosphate cathode material with a high tap density includes the following steps:

[0106] Step S1: Take a certain amount of ammonium metavanadate (APV) and place it in deionized water, add ammonia water with a concentration of 32%, and then stir to obtain a light yellow transparent solution.

[0107] The step S1: Take a certain amount of ammonium metavanadate and place it in deionized water, add ammonia water with a concentration of 32%, and then stir to obtain a light yellow transparent solution, includes:

[0108] Take a certain amount of ammonium metavanadate and place it in deionized water, add ammonia water with a concentration of 32%, and then stir for 30 minutes to obtain a light yellow transparent solution.

[0109] The step S1: Take a certain amount of ammonium metavanadate and place it in deionized water, add ammonia water with a concentration of 32%, and then stir to obtain a light yellow transparent solution, includes:

[0110] The addition amount of ammonia water is calculated according to the molar ratio NH3 / V = 1.42, and the dissolution reaction needs to be carried out under the condition of a water bath at 72 °C.

[0111] Step S2: Dry the obtained light yellow transparent solution to obtain a vanadium-containing powder.

[0112] It should be noted that the obtained vanadium-containing powder is spherical.

[0113] In the embodiment of the present invention, drying the obtained light yellow transparent solution to obtain a vanadium-containing powder; includes:

[0114] Dry the light yellow transparent solution with a spray dryer.

[0115] In the embodiment of the present invention, the feeding speed of the spray dryer is 280 mL / h, and the air inlet temperature is controlled at 190 °C.

[0116] Step S3: Heat-treat the vanadium-containing powder to obtain vanadium pentoxide particles.

[0117] The vanadium pentoxide particles are spherical.

[0118] In an embodiment of the present invention, step S3 of heat-treating the vanadium-containing powder to obtain vanadium pentoxide particles includes:

[0119] Heat-treat the vanadium-containing powder using a muffle furnace and perform the heat treatment in an air or oxygen atmosphere.

[0120] In an embodiment of the present invention, the heat treatment temperature is 590 °C and the heat preservation time is 5.5 h.

[0121] Step S4: Mix the above-mentioned vanadium pentoxide with lithium carbonate, ammonium dihydrogen phosphate, and sucrose, and ball mill for 14 h to obtain a precursor; the molar ratio of vanadium pentoxide, lithium carbonate, ammonium dihydrogen phosphate, and sucrose is: 2:3.04:3:0.80.

[0122] Step S5: Roast the above-mentioned precursor in a roasting furnace, and after the roasting is completed, cool it to room temperature with the furnace, take out the roasted material and grind it into powder to obtain the lithium vanadium phosphate material with high tap density.

[0123] In an embodiment of the present invention, the roasting furnace can be a vacuum tube furnace.

[0124] In an embodiment of the present invention, the precursor is roasted in an argon atmosphere.

[0125] In an embodiment of the present invention, the roasting of the precursor in the roasting furnace includes:

[0126] Roast at 390 °C for 4.5 h in an argon atmosphere, then raise the temperature to 790 °C and roast for 9.5 h. After the roasting is completed, cool it to room temperature with the furnace.

[0127] Step S5 further includes passing the powder through a 125-mesh sieve to obtain the lithium vanadium phosphate material with high tap density.

[0128] Example 4

[0129] A method for preparing a lithium vanadium phosphate cathode material with high tap density includes the following steps:

[0130] Step S1: Take a quantitative amount of ammonium polyvanadate (APV) and place it in deionized water, add ammonia water with a concentration of 28%, and then stir to obtain a light yellow transparent solution.

[0131] Step S1 of taking a quantitative amount of ammonium polyvanadate and placing it in deionized water, adding ammonia water with a concentration of 28%, and then stirring to obtain a light yellow transparent solution includes:

[0132] Take a quantitative amount of ammonium polyvanadate and place it in deionized water, add ammonia water with a concentration of 28%, and then stir for 20 minutes to obtain a light yellow transparent solution.

[0133] Step S1: Take a quantitative amount of ammonium metavanadate and place it in deionized water. Add ammonia water with a concentration of 28%, and then stir to obtain a light yellow transparent solution, including:

[0134] The addition amount of ammonia water is calculated according to the molar ratio NH3 / V = 1.38, and the dissolution reaction needs to be carried out under the condition of a water bath at 68 °C.

[0135] Step S2: Dry the obtained light yellow transparent solution to obtain a vanadium-containing powder.

[0136] It should be noted that the obtained vanadium-containing powder is spherical.

[0137] In the embodiment of the present invention, drying the obtained light yellow transparent solution to obtain a vanadium-containing powder includes:

[0138] Dry the light yellow transparent solution with a spray dryer.

[0139] In the embodiment of the present invention, the feeding speed of the spray dryer is 230 mL / h, and the air inlet temperature is controlled at 160 °C.

[0140] Step S3: Heat-treat the vanadium-containing powder to obtain vanadium pentoxide particles.

[0141] The vanadium pentoxide particles are spherical.

[0142] In the embodiment of the present invention, step S3, heat-treating the vanadium-containing powder to obtain vanadium pentoxide particles, includes:

[0143] Use a muffle furnace to heat-treat the vanadium-containing powder, and carry out the heat treatment in an air or oxygen atmosphere.

[0144] In the embodiment of the present invention, the heat treatment temperature is 560 °C, and the holding time is 4.5 h.

[0145] Step S4: Mix the above vanadium pentoxide with lithium carbonate, ammonium dihydrogen phosphate, and sucrose, and ball mill for 11 to obtain a precursor; wherein the molar ratio of vanadium pentoxide, lithium carbonate, ammonium dihydrogen phosphate, and sucrose is: 2:3.01:3:0.70.

[0146] Step S5: Roast the above precursor in a roasting furnace, and after the roasting is completed, cool it to room temperature with the furnace, take out the roasted material and grind it into powder to obtain a lithium vanadium phosphate material with a high tap density.

[0147] In the embodiment of the present invention, the roasting furnace can be a vacuum tube furnace.

[0148] In the embodiment of the present invention, the precursor is roasted in an argon atmosphere.

[0149] In the embodiment of the present invention, roasting in the precursor roasting furnace includes:

[0150] Roast at 360 °C for 3.5 h in an argon atmosphere, then raise the temperature to 760 °C and roast for 8.5 h. After roasting is completed, cool to room temperature with the furnace.

[0151] Step S5 further includes passing the powder through a 115-mesh sieve to obtain a lithium vanadium phosphate material with a high tap density.

[0152] Example 5

[0153] A preparation method of a lithium vanadium phosphate cathode material with a high tap density includes the following steps:

[0154] Step S1: Take a quantitative amount of ammonium metavanadate (APV) and place it in deionized water, add ammonia water with a concentration of 30%, and then stir to obtain a light yellow transparent solution.

[0155] The step S1: Take a quantitative amount of ammonium metavanadate and place it in deionized water, add ammonia water with a concentration of 30%, and then stir to obtain a light yellow transparent solution, includes:

[0156] Take a quantitative amount of ammonium metavanadate and place it in deionized water, add ammonia water with a concentration of 30%, and then stir for 25 minutes to obtain a light yellow transparent solution.

[0157] The step S1: Take a quantitative amount of ammonium metavanadate and place it in deionized water, add ammonia water with a concentration of 30%, and then stir to obtain a light yellow transparent solution, includes:

[0158] The addition amount of ammonia water is calculated according to the molar ratio NH3 / V = 1.4, and the dissolution reaction needs to be carried out under the condition of a water bath at 70 °C.

[0159] Step S2: Dry the obtained light yellow transparent solution to obtain a vanadium-containing powder.

[0160] It should be noted that the obtained vanadium-containing powder is spherical.

[0161] In the embodiment of the present invention, drying the obtained light yellow transparent solution to obtain a vanadium-containing powder; includes:

[0162] Dry the light yellow transparent solution with a spray dryer.

[0163] In the embodiment of the present invention, the feeding speed of the spray dryer is 250 mL / h, and the air inlet temperature is controlled at 175 °C.

[0164] Step S3: Heat-treat the vanadium-containing powder to obtain vanadium pentoxide particles.

[0165] The vanadium pentoxide particles are spherical.

[0166] In an embodiment of the present invention, step S3 of heat-treating the vanadium-containing powder to obtain vanadium pentoxide particles includes:

[0167] The vanadium-containing powder is heat-treated using a muffle furnace and the heat treatment is carried out in an air or oxygen atmosphere.

[0168] In an embodiment of the present invention, the heat treatment temperature is 575 °C and the heat preservation time is 5 h.

[0169] Step S4: Mix the above vanadium pentoxide with lithium carbonate, ammonium dihydrogen phosphate, and sucrose, and ball mill for 13 h to obtain a precursor; wherein the molar ratio of vanadium pentoxide, lithium carbonate, ammonium dihydrogen phosphate, and sucrose is 2:3.03:3:0.74.

[0170] Step S5: Roast the above precursor in a roasting furnace, and after the roasting is completed, cool it to room temperature with the furnace, take out the roasted material and grind it into powder to obtain the lithium vanadium phosphate material with high tap density.

[0171] In an embodiment of the present invention, the roasting furnace can be a vacuum tube furnace.

[0172] In an embodiment of the present invention, the precursor is roasted in an argon atmosphere.

[0173] In an embodiment of the present invention, roasting the precursor in a roasting furnace includes:

[0174] Roast at 375 °C for 4 h in an argon atmosphere, then raise the temperature to 775 °C and roast for 9 h. After the roasting is completed, cool it to room temperature with the furnace.

[0175] Step S5 further includes passing the powder through a 120-mesh sieve to obtain the lithium vanadium phosphate material with high tap density.

[0176] Example 6

[0177] Take an appropriate amount of APV and place it in deionized water. Add ammonia water with a concentration of 30% (NH3 / V = 1.3), and stir for 30 minutes under the condition of a 70°C water bath to obtain a light yellow transparent solution. Dry the feed liquid with a spray dryer. The feed rate of the dryer is 200 ml / h, and the air inlet temperature is controlled at 150°C to obtain spherical vanadium-containing powder. Roast the spherical powder in a muffle furnace at 550°C for 4 hours under an air atmosphere to obtain spherical vanadium pentoxide particles. Mix vanadium pentoxide with lithium carbonate, ammonium dihydrogen phosphate, and sucrose (the molar ratio of vanadium pentoxide, lithium carbonate, ammonium dihydrogen phosphate, and sucrose is: 2:3.05:3:0.66), and ball mill for 10 hours to obtain a precursor. Put the above precursor into a vacuum tube furnace, under an argon atmosphere, at 350°C, roast for 3 hours, then raise the temperature to 800°C and roast for 8 hours. After roasting is completed, cool to room temperature with the furnace, take out and grind finely, and pass the powder through a 120-mesh sieve to obtain a lithium vanadium phosphate material with a high tap density.

[0178] Example 7

[0179] Take an appropriate amount of APV and place it in deionized water. Add ammonia water with a concentration of 30% (NH3 / V = 1.5), and stir for 30 minutes under the condition of a 70°C water bath to obtain a light yellow transparent solution. Dry the feed liquid with a spray dryer. The feed rate of the dryer is 200 ml / h, and the air inlet temperature is controlled at 150°C to obtain spherical vanadium-containing powder. Roast the spherical powder in a muffle furnace at 550°C for 4 hours under an air atmosphere to obtain spherical vanadium pentoxide particles. Mix vanadium pentoxide with lithium carbonate, ammonium dihydrogen phosphate, and sucrose (the molar ratio of vanadium pentoxide, lithium carbonate, ammonium dihydrogen phosphate, and sucrose is: 2:3.05:3:0.83), and ball mill for 15 hours to obtain a precursor. Put the above precursor into a vacuum tube furnace, under an argon atmosphere, at 400°C, roast for 5 hours, then raise the temperature to 900°C and roast for 10 hours. After roasting is completed, cool to room temperature with the furnace, take out and grind finely, and pass the powder through a 120-mesh sieve to obtain a lithium vanadium phosphate material with a high tap density.

[0180] Comparative Example 1

[0181] Take an appropriate amount of APV and roast it in a muffle furnace at 550°C for 4 hours under an air atmosphere to obtain vanadium pentoxide particles. Mix the vanadium pentoxide with lithium carbonate, ammonium dihydrogen phosphate, and sucrose (the molar ratio of vanadium pentoxide, lithium carbonate, ammonium dihydrogen phosphate, and sucrose is: 2:3.05:3:0.66), and ball mill for 10 hours to obtain a precursor. Put the above precursor into a vacuum tube furnace, under an argon atmosphere, at 350°C, roast for 3 hours, then raise the temperature to 800°C and roast for 8 hours. After roasting is completed, cool to room temperature with the furnace, take out and grind finely, and pass the powder through a 120-mesh sieve to obtain an ordinary lithium vanadium phosphate material.

[0182] Among them, the assembled button batteries of Examples 6 and 7 and Comparative Example 1 were tested for their electrochemical performance, and the test results are shown in Table 1 below, where the test voltage range was 3.0 - 4.3V.

[0183] Table 1

[0184] Example Tap density g / cm3 0.1C gram capacity (mah / g) Example 6 1.25 125 Example 7 1.17 123 Comparative Example 1 (D-1) 0.85 117

[0185] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the scope of knowledge possessed by those of ordinary skill in the art.

Claims

1. A preparation method of a lithium vanadium phosphate cathode material with high tap density, characterized in that, The method includes: Take a quantitative amount of ammonium metavanadate and place it in deionized water. Add ammonia water with a concentration of 25 - 35%, and then stir to obtain a light yellow transparent solution. Use a spray dryer to dry the obtained light yellow transparent solution to obtain spherical vanadium-containing powder. Perform heat treatment on the vanadium-containing powder to obtain spherical vanadium pentoxide particles; the heat treatment temperature is 550°C to 600°C, and the heat preservation time is 4 to 6 hours. Mix the above vanadium pentoxide with lithium carbonate, ammonium dihydrogen phosphate, and sucrose, and ball mill for 10 - 15 hours to obtain a precursor; among them, the molar ratio of vanadium pentoxide, lithium carbonate, ammonium dihydrogen phosphate, and sucrose is: 2:(3.0 - 3.05):3:(0.66 - 0.83). Roast the above precursor in a roasting furnace, and after roasting is completed, cool it to room temperature with the furnace. Take out the roasted material and grind it into powder to obtain lithium vanadium phosphate material with high tap density.

2. The preparation method of the lithium vanadium phosphate cathode material with high tap density according to claim 1, characterized in that The step of taking a quantitative amount of ammonium metavanadate and placing it in deionized water, adding ammonia water with a concentration of 25 - 35%, and then stirring to obtain a light yellow transparent solution includes: Take a quantitative amount of ammonium metavanadate and place it in deionized water. Add ammonia water with a concentration of 25 - 35%, and then stir for 20 - 30 minutes to obtain a light yellow transparent solution.

3. The preparation method of the lithium vanadium phosphate cathode material with high tap density according to claim 2, characterized in that, The step of taking a quantitative amount of ammonium metavanadate and placing it in deionized water, adding ammonia water with a concentration of 25 - 35%, and then stirring to obtain a light yellow transparent solution includes: The amount of ammonia water added is calculated according to the molar ratio NH3 / V = 1.3 - 1.5, and the dissolution reaction needs to be carried out under the condition of a water bath at 65 - 85°C.

4. The preparation method of the lithium vanadium phosphate cathode material with high tap density according to claim 3, characterized in that, The feeding speed of the spray dryer is 200 - 300 mL / h, and the air inlet temperature is controlled at 150 - 200°C.

5. The preparation method of the lithium vanadium phosphate cathode material with high tap density according to claim 1, characterized in that, The step of performing heat treatment on the vanadium-containing powder to obtain vanadium pentoxide particles includes: Use a muffle furnace to perform heat treatment on the vanadium-containing powder, and perform heat treatment in an air or oxygen atmosphere.

6. The preparation method of the lithium vanadium phosphate cathode material with high tap density as described in claim 1, wherein, The roasting furnace is a vacuum tube furnace.

7. The preparation method of the high tap density lithium vanadium phosphate cathode material according to claim 6, characterized in that, The step of roasting the precursor in a roasting furnace includes: Under an argon atmosphere, roast at 350 - 400°C for 3 - 5 hours, then raise the temperature to 750 - 800°C and roast for 8 - 10 hours. After roasting is completed, cool it to room temperature with the furnace.

8. The preparation method of the lithium vanadium phosphate cathode material with high tap density according to claim 1, characterized in that, The step of roasting the above precursor in a roasting furnace, and after roasting is completed, cooling it to room temperature with the furnace, taking out the roasted material and grinding it into powder to obtain lithium vanadium phosphate material with high tap density includes: Sieve the powder through a 110 - 130 mesh sieve to obtain lithium vanadium phosphate material with high tap density.

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