Preparation method of positive electrode material with Sb2Te3 nanometer coating layer

Abstract

The application provides a preparation method of a positive electrode material with an Sb2Te3 nanometer coating layer x M (100‑x) (OH)2 and a lithium source are uniformly mixed, and then the mixture is kept at 200-800 DEG C for 2-10 hours to obtain a primary synthesis product; then a certain amount of Na2TeO3 and SbCl3 are weighed and dissolved in organic solvents respectively, and heated and stirred to obtain a Te source solution and a Sb source solution; the Te source solution, the Sb source solution, a reducing agent and an alkaline substance are mixed in a certain proportion, and then added into a reaction kettle, and reacted under heating and pressurization for a certain time, and then dehydrated, washed and dried to obtain an Sb2Te3 nanometer material; finally, the Sb2Te3 nanometer material and the primary synthesis product are kept at 100-500 DEG C for 2-8 hours to obtain the positive electrode material with the Sb2Te3 nanometer coating layer. The positive electrode material prepared by the method has the Sb2Te3 nanometer coating layer on the surface, can prevent side reactions between the positive electrode material and an electrolyte, is beneficial to the embedding and disembedding of lithium ions, and effectively guarantees the cycle performance of the positive electrode material.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery cathode material technology, specifically to a method for preparing a cathode material with an Sb2Te3 nano-coating layer. Background Technology

[0002] With increasingly severe environmental and energy issues, the development and use of clean energy has gradually become a mainstream trend. In the battery field, lithium-ion rechargeable batteries are highly competitive due to their outstanding advantages such as high energy density, long cycle life, no memory effect, and environmental friendliness, occupying a large market share. The cathode material, as the lithium-ion source in the charging and discharging process of a lithium-ion battery, is a crucial component, requiring it to possess a stable structure and excellent electrochemical properties.

[0003] Existing cathode materials include lithium cobalt oxide, lithium manganese oxide, nickel-cobalt-manganese ternary materials, lithium-rich manganese-based layered cathode materials, and lithium iron phosphate materials. Layered cathode materials have a higher energy density than traditional olivine-type lithium iron phosphate. However, layered cathode materials exhibit superior lithium-ion insertion and extraction during charge and discharge, making them more susceptible to interfacial side reactions at grain boundaries when in contact with the electrolyte. This can compromise the structural stability of the cathode material and lead to a decline in cycle performance.

[0004] Therefore, there is a need to provide a method for preparing cathode materials with Sb2Te3 nanocoating layers to solve the aforementioned existing problems. Summary of the Invention

[0005] In view of this, the present invention provides a method for preparing a cathode material with an Sb2Te3 nano-coating layer, which can thinly and uniformly coat the surface of the cathode material with Sb2Te3 nanomaterials. While modifying the surface defects of the cathode material, it also plays a role in blocking interfacial side reactions between the electrolyte and the cathode material, stabilizing the structure. At the same time, the high conductivity of Sb2Te3 makes the cathode material coating layer conductive, thereby improving the electrochemical performance of the cathode material.

[0006] To achieve the above-mentioned technical effects, this invention provides a method for preparing a cathode material with an Sb2Te3 nano-coating layer, employing the following technical solution:

[0007] A method for preparing a cathode material with an Sb2Te3 nanocoating layer includes the following steps:

[0008] Step 1: Add metal hydroxide Ni x M (100-x) (OH)2 and lithium source are added to a mixer in a certain proportion and mixed evenly. The mixture is kept at 200-800℃ for 2-10 hours to obtain the primary synthesis product.

[0009] Step 2: Weigh a certain amount of Na2TeO3 and SbCl3 and dissolve them separately in an organic solvent, heat and stir until homogeneous to obtain Te source solution and Sb source solution;

[0010] Step 3: Mix the Te source solution, Sb source solution, reducing agent and alkaline substance in a certain proportion, add them to the reaction vessel, react for a certain time under heating and pressure, and then dehydrate, wash and dry them to obtain Sb2Te3 nanomaterials.

[0011] Step 4: The Sb2Te3 nanomaterial obtained in Step 3 and the primary synthesis product obtained in Step 1 are kept at 100-500℃ for 2-8 hours to obtain a cathode material with an Sb2Te3 nanocoating layer.

[0012] Furthermore, metal hydroxide Ni x M (100-x) In (OH)2, metal M is at least one of Co, Mn, and Al, and 50.0 ≤ x ≤ 96.0.

[0013] Furthermore, the lithium source is one or both of lithium hydroxide and lithium carbonate; metal hydroxide Ni x M (100-x) The ratio of (OH)2 to lithium source is 1:(1.02~1.08) of total metal to lithium.

[0014] Furthermore, in step 2, the concentration of the prepared Te source solution is 10-100 mmol / L, and the concentration ratio of Sb source solution to Te source solution is (5-50):1.

[0015] Furthermore, in step 2, the organic solvent is at least one of methanol, ethanol, propanol, and ethylene glycol; in step 3, the reducing agent includes at least one of hydrazine, ascorbic acid, and sodium borohydride; and the alkaline substance is a water-soluble substance, including at least one of NaOH, LiOH, and KOH.

[0016] Preferably, the reducing agent is hydrazine.

[0017] Furthermore, in step 3, the Te source solution, Sb source solution, and reducing agent are mixed in a volume ratio of 15:1:1.

[0018] Furthermore, in step 3, the Te source solution, Sb source solution, reducing agent, and alkaline substance are added to the reaction vessel, pressurized to 1 kPa to 100 kPa, heated to 100 to 500°C, and reacted for 5 to 20 hours.

[0019] Furthermore, in step 3, after the Te source solution, Sb source solution, reducing agent, and alkaline substance have reacted in the reactor, the resulting slurry is dehydrated by means of centrifugation or pressure filtration, and then washed 1 to 3 times with anhydrous ethanol. After removing the filtrate and drying, Sb2Te3 nanomaterials are obtained.

[0020] Furthermore, in step 4, the Sb2Te3 nanomaterial and the primary synthesis product are kept at 100-500℃ for 2-8 hours to obtain a cathode material with an Sb2Te3 nanocoating layer, wherein the mass fraction of Sb element in the cathode material is 500-6000 ppm.

[0021] Furthermore, Sb2Te3 can be replaced with Bi2Te3, where Sb and Bi are elements in the same group and have similar properties in tellurides.

[0022] The above-described technical solution of the present invention has at least the following beneficial effects:

[0023] 1. This invention provides a method for preparing a cathode material with an Sb2Te3 nano-coating layer, which can form a uniform nano-coating layer on the surface of the cathode material, effectively blocking interfacial side reactions between the electrolyte and the cathode material, and stabilizing the structure of the cathode material;

[0024] 3. Sb2Te3 has excellent thermoelectric properties and high electrical conductivity, which allows it to play a certain role in conducting electricity in the cathode material, thereby improving the rate capability and cycle performance of the cathode material.

[0025] 3. Sb2Te3 has a hexahedral layered structure. Its spatial structure, similar to that of cathode materials, prevents it from hindering the insertion and extraction of lithium ions during the charging and discharging process of lithium-ion batteries. Attached Figure Description

[0026] Figure 1 The charge-discharge curves are for Examples 1-3 and Comparative Examples 1-2.

[0027] Figure 2 The graph shows a comparison of the cycling at room temperature (25°C) between Examples 1-3 and Comparative Examples 1-2. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will be described in conjunction with the accompanying drawings of the embodiments of the present invention. Figure 1-2 The technical solutions of the embodiments of the present invention will be clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0029] Example 1

[0030] With LiNi as the cathode material 90.00 Co 5.97 Mn 4.03 Taking O2 as an example, in LiNi 90.00 Co 5.97 Mn 4.03 The specific steps for preparing an O2 cathode material coated with an Sb2Te3 nanolayer are as follows:

[0031] (1) Ni metal hydroxide 90.00 Co 5.97 Mn 4.03 (OH)2 and lithium hydroxide were mixed evenly in a high-speed mixer at a total metal to lithium ion molar ratio of 1:1.045, and the mixture was kept at 650℃ for 8 hours to obtain the primary synthesis product.

[0032] (2) Weigh 11.522g Na2TeO3, 23.300g PVP and 2910g ethylene glycol and add them to a conical flask to prepare Te source solution; Weigh 2.280g SbCl3 and dissolve it in 55.800g ethylene glycol and stir to prepare Sb source solution;

[0033] (3) Mix the prepared Te source solution, Sb source solution and hydrazine in a volume ratio of 15:1:1, add 5g of LiOH, add the prepared mixed solution to the reaction vessel, pressurize to 20KPa, heat to 200℃, and keep at a constant temperature for 15h;

[0034] (4) The slurry after reaction was centrifuged at 8000 r / min for 10 min to remove water, then washed twice with anhydrous ethanol, and dried after removing the filtrate to obtain Sb2Te3 nanomaterials.

[0035] (5) Sb2Te3 nanomaterials and the primary synthesis product were heated at 200℃ for 6 hours to obtain LiNi with an Sb2Te3 nanocoating layer. 90.00 Co 5.97 Mn 4.03 O2 cathode material.

[0036] A LiNi with an Sb2Te3 nanocoating layer prepared in the above embodiments 90.00 Co 5.97 Mn 4.03 O2 cathode material was used as a cathode material for lithium-ion batteries. When assembled into a coin cell, its electrochemical performance was tested. The initial discharge capacity at 0.2C was 218.8 mAh / g, the initial discharge efficiency was 93.6%, and the cycle retention rate at room temperature (25℃) for 50 cycles was 96.8%.

[0037] Example 2

[0038] With LiNi as the cathode material83.06 Co 11.05 Mn 5.89 Taking O2 as an example, in LiNi 83.06 Co 11.05 Mn 5.89 The specific steps for preparing an O2 cathode material coated with an Sb2Te3 nanolayer are as follows:

[0039] (1) Ni metal hydroxide 83.06 Co 11.05 Mn 5.89 (OH)2 and lithium hydroxide were mixed evenly in a high-speed mixer at a total metal to lithium ion molar ratio of 1:1.045, and the mixture was kept at 700℃ for 7 hours to obtain the primary synthesis product.

[0040] (2) Weigh 11.522g Na2TeO3, 23.300g PVP and 2910g ethylene glycol and add them to a conical flask to prepare Te source solution; Weigh 2.280g SbCl3 and dissolve it in 55.800g ethylene glycol and stir to prepare Sb source solution;

[0041] (3) Mix the prepared Te source solution, Sb source solution and hydrazine in a volume ratio of 15:1:1, add 5g of LiOH, add the prepared mixed solution to the reaction vessel, pressurize to 20KPa, heat to 200℃, and keep at a constant temperature for 15h;

[0042] (4) The slurry after reaction was centrifuged at 7500 r / min for 15 min to remove water, then washed twice with anhydrous ethanol, and dried after removing the filtrate to obtain Sb2Te3 nanomaterials.

[0043] (5) Sb2Te3 nanomaterials and the primary synthesis product were heated at 250℃ for 6 hours to obtain LiNi with an Sb2Te3 nanocoating layer. 83.06 Co 11.05 Mn 5.89 O2 cathode material.

[0044] A LiNi with an Sb2Te3 nanocoating layer prepared in the above embodiments 83.06 Co 11.05 Mn 5.89 O2 cathode material was used as a cathode material for lithium-ion batteries. When assembled into a coin cell, its electrochemical performance was tested. The initial discharge capacity at 0.2C was 216.5 mAh / g, the initial discharge efficiency was 92.3%, and the cycle retention rate at room temperature (25℃) for 50 cycles was 95.9%.

[0045] Example 3

[0046] With LiNi as the cathode material 88.11 Co 8.97Al 2.92 Taking O2 as an example, in LiNi 88.11 Co 8.97 Al 2.92 The specific steps for preparing an O2 cathode material coated with an Sb2Te3 nanolayer are as follows:

[0047] (1) Ni metal hydroxide 88.11 Co 8.97 Al 2.92 (OH)2 and lithium hydroxide were mixed evenly in a high-speed mixer at a total metal to lithium ion molar ratio of 1:1.030, and the mixture was kept at 620℃ for 8 hours to obtain the primary synthesis product.

[0048] (2) Weigh 11.522g Na2TeO3, 23.300g PVP and 2910g ethylene glycol and add them to a conical flask to prepare Te source solution; Weigh 2.280g SbCl3 and dissolve it in 55.800g ethylene glycol and stir to prepare Sb source solution;

[0049] (3) Mix the prepared Te source solution, Sb source solution and hydrazine in a volume ratio of 15:1:1, add 5g of LiOH, add the prepared mixed solution to the reaction vessel, pressurize to 20KPa, heat to 200℃, and keep at a constant temperature for 15h;

[0050] (4) The slurry after reaction was dehydrated by pressure filtration, then washed twice with anhydrous ethanol, and dried after removing the filtrate to obtain Sb2Te3 nanomaterials.

[0051] (5) Sb2Te3 nanomaterials and the primary synthesis product were heated at 400℃ for 5 h to obtain LiNi with an Sb2Te3 nanocoating layer. 88.11 Co 8.97 Al 2.92 O2 cathode material.

[0052] A LiNi with an Sb2Te3 nanocoating layer prepared in the above embodiments 88.11 Co 8.97 Al 2.92 O2 cathode material was used as a cathode material for lithium-ion batteries. When assembled into a coin cell, its electrochemical performance was tested. The initial discharge capacity at 0.2C was 213.7 mAh / g, the initial discharge efficiency was 91.2%, and the cycle retention rate at room temperature (25℃) for 50 cycles was 93.7%.

[0053] Comparative Example 1

[0054] Comparative Example 1: LiNi without Sb2Te3 nanocoating was prepared using the method described in Example 1. 90.00 Co 5.97 Mn 4.03O2 cathode material.

[0055] LiNi without Sb2Te3 nanocoating 90.00 Co 5.97 Mn 4.03 O2 cathode material was used as a cathode material for lithium-ion batteries. When assembled into a coin cell, its electrochemical performance was tested. The initial discharge capacity at 0.2C was 217.1 mAh / g, the initial discharge efficiency was 92.7%, and the cycle retention rate at room temperature (25℃) for 50 cycles was 93.2%.

[0056] Comparative Example 2

[0057] Comparative Example 2: A LiNi nanocoating with an Sb₂Te₃ nanolayer was prepared using the specific steps described in Example 1. 90.00 Co 5.97 Mn 4.03 O2 cathode material, in which the reducing agent hydrazine is replaced with ascorbic acid, while the mixed solution ratio remains unchanged.

[0058] A LiNi nanocoating with Sb2Te3 nanolayer prepared using ascorbic acid as a reducing agent 90.00 Co 5.97 Mn 4.03 Using O2 cathode material, assembled into a coin cell, its electrochemical performance was tested. The initial discharge capacity at 0.2C was 216.9 mAh / g, the initial discharge efficiency was 92.8%, and the cycle retention rate at room temperature (25℃) for 50 cycles was 94.2%.

[0059] Table 1. Button test results of Examples 1-3 and Comparative Examples 1-2

[0060] Group Capacity per gram (mAh / g) First-efficacy / % 50-cycle retention rate / % Example 1 218.8 93.6 96.8 Example 2 216.5 92.3 95.9 Example 3 213.7 91.2 93.7 Comparative Example 1 217.1 92.7 93.2 Comparative Example 2 216.9 92.8 94.2

[0061] The coin cell capacity of Example 1 and Example 2 is 218.8 mAh / g and 216.5 mAh / g, respectively. The Ni content of Example 1 is higher than that of Example 2, so the coin cell capacity of Example 1 is higher than that of Example 2.

[0062] The coin cell capacity and retention rates after 50 cycles at 25°C in Example 1 and Comparative Example 1 were 218.8 mAh / g and 96.8%, and 217.1 mAh / g and 93.2%, respectively. This indicates that the LiNi nanolayer with the Sb₂Te₃ nanocoating... 90.00 Co 5.97 Mn 4.03 O2 cathode material exhibits better tethering performance than LiNi without the Sb2Te3 nanocoating layer. 90.00 Co 5.97 Mn 4.03In O2 cathode materials, the Sb2Te3 nano-coating layer blocks side reactions between the electrolyte and the cathode material, effectively improving the electrochemical performance of the cathode material.

[0063] The coin cell capacity and retention rates after 50 cycles at room temperature (25°C) of Example 1 and Comparative Example 2 were 218.8 mAh / g and 96.8%, and 216.9 mAh / g and 94.2%, respectively. Example 1 prepared LiNi nanoparticles with an Sb₂Te₃ nanocoating. 90.00 Co 5.97 Mn 4.03 The reducing agent used in the O2 cathode material is hydrazine. Comparative Example 2 shows the preparation of LiNi with an Sb2Te3 nanocoating layer. 90.00 Co 5.97 Mn 4.03 The reducing agent used in the O2 cathode material is ascorbic acid. Therefore, in the preparation process of the cathode material with Sb2Te3 nano-coating layer described in this invention, the preferred reducing agent is hydrazine.

[0064] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a cathode material with an Sb2Te3 nanocoating layer, characterized in that, Includes the following steps: Step 1: Add metal hydroxide Ni x M (100-x) (OH)₂ and lithium source are added to a mixer in a certain proportion and mixed evenly. The mixture is kept at 200–800℃ for 2–10 hours to obtain the primary synthesis product; metal hydroxide Ni x M (100-x) In (OH)₂, metal M is at least one of Co, Mn, and Al, and 50.0 ≤ x ≤ 96.0; the lithium source is one or both of lithium hydroxide and lithium carbonate; the metal hydroxide Ni x M (100-x) The mixing ratio of (OH)2 with the lithium source is 1:(1.02~1.08) of the total metal to lithium molar ratio; Step 2: Weigh a certain amount of Na2TeO3 and SbCl3 and dissolve them separately in an organic solvent, heat and stir until homogeneous to obtain Te source solution and Sb source solution; In Step 2, the concentration of the obtained Te source solution is 10-100 mmol / L, and the concentration ratio of Sb source solution to Te source solution is (5-50):1; In Step 2, the organic solvent is at least one of methanol, ethanol, propanol, and ethylene glycol; Step 3: Mix the Te source solution, Sb source solution, reducing agent, and alkaline substance in a certain proportion, add them to a reaction vessel, react under heating and pressure for a certain time, and then dehydrate, wash, and dry to obtain Sb2Te3 nanomaterials; In Step 3, the reducing agent includes at least one of hydrazine, ascorbic acid, and sodium borohydride; In Step 3, the Te source solution, Sb source solution, and reducing agent are mixed in a volume ratio of 15:1:1; The alkaline substance is a water-soluble substance, including at least one of NaOH, LiOH, and KOH; Step 4: The Sb2Te3 nanomaterial obtained in Step 3 and the primary synthesis product obtained in Step 1 are kept at 100-500℃ for 2-8 hours to obtain a cathode material with an Sb2Te3 nanocoating layer.

2. The method for preparing the cathode material with an Sb₂Te₃ nano-coating layer according to claim 1, characterized in that, In step 3, the Te source solution, Sb source solution, reducing agent, and alkaline substance are added to the reaction vessel, pressurized to 1 kPa to 100 kPa, heated to 100 to 500 °C, and reacted for 5 to 20 hours.

3. The method for preparing the cathode material with an Sb₂Te₃ nano-coating layer according to claim 1, characterized in that, In step 3, after the Te source solution, Sb source solution, reducing agent, and alkaline substance have reacted in the reactor, the resulting slurry is dehydrated by centrifugation or pressure filtration, then washed 1 to 3 times with anhydrous ethanol, and after removing the filtrate and drying, Sb2Te3 nanomaterials are obtained.

4. The method for preparing the cathode material with an Sb₂Te₃ nano-coating layer according to claim 1, characterized in that, In step 4, the Sb2Te3 nanomaterial and the primary synthesis product are kept at 100-500℃ for 2-8 hours to obtain a cathode material with an Sb2Te3 nanocoating layer. The mass fraction of Sb element in the cathode material is 500-6000 ppm.

5. The method for preparing the cathode material with an Sb₂Te₃ nano-coating layer according to claim 1, characterized in that, The Sb2Te3 can be replaced with Bi2Te3, where Sb and Bi are elements from the same group.

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