A coated layered oxide sodium-ion battery cathode material with excellent cycle stability

Abstract

The application provides a coated layered oxide sodium ion battery positive electrode material with excellent cycle stability, the positive electrode material is coated with nano-aluminum oxide and nano-titanium oxide on the surface of Na 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2 material. The positive electrode material provided by the application exhibits excellent long cycle stability and has a wide commercial development prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sodium ion batteries, and particularly relates to a coated layered oxide sodium ion battery positive electrode material with excellent cycle stability and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of social economy, the traditional fossil energy structure cannot meet the actual development needs, and the concept of pursuing ecological environmental protection also promotes various fields to seek more efficient and green sustainable new energy storage systems. In the past few years, the energy such as wind energy, water energy and tidal energy has been successfully applied in some areas in the development process, but this application is largely limited by the region, and the energy efficiency cannot meet the needs of long-term social development, so it is necessary to explore more suitable energy storage systems. In recent years, through the continuous research and exploration of scientists, lithium ion batteries as efficient portable energy storage devices gradually entered the field of vision of people, and finally realized the commercial application of lithium ion batteries through unremitting efforts and exploration, and successfully applied to the production and life of people, bringing great convenience. However, with the development of society to a deeper level, the limited lithium resources and high lithium price make lithium batteries cannot meet the needs of long-term development. Based on this, it is urgent to explore new energy storage devices suitable for social development to better benefit human beings and improve people's material living standards. In this exploration process, sodium resources similar to lithium have received extensive attention, given their similar physical and chemical properties to lithium and more abundant crustal reserves. Once the research is successful, it can greatly reduce the price of energy storage devices, and effectively meet the current social development needs. However, the larger atomic radius and weight of sodium than lithium make sodium ion batteries undergo more complex structural changes in the actual reaction process, thereby seriously affecting the performance of sodium ion batteries, resulting in poor electrochemical performance. Therefore, more suitable methods are needed to develop high-performance electrode materials for application in sodium ion batteries. SUMMARY

[0003] In view of the above, the technical problem to be solved by the present application is to provide a coated layered oxide sodium ion battery positive electrode material with excellent cycle stability and a preparation method thereof. The positive electrode material provided by the present application has long cycle performance, and the entire synthesis process is simple and has high yield.

[0004] To achieve the above purposes, the present application adopts the following technical solutions:

[0005] The present application first discloses a coated layered oxide sodium ion battery positive electrode material with excellent cycle stability, which is Na 0.66 Ni 0.23 Cu 0.1 Mn 0.67The surface of the O2 material is coated with nano-alumina and nano-titanium oxide.

[0006] Furthermore, the mass percentage of the nano-alumina in Na 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2 content is 1-5% by mass; the nano-titanium oxide content is 1-5% by mass of Na. 0.66 Ni 0.23 Cu 0.1 Mn 0.67 1-5% of the mass of O2;

[0007] The coated layered oxide sodium-ion battery cathode material with excellent cycle stability described in this invention can be prepared by a wet chemical method. The specific steps are as follows:

[0008] Step 1, Na 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2 material, nano-alumina, and nano-titanium oxide are placed in a ball mill jar, and ethanol is added for wet ball milling. The mixture is then removed and dried to obtain the precursor material.

[0009] Step 2: Calcine the precursor to obtain the final product, a coated layered oxide sodium-ion battery cathode material, denoted as Na. 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2@(Al2O3+TiO2).

[0010] Further, the calcination method described in step 2 is as follows: in an air atmosphere, the temperature is raised to 350-600°C at a heating rate of 2-10°C, and held for 4-10 hours.

[0011] Na used in this invention 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2 can be prepared using the sol-gel method, with the following specific steps:

[0012] Sodium source compound, nickel source compound, copper source compound, and manganese source compound were dissolved in deionized water with a chelating agent at a certain molar ratio. The mixture was stirred continuously until fully mixed. The deionized water was evaporated in a constant temperature oil bath with continuous stirring to obtain a preliminary sample. The sample was then further dried at high temperature in an oven to obtain a dried sample.

[0013] The dried sample was ground to obtain powder;

[0014] The powder was subjected to a two-step calcination process to obtain product Na.0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2.

[0015] Further: the sodium source compound is one or more of sodium oxalate, sodium chloride, sodium nitrate, sodium acetate, and sodium sulfate; the nickel source compound is one or more of nickel oxalate, nickel chloride, nickel nitrate, nickel acetate, and nickel sulfate; the copper source compound is one or more of copper oxalate, copper chloride, copper nitrate, copper acetate, and copper sulfate; the manganese source compound is one or more of manganese oxalate, manganese chloride, manganese nitrate, manganese acetate, and manganese sulfate; and the chelating agent is one or more of citric acid, oxalic acid, tartaric acid, or ethylenediaminetetraacetic acid.

[0016] Furthermore, the two-step calcination is divided into a first part of pre-calcination and a second part of high-temperature calcination; the pre-calcination involves heating to 350-600℃ at a heating rate of 2-10℃ / min and holding at that temperature for 4-10 hours; the high-temperature calcination involves continuing to heat to 800-1000℃ at a heating rate of 2-10℃ / min and holding at that temperature for 10-24 hours.

[0017] The present invention also prepared a sodium-ion battery cathode sheet, which is prepared from the synthesized layered oxide sodium-ion battery cathode material with excellent cycle stability, conductive additives, binders and related solvents.

[0018] The present invention also discloses a sodium-ion battery, which is composed of the above-prepared positive electrode, separator, electrolyte and negative electrode metallic sodium. It has shown great application prospects in many energy storage devices, such as electric vehicles, solar power generation, wind power generation, smart grid peak shaving, distributed power stations or communication bases, etc.

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

[0020] This invention provides a coated layered oxide sodium-ion battery cathode material, Na, with excellent cycle stability. 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2@(Al2O3+TiO2), through the synergistic coating of Al2O3 and TiO2, exhibits extremely long cycle stability, further promoting the commercialization of sodium-ion battery cathode materials. Furthermore, the cathode material provided by this invention has a simple synthesis route and excellent electrochemical performance. Attached Figure Description

[0021] Figure 1 The image shown is an SEM image of the target product obtained in Example 1.

[0022] Figure 2The image shows the XRD pattern of the target product obtained in Example 1.

[0023] Figure 3 The charge-discharge curve of the target product obtained in Example 1 at a current density of 0.1C is shown.

[0024] Figure 4 The image shows the cyclic stability spectrum of the target product obtained in Example 1 at a current density of 0.1C.

[0025] Figure 5 The spectrum is the rate performance spectrum of the target product obtained in Example 1.

[0026] Figure 6 The image shows the cyclic stability spectrum of the target product obtained in Example 1 at a current density of 1C.

[0027] Figure 7 The image shows the cyclic stability spectrum of the target product obtained in Example 1 at a current density of 5C.

[0028] Figure 8 The charge-discharge curve of the target product obtained in Example 2 at a current density of 0.1C is shown.

[0029] Figure 9 The image shows the cyclic stability spectrum of the target product obtained in Example 2 at a current density of 1C.

[0030] Figure 10 The charge-discharge curve of the target product obtained in Example 3 at a current density of 0.1C is shown.

[0031] Figure 11 The image shows the cyclic stability spectrum of the target product obtained in Example 3 at a current density of 1C.

[0032] Figure 12 The charge-discharge curve of the target product obtained in Example 4 at a current density of 0.1C is shown.

[0033] Figure 13 The image shows the cyclic stability spectrum of the target product obtained in Example 4 at a current density of 1C. Detailed Implementation

[0034] This invention provides a coated layered oxide sodium-ion battery cathode material, Na, with excellent cycle stability. 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2@(Al2O3+TiO2). The sodium-ion battery cathode material provided by this invention is in bulk form.

[0035] In some specific embodiments of the present invention, the sodium-ion battery cathode material is Na. 0.66 Ni0.23 Cu 0.1 Mn 0.67 O2@2%(Al2O3+TiO2), where 2% represents that the mass of both nano-Al2O3 and nano-TiO2 is Na. 0.66 Ni 0.23 Cu 0.1 Mn 0.67 It contains 2% O2 by mass. Its overall performance is the best, exhibiting excellent cycle stability at 5C (1C = 170 mAg). -1 It can stably cycle 2000 times under high current density with a capacity retention rate of 84.6%, which greatly promotes the future commercial application of sodium-ion batteries.

[0036] This invention also successfully prepared a sodium-ion battery positive electrode sheet, which is made of positive electrode material, conductive additive, binder and solvent, wherein: the positive electrode material is selected from the above-synthesized coated layered oxide sodium-ion battery positive electrode material with excellent cycle stability; the conductive additive is selected from one or more of carbon black, Super-P and Ketjen black; the binder is selected from one or more of sodium carboxymethyl cellulose, polyacrylic acid, sodium alginate and polyvinylidene fluoride; and the solvent is selected from one or more of N-methylpyrrolidone or deionized water.

[0037] The present invention also provides a method for preparing the above-mentioned sodium-ion battery positive electrode sheet, which involves mixing positive electrode material, conductive additives, binders and solvents in a certain proportion, and then preparing the battery positive electrode sheet through subsequent coating and drying processes.

[0038] The specific methods for mixing, coating, and drying in this invention are common preparation methods, which can be followed according to methods known to those skilled in the art.

[0039] This invention also prepares a sodium-ion battery, comprising a positive electrode, a separator, an organic electrolyte, and a negative electrode of metallic sodium, wherein: the positive electrode uses the aforementioned sodium-ion battery positive electrode. The electrolyte used is a carbonate-based electrolyte with a concentration of 0.5–2 M, preferably 1 M; the solvent in the electrolyte is derived from one or more of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, and fluorinated ethylene carbonate, preferably a mixed solvent of propylene carbonate and fluorinated ethylene carbonate; the solute in the electrolyte is selected from one or more of sodium perchlorate, sodium hexafluorophosphate, and sodium bis(trifluoromethanesulfonyl)imide, preferably sodium perchlorate. The separator is preferably glass fiber.

[0040] This invention also provides the application of the above-mentioned sodium-ion battery in large-scale energy storage devices such as electric vehicles, solar power generation, wind power generation, smart grid peak shaving, distributed power stations or communication bases.

[0041] The present invention has the following advantages:

[0042] (1) A bulk-coated layered oxide sodium-ion battery cathode material with excellent cycle stability, Na, was synthesized. 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2@(Al2O3+TiO2) has greatly promoted the future commercial development of sodium-ion battery material systems.

[0043] (2) The Na of the present invention 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2@(Al2O3+TiO2) exhibits excellent cycle stability and is inexpensive, making it a promising cathode material for sodium-ion batteries.

[0044] (3) The optimal Na of this invention 0.66 Ni 0.23 Cu 0.1 Mn 0.67 The O2@2% (Al2O3+TiO2) cathode material exhibits the best cycle stability. This is attributed to the abundant resources and excellent chemical stability of Al2O3 and TiO2, which effectively reduce side reactions between the materials and the electrolyte during the reaction process. Their combined interaction further enhances electrochemical performance. This material achieves excellent cycle stability at 5C (1C = 170 mAg). -1 It retains a capacity of up to 84.6% after 2000 cycles at a current density, making it an ideal cathode material for preparing sodium-ion battery energy storage devices.

[0045] (4) Compared with materials that are not coated and materials that are only coated with nano-Al2O3 or nano-TiO2, the cathode material synthesized by the method of the present invention has better overall performance.

[0046] To further understand the present invention, the following description, in conjunction with specific embodiments, illustrates the superior performance of the layered oxide sodium-ion battery cathode material provided by the present invention, its preparation method, and its application. The scope of protection of the present invention is not limited by the following embodiments.

[0047] Example 1

[0048] Step 1, Prepare Na 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2@2% (Al2O3+TiO2) cathode material

[0049] Sodium acetate, nickel acetate, copper acetate, manganese acetate, and citric acid were dissolved in deionized water (the molar ratio of sodium acetate, nickel acetate, copper acetate, and manganese acetate was 0.66:0.23:0.1:0.67, and the total molar amount of the four components was 1:3 with the molar ratio of citric acid). The mixture was stirred continuously until homogeneous. The solution was transferred to an 80°C oil bath and stirred until the solution was completely evaporated. The sample was then transferred to a 150°C oven and dried for 6 hours. After cooling to room temperature, the sample was removed and ground into powder in a mortar.

[0050] The powder sample was placed in a muffle furnace and calcined in air in a two-step process: first, the temperature was increased to 450℃ at a rate of 2℃ / min and held for 6 hours; then, the temperature was further increased to 950℃ at a rate of 2℃ / min and held for 15 hours. After cooling to room temperature, the product Na was obtained. 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2.

[0051] Will Na 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2 material, nano-alumina, and nano-titanium oxide were placed in a ball mill jar (the mass of nano-Al2O3 and nano-TiO2 were both Na). 0.66 Ni 0.23 Cu 0.1 Mn 0.67 Add 2% (by mass) of O2, then add an appropriate amount of ethanol and perform wet ball milling for 24 hours at a speed of 400 r / min. The material is then removed and dried to obtain the precursor material. The precursor is then calcined in air (heated to 550℃ at a rate of 2℃ and held for 5 hours) to obtain the final product, a coated layered oxide sodium-ion battery cathode material, denoted as Na. 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2@2%(Al2O3+TiO2).

[0052] Step 2, Preparation of sodium-ion battery positive electrode sheet

[0053] The Na synthesized above 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2@2% (Al2O3+TiO2) cathode material, SuperP, and polyvinylidene fluoride binder (PVDF) are mixed at a mass ratio of 7:2:1, with a certain amount of N-methylpyrrolidone added as a solvent. After mixing, slurrying, coating, and drying, a product containing Na is obtained. 0.66 Ni0.23 Cu 0.1 Mn 0.67 Sodium-ion battery cathode material with O2@2% (Al2O3+TiO2) active material.

[0054] Step 3, assemble with the final product Na 0.66 Ni 0.23 Cu 0.1 Mn 0.67 Sodium-ion batteries with O2@2% (Al2O3+TiO2) as the positive electrode material.

[0055] The sodium-ion battery positive electrode and metallic sodium negative electrode prepared above were assembled into a sodium-ion battery in a glove box. GF / F was used as the battery separator, and carbonate electrolyte (1M NaClO4 in PC) was selected as the electrolyte.

[0056] Figure 1 The image shown is a SEM image of the cathode material prepared in Example 1. As can be seen from the image, the material has a blocky morphology.

[0057] Figure 2 The image shown is an XRD pattern of the cathode material obtained in Example 1, which has a P2 phase structure.

[0058] Figure 3 The image shows a sodium-ion battery assembled using the cathode material obtained in Example 1 at 0.1C (1C = 170 mAg). -1 The charge-discharge curves at the current density show that the synthesized material exhibits a capacity of 86.2 mAh / g in sodium-ion batteries. -1 The specific discharge capacity.

[0059] Figure 4 The results show the cycle stability test results of the sodium-ion battery assembled with the cathode material obtained in Example 1 at a current density of 0.1C. It can be stably cycled for 100 cycles with a capacity retention rate of 97.6%.

[0060] Figure 5 The figure shows the rate performance test results of the sodium-ion battery assembled with the cathode material obtained in Example 1 at different current densities. As shown in the figure, it exhibits excellent rate performance, still achieving 53.4 mAh g⁻¹ at 20C. -1 Electrochemical capacity.

[0061] Figure 6 The results show the cycle stability test results of the sodium-ion battery assembled with the cathode material obtained in Example 1 at a current density of 1C. After 600 stable cycles, it still retains 89.3% of its capacity.

[0062] Figure 7The results show the cycle stability test results of the sodium-ion battery assembled with the cathode material obtained in Example 1 at a current density of 5C. After 2000 cycles, it still has a capacity retention rate of up to 84.6%.

[0063] Example 2

[0064] The preparation method is the same as in Example 1, except that the mass of both nano-Al2O3 and nano-TiO2 is Na. 0.66 Ni 0.23 Cu 0.1 Mn 0.67 When the O2 mass is 0%, i.e., without the addition of nano-Al2O3 and nano-TiO2, the resulting cathode material is denoted as Na. 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2@0%(Al2O3+TiO2).

[0065] Figure 8 The image shows a sodium-ion battery assembled using the cathode material obtained in Example 2 at 0.1C (1C = 170 mAg). -1 The charge-discharge curves at the current density are shown in the figure. As can be seen from the figure, the synthesized material exhibits a current density of 105.8 mAh g⁻¹ in sodium-ion batteries. -1 The specific discharge capacity.

[0066] Figure 9 The image shows a sodium-ion battery assembled using the cathode material obtained in Example 2 at 1C (1C = 170 mAg). -1 Cyclic stability at current density: As shown in the figure, the synthesized material retains 79.1% of its capacity after 400 cycles in a sodium-ion battery.

[0067] Example 3

[0068] The preparation method is the same as in Example 1, except that the mass of both nano-Al2O3 and nano-TiO2 is Na. 0.66 Ni 0.23 Cu 0.1 Mn 0.67 The cathode material obtained by adding 1% of the mass of O2 is denoted as Na. 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2@1%(Al2O3+TiO2).

[0069] Figure 10 The image shows a sodium-ion battery assembled using the cathode material obtained in Example 3 at 0.1C (1C = 170 mAg). -1 The charge-discharge curves at the current density are shown in the figure. As can be seen from the figure, the synthesized material exhibits a charge-discharge ratio of 85.6 mAh g⁻¹ in sodium-ion batteries.-1 The specific discharge capacity.

[0070] Figure 11 The image shows a sodium-ion battery assembled using the cathode material obtained in Example 3 at 1C (1C = 170 mAg). -1 As shown in the figure, the synthesized material retains 81.3% of its capacity after 400 cycles in a sodium-ion battery, demonstrating cycling stability at current density.

[0071] Example 4

[0072] The preparation method is the same as in Example 1, except that the mass of both nano-Al2O3 and nano-TiO2 is Na. 0.66 Ni 0.23 Cu 0.1 Mn 0.67 The cathode material obtained by adding 3% of the mass of O2 is denoted as Na. 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2@3% (Al2O3+TiO2).

[0073] Figure 12 The image shows a sodium-ion battery assembled using the cathode material obtained in Example 4 at 0.1C (1C = 170 mAg). -1 The charge-discharge curves at the current density are shown in the figure. It can be seen that 80.2 mAh g can be released during the initial cycle. -1 The specific discharge capacity.

[0074] Figure 13 The image shows a sodium-ion battery assembled using the cathode material obtained in Example 4 at 1C (1C = 170 mAg). -1 As shown in the figure, the synthesized material exhibits 84.1% capacity retention after 400 cycles in a sodium-ion battery, demonstrating cycling stability at current density.

[0075] The above description is only a preferred embodiment 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 coated layered oxide sodium-ion battery cathode material with excellent cycle stability, characterized in that: The sodium-ion battery cathode material is made of Na... 0.66 Ni 0.23 Cu 0.1 Mn 0.67 The surface of the O2 material is coated with nano-alumina and nano-titanium oxide.

2. The coated layered oxide sodium-ion battery cathode material with excellent cycle stability according to claim 1, characterized in that: The mass ratio of nano-alumina to Na 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2 content is 1-5% by mass; the nano-titanium oxide content is 1-5% by mass of Na. 0.66 Ni 0.23 Cu 0.1 Mn 0.67 1-5% of the mass of O2.

3. A method for preparing a coated layered oxide sodium-ion battery cathode material with excellent cycle stability as described in claim 1 or 2, characterized in that, Includes the following steps; Step 1, Na 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2 material, nano-alumina, and nano-titanium oxide are placed in a ball mill jar, ethanol is added, and wet ball milling is performed. The material is then removed and dried to obtain the precursor material. Step 2: Calcine the precursor to obtain the final product, a coated layered oxide sodium-ion battery cathode material, denoted as Na. 0.66 Ni 0.23 Cu 0.1 Mn 0.67 O2@(Al2O3+TiO2).

4. The preparation method according to claim 3, characterized in that: The calcination method described in step 2 is as follows: in an air atmosphere, the temperature is raised to 350-600°C at a heating rate of 2-10°C, and held for 4-10 hours.

5. A sodium-ion battery positive electrode sheet, prepared from a positive electrode material, conductive additives, a binder, and a solvent, characterized in that: The cathode material is selected from the coated layered oxide sodium-ion battery cathode material with excellent cycle stability described in claim 1.

6. A sodium-ion battery, comprising a positive electrode, a separator, an organic electrolyte, and a negative electrode of metallic sodium, characterized in that: The positive electrode is the sodium-ion battery positive electrode as described in claim 5.

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