SnxSey surface modified O3 type layered oxide positive electrode material and preparation method thereof
By constructing a SnxSey coating layer on the surface of layered oxide cathode material for sodium-ion batteries and performing elemental doping, the structural collapse and side reaction problems of layered oxide cathode materials in sodium-ion batteries during charge and discharge processes are solved, the stability and cycle life of the material are improved, and low-cost and environmentally friendly material improvement is achieved.
Patent Information
- Application Number
- CN202511019615.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-23
- Publication Date
- 2025-10-28
AI Technical Summary
Existing layered oxide cathode materials for sodium-ion batteries suffer from irreversible phase transitions due to sodium ion insertion/extraction during charge and discharge, structural collapse, surface moisture absorption and pulverization due to air sensitivity, and electrolyte decomposition caused by residual alkali, all of which affect the stability and cycle life of the materials.
By constructing a uniform SnxSey coating layer on the surface of the substrate NaNiaFebMnzO2, and adopting a synergistic strategy of surface coating and elemental doping, a SnxSey surface-modified O3-type layered oxide cathode material was prepared. The SnxSey coating was used as a protective layer to suppress phase transitions and side reactions and enhance material stability. Furthermore, the surface residual alkali removal and gradient doping were achieved through a controllable heat treatment process.
It improves the structural stability and cycle life of layered oxide cathode materials for sodium-ion batteries, enhances the stability of the material during high-voltage charge and discharge processes, improves cycle stability by more than 50%, and reduces the cost and environmental impact of the material.
Smart Images
Figure CN120854529A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of sodium-ion battery electrode material preparation technology, and particularly to a Sn... x Se y Surface-modified O3-type layered oxide cathode material and its preparation method. Background Technology
[0002] In recent years, the development of electrochemical energy storage technology has shown a trend of prioritizing economy and safety while weakening energy density. Although lithium-ion batteries dominate the secondary battery market, their large-scale energy storage applications face bottlenecks due to the scarcity and uneven distribution of lithium resources. Sodium-ion batteries, with their similar physicochemical properties to lithium batteries and the advantage of abundant sodium resources, have seen significant technological advancements since 2010, with demonstration projects gradually expanding in scale. They have demonstrated the potential to replace lithium batteries, achieving both cost reduction and energy density exceeding 160 Wh / kg. As the core component of sodium batteries, the cathode material directly determines the system's energy density and cycle life. Currently, the mainstream systems cover four main categories: polyanionic, Prussian blue, layered oxides, and organic polymers. Among them, layered oxides, with their high specific capacity of approximately 200 mAh / g, excellent rate performance (10C capacity retention >80%), and suitability for large-scale solid-state sintering processes, have become a key direction for industrialization. However, this material suffers from three core defects: First, the deintercalation and intercalation of sodium ions during charging and discharging leads to an irreversible P2→O2 phase transition, resulting in a volume expansion of >5%. Simultaneously, the multi-stage phase transition with O3 induces structural collapse, leading to a capacity decay rate >0.1% / week. Second, air sensitivity causes surface moisture absorption and pulverization; when humidity >30% RH, the expansion rate reaches 8% in 24 hours, accelerating interfacial side reactions. Third, residual alkali accumulation occurs; when the surface Na2CO3 content >5wt%, it triggers electrolyte decomposition and a surge in impedance. Therefore, through transition metal doping, such as Mg... 2+ / Ti 4+ By employing strategies such as site control, atomic layer deposition and coating (e.g., Al2O3 < 5nm) and P / O two-phase composite structure design (e.g., P2 / O3 interface energy < 0.5 J / m²), a triple optimization system of "bulk phase-interface-macrostructure" is constructed, propelling layered oxide cathodes into the pilot-scale production stage. Summary of the Invention
[0003] The purpose of this invention is to provide a SnxSey surface-modified O3-type layered oxide cathode material and its preparation method, addressing the aforementioned problems.
[0004] To achieve the above objectives, the present invention adopts the following technical solution:
[0005] A Sn x Se ySurface-modified O3-type layered oxide cathode materials, through a synergistic strategy of surface coating and elemental doping, are developed on a NaNi substrate. a Fe b Mn z O2 surface builds uniform Sn x Se y Coating layer, Sn x Se y With NaNi a Fe b Mn z The mass ratio of O2 is 1:50-200; Sn x Se y In the middle, 0.5 <x:y≤1;NaNi a Fe b Mn z In O2, 0.2≤a≤0.4, 0.2≤b≤0.4, and 0.2≤z≤0.4.
[0006] Furthermore, the aforementioned Sn x Se y The preparation method of surface-modified O3-type layered oxide cathode material includes the following steps:
[0007] 1) Based on the chemical formula of the matrix NaNi a Fe b Mn z The molar ratio of Ni:Fe:Mn in O2 is a:b:z. Weigh out nickel salt, iron salt and manganese salt, and then dissolve nickel salt, iron salt and manganese salt in deionized water to prepare nickel salt solution, iron salt solution and manganese salt solution with molar concentration of 0.5-2 mol / L respectively.
[0008] 2) Mix the alkali solution and the complexing agent to prepare a mixed alkali solution;
[0009] 3) Add the mixed alkaline solution obtained in step 2) into the reaction vessel and control the pH value between 9 and 12;
[0010] 4) The nickel salt solution, iron salt solution and manganese salt solution prepared in step 1) are added to the reaction vessel at a uniform rate. The pH value is 9-12 and the temperature is 40-60℃ throughout the process.
[0011] 5) After adding the nickel salt solution, iron salt solution and manganese salt solution, let it stand for 3-12 hours, then filter, wash and dry the precipitate;
[0012] 6) The dried precipitate is uniformly mixed with sodium salt, and a small amount of flux is added to lower the crystal phase transformation temperature. The mixture is then sintered in air to obtain the layered oxide cathode material for sodium-ion batteries, i.e., the matrix NaN. a Feb Mn z O2, the mass ratio of flux to matrix is 1:40;
[0013] 7) Dissolve the selenium source and tin source in ethanol, and then add the NaNi matrix obtained in step 6). a Fe b Mn z O2 is evaporated at 80-100℃ to form a powder;
[0014] 8) The powder obtained in step 7) is vacuum dried and crushed at 80-120℃, and then calcined in an argon or argon-hydrogen mixed atmosphere to obtain the Sn. x Se y Surface-modified O3-type layered oxide cathode material; the H2 concentration in the argon-hydrogen mixed atmosphere is 5%.
[0015] Preferably, in step 1) of the above preparation method, the nickel salt is one or more of nickel sulfate, nickel nitrate and nickel acetate; the iron salt is one or more of ferric sulfate, ferric nitrate and ferric acetate; and the manganese salt is one or more of manganese sulfate, manganese nitrate and manganese acetate.
[0016] Preferably, in step 2) of the above preparation method, the alkaline solution is one or both of sodium hydroxide solution and potassium hydroxide solution, and the molar concentration of the alkaline solution is 2-10 mol / L; the complexing agent is one or both of ammonia water and urea solution, and the mass concentration of the complexing agent is 25%-28%; the volume ratio of the alkali to the complexing agent is 10:1.
[0017] Preferably, the sodium salt in step 6) of the above preparation method is one or more of sodium hydroxide, sodium carbonate, and sodium acetate; and the flux is one or more of sodium chloride, sodium nitrate, and sodium metaborate.
[0018] Preferably, in step 6) of the above preparation method, the molar ratio of the precipitate to the sodium salt is 1:1.03-1:1.05.
[0019] Preferably, the specific conditions and steps for sintering in step 6) of the above preparation method are as follows: first, heat the temperature to 350-500℃ at a heating rate of 1-5℃ / min and hold for 4-6 hours for pre-firing; then heat the temperature to 800-950℃ at a heating rate of 1-5℃ / min and hold for 14-20 hours for calcination; finally, depending on the situation, cool the temperature to 600-350℃ at a cooling rate of 1-5℃ / min and hold for 3-6 hours.
[0020] Preferably, the selenium source mentioned in step 7) of the above preparation method is one or more of selenium powder and selenium dioxide, and the tin source is one or more of tin powder, tin dioxide and tin tetrachloride.
[0021] Preferably, the calcination conditions in step 8) of the above preparation method are: heating to 300-500℃ at a heating rate of 1-5℃ / min and holding at that temperature for 0.5-6 hours.
[0022] In summary, due to the adoption of the above technical solution, the present invention has the following beneficial effects:
[0023] 1. The Sn prepared in this invention x Se y The coating, acting as a protective layer, covers the surface of the layered oxide cathode material in sodium-ion batteries. Firstly, it reduces side reactions and improves air stability. Secondly, its elemental surface doping regulates the bulk phase of the cathode material, suppressing phase transitions and maintaining structural stability. Thirdly, it reacts with excess Na₂CO₃ to generate sodium selenate or sodium selenite, which exhibit high-voltage stability, thereby improving the material's stability during charge and discharge. Finally, this coating, being an N-type semiconductor, can form a PN-type heterostructure interface with the cathode material, thus constructing a triple optimization system of "bulk phase-interface-macrostructure," enhancing the structural stability and cycle life of the layered oxide cathode material in sodium-ion batteries.
[0024] 2. This invention utilizes a controllable heat treatment process to heat Sn in an Ar / 5% H2 mixed atmosphere. x Se y In-situ chemical reaction occurs with residual alkali on the surface of the cathode material, simultaneously achieving residual alkali removal and gradient doping control, mitigating surface side reactions of the cathode material, and effectively suppressing structural collapse during repeated sodium ion insertion / extraction. Simultaneously, surface doping, specifically Sn / Se co-doping, enhances structural stability during cycling. This process constructs Sn-based composites on the particle surface that possess both chemical bonding and electrochemical compatibility characteristics. x Se y The coating layer effectively suppresses side reactions at the electrode interface during high-voltage charging and discharging, thereby improving the cycle stability of the layered oxide cathode material by more than 50%.
[0025] 3. This invention combines co-precipitation with a solid-state method, making it simple and easy to operate. It contains no Co, but is rich in Fe and Mn, making it abundant in resources, low in cost, and with low sintering energy consumption, thus being environmentally friendly. This method combines easily controllable process parameters, low energy consumption and cost, and environmental friendliness, overcoming the interface compatibility bottleneck of traditional coating processes. Sn generated using the method described in this invention... x Se y In its current state, the coating acts as a sodium-ion protective layer, covering the surface of the layered oxide cathode material of the sodium-ion battery. The elemental surface doping adjusts the interaction force of the cathode material, thereby improving the structural stability and cycle life of the layered oxide cathode material of the sodium-ion battery. Attached Figure Description
[0026] Figure 1 XRD patterns of SnSe-coated surface-modified layered oxide cathode material for sodium-ion batteries and layered oxide cathode material for sodium-ion batteries.
[0027] Figure 2 NaNi is a layered oxide cathode material for sodium-ion batteries. a Fe b Mn z SEM image of O2.
[0028] Figure 3 SEM image of the SnSe-coated surface-modified layered oxide cathode material for sodium-ion batteries.
[0029] Figure 4 The initial charge-discharge curves of the SnSe-coated surface-modified layered oxide cathode material for sodium-ion batteries and the layered oxide cathode material for sodium-ion batteries at a current density of 0.1 C are shown.
[0030] Figure 5 The discharge cycle curves of the SnSe-coated surface-modified layered oxide cathode material for sodium-ion batteries and the layered oxide cathode material for sodium-ion batteries at a current density of 1.0 C are shown. Detailed Implementation
[0031] To more clearly illustrate the present invention, the following specific embodiments will be used to further explain the invention.
[0032] Example 1:
[0033] This embodiment prepares a SnSe surface-modified O3-type layered oxide cathode material with the chemical formula NaNi. 0.4 Fe 0.2 Mn 0.4 O2 is used as the layered oxide cathode material for sodium-ion batteries as the matrix, and a synergistic strategy of surface coating and elemental doping is employed to achieve the desired effect on the NaNi matrix. 0.4 Fe 0.2 Mn 0.4 A uniform SnSe coating layer is constructed on the O2 surface. The specific preparation method includes the following steps:
[0034] 1) According to the chemical formula of the matrix sodium-ion battery layered oxide cathode material NaNi 0.4 Fe 0.2 Mn 0.4 To prepare a 2 mol / L salt solution, 670.2 g of nickel sulfate hexahydrate, 333.6 g of ferrous sulfate heptahydrate, and 405.8 g of manganese sulfate monohydrate were weighed out and dissolved in 3 L of deionized water to achieve a molar ratio of Ni:Fe:Mn = 0.4:0.2:0.4.
[0035] 2) Dissolve 1000g of NaOH in 2500mL of deionized water to prepare a NaOH solution with a concentration of approximately 10 mol / L, and then mix it with 250mL of ammonia solution with a mass concentration of 25% to prepare a mixed alkaline solution;
[0036] 3) Add the mixed alkaline solution obtained in step 2) into the reaction vessel using a peristaltic pump, and control the pH value in the reaction vessel to 10;
[0037] 4) The nickel salt solution, iron salt solution and manganese salt solution prepared in step 1) are added to the reaction vessel at a constant speed using a peristaltic pump. The pH value is controlled at 9 and the temperature is controlled at 60°C throughout the process.
[0038] 5) After the nickel salt solution, iron salt solution, and manganese salt solution have been added, let it stand for 12 hours to age. Then, filter, wash, and dry the precipitate to obtain the dried precipitate Ni. 0.4 Fe 0.2 Mn 0.4 (OH)2;
[0039] 6) Weigh 1.6239 g of dried Ni precipitate at a molar ratio of 1:1.05. 0.4 Fe 0.2 Mn 0.4 (OH)₂ and 0.9971g of sodium carbonate are mixed evenly, and 0.05g of sodium chloride flux is added. In an air atmosphere, the mixture is first heated to 450℃ at a heating rate of 1-5℃ / min, then pre-calcined at 450℃ for 5 hours, and then heated to 850℃ at a heating rate of 1-5℃ / min. Finally, it is calcined at 850℃ for 15 hours to obtain the sodium-ion battery layered oxide cathode material NaNi. 0.4 Fe 0.2 Mn 0.4 O2;
[0040] 7) Dissolve 0.0057g of selenium powder and 0.0086g of tin powder in ethanol, and add 2.0000g of the prepared sodium-ion battery layered oxide cathode material NaNi. 0.4 Fe 0.2 Mn 0.4 O2(SnSe and NaNi) 0.4 Fe 0.2 Mn 0.4 The O2 mass ratio is approximately 1:140, and it is slowly evaporated at 80℃ to form a powder.
[0041] 8) The obtained powder is vacuum dried and crushed at 120℃, heated to 450℃ at a heating rate of 1-5℃ / min in an argon or argon-hydrogen atmosphere (H2 concentration of 5%), and then calcined at 450℃ for 2 hours to obtain a SnSe-coated surface-modified sodium-ion battery layered oxide cathode material, namely the SnSe surface-modified O3 type layered oxide cathode material.
[0042] like Figure 1 It can be seen that the peak positions of the sodium-ion battery layered oxide cathode material after SnSe coating surface modification are basically the same as those of the unmodified sodium-ion battery layered oxide cathode material. This means that the SnSe coating surface modification did not alter the structure of the sodium-ion battery layered oxide cathode material. The SEM images of the SnSe-coated surface-modified sodium-ion battery layered oxide cathode material and the unmodified sodium-ion battery layered oxide cathode material obtained in this example are shown below. Figure 2 and Figure 3 As shown, by Figure 2 and Figure 3 The comparison shows that the SnSe coating is uniformly coated on the surface of the layered oxide cathode material of sodium-ion batteries.
[0043] The SnSe-coated surface-modified sodium-ion battery layered oxide cathode material (or sodium-ion battery layered oxide cathode material) prepared in this embodiment was mixed with conductive carbon black Super P and binder PVDF in a mass ratio of 8:1:1. N-methylpyrrolidone was added and stirred until homogeneous. The resulting slurry was coated onto current collector aluminum foil and dried at 120°C to obtain a cathode sheet. Using a sodium metal sheet as the anode, glass fiber as the separator, and NaClO4 as the electrolyte, a CR2032 type button cell was assembled in an argon-filled glove box. The resulting cell was subjected to charge-discharge cycle testing at a rate of 1.0C. The test results are as follows: Figures 4-5 As shown.
[0044] in Figure 4 The graph shows the initial charge-discharge curves for voltages of 2.0-4.0V. Since the coating material cannot provide additional capacity, the initial capacity of the battery made with SnSe-coated surface-modified sodium-ion battery layered oxide cathode material is slightly lower, but its initial coulombic efficiency of 99.56% is higher than that of the sodium-ion battery layered oxide cathode material of 98.90%.
[0045] The resulting cycle curve is as follows Figure 5As shown, the battery made from the SnSe surface-modified and surface-doped sodium-ion battery layered oxide cathode material prepared in this embodiment has an initial discharge specific capacity of 118.97 mAh / g. After 300 cycles, its discharge specific capacity is 80.10 mAh / g, with a cycle retention rate of approximately 73.94%. In contrast, the battery made from the sodium-ion battery layered oxide cathode material has an initial discharge specific capacity of 123.17 mAh / g. After 300 cycles, its discharge specific capacity is 32.21 mAh / g, with a cycle retention rate of only 30.65%. From the above results, it can be seen that the SnSe-coated surface-modified sodium-ion battery layered oxide cathode material has a stable structure and good cycle stability.
[0046] Example 2:
[0047] This embodiment prepares a SnSe surface-modified O3-type layered oxide cathode material with the chemical formula NaNi. 0.4 Fe 0.2 Mn 0.4 O2 is used as the layered oxide cathode material for sodium-ion batteries as the matrix, and a synergistic strategy of surface coating and elemental doping is employed to achieve the desired effect on the NaNi matrix. 0.4 Fe 0.2 Mn 0.4 A uniform SnSe coating layer is constructed on the O2 surface. The specific preparation method includes the following steps:
[0048] 1) According to the chemical formula of sodium-ion battery cathode material NaNi 0.4 Fe 0.2 Mn 0.4 To prepare a 1 mol / L salt solution, 756.1 g of nickel nitrate hexahydrate, 525.2 g of ferric nitrate nonahydrate, and 632.5 g of manganese nitrate tetrahydrate were weighed and dissolved in 6 L of deionized water, according to the molar ratio of Ni:Fe:Mn = 0.4:0.2:0.4 shown in O2.
[0049] 2) Dissolve 500g NaOH in 2500mL of deionized water to prepare a NaOH solution with a concentration of approximately 5mol / L, and then mix it with 250mL of ammonia solution with a volume concentration of 25% to prepare a mixed alkaline solution;
[0050] 3) Add the mixed alkaline solution obtained in step 2) into the reaction vessel using a peristaltic pump, and control the pH value in the reaction vessel to 10;
[0051] 4) The nickel salt solution, iron salt solution and manganese salt solution prepared in step 1) are added to the reaction vessel at a constant speed using a peristaltic pump. The pH value is controlled at 9 and the temperature is controlled at 60°C throughout the process.
[0052] 5) After the nickel salt solution, iron salt solution, and manganese salt solution have been added, let it stand for 10 hours to age. Then, filter, wash, and dry the precipitate to obtain the dried precipitate Ni. 0.4 Fe 0.2 Mn 0.4 (OH)2;
[0053] 6) Weigh 1.6239 g of dried Ni precipitate at a molar ratio of 1:1.05. 0.4 Fe 0.2 Mn 0.4 (OH)₂ and 0.7524 g of sodium hydroxide are mixed evenly, and 0.05 g of sodium chloride flux is added. In an air atmosphere, the mixture is first heated to 500 °C at a heating rate of 1-5 °C / min, then pre-calcined at 500 °C for 4 hours, then heated to 900 °C at a heating rate of 1-5 °C / min, and then calcined at 900 °C for 20 hours. Finally, the mixture is cooled to 500 °C at a cooling rate of 5 °C / min and held at that temperature for 3 hours to obtain the sodium-ion battery layered oxide cathode material NaNi. 0.4 Fe 0.2 Mn 0.4 O2;
[0054] 7) Dissolve 0.0040g of selenium powder and 0.0060g of tin powder in ethanol, and add 2.0000g of the prepared sodium-ion battery layered oxide cathode material NaNi. 0.4 Fe 0.2 Mn 0.4 O2(SnSe and NaNi) 0.4 Fe 0.2 Mn 0.4 The O2 mass ratio is approximately 1:200, and it is slowly evaporated at 80℃ to form a powder.
[0055] 8) The obtained powder is vacuum dried and crushed at 120℃, heated to 350℃ at a heating rate of 1-5℃ / min in an argon or argon-hydrogen atmosphere (H2 concentration of 5%), and then calcined at 350℃ for 1 hour to obtain a SnSe-coated surface-modified sodium-ion battery layered oxide cathode material, namely the SnSe surface-modified O3-type layered oxide cathode material.
[0056] The structures of the matrix and product in this embodiment are consistent with those in Example 1, and related test spectra and analyses are omitted here.
[0057] Example 3:
[0058] This embodiment prepares a SnSe2 surface-modified O3-type layered oxide cathode material with the chemical formula NaNi. 0.4 Fe 0.2 Mn 0.4O2 is used as the layered oxide cathode material for sodium-ion batteries as the matrix, and a synergistic strategy of surface coating and elemental doping is employed to achieve the desired effect on the NaNi matrix. 0.4 Fe 0.2 Mn 0.4 To construct a uniform SnSe2 coating layer on the O2 surface, the specific preparation method includes the following steps:
[0059] 1) According to the chemical formula of the layered oxide cathode material of sodium-ion batteries, NaNi 0.4 Fe 0.2 Mn 0.4 The molar ratio of Ni:Fe:Mn = 0.4:0.2:0.4 shown in O2 was prepared by weighing out 604.0g of nickel acetate dihydrate, 545.8g of ferric acetate hexahydrate and 813.1g of manganese acetate tetrahydrate and dissolving them in 12L of deionized water to prepare a salt solution with a concentration of 0.5mol / L.
[0060] 2) Dissolve 200g of NaOH in 2500mL of deionized water to prepare a NaOH solution with a concentration of approximately 2mol / L, and then mix it with 250mL of urea with a mass concentration of 25% to prepare a mixed alkaline solution;
[0061] 3) Add the mixed alkaline solution obtained in step 2) into the reaction vessel using a peristaltic pump, and control the pH value in the reaction vessel to 10;
[0062] 4) The nickel salt solution, iron salt solution and manganese salt solution prepared in step 1) are added to the reaction vessel at a constant rate using a peristaltic pump. The pH value is controlled at 10.5 and the temperature is controlled at 50°C throughout the process.
[0063] 5) After the nickel salt solution, iron salt solution, and manganese salt solution have been added, let it stand for 8 hours to age. Then, filter, wash, and dry the precipitate to obtain the dried precipitate Ni. 0.4 Fe 0.2 Mn 0.4 (OH)2;
[0064] 6) Weigh 1.6239 g of dried Ni precipitate at a molar ratio of 1:1.03. 0.4 Fe 0.2 Mn 0.4 (OH)₂ and 0.9780 g of sodium carbonate are mixed evenly, and 0.05 g of sodium nitrate flux is added. In an air atmosphere, the mixture is first heated to 500 °C at a rate of 1-5 °C / min, then pre-calcined at 500 °C for 6 hours, then heated to 950 °C at a rate of 1-5 °C / min, and calcined at 950 °C for 15 hours. Finally, the mixture is cooled to 500 °C at a rate of 1-5 °C / min and held at 500 °C for 3 hours to obtain the sodium-ion battery layered oxide cathode material NaNi. 0.4 Fe0.2 Mn 0.4 O2;
[0065] 7) Dissolve 0.0320g of selenium dioxide and 0.0217g of tin dioxide in ethanol, and add 2.0000g of the prepared sodium-ion battery layered oxide cathode material NaNi. 0.4 Fe 0.2 Mn 0.4 O2(SnSe2 and NaNi) 0.4 Fe 0.2 Mn 0.4 The O2 mass ratio is approximately 1:50, and it is slowly evaporated at 80℃ to form a powder.
[0066] 8) The obtained powder is vacuum dried and crushed at 120℃, heated to 450℃ at a heating rate of 1-5℃ / min in an argon or argon-hydrogen atmosphere (hydrogen concentration of 5%), and then calcined at 450℃ for 0.5 hours to obtain a SnSe2-coated surface-modified sodium-ion battery layered oxide cathode material, namely the SnSe2-coated surface-modified O3-type layered oxide cathode material.
[0067] The structures of the matrix and product in this embodiment are similar to those in Example 1, and related test spectra and analyses are omitted here.
[0068] Example 4:
[0069] This embodiment prepares a Sn4Se5 surface-modified O3-type layered oxide cathode material with the chemical formula NaNi. 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 is used as the layered oxide cathode material for sodium-ion batteries as the matrix, and a synergistic strategy of surface coating and elemental doping is employed to achieve the desired effect on the NaNi matrix. 1 / 3 Fe 1 / 3 Mn 1 / 3 A uniform Sn4Se5 coating layer is constructed on the O2 surface. The specific preparation method includes the following steps:
[0070] 1) According to the chemical formula of sodium-ion battery cathode material NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 To prepare a 2mol / L salt solution, 530.5g of nickel sulfate hexahydrate, 556.5g of ferrous sulfate heptahydrate, and 338.0g of manganese sulfate monohydrate were weighed and dissolved in 3L of deionized water to achieve the molar ratio of Ni:Fe:Mn = 1 / 3:1 / 3:1 / 3 shown in O2.
[0071] 2) Dissolve 200g of NaOH in 2500mL of deionized water to prepare a NaOH solution with a concentration of approximately 2mol / L, and then mix it with 250mL of urea with a mass concentration of 27% to prepare a mixed alkaline solution;
[0072] 3) Add the mixed alkaline solution obtained in step 2) into the reaction vessel using a peristaltic pump, and control the pH value in the reaction vessel to 9;
[0073] 4) The nickel salt solution, iron salt solution and manganese salt solution prepared in step 1) are added to the reaction vessel at a constant rate using a peristaltic pump. The pH value is controlled at 10.5 and the temperature is controlled at 50°C throughout the process.
[0074] 5) After the nickel salt solution, iron salt solution, and manganese salt solution have been added, let it stand for 5 hours to age. Then, filter, wash, and dry the precipitate to obtain the dried precipitate Ni. 1 / 3 Fe 1 / 3 Mn 1 / 3 (OH)2;
[0075] 6) Weigh 1.6134 g of dried Ni precipitate at a molar ratio of 1:1.04. 1 / 3 Fe 1 / 3 Mn 1 / 3 (OH)₂ and 0.9888g of sodium carbonate are mixed evenly, and 0.05g of sodium nitrate flux is added. In an air atmosphere, the mixture is first heated to 450℃ at a rate of 1-5℃ / min, then pre-calcined at 450℃ for 5 hours, followed by a further heating to 950℃ at a rate of 1-5℃ / min, and then calcined at 950℃ for 14 hours. Finally, the mixture is cooled to 600℃ at a rate of 1-5℃ / min and held at 600℃ for 6 hours to obtain the sodium-ion battery layered oxide cathode material NaNi. 1 / 3 Fe 1 / 3 Mn 1 / 3 O2;
[0076] 7) Dissolve 0.0118g of selenium powder and 0.0142g of tin powder in ethanol, and add 2.0000g of the prepared sodium-ion battery layered oxide cathode material NaNi. 1 / 3 Fe 1 / 3 Mn 1 / 3 O2(Sn4Se5 and NaNi) 1 / 3 Fe 1 / 3 Mn 1 / 3 The O2 mass ratio is approximately 1:77, and it is slowly evaporated at 90℃ to form a powder.
[0077] 8) The obtained powder is vacuum dried and crushed at 80℃, heated to 300℃ at a heating rate of 1-5℃ / min in an argon or argon-hydrogen atmosphere (concentration of 5%), and then calcined at 300℃ for 2 hours to obtain a Sn4Se5 coated surface modified sodium-ion battery layered oxide cathode material, namely the Sn4Se5 surface modified O3 type layered oxide cathode material.
[0078] The structures of the matrix and product in this embodiment are similar to those in Example 1, and related test spectra and analyses are omitted here.
[0079] Example 5:
[0080] This embodiment prepares a SnSe2 surface-modified O3-type layered oxide cathode material with the chemical formula NaNi. 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 is used as the layered oxide cathode material for sodium-ion batteries as the matrix, and a synergistic strategy of surface coating and elemental doping is employed to achieve the desired effect on the NaNi matrix. 1 / 3 Fe 1 / 3 Mn 1 / 3 To construct a uniform SnSe2 coating layer on the O2 surface, the specific preparation method includes the following steps:
[0081] 1) According to the chemical formula of sodium-ion battery cathode material NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 The molar ratio of Ni:Fe:Mn = 1 / 3:1 / 3:1 / 3 shown in O2 was determined by weighing out 394.0g of nickel acetate dihydrate, 680.0g of ferric acetate hexahydrate and 503.0g of manganese acetate tetrahydrate, and dissolving them in 3L of deionized water to prepare a salt solution with a concentration of 2mol / L.
[0082] 2) Dissolve 280g of KOH in 2500mL of deionized water to prepare a KOH solution with a concentration of approximately 2mol / L, and then mix it with 250mL of urea with a mass concentration of 28% to prepare a mixed alkaline solution;
[0083] 3) Add the mixed alkaline solution obtained in step 2) into the reaction vessel using a peristaltic pump, and control the pH value in the reaction vessel to 12;
[0084] 4) Add the nickel salt solution, iron salt solution and manganese salt solution prepared in step 1) into the reaction vessel at a constant speed using a peristaltic pump. During the entire process, control the pH value at 12 and the temperature at 40℃.
[0085] 5) After the nickel salt solution, iron salt solution, and manganese salt solution have been added, let it stand for 3 hours to age. Then, filter, wash, and dry the precipitate to obtain the dried precipitate Ni. 1 / 3 Fe 1 / 3Mn 1 / 3 (OH)2;
[0086] 6) Weigh 1.6134 g of dried Ni precipitate at a molar ratio of 1:1.03. 1 / 3 Fe 1 / 3 Mn 1 / 3 (OH)₂ and 1.5158 g of sodium acetate were mixed evenly, and 0.05 g of sodium borohydride flux was added. In an air atmosphere, the mixture was first heated to 350 °C at a rate of 1-5 °C / min, then pre-calcined at 350 °C for 6 hours, then heated to 950 °C at a rate of 1-5 °C / min, and then calcined at 800 °C for 20 hours. Finally, the mixture was cooled to 350 °C at a rate of 1-5 °C / min and held at 350 °C for 5 hours to obtain the sodium-ion battery layered oxide cathode material NaNi. 1 / 3 Fe 1 / 3 Mn 1 / 3 O2;
[0087] 7) Dissolve 0.0235g of selenium powder and 0.0390g of tin tetrachloride in ethanol, and add 2.0000g of the prepared sodium-ion battery layered oxide cathode material NaNi. 1 / 3 Fe 1 / 3 Mn 1 / 3 O2(SnSe2 and NaNi) 1 / 3 Fe 1 / 3 Mn 1 / 3 The O2 mass ratio is approximately 1:85, and it is slowly evaporated at 100℃ to form a powder.
[0088] 8) The obtained powder is vacuum dried and crushed at 100℃, heated to 500℃ at a heating rate of 1-5℃ / min in an argon or argon-hydrogen atmosphere (H2 concentration of 5%), and then calcined at 500℃ for 6 hours to obtain a SnSe2-coated surface-modified sodium-ion battery layered oxide cathode material, namely the SnSe2-coated surface-modified O3-type layered oxide cathode material.
[0089] The structures of the matrix and product in this embodiment are similar to those in Example 1, and related test spectra and analyses are omitted here.
[0090] The above description is a detailed description of the preferred embodiments of the present invention. However, the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the technical spirit of the present invention should fall within the patent scope covered by the present invention.
Claims
1. A Sn x Se y Surface-modified O3-type layered oxide cathode material, characterized in that, Through a synergistic strategy of surface coating and elemental doping, in the NaNi matrix a Fe b Mn z O2 surface builds uniform Sn x Se y Coating layer, Sn x Se y With NaNi a Fe b Mn z The mass ratio of O2 is 1:50-200; Sn x Se y In the given condition, 0.5 ≤ x:y ≤ 1; NaNi a Fe b Mn z In O2, 0.2≤a≤0.4, 0.2≤b≤0.4, and 0.2≤z≤0.
4.
2. A Sn according to claim 1 x Se y Surface-modified O3-type layered oxide cathode material, characterized in that, Includes the following steps: 1) Based on the chemical formula of the matrix NaNi a Fe b Mn z The molar ratio of Ni:Fe:Mn in O2 is a:b:z. Weigh out nickel salt, iron salt and manganese salt, and then dissolve nickel salt, iron salt and manganese salt in deionized water to prepare nickel salt solution, iron salt solution and manganese salt solution with molar concentration of 0.5-2 mol / L respectively. 2) Mix the alkali solution and the complexing agent to prepare a mixed alkali solution; 3) Add the mixed alkaline solution obtained in step 2) into the reaction vessel and control the pH value between 9 and 12; 4) The nickel salt solution, iron salt solution and manganese salt solution prepared in step 1) are added to the reaction vessel at a uniform rate. The pH value is 9-12 and the temperature is 40-60℃ throughout the process. 5) After adding the nickel salt solution, iron salt solution and manganese salt solution, let it stand for 3-12 hours, then filter, wash and dry the precipitate; 6) The dried precipitate is uniformly mixed with sodium salt, flux is added, and sintered in air atmosphere to obtain the matrix NaN. a Fe b Mn z O2; 7) Dissolve the selenium source and tin source in ethanol, and then add the NaNi matrix obtained in step 6). a Fe b Mn z O2 is evaporated at 80-100℃ to form powder; 8) The powder obtained in step 7) is vacuum dried and crushed at 80-120℃, and then calcined in an argon or argon-hydrogen mixed atmosphere to obtain the Sn. x Se y Surface-modified O3-type layered oxide cathode material.
3. The preparation method according to claim 2, characterized in that, In step 1), the nickel salt is one or more of nickel sulfate, nickel nitrate, and nickel acetate; the iron salt is one or more of ferrous sulfate, ferric nitrate, and ferric acetate; and the manganese salt is one or more of manganese sulfate, manganese nitrate, and manganese acetate.
4. The preparation method according to claim 2, characterized in that, In step 2), the alkaline solution is one or both of sodium hydroxide solution and potassium hydroxide solution, and the molar concentration of the alkaline solution is 2-10 mol / L; the complexing agent is one or both of ammonia water and urea solution, and the mass concentration of the complexing agent is 25%-28%; the volume ratio of the alkaline solution to the complexing agent is 10:
1.
5. The preparation method according to claim 2, characterized in that, The sodium salt mentioned in step 6) is one or more of sodium hydroxide, sodium carbonate, and sodium acetate; the flux is one or more of sodium chloride, sodium nitrate, and sodium metaborate.
6. The preparation method according to claim 2, characterized in that, In step 6), the molar ratio of the precipitate to the sodium salt is 1:1.03-1:1.
05.
7. The preparation method according to claim 2, characterized in that, The specific conditions and steps for sintering in step 6) include: first, heating to 350-500℃ at a heating rate of 1-5℃ / min and holding for 4-6 hours for pre-firing; then heating to 800-950℃ at a heating rate of 1-5℃ / min and holding for 14-20 hours for calcination.
8. The method according to claim 2, characterized in that, The selenium source mentioned in step 7) is one or more of selenium powder and selenium dioxide, and the tin source is one or more of tin powder, tin dioxide and tin tetrachloride.
9. The method according to claim 2, characterized in that, The calcination conditions in step 8) are: heating to 300-500℃ at a heating rate of 1-5℃ / min and holding at that temperature for 0.5-6 hours.