Method for inhibiting iron ion migration of Na0. 67Fe0. 5Mn0. 5O2 material as well as product and application thereof

Abstract

The invention discloses a method for inhibiting iron ion migration of a Na < 0.67 > Fe < 0.5 > Mn < 0.5 > O < 2 > material and a product and application of the product, and belongs to the technical field of electrode materials. Zr ions are used for partially replacing iron ions in the Na < 0.67 > Fe < 0.5 > Mn < 0.5 > O < 2 > material. Zirconium ions are used for partially replacing iron ions in the Na < 0.67 > Fe < 0.5 > Mn < 0.5 > O < 2 > material, so that migration of the iron ions to a sodium layer is inhibited, the problem of rapid capacity attenuation of an existing Na < 0.67 > Fe < 0.5 > Mn < 0.5 > O < 2 > material in circulation is solved, the sodium ion diffusion rate of the material is increased, and the circulation stability of the material is improved. The method provided by the invention is simple and convenient to popularize and apply.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electrode materials, and particularly relates to a method for inhibiting iron ion migration in Na 0.67 Fe 0.5 Mn 0.5 O2 material and products and applications thereof. BACKGROUND

[0002] P2 phase iron / manganese-based layered oxides have the advantages of low cost, rich reserves, high theoretical capacity, and become potential candidate materials for sodium-ion batteries (SIB). However, during the electrochemical process, the migration of iron ions to the sodium layer is the main reason for the rapid capacity decay and structural degradation of Na 0.67 Fe 0.5 Mn 0.5 O2 material, and the aggregation of iron ions and Jahn-Teller effect are the key factors triggering iron migration. Therefore, the development of high-performance sodium-ion battery cathode materials depends on finding effective strategies to effectively inhibit iron ion migration.

[0003] At present, researchers introduce low-valence elements into the crystal structure to alleviate the irreversible phase transition and Jahn-Teller effect, and improve the cycle stability of iron-manganese-based layered oxides, however, the obtained material still has the disadvantage of P2-Z phase transition and the disadvantage of iron ion migration to the sodium layer, resulting in poor sodium ion diffusion rate and structural defects due to stress accumulation during the cycle process.

[0004] Therefore, how to further solve the above problems and provide a method for effectively inhibiting iron ion migration in Na 0.67 Fe 0.5 Mn 0.5 O2 material is a technical problem that needs to be solved by those skilled in the art. SUMMARY

[0005] To solve the above technical problems, the present application provides a method for inhibiting iron ion migration in Na 0.67 Fe 0.5 Mn 0.5 O2 material and products and applications thereof.

[0006] To achieve the above purpose, the present application provides the following technical solutions: A method for inhibiting iron ion migration in Na 0.67 Fe 0.5 Mn 0.5 O2 material, wherein Zr ions are used to partially replace iron ions in the Na 0.67 Fe 0.5 Mn 0.5 O2 material, to obtain a Zr-doped iron-manganese-based layered metal oxide electrode material Na 0.67Fe 0.5-x Zr x Mn 0.5 O2; wherein, the x=0.03-0.1.

[0007] Preferably, the method comprises the following steps: dissolving the manganese source, the iron source, the zirconium source and the urea in a solvent, mixing the obtained solid product with a sodium source after hydrothermal reaction, and calcining the mixture, cooling and grinding after the calcination, to obtain the Zr-doped Na 0.67 Fe 0.5 Mn 0.5 O2 material and partially replace the iron ions therein, to obtain the Zr-doped iron-manganese-based layered metal oxide electrode material Na 0.67 Fe 0.5-x Zr x Mn 0.5 O2.

[0008] Beneficial effects: the present application partially replaces the iron ions in the Na 0.67 Fe 0.5 Mn 0.5 O2 material with zirconium ions, so as to inhibit the migration thereof. 0.67 Fe 0.5 Mn 0.5 O2 material in the electrochemical process, and can also expand the sodium layer spacing, which is more conducive to the deintercalation of sodium ions, thereby improving the specific capacity and cycle stability of the material.

[0009] More specifically, the present application partially replaces the iron ions in the Na 0.67 Fe 0.5 Mn 0.5 O2 material with zirconium ions, which can effectively inhibit the oxidation of Fe 3+ to Fe 4+ in the charging process, reduce the number of Fe 4+ O6, hinder the migration of iron ions to the sodium layer, and prevent the structural collapse in the charging and discharging process. In addition, the doping of zirconium ions increases the interplanar spacing and adjusts the relative thickness of the NaO2 and MO2 layers, which can significantly enhance the cycle stability and rate performance of the material, improve the diffusion rate of sodium ions in the electrochemical process, and provide a new perspective for the research of iron ion migration and P2-phase iron / manganese-based layered oxide materials.

[0010] More preferably, the molar ratio of the manganese source, the iron source, the zirconium source and the sodium source is 0.95:1:(0.03-0.07), more preferably 0.95:1:0.03, 0.95:1:0.05, 0.95:1:0.07.

[0011] Preferably, the manganese source is manganese nitrate and / or manganese chloride.

[0012] Preferably, the iron source is iron nitrate and / or iron chloride.

[0013] Preferably, the zirconium source is zirconium nitrate and / or zirconium acetate.

[0014] Preferably, the sodium source is sodium carbonate.

[0015] More preferably, the solvent is a mixture of ethylene glycol and deionized water in a volume ratio of 2:1.

[0016] Beneficial effects: The deionized water is used to dissolve the iron source, the manganese source, the zirconium source and the sodium source, and the ethylene glycol is used to improve the regularity of the crystal structure of the material in the formation process, thereby improving the crystallinity and purity of the product. The urea is added as a precipitant in the present application, which is used to avoid introducing other impurities and to make the sodium carbonate more stable in the air at room temperature. In the reaction process, the sodium carbonate reacts with the iron source, the manganese source and the zirconium source to form a metal salt precipitate.

[0017] More preferably, the mixing and dissolving is carried out at a constant temperature of 35℃ for 2-5h.

[0018] The rotation speed of the constant temperature stirring is 400-500rpm.

[0019] More preferably, the mixing of the solid product and the sodium source is carried out by mixing and grinding the solid product and the sodium source in a grinder for 1-2h.

[0020] Preferably, the temperature of the hydrothermal reaction is 130-160℃, and the time is 12h.

[0021] More preferably, the hydrothermal reaction further includes centrifugation and drying.

[0022] The centrifugation is carried out at a rotation speed of 5000-8000rpm using deionized water and anhydrous ethanol alternately. The drying is carried out at a temperature of 60-80℃ for 12h.

[0023] Preferably, the calcination is carried out at a temperature of 850-1000℃ for 15h.

[0024] A Zr-doped iron-manganese-based layered metal oxide electrode material prepared by the above method.

[0025] Application of a Zr-doped iron-manganese-based layered metal oxide electrode material in a sodium ion battery positive electrode material.

[0026] Compared with the prior art, the application has the following advantages and technical effects: The application combines a solvothermal method and a high-temperature solid-phase method to prepare a Zr-doped iron-manganese-based layered metal oxide electrode material. 0.67 Fe 0.5 Mn 0.5 O2 material, and further suppresses the migration of iron ions to the sodium layer, thereby solving the problem of rapid capacity decay of the existing Na 0.67 Fe 0.5 Mn 0.5 O2 material in the cycle, enhancing the sodium ion diffusion rate and cycle stability of the material. The method provided by the application is simple and convenient to popularize and apply. BRIEF DESCRIPTION OF DRAWINGS

[0027] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and serve as an explanation of the illustrative embodiments of the present application and their description, and do not constitute an improper limitation of the present application. In the drawings: Figure 1 XRD patterns of the materials with different Zr doping amounts obtained in Examples 1-3 and Comparative Example 1; Figure 2 XRD patterns of the products obtained in Example 4 and Example 5; Figure 3 Elemental distribution map of the Na 0.67 Fe 0.45 Zr 0.05 Mn 0.5 O2 material obtained in Example 1; Figure 4 SEM and TEM photos of the Na 0.67 Fe 0.45 Zr 0.05 Mn 0.5 O2 material obtained in Example 1; Wherein, (a) is a SEM photo; (b) is a TEM photo; and (c) is an enlarged view of the red box part in (b); Figure 5 SEM photo of the Na 0.67 Fe 0.5 Mn 0.5 O2 material obtained in Comparative Example 1; Figure 6 XRD patterns of the products obtained in Example 1 and Comparative Example 1; Figure 7The XRD refinement figure of the product obtained in Example 1 and Comparative Example 1; Figure 8 The first charge-discharge comparison figure of the product obtained in Example 1 and Comparative Example 1; Figure 9 The rate comparison figure of the product obtained in Example 1 and Comparative Example 1; Figure 10 The cycle specific capacity of the product obtained in Example 1 and Comparative Example 1 at 0.5C rate; Figure 11 The cycle specific capacity of the product obtained in Example 1 and Comparative Example 1 at 1C rate; Figure 12 The EIS comparison figure of the product obtained in Example 1 and Comparative Example 1 after 100 cycles; Figure 13 The XRD figure of Na 0.67 Fe 0.45 Ce 0.05 Mn 0.5 O2 material obtained in Comparative Example 2; Figure 14 The valence change of iron ions before and after Zr doping in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0029] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0030] The embodiments of the present application provide a method for inhibiting the migration of iron ions in Na 0.67 Fe 0.5 Mn 0.5 O2 material, wherein Zr ions are used to partially replace the iron ions in the Na 0.67 Fe 0.5 Mn 0.5 O2 material, to obtain a Zr-doped iron-manganese-based layered metal oxide electrode material Na 0.67 Fe 0.5-x Zr x Mn 0.5 O2. Wherein, the x=0.03-0.1.

[0031] In a preferred embodiment, the method comprises the following steps: The manganese source, iron source, zirconium source, and urea are mixed and dissolved in a solvent, and after hydrothermal reaction, the obtained solid product is mixed with a sodium source and calcined, and after calcination, the product is cooled and ground to obtain the Zr-doped Na 0.67 Fe 0.5 Mn 0.5 O2material and partially replace the iron ions therein to obtain a Zr-doped iron-manganese-based layered metal oxide electrode material Na 0.67 Fe 0.5-x Zr x Mn 0.5 O2.

[0032] In a more preferred embodiment, the molar ratio of the manganese source, iron source, zirconium source, and sodium source is 0.95:1:(0.03-0.07), more preferably 0.95:1:0.03, 0.95:1:0.05, or 0.95:1:0.07.

[0033] In a preferred embodiment, the manganese source is manganese nitrate and / or manganese chloride.

[0034] In a preferred embodiment, the iron source is iron nitrate and / or iron chloride.

[0035] In a preferred embodiment, the zirconium source is zirconium nitrate and / or zirconium acetate.

[0036] In a preferred embodiment, the sodium source is sodium carbonate.

[0037] In a more preferred embodiment, the solvent is a mixture of ethylene glycol and deionized water in a volume ratio of 2:1.

[0038] In a more preferred embodiment, the mixing and dissolving is carried out by constant temperature stirring at 35°C for 2h.

[0039] In a more preferred embodiment, the mixing of the solid product with the sodium source is carried out by mixing and grinding the solid product with the sodium source during grinding.

[0040] In a preferred embodiment, the hydrothermal reaction is carried out at a temperature of 130-160°C for 12h.

[0041] In a more preferred embodiment, the hydrothermal reaction further comprises centrifugation and drying.

[0042] The centrifugation is carried out at a speed of 5000-8000rpm using deionized water and anhydrous ethanol alternately; The drying is carried out at a temperature of 60-80°C for 12h.

[0043] In a preferred embodiment, the temperature of the calcination is 850-1000℃, and the time is 15h.

[0044] The application also provides a Zr-doped iron-manganese-based layered metal oxide electrode material prepared by the method.

[0045] The application also provides an application of the Zr-doped iron-manganese-based layered metal oxide electrode material in a sodium-ion battery positive electrode material.

[0046] Unless otherwise specified, the raw materials in the embodiments of the application are purchased through a commercial channel; Unless otherwise specified, the room temperature or normal temperature in the embodiments of the application refers to 25±3℃.

[0047] Embodiment 1 A method for inhibiting the migration of iron ions in a Na 0.67 Fe 0.5 Mn 0.5 O2 material, comprising the following steps: At 35℃, 1.255g of manganese nitrate tetrahydrate, 1.818g of iron nitrate nonahydrate and 0.0.2147g of zirconium nitrate pentahydrate, 1.201g of urea were added into a mixed solution of 40ml of ethylene glycol and 20ml of deionized water, and stirred at 35℃ for 2h at a rotation speed of 400rpm to make them fully dissolved and uniformly mixed. Then the obtained mixed solution was placed into a high-pressure reaction kettle and reacted at 150℃ for 12h. After the reaction, the precipitate product obtained after centrifugation was washed and centrifuged alternately with deionized water and anhydrous ethanol at a rotation speed of 5000rpm, and then dried in a vacuum drying box at 60℃ for 12h. Then 0.355g of sodium carbonate was mixed and ground in a mortar for 1h, and then placed in a tube furnace for calcination at 900℃ for 15h. After calcination, the sample was naturally cooled and ground to obtain a Zr-doped Na 0.67 Fe 0.5 Mn 0.5 O2 material, and the Na 0.67 Fe 0.45 Zr 0.05 Mn 0.5 O2 material (after Zr doping) was placed in a glove box for storage.

[0048] Embodiment 2 A method for inhibiting the migration of iron ions in a Na 0.67 Fe 0.5 Mn 0.5 O2 material, which is different from embodiment 1 in that the substitution amount of Zr ions is changed, and specifically comprising the following steps: Mn(NO3)2.4H2O 1.255 g, Fe(NO3)3.9H2O 1.899 g, Zr(NO3)2.5H2O 0.1288 g, C(O)NH2 1.201 g were added into 40 mL ethylene glycol and 20 mL deionized water mixed solution, and stirred at 35 °C for 2 h at 400 rpm to make them fully dissolved and uniformly mixed. Then the mixed solution was put into an autoclave and reacted at 150 °C for 12 h. After reaction, the product was washed and centrifuged with deionized water and anhydrous ethanol alternately at 5000 rpm. The precipitate obtained after centrifugation was dried in a vacuum drying box at 60 °C for 12 h. Then 0.355 g of Na2CO3 was added and ground in a mortar for 1 h, and then calcined in a tube furnace at 900 °C for 15 h. After calcination, it was naturally cooled and ground to obtain Zr-doped Na 0.67 Fe 0.5 Mn 0.5 O2material, to obtain Na 0.67 Fe 0.47 Zr 0.03 Mn 0.5 O2material, which was stored in a glove box.

[0049] Example 3 A method for inhibiting the migration of iron ions in a Na 0.67 Fe 0.5 Mn 0.5 O2material, which was stored in a glove box. Mn(NO3)2.4H2O 1.255 g, Fe(NO3)3.9H2O 1.737 g, Zr(NO3)2.5H2O 0.3005 g, C(O)NH2 1.201 g were added into 40 mL ethylene glycol and 20 mL deionized water mixed solution, and stirred at 35 °C for 2 h at 400 rpm to make them fully dissolved and uniformly mixed. Then the mixed solution was put into an autoclave and reacted at 150 °C for 12 h. After reaction, the product was washed and centrifuged with deionized water and anhydrous ethanol alternately at 5000 rpm. The precipitate obtained after centrifugation was dried in a vacuum drying box at 60 °C for 12 h. Then 0.355 g of Na2CO3 was added and ground in a mortar for 1 h, and then calcined in a tube furnace at 900 °C for 15 h. After calcination, it was naturally cooled and ground to obtain Zr-doped Na 0.67 Fe 0.5 Mn 0.5 O2material, to obtain Na 0.67 Fe 0.43 Zr 0.07 Mn 0.5 O2material, which was stored in a glove box.

[0050] Example 4 A method for inhibiting the migration of iron ions in a Na 0.67 Fe 0.5 Mn0.5 A method for migration of iron ions in O2 material, comprising the following steps: At 35°C, 0.99 g of manganese chloride tetrahydrate, 1.081 g of iron chloride hexahydrate and 0.2974 g of zirconium acetate tetrahydrate, 1.201 g of urea were added into a mixed solution of 40 ml of ethylene glycol and 20 ml of deionized water, and stirred at 35°C for 3 h at a rotation speed of 500 rpm to make them fully dissolved and uniformly mixed, and then the obtained mixed solution was put into a high-pressure reaction kettle to react at 140°C for 12 h, after the reaction, the precipitate obtained after centrifugation was washed with deionized water and anhydrous ethanol alternately at a rotation speed of 5000 rpm, and then dried in a vacuum drying box at 80°C for 12 h, and then mixed with 0.355 g of sodium carbonate in a mortar and ground for 1 h, and then calcined in a tube furnace at 850°C for 15 h, and then naturally cooled and ground to obtain Zr-doped Na 0.67 Fe 0.5 Mn 0.5 O2 material, to obtain Na 0.67 Fe 0.4 Zr 0.1 Mn 0.5 O2 material, which was stored in a glove box.

[0051] Example 5 A method for migration of iron ions in Na 0.67 Fe 0.5 Mn 0.5 O2 material, comprising the following steps: At 35°C, 0.99 g of manganese chloride tetrahydrate, 1.081 g of iron chloride hexahydrate and 0.2974 g of zirconium acetate tetrahydrate, 1.201 g of urea were added into a mixed solution of 40 ml of ethylene glycol and 20 ml of deionized water, and stirred at 35°C for 3 h at a rotation speed of 500 rpm to make them fully dissolved and uniformly mixed, and then the obtained mixed solution was put into a high-pressure reaction kettle to react at 140°C for 12 h, after the reaction, the precipitate obtained after centrifugation was washed with deionized water and anhydrous ethanol alternately at a rotation speed of 5000 rpm, and then dried in a vacuum drying box at 80°C for 12 h, and then mixed with 0.355 g of sodium carbonate in a mortar and ground for 1 h, and then calcined in a tube furnace at 850°C for 15 h, and then naturally cooled and ground to obtain Zr-doped Na 0.67 Fe 0.5 Mn 0.5 O2 material, to obtain Na 0.67 Fe 0.45 Zr 0.05 Mn 0.5 O2 material, which was stored in a glove box.

[0052] Comparative Example 1 The difference from Example 1 is only that the Zr doping process is not included, only Na 0.67 Fe 0.5 Mn 0.5 O2 material (before Zr doping), specifically including the following steps: At 35°C, 1.255 g of manganese nitrate tetrahydrate and 2.02 g of iron nitrate nonahydrate, 1.201 g of urea were added to a mixed solution of 40 ml of ethylene glycol and 20 ml of deionized water, and constant temperature stirring was carried out at a rotation speed of 400 rpm for 2 h to make it fully dissolved and uniformly mixed, and then the mixed solution was placed in a high-pressure reaction kettle and reacted at 150°C for 12 h. The reaction completed solution was washed and centrifuged alternately with deionized water and anhydrous ethanol at a rotation speed of 5000 rpm, the precipitate obtained after centrifugation was dried in a vacuum drying box at 60°C for 12 h, then mixed with 0.355 g of sodium carbonate in a mortar and ground for 1 h, and then placed in a tube furnace and calcined at 900°C for 15 h. After calcination, it was naturally cooled and ground to obtain Na 0.67 Fe 0.5 Mn 0.5 O2 material, which was stored in a glove box.

[0053] Comparative Example 2 The difference from Example 1 is only that the Zr doping in step (2) is replaced by Ce doping, specifically including the following steps: At 35°C, 1.255 g of manganese nitrate tetrahydrate, 1.181 g of iron nitrate nonahydrate and 0.217 g of cerium nitrate hexahydrate, 1.201 g of urea were added to a mixed solution of 40 ml of ethylene glycol and 20 ml of deionized water, and constant temperature stirring was carried out at a rotation speed of 400 rpm for 2 h to make it fully dissolved and uniformly mixed, and then the mixed solution was placed in a high-pressure reaction kettle and reacted at 150°C for 12 h. After the reaction was completed, the reaction completed solution was washed and centrifuged alternately with deionized water and anhydrous ethanol at a rotation speed of 5000 rpm, the precipitate obtained after centrifugation was dried in a vacuum drying box at 60°C for 12 h, then mixed with 0.355 g of sodium carbonate in a mortar and ground for 1 h, and then placed in a tube furnace and calcined at 900°C for 15 h. After calcination, it was naturally cooled and ground to realize Ce-doped Na 0.67 Fe 0.5 Mn 0.5 O2 material, which was stored in a glove box. 0.67 Fe 0.45 Ce 0.05 Mn 0.5 O2 material, which was stored in a glove box.

[0054] Technical effects: 1. Performance characterization Figure 1The XRD patterns of Zr ion-doped materials obtained in Examples 1-3 and Comparative Example 1 show that the crystal structure of the material does not change for different Zr ion doping, and the original P2 phase structure is maintained. However, some oxide impurities are inevitably present.

[0055] Figure 2 The images show the XRD patterns of Zr ion-doped materials synthesized from different raw materials in Examples 4 and 5. It can be seen that Na+ can still be prepared using different source materials. 0.67 Fe 0.4 Zr 0.1 Mn 0.5 O2 and Na 0.67 Fe 0.45 Zr 0.05 Mn 0.5 The presence of O2 materials demonstrates the feasibility of this method.

[0056] Figure 3 Na obtained in Example 1 0.67 Fe 0.45 Zr 0.05 Mn 0.5 The elemental distribution diagram of the O2 material shows that the material synthesized using this method has a uniform elemental distribution.

[0057] Na obtained in Example 1 0.67 Fe 0.45 Zr 0.05 Mn 0.5 Electron micrographs of O2 materials are shown below. Figure 4 As shown, where, Figure 4 Part (a) is a SEM image, showing Na 0.67 Fe 0.45 Zr 0.05 Mn 0.5 O2 material is a structure composed of irregularly stacked sheet-like particles. Figure 4 Part (b) is a TEM image, and part (c) is a magnified view of the red box in (b). It can be seen that the doping of Zr ions expands the interplanar spacing of the (103) crystal planes.

[0058] Na obtained from Comparative Example 1 0.67 Fe 0.5 Mn 0.5 SEM images of O2 materials, such as Figure 5 As shown, it can be seen that Na 0.67 Fe 0.5 Mn 0.5 The O2 material exhibits an irregular sheet-like structure.

[0059] Figure 6For the XRD patterns of the products obtained before and after zirconium ion doping (i.e., Example 1 (after zirconium ion doping) and Comparative Example 1 (before zirconium ion doping)), it can be seen that the diffraction peaks of the materials before and after zirconium ion doping all correspond to the standard card, and some oxide impurities inevitably exist. Among them, the (002) characteristic peak of the product obtained in Example 1 shifts to a low angle, according to the Bragg equation, the angle shifts to a low angle, which means that the doping of zirconium ions causes the expansion of the (002) crystal face spacing.

[0060] Figure 7 For the XRD refinement patterns before and after Zr ion doping, the refinement data are shown in Table 1, wherein a and b are the distances between transition metal ions, and c is the sodium layer spacing. It can be seen that the values of a and b decrease after refinement, the distance between transition metal ions decreases, the stability of the transition metal layer is enhanced, and the migration of iron ions in the charging and discharging process is inhibited. At the same time, the increase of the value of c indicates that the material has an increased sodium layer spacing, which is beneficial to improve the diffusion dynamics of sodium ions.

[0061] Table 1 2. Electrochemical performance 2.1 Preparation of the battery 1) Preparation of the electrode sheet Raw materials: polyvinylidene fluoride (PVDF), N-methyl pyrrolidone (NMP), carbon black (acetylene black), electrode material (product obtained in the examples and comparative examples); According to the mass ratio of 8:1:1, electrode material 0.08 g, carbon black 0.01 g, and PVDF 0.01 g were weighed respectively, and the three powders were ground uniformly with a mortar. Then 1 g of NMP was slowly added, and the mixture was stirred into a paste. The paste was uniformly coated on an aluminum foil using a film applicator. The aluminum foil was vacuum dried at 80°C for 6h (or 60°C for 12h), and then cut into a 14×14mm circular positive electrode sheet using a sheet cutter.

[0062] 2) Battery assembly Raw materials: positive electrode sheet obtained in step 1), sodium secondary battery electrolyte, foam nickel (14×14 mm), sodium sheet (14×14 mm), separator (PP, 18×18 mm), argon, positive shell and negative shell of the button cell (CR2025); The positive electrode sheet obtained in step 1) was placed into the positive shell of the button cell 2025, and then a glass fiber separator was placed. After slowly adding 120µL of electrolyte to completely soak the electrode sheet, a sodium sheet and a foam nickel were sequentially placed, followed by a negative shell of the button cell 2025. Then, the sheet was pressed using a sheet press at a pressure of 50Mpa for 5s, thereby completing the assembly of the battery, and obtaining a sodium ion battery.

[0063] 2.2 The electrochemical performance of the products obtained in Example 1 and Comparative Example 1 was detected using the above sodium ion battery: According to the new battery test system and Chenhua 760e electrochemical workstation, the voltage range was 2V-4V, and the current density was selected as 1C=175mA g -1 The first charge-discharge, cycle specific capacity and EIS performance of the products obtained in Example 1 and Comparative Example 1 were detected.

[0064] Figure 8 The first charge-discharge of the products obtained in Example 1 and Comparative Example 1 was compared, and it could be seen that the first discharge specific capacity of the product obtained in Comparative Example 1 was 93mAh g -1 at 0.1C rate, and the first discharge specific capacity of the material obtained after zirconium ion doping (Example 1) reached 120.3 mAh g -1 Zirconium ion doping expanded the sodium ion migration channel and accelerated the sodium ion transmission.

[0065] Figure 9 The rate comparison chart of different materials before and after zirconium ion doping could be seen, and it could be seen that the specific capacity of the material after zirconium ion doping was obviously improved at different rates.

[0066] Figure 10 The cycle specific capacity of the products obtained in Example 1 and Comparative Example 1 at 0.5C rate could be seen, and it could be seen that the specific capacity of the product obtained in Example 1 remained higher than that of Comparative Example 1 in 200 cycles, and the cycle stability was also improved.

[0067] Figure 11 The cycle specific capacity of the products obtained in Example 1 and Comparative Example 1 at 1C rate could be seen, and it could be seen that the specific capacity of the product obtained in Example 1 remained higher than that of Comparative Example 1 in 500 cycles.

[0068] Figure 12 The EIS comparison chart of the products obtained in Example 1 and Comparative Example 1 after 100 cycles could be seen, and it could be seen that the semicircle diameter in the high frequency region represented the charge transfer resistance (Rct), and the oblique line in the low frequency region was equivalent to the Warburg impedance (W). Rct could be used to measure the transfer impedance of Na + at the electrolyte / electrode interface, and W was used to measure the diffusion of Na + After 100 cycles, zirconium ion doping obviously reduced the charge transfer resistance of the material, and zirconium ion doping promoted the sodium ion extraction rate.

[0069] Figure 13 In Comparative Example 2, the element Ce was selected to prepare Na 0.67 Fe 0.45 Ce 0.05 Mn 0.5The XRD pattern of the O2 material can be seen that the prepared material cannot be aligned with the standard card 54-0894, indicating that the selection of Ce element cannot prepare the material, and cannot reach the synergistic effect with the iron ion in the application.

[0070] Figure 14 For the valence change of the iron ion before and after Zr doping in Example 1 and Comparative Example 1, it can be seen that the content of trivalent iron ion is reduced after Zr doping, and the trivalent iron ion is the key factor causing the Jahn-Teller effect of the layered oxide, therefore, the reduction of the content of the trivalent iron ion enhances the stability of the transition metal layer of the material, and inhibits the migration of the iron ion in the charging and discharging process.

[0071] The above is only the preferred specific embodiment of the application, but the protection scope of the application is not limited to this, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the application, which should be covered in the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.

Claims

1. A method for inhibiting Na 0.67 Fe 0.5 Mn 0.5 The method for iron ion migration in O2 materials is characterized by... The Na is partially replaced by Zr ions. 0.67 Fe 0.5 Mn 0.5 Iron ions in O2 material yield Zr-doped iron-manganese base layer metal oxide electrode material Na. 0.67 Fe 0.5-x Zr x Mn 0.5 O2; Wherein, x = 0.03-0.

1.

2. A method for inhibiting Na according to claim 1 0.67 Fe 0.5 Mn 0.5 The method for iron ion migration in O2 materials is characterized by... Specifically, the following steps are included: Manganese, iron, zirconium, and urea sources are mixed and dissolved in a solvent. After hydrothermal reaction, the resulting solid product is mixed with a sodium source and calcined. After calcination, the mixture is cooled and ground to achieve Zr-doped Na. 0.67 Fe 0.5 Mn 0.5 O2 material is used to partially replace the iron ions in it, resulting in Zr-doped iron-manganese base layer metal oxide electrode material Na. 0.67 Fe 0.5-x Zr x Mn 0.5 O2.

3. A method for inhibiting Na according to claim 2 0.67 Fe 0.5 Mn 0.5 The method for iron ion migration in O2 materials is characterized by... The manganese source is manganese nitrate and / or manganese chloride.

4. A method for inhibiting Na according to claim 2 0.67 Fe 0.5 Mn 0.5 The method for iron ion migration in O2 materials is characterized by... The iron source is ferric nitrate and / or ferric chloride.

5. A method for inhibiting Na according to claim 2 0.67 Fe 0.5 Mn 0.5 The method for iron ion migration in O2 materials is characterized by... The zirconium source is zirconium nitrate and / or zirconium acetate.

6. A method for inhibiting Na according to claim 2 0.67 Fe 0.5 Mn 0.5 The method for iron ion migration in O2 materials is characterized by... The sodium source is sodium carbonate.

7. A method for inhibiting Na according to claim 2 0.67 Fe 0.5 Mn 0.5 The method for iron ion migration in O2 materials is characterized by... The hydrothermal reaction was carried out at a temperature of 130-160℃ for 12 hours.

8. A method for inhibiting Na according to claim 2 0.67 Fe 0.5 Mn 0.5 The method for iron ion migration in O2 materials is characterized by... The calcination temperature is 850-1000℃, and the time is 15 hours.

9. A Zr-doped iron-manganese base layer metal oxide electrode material prepared by the method according to any one of claims 1-8.

10. The application of the Zr-doped iron-manganese base layer metal oxide electrode material as described in claim 9 in the cathode material of sodium-ion batteries.

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