MANUFACTURING METHOD OF A CATHODAL MATERIAL FOR A DOPED MANGANE-BASED SODIUM ION BATTERY

Abstract

Preparation method of a cathode material for a doped manganese-based sodium ion battery, comprising the following steps: S1: Dissolving one or both of antimony trioxide and bismuth trioxide with an acid and subsequently adding a divalent manganese salt to produce a mixed metal salt solution; S2: Adding the mixed metal salt solution to an excess alkaline oxidizing agent solution for the reaction, and after the reaction is complete, carrying out a solid-liquid separation to obtain a solid material, such that manganese ions are oxidized to manganese dioxide, and antimony is co-precipitated with the manganese dioxide to a form of sodium hexahydroxyantimonate, or bismuth is co-precipitated with the manganese dioxide to a form of sodium bismuthate, thereby ensuring the homogeneity of doped elements in the cathode material and achieving atomic-level mixing between the elements; and S3: Drying the solid material and subsequent mixing with a sodium source and sintering of a resulting mixture to obtain the cathode material for the doped manganese-based sodium ion battery; wherein, in step S2, the alkaline oxidizing agent solution is a sodium hydroxide solution in which one or more of sodium hypochlorite, sodium chlorate, and sodium permanganate are dissolved; wherein, in step S2, the mixed metal salt solution is added dropwise, the alkaline oxidizing agent solution always has a pH equal to or greater than 10.5, and one oxidizing agent in the alkaline oxidizing agent solution is always sufficient; and wherein, in step S2, the temperature of the reaction is controlled to between 2 °C and 10 °C.

Description

TECHNICAL AREA

[0001] The present disclosure belongs to the technical field of sodium ion batteries and relates in particular to a manufacturing process of a cathode material for a sodium ion battery based on doped manganese. BACKGROUND

[0002] Sodium-ion batteries possess the characteristics of low raw material costs, abundant resources, and high electrochemical performance potential. Therefore, they are expected to be used in the field of large-scale energy storage and represent one of the key research areas for next-generation battery technology.

[0003] The increasing demand for new energy storage systems and the continuous expansion of the sodium-ion battery market have made research into high-performance sodium-ion electrode materials increasingly important. The cathode material is a key factor influencing the energy density, lifespan, and cost of batteries. The development of highly efficient cathode materials is crucial for promoting the commercialization of sodium-ion batteries.

[0004] Currently, common cathode materials for sodium-ion batteries mainly consist of layered transition metal oxides, Prussian blue analogs, polyanionic compounds, and tunnel oxides. Compared to materials such as Prussian blue analogs, polyanionic compounds, and tunnel oxides, layered transition metal oxides exhibit a higher specific capacity and better meet the requirement for high energy density.

[0005] However, layered transition metal oxides exhibit poor cycling performance and low capacity retention, which require further improvement. Some recent research indicates that the instability of the material structure caused by phase transitions and side reactions between the material and the electrolyte are the main reasons for the poor cycling performance. To mitigate these problems, elemental doping, surface coating, and novel structural design have been proposed as effective methods to improve the cycling performance of cathode materials. Among these, the elemental doping process is simpler and more effective than the other two methods, significantly reducing production costs and time. Doping with other elements improves the stability of the crystal structure, increases the stability of the cathode material structure, and further enhances cycling performance.

[0006] However, doping materials presents the following difficulties: (1) the doping phase places extremely high demands on the stability of the process control; (2) the selection of doping elements, process methods and parameter control are difficult in order to achieve uniform doping effects; and (3) there is little research on doping techniques, doping elements, doping quantity, etc., which makes research and development as well as industrialization more difficult.

[0007] CN 1 10 112 375 A discloses a positive electrode material based on a manganese-based double transition metal for a sodium-ion battery, characterized in that the general formula Na x Mn 1-y M y O2 is where M is Ru, Ir, Nb, Bi, Sn, Ta or Sb and 0.3≤x≤1 and 0 <y≤0,5.

[0008] US 2019 / 0207213A1 discloses a sodium-based active electrode material and a secondary battery containing it. The active electrode material is represented by the following chemical formula 1 and has an orthorhombic crystal system and the space group Cmcm. [Chemical Formula 1]Na x [Mn 1-y-z M 1 y M 2 z]O 2-α A α In chemical formula 1, x can be between 0.5 and 0.8. M 1 and M 2 The elements can be Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nd, Mo, Tc, Ru, Rh, Pd, Pb, Ag, Cd, Al, Ga, In, Sn, or Bi, independently of each other. y can be between 0 and 0.25. z can be between 0 and 0.25. A can be N, O, F, or S, and a can be between 0 and 0.1. OVERVIEW

[0009] The present disclosure aims to solve at least one of the technical problems that exist in the aforementioned prior art. Therefore, the present disclosure proposes a manufacturing process for a cathode material for a manganese-doped sodium-ion battery, which can improve the cycle performance of the cathode material for manganese-based sodium-ion batteries.

[0010] According to one aspect of the present disclosure, a preparation method for a cathode material for a doped manganese-based sodium ion battery is proposed, comprising the following steps: S1: Dissolving one or both of antimony trioxide and bismuth trioxide with an acid and subsequently adding a divalent manganese salt to produce a mixed metal salt solution; S2: Adding the mixed metal salt solution to an excess alkaline oxidizing agent solution for the reaction, and, after the reaction is complete, carrying out a solid-liquid separation to obtain a solid material, such that manganese ions are oxidized to manganese dioxide, and antimony is co-precipitated with the manganese dioxide to a form of sodium hexahydroxyantimonate, or bismuth is co-precipitated with the manganese dioxide to a form of sodium bismuthate, thereby ensuring the homogeneity of doped elements in the cathode material and achieving atomic-level mixing between the elements; and S3: Drying the solid material and subsequent mixing with a sodium source and sintering of a resulting mixture to obtain the cathode material for the doped manganese-based sodium ion battery, wherein, in step S2, the alkaline oxidizing agent solution is a sodium hydroxide solution in which one or more of sodium hypochlorite, sodium chlorate, and sodium permanganate are dissolved; wherein, in step S2, the mixed metal salt solution is added dropwise, the alkaline oxidizing agent solution always has a pH equal to or greater than 10.5, and one oxidizing agent in the alkaline oxidizing agent solution is always sufficient; and wherein, in step S2, the temperature of the reaction is controlled to between 2 °C and 10 °C.

[0011] In some embodiments of the present disclosure, the acid in step S1 is selected from at least one of the following acids: tartaric acid, hydrochloric acid, concentrated sulfuric acid or concentrated nitric acid.

[0012] In some embodiments of the present disclosure, in step S1 the divalent manganese salt is selected from at least one of the following salts: manganese sulfate, manganese chloride and manganese nitrate; wherein a total concentration of a metal ion in the mixed metal salt solution is 0.1 mol / L to 2.0 mol / L; a molar ratio of the dopant metal to manganese in the mixed metal salt solution is (1-15): (85-99), and the dopant metal is one or both of antimony and bismuth.

[0013] In some embodiments of the present disclosure, sodium hypochlorite, sodium chlorate and sodium permanganate are selected as oxidizing agents in the alkaline oxidizing agent solution in step S2 to avoid mixing other ions and thus improve the purity of the product.

[0014] In some embodiments of the present disclosure, the concentration of sodium hydroxide in the alkaline oxidizing agent solution in step S2 is 0.1 mol / L to 4.0 mol / L.

[0015] In some embodiments of the present disclosure, the dropwise addition of the mixed metal salt solution in step S2 can reduce the occurrence of side reactions and avoid a phenomenon of independent precipitation of manganese dioxide.

[0016] In the present disclosure, in step S2 the temperature of the reaction is controlled to 2 °C to 10 °C, which avoids dissolving the generated sodium hexahydroxyantimonate or sodium bismuth to produce colloids.

[0017] In some embodiments of the present disclosure, the reaction in step S2 is terminated when the addition of the mixed metal salt solution to the alkaline oxidizing agent solution is stopped.

[0018] In some embodiments of the present disclosure, the temperature for drying the solid material in step S3 does not exceed 25 °C.

[0019] In some embodiments of the present disclosure, the sodium source in step S3 is one or more of sodium carbonate, sodium oxalate, sodium acetate, sodium hydroxide or sodium peroxide.

[0020] In some embodiments of the present disclosure, in step S3, the molar ratio of the sodium element in the sodium source to the manganese element in the solid is 0 <x≤1.

[0021] In some embodiments of the present disclosure, the sintering in step S3 is carried out at a temperature of 650 °C to 950 °C, with the sintering lasting 12 to 24 hours.

[0022] According to a preferred embodiment of the present disclosure, the present disclosure has at least the following advantageous effects. 1. Since the material is doped with an antimony or bismuth element, the skeletal structure of the material is strengthened and the phase change of the material during the charging and discharging process is suppressed, which can significantly improve the specific capacity, cycle performance and rate capability of the material. 2. By adding a mixed metal salt solution dropwise to an excess alkaline oxidizing agent solution, manganese ions are oxidized to manganese dioxides, and antimony or bismuth are co-precipitated with manganese dioxides in the form of sodium hexahydroxyantimonate or sodium bismutate, thereby ensuring the homogeneity of the doping element of the material and achieving mixing at the atomic level between the elements. 3. By exploiting the water-insoluble property of sodium hexahydroxyantimonate or sodium bismuth, sodium ions are introduced beforehand during co-precipitation to reduce the pressure of the subsequent sintering with the sodium source, and only a small amount of the sodium source needs to be added according to the ratio to achieve successful sintering. 4. In the cathode material produced by sintering for the sodium ion battery, both antimony and bismuth are positive pentavalents with higher valences, so that their properties are extremely stable, which can prevent the occurrence of side reactions between the material interface and the electrolyte during the charging and discharging process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present revelation is further described below in connection with the drawings and examples in which: Fig. 1 is a SEM image of the cathode material for a doped manganese-based sodium ion battery produced in Example 1 of the present disclosure. DETAILED DESCRIPTION OF THE EXECUTION FORMS

[0024] The following section clearly and completely describes the concept of this revelation and the technical effects produced by it, along with the examples, in order to fully understand its purpose, features, and effects. It is evident that the examples described represent only a portion of the examples in this revelation, and not all of them. All other examples obtained by skilled workers based on the examples in this revelation, without any creative work, fall within the scope of this revelation. Example 1

[0025] In this example, a cathode material for a manganese-doped sodium ion battery was produced, and the specific process was as follows. (1) Antimony trioxide was dissolved in hydrochloric acid and manganese chloride was added to prepare a mixed metal salt solution with a total metal ion concentration of 0.1 mol / L, in which the molar ratio of antimony to manganese was 5:95. (2) A mixed solution of sodium hydroxide with a concentration of 1.0 mol / L and sodium hypochlorite with a concentration of 0.3 mol / L was prepared as an alkaline oxidizing agent solution. (3) The mixed metal salt solution was added dropwise to the alkaline oxidizing agent solution for the reaction, and the temperature of the reaction system was controlled between 2 °C and 10 °C. It was always ensured that the alkaline oxidizing agent solution had a pH ≥ 10.5 and that the oxidizing agent was always sufficient. After the reaction was complete, a solid-liquid separation was carried out to obtain a solid material. (4) After drying at a low temperature, the solid material was mixed with sodium oxalate in a sodium-to-manganese molar ratio of 0.39:1 and then held at 650 °C for 24 hours. After the reaction was complete, the cathode material for the doped manganese-based sodium-ion battery was given the chemical formula Na 0,44 Sb 0,05 Mn 0.95 O 2,15 receive.

[0026] The cathode material for the doped manganese-based sodium-ion battery was assembled into a sodium-ion half-cell exhibiting a voltage range of 2.0 V to 3.8 V at a rate of 0.8 C, an initial specific capacity of up to 135.3 mAh / g, a specific capacity of 131.2 mAh / g after 100 charge and discharge cycles, and a capacity retention rate of 96.97%. Example 2

[0027] In this example, a cathode material for a manganese-doped sodium-ion battery was produced, and the specific process was as follows: (1) Bismuth trioxide was dissolved with tartaric acid and manganese chloride was added to prepare a mixed metal salt solution with a total metal ion concentration of 0.2 mol / L, where the molar ratio of bismuth to manganese was 5:95. (2) A mixed solution of sodium hydroxide with a concentration of 2.0 mol / L and sodium hypochlorite with a concentration of 0.5 mol / L was prepared as an alkaline oxidizing agent solution. (3) The mixed metal salt solution was added dropwise to the alkaline oxidizing agent solution for the reaction, and the temperature of the reaction system was controlled between 2 °C and 10 °C. It was always ensured that the alkaline oxidizing agent solution had a pH ≥ 10.5 and that the oxidizing agent was always sufficient. After the reaction was complete, a solid-liquid separation was carried out to obtain a solid material. (4) After drying at a low temperature, the solid material was mixed with sodium oxalate in a sodium-to-manganese molar ratio of 0.39:1 and then held at 700 °C for 20 hours. After the reaction was complete, the cathode material for the doped manganese-based sodium-ion battery was given the chemical formula Na 0,44 Bi 0,05 Mn 0,95 O 2,15 receive.

[0028] The cathode material for the doped manganese-based sodium-ion battery was assembled into a sodium-ion half-cell exhibiting a voltage range of 2.0 V to 3.8 V at a rate of 0.8 C, an initial specific capacity of up to 134.6 mAh / g, a specific capacity of 131.5 mAh / g after 100 charge and discharge cycles, and a capacity retention rate of 97.70%. Example 3

[0029] In this example, a cathode material for a manganese-doped sodium ion battery was produced, with the specific process being as follows. (1) Antimony trioxide and bismuth trioxide were dissolved with hydrochloric acid and manganese chloride was added to prepare a mixed metal salt solution with a total metal ion concentration of 0.3 mol / L, in which the molar ratio of antimony, bismuth and manganese was 5:5:90. (2) A mixed solution of sodium hydroxide with a concentration of 4.0 mol / L and sodium hypochlorite with a concentration of 1.0 mol / L was prepared as an alkaline oxidizing agent solution. (3) The mixed metal salt solution was added dropwise to the alkaline oxidizing agent solution for the reaction, and the temperature of the reaction system was controlled between 2 °C and 10 °C. It was always ensured that the alkaline oxidizing agent solution had a pH ≥ 10.5 and that the oxidizing agent was always sufficient. After the reaction was complete, a solid-liquid separation was carried out to obtain a solid material. (4) After drying at a low temperature, the solid material was mixed with sodium peroxide in a sodium-to-manganese molar ratio of 0.39:1 and then held at 900 °C for 18 hours. After the reaction was complete, the cathode material for the doped manganese-based sodium-ion battery was given the chemical formula Na 0,44 Sb 0,05 Bi 0,05 Mn 0,90 O 2,15 receive.

[0030] The cathode material for the doped manganese-based sodium-ion battery was assembled into a sodium-ion half-cell exhibiting a voltage range of 2.0 V to 3.8 V at a rate of 0.8 C, an initial specific capacity of up to 138.7 mAh / g, a specific capacity of 132.3 mAh / g after 100 charge and discharge cycles, and a capacity retention rate of 95.39%.

Claims

[1] Preparation method of a cathode material for a doped manganese-based sodium ion battery comprising the following steps: S1: Dissolving one or both of antimony trioxide and bismuth trioxide with an acid and subsequently adding a divalent manganese salt to produce a mixed metal salt solution; S2: Adding the mixed metal salt solution to an excess alkaline oxidizing agent solution for the reaction, and after the reaction is complete, carrying out a solid-liquid separation to obtain a solid material, such that manganese ions are oxidized to manganese dioxide, and antimony is co-precipitated with the manganese dioxide to a form of sodium hexahydroxyantimonate, or bismuth is co-precipitated with the manganese dioxide to a form of sodium bismuthate, thereby ensuring the homogeneity of doped elements in the cathode material and achieving atomic-level mixing between the elements; and S3: Drying the solid material and subsequent mixing with a sodium source and sintering of a resulting mixture to obtain the cathode material for the doped manganese-based sodium ion battery; wherein, in step S2, the alkaline oxidizing agent solution is a sodium hydroxide solution in which one or more of sodium hypochlorite, sodium chlorate, and sodium permanganate are dissolved; wherein, in step S2, the mixed metal salt solution is added dropwise, the alkaline oxidizing agent solution always has a pH equal to or greater than 10.5, and one oxidizing agent in the alkaline oxidizing agent solution is always sufficient; and wherein, in step S2, the temperature of the reaction is controlled to between 2 °C and 10 °C. [2] Preparation method according to claim 1, wherein, in step S1, the acid is selected from at least one of the following acids: tartaric acid, hydrochloric acid, concentrated sulfuric acid or concentrated nitric acid. [3] Preparation method according to claim 1, wherein, in step S1, the divalent manganese salt is selected from at least one of the following salts: manganese sulfate, manganese chloride or manganese nitrate; and wherein the total concentration of metal ions in the mixed metal salt solution is 0.1 mol / L to 2.0 mol / L. [4] Preparation method according to claim 1, wherein, in step S2, the concentration of sodium hydroxide in the alkaline oxidizing agent solution is 0.1 mol / L to 4.0 mol / L. [5] Preparation method according to claim 1, wherein, in step S3, the sodium source is selected from at least one of the following: sodium carbonate, sodium oxalate, sodium acetate, sodium hydroxide or sodium peroxide. [6] Preparation method according to claim 1, wherein, in step S3, a molar ratio of the sodium element in the sodium source to the manganese element in the solid material x: 1, wherein 0 <x≤ 1. [7] Preparation method according to claim 1, wherein, in step S3, sintering is carried out at a temperature of 650 °C to 950 °C for a duration of 12 hours to 24 hours.

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