MANUFACTURING METHOD FOR A CATHOD MATERIAL FOR SODIUM-ION BATTERIES

Abstract

A manufacturing process for a cathode material for sodium-ion batteries, wherein the cathode material has a chemical formula Na 0,67 Mn a Zr b F c O2 has, where 0 <a<1, 0<b<1, 0<c<1 und a+b+c=1; wobei das Herstellungsverfahren die folgenden Schritte aufweist: (1) Subjecting a battery powder to acid leaching, adding a reducing agent to a material after acid leaching for reaction, adding an alkaline solution to adjust pH, subjecting a resulting mixture to a precipitation reaction and then filtering the same to obtain a precipitate and a filtrate; (2) Adding potassium permanganate to the filtrate, carrying out a primary precipitation reaction and solid-liquid separation to obtain manganese dioxide and a filtrate, adjusting the pH of the filtrate and introducing carbon dioxide, carrying out a secondary precipitation reaction and solid-liquid separation to obtain lithium carbonate and a fluorine-containing solution; (3) Adding a sodium source, a zirconium salt and a complexing agent to the fluorine-containing solution for reacting and sintering a reacted material to produce a Na 0,67 Zr b F c to obtain O2 precursors; and (4) Mixing the Na 0,67 Zr b F c O2 precursor with the manganese dioxide in step (2) and calcination of a resulting mixture to form the cathode material Na 0,67 Mn a Zr b F c to obtain O2; wherein in step (1) the battery powder is obtained by subjecting a waste lithium manganate to discharge, comminution, high temperature calcination and sieving; wherein in step (1) an acid used for acid leaching is at least one of malic acid and one of citric acid; wherein in step (3) the complexing agent is at least one of glucose and sucrose; and where in step (4) the calcination is carried out at a temperature of 300°C to 400°C for 6 to 12 hours.

Description

TECHNICAL FIELD

[0001] The present invention belongs to the technical field of sodium ion batteries and particularly relates to a manufacturing method for a cathode material for sodium ion batteries. BACKGROUND

[0002] Lithium manganate (LiMn2O4), as a cathode material for lithium-ion batteries, is known for its low price, high potential, environmental friendliness, and high safety. Currently, lithium manganate batteries are widely used in the field of new energy. According to statistics, the service life of lithium batteries is 3 to 5 years, and battery scrap reached its first peak in 2018, with lithium manganate battery scrap exceeding 10,000 tons. The cathode materials of lithium manganate batteries contain many Li and Mn elements, which will cause serious pollution to the aquatic environment if these elements are not treated safely and effectively. Therefore, recycling various battery materials can not only reduce enterprises' production costs and promote the sustainable development of the new energy industry, but also reduce environmental pollution caused by waste battery materials.

[0003] Currently, many companies have the capabilities to recycle batteries, but there are still many problems that urgently need to be resolved. Lithium manganate batteries have poor specific capacity and performance, while sodium-ion batteries have high specific capacity and low cost. However, the cathode materials of sodium-ion batteries also have some weaknesses, such as poor conductivity.

[0004] Therefore, it is urgently necessary to provide a sodium ion battery cathode material and manufacturing process that not only enables the recycling of lithium manganate batteries but also improves the problem of insufficient performance of the sodium ion battery cathode material.

[0005] CN 1 07 369 826 A discloses a lithium / sodium layered metal oxide positive electrode material with dual modification of doping and coating and a one-step manufacturing process therefor. The ion-doped and interface-coated lithium / sodium layered metal oxide positive electrode material is prepared by a solvent heat treatment / solid-state ball milling process, wherein the doped ions are one or more of the following: F - , Mg2 + , Cu2 + , Zn2 + , Al3 + , Fe3 + , Cr3 + , Ti4 + , Zr4 + , Mo4 + , Nb5 + and V5 + The interfacial coating is an ionic compound comprising lanthanide or actinide ions with an ionic radius greater than or equal to 1.016 Å. OVERVIEW

[0006] The present invention aims to solve at least one of the above-mentioned technical problems in existing technology. Therefore, the present invention provides a manufacturing method for a cathode material for sodium-ion batteries. The sodium-ion battery cathode material has a high specific capacity and excellent cycle performance.

[0007] To achieve the above-mentioned object, the present invention applies the following technical solutions.

[0008] A manufacturing method for a cathode material for sodium ion batteries, wherein the cathode material has a chemical formula Na 0,67 Mn a Zr b F c O2, where 0 <a<1, 0<b<1, 0<c<1 und a+b+c=1, enthält die folgenden Schritte: (1) Subjecting a battery powder to acid leaching, adding a reducing agent into a material after acid leaching for reaction, adding an alkali to adjust a pH, subjecting a resulting mixture to precipitation reaction, and then filtering the same to obtain a precipitate and a filtrate; (2) adding potassium permanganate into the filtrate, conducting a primary precipitation reaction and a solid-liquid separation to obtain manganese dioxide and a filtrate, adjusting a pH of the filtrate and introducing carbon dioxide, conducting a secondary precipitation reaction and a solid-liquid separation to obtain lithium carbonate and a fluorine-containing solution; (3) Adding a sodium source, a zirconium salt and a complexing agent into the fluorine-containing solution to react and sinter a reacted material to form a Na 0,67 Zr b F c to obtain O2 precursors; and (4) Mixing the Na 0,67 Zr b F c O2 precursor with the manganese dioxide in step (2) and calcining a resulting mixture to form the cathode material Na 0,67 Mn a Zr b F c to receive O2; wherein in step (1), the battery powder is obtained by subjecting a waste lithium manganate to discharge, crushing, high temperature calcination and sieving; wherein in step (1), an acid used for the acid leaching is at least one of malic acid and citric acid; wherein in step (3) the complexing agent is at least one of glucose and sucrose; and wherein in step (4) the calcination is carried out at a temperature of 300°C to 400°C for 6 hours to 12 hours.

[0009] More preferably, the discharging refers to a discharging treatment carried out in a saturated sodium chloride solution.

[0010] More preferably, the calcination is carried out at a temperature of 600 °C to 900 °C and lasts from 2 hours to 6 hours.

[0011] More preferably, the mesh size of the sieve is in the range of 100 µm to 200 µm.

[0012] Preferably, the acid leaching in step (1) lasts from 4 hours to 12 hours.

[0013] Preferably, in step (1), the reducing agent is at least one of iron powder or aluminum powder.

[0014] Preferably in step (1) the alkali metal hydroxide is sodium hydroxide.

[0015] Preferably, in step (1), adjusting the pH refers to adjusting the pH of the solution to 3 to 5.

[0016] Furthermore, in step (1) a concentration of the alkali metal hydroxide solution is preferably in the range of 0.5 mol / L to 3 mol / L.

[0017] Preferably, in step (2), a concentration ratio of manganese ions in the potassium permanganate to manganese ions in the solution (2 to 3): 1.

[0018] Preferably, in step (2) the pH of the filtrate is adjusted to 9 to 10.

[0019] Preferably, in step (2), the alkali used to adjust the pH of the filtrate is sodium hydroxide.

[0020] Preferably, in step (3), the sodium source is at least one of Na2CO3, NaNO3 or Na2SO4.

[0021] Preferably, in step (3), the zirconium salt is at least one of zirconium nitrate, zirconium acetate or zirconium citrate.

[0022] Furthermore, in step (3), sintering is carried out at a temperature of 350 °C to 450 °C and lasts 4 hours to 8 hours.

[0023] Preferably, in step (4), a molar ratio of the Na 0,67 Zr b F c O2 precursor to manganese dioxide 1: (0.7 to 0.9).

[0024] Compared with the existing technology, the present invention has the following advantageous effects. 1. The sodium ion battery cathode material produced by the present invention is doped with fluorine ions having a distance between Na + -diffusion layers, thereby improving the electronic conductivity of the cathode material; and then Zr 4+ introduced to prevent a crystal structure from being dissolving Mn 3+ in the cathode material collapses, and Zr 4+replaces part of the manganese ions in the cathode material, so that a volume of the cathode material is small during the process of charging and discharging, which reduces the deformation of the material and improves the cycle performance. 2. In the production method according to the present invention, waste lithium manganate is used as the raw material and added to the acidic solution for dissolution. The final filtrate contains only fluorine ions due to the removal of impurities, and the fluorine ions can be used for subsequent modification of the sodium-ion battery cathode material. In the production method, calcination is carried out at a temperature of 300°C to 400°C. Under this condition, the crystal structure of manganese dioxide is α-MnO2. α-MnO2 has a large specific surface area and good corrosion resistance, which not only promotes electron transfer but also prevents the active substances in the electrolyte and the cathode material from reacting with each other. 3. Part of the raw materials of the present invention is taken from the waste batteries, which not only eliminates the threat of the waste batteries to the environment, but also contributes to the sustainable development of the industry and is in line with the concept of green development. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a flowchart of an embodiment of the present invention; Fig. 2 is an SEM diagram of Embodiment 1 of the present invention; and Fig. 3 is an SEM diagram of Embodiment 2 of the present invention. DETAILED DESCRIPTION

[0025] The concepts and technical effects produced by the present invention are described clearly and completely in conjunction with the embodiments in order to sufficiently understand the objects, features, and effects of the present invention. It should be understood that the described embodiments are merely some embodiments of the present invention and not all embodiments. Other embodiments obtained by those skilled in the art without exerting any creative effort are all intended to be within the scope of the present invention. Embodiment 1

[0026] A chemical formula of a sodium ion battery cathode material of this embodiment was Na 0,67 Mn 0,87 Zr 0,10 F 0,03 O2.

[0027] A manufacturing method of the sodium ion battery cathode material of this embodiment included the following steps: (1) Discharging and crushing a waste lithium manganate battery material and calcining at 900 °C for 2 hours to obtain a battery powder; (2) Adding 10 g of the battery powder above into 100 mL of malic acid solution with a concentration of 1 mol / L and reacting for 12 hours, adding 1 g of iron powder, then adding a NaOH solution with a concentration of 0.5 mol / L, adjusting a pH of the solution to 4 and filtering to obtain a filtrate; (3) Adding 1 g of potassium permanganate into the filtrate above, conducting a primary precipitation reaction and a solid-liquid separation to obtain manganese dioxide and a filtrate, adding a NaOH solution having a concentration of 1 mol / L into the filtrate to adjust a pH of the filtrate to 10, and introducing carbon dioxide, conducting a secondary precipitation reaction for 3 hours, and then conducting a solid-liquid separation to obtain a fluorine-containing solution and lithium carbonate; (4) Mixing 0.5 mol of NaNO3, 0.1 mol of Zr(NO3)4·5H2O and 1 g of glucose, adding the mixture to the fluorine-containing solution in step (3), stirring and reacting in a water bath at 30 °C for 24 hours and then calcining at 300 °C for 4 hours to obtain a Na 0,67 Zr a F b to obtain O2 material; and (5) Supply of Na 0,67 Zr a F bO2 material and manganese dioxide in step (3) into a muffle furnace for calcination at 300 °C for 12 hours and finally producing a sodium ion battery cathode material (Na 0,67 Mn 0.87 Zr 0,10 F 0,03 O2) with an α-MnO2 crystal form. Embodiment 2

[0028] A chemical formula of a sodium ion battery cathode material of this embodiment was Na 0,67 Mn 0,83 Zr 0,10 F 0,07 O2.

[0029] A manufacturing method of the sodium ion battery cathode material of this embodiment included the following steps: (1) Discharging and crushing a waste lithium manganate battery material and calcining at 900 °C for 2 hours to obtain a battery powder; (2) Adding 12 g of the battery powder above into 100 mL of malic acid solution with a concentration of 1.5 mol / L and reacting for 12 hours, adding 1.5 g of iron powder, then adding a NaOH solution with a concentration of 0.5 mol / L, adjusting a pH of the solution to 4 and filtering to obtain a filtrate; (3) Adding 1.5 g of potassium permanganate into the filtrate above, conducting a primary precipitation reaction and a solid-liquid separation to obtain manganese dioxide and a filtrate, adding a NaOH solution having a concentration of 1.5 mol / L into the filtrate to adjust a pH of the filtrate to 10, and introducing carbon dioxide, conducting a secondary precipitation reaction for 3 hours, and then conducting a solid-liquid separation to obtain a fluorine-containing solution and lithium carbonate; (4) Mixing 0.6 mol of Na2SO4, 0.1 mol of Zr(NO3)4-5H2O and 1.5 g of glucose, adding the mixture to the fluorine-containing solution in step (3), stirring and reacting in a water bath at 30 °C for 24 hours and then calcining at 300 °C for 4 hours to obtain a Na 0,67 Zr a F b to obtain O2 material; and (5) Supply of Na 0,67 Zr a F b O2 material and manganese dioxide in step (3) into a muffle furnace for calcination at 300 °C for 12 hours and finally producing a sodium ion battery cathode material (Na 0,67 Mn 0,83 Zr 0,10 F 0,07 O2) with an α-MnO2 crystal form. Embodiment 3

[0030] A chemical formula of a sodium ion battery cathode material of this embodiment was Na 0,67 Mn 0,8 Zr 0,1 F 0,1 O2.

[0031] A manufacturing method of the sodium ion battery cathode material of this embodiment included the following steps: (1) Discharging and crushing a waste lithium manganate battery material and calcining at 900 °C for 2 hours to obtain a battery powder; (2) Adding 14 g of the battery powder above into 100 mL of malic acid solution with a concentration of 2 mol / L and reacting for 12 hours, adding 2 g of iron powder, then adding a NaOH solution with a concentration of 0.5 mol / L, adjusting a pH of the solution to 4 and filtering to obtain a filtrate; (3) Adding 1.5 g of potassium permanganate to the filtrate above, conducting a primary precipitation reaction and solid-liquid separation to obtain manganese dioxide and a filtrate, adding a NaOH solution having a concentration of 2 mol / L to the filtrate to adjust the pH of the filtrate to 10, and introducing carbon dioxide, conducting a secondary precipitation reaction for 3 hours, and then conducting a solid-liquid separation to obtain a fluorine-containing solution and lithium carbonate; (4) Mixing 0.6 mol of NaNO3, 0.1 mol of Zr(NO3)4·5H2O and 2.5 g of glucose, adding the mixture to the fluorine-containing solution in step (3), stirring and reacting in a water bath at 30 °C for 24 hours and then calcining at 300 °C for 4 hours to obtain a Na 0,67 Zr a F b to obtain O2 material; and (5) Supply of Na 0,67 Zr a F bO2 material and manganese dioxide in step (3) into a muffle furnace for calcination at 300 °C for 12 hours and finally producing a sodium ion battery cathode material (Na 0,67 Mn 0,8 Zr 0,1 F 0,1 O2) with an α-MnO2 crystal form. Embodiment 4

[0032] A chemical formula of a sodium ion battery cathode material of this embodiment was Na 0,67 Mn 0,75 Zr 0,1 F 0,15 .

[0033] A manufacturing method of the sodium ion battery cathode material of this embodiment included the following steps: (1) Discharging and crushing a waste lithium manganate battery material and calcining at 900 °C for 2 hours to obtain a battery powder; (2) Adding 16 g of the battery powder above into 100 mL of malic acid solution with a concentration of 2.5 mol / L and reacting for 12 hours, adding 2 g of iron powder to stir, then adding a NaOH solution with a concentration of 0.5 mol / L, adjusting a pH of the solution to 4 and filtering to remove iron and aluminum, and obtaining a filtrate; (3) Adding 2 g of potassium permanganate into the filtrate above, conducting a primary precipitation reaction and a solid-liquid separation to obtain manganese dioxide and a filtrate, adding a NaOH solution having a concentration of 2 mol / L into the filtrate to adjust a pH of the filtrate to 10, and introducing carbon dioxide, conducting a secondary precipitation reaction for 3 hours, and then conducting a solid-liquid separation to obtain a fluorine-containing solution and lithium carbonate; (4) Mixing 0.7 mol of NaNO3, 0.1 mol of Zr(NO3)4·5H2O and 2 g of glucose, adding the mixture to the fluorine-containing solution in step (3), stirring and reacting in a water bath at 30 °C for 24 hours and then calcining at 300 °C for 4 hours to obtain a Na 0,67 Zr a F b to obtain O2 material; and (5) Supply of Na 0,67 Zr a F b O2 material and manganese dioxide in step (3) into a muffle furnace for calcination at 300 °C for 12 hours and finally producing a sodium ion battery cathode material (Na 0,67 Mn 0,75 Zr 0,1 F 0,15 ) with an α-MnO2 crystal form. Embodiment 5

[0034] The chemical formula of a sodium ion battery cathode material of this embodiment was Na 0,67 Mn 0,7 Zr 0,1 F 0,2 O2.

[0035] A manufacturing method of the sodium ion battery cathode material of this embodiment included the following steps: (1) Discharging and crushing a waste lithium manganate battery material and calcining at 800 °C for 5 hours to obtain a battery powder and an electrode plate powder; (2) Adding 18 g of the battery powder above into 100 mL of citric acid solution with a concentration of 2 mol / L and reacting for 10 hours, adding an iron powder, then adding a NaOH solution with a concentration of 2 mol / L, adjusting a pH of the solution to 4 and filtering to obtain a filtrate and a filter residue; (3) Adding 3 g of potassium permanganate into the filtrate above, conducting a primary precipitation reaction and a solid-liquid separation to obtain manganese dioxide and a filtrate, adding a NaOH solution having a concentration of 2 mol / L into the filtrate to adjust a pH of the filtrate to 10, and introducing carbon dioxide, conducting a secondary precipitation reaction for 6 hours, and then conducting a solid-liquid separation to obtain a fluorine-containing solution and lithium carbonate; (4) Mixing 0.75 mol of Na2CO3, 0.1 mol of Zr(NO3)4·5H2O and 3 g of glucose, adding the mixture to the fluorine-containing solution in step (3), stirring and reacting in a water bath at 55 °C for 18 hours and then calcining at 400 °C for 8 hours to obtain a Na 0,67 Zr a F b to obtain O2 material; and (5) Supply of Na 0,67 Zr a F bO2 material and manganese dioxide in step (3) into a muffle furnace for calcination at 400 °C for 9 hours and finally producing a sodium ion battery cathode material (Na 0,67 Mn 0,7 Zr 0,1 F 0,2 O2) with an α-MnO2 crystal form. Comparison example 1

[0036] The chemical formula of a sodium ion battery cathode material of this comparative example was Na 0.67 Mn 0.87 F 0.13 O2.

[0037] The preparation process of the sodium ion battery cathode material of this Comparative Example differed from Embodiment 1 in that no Zr(NO3)4·5H2O was added in step (4). Comparison example 2

[0038] The chemical formula of a sodium ion battery cathode material of the comparative example was Na 0,67 Mn 0,87 Zr 0,13 O2.

[0039] The manufacturing process of the sodium ion battery cathode material of this Comparative Example differed from Embodiment 1 in that no fluorine-containing solution was added to react in step (4) to produce Na 0,67 Zr a to receive O2. Comparison example 3

[0040] A chemical formula of the sodium ion battery cathode material of the comparative example was Na 0,67 MnO2. Analysis of Embodiments 1 to 4 and Comparative Examples 1 to 3: Table 1 Lattice parameters of the cathode materials under different conditions Sample type / lattice constant a (Å) b (Å) c (Å) Comparative example 3 Na 0,67 MnO2 9,0621 26,312 2,794 Comparative example 2 Na 0,67 Mn a Zr b O2 9,0814 26,426 2,814 Comparative example 1 Na 0,67 Mn a F3O2 9,0945 26,481 2,864 Embodiment 1 9,124 26,578 2,951 Embodiment 2 9,209 26,541 2,959 Embodiment 3 9,212 26,612 2,961 Embodiment 4 9,159 26,498 2,952 Embodiment 5 9,189 26,512 2,941

[0041] As shown in Table 1, when a raw material contains fluorine ions, the lattice constant of the raw material containing fluorine ions is larger than that of a raw material without fluorine ions, which proves that the fluorine ions can increase the distance from Na + Enlarge diffusion layers. Table 2 Physical properties of the cathode materials under different conditions Sample type Charge transfer impedance (Ω) Specific capacity (mAhg -1 ) Electronic conductivity (S / cm) Capacity after 100 cycles Capacity maintenance rate (%) NaMnO2 241 134 3,8*10 -6 128,6 96,1 Na 0,67 Mn 0,87 Zr 0,10 F 0,03 O2 198 151 4,5*10 -5 146,7 97,2 Na 0,67 Mn 0,83 Zr 0,10 F 0,07 O2 175 162 8,2*10 -4 156,9 96,9 Na 0,67 Mn 0,8 Zr 0,1 F 0,1 O2 152 172 9,1*10 -4 167,8 97,6 Na 0,67 Mn 0,75 Zr 0,1 F 0,15 O2 164 162 7,6*10 -4 157,4 97,2 Na 0,67 Mn 0,7 Zr 0,1 F 0,2 O2 180 158 6,9*10 -4 153,4 97,1

[0042] From the above table, it can be seen that Embodiments 1 to 5 of the present invention have high specific capacities, which are 172 mAhg -1 and can maintain high capacities even after 100 cycles, as well as exhibit good cycle performance and capacity retention rates.

[0043] Fig. 1 is a flowchart of an embodiment of the present invention. As can be seen from Fig.As shown in Figure 1, the battery powder is subjected to acid leaching to remove the black powder, then added with iron powder to remove copper, and then added with sodium carbonate to adjust the pH. After removing the iron and aluminum, potassium permanganate is added for reaction to obtain manganese dioxide and the filtrate. The pH of the filtrate is then adjusted, and carbon dioxide is introduced to precipitate lithium to obtain lithium carbonate and the fluorine-containing solution. Afterward, the sodium salt, zirconium salt, and complexing agent are added for reaction and sintering, and then mixed with manganese dioxide for calcination to obtain the sodium-ion battery anode material.

[0044] Fig. Figure 2 is an SEM diagram of Embodiment 1 of the present invention. Fig. 2 it can be seen that the particles have a uniform size and a smooth surface.

[0045] Fig. 3 is an SEM diagram of Embodiment 2 of the present invention. Fig. 3 it can be seen that the dosage change of the doped elements does not obviously affect the basic morphology of the material.

Claims

[1] A manufacturing method for a cathode material for sodium ion batteries, wherein the cathode material has a chemical formula Na 0,67 Mn a Zr b F c O2, where 0 <a<1, 0<b<1, 0<c<1 und a+b+c=1; wobei das Herstellungsverfahren die folgenden Schritte aufweist: (1) Subjecting a battery powder to acid leaching, adding a reducing agent into a material after acid leaching for reaction, adding an alkali to adjust a pH, subjecting a resulting mixture to a precipitation reaction, and then filtering the same to obtain a precipitate and a filtrate; (2) adding potassium permanganate into the filtrate, conducting a primary precipitation reaction and a solid-liquid separation to obtain manganese dioxide and a filtrate, adjusting a pH of the filtrate and introducing carbon dioxide, conducting a secondary precipitation reaction and a solid-liquid separation to obtain lithium carbonate and a fluorine-containing solution; (3) Adding a sodium source, a zirconium salt and a complexing agent into the fluorine-containing solution to react and sinter a reacted material to form a Na 0,67 Zr b F c to obtain O2 precursors; and (4) Mixing the Na 0,67 Zr b F c O2 precursor with the manganese dioxide in step (2) and calcining a resulting mixture to form the cathode material Na 0,67 Mn a Zr b F c to receive O2; wherein in step (1), the battery powder is obtained by subjecting a waste lithium manganate to discharge, crushing, high temperature calcination and sieving; wherein in step (1), an acid used for the acid leaching is at least one of malic acid and citric acid; wherein in step (3) the complexing agent is at least one of glucose and sucrose; and wherein in step (4) the calcination is carried out at a temperature of 300°C to 400°C for 6 hours to 12 hours. [2] The manufacturing method according to claim 1, wherein in step (1), the reducing agent is at least one of iron powder and aluminum powder. [3] The manufacturing method according to claim 1, wherein in step (2), a concentration ratio of manganese ions in the potassium permanganate to manganese ions in the filtrate is 2-3:

1. [4] The manufacturing method according to claim 1, wherein in step (3), the zirconium salt is at least one of zirconium nitrate, zirconium acetate and zirconium citrate. [5] The manufacturing method according to claim 1, wherein in step (3), the sodium source is at least one of Na2CO3, NaNO3 and Na2SO4.

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