CN116613294A - Sodium ion positive electrode material with low residual alkali content and preparation method thereof - Google Patents

Sodium ion positive electrode material with low residual alkali content and preparation method thereof Download PDF

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CN116613294A
CN116613294A CN202310749621.9A CN202310749621A CN116613294A CN 116613294 A CN116613294 A CN 116613294A CN 202310749621 A CN202310749621 A CN 202310749621A CN 116613294 A CN116613294 A CN 116613294A
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positive electrode
sodium
electrode material
sintering
equal
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张玉军
邵洪源
张洁
周春鹏
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Wanhua Chemical Sichuan Battery Material Technology Co ltd
Wanhua Chemical Yantai Battery Material Technology Co ltd
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Wanhua Chemical Sichuan Battery Material Technology Co ltd
Wanhua Chemical Yantai Battery Material Technology Co ltd
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    • C01G53/50—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese of the type [MnO2]n-, e.g. Li(NixMn1-x)O2, Li(MyNixMn1-x-y)O2
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Abstract

The invention provides a sodium ion positive electrode material with low residual alkali content and a preparation method thereof, and the structure is Na x Ni y Fe z Cu a Mn b M 1‑y‑z‑a‑b O 2 Wherein x is more than or equal to 0.70 and less than or equal to 1.20,y is more than 0 and less than or equal to 0.6,0, z is more than or equal to 0.4, a is more than 0 and less than or equal to 0.1, b is more than 0 and less than or equal to 0.4, y+z+a+b is less than or equal to 1, and M is one or more than one of Mg, ca, sr, zr, ti, W, B; the ratio of I (113)/I (018) in the XRD crystal structure of the sodium-electricity positive electrode material is between 0.7 and 1.2, and the ratio of FWHM (113)/FWHM (018) is between 1.2 and 1.8; the ratio of I (006)/I (101) is between 0.6 and 1.3, and the ratio of FWHM (006)/FWHM (101) is between 1.0 and 1.5. The sodium ion battery anode material prepared by the invention has excellent air stability, low residual alkali, stable processing performance and excellent electrochemical performance, and can be used for preparing a battery core within the humidity range of 10-30%.

Description

Sodium ion positive electrode material with low residual alkali content and preparation method thereof
Technical Field
The invention belongs to the technical field of sodium batteries, and particularly relates to a sodium ion positive electrode material with low residual alkali content and a preparation method thereof.
Background
The lithium ion battery has high energy density and is widely applied to the fields of new energy electric vehicles and energy storage; however, lithium resources are limited and expensive, so that lithium ion batteries are difficult to meet the increasing demands of new energy electric vehicles and energy storage. Because the sodium resources are abundant and the cost of the sodium resources is far lower than that of the lithium resources, and the sodium element and the lithium element have close electrochemical properties, the development of safe and high-performance sodium ion batteries is a future development direction
The sodium ion positive electrode material of the O3 type layered oxide has high discharge specific capacity, however, the sodium ion positive electrode material of the layered oxide has poor air stability, high residual alkali, difficult processing during the preparation of the battery, and great limitation on the application of the sodium ion battery, so that the improvement of the stability of the sodium ion positive electrode material is important.
Patent CN114725357a discloses a method for reducing sodium ion positive electrode material, which is to mix an acidic solution with the positive electrode material to reduce residual alkali of the positive electrode material, but washing the positive electrode material by the acidic solution can cause surface damage of the positive electrode material, dissolution of transition metal, damage of the structure of the positive electrode material, and excessively rapid performance decay in the circulation process.
Disclosure of Invention
In order to solve the problems, the invention provides a sodium ion positive electrode material with low residual alkali content and a preparation method thereof, and researches show that the sodium ion positive electrode material can be beneficial to the removal of sodium ions in a specified range of controlling the specific position ratio in the XRD crystal structure of the sodium ion positive electrode material, effectively inhibit the occurrence of irreversible phase change and improve the structural stability of the material. The preparation method provided by the invention adopts 2 precursors with different particle diameters to be sintered and mixed independently, and excellent crystal structure can be obtained by controlling conditions such as sintering, cladding and the like; the sodium ion battery obtained by the preparation method has a specific XRD crystal structure, improves the surface stability of the sodium ion positive electrode material, prevents side reaction with electrolyte and dissolution of metal ions, and has lower residual alkali content.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
a sodium ion positive electrode material with low residual alkali content has a structure of Na x Ni y Fe z Cu a Mn b M 1-y-z-a-b O 2 Wherein x is more than or equal to 0.70 and less than or equal to 1.20,0, y is more than or equal to 0.6,0 and less than or equal to 0.4, z is more than or equal to 0 and less than or equal to 0.1, b is more than or equal to 0 and less than or equal to 0.4, and y+z+a+b is less than 1, and M is selected from one or more of Mg, ca, sr, zr, ti, W, B.
Preferably, the positive electrode material is coated with aluminum;
preferably, the positive electrode material is further coated with phosphate.
The ratio of I (113)/I (018) in the XRD crystal structure of the sodium-electricity positive electrode material is between 0.7 and 1.2, and the ratio of FWHM (113)/FWHM (018) is between 1.2 and 1.8; the ratio of I (006)/I (101) is between 0.6 and 1.3, and the ratio of FWHM (006)/FWHM (101) is between 1.0 and 1.5; the ratio of the sum of peak intensities of the hybrid peaks between 38 DEG and 39 DEG to I (012) is less than 0.2; no NiO hetero-peaks between 40-45 deg..
The layered positive electrode material of O3 phase changes phase in the circulation process, and is changed from O3 phase to irreversible P3 phase, and research shows that when I (113)/I (018), I (006)/I (101), FWHM (113)/FWHM (018) and FWHM (006)/FWHM (101) are in a specified range, the release of sodium ions can be facilitated, the irreversible phase change can be effectively inhibited, and the structural stability of the material is improved. When the ratio of the sum of peak intensities of the hetero peaks between 38 degrees and 39 degrees to I (102) is smaller than 0.2, the Cu element in the material is stabilized in the material and no precipitation exists; the 40-45 DEG no impurity peak shows that the surface of the positive electrode material has no impurity peak of rock salt phase, and the stability of the material is further improved.
The positive electrode material is placed in water and stirred for 5 minutes, and the shape of the positive electrode material is kept spherical and is free from dissociation; the main peaks of (003) and (104) in the XRD pattern remain intact without disappearance.
In a specific embodiment, the sodium-electric positive electrode material has a pH of 12.3 or less; naOH (ethanol is solvent) remained on the surface is less than or equal to 500ppm; na (Na) 2 CO 3 ≤10000ppm；H 2 O is less than or equal to 200ppm; after the positive electrode material is exposed to an environment with humidity of 30% for 4 hours, H 2 O≤400ppm。
The invention also provides a preparation method of the sodium ion positive electrode material with low residual alkali content, which comprises the following steps:
step 1): 2 nickel-iron-copper-manganese precursors with different granularities are selected;
step 2): 2 nickel-iron-copper-manganese precursors with different particle sizes are respectively mixed with a sodium source and optional M compounds according to a certain proportion, and the mixture is sintered, wherein the whole sintering process comprises three steps; the first step is sintering under the condition of temperature T1 in oxygen or compressed air atmosphere; step two, raising the temperature to T2 for sintering; thirdly, reducing the temperature to T3 for sintering to obtain a sodium-electricity anode material of 2 granularity matrixes;
step 3): adding the 2 matrix sodium-electricity anode materials obtained in the step 2) and Al compounds into a high-speed mixer respectively, fully mixing and sintering at a certain temperature to obtain an Al-coated sodium-electricity anode material;
step 4): and (3) respectively mixing the 2 positive electrode materials obtained in the step (3) with phosphate, and then sintering at a certain temperature to obtain 2 phosphate-coated sodium-electricity positive electrode materials with low residual alkali content.
Step 5): and uniformly mixing the obtained 2 sodium electric positive electrode materials with different granularities according to a certain mass ratio to obtain the sodium electric positive electrode material with low residual alkali content.
In a specific embodiment, provided that the particle sizes of the 2 different particle size precursors in step 1) are Y1 and Y2, respectively
a) The D50 of Y1 is 2-7um, preferably 3-6um; BET of 5-25m 2 /g, preferably 10-20m 2 /g; the particle size distribution (D90-D10)/D50 is 0.4 to 1.0, preferably 0.5 to 0.9;
b) The D50 of Y2 is 8-18um, preferably 10-16um; BET of 5-20m 2 Preferably 8-18m 2 /g; the particle size distribution (D90-D10)/D50 is from 0.1 to 0.6, preferably from 0.2 to 0.5.
In a specific embodiment, the precursor of nickel, iron, copper and manganese has a structure of Ni y Fe z Cu a Mn b (OH) 2 Wherein y is more than 0 and less than or equal to 0.6,0, z is more than 0 and less than or equal to 0.4, a is more than 0 and less than or equal to 0.1, and b is more than 0 and less than or equal to 0.4.
In a specific embodiment, the sodium source is added in step 2) in a molar ratio Na: me=0.7-1.2:1, where Me is the sum of the molar amounts of Ni, fe, cu, mn; more preferably, the sodium source is selected from any one or more of sodium carbonate, sodium hydroxide, sodium oxalate or sodium acetate.
In a specific embodiment, the M-containing compound in step 2) is selected from one or more of Mg, ca, sr, zr, ti, W, B; preferably, the compound of M is incorporated in an amount of 0-1.0% by mass of the total metal of nickel, iron, copper, manganese, preferably the compound of M is incorporated in an amount other than 0.
In a specific embodiment, the atmosphere in step 2) is compressed air or oxygen, the sintering temperature T1 is 600-900 ℃, and the sintering time is 3-6 hours; the sintering temperature T2 is 800-1000 ℃ and the sintering time is 8-15h; the sintering temperature T3 is 400-700 ℃ and the sintering time is 2-4h.
Preferably, the sintering temperature T2 is greater than T1.
In a specific embodiment, the compound of step 3) aluminum is one or more of aluminum oxide, aluminum hydroxide, aluminum chloride, or aluminum nitrate; the coating amount of Al is 0.05-0.3% of the mass of the sodium-electricity anode material obtained in the step 2), the sintering temperature is 300-700 ℃, and the sintering time is 5-10h.
In a specific embodiment, step 4) the phosphate is NaFePO 4 、Na 3 V 2 (PO4) 3 Any one of them; the coating amount of the phosphate is 0.05-0.5% of the mass of the Al-coated sodium-electricity positive electrode material obtained in the step 3), and the material is burnedThe junction temperature is 400-800 ℃, and the sintering time is 5-10h.
In a specific embodiment, in step 5), the mass ratio Y2 of the phosphate coated low residual alkali content sodium electric positive electrode material prepared from the precursor with the particle size of Y2 to the phosphate coated low residual alkali content sodium electric positive electrode material prepared from the precursor with the particle size of Y1 is: y1 is 2-5:1.
In a specific embodiment, the slurry viscosity is less than or equal to 800 mpa.s and has fluidity during the process of making the sodium electric positive electrode material into a battery; after standing for 24 hours, the viscosity of the slurry is less than or equal to 10000 Pa.s, and the slurry has fluidity; the discharge capacity of 0.2C is more than 130mAh/g in the half cell 2.0-4.0V, and the average voltage is more than 3.0V.
Compared with the prior art, the invention has the following beneficial effects:
the research of the invention finds that: i (006)/I (101) and FWHM (006)/FWHM (101) in XRD crystal structure are in proper range, the sodium layer spacing is proper, the extraction of sodium ions is facilitated, and the capacity is high; i (113)/I (018) and FWHM (113)/FWHM (018) are in proper ranges, the irreversible phase change can be effectively inhibited in the circulation process, and the obtained sodium ion battery material is more stable in structure and lower in residual alkali content; according to the invention, 2 precursors with different particle diameters are preferably sintered with a sodium source respectively, and the optimal sodium proportion and sintering temperature of the precursors with different particle diameters are adjusted, so that the specific crystal structure of the invention can be obtained; through the co-doping of metal elements of the metal layer and the sodium layer and the cladding of aluminum and phosphate, the sodium-ion anode material with stable low residual alkali content is prepared, which is favorable for obtaining proper I (006)/I (101) value and FWHM (006)/FWHM (101) value, improves the stability of the sodium layer, prevents side reaction with electrolyte and dissolution of metal ions.
The sodium ion positive electrode material has high air stability, low residual alkali and excellent electrical property, and can be used for processing slurry at the ambient humidity of 30%.
Drawings
Fig. 1 is an SEM image of the positive electrode material prepared in example 1 of the present invention after washing.
Fig. 2 is an SEM image of the positive electrode material prepared in comparative example 1 after washing with water.
Fig. 3 is an XRD pattern after washing of the positive electrode material prepared in example 1 of the present invention.
Fig. 4 is an XRD pattern after washing the positive electrode material prepared in comparative example 1.
Fig. 5 is a graph showing the moisture growth tendency of the positive electrode materials prepared in example 1 and comparative example 1 according to the present invention when exposed to an environment having a humidity of 30%.
Detailed Description
The following examples will further illustrate the method provided by the present invention, but the invention is not limited to the examples listed and should also include any other known modifications within the scope of the claims.
Residual alkali: equipment model: 905, manufacturer: swiss Wantong; the method comprises the following steps: GB/T41704-2022
Moisture content: equipment model: 851+860, manufacturer: swiss Wantong; the method comprises the following steps: GB/T6283-2008
XRD: equipment model: aerodes; the manufacturer: malvern panaceae (Panac)
A method for preparing a stable low residual alkali content positive electrode material of a sodium ion battery, comprising the following steps:
1) 2 nickel-iron-copper-manganese precursors (Y1 and Y2) with different granularities are selected;
2) Step 2: 2 nickel-iron-copper-manganese precursors with different granularities are respectively mixed with a compound of M and a sodium source according to a certain proportion, and the mixture is sintered, and the whole sintering process is divided into three steps; the first step is sintering under the atmosphere and the temperature T1; step two, raising the temperature to T2 for sintering; thirdly, reducing the temperature to T3 for sintering to obtain sodium-electricity anode materials of 2 matrixes with different particle diameters;
3) Step 3: adding the 2 matrix sodium-electricity anode materials obtained in the step 2 and Al compounds into a high-speed mixer respectively, fully mixing and sintering at a certain temperature to obtain an Al-coated sodium-electricity anode material;
4) Step 4: and (3) respectively adding the 2 positive electrode materials obtained in the step (3) and sodium phosphate (NaXPO 4) into a high-speed mixture, fully mixing, and sintering at a certain temperature to obtain 2 phosphate-coated stable sodium-electricity positive electrode materials with low residual alkali content.
5) Step 5: and uniformly mixing the obtained 2 sodium electric positive electrode materials with different granularities according to a certain mass ratio to obtain the final sodium electric positive electrode material with low residual alkali content.
The invention is further illustrated, but not limited, by the following more specific examples.
Example 1
1) 100g of Y1 Ni were weighed out 0.23 Fe 0.33 Cu 0.10 Mn 0.34 (OH) 2 Precursor, particle size D50 of 3.5um, (D90-D10)/D50 of 0.96, sodium carbonate and precursor powder were added into a ball mill in a molar ratio of Na/(Ni+Fe+Cu+Mn) =1.00:1, then MgO with precursor mass of 0.1% and CaCO with doping amount of 0.6% of precursor mass were added 3 Mixing in a ball mill. Sintering at 800 ℃ for 240min in an air atmosphere, heating to 900 ℃ for 600min, cooling to 600 ℃ for 180min, and obtaining the doped anode material.
Al of 0.1% of the mass of the positive electrode material is doped 2 O 3 Mixing with the doped matrix in a ball mill, and sintering at 600 ℃ for 480min in an air atmosphere to obtain the Al-coated anode material.
NaFePO of 0.2% of the mass of the Al-coated cathode material 4 Adding the mixture and the Al-coated positive electrode material into a ball mill for mixing, and sintering at 700 ℃ for 360min in an air atmosphere to obtain the final positive electrode material 1.
2) 100g of Y2 Ni was weighed out 0.23 Fe 0.33 Cu 0.10 Mn 0.34 (OH) 2 Precursor, particle size D50 of 10.5um, (D90-D10)/D50 of 0.42, sodium carbonate and precursor powder were mixed according to a molar ratio of Na/(Ni+Fe+Cu+Mn) =1.00:1, mgO with doping amount of 0.1% of the precursor mass and CaCO with doping amount of 0.6% of the precursor mass 3 Adding into a ball mill for mixing. Sintering at 800 ℃ for 240min in an air atmosphere, heating to 920 ℃ for 600min, cooling to 600 ℃ for 180min, and obtaining the doped anode material.
Al of 0.1% of the mass of the positive electrode material is doped 2 O 3 Mixing with the doped matrix in a ball mill, and sintering at 600 ℃ for 480min in an air atmosphere to obtain the Al-coated anode material.
NaFePO of 0.2% of the mass of the Al-coated cathode material 4 Adding the mixture and the Al-coated positive electrode material into a ball mill for mixing, and sintering at 700 ℃ for 360min in an air atmosphere to obtain the final positive electrode material 2.
3) And mixing the positive electrode material 2 and the positive electrode material 1 according to a mass ratio of 8:2 to obtain the stable positive electrode material with low residual alkali content.
4) The physical and chemical performance index of the prepared positive electrode material is PH 11.95; 215ppm of NaOH; na (Na) 2 CO 3 :4783ppm；H 2 O is 136ppm; h after 4H of exposure under 30% humidity environment 2 O is 312ppm; i (113)/I (018): 0.9; FWHM (113)/FWHM (018): 1.6; i (006)/I (101): 1.0; FWHM (006)/FWHM (101): 1.1; the sum of peak intensities of the hetero peaks between 38 DEG and 39 DEG is equal to I (012): 0.08. (test methods feedback above)
5) The positive electrode material was fabricated into a button cell and its performance was tested. Slurry viscosity 6100mpa.s; the metal sodium sheet is used as a negative electrode to assemble a 2032 button cell, and a new Weibull button electrical testing system (the name is replaced and button electrical testing equipment manufacturers are not unique) is adopted to perform electrical performance testing (the charge and discharge voltages are respectively 2.00-4.00V).
The result shows that the discharge capacity of the positive electrode material with low residual alkali content at 0.2C is 145mAh/g, and the initial effect at 0.2C is 94.3%.
After the anode material is placed in water and stirred for 5 minutes, the shape of the anode material is kept spherical and no dissociation exists; the main peaks of (003) and (104) in the XRD pattern remain intact without disappearance.
Comparative example 1
1) 100g of Y1 Ni was weighed out 0.23 Fe 0.33 Cu 0.10 Mn 0.34 (OH) 2 The precursor, particle size D50 is 3.5um, (D90-D10)/D50 is 0.96, sodium carbonate and precursor powder are added to a ball mill to mix according to a molar ratio Na/(ni+fe+cu+mn) =1.00:1. Sintering at 800 ℃ for 240min in an air atmosphere, heating to 900 ℃ for 600min, cooling to 600 ℃ for 180min, and obtaining the anode material.
Mass of positive electrode material0.1% Al of 2 O 3 Mixing with the matrix, adding into a ball mill, and sintering at 600 ℃ for 480min in an air atmosphere to obtain the Al-coated anode material.
NaFePO of 0.2% of the mass of the Al-coated cathode material 4 Adding the mixture and the Al-coated positive electrode material into a ball mill for mixing, and sintering at 700 ℃ for 360min in an air atmosphere to obtain the final positive electrode material 1.
2) Weigh 100gY Ni 0.23 Fe 0.33 Cu 0.10 Mn 0.34 (OH) 2 The precursor, particle size D50 of 10.5um, (D90-D10)/D50 of 0.42, was mixed with sodium carbonate in a ball mill at Na/(ni+fe+cu+mn) =1.00:1. Sintering at 800 ℃ for 240min in an air atmosphere, heating to 920 ℃ for 600min, cooling to 600 ℃ for 180min, and obtaining the anode material.
Al in an amount of 0.1% by mass of the positive electrode material 2 O 3 Mixing with the matrix, adding into a ball mill, and sintering at 600 ℃ for 480min in an air atmosphere to obtain the Al-coated anode material.
Coating NaFePO with the mass of 0.2% of the mass of the Al-coated positive electrode material 4 Adding the mixture and the Al-coated positive electrode material into a ball mill for mixing, and sintering at 700 ℃ for 360min in an air atmosphere to obtain the final positive electrode material 2.
3) And mixing the positive electrode material 2 and the positive electrode material 1 according to a mass ratio of 8:2 to obtain the positive electrode material with low residual alkali content.
4) The physical and chemical performance index of the prepared positive electrode material is PH 12.65; 783ppm NaOH; na (Na) 2 CO 3 :9346ppm；H 2 421ppm of O; h after 4H of exposure under 30% humidity environment 2 852ppm of O; i (113)/I (018): 0.6; FWHM (113)/FWHM (018): 1.9; i (006)/I (101): 0.5; FWHM (006)/FWHM (101): 1.7; the sum of peak intensities of the hetero peaks between 38 DEG and 39 DEG is equal to I (012): 0.21.
5) The positive electrode material was fabricated into a button cell and its performance was tested. The viscosity of the slurry was 8300mPa.s; the metal sodium sheet is used as a negative electrode to assemble a 2032 button cell, and a new Weibull button electrical test system is adopted to perform electrical property test (the charge and discharge voltages are respectively 2.00-4.00V).
The result shows that the discharge capacity of the positive electrode material with low residual alkali content at 0.2C is 137mAh/g, and the initial effect at 0.2C is 92.6%.
Example 2
1) Weigh 100Y1 Ni 0.27 Fe 0.33 Cu 0.06 Mn 0.34 (OH) 2 Precursor, particle size D50 of 4.0um, (D90-D10)/D50 of 0.91 sodium carbonate and precursor powder are mixed according to mole ratio Na/(Ni+Fe+Cu+Mn) =0.99:1, doping amount of 0.1% MgO of precursor mass and doping amount of 0.8% CaCO of precursor mass 3 Adding into a ball mill for mixing. Sintering at 800 ℃ for 240min in an air atmosphere, heating to 900 ℃ for 600min, cooling to 600 ℃ for 180min, and obtaining the doped anode material.
0.2% of Al by mass of the doped cathode material 2 O 3 Mixing with the doped matrix in a ball mill, and sintering at 600 ℃ for 480min in an air atmosphere to obtain the Al-coated anode material.
NaFePO of 0.2% of the mass of the Al-coated cathode material 4 Adding the mixture and the Al-coated positive electrode material into a ball mill for mixing, and sintering at 700 ℃ for 360min in an air atmosphere to obtain the final positive electrode material 1.
2) Weigh 100gY Ni 0.27 Fe 0.33 Cu 0.06 Mn 0.34 (OH) 2 Precursor, particle size D50 of 11.0um, (D90-D10)/D50 of 0.47, sodium carbonate and precursor powder are mixed according to a molar ratio of Na/(Ni+Fe+Cu+Mn) =0.99:1, wherein doping amount is 0.1% MgO of precursor mass and doping amount is 0.8% CaCO of precursor mass 3 Adding into a ball mill for mixing. Sintering at 800 ℃ for 240min in an air atmosphere, heating to 920 ℃ for 600min, cooling to 600 ℃ for 180min, and obtaining the doped anode material.
Will dope Al of 0.2% of the mass of the positive electrode material 2 O 3 Mixing with the doped matrix in a ball mill, and sintering at 600 ℃ for 480min in an air atmosphere to obtain the Al-coated anode material.
Coating NaFePO with the mass of 0.2% of the mass of the Al-coated positive electrode material 4 Adding the mixture and the Al-coated positive electrode material into a ball mill for mixing, and sintering at 700 ℃ for 360min in an air atmosphere to obtain the final positive electrode material 2.
3) And mixing the positive electrode material 2 and the positive electrode material 1 according to a mass ratio of 8:2 to obtain the positive electrode material with low residual alkali content.
4) The physical and chemical performance index of the prepared positive electrode material is PH 12.07; naOH 287ppm; na (Na) 2 CO 3 :3283ppm；H 2 O is 187ppm; h after 4H of exposure under 30% humidity environment 2 O is 345ppm; i (113)/I (018): 1.05; FWHM (113)/FWHM (018): 1.47; i (006)/I (101): 0.92; FWHM (006)/FWHM (101): 1.18; the sum of peak intensities of the hetero peaks between 38 DEG and 39 DEG is equal to I (012): 0.06.
5) The positive electrode material was fabricated into a button cell and its performance was tested. The viscosity of the slurry was 6300mpa.s; the metal sodium sheet is used as a negative electrode to assemble a 2032 button cell, and a new Weibull button electrical test system is adopted to perform electrical property test (the charge and discharge voltages are respectively 2.00-4.00V).
The result shows that the discharge capacity of the positive electrode material with low residual alkali content at 0.2C is 146mAh/g, and the initial effect at 0.2C is 94.6%.
Comparative example 2
1) Weigh 100gY Ni 1 0.27 Fe 0.33 Cu 0.06 Mn 0.34 (OH) 2 The precursor, particle size D50 is 4.0um, (D90-D10)/D50 is 0.91, sodium carbonate and precursor powder are added to a ball mill according to a molar ratio Na/(ni+fe+cu+mn) =0.99:1 for mixing. Sintering at 800 ℃ for 240min in an air atmosphere, heating to 900 ℃ for 600min, cooling to 600 ℃ for 180min, and obtaining the anode material 1.
2) 100g of Y2 Ni was weighed out 0.27 Fe 0.33 Cu 0.06 Mn 0.34 (OH) 2 The precursor, particle size D50 of 11.0um, (D90-D10)/D50 of 0.47, was mixed by adding sodium carbonate and precursor powder in a molar ratio Na/(ni+fe+cu+mn) =0.99:1 to a ball mill. Sintering at 800 ℃ for 240min in an air atmosphere, heating to 920 ℃ for 600min, cooling to 600 ℃ for 180min, and obtaining the anode material 2.
3) And mixing the positive electrode material 2 and the positive electrode material 1 according to a mass ratio of 8:2 to obtain the positive electrode material with low residual alkali content.
4) The physical and chemical performance index of the prepared positive electrode material is PH 13.15; naOH 984ppm；Na 2 CO 3 :8783ppm H 2 O is 534ppm; h after 4H of exposure under 30% humidity environment 2 975ppm of O; i (113)/I (018): 1.27; FWHM (113)/FWHM (018): 1.16; i (006)/I (101): 1.34; FWHM (006)/FWHM (101): 0.93; the sum of peak intensities of the hetero peaks between 38 DEG and 39 DEG is equal to I (012): 0.23.
5) The positive electrode material was fabricated into a button cell and its performance was tested. The slurry viscosity was 9400mpa.s; the metal sodium sheet is used as a negative electrode to assemble a 2032 button cell, and a new Weibull button electrical test system is adopted to perform electrical property test (the charge and discharge voltages are respectively 2.00-4.00V).
The result shows that the discharge capacity of the positive electrode material with low residual alkali content at 0.2C is 132mAh/g, and the initial effect at 0.2C is 91.9%.
Example 3
1) 100g of Ni with a particle size D50 of 3.0umY1 was weighed out 0.23 Fe 0.33 Cu 0.10 Mn 0.34 (OH) 2 Precursor, particle size D50 is 3.0um, (D90-D10)/D50 is 0.93, sodium carbonate and precursor powder are mixed according to mole ratio Na/(Ni+Fe+Cu+Mn) =1.00:1, and doping amount is precursor mass 0.1% MgO, 0.2% ZrO 2 And a doping level of 0.6% CaCO based on the precursor mass 3 Adding into a ball mill for mixing. Sintering at 800 ℃ for 240min in an air atmosphere, heating to 900 ℃ for 600min, cooling to 600 ℃ for 180min, and obtaining the doped anode material.
Al of 0.1% of the mass of the positive electrode material is doped 2 O 3 Mixing with the doped matrix in a ball mill, and sintering at 600 ℃ for 480min in an air atmosphere to obtain the Al-coated anode material.
Coating NaFePO with the mass of 0.2% of the mass of the Al-coated positive electrode material 4 Adding the mixture and the Al-coated positive electrode material into a ball mill for mixing, and sintering at 700 ℃ for 360min in an air atmosphere to obtain the final positive electrode material 1.
2) 100g of Y2 Ni was weighed out 0.23 Fe 0.33 Cu 0.10 Mn 0.34 (OH) 2 Precursor, particle size D50 of 11.5um, (D90-D10)/D50 of 0.44, sodium carbonate and precursor powder are mixed according to mole ratio Na/(Ni+Fe+Cu+Mn) =1.00:1, and doping amount is precursor mass of 0.1% MgO, 0.2% ZrO 2 And a doping level of 0.6% CaCO based on the precursor mass 3 Adding into a ball mill for mixing. Sintering at 800 ℃ for 240min in an air atmosphere, heating to 920 ℃ for 600min, cooling to 600 ℃ for 180min, and obtaining the doped anode material.
0.1% of Al by mass of the doped cathode material 2 O 3 Mixing with the doped matrix in a ball mill, and sintering at 600 ℃ for 480min in an air atmosphere to obtain the Al-coated anode material.
NaFePO of 0.2% of the mass of the Al-coated cathode material 4 Adding the mixture and the Al-coated positive electrode material into a ball mill for mixing, and sintering at 700 ℃ for 360min in an air atmosphere to obtain the final positive electrode material 2.
3) And mixing the positive electrode material 2 and the positive electrode material 1 according to a mass ratio of 8:2 to obtain the positive electrode material with low residual alkali content.
4) The physical and chemical performance index of the prepared positive electrode material is PH 11.89; naOH 247ppm; na (Na) 2 CO 3 :4361ppm H 2 O is 148ppm; h after 4H of exposure under 30% humidity environment 2 O is 300ppm; i (113)/I (018): 1.10; FWHM (113)/FWHM (018): 1.39; i (006)/I (101): 1.05; FWHM (006)/FWHM (101): 1.09; the sum of peak intensities of the hetero peaks between 38 DEG and 39 DEG is equal to I (012): 0.07.
5) The positive electrode material was fabricated into a button cell and its performance was tested. The viscosity of the slurry was 5900mpa.s; the metal sodium sheet is used as a negative electrode to assemble a 2032 button cell, and a new Weibull button electrical test system is adopted to perform electrical property test (the charge and discharge voltages are respectively 2.00-4.00V).
The result shows that the discharge capacity of the positive electrode material with low residual alkali content at 0.2C is 143mAh/g, and the initial effect at 0.2C is 94.5%.
Comparative example 3
1) Weigh 100gY Ni 1 0.23 Fe 0.33 Cu 0.10 Mn 0.34 (OH) 2 Precursor, particle size D50 is 3.0um, (D90-D10)/D50 is 0.93, sodium carbonate and precursor powder are mixed according to mole ratio Na/(Ni+Fe+Cu+Mn) =1.00:1, and doping amount is precursor mass 0.1% MgO, 0.2% ZrO 2 And a doping level of 0.6% CaCO based on the precursor mass 3 Adding into a ball mill for mixing. In the airSintering at 800 ℃ for 240min in the atmosphere of gas, heating to 900 ℃ for 600min, cooling to 600 ℃ for 180min, and obtaining the doped anode material.
Al in an amount of 0.1% by mass of the positive electrode material 2 O 3 Mixing with the doped matrix in a ball mill, and sintering at 600 ℃ for 480min in an air atmosphere to obtain the Al-coated anode material 1.
2) Weigh 100gY Ni 0.23 Fe 0.33 Cu 0.10 Mn 0.34 (OH) 2 Precursor, particle size D50 of 11.5um, (D90-D10)/D50 of 0.44, sodium carbonate and precursor powder were mixed in an amount of Na/(Ni+Fe+Cu+Mn) =1.00:1, and doping amount of 0.1% MgO, 0.2% ZrO 2 And a doping level of 0.6% CaCO 3 Adding into a ball mill for mixing. Sintering at 800 ℃ for 240min in an air atmosphere, heating to 900 ℃ for 600min, cooling to 600 ℃ for 180min, and obtaining the doped anode material.
Al in an amount of 0.1% by mass of the positive electrode material 2 O 3 Mixing with the doped matrix in a ball mill, and sintering at 600 ℃ for 480min in an air atmosphere to obtain the Al-coated anode material 2.
3) And mixing the positive electrode material 2 and the positive electrode material 1 according to a mass ratio of 8:2 to obtain the positive electrode material with low residual alkali content.
4) The physical and chemical performance index of the prepared positive electrode material is PH 12.37; naOH 421ppm; na (Na) 2 CO 3 :8545ppm H 2 O is 214ppm; h after 4H of exposure under 30% humidity environment 2 423ppm of O; i (113)/I (018): 1.36; FWHM (113)/FWHM (018): 1.12; i (006)/I (101): 1.42; FWHM (006)/FWHM (101): 0.89; the sum of peak intensities of the hetero peaks between 38 DEG and 39 DEG is equal to I (012): 0.22.
5) The positive electrode material was fabricated into a button cell and its performance was tested. The viscosity of the slurry was 7200mPa.s; the metal sodium sheet is used as a negative electrode to assemble a 2032 button cell, and a new Weibull button electrical test system is adopted to perform electrical property test (the charge and discharge voltages are respectively 2.00-4.00V).
The result shows that the discharge capacity of the positive electrode material with low residual alkali content at 0.2C is 137mAh/g, and the initial effect at 0.2C is 93.2%.
Example 4
1) 100g of Y1 Ni was weighed out 0.27 Fe 0.33 Cu 0.06 Mn 0.34 (OH) 2 Precursor, particle size D50 is 5.0um (D90-D10)/D50 is 0.89, sodium carbonate and precursor powder are mixed according to mole ratio of Na/(Ni+Fe+Cu+Mn) =0.99:1, and doping amount is 0.1% MgO and 0.1% TiO of precursor mass 2 And CaCO with doping amount of 0.8% of the mass of the precursor 3 Adding into a ball mill for mixing. Sintering at 800 ℃ for 240min in an air atmosphere, heating to 900 ℃ for 600min, cooling to 600 ℃ for 180min, and obtaining the doped anode material.
0.1% of Al by mass of the doped cathode material 2 O 3 Mixing with the doped matrix in a ball mill, and sintering at 600 ℃ for 480min in an air atmosphere to obtain the Al-coated anode material.
NaFePO of 0.2% of the mass of the Al-coated cathode material 4 Adding the mixture and the Al-coated positive electrode material into a ball mill for mixing, and sintering at 700 ℃ for 360min in an air atmosphere to obtain the final positive electrode material 1.
2) 100g of Y2 Ni was weighed out 0.27 Fe 0.33 Cu 0.06 Mn 0.34 (OH) 2 Precursor, particle size D50 is 12.0um, (D90-D10)/D50 is 0.43, sodium carbonate and precursor powder are mixed according to a molar ratio of Na/(Ni+Fe+Cu+Mn) =0.99:1, and doping amount is 0.1% MgO, 0.1% TiO2 and doping amount is 0.8% CaCO of precursor mass 3 Adding into a ball mill for mixing. Sintering at 800 ℃ for 240min in an air atmosphere, heating to 920 ℃ for 600min, cooling to 600 ℃ for 180min, and obtaining the doped anode material.
0.1% of Al by mass of the doped cathode material 2 O 3 Mixing with the doped matrix in a ball mill, and sintering at 600 ℃ for 480min in an air atmosphere to obtain the Al-coated anode material.
NaFePO of 0.2% of the mass of the Al-coated cathode material 4 Adding the mixture and the Al-coated positive electrode material into a ball mill for mixing, and sintering at 700 ℃ for 360min in an air atmosphere to obtain the final positive electrode material 2.
3) And mixing the positive electrode material 2 and the positive electrode material 1 according to a mass ratio of 7:3 to obtain the positive electrode material with low residual alkali content.
4) The physical and chemical performance index of the prepared positive electrode material is PH 11.98; 263ppm of NaOH; na (Na) 2 CO 3 :3176ppm；H 2 O is 170ppm; h after 4H of exposure under 30% humidity environment 2 323ppm of O; i (113)/I (018): 1.01; FWHM (113)/FWHM (018): 1.38; i (006)/I (101): 0.87; FWHM (006)/FWHM (101): 1.23; the sum of peak intensities of the hetero peaks between 38 DEG and 39 DEG is equal to I (012): 0.05.
5) The positive electrode material was fabricated into a button cell and its performance was tested. Slurry viscosity 6100mpa.s; the metal sodium sheet is used as a negative electrode to assemble a 2032 button cell, and a new Weibull button electrical test system is adopted to perform electrical property test (the charge and discharge voltages are respectively 2.00-4.00V).
The result shows that the discharge capacity of the positive electrode material with low residual alkali content at 0.2C is 144mAh/g, and the initial effect at 0.2C is 94.8%.
Example 5
1) 100g of Y1 Ni was weighed out 0.20 Fe 0.30 Cu 0.10 Mn 0.40 (OH) 2 Precursor, particle size D50 is 3.5um, (D90-D10)/D50 is 0.90, sodium carbonate and precursor powder are mixed according to a molar ratio of Na/(Ni+Fe+Cu+Mn) =1.02:1, and the doping amount is MgO which is 0.1% of the mass of the precursor, and TiO which is 0.1% of the mass of the precursor 2 And CaCO with doping amount of 0.6% of the mass of the precursor 3 Adding into a ball mill for mixing. Sintering at 800 ℃ for 240min in an air atmosphere, heating to 900 ℃ for 600min, cooling to 600 ℃ for 180min, and obtaining the doped anode material.
0.1% of Al by mass of the doped cathode material 2 O 3 Mixing with the doped matrix in a ball mill, and sintering at 600 ℃ for 480min in an air atmosphere to obtain the Al-coated anode material.
NaFePO of 0.2% of the mass of the Al-coated cathode material 4 Adding the mixture and the Al-coated positive electrode material into a ball mill for mixing, and sintering at 700 ℃ for 360min in an air atmosphere to obtain the final positive electrode material 1.
2) 100g of Ni with a particle size D50 of 11.0umY2 was weighed out 0.20 Fe 0.30 Cu 0.10 Mn 0.40 (OH) 2 Precursor, particle size D50 of11.0um, (D90-D10)/D50 is 0.46, sodium carbonate and precursor powder are mixed according to a molar ratio of Na/(Ni+Fe+Cu+Mn) =1.02:1, and doping amount is 0.1% MgO, 0.1% TiO2 and doping amount is 0.6% CaCO of precursor mass 3 Adding into a ball mill for mixing. Sintering at 800 ℃ for 240min in an air atmosphere, heating to 920 ℃ for 600min, cooling to 600 ℃ for 180min, and obtaining the doped anode material.
0.1% of Al by mass of the doped cathode material 2 O 3 Mixing with the doped matrix in a ball mill, and sintering at 600 ℃ for 480min in an air atmosphere to obtain the Al-coated anode material.
NaFePO of 0.2% of the mass of the Al-coated cathode material 4 Adding the mixture and the Al-coated positive electrode material into a ball mill for mixing, and sintering at 700 ℃ for 360min in an air atmosphere to obtain the final positive electrode material 2.
3) And mixing the positive electrode material 2 and the positive electrode material 1 according to a mass ratio of 7:3 to obtain the positive electrode material with low residual alkali content.
4) The physical and chemical performance index of the prepared positive electrode material is PH 11.87; naOH 251ppm; na (Na) 2 CO 3 :4172ppm H 2 O is 184ppm; h after 4H of exposure under 30% humidity environment 2 O is 300ppm; i (113)/I (018): 1.07; FWHM (113)/FWHM (018): 1.43; i (006)/I (101): 0.93; FWHM (006)/FWHM (101): 1.28; the sum of peak intensities of the hetero peaks between 38 DEG and 39 DEG is equal to I (012): 0.06.
5) The positive electrode material was fabricated into a button cell and its performance was tested. The viscosity of the slurry was 6300mpa.s; the metal sodium sheet is used as a negative electrode to assemble a 2032 button cell, and a new Weibull button electrical test system is adopted to perform electrical property test (the charge and discharge voltages are respectively 2.00-4.00V).
The result shows that the discharge capacity of the positive electrode material with low residual alkali content at 0.2C is 142mAh/g, and the initial effect at 0.2C is 94.1%.
SEM after washing example 1 and comparative example 1 are shown in fig. 1, it can be seen that the morphology and structure of example 1 are stable.
XRD after washing example 1 and comparative example 1 as shown in fig. 2, it can be seen that the positive electrode material of example 1 has a stable crystal structure.
Example 1And comparative example 1H of the left-standing Material 2 O is as shown in FIG. 3, and it can be seen that example 1 is structurally stable.
The 0.2C discharge capacities of examples 1, 2, 3, 4, and 5 are shown in table 1, and the sodium-electricity positive electrode material was excellent in electrical properties.
Table 1 example capacity table in the 4.4V-4.75V charging voltage interval
While the present invention has been described in detail through the foregoing description of the preferred embodiment, it should be understood that the foregoing description is not to be considered as limiting the invention. Those skilled in the art will appreciate that certain modifications and adaptations of the invention are possible and can be made under the teaching of the present specification. Such modifications and adaptations are intended to be within the scope of the present invention as defined in the appended claims.

Claims (10)

1. A sodium ion positive electrode material with low residual alkali content is characterized in that the structure is Na x Ni y Fe z Cu a Mn b M 1-y-z-a- b O 2 Wherein x is more than or equal to 0.70 and less than or equal to 1.20,0, y is more than or equal to 0.6,0 and less than or equal to 0.4, z is more than or equal to 0 and less than or equal to 0.1, b is more than or equal to 0 and less than or equal to 0.4, y+z+a+b is more than or equal to 1, and M is selected from one or more of Mg, ca, sr, zr, ti, W, B;
the ratio of I (113)/I (018) in the XRD crystal structure of the sodium-electricity positive electrode material is between 0.7 and 1.2, and the ratio of FWHM (113)/FWHM (018) is between 1.2 and 1.8; the ratio of I (006)/I (101) is between 0.6 and 1.3, and the ratio of FWHM (006)/FWHM (101) is between 1.0 and 1.5.
2. The positive electrode material according to claim 1, wherein the ratio of the sum of peak intensities of the hetero peaks between 38 ° -39 ° to I (012) is less than 0.2; no NiO hetero-peaks between 40-45 deg..
3. The positive electrode material according to claim 1 or 2, wherein the positive electrode material is coated with aluminum; preferably, the positive electrode material is further coated with phosphate.
4. A method for preparing the sodium ion positive electrode material according to any one of claims 1 to 3, comprising the steps of:
step 1): 2 nickel-iron-copper-manganese precursors with different granularities are selected;
step 2): 2 nickel-iron-copper-manganese precursors with different particle sizes are respectively mixed with a sodium source and optional M compounds, and the mixture is sintered, wherein the sintering comprises three steps; the first step is sintering under the condition of temperature T1 in oxygen or compressed air atmosphere; step two, raising the temperature to T2 for sintering; thirdly, reducing the temperature to T3 for sintering to obtain a sodium-electricity anode material of 2 granularity matrixes;
step 3): fully mixing the sodium-electricity anode materials of the 2 matrixes obtained in the step 2) with Al compounds respectively, and sintering to obtain an Al-coated sodium-electricity anode material;
step 4): mixing the 2 positive electrode materials obtained in the step 3 with phosphate respectively, and then sintering to obtain 2 sodium-electricity positive electrode materials coated with phosphate and having low residual alkali content;
step 5): uniformly mixing the 2 sodium electric positive electrode materials with different granularities obtained in the step 4) to obtain the sodium electric positive electrode material with low residual alkali content.
5. The process of claim 4, wherein the 2 precursors of step 1) have particle sizes Y1 and Y2, respectively
a) The D50 of Y1 is 2-7um, preferably 3-6um; BET of 5-25m 2 /g, preferably 10-20m 2 /g; the particle size distribution (D90-D10)/D50 is 0.4 to 1.0, preferably 0.5 to 0.9;
b) The D50 of Y2 is 8-18um, preferably 10-16um; BET of 5-20m 2 Preferably 8-18m 2 /g; the particle size distribution (D90-D10)/D50 is from 0.1 to 0.6, preferably from 0.2 to 0.5.
6. The method according to claim 4 or 5, wherein the precursor of nickel, iron, copper and manganese has a structural formula of Ni y Fe z Cu a Mn b (OH) 2 Wherein y is more than 0 and less than or equal to 0.6,0, z is more than 0 and less than or equal to 0.4, a is more than 0 and less than or equal to 0.1, and b is more than 0 and less than or equal to 0.4.
7. The method according to any one of claims 4 to 6, wherein the sodium source is added in the amount of Na: me=0.7-1.2:1, where Me is the sum of the molar amounts of Ni, fe, cu, mn; more preferably, the sodium source is selected from any one or more of sodium carbonate, sodium hydroxide, sodium oxalate or sodium acetate;
preferably, the M-containing compound in step 2) is selected from one or more of Mg, ca, sr, zr, ti, W, B; preferably, the doping amount of M is 0-1.0% of the total metal mass of nickel, iron, copper and manganese, and preferably the doping amount of M is not 0.
8. The method according to any one of claims 4 to 7, wherein the atmosphere in step 2) is compressed air or oxygen, the sintering temperature T1 is 600 to 900 ℃, and the sintering time is 3 to 6 hours; the sintering temperature T2 is 800-1000 ℃ and the sintering time is 8-15h; the sintering temperature T3 is 400-700 ℃ and the sintering time is 2-4h;
preferably, the sintering temperature T2 is greater than T1.
9. The method of any one of claims 4 to 8, wherein the compound of step 3) aluminum is one or more of aluminum oxide, aluminum hydroxide, aluminum chloride, or aluminum nitrate; the coating amount of Al is 0.05-0.3% of the mass of the sodium-electricity anode material obtained in the step 2), the sintering temperature is 300-700 ℃, and the sintering time is 5-10h;
preferably, the phosphate of step 4) is NaFePO 4 、Na 3 V 2 (PO4) 3 One or more of the following; the coating amount of the phosphate is 0.05-0.5% of the mass of the Al-coated sodium-electricity positive electrode material obtained in the step 3), and the sintering temperature isSintering at 400-800 deg.c for 5-10 hr.
10. The preparation method according to any one of claims 5 to 9, wherein in step 5), the mass ratio Y2 of the phosphate-coated low residual alkali content sodium electric positive electrode material obtained by preparing the precursor having a particle size of Y2 to the phosphate-coated low residual alkali content sodium electric positive electrode material obtained by preparing the precursor having a particle size of Y1 is: y1 is 2-5:1.
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CN117285087A (en) * 2023-11-24 2023-12-26 北京中科海钠科技有限责任公司 Layered oxide, preparation method thereof and sodium battery

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116914126A (en) * 2023-09-13 2023-10-20 深圳华钠新材有限责任公司 Sodium ion positive electrode material and preparation method and application thereof
CN116914126B (en) * 2023-09-13 2023-11-28 深圳华钠新材有限责任公司 Sodium ion positive electrode material and preparation method and application thereof
CN116936782A (en) * 2023-09-19 2023-10-24 宜宾锂宝新材料有限公司 Multilayer coated positive electrode material, preparation method thereof, positive electrode and sodium ion battery
CN116936782B (en) * 2023-09-19 2024-01-19 宜宾锂宝新材料有限公司 Multilayer coated positive electrode material, preparation method thereof, positive electrode and sodium ion battery
CN117285087A (en) * 2023-11-24 2023-12-26 北京中科海钠科技有限责任公司 Layered oxide, preparation method thereof and sodium battery
CN117285087B (en) * 2023-11-24 2024-04-23 北京中科海钠科技有限责任公司 Layered oxide, preparation method thereof and sodium battery

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