CN116873987A - A multi-component precursor for sodium ion batteries and its preparation method and application - Google Patents

Abstract

The invention discloses a sodium ion battery multielement precursor, a preparation method and application thereof. The chemical formula of the polynary precursor of the sodium ion battery is Ni _x Mn _y M _z N _a (OH) ₂ Wherein x is more than or equal to 0.10 and less than or equal to 0.40,0.30, y is more than or equal to 0.80,0 and less than or equal to z is more than or equal to 0.20, and a is more than or equal to 0 and less than or equal to 0.02; wherein M is a low-valence metal with a small ionic radius, and M is at least one selected from Co, cu, K, mg and Ca; n is a high-valence metal with a large ionic radius, and N is at least one of Ti, nb, W, sb and Zr; x, y, z and a satisfy that the polynary precursor of the sodium ion battery is electrically neutral and has a chemical formula of zero valence. The positive electrode material prepared from the polynary precursor of the sodium ion battery improves the charge of the batteryThe electric cut-off voltage thus increases the energy density of the battery and also increases the rate capability and reversible capacity of the battery.

Description

A multi-component precursor for sodium ion batteries and its preparation method and application

Technical field

The invention belongs to the technical field of sodium-ion battery materials and relates to a multi-element precursor for sodium-ion batteries and its preparation method and application.

Background technique

Lithium-ion batteries have been widely used in fields such as electronic equipment and electric vehicles since their birth. However, due to the limited abundance and uneven distribution of lithium resources, the manufacturing cost of lithium-ion batteries has gradually increased. To this end, we need to find the next generation of high-capacity, low-cost, and environmentally friendly secondary batteries.

Because its working principle is similar to that of lithium-ion batteries, and it has the advantages of low cost, non-toxicity, uniform and abundant resource distribution, sodium-ion batteries are considered to be the next generation secondary batteries with the most development potential. However, compared with lithium-ion batteries, although sodium-ion battery layered oxide cathode materials have the advantage of low cost, they have the inherent disadvantage of low energy density. The sodium-ion battery layered oxide cathode materials currently developed are made of The battery voltage is not high, the average discharge voltage is around 3.2V, and the charging cut-off voltage is around 4.0V, which affects its energy density and cannot meet the application of sodium-ion batteries in the field of electric vehicles. Battery energy can be increased by increasing the voltage. There is still a lot of room for density.

Patent CN113764669A improves the charging cut-off voltage of layered cathode materials for sodium ion batteries by introducing anion and cation F ^- and Li ⁺ into the layered cathode material. At a current density of 50mA g ^-1 and a voltage range of 2.0-4.5V, the material's reversible capacity can still reach 171mAh g ^-1 after 20 cycles. Although the layered oxide cathode material prepared by this method has certain advantages in energy density, it introduces lithium metal, which is relatively expensive, and also introduces fluorine, which is difficult to process, which not only increases the cost of raw materials, but also increases the Processing costs.

CN109734069A provides a high-voltage cathode material for sodium ion secondary batteries, which has a phosphate metal compound represented by the formula Na _x C _y M _z (PO ₄ ) ₂ F ₃ , wherein M is Mg, Ti, V, Mn, At least one element among Fe, Co, Ni, Cu, Zn and Zr, and satisfying 2≤x≤4, 1≤y≤2, 0≤z≤1. The cathode material for sodium ion secondary batteries has a high voltage with a voltage range of 2.0-4.9V, which can effectively improve the high energy density of sodium ion secondary batteries and ensure the stability and reliability of sodium ion secondary batteries. However, the introduction of fluorine, which is difficult to process, not only increases the cost of raw materials, but also increases the cost of processing.

In view of this, it is necessary to provide a high-voltage sodium-ion battery cathode material that has the advantages of high voltage resistance, high capacity and low cost, thereby facilitating the application of sodium-ion batteries in the field of electric vehicles.

Contents of the invention

In view of the above-mentioned problems existing in the prior art, the purpose of the present invention is to provide a multi-component precursor for sodium ion batteries and its preparation method and application.

In order to achieve the above objects, the present invention adopts the following technical solutions:

In a first aspect, the present invention provides a multi-component precursor for sodium ion batteries. The chemical formula of the multi-component precursor for sodium ion batteries is Ni _x Mn _y M _z N _a (OH) ₂ , where 0.10≤x≤0.40, 0.30≤y ≤0.80, 0<z≤0.20, 0<a≤0.02; where M is a low-valence metal with a small ionic radius, M is selected from at least one of Co, Cu, K, Mg and Ca; N is a large ionic radius A high-valence metal, N is selected from at least one of Ti, Nb, W, Sb and Zr;

x, y, z and a satisfy that the multi-element precursor of the sodium ion battery is electrically neutral and the chemical formula is in the zero valence state.

In the present invention, x may be, for example, 0.1, 0.12, 0.15, 0.18, 0.20, 0.22, 0.24, 0.26, 0.28, 0.30, 0.33, 0.35, 0.37 or 0.40, etc. For example, y can be 0.30, 0.33, 0.35, 0.37, 0.40, 0.42, 0.45, 0.48, 0.50, 0.53, 0.56, 0.58, 0.60, 0.63, 0.66, 0.68, 0.70, 0.72, 0.75, 0.78 or 0.80, etc., and z can be, for example, It is 0.001, 0.002, 0.003, 0.005, 0.006, 0.008, 0.01, 0.015, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.12, 0.14, 0.16, 0.18 or 0.20, etc. a can be, for example, 0.001, 0.002, 0.003, 0.005, 0.006, 0.008, 0.01, 0.012, 0.015, 0.017 or 0.02, etc.

Through reasonable component design, the present invention provides a multi-component sodium ion battery precursor co-doped with an appropriate amount of high-valency large-radius metal ions and low-valency small-radius metal ions. By introducing these two types of metal elements in the precursor stage, the degree of disorder of the transition metal in the metal oxide cathode material is increased, the occurrence of phase transformation during the charge and discharge process is suppressed, the electrochemical behavior is enhanced, and it is helpful for its use in the metal oxide cathode material. Stable operation under high voltage increases the battery's charging cut-off voltage and thereby increases the battery's energy density. Moreover, metal elements with large ion radii increase the distance between metal layers, which is conducive to the rapid transmission of sodium ions and improves the rate performance of the battery. .

In the present invention, the presence of high-valence metals (at least one of Ti, Nb, W, Sb, and Zr) with large ion radii provides additional capacity under high voltage, effectively increasing the operating voltage and energy density of the battery.

The cathode material prepared by using the multi-element precursor of the sodium ion battery of the present invention has a high charging cut-off voltage and excellent capacity, can operate stably in the voltage range of 2.50-4.50V, and has extremely high reversible capacity.

The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

Preferably, 0.03<z<0.10, 0.004<a<0.015.

Preferably, M is selected from at least one of Mg and Ca, and N is at least one of Zr and Ti. Compared with other divalent metals, Mg and Ca have smaller ionic radii, and compared with other metals with large ionic radii, Zr and Ti have higher charge valence states. Both factors It can improve the reversible capacity of materials during circulation to a certain extent.

In one embodiment, low-valence metals with small ionic radii are evenly distributed in the multi-component precursor for sodium ion batteries.

In one embodiment, high-valence metals with large ionic radii are evenly distributed in the multi-element precursor of the sodium-ion battery.

Preferably, the average particle size of the multi-component precursor for sodium ion batteries is 3 to 10 μm, such as 3 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm.

In a second aspect, the present invention provides a method for preparing a multi-component precursor for a sodium ion battery as described in the first aspect, the method comprising the following steps:

Disperse the nickel salt, manganese salt and M source in the solvent to obtain a first metal salt solution;

The first metal salt solution, N source solution, precipitant solution and complexing agent solution are added to the bottom solution in parallel flow, and a co-precipitation reaction is performed to obtain the multi-element precursor of the sodium ion battery.

The invention directly carries out co-doping of high-valency large-radius metal ions and low-valency small-radius metal ions in the precursor co-precipitation stage, and the elements in the precursor are evenly distributed.

The method of the invention has mild reaction conditions, simple preparation process, easy control of consistency, low cost, and can realize large-scale production.

Preferably, the preparation method of the first salt solution includes: separately preparing a nickel-manganese mixed solution and an M source solution, and mixing the nickel-manganese mixed solution and the M source solution to obtain the first salt solution.

Preferably, the total concentration of metal ions in the first metal salt solution is 0.5-5 mol/L, such as 0.5 mol/L, 0.7 mol/L, 0.8 mol/L, 1 mol/L, 1.2 mol/L, 1.5 mol/L, 2mol/L, 2.2mol/L, 2.4mol/L, 2.5mol/L, 3mol/L, 3.5mol/L, 4mol/L, 4.5mol/L or 5mol/L, etc.

Preferably, the feed rate of the first metal salt solution is 4 to 100L/h, such as 4L/h, 6L/h, 8L/h, 10L/h, 15L/h, 20L/h, 25L/h, 30L/h, 35L/h, 40L/h, 45L/h, 50L/h, 55L/h, 60L/h, 65L/h, 70L/h, 75L/h, 80L/h, 85L/h, 90L/ h, 95L/h or 100L/h, etc., preferably 5 to 30L/h.

Preferably, the total concentration of metal ions in the N source solution is 0.01 to 1 mol/L, such as 0.01 mol/L, 0.03 mol/L, 0.05 mol/L, 0.08 mol/L, 0.1 mol/L, 0.15 mol /L, 0.2mol/L, 0.25mol/L, 0.3mol/L, 0.35mol/L, 0.4mol/L, 0.45mol/L, 0.5mol/L, 0.55mol/L, 0.6mol/L, 0.65mol /L, 0.7mol/L, 0.75mol/L, 0.8mol/L, 0.85mol/L, 0.9mol/L or 1mol/L, etc.

Preferably, the feed rate of the N source solution is 1 to 20L/h, such as 2L/h, 4L/h, 6L/h, 8L/h, 10L/h, 15L/h or 20L/h, etc., preferably It is 1~5L/h.

By controlling the feed rates of the first metal salt solution and the N source solution, uniformly doped materials can be obtained.

Preferably, the concentration of the precipitant solution is 2 to 15 mol/L, such as 2 mol/L, 3 mol/L, 4 mol/L, 6 mol/L, 8 mol/L, 10 mol/L, 12 mol/L, 13 mol/L or 15mol/L etc.

Preferably, the feed rate of the precipitant solution is 1 to 20L/h, such as 2L/h, 4L/h, 6L/h, 8L/h, 10L/h, 15L/h or 20L/h, etc.

The type of precipitating agent is not specifically limited in the present invention, and may be NaOH, for example.

Preferably, the concentration of the complexing agent solution is 4 to 12 mol/L, such as 4 mol/L, 6 mol/L, 8 mol/L, 10 mol/L or 12 mol/L, etc.

Preferably, the feed rate of the complexing agent solution is 0.5-10L/h, such as 0.5L/h, 1L/h, 2L/h, 4L/h, 6L/h, 8L/h or 10L/h, etc. .

The type of complexing agent is not specifically limited in the present invention. For example, it may be ammonia water.

Preferably, the pH of the bottom liquid is 8 to 12, such as 8, 8.5, 9, 9.5, 10, 10.5, 11 or 12, etc.

Preferably, the concentration of the complexing agent in the bottom solution is 0 to 2 mol/L, such as 0 mol/L, 0.1 mol/L, 0.2 mol/L, 0.5 mol/L, 0.7 mol/L, 1 mol/L, 1.2mol/L, 1.5mol/L, 1.8mol/L or 2mol/L, etc. Wherein, the concentration of the complexing agent in the bottom liquid is 0 mol/L means that the bottom liquid does not contain the complexing agent.

Preferably, the co-precipitation reaction is carried out under a protective atmosphere.

The present invention does not specifically limit the type of gas in the protective atmosphere. Specifically, it can be at least one of nitrogen, helium or argon, but is not limited to the types listed above. Protective gases commonly used in the gas field are also applicable. in the present invention.

Preferably, the temperature of the co-precipitation reaction is 20-70°C, such as 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C, etc. .

Preferably, the pH is maintained in the range of 8 to 12 during the co-precipitation reaction. The pH may be, for example, 8, 8.5, 9, 9.5, 10, 10.5, 11 or 12, etc.

In a third aspect, the present invention provides a multi-component cathode material for a sodium ion battery, which is prepared by using the multi-component precursor for a sodium ion battery described in the first aspect.

The present invention does not limit the preparation method of multi-component cathode materials for sodium ion batteries. For example, the preparation method of multi-component cathode materials for sodium ion batteries includes the following steps:

The multi-component precursor of the sodium ion battery is mixed with the sodium source and then sintered to obtain the multi-component cathode material for the sodium ion battery.

In one embodiment, the sintering is performed in a flowing oxygen stream.

In one embodiment, the sintering temperature is 800-1400°C, such as 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C, 1200°C, 1300°C or 1400°C, etc.

In one embodiment, the sintering time is 10 to 25h, such as 10h, 12h, 14h, 15h, 16h, 18h, 20h, 22h, 23h or 25h, etc.

In one embodiment, sintering is followed by grinding and sieving steps.

In a fourth aspect, the present invention provides a sodium ion battery, which includes the multi-element positive electrode material of the sodium ion battery described in the third aspect.

The numerical range described in the present invention not only includes the point values listed above, but also includes any point value between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively enumerate the ranges. Specific point values included.

Compared with the prior art, the present invention has the following beneficial effects:

(1) Through reasonable component design, the present invention provides a multi-element sodium ion battery precursor co-doped with an appropriate amount of high-valency large-radius metal ions and low-valency small-radius metal ions. By introducing these two types of metal elements in the precursor stage, the degree of disorder of the transition metal in the metal oxide cathode material is increased, the occurrence of phase transformation during the charge and discharge process is suppressed, the electrochemical behavior is enhanced, and it is helpful for its use in the metal oxide cathode material. Stable operation under high voltage increases the battery's charging cut-off voltage and thereby increases the battery's energy density. Moreover, metal elements with large ion radii increase the distance between metal layers, which is conducive to the rapid transmission of sodium ions and improves the rate performance of the battery. .

(2) The cathode material prepared using the multi-element precursor of the sodium ion battery of the present invention has a high charging cut-off voltage and excellent capacity, can operate stably in the voltage range of 2.50-4.50V, and has extremely high reversible capacity. For the first time The discharge capacity is above 162mAh/g, the capacity after 100 cycles is above 157mAh/g, and the capacity retention rate after 100 cycles is still above 96%.

Description of the drawings

Figure 1 is an SEM image of the multi-component precursor for sodium ion batteries prepared in Example 1.

Figures 2 and 3 are EPMA images of Co and Zr elements in the cross-section of the multi-component precursor for sodium ion batteries prepared in Example 1.

Detailed ways

The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation modes.

In order to facilitate understanding of the present invention, the following examples describe the invention in a comprehensive and detailed manner, but the protection scope of the present invention is not limited to the following specific examples.

Example 1

This embodiment provides a multi-component precursor for sodium ion batteries. The preparation method of the multi-component precursor for sodium ion batteries includes the following steps:

(1) Mix the nickel-manganese mixed salt solution and the cobalt sulfate solution to obtain a first metal salt solution with a total metal ion concentration of 2 mol/L and a nickel, manganese, and cobalt molar ratio of 0.22:0.72:0.05.

Prepare a 0.1 mol/L zirconium sulfate solution.

The first metal salt solution, zirconium sulfate solution, 10 mol/L sodium hydroxide solution and 8 mol/L ammonia water were added into the bottom solution with a pH value of 11.2 and an ammonia concentration of 0.5 mol/L in parallel flow. During the parallel flow addition process, the feed rate of the first metal salt solution is 40L/h, and the feed rate of the zirconium sulfate solution is 4L/h. By controlling the flow rates of sodium hydroxide solution and ammonia water, the pH value of the reaction system is controlled. Between 10.4 and 10.7, the ammonia concentration is between 0.40 and 0.60 mol/L. Under nitrogen protection, perform a co-precipitation reaction at a reaction temperature of 50°C. After 50 hours of reaction, the average particle size reaches 6.0 μm and the reaction is stopped.

(2) Product post-processing: After the reaction is completed, age it for 8 hours, centrifuge and wash, and dry at 150°C to obtain the multi-component precursor powder for sodium ion batteries. The chemical formula of the multi-component precursor for sodium ion batteries is [Ni _0.22 Mn _0.72 Co _0.05 Zr _0.005 ](OH) ₂ .

The SEM image of the multi-component precursor for sodium ion batteries prepared in this example is shown in Figure 1. It can be seen from the figure that the precursor prepared in this example has good sphericity, uniform size, and an average particle size of 6.0 μm.

The EPMA images of Co and Zr elements in the cross section of the precursor material prepared in this embodiment are shown in Figures 2 and 3. It can be seen from the figures that Co and Zr elements are evenly distributed inside the precursor particles.

This embodiment provides a multi-component cathode material for sodium ion batteries. The preparation method of the multi-component cathode material for sodium ion batteries includes the following steps:

Sodium carbonate and the above-mentioned sodium ion battery multi-component precursor powder were weighed and mixed evenly according to a molar ratio of 1.05:1, calcined at 1000°C for 16 hours, ground and sieved to obtain the positive electrode material.

Example 2

This embodiment provides a multi-component precursor for sodium ion batteries. The preparation method of the multi-component precursor for sodium ion batteries includes the following steps:

(1) Mix the nickel-manganese mixed salt solution and the copper sulfate solution to obtain a first metal salt solution with a total metal ion concentration of 2 mol/L and a nickel-manganese-copper molar ratio of 0.25:0.70:0.04.

Prepare a 0.05mol/L titanyl sulfate solution.

The first metal salt solution, titanyl sulfate solution, 10 mol/L sodium hydroxide solution and 8 mol/L ammonia water were added in parallel flow to the bottom solution with a pH value of 11.0 and an ammonia concentration of 0.2 mol/L. During the parallel addition process, the feed rate of the first metal salt solution is 80L/h, and the feed rate of the titanyl sulfate solution is 16L/h. By controlling the flow rates of sodium hydroxide solution and ammonia water, the pH of the reaction system is controlled. The value is between 9.5 and 10.0, and the ammonia concentration is between 0.15 and 0.25 mol/L. Under nitrogen protection, the co-precipitation reaction is carried out at a reaction temperature of 40°C. The reaction is continued for 35 hours. When the average particle size reaches 4.0 μm, the reaction is stopped.

(2) Product post-treatment: After the reaction is completed, age for 6 hours, centrifuge and wash, and dry at 120°C to obtain the precursor powder. The precursor chemical formula is [Ni _0.25 Mn _0.70 Cu _0.04 Ti _0.005 ](OH) ₂ .

This embodiment provides a multi-component cathode material for sodium ion batteries. The preparation method of the multi-component cathode material for sodium ion batteries includes the following steps:

Sodium carbonate and the above-mentioned sodium ion battery multi-component precursor powder were weighed and mixed evenly according to a molar ratio of 1.05:1, calcined at 900°C for 18 hours, ground and sieved to obtain the cathode material.

Example 3

This embodiment provides a multi-component precursor for sodium ion batteries. The preparation method of the multi-component precursor for sodium ion batteries includes the following steps:

(1) Mix the nickel-manganese mixed salt solution and the cobalt sulfate solution to obtain a first metal salt solution with a total metal ion concentration of 3.5 mol/L and a nickel, manganese, and cobalt molar ratio of 0.15:0.75:0.09.

Prepare a 0.2mol/L zirconium sulfate solution.

The first metal salt solution, zirconium sulfate solution, 5 mol/L sodium hydroxide solution and 10 mol/L ammonia water were added into the bottom solution with a pH value of 10.5 and an ammonia concentration of 1 mol/L in parallel flow. During the parallel flow addition process, the feed rate of the first metal salt solution is 20L/h, and the feed rate of the zirconium sulfate solution is 2L/h. By controlling the flow rates of sodium hydroxide solution and ammonia water, the pH value of the reaction system is controlled. Between 10.0 and 11.0, and the ammonia concentration between 0.60 and 2.0 mol/L, under nitrogen protection, perform a co-precipitation reaction at a reaction temperature of 60°C until the average particle size reaches 7.0 μm, then stop the reaction.

(2) Product post-processing: After the reaction is completed, it is aged for 10 hours, centrifuged and washed, and dried at 90°C to obtain the multi-component precursor powder for sodium ion batteries. The chemical formula of the multi-component precursor for sodium ion batteries is [Ni _0.15 Mn _0.75 Co _0.09 Zr _0.005 ](OH) ₂ .

Example 4

The difference from Example 1 is that the cobalt sulfate solution is replaced by a calcium nitrate solution of the same concentration. In this example, the amount of calcium element is the same as the amount of cobalt element in Example 1.

Example 5

The difference from Example 1 is that the zirconium sulfate solution is replaced by an ammonium tungstate solution of the same concentration. In this example, the amount of tungsten element is the same as the amount of zirconium element in Example 1.

Example 6

The difference from Example 1 is that during the co-current addition process, the feed rate of the first metal salt solution is 20L/h, and the feed rate of the zirconium sulfate solution is 2L/h.

Example 7

The difference from Example 2 is that during the co-current addition process, the feed rate of the first metal salt solution is 20L/h, and the feed rate of the titanyl sulfate solution is 4L/h.

Example 8

The difference from Example 1 is that by adjusting the ratio of the reaction raw materials, the chemical formula of the multi-component precursor for the sodium ion battery is [Ni _0.22 Mn _0.75 Co _0.02 Zr _0.005 ](OH) ₂ .

Example 9

The difference from Example 1 is that by adjusting the proportion of the reaction raw materials, the chemical formula of the multi-component precursor for the sodium ion battery is [Ni _0.22 Mn _0.69 Co _0.05 Zr _0.02 ](OH) ₂ .

Comparative example 1

The difference between this comparative example and Example 1 is that no cobalt sulfate solution is used in step (1) of this comparative example.

The remaining preparation methods and parameters remain consistent with Example 1.

Comparative example 2

The difference between this comparative example and Example 1 is that zirconium sulfate solution is not used in step (1) of this comparative example.

The remaining preparation methods and parameters remain consistent with Example 1.

Comparative example 3

The difference between this comparative example and Example 1 is that neither cobalt sulfate solution nor zirconium sulfate solution is used in step (1) of this comparative example.

The remaining preparation methods and parameters remain consistent with Example 1.

Comparative example 4

The difference between this comparative example and Example 1 is that the feed rate of the zirconium sulfate solution in step (1) of this comparative example increases in a gradient from 2L/h to 6L/h.

test:

Under the condition of 25°C, use the cathode material prepared above as the main material of the cathode and the metal sodium sheet as the cathode, and assemble them into CR2032 button batteries respectively, and then in the voltage range of 2.50-4.50V, the discharge current density is 20mA g ^-1 The electrochemical performance test was carried out and the test results are as shown in Table 1 below:

Table 1

It can be seen from the data in the table that in Examples 1-9, the button battery obtained from the multi-component precursor of the high-voltage sodium ion battery prepared by the present invention was discharged in the 2.5-4.5V range at a current density of 20mA g ^-1 In the charge and discharge test, after 100 charge and discharge cycles, the first discharge capacity was greater than 162mAh/g, and the capacity retention rate after 100 cycles was still above 96%.

However, the cathode materials prepared by conventional precursors (Comparative Examples 1-3) that do not introduce low-valence states or dope high-valence states are charged and discharged at 20mA g ^-1 in the discharge range of 2.5-4.5V. After 100 cycles, the discharge The capacity is less than 130mAh/g, and the capacity retention rate is less than 80%. It can be seen from this that the high-voltage resistance performance of the sodium-ion battery assembled from the cathode material obtained from the multi-component precursor of the high-voltage sodium-ion battery prepared in the present invention is better than that of the conventional sodium-ion battery.

Comparing Example 1 with Examples 4-5, it can be seen that the types of doping elements are preferred. M is preferably one of Mg and Ca, and N is preferably one of Zr and Ti. Because compared with other divalent metals, Mg and Ca have smaller ionic radii, and compared with other metals with large ionic radii, Zr and Ti have higher charge valence states. These two factors Both can improve the reversible capacity of materials during circulation to a certain extent.

Comparison between Example 1 and Example 6, and Example 2 and Example 7 shows that the appropriate feed rate directly affects the reaction rate, and thus affects the performance of the final material. The feed rate of the first metal salt solution is preferably 5 to 30L. /h, the N source solution feed rate is preferably 1 to 5L/h.

Comparing Example 1 with Examples 8-9, it can be seen that the content of doping metal directly affects the electrochemical performance of the material. The doping amount of metal M is preferably 0.03 to 0.10, and the doping amount of metal N is preferably 0.004 to 0.015.

Comparing Example 1 with Comparative Example 4, it can be seen that the uniformity of doping metal distribution will also affect the electrochemical performance of the material. The effect of uniform doping of metal N is significantly better than that of uneven doping.

Comparing Example 1 with Comparative Example 4, it can be seen that the gradient change of the feed speed leads to uneven doping, thereby reducing the performance of the material.

The applicant declares that the present invention illustrates the detailed methods of the present invention through the above embodiments, but the present invention is not limited to the above detailed methods, that is, it does not mean that the present invention must rely on the above detailed methods to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacement of raw materials of the product of the present invention, addition of auxiliary ingredients, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims (10)

1. A polynary precursor of a sodium ion battery is characterized in that the polynary precursor of the sodium ion battery has a chemical formula of Ni _x Mn _y M _z N _a (OH) ₂ Wherein x is more than or equal to 0.10 and less than or equal to 0.40,0.30, y is more than or equal to 0.80,0 and less than or equal to z is more than or equal to 0.20, and a is more than or equal to 0 and less than or equal to 0.02; wherein M is a low-valence metal with a small ionic radius, and M is at least one selected from Co, cu, K, mg and Ca; n is a high-valence metal with a large ionic radius, and N is at least one of Ti, nb, W, sb and Zr;

x, y, z and a satisfy that the polynary precursor of the sodium ion battery is electrically neutral and has a chemical formula of zero valence.

2. The sodium ion battery multi-element precursor of claim 1, wherein 0.03< z <0.10,0.004< a <0.015;

preferably, M is selected from at least one of Mg and Ca, and N is at least one of Zr and Ti.

3. The sodium ion battery precursor according to claim 1 or 2, wherein the average particle size of the sodium ion battery precursor is 5 to 15 μm.

4. A method for preparing a precursor for a sodium ion battery according to any one of claims 1 to 3, comprising the steps of:

dispersing nickel salt, manganese salt and an M source in a solvent to obtain a first metal salt solution;

and adding the first metal salt solution, the N source solution, the precipitant solution and the complexing agent solution into the base solution in parallel flow, and performing coprecipitation reaction to obtain the sodium ion battery multielement precursor.

5. The method for preparing a precursor of a sodium ion battery according to claim 4, wherein the method for preparing the first salt solution comprises:

respectively preparing a nickel-manganese mixed solution and an M source solution, and mixing the nickel-manganese mixed solution with the M source solution to obtain a first salt solution.

6. The method for preparing a precursor of a sodium ion battery according to claim 4 or 5, wherein the total concentration of metal ions in the first metal salt solution is 0.5 to 5mol/L;

preferably, the feeding speed of the first metal salt solution is 4-100L/h, preferably 5-30L/h;

preferably, the total concentration of metal ions in the N source solution is 0.01-1 mol/L;

preferably, the feeding speed of the N source solution is 1-20L/h, preferably 1-5L/h;

preferably, the concentration of the precipitant solution is 2-15 mol/L;

preferably, the feeding speed of the precipitant solution is 1-20L/h;

preferably, the concentration of the complexing agent solution is 4-12 mol/L;

preferably, the complexing agent solution is fed at a rate of 0.5 to 10L/h.

7. The method for preparing a precursor of a sodium ion battery according to any one of claims 4 to 6, wherein the pH of the base solution is 8 to 12;

preferably, the concentration of the complexing agent in the base solution is 0-2 mol/L.

8. The method for preparing a precursor of a sodium ion battery according to any one of claims 4 to 7, wherein the coprecipitation reaction is carried out under protective atmosphere;

preferably, the temperature of the coprecipitation reaction is 20-70 ℃;

preferably, the pH is maintained in the range of 8 to 12 during the co-precipitation reaction.

9. A multi-element positive electrode material for a sodium ion battery, which is characterized in that the multi-element positive electrode material for a sodium ion battery is prepared by adopting the multi-element precursor for a sodium ion battery according to any one of claims 1 to 3.

10. A sodium ion battery comprising the sodium ion battery multi-element positive electrode material of claim 9.