CN116675203A - Preparation method and application of sodium ion battery active material - Google Patents

Abstract

The invention discloses a preparation method and application of an active material of a sodium ion battery. The preparation method comprises: S1, taking phosphorus source, iron source, and sodium source as reaction raw materials, using nanometer metal as a reducing agent, and mixing according to a set ratio, Obtain a mixed product; S2, place the mixed product under an inert atmosphere for ball milling to obtain a ball milled product; S3, place the ball milled product under an inert atmosphere for calcination, and cool to obtain the active material of the sodium ion battery; the sodium ion battery The chemical formula of the active material is NaM _x Fe _y PO ₄ , 0<x<1, 0<y<1, and M is selected from one or more of Mg, Al, Ti, V, Mn, Zn, and Cr. According to the metal activity sequence Mg, Al, Ti, Zr, V, Mn, Zn, Cr is greater than Fe, the present invention selects nano metal Mg, Al, Ti, Zr, V, Mn, Zn, Cr powder as the reducing agent to reduce the high price For iron, use a ball mill to fully mix the raw materials to increase the reactivity.

Description

A kind of preparation method and application of sodium ion battery active material

technical field

The invention relates to a preparation method and application of an active material of a sodium ion battery, belonging to the technical field of sodium ion batteries.

Background technique

The development of green energy storage technology can effectively alleviate problems such as energy crisis and environmental pollution. Lithium-ion batteries have become one of the most widely used energy storage technologies due to their advantages such as high energy density and long cycle life, but lithium resources are limited and unevenly distributed. And the high cost hinders the development of lithium-ion batteries. As the price of lithium resources in the world increases, sodium-ion batteries are considered to be an effective replacement or supplement to lithium-ion batteries due to their abundant resources, low price, and similar working principles to lithium-ion batteries.

Among many cathode materials for sodium-ion batteries, polyanionic compounds are considered to be the most promising type of electrode materials due to their excellent structural stability, safety and suitable voltage platform. Among them, sodium iron phosphate material is rich in raw materials, low in price, has three-dimensional ion diffusion channels, and has good safety performance. Sodium iron phosphate NaFePO ₄ is preferentially considered as the cathode material for sodium ion batteries. The theoretical specific capacity of NaFePO ₄ with olivine structure as anode material for sodium ion battery is 154mAh/g.

CN 105161688A discloses a carbon-coated sodium iron phosphate-sodium vanadium phosphate composite material and a preparation method thereof. First, ferric vanadate is prepared, and then carbon vanadate is obtained through steps such as ball milling, back-grinding, and calcination by using ferric vanadate as a raw material. Coated sodium iron phosphate-sodium vanadium phosphate. The obtained material has a gram capacity of 101.8mAh·g ^-1 for the first charge and discharge under 1C rate in the voltage range of 2.0-4.0V; in the process of charge and discharge, after 50 cycles of 1C, the capacity retention rate is 96.5%.

CN 115148976 A discloses a method for synthesizing sodium iron phosphate pyrophosphate sodium/carbon as the cathode material of sodium ion battery and its sodium ion battery. Stir with water, heat and stir to evaporate to dryness, dry the obtained solid, grind, pre-sinter under the protection of nitrogen, and after natural cooling, grind again, sinter under the protection of nitrogen, and naturally cool to obtain sodium iron phosphate pyrophosphate/carbon as the positive electrode material of sodium ion battery .

The obtained material was charged and discharged at a rate of 1C in the voltage range of 2.0-4.2V. The material showed a typical charge-discharge curve of sodium ferric phosphate pyrophosphate, and its first discharge specific capacity was 99.38mAh g ^-1 , 300 cycles The post-capacity retention rate was 94.2%.

In the prior art, in the preparation process of sodium iron phosphate, carbon reduction is generally used for carbon coating or carbon doping to improve the conductivity of sodium iron phosphate. Carbon reduction is likely to cause environmental pollution, and the prepared sodium iron phosphate has a relatively low specific capacity. Low, the problem of rapid capacity decay after cycling.

Contents of the invention

The purpose of the present invention is to provide a preparation method and application of the active material of a sodium ion battery, so as to solve the problem of environmental pollution caused by carbon reduction in the prior art, the prepared sodium iron phosphate has a low specific capacity, and the capacity decays quickly after cycling The problem.

In order to achieve the above object, the present invention provides the following technical solutions:

A preparation method of an active material for a sodium ion battery, comprising the following steps:

S1. Using phosphorus source, iron source, and sodium source as reaction raw materials, and nano-metal as reducing agent, mix according to a set ratio to obtain a mixed product;

S2, placing the mixed product obtained in step S1 under an inert atmosphere for ball milling to obtain a ball milled product;

S3. Calcining the ball-milled product obtained in step S2 under an inert atmosphere, and cooling to obtain the active material for the sodium-ion battery;

The chemical formula of the active material of the sodium ion battery is NaM _x Fe _y PO ₄ , 0<x<1, 0<y<1, M is selected from one of Mg, Al, Ti, V, Mn, Zn, Cr or Various.

In a preferred solution, in step S1, the phosphorus source is one or more of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, sodium dihydrogen phosphate and phosphorus pentoxide.

In a preferred solution, in step S1, the iron source is one or more of iron phosphate and ferric oxide.

Preferred scheme, in step S1, described sodium source is sodium carbonate, sodium bicarbonate, sodium hydroxide, sodium acetate, sodium phosphate, sodium hydrogen phosphate, sodium oxalate, sodium formate, sodium citrate, sodium pyrophosphate and sodium metaphosphate one or more of them.

In a preferred solution, in step S2, under an inert atmosphere, the mixed product is placed in a planetary ball mill for ball milling, and the ball milling time is 0.5-24 hours.

The technical effect of the above scheme: the ball milling process of the mixed product needs to be carried out under an inert atmosphere to prevent the nano metal from being oxidized and affecting its reduction performance.

In the preferred scheme, in step S3, the calcination process adopts segmental sintering (static sintering process), and the segmental sintering includes that the working temperature of the first segment is 300-500°C, and the material holding time is 2-8h; the second segment The working temperature is 500-600°C, the material holding time is 0.5-4h, and the heating rate of each section is controlled to be 1-5°C/min.

Preferably, the inert atmosphere is any one of nitrogen, argon and helium.

The invention also provides the application of the preparation method of the active material of the sodium ion battery in the preparation of the positive electrode material of the sodium battery.

Compared with the prior art, the beneficial technical effect of the present invention is:

1) The present invention provides a kind of preparation method of sodium-ion battery active material, according to metal activity sequence Mg, Al, Ti, Zr, V, Mn, Zn, Cr is greater than Fe, selects nanometer metal Mg, Al, Ti, Zr, V, Mn, Zn, and Cr powders are used as reducing agents to reduce high-valent iron, and the raw materials are fully mixed by using a ball mill under an inert atmosphere to increase the reactivity.

2) The present invention provides a method for preparing the active material of a sodium ion battery, which adopts a carbon-free reduction-low temperature synthesis process, the process is simple, the synthesis temperature is low, the reaction time is short, the synthesis reaction is sufficient at low temperature, and the carbon-free reduction can effectively save energy Reduce emissions and reduce product costs.

3) The active material for sodium ion batteries prepared by the present invention exhibits excellent electrochemical performance; at room temperature, the capacity retention rate after 100 cycles at 1C is 85.2%, and the discharge capacity at 0.1C reaches 115.6mAh/g.

Description of drawings

FIG. 1 is a SEM image of NaV _0.2 Fe _0.7 PO ₄ , an active material for a sodium ion battery in Example 1 of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, those skilled in the art All other embodiments obtained by personnel without creative work belong to the protection scope of the present invention.

This example has no special instructions, the reagents used are all common commercially available products or prepared by conventional means, and the equipment used is all conventional equipment in this field. The following are some examples of the inventor in the test:

Example 1

A kind of preparation method of sodium ion battery active material NaV _0.2 Fe _0.7 PO ₄ , comprises the following steps:

S1, with ammonium dihydrogen phosphate, ferric oxide, sodium carbonate as reaction raw materials, with metal vanadium powder as reducing agent, mix in the ratio that is 1: 0.2: 0.7: 1 by the molar ratio of sodium, vanadium, iron, phosphorus element, A mixed product is obtained;

S2, placing the mixed product obtained in step S1 under nitrogen for ball milling for 6 hours to obtain a ball milled product;

S3. Place the ball mill product obtained in step S2 under nitrogen for calcination. The calcination process adopts segmental sintering. The segmental sintering includes that the working temperature of the first segment is 400°C, and the material holding time is 6h; the operating temperature of the second segment is 600°C. °C, the material holding time is 2 hours, the heating rate of each stage is controlled to be 5 °C/min, and the active material of the sodium ion battery is obtained after cooling.

FIG. 1 is a SEM image of NaV0.2Fe0.7PO4, an active material for a sodium ion battery in Example 1 of the present invention.

Example 2

A kind of preparation method of sodium ion battery active material NaAl _0.2 Fe _0.7 PO ₄ , comprises the following steps:

S1. Using sodium dihydrogen phosphate, iron phosphate, and sodium carbonate as reaction raw materials, and using metal aluminum powder as a reducing agent, mix them in a ratio of 1:0.2:0.7:1 in molar ratios of sodium, aluminum, iron, and phosphorus to obtain a mixture product;

S2, placing the mixed product obtained in step S1 under nitrogen for ball milling for 6 hours to obtain a ball milled product;

S3. The ball mill product obtained in step S2 is placed under nitrogen for calcination. The calcination process adopts segmental sintering. The segmental sintering includes the working temperature of the first segment being 400° C. and the material holding time of 6 hours; the operating temperature of the second segment is 550 ° C. °C, the material holding time is 4 hours, the heating rate of each section is controlled to be 5 °C/min, and the active material of the sodium ion battery is obtained after cooling.

Example 3

A kind of preparation method _of sodium ion battery active material _{NaMn0.3Fe0.7PO4} , comprises _the following steps:

S1. Taking sodium dihydrogen phosphate, iron phosphate, and sodium carbonate as reaction raw materials, and using metallic manganese powder as a reducing agent, mixing them in a ratio of 1:0.3:0.7:1 molar ratio of sodium, manganese, iron, and phosphorus elements to obtain a mixed product;

S2, placing the mixed product obtained in step S1 under nitrogen for ball milling for 6 hours to obtain a ball milled product;

S3. Place the ball mill product obtained in step S2 under nitrogen for calcination. The calcination process adopts segmental sintering. The segmental sintering includes that the working temperature of the first segment is 500°C, and the material holding time is 6h; the operating temperature of the second segment is 600°C. °C, the material holding time is 2 hours, the heating rate of each stage is controlled to be 5 °C/min, and the active material of the sodium ion battery is obtained after cooling.

Example 4

A kind of preparation method _of sodium ion battery active material _{NaMg0.4Fe0.6PO4} , comprises _the following steps:

S1. Taking sodium dihydrogen phosphate, iron phosphate, and sodium carbonate as reaction raw materials, and using metal magnesium powder as a reducing agent, mix them in a ratio of 1:0.4:0.6:1 in molar ratios of sodium, magnesium, iron, and phosphorus to obtain a mixture product;

S2, placing the mixed product obtained in step S1 under nitrogen for ball milling for 8 hours to obtain a ball milled product;

S3. Place the ball mill product obtained in step S2 under nitrogen for calcination. The calcination process adopts segmental sintering. The segmental sintering includes that the working temperature of the first segment is 500°C, and the material holding time is 6h; the operating temperature of the second segment is 600°C. °C, the material holding time is 2 hours, the heating rate of each stage is controlled to be 5 °C/min, and the active material of the sodium ion battery is obtained after cooling.

Example 5

A kind of preparation method _of sodium ion battery active material _{NaTi0.1Fe0.8PO4} , comprises _the following steps:

S1. Using sodium dihydrogen phosphate, iron phosphate, and sodium carbonate as reaction raw materials, metal titanium powder is used as a reducing agent, and the molar ratio of sodium, titanium, iron, and phosphorus is mixed in a ratio of 1:0.1:0.8:1 to obtain a mixed product;

S2, placing the mixed product obtained in step S1 under nitrogen for ball milling for 8 hours to obtain a ball milled product;

S3. Place the ball mill product obtained in step S2 under nitrogen for calcination. The calcination process adopts segmental sintering. The segmental sintering includes that the working temperature of the first segment is 500°C, and the material holding time is 6h; the operating temperature of the second segment is 600°C. °C, the material holding time is 2 hours, the heating rate of each stage is controlled to be 5 °C/min, and the active material of the sodium ion battery is obtained after cooling.

Example 6

A kind of preparation method of sodium ion battery active material NaZn _0.1 Fe _0.9 PO ₄ , comprises the following steps:

S1. Using sodium dihydrogen phosphate, iron phosphate, and sodium carbonate as reaction raw materials, metal zinc powder is used as a reducing agent, and the molar ratio of sodium, zinc, iron, and phosphorus is mixed in a ratio of 1:0.1:0.9:1 to obtain a mixed product;

S2, placing the mixed product obtained in step S1 under nitrogen for ball milling for 8 hours to obtain a ball milled product;

S3. Place the ball mill product obtained in step S2 under nitrogen for calcination. The calcination process adopts segmental sintering. The segmental sintering includes that the working temperature of the first segment is 500°C, and the material holding time is 6h; the operating temperature of the second segment is 600°C. °C, the material holding time is 2 hours, the heating rate of each stage is controlled to be 5 °C/min, and the active material of the sodium ion battery is obtained after cooling.

Example 7

A kind of preparation method _of sodium ion battery active material _{NaCr0.2Fe0.7PO4} , comprises _the following steps:

S1. Using sodium dihydrogen phosphate, iron phosphate, and sodium carbonate as reaction raw materials, metal chromium powder is used as a reducing agent, and the molar ratio of sodium, chromium, iron, and phosphorus is mixed in a ratio of 1:0.2:0.7:1 to obtain a mixed product;

S2, placing the mixed product obtained in step S1 under nitrogen for ball milling for 8 hours to obtain a ball milled product;

S3. Place the ball mill product obtained in step S2 under nitrogen for calcination. The calcination process adopts segmental sintering. The segmental sintering includes that the working temperature of the first segment is 500°C, and the material holding time is 6h; the operating temperature of the second segment is 600°C. °C, the material holding time is 2 hours, the heating rate of each stage is controlled to be 5 °C/min, and the active material of the sodium ion battery is obtained after cooling.

Comparative example 1

A preparation method of sodium iron phosphate NaFePO ₄ /C active material, comprising the following steps:

S1, using sodium dihydrogen phosphate, iron phosphate, and sodium carbonate as reaction raw materials, using glucose as a reducing agent and a carbon source to obtain a mixed product;

S2, placing the mixed product obtained in step S1 under nitrogen for ball milling for 8 hours to obtain a ball milled product;

S3. Place the ball mill product obtained in step S2 under nitrogen for calcination. The calcination process adopts segmental sintering. The segmental sintering includes that the working temperature of the first segment is 500°C, and the material holding time is 6h; the operating temperature of the second segment is 600°C. ℃, the material holding time is 2h, the heating rate of each stage is controlled to be 5℃/min, and the sodium iron phosphate active material is obtained after cooling.

Get the sodium ion battery positive electrode material, polyvinylidene fluoride binder and carbon black conductive agent that embodiment 1-7, comparative example 1 make, the sodium ion positive electrode material, binder and conductive agent are according to mass ratio be 8: Mix 1:1, add an appropriate amount of N-methylpyrrolidone to make a viscous slurry, coat it on an aluminum foil with a rough surface, and bake it in a vacuum oven at 80°C for 8 hours. After it is completely dry, put the whole The pole piece of the block is made into a disc electrode of a suitable size by a punching machine for future use. Using sodium metal as the counter electrode, glass fiber as the separator, and 1mol/L NaClO ₄ (EC and DEC with a solvent volume ratio of 1:1) as the electrolyte, a 2016 button cell was assembled in an argon protective glove box. The battery was tested within the voltage range of 2.0-4.0V, and the results are shown in Table 1:

Table 1 Electrochemical performance test data of sodium ion battery

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (8)

1. a preparation method of sodium ion battery active material, is characterized in that, comprises the following steps: S1. Using phosphorus source, iron source, and sodium source as reaction raw materials, and nano-metal as reducing agent, mix according to a set ratio to obtain a mixed product; S2, placing the mixed product obtained in step S1 under an inert atmosphere for ball milling to obtain a ball milled product; S3. Calcining the ball-milled product obtained in step S2 under an inert atmosphere, and cooling to obtain the active material for the sodium-ion battery; The chemical formula of the active material of the sodium ion battery is NaM _x Fe _y PO ₄ , 0<x<1, 0<y<1, M is selected from one of Mg, Al, Ti, V, Mn, Zn, Cr or Various. 2. according to the preparation method of the described sodium ion battery active material of claim 1, it is characterized in that, in step S1, described phosphorus source is in ammonium dihydrogen phosphate, diammonium hydrogen phosphate, sodium dihydrogen phosphate and phosphorus pentoxide one or more of. 3. The method for preparing the active material of the sodium-ion battery according to claim 1, characterized in that, in step S1, the iron source is one or more of iron phosphate and ferric oxide. 4. according to the preparation method of the described sodium ion battery active material of claim 1, it is characterized in that, in step S1, described sodium source is sodium carbonate, sodium bicarbonate, sodium hydroxide, sodium acetate, sodium phosphate, sodium hydrogen phosphate , sodium oxalate, sodium formate, sodium citrate, sodium pyrophosphate and sodium metaphosphate or one or more. 5 . The method for preparing the active material of a sodium ion battery according to claim 1 , wherein, in step S2 , the mixed product is placed in a planetary ball mill for ball milling, and the milling time is 0.5-24 hours. 6. The method for preparing the active material of the sodium ion battery according to claim 1, characterized in that, in step S3, the calcination process adopts segmental sintering, and the segmental sintering includes the working temperature of the first stage being 300-500°C, The material holding time is 2-8 hours; the working temperature of the second stage is 500-600°C, the material holding time is 0.5-4h, and the heating rate of each stage is controlled to be 1-5°C/min. 7. The preparation method of the active material of the sodium ion battery according to claim 1, wherein the inert atmosphere is any one of nitrogen, argon and helium. 8. The application of the preparation method of the active material of the sodium ion battery according to any one of claims 1 to 7 in the preparation of the positive electrode material of the sodium battery.