CN115172709A - High-performance strontium-doped ternary sodium-ion battery positive electrode material and preparation method thereof - Google Patents

Abstract

The invention discloses a high-performance strontium-doped ternary sodium-ion battery positive electrode material and a preparation method thereof. The chemical general formula of the anode material is Na _1‑x Sr _x [Ni _1‑y‑z Mn _y Fe _z ]O ₂ Wherein x is more than 0 and less than or equal to 0.04,0 and more than or equal to 1,0 and more than or equal to z is less than or equal to 1. The preparation method comprises the following steps: dispersing sodium-containing compound, nickel-containing compound, manganese-containing compound, iron-containing compound and strontium-containing compound in ionized water to obtain componentDispersing; stirring and grinding the dispersion liquid, and drying to obtain powder; calcining the obtained powder. According to the invention, strontium metal ions are doped to replace sodium sites, so that sodium ion channels are expanded, a layered structure is stabilized, and structural breakage caused by volume change in the process of sodium ion deintercalation is reduced. The prepared anode material can effectively improve the cycling stability and the discharge specific capacity of the sodium-ion battery, and the preparation process is simple and has high repeatability.

Description

A high-performance strontium-doped ternary sodium-ion battery cathode material and preparation method thereof

technical field

The invention relates to a high-performance strontium-doped ternary sodium-ion battery positive electrode material and a preparation method thereof, belonging to the technical field of sodium-ion batteries.

Background technique

As countries around the world vigorously promote the development and use of clean and renewable energy, higher requirements have also been placed on large-scale energy storage systems. Currently, lithium-ion batteries, which are widely used in 3C and electric vehicles, are the first candidates. However, the uneven distribution and low abundance of lithium resources have led to a surge in the prices of lithium salts such as lithium carbonate and lithium hydroxide in recent years. Although lithium-ion batteries can meet the energy density requirements of large-scale energy storage systems, the cost issue has become a major obstacle. The sodium-ion battery has a similar working principle to the lithium-ion battery, and has abundant sodium reserves and low cost. It is a battery system with great development potential and is suitable for large-scale energy storage systems.

The electrode materials of Na-ion batteries have a huge impact on the performance of Na-ion batteries. Compared with the negative electrode materials, the cathode materials have obvious disadvantages, such as low capacity, poor cycle performance and low energy density. It is particularly important to find new cathode materials with higher energy density, better cycle performance and high capacity and to modify them. Moreover, the cost and electrochemical performance of sodium-ion batteries mainly depend on the cathode material of the sodium-ion battery, which accounts for about 26% of the cost. In order to obtain an efficient, recyclable, non-toxic and harmless sodium-ion battery, the development of The battery cathode material is of great significance.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is: the problems of poor stability and cycle performance generally exist in the layered sodium ion battery.

In order to solve the above technical problems, the present invention provides a high-performance strontium-doped ternary sodium-ion battery positive electrode material, the general chemical formula of which is Na _1-x Sr _x [Ni _1-yz Mn _y F _z ]O ₂ , wherein , 0<x≤0.04, 0<y≤1, 0<z≤1.

The present invention also provides a method for preparing the above-mentioned high-performance strontium-doped ternary sodium-ion battery positive electrode material, comprising the following steps:

Step 1): weigh sodium-containing compounds, nickel-containing compounds, manganese-containing compounds, iron-containing compounds and strontium-containing compounds in proportion and disperse them in ionized water to obtain a dispersion;

Step 2): the dispersion is stirred and ground and then dried to obtain powder;

Step 3): calcining the powder obtained in step 2) to obtain a high-performance strontium-doped ternary sodium ion positive electrode material.

Preferably, the sodium-containing compound in the step 1) is sodium carbonate, the nickel-containing compound is nickel oxide, the manganese-containing compound is manganese oxide, the iron-containing compound is iron oxide, and the strontium-containing compound is strontium carbonate.

Preferably, in the step 1), the weight ratio of the sodium-containing compound, the nickel-containing compound, the manganese-containing compound, the iron-containing compound, and the strontium compound is 161-166:50-60:90-110:55-70:4-16 .

Preferably, the solid content of the dispersion obtained in the step 1) is 30-40 wt%.

Preferably, the grinding in the step 2) adopts a ball mill, and the grinding speed of the ball mill is 2500 r/min.

Preferably, the drying in the step 2) is spray drying.

Preferably, the calcination in the step 3) is placed in a tube furnace and calcined in an air atmosphere.

Preferably, the calcination in the step 3) is specifically: calcination at 850° C.˜950° C. for 10˜12 h.

The invention also provides the application of the above-mentioned high-performance strontium-doped ternary sodium-ion battery positive electrode material in a sodium-ion battery.

Ni, Fe and Mn in the ternary material Na _1-x Sr _x [Ni _1-yz M _y F _z ]O ₂ have different functions. It is generally believed that increasing the content of Mn element in the material can improve the structural stability of the material, and increasing the content of Ni element can improve the discharge specific capacity. Through doping modification, the ternary sodium-ion battery can maintain the structural stability while having a high discharge specific capacity.

Compared with the prior art, the beneficial effect of the present invention is that: the high-performance strontium-doped ternary sodium-ion battery positive electrode material of the present invention is doped with Sr to form a chemical formula of Na _1-x Sr _x [Ni _{1 -yz} Mn _y Fe _z ]O ₂ cathode material, the larger strontium ion radius can effectively expand the sodium ion channel, help to improve the diffusion ability of sodium ions, increase the ion migration rate, and improve the electrochemical performance of the cathode material; thus It can effectively improve the positive cycle stability and discharge specific capacity of the corresponding sodium-ion battery.

Description of drawings

1 is an X-ray diffraction diagram of a high-performance strontium-doped ternary sodium-ion battery cathode material prepared in Example 1;

Fig. 2 is the first charge-discharge curve diagram of the high-performance strontium-doped ternary sodium-ion battery cathode material prepared in Example 1 (charge-discharge start-stop voltage 1.75-4.4V, 0.1C rate, 1C=170mA/g);

Fig. 3 is the cycle performance curve diagram of the high-performance strontium-doped ternary sodium-ion battery positive electrode material prepared in Example 1 (charge-discharge start-stop voltage 1.75-4.4V, 1C rate, 1C=170mA/g);

FIG. 4 is an XRD refined curve diagram of the high-performance strontium-doped ternary sodium-ion battery cathode material prepared in Example 1. FIG.

Detailed ways

In order to make the present invention more obvious and comprehensible, preferred embodiments are described in detail below with reference to the accompanying drawings.

Example 1

A preparation method of a high-performance strontium-doped ternary sodium-ion battery cathode material, comprising the following steps:

(1) using sodium carbonate, nickel oxide, iron oxide, manganese oxide and strontium carbonate as raw materials, and its weight preparation ratio of parts and numbers is 166:56:107:60:4;

(2) Disperse the above-mentioned raw materials in deionized water, adjust the solid content in the dispersion to 40%, add it to a ball mill and grind, and adjust the grinding speed to 2500 r/min, and maintain a low temperature state during the grinding process;

(3) the solution after the ball milling is used to obtain a uniform powder by a spray dryer, and a small amount is compacted and then placed in a tube furnace for calcination;

(4) During sintering, the sintering temperature was 900° C., and the temperature was kept for 12 hours to obtain a strontium-doped ternary sodium-ion battery cathode material Na _0.99 Sr _0.01 [Ni _0.25 Mn _0.5 Fe _0.25 ]O ₂ .

The obtained material was detected by X-ray diffractometer (XRD, Rigaku, Japan). As shown in Figure 1, the diffraction pattern was refined by the software (EXPGUI) and confirmed to correspond to the α-NaFeO ₂ structure of the space group R3m without Obvious impurity peaks, thus determine the occupancy of strontium ions in the sodium position, and verify that the obtained material is Na _0.99 Sr _0.01 [Ni _0.25 Mn _0.5 Fe _0.25 ]O ₂ according to the raw material ratio.

Performance Testing:

The high-performance strontium-doped ternary sodium-ion cathode material prepared in Example 1 was used in a sodium-ion battery, and the cycle charge-discharge performance was tested. The first charge-discharge performance curve is shown in Figure 2, and its first charge voltage was 4.4 V, the discharge voltage is 1.75V, and the specific capacity of the first discharge is 158.8mAh/g. The cycle charge-discharge performance curve is shown in Figure 3. At a rate of 1C, the specific capacity of the first discharge is 121.8mAh/g, and after 100 cycles After the first cycle of charge and discharge, the discharge specific capacity is 96.8mAh/g, the discharge specific capacity of the battery only decreases by 25mAh/g, and the cycle retention rate is 80%, indicating that the above-mentioned positive electrode material has good cycle stability.

Example 2

A preparation method of a high-performance strontium-doped ternary sodium-ion battery cathode material, comprising the following steps:

(1) using sodium carbonate, nickel oxide, iron oxide, manganese oxide and strontium carbonate as raw materials, and the ratio of parts and numbers by weight is 164:56:107:60:8;

(2) Disperse the above-mentioned raw materials in deionized water, adjust the solid content in the dispersion to 40%, add it to a ball mill and grind, and adjust the grinding speed to 2500 r/min, and maintain a low temperature state during the grinding process;

(3) the solution after the ball milling is used to obtain a uniform powder by a spray dryer, and a small amount is compacted and then placed in a tube furnace for calcination;

(4) During sintering, the sintering temperature was 900° C., and the temperature was kept for 12 h to obtain a strontium-doped ternary sodium-ion battery cathode material Na _0.98 Sr _0.02 [Ni _0.25 Mn _0.5 Fe _0.25 ]O ₂ .

The obtained material was detected by X-ray diffractometer (XRD, Rigaku, Japan). The diffraction pattern was refined by software (EXPGUI) and confirmed to correspond to the α-NaFeO ₂ structure of space group R3m without obvious impurity peaks. This determines the occupancy of the strontium ion in the sodium site, and it is verified that the obtained material is Na _0.98 Sr _0.02 [Ni _0.25 Mn _0.5 Fe _0.25 ]O ₂ according to the raw material ratio.

Example 3

A preparation method of a high-performance strontium-doped ternary sodium-ion battery cathode material, comprising the following steps:

(1) using sodium carbonate, nickel oxide, iron oxide, manganese oxide and strontium carbonate as raw materials, and its weight preparation parts ratio is 163:56:107:60:12;

(2) Disperse the above-mentioned raw materials in deionized water, adjust the solid content in the dispersion to 40%, add it to a ball mill and grind, and adjust the grinding speed to 2500 r/min, and maintain a low temperature state during the grinding process;

(3) the solution after the ball milling is used to obtain a uniform powder by a spray dryer, and a small amount is compacted and then placed in a tube furnace for calcination;

(4) During sintering, the sintering temperature was 900° C., and the temperature was kept for 12 hours to obtain a strontium-doped ternary sodium-ion battery cathode material Na _0.97 Sr _0.03 [Ni _0.25 Mn _0.5 Fe _0.25 ]O ₂ .

The obtained material was detected by X-ray diffractometer (XRD, Rigaku, Japan). The diffraction pattern was refined by software (EXPGUI) and confirmed to correspond to the α-NaFeO ₂ structure of space group R3m without obvious impurity peaks. This determines the occupancy of strontium ions at the sodium site, and it is verified that the obtained material is Na _0.97 Sr _0.03 [Ni _0.25 Mn _0.5 Fe _0.25 ]O ₂ according to the raw material ratio.

Example 4

A preparation method of a high-performance strontium-doped ternary sodium-ion battery cathode material, comprising the following steps:

(1) using sodium carbonate, nickel oxide, iron oxide, manganese oxide and strontium carbonate as raw materials, the ratio of parts by weight is 161:56:107:60:16;

(2) Disperse the above-mentioned raw materials in deionized water, adjust the solid content in the dispersion to 40%, add it to a ball mill and grind, and adjust the grinding speed to 2500 r/min, and maintain a low temperature state during the grinding process;

(3) the solution after the ball milling is used to obtain a uniform powder by a spray dryer, and a small amount is compacted and placed in a tube furnace to be calcined with oxygen;

(4) During sintering, the sintering temperature was 900° C. and the temperature was kept for 12 hours to obtain a strontium-doped ternary sodium-ion battery cathode material Na _0.96 Sr _0.04 [Ni _0.25 Mn _0.5 Fe _0.25 ]O ₂ .

The obtained material was detected by X-ray diffractometer (XRD, Rigaku, Japan). The diffraction pattern was refined by software (EXPGUI) and confirmed to correspond to the α-NaFeO ₂ structure of space group R3m without obvious impurity peaks. This determines the occupancy of strontium ions at the sodium site, and it is verified that the obtained material is Na _0.96 Sr _0.04 [Ni _0.25 Mn _0.5 Fe _0.25 ]O ₂ according to the raw material ratio.

Claims (10)

1. A high-performance strontium-doped ternary sodium-ion battery positive electrode material, characterized in that the general chemical formula is Na _1-x Sr _x [Ni _1-yz M _y F _z ]O ₂ , wherein 0<x≤ 0.04, 0<y≤1, 0<z≤1. 2. the preparation method of high-performance strontium-doped ternary sodium-ion battery positive electrode material according to claim 1, is characterized in that, comprises the steps: Step 1): weigh sodium-containing compounds, nickel-containing compounds, manganese-containing compounds, iron-containing compounds and strontium-containing compounds in proportion and disperse them in ionized water to obtain a dispersion; Step 2): the dispersion is stirred and ground and then dried to obtain powder; Step 3): calcining the powder obtained in step 2) to obtain a high-performance strontium-doped ternary sodium ion positive electrode material. 3. The preparation method of high-performance strontium-doped ternary sodium-ion battery positive electrode material as claimed in claim 2, wherein the sodium-containing compound in the step 1) is sodium carbonate, and the nickel-containing compound is nickel oxide, The manganese-containing compound is manganese oxide, the iron-containing compound is iron oxide, and the strontium-containing compound is strontium carbonate. 4. The method for preparing a high-performance strontium-doped ternary sodium-ion battery positive electrode material according to claim 2, wherein in the step 1), a sodium-containing compound, a nickel-containing compound, a manganese-containing compound, and an iron-containing compound The weight ratio of the strontium compound is 161-166:50-60:90-110:55-70:4-16. 5 . The method for preparing a high-performance strontium-doped ternary sodium-ion battery positive electrode material according to claim 2 , wherein the solid content of the dispersion obtained in the step 1) is 30-40 wt %. 6 . 6. The preparation method of high-performance strontium-doped ternary sodium-ion battery positive electrode material as claimed in claim 2, wherein the grinding in the step 2) adopts a ball mill, and the grinding speed of the ball mill is 2500r/min . 7 . The method for preparing a high-performance strontium-doped ternary sodium-ion battery positive electrode material according to claim 2 , wherein the drying in the step 2) is spray drying. 8 . 8 . The method for preparing a high-performance strontium-doped ternary sodium-ion battery positive electrode material according to claim 2 , wherein the calcining in the step 3) is calcining in an air atmosphere in a tube furnace. 9 . 9. The method for preparing a high-performance strontium-doped ternary sodium-ion battery positive electrode material according to claim 2 or 8, wherein the calcination in the step 3) is specifically: calcining at 850°C to 950°C 10 to 12 hours. 10. Application of the high-performance strontium-doped ternary sodium-ion battery positive electrode material of claim 1 in a sodium-ion battery.

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