Iron isophthalate negative electrode material for lithium battery and preparation method of iron isophthalate negative electrode material

Abstract

The invention discloses an iron isophthalate negative electrode material for a lithium battery and a preparation method. The iron isophthalate is synthesized by taking ferric chloride hexahydrate, isophthalic acid, sodium hydroxide and water as raw materials, the chemical formula of the iron isophthalate is Fe2 (C6H4 (COO) 2) 3, the specific surface area of the iron isophthalate is 65.2 m < 2 > g <-1 >, and the iron isophthalate is an ellipsoidal particle with the particle size of 50-350 nm. The preparation method of the material comprises the following steps: completely dissolving 2.4000 g of NaOH into 100 mL of deionized water, slowly adding 4.9839 g of isophthalic acid into the NaOH solution, and stirring at 30 DEG C for 1 hour until the solution is clarified to obtain a solution A; adding FeCl3. 6H2O into the solution A, heating to 60 DEG C, and stirring for 1-2 hours to obtain orange turbid liquid B; placing the turbid liquid B in a reaction kettle to react for 6-12 hours at 120-160 DEG C; and repeatedly centrifugally washing the product for 3-5 times, and drying at 100 DEG C for 12 hours to obtain iron isophthalate powder. The iron isophthalate is rich in raw material source, low in cost and simple and environment-friendly in preparation process, and has relatively high cycle capacity and retention rate when being used as a lithium ion battery negative electrode material.

Description

Technical Field

[0001] The invention discloses an iron isophthalate negative electrode material for lithium battery and a preparation method thereof, belongs to the field of negative electrode materials for lithium ion batteries, and specifically relates to the preparation and application of the material. Background Art

[0002] In the context of dual carbon action and energy transformation, lithium-ion batteries, as the leader in the field of energy revolution, are facing increasing demand and performance requirements. At present, the main negative electrode materials for lithium-ion batteries are carbon, transition metal oxides, tin-based, and silicon-based. Carbon-based negative electrodes have been commercialized, but the low lithium deintercalation potential of carbon-based negative electrodes easily leads to the formation of lithium dendrites, which seriously affects the safety performance of lithium-ion batteries; transition metal oxides have poor cycle stability and rapid capacity decay when used as negative electrode materials for lithium-ion batteries; and tin-based and silicon-based negative electrode materials for lithium-ion batteries will produce large volume expansion during the lithium deintercalation process, with rapid capacity decay and safety hazards. In general, it is difficult for current traditional negative electrodes to meet the needs of low cost, high capacity, and safety.

[0003] Metal organic frameworks (MOFs) have become a new type of negative electrode material for lithium-ion batteries with great potential due to their excellent structural designability. The structure and performance of MOFs are jointly determined by the type of ligand and the type of metal central ion. Researchers are constantly looking for suitable ligands and metal ions to prepare MOFs that can be used as negative electrodes for lithium-ion batteries. Patent CN118165285A discloses a method for preparing a Fe-based MOF lithium battery negative electrode material. The material of the invention uses 2,5-dihydroxyterephthalic acid as a ligand, and synthesizes an amorphous Fe-based MOF with a mixed-valence core-shell sphere structure through a solvent thermal reaction regulated by dissolved oxygen. It has good cycle performance when used in lithium-ion batteries, but the preparation of this material requires an oxygen-free environment, the preparation process conditions are harsh, the preparation method is relatively complicated, and the purity of the obtained sample is not high. Patent CN115241439A discloses a preparation method and application of a novel negative electrode material Al@MIL-53 for lithium-ion batteries. The invention uses aluminum powder and terephthalic acid as raw materials to synthesize Al@MIL-53 negative electrode material by hydrothermal method. The characteristics are low cost, high yield, and easy to control preparation conditions. However, the capacity retention rate of this material used as a negative electrode for lithium-ion batteries is poor, which is only about 12% after 50 cycles. Patent CN116682968A discloses a capacity self-activated MIL-100 (Fe) lithium-ion battery negative electrode material and its synthesis process. The ligand of the invention is trimesic acid, and its preparation method is hydrothermal method. The method is relatively simple but the cost of raw materials is high. In the document DOI:10.1016 / j.electacta.2017.03.095, Wang et al. used terephthalic acid as a ligand and used two methods to synthesize crystalline and amorphous zinc terephthalate (ZnTP). The synthesis method is simple and the raw material cost is low. However, the amorphous zinc terephthalate (ZnTP) with better electrochemical performance has a specific capacity of only 180 mAh / g at a current density of 50 mA / g.

[0004] Under the premise of fully considering the coordination stability of metals and organic ligands and the designability of the structure, it is of great practical significance to find a low-cost, simple and environmentally friendly preparation method, and high capacity and cycle retention rate MOFs negative electrode material for lithium batteries to provide high-performance negative electrode materials. Therefore, the present invention discloses an iron isophthalate negative electrode material for lithium batteries. In the early preparation process of iron isophthalate, we found that since sodium isophthalate is slightly soluble in water, directly using sodium isophthalate as a raw material has a low yield and is prone to side reactions. At the same time, isophthalic acid has the characteristics of being insoluble in cold water and slightly soluble in boiling water. Therefore, the present invention uses isophthalic acid and sodium hydroxide as raw materials, and the addition of NaOH promotes the deprotonation of isophthalic acid and increases the solubility of sodium isophthalate. It is found that this method can obtain a transparent solution through the reaction of isophthalic acid and sodium hydroxide, and at the same time has the effect of improving Fe 3+ with Na+ Multiple effects of reaction rate and feedstock conversion on the displacement to produce ferric isophthalate precipitate. Summary of the invention

[0005] The invention discloses an iron isophthalate negative electrode material for lithium battery, which is synthesized with ferric chloride hexahydrate, isophthalic acid, sodium hydroxide and water as raw materials. The chemical formula of the material is Fe2(C6H4(COO)2)3, and the specific surface area is 65.2m 2 g -1 , the pore structure is mesoporous, and the shape is elliptical particles with a particle size of 50-350nm. The preparation steps of the material are as follows: 2.4000g NaOH is dissolved in 100mL deionized water and stirred until it is clear to obtain a NaOH solution, and then 4.9839g isophthalic acid is slowly added to the NaOH solution, and stirred at 30℃ for 1h until the solution is clear to obtain solution A; FeCl3·6H2O is added to solution A, and the temperature is raised to 50-70℃ and stirred for 1-2h until the solution turns into an orange suspension B. The suspension B is transferred to a polytetrafluoroethylene reactor and crystallized in an oven at 140-160℃ for 6-12h. After the crystallization is completed, the solid-liquid centrifugation is performed at 8000r / min for 5min, and the solid product is washed 3-5 times with 50mL deionized water until the pH of the washing solution is 7-7.5. The centrifuged product is dried at 100℃ for 12h to obtain the iron isophthalate sample powder. The obtained iron isophthalate was used as the negative electrode material for lithium-ion batteries for battery assembly, and the electrochemical related performance was tested. The main raw materials are isophthalic acid and ferric chloride hexahydrate, which are abundant in source, low in cost, simple in preparation process and environmentally friendly, and have high cycle capacity and good rate performance when used as negative electrode materials for lithium-ion batteries.

[0006] The present invention has the following advantages:

[0007] 1. In the preparation process of iron isophthalate, due to the fact that isophthalic acid and sodium isophthalate are almost insoluble in water, the addition of NaOH plays an important role in promoting the deprotonation of isophthalic acid, increasing the solubility of sodium isophthalate, and thus improving the reaction rate and raw material conversion rate.

[0008] 2. The prepared iron isophthalate is in the shape of ellipsoidal particles with a particle size of 50 to 350 nm. The material has good stability, abundant raw material sources, low cost, simple and environmentally friendly preparation process, and high cycle capacity, cycle retention rate and safety. It is a new negative electrode material for lithium-ion batteries and has the potential for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is the XRD spectrum of the iron isophthalate material prepared in Example 5 of the present invention.

[0010] Figure 2 This is a SEM photograph of the iron isophthalate material prepared in Example 5 of the present invention.

[0011] Figure 3 It is a nitrogen adsorption / desorption isotherm curve and pore size distribution diagram of the iron isophthalate material prepared in Example 5 of the present invention.

[0012] Figure 4 This is a constant current charge and discharge cycle test chart of the iron isophthalate prepared in Example 5 of the present invention used as a negative electrode material for a lithium-ion battery. DETAILED DESCRIPTION

[0013] In order to better illustrate the purpose, technical scheme and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. It is particularly noted that the embodiments of the present invention are only used to illustrate the technical effects of the present invention, rather than to limit the scope of protection of the present invention. The raw materials used in the embodiments can all be obtained by commercial purchase.

[0014] Example 1

[0015] (1) Dissolve 2.4000 g of NaOH in 100 mL of deionized water and stir until the solution is clear to obtain a NaOH solution. Add 4.9839 g of isophthalic acid to the NaOH solution and stir at 30° C. for 1 h until the solution is clear to obtain a solution A.

[0016] (2) Add 5.4060 g FeCl3·6H2O to solution A, heat to 50°C and stir thoroughly for 2 h until the solution turns into orange suspension B;

[0017] (3) Transfer suspension B to a polytetrafluoroethylene reactor and place it in a 160°C oven for crystallization for 8 h;

[0018] (4) After the crystallization is completed, the solid-liquid centrifugation is performed at 8000 r / min for 5 min, and the solid product is washed 3 to 5 times with 50 mL of deionized water until the pH of the washing liquid is 7 to 7.5. The centrifuged product is dried at 100° C. for 12 h to obtain iron isophthalate.

[0019] Example 2

[0020] (1) Dissolve 2.4000 g of NaOH in 100 mL of deionized water and stir until the solution is clear to obtain a NaOH solution. Add 4.9839 g of isophthalic acid to the NaOH solution and stir at 30° C. for 1 h until the solution is clear to obtain a solution A.

[0021] (2) Add 5.4060 g FeCl3·6H2O to solution A, heat to 60°C and stir thoroughly for 1 h until the solution turns into orange suspension B;

[0022] (3) Transfer suspension B to a polytetrafluoroethylene reactor and place it in a 150°C oven for crystallization for 10 h;

[0023] (4) After the crystallization is completed, the solid-liquid centrifugation is performed at 8000 r / min for 5 min, and the solid product is washed 3 to 5 times with 50 mL of deionized water until the pH of the washing liquid is 7 to 7.5. The centrifuged product is dried at 100° C. for 12 h to obtain iron isophthalate.

[0024] Example 3

[0025] (1) Dissolve 2.4000 g of NaOH in 100 mL of deionized water and stir until the solution is clear to obtain a NaOH solution. Add 4.9839 g of isophthalic acid to the NaOH solution and stir at 30° C. for 1 h until the solution is clear to obtain a solution A.

[0026] (2) Add 5.4060 g FeCl3·6H2O to solution A, heat to 60°C and stir thoroughly for 2 h until the solution turns into orange suspension B;

[0027] (3) Transfer suspension B to a polytetrafluoroethylene reactor and place it in a 140°C oven for crystallization for 12 h;

[0028] (4) After the crystallization is completed, the solid-liquid centrifugation is performed at 8000 r / min for 5 min, and the solid product is washed 3 to 5 times with 50 mL of deionized water until the pH of the washing liquid is 7 to 7.5. The centrifuged product is dried at 100° C. for 12 h to obtain iron isophthalate.

[0029] Example 4

[0030] (1) Dissolve 2.4000 g of NaOH in 100 mL of deionized water and stir until the solution is clear to obtain a NaOH solution. Add 4.9839 g of isophthalic acid to the NaOH solution and stir at 30° C. for 1 h until the solution is clear to obtain a solution A.

[0031] (2) Add 5.4060 g FeCl3·6H2O to solution A, heat to 70°C and stir thoroughly for 1 h until the solution turns into orange suspension B;

[0032] (3) Transfer suspension B to a polytetrafluoroethylene reactor and place it in a 160°C oven for crystallization for 6 h;

[0033] (4) After the crystallization is completed, the solid-liquid centrifugation is performed at 8000 r / min for 5 min, and the solid product is washed 3 to 5 times with 50 mL of deionized water until the pH of the washing liquid is 7 to 7.5. The centrifuged product is dried at 100° C. for 12 h to obtain iron isophthalate.

[0034] Example 5

[0035] (1) Dissolve 2.4000 g of NaOH in 100 mL of deionized water and stir until the solution is clear to obtain a NaOH solution. Add 4.9839 g of isophthalic acid to the NaOH solution and stir at 30° C. for 1 h until the solution is clear to obtain a solution A.

[0036] (2) Add 5.4060 g FeCl3·6H2O to solution A, heat to 60°C and stir thoroughly for 2 h until the solution turns into orange suspension B;

[0037] (3) Transfer suspension B to a polytetrafluoroethylene reactor and place it in a 160°C oven for crystallization for 12 h;

[0038] (4) After the crystallization is completed, the solid-liquid centrifugation is performed at 8000 r / min for 5 min, and the solid product is washed 3 to 5 times with 50 mL of deionized water until the pH of the washing liquid is 7 to 7.5. The centrifuged product is dried at 100° C. for 12 h to obtain iron isophthalate.

Claims

1. A lithium battery negative electrode material made of iron isophthalate. It is characterized in that The ferric isophthalate is synthesized from ferric chloride hexahydrate, isophthalic acid, sodium hydroxide and water as raw materials, and its chemical formula is Fe 2 (C 6 H 4 (COO) 2 ) 3 , with a specific surface area of ​​65.2m 2 g -1 The pore structure is mesoporous and the shape is ellipsoidal particles with a particle size of 50 to 350 nm.

2. The method for preparing a lithium battery iron isophthalate negative electrode material according to claim 1, It is characterized in that The preparation steps are as follows: (1) Dissolve 2.4000 g of NaOH in 100 mL of deionized water and stir until the solution is clear to obtain a NaOH solution. Then slowly add 4.9839 g of isophthalic acid to the NaOH solution and stir at 30° C. for 1 h until the solution is clear to obtain a solution A. (2) 5.4060 g FeCl 3 6H 2 O is slowly added into solution A, and the temperature is raised to 50-70°C and stirred thoroughly for 1-2 hours until the solution turns into orange suspension B; (3) Transfer suspension B to a polytetrafluoroethylene reactor and crystallize in an oven at 140-160°C for 6-12 hours; (4) After the crystallization is completed, the solid-liquid centrifugation is performed at 8000 r / min for 5 min, and the solid product is washed 3 to 5 times with 50 mL of deionized water until the pH of the washing liquid is 7 to 7.

5. The centrifuged product is dried at 100° C. for 12 h to obtain iron isophthalate.

3. The iron isophthalate according to claim 1, It is characterized in that When used as negative electrode material for lithium-ion batteries, the discharge specific capacity after 50 cycles at a current density of 100 mA / g is 487 mA / g.

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