A sodium-ion battery anode material with single-atom sodium-loving sites, its preparation and application

Abstract

This invention belongs to the field of sodium-ion battery technology, specifically relating to a sodium-ion battery anode material with single-atom sodium-affinity sites, its preparation, and its application. The method includes the following steps: (I) dissolving sodium lignosulfonate and a metal salt in water in a specific ratio and placing them in a high-temperature, high-pressure reactor for hydrothermal reaction; (II) filtering, washing, and drying the product after the hydrothermal reaction, mixing it with a nitrogen source, and placing it in a high-temperature tube furnace for high-temperature carbonization to obtain the sodium-ion battery anode material. In the preparation method of this invention, the hydrothermal product after adding the metal salt can be directly carbonized at high temperature to prepare a hard carbon anode material with abundant micropores. Further high-temperature carbonization with a nitrogen source in step II can prepare a sodium-ion battery anode material with single-atom sodium-affinity sites. This invention solves the problems of slow sodium-ion migration rate and low reversible capacity in existing hard carbon anode materials.

Description

Technical Field

[0001] This invention belongs to the field of sodium-ion battery technology, specifically relating to a sodium-ion battery anode material with a single-atom sodium-loving site, its preparation and application. Background Technology

[0002] Sodium-ion batteries, due to their abundant sodium reserves, low production costs, and safety, have become a new generation of large-scale grid energy storage systems for advancing global carbon neutrality. As research on cathode materials (layered oxides, Prussian blue, etc.) matures and meets the requirements for commercial production, developing suitable anode materials has become a prerequisite for the large-scale commercialization of sodium-ion batteries.

[0003] Hard carbon, as a non-graphitizable carbon, has become the most suitable anode material for sodium-ion batteries due to its graphitic microcrystalline regions (interlayer spacing greater than 0.37 nm) suitable for sodium ion intercalation and its abundant hierarchical porous structure. However, the sodium storage mechanism of hard carbon is still controversial (typical charge-discharge curves of hard carbon include sodium storage in the slope region above 0.1V and sodium storage in the plateau region below 0.1V). The capacity in the low-voltage region and the slow sodium ion migration rate have become important factors limiting the energy density of sodium-ion batteries. Summary of the Invention

[0004] To address the issues of slow sodium ion migration rate and low reversible capacity in existing hard carbon anode materials, the primary objective of this invention is to provide a sodium-ion battery anode material with single-atom sodium-loving sites.

[0005] Another objective of this invention is to provide a method for preparing a sodium-ion battery anode material with a single-atom sodium-loving site.

[0006] Another object of the present invention is to provide the application of the above-mentioned sodium-ion battery anode material having a single-atom sodium-loving site.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A method for preparing a sodium-ion battery anode material with single-atom sodium-loving sites, comprising the following steps:

[0009] (I) Dissolve sodium lignosulfonate and metal salt in water in a certain proportion and carry out a hydrothermal reaction;

[0010] (II) The product after hydrothermal reaction is filtered, washed and dried, and then mixed with a nitrogen source and carbonized at high temperature to obtain the sodium-ion battery anode material.

[0011] Furthermore, in step I, the sodium lignosulfonate is a byproduct extracted from papermaking black liquor.

[0012] Further, in step I, the metal salt is one or more transition metal salts such as zinc chloride, ferric chloride, cobalt chloride, nickel chloride, copper chloride, manganese chloride, and magnesium chloride, with zinc chloride being the most preferred.

[0013] Further, in step I, the mass ratio of sodium lignosulfonate to metal salt is 1:0.1 to 1:5.

[0014] Furthermore, in step I, the solvent for the hydrothermal reaction is one or more of water and ethanol, preferably water.

[0015] Furthermore, in step I, the solid-liquid ratio in the hydrothermal reaction is 1:2 to 1:10 (g / mL), preferably 1:10 (g / mL).

[0016] Further, in step I, the temperature of the hydrothermal reaction is 100-250℃, the reaction time is 2-12h, and the heating rate is 10℃ / min; preferably, the temperature of the hydrothermal reaction is 200-250℃, and the reaction time is 4-12h; most preferably, the temperature of the hydrothermal reaction is 200℃, and the reaction time is 4h.

[0017] Further, in step II, the nitrogen source is one or more nitrogen-containing salts such as ammonium chloride, urea, ammonium oxalate, ammonium sulfate, and ammonium nitrate, preferably ammonium chloride.

[0018] Further, in step II, the mass ratio of the hydrothermal reaction product to the nitrogen source is 1:0.5 to 1:10, the mass ratio of the hydrothermal reaction product to the nitrogen source is 1:3 to 1:8, and most preferably 1:5.

[0019] Furthermore, in step II, the mixing method is ball milling, which means that the solid powder is pulverized and mixed evenly.

[0020] Further, in step II, the high-temperature carbonization process is divided into two stages: first, the temperature is raised to 600-900℃ and held for 1-4 hours, and then the temperature is raised to 1000-1400℃ and held for 1-4 hours. The carbonization heating rate is 5℃ / min, and the carbonization atmosphere is one or more of nitrogen and argon. More preferably, the first stage holding temperature is 800-900℃, and the second stage holding temperature is 1300-1400℃. Most preferably, the first stage holding temperature is 800℃, and the second stage holding temperature is 1300℃.

[0021] Furthermore, in step II, the carbonization product needs to be cleaned, ground, and dried to finally obtain a sodium-ion battery anode material with a single-atom sodium-loving site.

[0022] Furthermore, the present invention also discloses a sodium-ion battery anode material having a single-atom sodium-loving site, which is prepared by the aforementioned preparation method.

[0023] Furthermore, the present invention also discloses a sodium-ion battery assembled from the above-mentioned sodium-ion battery negative electrode material.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] This invention uses lignin sulfonate, a waste product from papermaking black liquor, as a raw material to prepare a high-value-added hard carbon anode product, reducing environmental pollution while realizing the value-added utilization of papermaking black liquor waste.

[0026] In the preparation method described in this invention, the hydrothermal product after adding a metal salt can be directly carbonized at high temperature to prepare a hard carbon anode material with abundant micropores. Further high-temperature carbonization with a nitrogen source in step II can then prepare a sodium-ion battery anode material with single-atom sodium-loving sites. This invention offers high flexibility and produces hard carbon with excellent performance.

[0027] In the preparation method of the present invention, when the metal salt is zinc chloride, the sodium-ion battery anode material with single-atom sodium-loving sites greatly improves the sodium ion migration rate by introducing metal single-atom sites (ZnN4C) inside the hard carbon material, thereby improving the rate performance of the hard carbon. Attached Figure Description

[0028] To more clearly illustrate the technical solutions adopted in the embodiments of the present invention or the prior art, the accompanying drawings involved in the description of the embodiments or the prior art will be briefly introduced below. It should be noted that these drawings only represent some embodiments of the present invention, and those skilled in the art can derive other related drawings based on these drawings without creative effort.

[0029] Figure 1 The sodium-ion battery charge-discharge curves of the sodium-ion battery anode materials prepared in Example 1, Comparative Example 7 and Comparative Example 9 of this invention are shown. The experimental results are all stable data obtained by repeating the experiment three times.

[0030] Figure 2 The sodium-ion battery rate performance diagrams are for the sodium-ion battery anode materials prepared in Example 1, Comparative Example 7, and Comparative Example 9 of this invention. The experimental results are all stable data obtained by repeating the experiment three times.

[0031] Figure 3 The diagram shows the cycle stability of sodium-ion batteries using sodium-ion battery anode materials prepared in Example 1 and Comparative Example 9 of this invention at a current density of 3 A / g. The experimental results are all stable data obtained by repeating the experiment three times.

[0032] Figure 4The diagram shows the pore size distribution of the sodium-ion battery anode materials prepared in Example 1, Comparative Example 7, and Comparative Example 9 of this invention.

[0033] Figure 5 Aberration-corrected electron microscope image of the sodium-ion battery anode material prepared in Example 1 of this invention;

[0034] Figure 6 The rate performance diagrams are for the sodium-ion battery anode materials prepared in Examples 2-7 of the present invention. The experimental results are all stable data obtained by repeating the experiment three times.

[0035] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0036] To clearly demonstrate the objectives, technical solutions, and advantages of the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be comprehensively and accurately described below. It should be understood that the following embodiments are only for illustrating the present invention and are not intended to limit it. Unless otherwise expressly stated, all technical and scientific terms used herein follow the general definitions within the technical field, and all reagents mentioned meet industrial or analytical purity standards. Furthermore, the accompanying drawings and descriptions are intended to help those skilled in the art to deeply understand this application, and are not intended to limit the subject matter covered by the claims.

[0037] Regarding the "range" mentioned in this application, it is defined by setting a lower limit and an upper limit, which define the boundaries of a specific range. Such a range may or may not include its endpoints, and can be freely combined; that is, any lower limit can be combined with any upper limit to form a new range.

[0038] Unless otherwise specified, all embodiments and their optional solutions in this application can be combined with each other to create new technical solutions. Similarly, unless otherwise specified, all technical features and their optional features in this application can also be combined with each other to form new technical solutions.

[0039] The present invention will now be described in detail, and includes the following specific steps:

[0040] (I) Sodium lignosulfonate and metal salt extracted from black liquor of papermaking are dissolved in water in a certain proportion and placed in a high temperature and high pressure reactor for hydrothermal reaction.

[0041] (II) The product after hydrothermal reaction is filtered, washed and dried, mixed with a nitrogen source, and placed in a high-temperature tube furnace for high-temperature carbonization to obtain the sodium-ion battery anode material with a single-atom sodium-loving site.

[0042] Example 1

[0043] (I) Sodium lignin sulfonate and zinc chloride extracted from papermaking black liquor were dissolved in 200 mL of water at a mass ratio of 1:5 and placed in a high-temperature and high-pressure reactor for hydrothermal reaction at 200°C for 4 h.

[0044] (II) The product after hydrothermal reaction is filtered, washed and dried with water, and then mixed with ammonium chloride (the mass ratio of hydrothermal reaction product to ammonium chloride is 1:5). The mixture is placed in a high-temperature tube furnace and heated to 800°C for 2 hours. Then the temperature is increased to 1300°C and held for 3 hours. The cooled material is then washed sequentially in 1 mol / L hydrochloric acid solution and water for 6 hours, and dried to obtain the sodium-ion battery anode material with single-atom sodium-loving sites.

[0045] Example 2

[0046] Example 2 follows the same preparation process as Example 1, except that the metal salt in step I of preparing the sodium-ion battery anode material with single-atom sodium-loving sites is ferric chloride.

[0047] Example 3

[0048] Example 3 follows the same preparation process as Example 1, except that the metal salt in step I of preparing the sodium-ion battery anode material with single-atom sodium-loving sites is cobalt chloride.

[0049] Example 4

[0050] Example 4 follows the same preparation process as Example 1, except that the metal salt in step I of preparing the sodium-ion battery anode material with single-atom sodium-loving sites is nickel chloride.

[0051] Example 5

[0052] Example 5 follows the same preparation process as Example 1, except that the metal salt in step I of preparing the sodium-ion battery anode material with single-atom sodium-loving sites is copper chloride.

[0053] Example 6

[0054] Example 6 follows the same preparation process as Example 1, except that the metal salt in step I of preparing the sodium-ion battery anode material with single-atom sodium-loving sites is manganese chloride.

[0055] Example 7

[0056] Example 7 follows the same preparation process as Example 1, except that the metal salt in step I of preparing the sodium-ion battery anode material with single-atom sodium-loving sites is magnesium chloride.

[0057] Example 8

[0058] Example 8 follows the same preparation process as Example 1, except that the nitrogen salt in step II of preparing the sodium-ion battery anode material with single-atom sodium-loving sites is ammonium sulfate.

[0059] Example 9

[0060] Example 9 follows the same preparation process as Example 1, except that the nitrogen salt in step II of preparing the sodium-ion battery anode material with single-atom sodium-loving sites is urea.

[0061] Example 10

[0062] Example 10 follows the same preparation process as Example 1, except that the nitrogen salt in step II of preparing the sodium-ion battery anode material with single-atom sodium-loving sites is ammonium nitrate.

[0063] Example 11

[0064] Example 11 follows the same preparation process as Example 1, except that the nitrogen salt in step II of preparing the sodium-ion battery anode material with single-atom sodium-loving sites is ammonium oxalate.

[0065] Comparative Example 1

[0066] Comparative Example 1 follows the same preparation process as Example 1, except that the hydrothermal reaction temperature in step I of preparing the sodium-ion battery anode material with single-atom sodium-loving sites is 100 degrees Celsius.

[0067] Comparative Example 2

[0068] Comparative Example 2 follows the same preparation process as Example 1, except that the hydrothermal reaction time in step I of preparing the sodium-ion battery anode material with single-atom sodium-loving sites is 2 hours.

[0069] Comparative Example 3

[0070] Comparative Example 3 follows the same preparation process as Example 1, except that in step I of preparing the sodium-ion battery anode material with single-atom sodium-loving sites, the mass ratio of sodium lignosulfonate to metal salt is 1:10.

[0071] Comparative Example 4

[0072] Comparative Example 4 follows the same preparation process as Example 1, except that: ammonium chloride is added in step II of preparing the sodium-ion battery anode material with single-atom sodium-loving sites, and the mass ratio of hydrothermal reaction product to ammonium chloride is 1:2.

[0073] Comparative Example 5

[0074] Comparative Example 5 follows the same preparation process as Example 1, except that: ammonium chloride is added in step II of preparing the sodium-ion battery anode material with single-atom sodium-loving sites, and the mass ratio of hydrothermal reaction product to ammonium chloride is 1:10.

[0075] Comparative Example 6

[0076] Comparative Example 6 follows the same preparation process as Example 1, except that the carbonization temperature in step II of preparing the sodium-ion battery anode material with single-atom sodium-loving sites is 600°C.

[0077] Comparative Example 7

[0078] Comparative Example 7 follows the same preparation process as Example 1, except that no metal salt is added in step I of preparing the sodium-ion battery anode material with single-atom sodium-loving sites.

[0079] Comparative Example 8

[0080] Comparative Example 8 follows the same preparation process as Example 1, except that the second carbonization temperature in step II of preparing the sodium-ion battery anode material with single-atom sodium-loving sites is 1200°C.

[0081] Comparative Example 9

[0082] Comparative Example 9 follows the same preparation process as Example 1, except that nitrogen salts are not added in step II of preparing the sodium-ion battery anode material with single-atom sodium-loving sites.

[0083] The sodium-ion battery anode materials with single-atom sodium-loving sites prepared in the various embodiments and comparative examples of the present invention were analyzed and tested, as follows:

[0084] Electrochemical performance testing: The electrochemical performance of sodium-ion battery anode materials with single-atom sodium-loving sites is usually tested in a half-cell system using the Xinwei button cell system, with 1 mol / L NaPF6 as the electrolyte.

[0085] Galvanostatic charge-discharge (GCD) testing was conducted on the Xinwei button battery testing system. The test procedure involved discharging followed by charging, with the charge and discharge test currents sequentially set to 0.02 A / g, 0.05 A / g, 0.1 A / g, 0.2 A / g, 0.5 A / g, 1 A / g, 3 A / g, and 0.02 A / g. Five cycles were performed at each current density to obtain the first-cycle charge-discharge curve and rate performance curve of the prepared material. The corresponding cycle stability test was conducted by setting the current density to 3 A / g and performing 5000 cycles.

[0086] Specific surface area and pore structure (BET) analysis were performed using a micropore analyzer (ASAP2060) at 77 K (liquid nitrogen bath) and 273 K (ice-water bath) for isothermal adsorption analysis of dry nitrogen and carbon dioxide, respectively. The surface area, pore diameter, and pore volume of the samples were calculated using equivalent analytical theories of Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH).

[0087] Depend on Figure 1 The first charge-discharge curves show that, after hydrothermal reaction by introducing metal salt, the comparative example 9, prepared by direct carbonization, has an initial coulombic efficiency of 84.5% and an initial charge capacity of 302 mAh / g. Furthermore, after carbonization by introducing a nitrogen source, Example 1, which has sodium-loving ZnN4C sites, has an initial coulombic efficiency of 88.7% and an initial charge capacity of 342 mAh / g. These are significant improvements compared to the initial coulombic efficiency of 59.8% and the initial charge capacity of 160 mAh / g of the blank comparative example 7.

[0088] Depend on Figure 2 As can be seen from the rate performance curves, Comparative Example 9, which was prepared by introducing metal salt water for hydrothermal carbonization and pore formation, and Example 1, which introduced a single-atom sodium-loving site, both exhibit superior rate performance compared to the blank Comparative Example 7 sample. This further verifies the feasibility of this metal salt-assisted hydrothermal carbonization and single-atom site-assisted improvement of sodium ion migration efficiency.

[0089] Depend on Figure 3 As can be seen from the cycling stability curves, after further introducing the single-atom sodium-loving site ZnN4C, in addition to the improvement of reversible capacity and rate performance, the ZnN4C site can further promote the uniform formation of SEI film on the surface of hard carbon anode, thereby improving its stability. Therefore, Example 1 shows better stability performance than Comparative Example 9 after cycling 5000 times at a high current of 3A / g, further proving the important role of the single-atom sodium-loving site of ZnN4C.

[0090] Depend on Figure 4 As can be seen from the pore size distribution diagram, the introduction of metal salts during the hydrothermal process (Comparative Example 9) significantly increases the content of micropores and mesopores in the hard carbon material, which is beneficial for further sodium storage. After further introducing a nitrogen source (Example 1), the volatilization of zinc is hindered due to the anchoring effect of the nitrogen source, resulting in a further decrease in the mesopore content compared to Comparative Example 7. Instead, it is transformed into a microporous structure that is more conducive to sodium storage.

[0091] Figure 5The image shows a spherical aberration electron microscope image of the sodium-ion battery anode material prepared in Example 1. The bright spots distributed therein are the ZnN4C single-atom sodium-loving sites introduced into the hard carbon material.

[0092] Figure 6 The graph shows the rate performance of the sodium-ion battery anode materials prepared in Examples 2-7. As can be seen from the graph, thanks to the low volatilization temperature of zinc, its performance is excellent among all similar metal salts.

[0093] To better illustrate the differences between the various embodiments and comparative examples, the test results of the embodiments and comparative examples are summarized in Table 1.

[0094] Table 1. Test results of Examples 1-11 and Comparative Examples 1-9

[0095]

[0096] Analysis of the table shows that the performance differences between different metal salts (Examples 2-7) are significant due to the varying volatilization temperatures of the different metal oxides formed after heating with different metal salts. This is because particles such as iron oxide and manganese oxide are difficult to volatilize at high temperatures and remain inside the carbon material, inducing excessive graphitization and resulting in hard carbon materials that cannot have suitable interlayer spacing for sodium intercalation. Furthermore, the anchoring effect of different nitrogen sources on zinc metal also varies significantly. In Example 8, ammonium sulfate was used as the nitrogen source to anchor zinc single atoms, achieving a reversible capacity of 341 mAh / g. However, the introduction of additional sulfur elements introduced during the process introduces additional defect sites, leading to a significant decrease in the first-cycle coulombic efficiency. Nitrogen sources such as ammonium nitrate, urea, and ammonium oxalate showed relatively poor performance.

[0097] The data from Examples 1-9 further illustrate that the construction of these single-atom sodium-loving sites is affected by the nitrogen source ratio and carbonization temperature. An excessively high nitrogen source ratio leads to an increase in defect content and a decrease in first-efficiency, while an excessively low ratio leads to a decrease in the number of sites and poor performance.

[0098] The above experimental results demonstrate that the metal brine thermal method employed in this invention, by adding a nitrogen source during the carbonization process to introduce single-atom sodium-affinity sites, can significantly improve the first-cycle coulombic efficiency and reversible capacity of hard carbon materials, while simultaneously inducing the formation of a uniform SEI film and enhancing its cycle stability. This invention not only achieves emission reduction and efficiency improvement in papermaking black liquor waste from the raw material perspective, but also features a simple process that can prepare high-performance sodium-ion battery anode materials with single-atom sodium-affinity sites.

[0099] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a sodium-ion battery anode material with single-atom sodium-loving sites, characterized in that, It includes the following steps: (I) Sodium lignosulfonate and a metal salt are dissolved in water in a certain proportion and subjected to a hydrothermal reaction; the metal salt is zinc chloride; the mass ratio of sodium lignosulfonate to metal salt is 1:0.1 to 1:5; the solvent for the hydrothermal reaction is one or more of water and ethanol; (II) The product after hydrothermal reaction is filtered, washed and dried, and then mixed with a nitrogen source and carbonized at high temperature to obtain the sodium-ion battery anode material; the nitrogen source is one or more of ammonium chloride, urea, ammonium oxalate, ammonium sulfate and ammonium nitrate. In step II, the mass ratio of the hydrothermal reaction product to the nitrogen source is 1:0.5 to 1:10; the high-temperature carbonization process is divided into two stages: first, the temperature is raised to 800-900℃ and held for 1-4 hours, and then the temperature is raised to 1000-1400℃ and held for 1-4 hours.

2. The preparation method according to claim 1, characterized in that, In step I, The solid-liquid ratio in the hydrothermal reaction is 1:2 to 1:10 g / mL.

3. The preparation method according to claim 1, characterized in that, In step I, the temperature of the hydrothermal reaction is 100-250℃, and the reaction time is 2-12h.

4. The preparation method according to claim 1, characterized in that, In step II, the nitrogen source is one or more of ammonium chloride, urea, ammonium oxalate, ammonium sulfate, and ammonium nitrate.

5. The preparation method according to claim 1, characterized in that, In step II, the carbonization heating rate is 5°C / min, and the carbonization atmosphere is one or more of nitrogen and argon.

6. A sodium-ion battery anode material with a single-atom sodium-loving site, characterized in that, It is prepared by the method described in any one of claims 1 to 5.

7. A sodium-ion battery, characterized in that, Its negative electrode is the sodium-ion battery negative electrode material according to claim 6.

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