High-performance bismuth / carbon negative electrode material, preparation method and application of high-performance bismuth / carbon negative electrode material in sodium-ion battery

Abstract

The invention discloses a high-performance bismuth / carbon negative electrode material, a preparation method and application of the high-performance bismuth / carbon negative electrode material in a sodium-ion battery, and the preparation method comprises the following steps: taking basic bismuth gallate as a precursor material, and carrying out simple carbon thermal reduction treatment to obtain the final bismuth / carbon negative electrode material (Bi (at) C). The bismuth / carbon composite material prepared by the invention is uniformly loaded with metal bismuth nanoparticles and is coated with a carbon layer, the bismuth nanoparticles are used as a core sodium storage active component and provide higher capacity by virtue of excellent sodium ion embedding / de-embedding capability, and the carbon layer coated on the surface can promote electron transport and sodium ion diffusion and also can be used for preparing a sodium storage material. And the volume expansion and shrinkage of the metal bismuth in the charge-discharge cycle can be relieved, and the structural integrity of the electrode is guaranteed. By virtue of the synergistic effect of the bismuth and the carbon, the prepared bismuth / carbon negative electrode material has the advantage of high specific capacity when being used as a sodium-ion battery negative electrode material, and excellent rate capability and cycling stability are synchronously realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery materials, more particularly, to a high-performance bismuth / carbon negative electrode material and a preparation method and sodium-ion battery application thereof. BACKGROUND

[0002] With the transformation of global energy structure to renewable energy, the demand for large-scale energy storage technology is increasingly urgent. Although lithium-ion batteries have dominated the consumer electronics and electric vehicle fields, the limited reserves and uneven distribution of lithium resources in the earth's crust have led to a significant increase in their cost, which is constrained by resources, making it difficult to meet the long-term demand for low-cost and high-safety large-scale energy storage. Sodium-ion batteries, due to their abundant reserves, wide distribution and low cost, have shown great application potential in the field of large-scale energy storage and have become one of the important candidates to replace lithium-ion batteries. The mainstream layer oxide positive electrode has a similar crystal structure and manufacturing technology to the ternary oxide positive electrode of lithium-ion batteries, and is gradually realizing industrialization. However, the research on negative electrodes is difficult because the ionic radius of sodium ions is about 55% larger than that of lithium ions, causing a huge volume change when sodium ions are inserted into the negative electrode material, which destroys the integrity of the material. Therefore, the negative electrode materials commonly used in lithium-ion batteries cannot be well applied to sodium-ion batteries. Among the currently studied negative electrode materials, they can be divided into intercalation-type materials, conversion-type materials and alloy-type materials according to the sodium-ion storage mechanism. Among them, carbon materials (such as hard carbon, soft carbon and graphene) as one of the most commonly used negative electrode materials have good stability, but the specific capacity is relatively low. The capacity of intercalation-type materials such as titanium-based oxides is even lower, which is difficult to meet the demand for high energy density. Conversion-type materials such as transition metal compounds have a high theoretical capacity, but have problems such as serious volume expansion and poor conductivity. In comparison, alloy-type materials have higher energy density than intercalation-type materials and higher conductivity than conversion-type materials, becoming a research hotspot.

[0003] Metallic bismuth (Bi) is a novel alloy-type negative electrode material. Compared with other alloy-based negative electrodes, bismuth exhibits the most remarkable feature of a smooth and long-lasting voltage platform during alloying. It not only has a high theoretical capacity (385 mAh·g-1), but also has a relatively high density (9.8 g·cm-3), and a high volume specific capacity of 3765 mAh·cm-3. Moreover, the working voltage of bismuth is about 0.5 V, which is at a suitable level and can effectively improve the performance of the battery. Bismuth belongs to the hexagonal structure, and the interlayer spacing along the c-axis is large, which is beneficial to the diffusion of sodium ions. These characteristics make it a potential choice for sodium-ion battery negative electrode materials. However, during the alloying / de-alloying process, bismuth negative electrodes will undergo a huge volume change (expansion rate of about 250%) and cause material pulverization and structure collapse, which destroys the integrity of the material and causes capacity decay and shortens the service life.

[0004] To solve the problem of poor electrochemical performance caused by volume expansion of Bi, researchers have developed various strategies, such as constructing nanostructures, surface modification, and preparing binary Bi alloys. However, some preparation processes are complex, high in cost, high in energy consumption, and low in cycle capacity, such as the commonly used hydrothermal synthesis method which requires high temperature and high pressure conditions. Therefore, it is necessary to design a bismuth / carbon negative electrode material with simple preparation method, mild preparation conditions and excellent performance.

[0005] SUMMARY To overcome at least one problem existing in the prior art, the primary object of the present application is to provide a high-performance bismuth / carbon negative electrode material.

[0006] The second object of the present application is to provide a preparation method of the high-performance bismuth / carbon negative electrode material.

[0007] The third object of the present application is to provide a sodium ion battery The fourth object of the present application is to provide a preparation method of the sodium ion battery.

[0008] To achieve the above objects, the present application provides the following solutions: The present application provides that the bismuth / carbon negative electrode material is obtained by alkali bismuth gallate carbonization treatment, and the bismuth / carbon negative electrode material is composed of bismuth nanoparticles coated by carbon layers uniformly distributed on nanosheets.

[0009] The present application also provides a preparation method of the high-performance bismuth / carbon negative electrode material, comprising the following steps: The alkali bismuth gallate is subjected to carbonization treatment under inert gas atmosphere, the treatment temperature is 800℃, the holding time is 2h, and the heating rate is 5℃ / min, so that the high-performance bismuth / carbon negative electrode material can be obtained.

[0010] Further technical solutions of the present application: the inert gas is argon atmosphere.

[0011] The present application also provides a sodium ion battery, which comprises: the high-performance bismuth / carbon negative electrode material described above; a conductive agent (5-15 wt%) selected from carbon black; a binder (5-15 wt%) selected from sodium alginate.

[0012] The present application also provides a preparation method of the sodium ion battery described above, comprising the following steps: S1, grinding the bismuth / carbon negative electrode material, conductive carbon and binder in deionized water into a slurry, coating on a copper foil current collector, drying at 80℃ for 8-12h to prepare a negative electrode sheet, and cutting into electrode round pieces; S2, in a glove box without water and oxygen, the negative electrode shell of the button cell is placed flat on the base plate with the opening facing up, and the electrode sheet of step S1 is placed in the center of the negative electrode shell; then the electrode sheet surface is soaked with electrolyte drops, and the separator is clamped to cover the electrode sheet; the separator is soaked with electrolyte drops again, and the sodium metal sheet is clamped in the center of the separator, and then the positive electrode shell is sealed, thereby obtaining the button cell.

[0013] A further technical solution of the application is that the conductive carbon material is carbon black, and the binder is sodium alginate.

[0014] A further technical solution of the application is that the electrolyte used in step S2 is a sodium hexafluorophosphate solution (1.0M NaFP6 in DME = 100 Vol %), and the separator used is a glass fiber separator.

[0015] The application further provides a rapid charging method for a sodium ion battery, which uses the above-mentioned battery, the charging current density is 2-5 C, and the dendrite growth is inhibited by pulse voltage control during the charging process.

[0016] Finally, the application further provides an application of the above-mentioned high-performance bismuth / carbon negative electrode material in an energy storage system or an electric vehicle, and the working temperature range of the battery pack is 0-40℃.

[0017] Compared with the prior art, the application has the following beneficial effects: The application provides a high-performance bismuth / carbon negative electrode material and a preparation method and application thereof in a sodium ion battery, and bismuth nanoparticles coated with a carbon layer are obtained by carbon thermal reduction of alkali bismuth gallate. The nano-sized bismuth particles can shorten the sodium ion diffusion path, the external carbon layer has rich defects, provides an electron / sodium ion transmission channel, and effectively alleviates the volume change of the bismuth particles during the charging and discharging process, improves the structural stability of the electrode material, and thus improves the cycle stability and rate performance of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The SEM image of the bismuth / carbon negative electrode material (Bi@C) prepared in Example 1 of the application.

[0019] Figure 2 The TEM image of the bismuth / carbon negative electrode material (Bi@C) prepared in Example 1 of the application.

[0020] Figure 3 The HRTEM image of the bismuth / carbon negative electrode material (Bi@C) prepared in Example 1 of the application.

[0021] Figure 4 The element mapping image of the bismuth / carbon negative electrode material (Bi@C) prepared in Example 1 of the application.

[0022] Figure 5 Raman spectrum of the bismuth / carbon negative electrode material (Bi@C) prepared for Example 1 of the present application.

[0023] Figure 6 Cycle performance graph of the sodium ion half-cell assembled with the bismuth / carbon negative electrode material (Bi@C) prepared for Example 1 of the present application at 0.1 A g -1 of current density.

[0024] Figure 7 Cycle performance graph of the sodium ion half-cell assembled with the bismuth / carbon negative electrode material (Bi@C) prepared for Example 1 of the present application at 1 Ag -1 of current density.

[0025] Figure 8 Rate performance graph of the sodium ion half-cell assembled with the bismuth / carbon negative electrode material (Bi@C) prepared for Example 1 of the present application at different current densities. DETAILED DESCRIPTION

[0026] The embodiments of the present application will be described in detail below with examples, but those skilled in the art will understand that the following examples are only for illustration of the present application and should not be regarded as limiting the scope of the present application. If the specific conditions are not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are followed. If the manufacturers of the reagents or instruments used are not specified, they are all conventional products that can be obtained by commercial purchase.

[0027] It should be noted that: In the present application, all the embodiments and preferred implementation methods mentioned in the present text can be combined with each other to form new technical solutions, if not otherwise specified.

[0028] In the present application, unless otherwise specified, each reaction or operation step can be carried out sequentially or according to the sequence. Preferably, the reaction method in the present text is carried out sequentially.

[0029] Unless otherwise specified, the professional and scientific terms used in the present text have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the recorded content can also be applied in the present application.

[0030] Terminology Bi: (bismuth) bismuth; SEM: scanning electron microscope; TEM: transmission electron microscope; The present application provides the following solutions: The present application provides a high-performance bismuth / carbon negative electrode material, which is obtained by alkali bismuth gallate carbonization treatment, and the bismuth / carbon negative electrode material is composed of bismuth nanoparticles coated by carbon layers uniformly distributed on nanosheets.

[0031] The application also provides a preparation method of the high-performance bismuth / carbon negative electrode material, comprising the following steps: The alkali bismuth gallate is subjected to carbonization treatment in an inert gas atmosphere, the treatment temperature is 800 DEG C, the holding time is 2 h, and the heating rate is 5 DEG C / min, so that the high-performance bismuth / carbon negative electrode material is obtained.

[0032] In some preferred embodiments of the application, the inert gas is an argon atmosphere.

[0033] The application also provides a sodium ion battery, comprising the high-performance bismuth / carbon negative electrode material. The conductive agent (5-15 wt%) is selected from carbon black. The binder (5-15 wt%) is selected from sodium alginate.

[0034] The application also provides a preparation method of the sodium ion battery, comprising the following steps: S1, the bismuth / carbon negative electrode material, the conductive carbon and the binder are ground into a slurry in deionized water, coated on a copper foil current collector, dried at 80 DEG C for 8-12 h in a vacuum oven, and cut into an electrode wafer; S2, in an anhydrous and anaerobic glove box, the negative electrode shell of the button cell is opened upward, placed on a pad, and the electrode wafer of step S1 is placed in the center of the negative electrode shell; then the electrode wafer surface is soaked by adding electrolyte dropwise, and the separator is clamped to cover the electrode wafer; the separator is soaked again by adding electrolyte dropwise, and the sodium metal sheet is clamped to the center of the separator, and then the positive electrode shell is sealed, thereby obtaining a button cell.

[0035] In some preferred embodiments of the application, the conductive carbon material is carbon black, and the binder is sodium alginate.

[0036] In some preferred embodiments of the application, the electrolyte used in step S2 is a sodium hexafluorophosphate solution (1.0M NaFP6 in DME=100 Vol %), and the separator used is a glass fiber separator.

[0037] The application also provides a rapid charging method of a sodium ion battery, which uses the above-mentioned battery, the charging current density is 2-5 C, and the dendrite growth is inhibited by pulse voltage control during the charging process.

[0038] Finally, the application also provides an application of the above-mentioned composite material in an energy storage system or an electric vehicle, and the working temperature range of the battery pack is 0-40 DEG C.

[0039] Next, the preparation method of the high-performance bismuth / carbon negative electrode material (Bi@C) and the preparation method of the nano-ion battery are described in detail with specific examples.

[0040] Example 1 Preparation of bismuth / carbon negative electrode material (Bi@C) The preparation method comprises the following steps: The prepared bismuth subgallate is transferred into a porcelain boat, and then the porcelain boat is placed into a quartz tube. The quartz tube is heated to 800℃ at a heating rate of 5℃ / min under an argon atmosphere through a tube furnace, and kept at a constant temperature for 2 hours to obtain Bi@C. -1

[0041] Figure 1 The scanning electron microscope (SEM) image of the bismuth / carbon negative electrode material (Bi@C) obtained in Example 1 is shown in FIG. 1. It can be seen from FIG. 1 that the carbon thermal reduction obtains bismuth nanoparticles uniformly distributed on the surface of nanosheets, and a layer of carbon layer is coated on the surface of the nanoparticles. Figure 1

[0042] Figure 2 The transmission electron microscope (TEM) image of the bismuth / carbon negative electrode material (Bi@C) obtained in Example 1 is shown in FIG. 2. It can be further observed from FIG. 2 that the carbon layer wraps the bismuth nanoparticles. Figure 2

[0043] Figure 3 The high-resolution transmission electron microscope (HRTEM) image of the bismuth / carbon negative electrode material (Bi@C) obtained in Example 1 is shown in FIG. 3. The lattice fringes indicated in FIG. 3 correspond to the 012 crystal plane of bismuth, indicating the formation of bismuth nanoparticles. Figure 3

[0044] Figure 4 The element mapping image of the bismuth / carbon negative electrode material (Bi@C) obtained in Example 1 is shown in FIG. 4, which shows that the synthesized Bi@C composite material contains Bi, C and O elements, and is uniformly distributed.

[0045] Figure 5 The Raman spectrum of the bismuth / carbon negative electrode material (Bi@C) obtained in Example 1 is shown in FIG. 5. The D peak and G peak of carbon material appear, and the ratio is 1.0358, indicating a high degree of graphitization.

[0046] Example 2 The bismuth / carbon negative electrode material (Bi@C) obtained in Example 1, conductive carbon and sodium alginate are ground uniformly in a mortar at a mass ratio of 8:1:1 to form a slurry with good dispersibility, and then uniformly coated on a copper foil current collector. After vacuum drying at 80℃ for 8-12h, an electrode sheet is prepared, and the electrode sheet is cut into an electrode disc.

[0047] Example 3 Preparation of a button cell ​​​​A CR 2032 button cell with sodium metal as the counter / reference electrode was used to construct the test cell, which was operated in an argon-filled glove box, with the negative shell of the button cell opened upward, placed flat on a pad, and the electrode sheet of Example 2 placed in the center of the negative shell; then 1 drop of electrolyte was added to the electrode sheet surface using a rubber-tipped dropper, and a glass fiber separator was clamped to cover the electrode sheet; 3-4 drops of electrolyte were added to the separator, and a sodium metal sheet was clamped in the center of the separator; finally, a gasket and steel plate were placed in the center of the sodium metal sheet, and the positive shell was sealed after being covered, and the button cell was obtained.

[0048] Electrochemical performance test of application example 1 The button cell prepared in Example 3 was subjected to electrochemical performance (cycle performance and rate performance) testing using a multi-channel battery tester (Wuhan LanDian). The test voltage range was 0.01 V-1.5 V vs. Na / Na + . During cycle performance testing, the current density was 0.1 A g -1 and 1 A g -1 ; during rate performance testing, the initial current density was 0.1 A g -1 , which was sequentially increased to 0.2 A g -1 , 0.5 A g -1 , 1 A g -1 , 2 A g -1 , 5 A g -1 , 10 A g -1 , 15 A g -1 , and 20 A g -1 , and then returned to 0.1 A g -1 . Figure 6 Cycle performance of bismuth / carbon negative electrode material (Bi@C) at a current density of 0.1 A g -1 . At a current density of 0.1 A g -1 , the cycle was 500 times, with a high reversible capacity of 316 mAh g -1 .

[0049] Figure 7 Cycle performance of bismuth / carbon negative electrode material (Bi@C) at a current density of 1 A g -1 . At a current density of 1 A g -1 , the cycle was 200 times, with a high reversible capacity of 315 mAh g -1 , indicating that the bismuth / carbon negative electrode material (Bi@C) has excellent high specific capacity and cycle stability.

[0050] Figure 8The figure of rate performance of bismuth / carbon negative electrode material (Bi@C) at current density from 0.1 A g -1 to 20 A g -1 The bismuth / carbon negative electrode material (Bi@C) can obtain 287.8 mAh g -1 of sodium storage capacity even at a large current density of 20 A g -1 It can be seen that the prepared Bi@C has excellent performance and has great potential in sodium ion batteries.

[0051] The application provides a high-performance bismuth / carbon negative electrode material, a preparation method thereof and sodium ion battery application. The preparation method comprises the following steps: taking alkaline bismuth gallate as a precursor material, and obtaining a final bismuth / carbon negative electrode material (Bi@C) through simple carbon thermal reduction treatment. The bismuth / carbon composite material prepared by the application uniformly loads metal bismuth nanoparticles and is coated by a carbon layer, wherein the bismuth nanoparticles serve as a core sodium storage active component and provide a high capacity due to the excellent sodium ion intercalation / deintercalation capacity, and the surface-coated carbon layer can promote electron transmission and sodium ion diffusion and also can relieve the volume expansion and shrinkage of metal bismuth generated in the charge and discharge cycle, thus guaranteeing the integrity of the electrode structure. Relying on the synergistic effect of the two, the prepared bismuth / carbon negative electrode material, when used as a sodium ion battery negative electrode material, not only has a high specific capacity advantage, but also simultaneously realizes excellent rate performance and cycle stability.

[0052] In the description of the present specification, the description referring to the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0053] Although several embodiments of the present application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A high-performance bismuth / carbon anode material, characterized in that: The bismuth / carbon anode material is obtained by carbonization of basic bismuth gallate, and the bismuth / carbon anode material is composed of bismuth nanoparticles coated with a carbon layer uniformly distributed on nanosheets.

2. The method for preparing the high-performance bismuth / carbon anode material according to claim 1, characterized in that: Includes the following steps: Basic bismuth gallate was carbonized in an inert gas atmosphere at a temperature of 800℃ for 2 hours with a heating rate of 5℃ / min to obtain a high-performance bismuth / carbon anode material.

3. The method for preparing the high-performance bismuth / carbon anode material according to claim 2, characterized in that: The inert gas is an argon atmosphere.

4. A sodium-ion battery, characterized in that: It includes: The high-performance bismuth / carbon anode material as described in claim 1; Conductive agent (5~15 wt%), selected from carbon black; The binder (5~15 wt%) is selected from sodium alginate.

5. The method for preparing the sodium-ion battery according to claim 4, characterized in that: Includes the following steps: S1, the bismuth / carbon negative electrode material, conductive carbon and binder described in claim 1 are ground into a slurry in deionized water, coated onto a copper foil current collector, and dried under vacuum at 80°C for 8-12 hours to form a negative electrode sheet, which is then cut into electrode discs. S2. In an anhydrous and oxygen-free glove box, place the button cell with the negative electrode shell opening facing upwards on a pad, and place the electrode sheet from step S1 in the center of the negative electrode shell; then drip electrolyte to wet the surface of the electrode sheet, and clamp the separator to cover the electrode sheet; drip electrolyte again to wet the separator, and clamp the sodium metal sheet in the center of the separator, cover with the positive electrode shell and seal to obtain the button cell.

6. The method for preparing a sodium-ion battery according to claim 5, characterized in that: The conductive carbon material is carbon black, and the binder is sodium alginate.

7. The method for preparing a sodium-ion battery according to claim 5, characterized in that: The electrolyte used in step S2 is sodium hexafluorophosphate solution (1.0M NaFP6 in DME=100 Vol %), and the diaphragm used is a glass fiber diaphragm.

8. A method for fast charging a sodium-ion battery, characterized in that, The battery described in claim 4 has a charging current density of 2~5 C, and dendrite growth is suppressed by pulsed voltage control during the charging process.

9. The application of the high-performance bismuth / carbon anode material according to claim 1 in energy storage systems or electric vehicles, characterized in that, The battery pack operates in a temperature range of 0~40℃.

Images