Gelatin-based carbon dot compound as well as preparation method and application thereof

Abstract

The invention relates to a preparation method and application of a gelatin-based carbon dot compound. The preparation method of the gelatin-based carbon dot compound comprises the following steps: adding gelatin into a solvent, swelling and dissolving to obtain a gelatin solution; putting the gelatin solution into a hydrothermal kettle, keeping the temperature at a certain temperature, and taking out to obtain a hydrothermal product solution; putting the product liquid subjected to hydrothermal treatment into a centrifugal machine, centrifuging, and taking out supernatant liquid; and drying the supernate to obtain the gelatin-based carbon dot compound. The gelatin-based carbon dot compound disclosed by the invention can be used as an electrode adhesive and is beneficial to reducing the positive electrode impedance of the zinc-manganese battery, the polymer layer can form a network structure and is beneficial to keeping the positive electrode structure stable, and an electrode prepared from the gelatin-based carbon dot compound has high specific capacity and excellent cycling stability.

Description

Technical Field

[0001] The present invention belongs to the field of electrode technology, and in particular relates to a gelatin-based carbon dot composite and a preparation method and application thereof. Background Art

[0002] As the global energy structure shifts to renewable energy, the demand for energy storage increases, and efficient and economical energy storage technologies are urgently needed. Although lithium-ion batteries (LIBs) are a mature energy storage technology, they face severe challenges in terms of raw material supply, safety, and cost. To this end, neutral aqueous zinc-ion batteries (AZIBs) have become a promising battery because the system is safe and the zinc metal anode has a high theoretical volumetric energy density.

[0003] Among the various cathode materials developed for AZlB, manganese dioxide (MnO 2 ) is an ideal electrode material and has been widely studied due to its high theoretical energy density. However, aqueous zinc-manganese dioxide batteries (Zn-MnO 2 ) challenges still exist. Summary of the invention

[0004] In order to overcome the above problems, the present invention provides a gelatin-based carbon dot composite and its preparation method and application. The gelatin-based carbon dot composite as a positive electrode binder is beneficial to reducing the positive electrode impedance, wherein the polymer can form a network structure, which is beneficial to maintaining the stability of the positive electrode structure, and the electrode prepared therefrom has a high specific capacity and excellent cycle stability.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A method for preparing a gelatin-based carbon dot composite comprises the following steps:

[0007] Step 1: adding gelatin into a solvent to swell and dissolve it to obtain a gelatin solution;

[0008] Step 2: putting the gelatin solution obtained in step 1 into a hydrothermal kettle, taking it out after keeping it warm, and obtaining a hydrothermal product solution;

[0009] Step 3: Place the hydrothermal product liquid obtained in step 2 into a centrifuge, centrifuge, and take out the supernatant;

[0010] Step 4: Dry the product obtained in step 3 to obtain the gelatin-based carbon dot complex.

[0011] Furthermore, in step 1, the mass fraction of gelatin is 3%-10%, the solvent is deionized water, the swelling temperature is 10-28°C, and the dissolution temperature is 45-65°C;

[0012] In the step 2, the hydrothermal insulation temperature is 150-240° C., and the insulation time is 3-10 hours.

[0013] Furthermore, in the step 3, the rotation speed of the centrifugal treatment is 5000-10000 r / min, and the centrifugal time is 5 min-20 min.

[0014] Furthermore, in step 4, the drying method is one of freeze drying and drying.

[0015] The invention also discloses a gelatin-based carbon dot composite, which is prepared according to the above preparation method.

[0016] The present invention also discloses an application of the gelatin-based carbon dot composite as a positive electrode binder in a zinc-manganese battery. The positive electrode is designed and prepared using the gelatin-based carbon dot composite as a binder, and a zinc-manganese full battery is assembled for electrochemical testing.

[0017] Furthermore, the application of the gelatin-based carbon dot composite as a positive electrode binder in a zinc-manganese battery specifically comprises the following steps:

[0018] Manganese dioxide, a conductive agent and a gelatin-based carbon dot composite are uniformly mixed and magnetically stirred to prepare a positive electrode slurry;

[0019] The positive electrode slurry is scraped onto titanium foil and cut into discs after drying as the positive electrode of button cells;

[0020] The above positive electrode sheet, common zinc sheet negative electrode and glass fiber separator were assembled into CR2025 button battery, and after standing, the cycle performance test was carried out.

[0021] Furthermore, the mass fraction of the gelatin-based carbon dot composite in the positive electrode slurry is 5%-20%, the magnetic stirring speed is 300-600r / min, and the time is 10h-15h.

[0022] Furthermore, the mass ratio of the manganese dioxide, the conductive agent and the gelatin-based carbon dot composite is 6-8:1.5-2:0.5-2.

[0023] Furthermore, the conductive agent is one of Ketjen black (KB), acetylene black (AB) and conductive carbon black (Super P).

[0024] The gelatin-based carbon dot composite prepared by the present invention has more excellent performance as a positive electrode binder:

[0025] After assembling the zinc-manganese full battery with the prepared positive electrode, it was charged and discharged at a rate of 5C. After 500 cycles, no obvious capacity decay occurred and the capacity was stable at 300 mAh g -1 about.

[0026] This result shows that the gelatin-based carbon dot composite prepared by the present invention shows great advantages as a positive electrode binder in the application of zinc-manganese batteries, and the composite gives the positive electrode extremely high structural stability.

[0027] During the high-rate charge and discharge process, the stress changes on the electrode material and the volume effects caused by ion insertion and extraction did not cause substantial damage to the overall structure of the electrode. The network structure formed by the polymer in the gelatin carbon dot composite effectively maintained the integrity and stability of the electrode structure, preventing the shedding of active substances and structural collapse, thereby ensuring the stable output of the battery capacity.

[0028] The gelatin-based carbon dot composite prepared in the present invention is used as a positive electrode binder to enable the manganese dioxide positive electrode to have excellent cycle performance, and its mechanism is:

[0029] The gelatin-based carbon dot composite reduces the internal impedance of the positive electrode, reduces polarization, and ensures efficient charging and discharging reactions of the battery.

[0030] The network structure formed by the polymer layer in the gelatin-based carbon dot composite binder not only enhances the mechanical strength of the electrode, but also provides a stable channel for ion transport. This network structure disperses and fixes the active substances well, further improving the stability of the active substances in the electrode.

[0031] The present invention has the following beneficial effects:

[0032] 1. The gelatin-based carbon dot composite binder for the positive electrode of a high-performance zinc-manganese battery prepared by the present invention has good ion-conducting properties, and the battery exhibits high performance under high-rate charge and discharge conditions.

[0033] 2. The gelatin-based carbon dot composite binder for the positive electrode of a high-performance zinc-manganese battery prepared by the present invention imparts structural stability to the positive electrode, thereby minimizing the capacity decay of the battery during long-term cycling and improving the charge and discharge cycle life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The following is a further description with reference to the accompanying drawings.

[0035] Figure 1 This is a TEM image of the gelatin-based carbon dot composite binder for high-performance zinc-manganese battery positive electrode prepared in Example 1 of the present invention.

[0036] Figure 2 Electrochemical impedance spectra of the gelatin-based carbon dot composite for high-performance zinc-manganese battery positive electrode prepared in Example 1 of the present invention and the battery assembled in Comparative Example 1. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0038] In the embodiments of the present invention, unless otherwise defined, all professional terms used hereinafter have the same meanings as those generally understood by those skilled in the art.

[0039] Unless otherwise specified, various reagents and raw materials used in the present invention can be purchased from the market.

[0040] Description of several conductive agents: The conductive agents used in the present invention are Ketjen black (KB), acetylene black (AB) and conductive carbon black (Super P).

[0041] Example 1

[0042] About the preparation of gelatin-based carbon dot composites:

[0043] Step 1: Swelling the gelatin in a 5% gelatin solvent at 25°C and then dissolving it at 60°C to obtain a gelatin solution;

[0044] Step 2: Put the mixed solution obtained in step 1 into a hydrothermal kettle, keep it at 180°C for 6 hours, and then take it out to obtain a hydrothermal product liquid;

[0045] Step 3: Place the hydrothermal solution obtained in step 2 into a centrifuge, centrifuge at 8000 r / min for 10 min, and take out the supernatant;

[0046] Step 4: Dry the product obtained in step 3 to obtain the gelatin-based carbon dot composite.

[0047] Manganese dioxide, conductive agent (KB) and gelatin-based carbon dot composite were mixed uniformly in a mass ratio of 7:2:1, and magnetically stirred at 500 r / min for 12 h to prepare a positive electrode slurry;

[0048] The positive electrode slurry is scraped onto the titanium foil and cut into discs after drying as the positive electrode sheets of button batteries;

[0049] The above-mentioned positive electrode sheet, common zinc sheet negative electrode and glass fiber separator were assembled into CR2025 button battery, and after standing, the cycle performance test was carried out.

[0050] Example 2

[0051] Step 1: Swelling the gelatin in a 10% gelatin solvent at 28°C and then dissolving the gelatin at 65°C to obtain a gelatin solution;

[0052] Step 2: Put the gelatin solution obtained in step 1 into a hydrothermal kettle, keep it at 240°C for 3 hours, then take it out to obtain a hydrothermal product liquid;

[0053] Step 3: Place the hydrothermal product liquid obtained in step 2 into a centrifuge, centrifuge at 10,000 r / min for 5 minutes, and take out the supernatant;

[0054] Step 4: Dry the product obtained in step 3 to obtain the gelatin-based carbon dot composite.

[0055] Manganese dioxide, conductive agent (AB) and gelatin-based carbon dot composite were uniformly mixed in a mass ratio of 6:2:2, and magnetically stirred at 600 r / min for 10 h to prepare a positive electrode slurry;

[0056] The positive electrode slurry is scraped onto titanium foil and cut into discs after drying as the positive electrode of button cells;

[0057] The above positive electrode sheet, common zinc sheet negative electrode and glass fiber separator were assembled into CR2025 button battery, and after standing, the cycle performance test was carried out.

[0058] Embodiment 3:

[0059] Step 1: Swelling the gelatin in a 3% gelatin solvent at 10°C and then dissolving it at 45°C to obtain a gelatin solution;

[0060] Step 2: Put the gelatin solution obtained in step 1 into a hydrothermal kettle, keep it at 150°C for 10 hours, then take it out to obtain a hydrothermal product liquid;

[0061] Step 3: Place the hydrothermal solution obtained in step 2 into a centrifuge, centrifuge at 5000 r / min for 20 min, and take out the supernatant;

[0062] Step 4: freeze-dry the product obtained in step 3 to obtain the gelatin-based carbon dot complex.

[0063] Manganese dioxide, a conductive agent (Super P) and a gelatin-based carbon dot composite were uniformly mixed in a mass ratio of 8:1.5:0.5, and magnetically stirred at 300 r / min for 15 h to prepare a positive electrode slurry;

[0064] The positive electrode slurry is scraped onto titanium foil and cut into discs after drying as the positive electrode of button cells;

[0065] The above positive electrode sheet, common zinc sheet negative electrode and glass fiber separator were assembled into CR2025 button battery, and after standing, the cycle performance test was carried out.

[0066] About assembling zinc-manganese batteries

[0067] In Example 1:

[0068] Manganese dioxide, conductive agent and gelatin-based carbon-carbon dots were mixed in a mass ratio of 7:2:1, magnetically stirred for a certain period of time to prepare a positive electrode slurry, which was then scraped onto titanium foil and cut into 12 mm discs after drying as the positive electrode of button batteries.

[0069] The above positive electrode sheet, common zinc sheet negative electrode and glass fiber separator were assembled into CR2025 button battery, the electrolyte was 2M ZnSO4 plus 0.2M MnSO4, and the assembled battery was left to stand for 8 hours;

[0070] Electrochemical performance test of zinc-manganese battery

[0071] The cycle performance of zinc-manganese batteries was tested on the charge and discharge equipment.

[0072] In Example 2, the mass ratio of manganese dioxide, conductive agent and gelatin-based carbon dot composite is 6:2:2; other operations are the same as Example 1.

[0073] In Example 3, the mass ratio of manganese dioxide, conductive agent and gelatin-based carbon dot composite is 8:1.5:0.5; other operations are the same as in Example 1.

[0074] The gelatin-based carbon dot composite for high-performance zinc-manganese battery positive electrode prepared in Example 1 has high performance. After 500 cycles at 5C, the specific capacity of the assembled full battery is about 300 mAh g -1 .

[0075] pass Figure 1 Example 1 is further described:

[0076] from Figure 1 It can be seen that the gelatin-based carbon dot composite was successfully synthesized, and the TEM images show that the quantum dots are evenly distributed in the composite;

[0077] from Figure 2 It can be seen that the battery assembled with gelatin-based carbon dot composite as the positive electrode binder has a smaller impedance than the battery assembled with PVDF as the positive electrode binder;

[0078] It can be seen from Table 1 that the electrode prepared with gelatin-based carbon dot composite as the positive electrode binder has excellent rate performance compared with the electrode prepared with PVDF as the positive electrode binder.

[0079] As can be seen from Table 2, the electrode prepared with gelatin-based carbon dot composite as the positive electrode binder has higher specific capacity and longer cycle stability than the electrode prepared with PVDF as the positive electrode binder, with a capacity of 307.2 mAh g-1 at 5C for 500 cycles. 1 Under the same conditions, the specific capacity of PVDF cathode is only 154 mAh g- 1 .

[0080] The gelatin-based carbon dot composite binder for high-performance zinc-manganese battery positive electrode prepared in Example 2 has excellent performance. After 500 cycles at 5C, the specific capacity of the assembled full battery is 270.3 mAh g -1 .

[0081] The gelatin-based carbon dot composite for high-performance zinc-manganese battery positive electrode prepared in Example 3 has excellent electrochemical performance. After 500 cycles at 5C, the specific capacity of the assembled full battery is about 247.8 mAh g -1 .

[0082] The gelatin-based carbon dot composite for high-performance zinc-manganese battery positive electrode prepared in Comparative Example 1 as a positive electrode binder has high performance. After 500 cycles at 5C, the specific capacity of the assembled full battery is 154 mAh g- 1 .

[0083] The electrical properties of the zinc-manganese full battery assembled in Example 1 are detailed in Tables 1 and 2:

[0084] Table 1 shows the rate performance results of the zinc-manganese full battery assembled with the gelatin-based carbon dot composite binder for the high-performance zinc-manganese battery positive electrode prepared in Example 1 of the present invention;

[0085] Table 2 shows the long cycle performance results at 5C of the zinc-manganese full battery assembled with the gelatin-based carbon dot composite binder for the high-performance zinc-manganese battery positive electrode prepared in Example 1 of the present invention, as shown in Table 1.

[0086] Table 1 List of zinc-manganese battery rate performance test results

[0087]

[0088] Table 2 List of test results of zinc-manganese battery cycle performance under 5C conditions

[0089]

[0090] As can be seen from Table 1, the electrode prepared using the gelatin-based carbon dot composite as a binder has excellent rate performance compared to the control group (electrode prepared using PVD F as a binder). As can be seen from Table 2, the electrode prepared using the gelatin-based carbon dot composite as a binder has high specific capacity and long cycle stability compared to the control group.

[0091] The gelatin-based carbon dot composite binder for the positive electrode of a high-performance zinc-manganese battery prepared by the present invention enables the battery to exhibit high performance under high-rate charge and discharge conditions. The gelatin-based carbon dot composite binder for the positive electrode of a high-performance zinc-manganese battery prepared by the present invention gives the positive electrode structure stability, so that the battery has little capacity decay during long-term cycles, and the battery cycle performance is significantly improved.

[0092] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the implementation of the present invention is not limited to the above-mentioned method. As long as various improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A method for preparing a gelatin-based carbon dot composite, characterized in that: The steps include: Step 1: adding gelatin into a solvent to swell and dissolve it to obtain a gelatin solution; Step 2: putting the gelatin solution obtained in step 1 into a hydrothermal kettle, taking it out after keeping it warm, and obtaining a hydrothermal product solution; Step 3: Place the hydrothermal product liquid obtained in step 2 into a centrifuge, centrifuge, and take out the supernatant; Step 4: Dry the product obtained in step 3 to obtain the gelatin-based carbon dot complex.

2. The method for preparing the gelatin-based carbon dot composite according to claim 1, characterized in that: In the step 1, the mass fraction of gelatin is 3%-10%, the solvent is deionized water, the swelling temperature is 10-28°C, and the dissolution temperature is 45-65°C; In the step 2, the hydrothermal insulation temperature is 150-240° C., and the insulation time is 3-10 hours.

3. The method for preparing the gelatin-based carbon dot composite according to claim 1, characterized in that: In the step 3, the rotation speed of the centrifugal treatment is 5000-10000 r / min, and the centrifugal time is 5 min-20 min.

4. The method for preparing the gelatin-based carbon dot composite according to claim 1, characterized in that: In step 4, the drying method is freeze drying or drying.

5. A gelatin-based carbon dot composite, characterized in that: The invention is prepared according to the preparation method according to any one of claims 1 to 4.

6. A use of the gelatin-based carbon dot composite according to claim 5 as a positive electrode binder in a zinc-manganese battery, characterized in that: The positive electrode was designed and prepared using the gelatin-based carbon dot composite as a binder, and a zinc-manganese full battery was assembled for electrochemical testing.

7. The use of the gelatin-based carbon dot composite as a positive electrode binder in a zinc-manganese battery according to claim 6, characterized in that: The specific operation includes the following steps: Manganese dioxide, a conductive agent and a gelatin-based carbon dot composite are uniformly mixed and magnetically stirred to prepare a positive electrode slurry; The positive electrode slurry is scraped onto titanium foil and cut into discs after drying as the positive electrode of button cells; The above positive electrode sheet, common zinc sheet negative electrode and glass fiber separator were assembled into CR2025 button battery, and after standing, the cycle performance test was carried out.

8. The use of the gelatin-based carbon dot composite as a positive electrode binder in a zinc-manganese battery according to claim 7, characterized in that: The mass fraction of the gelatin-based carbon dot composite in the positive electrode slurry is 5%-20%, the magnetic stirring speed is 300-600r / min, and the time is 10h-15h.

9. The use of the gelatin-based carbon dot composite as a positive electrode binder in a zinc-manganese battery according to claim 7, characterized in that: The mass ratio of the manganese dioxide, the conductive agent and the gelatin-based carbon dot composite is 6-8:1.5-2:0.5-2.

10. The use of the gelatin-based carbon dot composite as a positive electrode binder in a zinc-manganese battery according to claim 7, characterized in that: The conductive agent is one of Ketjen black (KB), acetylene black (AB) and conductive carbon black (SuperP).

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