Positive electrode with positive electrode / gel electrolyte integrated structure and preparation method and application thereof

Abstract

The invention relates to a positive electrode with a positive electrode / gel electrolyte integrated structure and a preparation method and application thereof. The preparation method comprises the following steps: mixing beta-type manganese dioxide (beta-MnO2), conductive carbon and a gelatin solution to obtain uniform positive electrode slurry; blade-coating a current collector with the positive electrode slurry to form gel to obtain a manganese dioxide positive electrode; and preparing a gel layer on the positive electrode by using gelatin, soaking the gel layer in the electrolyte for a certain time, and taking out the gel layer to obtain the positive electrode with the positive electrode / gel electrolyte integrated structure. A positive electrode / gel electrolyte efficient reaction interface is constructed, and the polarization phenomenon of ions in the transmission process is reduced, so that the cycling stability of the battery is improved; the gelatin-based hydrogel is utilized to integrate the positive electrode and the electrolyte, so that the electrochemical reaction kinetics of the battery is improved; and meanwhile, the gelatin material has the characteristics of good dispersity, no toxicity and environmental friendliness, so that the process is green. By applying the method, the flexible wearable battery with high safety can be designed and prepared.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and in particular relates to a positive electrode with a positive electrode / gel electrolyte integrated structure, and a preparation method and application thereof. Background Art

[0002] In today's era of rapid technological development, emerging electronic products such as wearable devices and flexible electronic devices are showing explosive growth, and the demand for flexible power sources is extremely urgent, which has prompted zinc-manganese batteries to attract much attention in the field of flexible power source research.

[0003] In the structure of traditional flexible zinc-manganese batteries, the interface contact between the gel-based or polymer-based electrolyte and the positive electrode is poor. During the frequent bending, stretching and other deformation processes of the flexible battery, it is very easy to break and delaminate, which in turn causes internal short circuits, posing a great threat to battery performance and safety. At the same time, the presence of traditional gel-based or polymer-based electrolytes inevitably increases the thickness and weight of the battery, which is not conducive to the pursuit of extremely thin and portable flexible electronic devices, and limits the application of flexible zinc-manganese batteries. Summary of the invention

[0004] In order to overcome a series of problems generated at the interface between the positive electrode and the gel electrolyte of the above-mentioned traditional zinc-manganese battery in flexible application scenarios, the present invention provides a method for preparing a positive electrode with a positive electrode / gel electrolyte integrated structure and its application.

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

[0006] A method for preparing a positive electrode with a positive electrode / gel electrolyte integrated structure comprises the following steps:

[0007] Step 1: Preparation of positive electrode

[0008] 1.1 Add gelatin into a solvent to swell and dissolve it to obtain gelatin solution A;

[0009] 1.2 Mix β-MnO2, KB carbon, and gelatin solution A obtained in step 1.1, and stir magnetically to obtain a uniform positive electrode slurry;

[0010] 1.3 Scrape the positive electrode slurry obtained in step 1.2 onto the current collector and obtain the positive electrode after gelation;

[0011] Step 2: Preparation of positive electrode with positive electrode / gel electrolyte integrated structure

[0012] 2.1 Add gelatin into the solvent to swell and dissolve, thereby obtaining gelatin solution B;

[0013] 2.2 Apply the gelatin solution B prepared in step 2.1 onto the positive electrode obtained in step 1.3, and then gel;

[0014] 2.3 The positive electrode in step 2.2 is immersed in an electrolyte to obtain a positive electrode with the positive electrode / gel electrolyte integrated structure.

[0015] Furthermore, in the step 1.1, the mass fraction of gelatin solution A is 1%-4%, the solvent is deionized water, the swelling temperature is 10-38°C, and the dissolution temperature is 50-70°C.

[0016] Furthermore, in the step 1.2, after the β-MnO2, KB carbon and gelatin solution A are mixed, the mass fraction of β-MnO2 is 55-75, the mass fraction of KB carbon is 20-35, the mass fraction of gelatin is 5-10, and the magnetic stirring time is 10h-15h.

[0017] Furthermore, in the step 1.3, the thickness of the slurry coating is 200 μm-300 μm, and the β-MnO2 loading is 0.8-3 mg.

[0018] Furthermore, in the step 2.1, the mass fraction of gelatin solution B is 5%-12%, the solvent is deionized water, the swelling temperature is 10-38°C, and the dissolution temperature is 50-70°C.

[0019] Furthermore, in the step 2.2, the amount of the coated gelatin solution is 150-350ul.

[0020] Furthermore, in the step 2.3, the electrolyte used for soaking is 1-2.5M ZnSO4 + 0.1-0.5M MnSO4 solution, the amount of electrolyte used is 5ml-20ml, and the soaking time is 2-8h.

[0021] The invention also discloses a positive electrode with a positive electrode / gel electrolyte integrated structure, which is prepared according to the above preparation method.

[0022] The invention also discloses the application of a positive electrode with a positive electrode / gel electrolyte integrated structure in a zinc-manganese battery, and assembles a battery with the positive electrode with the positive electrode / gel electrolyte integrated structure for electrochemical testing.

[0023] In the application of the present invention, the specific assembly operation of the zinc-manganese full battery is:

[0024] The method is to place an ordinary Zn negative electrode in a mold battery, and use plastic tweezers to gently buckle the prepared positive electrode / gel electrolyte and the electrolyte side onto the Zn negative electrode to ensure that the positive electrode and the Zn negative electrode are aligned and the electrolyte and the Zn negative electrode are in flat contact, and then encapsulate to obtain a zinc-manganese full battery with an integrated positive electrode / gel electrolyte structure.

[0025] The positive electrode with a positive electrode / gel electrolyte integrated structure prepared by the present invention has more excellent performance:

[0026] After assembling the zinc-manganese full battery, the positive electrode with the positive electrode / gel electrolyte integrated structure prepared in the embodiment has good cycle stability. At a charge and discharge rate of 2C, its specific capacity after 200 cycles is still 217.7 mAh g -1 , the Coulombic efficiency is close to 100%.

[0027] This result shows that the prepared positive electrode / gel electrolyte integrated structure positive electrode exhibits excellent electrochemical performance advantages in the zinc-manganese full battery system.

[0028] When charging and discharging at a 2C rate, the high capacity retention rate shows its structural stability and anti-attenuation ability. This is due to the continuous integration between the gelatin binder used in the positive electrode and the gelatin-based hydrogel electrolyte, which effectively reduces the loss of active substances caused by structural changes or side reactions during the charging and discharging process.

[0029] The high Coulomb efficiency further confirms that the positive electrode of the positive electrode / gel electrolyte integrated structure can achieve efficient reversibility of the electrochemical reaction, the electrons involved in the reaction can be effectively utilized, and minimal energy loss occurs during the charge transfer process.

[0030] The positive electrode of the positive electrode / gel electrolyte integrated structure prepared by the present invention has excellent cycle performance, and its mechanism is:

[0031] The gelatin binder builds an extremely stable integrated structure between the positive electrode and the gelatin-based hydrogel electrolyte. The rich functional groups on the gelatin molecular chain form a strong interaction with the ions in the electrolyte. The gel network formed by gelatin can effectively fix and disperse the positive electrode active substances. During the long-term cycle process, the dissolution, migration and agglomeration of the active substances are greatly inhibited. During the battery cycle, the gelatin-based material has certain flexibility and self-healing properties, and can self-heal through intermolecular interactions, ensuring the stability of the integrated structure of the positive electrode and the electrolyte, thereby ensuring the continuity of ion transmission.

[0032] The present invention has the following beneficial effects:

[0033] 1. The positive electrode with a positive electrode / gel electrolyte integrated structure prepared by the present invention constructs an extremely stable positive electrode / gel electrolyte interface, reduces the polarization phenomenon of ions during transmission, and thus improves the cycle performance of the battery.

[0034] 2. The positive electrode with a positive electrode / gel electrolyte integrated structure prepared by the present invention reduces the problems such as defects that may be caused by the introduction of the interface between the two, and improves the electrochemical reaction efficiency of the battery.

[0035] 3. The positive electrode with a positive electrode / gel electrolyte integrated structure prepared by the present invention ensures its safety in flexible batteries due to the excellent physical and chemical properties and environmental friendliness of gelatin materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The following is a further description with reference to the accompanying drawings.

[0037] Figure 1 This is a schematic diagram of the process of preparing a positive electrode with a positive electrode / gel electrolyte integrated structure according to Example 1 of the present invention. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0039] 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.

[0040] Unless otherwise specified, various reagents and raw materials used in the present invention can be purchased from the market.

[0041] In the present invention, the KB carbon is Ketjen black, model EC-600JD.

[0042] Example 1

[0043] Preparation of positive electrode with positive electrode / gel electrolyte integrated structure

[0044] Step 1: Accurately weigh 0.2 g of gelatin and 9.8 g of deionized water, swell them at room temperature (20°C) for 5 min, and then put them in a 60°C water bath to completely dissolve to obtain gelatin solution A;

[0045] Step 2: 0.36 g β-MnO2, 0.18 g KB carbon, and 3 g gelatin solution A were mixed. For the convenience of magnetic stirring, 2.5 ml deionized water was added and magnetic stirring was performed for 12 h to obtain a uniform positive electrode slurry.

[0046] Step 3: Apply the positive electrode slurry obtained in step 2 on the current collector with a coating thickness of 250 μm.

[0047] Step 4: Accurately weigh 0.5 g of gelatin and 4.5 g of deionized water, swell at room temperature (20°C) for 20 min, then place in a 60°C water bath to completely dissolve, and ultrasonically treat for 3 min to remove bubbles to obtain gelatin solution B.

[0048] Step 5: Take 250 μl of gelatin solution B and apply it to the positive electrode obtained in step 3 to form a gel.

[0049] Step 6: Soak the positive electrode in step 5 in 10 ml of 2M ZnSO4+0.2MMnSO4 electrolyte and take it out after 6 hours to obtain a positive electrode with an integrated structure of positive electrode / gel electrolyte.

[0050] A battery was assembled by assembling the above-mentioned positive electrode with the positive electrode / gel electrolyte integrated structure and a common zinc sheet negative electrode, and the cycle performance test was performed after standing.

[0051] The various properties obtained by the present invention are further described by the accompanying drawings:

[0052] from Figure 1 It can be seen that in the positive electrode with a positive electrode / gel electrolyte integrated structure prepared in Example 1 of the present invention, the gelatin hydrogel and the positive electrode present a complete integrated structure, and the gel electrolyte can be firmly attached to the positive electrode surface and successfully eliminate the interface.

[0053] Example 2

[0054] Preparation of positive electrode with positive electrode / gel electrolyte integrated structure

[0055] Step 1: Accurately weigh 0.1 g gelatin and 9.9 g deionized water, swell at 10°C for 5 min, and then put into a 50°C water bath to completely dissolve to obtain gelatin solution A;

[0056] Step 2: 0.33 g β-MnO2, 0.21 g KB carbon, and 6 g gelatin solution A were mixed and magnetically stirred for 10 h to obtain a uniform positive electrode slurry;

[0057] Step 3: Apply the positive electrode slurry obtained in step 2 on the current collector to form a gel with a coating thickness of 200 μm.

[0058] Step 4: Accurately weigh 0.25 g of gelatin and 4.75 g of deionized water, swell them at 10°C for 30 min, then put them in a 50°C water bath to dissolve completely, and ultrasonically treat them for 3 min to remove bubbles to obtain gelatin solution B.

[0059] Step 5: Pipette 150 μl of gelatin solution B onto the positive electrode obtained in step 3 to form a gel.

[0060] Step 6: Soak the electrode in step 5 in 5 ml of 1M ZnSO4+0.1M MnSO4 electrolyte and take it out after 2 hours to obtain the positive electrode with the positive electrode / gel electrolyte integrated structure.

[0061] The above positive electrode with the positive electrode / gel electrolyte integrated structure and the common zinc sheet negative electrode were assembled into a battery, and the cycle performance test was performed after standing. The battery assembled in Example 2 of the present invention showed relatively excellent cycle stability at a 2C rate, and during multiple charge and discharge cycles, the capacity attenuation of the battery assembled was lower than that of the common PVDF positive electrode / gelatin hydrogel electrolyte.

[0062] Example 3

[0063] Preparation of positive electrode with positive electrode / gel electrolyte integrated structure

[0064] Step 1: Accurately weigh 0.4 g gelatin and 9.6 g deionized water, swell at 38°C for 15 min, and then put into a 70°C water bath to completely dissolve to obtain gelatin solution A;

[0065] Step 2: 0.45 g β-MnO2, 0.12 g KB carbon, and 0.75 g gelatin solution A were mixed, and 4 ml of deionized water was added for magnetic stirring. The mixture was magnetically stirred for 10 h to obtain a uniform positive electrode slurry.

[0066] Step 3: Apply the positive electrode slurry obtained in step 2 on the current collector with a coating thickness of 300 μm.

[0067] Step 4: Accurately weigh 0.6 g of gelatin and 4.4 g of deionized water, swell them at 38°C for 30 min, then put them in a 70°C water bath to dissolve completely, and ultrasonically treat them for 3 min to remove bubbles to obtain gelatin solution B.

[0068] Step 5: Pipette 350 μl of gelatin solution B onto the positive electrode obtained in step 3 to form a gel.

[0069] Step 6: Soak the positive electrode in step 5 in 20 ml of 2.5M ZnSO4+0.5MMnSO4 electrolyte and take it out after 8 hours to obtain the positive electrode with the positive electrode / gel electrolyte integrated structure.

[0070] The positive electrode with the above-mentioned positive electrode / gel electrolyte integrated structure and the common zinc sheet negative electrode were assembled into a battery, and the cycle performance test was performed after standing. The battery assembled in Example 3 of the present invention showed relatively excellent cycle stability at a 2C rate, and during multiple charge and discharge cycles, the capacity attenuation of the battery assembled was lower than that of the common PVDF positive electrode / gelatin hydrogel electrolyte.

[0071] Comparative Example 1

[0072] Preparation of common PVDF cathode / gelatin hydrogel electrolyte

[0073] Step 1: Accurately weigh 0.1 g PVDF and 9.9 g NMP, mix them, and stir them magnetically at room temperature 20°C for 8 h to obtain a uniformly mixed solution;

[0074] Step 2: Mix 0.35 g β-MnO2, 0.1 g KB carbon, and 5 g PVDF solution, add 2.5 ml NMP, and stir magnetically for 12 h to obtain a uniform cathode slurry;

[0075] Step 3: Apply the positive electrode slurry obtained in step 2 on the current collector with a coating thickness of 250 μm.

[0076] Step 4: Accurately weigh 0.5 g of gelatin and 4.5 g of deionized water, swell at 20°C for 20 min, then place in a 60°C water bath to dissolve completely, and ultrasonically treat for 3 min to remove bubbles to obtain a gelatin solution.

[0077] Step 5: Pipette 200 μl of the gelatin solution in step 4 onto the positive electrode sheet in step 3.

[0078] Step 6: Soak the electrode in step 5 in 10 ml of 2MZnSO4+0.2MMnSO4 electrolyte and take it out after 6 hours to obtain the common PVDF positive electrode / gelatin hydrogel electrolyte material.

[0079] Table 1 is a rate performance table of the positive electrode assembled zinc-manganese full battery with a positive electrode / gel electrolyte integrated structure prepared in Example 1 of the present invention and the positive electrode assembled full battery prepared in Comparative Example 1 at 0.5C-5C, with 10 cycles at each rate.

[0080] Table 2 is a table showing the long cycle performance of the positive electrode assembled zinc-manganese full battery with a positive electrode / gel electrolyte integrated structure prepared in Example 1 of the present invention and the positive electrode assembled full battery prepared in Comparative Example 1 at 2C.

[0081] Table 1

[0082]

[0083] Table 2

[0084]

[0085] It can be seen from Table 1 that the positive electrode with a positive electrode / gel electrolyte integrated structure prepared in Example 1 of the present invention has a better rate performance than that of Comparative Example 1 after being assembled into a full battery. When the discharge rate is increased to 5C, it can still maintain 150 mAh g -1 When the discharge rate returns from the 5C high rate state to the 1C low rate state, the full battery capacity of Example 1 of the present invention can also quickly rise to 280mAh g -1, which fully reflects the structural stability of the positive electrode material and the reversibility of the internal reaction.

[0086] It can be seen from Table 2 that the battery corresponding to Example 1 of the present invention exhibits more excellent cycle stability at a 2C rate, and the specific capacity is still 217.7 mAh g after 200 cycles. -1 During multiple charge and discharge cycles, the battery capacity attenuation of the positive electrode assembly with an integrated positive electrode / gel electrolyte structure is lower.

[0087] The present invention has a positive electrode with a positive electrode / gel electrolyte integrated structure, constructs an extremely stable positive electrode / gel electrolyte integrated structure, reduces the polarization phenomenon of ions during transmission, and thus improves the cycle performance of the battery; uses gelatin-based hydrogel to improve the efficiency of the battery electrochemical reaction; and because the gelatin material has good dispersibility, non-toxicity and environmentally friendly characteristics, the process is green. The method can be used to design and prepare highly safe flexible wearable batteries.

[0088] 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 positive electrode having a positive electrode / gel electrolyte integrated structure, characterized in that: The following steps are involved: Step 1: Preparation of positive electrode 1.1 Add gelatin into a solvent to swell and dissolve it to obtain gelatin solution A; 1.2 Mix β-MnO2, KB carbon, and gelatin solution A obtained in step 1.1, and stir magnetically to obtain a uniform positive electrode slurry; 1.3 Scrape the positive electrode slurry obtained in step 1.2 onto the current collector to obtain a positive electrode by gelling; Step 2: Preparation of the positive electrode of the zinc-manganese battery with a positive electrode / gel electrolyte integrated structure 2.1 Add gelatin into the solvent to swell and dissolve, thereby obtaining gelatin solution B; 2.2 Apply the gelatin solution B prepared in step 2.1 onto the positive electrode obtained in step 1.3 to form a gel; 2.3 The positive electrode in step 2.2 is immersed in an electrolyte to obtain a positive electrode with the positive electrode / gel electrolyte integrated structure.

2. The method for preparing a positive electrode of a positive electrode / gel electrolyte integrated structure according to claim 1, characterized in that: In the step 1.1, the mass fraction of gelatin solution A is 1%-4%, the solvent is deionized water, the swelling temperature is 10-38°C, and the dissolution temperature is 50-70°C.

3. The method for preparing a positive electrode having a positive electrode / gel electrolyte integrated structure according to claim 1, characterized in that: In the step 1.2, after the β-MnO2, KB carbon and gelatin solution A are mixed, the mass fraction of β-MnO2 is 55-75, the mass fraction of KB carbon is 20-35, the mass fraction of gelatin is 5-10, and the magnetic stirring time is 10h-15h.

4. The method for preparing a positive electrode having a positive electrode / gel electrolyte integrated structure according to claim 1, characterized in that: In the step 1.3, the thickness of the slurry coating is 200 μm-300 μm, and the β-MnO2 loading is 0.8-3 mg.

5. The method for preparing a positive electrode having a positive electrode / gel electrolyte integrated structure according to claim 1, characterized in that: In the step 2.1, the mass fraction of gelatin solution B is 5%-12%, the solvent is deionized water, the swelling temperature is 10-38°C, and the dissolution temperature is 50-70°C.

6. The method for preparing a positive electrode having a positive electrode / gel electrolyte integrated structure according to claim 1, characterized in that: In step 2.2, 150-350ul of gelatin solution is transferred.

7. The method for preparing a positive electrode having a positive electrode / gel electrolyte integrated structure according to claim 1, characterized in that: In the step 2.3, the electrolyte used for soaking is 1-2.5M ZnSO4 + 0.1-0.5M MnSO4 solution, the amount of electrolyte used is 5ml-20ml, and the soaking time is 2-8h.

8. A positive electrode having a positive electrode / gel electrolyte integrated structure, characterized in that: The invention is prepared according to the preparation method according to any one of claims 1 to 7.

9. Use of a positive electrode with a positive electrode / gel electrolyte integrated structure according to claim 8 in a zinc-manganese battery, characterized in that: The battery was assembled with the positive electrode design having the positive electrode / gel electrolyte integrated structure and electrochemical testing was performed.

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