Use of a graphene composite and zinc-ion battery

Abstract

The application discloses application of a graphene composite material and a zinc ion battery. In the application of the graphene surface grafted radical polymer composite material (GO-g-PTMA or rGO-g-PTMA) as a positive electrode material of a zinc ion secondary battery, the grafting content of poly(4-methacryloxy-2,2,6,6-tetramethylpiperidinyl nitroxide) in the composite material is 45% to 55%. The zinc ion battery of the application also reaches a high capacity at a high voltage, and in addition, the zinc ion battery of the application also has excellent rate and cycle performance at a high voltage and a current.

Description

Technical Field

[0001] This invention relates to the application of a graphene composite material and zinc-ion batteries. Background Technology

[0002] Energy and the environment are global issues that cannot be ignored in the 21st century. Due to the non-renewable nature of fossil fuels and the greenhouse effect caused by overuse, developing clean and efficient renewable energy has become a common goal worldwide. In recent years, electric vehicles and smart electronic devices have developed rapidly, and secondary batteries, due to their high energy density, long cycle life, and portability, have become the most widely researched and applied energy storage system. Currently, commercially used secondary batteries are mainly lithium-ion batteries, but the Earth's limited lithium resources are increasingly unable to meet the explosively growing demand, and the safety issues of lithium-ion batteries have not been completely resolved. Therefore, developing a safe secondary battery that can replace lithium-ion batteries is of great significance. Non-toxic multivalent metals (such as magnesium, zinc, calcium, and aluminum) are widely distributed in nature, have low cost, and good safety, making them excellent performance materials for negative electrodes in secondary batteries. Among them, zinc (Zn) has the best safety performance, is stable in air, has a high auto-ignition temperature of 460℃, and has a volumetric capacity of up to 5851 mAh / mL when used as a negative electrode. -1 It has broad application prospects.

[0003] In the field of battery cathode materials, polyvalent metal ions face higher lattice energy and deformation tension during the insertion and extraction processes of inorganic cathode materials, making them more prone to lattice deformation and irreversible collapse. Furthermore, inorganic materials still present problems such as toxicity, environmental pollution, and unsustainable development. Therefore, organic cathode materials are a better choice. In 1985, Yaniger's research group first used the organic compound polyaniline (PANI) as a cathode material for zinc-ion batteries. In the following decades, more and more organic materials have been applied to zinc-ion batteries, including conductive polymers, carbonyl-containing monomers and polymers, and nitroxide radical polymers. Compared with other organic materials, nitroxide radical polymers possess very high redox potentials and fast redox kinetics, making them a high-performance cathode material for zinc-ion batteries. However, previous studies have shown that radical polymers applied to zinc-ion batteries cannot achieve high capacity at high voltages. Therefore, solving these problems will help to better apply radical polymers in zinc-ion batteries. Summary of the Invention

[0004] The technical problem this invention aims to solve is to overcome the deficiency of low capacity at high voltages when using free radical polymers in zinc-ion batteries, and to provide an application of graphene composite materials and a zinc-ion battery. The zinc-ion battery of this invention achieves high capacity even at high voltages. Furthermore, the zinc-ion battery of this invention also exhibits excellent rate performance and cycle life under high voltage and current.

[0005] This invention provides the use of a graphene surface-grafted free radical polymer composite material (GO-g-PTMA or rGO-g-PTMA) as a positive electrode material for zinc-ion secondary batteries. The free radical polymer is poly(4-methacryloyloxy-2,2,6,6-tetramethylpiperidine nitroxide radical), and the grafting content of poly(4-methacryloyloxy-2,2,6,6-tetramethylpiperidine nitroxide radical) in the composite material is 45%-55%. Alternatively, the composite material can be prepared by a method comprising the following steps:

[0006] (1) Grafting: In a solvent, graphene with a water content of 80-97% is polymerized with 2,2,6,6-tetramethyl-4-piperidin methacrylate (TMPM) in the presence of an initiator to prepare an intermediate product;

[0007] (2) Oxidation: The intermediate product, disodium ethylenediaminetetraacetate, sodium tungstate and hydrogen peroxide are oxidized in a solvent.

[0008] Preferably, the grafting content of poly(4-methacryloyloxy-2,2,6,6-tetramethylpiperidine nitroxide radical) in the composite material is 50%.

[0009] The grafting content is defined as the percentage of the mass of the grafted polymer to the total mass of the grafted composite material.

[0010] In the grafting process, the graphene may be reduced graphene oxide (rGO) and / or graphene oxide (GO).

[0011] In the grafting process, the water content of the graphene can be 97%.

[0012] In the grafting process, the mass ratio of graphene to 2,2,6,6-tetramethyl-4-piperidinium methacrylate (TMPM) is a conventional ratio, preferably 1:(2-100), for example 1:20.

[0013] In the grafting process, the initiator is a free radical initiator conventionally used in the art, preferably azobisisobutyronitrile and / or benzoyl peroxide.

[0014] In the grafting process, the molar ratio of 2,2,6,6-tetramethyl-4-piperidin methacrylate to the initiator is a conventional ratio, preferably (200-50):1, for example 68:1.

[0015] In the grafting process, the solvent is a conventional solvent in the art, preferably one or more of N-methylpyrrolidone, methanol, diethylene glycol and butanone, and more preferably N-methylpyrrolidone.

[0016] In the grafting process, the volume-to-mass ratio of the solvent to the graphene is a conventional condition in the art, preferably 2 mg / mL to 8 mg / mL, for example 4 mg / mL.

[0017] In the grafting process, the grafting reaction temperature is a conventional condition in the art, preferably 50-120°C, more preferably 60-80°C, for example 70°C.

[0018] In the grafting process, the reaction time of the grafting is related to the reaction scale, preferably 5-50 hours, for example 12 hours.

[0019] Preferably, the grafting is performed under anaerobic conditions.

[0020] Preferably, the grafting is performed in an inert gas environment, and the inert gas is preferably nitrogen or argon.

[0021] The grafting process includes the following steps: after the graphene is dispersed in the solvent, 2,2,6,6-tetramethyl-4-piperidin methacrylate and an initiator are added, followed by deoxygenation, heating, and quenching.

[0022] In the grafting process, the dispersion is a conventional operation in the art, such as ultrasonic dispersion.

[0023] In the grafting process, the deoxygenation is a conventional operation in the art, and preferably deoxygenation is performed by freeze-drying.

[0024] In the grafting process, the heating temperature is a conventional condition in the art, preferably 50-120°C, more preferably 60-80°C, for example 70°C.

[0025] The grafting reaction is completed and includes the following post-processing steps: filtration and washing.

[0026] In the grafting process, the filtration is a conventional operation in the art, and preferably uses an organic phase filter membrane with a pore size of 0.22 μm for vacuum filtration.

[0027] In the grafting process, the washing solvent is a conventional solvent in the art, preferably a ketone solvent, such as acetone.

[0028] In the oxidation process, the disodium ethylenediaminetetraacetate, hydrogen peroxide, and sodium tungstate are added in two separate steps. Preferably, the mass ratio of the first to the second addition of disodium ethylenediaminetetraacetate is (2-4):1, for example, 2.8:1. The mass ratio of the first to the second addition of hydrogen peroxide is (2-4):1, for example, 3:1. The mass ratio of the first to the second addition of sodium tungstate is (1-3):1, for example, 2:1.

[0029] In the oxidation process, the mass ratio of the intermediate product to disodium ethylenediaminetetraacetate is preferably (1-5):1, more preferably (2-3):1, for example 2.4:1.

[0030] In the oxidation process, the mass ratio of the intermediate product to sodium tungstate dihydrate is preferably (1-5):1, more preferably (2-4):1, for example 3.2:1.

[0031] In the oxidation process, the mass ratio of the intermediate product to the 30% hydrogen peroxide solution is preferably 1:(10-50), more preferably 1:(30-40), for example 1:37.

[0032] In the oxidation process, the solvent is a conventional solvent in the art, preferably one or more of N-methylpyrrolidone, methanol, diethylene glycol and butanone, and more preferably methanol.

[0033] In the oxidation process, the hydrogen peroxide is a conventional raw material in the art, preferably a hydrogen peroxide solution with a mass percentage concentration of 30%. Preferably, the intermediate product, disodium ethylenediaminetetraacetate, and sodium tungstate are mixed before the hydrogen peroxide is added. More preferably, the hydrogen peroxide is added slowly.

[0034] In the oxidation process, the sodium tungstate is added in a form conventional in the art, such as sodium tungstate dihydrate.

[0035] In the oxidation process, the reaction time is a conventional time in the art, preferably 12-60 hours, for example 48 hours.

[0036] In the oxidation process, the reaction temperature is a conventional condition in the art, preferably 10-50°C, for example, room temperature (20-30°C).

[0037] The grafting process also includes water, preferably deionized water.

[0038] In the grafting process, the amount of water used is conventional. Preferably, the mass ratio of the water to the total mass of the disodium ethylenediaminetetraacetate and sodium tungstate dihydrate is 1:(15-30), for example, 1:22.

[0039] The oxidation process includes the following steps: dispersing the intermediate product in the solvent, adding the disodium ethylenediaminetetraacetate, the sodium tungstate, and the water, slowly adding the hydrogen peroxide, reacting for 12-48 hours, then adding the disodium ethylenediaminetetraacetate, the sodium tungstate, and the water again, slowly adding the hydrogen peroxide, and reacting for another 12-48 hours.

[0040] After the oxidation reaction is completed, the following post-processing steps are also included: filtration, washing, and drying.

[0041] In the oxidation process, the filtration is a conventional operation in the art, and preferably, it is a vacuum filtration using an organic phase filter membrane with a pore size of 0.22 μm.

[0042] In the grafting process, the solvent used for washing is a conventional solvent in the art, preferably water, such as deionized water.

[0043] In the grafting process, the drying is a conventional operation in the art, and freeze drying is preferred.

[0044] This invention provides a method for preparing a graphene surface-grafted free radical polymer composite material (GO-g-PTMA or rGO-g-PTMA), which includes the following steps:

[0045] (1) Grafting: In a solvent, graphene with a water content of 80-97% is polymerized with 2,2,6,6-tetramethyl-4-piperidin methacrylate (TMPM) in the presence of an initiator to prepare an intermediate product;

[0046] (2) Oxidation: The intermediate product, disodium ethylenediaminetetraacetate, sodium tungstate and hydrogen peroxide are oxidized in a solvent;

[0047] Preferably, the grafting and oxidation are as described above.

[0048] The present invention also provides a composite material (GO-g-PTMA or rGO-g-PTMA) of graphene surface grafted with free radical polymers prepared by the preparation method described above.

[0049] The present invention also provides a battery positive electrode slurry, the raw materials of which include graphene surface grafted free radical polymer composite material ((GO-g-PTMA or rGO-g-PTMA)), polyvinylidene fluoride (PVDF), N-methylpyrrolidone and conductive agent as described above.

[0050] The mass ratio of the composite material to polyvinylidene fluoride is a conventional ratio used in the art, preferably 1:(5-20), for example 1:10.

[0051] The mass-to-volume ratio of the composite material and N-methylpyrrolidone is a conventional ratio used in the art, preferably 10-50 mg / mL, for example 32 mg / mL.

[0052] The mass ratio of the composite material to the conductive agent is a conventional ratio used in the art, preferably (5-10):1, for example 8:1.

[0053] The conductive agent is a conventional conductive agent, preferably Super P, acetylene black or Ketjen black.

[0054] The positive electrode slurry of the battery can be used in zinc-ion batteries.

[0055] The present invention also provides a method for preparing a battery positive electrode slurry, which includes the following steps: stirring the components of the battery positive electrode slurry as described above until homogeneous.

[0056] Preferably, the method for preparing the positive electrode slurry of the battery includes the following steps:

[0057] Simply add the composite material as described above, the NMP solution of the polyvinylidene fluoride (PVDF), and the conductive agent to NMP and stir.

[0058] Preferably, the composite material is a graphene surface-grafted free radical polymer prepared by the aforementioned preparation method.

[0059] Preferably, in the intended use, the composite material is prepared as the aforementioned positive electrode slurry.

[0060] More preferably, in the aforementioned use, the positive electrode slurry is prepared as the aforementioned positive electrode sheet.

[0061] The present invention also provides a battery positive electrode sheet, the raw materials of which include the aforementioned positive electrode slurry and current collector.

[0062] The current collector is a common current collector in the art. Preferably, the current collector is a metal foil or carbon cloth; the metal foil is preferably a titanium foil or a stainless steel foil.

[0063] The present invention also provides a method for preparing a positive electrode sheet for a battery, which includes the following steps: drying a current collector coated with the aforementioned positive electrode slurry and pressing it into a sheet.

[0064] The current collector is a common current collector in the art. Preferably, the current collector is a metal foil or carbon cloth; the metal foil is preferably a titanium foil or a stainless steel foil.

[0065] The present invention also provides the use of a composite material of graphene surface grafted with free radical polymer prepared by the preparation method described above as a battery cathode material.

[0066] Preferably, the battery is a zinc-ion secondary battery.

[0067] The present invention also provides a battery comprising a positive electrode and an electrolyte, wherein the positive electrode is...

[0068] Preferably, in the battery, the electrolyte comprises an electrolyte and a solvent.

[0069] Preferably, the positive electrode is as described above.

[0070] More preferably, the electrolyte is selected from one or more of Zn(ClO4)2, Zn(TFSI)2 and Zn(OTF)2; more preferably, the electrolyte is Zn(ClO4)2, Zn(TFSI)2 or Zn(OTF)2, and even more preferably Zn(ClO4)2 or Zn(TFSI)2.

[0071] The solvent is H2O or an organic solvent; the organic solvent is preferably one or more of TEGDME, DOL, DME, DMC, EC, and EMC; more preferably, the solvent is a mixture of H2O, TEGDME, DOL, DME, EC, or EC-EMC-DMC (EC-EMC-DMC means EC, EMC, and DMC are mixed in a certain proportion), and more preferably, the volume ratio of EC, EMC, and DMC is 1:1:1. The concentration of the electrolyte in the electrolyte is 2 mol / L.

[0072] The concentration of the electrolyte in the electrolyte solution is 1-4 mol / L, for example, 2 mol / L.

[0073] In the electrolyte, when the solvent is H2O, the electrolyte is Zn(TFSI)2.

[0074] In the electrolyte, when the solvent is an organic solvent, the electrolyte is Zn(ClO4)2.

[0075] The battery also includes a glass fiber membrane and a negative electrode. The negative electrode is preferably zinc foil.

[0076] Without violating common sense in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0077] The reagents and raw materials used in this invention are all commercially available.

[0078] The positive significance of this invention lies in:

[0079] This invention employs a graphene-grafted free radical polymer composite material with a specific grafting content of 45%-55% as the positive electrode material for zinc batteries. The positive electrode sheet prepared using this invention can be assembled into a battery in an air environment with the electrolyte, resulting in low manufacturing costs. The battery of this invention maintains excellent capacity even at high discharge potentials. Furthermore, the battery of this invention also maintains good cycle and rate performance at high discharge potentials, making it suitable for industrial applications. Attached Figure Description

[0080] Figure 1 These are thermogravimetric analysis (TGA) spectra of the raw material rGO, pure polymer PTMA, and the obtained polymer-graphene composite material rGO-g-PTMA used in Example 1 of this invention.

[0081] Figure 2 This is the electron paramagnetic resonance (EPR) spectrum of the polymer-graphene composite material rGO-g-PTMA obtained in Example 1 of this invention.

[0082] Figure 3 The image shows the Fourier Transform Infrared (FT-IR) spectra of the raw material rGO used in Example 1 of this invention and the resulting polymer-graphene composite material rGO-g-PTMA.

[0083] Figure 4 The cyclic voltammetry curves of the zinc-ion secondary battery obtained in the embodiments of the present invention, which uses rGO-g-PTMA as the positive electrode material and 1MZn(ClO4)2 / TEGDME as the electrolyte, are shown.

[0084] Figure 5a The charge-discharge curve (1C) of a zinc-ion secondary battery with rGO-g-PTMA as the positive electrode material and 1MZn(ClO4)2 / TEGDME as the electrolyte obtained in this invention example is shown.

[0085] Figure 5b The charge-discharge curve (20C) of a zinc-ion secondary battery with rGO-g-PTMA as the positive electrode material and 1MZn(ClO4)2 / TEGDME as the electrolyte obtained in this invention example is shown.

[0086] Figure 6a The image shows the cycle performance curve (1C) of a zinc-ion secondary battery using rGO-g-PTMA as the positive electrode material and 1MZn(ClO4)2 / TEGDME as the electrolyte, obtained in an example of this invention.

[0087] Figure 6b The figure shows the cycle performance curve (20C) of a zinc-ion secondary battery with rGO-g-PTMA as the positive electrode material and 1MZn(ClO4)2 / TEGDME as the electrolyte, obtained in an example of the present invention.

[0088] Figure 7 The data is a rate performance curve of a zinc-ion secondary battery obtained in this invention, using rGO-g-PTMA as the positive electrode material and 1MZn(ClO4)2 / TEGDME as the electrolyte.

[0089] Figure 8 The cyclic voltammetry curves of a zinc-ion secondary battery using rGO-g-PTMA as the positive electrode material and 1MZn(TFSI)2 / H2O as the electrolyte are obtained from examples of this invention.

[0090] Figure 9a The charge-discharge curve (1C) of a zinc-ion secondary battery with rGO-g-PTMA as the positive electrode material and 1MZn(TFSI)2 / H2O as the electrolyte obtained in this invention example is shown.

[0091] Figure 9b The charge-discharge curve (20C) of a zinc-ion secondary battery with rGO-g-PTMA as the positive electrode material and 1MZn(TFSI)2 / H2O as the electrolyte obtained in this invention example is shown.

[0092] Figure 10a The figure shows the cycle performance curve (1C) of a zinc-ion secondary battery with rGO-g-PTMA as the positive electrode material and 1MZn(TFSI)2 / H2O as the electrolyte, obtained in an example of the present invention.

[0093] Figure 10b The image shows the cycle performance curve (20C) of a zinc-ion secondary battery with rGO-g-PTMA as the positive electrode material and 1MZn(TFSI)2 / H2O as the electrolyte, obtained in an example of this invention.

[0094] Figure 11 The data is a rate performance curve of a zinc-ion secondary battery obtained in this invention, using rGO-g-PTMA as the positive electrode material and 1MZn(TFSI)2 / H2O as the electrolyte. Detailed Implementation

[0095] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0096] Example 1: Synthesis of poly(4-methacryloyloxy-2,2,6,6-tetramethylpiperidine nitroxide radical) grafted onto graphene surface (rGO-g-PTMA)

[0097] (1) Free radical polymerization: Reduced graphene oxide with a water content of 97% (where water content is the mass percentage of water in the mixture of reduced graphene oxide and water) was added to a Schlenk tube with a pre-stirred bar, containing 400 mg of original graphene oxide and 100 mL of N-methylpyrrolidone, and ultrasonically dispersed for 1 hour. 8 g (36 mmol) of 2,2,6,6-tetramethyl-4-piperidinium methacrylate (TMPM) and 87 mg (0.53 mmol) of azobisisobutyronitrile (AIBN) initiator were added under nitrogen atmosphere, where the amount of AIBN added was 1.5% of the monomer TMPM. After three freeze-drying deoxygenation cycles, the reaction was carried out in a 70°C oil bath for 12 hours, and the reaction was quenched by air purging. The reaction solution was filtered through an organic phase filter membrane with a pore size of 0.22 μm, and the solid fraction was washed three times with acetone to remove free polymer. The product rGO-g-PTMPM was dispersed and stored in 150 mL of methanol.

[0098] (2) Oxidation: The methanol dispersion of rGO-g-PTMPM (approximately 600 mg of rGO-g-PTMPM) obtained in step (1) was sonicated for 1 hour. 180 mg of disodium ethylenediaminetetraacetate, 125 mg of sodium tungstate dihydrate, and 15 mL of deionized water were added, followed by the slow addition of 15 mL of 30% hydrogen peroxide. After reacting at room temperature for 24 hours, 65 mg of disodium ethylenediaminetetraacetate, 62 mg of sodium tungstate dihydrate, and 5 mL of deionized water were added, followed by the slow addition of 5 mL of 30% hydrogen peroxide. After reacting at room temperature for another 24 hours, the reaction solution was filtered through a 0.22 μm organic phase filter membrane. The product was washed three times with deionized water and freeze-dried to obtain the final product rGO-g-PTMA (593 mg). Thermogravimetric analysis (TGA) showed that... Figure 1 The material lost 49.2% of its weight in the 200-450℃ range, and the calculated polymer grafting amount is approximately 50%. Paramagnetic resonance (EPR) results ( Figure 2 The results showed that the composite material rGO-g-PTMA and the pure polymer PTMA exhibited absorption signals at approximately 334 mT, indicating successful grafting of the polymer onto graphene. Infrared spectroscopy ( Figure 3 In the curve, compared with that of reduced graphene oxide (rGO), the grafted composite material showed an increase in the position at 1732 cm⁻¹. -1 The carbonyl absorption peak in the methacrylate skeleton and 1384 cm⁻¹ -1 The absorption peaks of nitrogen and oxygen free radicals at the point of origin demonstrate the successful grafting of the polymer onto the carbon material.

[0099] Example 2: Preparation method of positive electrode sheet for zinc-ion battery

[0100] (1) Dissolve 0.32g of polyvinylidene fluoride (PVDF) in 16mL of N-methylpyrrolidone for later use, with a concentration of 0.02g / mL;

[0101] (2) Add 80 mg rGO-g-PTMA, 500 μL PVDF NMP solution, 10 mg conductive agent Super P and 2 mL NMP solvent to a small reaction flask and stir thoroughly for 4 hours to obtain a black uniform slurry;

[0102] (3) Cut the current collector titanium foil into a rectangular sheet of 6cm×15cm, fix it on the glass substrate, apply the slurry described in (2) evenly with a spreader, place it in a vacuum drying oven at 70°C for 12 hours, and then use a tablet press to press the titanium foil coated with the positive electrode material into a circular electrode sheet with a diameter of 1.2cm.

[0103] The battery composed of the positive electrode prepared in Example 2 has a specific capacity of 256 mAh g at 1C rate in the Zn(ClO4)2 / TEGDME system. -1 After 250 cycles, the electrode capacity decreased by only 21.5%.

[0104] Example 3: Preparation method of zinc-ion battery electrolyte

[0105] Electrolyte 1: Dissolve 3.72 g (1 mol) of zinc perchlorate [Zn(ClO4)2] in 10 mL of tetraethylene glycol dimethyl ether (TEGDME) to prepare an organic phase electrolyte with a concentration of 1 mol / L;

[0106] Electrolyte 2: Dissolve 6.25 g (1 mol) of bis(trifluoromethanesulfonyl)imine zinc(II) [Zn(TFSI)2] in 10 mL of ultrapure water to prepare an aqueous electrolyte with a concentration of 1 mol / L.

[0107] The specific capacities (mAh g) of various electrolyte and electrolyte solvent combinations at 1C current density are shown in the table below. -1 ):

[0108]

[0109] "-" indicates that no test was performed.

[0110] The table shows that when the electrolyte solvent is water, Zn(TFSI)2 is the best electrolyte; while for organic phase electrolytes, TEGDME is the best solvent, and Zn(ClO4)2 is the preferred electrolyte. Comparing electrolytes of different concentrations reveals that the electrode performance is optimal when the electrolyte concentration is 2M.

[0111] Example 4: Zinc-ion battery assembly method

[0112] The zinc-ion battery provided by this invention can be assembled directly in air. Add one drop of zinc-ion electrolyte to the center of the positive electrode casing of the button cell, place the positive electrode plate face up, add three drops of electrolyte, cover with a glass fiber membrane (purchased from Whatman), add three drops of electrolyte, place the zinc foil negative electrode (1.54 cm in diameter), then place a circular nickel foam (1.2 cm in diameter), finally cover with the negative electrode casing of the button cell, press firmly with a battery press, clean the surface, and bag for later use.

[0113] Example 5: Zinc-ion Battery Test Method

[0114] The battery cycle and rate test results provided by this invention were obtained using a Neware CT4008 battery testing system with a cutoff voltage of 0.5-1.8V; the cyclic voltammetry (CV) curves and electrochemical impedance spectroscopy (EIS) results were obtained using a CHI 660E electrochemical workstation with a CV scan rate of 0.5 mV / s. -1 The cutoff voltage is 0.5-1.8V, and the EIS scan range is 100KHz-10mHz.

[0115] Cyclic voltammetry results ( Figure 4 , 8 The results show that the zinc-ion secondary battery provided by the present invention has two sets of redox peaks in both Zn(ClO4)2 / TEGDME electrolyte and Zn(TFSI)2 / H2O electrolyte, corresponding to two redox reaction processes. The redox potential of the material is the highest in Zn(ClO4)2 / TEGDME electrolyte, which is about 1.6 and 1.1 V respectively. Figure 5a , 5b Batteries 6a and 6b correspond to the charge-discharge curves and cycle performance of the Zn(ClO4)2 / TEGDME electrolyte. It can be seen that at a 1C current, the battery can achieve a capacity of 256 mAh g / kg. -1 Specific capacity, 384Wh kg -1 Energy density: 78.5% capacity remaining after 250 cycles; 178 mAh g / kg at 20C current. -1 Specific capacity (after activation): 267Wh kg -1 The energy density shows virtually no decay after 250 cycles. Figure 9a , 9b The charge-discharge curves and cycle performance of batteries 10a and 10b in Zn(TFSI)2 / H2O electrolyte are shown. It can be seen that at a 1C current, the battery can achieve a capacity of 222 mAh g / g. -1 Initial specific capacity, 333Wh kg -1 Energy density: 67% capacity remaining after 250 cycles; 182 mAh g / L at 20C current. -1The capacity (after activation) is 273Wh kg. -1 The energy density showed virtually no decay after 250 cycles. These results indicate that both electrolyte conditions are suitable for the battery provided by this invention, and excellent charge / discharge specific capacity and cycle performance can be obtained while maintaining a high potential, with particularly outstanding cycle performance under high-rate charge / discharge conditions. Figure 7 and 11 Rate performance of the battery was compared using gradient current variations in Zn(ClO4)2 / TEGDME and Zn(TFSI)2 / H2O electrolytes, respectively. The results show that both batteries exhibit excellent rate performance and capacity reversibility.

[0116] Example 6: The other components and preparation method of the positive electrode are the same as in Example 2, except that the conductive agent is replaced with acetylene black or Ketjen black. The performance of the prepared positive electrode in the Zn(ClO4)2 / TEGDME system is shown in the table below:

[0117] Acetylene black - 38.5％ Kochen Black 185 43.7％

[0118] "-" indicates that no test was performed.

[0119] As can be seen from Example 2 and the table above, when the conductive agent is Super P, the specific capacity of the battery at a 1C rate is 256 mAh g. -1 After 250 cycles, the electrode capacity decreased by only 21.5%, while the electrode specific capacity and cycle performance of the other two conductive agents were poor and low.

[0120] The above are merely preferred embodiments of the present invention. The use of electrolytic salt and electrolyte solvent can also be changed, and it can also be used in forms other than button batteries such as pouch batteries.

[0121] Comparative Example 1

[0122] The preparation method used in Example 1 was the same, except that the graphene was anhydrous reduced graphene oxide, and the resulting polymer grafting amount was approximately 20%. Performance testing in Zn(ClO4)2-TEGDME electrolyte showed a discharge specific capacity of 168 mAh g⁻¹. -1 Compared with the results of the aqueous rGO-g-PTMA experiment in Example 1, the specific capacity decreased, and the voltage plateau of the p-type reaction of the PTMA polymer was significantly shortened, while the voltage plateau of the n-type reaction disappeared. This indicates that a large part of the capacity comes from the pseudocapacitive reaction of graphene, while the contribution of PTMA to the capacity is reduced. Performance testing of anhydrous rGO-g-PTMA in Zn(TFSI)2-H2O electrolyte showed a discharge specific capacity of 173 mAh g. -1 The p-type reaction platform of PTMA polymer is significantly shortened, and the n-type reaction platform disappears.

Claims

1. The use of a graphene-grafted free radical polymer composite material as a positive electrode material for zinc-ion secondary batteries, characterized in that, The free radical polymer is poly(4-methacryloyloxy-2,2,6,6-tetramethylpiperidine nitroxide radical), and the grafting content of poly(4-methacryloyloxy-2,2,6,6-tetramethylpiperidine nitroxide radical) in the composite material is 50%-55%; the grafting content is defined as the mass percentage of the free radical polymer to the total mass of the graphene surface grafted free radical polymer composite material. The graphene surface-grafted free radical polymer composite material is prepared by the following method, which includes the following steps: (1) Grafting: Graphene with a water content of 80-97% is dispersed in a solvent and then 2,2,6,6-tetramethyl-4-piperidin methacrylate and an initiator are added. After deoxygenation, heating and quenching, an intermediate product is obtained; the water content is the mass percentage of water in the mixture of graphene and water. (2) Oxidation: Disperse the intermediate product in the solvent, add disodium ethylenediaminetetraacetate, sodium tungstate and water, slowly add hydrogen peroxide, and react for 12-48 hours. Then add disodium ethylenediaminetetraacetate, sodium tungstate and water again, and slowly add hydrogen peroxide. React for 12-48 hours. The mass ratio of the first addition to the second addition of disodium ethylenediaminetetraacetate is (2-4):

1. The mass ratio of the first addition to the second addition of sodium tungstate is (1-3):

1. The mass ratio of the first addition to the second addition of hydrogen peroxide is (2-4):

1. In the zinc-ion secondary battery, the electrolyte includes an electrolyte and a solvent; the electrolyte is selected from Zn(ClO4)2, and the solvent is tetraethylene glycol dimethyl ether; or, the electrolyte is selected from Zn(TFSI)2, and the solvent is H2O.

2. The use of the graphene surface-grafted free radical polymer composite material as described in claim 1 as a positive electrode material for zinc-ion secondary batteries, characterized in that, The grafting content of poly(4-methacryloyloxy-2,2,6,6-tetramethylpiperidine nitroxide radical) in the composite material is 50%; the grafting content is defined as the mass percentage of the free radical polymer to the total mass of the graphene surface grafted free radical polymer composite material.

3. The use of the graphene surface-grafted free radical polymer composite material as described in claim 1 as a positive electrode material for zinc-ion secondary batteries, characterized in that... The preparation method of the graphene surface grafted free radical polymer composite material satisfies one or more of the following conditions: (1) In the grafting, the graphene is reduced graphene oxide and / or graphene oxide; (2) In the grafting, the water content of the graphene is 97%; the water content is the mass percentage of water in the mixture of graphene and water; (3) In the grafting, the mass ratio of graphene to 2,2,6,6-tetramethyl-4-piperidin methacrylate is 1:(2-100). (4) In the grafting, the initiator is azobisisobutyronitrile and / or benzoyl peroxide; (5) In the grafting, the molar ratio of 2,2,6,6-tetramethyl-4-piperidin methacrylate to the initiator is (200-50):1; (6) In the grafting process, the solvent is one or more of N-methylpyrrolidone, methanol, diethylene glycol and butanone; (7) In the grafting, the volume-to-mass ratio of the solvent to the graphene is 2 mg / mL-8 mg / mL; (8) In the grafting, the reaction temperature of the grafting is 50-120℃; (9) In the grafting, the reaction time of the graft is 5-50 hours; (10) In the grafting, the grafting is carried out under anaerobic conditions; (11) In the grafting, the grafting is carried out in an inert gas environment; (12) In the oxidation process, the ratio of the mass of the intermediate product to the total mass of the disodium ethylenediaminetetraacetate is (1-5):1; (13) In the oxidation process, the mass ratio of the intermediate product to the total mass of sodium tungstate dihydrate is (1-5):1; (14) In the oxidation, the total mass of the intermediate product and the hydrogen peroxide solution with a mass percentage concentration of 30% is 1:(10-50). (15) In the oxidation process, the hydrogen peroxide is a hydrogen peroxide solution with a mass percentage concentration of 30%; (16) In the oxidation process, the sodium tungstate is sodium tungstate dihydrate; (17) In the oxidation, the reaction time is 12-60 hours; (18) In the oxidation, the reaction temperature is 10-50℃; The grafting described in (19) also includes water.

4. The use of the graphene surface-grafted free radical polymer composite material as described in claim 3 as a positive electrode material for zinc-ion secondary batteries, characterized in that... The preparation method of the graphene surface grafted free radical polymer composite material satisfies one or more of the following conditions: (1) In the grafting, the mass ratio of graphene to 2,2,6,6-tetramethyl-4-piperidin methacrylate is 1:20; (2) In the grafting, the molar ratio of 2,2,6,6-tetramethyl-4-piperidin methacrylate to the initiator is 68:1; (3) In the grafting, the solvent is N-methylpyrrolidone; (4) In the grafting, the volume-to-mass ratio of the solvent to the graphene is 4 mg / mL; (5) In the grafting, the reaction temperature of the grafting is 60-80℃; (6) In the grafting, the reaction time of the graft is 12 hours; (7) The inert gas is nitrogen or argon; (8) In the oxidation process, the ratio of the mass of the intermediate product to the total mass of the disodium ethylenediaminetetraacetate is (2-3):1; (9) In the oxidation process, the mass ratio of the intermediate product to the total mass of sodium tungstate dihydrate is (2-4):1; (10) In the oxidation process, the total mass of the intermediate product and the hydrogen peroxide solution with a mass percentage concentration of 30% is 1:(30-40). (11) In the oxidation process, the intermediate product, disodium ethylenediaminetetraacetate and sodium tungstate are mixed and then the hydrogen peroxide is added; (12) In the oxidation, the reaction time is 48 hours; (13) In the oxidation, the reaction temperature is room temperature; (14) In the grafting, the water is deionized water.

5. The use of the graphene surface-grafted free radical polymer composite material as described in claim 4 as a positive electrode material for zinc-ion secondary batteries, characterized in that... The preparation method of the graphene surface grafted free radical polymer composite material satisfies one or more of the following conditions: (1) In the grafting, the reaction temperature of the grafting is 70°C; (2) In the oxidation process, the mass ratio of the intermediate product to the total mass of the disodium ethylenediaminetetraacetate is 2.4:1; (3) In the oxidation process, the mass ratio of the intermediate product to the total mass of sodium tungstate dihydrate is 3.2:1; (4) In the oxidation process, the total mass ratio of the intermediate product to the hydrogen peroxide solution with a mass percentage concentration of 30% is 1:

37.

6. The use of the graphene surface-grafted free radical polymer composite material as described in claim 3 as a positive electrode material for zinc-ion secondary batteries, characterized in that, The preparation method of the graphene surface grafted free radical polymer composite material satisfies one or more of the following conditions: (1) In the grafting, the dispersion is ultrasonic dispersion; (2) In the grafting, the deoxygenation is carried out by freeze-drying; (3) In the grafting process, the heating temperature is 50-120℃; (4) After the grafting reaction is completed, the following post-processing steps are also included: filtration and washing; (5) In the grafting, the mass ratio of the water to the total mass of the disodium ethylenediaminetetraacetate and sodium tungstate dihydrate is 1:(15-30). After the oxidation reaction described in (6) is completed, the following post-processing steps are also included: filtration, washing and drying.

7. The use of the graphene-grafted free radical polymer composite material as described in claim 6 as a positive electrode material for zinc-ion secondary batteries, characterized in that... The preparation method of the graphene surface grafted free radical polymer composite material satisfies one or more of the following conditions: (1) In the grafting process, the heating temperature is 60~80℃; (2) In the grafting, the mass ratio of the water to the total mass of the disodium ethylenediaminetetraacetate and sodium tungstate dihydrate is 1:

22.

8. The use of the graphene surface-grafted free radical polymer composite material as described in claim 7 as a positive electrode material for zinc-ion secondary batteries, characterized in that, In the grafting process, the heating temperature is 70°C.

9. A method for preparing a graphene surface-grafted free radical polymer composite material, characterized in that, It includes the following steps: (1) Grafting: Graphene with a water content of 80-97% is dispersed in a solvent and then 2,2,6,6-tetramethyl-4-piperidin methacrylate and an initiator are added. After deoxygenation, heating and quenching, an intermediate product is obtained; the water content is the mass percentage of water in the mixture of graphene and water. (2) Oxidation: Disperse the intermediate product in a solvent, add disodium ethylenediaminetetraacetate, sodium tungstate and water, slowly add hydrogen peroxide, and react for 12-48 hours. Then add disodium ethylenediaminetetraacetate, sodium tungstate and water again, and slowly add hydrogen peroxide. React for 12-48 hours. The mass ratio of the first addition to the second addition of disodium ethylenediaminetetraacetate is (2-4):

1. The mass ratio of the first addition to the second addition of sodium tungstate is (1-3):

1. The mass ratio of the first addition to the second addition of hydrogen peroxide is (2-4):

1. In the graphene surface grafted free radical polymer composite material, the free radical polymer is poly(4-methacryloyloxy-2,2,6,6-tetramethylpiperidine nitroxide free radical), and the grafting content of poly(4-methacryloyloxy-2,2,6,6-tetramethylpiperidine nitroxide free radical) in the composite material is 50%-55%; the grafting content is defined as the mass percentage of the free radical polymer to the total mass of the graphene surface grafted free radical polymer composite material.

10. The method for preparing the graphene surface-grafted free radical polymer composite material as described in claim 9, characterized in that, The preparation method of the graphene surface grafted free radical polymer composite material satisfies one or more of the following conditions: (1) In the grafting, the graphene is reduced graphene oxide and / or graphene oxide; (2) In the grafting, the water content of the graphene is 97%; the water content is the mass percentage of water in the mixture of graphene and water; (3) In the grafting, the mass ratio of graphene to 2,2,6,6-tetramethyl-4-piperidin methacrylate is 1:(2-100). (4) In the grafting, the initiator is azobisisobutyronitrile and / or benzoyl peroxide; (5) In the grafting, the molar ratio of 2,2,6,6-tetramethyl-4-piperidin methacrylate to the initiator is (200-50):1; (6) In the grafting process, the solvent is one or more of N-methylpyrrolidone, methanol, diethylene glycol and butanone; (7) In the grafting, the volume-to-mass ratio of the solvent to the graphene is 2 mg / mL-8 mg / mL; (8) In the grafting, the reaction temperature of the grafting is 50-120℃; (9) In the grafting, the reaction time of the graft is 5-50 hours; (10) In the grafting, the grafting is carried out under anaerobic conditions; (11) In the grafting, the grafting is carried out in an inert gas environment; (12) In the oxidation process, the ratio of the mass of the intermediate product to the total mass of the disodium ethylenediaminetetraacetate is (1-5):1; (13) In the oxidation process, the mass ratio of the intermediate product to the total mass of sodium tungstate dihydrate is (1-5):1; (14) In the oxidation, the total mass of the intermediate product and the hydrogen peroxide solution with a mass percentage concentration of 30% is 1:(10-50). (15) In the oxidation process, the hydrogen peroxide is a hydrogen peroxide solution with a mass percentage concentration of 30%; (16) In the oxidation process, the sodium tungstate is sodium tungstate dihydrate; (17) In the oxidation, the reaction time is 12-60 hours; (18) In the oxidation, the reaction temperature is 10-50℃; The grafting described in (19) also includes water.

11. The method for preparing the graphene surface-grafted free radical polymer composite material as described in claim 10, characterized in that, The preparation method of the graphene surface grafted free radical polymer composite material satisfies one or more of the following conditions: (1) In the grafting, the mass ratio of graphene to 2,2,6,6-tetramethyl-4-piperidin methacrylate is 1:20; (2) In the grafting, the molar ratio of 2,2,6,6-tetramethyl-4-piperidin methacrylate to the initiator is 68:1; (3) In the grafting, the solvent is N-methylpyrrolidone; (4) In the grafting, the volume-to-mass ratio of the solvent to the graphene is 4 mg / mL; (5) In the grafting, the reaction temperature of the grafting is 60-80℃; (6) In the grafting, the reaction time of the graft is 12 hours; (7) The inert gas is nitrogen or argon; (8) In the oxidation process, the ratio of the mass of the intermediate product to the total mass of the disodium ethylenediaminetetraacetate is (2-3):1; (9) In the oxidation process, the mass ratio of the intermediate product to the total mass of sodium tungstate dihydrate is (2-4):1; (10) In the oxidation process, the total mass of the intermediate product and the hydrogen peroxide solution with a mass percentage concentration of 30% is 1:(30-40). (11) In the oxidation process, the intermediate product, disodium ethylenediaminetetraacetate and sodium tungstate are mixed and then the hydrogen peroxide is added; (12) In the oxidation, the reaction time is 48 hours; (13) In the oxidation, the reaction temperature is room temperature; (14) In the grafting, the water is deionized water.

12. The method for preparing the graphene surface-grafted free radical polymer composite material as described in claim 11, characterized in that, The preparation method of the graphene surface grafted free radical polymer composite material satisfies one or more of the following conditions: (1) In the grafting, the reaction temperature of the grafting is 70°C; (2) In the oxidation process, the mass ratio of the intermediate product to the total mass of the disodium ethylenediaminetetraacetate is 2.4:1; (3) In the oxidation process, the mass ratio of the intermediate product to the total mass of sodium tungstate dihydrate is 3.2:1; (4) In the oxidation process, the total mass ratio of the intermediate product to the hydrogen peroxide solution with a mass percentage concentration of 30% is 1:

37.

13. The method for preparing the graphene surface-grafted free radical polymer composite material as described in claim 9, characterized in that, The preparation method of the graphene surface grafted free radical polymer composite material satisfies one or more of the following conditions: (1) In the grafting, the dispersion is ultrasonic dispersion; (2) In the grafting, the deoxygenation is carried out by freeze-drying; (3) In the grafting process, the heating temperature is 50-120℃; (4) After the grafting reaction is completed, the following post-processing steps are also included: filtration and washing; (5) In the grafting, the mass ratio of the water to the total mass of the disodium ethylenediaminetetraacetate and sodium tungstate dihydrate is 1:(15-30). After the oxidation reaction described in (6) is completed, the following post-processing steps are also included: filtration, washing and drying.

14. The method for preparing the graphene surface-grafted free radical polymer composite material as described in claim 13, characterized in that, The preparation method of the graphene surface grafted free radical polymer composite material satisfies one or more of the following conditions: (1) In the grafting process, the heating temperature is 60~80℃; (2) In the grafting, the mass ratio of the water to the total mass of the disodium ethylenediaminetetraacetate and sodium tungstate dihydrate is 1:

22.

15. The method for preparing the graphene surface-grafted free radical polymer composite material as described in claim 14, characterized in that, In the grafting process, the heating temperature is 70°C.

16. A graphene surface-grafted free radical polymer composite material prepared by the preparation method according to any one of claims 9-15.

17. A battery positive electrode slurry, characterized in that, Its raw materials include the graphene surface grafted free radical polymer composite material as described in claim 16, polyvinylidene fluoride, N-methylpyrrolidone, and a conductive agent.

18. The battery positive electrode slurry as described in claim 17, characterized in that, The battery positive electrode slurry meets one or more of the following conditions: (1) The mass ratio of the composite material to polyvinylidene fluoride is 1:(5-20); (2) The mass-to-volume ratio of the composite material to N-methylpyrrolidone is 10-50 mg / mL; (3) The mass ratio of the composite material to the conductive agent is (5-10):1; (4) The conductive agent is Super P, acetylene black or Ketjen black; The positive electrode slurry of the battery described in (5) can be used in zinc-ion batteries.

19. The battery positive electrode slurry as described in claim 18, characterized in that, The battery positive electrode slurry meets one or more of the following conditions: (1) The mass ratio of the composite material to polyvinylidene fluoride is 1:10; (2) The mass-to-volume ratio of the composite material to N-methylpyrrolidone is 32 mg / mL; (3) The mass ratio of the composite material to the conductive agent is 8:

1.

20. A positive electrode sheet for a battery, characterized in that, Its raw materials include: battery positive electrode slurry and current collector as described in any one of claims 17-19.

21. The positive electrode of the battery as described in claim 20, characterized in that, The current collector is a metal foil or carbon cloth.

22. The positive electrode of the battery as described in claim 21, characterized in that, The metal foil is titanium foil or stainless steel foil.

23. A battery, characterized in that, It includes a positive electrode and an electrolyte; the positive electrode includes a composite material as described in claim 16; The electrolyte comprises an electrolyte and a solvent; the positive electrode is as described in any one of claims 20-22.

24. The battery as claimed in claim 23, characterized in that, The battery satisfies one of the following conditions (1) and / or (2): (1) The concentration of the electrolyte in the electrolyte solution is 1-4 mol / L; (2) The battery also includes a glass fiber membrane and a negative electrode.

25. The battery as claimed in claim 24, characterized in that, The battery satisfies (1) and / or (2) of the following conditions: (1) The concentration of the electrolyte in the electrolyte solution is 2 mol / L; (2) The negative electrode is zinc foil.

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