A high-rate lithium battery for drone based on graphene and preparation method thereof

Abstract

The present invention discloses a high-rate lithium battery for drones based on graphene and a preparation method thereof. The invention comprises the following steps: S1: preparing a solid electrolyte solution for standby use; S2: coating the positive electrode active slurry on the positive electrode current collector, drying, and obtaining a positive electrode plate; coating the negative electrode active slurry on the negative electrode current collector, drying, and obtaining a negative electrode plate; S3: coating the solid electrolyte solution with a surface density of 12-15 mg / cm 2 Coating on the surface of the positive electrode sheet, drying, hot pressing, cold pressing, to obtain a composite positive electrode sheet; S4: stacking the composite positive electrode sheet, separator, and negative electrode sheet to obtain a battery cell; placing the battery cell in a shell, hot pressing, cold pressing, to obtain a high-rate lithium battery. Beneficial effect: By adding graphene-based composite fillers and polyethylene glycol methyl ether acrylate composites to the solid electrolyte; and combining with positive electrode active materials, the performance of high-rate lithium batteries is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a high-rate lithium battery for a drone based on graphene and a preparation method thereof. Background Art

[0002] With the booming development of the drone industry, the demand for drone power is also gradually increasing. At the current stage of research, there is a tendency to change fuel drones into electric drones to reduce the flight noise and failure rate of drones, so that drones can start and stop at any time, glide silently, and cruise quietly when performing tasks, greatly improving the mission performance of drones.

[0003] UAV batteries have high requirements for battery power. When the throttle is quickly increased from the hovering state to the maximum speed, the battery power will increase rapidly, and the power will increase several times in a short period of time; therefore, it is necessary to solve the problems of high capacity, high rate, and cycle stability of UAV batteries. In existing high-rate lithium batteries, polymer electrolytes are generally used instead of liquid electrolytes, and gelled solid electrolytes reduce the risk of fire and explosion. However, the ionic conductivity of the solid electrolyte is generally lower than that of the liquid electrolyte, which affects the rate performance of the lithium battery; at the same time, there are pores in the solid electrolyte, which can easily cause lithium dendrites to penetrate the electrolyte, causing the battery to short-circuit, which affects safety. On the other hand, the interface contact problem between the positive electrode plate and the solid electrolyte, as well as the lithium storage performance and lithium ion diffusion performance of the positive electrode material, have an impact on the impedance of the battery. It is necessary to reduce the pseudo-face and polarization impedance and improve the performance of the battery.

[0004] In summary, it is of great significance to solve the above problems and prepare a high-rate lithium battery for drones based on graphene. Summary of the invention

[0005] The object of the present invention is to provide a graphene-based high-rate lithium battery for drones and a preparation method thereof, so as to solve the problems raised in the above-mentioned background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A method for preparing a high-rate lithium battery for a drone based on graphene, comprising the following steps:

[0008] S1: Material preparation;

[0009] S2: adding lithium salt and graphene-based composite filler to the solvent and stirring evenly; adding polyethylene oxide and polyethylene glycol methyl ether acrylate composite in sequence and mixing evenly to obtain a solid electrolyte solution with a solid content of 40 to 50 wt %, which is set aside;

[0010] S3: coating the positive electrode active slurry on the positive electrode current collector and drying to obtain a positive electrode sheet; coating the negative electrode active slurry on the negative electrode current collector and drying to obtain a negative electrode sheet;

[0011] S4: coating the solid electrolyte solution on the surface of the positive electrode sheet, drying, hot pressing, and cold pressing to obtain a composite positive electrode sheet;

[0012] S5: Stack the composite positive electrode sheet, separator, and negative electrode sheet to obtain a battery cell; place the battery cell into a casing, perform hot pressing and cold pressing, and obtain a high-rate lithium battery.

[0013] More optimally, the raw materials of the solid electrolyte solution include the following components: 100 parts of polyethylene oxide, 8 to 10 parts of polyethylene glycol methyl ether acrylate composite, 45 to 50 parts of lithium salt, and 18 to 22 parts of graphene-based composite filler, by weight.

[0014] More optimally, the graphene-based composite filler is obtained by compounding graphene oxide, cyclodextrin and phytic acid in a mass ratio of (1.2-1.5):2:1.

[0015] More optimally, the preparation method of the graphene-based composite filler is: add cyclodextrin, phytic acid, and p-toluenesulfonic acid to deionized water in sequence, add o-methylhydroquinone, set the temperature to 105-108°C for reaction for 3-4 hours, rotary evaporate, wash, and dry to obtain complex A; transfer it to a graphene oxide dispersion, disperse it evenly, set the temperature to 70-75°C for stirring for 6-8 hours, wash and dry to obtain a graphene-based composite filler.

[0016] More optimally, the preparation method of the polyethylene glycol methyl ether acrylate complex is: add potassium persulfate to sodium 4-styrenesulfonate and polyethylene glycol methyl ether acrylate dimethyl sulfoxide in a mass ratio of 1:2, set the temperature to 70-75°C for reaction for 24 hours, add n-hexane for precipitation, filter, wash and dry to obtain the polyethylene glycol methyl ether acrylate complex.

[0017] More optimally, the raw materials of the positive electrode active slurry include the following components: by weight, 92 to 96 parts of positive electrode active material, 1 to 3 parts of conductive agent, 3 to 5 parts of binder, and 70 to 100 parts of solvent; the positive electrode active material is porous lithium cobalt oxide; the binder is sodium 4-styrene sulfonate modified polyvinylidene fluoride.

[0018] More optimally, the preparation method of the porous lithium cobalt oxide is: dissolving cobalt nitrate hexahydrate in deionized water to obtain solution A, dissolving trimesic acid in DMF-ethanol to obtain solution B; slowly adding solution A to solution B and mixing evenly to obtain a mixed solution, adding graphene oxide and dispersing it evenly; transferring it to a hydrothermal kettle, reacting it at 200°C for 24 hours to obtain Co-MOF; grinding and mixing Co-MOF and lithium hydroxide monohydrate, transferring it to a high-temperature furnace, and heat treating it at a temperature of 700-800°C for 2-3 hours in an air atmosphere to obtain porous lithium cobalt oxide.

[0019] More optimally, the amount of graphene oxide added is 2-3 wt% of the mixed solution; the mass ratio of Co-MOF to lithium hydroxide monohydrate is 2.5:(1-1.5).

[0020] More optimally, the preparation method of the binder is: weigh polyvinylidene fluoride and sodium 4-styrene sulfonate in a mass ratio of 1: (0.8-1); 60 The pre-irradiation is carried out with Co-γ rays at room temperature with an irradiation amount of 50 to 100 kGy to obtain pre-irradiated powder, which is stored at -20°C for later use; the pre-irradiated powder is placed in a sodium 4-styrene sulfonate solution, degassed with nitrogen, the temperature is set at 60 to 65°C for reaction for 6 to 8 hours, and the binder is washed and dried to obtain the binder.

[0021] In addition, the raw materials of the negative electrode active slurry include the following components: by weight, 96 to 98 parts of negative electrode active material, 1 to 2 parts of conductive agent, 1 to 2 parts of binder, and 80 to 100 parts of solvent;

[0022] The conductive agent includes but is not limited to one or more of conductive graphite, conductive carbon black, Ketjen black, and carbon nanotubes;

[0023] The negative electrode material includes but is not limited to one or more of graphite, hard carbon, soft carbon, silicon carbon, and mesophase carbon microspheres.

[0024] The lithium salt includes but is not limited to one or more of lithium hexafluorophosphate, lithium difluorooxalatoborate, and lithium bis(fluorosulfonyl)imide.

[0025] More optimally, a high-rate lithium battery is prepared by a method for preparing a high-rate lithium battery for a graphene-based drone.

[0026] In this technical solution, by adding graphene-based composite fillers and polyethylene glycol methyl ether acrylate composites to polymer solid electrolytes, the mechanical properties of the electrolyte are improved, the interface impedance is reduced, and the performance of high-rate lithium batteries is improved; at the same time, the risk of fire is reduced and safety is increased. By preparing porous lithium cobalt oxide, the positive electrode lithium storage capacity is increased, and the lithium ion migration distance is reduced, thereby increasing the rate performance.

[0027] In the (1) scheme, polyethylene oxide is used as the main polymer of the solid electrolyte, and graphene-based composite fillers and polyethylene glycol methyl ether acrylate composites are introduced to improve safety, mechanical properties, and electrical properties.

[0028] Among them, the graphene-based composite filler is prepared by modifying graphene oxide with phytic acid-modified cyclodextrin. First, in order to solve the problem of low conductivity and poor mechanical properties of solid electrolytes; cyclodextrin is introduced as a filler, which can form a continuous hydrogen bond network with the ether bonds in polyethylene oxide; due to the hydrogen bond effect, the mechanical properties of the solid electrolyte are enhanced; at the same time, due to the effect of the ether bond, the Lewis alkalinity is increased, thereby increasing the affinity with lithium ions and the dissociation ability of lithium salts. Secondly, in order to further improve the affinity with lithium ions and improve the conductivity, phytic acid is used to modify cyclodextrin; and the modification of phytic acid not only improves the ionic conductivity, but also effectively increases the high temperature stability, can effectively buffer the volume change during the charge and discharge process at high current density, and significantly increases the cycle stability and rate performance. However, excessively increasing the ionic conductivity will introduce the problem of uneven deposition of lithium ions, reducing the cycle stability of the battery. Therefore, in this scheme, phytic acid-modified cyclodextrin is grafted onto the surface of graphene oxide to obtain a graphene-based composite filler, which further improves the mechanical properties while improving high-temperature stability and flame retardancy. Graphene oxide is allowed to form a uniform, elastic, and continuous lithium ion adsorption area in the solid electrolyte, effectively preventing the uneven deposition of lithium ions, synergistically and effectively suppressing the puncture problem of lithium dendrites, and improving battery stability and rate performance.

[0029] In scheme (2), in order to reduce the interfacial impedance, a polyethylene glycol methyl ether acrylate complex was introduced into the solid electrolyte to assist the higher molecular weight polyethylene oxide to form a dense solid electrolyte, reduce the porosity, and increase the cycle stability, rate performance and safety.

[0030] Among them, the polyethylene glycol methyl ether acrylate complex is obtained by the free radical reaction of polyethylene glycol methyl ether acrylate and sodium 4-styrene sulfonate. It has good compatibility with polyethylene oxide, and the introduction of sodium 4-styrene sulfonate increases high temperature stability and electrical properties; on the other hand, its introduction increases affinity with the positive electrode, reduces interface pores, and effectively reduces interface impedance.

[0031] In the (3) scheme, Co-MOF doped with oxidizable graphene is used as a precursor, and is ground and calcined with lithium hydroxide to obtain porous lithium cobalt oxide; the porosity effectively increases the lithium storage capacity, while reducing the lithium ion migration performance, increasing the interface contact between the electrode and the electrolyte, effectively buffering the volume expansion, and increasing the rate performance; and the doping of graphene oxide effectively increases the specific surface agent of Co-MOF and increases the porosity of lithium cobalt oxide. At the same time, polyvinylidene fluoride is modified with sodium 4-styrene sulfonate to effectively reduce the interface pores between the positive electrode and the electrolyte and reduce the interface impedance; in addition, sodium 4-styrene sulfonate is a surfactant, and after modification, it effectively increases the dispersibility of porous lithium cobalt oxide, so that no additional surfactant needs to be introduced after the positive active slurry is prepared. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] In the following embodiments, graphene oxide is prepared by passing graphene (purchased from McLean, 2000 mesh) through Hummers, and the preparation method is as follows: setting the temperature to 0°C, adding 5g of graphene to 115mL of concentrated sulfuric acid, adding 15g of potassium permanganate and 2.5g of sodium nitrate, stirring the reaction for 2 hours, and slowly adding 230mL of deionized water; adjusting the temperature to 95°C, adding 300mL of deionized water dropwise, cooling to 30°C, adding hydrogen peroxide, the solution turns bright yellow, and washing and drying to obtain graphene oxide.

[0034] Carbon nanotubes were purchased from McLean: thickness 1-2 nm; cyclodextrin was purchased from McLean: β-cyclodextrin, 98%; polyethylene glycol methyl ether acrylate was purchased from McLean: average molecular weight 1000; polyvinylidene fluoride was purchased from McLean: average molecular weight 534,000; polyethylene oxide was purchased from McLean: average molecular weight 600,000.

[0035] Embodiment 1:

[0036] S1: Material preparation:

[0037] (1) 2 g of cyclodextrin, 1 g of phytic acid, and 0.1 g of p-toluenesulfonic acid were added to 10 g of deionized water in sequence, and 0.5 g of o-methylhydroquinone was added. The temperature was set to 108 ° C for reaction for 3.5 hours, and the mixture was rotary evaporated, washed, and dried to obtain a composite A; the composite A was transferred to a 10 wt% graphene oxide dispersion (containing 1.5 g of graphene oxide), stirred and dispersed evenly for 30 minutes, and the temperature was set to 75 ° C for stirring for 7 hours, washed, and dried to obtain a graphene-based composite filler.

[0038] (2) Dispersing 1 g of sodium 4-styrene sulfonate and 2 g of polyethylene glycol methyl ether acrylate in 5 g of dimethyl sulfoxide (DMSO) solution, adding 0.1 g of potassium persulfate, setting the temperature to 75° C. for reaction for 24 hours, adding n-hexane for precipitation, filtering, washing, and drying to obtain a polyethylene glycol methyl ether acrylate complex.

[0039] (3) Dissolve 0.8 g of cobalt nitrate hexahydrate in 10 g of deionized water to obtain solution A, and dissolve 0.32 g of trimesic acid in 20 g of DMF-ethanol (mass ratio is 1:1) to obtain solution B; slowly add solution A to solution B and mix well to obtain a mixed solution, add 0.800 g of graphene oxide and disperse it evenly; transfer it to a hydrothermal autoclave and react it at 200°C for 24 hours to obtain Co-MOF; grind and mix 2.5 g of Co-MOF and 1.5 g of lithium hydroxide monohydrate, transfer it to a high-temperature furnace, set the temperature to 750°C in an air atmosphere, and heat treat it for 2 hours to obtain porous lithium cobalt oxide.

[0040] (4) 1g of polyvinylidene fluoride was placed in air using 60 The pre-irradiation was carried out with Co-γ rays at room temperature with an irradiation dose of 80 kGy to obtain a pre-irradiated powder, which was stored at -20°C for later use. The pre-irradiated powder was placed in a 6 wt% sodium 4-styrenesulfonate solution (the content of sodium 4-styrenesulfonate was 1 g, and the solvent was 1:4:1 deionized water, dimethyl sulfoxide, and 0.6 mol / L sulfuric acid), degassed with nitrogen, and the reaction temperature was set at 60°C for 8 hours, followed by washing and drying to obtain a binder.

[0041] S2: Add 48 parts of lithium salt and 20 parts of graphene-based composite filler to acetonitrile by weight and stir evenly; add 100 parts of polyethylene oxide and 10 parts of polyethylene glycol methyl ether acrylate composite in sequence and mix evenly to obtain a solid electrolyte solution with a solid content of 45wt%, which is set aside;

[0042] S3: According to the weight fraction, 95 parts of porous lithium cobalt oxide, 2 parts of carbon nanotubes, 3 parts of binder, and 82 parts of N-methylpyrrolidone were mixed evenly to obtain a positive electrode active slurry; the positive electrode active slurry was coated on aluminum foil with a surface density of 55 mg / cm 2 , drying to obtain a positive electrode sheet;

[0043] According to the weight fraction, 97 parts of graphite, 1.5 parts of carbon nanotubes, 1.5 parts of binder, and 100 parts of N-methylpyrrolidone were mixed evenly to obtain a negative electrode active slurry; the negative electrode active slurry was coated on a copper foil with a surface density of 20 mg / cm 2 , drying to obtain a positive electrode sheet;

[0044] S4: The solid electrolyte solution is prepared at a surface density of 12 mg / cm 2 Coat on the surface of the positive electrode, set the temperature to 80℃ and dry for 12 hours, set the temperature to 30℃ and dry for 24 hours; set the temperature to 80℃ and the pressure to 1000kg / cm 2 Hot press for 2 minutes; set the temperature to 30°C and the pressure to 500kg / cm 2 Cold pressing for 2 minutes to obtain a composite positive electrode sheet;

[0045] S5: Stack the composite positive electrode sheet, PVDF separator, and negative electrode sheet to obtain a battery cell; put the battery cell into the shell, set the temperature to 75°C and the pressure to 1000kg / cm 2 Hot press for 5 minutes; set the temperature to 30°C and the pressure to 1000kg / cm 2 Cold pressing for 3 minutes yields a high-rate lithium battery.

[0046] Embodiment 2:

[0047] S1: Material preparation:

[0048] (1) 2 g of cyclodextrin, 1 g of phytic acid, and 0.1 g of p-toluenesulfonic acid were added to 10 g of deionized water in sequence, and 0.5 g of o-methylhydroquinone was added. The temperature was set to 105 ° C for reaction for 4 hours, and the mixture was rotary evaporated, washed, and dried to obtain a composite A; the composite A was transferred to a graphene oxide dispersion with a concentration of 10 wt% (containing 1.2 g of graphene oxide), stirred and dispersed evenly for 30 minutes, and the temperature was set to 70-75 ° C for stirring for 6-8 hours, washed, and dried to obtain a graphene-based composite filler.

[0049] (2) Dispersing 1 g of sodium 4-styrene sulfonate and 2 g of polyethylene glycol methyl ether acrylate in 5 g of dimethyl sulfoxide (DMSO) solution, adding 0.1 g of potassium persulfate, setting the temperature to 70° C. for reaction for 24 hours, adding n-hexane for precipitation, filtering, washing, and drying to obtain a polyethylene glycol methyl ether acrylate complex.

[0050] (3) Dissolve 0.8 g of cobalt nitrate hexahydrate in 10 g of deionized water to obtain solution A, and dissolve 0.32 g of trimesic acid in 20 g of DMF-ethanol (mass ratio is 1:1) to obtain solution B; slowly add solution A to solution B and mix well to obtain a mixed solution, add 0.608 g of graphene oxide and disperse it evenly; transfer it to a hydrothermal autoclave and react it at 200°C for 24 hours to obtain Co-MOF; grind and mix 2.5 g of Co-MOF and 1 g of lithium hydroxide monohydrate, transfer it to a high-temperature furnace, set the temperature to 700°C in an air atmosphere, and heat treat it for 3 hours to obtain porous lithium cobalt oxide.

[0051] (4) 1g of polyvinylidene fluoride was placed in air using 60 The pre-irradiation was carried out with Co-γ rays at room temperature with an irradiation dose of 50 kGy to obtain a pre-irradiated powder, which was stored at -20°C for later use. The pre-irradiated powder was placed in a 6 wt% sodium 4-styrenesulfonate solution (the content of sodium 4-styrenesulfonate was 0.8 g, and the solvent was 1:4:1 deionized water, dimethyl sulfoxide, and 0.6 mol / L sulfuric acid), degassed with nitrogen, and the reaction temperature was set at 60°C for 6 hours, followed by washing and drying to obtain a binder.

[0052] S2: Add 45 parts of lithium salt and 22 parts of graphene-based composite filler to the solvent by weight and stir evenly; add 100 parts of polyethylene oxide and 8 parts of polyethylene glycol methyl ether acrylate composite in sequence and mix evenly to obtain a solid electrolyte solution with a solid content of 40wt%, which is set aside;

[0053] S3: According to the weight fraction, 92 parts of porous lithium cobalt oxide, 3 parts of carbon nanotubes, 5 parts of binder, and 70 parts of N-methylpyrrolidone were mixed evenly to obtain a positive electrode active slurry; the positive electrode active slurry was coated on aluminum foil with a surface density of 55 mg / cm 2 , drying to obtain a positive electrode sheet;

[0054] According to the weight fraction, 97 parts of graphite, 1.5 parts of carbon nanotubes, 1.5 parts of binder, and 100 parts of N-methylpyrrolidone were mixed evenly to obtain a negative electrode active slurry; the negative electrode active slurry was coated on a copper foil with a surface density of 20 mg / cm 2 , drying to obtain a positive electrode sheet;

[0055] S4: The solid electrolyte solution is prepared at a surface density of 12 mg / cm 2 Coat on the surface of the positive electrode, set the temperature to 80℃ and dry for 12 hours, set the temperature to 30℃ and dry for 24 hours; set the temperature to 80℃ and the pressure to 1000kg / cm 2 Hot press for 2 minutes; set the temperature to 30°C and the pressure to 500kg / cm 2 Cold pressing for 2 minutes to obtain a composite positive electrode sheet;

[0056] S5: Stack the composite positive electrode sheet, PVDF separator, and negative electrode sheet to obtain a battery cell; put the battery cell into the shell, set the temperature to 75°C and the pressure to 1000kg / cm 2 Hot press for 5 minutes; set the temperature to 30°C and the pressure to 1000kg / cm 2 Cold pressing for 3 minutes yields a high-rate lithium battery.

[0057] Embodiment 3:

[0058] S1: Material preparation:

[0059] (1) 2 g of cyclodextrin, 1 g of phytic acid, and 0.1 g of p-toluenesulfonic acid were added to 10 g of deionized water in sequence, and 0.5 g of o-methylhydroquinone was added. The temperature was set to 108 ° C for reaction for 4 hours, and the mixture was rotary evaporated, washed, and dried to obtain a composite A; the composite A was transferred to a graphene oxide dispersion with a concentration of 10 wt% (containing 1.5 g of graphene oxide), stirred and dispersed evenly for 30 minutes, the temperature was set to 70-75 ° C for stirring for 6-8 hours, and washed and dried to obtain a graphene-based composite filler.

[0060] (2) Dispersing 1 g of sodium 4-styrene sulfonate and 2 g of polyethylene glycol methyl ether acrylate in 5 g of dimethyl sulfoxide (DMSO) solution, adding 0.1 g of potassium persulfate, setting the temperature to 75° C. for reaction for 24 hours, adding n-hexane for precipitation, filtering, washing, and drying to obtain a polyethylene glycol methyl ether acrylate complex.

[0061] (3) Dissolve 0.8 g of cobalt nitrate hexahydrate in 10 g of deionized water to obtain solution A, and dissolve 0.32 g of trimesic acid in 20 g of DMF-ethanol (mass ratio is 1:1) to obtain solution B; slowly add solution A to solution B and mix well to obtain a mixed solution, add 0.912 g of graphene oxide and disperse it evenly; transfer it to a hydrothermal autoclave and react it at 200°C for 24 hours to obtain Co-MOF; grind and mix 2.5 g of Co-MOF and 1.5 g of lithium hydroxide monohydrate, transfer it to a high-temperature furnace, set the temperature to 800°C in an air atmosphere, and heat treat it for 2 hours to obtain porous lithium cobalt oxide.

[0062] (4) 1g of polyvinylidene fluoride was placed in air using 60 The pre-irradiation was carried out with Co-γ rays at room temperature with an irradiation dose of 100 kGy to obtain a pre-irradiated powder, which was stored at -20°C for later use. The pre-irradiated powder was placed in an 8 wt% sodium 4-styrenesulfonate solution (the content of sodium 4-styrenesulfonate was 1 g, and the solvent was 1:4:1 deionized water, dimethyl sulfoxide, and 0.6 mol / L sulfuric acid), degassed with nitrogen, and the reaction temperature was set at 65°C for 8 hours, followed by washing and drying to obtain a binder.

[0063] S2: Add 45-50 parts of lithium salt and 18-22 parts of graphene-based composite filler to the solvent by weight and stir evenly; add 100 parts of polyethylene oxide and 8-10 parts of polyethylene glycol methyl ether acrylate composite in sequence and mix evenly to obtain a solid electrolyte solution with a solid content of 50wt%, which is set aside;

[0064] S3: According to the weight fraction, 96 parts of porous lithium cobalt oxide, 1 part of carbon nanotubes, 3 parts of binder, and 100 parts of N-methylpyrrolidone were mixed evenly to obtain a positive electrode active slurry; the positive electrode active slurry was coated on aluminum foil with a surface density of 55 mg / cm 2 , drying to obtain a positive electrode sheet;

[0065] According to the weight fraction, 97 parts of graphite, 1.5 parts of carbon nanotubes, 1.5 parts of binder, and 100 parts of N-methylpyrrolidone were mixed evenly to obtain a negative electrode active slurry; the negative electrode active slurry was coated on a copper foil with a surface density of 20 mg / cm 2 , drying to obtain a positive electrode sheet;

[0066] S4: The solid electrolyte solution is prepared at a surface density of 12 mg / cm 2 Coat on the surface of the positive electrode, set the temperature to 80℃ and dry for 12 hours, set the temperature to 30℃ and dry for 24 hours; set the temperature to 80℃ and the pressure to 1000kg / cm 2 Hot press for 2 minutes; set the temperature to 30°C and the pressure to 500kg / cm 2 Cold pressing for 2 minutes to obtain a composite positive electrode sheet;

[0067] S5: Stack the composite positive electrode sheet, PVDF separator, and negative electrode sheet to obtain a battery cell; put the battery cell into the shell, set the temperature to 75°C and the pressure to 1000kg / cm 2 Hot press for 5 minutes; set the temperature to 30°C and the pressure to 1000kg / cm 2 Cold pressing for 3 minutes yields a high-rate lithium battery.

[0068] Comparative Example 1: The graphene-based composite filler is replaced with graphene oxide, and the rest is the same as Example 1;

[0069] Comparative Example 2: The graphene-based composite filler is replaced with cyclodextrin, and the rest is the same as Example 1;

[0070] Comparative Example 3: The polyethylene glycol methyl ether acrylate composite was not introduced, and the rest was the same as Example 1;

[0071] Comparative Example 4: The porous lithium cobalt oxide was replaced with purchased lithium cobalt oxide from Merck, and the rest was the same as Example 1;

[0072] Comparative Example 5: During the preparation of porous lithium cobalt oxide, graphene oxide is not introduced, and the rest is the same as in Example 1;

[0073] Comparative Example 6: The binder is replaced with polyvinylidene fluoride, and the rest is the same as Example 1.

[0074] Experiment: The high-rate lithium batteries prepared in the examples and comparative examples were subjected to charge and discharge tests at room temperature, at 1C and 10C; and the batteries were cycled 1000 times at 10C to detect the discharge capacity. The obtained performance is shown in the following table:

[0075]

[0076]

[0077] Conclusion: From the data of Examples 1 to 3, it can be seen that the scheme prepares porous lithium cobalt oxide as the positive electrode active material; introduces a composite filler in the modified adhesive and polymer solid electrolyte, and a composite organic matter, which synergistically and effectively improves the cycle stability and electrical performance of the high-rate lithium battery. By comparing the data in Comparative Examples 1 to 6, it can be seen that in Comparative Example 1, due to the single introduction of graphene oxide in the solid electrolyte, the buffering performance of the volume change during charging is reduced, and the cycle stability at high rate is reduced; similarly, in Comparative Example 2, the single introduction of cyclodextrin reduces the uniformity of lithium ion migration and the high temperature stability, resulting in a decrease in performance; in Comparative Example 3, the low molecular weight polyethylene glycol methyl ether acrylate complex is not introduced, which increases the interface resistance between the solid electrolyte and the electrode, and reduces the porosity of the solid electrolyte, resulting in a decrease in performance; in Comparative Example 4, due to the use of directly purchased lithium cobalt oxide, the porosity is reduced, resulting in a decrease in performance; and in Comparative Example 5, graphite oxide is not introduced, which reduces the specific surface area and reduces the performance; in Comparative Example 6, due to the unmodified binder, the affinity with lithium ions is reduced, and the interface resistance is increased, resulting in a decrease in performance.

[0078] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a high-rate lithium battery for a drone based on graphene. Features: The following steps are involved: S1: Material preparation; S2: adding lithium salt and graphene-based composite filler to the solvent and stirring evenly; adding polyethylene oxide and polyethylene glycol methyl ether acrylate composite in sequence and mixing evenly to obtain a solid electrolyte solution with a solid content of 40 to 50 wt %, which is set aside; S3: coating the positive electrode active slurry on the positive electrode current collector and drying to obtain a positive electrode sheet; coating the negative electrode active slurry on the negative electrode current collector and drying to obtain a negative electrode sheet; S4: coating the solid electrolyte solution on the surface of the positive electrode sheet, drying, hot pressing, and cold pressing to obtain a composite positive electrode sheet; S5: stacking the composite positive electrode sheet, the separator, and the negative electrode sheet to obtain a battery cell; placing the battery cell into a housing, hot pressing, and cold pressing to obtain a high-rate lithium battery; The preparation method of the graphene-based composite filler is as follows: cyclodextrin, phytic acid, and p-toluenesulfonic acid are added to deionized water in sequence, and o-methyl hydroquinone is added, and the temperature is set at 105-108° C. to react for 3-4 hours, and the composite A is rotary evaporated, washed, and dried to obtain the composite A; the composite A is transferred to a graphene oxide dispersion liquid, dispersed evenly, and the temperature is set at 70-75° C. to stir for 6-8 hours, and washed and dried to obtain the graphene-based composite filler; The preparation method of the polyethylene glycol methyl ether acrylate complex is as follows: sodium 4-styrene sulfonate and polyethylene glycol methyl ether acrylate in a mass ratio of 1:2 are dispersed in dimethyl sulfoxide, potassium persulfate is added, the temperature is set at 70-75°C for reaction for 24 hours, n-hexane is added for precipitation, and the mixture is filtered, washed and dried to obtain the polyethylene glycol methyl ether acrylate complex.

2. A method for preparing a high-rate lithium battery for a graphene-based drone according to claim 1, Features: The raw materials of the solid electrolyte solution include the following components: 100 parts of polyethylene oxide, 8 to 10 parts of polyethylene glycol methyl ether acrylate compound, 45 to 50 parts of lithium salt, and 18 to 22 parts of graphene-based composite filler are weighed by weight.

3. The method for preparing a high-rate lithium battery for a graphene-based drone according to claim 1, Features: The graphene-based composite filler is obtained by compounding graphene oxide, cyclodextrin and phytic acid in a mass ratio of (1.2-1.5):2:

1.

4. The method for preparing a high-rate lithium battery for a graphene-based drone according to claim 1, Features: The raw materials of the positive electrode active slurry include the following components: by weight, 92 to 96 parts of positive electrode active material, 1 to 3 parts of conductive agent, 3 to 5 parts of binder, and 70 to 100 parts of solvent; the positive electrode active material is porous lithium cobalt oxide; the binder is sodium 4-styrene sulfonate modified polyvinylidene fluoride.

5. A method for preparing a high-rate lithium battery for a graphene-based drone according to claim 4, Features: The preparation method of the porous lithium cobalt oxide is as follows: dissolving cobalt nitrate hexahydrate in deionized water to obtain solution A, dissolving trimesic acid in DMF-ethanol to obtain solution B; slowly adding solution A to solution B and mixing evenly to obtain a mixed solution, adding graphene oxide and dispersing it evenly; transferring it to a hydrothermal kettle, reacting it at 200° C. for 24 hours to obtain Co-MOF; grinding and mixing Co-MOF and lithium hydroxide monohydrate, transferring it to a high-temperature furnace, and heat treating it at a temperature of 700-800° C. for 2-3 hours in an air atmosphere to obtain porous lithium cobalt oxide.

6. A method for preparing a high-rate lithium battery for a graphene-based drone according to claim 4, Features: The added amount of graphene oxide accounts for 2-3wt% of the mixed solution; the mass ratio of Co-MOF to lithium hydroxide monohydrate is 2.5:(1-1.5).

7. A method for preparing a high-rate lithium battery for a graphene-based drone according to claim 4, Features: The preparation method of the binder is as follows: weigh polyvinylidene fluoride and sodium 4-styrene sulfonate in a mass ratio of 1: (0.8-1); 60 The pre-irradiation is carried out with Co-γ rays at room temperature with an irradiation amount of 50 to 100 kGy to obtain pre-irradiated powder, which is stored at -20°C for later use; the pre-irradiated powder is placed in a sodium 4-styrene sulfonate solution, degassed with nitrogen, the temperature is set at 60 to 65°C for reaction for 6 to 8 hours, and the binder is washed and dried to obtain the binder.

8. A high-rate lithium battery prepared according to the method for preparing a high-rate lithium battery for a graphene-based drone according to any one of claims 1 to 7.

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