Novel negative electrode material preparation method and solid-state lithium ion battery thereof
Technical Field
The invention belongs to the technical field of development of polymer lithium ion battery cathode materials, and particularly relates to a preparation method of a novel cathode material and a solid-state lithium ion battery thereof.
Background
Under the conditions of rapid population growth and rapid economic development, problems of environmental pollution, energy shortage and the like generate great threats to the living space of human beings and the sustainable occurrence of society, and the demand for sustainable energy is continuously increased. Therefore, the development of efficient renewable energy storage in conversion devices has attracted a great deal of attention. Lithium ion batteries having the advantages of high energy density, long cycle life, high operating voltage, and rapid charge and discharge rate have been widely used in consumer electronics such as mobile phones and notebook computers. As an important component of the lithium ion battery, the performance of the battery is restricted by the negative electrode material, so that the development of the high-performance negative electrode material plays an important role in promoting the construction of a lithium ion battery system with high energy, high voltage, long service life and high charge-discharge rate.
Orthorhombic niobium pentoxide (T-Nb)2O5) The most promising anode materials are considered because of their unique advantages. First, T-Nb2O5Can provide theoretical specific capacity of 200mAh/g, which is larger than Li4Ti5O12175 mAh/g. Secondly, due to the almost empty sites between the octahedral (001) crystal planes in their particular crystal structure, the two-dimensional channel itself will allow lithium ions to diffuse rapidly through the crystal planes of a-b. Therefore, the reaction kinetics can be greatly improved in the process of the lithium ion deintercalation reaction on the surface or near the surface of the electrode. Furthermore, T-Nb2O5The potential of the lithium is higher (1.2-2.0V), so that dendritic lithium is prevented from being generated, and the lithium battery has high safety. However, T-Nb2O5Practical applications in lithium ion batteries are limited by their inherent poor conductivity leading to reduced cycle life and rate capability. Therefore, T-Nb with stable structure and excellent performance is designed and prepared2O5Nanomaterials still present significant challenges.
Meanwhile, a liquid electrolyte using carbonate as a solvent as an ion conducting medium is an electrolyte mainly used in a commercial lithium ion battery at present. However, due to the defects of electrolyte leakage, easy volatilization of organic solvents, easy combustion and the like, the liquid lithium ion battery has serious potential safety hazard, and finally the liquid electrolyte cannot completely meet the requirement of large-scale energy storage on safety. Therefore, the Gel Polymer Electrolytes (GPEs) which have good processability of the polymers and high ionic conductivity of the liquid electrolytes can be considered, the problems of liquid leakage, flammability, explosion and the like of the liquid lithium ion batteries can be effectively solved, the appearance design of the batteries is flexible, and the Gel Polymer Electrolytes (GPEs) which can be continuously produced are attracted by wide attention and research.
Gel Polymer Electrolytes (GPEs) are polymer electrolyte membranes prepared from polymer monomers, plasticizers, and lithium salts by a certain method. Therefore, the composite material has the advantages of light weight, good viscoelasticity, controllable shape and the like. Because the solid polymer electrolyte hardly contains organic solvent, the solid polymer electrolyte rarely leaks, and the safety performance is greatly improved; the gel is in a solid state and a liquid state as a special substance form, and the duality ensures that the gel has solid cohesiveness and the property of liquid diffusion and transmission substances, so that the gel polymer electrolyte has good processability of a polymer and high ionic conductivity of an organic liquid electrolyte, and becomes a focus and a hot spot of current research.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a novel anode material of orthorhombic niobium pentoxide (T-Nb)2O5) A nanowire preparation method and a solid-state lithium ion battery thereof.
The technical scheme of the invention is as follows:
a preparation method of a novel anode material comprises the following steps:
(1) uniformly dispersing the surfactant in ultrapure water by using a high-speed disperser to obtain a suspension;
(2) dissolving the niobium salt in the suspension completely under the condition of mechanical stirring, then separating, washing and drying after hydrothermal reaction to obtain Nb2O5Precursor powder;
(3) calcining the precursor powder at high temperature in air atmosphere to obtain orthorhombic niobium pentoxide (T-Nb)2O5) A negative electrode material of a nanowire lithium ion battery.
The surfactant in the step (1) is one or more of Dodecyl Trimethyl Ammonium Bromide (DTAB), hexadecyl trimethyl ammonium bromide (CTAB), Octadecyl Trimethyl Ammonium Bromide (OTAB), 3-alkoxy-2-Hydroxypropyl Trimethyl Ammonium Bromide (HTAB), and hexadecyl trimethyl ammonium salicylate (C16TASal) quaternary ammonium salt cationic surfactants.
In the step (1), the concentration of the surfactant is 0.05-0.50 mol/L, and preferably, the concentration of the surfactant is 0.1-0.35 mol/L.
In the step (1), the rotating speed of the high-speed disperser is 8000-20,000 rpm, the dispersing time is 0.5-2.0 h, and preferably, the rotating speed of the high-speed disperser is 10,000-12,000 rpm, and the dispersing time is 1-1.5 h.
In the step (2), the niobium salt is ammonium niobium oxalate, niobium oxalate or anhydrous niobium chloride (NbCl)5) The solubility of the niobium salt is 0.05-0.85 mol/L, and the concentration of ammonium niobium oxalate and niobium salt is preferably 0.1-0.45 mol/L.
In the step (2), the temperature of the hydrothermal reaction is 140-200 ℃, the reaction time is 12-28 h, preferably, the temperature of the hydrothermal reaction is 160-180 ℃, and the reaction time is 18-24 h.
In the step (2), the separation is centrifugation or suction filtration, the washing degree is carried out until basic impurity ions exist in the precipitate, a freeze drying technology is adopted, the vacuum degree is not lower than-0.1 MPa, and the drying time is 12-24 hours.
In the step (3), the high-temperature calcination temperature is 500-800%oAnd C, calcining for 2-5 h. Preferably, the calcination temperature is 550-700 deg.CoAnd C, calcining for 2.5-4 h.
A solid lithium ion battery using the above prepared orthorhombic niobium pentoxide (T-Nb)2O5) The nanowire is used as the negative electrode of the lithium ion battery, the composite PVDF-HFP gel polymer electrolyte is used as the electrolyte, and lithium metal, lithium alloy and lithium cobaltate (LiCoO) are used2) Lithium manganate (LiMn)2O4) Lithium nickel manganese oxide (LiNi)xMn2-xO4), lithium iron phosphate (or iron phosphate) (LiFePO4/ FePO4) And ternary materials of nickel cobalt lithium manganate (NCM) and vanadium pentoxide (V)2O5) Molybdenum trioxide (MoO)3) One or more of the lithium ion batteries are used as the anode to prepare the solid lithium ion battery.
The composite PVDF-HFP gel polymer electrolyte is prepared by a solution casting technology, and the mass ratio of the composite PVDF-HFP gel polymer electrolyte to the PVDF-HFP gel polymer electrolyte is as follows: PC: EC: LiTFSI = (15-25): (15-30): (15-30): (15-20) the thickness of the electrolyte film is 50-150 μm.
The invention has the beneficial effects that: the orthorhombic niobium pentoxide (T-Nb) prepared by the invention2O5) The negative electrode material of the nanowire lithium ion battery has a porous and cross-linked nanowire structure, has the characteristics of stable structure, high conductivity and the like, and can form a good contact interface with a gel polymer electrolyte to prepare the solid polymer lithium ion battery together with the composite PVDF-HFP gel polymer electrolyte and the like, so that the battery has the advantages of high energy density, long cycle life, excellent rate capability, good safety and the like. Meanwhile, the preparation method has the advantages of simplicity, rapidness and low cost.
Drawings
FIG. 1 shows T-Nb prepared by the present invention2O5Scanning Electron Microscope (SEM) images of nanowires.
FIG. 2 shows T-Nb prepared by the present invention2O5Nanowire anode material and conventional T-Nb2O5First charge-discharge comparison curve of the negative electrode material.
FIG. 3 shows T-Nb prepared by the present invention2O5Nanowire anode material and conventional T-Nb2O5And (3) a comparison curve of the cycle performance of the solid lithium ion battery prepared from the negative electrode material and the composite PVDF-HFP gel electrolyte.
FIG. 4 shows T-Nb prepared by the present invention2O5Nanowire anode material and conventional T-Nb2O5And the multiplying power performance comparison curve of the solid lithium ion battery prepared from the cathode material and the composite PVDF-HFP gel electrolyte.
Detailed Description
The details of the present invention will be further described with reference to the accompanying drawings and specific embodiments.
A preparation method of a novel anode material comprises the following steps:
(1) uniformly dispersing the surfactant in ultrapure water by using a high-speed disperser to obtain a suspension;
(2) adding niobium saltCompletely dissolving the Nb in the suspension under the condition of mechanical stirring, then carrying out hydrothermal reaction, and then separating, washing and drying to obtain Nb2O5Precursor powder;
(3) calcining the precursor powder at high temperature in air atmosphere to obtain orthorhombic niobium pentoxide (T-Nb)2O5) A negative electrode material of a nanowire lithium ion battery.
The surfactant in the step (1) is one or more of Dodecyl Trimethyl Ammonium Bromide (DTAB), hexadecyl trimethyl ammonium bromide (CTAB), Octadecyl Trimethyl Ammonium Bromide (OTAB), 3-alkoxy-2-Hydroxypropyl Trimethyl Ammonium Bromide (HTAB), and hexadecyl trimethyl ammonium salicylate (C16TASal) quaternary ammonium salt cationic surfactant.
In the step (1), the concentration of the surfactant is 0.05-0.50 mol/L, preferably, the concentration of the surfactant is 0.1-0.35 mol/L.
In the step (1), the rotating speed of the high-speed disperser is 8000-20,000 rpm, the dispersing time is 0.5-2.0 h, preferably, the rotating speed of the high-speed disperser is 10,000-12,000 rpm, and the dispersing time is 1-1.5 h.
In the step (2), the niobium salt is ammonium niobium oxalate, niobium oxalate or anhydrous niobium chloride (NbCl)5) The solubility of the niobium salt is 0.05-0.85 mol/L, and the concentration of ammonium niobium oxalate and niobium salt is preferably 0.1-0.45 mol/L.
In the step (2), the temperature of the hydrothermal reaction is 140-200 ℃, the reaction time is 12-28 h, preferably, the temperature of the hydrothermal reaction is 160-180 ℃, and the reaction time is 18-24 h.
In the step (2), the separation is centrifugation or suction filtration, the washing degree is carried out until basic impurity ions exist in the precipitate, a freeze drying technology is adopted, the vacuum degree is not lower than-0.1 MPa, and the drying time is 12-24 hours.
In the step (3), the high-temperature calcination temperature is 500-800%oAnd C, calcining for 2-5 h. Preferably, the calcination temperature is 550-700%oAnd C, calcining for 2.5-4 hours.
A solid lithium ion battery using the above prepared orthorhombic niobium pentoxide (T-Nb)2O5) The nanowire is used as the negative electrode of the lithium ion battery, the composite PVDF-HFP gel polymer electrolyte is used as the electrolyte, and lithium metal, lithium alloy and lithium cobaltate (LiCoO) are used2) Lithium manganate (LiMn)2O4) Lithium nickel manganese oxide (LiNi)xMn2-xO4), lithium iron phosphate (or iron phosphate) (LiFePO4/ FePO4) And ternary materials of nickel cobalt lithium manganate (NCM) and vanadium pentoxide (V)2O5) Molybdenum trioxide (MoO)3) One or more of the lithium ion batteries are used as the anode to prepare the solid lithium ion battery.
The composite PVDF-HFP gel polymer electrolyte is prepared by a solution casting technology, and the mass ratio of the composite PVDF-HFP gel polymer electrolyte to the PVDF-HFP gel polymer electrolyte is as follows: PC: EC: LiTFSI = (15-25): (15-30): (15-30): (15-20) the thickness of the electrolyte film is 50-150 μm.
The following are specific examples:
example 1 is orthorhombic niobium pentoxide (T-Nb)2O5) Preparation of nanowires, example 2 is preparation of composite PVDF-HFP gel polymer electrolyte, and example 3 is preparation of solid lithium ion battery and cycle and rate performance test.
Example 1
Adding about 6.06g of ammonium niobium oxalate into 100mL of ultrapure water under the condition of mechanical stirring, transferring the ammonium niobium oxalate into a 200mL polytetrafluoroethylene reaction kettle after the ammonium niobium oxalate is completely dissolved, sealing, then placing the high-pressure reaction kettle into a 170 ℃ blast drying oven, reacting for 24h, naturally cooling to room temperature after the reaction is finished, washing with ultrapure water and ethanol for a plurality of times, freeze-drying, drying to obtain white powder, finally placing the white powder into a muffle furnace, reacting for 3 h at 600 ℃, and obtaining T-Nb similarly2O5A nanowire.
Example 2
With mechanical stirring, 3.0 g of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP, molecular weight 5.3X 10)5) SolutionIn 15.0 g of NMP, it was completely dissolved and a clear transparent gum solution was obtained. Then adding 1.5 g of ethylene glycol diethyl ether or branched polyethyleneimine to completely dissolve the ethylene glycol diethyl ether or branched polyethyleneimine, finally adding 0.6 g of LiTFSI, completely dissolving to obtain uniform slurry containing SiO2 and lithium salt, uniformly casting or blade-coating the obtained slurry on a clean glass plate or a polytetrafluoroethylene plate, then carrying out vacuum drying for 6-8 h at the temperature of 40-55 ℃ for the first time, and continuing drying for 10-14 h at the temperature of 60-80 ℃ for the second time; finally, peeling the composite PVDF-HFP gel polymer electrolyte from a glass plate or a PTFE plate to obtain the composite PVDF-HFP gel polymer electrolyte with the thickness of about 35-80 mu m and the pore diameter of about 0.5-1.5 mu m.
Example 3
The T-Nb prepared in example 12O5The nanowire negative electrode material, the SuperP and the PVDF are respectively mixed according to the mass ratio of 80: 10: 10, adding a proper amount of N-methyl-2-pyrrolidone (NMP), mechanically stirring for 30min at a high speed to obtain electrode slurry, uniformly coating the electrode slurry on a copper foil by a doctor blade method, drying for 10 h at 80 ℃ in vacuum, and cutting a sheet with the diameter of D =14 mm by a slicer to obtain a working electrode. Accurately weighing the electrode plate mass and numbering, and placing the obtained electrode plate in an argon-protected glove box for later use. Then using T-Nb2O5The nanowire is a working electrode, the metal lithium is used as a counter electrode and a reference electrode, the composite PVDF-HFP gel polymer electrolyte membrane is used as a diaphragm and is placed between a positive electrode and a negative electrode, the button cell is prepared by sealing, finally, the LAND CT2001A is used for testing the cycle performance and the rate performance, the testing voltage range is 1.1-3.0V, and the testing results are shown in figures 2, 3 and 4. Test results show that after the current density of 0.1C is cycled for 100 times, the discharge specific capacity still keeps 166.5mAh/g, and the current density has good cycle performance; at the same time, T-Nb2O5The nanowires still have excellent rate performance: under the multiplying power of 10C, the discharge specific capacity is still about 65 mAh/g.