WO2023087212A1 - Preparation method for mesoporous filler compounded gel polymer electrolyte - Google Patents

Abstract

Disclosed in the present invention are the preparation and application of a mesoporous filler compounded gel polymer electrolyte. In the present invention, silicon dioxide nanoparticles having special mesoporous structures are designed, and same are compounded with a gel polymer electrolyte to prepare a mesoporous filler compounded gel polymer electrolyte; in addition, a high mechanical strength and a good electrochemical stability are maintained. Compared with blank sample and solid silicon dioxide nanoparticle compounded electrolytes, the mesoporous filler compounded gel polymer electrolyte disclosed in the present invention has a higher liquid absorption amount and ionic conductivity, and also has a higher lithium ion mobility. Due to the good compatibility between a mesoporous filler and lithium metal, a stable SEI layer can be generated. In addition, a lithium metal battery assembled by the mesoporous filler compounded gel polymer electrolyte exhibits a good cycle performance.

Description

A preparation method of a mesoporous filler-composite gel polymer electrolyte technical field

The invention relates to the technical field of secondary batteries, in particular to a filler composite gel polymer electrolyte secondary battery.

Background technique

Lithium metal batteries have the highest theoretical specific capacity (3860mAh·g ^-1 ) and the lowest redox potential (-3.040Vvs. hydrogen electrode). Conventional liquid organic electrolytes not only have good ionic conductivity but also have good compatibility with electrodes, which play an important role in lithium metal batteries. However, using liquid organic electrolytes can easily lead to leakage and burning. In addition, due to the infiltration of Li dendrites, uncontrollable short circuits can seriously affect battery life and even lead to explosion. Solid polymer electrolytes can be used as a substitute for liquid electrolytes to address the safety issues of liquid electrolytes due to their good processability and flexibility. However, the low room temperature conductivity of solid polymer electrolytes limits the room temperature applications of lithium metal batteries. Gel polymer electrolytes, which combine the advantages of liquid electrolytes and solid polymers, are considered to be an exploration direction for practical applications of Li metal batteries and have received much attention. Their good interface with electrodes and strong organic solvent reserve can effectively suppress liquid leakage and thus enhance safety. More excitingly, the flexible gel polymer electrolyte can withstand the volume change and infiltration caused by Li dendrite growth. Therefore, gel polymer electrolytes are considered to be the best choice to improve the overall performance of lithium metal batteries.

The polymer matrix usually used to make gel polymer electrolyte mainly includes polyimide, PEO, PAN, PVDF-HFP and other polymers. Despite a large number of polymers to choose from, how to address the low ionic conductivity and weak mechanical properties of gel polymer electrolytes remains a great challenge for practical applications.

For this reason, a large number of methods have been developed to improve the overall performance of gel polymer electrolytes, such as introducing some inorganic fillers through physical blending to improve the mechanical strength of polymer electrolytes; or chemical blending to introduce another functional polymer to Improving some properties of gel polymer electrolytes. However, the poor conductivity of most inorganic fillers such as TiO2 affects the overall conductivity of the electrolyte. At the same time, due to the uneven particle size, it will agglomerate in the electrolyte, thereby creating stress concentration points, which will affect the mechanical properties of the polymer electrolyte. Although chemical blending can affect the electrical conductivity through the introduction of special functional groups, the process of modification and blending is often complicated and has certain safety issues.

Therefore, it is worthy of attention to develop a composite gel polymer electrolyte with excellent performance, safety and reliability, which has important economic value and social benefits for solving the increasingly serious energy problems.

Contents of the invention

The study found that the introduction of inorganic nanoparticles into the polymer matrix is a simple and effective strategy to solve the problem of low ionic conductivity and weak mechanical properties of gel polymer electrolytes, because it combines the advantages of inorganic and organic electrolytes and can significantly improve the Bulk properties of gel polymer electrolytes. A significant advantage of this approach is that the nanofillers have uniform distributed stress and excellent thermodynamic properties, which can enhance their mechanical properties and thermal stability. In addition, the stable Lewis acid-base effect between the polymer host and the surface chemical groups of ceramic nanoparticles can promote the dissociation of salts, thereby increasing the number of free Li ions. Therefore, the design of high specific surface area filler-filled gel polymer electrolytes is a reasonable direction. The uniform dispersion of fillers can not only improve the mechanical properties of gel polymer electrolytes, but also improve the electrochemical performance by reducing the crystallinity of the polymers. In addition, the high specific surface area can provide more opportunities for Lewis acid-base reactions and increase the number of lithium ion migrations. Finally, more filler-polymer interfaces can be generated due to abundant mesoporous channels. The more lithium ions there are, the more optimized the lithium ion migration channel is, and the better the performance of the battery will be.

In order to solve the technical problems of low electrical conductivity, poor mechanical strength and limited electrochemical performance improvement of existing polymer electrolytes for lithium batteries, the present invention provides a method for preparing a novel composite gel polymer electrolyte. The appropriate composite structure of the polymer electrolyte has excellent stability, good economic benefits, long service life, and excellent battery performance.

Technical scheme of the present invention:

A method for preparing a special structural filler for a lithium battery composite gel electrolyte, the special structural filler includes wormhole-shaped or walnut-shaped nano-inorganic particles, and flower-shaped nano-inorganic particles;

Among them, the preparation process of wormhole-like nano-inorganic particles is as follows:

First, choose a solvent as the reaction system, add one or several silane precursors to the system, add micelles as templates for precursor polymerization, and add an amine as a mineralizer to enhance the template environment , to prevent micelles from agglomerating, the mixed system is reacted in a heated environment; the prepared material is post-processed, and finally a wormhole-like nano-inorganic particle is obtained.

Further, the molar ratio of the silane precursor, micellar agent, mineralizer and solvent is 1:(0.02-0.06):(7-12):80

Furthermore, the precursor is one or more of the following substances: methyl orthosilicate, ethyl orthosilicate, isopropyl orthosilicate, tetrapropyl orthosilicate, methyl triethoxy silane, dimethyldiethoxysilane, tetrakis (2-methoxy-1-methylethyl) silicate;

Further, the solvent is one or more of the following substances: water, methanol, ethanol, propanol, butanol, pentanol, cyclohexane, cyclopentane;

Further, the micelles are one or more of the following substances: sodium lauryl sulfate, cetyltrimethylammonium bromide, cetyltrimethylammonium toluenesulfonate, Cetyl pyridinium bromide;

Furthermore, the amine mineralizer is one or more of the following substances: ammonia water, triethanolamine, ethylamine, propylamine, butylamine, diethylamine, diethylammonia, triethylamine Ammonium, urea, etc.;

Furthermore, the range of heating condition temperature and heating reaction time of the mixed system is: 30°C-120°C, 1-12h;

Furthermore, the post-treatment method of the prepared substance is at least one of the following methods: suction filtration, rotary evaporation, centrifugation, and vacuum drying.

Wherein, the preparation process of walnut-shaped nano-inorganic particles is as follows:

First, choose a solvent as the reaction system, add one or several silane precursors to the system, add micelles as templates for precursor polymerization, and add an amine as a mineralizer to adjust the pH value , to assist polymerization, and the mixed system reacts in a heated environment; the prepared material is post-processed to finally obtain a walnut-shaped nano-inorganic particle.

Further, the molar ratio of the silane precursor, micelle, mineralizer and solvent is 1:(0.01-0.04):(0.015-0.035):80; further, the precursor is the following substances One or more of: methyl orthosilicate, ethyl orthosilicate, isopropyl orthosilicate, tetrapropyl orthosilicate, methyltriethoxysilane, dimethyldiethoxysilane, Tetrakis(2-methoxy-1-methylethyl)silicate;

Further, the solvent is one or more of the following substances: water, methanol, ethanol, propanol, butanol, pentanol, cyclohexane, cyclopentane;

Further, the micelles are one or more of the following substances: sodium lauryl sulfate, cetyltrimethylammonium bromide, cetyltrimethylammonium toluenesulfonate, Cetyl pyridinium bromide;

Furthermore, the amine mineralizer is one or more of the following substances: ammonia water, triethanolamine, ethylamine, propylamine, butylamine, diethylamine, diethylammonia, triethylamine Ammonium, urea, etc.;

Furthermore, the range of heating condition temperature and heating reaction time of the mixed system is: 30°C-120°C, 1-12h;

Furthermore, the post-treatment method of the prepared substance is at least one of the following methods: suction filtration, rotary evaporation, centrifugation, and vacuum drying.

Wherein, the preparation process of flower-shaped nano-inorganic particles is as follows:

First, select a solvent as the reaction system, add one or several silane precursors to the system, and add micelles as templates for precursor polymerization, and the mixed system reacts in a high-temperature hydrothermal environment; preparation The obtained substance is post-treated to finally obtain a flower-like nano-inorganic particle with a special shape.

Further, the solvent is one or more of the following substances: water, methanol, ethanol, propanol, butanol, pentanol, cyclohexane, cyclopentane;

Furthermore, the precursor is one or more of the following substances: methyl orthosilicate, ethyl orthosilicate, isopropyl orthosilicate, tetrapropyl orthosilicate, methyl triethoxy silane, dimethyldiethoxysilane, tetrakis (2-methoxy-1-methylethyl) silicate;

Further, the micelles are one or more of the following substances: sodium lauryl sulfate, cetyltrimethylammonium bromide, cetyltrimethylammonium toluenesulfonate, Cetyl pyridinium bromide;

Further, the heating condition temperature and heating reaction time range of the mixed system are 80°C-180°C, 0.5h-12h;

Furthermore, the post-treatment method of the prepared substance is at least one of the following methods: suction filtration, rotary evaporation, centrifugation, and vacuum drying.

The present invention also claims to protect a preparation method of lithium battery composite gel electrolyte, comprising the following steps:

(1) prepare polymer solution;

(2) re-dissolving the prepared polymer in the polymer-soluble solvent;

(3) it is placed in a mold at a certain temperature;

(4) The prepared lithium battery composite gel electrolyte is added with special structural fillers for blending; heat treatment is carried out during and after blending.

Further, the preparation method of the polymer solution mainly includes a polymer and a solvent that can dissolve the polymer: first, the polymer is added to the solvent that can dissolve the polymer according to a certain amount ; The mixed solution is then formed into a film by the action of the mold; enters the heat treatment process and obtains the final required polymer;

Furthermore, the polymer is at least one selected from the following: polyacrylonitrile, polyoxypropylene, polyvinyl chloride, polyvinylidene fluoride, polyethylene oxide, various copolymers such as PVDF-HFP 、PAN-PMMA;

Further, the polymer-soluble solvent is at least one selected from the following: acetone, tetrahydrofuran, N,N-dimethylacetamide, N-methylpyrrolidone;

Further, the heat treatment temperature and time range are: 40°C-120°C, 1-24h;

Furthermore, the amount of the polymer added to the solvent is 1-20 parts, based on 100 parts by weight of the mixture of the polymer and the solvent.

Furthermore, the temperature range of the mold in step (3) is: 30°C to 120°C;

Further, the blending time range described in step (4) is: 1-12h;

Furthermore, the addition amount of the nano-inorganic particle filler is 1-20 parts, based on 100 parts by weight of the mixture of the polymer and the filler.

The present invention also claims a lithium battery, which includes in a battery case: a negative electrode, a positive electrode, the above-mentioned special structural filler for the lithium battery composite gel electrolyte, a polymer, and an electrolyte solution.

Further, the preparation method of the battery electrolyte mainly includes an electrolyte salt and a solvent that can dissolve the electrolyte salt: directly adding the electrolyte salt to the single or mixed mixture of the soluble electrolyte salt according to a certain amount. in the solvent;

Further, the electrolyte salt is at least one selected from the following substances: lithium bis-fluorosulfonimide (LiTFSI), lithium perchlorate (LiClCO4), lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate ( LiAsF6) lithium tetrafluoroborate (LiBF4), lithium trifluoromethanesulfonate (LiCFSO3);

Furthermore, the solvent for dissolving the electrolyte salt is a mixed system of at least two substances selected from the following: dimethyl carbonate (DMC), diethyl carbonate (DEC), propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, ethylene glycol bispropionitrile ether, diphenyl ether , crown ether, diethylene glycol dimethyl ether, dioxolane;

Further, the electrolyte salt is added in an amount of 1 to 20 parts by mass, based on 100 parts by weight of the mixture of the electrolyte solvent and the electrolyte salt.

Further, the preparation method of the negative electrode material and/or positive electrode material: first, the slurry of the positive/negative electrode material is coated on a current collector, and the initial positive/negative electrode is prepared after drying and removing the solvent. The final available electrode size and shape are prepared by pressing, cutting and other processes; the slurry contains a positive/negative electrode material, a binder, a solvent, and a conductive material;

Further, the positive electrode material is at least one material selected from the following: lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium vanadium oxide, lithium iron oxide;

Further, the negative electrode material is at least one material selected from the following: graphitized mesocarbon microspheres (MCMB), amorphous carbon, silicon, tin, natural graphite, artificial graphite;

Further, the binder is at least one material selected from the following: PVDF, LA-132, LA-133, CMC, SBR, pectin, etc.;

Furthermore, the conductive material is conductive carbon black.

The present invention also claims to protect a method for assembling a lithium battery, which includes putting the positive/negative electrode, the composite gel polymer electrolyte, and an electrolyte solution into the battery shell in a certain order; the An electrolyte solution needs to be in contact with the surface and/or interior of the positive/negative electrode, the surface and/or interior of the composite gel polymer electrolyte.

The present invention has the following beneficial effects: the present invention uses mesoporous silicon dioxide nanoparticles with special structure as filler, prepares a composite gel polymer electrolyte through a pouring method, and assembles a lithium metal battery. The composite gel polymer electrolyte provided by the invention also has the following advantages:

1) Mesoporous silica nanoparticles have a high specific surface area and internal pore volume, which provides a larger space for storing electrolytes. Under the same volume conditions, the liquid holding capacity of the gel composite electrolyte is significantly higher.

2) Doping similar to high pore volume (such as walnut-like and flower-like fillers) effectively increases the proportion of the filler-polymer interface region, while the migration of lithium ions in the polymer amorphous phase region and the filler-polymer interface region higher efficiency;

3) The advantage of high specific surface area fillers (such as wormhole-like fillers) is that there is a strong Lewis acid-base interaction between the hydroxyl groups on the surface and lithium salts in the electrolyte, which can promote the dissociation of lithium salts and increase lithium battery life. Lithium ion migration number;

4) A lithiation reaction can occur between the filler and the lithium dendrite, and the filler has good mechanical strength. These factors can effectively inhibit the growth of the lithium dendrite and improve the cycle stability of the lithium battery.

Description of drawings

Fig. 1 is the scanning electron microscope picture that uses the composite gel polymer electrolyte filler of embodiment 1;

Fig. 2 is the scanning electron microscope picture that uses the composite gel polymer electrolyte filler of embodiment 2;

Fig. 3 is the scanning electron microscope picture that uses the composite gel polymer electrolyte filler of embodiment 3;

Fig. 4 is the scanning electron microscope picture using the composite gel polymer electrolyte filler of comparative example 2;

Fig. 5 is to use the composite gel polymer electrolyte of embodiment 1 to assemble into the cycle performance of battery;

Figure 6 is the cycle performance of a battery assembled using the composite gel polymer electrolyte of Example 2;

Figure 7 is the cycle performance of a battery assembled using the composite gel polymer electrolyte of Example 3;

Figure 8 is the cycle performance of a battery assembled using the composite gel polymer electrolyte of Comparative Example 1;

Figure 9 shows the cycle performance of batteries assembled using the composite gel polymer electrolyte of Comparative Example 2.

Fig. 10 is the tensile stress-strain curves of various embodiments and comparative examples.

Detailed ways

The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are all conventional materials, reagents, methods and instruments in this field unless otherwise specified, and those skilled in the art can obtain them through commercial channels.

The raw materials used in the following examples are all commercially available products except for the wormhole-shaped, walnut-shaped and flower-shaped mesoporous silica fillers.

The specific surface area and pore volume comparison of ordinary silica nanoparticles, wormhole-shaped, walnut-shaped and flower-shaped nano-silica particles are shown in the following table:

sample	Specific surface area (BET)/m 2 ·g -1	Pore volume (BJH)/cm 3 ·g -1
Ordinary silica particles	164.81	0.57
Wormhole-like silica particles	985.36	0.81
Walnut-shaped silica particles	541.68	1.39
Flower-like silica particles	643.25	1.91

Composite gel polymer electrolytes were prepared using the wormhole-shaped, walnut-shaped and flower-shaped nano-silica particles prepared above.

Embodiment 1: The filler of a composite gel polymer electrolyte in this embodiment is wormhole-shaped silica nanoparticles.

The method for preparing the lithium metal battery assembled by the composite gel polymer electrolyte of Example 1 is carried out in the following steps:

Step 1: Accurately weigh 3.52g cetyltrimethylammonium bromide, 2.38g sodium lauryl sulfate and 5.27g triethanolamine with electronic analytical balance, take 100ml deionized water with measuring cylinder, and cetyl Trimethylammonium bromide, sodium lauryl sulfate and triethanolamine were all dissolved in distilled water and transferred to a 250mL three-necked flask. Mechanical stirring was carried out at a speed of 800 rpm for 10.0 h. Afterwards, 5.6 mL of ethyl orthosilicate was accurately weighed with a pipette and added into a three-neck flask for stirring, and the reaction time was 20.0 h. Then, the nano-silicon particle solution is concentrated by rotary evaporation to obtain a stable nano-silicon particle dispersion, which is then dried to obtain wormhole-like nano-silicon particles with a super-high specific surface area.

Step 2: Make a solution with 0.12g of required silicon dioxide and 0.8g of acetone, sonicate for 1.0h, stir with 1.3g of PVDFHFP and 4.3g of acetone at 50°C to make a solution, mix the two and continue to stir at 50°C After 2.0h, add 0.2g of water and continue to stir for 5.0h, drop the mixed solution on a glass plate with a 200μm spatula to form a film, dry it at room temperature for 1.0h, gently peel it off with tweezers and spread it on a glass plate, put it in 60 ℃ vacuum oven for 24h to remove the residue.

Step 3: First, dry LiCoO ₂ (LCO) powder and carbon black (Super P) in a vacuum oven at 120° C. for 24 hours to remove residual water. To prepare LCO electrodes, LCO powder, PVDF and Super P were dispersed in NMP at a ratio of 8:1:1 to obtain a slurry. Then spread the slurry evenly over the aluminum foil with a spatula. _LiCoO2 /CPE/Li cells were assembled to test cycle performance on the LAND battery test system.

Example 2: The filler of a composite gel polymer electrolyte in this example is walnut-shaped silica nanoparticles.

The method for preparing the lithium metal battery assembled by the composite gel polymer electrolyte of Example 2 is carried out in the following steps:

Step 1: Accurately weigh 4.08g cetyltrimethylammonium bromide, 2.38g sodium dodecylsulfonate and 5.27g ammonia water with electronic analytical balance, take 130ml deionized water with measuring cylinder, and cetyl Trimethylammonium bromide, sodium dodecylsulfonate and ammonia water were all dissolved in distilled water and transferred to a 250mL three-necked flask. Mechanical stirring was carried out at a speed of 600 rpm for 10.0 h. Afterwards, 7.8 mL of ethyl orthosilicate was accurately weighed with a pipette and added into a three-neck flask for stirring, and the reaction time was 15.0 h. Then, the nano-silicon particle solution is concentrated by rotary evaporation to obtain a stable nano-silicon particle dispersion, which is then dried to obtain ultra-high pore volume walnut-shaped silicon nano-particles.

Step 2: Make a solution with 0.21g of the required silica and 1.5g of acetone, sonicate for 1.0h, stir with 2.3g of PVDFHFP and 3.5g of acetone at 50°C to make a solution, mix the two and continue to stir at 50°C After 2.0h, add 0.2g of water and continue to stir for 5.0h, drop the mixed solution on a glass plate with a 200μm spatula to form a film, dry it at room temperature for 1.0h, gently peel it off with tweezers and spread it on a glass plate, put it in 60 ℃ vacuum oven for 24h to remove the residue.

Step 3: First, dry LiCoO ₂ (LCO) powder and carbon black (Super P) in a vacuum oven at 120° C. for 24 hours to remove residual water. To prepare LCO electrodes, LCO powder, PVDF and Super P were dispersed in NMP at a ratio of 8:1:1 to obtain a slurry. Then spread the slurry evenly over the aluminum foil with a spatula. _LiCoO2 /CPE/Li cells were assembled to test cycle performance on the LAND battery test system.

Embodiment 3: The filler of a composite gel polymer electrolyte in this embodiment is flower-shaped silica nanoparticles.

The method for preparing the lithium metal battery assembled by the composite gel polymer electrolyte of Example 3 is carried out in the following steps:

Step 1: Accurately weigh 3.86g of cetyltrimethylpyridinium bromide and 5.7g of ethyl orthosilicate with an electronic analytical balance, and take a mixed solution of 50ml of deionized water and 50ml of cyclohexane with a measuring cylinder, and mix hexadecane Trimethylpyridinium bromide and ethyl orthosilicate were all dissolved in the mixed solution and transferred to a 250mL three-necked flask, and mechanically stirred for 1h to form a uniform emulsion. After the reagents were uniformly dispersed, the mixed solution was transferred to a hydrothermal reaction kettle and reacted at 150° C. for 2 h. Then, the nano-silicon particle solution is concentrated by rotary evaporation to obtain a stable nano-silicon particle dispersion, and dried to obtain flower-shaped nano-silicon particles with abundant channels.

Step 2: Use 0.52g of required silica and 1.5g of acetone to make a solution, sonicate for 1.0h, stir with 5.6g of PVDFHFP and 7.8g of acetone at 50°C to make a solution, mix the two and continue to stir at 50°C After 2.0h, add 0.2g of water and continue to stir for 5.0h, drop the mixed solution on a glass plate with a 200μm spatula to form a film, dry it at room temperature for 1.0h, gently peel it off with tweezers and spread it on a glass plate, put it in 60 ℃ vacuum oven for 24h to remove the residue.

Step 3: First, dry LiCoO ₂ (LCO) powder and carbon black (Super P) in a vacuum oven at 120° C. for 24 hours to remove residual water. To prepare LCO electrodes, LCO powder, PVDF and Super P were dispersed in NMP at a ratio of 8:1:1 to obtain a slurry. Then spread the slurry evenly over the aluminum foil with a spatula. _LiCoO2 /CPE/Li cells were assembled to test cycle performance on the LAND battery test system.

Comparative Example 1: The difference between this example and Example 1 is that there is no filler in the gel polymer electrolyte.

Comparative Example 2: The difference between this example and Example 1 is that the filler in the gel polymer electrolyte is ordinary solid silica nanoparticles.

For the lithium metal batteries obtained in Examples 1-3 and Comparative Examples 1-2, the entire assembly process was operated in an argon glove box, and the assembly sequence was assembled according to negative electrode case/lithium sheet/CPE/LCO electrode sheet/positive electrode case. Finally, the button cell was sealed and extruded into a button cell, and various electrochemical experiments were carried out after standing for 10 hours.

(1) Conductivity test:

The behavior of ionic conductivity was evaluated by performing AC impedance analysis using an Autolab PGSTAT 302N system. The ionic conductivity can be calculated according to equation (4-1) as follows:

σ=L/(Rb·S)

L, Rb and S are the thickness, impedance and area of GPE, respectively. The results are detailed in Table 1.

(2) Liquid absorption test:

By immersing the electrolyte (1M LiDFOB, solvent volume ratio EC:DMC=1:1) in GPE (1M LiDFOB in EC:DMC), the liquid absorption is obtained by the following equation (4-2):

uptake＝(m _i -m ₀ )/m ₀ ×100%

m ₀ is the weight of the dry separator, and _mi is the weight of the separator after immersion in the electrolyte. The results are detailed in Table 1.

(3) Lithium ion migration number test:

Use the CHI760E electrochemical workstation to measure the Li+ migration number, and test the impedance, polarization current and time of the Li/GPE/Li symmetric battery before and after DC polarization. The lithium ion transfer number (tLi+) is calculated by the following equation (4-3):

Here, ΔV is the DC polarization voltage (0.005 V) applied in the chronoamperometry step, _I0 and _IS are the initial current and steady-state current in the chronoamperometry step, respectively. Ro and Rs are the initial and steady-state interfacial resistance, respectively. The results are detailed in Table 1.

Table 1 Performance comparison of gel polymer electrolyte obtained in Example 1-3 and Comparative Example 1-2

the	Conductivity/S·cm -1	Liquid absorption/%	Lithium ion transfer number
Example 1	3.17×10 -4	324	0.63
Example 2	3.29×10 -4	357	0.51
Example 3	3.65×10 -4	403	0.58

Comparative example 1	2.05×10 -4	217	0.33
Comparative example 2	2.56×10 -4	285	0.41

A novel composite gel polymer electrolyte was prepared by exploring the composite process of filler and gel polymer matrix. Those containing gel polymer electrolytes with special structures have high ionic conductivity and lithium ion transfer number. In the battery system of wormhole-like fillers, the possible mechanism for the improvement of electrochemical performance of wormhole-like fillers is proposed and proved: the effective surface area is increased by the uniform distribution and dense microporous structure. This further enhances the strong Lewis acid-base interaction between the electrolyte ion species and the hydroxyl groups on the surface of the ceramic filler, which further dissociates the lithium salt and releases more lithium ions for migration. The ion migration number is the highest, and the reason why the specific capacity of the battery is higher than that of the comparison sample. In the walnut-shaped filler battery system, the structural advantage of high pore volume can effectively increase the filler-polymer interface, which is more conducive to the transport of lithium ions, optimizes the passage of lithium ions during migration, and enables rapid migration of lithium ions , polymer batteries containing walnut-like fillers have higher battery specific capacity when the migration number of lithium ions is lower than that of wormholes. Therefore, the optimized migration channel mechanism brought by high pore volume is better than that of high specific surface area structure. Mechanism of salt. In the flower-shaped filler battery system, the filler has the characteristics of high specific surface area and ultra-high pore volume, which makes the flower-shaped filler have both walnut-like and wormhole-like structural advantages and possible mechanisms of action. Polymer batteries have higher specific capacity. It is well known that lithium ions can transfer faster in the filler-polymer interface and in the amorphous phase, therefore, the lithium ion migration channel of the filler is more optimized, and the lithium ion migration efficiency of the composite gel polymer electrolyte is higher, so that the battery has Excellent cycle performance. Crucially, the uniform distribution of fillers in the gel polymer electrolyte enables the formation of a stable SEI layer on the Li anode, thereby significantly suppressing Li dendrite growth. Compared with filler-free gel electrolytes and solid particle-filled batteries, the gel-polymer batteries doped with mesoporous fillers exhibit excellent cycle stability in addition to higher mechanical strength and thermal stability.

Claims (17)

1. A method for preparing a special structural filler for a lithium battery composite gel electrolyte, the special structural filler includes wormhole-shaped, walnut-shaped or flower-shaped nano-inorganic particles;

   Among them, the preparation process of wormhole-like nano-inorganic particles is as follows:

   First, choose a solvent as the reaction system, add one or several silane precursors to the system, add micelles as templates for precursor polymerization, and add an amine as a mineralizer to enhance the template environment , to prevent micelles from agglomerating, wherein the silane precursor, micellar agent, mineralizer and solvent molar ratio are 1:(0.02-0.06):(7-12):80, and the mixed system reacts in a heated environment ; The prepared material is post-treated to finally obtain a wormhole-like nano-inorganic particle;

   The preparation process of walnut-shaped nano inorganic particles is as follows:

   First, choose a solvent as the reaction system, add one or several silane precursors to the system, add micelles as templates for precursor polymerization, and add an amine as a mineralizer to adjust the pH value , assist polymerization, wherein said silane precursor, micelle agent, mineralizer and solvent molar ratio are 1:(0.01-0.04):(0.015-0.035):80, mixed system reacts under the environment of heating; Preparation The resulting material is post-treated to finally obtain a walnut-shaped nano-inorganic particle;

   Wherein, the preparation process of flower-shaped nano-inorganic particles is as follows:

   First, select a solvent as the reaction system, add one or several silane precursors to the system, and add micelles as templates for precursor polymerization, and mix the system in a high-temperature hydrothermal environment at 80°C to 180°C The reaction is carried out under the following conditions; the prepared substance is post-treated to finally obtain a flower-like nano-inorganic particle with a special shape.
2. The preparation method according to claim 1, wherein the precursor is one or more of the following substances: methyl orthosilicate, ethyl orthosilicate, isopropyl orthosilicate, orthosilicate Tetrapropyl ester, methyltriethoxysilane, dimethyldiethoxysilane, tetrakis(2-methoxy-1-methylethyl)silicate.
3. The preparation method according to claim 1, characterized in that the solvent is one or more of the following substances: water, methanol, ethanol, propanol, butanol, pentanol, cyclohexane, cyclopentane.
4. The preparation method according to claim 1, wherein the micelle is one or more of the following substances: sodium lauryl sulfate, cetyltrimethylammonium bromide, hexadecane ammonium trimethyltoluene sulfonate, hexadecyl pyridinium bromide.
5. The preparation method according to claim 1, wherein the amine mineralizer is one or more of the following substances: ammonia water, triethanolamine, ethyl ammonia, propyl ammonia, butyl ammonia, diethyl ammonia, Amines, diethylammonia, triethylammonia.
6. The preparation method according to claim 1, characterized in that during the preparation of wormhole-shaped and walnut-shaped inorganic nano particles, the range of heating condition temperature and heating reaction time of the mixing system is: 30°C to 120°C, 1- 12h.
7. The preparation method according to claim 1, characterized in that the post-treatment method is at least one of the following methods: suction filtration, rotary evaporation, centrifugation, and vacuum drying.
8. A preparation method of lithium battery composite gel electrolyte, comprising the steps of:

   (1) prepare polymer solution;

   (2) re-dissolving the prepared polymer in the polymer-soluble solvent;

   (3) it is placed in a mold at a certain temperature;

   (4) Adding the lithium battery composite gel electrolyte filler with a special structure prepared by the preparation method described in any one of claims 1-7 into it for blending; performing heat treatment during the blending process and after blending.
9. The preparation method according to claim 8, characterized in that the preparation method of the polymer solution mainly includes a polymer and a solvent that can dissolve the polymer: first, add the polymer according to a certain amount into the solvent in which the polymer can be dissolved; the mixed solution is then shaped into a film by the action of a mold; enters the heat treatment process and obtains the final desired polymer.
10. The preparation method according to claim 9, characterized in that the polymer is at least one selected from the following materials: polyacrylonitrile, polyoxypropylene, polyvinyl chloride, polyvinylidene fluoride, polyethylene oxide, Various copolymers such as PVDF-HFP, PAN-PMMA;

    The polymer-soluble solvent is at least one selected from the following substances: acetone, tetrahydrofuran, N,N-dimethylacetamide, N-methylpyrrolidone;

    The heat treatment temperature and time range are: 40°C to 120°C, 1-24h;

    The amount of the polymer added to the solvent is 1-20 parts, based on 100 parts by weight of the mixture of the polymer and the solvent.
11. The preparation method according to claim 9, characterized in that the mold temperature range in step (3) is: 30°C to 120°C;

    The blending time range described in step (4) is: 1-12h;

    The added amount of the nano inorganic particle filler is 1-20 parts, based on 100 parts by weight of the mixture of the polymer and the filler.
12. A kind of lithium battery, described battery comprises in a battery case: a kind of negative pole, a kind of positive pole, the special structural filler of lithium battery composite gel electrolyte prepared by the preparation method described in any one of claims 1-7, a A polymer, an electrolyte solution.
13. The preparation method according to claim 12, characterized in that the preparation method of the battery electrolyte mainly includes an electrolyte salt and a solvent that can dissolve the electrolyte salt: directly adding the electrolyte salt to the In a single or mixed solvent in which the electrolyte salt can be dissolved.
14. The preparation method according to claim 13, wherein the electrolyte salt is at least one selected from the following: lithium bis-fluorosulfonyl imide (LiTFSI), lithium perchlorate (LiClCO4), lithium hexafluorophosphate (LiPF6 ), lithium hexafluoroarsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), lithium trifluoromethanesulfonate (LiCFSO3);

    The solvent for dissolving the electrolyte salt is at least a mixed system of two substances selected from the following: dimethyl carbonate (DMC), diethyl carbonate (DEC), propylene carbonate (PC), ethylene carbonate (EC), Ethyl methyl carbonate (EMC), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, ethylene glycol bispropionitrile ether, diphenyl ether, crown ether, Diethylene glycol dimethyl ether, dioxolane;

    The number of parts by mass of the electrolyte salt added is 1 to 20 parts, based on 100 parts by weight of the mixture of the electrolyte solvent and the electrolyte salt.
15. The preparation method according to claim 12, characterized in that the preparation method of said anode material and/or cathode material: first, coating the slurry of said anode/anode material on a current collector, drying and removing The initial positive/negative electrode is prepared after the solvent, and the final usable electrode size and shape are prepared by pressing, cutting and other processes; the slurry contains a positive/negative electrode material, a binder, a solvent, A conductive material.
16. The preparation method according to claim 15, wherein the positive electrode material is at least one material selected from the following: lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium vanadium oxide, lithium iron oxide thing;

    The negative electrode material is at least one selected from the following materials: graphitized mesocarbon microspheres (MCMB), amorphous carbon, silicon, tin, natural graphite, artificial graphite;

    The binder is at least one material selected from the following: PVDF, LA-132, LA-133, CMC, SBR, pectin; the conductive material is conductive carbon black.
17. An assembly method of a lithium battery, characterized in that a composite gel polymer electrolyte comprising the positive/negative electrode, the preparation method according to any one of claims 8-11, and an electrolyte solution are prepared in a certain order Put it into the battery shell; the electrolyte solution needs to be in contact with the surface and/or inside of the positive electrode/negative electrode and the surface and/or inside of the composite gel polymer electrolyte.

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