Shear-thickened electrolyte and its preparation method

Abstract

This invention relates to a shear-thickening electrolyte and its preparation method. The shear-thickening electrolyte exhibits impact-hardening properties under high excitation and flame-retardant properties under low excitation. The shear-thickening electrolyte comprises lithium salt, organic solvent, and mesoporous particulate filler for adsorbing flame retardants. The preparation method includes the following steps: a. synthesis of mesoporous silica; b. dispersion of the product obtained in step a in a triphenyl phosphate ethanol solution, followed by stirring and ultrasonic adsorption; c. uniform dispersion of the product obtained in step b in a conventional electrolyte. The shear-thickening electrolyte possesses the functions of rapid hardening under high impact rates to resist external impacts and flame retardancy under low excitation rates, protecting users from impact and high-temperature damage.

Description

Technical Field

[0001] This invention relates to the field of smart materials and manufacturing, specifically to a shear-thickening electrolyte and its preparation method, wherein the electrolyte is a shear-thickening electrolyte with anti-collision and flame-retardant functions. Background Technology

[0002] With the development and popularization of new energy vehicles, vehicle safety performance has gradually attracted widespread attention. Statistics show that in safety accidents involving electric and hybrid vehicles, 30% have been identified as battery-related. Furthermore, in collision-related fires, 60% are caused by the battery. It can be said that battery collision safety has become a crucial factor affecting the safety performance of new energy vehicles.

[0003] Current methods for improving automotive collision safety performance suffer from drawbacks such as excessively heavy protective packs, reduced driving range, and slow response times. Shear-thickened electrolytes, however, can passively respond to rapid external stimuli. The viscosity of the system increases rapidly upon impact and quickly returns to its initial state after the stimulus disappears, making it an effective method for improving battery collision safety. US Patent No. 20160093917 discloses a method for preparing a passively impact-resistant shear-thickened electrolyte, wherein the dispersed phase particles are 20%–40% by mass of solid ceramic particles. US Patent No. 2020028724 discloses a method for preparing a shear-thickened electrolyte by dispersing solid ceramic particles with a polydispersity index less than 0.1 and an average particle size of 50 nm–1 μm into an electrolyte salt, thus obtaining a shear-thickened electrolyte with impact-resistant properties. US Patent Publication No. US20190181504 discloses a passively shock-resistant composite electrolyte, wherein the dispersed phase particles are solid ceramic particles with a mass fraction of 20%–40% that have undergone heat treatment under negative pressure at 80 degrees Celsius. Chinese Patent Publication No. CN113381067 discloses a safe electrolyte capable of liquid-quasi-solid interconversion, comprising an organic carbonate solvent, an electrolyte lithium salt, and functional electrolyte additives, wherein the functional electrolyte additives include conventional film-forming additives and solid nano-oxides that provide a shear thickening effect.

[0004] Based on currently available patents, shear-thickening electrolytes can rapidly increase viscosity under high-speed impact to resist external shocks, thus providing explosion-proof and shock-resistant protection. However, they cannot effectively protect the battery at low excitation rates. This means that such shear-thickening electrolytes cannot solve the problem of spontaneous combustion and fire in lithium-ion batteries under static charging conditions, and are also not suitable for large-scale promotion and application. In the literature 'Shear thickening electrolyte built from sterically stabilized colloidal particles' (B. Shen, Blamstrong, M. Doucet, et al.), a battery based on a conventional electrolyte had a specific capacity of 141 mAh g after 100 cycles. -1 The battery based on shear-thickened electrolyte has a specific capacity of only 108 mAh g after 100 cycles. -1 The reduction was 23.40%. Furthermore, compared to the ionic conductivity of the conventional electrolyte after standing for 24 hours (11.6 mS / cm),... -1 The ionic conductivity of the shear-thickened electrolyte after standing for 24 hours was 5.4 mS / cm. -1 The decrease was 53.45%. Summary of the Invention

[0005] This invention overcomes the shortcomings of traditional technologies by employing mesoporous particulate fillers that adsorb flame retardants to provide a shear-thickening electrolyte and its preparation method. The shear-thickening electrolyte exhibits high-speed impact resistance and low-speed flame retardancy, thus protecting the lives and property of occupants in new energy vehicles.

[0006] Specifically, the present invention is achieved through the following technical solution:

[0007] A shear-thickening electrolyte, comprising lithium salt, organic solvent, and mesoporous particle filler for adsorbing flame retardant; based on the total mass of the shear-thickening electrolyte, the mass percentage of lithium salt is 10%–20%, the mass percentage of organic solvent is 60%–80%, and the mass percentage of mesoporous particle filler for adsorbing flame retardant is 9%–24%.

[0008] Further, the mass percentage of lithium salt is 10% to 20% based on the total mass of the shear-thickening electrolyte. For example, the mass percentage of lithium salt is 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18%, 18.5%, 19%, 19.5%, or 20% based on the total mass of the shear-thickening electrolyte.

[0009] Furthermore, based on the total mass of the shear-thickening electrolyte, the organic solvent content is 60% to 80% by mass. For example, based on the total mass of the shear-thickening electrolyte, the mass percentage of organic solvent is 60%, 60.5%, 61%, 61.5%, 62%, 62.5%, 63%, 63.5%, 64%, 64.5%, 65%, 65.5%, 66%, 66.5%, 67%, 67.5%, 68%, 68.5%, 69%, 69.5%, 70%, 70.5%, 71%, 71.5%, 72%, 72.5%, 73%, 73.5%, 74%, 74.5%, 75%, 75.5%, 76%, 76.5%, 77%, 77.5%, 78%, 78.5%, 79%, 79.5%, or 80%.

[0010] Further, based on the total mass of the shear-thickening electrolyte, the mass percentage of the mesoporous particle filler adsorbing the flame retardant is 9% to 24%. For example, based on the total mass of the shear-thickening electrolyte, the mass percentage of the mesoporous particle filler adsorbing the flame retardant is 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18%, 18.5%, 19%, 19.5%, 20%, 20.5%, 21%, 21.5%, 22%, 22.5%, 23%, 23.5%, or 24%.

[0011] Furthermore, the shear-thickening electrolyte comprises mesoporous silica particles that adsorb the flame retardant triphenyl phosphate, lithium salt (lithium hexafluorophosphate), and organic solvent (EC / EMC / DMC volume ratio 1:1:1).

[0012] Furthermore, the organic solvent is a mixed solution formed by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC).

[0013] Furthermore, the mesoporous silica particles adsorbing the flame retardant triphenyl phosphate are obtained by uniformly dispersing 3.0 g of mesoporous silica in a 250 mL ethanol solution containing 12 g of triphenyl phosphate, followed by ultrasonic oscillation and stirring for adsorption. Preferably, the ultrasonic oscillation time is 2 h, the stirring adsorption speed is 1000 rpm / min, and the time is 24 h.

[0014] Furthermore, the mesoporous silica is prepared by the "sacrificial template method". In the preparation process, the template agent is hexadecyltrimethylammonium bromide, the silicon source is tetraethyl orthosilicate, and the alkaline hydrolysis environment is ammonia water.

[0015] Furthermore, the volume ratio of ethanol to water in the mesoporous silica is 0.5:1.

[0016] Furthermore, the components for preparing mesoporous silica need to be continuously mechanically stirred under water bath conditions; preferably, the water bath temperature is 45 degrees Celsius, the continuous stirring time is 24 hours, and the stirring speed is 650 rpm / min.

[0017] Furthermore, the suspension system in the process of preparing mesoporous silica needs to be centrifuged to obtain the mesoporous silica / template intermediate product; preferably, the centrifugation rate is 7900 rpm / min and the centrifugation time is 10 min.

[0018] Furthermore, the mesoporous silica / template agent needs to be calcined in a muffle furnace to remove the template agent; preferably, the calcination temperature is 550 degrees Celsius, the calcination time is 360 min, and the heating time is 90 min.

[0019] Furthermore, the mesoporous particle filler for adsorbing flame retardants is prepared by the following method: mesoporous silica is uniformly dispersed in an ethanol solution of triphenyl phosphate, and then subjected to ultrasonic oscillation and stirring for adsorption.

[0020] Furthermore, the mass ratio of mesoporous silica to triphenyl phosphate is 5:1 to 50:1; for example, the mass ratio of mesoporous silica to triphenyl phosphate is 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, 21:1, 22:1, 23... :1, 24:1, 25:1, 26:1, 27:1, 28:1, 29:1, 30:1, 31:1, 32:1, 33:1, 34:1, 35:1, 36:1, 37:1, 38:1, 39:1, 40:1, 41:1, 42:1, 43:1, 44:1, 45:1, 46:1, 47:1, 48:1, 49:1, or 50:1.

[0021] Furthermore, the mesoporous silica is uniformly dispersed in the electrolyte by magnetic stirring for 2 hours at a rate of 600 rpm / min; preferably, this step is performed in a glove box.

[0022] The method for preparing the shear-thickening electrolyte as described above includes the following steps:

[0023] a. Mix hexadecyltrimethylammonium bromide, water, ethanol, tetraethyl orthosilicate and ammonia, stir, centrifuge, wash, remove template agent, and calcine to obtain mesoporous silica;

[0024] b. Mesoporous silica was dispersed in a triphenyl phosphate ethanol solution and subjected to ultrasonic adsorption. After evaporation, mesoporous silica with adsorbed flame retardant was obtained.

[0025] c. Mix the mesoporous silica with adsorbed flame retardant obtained in step b with lithium salt and organic solvent, and stir evenly to obtain the shear-thickening electrolyte.

[0026] Specifically, the method for preparing the shear-thickening electrolyte as described above includes the following steps:

[0027] a. Add water, ethanol, tetraethyl orthosilicate, hexadecyltrimethylammonium bromide and ammonia to a three-necked flask and mechanically stir in a water bath for 24 hours;

[0028] b. Centrifuge the suspension obtained in step a to obtain a white particulate precipitate;

[0029] c. Wash the white particles twice with deionized water and once with ethanol to obtain the mesoporous silica / templative intermediate product.

[0030] d. The intermediate product obtained in step c is magnetically stirred in a hydrochloric acid-ethanol solution at 60 degrees Celsius for 4.5 hours to initially remove the template agent; preferably, the volume ratio of hydrochloric acid to ethanol is 0.05:1.

[0031] e. Centrifuge the suspension system obtained in step d, and wash it twice with deionized water and once with ethanol.

[0032] f. Place the white granules obtained in step e in a drying oven for drying; preferably, the drying time is 24 hours and the drying temperature is 80 degrees Celsius;

[0033] g. The particles obtained in step f are placed in a muffle furnace for calcination to further remove the template agent; preferably, the calcination time is 360 min, the temperature is 550 degrees Celsius, and the heating rate is 90 min during the heating process;

[0034] h. Dissolve 12g of triphenyl phosphate in 250mL of ethanol solution and stir magnetically for 10min to obtain a clear and transparent triphenyl phosphate ethanol solution without particle precipitate.

[0035] i. The white particles obtained in step g are uniformly dispersed into the solution system prepared in step h, and then subjected to ultrasonication and stirring adsorption. Preferably, the ultrasonication time is 2 hours, the magnetic stirring is continuous at room temperature for 24 hours, and the stirring adsorption speed is 1000 rpm / min;

[0036] j. Place the white suspension system obtained in step i on a magnetic stirrer for high-temperature evaporation for 30 hours at a temperature of 80 degrees Celsius.

[0037] k. Dry the white particles obtained in step j, grind them, and disperse them evenly in the electrolyte. Stir magnetically for 2 hours at a stirring rate of 600 rpm / min.

[0038] The beneficial effects of this invention are as follows:

[0039] The shear-thickening electrolyte provided by this invention can be widely used in secondary energy storage batteries for new energy vehicles. While effectively improving the collision safety performance of traditional batteries, it also provides excellent flame retardancy through the adsorption of flame retardants within the mesoporous structure. Furthermore, in electrochemical performance tests, the specific capacity of batteries based on the shear-thickening electrolyte (12 wt.%) is approximately equal to that of batteries based on conventional electrolytes, with a slight improvement in coulombic efficiency. Therefore, this material has significant application potential in fields such as secondary energy storage batteries. Attached Figure Description

[0040] Figure 1 This is a scanning electron microscope image of mesoporous silica from Example 1.

[0041] Figure 2 The specific surface area of ​​mesoporous silica and solid silica (Shanghai Buwei Applied Materials Technology Co., Ltd., 300nm spherical silica) in Example 1 is given.

[0042] Figure 3 The pore volume of mesoporous silica and solid silica (Shanghai Buwei Applied Materials Technology Co., Ltd., 300nm spherical silica) in Example 1.

[0043] Figure 4 The thermal conductivity of mesoporous silica and solid silica (Shanghai Buwei Applied Materials Technology Co., Ltd., 300nm spherical silica) in Example 1 is given.

[0044] Figure 5 The nitrogen adsorption test curve of mesoporous silica in Example 1 is shown.

[0045] Figure 6 The adsorption curve of dye ethanol solution on mesoporous silica in Example 1 is shown.

[0046] Figure 7 The sedimentation test results are for mesoporous silica and solid silica (Shanghai Buwei Applied Materials Technology Co., Ltd., 300nm spherical silica) in Example 1.

[0047] Figure 8 The results are the shear rate-viscosity test results of the shear thickening electrolytes in Examples 4-6.

[0048] Figure 9 The results show the combustion performance test results of the conventional electrolyte and the shear-thickened electrolyte of Example 4.

[0049] Figure 10 Electrochemical cycling performance testing of conventional electrolytes.

[0050] Figure 11 Example 4: Electrochemical cycling performance test of shear-thickened electrolyte (12 wt.%).

[0051] Figure 12 Incident energy and dissipated energy of conventional electrolyte and shear-thickened electrolyte of Example 4.

[0052] Figure 13 High-speed bullet tests were conducted using conventional electrolyte and the shear-thickened electrolyte of Example 4 at an initial velocity of 85 m / s.

[0053] Figure 14 High-speed bullet tests were conducted using conventional electrolyte and the shear-thickened electrolyte of Example 4 at an initial velocity of 52 m / s. Detailed Implementation

[0054] The performance parameters of the samples prepared in the following examples were tested according to the following test methods:

[0055] The following are some of the raw materials used in the following embodiments of the present invention: solid silica (Shanghai Buwei Applied Materials Technology Co., Ltd., 300nm spherical silica).

[0056] The standard electrolyte was a commercially available electrolyte purchased from Shanxi Lizhiyuan Battery Materials Co., Ltd. The commercial electrolyte parameters were 1 mol / L LiPF6 (lithium hexafluorophosphate) and the volume ratio of EC / EMC / DMC was 1:1:1.

[0057] Example 1:

[0058] The method for preparing mesoporous silica is as follows:

[0059] Take the following raw materials in the following volume ratios:

[0060] Ethanol:water = 0.5:1

[0061] Mix 150 mL of ethanol with 300 mL of water, add 3.0 g of hexadecyltrimethylammonium bromide and 23 mL of ammonia (molar concentration 13.38 mol / L), and place in a three-necked flask at a water bath temperature of 45 °C with continuous mechanical stirring for 1 h. Then, add 5 mL of tetraethyl orthosilicate dropwise and continue stirring at 45 °C for 24 h. After 24 h, centrifuge and wash the mixture, then wash it with a hydrochloric acid-ethanol solution (hydrochloric acid-ethanol solution with magnetic stirring at 60 °C for 4.5 h, hydrochloric acid to ethanol volume ratio of 0.05:1) and calcine it in a muffle furnace at 550 °C. The temperature is increased from room temperature to 550 °C within 90 min, and the calcination time at 550 °C is 360 min. After natural cooling, mesoporous silica particles with a particle size of 420 nm are obtained.

[0062] The reagents mentioned above are all from Sinopharm Chemical Reagent Co., Ltd. Figure 1 The image shown is a scanning electron microscope image of mesoporous silica from Example 1. It can be seen that the mesoporous silica particles are uniform.

[0063] Figure 2 The specific surface areas of mesoporous silica and solid silica (Shanghai Buwei Applied Materials Technology Co., Ltd., 300nm spherical silica) in Example 1 are shown, indicating that the mesoporous silica prepared in Example 1 has a high specific surface area. Figure 3 The pore volumes are shown for the mesoporous silica and commercially available solid silica (Shanghai Buwei Applied Materials Technology Co., Ltd., 300nm spherical silica) from Example 1. The high pore volume of the mesoporous silica prepared in Example 1 is evident. The pore volumes of both mesoporous and solid silica were measured using a specific surface area and porosity distribution analyzer, model TriStar II 3020.

[0064] Figure 4 The thermal conductivity of mesoporous silica and commercial solid silica in Example 1 is shown. It can be seen that the mesoporous silica prepared in Example 1 has low thermal conductivity. The thermal conductivity of both mesoporous and solid silica was measured using a thermal constant meter, specifically a HotDisk TPS 2500S instrument.

[0065] Figure 5 The nitrogen adsorption test curves for mesoporous silica in Example 1 are shown. This demonstrates the high adsorption characteristics of the mesoporous silica prepared in Example 1 for gases. The nitrogen adsorption test curves for the mesoporous silica were measured using a specific surface area and porosity distribution analyzer, model TriStar II 3020. The adsorption-desorption curves of N2 on the mesoporous structure of the mesoporous silica were also measured using a specific surface area and porosity distribution analyzer, model TriStar II 3020.

[0066] Figure 6 The image shows the adsorption curve of the dye ethanol solution on the mesoporous silica in Example 1. It demonstrates the high adsorption characteristics of the mesoporous silica prepared in Example 1 for liquids.

[0067] Figure 7 The sedimentation test results for mesoporous silica and solid silica (Shanghai Buwei Applied Materials Technology Co., Ltd., 300nm spherical silica) in Example 1 are shown. This indicates that the mesoporous silica prepared in Example 1 has a lower density and improved anti-settling performance compared to solid silica. The sedimentation test methods for mesoporous and solid silica are as follows: 12% by mass of solid silica and mesoporous silica were separately dispersed in 250mL of conventional electrolyte. After stirring with a magnetic stirrer for 1 hour, the mixture was allowed to stand for 24 hours. Then, 40mL of liquid was drawn from 1cm below the top of the liquid surface using a pipette and centrifuged in a centrifuge tube. After centrifugation, the solid silica and mesoporous silica of different masses were obtained by drying in a drying oven at 80℃ for 24 hours. The smaller the mass, the more severe the sedimentation.

[0068] Example 2:

[0069] The method for preparing mesoporous silica is as follows:

[0070] Take the following raw materials in the following volume ratios:

[0071] Ethanol:Water = 1:0.5

[0072] Mix 300 mL of ethanol with 150 mL of water, add 3.0 g of hexadecyltrimethylammonium bromide and 23 mL of ammonia (molar concentration 13.38 mol / L), and place in a three-necked flask at a water bath temperature of 45°C with continuous stirring for 1 hour. Then, add 5 mL of tetraethyl orthosilicate dropwise and continue stirring at 45°C for 24 hours. After 24 hours, centrifuge and wash the mixture, then wash it with a hydrochloric acid-ethanol solution (hydrochloric acid-ethanol solution with magnetic stirring at 60°C for 4.5 hours, hydrochloric acid to ethanol volume ratio 0.05:1) and calcine it in a muffle furnace at 550°C. The temperature is increased from room temperature to 550°C within 90 minutes, and calcined at 550°C for 360 minutes, followed by natural cooling to obtain mesoporous silica particles with a particle size of 650 nm. The specific surface area of ​​the mesoporous silica is 686.2026 m². 2 g -1 The volume of the hole is 0.7747 cm³. 3 g -1 The average pore diameter is 4.2448 nm.

[0073] The reagents mentioned above are all from Sinopharm Chemical Reagent Co., Ltd.

[0074] The particle size of the mesoporous silica prepared in Example 1 and Example 2 was tested respectively. The test method was based on the average value of 8 test points randomly selected from the scanning electron microscope images.

[0075] Ethanol:water volume ratio 0.5:1 1:0.5 Particle size 420nm 650nm

[0076] Example 3:

[0077] The raw material used below is the mesoporous silica with a diameter of 420 nm that adsorbs triphenyl phosphate, prepared in Example 1.

[0078] The preparation steps of mesoporous silica adsorbing triphenyl phosphate flame retardant are as follows:

[0079] Take the following raw materials in the indicated mass ratios:

[0080] Triphenyl phosphate:ethanol = 12:197

[0081] Triphenyl phosphate was added to ethanol at a ratio of 12g of triphenyl phosphate to 250mL of ethanol (approximately 197g by mass), and the mixture was continuously stirred magnetically until the solution became clear and transparent with no solid particles remaining at the bottom. 100g of the mesoporous silica particles obtained in Example 1 were then uniformly dispersed in the triphenyl phosphate ethanol solution. The mixture was ultrasonically vibrated for 2 hours, magnetically stirred for 24 hours, and then evaporated at 80°C for 30 hours to obtain mesoporous silica particles adsorbed with triphenyl phosphate flame retardant.

[0082] Example 4:

[0083] The raw materials used below are the mesoporous silica particles that adsorbed the triphenyl phosphate flame retardant obtained in Example 3 and a conventional electrolyte. The conventional electrolyte is a commercially available electrolyte purchased from Shanxi Lizhiyuan Battery Materials Co., Ltd. The parameters of the commercial electrolyte are 1 mol / L LiPF6 (lithium hexafluorophosphate) and the volume ratio of EC / EMC / DMC is 1:1:1.

[0084] The preparation steps of the shear-thickening electrolyte are as follows: The mesoporous silica particles adsorbing the triphenyl phosphate flame retardant obtained in Example 3 are dispersed in the conventional electrolyte and magnetically stirred for 2 hours at a speed of 600 rpm / min to obtain the shear-thickening electrolyte. The mesoporous silica particles adsorbing the triphenyl phosphate flame retardant constitute 12% of the total mass of the shear-thickening electrolyte.

[0085] Figure 10 This is a test of the electrochemical cycling performance of a conventional electrolyte. Figure 11 Electrochemical cycling performance test of the shear-thickened electrolyte in Example 4 (12 wt.%). Figure 10 and Figure 11The electrochemical performance of the shear-thickening electrolyte in Example 4 is not significantly different from that of a conventional electrolyte. First, a half-cell was assembled, then the battery was clamped onto the test channel. The program was set to activate at 0.2C for 2 cycles, followed by cycling at 0.5C. The charge / discharge range was set to 2.2V–3.8V. After 70 cycles, the attached... Figure 10 and attached Figure 11 The data results are automatically generated by the system after the test is completed.

[0086] Figure 12 Incident and dissipated energy of conventional electrolytes and shear-thickened electrolytes of Example 4 were measured. During testing, the pouch cell was first fixed in a fixture with 12 screws. The impact resistance of the sample was evaluated by the incident and dissipated energy of the bullet penetrating it. The bullet's position was recorded using a high-speed camera. By comparing the displacement and time difference between two images taken before and after the bullet's trajectory, the remaining velocity of the bullet could be calculated. Then, using E = 0.5 mV... 2 The remaining energy of the bullet was calculated. The incident velocity was calculated using a laser velocimeter and an oscilloscope. The test samples in the attached figures are pouch batteries with different formulations, encapsulated in a glove box using an aluminum-plastic film. The conventional electrolyte sample contains 15 mL of conventional electrolyte. The shear-thickening electrolyte sample is the shear-thickening electrolyte prepared in Example 4, containing 15 mL of conventional electrolyte and 12% by mass of the 420 nm diameter mesoporous silica adsorbed with triphenyl phosphate prepared in Example 3. Figure 12 It can be seen that shear-thickened electrolytes can dissipate more energy during impact, thus improving the collision safety performance of traditional batteries. The figure shows the incident energy versus dissipated energy curves for conventional and shear-thickened electrolytes. As can be seen from the figure, with a fixed mass of the spherical bullet, the incident energy depends on the incident velocity of the bullet, while the dissipated energy is calculated from the difference between the incident energy and the remaining energy (which can be derived from the remaining velocity). Due to the energy dissipation characteristics of shear-thickened electrolytes, batteries based on shear-thickened electrolytes exhibit superior energy dissipation characteristics compared to batteries based on conventional electrolytes at different incident velocities.

[0087] Figure 13 High-speed bullet tests were conducted using a conventional electrolyte and the shear-thickening electrolyte from Example 4, both with an initial velocity of 85 m / s. At an initial velocity of 85 m / s, the bullet retained a velocity of 82 m / s after penetrating the pouch cell based on the conventional electrolyte, while the bullet retained a velocity of 70 m / s after penetrating the pouch cell based on the shear-thickening electrolyte, indicating that the shear-thickening electrolyte has better energy dissipation characteristics. In this experiment, the pouch cell dimensions were 120 mm × 100 mm × 5 mm, and the amounts of both the electrolyte and the shear-thickening electrolyte were 60 μL.

[0088] Figure 14 High-speed bullet tests were conducted on conventional electrolytes and the shear-thickening electrolyte of Example 4 at an initial velocity of 52 m / s. The protective and energy dissipation characteristics of the samples under ballistic impact were tested using the following method: The ballistic impact testing system used included an air gun, a laser velocimeter, a digital oscilloscope (Tektronix DPO 2014B), and a high-speed camera (PHANTOM 2701090-1650). A spherical bullet with a diameter of 8.1 mm and a weight of 2 g was placed in the chamber of the air gun. The initial velocity was controlled by the air pressure and the depth of the bullet within the chamber. A laser velocimeter was mounted on the muzzle of the air gun and connected to an oscilloscope to measure the initial velocity of the bullet. The experimental sample was fixed to a clamp opposite the muzzle, with a distance of 15 cm between the muzzle and the clamp. With an initial velocity of 52 m / s, the bullet, after penetrating a pouch cell based on a conventional electrolyte, retained a velocity of 29 m / s. However, after impacting a pouch cell based on a shear-thickening electrolyte, the bullet did not penetrate, retaining a velocity of 0 m / s. This indicates that the shear-thickening electrolyte provides better protection for the battery. In this experiment, the pouch cell dimensions were 120 mm × 100 mm × 5 mm, and the amounts of both the electrolyte and the shear-thickening electrolyte were 60 μL.

[0089] Example 5:

[0090] The raw materials used below are the mesoporous silica particles that adsorbed the triphenyl phosphate flame retardant obtained in Example 3 and a conventional electrolyte. The conventional electrolyte is a commercially available electrolyte purchased from Shanxi Lizhiyuan Battery Materials Co., Ltd., with parameters of 1 mol / L LiPF6 (lithium hexafluorophosphate) and a volume ratio of EC / EMC / DMC of 1:1:1.

[0091] The preparation steps of the shear-thickening electrolyte are as follows:

[0092] The mesoporous silica particles adsorbed with triphenyl phosphate flame retardant obtained in Example 3 were dispersed in the conventional electrolyte and magnetically stirred for 2 hours at a speed of 600 rpm / min to obtain a shear-thickening electrolyte. The mesoporous silica particles adsorbed with triphenyl phosphate flame retardant comprised 15% of the total mass of the shear-thickening electrolyte.

[0093] Example 6:

[0094] The raw materials used below are the mesoporous silica particles that adsorbed the triphenyl phosphate flame retardant obtained in Example 3 and a conventional electrolyte. The conventional electrolyte is a commercially available electrolyte purchased from Shanxi Lizhiyuan Battery Materials Co., Ltd., with parameters of 1 mol / L LiPF6 (lithium hexafluorophosphate) and a volume ratio of EC / EMC / DMC of 1:1:1.

[0095] The preparation steps of the shear-thickening electrolyte are as follows:

[0096] The mesoporous silica particles adsorbed with triphenyl phosphate flame retardant obtained in Example 3 were dispersed in the conventional electrolyte and magnetically stirred for 2 hours at a speed of 600 rpm / min to obtain a shear-thickening electrolyte. The mesoporous silica particles adsorbed with triphenyl phosphate flame retardant comprised 18% of the total mass of the shear-thickening electrolyte.

[0097] The shear-thickened electrolytes prepared in Examples 4-6 were tested together with a particle-free conventional electrolyte (manufactured by Shanxi Lizhiyuan Battery Materials Co., Ltd., with parameters of 1 mol / L LiPF6 (lithium hexafluorophosphate) and an EC / EMC / DMC volume ratio of 1:1:1). The test results are attached. Figure 8 As shown, the conventional electrolyte is a shear-thinning fluid. As the shear rate increases from 1 to 1000 L / s, the viscosity decreases from 49.24 Pa·s to 2.79 Pa·s. However, the shear-thickening electrolytes with mesoporous silica particles containing 12%, 15%, and 18% of the mass percentage of the triphenyl phosphate flame retardant increase in viscosity from 67.45, 85.51, and 98.07 Pa·s to 88.50, 157.38, and 244.36 Pa·s, respectively, at the same shear rate. The relative shear thickening effects reach 31.21%, 84.05%, and 149.17%, respectively. The relative shear thickening effect is calculated as the ratio of the difference between the final viscosity and the initial viscosity to the initial viscosity.

[0098] Figure 8 The results of shear rate-viscosity tests for the shear-thickened electrolytes in Examples 4-6 are presented. This primarily demonstrates that the viscosity of shear-thickened electrolytes exhibits rate-sensitive characteristics; the viscosity of the system increases with increasing shear rate. This provides the theoretical basis for the impact-resistant performance of lithium-ion batteries based on shear-thickened electrolytes. (Appendix) Figure 8 For shear-thickening electrolytes with a mass fraction of 12 wt.% or higher, the viscosity of the system increases significantly with increasing shear rate. Viscosity, as a reflection of a liquid's resistance to flow, directly determines the energy dissipation characteristics of the system. This phenomenon is because shear-thickening electrolytes are strain-rate-dependent smart materials. When the system is subjected to rapid shearing, the particles in the system (i.e., the mesoporous silica adsorbing the flame retardant) form particle clusters, leading to an increase in viscosity and energy dissipation. Shear rate-viscosity test of shear-thickening electrolytes: The shear rate-viscosity test curves of the shear-thickening electrolytes of Examples 4 (12% mass fraction), 5 (15% mass fraction), and 6 (18% mass fraction) and conventional electrolytes are attached. Figure 8As shown, the particles used in the shear-thickening electrolyte are mesoporous silica particles that adsorb flame retardants as obtained in Example 3. The testing method is as follows: The sample is dropped onto a plate of a commercial rheometer (Physica MCR 302, Anton Paar Co., Austria) filled with argon gas to test and characterize its rheological properties. The argon gas cylinder is connected to a flow meter via a latex tube, and the flow meter is then connected to the temperature control hood of the MCR302. Argon gas is passed through for 5 minutes before the test, and then the sample is placed in the hood to ensure that the temperature control hood is filled with argon gas during the test, thus preventing the shear-thickening electrolyte from evaporating during the rheological test. The test volume is approximately 100 μl. The shear rate is set to 1–1000 L / s, with a total of 30 measurement points.

[0099] Figure 9 Combustion performance tests were conducted on the conventional electrolyte and the shear-thickened electrolyte of Example 4. The specific test method for measuring the combustion performance of the conventional electrolyte and the shear-thickened electrolyte of Example 4 is as follows: The sample was placed in the battery casing of a 2036 coin cell and ignited with a blowtorch, and the combustion time was recorded. Figure 9 It can be seen that the self-extinguishing time of the conventional electrolyte is 147 s / g. When mesoporous silica electrolyte (12 wt%, based on the total mass of added mesoporous silica electrolyte) is added, the self-extinguishing time is 144 s / g, a decrease of 2.04% compared to the conventional electrolyte. The mesoporous silica electrolyte with added flame retardant (12 wt%) has a self-extinguishing time of 87 s / g, a decrease of 39.58% compared to the electrolyte with added mesoporous silica (12 wt%). Under static conditions, the mesoporous silica particles with adsorbed flame retardant can reduce the combustion time of the electrolyte and also provide a certain flame-retardant effect.

[0100] Finally, it should be noted that the above embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A shear-thickening electrolyte, characterized in that, The shear-thickening electrolyte is composed of lithium salt, organic solvent, and mesoporous particle filler for adsorbing flame retardant; based on the total mass of the shear-thickening electrolyte, the mass percentage of lithium salt is 10.5%~19.5%, the mass percentage of organic solvent is 60%~78.5%, and the mass percentage of mesoporous particle filler for adsorbing flame retardant is 10.5%~24%. The mesoporous particle filler for the adsorbed flame retardant is mesoporous silica that adsorbs triphenyl phosphate. Mesoporous silica is prepared by the following method: mesoporous silica is obtained by hydrolysis and reaction of tetraethyl orthosilicate as silicon source and hexadecyltrimethylammonium bromide as template agent under alkaline conditions; the particle diameter of the mesoporous silica is 420 nm to 800 nm; the mesoporous particle filler for adsorbing flame retardants is prepared by the following method: mesoporous silica is uniformly dispersed in an ethanol solution of triphenyl phosphate and subjected to ultrasonic and stirring adsorption; the mass ratio of mesoporous silica to triphenyl phosphate is 49:1 to 5:

1.

2. The shear-thickening electrolyte according to claim 1, characterized in that, The surface pore size of the mesoporous silica is 4.2448 nm.

3. The shear-thickening electrolyte according to claim 1, characterized in that, The mass fraction of mesoporous silica particles that adsorb flame retardants in the shear-thickening electrolyte is 18%. When the external excitation rate exceeds the critical rate, the particles will agglomerate, and the viscosity of the system will increase.

4. The shear-thickening electrolyte according to claim 1, characterized in that, In the synthesis of mesoporous silica, V is added to the silicon source. 乙醇 V 水 An ethanol-water mixture with a volume ratio of 0.5:1, wherein the particles are formed by mechanically stirring at 650 rpm / min under water bath conditions for 24 h.

5. The shear-thickening electrolyte according to claim 1, characterized in that, In the synthesis of the mesoporous silica, the template agent is removed by stirring with hydrochloric acid ethanol solution and calcining in a muffle furnace.

6. The shear-thickening electrolyte according to claim 1, characterized in that, The lithium salt is lithium hexafluorophosphate, and the organic solvent is a mixed solution formed by mixing ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate.

7. A method for preparing the shear-thickening electrolyte as described in any one of claims 1-6, characterized in that, Includes the following steps: a. Mix hexadecyltrimethylammonium bromide, water, ethanol, tetraethyl orthosilicate and ammonia, stir, centrifuge, wash, remove template agent, and calcine to obtain mesoporous silica; b. Mesoporous silica was dispersed in a triphenyl phosphate ethanol solution and subjected to ultrasonic adsorption. After evaporation, mesoporous silica with adsorbed flame retardant was obtained. c. Mix the mesoporous silica with adsorbed flame retardant obtained in step b with lithium salt and organic solvent, and stir evenly to obtain the shear-thickening electrolyte.

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