Hydrotalcite cellulose composite film and preparation method thereof, solid electrolyte membrane and preparation method thereof, lithium battery

Abstract

The application belongs to the technical field of solid electrolyte, and particularly relates to a hydrotalcite cellulose composite film, a preparation method thereof, a solid electrolyte film, a preparation method thereof, and a lithium battery. The hydrotalcite cellulose composite film provided by the application, after in-situ growth of lithium aluminum hydrotalcite on cellulose, not only retains good toughness of cellulose, but also further plays high conductivity and electrochemical stability of lithium aluminum hydrotalcite (LiAl LDH), and improves mechanical properties and electrochemical stability of the composite solid electrolyte.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of solid electrolyte, and particularly relates to a hydrotalcite cellulose composite film, a preparation method thereof, a solid electrolyte film, a preparation method thereof, and a lithium battery. BACKGROUND

[0002] Lithium ion batteries (LIBs) have been considered as an efficient energy storage system based on their energy density, power density, reliability and stability, and have occupied an irreplaceable position in the research of many fields in the past few decades. Since Sony commercialized lithium ion batteries in 1991, portable electronic devices have been inseparable from lithium ion batteries, not only electric vehicles, but also smart grids, lithium ion batteries play a key role. Energy storage devices have gradually increased people's requirements due to the development of technology and the improvement of the quality of life, such as higher volume energy density and power load balancing. However, the above requirements cannot be met by the current lithium ion batteries. Therefore, it is urgent to develop new lithium batteries to meet the requirements of the new era. Safety performance and energy density are the two major problems of the current liquid lithium ion battery. The liquid lithium ion battery mainly uses dimethyl carbonate, ethylene carbonate and other carbonate compounds, which have low volatility and flash point, thus easily causing the flammability of the electrolyte. In addition, dendritic crystals may appear on the surface of the negative electrode, thus penetrating the membrane and causing the battery to catch fire.

[0003] However, as the demand for advanced energy storage continues to increase, the highest energy storage potential of lithium-ion batteries cannot meet the market energy storage density even if it is fully developed to the highest theoretical energy density of the current commercial system. In order to adapt to the requirement of higher energy density in the future, it is necessary to develop all-solid-state metal lithium batteries. The most important part is the solid-state electrolyte. According to the different components of the electrolyte, the solid-state electrolyte is mainly divided into inorganic solid-state electrolyte, polymer solid-state electrolyte and composite solid-state electrolyte. The existing polymer solid-state electrolyte has good elasticity and adaptability to volume change, and is widely used in flexible batteries. However, the polymer is easy to crystallize at room temperature, resulting in low ionic conductivity, and the thermodynamic instability of the interface limits their compatibility with high-voltage positive electrode materials. The poor mechanical properties cannot inhibit the growth of dendrites. Although the inorganic solid-state electrolyte has high ionic conductivity, wide electrochemical window and satisfactory mechanical strength, its brittleness and fragility lead to poor processability and large interface resistance. Therefore, the combination of inorganic solid-state electrolyte and organic solid-state electrolyte in the form of composite solid-state electrolyte is used to solve the above problems of the two kinds of solid-state electrolytes, and the synergistic effect of different materials is realized. The inorganic solid-state electrolyte not only improves the mechanical strength of the polymer electrolyte, but also improves the ionic conductivity of the electrolyte. Due to the interaction between the solid-state electrolytes, the redox stability of the electrolyte is increased, thereby prolonging the electrochemical window. The composite solid-state electrolyte with excellent ionic conductivity, electrochemical stability and excellent mechanical strength provides great potential for the application of the next generation of all-solid-state metal lithium batteries. However, the mechanical properties of the organic-inorganic composite electrolyte are poor, which cannot effectively inhibit the growth of dendrites. In addition, the inherent shortcomings of the polymer may limit the thermal and electrochemical stability of the organic-inorganic composite electrolyte. SUMMARY

[0004] The purpose of the present application is to provide a hydrotalcite cellulose composite film and a preparation method thereof, a solid-state electrolyte film and a preparation method thereof, and a lithium battery. The cellulose composite film provided by the present application can further improve the mechanical properties and thermal and electrochemical stability of the solid-state electrolyte film.

[0005] In order to achieve the above purpose, the present application provides the following technical scheme:

[0006] The present application provides a preparation method of a hydrotalcite cellulose composite film, comprising the following steps:

[0007] The cellulose, poly(4-sodium styrene sulfonate), (3-aminopropyl)trimethoxysilane and water are first mixed, and then dried to obtain modified cellulose;

[0008] mixing the modified cellulose, the water-soluble lithium salt, the water-soluble aluminum salt, the water-soluble meta-aluminates and water, adjusting the pH value of the obtained mixed solution to be alkaline, and then in-situ growing to obtain a lithium-aluminum hydrotalcite-cellulose slurry;

[0009] forming a film from the lithium-aluminum hydrotalcite-cellulose slurry to obtain the hydrotalcite-cellulose composite film;

[0010] The water in the first mixing and the second mixing is deionized water from which carbon dioxide is removed.

[0011] Preferably, the mass ratio of the cellulose and the poly(4-styrenesulfonic acid sodium) is 1:1-6.

[0012] The use amount ratio of the cellulose and the (3-aminopropyl)trimethoxysilane is 3g-6g: 0.5mL-1mL.

[0013] The concentration of the cellulose in the suspension obtained by the first mixing is 2-5wt%.

[0014] The drying temperature is 60-80℃, and the time is 8h.

[0015] Preferably, the water-soluble lithium salt includes one or more of lithium chloride, lithium nitrate, lithium carbonate and lithium sulfate; the water-soluble aluminum salt includes one or more of aluminum chloride, aluminum nitrate, aluminum carbonate and aluminum sulfate; and the water-soluble meta-aluminates includes one or more of sodium meta-aluminate, potassium meta-aluminate and magnesium meta-aluminate.

[0016] The molar ratio of the water-soluble lithium salt and the water-soluble aluminum salt is 1:1-3:1, in terms of the molar amount of Li and Al.

[0017] The molar ratio of the water-soluble lithium salt and the water-soluble meta-aluminate is 1:1-1:2.

[0018] The concentration of the water-soluble lithium salt in the mixed solution obtained by the second mixing is 1-3mol / L.

[0019] The concentration of the modified cellulose in the mixed solution obtained by the second mixing is 3-6wt%.

[0020] Preferably, the process of the second mixing is as follows:

[0021] Firstly mixing the water-soluble lithium salt, the water-soluble aluminum salt and water to obtain solution A;

[0022] Secondly mixing part of the meta-aluminate, sodium hydroxide and water to obtain solution B;

[0023] Thirdly mixing the remaining sodium meta-aluminate and water to obtain solution C;

[0024] After the solution C and the modified cellulose are mixed at the fourth stage, the solution A and the solution B are added dropwise.

[0025] Preferably, the alkaline pH value is 9-11.

[0026] The in-situ growth temperature is 70-85 DEG C, and the time is 2h.

[0027] The application further provides a cellulose composite membrane prepared by the preparation method.

[0028] The application further provides a preparation method of a solid electrolyte membrane.

[0029] After the base film is calcined and immersed in an organic polymer, the solid electrolyte membrane is obtained after drying.

[0030] The base film is the cellulose composite membrane.

[0031] Preferably, the organic polymer comprises one or more of polyethylene glycol diacrylate, polyethylene oxide, polypropylene carbonate and polyvinylidene fluoride-hexafluoropropylene copolymer; and the molecular weight of the organic polymer is 500-1000.

[0032] The calcination temperature is 170-200 DEG C, the temperature rising speed is 5-10 DEG C / min, and the holding time is 4h.

[0033] The soaking time is 1-4h.

[0034] The application further provides a solid electrolyte membrane prepared by the preparation method.

[0035] The application further provides a lithium battery comprising an electrolyte membrane, wherein the electrolyte membrane is the solid electrolyte membrane.

[0036] The application provides a preparation method of a hydrotalcite cellulose composite membrane, comprising the following steps: mixing cellulose, poly(4-sodium styrene sulfonate), (3-aminopropyl)trimethoxysilane and water at a first stage, and drying to obtain modified cellulose; mixing the modified cellulose, a water-soluble lithium salt, a water-soluble aluminum salt, a water-soluble meta-aluminum salt and water at a second stage, adjusting the pH value of the obtained mixed solution to be alkaline, and then performing in-situ growth to obtain a lithium aluminum hydrotalcite-cellulose slurry; and performing film formation on the lithium aluminum hydrotalcite-cellulose slurry to obtain the hydrotalcite cellulose composite membrane; and the water in the first mixing and the second mixing is deionized water without carbon dioxide.

[0037] Compared with the prior art, the application has the following beneficial effects:

[0038] (1) The cellulose composite film provided by the present application, compared with the existing composite solid electrolyte, after growing lithium aluminum hydrotalcite in situ on cellulose, not only retains the good toughness of cellulose, but also further plays the high conductivity and electrochemical stability of lithium aluminum hydrotalcite (LiAl LDH), improves the mechanical properties and electrochemical stability of the composite solid electrolyte, and makes the strain performance reach about 2.0 times of the existing composite solid electrolyte. As can be seen from the examples, the solid electrolyte film prepared by the cellulose composite film provided by the present application shows high ion conductivity of 1.3×10 -3 S / cm, high ion transference number of 0.76 and electrochemical window of 5.1V, which shows that lithium aluminum hydrotalcite plays a major role in ion conduction and maintains high electrochemical stability.

[0039] (2) The reason why the performance of the solid electrolyte film of the present application is excellent is that the fibers between the cellulose exhibit irregular strip-shaped morphology, and each fiber has a porous structure, and the place where the fibers intersect is flat. Such structure makes it have good toughness, dispersibility and chemical stability, so the mechanical properties of the composite solid electrolyte are improved by introducing cellulose. And the in-situ grown lithium aluminum hydrotalcite provides a specific lithium ion transport channel, so that the high ion conductivity and ion transference number are retained, and the cycle performance of lithium symmetric battery and lithium full battery is improved. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 X-ray diffraction spectrum of LiAl LDH hydrotalcite powder obtained in Example 1, LA-Cel solid electrolyte film obtained in Example 3 and cellulose;

[0041] Figure 2 Scanning electron microscope image of the LA-Cel solid electrolyte film obtained in Example 3;

[0042] Figure 3 Electrochemical stability window diagram of the lithium / stainless steel battery assembled by the LA-Cel solid electrolyte film obtained in Example 3;

[0043] Figure 4 Ion conductivity diagram of the LA-Cel solid electrolyte film obtained in Example 3;

[0044] Figure 5 Symmetric battery cycle performance diagram of the LA-Cel solid electrolyte film obtained in Example 3;

[0045] Figure 6 Symmetric battery lithium ion transference number diagram of the LA-Cel solid electrolyte film obtained in Example 3;

[0046] Figure 7 The cycle rate graph of the full solid-state lithium battery assembled by the LA-Cel solid electrolyte film obtained in Example 3 at room temperature;

[0047] Figure 8 The 0.5C cycle performance graph of the full solid-state lithium battery assembled by the LA-Cel solid electrolyte film obtained in Example 3 at room temperature;

[0048] Figure 9 The mechanical property test graph of the LA-Cel solid electrolyte film obtained in Example 3.

[0049] Figure 10 The actuality graph of the LA-Cel solid electrolyte film with different areas obtained in Example 8. DETAILED DESCRIPTION

[0050] The application provides a preparation method of a hydrotalcite cellulose composite film, comprising the following steps:

[0051] The cellulose, poly(4-sodium styrene sulfonate), (3-aminopropyl)trimethoxysilane and water are first mixed, and the modified cellulose is obtained after drying;

[0052] The modified cellulose, a water-soluble lithium salt, a water-soluble aluminum salt, a water-soluble met-aluminum salt and water are secondly mixed, the pH value of the obtained mixed solution is adjusted to be alkaline, and then in-situ growth is carried out to obtain a lithium aluminum hydrotalcite-cellulose slurry;

[0053] The lithium aluminum hydrotalcite-cellulose slurry is subjected to film forming to obtain the hydrotalcite cellulose composite film.

[0054] The water in the first mixing and the second mixing is deionized water from which carbon dioxide is removed.

[0055] In the application, all the preparation raw materials are commercially available products which are well known to those skilled in the art, unless otherwise specified.

[0056] The cellulose, poly(4-sodium styrene sulfonate), (3-aminopropyl)trimethoxysilane and water are first mixed, and the modified cellulose is obtained after drying.

[0057] In the application, the water is deionized water from which carbon dioxide is removed; the method for removing carbon dioxide is preferably boiling the deionized water in an inert atmosphere; and the inert atmosphere is preferably argon.

[0058] In the present application, the mass ratio of the cellulose and poly(4-styrenesulfonic acid sodium) is preferably 1:1-6, further preferably 1:4; the ratio of the amount of the cellulose and (3-aminopropyl)trimethoxysilane is preferably 3g-6g: 0.5mL-1mL, further preferably 6g: 0.5mL. In the present application, the concentration of the cellulose in the suspension obtained by the first mixing is preferably 2-5wt%.

[0059] In the present application, the process of the first mixing is preferably as follows:

[0060] Step 1: dissolving poly(4-styrenesulfonic acid sodium) in water to obtain a poly(4-styrenesulfonic acid sodium) solution; Step 2: dispersing cellulose in pure water to obtain a cellulose suspension; Step 3: dispersing the cellulose suspension in methanol, and then performing ultrasonic treatment and stirring to obtain a cellulose methanol dispersion; Step 4: adding (3-aminopropyl)trimethoxysilane dropwise to the cellulose methanol dispersion, and then performing continuous stirring and centrifugation to obtain a cellulose precipitate; Step 5: dispersing the cellulose precipitate into the poly(4-styrenesulfonic acid sodium) solution, and then performing stirring and centrifugation to obtain modified cellulose; Step 6: dispersing the modified cellulose in water to obtain the modified cellulose suspension.

[0061] In the present application, in Step 1, the dissolving is performed under stirring, and the stirring time is preferably 6h. In the present application, the mass concentration of the poly(4-styrenesulfonic acid sodium) solution is preferably 1%. In the present application, in Step 2, the dispersing is performed under stirring; the stirring time is preferably 12h. In the present application, the ratio of the amount of the cellulose and methanol is preferably 6g: 150mL. In the present application, in Step 3, the ultrasonic treatment time is preferably 30min, and the stirring time is preferably 4h. In the present application, in Step 4, the dropwise adding is preferably performed in a glove box; the continuous stirring time is preferably 24h. In the present application, in Step 5, the stirring time is preferably 6h.

[0062] After the mixing, the present application further preferably comprises centrifuging the obtained mixed system to obtain a precipitate, and then drying the precipitate. In the present application, the drying temperature is preferably 60-80℃, and the time is preferably 8h.

[0063] After obtaining the modified cellulose, the present application second mixes the modified cellulose, a water-soluble lithium salt, a water-soluble aluminum salt, a water-soluble meta-aluminic acid salt and water, adjusts the pH value of the obtained mixed solution to be alkaline, and then performs in-situ growth to obtain a lithium-aluminum hydrotalcite-cellulose slurry.

[0064] In the present application, the water-soluble lithium salt preferably comprises one or more of lithium chloride, lithium nitrate, lithium carbonate and lithium sulfate; the water-soluble aluminum salt preferably comprises one or more of aluminum chloride, aluminum nitrate, aluminum carbonate and aluminum sulfate; and the water-soluble meta-aluminate preferably comprises one or more of sodium meta-aluminate, potassium meta-aluminate and magnesium meta-aluminate. In the present application, the molar ratio of the water-soluble lithium salt to the water-soluble aluminum salt is preferably 1:1 to 3:1, based on the molar amount of Li and Al; and the molar ratio of the water-soluble lithium salt to the water-soluble meta-aluminate is preferably 1:1 to 1:2. In the present application, the concentration of the water-soluble lithium salt in the mixed solution obtained by the second mixing is preferably 1 to 3 mol / L, and more preferably 1.5 mol / L; and the concentration of the modified cellulose in the mixed solution obtained by the second mixing is preferably 3 to 6 wt%, and more preferably 4 wt%.

[0065] In the present application, the process of the second mixing is preferably as follows:

[0066] The water-soluble lithium salt, the water-soluble aluminum salt and water are mixed at a primary stage to obtain a solution A;

[0067] Part of the meta-aluminate, sodium hydroxide and water are mixed at a secondary stage to obtain a solution B;

[0068] The remaining meta-aluminate and water are mixed at a tertiary stage to obtain a solution C;

[0069] The solution C and the modified cellulose are mixed at a quaternary stage under argon and stirring, and then the solution A and the solution B are added dropwise.

[0070] In the present application, the concentration of the water-soluble lithium salt in the solution A is preferably 1.5 mol / L. In the present application, the primary mixing is preferably carried out under ultrasonication, and the time of the ultrasonication is preferably 15 min.

[0071] In the present application, the molar ratio of the part of the meta-aluminate to the sodium hydroxide is preferably 2.5:1. In the present application, the concentration of the part of the meta-aluminate in the solution B is preferably 1 mol / L. In the present application, the secondary mixing is preferably carried out under ultrasonication, and the time of the ultrasonication is preferably 15 min.

[0072] In the present application, the mass of the remaining meta-aluminate is preferably the same as that of the solution B. In the present application, the tertiary mixing is preferably carried out under ultrasonication, and the time of the ultrasonication is preferably 15 min.

[0073] In the present application, the temperature of the quaternary mixing is preferably 85°C; and the quaternary mixing is preferably the addition of the modified cellulose to the solution C. The present application does not have a special limitation on the rate of the dropwise addition, and any rate known to those skilled in the art can be used.

[0074] In the present application, the alkaline pH value is preferably 9-11.

[0075] In the present application, the in-situ growth temperature is 70-85℃. In the present application, the in-situ growth is started when the solution A and solution B are added dropwise.

[0076] After the in-situ growth, the present application further preferably includes cooling the obtained slurry.

[0077] After the lithium aluminum hydrotalcite-cellulose slurry is obtained, the present application performs film formation on the lithium aluminum hydrotalcite-cellulose slurry to obtain the hydrotalcite cellulose composite film.

[0078] In the present application, the film formation method is preferably suction filtration film formation. After the suction filtration film formation, the present application further preferably performs drying and membrane separation, and the drying temperature is preferably 60℃.

[0079] The present application further provides a cellulose composite film prepared by the preparation method described in the above technical solution, which includes a cellulose film substrate and lithium aluminum hydrotalcite in-situ grown on the cellulose film substrate.

[0080] The present application further provides a preparation method of a solid electrolyte film, which includes the following steps:

[0081] After the base film is calcined, it is immersed in an organic polymer, taken out and dried to obtain the solid electrolyte film.

[0082] The base film is the cellulose composite film described in the above technical solution.

[0083] In the present application, the calcination temperature is preferably 170-200℃, the temperature rising speed for rising to the calcination temperature is preferably 5-10℃ / min, and the holding time is preferably 4h.

[0084] In the present application, the organic polymer preferably includes one or more of polyethylene glycol diacrylate, polyethylene oxide, polypropylene carbonate and polyvinylidene fluoride-hexafluoropropylene copolymer; and the molecular weight of the organic polymer is preferably 500-1000.

[0085] In the present application, the immersion time is preferably 1-4h. In the present application, the drying process is preferably: drying in a vacuum drying oven at 80℃ for 24h.

[0086] The present application further provides a solid electrolyte film prepared by the preparation method described in the above technical solution.

[0087] The present application further provides a lithium battery including an electrolyte film, and the electrolyte film is the solid electrolyte film described in the above technical solution.

[0088] In order to further illustrate the present application, the present application involving a hydrotalcite cellulose composite membrane and a preparation method thereof, a solid electrolyte membrane and a preparation method thereof, and a lithium battery are described in detail below with reference to the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present application.

[0089] Example 1

[0090] Preparation of lithium aluminum hydrotalcite powder:

[0091] Deionized water was boiled under an argon atmosphere and then cooled to obtain deionized water (hereinafter referred to as deionized water) from which carbon dioxide was removed for standby use;

[0092] 0.06 mol of LiCl and 0.02 mol of AlCl3 were weighed in a molar ratio of 3:1, dissolved in 40 mL of deionized water, and ultrasonically dissolved for 15 min for standby use to obtain solution A;

[0093] 0.25 mol of NaAlO2 and 1 mol of NaOH were weighed and dissolved in 40 mL of deionized water, and ultrasonically dissolved for 15 min for standby use to obtain solution B;

[0094] The same amount of NaAlO2 as solution B was weighed and dissolved in 40 mL of deionized water, and ultrasonically dissolved for 15 min for standby use to obtain solution C;

[0095] Solution A and solution B were added dropwise to solution C under an argon atmosphere and stirring at 85°C, and the synthesis of lithium aluminum hydrotalcite was performed during the dropwise addition process, and the pH was controlled to be about 11 during the entire process. The system after the reaction was cooled and centrifuged to collect the white precipitate, and deionized water was used for centrifugation until neutralization. The obtained white precipitate was frozen and then transferred to a freeze dryer for drying for 12 h. Then, it was dried at 170°C for 4 h to obtain lithium aluminum hydrotalcite powder (denoted as LiAl LDH hydrotalcite powder), which was stored in a glove box.

[0096] Example 2

[0097] Preparation of lithium aluminum hydrotalcite-cellulose membrane in situ growth:

[0098] Deionized water was boiled under an argon atmosphere and then cooled to obtain deionized water (hereinafter referred to as deionized water) from which carbon dioxide was removed for standby use;

[0099] 1.5 g of poly(4-sodium styrene sulfonate) was weighed and dissolved in 150 mL of deionized water, and stirred for 6 h to obtain a poly(4-sodium styrene sulfonate) solution with a mass concentration of 1%;

[0100] 6.0 g of cellulose was weighed and dispersed in 150 mL of pure water, and stirred for 12 h to obtain a cellulose suspension;

[0101] The cellulose suspension was dispersed in 150 mL of anhydrous methanol, and after ultrasonic treatment for 30 min and stirring for 4 h, the solution was transferred to a glove box, 0.4 mL of (3-aminopropyl)trimethoxysilane was added dropwise to the solution, and after stirring for 24 h, centrifugation was performed;

[0102] The cellulose obtained by centrifugation was dispersed in a poly(4-styrenesulfonic acid sodium) solution, and after stirring for 6 h, centrifugation was performed. The modified cellulose obtained was dissolved in deionized water to obtain a modified cellulose suspension with a concentration of 4 wt%. The modified cellulose suspension obtained was subjected to centrifugal separation, and the precipitate obtained was dried at 80°C for 8 h to obtain modified cellulose.

[0103] 0.06 mol of LiCl and 0.02 mol of AlCl3 were weighed in a molar ratio of 3:1, dissolved in 40 mL of deionized water, and after ultrasonic treatment for 15 min to ensure complete dissolution, solution A was obtained;

[0104] 0.25 mol of NaAlO2 and 1 mol of NaOH were dissolved in 40 mL of deionized water, and after ultrasonic treatment for 15 min to ensure complete dissolution, solution B was obtained;

[0105] The same amount of NaAlO2 as solution B was dissolved in 40 mL of deionized water, and after ultrasonic treatment for 15 min to ensure complete dissolution, solution C was obtained;

[0106] Under an argon atmosphere and stirring at 85°C, 4 g of modified cellulose was added to solution C to obtain a mixture, and then solution A and solution B were added dropwise to the mixture. In-situ growth was performed during the dropwise addition process, and the pH value was controlled at about 11 during the entire process. After cooling, a slurry was obtained, and the slurry was subjected to vacuum filtration, then placed in a 60°C oven for drying, and finally separated from the filter paper to obtain a cellulose composite membrane (denoted as LiAl LDH-cellulose membrane).

[0107] Example 3

[0108] Preparation of a solid electrolyte membrane:

[0109] The cellulose composite membrane obtained in Example 2 was calcined at 185°C for 4 h under an argon atmosphere to remove water in the framework, then immersed in polyethylene glycol diacrylate (PEGDA) with a molecular weight of 700 for 2 h, and then transferred to a 80°C vacuum drying oven for drying for 24 h to obtain a solid electrolyte membrane (LA-Cel solid electrolyte membrane).

[0110] Figure 1 X-ray diffraction spectra of LiAl LDH hydrotalcite powder prepared in Example 1, LA-Cel solid electrolyte membrane obtained in Example 3, and cellulose. FromFigure 1 It can be seen that the XRD spectrum of the prepared LA-Cel composite solid-state electrolyte membrane corresponds to the standard spectrum of LiAlLDH hydrotalcite powder and cellulose, so it can be proved that the lithium aluminum hydrotalcite-cellulose composite solid-state electrolyte membrane is successfully synthesized.

[0111] Example 4

[0112] The solid-state electrolyte membrane prepared in Example 3 (cut into a circular piece with a diameter of 16 m) was used as a battery separator;

[0113] A lithium sheet / stainless steel battery was assembled in the glove box in the order of negative electrode shell, lithium sheet, solid-state electrolyte membrane, gasket, spring, and positive electrode shell, and LSV test was performed to test the electrochemical stability window of the solid-state electrolyte membrane, and the obtained LSV curve is shown in Figure 3 It can be seen from Figure 3 that the prepared solid-state electrolyte membrane shows an electrochemical stability window of up to 5.1 V.

[0114] A stainless steel symmetric battery was assembled in the glove box in the order of negative electrode shell, gasket, solid-state electrolyte membrane, gasket, spring, and positive electrode shell, and AC impedance test was performed to determine the ionic conductivity of the solid-state electrolyte membrane at room temperature. The obtained conductivity curve is shown in Figure 4 It can be seen from Figure 4 that the calculated solid-state electrolyte membrane shows an ionic conductivity of more than 10 -5 S*cm -1 at room temperature, specifically 1.3×10 -3 S / cm.

[0115] Example 5

[0116] The solid-state electrolyte membrane prepared in Example 3 (cut into a circular piece with a diameter of 16 m) was used as a battery separator;

[0117] A Li|Li symmetric battery was assembled in the glove box in the order of negative electrode shell, lithium sheet, solid-state electrolyte membrane, lithium sheet, gasket, spring, and positive electrode shell. The LA-Cel solid-state electrolyte showed excellent stability of lithium stripping / plating and could be stably cycled for 2500 h without short circuit phenomenon, and the overpotential was only about 20 mV, indicating that the LA-Cel solid-state electrolyte membrane had good interface compatibility with the lithium negative electrode.

[0118] Figure 5 The cycle performance graph of the symmetric battery assembled for the LA-Cel solid-state electrolyte membrane, from Figure 5 it can be seen that the ionic conductivity of the prepared solid-state electrolyte membrane is more than 10 2At a current density of 1.5 GHz, the stacked battery assembled using LA-Cel solid-state electrolyte can cycle stably for 2500 h.

[0119] In addition, a lithium ion transference number test was conducted using a symmetrical battery. The lithium ion transference number of the LA-Cel solid electrolyte membrane prepared in Example 3 reached 0.76, indicating that the solid electrolyte constructed using the in-situ growth design has good lithium ion transport capacity. The specific test results are as follows: Figure 6 As shown, it can be seen that after testing and calculation, the lithium ion transference number of LA-Cel solid electrolyte is as high as 0.76.

[0120] Example 6

[0121] The solid electrolyte membrane prepared in Example 3 (cut into discs with a diameter of 16 μm) was used as a battery separator;

[0122] In a glove box, a full battery was assembled in the order of negative electrode shell, lithium sheet, solid electrolyte membrane, lithium iron phosphate positive electrode, gasket, shrapnel, and positive electrode shell, and its cycle performance was tested.

[0123] from Figure 7 It can be seen that the rate performance of the Li||LiFePO4 battery based on the LA-Cel solid electrolyte membrane at different rates from 0.1 to 2.0C at room temperature is excellent, with discharge capacities of 157.8, 145.4, 138.4, 123.2, and 101.5 mAh / g, respectively. Its battery performance is more stable at high rates. After the 2.0C cycle, when the current density returned to 0.1C, the discharge capacity of the Li|LA-Cel|LFP battery recovered to 154.3 mAh / g, which is 97.8% of the initial capacity.

[0124] from Figure 8 It can be seen that under 0.5C conditions, the LA-Cel solid electrolyte membrane shows good cycling performance in 1000 cycles, with a discharge capacity of 127.4 mAh / g after cycling and a capacity retention rate of 91.4%.

[0125] Example 7

[0126] Mechanical performance testing of the solid electrolyte membrane prepared in Example 3 was performed. Tensile testing of the LA-Cel solid electrolyte demonstrated excellent flexibility. Therefore, the LA-Cel solid electrolyte exhibits excellent mechanical properties, effectively suppresses lithium dendrite growth, and provides good contact between the positive and negative electrodes, suggesting promising application prospects.

[0127] from Figure 9It can be seen that the stress of LA-Cel solid electrolyte reaches 23.24 MPa, and the strain reaches 45.32%.

[0128] Example 8

[0129] According to the method in Example 3, the composite solid electrolyte is prepared, and the difference is that a large container is used, and the amount of reagent used is increased, that is, the solid electrolyte film prepared in batches can be obtained. LA-Cel solid electrolyte films of different sizes are prepared, with a diameter of 1.6 cm to 11 m or even larger, so as to illustrate that the LA-Cel electrolyte film can be prepared in large quantities.

[0130] Figure 10 In order to obtain the physical map of the obtained LA-Cel solid electrolyte film with different areas, from Figure 10 It can be seen that the solid electrolyte films prepared in different scales have similar appearances and no obvious difference.

[0131] Although the above examples make a detailed description of the present application, it is only a part of the embodiments of the present application, not all the embodiments, and other embodiments can be obtained according to the present embodiments without creativity, which belong to the protection scope of the present application.

Claims

1. A method for producing a solid-state electrolyte film, characterized by, The method comprises the following steps: The cellulose, poly(4-sodium styrene sulfonate), (3-aminopropyl)trimethoxysilane and water are first mixed to obtain modified cellulose after drying; The modified cellulose, water-soluble lithium salt, water-soluble aluminum salt, water-soluble meta-aluminum salt and water are second mixed, and the pH value of the obtained mixed solution is adjusted to be alkaline, then in-situ growth is carried out to obtain lithium aluminum hydrotalcite-cellulose slurry; the water in the first and second mixing is deionized water without carbon dioxide; The lithium aluminum hydrotalcite-cellulose slurry is formed into a film to obtain a hydrotalcite cellulose composite film; The hydrotalcite cellulose composite film is calcined and then immersed in an organic polymer, and after being taken out, it is dried to obtain the solid electrolyte film; The mass ratio of the cellulose and poly(4-sodium styrene sulfonate) is 1:1-6; The dosage ratio of the cellulose and (3-aminopropyl)trimethoxysilane is 3g-6g:0.5mL-1mL; The concentration of the cellulose in the suspension obtained by the first mixing is 2-5wt%; The drying temperature is 60-80℃, and the time is 8h; The water-soluble lithium salt comprises one or more of lithium chloride, lithium nitrate, lithium carbonate and lithium sulfate; the water-soluble aluminum salt comprises one or more of aluminum chloride, aluminum nitrate, aluminum carbonate and aluminum sulfate; the water-soluble meta-aluminum salt comprises one or more of sodium meta-aluminate, potassium meta-aluminate and magnesium meta-aluminate; The molar ratio of the water-soluble lithium salt and the water-soluble aluminum salt is 1:1-3:1, in terms of the molar amount of Li and Al; The molar ratio of the water-soluble lithium salt and the water-soluble meta-aluminum salt is 1:1-1:2; The concentration of the water-soluble lithium salt in the mixed solution obtained by the second mixing is 1-3mol / L; The concentration of the modified cellulose in the mixed solution obtained by the second mixing is 3-6wt%.

2. The production method according to claim 1, characterized by, The process of the second mixing is as follows: The water-soluble lithium salt, the water-soluble aluminum salt and water are first mixed to obtain solution A; Part of the meta-aluminum salt, sodium hydroxide and water are second mixed to obtain solution B; The remaining sodium meta-aluminate and water are third mixed to obtain solution C; The solution C and the modified cellulose are fourth mixed, and the solution A and the solution B are added dropwise.

3. The preparation method according to claim 1, characterized in that The pH value of the alkaline is 9-11; The temperature of the in-situ growth is 70-85℃, and the time is 2h.

4. The production method according to any one of claims 1 to 3, characterized by, The hydrotalcite cellulose composite film comprises a cellulose film matrix and lithium aluminum hydrotalcite in-situ grown on the cellulose film matrix.

5. The preparation method according to claim 1, characterized in that The organic polymer comprises one or more of polyethylene glycol diacrylate, polyethylene oxide, polypropylene carbonate and polyvinylidene fluoride-hexafluoropropylene copolymer; the molecular weight of the organic polymer is 500-1000; The calcination temperature is 170-200℃, the temperature rising speed for rising to the calcination temperature is 5-10℃ / min, and the holding time is 4h; The immersion time is 1-4h.

6. The solid electrolyte film prepared by the preparation method in any one of claims 1-5.

7. A lithium battery comprising an electrolyte membrane, characterized in that, The electrolyte film is the solid electrolyte film in claim 6.

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