Method for preparing carboxymethyl chitosan-phytic acid-glycerol composite battery separator

Abstract

The application relates to a preparation method of a carboxymethyl chitosan-phytic acid-glycerol composite battery diaphragm and belongs to the field of organic composite battery diaphragms. The application solves the problem that the existing battery diaphragm is difficult to consider biological safety and electrochemical performance. In the application, carboxymethyl chitosan is fully dissolved in deionized water, 50% phytic acid solution, glycerol and auxiliary materials are added, and stirring is conducted until no flocculent insoluble substance is generated to obtain a composite liquid; the composite liquid is centrifuged to remove bubbles, and then constant temperature drying is conducted in a drying box to obtain the carboxymethyl chitosan-phytic acid-glycerol composite battery diaphragm. The carboxymethyl chitosan-phytic acid-glycerol composite battery diaphragm prepared in the application has the characteristics of being edible, high conductivity, compactness, porosity, low swelling rate and excellent tensile strength and the like. The application is mainly applied in the field of swallowable batteries.

Description

Technical Field

[0002] This invention belongs to the field of organic composite battery separators, specifically relating to a method for preparing a carboxymethyl chitosan-phytic acid-glycerol composite battery separator with high conductivity and low swelling rate. Background Technology

[0004] Traditional mainstream battery separators are mainly made of inedible petroleum-based polymer materials. These separators suffer from poor biocompatibility and require the use of toxic organic solvents in their manufacturing process, making them unsuitable for the special needs of swallowable batteries. Therefore, there is an urgent need to develop a non-biotoxic battery separator that can replace traditional plastics.

[0005] Among numerous organic biopolymer materials, chitin possesses characteristics such as natural renewability, good biocompatibility, and excellent ion conduction. Carboxymethyl chitosan, a water-soluble anionic polysaccharide ether produced by carboxymethylation modification of chitin, exhibits excellent biocompatibility, easily tunable chemical structure, and good hydrophilicity, enabling it to form natural membranes. It is currently widely used in medical dressings, food additives, and skincare cosmetics. However, pure carboxymethyl chitosan membranes have two major drawbacks: firstly, their excessive hydrophilicity leads to swelling in electrolytes, causing membrane structure collapse and disruption of ion conduction pathways; secondly, their low conductivity fails to meet the ion transport requirements of battery membranes.

[0006] In summary, no artificially synthesized composite battery separators suitable for use in swallowable batteries have yet been discovered. Existing battery separators struggle to balance biosafety and electrochemical performance, and these issues urgently need to be addressed. Summary of the Invention

[0008] The purpose of this invention is to solve the problem that existing battery separators cannot simultaneously achieve both biosafety and electrochemical performance. This invention provides a method for preparing a carboxymethyl chitosan-phytic acid-glycerol composite battery separator.

[0009] A method for preparing a carboxymethyl chitosan-phytic acid-glycerol composite battery separator, the method comprising:

[0010] S1. Add carboxymethyl chitosan powder to deionized water and stir until fully dissolved. At the same time, add 50% phytic acid solution, glycerin and excipients, and stir until there are no flocculent insoluble substances to obtain a composite solution.

[0011] S2. Transfer the prepared composite liquid into a centrifuge container and centrifuge it in a centrifuge until the composite liquid system is free of bubbles and is homogeneous and stable.

[0012] S3. Wipe the inner wall of the petri dish with anhydrous ethanol. After it dries, pour the centrifuged composite solution into the petri dish along the wall and spread it along the wall to the entire bottom surface of the petri dish. After spreading, the composite solution system should be free of air bubbles.

[0013] S4. Place the petri dish containing the composite solution in a drying oven and dry it at a constant temperature to obtain the carboxymethyl chitosan-phytic acid-glycerol composite battery separator.

[0014] Preferably, in step S1, the ratio of carboxymethyl chitosan, 50% phytic acid solution, glycerol and excipients in the composite solution is 100:12:10:5; the stirring mechanism used in the stirring operation has a rotation speed of 1000 r / min, a temperature of 35℃, and a stirring time of 2 to 3 hours.

[0015] Preferably, the degree of substitution of the carboxymethyl chitosan is ≥80%; and the concentration of the carboxymethyl chitosan in the composite liquid is 1.5g / 50ml to 2.5g / 50ml.

[0016] Preferably, in step S2, the centrifuge speed is 5000 r / min and the centrifugation time is 8 min.

[0017] Preferably, the liquid depth of the composite liquid after spreading in step S3 is 0.72 mm to 1.44 mm.

[0018] Preferably, the constant temperature drying conditions in step S4 are: the composite liquid is dried at 60°C for 10 to 14 hours.

[0019] Preferably, the excipient is one of Tween-80, sodium alginate, sodium carboxymethyl cellulose, and konjac mannan.

[0020] Preferably, the stirring time in step S1 is 3 hours, the concentration of carboxymethyl chitosan in the composite solution is 2 g / 50 ml, the depth of the composite solution after spreading in step S3 is 1.08 mm, and the constant temperature drying conditions in step S4 are: the composite solution is dried at 60°C for 12 hours.

[0021] The beneficial effects of this invention are:

[0022] This invention provides a simple and low-cost method for preparing a carboxymethyl chitosan-phytic acid-glycerol composite battery separator. The method involves fully dissolving carboxymethyl chitosan in deionized water, simultaneously adding 50% phytic acid solution, glycerol, and excipients, and stirring until no flocculent insoluble matter remains to obtain a composite solution. The composite solution is then centrifuged to remove bubbles and placed in a drying oven for constant-temperature drying to obtain the carboxymethyl chitosan-phytic acid-glycerol composite battery separator. The carboxymethyl chitosan-phytic acid-glycerol composite battery separator prepared by this invention is edible and possesses advantages such as high conductivity, density, porosity, low swelling rate, and excellent tensile strength.

[0023] This invention provides a carboxymethyl chitosan-phytic acid-glycerol composite battery separator for use in swallowable batteries. The composite battery separator is constructed using edible-grade natural raw materials as the core. This invention utilizes the hydrogen bond cross-linking network formed by phytic acid and carboxymethyl chitosan to improve the density of the separator, utilizes the plasticizing effect of glycerol to improve the flexibility of the separator, and utilizes excipients to improve the conductivity of the separator. This achieves the goal of improving the conductivity, density, porosity and toughness of the separator while reducing the swelling rate.

[0024] This invention uses edible and non-toxic materials, with no risk of toxic residues, and is suitable for swallowable scenarios. The raw materials are widely available and readily available, which can significantly reduce the preparation cost.

[0025] This invention employs a completely aqueous, non-toxic process, without using any toxic organic solvents throughout the entire process, effectively avoiding potential irritation and damage to the human body.

[0026] This invention has broad application prospects in the fields of flexible electronics and medical power supplies. Attached Figure Description

[0028] Figure 1 This is a schematic diagram illustrating the principle of the preparation method of the carboxymethyl chitosan-phytic acid-glycerol composite battery separator described in this invention;

[0029] Figure 2 The diagram shows the swelling ratios of the composite battery separators CMCS1 to CMCS5 obtained in Examples 1 to 5, respectively.

[0030] Figure 3 The Nyquist plots of the composite battery separators CMCS1 to CMCS5 obtained in Examples 1 to 5 are shown at 25°C; where Zreal is the real part of the impedance of the composite battery separator and Zimag is the imaginary part of the impedance of the composite battery separator.

[0031] Figure 4 The following are bar charts showing the conductivity of the composite battery separators CMCS1 to 5 obtained in Examples 1 to 5 at 25°C.

[0032] Figure 5 The infrared spectra of the composite battery separators CMCS1 to 5 obtained in Examples 1 to 5 are shown below.

[0033] Figure 6 The tensile strength diagrams are for the composite battery separators CMCS1 to 5 obtained in Examples 1 to 5, respectively.

[0034] Figure 7 The stress-strain diagrams are for the composite battery separators CMCS1 to 5 obtained in Examples 1 to 5, respectively. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0038] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0039] Specific Implementation Method 1: Combination Figure 1 This embodiment describes a method for preparing the carboxymethyl chitosan-phytic acid-glycerol composite battery separator, which includes:

[0040] S1. Add carboxymethyl chitosan powder to deionized water and stir until fully dissolved. At the same time, add 50% phytic acid solution, glycerin and excipients, and stir until there are no flocculent insoluble substances to obtain a composite solution.

[0041] In specific applications, the feeding ratio of carboxymethyl chitosan, 50% phytic acid solution, glycerol and excipients in the composite solution is 100:12:10:5; the stirring mechanism used in the stirring operation has a rotation speed of 1000 r / min, a temperature of 35℃, and a stirring time of 2 to 3 hours;

[0042] The excipients are one of Tween-80, sodium alginate, sodium carboxymethyl cellulose, and konjac mannan. By adding non-toxic Tween-80, sodium alginate, sodium carboxymethyl cellulose, and konjac mannan as excipients, the micropore structure of the membrane is further optimized and a continuous ion transport channel is constructed to improve conductivity.

[0043] The degree of carboxymethyl chitosan substitution is ≥80%; the concentration of carboxymethyl chitosan in the composite liquid is 1.5g / 50ml to 2.5g / 50ml;

[0044] S2. Transfer the prepared composite liquid into a centrifuge container and centrifuge it until the composite liquid system is free of bubbles and is homogeneous and stable; specifically, the centrifuge speed is 5000 r / min and the centrifugation time is 8 min.

[0045] S3. Wipe the inner wall of the petri dish with anhydrous ethanol and let it dry. Then, pour the centrifuged composite solution into the petri dish along the wall and spread it to the bottom of the entire petri dish. The composite solution system should be free of air bubbles after spreading. Specifically, the liquid depth of the composite solution after spreading should be 0.72 mm to 1.44 mm.

[0046] S4. Place the petri dish containing the composite solution in a drying oven and dry it at a constant temperature to obtain a carboxymethyl chitosan-phytic acid-glycerol composite battery separator. Specifically, the constant temperature drying conditions are: after drying the composite solution at 60℃ for 10 to 14 hours, a carboxymethyl chitosan-phytic acid-glycerol composite battery separator with high conductivity and low swelling ratio is obtained.

[0047] Furthermore, an optimal combination is provided: in step S1, the stirring time is 3 hours, and the concentration of carboxymethyl chitosan in the composite solution is 2 g / 50 ml; in step S3, the depth of the composite solution after spreading is 1.08 mm; and in step S4, the constant temperature drying condition is that the composite solution is dried at 60°C for 12 hours. Under this combination, the prepared carboxymethyl chitosan-phytic acid-glycerol composite battery separator has the best effect.

[0048] This invention provides a simple and low-cost method for preparing a carboxymethyl chitosan-phytic acid-glycerol composite battery separator with high conductivity and low swelling rate. The method involves fully dissolving carboxymethyl chitosan in deionized water, adding 50% phytic acid, glycerol, and excipients, and stirring until no flocculent insoluble matter remains to obtain a composite solution. The composite solution is then centrifuged to remove bubbles and placed in a drying oven for constant-temperature drying to obtain the carboxymethyl chitosan-phytic acid-glycerol composite battery separator. The carboxymethyl chitosan-phytic acid-glycerol composite battery separator prepared by this invention is edible and possesses advantages such as high conductivity, density, porosity, low swelling rate, and excellent tensile strength.

[0049] Phytic acid, a natural organic acid, is widely found in nuts and some fruits and vegetables. Its molecular structure contains multiple phosphate groups, which can form hydrogen bond cross-linking networks with the hydroxyl and amino groups of carboxymethyl chitosan, thereby increasing the density of the membrane and preventing the collapse of the membrane's conductive pathways.

[0050] Glycerin, as a green plasticizer, can improve the flexibility of the diaphragm, thereby enhancing its tensile strength.

[0051] This invention utilizes the hydrogen-bonded cross-linking network formed by phytic acid and carboxymethyl chitosan to improve the density of the membrane, utilizes the plasticizing effect of glycerol to improve the flexibility of the membrane, and utilizes excipients to improve the conductivity of the membrane, thereby achieving the goal of improving the conductivity and density of the membrane.

[0052] Verification experiment:

[0053] The technical effects of the present invention will be illustrated below through specific embodiments 1 to 5.

[0054] Example 1:

[0055] Step S1: Add 2g of carboxymethyl chitosan powder to 47ml of deionized water and stir until fully dissolved. Then add 0.19ml of 50% phytic acid solution and 0.16ml of glycerol, and stir until there is no obvious foam on the surface and no obvious flocculent insoluble matter in the solution. Then add 0.095ml of Tween-80 and stir further until fully mixed to obtain the composite solution. The entire process is carried out in a stirring system at 1000r / min and 35℃ for 2-3 hours.

[0056] Step S2: Transfer the prepared composite liquid into a centrifuge container and centrifuge at 5000 r / min for 8 min until the composite liquid system is free of bubbles and is homogeneous and stable.

[0057] Step S3: Wipe the inner wall of the culture dish with anhydrous ethanol. After it dries, pour the centrifuged composite solution into the culture dish along the wall and spread it to the entire surface of the culture dish. The composite solution system should be free of air bubbles after spreading, and the liquid depth of the composite solution after spreading should be 1.08 mm.

[0058] Step S4: Place the petri dish containing the composite solution in a drying oven and dry it at 60°C for 10-14 hours to obtain the target product, carboxymethyl chitosan-phytic acid-glycerol composite battery separator CMCS1, which has high conductivity and low swelling rate.

[0059] Example 2:

[0060] Step S1: Add 2g of carboxymethyl chitosan powder to 47ml of deionized water and stir until fully dissolved. Then add 0.19ml of 50% phytic acid solution and 0.16ml of glycerol, and stir until there is no obvious foam on the surface and no obvious flocculent insoluble matter in the solution. Then add 0.1g of sodium alginate and stir further until fully mixed to obtain the composite solution. The entire process is carried out in a stirring system at 1000r / min and 35℃ for 2-3 hours.

[0061] Step S2: Transfer the prepared composite liquid into a centrifuge container and centrifuge at 5000 r / min for 8 min until the composite liquid system is free of bubbles and is homogeneous and stable.

[0062] Step S3: Wipe the inner wall of the culture dish with anhydrous ethanol. After it dries, pour the centrifuged composite solution into the culture dish along the wall and spread it to the entire surface of the culture dish. The composite solution system should be free of air bubbles after spreading, and the liquid depth of the composite solution after spreading should be 1.08 mm.

[0063] Step S4: Place the petri dish containing the composite solution in a drying oven and dry at 60°C for 10-14 hours to obtain the target product, carboxymethyl chitosan-phytic acid-glycerol composite battery separator CMCS2, which has high conductivity and low swelling rate.

[0064] Example 3:

[0065] Step S1: Add 2g of carboxymethyl chitosan powder to 47ml of deionized water and stir until fully dissolved. Then add 0.19ml of 50% phytic acid solution and 0.16ml of glycerol, and stir until there is no obvious foam on the surface and no obvious flocculent insoluble matter in the solution. Then add 0.1g of sodium carboxymethyl cellulose and stir further until fully mixed to obtain the composite solution. The entire process is carried out in a stirring system at 1000r / min and 35℃ for 2-3 hours.

[0066] Step S2: Transfer the prepared composite liquid into a centrifuge container and centrifuge at 5000 r / min for 8 min until the composite liquid system is free of bubbles and is homogeneous and stable.

[0067] Step S3: Wipe the inner wall of the culture dish with anhydrous ethanol. After it dries, pour the centrifuged composite solution into the culture dish along the wall and spread it to the entire surface of the culture dish. The composite solution system should be free of air bubbles after spreading, and the liquid depth of the composite solution after spreading should be 1.08 mm.

[0068] Step S4: Place the petri dish containing the composite solution in a drying oven and dry at 60°C for 10-14 hours to obtain the target product, carboxymethyl chitosan-phytic acid-glycerol composite battery separator CMCS3, which has high conductivity and low swelling rate.

[0069] Example 4:

[0070] Step S1: Add 2g of carboxymethyl chitosan powder to 47ml of deionized water and stir until fully dissolved. Then add 0.19ml of 50% phytic acid solution and 0.16ml of glycerol, and stir until there is no obvious foam on the surface and no obvious flocculent insoluble matter in the solution. Then add 0.1g of konjac mannan and stir further until fully mixed to obtain a composite solution. The entire process is carried out in a stirring system at 1000r / min and 35℃ for 2-3 hours.

[0071] Step S2: Transfer the prepared composite liquid into a centrifuge container and centrifuge at 5000 r / min for 8 min until the composite liquid system is free of bubbles and is homogeneous and stable.

[0072] Step S3: Wipe the inner wall of the culture dish with anhydrous ethanol. After it dries, pour the centrifuged composite solution into the culture dish along the wall and spread it to the entire surface of the culture dish. The composite solution system should be free of air bubbles after spreading, and the liquid depth of the composite solution after spreading should be 1.08 mm.

[0073] Step S4: Place the petri dish containing the composite solution in a drying oven and dry it at 60°C for 10-14 hours to obtain the target product, carboxymethyl chitosan-phytic acid-glycerol composite battery separator CMCS4, which has high conductivity and low swelling rate.

[0074] Example 5:

[0075] Step S1: Add 2g of carboxymethyl chitosan powder to 47ml of deionized water and stir until fully dissolved. Then add 0.19ml of 50% phytic acid solution and 0.16ml of glycerol, and stir until there is no obvious foam on the surface and no obvious flocculent insoluble matter in the solution to obtain a composite solution. The entire process is carried out in a stirring system at 1000r / min and 35℃ for 2-3 hours.

[0076] Step S2: Transfer the prepared composite liquid into a centrifuge container and centrifuge at 5000 r / min for 8 min until the composite liquid system is free of bubbles and is homogeneous and stable.

[0077] Step S3: Wipe the inner wall of the culture dish with anhydrous ethanol. After it dries, pour the centrifuged composite solution into the culture dish along the wall and spread it to the entire surface of the culture dish. The composite solution system should be free of air bubbles after spreading, and the liquid depth of the composite solution after spreading should be 1.08 mm.

[0078] Step S4: Place the petri dish containing the composite solution in a drying oven and dry it at 60°C for 10-14 hours to obtain the target product, carboxymethyl chitosan-phytic acid-glycerol composite battery separator CMCS5, which has high conductivity and low swelling rate.

[0079] The composite battery separator CMCS1 obtained in Example 1 was cut into a 20mm × 20mm shape and dried. The initial thickness of CMCS1 was measured using a five-point sampling method. The composite battery separator CMCS1 obtained in Example 1 was then immersed in a 1mol / L NaHSO4 solution for at least 5 minutes. After drying, the final thickness of CMCS1 was measured using the five-point sampling method, and the swelling rate of CMCS1 was calculated. Examples CMCS2, CMCS3, CMCS4, and CMCS5 were tested using the same method.

[0080] The composite battery separator CMCS1 obtained in Example 1 was immersed in a 1 mol / L NaHSO4 solution for at least 5 min, cut into a circular shape with a diameter of 13 mm, and tested using electrochemical impedance spectroscopy (EIS). Before testing, the assembled Swagelok test system was placed at an open circuit potential and allowed to stand for 2 min until the potential fluctuation amplitude was ≤2 mV before starting the test. A sinusoidal AC voltage of 5 mV was applied, the scan range was 0.1-10000 Hz, the sampling point number was set to 10 points / decade, and the test temperatures were 25℃, 35℃, 45℃, and 55℃, respectively. The conductivity of Example CMCS1 at different test temperatures was calculated. Examples CMCS2, CMCS3, CMCS4, and CMCS5 were tested using the same method.

[0081] The composite battery separator CMCS1 obtained in Example 1 was cut into a 2mm × 2mm shape and tested using a Fourier transform infrared spectroscopy (FTIR) instrument, with a wavenumber test range of 4000 to 4000. The resolution is set to 4. The number of scans was 32, baseline correction was performed with air as the background, and the test environment was maintained at 25°C. The composite battery separators CMCS2, CMCS3, CMCS4, and CMCS5 obtained in Examples 2 to 5 were tested using the same method.

[0082] The composite battery separator CMCS1 obtained in Example 1 was cut into a shape of 10mm × 30mm, and a room temperature tensile test was performed on CMCS1 using an electronic universal testing machine. The portion within 10mm on both sides of CMCS1 was adhered to an industrial insulating rubber sheet and clamped in the testing machine, and a tensile test was performed at a speed of 2mm / min. The composite battery separators CMCS2, CMCS3, CMCS4, and CMCS5 obtained in Examples 2 to 5 were tested using the same method.

[0083] The performance of the composite battery separators CMCS1~5 obtained in Examples 1 to 5 are as follows:

[0084] like Figure 2 As shown, the swelling rates of the composite battery separator CMCS4 obtained in Example 4 and the composite battery separator CMCS5 obtained in Example 5 were 114.86% and 111.06%, respectively, which were significantly lower than the swelling rate of 236.7% of the composite battery separator CMCS2 obtained in Example 2. This indicates that konjac mannan and the blank formulation performed better in suppressing swelling and could ensure the dimensional stability of the separator during battery operation.

[0085] like Figure 3 As shown, the resistance in each embodiment is at 100. Up to 300 The presence of these features indicates that the carboxymethyl chitosan-phytic acid-glycerol composite battery separator prepared by this invention has low overall resistance and excellent proton conduction performance, which can effectively ensure efficient proton transport during battery operation.

[0086] like Figure 4 As shown, the composite battery separator CMCS3 obtained in Example 3 has the highest conductivity, reaching 66.56 mS / cm, and the composite battery separator CMCS4 obtained in Example 4 also reaches 58.1 mS / cm. This indicates that adding sodium carboxymethyl cellulose or konjac mannan can effectively improve the proton conduction capacity of the separator and meet the design goal of high conductivity.

[0087] like Figure 5 As shown, the infrared spectral curves corresponding to each embodiment are all at 1410 cm⁻¹. -1 A stable characteristic peak appears nearby, corresponding to the interaction between the carboxyl group (-COOH) in the phytic acid molecule and the carboxyl group (-CH2COOH) in the carboxymethyl chitosan molecule, forming a hydrogen-bonded complex structure; in The characteristic peaks nearby indicate that a large number of hydroxyl groups (-OH) in the three molecules form dense intermolecular hydrogen bonds, achieving the initial cross-linking of the three molecules; The shift of characteristic peaks in the vicinity confirms that the COC ether bonds and CN bonds in carboxymethyl chitosan interact with the PO bonds in phytic acid and the CO bonds in glycerol, further enhancing the cross-linking effect; The strong characteristic peaks nearby indicate that the bond energy and bond length of the CO bond change regularly during the interaction process, forming a stable composite structure interwoven with covalent and hydrogen bonds. This fully confirms that carboxymethyl chitosan, phytic acid and glycerol underwent a synergistic reaction in each embodiment, thereby forming a composite battery membrane with stable structure and excellent performance.

[0088] like Figure 6 As shown, the composite battery separator CMCS4 obtained in Example 4 has a significantly better fracture strength than other examples, with a maximum bearing capacity of about 25N and the ability to withstand greater deformation. This indicates that konjac mannan performs outstandingly in improving the overall structural stability and deformation resistance of the separator.

[0089] like Figure 7 As shown, the composite battery separator CMCS5 obtained in Example 5 has the highest elastic modulus, reaching approximately 340 MPa, exhibiting the strongest resistance to deformation stiffness. The composite battery separator CMCS4 obtained in Example 4 has the highest elongation at break, reaching approximately 22%, demonstrating the best flexibility. The composite battery separator CMCS2 obtained in Example 2 has a tensile strength of approximately 30 MPa, which is significantly better than the other examples, indicating that sodium alginate can effectively improve the tensile load-bearing capacity of the separator.

[0090] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A method for preparing a carboxymethyl chitosan-phytic acid-glycerol composite battery separator, characterized in that, The method includes: S1. Add carboxymethyl chitosan powder to deionized water and stir until fully dissolved. At the same time, add 50% phytic acid solution, glycerin and excipients, and stir until there are no flocculent insoluble substances to obtain a composite solution. S2. Transfer the prepared composite liquid into a centrifuge container and centrifuge it in a centrifuge until the composite liquid system is free of bubbles and is homogeneous and stable. S3. Wipe the inner wall of the petri dish with anhydrous ethanol. After it dries, pour the centrifuged composite solution into the petri dish along the wall and spread it along the wall to the entire bottom surface of the petri dish. After spreading, the composite solution system should be free of air bubbles. S4. Place the petri dish containing the composite solution in a drying oven and dry it at a constant temperature to obtain the carboxymethyl chitosan-phytic acid-glycerol composite battery separator.

2. The method for preparing the carboxymethyl chitosan-phytic acid-glycerol composite battery separator according to claim 1, characterized in that, In step S1, the ratio of carboxymethyl chitosan, 50% phytic acid solution, glycerol and excipients in the composite solution is 100:12:10:5; the stirring mechanism used in the stirring operation has a rotation speed of 1000 r / min, a temperature of 35℃, and a stirring time of 2 to 3 hours.

3. The method for preparing the carboxymethyl chitosan-phytic acid-glycerol composite battery separator according to claim 2, characterized in that, The degree of substitution of the carboxymethyl chitosan is ≥80%; the concentration of the carboxymethyl chitosan in the composite liquid is 1.5g / 50ml to 2.5g / 50ml.

4. The method for preparing the carboxymethyl chitosan-phytic acid-glycerol composite battery separator according to claim 1, characterized in that, In step S2, the centrifuge speed is 5000 r / min and the centrifugation time is 8 min.

5. The method for preparing the carboxymethyl chitosan-phytic acid-glycerol composite battery separator according to claim 1, characterized in that, In step S3, the liquid depth of the spread composite liquid is 0.72 mm to 1.44 mm.

6. The method for preparing the carboxymethyl chitosan-phytic acid-glycerol composite battery separator according to claim 1, characterized in that, The constant temperature drying conditions in step S4 are: the composite solution is dried at 60℃ for 10 to 14 hours.

7. The method for preparing the carboxymethyl chitosan-phytic acid-glycerol composite battery separator according to claim 1, characterized in that, The excipients are one of Tween-80, sodium alginate, sodium carboxymethyl cellulose, and konjac mannan.

8. The method for preparing the carboxymethyl chitosan-phytic acid-glycerol composite battery separator according to claim 1, characterized in that, In step S1, the stirring time is 3 hours, and the concentration of carboxymethyl chitosan in the composite solution is 2 g / 50 ml. In step S3, the depth of the composite solution after spreading is 1.08 mm. In step S4, the constant temperature drying conditions are: the composite solution is dried at 60°C for 12 hours.

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