阅读说明：本技术 一种生物基凝胶聚合物电解质及其制备方法 (Bio-based gel polymer electrolyte and preparation method thereof ) 是由 潘安强 柴思敏 于 2020-12-21 设计创作，主要内容包括：本发明公开了一种电化学性能稳定的由纳米纤维相互搭建的生物基凝胶聚合物电解质及其制备方法,所述的膜骨架为：PAN和PLLA两者共混纳米纤维膜或者PAN、PLLA和CS三者的共混纳米纤维膜；PAN和PLLA两者共混纳米纤维膜中,PAN和PLLA的质量比为(1～7):1；PAN、PLLA和CS三者的共混纳米纤维膜中,PAN和PLLA的质量比为(2～4):1,CS与PLLA的摩尔比为(2～3.5):1。本发明中纳米纤维膜采用的多种聚合物,利用多种聚合物之间性能的互补,使得制备的聚合物膜具有更好的电化学性能。(The invention discloses a bio-based gel polymer electrolyte with stable electrochemical performance and built by nano-fibers and a preparation method thereof, wherein the membrane skeleton comprises the following components: a blend nanofiber membrane of both PAN and PLLA or a blend nanofiber membrane of PAN, PLLA and CS; in the PAN and PLLA blended nanofiber membrane, the mass ratio of PAN to PLLA is (1-7) to 1; in the blended nanofiber membrane containing PAN, PLLA and CS, the mass ratio of PAN to PLLA is (2-4): 1, and the molar ratio of CS to PLLA is (2-3.5): 1. The nanofiber membrane provided by the invention adopts various polymers, and the prepared polymer membrane has better electrochemical performance by utilizing the complementation of the performances of the various polymers.)

1. A membrane skeleton of a bio-based gel polymer electrolyte, characterized in that the membrane skeleton is: a blend nanofiber membrane of both PAN and PLLA or a blend nanofiber membrane of PAN, PLLA and CS; in the PAN and PLLA blended nanofiber membrane, the mass ratio of PAN to PLLA is (1-7) to 1; in the blended nanofiber membrane containing PAN, PLLA and CS, the mass ratio of PAN to PLLA is (2-4): 1, and the molar ratio of CS to PLLA is (2-3.5): 1.

2. The method for preparing a membrane scaffold of a bio-based gel polymer electrolyte according to claim 1, comprising the steps of:

1) preparation of PAN solution: dissolving PAN powder in a solvent, and dissolving the PAN powder completely at a set temperature and a stirring speed to obtain a PAN solution;

2) preparation of PAN/PLLA solutions: adding PLLA into the PAN solution obtained in the step 1) according to the mass ratio of PAN to PLLA, and dissolving at a set temperature to obtain a PAN/PLLA blended solution

2') preparation of PAN/P (LLA-CS) solution: adding PLLA and CS into a DMF-oAC mixed solvent according to a set molar ratio, carrying out a crosslinking reaction under the condition of heating and stirring, and obtaining a P (LLA-CS) solution after the reaction is finished; mixing the PAN solution and the P (LLA-CS) solution in the step 1) according to the mass ratio of the PAN to the PLLA, and uniformly stirring at a set temperature to obtain a PAN/P (LLA-CS) solution;

3) preparation of a substrate for a bio-based gel polymer electrolyte: and (3) carrying out electrostatic spinning on the PAN/PLLA blended solution in the step 2) or the PAN/P (LLA-CS) solution in the step 2'), and drying after spinning is finished to obtain a PAN/PLLA blended nano-fiber membrane or a PAN/P (LLA-CS) blended nano-fiber membrane, wherein the obtained nano-fiber membrane is the membrane framework of the bio-based gel polymer electrolyte.

3. The method for preparing a membrane skeleton of a bio-based gel polymer electrolyte according to claim 2, wherein in the step 1), the solvent is N, N-dimethylformamide, the concentration of the PAN solution is 0.08-0.12 g/mL, the set temperature is 40-60 ℃, and the stirring speed is 600-800 r/min.

4. The method for preparing the membrane skeleton of the bio-based gel polymer electrolyte according to claim 2, wherein in the step 2), the temperature is set to be 40-60 ℃ and the stirring speed is 600-800 r/min.

5. The method for preparing a membrane skeleton of a bio-based gel polymer electrolyte according to claim 2, wherein in the step 2'), the DMF-oAC mixed solvent is glacial acetic acid added in an amount of 0.01 to 0.5% by volume relative to the total amount of DMF, based on the total amount of DMF solvents in the step 1) and the step 2); the concentration of PLLA in the mixed solvent is 0.05-0.07 g/mL.

6. The method for preparing the membrane skeleton of the bio-based gel polymer electrolyte according to claim 2, wherein in the step 2'), the temperature of heating and stirring is 120-180 ℃, the stirring speed is 200-300 r/min, and the crosslinking reaction time is 30-200 min; the set temperature is 50-80 ℃, the stirring speed is 600-800 r/min, and the stirring time is 12 h.

7. The method for preparing the membrane skeleton of the bio-based gel polymer electrolyte according to claim 2, wherein in the step 3), the electrostatic spinning process parameters are as follows: the injector used for electrostatic spinning is 10mL, the low voltage intensity is-0.1 kV, the high voltage intensity is 14-16 kV, and the injection speed is 0.065-0.085 mm/min; the electrospinning time is 10-13 h; the thickness of the electrostatic spinning membrane is 50-80 μm; the drying is vacuum drying, the drying temperature is 50-70 ℃, and the drying time is 10-14 h.

8. A preparation method of a bio-based gel polymer electrolyte comprises the following steps:

cutting the membrane skeleton of the bio-based gel polymer electrolyte prepared in claim 2 into a predetermined diameter, placing the membrane skeleton in a container, dropping LiTFSI (DOL: DME,1:1, v: v) absorbed by a dropper into an argon-filled glove box, infiltrating, swelling, and plasticizing, and then sucking off the excess electrolyte on the surface of the membrane by using filter paper to obtain the bio-based gel polymer electrolyte, and assembling the battery.

9. The method for preparing a bio-based gel polymer electrolyte according to claim 8, wherein the predetermined size is a circular disc with a diameter d of 19mm, the concentration of LiTFSI is 0.5-1.5M, and the soaking time is 10-14 h.

Technical Field

The invention belongs to the technical field of material chemistry, and particularly relates to a bio-based gel polymer electrolyte and a preparation method thereof.

Background

The ideal solid electrolyte has high ionic conductivity, excellent chemical and electrochemical stability and low synthesis cost, and compared with inorganic solid electrolyte, the gel polymer electrolyte has not only the good mechanical property of solid electrolyte but also the high ionic conductivity of liquid electrolyte. Lithium ions can therefore be transported in gel polymer electrolytes by means of both the movement of the polymer chains and the swollen gel or liquid phase. Gel polymers are considered to be the best candidates for replacement of commercial liquid electrolytes.

Polyacrylonitrile (PAN) is widely used for the construction of the backbone of the polymer electrolyte membrane due to its high ionic conductivity and electrochemical oxidation resistance, while the ionic conductivity of the gel polymer electrolyte constructed therefrom is about 10 at 298K^-3S cm^-1. However, CN groups in pure PAN are liable to react with the Li anode, and a "passivation layer" is formed between the Li metal cathode and the PAN electrolyte, resulting in increased interface impedance, hindered ion transport, and deteriorated electrochemical performance.

As a biodegradable high polymer material, the L-polylactic acid (PLLA) has good mechanical properties, flexible molecular chains and long degradable time, and becomes one of candidate materials of medical artificial frameworks. Meanwhile, PLLA is a high-polarity cellulose derivative, and has strong liquid electrolyte absorbability, and researches show that when polylactic acid is independently used as a matrix material of a polymer electrolyte framework, the electrochemical performance of the battery is poor due to the crystallization behavior of the polylactic acid.

Chitosan (CS) is obtained by deacetylating chitin widely existing in nature, and has-OH and-NH in the structure of natural polymer₂Two biological functional groups with good biocompatibility, safety, degradability and the like are widely used for biochemistryAnd biomedicine, food, chemical industry, water treatment, metal extraction and recovery and other fields. The molecular chain regularity of the single polymer matrix is good, so that the polymer film has certain crystallization behavior, the movement of the molecular chain is hindered, and the ionic conductivity cannot meet the application requirement.

The existing method for preparing the polymer electrolyte membrane skeleton mainly comprises a solution pouring method, an extraction activation method, a phase separation/inversion method and the like, wherein the solution pouring method is to pour a polymer into a specific mould after the polymer is dissolved in a conventional solvent for forming, and the solvent is difficult to be completely removed due to the solvation effect of lithium salt. The extraction activation method is that a plasticizer is added into a polymer solution system, and the plasticizer is removed by solvent extraction after casting film formation to obtain a polymer porous film, wherein the polymer porous film obtained by the method has uneven pore distribution; the phase separation/inversion method avoids the extraction process of the plasticizer, and the obtained polymer gel electrolyte has good electrochemical and mechanical properties, but the residual solvent can influence the electrochemical stability and safety of the battery.

Disclosure of Invention

The invention aims to provide a bio-based gel polymer electrolyte which is stable in electrochemical performance and is built by nano fibers and a preparation method thereof.

The membrane skeleton of the bio-based gel polymer electrolyte provided by the invention is as follows: a blend nanofiber membrane of both PAN and PLLA or a blend nanofiber membrane of PAN, PLLA and CS; in the PAN and PLLA blended nanofiber membrane, the mass ratio of PAN to PLLA is (1-7) to 1; in the blended nanofiber membrane containing PAN, PLLA and CS, the mass ratio of PAN to PLLA is (2-4): 1, and the molar ratio of CS to PLLA is (2-3.5): 1.

The preparation method of the membrane skeleton of the bio-based gel polymer electrolyte comprises the following steps:

1) preparation of PAN solution: dissolving PAN powder in a solvent, and dissolving the PAN powder completely at a set temperature and a stirring speed to obtain a PAN solution;

2) preparation of PAN/PLLA solutions: adding PLLA into the PAN solution obtained in the step 1) according to the mass ratio of PAN to PLLA, and dissolving at a set temperature to obtain a PAN/PLLA blended solution

2') preparation of PAN/P (LLA-CS) solution: adding PLLA and CS into a DMF-oAC mixed solvent according to a set molar ratio, carrying out a crosslinking reaction under the condition of heating and stirring, adding the obtained P (LLA-CS) crosslinking solution into the PAN solution obtained in the step 1) when the reaction is finished, and uniformly stirring at a set temperature to obtain a PAN/P (LLA-CS) co-crosslinking solution;

3) preparation of a substrate for a bio-based gel polymer electrolyte: and (3) carrying out electrostatic spinning on the PAN/PLLA blended solution in the step 2) or the PAN/P (LLA-CS) solution in the step 2'), and drying after spinning is finished to obtain a PAN/PLLA blended nano-fiber membrane or a PAN/P (LLA-CS) blended nano-fiber membrane, wherein the obtained nano-fiber membrane is the membrane framework of the bio-based gel polymer electrolyte.

In the step 1), the solvent is N, N-dimethylformamide, the concentration of the PAN solution is 0.08-0.12 g/mL, the set temperature is 40-60 ℃, and the stirring speed is 600-800 r/min.

In the step 2), the set temperature is 40-60 ℃, and the stirring speed is 600-800 r/min.

In the step 2 '), the DMF-oAC mixed solvent is prepared by adding a corresponding amount of DMF according to the volume ratio of 50% of DMF in the step 1), and adding glacial acetic acid accounting for 0.01-0.5% of the total volume of DMF based on the total amount of DMF solvents in the step 1) and the step 2'); adding PLLA into a mixed solvent according to the mass ratio of PAN to PLLA (2-4): 1, wherein the concentration of the PLLA in the mixed solvent is 0.05-0.07 g/mL, and the molar ratio of chitosan to PLLA is n_PLLA:n_CS＝1:(1.5～3.5)。

In the step 2'), the heating and stirring temperature of the PLLA and the CS is 120-180 ℃, the stirring speed is 200-300 r/min, and the crosslinking reaction time is 30-200 min; the mixing set temperature of the PAN and the PLLA-CS is 50-80 ℃, the stirring speed is 600-800 r/min, and the stirring time is 12 h.

In the step 3), the electrostatic spinning process parameters are as follows: the injector used for electrostatic spinning is 10mL, the low voltage intensity is-0.1 kV, the high voltage intensity is 14-16 kV, and the injection speed is 0.065-0.085 mm/min; the electrospinning time is 10-13 h; the thickness of the electrostatic spinning membrane is 50-80 μm; the drying is vacuum drying, the drying temperature is 50-70 ℃, and the drying time is 10-14 h.

The preparation method of the bio-based gel polymer electrolyte comprises the following steps:

cutting the prepared membrane skeleton of the bio-based gel polymer electrolyte into a size with a set diameter, placing the membrane skeleton in a container, dripping LiTFSI (DOL: DME,1:1, v: v) absorbed by a dropper in a glove box filled with argon on the membrane skeleton, infiltrating, swelling and plasticizing, and completely absorbing the redundant electrolyte on the surface of the membrane by using filter paper to obtain the bio-based gel polymer electrolyte, and assembling the battery.

The set size is a wafer with the diameter d of 19mm, the concentration of the LiTFSI is 0.5-1.5M, and the soaking time is 10-14 h.

The molecular weight of the PAN is 140000-160000 g/mol; the molecular weight of PLLA is 40000-60000 g/mol; the molecular weight of CS is 116.28 g/mol.

The principle of the invention is as follows: the CN group of the pure PAN film is easy to react with the Li anode, and a 'passivation layer' is formed between the Li metal cathode and the PAN electrolyte, so that the interface impedance is increased, the ion transport is blocked, and the electrochemical performance is deteriorated. In the polymer electrolyte membrane, PLLA or P (LLA-CS) is introduced on the basis of PAN, and an electron-withdrawing group hydroxyl in the PLLA can form an intermolecular hydrogen bond with a CN group in the PAN, so that the passivation effect generated by pure PAN is reduced, and the stability of a battery is improved. CS is further introduced into P (LLA-CS), and the introduction of CS can have a crosslinking reaction with PLLA, so that a polymer system has lower crystallinity, the movement of a molecular chain segment is improved, and the ionic conductivity of the gel polymer electrolyte is further improved.

The invention has the beneficial effects that: 1) the invention adopts an electrostatic spinning method to prepare PAN/PLLA or P (LLA-CS) blended polymer skeleton membrane, the porous polymer membrane is formed by mutually lapping nano fibers, the formed pores can provide good ion channels, and the nano fibers are also easily activated and gelatinized by liquid electrolyte, and simultaneously, the method can effectively regulate and control the fine structure of the fibers. The prepared PAN/PLLA blended polymer electrolyte has the advantages of uniform distribution of the thickness of a skeleton film and the diameter size of fibers, good non-crystallinity, economy and environmental protection, and the gel polymer electrolyte prepared by the skeleton film has good stability, strong practicability and good industrialization prospect. 2) The nanofiber membrane provided by the invention adopts various polymers, and the prepared polymer membrane has better electrochemical performance by utilizing the complementation of the performances of the various polymers.

Drawings

FIG. 1 is an XRD pattern of a PAN/PLLA polymer film prepared in example 1 of the invention.

FIG. 2 is a FTIR plot of PAN/PLLA polymer films prepared in example 1 of the present invention.

FIG. 3 is a graph of the cycling performance at 5C current density for a cell assembled with a PAN/PLLA polymer membrane prepared in example 1 of the invention.

FIG. 4 is an XRD pattern of PAN/P (LLA-CS) polymer film prepared according to example 6 of the present invention.

FIG. 5 is an SEM image of a PAN/P (LLA-CS) polymer membrane prepared in example 6 of the present invention.

FIG. 6 is a LSV diagram of PAN/P (LLA-CS) gel polymer electrolyte prepared in example 6 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by those skilled in the art without any creative work based on the embodiments of the present invention belong to the protection scope of the present invention.

In this example, unless otherwise specified, the chemical reagents used were analytical reagents, all of which were common commercial products or prepared by conventional means, and the equipment used was conventional in the art, and the following are some examples of the inventors in the experiment:

the molecular weight of PAN in the examples of the present invention was 150000 g/mol; the molecular weight of PLLA is 50000 g/mol; the molecular weight of CS is 116.28 g/mol.

Example 1

The preparation method of the PAN/PLLA bio-based gel polymer electrolyte provided by the invention comprises the following steps:

(1) weighing a certain amount of PAN powder, adding into 10ml of N, N-dimethylformamide solvent, stirring at 50 ℃ and 700r/min until the PAN powder is completely dissolved to obtain C_PAN0.08g/mL of a light yellow transparent solution;

(2) according to m_PAN:m_PLLAWeighing PLLA powder according to the mass ratio of 3:1, adding the PLLA powder into the PAN solution obtained in the step (1), stirring the mixture at the temperature of 50 ℃ and the speed of 700r/min until the mixture is completely dissolved, and continuously stirring the mixture for 12 hours under the condition;

(3) adding the PAN/PLLA blended homogeneous solution obtained in the step (2) into a 10ml syringe, injecting under the conditions of low voltage of-0.1 kV and high voltage of 15kV, and carrying out electrostatic spinning at the injection speed of 0.065mm/min for 10 h;

(4) putting the PAN/PLLA blended polymer skeleton membrane obtained in the step (3) into a vacuum drying oven for vacuum drying for 12h at the temperature of 60 ℃, wherein the thickness of the PAN/PLLA polymer skeleton membrane obtained after drying is 50 mu m; cutting the film into a circular sheet with the diameter d being 19mm by a slicer for later use;

(5) drying the PAN/PLLA blended wafer obtained in the step (4) at 60 ℃ in vacuum for 5h, removing water, putting the dried PAN/PLLA blended wafer into an argon-filled glove box, keeping the water/oxygen partial pressure to be less than 0.1ppm, sucking 0.3ml of 1M LiTFSI (DOL: DME,1:1, v: v) by using a dropper, adding the 1M LiTFSI into a container for placing a PAN/PLLA blended polymer skeleton film, and infiltrating for plasticizing for 12 h;

(6) and (4) completely sucking the redundant electrolyte on the surface of the PAN/PLLA gel polymer electrolyte obtained in the step (5) by using filter paper, and assembling the battery.

FIG. 1 is an XRD pattern of the PAN/PLLA polymer film prepared in example 1, from which it can be seen that the blend product PAN/PLLA has a strong disorder degree, which is favorable for the migration of lithium ions; FIG. 2 is a FTIR spectrum of PAN/PLLA polymer film prepared in example 1, from which it can be seen that the resulting polymer film was at 1750cm^-1And 2245cm^-1the-C ═ O peak and the-C ≡ N peak appear at the same time at 3000-3400cm^-1A hydrogen bond peak appears, which indicates that PAN and PLA are combined by a hydrogen bond functional group; FIG. 2 is a PAN/PLLA gel polymer prepared in example 1The cycle performance map of the full battery assembled by the electrolyte and the lithium iron phosphate under the current density of 5C shows that the battery assembled by the electrolyte has better cycle stability, and the charge-discharge capacity is still 136.09mA h g after 250 cycles^-1. When pure PAN is used as an electrolyte framework, the battery capacity is rapidly attenuated after 50 times of circulation, and the charge-discharge capacity is only 89.67mA h g after 250 times of circulation^-1。

Example 2

The preparation method of the PAN/PLLA bio-based gel polymer electrolyte provided by the invention comprises the following steps:

(1) weighing a certain amount of PAN powder, adding into 10ml of N, N-dimethylformamide solvent, stirring at 50 ℃ and 700r/min until the PAN powder is completely dissolved to obtain C_PAN0.08g/mL of a light yellow transparent solution;

(2) according to m_PAN:m_PLLAWeighing PLLA powder according to the mass ratio of 7:1, adding the PLLA powder into the PAN solution obtained in the step (1), stirring the mixture at the temperature of 50 ℃ and the speed of 700r/min until the PLLA powder is completely dissolved, and continuously stirring the mixture for 12 hours under the condition;

(3) adding the PAN/PLLA blended homogeneous solution obtained in the step (2) into a 10ml syringe, injecting under the conditions of low voltage of-0.1 kV and high voltage of 15kV, and carrying out electrostatic spinning at the injection speed of 0.007mm/min for 11 h;

(4) putting the PAN/PLLA blended polymer skeleton membrane obtained in the step (3) into a vacuum drying oven for vacuum drying for 12h at the temperature of 60 ℃, wherein the thickness of the PAN/PLLA polymer skeleton membrane obtained after drying is 55 mu m; cutting the film into a circular sheet with the diameter d being 19mm by a slicer for later use;

(5) drying the PAN/PLLA blended wafer obtained in the step (4) at 60 ℃ in vacuum for 5h, removing water, putting the dried PAN/PLLA blended wafer into an argon-filled glove box, keeping the water/oxygen partial pressure to be less than 0.1ppm, sucking 0.3ml of 1M LiTFSI (DOL: DME,1:1, v: v) by using a dropper, adding the 1M LiTFSI into a container for placing a PAN/PLLA blended polymer skeleton film, and infiltrating for plasticizing for 12 h;

(6) and (4) completely sucking the redundant electrolyte on the surface of the PAN/PLLA gel polymer electrolyte obtained in the step (5) by using filter paper, and assembling the battery.

Example 3

The preparation method of the PAN/PLLA bio-based gel polymer electrolyte provided by the invention comprises the following steps:

(1) weighing a certain amount of PAN powder, adding into 10ml of N, N-dimethylformamide solvent, stirring at 50 ℃ and 700r/min until the PAN powder is completely dissolved to obtain C_PAN0.10g/mL of a light yellow transparent solution;

(2) according to m_PAN:m_PLLAWeighing PLLA powder according to the mass ratio of 5:1, adding the PLLA powder into the PAN solution obtained in the step (1), stirring the mixture at the temperature of 50 ℃ and the speed of 700r/min until the PLLA powder is completely dissolved, and continuously stirring the mixture for 12 hours under the condition;

(3) adding the PAN/PLLA blending homogeneous solution obtained in the step (2) into a 10ml injector, and injecting under the conditions of low voltage of-0.1 kV and high voltage of 15kV, wherein the injection speed is 0.007mm/min for electrostatic spinning; the electrospinning time is 12 h;

(4) putting the PAN/PLLA blended polymer skeleton membrane obtained in the step (3) into a vacuum drying oven for vacuum drying for 12 hours at the temperature of 60 ℃, wherein the thickness of the PAN/PLLA polymer skeleton membrane obtained after drying is 65 mu m; cutting the film into a circular sheet with the diameter d being 19mm by a slicer for later use;

(5) drying the PAN/PLLA blended wafer obtained in the step (4) at 60 ℃ in vacuum for 5h, removing water, putting the dried PAN/PLLA blended wafer into an argon-filled glove box, keeping the water/oxygen partial pressure to be less than 0.1ppm, sucking 0.3ml of 1M LiTFSI (DOL: DME,1:1, v: v) by using a dropper, adding the 1M LiTFSI into a container for placing a PAN/PLLA blended polymer skeleton film, and infiltrating for plasticizing for 12 h;

(6) and (4) completely sucking the redundant electrolyte on the surface of the PAN/PLLA gel polymer electrolyte obtained in the step (5) by using filter paper, and assembling the battery.

Example 4

The preparation method of the PAN/PLLA bio-based gel polymer electrolyte provided by the invention comprises the following steps:

(1) weighing a certain amount of PAN powder, adding into 10ml of N, N-dimethylformamide solvent, stirring at 50 ℃ and 700r/min until the PAN powder is completely dissolved to obtain C_PAN0.10g/mL of a light yellow transparent solution;

(2) according to m_PAN：m_PLLA＝3：1, adding PLLA powder weighed according to the mass ratio of the PLLA powder into the PAN solution obtained in the step (1), stirring the mixture at the temperature of 50 ℃ and the speed of 700r/min until the mixture is completely dissolved, and continuously stirring the mixture for 12 hours under the condition;

(3) adding the PAN/PLLA blending homogeneous solution obtained in the step (2) into a 10ml injector, injecting under the conditions of low voltage of-0.1 kV and high voltage of 15kV, and carrying out electrostatic spinning under the condition that the injection speed is 0.07 mm/min; the electrospinning time is 12 h;

(4) putting the PAN/PLLA blended polymer skeleton membrane obtained in the step (3) into a vacuum drying oven for vacuum drying for 12 hours at the temperature of 60 ℃, wherein the thickness of the PAN/PLLA polymer skeleton membrane obtained after drying is 65 mu m; cutting the film into a circular sheet with the diameter d being 19mm by a slicer for later use;

(5) drying the PAN/PLLA blended wafer obtained in the step (4) at 60 ℃ in vacuum for 5h, removing water, putting the dried PAN/PLLA blended wafer into an argon-filled glove box, keeping the water/oxygen partial pressure to be less than 0.1ppm, sucking 0.3ml of 1M LiTFSI (DOL: DME,1:1, v: v) by using a dropper, adding the 1M LiTFSI into a container for placing a PAN/PLLA blended polymer skeleton film, and infiltrating for plasticizing for 12 h;

(6) and (4) completely sucking the redundant electrolyte on the surface of the PAN/PLLA gel polymer electrolyte obtained in the step (5) by using filter paper, and assembling the battery.

Example 5

The preparation method of the PAN/PLLA bio-based gel polymer electrolyte provided by the invention comprises the following steps:

(1) weighing a certain amount of PAN powder, adding into 10ml of N, N-dimethylformamide solvent, stirring at 50 ℃ and 700r/min until the PAN powder is completely dissolved to obtain C_PAN0.12g/mL of a light yellow transparent solution;

(2) according to m_PAN：m_PLLA1:1, adding PLLA powder weighed according to the mass ratio of the PLLA powder into the PAN solution obtained in the step (1), stirring the mixture at the temperature of 50 ℃ and the speed of 700r/min until the mixture is completely dissolved, and continuously stirring the mixture for 12 hours under the condition;

(3) adding the PAN/PLLA blending homogeneous solution obtained in the step (2) into a 10ml injector, injecting under the conditions of low voltage of-0.1 kV and high voltage of 15kV, and carrying out electrostatic spinning under the condition that the injection speed is 0.075 mm/min; the electrospinning time is 13 h;

(4) putting the PAN/PLLA blended polymer skeleton membrane obtained in the step (3) into a vacuum drying oven for vacuum drying for 12h at the temperature of 60 ℃, wherein the thickness of the PAN/PLLA polymer skeleton membrane obtained after drying is 80 mu m; cutting the film into a circular sheet with the diameter d being 19mm by a slicer for later use;

(5) drying the PAN/PLLA blended wafer obtained in the step (4) at 60 ℃ in vacuum for 5h, removing water, putting the dried PAN/PLLA blended wafer into an argon-filled glove box, keeping the water/oxygen partial pressure to be less than 0.1ppm, sucking 0.3ml of 1M LiTFSI (DOL: DME,1:1, v: v) by using a dropper, adding the 1M LiTFSI into a container for placing a PAN/PLLA blended polymer skeleton film, and infiltrating for plasticizing for 12 h;

(6) and (4) completely sucking the redundant electrolyte on the surface of the PAN/PLLA gel polymer electrolyte obtained in the step (5) by using filter paper, and assembling the battery.

Example 6

The invention provides a preparation method of PAN/P (LLA-CS) bio-based gel polymer electrolyte, which comprises the following steps:

(1) adding 10ml of N, N-Dimethylformamide (DMF) solvent into a beaker, weighing 0.9g of PAN powder, adding the PAN powder into the DMF solvent, and stirring at 50 ℃ and 700r/min until the PAN powder is completely dissolved to obtain a PAN solution;

(2) adding 5ml of N, N-Dimethylformamide (DMF) solvent into a 10ml serum bottle, measuring glacial acetic acid (oAC) solution with the corresponding volume according to the percentage of 0.01 percent of the total volume of the DMF added in the steps (1) and (2), and adding the glacial acetic acid solution into the serum bottle to obtain a DMF-oAC mixed solvent;

(3) according to n_CS:n_PLLAMolar ratio of 2:1, m_PAN：m_PLLA3:1, respectively weighing chitosan and polylactic acid powder with corresponding mass, adding the chitosan and the polylactic acid powder into a DMF-oAC mixed solvent, wherein the concentration of PLLA in the mixed solvent is 0.06g/mL, adding the PLLA into the mixed solvent according to the mass ratio of PAN to PLLA of 3:1, the concentration of PLLA in the mixed solvent is 0.06g/mL, and the molar ratio of the added chitosan to the PLLA is n_PLLA:n_CSStirring in oil bath at 120 ℃ and 250r/min for 30min to obtain a P (LLA-CS) solution for crosslinking reaction, wherein the ratio of the P to the LLA to the CS is 1: 3.5;

(4) adding the P (LLA-CS) solution obtained in the step (3) into the PAN solution obtained in the step (1) while the solution is hot, stirring the solution at 50 ℃ at 700r/min until the solution is completely dissolved, and then continuously stirring the solution for 12 hours to obtain a cross-linked precursor solution;

(5) adding the crosslinking precursor solution obtained in the step (4) into a 10ml injector, and injecting under the conditions of low voltage of-0.1 kV and high voltage of 15kV, wherein the injection speed is 0.065mm/min for electrostatic spinning; the electrospinning time is 10 h;

(6) vacuum drying the PAN/P (LLA-CS) polymer film obtained in the step (5) at 60 ℃ for 12h, wherein the thickness of the polymer film is 50 mu m; cutting into a circular piece with the diameter d being 19mm, sucking 0.3ml of 1M LiTFSI (DOL: DME,1:1, v: v) in an argon-filled glove box by a dropper, adding the circular piece into a container for placing the PAN/P (LLA-CS) polymer film, soaking for 12h, swelling and plasticizing, and sucking the redundant electrolyte on the surface of the PAN/P (LLA-CS) polymer electrolyte by filter paper to assemble the battery.

FIG. 4 is an XRD pattern of the PAN/P (LLA-CS) polymer film prepared in example 6, from which it can be seen that the PAN/P (LLA-CS) polymer film has a low crystallinity behavior, indicating that the polymer film has a strong disordered structure, which facilitates the migration of lithium ions in the polymer film; FIG. 5 is an SEM image of PAN/P (LLA-CS) polymer film prepared in example 6, from which it can be seen that the polymer film is formed by the staggered stacking of nanofibers, but spherical particles with non-uniform size are present in the nanofibers, and may be incompletely reacted chitosan, indicating that the reaction of chitosan with polylactic acid is insufficient under the temperature condition; fig. 6 is a LSV diagram of PAN/P (LLA-CS) gel polymer electrolyte prepared in example 6, and it can be seen from the diagram that the electrochemical stability window of the gel polymer electrolyte reaches 5.29V, indicating that the electrolyte can be used for matching of high voltage positive electrode materials.

Example 7

The invention provides a preparation method of PAN/P (LLA-CS) bio-based gel polymer electrolyte, which comprises the following steps:

(1) adding 10ml of N, N-Dimethylformamide (DMF) solvent into a beaker, weighing 0.9g of PAN powder, adding the PAN powder into the DMF solvent, and stirring at 50 ℃ and 700r/min until the PAN powder is completely dissolved to obtain a PAN solution;

(2) adding 5ml of N, N-Dimethylformamide (DMF) solvent into a 10ml serum bottle, measuring glacial acetic acid (oAC) solution with the corresponding volume according to the percentage of 0.2 percent of the total volume of the DMF added in the steps (1) and (2), and adding the glacial acetic acid solution into the serum bottle to obtain a DMF-oAC mixed solvent;

(3) according to n_CS:n_PLLAMolar ratio of 2.5:1, m_PAN：m_PLLA3:1, respectively weighing chitosan and polylactic acid powder with corresponding mass, adding the chitosan and the polylactic acid powder into a DMF-oAC mixed solvent, wherein the PLLA concentration is 0.06g/mL, and carrying out oil bath stirring for 30-200 min under the conditions of 160 ℃ and 250r/min to obtain a P (LLA-CS) solution for crosslinking reaction;

(4) adding the P (LLA-CS) solution obtained in the step (3) into the PAN solution obtained in the step (1) while the solution is hot, stirring the solution at 70 ℃ at 700r/min until the solution is completely dissolved, and then continuously stirring the solution for 12 hours to obtain a cross-linked precursor solution;

(5) adding the mixed solution obtained in the step (4) into a 10ml injector, injecting under the conditions of low voltage of-0.1 kV and high voltage of 15kV, and carrying out electrostatic spinning under the condition that the injection speed is 0.07 mm/min; the electrospinning time is 11 h;

(6) vacuum drying the PAN/P (LLA-CS) polymer film obtained in the step (5) at 60 ℃ for 12h, wherein the thickness of the polymer film is 60 mu m; cutting into a circular piece with the diameter d being 19mm, sucking 0.5ml of 1M LiTFSI (DOL: DME,1:1, v: v) in an argon-filled glove box by a dropper, adding the circular piece into a container for placing the PAN/P (LLA-CS) polymer film, soaking for 12h, swelling and plasticizing, and sucking the redundant electrolyte on the surface of the PAN/P (LLA-CS) polymer electrolyte by filter paper to assemble the battery.

Example 8

The invention provides a preparation method of PAN/P (LLA-CS) bio-based gel polymer electrolyte, which comprises the following steps:

(1) adding 10ml of N, N-Dimethylformamide (DMF) solvent into a beaker, weighing 0.9g of PAN powder, adding the PAN powder into the DMF solvent, and stirring at 50 ℃ and 700r/min until the PAN powder is completely dissolved to obtain a PAN solution;

(2) adding 5ml of N, N-Dimethylformamide (DMF) solvent into a 10ml serum bottle, and adding glacial acetic acid (oAC) solution with the corresponding volume which is 0.5 percent of the total volume of the DMF added in the steps (1) and (2) into the serum bottle to obtain a DMF-oAC mixed solvent;

(3) according to n_CS:n_PLLAMolar ratio of 3.5:1, m_PAN:m_PLLARespectively weighing chitosan and polylactic acid powder with corresponding mass according to the mass ratio of 3:1, adding the chitosan and the polylactic acid powder into a DMF-oAC mixed solvent, wherein the PLLA concentration is 0.06g/mL, and carrying out oil bath stirring for 200min at 180 ℃ and 250r/min to obtain a P (LLA-CS) solution for crosslinking reaction;

(4) adding the P (LLA-CS) solution obtained in the step (3) into the PAN solution obtained in the step (1) while the solution is hot, stirring the solution at 70 ℃ at 700r/min until the solution is completely dissolved, and then continuously stirring the solution for 12 hours to obtain a cross-linked precursor solution;

(5) adding the mixed solution obtained in the step (4) into a 10ml injector, and injecting under the conditions of low voltage of-0.1 kV and high voltage of 15kV, wherein the injection speed is 0.085mm/min for electrostatic spinning; the electrospinning time is 12 h;

(6) vacuum drying the PAN/P (LLA-CS) polymer film obtained in the step (5) at 60 ℃ for 12h, wherein the thickness of the polymer film is 80 mu m; cutting into a circular piece with the diameter d being 19mm, sucking 0.8ml of 1M LiTFSI (DOL: DME,1:1, v: v) in an argon-filled glove box by a dropper, adding the circular piece into a container for placing the PAN/P (LLA-CS) polymer film, soaking for 12h, swelling and plasticizing, and sucking the redundant electrolyte on the surface of the PAN/P (LLA-CS) polymer electrolyte by filter paper to assemble the battery.

The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-described embodiments. Modifications and variations that may occur to those skilled in the art without departing from the spirit and scope of the invention are to be considered as within the scope of the invention.