CN110212156B - Flexible electrode, preparation method and flexible lithium ion battery - Google Patents

Flexible electrode, preparation method and flexible lithium ion battery Download PDF

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CN110212156B
CN110212156B CN201910468736.4A CN201910468736A CN110212156B CN 110212156 B CN110212156 B CN 110212156B CN 201910468736 A CN201910468736 A CN 201910468736A CN 110212156 B CN110212156 B CN 110212156B
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flexible
electrode
active material
black tea
conductive agent
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CN110212156A (en
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邓永红
杜磊磊
韩兵
王军
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Nayuan New Material Technology Wuxi Co ltd
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Southwest University of Science and Technology
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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Abstract

The invention relates to the technical field of flexible lithium ion batteries, and particularly provides a flexible electrode, a preparation method of the flexible electrode and a flexible lithium ion battery. The flexible electrode is a flexible positive electrode or a flexible negative electrode, and the flexible positive electrode and/or the flexible negative electrode comprise a flexible bacterial membrane with a three-dimensional network structure, a conductive agent and an active material, wherein the conductive agent and the active material are filled and combined in the three-dimensional network structure of the flexible bacterial membrane. According to the flexible electrode, the active material, the conductive agent and the flexible bacterial membrane are tightly combined to form a whole, so that the electrode has inherent flexibility of the bacterial membrane, the falling-off of the active material and the conductive agent can be inhibited, the stability of the electrode is improved when the flexible electrode is assembled into a lithium ion battery, the electrochemical performance of the battery is improved, and the commercial application of the flexible lithium ion battery is promoted.

Description

Flexible electrode, preparation method and flexible lithium ion battery
Technical Field
The invention belongs to the technical field of flexible lithium ion batteries, and particularly relates to a flexible electrode, a preparation method of the flexible electrode and a flexible lithium ion battery.
Background
With the development of wearable device technology, flexible electronic devices required by wearable devices and the like are gradually developed towards flexibility, and how to develop a lithium ion battery with ultrahigh flexibility has become one of research hotspots in the field of energy storage. The research of the flexible lithium ion battery at present mainly uses a flexible substrate as a load body, and active materials are combined on the surface of the load body in the modes of coating, suction filtration, extrusion and the like, the modes can reduce the bending property of a flexible base material, and the prepared electrode active materials are easy to fall off, so that the performance of the obtained product is poor.
In the prior art, nano-cellulose is used as a base material, and a filter pressing method is adopted to prepare a flexible self-supporting film from a mixed solution of molybdenum disulfide nanosheets, nano-cellulose, graphene and carbon nanotubes, but the method destroys the flexibility and mechanical properties of the nano-cellulose, thereby affecting the overall flexibility of the flexible battery.
And coating the active material on the conductive film by using the conductive film as an electrode current collector in a coating mode, thereby obtaining the flexible electrode. However, the flexible electrode obtained by the method has low surface density and is easy to fall off in the bending process, so that the performance of the battery is rapidly reduced and even the battery is scrapped.
Disclosure of Invention
The invention provides a flexible electrode and a preparation method thereof, aiming at the problems that an electrode material of the existing flexible battery is easy to fall off, poor in flexibility performance, low in surface density, easy to cause falling off by bending and the like.
Further, the invention also provides a flexible lithium ion battery comprising the flexible electrode.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a flexible electrode which is a flexible positive electrode or a flexible negative electrode, wherein the flexible positive electrode and/or the flexible negative electrode comprises a flexible mycoderm with a three-dimensional network structure, a conductive agent and an active material, wherein the conductive agent and the active material are filled and combined in the three-dimensional network structure of the flexible mycoderm.
Correspondingly, the preparation method of the flexible electrode comprises the following steps:
providing a culture solution containing black tea, high-purity water and glucose;
adding an active material, a conductive agent and a black tea fungus strain into the culture solution, and mixing until the active material, the conductive agent and the black tea fungus strain are uniformly dispersed to obtain a flexible electrode growth solution;
standing and culturing the growth solution of the flexible electrode at a constant temperature of 25-35 ℃ to obtain a mycoderm containing an active material and a conductive agent;
and removing impurities from the bacterial membrane, cleaning, and freeze-drying to obtain the flexible electrode.
Further, a flexible lithium ion battery comprises a positive electrode and a negative electrode, wherein the positive electrode is the flexible electrode or the flexible electrode prepared by the preparation method of the flexible electrode; and/or the negative electrode is the flexible electrode or the flexible electrode prepared by the preparation method of the flexible electrode.
The invention has the technical effects that:
compared with the prior art, the flexible electrode provided by the invention has the advantages that the active material and the conductive agent are filled and combined in the flexible bacterial membrane with the three-dimensional net structure, and the active material, the conductive agent and the flexible bacterial membrane are tightly combined to form a whole, so that the electrode has the inherent flexibility of the bacterial membrane, the falling-off of the active material and the conductive agent can be inhibited, and the stability of the electrode is improved when the electrode is assembled into a lithium ion battery, so that the electrochemical performance of the battery is improved.
The preparation method of the flexible electrode has the advantages of cheap and easily-obtained raw materials and simple preparation process, and ensures that the active material and the conductive agent are uniformly filled in the generated mycoderm in a co-growth mode, thereby being beneficial to improving the bonding strength of the active material, the conductive agent and the mycoderm and ensuring that the active material in the flexible electrode is not easy to fall off.
Compared with the existing flexible battery, the flexible lithium ion battery has the advantages that the positive electrode and the negative electrode are the flexible electrodes obtained by the method, so that the lithium ion battery has good flexibility, the active material is not easy to fall off from the electrodes, and the electrochemical energy of the lithium ion battery is greatly improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is an SEM image of a lithium titanate electrode prepared by the preparation method of the flexible electrode in the embodiment 1-4 of the invention;
fig. 2 is an SEM image of a flexible lithium ion battery assembled by a lithium iron phosphate electrode (as a positive electrode), a black tea fungus membrane (as a diaphragm), and a lithium titanate electrode (as a negative electrode) prepared by a method for preparing a flexible electrode according to example 5 of the present invention;
fig. 3 is a cycle curve and coulombic efficiency of a lithium ion battery assembled by the lithium titanate electrode obtained in example 1 of the present invention;
fig. 4 is a cycle curve and coulombic efficiency of the flexible lithium ion battery assembled in example 2 of the present invention;
fig. 5 is a cycle curve and coulombic efficiency of the assembled flexible lithium ion battery of example 3 of the present invention;
fig. 6 is a cycle curve and coulombic efficiency of the flexible lithium ion battery assembled in example 4 of the present invention;
fig. 7 shows the cycle curve and coulombic efficiency of the flexible lithium ion battery assembled in example 5 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention provides a preparation method of a flexible electrode.
Specifically, the preparation method of the flexible electrode comprises the following steps:
providing a culture solution containing black tea, high-purity water and glucose;
adding an active material, a conductive agent and a black tea fungus strain into the culture solution, and mixing until the active material, the conductive agent and the black tea fungus strain are uniformly dispersed to obtain a flexible electrode growth solution;
standing and culturing the growth solution of the flexible electrode at a constant temperature of 25-35 ℃ to obtain a mycoderm containing an active material and a conductive agent;
and removing impurities from the bacterial membrane, cleaning, and freeze-drying to obtain the flexible electrode.
The above preparation method is explained in detail below:
the culture solution comprises black tea, high-purity water and glucose, wherein the black tea contains trace elements and nitrogen sources required by the growth of mycoderm. Glucose is used as a carbon source, and high-purity water is used as a solvent and water.
Preferably, in the culture solution, the components are black tea: high purity water: glucose (2-5): (400-600): (40-60). For example, the black tea can be: high purity water: the glucose is 3:500:50, so that the concentration of the culture solution is not too high, the flowing of the culture solution is facilitated, the active materials and the conductive agents are convenient to add, and meanwhile, the growth of a mycoderm is facilitated.
According to the mass ratio, the feeding proportion of the active material, the conductive agent and the culture solution is (90-95): (5-10): (2212-5525). The preparation method of the flexible electrode can be used for preparing a flexible positive electrode and a flexible negative electrode, so that the corresponding active material and the conductive agent of the electrode can be added according to the preparation requirement in the preparation process.
Specifically, when the prepared flexible electrode is a flexible positive electrode, the added active material is selected from any one of lithium iron phosphate, lithium cobaltate and ternary materials, and the added conductive agent can be graphene, carbon nanotubes, conductive carbon black and the like. The mass ratio of the active material to the conductive agent is (90-95): (5-10).
When the prepared flexible electrode is a flexible negative electrode, the added active material is selected from any one of lithium titanate, natural graphite, a silicon-based material, a tin-based material and a metal oxide. The added conductive agent can be graphene, carbon nanotubes, conductive carbon black and the like. The mass ratio of the active material to the conductive agent is (90-95): (5-10).
In the specific adding process, the active material, the conductive agent and the culture solution can be mixed and ultrasonically dispersed to obtain the dispersion solution, and then the black tea fungus strain is added, or the active material, the conductive agent and the black tea fungus strain can be directly added into the culture solution at the same time.
The purpose of the ultrasonic dispersion is mainly to uniformly disperse the active material and the conductive agent in the culture solution, so that the obtained flexible electrode active material and the conductive agent are uniformly dispersed.
The black tea fungus strain can be added in a black tea fungus liquid mode, and the mass concentration of the black tea fungus in the added black tea fungus liquid is 5% -30%. Preferably, the adding amount of the black tea fungus liquid is 50-150% of the culture solution.
During the culture process, nutrients, such as glucose or black tea, can be added to the culture medium as appropriate according to the growth of the mycoderm to ensure that the growth of the mycoderm is good. And the culture vessel can be designed to the required size according to the requirement to obtain the mycoderm with specific shape and size.
Preferably, the temperature for culturing the mycoderm is 30 ℃, the growth state of the active material, the conductive agent and the nano-cellulose is optimal at the temperature, the obtained mycoderm has a uniformly distributed three-dimensional structure, and the active material and the conductive agent are uniformly distributed and filled fully.
And after the culture is finished, soaking the flexible electrode in ultrapure water or boiling alkaline water to remove impurities, sterilizing at high temperature to obtain a high-purity flexible electrode precursor, and then freeze-drying to obtain the flexible electrode.
The preparation method has the advantages of cheap and easily-obtained raw materials and simple preparation process, and ensures that the active material and the conductive agent are uniformly filled in the generated mycoderm in a co-growth mode, thereby being beneficial to improving the bonding strength of the active material, the conductive agent and the mycoderm and ensuring that the active material in the flexible electrode is not easy to fall off.
The flexible electrode obtained by the preparation method comprises a flexible bacterial membrane with a three-dimensional network structure, and an active material and a conductive agent which are filled and combined in the three-dimensional network structure of the flexible bacterial membrane.
In the flexible electrode, the mass ratio of the active material to the conductive agent is (90-95) to (5-10).
The flexible electrode can be a flexible positive electrode or a flexible negative electrode.
The flexible electrode has the characteristics of high bonding strength of the active material, the conductive agent and the bacterial membrane, good flexibility and the like, so that the flexible electrode can be assembled into a flexible lithium ion battery, and the positive electrode and/or the negative electrode of the flexible lithium ion battery are flexible electrodes.
The electrolyte of the flexible lithium ion battery takes Ethylene Carbonate (EC), dimethyl carbonate (DMC) and methyl ethyl carbonate (EMC) as solvents, and LiPF6Is a lithium salt.
The diaphragm of the flexible lithium ion battery can be a conventional diaphragm, such as a polypropylene (PP) diaphragm and a Polyethylene (PE) diaphragm, and can also be a black tea fungus membrane prepared by the preparation method of the flexible electrode, and an active material and a conductive agent are not added into a culture solution in the preparation process, so that the black tea fungus membrane does not contain the conductive agent and the active material.
The assembled flexible lithium ion battery has good flexibility, and the active material is not easy to fall off from the electrode, thereby greatly improving the electrochemical performance of the lithium ion battery.
In order to more effectively explain the technical solution of the present invention, the technical solution of the present invention is explained below by a plurality of specific examples.
Example 1
A preparation method of a flexible electrode, wherein an active material of the flexible electrode is lithium titanate, and the preparation method comprises the following steps:
(a) separately, 1.2g of black tea, 200g of ultrapure water and 20g of glucose were mixed, sterilized and prepared into 221.2g of a culture solution.
(b) Putting 9.5g of lithium titanate and 0.5g of carbon nanotubes into the culture solution, and ultrasonically crushing and dispersing until the solution is uniform.
(c) Mixing the uniformly mixed dispersion liquid in the step (b) with the black tea fungus liquid according to the mass ratio of the culture liquid to the black tea fungus liquid of 1:1, wherein the mass concentration of the black tea fungus in the black tea fungus liquid is 5%, and standing and culturing under the constant temperature condition of 30 ℃.
(d) Boiling the bacterial membrane obtained in the step (c) with alkaline water to perform sterilization and impurity removal effects, then cleaning with ultrapure water, and freeze-drying to obtain the flexible lithium titanate electrode.
Example 2
A preparation method of a flexible electrode, wherein an active material of the flexible electrode is lithium titanate, and the preparation method comprises the following steps:
(a) 2g of black tea, 400g of ultrapure water and 40g of glucose were mixed, sterilized and prepared into 442g of a culture solution.
(b) 9.3g of lithium titanate and 0.7g of carbon nanotubes are put into the culture solution, and ultrasonically crushed and dispersed until the solution is uniform.
(c) Mixing the uniformly mixed dispersion liquid in the step (b) with the black tea fungus liquid according to the mass ratio of the culture liquid to the black tea fungus liquid of 1:3, wherein the mass concentration of the black tea fungus in the black tea fungus liquid is 20%, and standing and culturing under the constant temperature condition of 30 ℃.
(d) Boiling the bacterial membrane obtained in the step (c) with alkaline water to perform sterilization and impurity removal effects, then cleaning with ultrapure water, and freeze-drying to obtain the flexible lithium titanate electrode.
Example 3
A preparation method of a flexible electrode, wherein an active material of the flexible electrode is lithium titanate, and the preparation method comprises the following steps:
(a) separately, 2.5g of black tea, 500g of ultrapure water and 50g of glucose were mixed, sterilized and prepared into 552.5g of a culture solution.
(b) 9.0g of lithium titanate and 1.0g of carbon nanotubes are put into the culture solution, and ultrasonically crushed and dispersed until the solution is uniform.
(c) And (c) mixing the uniformly mixed dispersion liquid in the step (b) with the black tea fungus liquid according to the mass ratio of the culture liquid to the black tea fungus liquid of 1:2, wherein the mass concentration of the black tea fungus in the black tea fungus liquid is 5%, and standing and culturing at the constant temperature of 25 ℃.
(d) Boiling the bacterial membrane obtained in the step (c) with alkaline water to perform sterilization and impurity removal effects, then cleaning with ultrapure water, and freeze-drying to obtain the flexible lithium titanate electrode.
Example 4
A preparation method of a flexible electrode, wherein an active material of the flexible electrode is lithium titanate, and the preparation method comprises the following steps:
(a) 3g of black tea, 500g of ultrapure water and 40g of glucose were mixed, sterilized and prepared into 543g of a culture solution.
(b) Putting 9.5g of lithium titanate and 0.5g of carbon nanotubes into the culture solution, and ultrasonically crushing and dispersing until the solution is uniform.
(c) Mixing the uniformly mixed dispersion liquid in the step (b) with the black tea fungus liquid according to the mass ratio of the culture liquid to the black tea fungus liquid of 1:1.5, wherein the mass concentration of the black tea fungus in the black tea fungus liquid is 30%, and standing and culturing under the constant temperature condition of 30 ℃.
(d) Boiling the bacterial membrane obtained in the step (c) with alkaline water to perform sterilization and impurity removal effects, then cleaning with ultrapure water, and freeze-drying to obtain the flexible lithium titanate electrode.
Example 5
A preparation method of a flexible electrode comprises the following steps:
(a) separately, 1.2g of black tea, 200g of ultrapure water and 20g of glucose were mixed, sterilized and prepared into 221.2g of a culture solution.
(b) Putting 9.5g of lithium titanate and 0.5g of carbon nanotubes into the culture solution in the step (a), and ultrasonically crushing and dispersing until the solution is uniform.
(c) And (c) mixing the uniformly mixed dispersion liquid in the step (b) with the black tea fungus liquid according to the mass ratio of the culture liquid to the black tea fungus liquid of 1:1, wherein the mass concentration of the black tea fungus in the black tea fungus liquid is 10%, and standing and culturing at the constant temperature of 30 ℃ to obtain the flexible negative electrode, wherein the flexible negative electrode is in a jelly shape.
(d) One week later, preparing the culture solution in the step (a), adding the mixed solution of the prepared culture solution and the black tea fungus liquid into the culture dish in the step (c) according to the mass ratio of 1:1 (wherein the mass concentration of the black tea fungus in the black tea fungus liquid is 10%), continuing to culture at constant temperature of 30 ℃ to obtain a blank black tea fungus membrane, wherein the black tea fungus membrane grows on the jelly-shaped flexible negative electrode surface and is also jelly-shaped, and the black tea fungus membrane is used as a diaphragm.
(e) Preparing the culture solution in the step (a), putting 9.5g of lithium iron phosphate and 0.5g of carbon nano tubes into the culture solution, and performing ultrasonic dispersion until the mixture is uniform to obtain a dispersion solution.
(f) And after one week, adding the dispersion liquid obtained in the step (e) and the black tea fungus liquid into the culture dish in the step (d) according to the mass ratio of the culture liquid to the black tea fungus liquid of 1:1 (wherein the mass concentration of the black tea fungus in the black tea fungus liquid is 10%), continuing constant-temperature culture at 30 ℃ to enable the flexible positive electrode to grow on the surface of the black tea fungus membrane, so as to obtain the flexible positive electrode, and thus obtaining the integrated flexible electrode.
In order to verify the electrochemical performance of the flexible electrodes obtained in examples 1 to 5, the following performance tests were performed.
Scanning Electron Microscopy (SEM)
SEM scanning was performed on the flexible electrodes prepared in examples 1 to 5 by using Tescan mira3, Oxford equipment, and the results are shown in FIGS. 1 and 2, respectively.
Fig. 1a to 1d correspond to embodiments 1 to 4, respectively, and it can be seen from fig. 1 that the three-dimensional network structure of the flexible electrode is good, fine lithium titanate particles are uniformly dispersed in the network structure and tightly wrapped by the cellulose filament and the carbon nanotube, and the flexibility is ensured and the excellent conductivity is required to be satisfied. Meanwhile, the concentration of the active material is higher, and higher material loading can be realized. Wherein, the dispersion is good in figure 1a, and the active material, the conductive agent and the cellulose have good distribution ratio effect.
As can be seen from fig. 2, the layered structure has three distinct layers, with the upper and lower portions being the positive and negative electrodes, and the middle being the blank separator portion. The positive electrode and the negative electrode have obvious particle distribution, and the positive electrode and the negative electrode are in good contact with the diaphragm and are connected into a whole, so that the obtained integrated battery can ensure that the flexible battery has a stable structure and keeps good performance in the bending process.
(II) electrochemical Performance testing
The flexible lithium titanate electrodes obtained in examples 1 to 4 were used in combination with a lithium sheet and an electrolyte (EC: EMC: DMC 1:1:1 vol%, 1M LiPF)6) And a Celgard 2400 diaphragm is assembled into a flexible lithium ion battery in a glove box, the clip battery with the nominal capacity of 1mAh is assembled and then stands for 24h, and then is charged and discharged on a Xinwei charging and discharging instrument at a constant current of 1C, wherein the voltage range is 0.1-2V, and the result is shown in figures 3-6.
FIGS. 3 to 6 correspond to the cycle performance of examples 1 to 4, respectively. As can be seen from FIG. 2, the battery has very good cycle performance, no obvious attenuation after 1000 cycles, and capacity retention rate of more than 90%. Meanwhile, the coulomb efficiency in the circulation process is high and is close to 100 percent. The cycling performance of the electrodes obtained in comparative examples 1 to 4 was best when the ratio of active material to conductive agent was 95: 5. By changing the amount of culture added, it was found that the increase in the amount of culture medium may lower the overall conductivity of the electrode, and therefore the cycle performance was slightly inferior to that of example 1.
The integrated battery (lithium titanate + separator + lithium iron phosphate) obtained in example 5 was charged with an appropriate amount of an electrolyte (EC: EMC: DMC 1:1:1 vol%, 1M LiPF)6) And assembling a flexible lithium ion battery in the glove box, wherein the clip battery with the nominal capacity of 2.5mAh is assembled, standing for 24h after the assembly is finished, and then performing constant current charging and discharging on a Xinwei charging and discharging instrument at the current of 1C, wherein the voltage range is 2.5-3.9V, and the result is shown in figure 7.
As can be seen from fig. 7, the battery has good cycle performance, and under the condition of high capacity, the capacity of the battery is still 1.5mAh after 200 cycles of cycle, and simultaneously, the coulomb efficiency in the cycle process is close to 100%.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (10)

1. A flexible electrode is characterized in that the flexible electrode is a flexible positive electrode or a flexible negative electrode, the flexible positive electrode and/or the flexible negative electrode comprises a flexible mycoderm with a three-dimensional network structure, a conductive agent and an active material, wherein the conductive agent and the active material are filled and combined in the three-dimensional network structure of the flexible mycoderm; the flexible mycoderm is a black tea mycoderm, and the active material and the conductive agent are filled in the generated mycoderm in a co-growth mode.
2. The flexible electrode of claim 1, wherein if the flexible electrode is a flexible negative electrode, the active material is selected from any one of lithium titanate, natural graphite, silicon-based materials, metal oxides;
if the flexible electrode is a flexible positive electrode, the active material is selected from any one of lithium iron phosphate, lithium cobaltate and ternary materials.
3. The flexible electrode of claim 1, wherein the conductive agent is selected from at least one of graphene, carbon nanotubes, and conductive carbon black.
4. The flexible electrode according to claim 1 or 2, wherein the mass ratio of the active material to the conductive agent filled in the flexible three-dimensional mycoderm network frame is (90-95): 5-10.
5. A method for preparing a flexible electrode according to any one of claims 1 to 4, comprising the steps of:
providing a culture solution containing black tea, high-purity water and glucose;
adding an active material, a conductive agent and a black tea fungus strain into the culture solution, and mixing until the active material, the conductive agent and the black tea fungus strain are uniformly dispersed to obtain a flexible electrode growth solution;
standing and culturing the growth solution of the flexible electrode at a constant temperature of 25-35 ℃ to obtain a mycoderm containing an active material and a conductive agent;
and removing impurities from the bacterial membrane, cleaning, and freeze-drying to obtain the flexible electrode.
6. The method for preparing a flexible electrode according to claim 5, wherein the ratio by mass of black tea: high purity water: glucose (2-5): (400-600): (40-60);
according to the mass ratio, the active material: conductive agent: culture solution (90-95): (5-10): (2212-5525).
7. The method for preparing the flexible electrode according to claim 5, wherein the black tea fungus strain is added in a black tea fungus liquid mode, and the mass concentration of the black tea fungus in the black tea fungus liquid is 5% -30%; the adding amount of the black tea fungus liquid is 50-150% of the mass of the culture solution.
8. The method for preparing a flexible electrode according to claim 5, further comprising a process of sterilizing the obtained mycoderm before removing impurities.
9. A flexible lithium ion battery comprises a positive electrode and a negative electrode, and is characterized in that the positive electrode is the flexible electrode as claimed in any one of claims 1 to 4 or the flexible electrode prepared by the preparation method of the flexible electrode as claimed in any one of claims 5 to 8; and/or the negative electrode is the flexible electrode as claimed in any one of claims 1 to 4 or the flexible electrode prepared by the preparation method of the flexible electrode as claimed in any one of claims 5 to 8.
10. The flexible lithium ion battery of claim 9, wherein the electrolyte of the flexible lithium ion battery is prepared by using ethylene carbonate, dimethyl carbonate and methyl ethyl carbonate as solvents and LiPF6Is a lithium salt; the diaphragm of the flexible lithium ion battery is a black tea fungus membrane or a polypropylene diaphragm or a polyethylene diaphragm.
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