A lithiated polyether ether ketone-based composite solid electrolyte and a method for preparing the same

Abstract

The application discloses a kind of lithiated polyether ether ketone-based composite solid electrolyte and preparation method thereof.The preparation method comprises the following steps: polyether ether ketone polymer is sulfonated in concentrated sulfuric acid, then ion exchange is carried out in lithium hydroxide aqueous solution, to obtain lithiated polyether ether ketone;Lithiated polyether ether ketone, lithium bis-trifluoromethylsulfonimide is dissolved in organic solvent to prepare polymer / lithium salt solution, and butanedinitrile, fluoroethylene carbonate is added, to obtain lithiated polyether ether ketone / butanedinitrile composite electrolyte solution;Lithiated polyether ether ketone / butanedinitrile composite electrolyte solution is prepared into film, and after drying, lithiated polyether ether ketone-based composite solid electrolyte is obtained.The composite solid electrolyte film of the application has mechanical flexibility and thermal dimensional stability, not only optimizes the interface stability of electrolyte and electrode, but also significantly improves the ionic conductivity and charge-discharge cycle stability of lithium metal battery, fundamentally improves the thermal safety and capacity decay problem of lithium metal battery.

Description

Technical Field

[0001] This invention relates to the field of solid electrolytes for lithium metal batteries and their preparation, specifically a lithium-ionized polyether ether ketone-based composite solid electrolyte and its preparation method. Background Technology

[0002] Lithium-ion batteries have been widely used in portable electronic devices, smart homes, and new energy vehicles due to their significant advantages such as low cost, high energy density, long lifespan, low self-discharge rate, and no memory effect. Among them, lithium metal anodes, with their high theoretical specific capacity (3860 mAh g⁻¹), are particularly valuable. -1 The outstanding characteristics of lithium metal (LiMe) and its low electrode potential (-3.04 V vs. standard hydrogen electrode) make it an ideal negative electrode material for lithium-ion batteries. However, uneven deposition / stripping of lithium ions on its surface can easily lead to the formation of lithium dendrites, causing capacity decay and, in severe cases, puncturing the separator, resulting in safety hazards such as short circuits and thermal runaway. Polymer solid electrolytes, which combine excellent flexibility and good interfacial compatibility, integrate the functions of electrolyte and separator. With their excellent mechanical strength and uniform lithium-ion transport characteristics, they can fundamentally suppress the growth of lithium dendrites and the risk of puncture. However, the widely used polyethylene oxide (PEO)-based solid electrolytes, although they can promote efficient lithium salt dissociation and rapid lithium-ion transport by forming coordination with lithium ions through the ether oxygen coordination sites in the molecular chain, still have significant shortcomings in mechanical strength, high-temperature resistance, and safety, making it difficult to meet the practical application requirements of high-performance lithium metal batteries.

[0003] Polyetheretherketone (PEEK), an aromatic polymer with an alternating ether-ketone structure, possesses excellent thermal stability and mechanical strength, effectively preventing short circuits caused by electrolyte membrane shrinkage and melting under abnormally high temperatures, making it an ideal candidate material for electrolyte membrane substrates. Succinate (SN), as a plasticizer, can significantly improve the ion transport efficiency of the electrolyte and is inexpensive, showing broad application prospects. However, pure PEEK molecules are rigid and lack ion transport active sites. When combined with SN, they exhibit poor compatibility and low ion transport efficiency, making it difficult to balance mechanical properties and ionic conductivity. Furthermore, SN readily undergoes side reactions with low-potential lithium metal, corroding the electrode and forming an unstable passivation layer, leading to rapid capacity decay and severely restricting battery cycle life and safety. Therefore, developing a PEEK / SN composite solid-state electrolyte membrane with excellent mechanical properties, thermal dimensional stability, high ionic conductivity, good interfacial stability, and lithium dendrite suppression capability is crucial to overcoming existing technological bottlenecks. Summary of the Invention

[0004] To overcome the aforementioned shortcomings and deficiencies of the prior art, the present invention aims to provide a lithium-based polyether ether ketone (PEEEK) composite solid electrolyte and its preparation method. The method involves modifying PEEK polymers to obtain lithium-based PEEK with both mechanical properties and thermal stability as the polymer backbone. This backbone is then composited with succinic anion exchanger (SN). Utilizing the ion-dipole interaction between the lithium-based PEEK and succinic anion exchanger, the electrolyte's ion transport behavior is effectively regulated: on the one hand, it promotes efficient lithium-ion conduction and uniform deposition, significantly increasing lithium-ion transference number while improving ion conductivity; on the other hand, it improves the uniformity of lithium-ion deposition at the electrode interface, inhibits lithium dendrite growth, and thus extends battery cycle life. The present invention simultaneously solves the technical difficulties of SN's corrosion of lithium metal and uneven lithium-ion deposition.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention provides a method for preparing a lithium-ionized polyether ether ketone-based composite solid electrolyte, comprising the following steps:

[0007] (1) Polyether ether ketone polymers are sulfonated in concentrated sulfuric acid to obtain sulfonated polyether ether ketone;

[0008] (2) Sulfonated polyether ether ketone undergoes ion exchange in an aqueous lithium hydroxide solution to obtain lithium-ionized polyether ether ketone;

[0009] (3) Lithium-ionized polyether ether ketone and lithium bis(trifluoromethanesulfonyl)imide are dissolved in an organic solvent to prepare a polymer / lithium salt solution, and succinic acid and fluoroethylene carbonate are added to obtain a lithium-ionized polyether ether ketone / succinic acid composite electrolyte solution.

[0010] (4) Prepare a film from the lithium-ionized polyether ether ketone / succinic acid composite electrolyte solution obtained in step (3), and dry it to obtain a lithium-ionized polyether ether ketone-based composite solid electrolyte.

[0011] In some embodiments of the present invention, the polyetheretherketone polymer has one of the following structures:

[0012]

[0013] Where n is the degree of aggregation, and the value of n ranges from 200 to 700.

[0014] In some embodiments of the present invention, in step (3), the mass ratio of the lithium-ionized polyether ether ketone to succinic acid is (1~4):1.

[0015] In some embodiments of the present invention, in step (3), the mass ratio of the lithium-ionized polyether ether ketone to lithium bis(trifluoromethanesulfonylimide) is 1:(0.5~2).

[0016] In some embodiments of the present invention, in step (3), the mass ratio of the fluoroethylene carbonate to the succinic acid is (0.1~0.5):1.

[0017] In some embodiments of the present invention, the sulfonation treatment in step (1) specifically involves a sulfonation temperature of 40 °C to 80 °C and a sulfonation time of 3 to 5 h.

[0018] In some embodiments of the present invention, in step (3), the organic solvent is one of N,N-dimethylformamide, N,N-dimethylacetamide or dimethyl sulfoxide.

[0019] The present invention also provides a lithium-based polyether ether ketone composite solid electrolyte, comprising lithium-based polyether ether ketone, lithium bis(trifluoromethanesulfonyl)imide, succinate and fluoroethylene carbonate; wherein the mass ratio of lithium-based polyether ether ketone to succinate is (1~4):1; and the mass ratio of lithium-based polyether ether ketone to lithium bis(trifluoromethanesulfonyl)imide is 1:(0.5~2).

[0020] In some embodiments of the present invention, there is an ion-dipole interaction between lithium-ionized polyether ether ketone and succinic acid.

[0021] The present invention also provides a lithium metal battery comprising the aforementioned lithium-ionized polyether ether ketone-based composite solid electrolyte.

[0022] The principle of this invention is as follows:

[0023] This invention selects polyetheretherketone (PEEK) polymers as the matrix material, which possess an aromatic structure with alternating ether and ketone components, exhibiting excellent thermal stability and mechanical strength. By sulfonating and ion-exchanging the PEEK polymers, -SO3Li active groups are introduced to construct single-ion conductor channels, laying the structural foundation for efficient lithium-ion migration. Succinate (SN), as a high-ionic-conductivity, low-cost plasticizer, can significantly improve the ionic conductivity of the electrolyte system; however, SN readily undergoes side reactions with strongly reducing lithium metal, leading to lithium metal electrode corrosion and interfacial instability, thereby causing battery capacity decay. This invention, based on the ion-dipole interaction between lithium-ionized PEEK and succinate, prepares a high-safety and high-performance lithium-ionized PEEK-based composite solid electrolyte, precisely controlling the ion transport behavior in the electrolyte, thereby improving the thermal safety, cycle stability, and capacity retention of lithium metal batteries.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] (1) This invention utilizes the ion-dipole interaction between lithium-ionized polyether ether ketone (PEEK) and succinic anion to effectively regulate the ion transport behavior of the electrolyte. On the one hand, it promotes efficient lithium-ion conduction and uniform deposition, significantly increasing the lithium-ion transference number while improving ion conductivity; on the other hand, it improves the uniformity of lithium-ion deposition at the electrode interface, inhibits lithium dendrite growth, and thus extends the battery cycle life. This method simultaneously solves the technical difficulties of lithium metal corrosion by SN and uneven lithium-ion deposition.

[0026] (2) By controlling the sulfonation reaction conditions (such as reaction temperature), the present invention can precisely adjust the degree of sulfonation of PEEK and the content of -SO3Li groups (lithiation rate), thereby optimizing the interaction strength between PEEK-SO3Li-x and SN, and obtaining a composite solid electrolyte membrane with adjustable electrochemical performance and excellent thermal dimensional stability to meet the performance and safety requirements of lithium metal batteries in different application scenarios. Attached Figure Description

[0027] Figure 1 The stress-strain test results are for the lithium-ionized polyether ether ketone-based composite solid electrolytes of Examples 1-3 of the present invention.

[0028] Figure 2 The thermal dimensional stability tests of the lithium-ionized polyether ether ketone-based composite solid electrolytes in Examples 1-3 of the present invention are presented.

[0029] Figure 3 Linear sweep voltammetry (LSV) tests were performed on the lithium-ionized polyether ether ketone-based composite solid electrolytes of Examples 1-3 of this invention.

[0030] Figure 4 The image shows the EIS spectrum of the lithium-ionized polyether ether ketone-based composite solid electrolyte of Example 1 of the present invention at 30 °C to 80 °C.

[0031] Figure 5 The ionic conductivity at 30 °C to 80 °C is that of the lithium-ionized polyether ether ketone-based composite solid electrolyte of Example 1 of the present invention.

[0032] Figure 6 The image shows the EIS spectrum of the lithium-ionized polyether ether ketone-based composite solid electrolyte of Example 2 of the present invention at 30 °C to 80 °C. The inset is a partial enlarged view.

[0033] Figure 7 The ionic conductivity at 30 °C to 80 °C is that of the lithium-ionized polyether ether ketone-based composite solid electrolyte of Example 2 of the present invention.

[0034] Figure 8The image shows the EIS spectrum of the lithium-ionized polyether ether ketone-based composite solid electrolyte of Example 3 of the present invention at 30 °C to 80 °C.

[0035] Figure 9 The ionic conductivity at 30 °C to 80 °C is that of the lithium-ionized polyether ether ketone-based composite solid electrolyte of Example 3 of the present invention.

[0036] Figure 10 The graphs show the long-cycle performance of lithium metal batteries using lithium-ionized polyether ether ketone-based composite solid electrolytes in Examples 1-3 of this invention at 0.2C under 25 °C.

[0037] Figure 11 The graphs show the long-cycle performance of lithium metal batteries using lithium-ionized polyether ether ketone-based composite solid electrolytes in Examples 1-3 of this invention at 0.5C under 25 °C.

[0038] Figure 12 The figure shows the chronocurrent curve of the lithium-ionized polyether ether ketone-based composite solid electrolyte of Example 1 of the present invention, with the inset showing the EIS spectra before and after polarization.

[0039] Figure 13 The figure shows the chronoamperometry curve of the lithium-ion polyether ether ketone-based composite solid electrolyte of Example 2 of the present invention, with the inset showing the EIS spectra before and after polarization.

[0040] Figure 14 The figure shows the chronoamperometry curve of the lithium-ion polyether ether ketone-based composite solid electrolyte of Example 3 of the present invention, with the inset showing the EIS spectra before and after polarization.

[0041] Figure 15 The lithium-ion transference number is the lithium-ion transference number of the lithium-ion polyether ether ketone-based composite solid electrolytes of Examples 1-3 of the present invention. Detailed Implementation

[0042] The present invention is further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0043] Example 1: Preparation of lithium-ionized polyetheretherketone / succinic anionyl nitrile composite solid electrolyte membrane

[0044] Step 1: Sulfonation reaction

[0045] 10g of polyether ether ketone (PEEK) powder was added to 140mL of 98% concentrated sulfuric acid (H2SO4) and mechanically stirred at room temperature for 1h until completely dissolved. Then, under a nitrogen protective atmosphere, the mixture was heated in an oil bath at 50℃ for 4h to complete the sulfonation reaction.

[0046] Step 2: Preparation of sulfonated polyether ether ketone (PEEK-SO3H)

[0047] The reaction solution from step one was slowly poured into excess ice water to precipitate fiber precipitate. After filtration and collection of the precipitate, it was repeatedly washed with deionized water until the pH of the washing solution was 7 to remove residual sulfuric acid. The washed precipitate was placed in an 80°C forced-air oven and dried for 12 hours to obtain sulfonated polyether ether ketone (PEEK-SO3H).

[0048] Step 3: Preparation of lithium-ionized polyether ether ketone (PEEK-SO3Li)

[0049] The PEEK-SO3H obtained in step two was placed in an excess of 0.1 mol L. -1 An ion exchange reaction was carried out in an aqueous solution of lithium hydroxide (LiOH) at room temperature for 24 h. After the reaction was completed, the product was collected by filtration and washed repeatedly with deionized water until the pH of the washing solution was 7 to remove unreacted LiOH. The product was then dried in an 80°C oven for 12 h to obtain lithium-ionized polyether ether ketone (PEEK-SO3Li).

[0050] Step 4: Preparation of the composite polymer electrolyte solution

[0051] Accurately weigh 1g PEEK-SO3Li and 1g lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), dissolve them in 4 mL N,N-dimethylformamide (DMF), and stir at room temperature until a homogeneous polymer / lithium salt solution is formed; then add 3g succinate (SN) and 0.6g fluoroethylene carbonate (FEC), and continue stirring for 12 h to obtain a homogeneous and stable lithium-ionized polyetheretherketone / succinate composite electrolyte solution.

[0052] Step 5: Solution casting to form a film

[0053] The above-mentioned composite electrolyte solution was uniformly poured into a polytetrafluoroethylene (PTFE) mold using a solution casting method. Most of the DMF solvent was evaporated in a fume hood at room temperature, allowing the electrolyte membrane to initially form.

[0054] Step Six: Secondary Drying

[0055] The pre-formed membrane was dried in an 80 °C forced-air oven for 4 h to remove residual solvent; then it was transferred to an 80 °C vacuum oven for a second drying for 24 h to obtain a lithium-ionized polyether ether ketone / succinic anion composite solid electrolyte membrane (denoted as SN3 / PEEK-SO3Li-0.6).

[0056] Example 2

[0057] In Example 2, the oil bath temperature in step one was 60°C, and the composite solid electrolyte membrane SN3 / PEEK-SO3Li-0.9 was finally obtained.

[0058] Example 3

[0059] In Example 3, the oil bath temperature in step one was 70°C, and the composite solid electrolyte membrane SN3 / PEEK-SO3Li-1.1 was finally obtained.

[0060] Mechanical property testing of electrolyte membranes:

[0061] In this invention, the composite electrolyte membranes of Example 1 (SN3 / PEEK-SO3Li-0.6), Example 2 (SN3 / PEEK-SO3Li-0.9), and Example 3 (SN3 / PEEK-SO3Li-1.1) were cut into strips of 50 mm × 10 mm and subjected to tensile testing using an electronic universal testing machine at a tensile rate of 50 mm / min. The stress-strain test results are as follows: Figure 1 As shown, the tensile strengths of the electrolyte membranes corresponding to Examples 1, 2, and 3 are 1.11 MPa, 1.85 MPa, and 1.38 MPa, respectively. The test results show that SN3 / PEEK-SO3Li-0.9 exhibits higher fracture strength (1.85 MPa) and elongation at break (225%). With the increase of the -SO3Li grafting rate, the interaction between PEEK-SO3Li-x and the cyano group (-CN) of SN is enhanced, leading to an increase in the material's fracture strength and elongation at break. However, as the -SO3Li grafting rate continues to increase (SN3 / PEEK-SO3Li-1.1), excessive negative charge leads to increased inter-chain repulsive forces, weakened inter-chain interactions, and increased chain slippage or breakage, resulting in a slight decrease in fracture strength and elongation at break.

[0062] Electrolyte membrane thermal dimensional stability test:

[0063] The thermal dimensional stability of the composite electrolyte membranes of Example 1 (SN3 / PEEK-SO3Li-0.6), Example 2 (SN3 / PEEK-SO3Li-0.9), and Example 3 (SN3 / PEEK-SO3Li-1.1) was tested by gradient heating to 200 °C in a -0.1 MPa vacuum oven. The test results are as follows: Figure 2 As shown in the figure, Examples 1-3 did not melt, shrink, or deform under 200℃ high-temperature conditions, exhibiting excellent thermal dimensional stability. This indicates that the lithium-based polyether ether ketone composite solid electrolyte can avoid short-circuit problems caused by electrolyte volatilization and melting under abnormally high-temperature conditions, thereby preventing thermal runaway and effectively improving the thermal safety of lithium metal batteries.

[0064] Linear Sweep Voltammetry (LSV) test of electrolyte membrane:

[0065] This invention assembles the above-mentioned electrolyte membrane into an SS||SPE||Li coin cell and performs linear sweep voltammetry (LSV) testing on it. The test results are as follows: Figure 3 As shown in the figure, the electrochemical windows of the electrolyte membranes corresponding to Examples 1, 2, and 3 are 5.12V, 5.56V, and 5.85V, respectively. The test results show that as the content of -SO3Li groups on the PEEK-SO3Li-x molecular chain gradually increases in the examples of this invention, the electron-withdrawing ability of the molecular chain is correspondingly enhanced, thereby significantly improving the antioxidant capacity of the electrolyte membrane. Specifically, this manifests as continuous optimization of the high-voltage performance of the electrolyte membrane, enabling it to adapt to a wider range of operating voltages and effectively improving the safety of lithium metal batteries.

[0066] Electrolyte membrane ionic conductivity test:

[0067] Electrochemical impedance spectroscopy (EIS) was performed on the composite electrolyte membranes of Example 1 (SN3 / PEEK-SO3Li-0.6), Example 2 (SN3 / PEEK-SO3Li-0.9), and Example 3 (SN3 / PEEK-SO3Li-1.1). The ionic conductivity is as follows: Figures 4-9 As shown in the figure. The test results show that the ionic conductivity corresponding to Examples 1, 2, and 3 is 2.44 × 10⁻⁶. -4 3.0×10 -4 1.46×10 -4 S cm -1 The ionic conductivity of Example 2 was significantly higher than that of the other two examples. This phenomenon is mainly attributed to the combined regulation of the lithiation rate (i.e., the -SO3Li grafting rate) of the polymer matrix PEEK-SO3Li-x and its interaction with the plasticizer SN.

[0068] (1) As the lithiation rate gradually increases, the polarity of PEEK-SO3Li-x is correspondingly enhanced, and the interaction between it and SN promotes the uniform dispersion of SN in the matrix, providing a smoother channel for ion migration and driving the improvement of ionic conductivity.

[0069] (2) When the lithiation rate is too high, the rigidity of the PEEK-SO3Li-x matrix increases significantly, the movement of molecular chain segments is significantly restricted, which in turn hinders ion migration and leads to a decrease in ionic conductivity;

[0070] (3) In Example 2, the -SO3Li grafting rate of SN3 / PEEK-SO3Li-0.9 is about 90%. At this time, its steric hindrance effect and polar interaction reach the optimal balance, and the molecular chain segment mobility is in the best state, thus exhibiting the highest ionic conductivity.

[0071] Based on the above regulation mechanism, the present invention can specifically regulate the interaction between the oil bath and SN by controlling the oil bath temperature in step (1), thereby obtaining lithium metal battery electrolyte membranes that meet different performance requirements.

[0072] Lithium metal battery cycle performance test at 0.2C and 0.5C:

[0073] In this invention, the composite electrolyte membranes of Example 1 (SN3 / PEEK-SO3Li-0.6), Example 2 (SN3 / PEEK-SO3Li-0.9), and Example 3 (SN3 / PEEK-SO3Li-1.1) were assembled into lithium metal batteries, and their cycle performance was tested at charge-discharge rates of 0.2C and 0.5C. The test results are as follows: Figures 10-11 As shown.

[0074] Test results show that:

[0075] (1) In the SN3 / PEEK-SO3Li-1.1 composite electrolyte membrane of Example 3, the strong ion-dipole interaction between PEEK-SO3Li-1.1 and SN can effectively alleviate the corrosion reaction of SN on lithium metal electrode. In particular, under the current density of 0.5C, the battery capacity decay phenomenon is significantly improved.

[0076] (2) The battery assembled with the SN3 / PEEK-SO3Li-0.9 composite electrolyte membrane in Example 2 has an initial discharge capacity of 150 mAh・g⁻¹ at a rate of 0.2C, showing excellent initial electrochemical performance;

[0077] (3) The SN3 / PEEK-SO3Li-0.6 composite electrolyte membrane in Example 1 has a low content of -SO3Li groups on the molecular chain, which cannot fully play the role of ion transport and interface stabilization, resulting in rapid capacity decay of the battery during cycling.

[0078] Lithium-ion transport number test of electrolyte membrane:

[0079] In this invention, the composite electrolyte membranes of Example 1 (SN3 / PEEK-SO3Li-0.6), Example 2 (SN3 / PEEK-SO3Li-0.9), and Example 3 (SN3 / PEEK-SO3Li-1.1) were assembled into Li||SPE||Li coin cells. Chrono-current and electrochemical impedance spectroscopy tests were performed to calculate the lithium-ion transference number. The test results are as follows: Figures 12-15The test results showed that the lithium-ion transference numbers for Examples 1, 2, and 3 were 0.48, 0.72, and 0.81, respectively. The lithium-ion transference number increased with the increase of the -SO3Li grafting rate of PEEK-SO3Li-x. This is mainly attributed to the fact that the -SO3Li group can not only serve as a lithium source to provide active Li... + Meanwhile, its negative charge portion (-SO3) - The TFSI is immobilized on the polymer backbone, creating a stable anionic environment, thereby suppressing TFSI. - The migration of lithium ions is facilitated by this effect. This increases the lithium ion concentration at the interface between the polymer electrolyte and the electrode, promoting lithium ion transport and resulting in an increased lithium ion transference number.

[0080] Understandably, in the above embodiments, polyetheretherketone (PEEK) may also be one of the following structures:

[0081] .

[0082] Polyether ketone ketone (PEKK) and polyether ether ketone ketone (PEEKK) both belong to the polyarylether ketone polymer family, and their main chain structures are similar to those of polyether ether ketone (PEEK). The electrolyte membrane design in this invention is primarily based on sulfonation, ion exchange, and the interaction between -SO3Li and SN. The sulfonation reaction mainly occurs at the active sites on the benzene ring. For both PEKK and PEEKK, the electron cloud density of their aromatic rings is sufficient to undergo electrophilic substitution (-SO3H grafting). Ion exchange yields PEKK-SO3Li-x and PEEKK-SO3Li-x. Furthermore, the introduction of -SO3Li increases the polarity of PEKK-SO3Li-x and PEEKK-SO3Li-x, making them soluble and allowing for the preparation of electrolyte membranes via solution casting for application in lithium metal batteries. Since polyaryletherketone polymers have similar main chain rigidity, thermal stability, and chemical stability, the prepared SN / PEKK-SO3Li-x and SN / PEEKK-SO3Li-x electrolyte membranes can exhibit similar comprehensive performance to the SN3 / PEEK-SO3Li-x electrolyte membrane in lithium metal batteries.

[0083] Those skilled in the art will readily understand that the above description is merely an embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a lithium-ionized polyether ether ketone-based composite solid electrolyte, characterized in that, Includes the following steps: (1) Polyether ether ketone polymers are sulfonated in concentrated sulfuric acid to obtain sulfonated polyether ether ketone; (2) Sulfonated polyether ether ketone undergoes ion exchange in an aqueous lithium hydroxide solution to obtain lithium-ionized polyether ether ketone; (3) Lithium-ionized polyether ether ketone and lithium bis(trifluoromethanesulfonyl)imide are dissolved in an organic solvent to prepare a polymer / lithium salt solution, and succinic acid and fluoroethylene carbonate are added to obtain a lithium-ionized polyether ether ketone / succinic acid composite electrolyte solution. (4) Prepare a film from the lithium-ionized polyether ether ketone / succinic acid composite electrolyte solution obtained in step (3), and dry it to obtain a lithium-ionized polyether ether ketone-based composite solid electrolyte.

2. The method for preparing the lithium-ionized polyether ether ketone-based composite solid electrolyte according to claim 1, characterized in that, The polyetheretherketone polymer has one of the following structures: ； Where n is the degree of aggregation, and the value of n ranges from 200 to 700.

3. The method for preparing the lithium-ionized polyether ether ketone-based composite solid electrolyte according to claim 1, characterized in that, In step (3), the mass ratio of lithium-ionized polyether ether ketone to succinic acid is (1~4):

1.

4. The method for preparing the lithium-ionized polyether ether ketone-based composite solid electrolyte according to claim 1, characterized in that, In step (3), the mass ratio of lithium-ionized polyether ether ketone to lithium bis(trifluoromethanesulfonylimide) is 1:(0.5~2).

5. The method for preparing the lithium-ionized polyether ether ketone-based composite solid electrolyte according to claim 1, characterized in that, In step (3), the mass ratio of fluoroethylene carbonate to succinic acid is (0.1~0.5):

1.

6. The method for preparing the lithium-ionized polyether ether ketone-based composite solid electrolyte according to claim 1, characterized in that, The sulfonation treatment in step (1) is specifically as follows: the sulfonation temperature is 40 °C ~ 80 °C, and the sulfonation time is 3 ~ 5 h.

7. The method for preparing the lithium-ionized polyether ether ketone-based composite solid electrolyte according to claim 1, characterized in that, In step (3), the organic solvent is N,N-dimethylformamide, N,N-dimethylacetamide or dimethyl sulfoxide.

8. A lithium-ionized polyetheretherketone-based composite solid electrolyte, characterized in that, It includes lithium-ionized polyether ether ketone, lithium bis(trifluoromethanesulfonyl)imide, succinate, and fluoroethylene carbonate; the mass ratio of the lithium-ionized polyether ether ketone to succinate is (1~4):1; the mass ratio of the lithium-ionized polyether ether ketone to lithium bis(trifluoromethanesulfonyl)imide is 1:(0.5~2).

9. The lithium-ionized polyetheretherketone-based composite solid electrolyte according to claim 8, characterized in that, There is an ion-dipole interaction between the lithium-ionized polyether ether ketone and succinic acid.

10. A lithium metal battery, characterized in that, It comprises the lithium-ionized polyether ether ketone-based composite solid electrolyte as described in claim 8 or 9.

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