Polymer solid electrolyte, lithium ion battery and preparation method

Abstract

The invention discloses a polymer solid electrolyte, a lithium ion battery and a preparation method. The polymer solid electrolyte comprises a polymer electrolyte, a lithium salt and an additive, the lithium salt initiates the polymer electrolyte to perform in-situ polymerization; the polymer electrolyte is poly (1, 3-dioxolame) obtained by ring opening polymerization of 1, 3-dioxolame. The in-situ polymerization high-concentration salt polymer solid electrolyte has good interface contact with an electrode, so that ion transmission at an interface is optimized; due to poor fluidity of the polymer, a construction site of a solid-state inter-electrolyte phase (SEI) is moved from the surface of an electrode particle to an electrode / electrolyte interface, and the volume change rate is far smaller than that of the surface of the particle, so that the SEI is essentially prevented from bearing huge stress of volume expansion.

Description

Technical Field

[0001] The present application relates to a polymer solid electrolyte, a lithium ion battery and a preparation method, and belongs to the technical field of batteries. Background Art

[0002] Among commercial secondary batteries, lithium-ion batteries have the highest energy density. However, the theoretical specific capacity of lithium-ion batteries based on the "deintercalation" theory is currently less than 300 mA hg -1 , the actual energy density is less than 200Whkg -1 , which is far from meeting people's demand for electric vehicles to have a range of 500km. Therefore, it is urgent to develop electrode materials with high theoretical specific capacity. Among the new electrode materials, there are many materials with high theoretical specific capacity, such as lithium metal anode (3600mA hg -1 )、Silicon anode (4200mAh g -1 )、sulfur cathode (1672mA hg -1 )wait.

[0003] However, among the electrode materials that have been developed to be relatively mature or new electrode materials, there are many materials that have volume changes during the charging and discharging process. For example: the volume change rate of graphite before and after charging and discharging is 10-20%, the unit cell volume of the high nickel system will shrink by 5%-10% during the delithiation process, the volume change rate of the sulfur positive electrode before and after charging and discharging is 79%, and the lithium negative electrode inevitably has volume changes due to its deposition and dissolution charging and discharging mechanism. The volume change rate of the silicon-based negative electrode before and after charging and discharging is even as high as 400%. On the one hand, a volume change of more than 50% during the charging process will cause the particles of the active material to fall off the electrode, lose electrical connection with the electrode, and thus cause the loss of active material; on the other hand, it will destroy the SEI or CEI in the electrode, causing repeated side reactions and continuous consumption of electrolyte and active Li + . This will eventually cause the battery polarization to increase and the capacity to decay.

[0004] Using low-fluidity solid electrolytes to transfer the construction location of SEI or CEI in the electrode from the particle surface to the electrode / electrolyte interface can effectively avoid the continuous occurrence of side reactions in the electrode. Compared with other types of solid electrolytes, in-situ polymerized polymer solid electrolytes have better physical contact with the electrode, which is conducive to ion conduction at the interface. In addition, the flexibility of polymer electrolytes can better adapt to the volume changes of the electrode. 1,3-Dioxolane (DOL) is a commonly used ether solvent that can be initiated by proton acid and polymerized in situ to prepare polymer solid electrolytes. However, in the existing poly-DOL strategy, due to the uncontrollable rapid ring-opening polymerization of DOL, it leads to excessive polymerization and poor solubility of lithium salts, which will affect the ion transport in the electrolyte. Summary of the invention

[0005] The in-situ polymerized high-concentration salt polymer solid electrolyte protected by the present invention has the following advantages: 1. For electrodes whose active materials are powders, the polymer solid electrolyte transfers the site for constructing SEI / CEI from the surface of the particles to the electrode / electrolyte interface, thereby avoiding its change with the volume change of the particles and reducing its breakage; 2. The in-situ polymerization preparation method ensures good ion transport at the electrode / electrolyte interface; 3. By adding appropriate additives (inhibitors) to regulate the speed of DOL ring-opening polymerization, high-concentration lithium salt dissolution is achieved; 4. The high-concentration salt polymer solid electrolyte changes the Li + The solvation structure of the evolved SEI / CEI increases the content of inorganic components, thereby enhancing the mechanical strength of SEI / CEI and improving its stability; 5. The higher lithium salt concentration in the high-concentration salt polymer solid electrolyte ensures the rapid transmission of lithium ions in the electrolyte. Therefore, the lithium-ion battery prepared using the high-concentration salt polymer solid electrolyte has good cycle stability and rate performance.

[0006] According to one aspect of the present application, a polymer solid electrolyte is provided, the polymer solid electrolyte comprising a polymer electrolyte, a lithium salt and an additive;

[0007] The lithium salt initiates in-situ polymerization of the polymer electrolyte;

[0008] The additive is selected from LiNO 3 and / or LiTFSI;

[0009] The polymer electrolyte includes 1,3-dioxolane and poly-1,3-dioxolane;

[0010] The poly 1,3-dioxolane is obtained by ring-opening polymerization of 1,3-dioxolane.

[0011] Optionally, the lithium salt is selected from LiFSI and / or LiPF 6 .

[0012] Optionally, the concentration of the lithium salt relative to the 1,3-dioxolane is 2 mol L -1 ~10mol L -1 .

[0013] Optionally, the concentration of the lithium salt is independently selected from 2 mol L -1 , 4 mol L -1 , 6 mol L -1 , 8 mol L -1 , 10 mol L -1Any value in or a range between any two of the above.

[0014] Optionally, the concentration of the lithium salt relative to the 1,3-dioxolane is 4 mol L -1 ~8mol L -1 Optionally, the weight average molecular weight of the poly 1,3-dioxolane is 10,000 to 3,000,000.

[0015] Optionally, the weight average molecular weight of the poly 1,3-dioxolane is independently selected from any value of 10,000, 50,000, 100,000, 500,000, 1,000,000, 2,000,000, 3,000,000, or a range between any two of the above values.

[0016] Optionally, the weight average molecular weight of the poly 1,3-dioxolane is 50,000 to 1,000,000.

[0017] Optionally, when the additive is LiNO 3 When LiNO 3 The amount of the compound used is 0.2wt.% to 10wt.% of the 1,3-dioxolane.

[0018] Optionally, when the additive is LiNO 3 When LiNO 3 The amount of 1,3-dioxolane used is independently selected from any value among 0.2wt.%, 0.5wt.%, 1wt.%, 2wt.%, 5wt.%, 10wt.% or a range between any two of the above.

[0019] Optionally, when the additive is LiNO 3 When LiNO 3 The amount of the compound used is 1wt.% to 5wt.% of the 1,3-dioxolane.

[0020] Optionally, when the additive is LiTFSI, the concentration of LiTFSI relative to the 1,3-dioxolane is 0.1 mol L -1 ~5mol L -1 .

[0021] Optionally, when the additive is LiTFSI, the concentration of LiTFSI is independently selected from 0.1 mol L -1 , 0.5 mol L -1 , 1 mol L -1 , 2 mol L -1 , 3 mol L -1 , 5 mol L -1Any value in or a range between any two of the above.

[0022] Optionally, when the additive is LiTFSI, the concentration of LiTFSI relative to the 1,3-dioxolane is 0.5 mol L -1 ~2mol L -1 .

[0023] Optionally, the polymer solid electrolyte further includes an initiator, and the initiator initiates in-situ polymerization of the polymer electrolyte.

[0024] Optionally, the initiator is selected from Al(OTf) 3 and / or polysulfides.

[0025] Optionally, the amount of the initiator used is 0.5 wt.% to 5 wt.% of the 1,3-dioxolane.

[0026] Optionally, when an initiator is used, the lithium salt is selected from LiTFSI, LiClO 4 , LiBF 4 、LiAsF 4 、LiCF 3 SO 3 At least one of .

[0027] According to another aspect of the present application, a lithium-ion battery is provided, the lithium-ion battery comprising a polymer solid electrolyte, a positive electrode, a negative electrode and a separator;

[0028] The polymer solid electrolyte is selected from the polymer solid state battery described above.

[0029] Optionally, when the lithium-ion battery is charged and discharged, at least one side of the positive electrode or the negative electrode undergoes a volume change.

[0030] Optionally, the volume change is 50% to 500%.

[0031] Optionally, if the volume of the positive electrode changes, the positive electrode is a sulfur positive electrode.

[0032] Optionally, if the volume of the negative electrode changes, the negative electrode is selected from at least one of a silicon negative electrode, a silicon oxide negative electrode, and a lithium negative electrode.

[0033] According to another aspect of the present application, a method for preparing the lithium-ion battery described above is provided, the method comprising:

[0034] The separator is immersed in a polymer solid electrolyte precursor solution, assembled into a battery for in-situ polymerization, and a lithium-ion battery is obtained;

[0035] The polymer solid electrolyte precursor solution comprises 1,3-dioxolane, lithium salt and additives.

[0036] Optionally, the soaking time is 2 to 60 seconds.

[0037] Optionally, the soaking time is independently selected from any value among 2s, 5s, 10s, 30s, 45s, 60s or a range between any two of the above.

[0038] Optionally, the soaking time is 5 to 30 seconds.

[0039] Optionally, the in-situ polymerization time is 10 min to 12 h.

[0040] Optionally, the time of the in-situ polymerization is independently selected from any value of 10 min, 30 min, 1 h, 2 h, 5 h, 8 h, 10 h, 12 h, or a range between any two of the above values.

[0041] As a specific implementation, the present application is implemented through the following technical solutions:

[0042] An in-situ polymerized high-concentration salt polymer solid electrolyte, wherein the electrolyte comprises a polymer electrolyte, a high-concentration lithium salt, a suitable additive or / and an initiator. The high-concentration salt polymer solid electrolyte is prepared by in-situ polymerization of an organic solvent in a battery initiated by lithium salt or an initiator.

[0043] When an initiator is used for initiation, the initiator is Al(OTf) 3 , polysulfide, and the polymerization reaction proceeds directly at room temperature without the need for additional initiation conditions.

[0044] The additive is LiNO 3 One or more substances that can slow down the polymerization reaction, such as LiTFSI, are used to slow down the rate of DOL ring-opening polymerization.

[0045] In the present application, the lithium-ion battery uses an in-situ polymerization method to prepare a high-concentration salt polymer solid electrolyte.

[0046] The specific preparation process is as follows: prepare a precursor solution of a high-concentration salt polymer solid electrolyte, soak the diaphragm in the precursor solution for 2 to 60 seconds, preferably 5 to 30 seconds, and then assemble it into a battery for in-situ polymerization to obtain a lithium-ion battery using a high-concentration salt polymer solid electrolyte. The polymerization time is 10 minutes to 12 hours.

[0047] The present invention relates to an in-situ polymerized high-concentration salt polymer solid electrolyte and a lithium ion battery containing the electrolyte. The in-situ polymerized high-concentration salt polymer solid electrolyte contains one or more lithium salts; the in-situ polymerized high-concentration salt polymer solid electrolyte contains one or more polymers that can be used for lithium ion conduction; the in-situ polymerized high-concentration salt polymer solid electrolyte is used for electrode materials with a volume change of more than 50% during charging and discharging, and a lithium ion battery assembled using the same.

[0048] The in-situ polymerized high-concentration salt polymer solid electrolyte of the present invention has good interface contact with the electrode, thereby optimizing ion transmission at the interface; the in-situ polymerized high-concentration salt polymer solid electrolyte has a high lithium salt concentration, thereby ensuring good ion conduction in the electrolyte and improving the rate performance of the battery; due to the poor fluidity of the polymer, the construction site of the solid electrolyte interphase (SEI) is moved from the surface of the electrode particles to the interface of the electrode / electrolyte, where the volume change rate is much smaller than the particle surface, thereby essentially avoiding the huge stress of volume expansion on the SEI; at the same time, the high salt concentration improves the Li + The solvation structure induces the construction of a SEI with a high inorganic phase content, thereby improving the mechanical strength of the SEI. The use of the high-concentration salt polymer solid electrolyte can construct a 2DSEI with high mechanical strength at the electrode / electrolyte interface, improve the stability of the electrode structure and the stability of the SEI, reduce the SEI's fragmentation and reformation and repeated consumption of active substances, and thus improve the cycle stability. Compared with batteries using liquid electrolytes, lithium-ion batteries prepared using this type of high-concentration salt polymer solid electrolyte reduce the SEI's fragmentation and reformation and consumption of active substances, thereby having better cycle stability, and compared with batteries using low-concentration salt polymer solid electrolytes, improve the ion conductivity in the battery and thus have better rate performance.

[0049] The beneficial effects of this application include:

[0050] 1) The preparation process of the high-concentration salt polymer solid electrolyte used in this application is simple;

[0051] 2) The in-situ polymerized high-concentration salt polymer solid electrolyte provided in the present application has better physical contact with the electrode, which is beneficial to improve the interface contact problem between the electrolyte and the solid electrolyte;

[0052] 3) The in-situ polymerized high-concentration salt polymer solid electrolyte provided in this application has poor fluidity, so the construction site of SEI or CEI is transferred from the surface of the particle to the electrode / electrolyte interface, where the volume change is much smaller than that of the particle surface, thereby effectively reducing the breakage of SEI / CEI;

[0053] 4) The in-situ polymerized high-concentration salt polymer solid electrolyte provided in the present application has a high lithium salt concentration, which is beneficial to ion conduction and can improve the rate performance of the battery;

[0054] 5) The high-concentration salt polymer solid electrolyte provided in this application has a high lithium salt concentration. + The solvated structure increases the content of inorganic phase in SEI / CEI, thereby improving the mechanical strength of SEI / CEI;

[0055] 6) The SEI / CEI evolved from the high-concentration salt polymer solid electrolyte used in the present application avoids changes with the particle volume, has high mechanical strength, and thus has high stability, thereby improving the cycle stability of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 For this application DOL+LiNO 3 , Comparative Example 1, Comparative Example 3 and Electronic photographs of the polymerization process of Example 1: 0 min (top) and 2 h (bottom).

[0057] Figure 2 For the DOL of this application, comparative example 1, comparative example 3, example 1 and example 2 1 H NMR spectrum.

[0058] Figure 3 This is a diagram of the key effects of additives in this application.

[0059] Figure 4 This is an electronic photograph of Example 4 of the present application.

[0060] Figure 5 For this application (a is LiNO 3 +DOL, b is the solvated structure in Comparative Example 1 and c is the solvated structure in Example 1).

[0061] Figure 6 This is the XPS spectra of SEI after the first discharge cycle of Comparative Example 1, Comparative Example 3 and Example 1 of the present application.

[0062] Figure 7 The rate performance diagram (left) and cycle performance diagram (right) of Comparative Example 1, Comparative Example 3 and Example 1 of the present application.

[0063] Figure 8 This is the cycle performance diagram of Comparative Example 5 and Example 5 of the present application.

[0064] Fig. 9 This is the cycle performance diagram of Example 2 of the present application.

[0065] Fig.10This is the ion conductance EIS spectrum of the steel-on-steel battery assembled according to Comparative Example 4 and Example 1 of the present application.

[0066] Fig.11 These are SEM images of the electrode cross-sections after cycles of Comparative Example 1 and Example 1 of the present application, with scales of 20 μm and 10 μm, respectively.

[0067] Fig.12 These are SEM images of the electrode surfaces after cycles in Comparative Example 3 and Example 1 of the present application, with a scale of 50 μm.

[0068] Fig.13 This is a comparison chart of electrode thickness before and after cycles of Example 3 and Example 4 of the present application. DETAILED DESCRIPTION

[0069] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0070] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0071] This application uses a nuclear magnetic resonance hydrogen spectrometer (NMR, AVANCE III 400MHz, Switzerland) to measure and analyze the state of different electrolyte / electrolyte solvent molecules. The specific process of sample preparation is as follows: 400 μL of liquid sample is placed in a nuclear magnetic resonance tube, deuterated chloroform (CDCl 3 ) After dissolving the test sample, the H NMR spectrum was collected.

[0072] X-ray photoelectron spectroscopy (XPS) was performed using ESCALAB250xi, Thermo Fisher.

[0073] The battery cycle and rate performance are tested using a Blue Electric charge and discharge instrument.

[0074] The microstructure of the electrode after cycling was observed using a scanning electron microscope (SEM, model: JSM-7800F, QUANTA200FEG).

[0075] Example 1

[0076] 6M LiFSI, small molecule 1,3-dioxolane and 2wt% LiNO 3The precursor solution was mixed and the separator was immersed in the precursor solution for 10 seconds, and then assembled into the battery for in-situ polymerization to obtain a lithium-ion battery using a high-concentration salt polymer solid electrolyte, and the polymerization time was 30 minutes.

[0077] Preparation of Si negative electrode: 0.05g of aqueous binder sodium alginate (SA) was dissolved in 4.5g of deionized water, stirred for 0.5h, then 0.1g of Super P and 0.35g of silicon particles (size 100-300nm) were added and stirred for 5h, then coated on copper foil, the scraper was adjusted to 120μm, and then placed in a 60℃ oven for drying for 8h. The obtained electrode was cut into small discs with a diameter of 10mm and weighed, then vacuum dried at 60℃ for 2h as a negative electrode sheet (the loading of single active material was 1mg cm -2 ).

[0078] Battery assembly process: The battery is assembled in a glove box filled with argon gas with a water and oxygen content of less than 0.01ppm. The battery is assembled in the order of negative electrode shell, electrode sheet, electrolyte + diaphragm or solid electrolyte, electrode sheet, and positive electrode shell. If non-in-situ polymerization is used, the diaphragm soaked in the precursor solution is placed on a polytetrafluoroethylene plate for polymerization for 30 minutes, and the battery is assembled after obtaining the solid electrolyte.

[0079] Among them, the formula of the electrolyte / electrolyte used in the precursor solution (high-concentration salt polymer solid electrolyte) and the polymerization process are shown in Table 1 below. The battery assembly of Examples 1 to 5 and Comparative Examples 1 to 5 is carried out according to the formula and polymerization process shown in Table 1.

[0080] Table 1: Solution / electrolyte formulation and polymerization process

[0081]

[0082] Figure 1 By comparing DOL+LiNO 3 , Comparative Example 1, Comparative Example 3 and Example 1, the states of different electrolyte / electrolyte systems can be intuitively observed ( Figure 1 ). Comparative Example 1 is a uniform liquid electrolyte, Comparative Example 3 is an inhomogeneous and rapidly polymerized solid electrolyte, and Example 1 is a uniform and controllable polymerized high-concentration salt polymer solid electrolyte. (Controllable polymerization).

[0083] Figure 2 By comparing the NMR spectra of DOL, Comparative Example 1, Comparative Example 3, Example 1 and Example 2, the state of the organic solvent in different electrolyte / electrolyte systems can be determined ( Figure 2In comparative example 1, DOL is a small molecule solvent, in comparative example 3, DOL small molecule ring-opening polymerization is formed into poly-DOL, and in examples 1 and 2, poly-DOL and small molecule DOL coexist. (Electrolyte state).

[0084] Figure 3 The DFT theoretical calculations show that LiNO 3 Mechanism of preventing DOL ring-opening polymerization ( Figure 3 The initiator usually reacts with trace water in the electrolyte to generate proton acid to attack the DOL ring opening and further polymerize. 3 - It has a higher binding energy with proton acid, thus stabilizing proton acid to prevent ring-opening polymerization. Therefore, additives (inhibitors) are the key to increasing the salt concentration in the electrolyte system. At the same time, by dissolving the lithium salt in Example 4 and uniformly polymerizing DOL ( Figure 4 ), and the inhibition effect of LiTFSI was also confirmed. (Inhibition mechanism and dissolution of high concentration lithium salt).

[0085] Figure 5 By comparing the solvation structures in different electrolyte / electrolyte systems in Comparative Example 1, Comparative Example 3 and Example 1, it can be found that Li + In the dissolved structure, salt anions dominate, while in the liquid electrolyte, solvent molecules dominate ( Figure 5 ). This means that in the process of high-concentration salt polymer solid electrolyte decomposition to form SEI, more lithium salt decomposes into inorganic components in SEI, so the proportion of inorganic components in the obtained SEI is much higher than that of SEI generated by liquid electrolyte decomposition. This conclusion is consistent with the results of XPS ( Figure 6 ), the proportion of inorganic components in the SEI formed by using high-concentration salt polymer solid electrolyte is significantly higher than that of polymer solid and liquid electrolytes using low-concentration salt. (Advantages of high-concentration lithium salt).

[0086] Therefore, the rate performance and cycle performance of the battery assembled using Example 1 are greatly improved compared with those of Comparative Examples 1 and 3 ( Figure 7 ). Example 1 still shows 2200 mAh g after 100 cycles at 0.2C. -1 The reversible specific capacity is much higher than that of comparative example 1 (900 mAh g -1 ) and Comparative Example 3 (0 mAh g -1 ). Compared with Comparative Example 1 and Example 1, Comparative Example 3 with poor ion conductivity showed higher polarization. In contrast, the higher lithium salt concentration in Example 1 ensured good ion transport in the electrolyte, resulting in less polarization. Therefore, the discharge capacity of Example 1 at 2C was 1765 mAh g -1, compared with Comparative Example 3 (15 mAh g -1 ) has obvious advantages compared with the

[0087] As for the battery in Comparative Example 2, since pressure is required to maintain direct interface contact between electrolyte particles and between electrolyte and electrode during the test of inorganic solid electrolyte, the battery assembled using button cells cannot be tested for electrochemical performance. This fully demonstrates that polymer electrolytes are simpler to operate and have lower testing requirements than inorganic solid electrolytes.

[0088] Similarly, in the lithium-sulfur battery system, after 50 cycles, the capacity retention rate of Example 5 is much higher than that of Comparative Example 5 ( Figure 8 ). The above results further illustrate that the high-concentration salt polymer solid electrolyte strategy is applicable to different solvents and different battery systems.

[0089] like Figure 7 and 9 As shown, through Fig. 9 Embodiment 2 in Figure 7 Comparison of the cycle performance of Comparative Example 1 and Comparative Example 3 ( Figure 7 and Fig. 9 ) It can be seen that the cycle stability of the in-situ polymerized high-concentration salt polymer solid electrolyte with 2M LiFSI is significantly improved compared with Comparative Examples 1 and 3. By comparing the performance of Example 2 with that of Example 1, the content of lithium salt in the electrolyte can be further optimized.

[0090] like Fig.10 As shown, by comparing the electrochemical impedance spectra of Example 1 and Comparative Example 4, it can be seen that the impedance values ​​of the same electrolyte through two different means of in-situ and non-in-situ polymerization are significantly different. The interface contact of the electrode / electrolyte using the in-situ polymerization method is closer, so the ion transport is good, so the impedance of the battery is smaller than that of the battery using non-in-situ polymerization. The above results fully illustrate that the preparation method through in-situ polymerization ensures good ion transport at the electrode / electrolyte interface.

[0091] like Fig.11 and 12 As shown, the surface and cross-sectional morphologies of Comparative Example 1, Comparative Example 3 and Example 1 after cycling were observed by SEM ( Fig.11 , 12). It can be seen that due to the repeated crushing and reformation of SEI, the electrode using liquid electrolyte is occupied by SEI and almost no Si particles can be seen. This is the main reason for the increase in battery polarization and capacity decay. Comparing the surface morphology of Comparative Example 3 and Example 1, it can be found that due to the low content of lithium salt in Comparative Example 3, the content of inorganic components in the generated SEI is low, resulting in poor mechanical properties of SEI, so many cracks are generated during the cycle, while the high mechanical strength SEI in Example 1 remains stable during the cycle.

[0092] like Fig.13 As shown, the change of electrode thickness before and after the cycle of Example 3 and Example 4 ( Fig.13 ), it can be found that the electrode thickness changes of Example 3 and Example 4 before and after the cycle are very small, indicating that few side reactions occur in the electrode, confirming that the in-situ polymerization of high-concentration salt polymer solid electrolytes prepared by adjusting the salt concentration, changing the initiation mode, and changing the inhibitor strategy are feasible.

[0093] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A polymer solid electrolyte, characterized in that: The polymer solid electrolyte comprises a polymer electrolyte, a lithium salt and an additive; The lithium salt initiates in-situ polymerization of the polymer electrolyte; The additive is selected from LiNO3 and / or LiTFSI; The polymer electrolyte includes 1,3-dioxolane and poly-1,3-dioxolane; The poly 1,3-dioxolane is obtained by ring-opening polymerization of 1,3-dioxolane.

2. The polymer solid electrolyte according to claim 1, characterized in that The lithium salt is selected from LiFSI and / or LiPF6; Preferably, the concentration of the lithium salt relative to the 1,3-dioxolane is 2 mol L -1 ~10mol L -1 ; Preferably, the concentration of the lithium salt is 4 mol L relative to the 1,3-dioxolane. -1 ~8mol L -1 .

3. The polymer solid electrolyte according to claim 1, characterized in that: The weight average molecular weight of the poly 1,3-dioxolane is 10,000 to 3,000,000; Preferably, the weight average molecular weight of the poly 1,3-dioxolane is 50,000 to 1,000,000.

4. The polymer solid electrolyte according to claim 1, characterized in that When the additive is LiNO3, the amount of LiNO3 used is 0.2wt.% to 10wt.% of the 1,3-dioxolane; Preferably, when the additive is LiNO3, the amount of LiNO3 used is 1 wt.% to 5 wt.% of the 1,3-dioxolane; Preferably, when the additive is LiTFSI, the concentration of LiTFSI relative to the 1,3-dioxolane is 0.1 mol / L -1 ~5mol L -1 ; Preferably, when the additive is LiTFSI, the concentration of LiTFSI relative to the 1,3-dioxolane is 0.5 mol / L -1 ~2mol L -1 .

5. The polymer solid electrolyte according to claim 1, characterized in that: The polymer solid electrolyte also includes an initiator, which initiates in-situ polymerization of the polymer electrolyte; Preferably, the initiator is selected from Al(OTf)3 and / or polysulfide; Preferably, the amount of the initiator used is 0.5 wt.% to 5 wt.% of the 1,3-dioxolane.

6. The polymer solid electrolyte according to claim 5, characterized in that: When an initiator is used, the lithium salt is selected from at least one of LiTFSI, LiClO4, LiBF4, LiAsF4, and LiCF3SO3.

7. A lithium ion battery, characterized in that: The lithium-ion battery comprises a polymer solid electrolyte, a positive electrode, a negative electrode and a separator; The polymer solid electrolyte is selected from the polymer solid state battery according to any one of claims 1 to 6.

8. The lithium-ion battery according to claim 7, characterized in that: When the lithium-ion battery is charged or discharged, at least one side of the positive electrode or the negative electrode undergoes a volume change; Preferably, the volume change is 50% to 500%; Preferably, if the volume of the positive electrode changes, the positive electrode is a sulfur positive electrode; Preferably, when the volume of the negative electrode changes, the negative electrode is selected from at least one of a silicon negative electrode, a silicon oxide negative electrode, and a lithium negative electrode.

9. The method for preparing a lithium ion battery according to any one of claims 7 or 8, characterized in that: The preparation method comprises: The separator is immersed in a polymer solid electrolyte precursor solution, assembled into a battery for in-situ polymerization, and a lithium-ion battery is obtained; The polymer solid electrolyte precursor solution comprises 1,3-dioxolane, lithium salt and additives.

10. The preparation method according to claim 9, characterized in that: The soaking time is 2 to 60 seconds; Preferably, the soaking time is 5 to 30 seconds; Preferably, the in-situ polymerization time is 10 min to 12 h.

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