A polymer solid-state electrolyte, a lithium ion battery and a preparation method

Abstract

The application discloses a polymer solid electrolyte, a lithium ion battery and a preparation method, the polymer solid electrolyte comprising a polymer electrolyte, a lithium salt and an additive; the lithium salt initiates in-situ polymerization of the polymer electrolyte; and the polymer electrolyte is poly-1,3-dioxolane obtained by ring-opening polymerization of 1,3-dioxolane. The in-situ polymerization high-concentration-salt polymer solid electrolyte has good interface contact with an electrode, so that ion transmission at the interface is optimized; due to poor flowability of the polymer, a construction site of a solid electrolyte interphase (SEI) is moved from a surface of an electrode particle to an electrode / electrolyte interface, a volume change rate at the interface is far less than that at the surface of the particle, and therefore, the SEI essentially avoids bearing a huge stress of volume expansion.

Description

TECHNICAL FIELD

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

[0002] Among commercialized secondary batteries, lithium ion batteries are currently the secondary batteries with the highest energy density, but the theoretical specific capacity of lithium ion batteries based on the "de-intercalation" theory is currently less than 300 mA h g -1 , and the actual energy density is less than 200 Wh kg -1 , which cannot meet the demand of 500 km endurance of electric vehicles. Therefore, it is urgent to develop electrode materials with high theoretical specific capacity. Among new electrode materials, there are materials with high theoretical specific capacity, such as lithium metal negative electrode (3600 mA h g -1 ), silicon negative electrode (4200 mAh g -1 ), sulfur positive electrode (1672 mA h g -1 ) and the like.

[0003] However, among the electrode materials that have been developed relatively maturely or new electrode materials, there are materials that have volume changes in 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% in the process of de-lithiation, the volume change rate of the sulfur positive electrode before and after charging and discharging is 79%, the lithium negative electrode inevitably has volume changes due to its deposition and dissolution charging and discharging mechanism, and the volume change rate of the silicon-based negative electrode before and after charging and discharging is even as high as 400%. More than 50% of the volume change in the charging process will cause the active material particles to fall off from the electrode, lose electrical connection with the electrode, and thus cause loss of active material; on the other hand, it will damage the SEI or CEI in the electrode, causing repeated occurrence of side reactions, and constantly consuming electrolyte and active Li + . Ultimately, it will cause the battery polarization to increase and the capacity to decay.

[0004] Using a solid-state electrolyte with low fluidity, the construction position of the SEI or CEI in the electrode is transferred from the particle surface to the electrode / electrolyte interface, which can effectively avoid the continuous occurrence of side reactions in the electrode. The in-situ polymerized polymer solid-state electrolyte has better physical contact with the electrode compared with other types of solid-state electrolytes, which is beneficial to ion conduction at the interface. In addition, the flexibility of the polymer electrolyte can better adapt to the volume change of the electrode. 1,3-dioxolane (DOL) is a commonly used ether solvent, which can be initiated by a protonic acid and undergo in-situ polymerization to prepare a polymer solid-state electrolyte. However, in the existing DOL strategy, uncontrolled rapid ring-opening polymerization of DOL occurs, resulting in too high a degree of polymerization and poor solubility of lithium salt, which will affect ion transport in the electrolyte. SUMMARY

[0005] The in-situ polymerized high-concentration salt polymer solid-state electrolyte protected by the present application has the following advantages: 1. For the electrode with powder active material, the polymer solid-state electrolyte will transfer the site of SEI / CEI construction from the surface of the particle to the electrode / electrolyte interface, avoiding the change of SEI / CEI following the volume change of the particle and thus reducing the breakage of SEI / CEI; 2. The preparation method of in-situ polymerization ensures good ion transmission at the electrode / electrolyte interface; 3. The addition of appropriate additives (polymerization inhibitors) controls the speed of DOL ring-opening polymerization, realizing the dissolution of high-concentration lithium salt; 4. The high-concentration salt polymer solid-state electrolyte changes the solvation structure of Li + , thus increasing the inorganic component content in the evolved SEI / CEI, thereby enhancing the mechanical strength of SEI / CEI and improving its stability; 5. The high lithium salt concentration in the high-concentration salt polymer solid-state electrolyte ensures the rapid transmission of lithium ions in the electrolyte. Therefore, the lithium ion battery prepared using the high-concentration salt polymer solid-state electrolyte has good cycle stability and rate performance.

[0006] According to one aspect of the present application, a polymer solid-state electrolyte is provided, which comprises 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 LiNO3 and / or LiTFSI;

[0009] The polymer electrolyte comprises 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 LiPF6.

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

[0013] Optionally, the concentration of the lithium salt is independently selected from any value or a range value between any two of the following values: 2 mol L -1 , 4 mol L -1 , 6 mol L -1 , 8 mol L -1 , 10 mol L -1 per 1,3-dioxolane.

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

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

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

[0017] Optionally, when the additive is LiNO3, the amount of LiNO3 is 0.2 wt.% ~ 10 wt.% of the 1,3-dioxolane.

[0018] Optionally, when the additive is LiNO3, the amount of LiNO3 is independently selected from any value or a range between any two values of 0.2 wt.%, 0.5 wt.%, 1 wt.%, 2 wt.%, 5 wt.%, 10 wt.% of the 1,3-dioxolane.

[0019] Optionally, when the additive is LiNO3, the amount of LiNO3 is 1 wt.% ~ 5 wt.% of the 1,3-dioxolane.

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

[0021] Optionally, when the additive is LiTFSI, the concentration of LiTFSI is independently selected from any value or a range between any two values of 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 -1 of the 1,3-dioxolane.

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

[0023] Optionally, the polymer solid-state electrolyte further comprises an initiator, which initiates in-situ polymerization of the polymer electrolyte.

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

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

[0026] Optionally, when an initiator is used, the lithium salt is selected from at least one of LiTFSI, LiClO4, LiBF4, LiAsF4, LiCF3SO3.

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

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

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

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

[0031] Optionally, when the positive electrode undergoes volume change, the positive electrode is a sulfur positive electrode.

[0032] Optionally, when the negative electrode undergoes volume change, the negative electrode is selected from at least one of a silicon negative electrode, a silicon oxide negative electrode, a lithium negative electrode.

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

[0034] immersing the separator in a polymer solid-state electrolyte precursor solution, assembling into a battery to undergo in-situ polymerization, obtaining a lithium ion battery;

[0035] The polymer solid-state electrolyte precursor solution comprises 1,3-dioxolane, a lithium salt and an additive.

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

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

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

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

[0040] Optionally, the in-situ polymerization time 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 embodiment, the present application is implemented by the following technical solutions:

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

[0043] When the initiator is used to initiate, the initiator is one or more of Al(OTf)3 and polysulfides, and the polymerization reaction is directly carried out at room temperature without additional initiation conditions.

[0044] The additive is one or more of LiNO3, LiTFSI and other substances that can slow down the polymerization reaction, which is used to slow down the rate of DOL ring-opening polymerization.

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

[0046] The specific preparation process is as follows: a precursor solution of the high-concentration salt polymer solid-state electrolyte is prepared, a separator is soaked in the precursor solution for 2-60 s, preferably 5-30 s, and then assembled into a battery to occur in-situ polymerization to obtain a lithium ion battery using a high-concentration salt polymer solid-state electrolyte, and the polymerization time is 10 min to 12 h.

[0047] The present application relates to a high-concentration salt polymer solid-state electrolyte prepared by in-situ polymerization and a lithium ion battery comprising the electrolyte. The in-situ polymerization high-concentration salt polymer solid-state electrolyte comprises one or more lithium salts; the in-situ polymerization high-concentration salt polymer solid-state electrolyte comprises one or more polymers that can be used for lithium ion conduction; the in-situ polymerization high-concentration salt polymer solid-state electrolyte is suitable for electrode materials with a volume change of more than 50% during charging and discharging and lithium ion batteries assembled using the same.

[0048] The in-situ polymerization high-concentration salt polymer solid-state electrolyte has good interface contact with the electrode, thereby optimizing ion transmission at the interface; the in-situ polymerization high-concentration salt polymer solid-state electrolyte has high lithium salt concentration, thereby ensuring good ion conduction in the electrolyte and improving the rate performance of the battery; due to the poor flowability of the polymer, the construction site of the solid electrolyte interphase (SEI) is moved from the surface of the electrode particles to the electrode / electrolyte interface, and the volume change rate here is much smaller than that of the particle surface, thereby essentially avoiding the huge stress on the SEI due to volume expansion; at the same time, the high salt concentration improves the solvation structure of Li + in the electrolyte, induces the construction of SEI with high inorganic phase content, and thereby improves the mechanical strength of the SEI; the use of the high-concentration salt polymer solid-state electrolyte can construct a 2D SEI with high mechanical strength at the electrode / electrolyte interface, improves the stability of the electrode structure and the stability of the SEI, reduces the repeated consumption of active materials due to the fragmentation and reformation of the SEI, and therefore improves the cycle stability; the lithium ion battery prepared using the high-concentration salt polymer solid-state electrolyte has better cycle stability compared with the battery using a liquid electrolyte, and has better rate performance compared with the battery using a low-concentration salt polymer solid-state electrolyte.

[0049] The application can produce beneficial effects, including:

[0050] 1) The high-concentration salt polymer solid-state electrolyte used in the application has a simple preparation process;

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

[0052] 3) The in-situ polymerization high-concentration salt polymer solid-state electrolyte provided by the application has poor flowability, so the construction site of the SEI or CEI is transferred from the surface of the particles to the electrode / electrolyte interface, and the volume change here is much smaller than that of the particle surface, thereby effectively reducing the fragmentation of the SEI / CEI;

[0053] 4) The in-situ polymerization high-concentration salt polymer solid-state electrolyte provided by the application has 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-state electrolyte provided by the application has high lithium salt concentration, which changes the solvation structure of Li + and improves the inorganic phase content in the SEI / CEI, thereby improving the mechanical strength of the SEI / CEI;

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

[0056] Figure 1 Electrophotograph of the polymerization process of the DOL+LiNO3 of the present application, Comparative Example 1, Comparative Example 3, and Example 1: 0 min (top) and 2 h (bottom).

[0057] Figure 2 Electrophotograph of the DOL of the present application, Comparative Example 1, Comparative Example 3, Example 1, and Example 2 1 H NMR spectrum.

[0058] Figure 3 Graph of the key role of the additive in the present application.

[0059] Figure 4 Electrophotograph of Example 4 of the present application.

[0060] Figure 5 Solvation structure in the present application (a is LiNO3+DOL, b is Comparative Example 1, and c is Example 1).

[0061] Figure 6 XPS spectrum of the SEI after the first circle discharge of Comparative Example 1, Comparative Example 3, and Example 1 of the present application.

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

[0063] Figure 8 Cycle performance graph of Comparative Example 5 and Example 5 of the present application.

[0064] Figure 9 Cycle performance graph of Example 2 of the present application.

[0065] Figure 10 Ion conductance EIS spectrum of the steel-against-steel battery assembled from Comparative Example 4 and Example 1 of the present application.

[0066] Figure 11 SEM image of the cross section of the electrode after cycling of Comparative Example 1 and Example 1 of the present application, with scales of 20 μm and 10 μm, respectively.

[0067] Figure 12 SEM image of the surface of the electrode after cycling of Comparative Example 3 and Example 1 of the present application, with scales of 50 μm.

[0068] Figure 13The electrode thickness comparison chart before and after the cycle of the present application embodiment 3 and embodiment 4. DETAILED DESCRIPTION

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

[0070] The raw materials in the examples of the present application are all purchased through commercial channels unless otherwise specified.

[0071] The present application uses a nuclear magnetic resonance hydrogen spectrometer (nuclear magnetic resonance, NMR, AVANCE III 400MHz, Switzerland) to measure and analyze the state of different electrolyte / electrolyte solvent molecules. The specific preparation of the sample is as follows: 400μL of liquid sample is placed in a nuclear magnetic tube, and deuterated chloroform (CDCl3) is added to dissolve the test sample before nuclear magnetic hydrogen spectrum collection.

[0072] ESCALAB250xi, Thermo Fisher is used for X-ray photoelectron spectroscopy (X-ray Photoelectron Spectroscopy, XPS) test.

[0073] The blue electric charge-discharge instrument is used to test the cycle and rate performance of the battery.

[0074] The scanning electron microscope (Scanning Electron Microscope, SEM, model: JSM-7800F, QUANTA200FEG) is used to observe the microstructure of the electrode after the cycle.

[0075] Example 1

[0076] 6M LiFSI, small molecule 1,3-dioxolane and LiNO3 with a dosage of 2wt% of 1,3-dioxolane are mixed to form a precursor solution. The separator is soaked in the precursor solution for 10s, and then assembled into a battery to occur in-situ polymerization to obtain a lithium ion battery using a high-concentration salt polymer solid electrolyte, and the polymerization time is 30min.

[0077] Preparation of Si negative electrode: 0.05g of water-based binder sodium alginate (SA) is dissolved in 4.5g of deionized water, after stirring for 0.5h, 0.1g of Super P, 0.35g of silicon particles (size 100-300nm) are added and stirred for 5h, then scraped on a copper foil to form a film, adjust the scraper to 120μm scraping, then put into a 60℃ oven to dry for 8h. The obtained electrode is cut into small round pieces with a diameter of 10mm and weighed, then vacuum dried at 60℃ for 2h, as a negative electrode piece (the loading of single piece active material is 1mg cm -2 ).

[0078] Battery assembly process: Battery assembly is carried out in a glove box filled with argon gas, where the water and oxygen content are both below 0.01 ppm. The battery is assembled in the following order: negative electrode shell, electrode plates, electrolyte + separator or solid electrolyte, electrode plates, positive electrode shell. If non-in-situ polymerization is used, the separator, soaked in the precursor solution, is placed on a polytetrafluoroethylene plate and polymerized for 30 minutes to obtain a solid electrolyte before battery assembly.

[0079] The formulation and polymerization process of the electrolyte / electrolyte used in the precursor solution (high-concentration salt polymer solid electrolyte) are shown in Table 1 below. The batteries of Examples 1 to 5 and Comparative Examples 1 to 5 were assembled according to the formulation and polymerization process shown in Table 1.

[0080] Table 1: Formulation and polymerization process of electrolyte / solvent

[0081]

[0082] Figure 1 By comparing the electron microscope images of DOL+LiNO3, Comparative Example 1, Comparative Example 3, and Example 1, the states of different electrolyte / electrolyte systems can be observed intuitively. Figure 1 Comparative Example 1 is a homogeneous liquid electrolyte, Comparative Example 3 is a heterogeneous and rapidly polymerized solid electrolyte, and Example 1 is a homogeneous, controllably polymerized high-concentration salt polymer solid electrolyte (controllably polymerized).

[0083] Figure 2 In this study, 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 2 In Comparative Example 1, DOL was a small molecule solvent. In Comparative Example 3, small molecule DOL underwent ring-opening polymerization to form polyDOL. Examples 1 and 2 showed a coexistence of polyDOL and small molecule DOL (electrolyte state).

[0084] Figure 3 The mechanism by which LiNO3 inhibits the ring-opening polymerization of DOL was explained through DFT theoretical calculations. Figure 3 Initiators typically react with trace amounts of water in the electrolyte to generate a protic acid that attacks the ring-opening mechanism of DOL, leading to further polymerization. NO3 - It has a higher binding energy with protic acids, thus stabilizing them and preventing ring-opening polymerization. Therefore, additives (polymerization inhibitors) are key to increasing the salt concentration in the electrolyte system. Simultaneously, through the dissolution of lithium salt and the homogeneous polymerization of DOL in Example 4... Figure 4 This also confirms the polymerization inhibition effect of LiTFSI (polymerization inhibition mechanism and dissolution of high-concentration lithium salts).

[0085] Figure 5 In particular, 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 the Li + The salt anion dominates in the solvation structure, while the solvent molecule dominates in the liquid electrolyte. Figure 5 This means that in the process of decomposition of high-concentration salt polymer solid-state electrolyte to form SEI, more lithium salt is decomposed into inorganic components in SEI, so that the proportion of inorganic components in the obtained SEI is much higher than that of SEI formed by decomposition of liquid electrolyte, which 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-state electrolyte is significantly higher than that of the polymer solid-state electrolyte using low-concentration salt and liquid electrolyte. (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 Comparative Example 1 and Comparative Example 3. Figure 7 Example 1 still shows a reversible specific capacity of 2200 mAh g -1 after 100 cycles at 0.2C, which 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 shows higher polarization. In contrast, the high lithium salt concentration in Example 1 ensures good ion transport within the electrolyte, resulting in less polarization. Therefore, the discharge capacity of Example 1 at 2C is 1765 mAh g -1 , which has a significant advantage over Comparative Example 3 (15 mAh g -1 ).

[0087] However, the battery in Comparative Example 2 cannot be tested for electrochemical performance because it uses a button cell, which cannot maintain the contact between electrolyte particles and the interface between electrolyte and electrode under pressure during the test of inorganic solid-state electrolyte. This fully illustrates that the polymer electrolyte is easier to operate and has lower testing requirements compared with inorganic solid-state.

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

[0089] As shown in Figure 7 and 9 , by Figure 9 Example 2, Figure 7Comparative Example 1 and Comparative Example 3 in the cycle performance of the contrast Figure 7 and Figure 9 It can be seen that the in-situ polymerized high-concentration salt polymer solid electrolyte with 2M LiFSI has obvious improvement in cycle stability compared with Comparative Example 1 and 3. Through the performance comparison of Example 2 and Example 1, the content of lithium salt in the electrolyte can be further optimized.

[0090] As shown in Figure 10 , by comparing the electrochemical impedance spectrograms of Comparative Example 1 and Comparative Example 4, it can be seen that the same electrolyte has obvious difference in impedance value through two different means of in-situ and non-in-situ polymerization. The interface contact of the electrode / electrolyte is closer by using the in-situ polymerization method, so the ion transmission is good, and therefore the impedance of the battery is smaller than that of the battery using non-in-situ polymerization. The above results fully demonstrate that the preparation method by in-situ polymerization ensures good ion transmission at the electrode / electrolyte interface.

[0091] As shown in Figure 11 and 12 , the surface and cross-sectional morphology of Comparative Example 1, Comparative Example 3 and Example 1 after cycling are observed by SEM Figure 11 , 12 It can be seen that the electrode using liquid electrolyte has almost no Si particles occupied by SEI due to repeated breaking and reforming of SEI, which is the main reason for the increase of battery polarization and capacity decay. By comparing the surface morphology of Comparative Example 3 and Example 1, it can be found that the content of inorganic components in the SEI generated in Comparative Example 3 is low due to the low content of lithium salt, which leads to poor mechanical properties of SEI and therefore many cracks are generated in the process of cycling, while the high mechanical strength SEI in Example 1 remains stable in the process of cycling.

[0092] As shown in Figure 13 , by the change of electrode thickness before and after cycling of Example 3 and Example 4 Figure 13 , it can be found that the electrode thickness of Example 3 and Example 4 changes very little before and after cycling, which indicates that there are few side reactions occurring in the electrode, confirming that the in-situ polymerized high-concentration salt polymer solid electrolyte prepared by adjusting the salt concentration, changing the initiation method and changing the polymerization inhibitor strategy is feasible.

[0093] The above is only a few embodiments of the present application, and does not limit the present application in any form. Although the above is disclosed as a preferred embodiment, it is not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, which are equivalent to equivalent embodiments and belong to the scope of the technical solution.

Claims

1. A polymer solid-state electrolyte, characterized by, The polymer solid-state electrolyte comprises a polymer electrolyte, a lithium salt and an additive; The lithium salt initiates in-situ polymerization of 1,3-dioxolane; The additive is selected from LiNO3; The polymer electrolyte comprises 1,3-dioxolane and poly-1,3-dioxolane; The poly-1,3-dioxolane is obtained by ring-opening polymerization of 1,3-dioxolane; the concentration of the lithium salt is 2 mol L relative to the 1,3-dioxolane -1 10 mol L -1 ; The amount of LiNO3 is 0.2 wt.% to 10 wt.% of the 1,3-dioxolane.

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

3. The polymer solid-state electrolyte according to claim 1, wherein The weight average molecular weight of the poly-1,3-dioxolane is 10,000 to 3,000,000.

4. The polymer solid-state electrolyte of claim 1, wherein The weight average molecular weight of the poly-1,3-dioxolane is 50,000 to 1,000,000.

5. The polymer solid-state electrolyte of claim 1, wherein, The amount of LiNO3 is 1 wt.% to 5 wt.% of the 1,3-dioxolane.

6. The polymer solid-state electrolyte of claim 1, wherein The polymer solid-state electrolyte further comprises an initiator, which initiates in-situ polymerization of 1,3-dioxolane.

7. The polymer solid-state electrolyte according to claim 6, wherein The initiator is selected from Al(OTf)3 and / or polysulfide.

8. The polymer solid-state electrolyte of claim 6, wherein, The amount of the initiator is 0.5 wt.% to 5 wt.% of the 1,3-dioxolane.

9. The polymer solid-state electrolyte of claim 6, wherein, When an initiator is used, the lithium salt is selected from at least one of LiTFSI, LiClO4, LiBF4, LiAsF4, and LiCF3SO3.

10. A lithium-ion battery, characterized by, The lithium ion battery comprises a polymer solid-state electrolyte, a positive electrode, a negative electrode and a separator; The polymer solid-state electrolyte is selected from any one of the polymer solid-state electrolytes of claims 1 to 9.

11. The lithium-ion battery of claim 10, wherein, At least one of the positive electrode or the negative electrode undergoes volume change when the lithium ion battery is charged or discharged.

12. The lithium-ion battery of claim 11, wherein, The volume change is 50% to 500%.

13. The lithium-ion battery of claim 11, wherein, When the positive electrode undergoes volume change, the positive electrode is a sulfur positive electrode.

14. The lithium-ion battery of claim 11, wherein, When the negative electrode undergoes volume change, the negative electrode is selected from at least one of a silicon negative electrode, a silicon oxide negative electrode and a lithium negative electrode.

15. The method of producing a lithium-ion battery according to any one of claims 10 to 14, characterized in that, The preparation method comprises: immersing a separator in a polymer solid-state electrolyte precursor solution, assembling into a battery to undergo in-situ polymerization, and obtaining a lithium ion battery; The polymer solid-state electrolyte precursor solution comprises 1,3-dioxolane, a lithium salt and an additive.

16. The method of claim 15, wherein, The immersion time is 2 to 60 seconds.

17. The preparation method according to claim 15, characterized in that, The immersion time is 5 to 30 seconds.

18. The method of claim 15, wherein, The in-situ polymerization time is 10 minutes to 12 hours.

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