A high-performance solid electrolyte with in-situ self-polymerization, its preparation method and application

Abstract

This invention discloses a high-performance solid electrolyte with in-situ self-polymerization, its preparation method, and its applications. The electrolyte comprises a mixed precursor solution of self-polymerizing monomers, lithium salts, organic solvents, and a thermal initiator, prepared via a one-step thermally initiated in-situ curing process. The resulting electrolyte exhibits high room-temperature ionic conductivity (>10). –4 S cm –1 ), wide electrochemical window (>4.6 V vs Li) + It exhibits excellent interfacial stability and good stability over a wide temperature range (-20℃~45℃), and when applied to high-voltage lithium-ion batteries (such as the Gr||NCM811 system), it demonstrates high coulombic efficiency and long cycle life, effectively solving the problems of leakage and flammability / explosion associated with traditional liquid electrolytes, thus possessing significant prospects for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage materials technology, specifically relating to a high-performance solid electrolyte with in-situ self-polymerization, its preparation method, and its application. Background Technology

[0002] With the rapid development of electric vehicles and large-scale energy storage systems, unprecedentedly high standards have been placed on the energy density, safety performance, and cycle life of lithium-ion batteries. To improve battery energy density, the industry widely adopts high-voltage lithium cobalt-nickel-manganese oxide (such as LiNi) batteries. 0.8 Co 0.1 Mn 0.1 Positive electrode material systems such as O2. However, the operating voltage of such materials typically exceeds 4.3 V (relative to Li). + The lithium carbonate (LCC) exceeds the upper limit of the electrochemical stability window of traditional liquid carbonate electrolytes. In practical applications, liquid electrolytes undergo continuous oxidative decomposition under high voltage, which not only forms an unstable positive electrode electrolyte interface film on the positive electrode surface, consuming the active lithium source and leading to increased battery internal resistance and rapid capacity decay, but also triggers electrolyte decomposition and gas production, resulting in serious safety hazards such as battery swelling, increased internal pressure, and even thermal runaway.

[0003] To fundamentally address the safety and voltage bottlenecks of liquid electrolytes, solid-state electrolytes are considered an ideal choice for next-generation battery technology. Among various solid-state electrolytes, polymer solid-state electrolytes have attracted much attention due to their excellent film-forming properties, flexibility, and good interfacial contact with electrodes. Currently, polyethylene oxide (PEO)-based electrolytes are one of the most widely studied systems, but they have two inherent drawbacks: First, the crystallization tendency of PEO leads to its generally low ionic conductivity at room temperature (typically below 10). –4 S cm –1 Firstly, it is difficult to meet the requirements of high-rate charge and discharge. Secondly, the electrochemical stability of the ether oxygen bond in PEO-based electrolyte is poor, and its oxidation resistance voltage window is usually less than 4.0 V, which cannot match the aforementioned high-voltage cathode materials, greatly limiting its application in high-voltage batteries.

[0004] To address the aforementioned issues, various modification schemes have been proposed in the prior art, but all of these schemes have significant shortcomings. For example, some technical solutions (such as Chinese Patent CN202510091775.2) improve the mechanical strength and electrochemical stability of the polymer backbone by introducing external crosslinking agents (such as trifluoroethyl methacrylate). However, such external crosslinking agents not only increase the complexity of the formulation and the cost of raw materials, but may also introduce uncontrollable side reaction sites in the electrolyte system, affecting the long-term cycle stability and interfacial compatibility of the battery. Other technical solutions (such as Chinese Patent CN202510114144.8) focus on complex chemical grafting modification of natural polymers (such as sodium alginate) (e.g., using glycidyl methacrylate, GMA), but such modification processes are cumbersome, the reaction conditions are harsh, and the purity and batch stability of the modified products are difficult to guarantee, which is not conducive to large-scale industrial production.

[0005] In summary, existing polymer electrolyte systems generally face the dilemma of balancing performance and process: for example, PEO-based electrolytes cannot meet the requirements of high-voltage applications due to their intrinsic properties; however, improving a certain aspect of performance by introducing complex external components or cumbersome modification steps sacrifices the simplicity, stability and economy of the system. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0008] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a high-performance solid electrolyte with in-situ self-polymerization, its preparation method, and its application.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a high-performance solid electrolyte based on self-polymerizing monomers, comprising, wherein the electrolyte is prepared by in-situ thermosetting reaction of a mixed precursor liquid containing self-polymerizing monomers, lithium salts, organic solvents and thermal initiators; wherein the self-polymerizing monomers simultaneously serve as monomers and crosslinking agents during the polymerization process.

[0010] As a preferred embodiment of the high-performance solid electrolyte of the present invention, the self-polymerizing monomer is an alkylene oxide compound containing a double bond, including one of glycidyl methacrylate, glycidyl acrylate, 1,2-epoxy-9-decene, 1,2-epoxy-5-hexene, epoxybutene, and 3-(allyloxy)oxetane.

[0011] As a preferred embodiment of the high-performance solid electrolyte of the present invention, the lithium salt includes one or more of lithium difluorooxalate borate, lithium difluorosulfonylimide, lithium trifluoromethanesulfonate, and lithium hexafluorophosphate.

[0012] As a preferred embodiment of the high-performance solid electrolyte of the present invention, the organic solvent includes one or more of ethylene carbonate, fluoroethylene carbonate, propylene carbonate, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, and ethyl butyrate.

[0013] As a preferred embodiment of the high-performance solid electrolyte of the present invention, the thermal initiator includes one of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, and dibenzoyl peroxide.

[0014] As a preferred embodiment of the high-performance solid electrolyte of the present invention, the mixed precursor liquid comprises, by mass percentage: 5%-20% self-polymerizing monomer, 10%-15% lithium salt, 64%-84% organic solvent, and 0.1%-1% thermal initiator.

[0015] As a preferred embodiment of the high-performance solid electrolyte of the present invention, the in-situ thermosetting reaction temperature is 40-80℃ and the reaction time is 6-24 hours.

[0016] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a high-performance solid electrolyte, comprising:

[0017] In an inert atmosphere, lithium salts are dissolved in an organic solvent to prepare a basic electrolyte.

[0018] Add monomers and thermal initiators to the base electrolyte and stir until completely dissolved to obtain a homogeneous and transparent mixed precursor solution;

[0019] The mixed precursor solution is injected into the battery casing and placed in an environment of 40-80℃ for thermally initiated curing reaction. After the reaction is complete, a high-performance solid electrolyte is obtained.

[0020] In a preferred embodiment of the preparation method described in this invention, the battery casing is pre-formed with positive and negative electrode plates and a separator to achieve in-situ forming of the electrolyte.

[0021] Another objective of this invention is to overcome the shortcomings of the prior art and provide a lithium secondary battery comprising a positive electrode, a negative electrode, a separator, and a high-performance solid electrolyte as described in any one of claims 1-7; wherein the positive electrode is a high-voltage positive electrode material, including but not limited to lithium nickel cobalt manganese oxide, lithium-rich manganese-based materials, or polyanionic positive electrode; and wherein the negative electrode includes but is not limited to a metallic lithium negative electrode, a graphite negative electrode, or a silicon-carbon composite negative electrode.

[0022] Beneficial effects of this invention:

[0023] (1) This invention utilizes the characteristic that alkyl oxidants containing double bonds contain both double bonds and epoxy groups. Under thermal initiation, the double bonds undergo free radical polymerization to form the main chain, while the epoxy groups can react with components in the system (such as lithium salt decomposition products) to undergo ring-opening polymerization, spontaneously forming a three-dimensional cross-linked network without the need for any additional cross-linking agents.

[0024] (2) The electrolyte obtained in this invention has high room temperature ionic conductivity (>1×10⁻⁶). –4 S cm –1 It features a wide electrochemical window (>4.6 V). The introduction of LiDFOB and FEC synergistically contributes to the construction of a stable BF- and LiF-rich CEI / SEI film, further enhancing interfacial stability, making it particularly suitable for high-voltage cathodes such as NCM811.

[0025] (3) The present invention adopts a one-step thermally initiated in-situ polymerization process, which is simple, mild, and does not require ultraviolet light equipment. It is suitable for battery designs of various shapes and is easy to scale up for production, with broad prospects for industrialization.

[0026] (4) The present invention uses this electrolyte in Gr||NCM811 batteries, which exhibit excellent cycle stability (>300 cycles, capacity retention >82%) at a high cutoff voltage of 4.45 V, solving the application bottleneck of traditional liquid systems and complex polymer systems at high voltage. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0028] Figure 1 This is a photograph of the solid electrolyte prepared in Example 1 of the present invention.

[0029] Figure 2The infrared spectrum is that of the solid electrolyte prepared in Example 1 of this invention.

[0030] Figure 3 Linear sweep voltammetry (LSV) curves of the solid electrolyte prepared in the embodiments of the present invention.

[0031] Figure 4 The graph shows the long-cycle performance of the Gr||NCM811 battery assembled with the solid electrolyte prepared in the embodiment of the present invention at room temperature and 1.0 C rate.

[0032] Figure 5 The graph shows the cycling performance of the Gr||NCM811 battery assembled with the solid electrolyte prepared in Example 1 of this invention at 45°C.

[0033] Figure 6 The graphs show the charge-discharge curves of the Gr||NCM811 battery assembled with the solid electrolyte prepared in Example 1 of the present invention at room temperature and -20°C.

[0034] Figure 7 The graph shows the long-cycle performance of the Gr||NCM811 battery assembled with the solid electrolyte prepared in the comparative example of this invention at room temperature and 1.0 C rate. Detailed Implementation

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0036] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0037] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0038] Unless otherwise specified, all raw materials used in the embodiments of this invention are commercially available. See Table 1 for details.

[0039] Table 1

[0040]

[0041] The specific performance testing conditions for the electrolytes prepared in the examples and comparative examples of this invention are as follows:

[0042] Linear scan voltammetry: Linear scan voltammetry was performed using a DH7000 electrochemical workstation. First, the working electrode SP@Al, separator, and reference electrode lithium sheet were placed in a coin cell casing, 50 μL of precursor solution was injected, and the casing was sealed. Then, the casing was transferred to a 60℃ drying oven for 6 hours to complete in-situ polymerization and curing. Next, the battery was connected to the electrochemical workstation, with an initial potential of 3 V, an end potential of 6 V, and a scan rate of 10 mV / s. The scan was then started, and the current-potential variation was recorded to generate a voltammetry curve. Finally, the voltammetry curve was analyzed to evaluate the battery's electrochemical performance.

[0043] Lithium-ion conductivity test: The lithium-ion conductivity was tested using a DH7000 electrochemical workstation. First, the electrode SS, separator, and electrode SS were placed in the coin cell case, 50 μL of precursor solution was injected and sealed, and then transferred to a 60℃ forced-air drying oven for 6 hours to complete in-situ polymerization and curing; then the battery was connected to the electrochemical workstation, and the AC impedance test parameters were set, with an AC voltage disturbance of 10 mV and a frequency range of 100000-0.1Hz, and the impedance data was recorded; the conductivity of the electrolyte was calculated based on the impedance data, and the formula (1) is:

[0044] σ=L / (R×S)(1)

[0045] Where L is the electrolyte membrane thickness, R is the impedance value, and S is the electrode area.

[0046] Room temperature charge-discharge cycle test: A room temperature charge-discharge cycle test was conducted using a Xinwei battery tester. First, the positive electrode NCM811, separator, and negative electrode graphite were placed into a coin cell casing, 50 μL of precursor solution was injected, and the casing was sealed. Then, it was transferred to a 60℃ forced-air drying oven for 6 hours to complete in-situ polymerization and curing. Next, the charge-discharge test steps were set: charging cut-off voltage 4.45V, discharging cut-off voltage 2.8V, and discharge at 0.1 C (1 C = 220 mAh g⁻¹). –1 The battery was activated by one constant current charge-discharge cycle, one 0.3 C constant current charge / 0.3 C constant current discharge cycle, and one 0.5 C constant current charge / 0.5 C constant current discharge cycle. Subsequent long cycles were performed using a 1.0 C constant current / constant voltage charge / 1.0 C constant current discharge cycle. The corresponding time, voltage, current, and capacity data were recorded. The capacity retention rate (%) after the Nth cycle is calculated as: (Nth discharge specific capacity / First discharge specific capacity at 1.0 C) × 100%.

[0047] High / Low Temperature Charge-Discharge Cycling Test: Low-temperature charge-discharge cycle tests were conducted using a Xinwei battery tester and a Shanghai Yiheng high / low temperature test chamber. First, the positive electrode NCM811, separator, and negative electrode graphite were placed into a coin cell casing, 50 μL of precursor solution was injected, and the casing was sealed. Then, it was transferred to a 60℃ forced-air drying oven for 6 hours to complete in-situ polymerization and curing. Next, a -20℃ charge-discharge test was performed: charging cut-off voltage 4.45 V, discharging cut-off voltage 2.8 V, and discharge at room temperature at 0.1 C (1 C = 220 mAh g). –1 The battery was activated by two constant current charge-discharge cycles and two cycles of 0.3 C constant current charging / discharging. Subsequently, it was charged and discharged in a -20°C chamber using 0.1 C constant current charging / discharging and 0.3 C constant current / constant voltage charging / discharging. The corresponding time, voltage, current, and capacity data were recorded. For the 45°C charge-discharge test, the charging cutoff voltage was set to 4.45 V and the discharging cutoff voltage to 2.8 V. At room temperature, the battery was activated by two cycles of 0.1 C constant current charging / discharging and two cycles of 0.3 C constant current charging / discharging. Subsequently, it was activated in a 45°C high-temperature chamber using two cycles of 0.1 C constant current charging / discharging, two cycles of 0.3 C constant current charging / discharging, and two cycles of 0.5 C constant current charging / discharging. Subsequent long-cycle tests were performed using 1.0 C constant current / constant voltage charging / 1.0 C constant current discharging. Finally, the corresponding data such as time, voltage, current, and capacity are recorded.

[0048] Constant current charge and discharge test: The constant current charge and discharge test is a test method to evaluate battery performance. The battery is charged with a set constant current (such as 1.0 C) until it reaches the preset voltage. After charging is completed, the battery is left to stand for a period of time. The battery is then discharged with a set constant current (such as 1.0 C) until the voltage drops to the preset value.

[0049] Example 1

[0050] (1) Preparation of precursor solution: In an argon glove box, 1.00 g LiDFOB was dissolved in a mixed solvent consisting of 2.23 g FEC and 5.10 g EMC, and the mixture was magnetically stirred until completely dissolved. Then, 1.00 g GMA monomer and 0.09 g AIBN initiator were added, and the mixture was stirred until completely dissolved to obtain a homogeneous and transparent mixed precursor solution.

[0051] (2) In-situ curing: The above-mentioned precursor liquid is injected into the button cell with NCM811 as the positive electrode and graphite as the negative electrode. After sealing, it is transferred to a 60°C forced-air drying oven for 6 hours to complete the in-situ polymerization curing, thus obtaining the solid-state battery.

[0052] Table 2

[0053]

[0054] Table 2 shows the components of the mixed precursor solution. Figure 1 This is a photograph of the solid electrolyte prepared in Example 1 of the present invention. Figure 2 The infrared spectrum is that of the solid electrolyte prepared in Example 1 of this invention.

[0055] Performance testing: LSV testing showed that its antioxidant capacity reached 4.64 V (see...). Figure 3 The assembled Gr||NCM811 battery retained 82.8% of its capacity after 300 cycles at a cutoff voltage of 4.45 V and a rate of 1.0 C (see...). Figure 4 Gr||NCM811 maintained 80.2% capacity retention after 173 cycles at 1.0°C and 45°C. (See...) Figure 5 Gr||NCM811 achieves 76.9% of its room temperature discharge capacity at the same rate at 0.1°C and -20°C, and 71.2% at the same rate at 0.3°C and -20°C. (See...) Figure 6 )

[0056] Example 2

[0057] (1) Preparation of precursor solution: In an argon glove box, 1.00 g LiDFOB was dissolved in a mixed solvent consisting of 2.23 g FEC and 5.10 g EMC, and magnetically stirred until completely dissolved. Then 1.99 g GMA monomer and 0.10 g AIBN initiator were added, and stirring was continued until completely dissolved to obtain a homogeneous and transparent mixed precursor solution.

[0058] (2) In-situ curing: The above-mentioned precursor liquid is injected into the button cell with NCM811 as the positive electrode and graphite as the negative electrode. After sealing, it is transferred to a 60°C forced-air drying oven for 6 hours to complete the in-situ polymerization curing, thus obtaining the solid-state battery.

[0059] Table 3

[0060]

[0061] Table 3 shows the components of the mixed precursor solution.

[0062] Performance testing: LSV testing showed that its antioxidant capacity reached 4.67 V (see...). Figure 3 The assembled Gr||NCM811 battery retained 80.4% of its capacity after 300 cycles at a cutoff voltage of 4.45 V and a rate of 1.0 C (see...). Figure 4 ).

[0063] Example 3

[0064] (1) Preparation of precursor solution: In an argon glove box, 2.13 g LiPF6 was dissolved in a mixed solvent consisting of 2.23 g FEC and 5.10 g EMC, and the mixture was magnetically stirred until completely dissolved. Then, 1.00 g GMA monomer and 0.10 g AIBN initiator were added, and the mixture was stirred until completely dissolved to obtain a homogeneous and transparent mixed precursor solution.

[0065] (2) In-situ curing: The above-mentioned precursor liquid is injected into the button cell with NCM811 as the positive electrode and graphite as the negative electrode. After sealing, it is transferred to a 60°C forced-air drying oven for 6 hours to complete the in-situ polymerization curing, thus obtaining the solid-state battery.

[0066] Table 4

[0067]

[0068] Table 4 shows the components of the mixed precursor solution.

[0069] Performance testing: LSV testing showed that its antioxidant capacity reached 4.61 V (see...). Figure 3 The assembled Gr||NCM811 battery, after 126 cycles at a cutoff voltage of 4.45 V and a rate of 1.0 C, retained only 80.2% of its capacity (see...). Figure 4 ).

[0070] Comparative Example 1

[0071] (1) Preparation of precursor solution: In an argon glove box, 1.00 g LiDFOB was dissolved in a mixed solvent consisting of 2.23 g FEC and 5.10 g EMC, and the mixture was magnetically stirred until completely dissolved. Then, 2.98 g GMA monomer and 0.11 g AIBN initiator were added, and the mixture was stirred until completely dissolved to obtain a homogeneous and transparent mixed precursor solution.

[0072] (2) In-situ curing: The above-mentioned precursor liquid is injected into the button cell with NCM811 as the positive electrode and graphite as the negative electrode. After sealing, it is transferred to a 60°C forced-air drying oven for 6 hours to complete the in-situ polymerization curing, thus obtaining the solid-state battery.

[0073] Table 5

[0074]

[0075] Table 5 shows the components of the mixed precursor solution.

[0076] Performance testing: After 111 cycles at a cutoff voltage of 4.45 V and a rate of 1.0 C, the assembled Gr||NCM811 battery retained 80.2% of its capacity (see...). Figure 7).

[0077] Comparative Example 2

[0078] (1) Preparation of precursor solution: In an argon glove box, 1.06 g LiPF6 was dissolved in a mixed solvent consisting of 2.23 g FEC and 5.10 g EMC, and the mixture was magnetically stirred until completely dissolved. Then, 1.00 g GMA monomer and 0.09 g AIBN initiator were added, and the mixture was stirred until completely dissolved to obtain a homogeneous and transparent mixed precursor solution.

[0079] (2) In-situ curing: The above-mentioned precursor liquid is injected into the button cell with NCM811 as the positive electrode and graphite as the negative electrode. After sealing, it is transferred to a 60°C forced-air drying oven for 6 hours to complete the in-situ polymerization curing, thus obtaining the solid-state battery.

[0080] Table 6

[0081]

[0082] Table 6 shows the components of the mixed precursor solution.

[0083] Performance testing: After 26 cycles at a cutoff voltage of 4.45 V and a rate of 1.0 C, the assembled Gr||NCM811 battery retained only 81.0% of its capacity (see...). Figure 7 ).

[0084] Comparative Example 3

[0085] (1) Preparation of precursor solution: In an argon glove box, 3.19 g LiPF6 was dissolved in a mixed solvent consisting of 2.23 g FEC and 5.10 g EMC, and magnetically stirred until completely dissolved. Then 1.00 g GMA monomer and 0.12 g AIBN initiator were added, and stirring was continued until completely dissolved to obtain a homogeneous and transparent mixed precursor solution.

[0086] (2) In-situ curing: The above-mentioned precursor liquid is injected into the button cell with NCM811 as the positive electrode and graphite as the negative electrode. After sealing, it is transferred to a 60°C forced-air drying oven for 6 hours to complete the in-situ polymerization curing, thus obtaining the solid-state battery.

[0087] Table 7

[0088]

[0089] Table 7 shows the components of the mixed precursor solution.

[0090] Performance testing: The assembled Gr||NCM811 battery showed almost no discharge capacity during cycling at a cutoff voltage of 4.45 V and a rate of 1.0 C (see...). Figure 7 ).

[0091] Comparative Example 4

[0092] (1) Preparation of precursor solution: In an argon glove box, 1.00 g LiDFOB was dissolved in a mixed solvent consisting of 7.85 g EC and 4.41 g DMC, and magnetically stirred until completely dissolved. Then 1.00 g GMA monomer and 0.08 g AIBN initiator were added, and stirring was continued until completely dissolved to obtain a homogeneous and transparent mixed precursor solution.

[0093] (2) In-situ curing: The above-mentioned precursor liquid is injected into the button cell with NCM811 as the positive electrode and graphite as the negative electrode. After sealing, it is transferred to a 60°C forced-air drying oven for 6 hours to complete the in-situ polymerization curing, thus obtaining the solid-state battery.

[0094] Table 8

[0095]

[0096] Table 8 shows the components of the mixed precursor solution.

[0097] Performance testing: After 200 cycles at a cutoff voltage of 4.45 V and a rate of 1.0 C, the assembled Gr||NCM811 battery retained 83.1% of its capacity (see...). Figure 7 ).

[0098] Comparative Example 5

[0099] (1) Preparation of precursor solution: In an argon glove box, 1.00 g LiDFOB was dissolved in a mixed solvent consisting of 0.62 g EC and 5.68 g DMC, and the mixture was magnetically stirred until completely dissolved. Then, 1.00 g GMA monomer and 0.08 g AIBN initiator were added, and the mixture was stirred until completely dissolved to obtain a homogeneous and transparent mixed precursor solution.

[0100] (2) In-situ curing: The above-mentioned precursor liquid is injected into the button cell with NCM811 as the positive electrode and graphite as the negative electrode. After sealing, it is transferred to a 60°C forced-air drying oven for 6 hours to complete the in-situ polymerization curing, thus obtaining the solid-state battery.

[0101] Table 9

[0102]

[0103] Table 9 shows the components of the mixed precursor solution.

[0104] Performance testing: After 200 cycles at a cutoff voltage of 4.45 V and a rate of 1.0 C, the assembled Gr||NCM811 battery retained 79.1% of its capacity (see...). Figure 7 ).

[0105] Comparative Example 6

[0106] (1) Preparation of precursor solution: In an argon glove box, 2.01 g LiDFOB was dissolved in a mixed solvent consisting of 2.14 g PC and 5.79 g DEC, and the mixture was magnetically stirred until completely dissolved. Then, 1.00 g GMA monomer and 0.11 g AIBN initiator were added, and the mixture was stirred until completely dissolved to obtain a homogeneous and transparent mixed precursor solution.

[0107] (2) In-situ curing: The above-mentioned precursor liquid is injected into the button cell with NCM811 as the positive electrode and graphite as the negative electrode. After sealing, it is transferred to a 60°C forced-air drying oven for 6 hours to complete the in-situ polymerization curing, thus obtaining the solid-state battery.

[0108] Table 10

[0109]

[0110] Table 10 shows the components of the mixed precursor solution.

[0111] Performance testing: After 200 cycles at a cutoff voltage of 4.45 V and a rate of 1.0 C, the assembled Gr||NCM811 battery retained 81.2% of its capacity (see...). Figure 7 ).

[0112] Linear scan voltammetry:

[0113] The Li||SP@Al batteries obtained in Examples 1, 2, and 3 were subjected to linear scan voltammetry tests at room temperature, with a scan range of 3-6 V and a scan rate of 10 mV / s. Figure 3 As shown, the oxidation potentials of the solid electrolytes prepared in the examples are all greater than 4.6 V, which makes them suitable for high-voltage, high-nickel cathode materials.

[0114] Room temperature charge-discharge cycle test:

[0115] Cycling performance tests were conducted at room temperature using the Gr||NCM811 batteries obtained in Examples 1, 2, and 3, with a charging cutoff voltage of 4.45 V and a discharging cutoff voltage of 2.8 V, respectively, at 0.1 C (1 C = 220 mAh g). –1 The battery was activated by one constant current charge / discharge cycle, one 0.3 C constant current charge / 0.3 C constant current discharge cycle, and one 0.5 C constant current charge / 0.5 C constant current discharge cycle. Subsequent long cycles were performed with a 1.0 C constant current / constant voltage charge / 1.0 C constant current discharge cycle. Figure 4 As shown, Example 1 exhibits a discharge specific capacity of 196.7 mAh g at 1.0 C. –1After 300 cycles, the capacity retention rate was 82.8%. Example 2 showed a discharge specific capacity of 198.9 mAh g at 1.0 C. –1 After 300 cycles, the capacity retention rate was 80.4%. Example 3 showed a discharge specific capacity of 191.5 mAhg at 1.0 C. –1 After 300 cycles, the capacity retention rate is 56.8%. Specifically, the capacity retention rate (%) after the Nth cycle is calculated as: (Nth discharge specific capacity / First discharge specific capacity at 1.0 C) × 100%.

[0116] Table 11

[0117]

[0118] Table 11 shows the results of room temperature charge-discharge cycle tests. As shown in Table 11, the lithium battery using Example 1 has a higher capacity retention rate.

[0119] High-temperature charge-discharge cycle test

[0120] The Gr||NCM811 obtained in Example 1 was subjected to cycle performance testing at 45°C, with a charge cutoff voltage of 4.45V and a discharge cutoff voltage of 2.8V. After activation cycling at room temperature, high-temperature long-cycle testing was conducted using a 1.0 C constant current constant voltage charging / 1.0 C constant current discharging rate. Figure 5 As shown.

[0121] Table 12

[0122]

[0123] Table 12 shows the results of the high-temperature charge-discharge cycle test. As shown in Table 12, the lithium battery using Example 1 has better high-temperature cycle performance.

[0124] Low temperature charge-discharge cycle test

[0125] The Gr||NCM811 obtained in Example 1 was subjected to cycle performance testing at –20°C, with a charge cutoff voltage of 4.45V and a discharge cutoff voltage of 2.8V. After activation cycling at room temperature, low-temperature cycle testing was performed using a 0.1C constant current charge / 0.1C constant current discharge rate and a 0.3C constant current constant voltage charge / 0.3C constant current discharge rate. Figure 6 As shown.

[0126] Table 13

[0127]

[0128] Table 13 shows the results of the low-temperature charge-discharge cycle test. As shown in Table 13, the lithium battery using Example 1 has better low-temperature cycle performance.

[0129] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A high performance solid state electrolyte based on a self-polymerizing monomer, characterized by: include, The electrolyte is prepared by in-situ thermosetting reaction of a mixed precursor liquid containing a self-polymerizing monomer, a lithium salt, an organic solvent and a thermal initiator; the self-polymerizing monomer acts as both a monomer and a self-crosslinking agent during the polymerization process. Among them, the in-situ thermosetting reaction involves injecting the mixed precursor liquid into the battery casing to initiate a thermal curing reaction. The self-polymerizing monomer is glycidyl methacrylate; The lithium salt includes one or both of lithium difluorooxalate borate and lithium hexafluorophosphate. The organic solvent is a mixture of fluoroethylene carbonate and methyl ethyl carbonate; The thermal initiator is azobisisobutyronitrile; The mixed precursor liquid comprises, by mass percentage: 5%-20% self-polymerizing monomer, 10%-15% lithium salt, 64%-84% organic solvent, and 0.1%-1% thermal initiator.

2. The high-performance solid electrolyte according to claim 1, characterized in that: The in-situ thermosetting reaction is carried out at a temperature of 40-80℃ for 6-24 hours.

3. The method for preparing the high-performance solid electrolyte according to any one of claims 1-2, characterized in that: include, In an inert atmosphere, lithium salts are dissolved in an organic solvent to prepare a basic electrolyte. Add monomers and thermal initiators to the base electrolyte and stir until completely dissolved to obtain a homogeneous and transparent mixed precursor solution; The mixed precursor solution is injected into the battery casing and placed in an environment of 40-80℃ for thermally initiated curing reaction. After the reaction is complete, a high-performance solid electrolyte is obtained.

4. The preparation method according to claim 3, characterized in that: The battery casing has pre-installed positive and negative electrode plates and a separator to achieve in-situ forming of the electrolyte.

5. A lithium secondary battery, characterized in that: The device comprises a positive electrode, a negative electrode, a separator, and a high-performance solid electrolyte as described in any one of claims 1-2; the positive electrode is a high-voltage positive electrode material, including lithium nickel cobalt manganese oxide, lithium-rich manganese-based material, or polyanionic positive electrode; the negative electrode includes a lithium metal negative electrode, a graphite negative electrode, or a silicon-carbon composite negative electrode.

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