A high safety semi-solid electrolyte composition containing a solid electrolyte additive and a method for preparing the same

Abstract

This invention relates to the field of new energy battery materials technology, and discloses a high-safety semi-solid electrolyte composition containing a solid electrolyte additive and its preparation method. The semi-solid electrolyte composition includes a semi-solid electrolyte matrix, a synergistically modified solid electrolyte additive, an organic small molecule functional regulator, a lithium salt, a flame retardant, a film-forming aid, and a stabilizer. The synergistically modified solid electrolyte additive uses lithium lanthanum zirconium oxide as a matrix, undergoes surface anchoring modification via methacryloyloxypropyltrimethoxysilane, and constructs a synergistic structure on its surface formed by polyethylene glycol dimethacrylate and 1-vinyl-3-ethylimidazolium difluorosulfonylimide salt, which combines a lithium-capable flexible segment and an ionic liquid interface layer. This invention achieves stable dispersion of the solid electrolyte in the semi-solid electrolyte and the construction of continuous ion conduction channels, thereby significantly improving the ion conduction performance, interface stability, and safety performance of the electrolyte, and has good application prospects.

Description

Technical Field

[0001] This invention relates to the field of new energy battery materials technology, specifically to a high-safety semi-solid electrolyte composition containing solid electrolyte additives and its preparation method. Background Technology

[0002] With the rapid development of new energy vehicles, energy storage devices, and portable electronic products, lithium-ion batteries are continuously evolving towards higher energy density, higher safety, and longer cycle life. As a crucial component for ion conduction in lithium-ion batteries, the electrolyte's performance significantly impacts the battery's safety, rate performance, and cycle stability. Current lithium-ion batteries generally employ liquid electrolyte systems based on carbonate-based organic solvents. While these electrolytes possess high ionic conductivity, they commonly suffer from flammability, volatility, and poor thermal stability. When the battery is subjected to overcharging, short circuits, or high-temperature shocks, thermal runaway can easily occur, posing significant safety hazards.

[0003] To improve battery safety, semi-solid electrolyte systems have received increasing attention in recent years. Semi-solid electrolytes typically introduce polymer matrices or inorganic solid electrolyte fillers into liquid electrolytes, creating a gel or semi-solid structure. This reduces electrolyte flow while maintaining high ion conductivity, thus improving battery safety. However, existing semi-solid electrolyte systems still have some shortcomings. For example, inorganic solid electrolyte particles tend to agglomerate and settle in organic electrolyte systems, leading to decreased system stability; the interfacial compatibility between the solid electrolyte and the electrolyte is poor, hindering the construction of continuous and stable lithium-ion conduction channels; and unstable interfacial films easily form at the electrode interface during cycling, affecting battery cycle performance and rate performance.

[0004] Traditional solid electrolyte fillers mostly serve only as mechanical reinforcements or simple ion conductors, lacking effective functionalized interface structures on their surfaces, making it difficult to achieve good interfacial synergy in semi-solid electrolyte systems. Therefore, how to structurally modify solid electrolytes to improve their dispersion stability and interfacial compatibility in electrolyte systems, construct efficient lithium-ion migration channels, and further enhance the safety performance and interfacial stability of the electrolyte has become a pressing technical problem in the current electrolyte technology field. Summary of the Invention

[0005] To overcome the problems of poor dispersion stability, insufficient interfacial compatibility, and discontinuous ion transport channels of solid electrolytes in semi-solid electrolyte systems, which affect electrolyte safety and battery cycle stability, as described in the background art, the present invention aims to provide a high-safety semi-solid electrolyte composition containing solid electrolyte additives and its preparation method. The present invention modifies the surface of solid electrolyte particles by anchoring them, constructing a synergistic modified structure on their surface that combines lithipotable flexible segments and an ionic liquid interface layer. This allows the solid electrolyte additives to achieve stable dispersion and construct continuous ion conduction channels in the semi-solid electrolyte system. Simultaneously, succinic anionylene is introduced into the system as an organic small molecule functional regulator, and combined with lithium salts, flame retardants, film-forming aids, and stabilizers to construct the semi-solid electrolyte system, thereby obtaining a semi-solid electrolyte composition with high safety and excellent ion transport performance. This invention constructs a solid electrolyte additive with a synergistic structure of lithiable flexible segments and an ionic liquid interface layer, and combines it with organic small molecule functional regulators to give the semi-solid electrolyte system better dispersion stability and interfacial compatibility, thereby significantly improving the safety performance, ion conduction performance and battery cycle stability of the electrolyte.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A high-safety semi-solid electrolyte composition containing a solid electrolyte additive, the high-safety semi-solid electrolyte composition comprising the following raw materials in parts by weight: 60-120 parts of semi-solid electrolyte matrix; 5-40 parts of synergistic modified solid electrolyte additive; 0.1-5 parts of organic small molecule functional regulator; 5-25 parts of lithium salt; 0.5-10 parts of flame retardant; 0.1-5 parts of film-forming aid; and 0.05-2 parts of stabilizer; wherein the synergistic modified solid electrolyte additive is prepared by surface anchoring modification of solid electrolyte microparticles with methacryloyloxypropyltrimethoxysilane, followed by in-situ polymerization of polyethylene glycol dimethacrylate and 1-vinyl-3-ethylimidazolium difluorosulfonylimide salt on its surface to form a synergistic modified structure possessing both lithiable flexible segments and an ionic liquid interface layer; and wherein the organic small molecule functional regulator is succinic anhydride.

[0008] Optionally, the synergistic modified solid electrolyte additive comprises the following raw materials in parts by weight: 60-120 parts of lithium lanthanum zirconium oxide, 0.5-6 parts of methacryloyloxypropyltrimethoxysilane, 1-10 parts of polyethylene glycol dimethacrylate, 0.5-8 parts of 1-vinyl-3-ethylimidazolium bisfluorosulfonylimide salt, 0.2-5 parts of lithium bis(trifluoromethanesulfonylimide), and 0.05-1 part of azobisisobutyronitrile.

[0009] Optionally, the preparation method of the synergistically modified solid electrolyte additive includes the following steps:

[0010] (1) Lithium lanthanum zirconium oxide and methacryloxypropyltrimethoxysilane were added to a solvent system to react, so that methacryloxypropyltrimethoxysilane was silanized on the surface of lithium lanthanum zirconium oxide to obtain surface-modified solid electrolyte particles.

[0011] (2) Polyethylene glycol dimethacrylate, 1-vinyl-3-ethylimidazolium bisfluorosulfonylimide salt and lithium bistrifluoromethanesulfonylimide were added to the surface-modified solid electrolyte particles and mixed and dispersed to obtain a composite dispersion system;

[0012] (3) Add azobisisobutyronitrile to the composite dispersion system to carry out in-situ polymerization reaction, so that polyethylene glycol dimethacrylate and 1-vinyl-3-ethylimidazolium difluorosulfonylimide salt form a polymer layer on the surface of solid electrolyte particles, thereby obtaining a synergistically modified solid electrolyte additive.

[0013] Optionally, the reaction conditions in step (1) are as follows: using a mixed solvent of ethanol and deionized water in a volume ratio of 4 to 6:1 as the reaction medium, stirring at 45 to 65°C for 2 to 3 hours at a pH of 4 to 6, and stirring at a speed of 300 to 500 rpm.

[0014] Optionally, the reaction conditions in step (2) are as follows: mechanical stirring and dispersion for 30 to 90 minutes at room temperature (20 to 30°C), stirring speed of 400 to 700 rpm, and ultrasonic dispersion for 10 to 30 minutes.

[0015] Optionally, the reaction conditions in step (3) are as follows: free radical polymerization reaction is carried out at 65-75°C for 3-5 hours under nitrogen protection, and the stirring speed is 300-500 rpm.

[0016] Optionally, the lithium salt is a mixture of lithium hexafluorophosphate and lithium bis(trifluoromethanesulfonyl)imide in a mass ratio of 1 to 3:1; the flame retardant is a mixture of triethyl phosphate and tris(trifluoroethyl) phosphate in a mass ratio of 1 to 2:1; the film-forming aid is a mixture of fluoroethylene carbonate and succinic anionyl ester in a mass ratio of 1 to 3:1; and the stabilizer is a mixture of di-tert-butyl-p-cresol and trimethyl phosphate in a mass ratio of 1 to 2:1.

[0017] Optionally, a method for preparing a high-safety semi-solid electrolyte composition containing a solid electrolyte additive, the preparation method comprising the following steps:

[0018] S1, add the semi-solid electrolyte matrix to the reaction vessel, and add lithium salt, flame retardant, film-forming aid and stabilizer in sequence under stirring conditions, so that the components are fully mixed and dissolved to obtain the basic electrolyte system;

[0019] S2, add synergistic modified solid electrolyte additives and organic small molecule functional regulators to the basic electrolyte system, and disperse them under stirring conditions to make the synergistic modified solid electrolyte additives uniformly dispersed in the electrolyte system to form a composite dispersion system.

[0020] S3 involves continuously stirring and degassing the composite dispersion system to ensure complete homogenization and eliminate air bubbles, thereby obtaining a high-safety semi-solid electrolyte composition containing solid electrolyte additives.

[0021] Optionally, the reaction conditions for step S1 are mechanical stirring at 20–40°C for 30–90 min at a stirring speed of 300–600 rpm; the reaction conditions for step S2 are mechanical stirring at 20–35°C for 40–120 min at a stirring speed of 400–700 rpm, combined with ultrasonic dispersion for 10–30 min.

[0022] Optionally, the reaction conditions in step S3 are: stirring and degassing at 25–40°C for 20–60 min, and vacuum degassing at a vacuum degree of −0.06–−0.09 MPa for 10–30 min.

[0023] The beneficial effects of this invention are:

[0024] This invention modifies the surface of solid electrolyte particles by anchoring them and constructs a synergistic modified structure on their surface, combining lithiable flexible segments and an ionic liquid interface layer. This results in better interfacial compatibility and dispersion stability of the solid electrolyte particles in a semi-solid electrolyte system, enabling the construction of continuous and stable lithium-ion conduction channels within the electrolyte. Simultaneously, the lithiable flexible segments coordinate with lithium salts, promoting lithium-ion migration, while the ionic liquid interface layer enhances the ion conductivity of the particle surface and reduces interfacial impedance, effectively improving the overall ionic conductivity of the semi-solid electrolyte system. Furthermore, by introducing succinic anionylene as a small organic molecule functional regulator, it participates in the electrode interfacial film formation process and optimizes the interfacial structure, further improving the interfacial stability and cycle stability of the electrolyte system. This results in a semi-solid electrolyte that maintains high safety while exhibiting excellent ion transport performance and electrochemical stability. Attached Figure Description

[0025] The invention will now be further described with reference to the accompanying drawings.

[0026] Figure 1 A comparison of the infrared spectra of lithium lanthanum zirconium oxide solid electrolyte and synergistically modified solid electrolyte additives;

[0027] Figure 2 This is a comparison chart of the ion conduction performance test results for samples with different ratios. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments. However, the present invention is not limited to the following embodiments. Equivalent adjustments made without departing from the spirit and essence of the present invention should also be considered to fall within the protection scope of the present invention.

[0029] Example 1: This example is to verify that when the components and reaction conditions are in a low range, the synergistic modified solid electrolyte additive constructed in this invention can still achieve stable dispersion in a semi-solid electrolyte system and form a stable electrolyte system.

[0030] S1, Preparation of synergistically modified solid electrolyte additives

[0031] Sixty parts of lithium lanthanum zirconium oxide were added to a mixed solvent of ethanol and deionized water in a volume ratio of 4:1 and dispersed by stirring at 300 rpm for 20 min, and the pH of the system was adjusted to 4. Then, 0.5 parts of methacryloyloxypropyltrimethoxysilane were added and the mixture was stirred at 45 °C for 2 h to silanize and modify the surface of the lithium lanthanum zirconium oxide with methacryloyloxypropyltrimethoxysilane, resulting in surface-modified solid electrolyte microparticles. One part of polyethylene glycol dimethacrylate, 0.5 parts of 1-vinyl-3-ethylimidazolium bisfluorosulfonylimide salt, and 0.2 parts of lithium bis(trifluoromethanesulfonylimide) were added to the system and dispersed by stirring at 400 rpm for 30 min at room temperature (20 °C), followed by ultrasonic dispersion for 10 min. Then, 0.05 parts of azobisisobutyronitrile were added and the mixture was subjected to free radical polymerization at 65 °C for 3 h under nitrogen protection to obtain a synergistically modified solid electrolyte additive.

[0032] S2, Preparation of semi-solid electrolyte system

[0033] Sixty parts of semi-solid electrolyte matrix were added to a reaction vessel and stirred at 300 rpm for 30 min at 20 °C. Then, 5 parts of lithium salt, 0.5 parts of flame retardant, 0.1 parts of film-forming aid, and 0.05 parts of stabilizer were added sequentially to ensure that all components were fully mixed and dissolved to obtain the basic electrolyte system. Subsequently, 5 parts of synergistic modified solid electrolyte additive and 0.1 parts of succinate were added to the system and stirred at 400 rpm for 40 min at 20 °C. The mixture was then ultrasonically dispersed for 10 min to form a composite dispersion system.

[0034] S3, Formation of semi-solid electrolyte

[0035] The composite dispersion system obtained in step S2 was stirred and degassed at 300 rpm for 20 min at 25 °C, and then vacuum degassed for 10 min at a vacuum degree of −0.06 MPa to obtain a high-safety semi-solid electrolyte composition containing solid electrolyte additives.

[0036] Example 2: This example is to verify that when the components and reaction conditions are within a moderate range, the synergistic modified solid electrolyte additive and semi-solid electrolyte system constructed in this invention can obtain a stable structure and excellent ion transport performance.

[0037] S1, Preparation of synergistically modified solid electrolyte additives

[0038] Ninety parts of lithium lanthanum zirconium oxide were added to a mixed solvent of ethanol and deionized water in a volume ratio of 5:1 and stirred and dispersed at 400 rpm for 30 min, and the pH of the system was adjusted to 5. Then, three parts of methacryloyloxypropyltrimethoxysilane were added and stirred at 55 °C for 2.5 h to silanize and modify the surface of lithium lanthanum zirconium oxide with methacryloyloxypropyltrimethoxysilane. Then, five parts of polyethylene glycol dimethacrylate, four parts of 1-vinyl-3-ethylimidazolium bisfluorosulfonylimide salt and two parts of lithium bis(trifluoromethanesulfonylimide) were added and stirred at 550 rpm for 60 min at 25 °C, followed by ultrasonic dispersion for 20 min. Finally, 0.5 parts of azobisisobutyronitrile were added and subjected to free radical polymerization at 70 °C for 4 h under nitrogen protection to obtain a synergistically modified solid electrolyte additive. Figure 1 The infrared spectrum comparison shows that the unmodified lithium lanthanum zirconium oxide mainly exhibits spectra in the 500–700 cm⁻¹ range. -1 The sample exhibits a distinct absorption peak at 2920–2850 cm⁻¹, corresponding to metal-oxygen bond vibrations, and the overall spectrum is relatively simple; the modified sample shows an absorption peak at 2920–2850 cm⁻¹. -1 A characteristic CH2 peak appears at 1720 cm⁻¹. -1 A C=O absorption peak appears at 1100 cm⁻¹. -1 C–O–C and Si–O related absorption peaks appear nearby, and at 1180 cm⁻¹ -1 and 1560cm -1 The presence of characteristic peaks for S=O and the imidazole ring at these locations indicates the successful introduction of the organic chain segment and the ionic liquid structure; simultaneously, the peaks at 500–700 cm⁻¹... -1 The presence of the skeletal peak indicates that the matrix structure has not been damaged; in summary, this proves that the synergistic modification structure has been successfully constructed.

[0039] S2, Preparation of semi-solid electrolyte system

[0040] Ninety parts of semi-solid electrolyte matrix were added to a reaction vessel and stirred at 450 rpm for 60 min at 30 °C. Then, 15 parts of lithium salt, 5 parts of flame retardant, 2.5 parts of film-forming aid, and 1 part of stabilizer were added sequentially to fully dissolve and form the basic electrolyte system. Subsequently, 20 parts of synergistic modified solid electrolyte additive and 2.5 parts of succinate were added and stirred at 550 rpm for 80 min at 25 °C, followed by ultrasonic dispersion for 20 min to obtain a composite dispersion system.

[0041] S3, Formation of semi-solid electrolyte

[0042] The composite dispersion system obtained in step S2 was stirred and degassed at 400 rpm for 40 min at 30 °C, and then vacuum degassed at a vacuum degree of −0.075 MPa for 20 min to obtain a high-safety semi-solid electrolyte composition containing solid electrolyte additives.

[0043] Example 3: This example is to verify that when the components and reaction conditions are in a high range, the synergistic modified solid electrolyte additive constructed in this invention can still maintain good dispersion stability and form a stable electrolyte structure in a semi-solid electrolyte system.

[0044] S1, Preparation of synergistically modified solid electrolyte additives

[0045] 120 parts of lithium lanthanum zirconium oxide were added to a mixed solvent of ethanol and deionized water in a volume ratio of 6:1 and dispersed by stirring at 500 rpm for 40 min, and the pH of the system was adjusted to 6. Then, 6 parts of methacryloyloxypropyltrimethoxysilane were added and stirred at 65 °C for 3 h to silanize and modify the surface of lithium lanthanum zirconium oxide. Then, 10 parts of polyethylene glycol dimethacrylate, 8 parts of 1-vinyl-3-ethylimidazolium bisfluorosulfonylimide salt and 5 parts of lithium bis(trifluoromethanesulfonylimide) were added and stirred at 700 rpm for 90 min at 30 °C, followed by ultrasonic dispersion for 30 min. Finally, 1 part of azobisisobutyronitrile was added and subjected to free radical polymerization at 75 °C for 5 h under nitrogen protection to obtain a synergistically modified solid electrolyte additive.

[0046] S2, Preparation of semi-solid electrolyte system

[0047] 120 parts of semi-solid electrolyte matrix were added to a reaction vessel and stirred at 600 rpm for 90 min at 40 °C. Then, 25 parts of lithium salt, 10 parts of flame retardant, 5 parts of film-forming aid, and 2 parts of stabilizer were added sequentially to fully dissolve the components and form the basic electrolyte system. Subsequently, 40 parts of synergistic modified solid electrolyte additive and 5 parts of succinic anionyl nitrile were added and stirred at 700 rpm for 120 min at 35 °C, followed by ultrasonic dispersion for 30 min to obtain a composite dispersion system.

[0048] S3, Formation of semi-solid electrolyte

[0049] The composite dispersion system obtained in step S2 was stirred and degassed at 500 rpm for 60 min at 40 °C, and then vacuum degassed at a vacuum degree of −0.09 MPa for 30 min to obtain a high-safety semi-solid electrolyte composition containing solid electrolyte additives.

[0050] Comparative Example 1: This comparative example aims to verify the impact of using only methacryloyloxypropyltrimethoxysilane for single surface anchoring modification of solid electrolytes, without constructing a synergistic structure of lithiable flexible segments and ionic liquid interface layer, on the structural stability and ion transport performance of semi-solid electrolyte systems.

[0051] S1, Preparation of single-surface anchored modified solid electrolyte additives

[0052] Ninety parts of lithium lanthanum zirconium oxide were added to a mixed solvent of ethanol and deionized water in a volume ratio of 5:1 and stirred and dispersed at 400 rpm for 30 min, and the pH of the system was adjusted to 5. Then, three parts of methacryloyloxypropyltrimethoxysilane were added and stirred at 55 °C for 2.5 h to silanize and modify the surface of lithium lanthanum zirconium oxide with methacryloyloxypropyltrimethoxysilane. After the reaction was completed, the product was separated, washed and dried to obtain a solid electrolyte additive with single surface anchoring modification.

[0053] S2, Preparation of semi-solid electrolyte system

[0054] Ninety parts of semi-solid electrolyte matrix were added to a reaction vessel and stirred at 450 rpm for 60 min at 30 °C. Then, 15 parts of lithium salt, 5 parts of flame retardant, 2.5 parts of film-forming aid, and 1 part of stabilizer were added sequentially to fully dissolve and form the basic electrolyte system. Subsequently, 20 parts of single surface anchoring modified solid electrolyte additive and 2.5 parts of succinate were added and stirred at 550 rpm for 80 min at 25 °C, followed by ultrasonic dispersion for 20 min to obtain a composite dispersion system.

[0055] S3, Formation of semi-solid electrolyte

[0056] The composite dispersion system obtained in step S2 was stirred and degassed at 400 rpm for 40 min at 30 °C, and then vacuum degassed for 20 min at a vacuum degree of −0.075 MPa to obtain a semi-solid electrolyte composition.

[0057] Comparative Example 2: This comparative example aims to verify the effect of forming a single polymeric modified structure on the surface of a solid electrolyte by only polyethylene glycol dimethacrylate and 1-vinyl-3-ethylimidazolium difluorosulfonylimide salt, without surface anchoring modification with methacryloyloxypropyltrimethoxysilane, on the structural stability and ion transport performance of the semi-solid electrolyte system.

[0058] S1, Preparation of solid electrolyte additives modified by single surface polymerization

[0059] Ninety parts of lithium lanthanum zirconium oxide were added to the reaction system, followed by five parts of polyethylene glycol dimethacrylate, four parts of 1-vinyl-3-ethylimidazolium difluorosulfonylimide salt, and two parts of lithium bis(trifluoromethanesulfonylimide). The mixture was stirred at 550 rpm for 60 min at 25 °C and then ultrasonically dispersed for 20 min. Next, 0.5 parts of azobisisobutyronitrile were added, and the mixture was subjected to free radical polymerization at 70 °C for 4 h under nitrogen protection. This allowed polyethylene glycol dimethacrylate and 1-vinyl-3-ethylimidazolium difluorosulfonylimide salt to form a polymer layer on the surface of the lithium lanthanum zirconium oxide, resulting in a single surface-polymerized modified solid electrolyte additive.

[0060] S2, Preparation of semi-solid electrolyte system

[0061] Ninety parts of semi-solid electrolyte matrix were added to a reaction vessel and stirred at 450 rpm for 60 min at 30 °C. Then, 15 parts of lithium salt, 5 parts of flame retardant, 2.5 parts of film-forming aid, and 1 part of stabilizer were added sequentially to fully dissolve and form the basic electrolyte system. Subsequently, 20 parts of single surface polymerization modified solid electrolyte additive and 2.5 parts of succinate were added and stirred at 550 rpm for 80 min at 25 °C, followed by ultrasonic dispersion for 20 min to obtain a composite dispersion system.

[0062] S3, Formation of semi-solid electrolyte

[0063] The composite dispersion system obtained in step S2 was stirred and degassed at 400 rpm for 40 min at 30 °C, and then vacuum degassed for 20 min at a vacuum degree of −0.075 MPa to obtain a semi-solid electrolyte composition.

[0064] Comparative Example 3: This comparative example is intended to verify the effect of not adding the organic small molecule functional regulator succinate on the structural stability, interface state and ion transport performance of the semi-solid electrolyte when other components and reaction conditions are kept consistent with those in Example 2.

[0065] S1, Preparation of synergistically modified solid electrolyte additives

[0066] Ninety parts of lithium lanthanum zirconium oxide were added to a mixed solvent of ethanol and deionized water in a volume ratio of 5:1 and stirred and dispersed at 400 rpm for 30 min, and the pH of the system was adjusted to 5. Then, three parts of methacryloyloxypropyltrimethoxysilane were added and stirred at 55 °C for 2.5 h to silanize and modify the surface of lithium lanthanum zirconium oxide with methacryloyloxypropyltrimethoxysilane. Then, five parts of polyethylene glycol dimethacrylate, four parts of 1-vinyl-3-ethylimidazolium bisfluorosulfonylimide salt and two parts of lithium bis(trifluoromethanesulfonylimide) were added and stirred at 550 rpm for 60 min at 25 °C, followed by ultrasonic dispersion for 20 min. Finally, 0.5 parts of azobisisobutyronitrile were added and subjected to free radical polymerization at 70 °C for 4 h under nitrogen protection to obtain a synergistically modified solid electrolyte additive.

[0067] S2, Preparation of semi-solid electrolyte system

[0068] Ninety parts of semi-solid electrolyte matrix were added to a reaction vessel and stirred at 450 rpm for 60 min at 30 °C. Then, 15 parts of lithium salt, 5 parts of flame retardant, 2.5 parts of film-forming aid, and 1 part of stabilizer were added sequentially to fully dissolve and form the basic electrolyte system. Subsequently, 20 parts of synergistic modified solid electrolyte additive were added and stirred at 550 rpm for 80 min at 25 °C, followed by ultrasonic dispersion for 20 min to obtain a composite dispersion system.

[0069] S3, Formation of semi-solid electrolyte

[0070] The composite dispersion system obtained in step S2 was stirred and degassed at 400 rpm for 40 min at 30 °C, and then vacuum degassed for 20 min at a vacuum degree of −0.075 MPa to obtain a semi-solid electrolyte composition.

[0071] Performance testing:

[0072] (1) Test method for ion conduction performance

[0073] The semi-solid electrolytes obtained in the examples and comparative examples were injected into stainless steel symmetric cells in a glove box. The electrolyte coating thickness was controlled to be approximately 200–300 μm. After assembly, the cells were allowed to stand at 25°C for 12 hours to ensure full wetting and stability of the system. Subsequently, an electrochemical workstation was used to perform AC impedance testing. The test frequency range was 1 MHz to 1 Hz, and the perturbation voltage was 5 mV. The resistance changes of different samples were compared by analyzing the impedance spectra to evaluate the ion conduction performance of each system.

[0074] (2) Interface stability test method

[0075] The semi-solid electrolytes obtained in the examples and comparative examples were assembled into lithium / electrolyte / lithium symmetric batteries. After standing at 25°C for 24 hours, constant current polarization tests were performed. The current density was set to 0.1 mA / cm². Cyclic tests were conducted using constant current charge-discharge mode, with each cycle lasting 1 hour. The cycles were repeated for 100 hours. The changes in polarization voltage over time were recorded to evaluate the stability of the electrolyte-lithium metal interface and the ability to suppress interfacial side reactions.

[0076] (3) Cyclic performance test method

[0077] The semi-solid electrolytes obtained in the examples and comparative examples were assembled into lithium / electrolyte / LiFePO4 coin cells. Charge-discharge cycle tests were conducted at room temperature, with the voltage range set to 2.5–4.2V and the charge-discharge rate set to 0.5C. The cells were continuously cycled 100 times, and the changes in the discharge specific capacity and capacity retention rate of the cells were recorded to evaluate the impact of different electrolyte systems on the cycle stability of the cells.

[0078] (4) Safety performance testing methods

[0079] The semi-solid electrolyte samples obtained in the examples and comparative examples were dropped onto glass fiber membranes and ignited in air. After contact with an open flame for 5 seconds, the flame source was removed, and the combustion, burning time, and self-extinguishing performance of the samples were observed. At the same time, the electrolyte samples were placed in a 120°C constant temperature oven and heated for 2 hours to observe their morphological changes, volatilization, and whether there was obvious flow or decomposition, so as to comprehensively evaluate the flame retardant performance and thermal safety of the electrolyte system.

[0080] Table 1 Performance test results of different samples

[0081] sample Ion conductivity (relative resistance / Ω) Polarization voltage (mV) Discharge specific capacity (mAh / g) Capacity retention rate (%) Burning time (s) Example 1 85 95 142 91.2 3 Example 2 62 68 156 96.5 0 Example 3 70 75 150 94.3 1 Comparative Example 1 130 145 128 85.6 8 Comparative Example 2 118 132 134 87.2 6 Comparative Example 3 105 120 138 89.1 5

[0082] As shown in Table 1, Examples 1-3 and Comparative Examples 1-3 exhibited significant differences in ion transport performance, interface stability, cycle performance, and safety performance. The overall performance of the Examples was superior to that of the Comparative Examples, with Example 2 showing the best performance. Specifically, the relative resistances of Examples 1-3 were 85Ω, 62Ω, and 70Ω, respectively, while those of Comparative Examples 1-3 were 130Ω, 118Ω, and 105Ω, respectively, indicating that the Example systems had lower ion transport resistance.

[0083] In terms of ion conduction performance, Figure 2 The relative resistances of Examples 1 to 3 were significantly lower than those of the comparative examples, especially Example 2, which was only 62Ω, indicating that its ion migration channel construction was more continuous and efficient. In contrast, the relative resistances of Comparative Examples 1 to 3 reached 130Ω, 118Ω and 105Ω, respectively, indicating that their ion conduction paths were not smooth and the system had poor conductivity.

[0084] Regarding interface stability, the polarization voltages of Examples 1-3 were 95mV, 68mV, and 75mV, respectively, which were significantly lower than those of Comparative Examples 1-3 (145mV, 132mV, and 120mV), indicating that the present invention effectively reduced the interface charge transfer resistance through synergistic structural modification. Among them, Example 2 had the lowest polarization voltage, at only 68mV, and exhibited the best interface stability.

[0085] In terms of cycling performance, the discharge specific capacities of Examples 1-3 were 142 mAh / g, 156 mAh / g, and 150 mAh / g, respectively, with capacity retention rates of 91.2%, 96.5%, and 94.3%, respectively. These were all superior to those of Comparative Examples 1-3 (discharge specific capacities of 128 mAh / g, 134 mAh / g, and 138 mAh / g, respectively, with capacity retention rates of 85.6%, 87.2%, and 89.1%, respectively). This indicates that the systems of the Examples have better structural stability and the ability to suppress side reactions during cycling, with Example 2 showing the best performance.

[0086] In terms of safety performance, the combustion times of Examples 1 to 3 were 3s, 0s and 1s respectively, which were significantly lower than those of Comparative Examples 1 to 3 (8s, 6s and 5s). Among them, Example 2 showed non-flammability or rapid self-extinguishing, indicating that the semi-solid electrolyte system constructed in this invention has excellent flame retardant performance and thermal stability.

[0087] In summary, this invention significantly improves the ion conduction performance, interfacial stability, cycle performance, and safety performance of semi-solid electrolytes by constructing a synergistic modified solid electrolyte additive that combines a lithium-capable flexible chain segment and an ionic liquid interface layer, and by introducing succinic anhydride as an organic small molecule functional regulator. Among these improvements, Example 2 shows the best overall performance, verifying the effectiveness and superiority of the technical solution of this invention.

Claims

1. A high-safety semi-solid electrolyte composition containing a solid electrolyte additive, characterized in that, The high-safety semi-solid electrolyte composition comprises the following raw materials in parts by weight: 60-120 parts of semi-solid electrolyte matrix; 5-40 parts of synergistic modified solid electrolyte additive; 0.1-5 parts of organic small molecule functional regulator; 5-25 parts of lithium salt; 0.5-10 parts of flame retardant; 0.1-5 parts of film-forming aid; and 0.05-2 parts of stabilizer. The synergistic modified solid electrolyte additive is prepared by surface anchoring modification of solid electrolyte microparticles with methacryloyloxypropyltrimethoxysilane, followed by in-situ polymerization of polyethylene glycol dimethacrylate and 1-vinyl-3-ethylimidazolium difluorosulfonylimide salt on its surface to form a synergistic modified structure that combines lithipotable flexible segments and an ionic liquid interface layer. The organic small molecule functional regulator is succinic anhydride.

2. The high-safety semi-solid electrolyte composition containing solid electrolyte additives according to claim 1, characterized in that, The synergistic modified solid electrolyte additive comprises the following raw materials in parts by weight: 60-120 parts of lithium lanthanum zirconium oxide, 0.5-6 parts of methacryloyloxypropyltrimethoxysilane, 1-10 parts of polyethylene glycol dimethacrylate, 0.5-8 parts of 1-vinyl-3-ethylimidazolium bisfluorosulfonylimide salt, 0.2-5 parts of lithium bis(trifluoromethanesulfonylimide), and 0.05-1 part of azobisisobutyronitrile.

3. A high-safety semi-solid electrolyte composition containing a solid electrolyte additive according to claim 1 or 2, characterized in that, The preparation method of the synergistic modified solid electrolyte additive includes the following steps: (1) Lithium lanthanum zirconium oxide and methacryloxypropyltrimethoxysilane were added to a solvent system to react, so that methacryloxypropyltrimethoxysilane was silanized on the surface of lithium lanthanum zirconium oxide to obtain surface-modified solid electrolyte particles. (2) Polyethylene glycol dimethacrylate, 1-vinyl-3-ethylimidazolium bisfluorosulfonylimide salt and lithium bistrifluoromethanesulfonylimide were added to the surface-modified solid electrolyte particles and mixed and dispersed to obtain a composite dispersion system; (3) Add azobisisobutyronitrile to the composite dispersion system to carry out in-situ polymerization reaction, so that polyethylene glycol dimethacrylate and 1-vinyl-3-ethylimidazolium difluorosulfonylimide salt form a polymer layer on the surface of solid electrolyte particles, thereby obtaining a synergistically modified solid electrolyte additive.

4. The high-safety semi-solid electrolyte composition containing solid electrolyte additives according to claim 3, characterized in that, The reaction conditions for step (1) are as follows: using a mixed solvent of ethanol and deionized water in a volume ratio of 4 to 6:1 as the reaction medium, stirring at 45 to 65°C for 2 to 3 hours at a pH of 4 to 6, and stirring at a speed of 300 to 500 rpm.

5. The high-safety semi-solid electrolyte composition containing solid electrolyte additives according to claim 3, characterized in that, The reaction conditions for step (2) are as follows: mechanical stirring and dispersion for 30 to 90 minutes at room temperature (20 to 30°C), stirring speed of 400 to 700 rpm, and ultrasonic dispersion for 10 to 30 minutes.

6. The high-safety semi-solid electrolyte composition containing solid electrolyte additives according to claim 3, characterized in that, The reaction conditions for step (3) are as follows: free radical polymerization reaction is carried out at 65-75°C for 3-5 hours under nitrogen protection, and the stirring speed is 300-500 rpm.

7. The high-safety semi-solid electrolyte composition containing solid electrolyte additives according to claim 1, characterized in that, The lithium salt is a mixture of lithium hexafluorophosphate and lithium bis(trifluoromethanesulfonyl)imide in a mass ratio of 1 to 3:1; the flame retardant is a mixture of triethyl phosphate and tris(trifluoroethyl) phosphate in a mass ratio of 1 to 2:1; the film-forming aid is a mixture of fluoroethylene carbonate and succinic anionyl in a mass ratio of 1 to 3:1; and the stabilizer is a mixture of di-tert-butyl-p-cresol and trimethyl phosphate in a mass ratio of 1 to 2:

1.

8. A method for preparing a high-safety semi-solid electrolyte composition containing a solid electrolyte additive, characterized in that, The preparation method includes the following steps: S1, add the semi-solid electrolyte matrix to the reaction vessel, and add lithium salt, flame retardant, film-forming aid and stabilizer in sequence under stirring conditions, so that the components are fully mixed and dissolved to obtain the basic electrolyte system; S2, add synergistic modified solid electrolyte additives and organic small molecule functional regulators to the basic electrolyte system, and disperse them under stirring conditions to make the synergistic modified solid electrolyte additives uniformly dispersed in the electrolyte system to form a composite dispersion system. S3 involves continuously stirring and degassing the composite dispersion system to ensure complete homogenization and eliminate air bubbles, thereby obtaining a high-safety semi-solid electrolyte composition containing solid electrolyte additives.

9. The method for preparing a high-safety semi-solid electrolyte composition containing a solid electrolyte additive according to claim 8, characterized in that, The reaction conditions for step S1 are mechanical stirring at 20–40°C for 30–90 min at a stirring speed of 300–600 rpm; the reaction conditions for step S2 are mechanical stirring at 20–35°C for 40–120 min at a stirring speed of 400–700 rpm, combined with ultrasonic dispersion for 10–30 min.

10. The method for preparing a high-safety semi-solid electrolyte composition containing a solid electrolyte additive according to claim 8, characterized in that, The reaction conditions for step S3 are: stirring and degassing at 25–40°C for 20–60 min, and vacuum degassing at a vacuum degree of −0.06–−0.09 MPa for 10–30 min.

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