A layered solid elastomeric electrolyte and its preparation method and application

Abstract

The application discloses a layered solid elastomer electrolyte and a preparation method and application thereof. The method comprises the following steps: using an acrylate mixture and a deep eutectic electrolyte system as raw materials, and performing thermal curing through a crosslinking agent and a thermal initiator to obtain a self-supporting high-pressure stable layer; using butyl fluoroacrylate, propylene-1,3-sulfolactone and a deep eutectic electrolyte system as raw materials, and performing thermal curing through a crosslinking agent and a thermal initiator to obtain a lithium metal supported interface matching layer; and laminating the two layers to obtain the layered solid elastomer electrolyte. The application is inspired by the layered structure design of a tire, and through independent polymerization and crosslinking of the layered elastomer electrolyte, high ion conductivity and interface stability are realized, and process compatibility required by industrial production is achieved.

Description

Technical Field

[0001] This invention belongs to the field of solid electrolyte and battery material technology, specifically relating to a layered solid elastomer electrolyte, its preparation method, and its application. The electrolyte comprises a high-voltage stabilizing layer near the positive electrode and an interface-matching layer near the negative electrode, which are independently polymerized and then laminated together, inspired by the functional design of the layered rubber structure of tires. Background Technology

[0002] Currently, all-solid-state polymer electrolytes have become a research focus for next-generation energy storage devices due to their high safety, good flexibility, and compatibility potential with high-capacity lithium metal anodes. Researchers have successfully developed systems based on matrices such as polyethylene oxide and polycarbonate, and improved their ionic conductivity and mechanical strength through copolymerization, crosslinking, and the introduction of inorganic fillers. They have initially achieved battery applications in the room temperature to moderate temperature range, demonstrating the feasibility of replacing traditional liquid electrolytes.

[0003] However, this technology still faces several key bottlenecks: First, the room temperature ionic conductivity is generally low (usually <10⁻). 4 The low efficiency (S / cm) severely restricts the battery's rate performance and low-temperature operating capability. Secondly, the insufficient stability of the polymer matrix-electrode interface easily leads to lithium dendrite growth and interfacial side reactions, resulting in capacity and cycle life degradation. Thirdly, it is difficult to synergistically optimize mechanical and electrochemical properties, and high-modulus systems often sacrifice ion migration ability. In addition, existing preparation processes still struggle to balance the uniformity, thickness control, and large-scale production costs of the electrolyte membrane, becoming a significant obstacle to industrial application. While systems using in-situ monomer polymerization improve ion conduction to some extent, they are prone to problems such as poor chemical compatibility, difficulty in precisely controlling the polymerization process, complex processes, high costs, and insufficient long-term interfacial stability.

[0004] Therefore, it is still necessary to address the problems of low room temperature ionic conductivity and poor electrode interface matching in existing all-solid polymer electrolytes, as well as the problems of poor chemical compatibility, difficulty in precise control of the polymerization process, complex and high cost of the process, and insufficient long-term interface stability of systems that use monomer in situ polymerization to improve ion conduction. Summary of the Invention

[0005] To address the shortcomings and deficiencies of existing technologies, the primary objective of this invention is to provide a method for preparing a layered solid elastomer electrolyte.

[0006] Inspired by the layered structure design of tires, this invention achieves both high ionic conductivity and interfacial stability through independently polymerized and cross-linked layered elastomer electrolytes, while also possessing the process compatibility required for industrial production.

[0007] Another object of the present invention is to provide a layered solid elastomer electrolyte prepared by the above preparation method.

[0008] Another object of the present invention is to provide the application of the above-mentioned layered solid elastomer electrolyte.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for preparing a layered solid elastomer electrolyte, comprising the following steps:

[0011] (1) Mix the acrylate mixture, the deep eutectic electrolyte system, the crosslinking agent and the thermal initiator, and then heat-cur them to obtain a high-pressure stable layer with self-supporting properties;

[0012] The deep eutectic electrolyte system includes succinate (SN) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0013] (2) Mix butyl fluorinated acrylate (HFA) and propylene-1,3-sulfonyl lactone (PS) to obtain solution A. Mix solution A, deep eutectic electrolyte system, crosslinking agent and thermal initiator to obtain mixture B. Drop mixture B onto lithium metal surface and heat-cured to obtain interface matching layer on lithium metal side.

[0014] The deep eutectic electrolyte system includes propylene-1,3-sulfonyl lactone (PS) and lithium difluorosulfonyl imide (LiFSI).

[0015] (3) The self-supporting high-pressure stabilizing layer and the interface matching layer on the lithium metal side are laminated together to obtain a layered solid elastomer electrolyte.

[0016] The high-voltage stabilizing layer obtained in step (1) of this invention is self-supporting and has excellent mechanical and high voltage stability. It is located near the positive electrode side in the battery and can solve the problem of poor high voltage stability of all-solid polymer electrolytes. The interface matching layer in step (2) is formed on the surface of the lithium metal negative electrode and has flexibility, which can solve the problem of poor interface matching between all-solid polymer electrolytes and electrodes. The two layers are independently prepared and laminated to form an integral elastomer electrolyte membrane without interface defects, which has high ionic conductivity, flexible mechanical properties and excellent interface stability.

[0017] Preferably, the acrylate mixture in step (1) comprises at least one of butyl acrylate (BA), butyl methacrylate (MBA), methyl methacrylate (MMA), and cyanoacrylate (AC); the mass ratio of at least one of butyl acrylate (BA), butyl methacrylate (MBA), methyl methacrylate (MMA), and cyanoacrylate (AC) is (1-4):1.

[0018] Preferably, the molar ratio of succinate (SN) and lithium bis(trifluoromethanesulfonylimide) (LiTFSI) in step (1) is (5-10):1.

[0019] Preferably, the mass ratio of the acrylate mixture and the deep eutectic electrolyte system in step (1) is (1-3):1.

[0020] Preferably, the crosslinking agent in step (1) includes at least one of acrylate compounds and acrylamide compounds containing active hydrogen; more preferably, the crosslinking agent includes at least one of ethoxylated trimethylolpropane triacrylate (ETPTA), polyethylene glycol methacrylate (PEGdA), and N,N-methyleneacrylamide (MBA); wherein the molecular weight of polyethylene glycol methacrylate (PEGdA) is 200-1000.

[0021] Preferably, the amount of crosslinking agent used in step (1) is 0.5-2.0 wt% of the high-pressure stabilizing layer.

[0022] Preferably, the thermal initiator in step (1) includes azo initiators, peroxide initiators, and combinations thereof; more preferably, the thermal initiator includes at least one of azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO).

[0023] Preferably, the amount of thermal initiator used in step (1) is 0.5-2.0 wt% of the high-pressure stabilizing layer.

[0024] Preferably, the temperature for heat curing in step (1) is 60-80℃ and the time is 8-15h.

[0025] Preferably, in solution A of step (2), the mass ratio of butyl fluoroacrylate (HFA) to propylene-1,3-sulfonyl ester (PS) is (1-3):1.

[0026] Preferably, the fluorobutyl acrylate in step (2) includes at least one of monofluorobutyl acrylate, difluorobutyl acrylate, trifluorobutyl acrylate, tetrafluorobutyl acrylate, pentafluorobutyl acrylate, hexafluorobutyl acrylate, heptafluorobutyl acrylate, octafluorobutyl acrylate and nonafluorobutyl acrylate.

[0027] Preferably, in the deep eutectic electrolyte system described in step (2), the molar ratio of propylene-1,3-sulfonolactone (PS) to lithium difluorosulfonylimide (LiFSI) is (2-3.5):1.

[0028] Preferably, the mass ratio of solution A and the deep eutectic electrolyte system in step (2) is (1-3):1.

[0029] Preferably, the crosslinking agent in step (2) includes at least one of acrylate compounds and acrylamide compounds containing active hydrogen; more preferably, the crosslinking agent includes at least one of ethoxylated trimethylolpropane triacrylate (ETPTA), polyethylene glycol methacrylate (PEGdA), and N,N-methyleneacrylamide (MBA); wherein the molecular weight of polyethylene glycol methacrylate (PEGdA) is 200-1000.

[0030] Preferably, the amount of crosslinking agent used in step (2) is 0.5-2.0 wt% of the interface matching layer.

[0031] Preferably, the thermal initiator in step (2) is selected from azo initiators, peroxide initiators and combinations thereof; more preferably, the thermal initiator includes at least one of azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO).

[0032] Preferably, the amount of thermal initiator used in step (2) is 0.5-2.0 wt% of the interface matching layer.

[0033] Preferably, the temperature for heat curing in step (2) is 50-70℃ and the time is 8-15h.

[0034] Preferably, the thickness of the high-pressure stabilizing layer in step (3) is 50-200 μm.

[0035] Preferably, in step (3), the thickness of the interface matching layer on the lithium metal side is 3-10 μm.

[0036] Preferably, the lamination process in step (3) includes at least one of manual pressure testing, mechanical rolling, and hydraulic pressure.

[0037] Preferably, the lamination pressure in step (3) is 0.1-2 MPa.

[0038] Secondly, the present invention provides a layered solid elastomer electrolyte prepared by the above preparation method.

[0039] Thirdly, the present invention provides the application of the above-mentioned layered solid elastomer electrolyte in batteries.

[0040] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0041] (1) The present invention achieves high ionic conductivity and good electrode interface stability through the synergistic effect of acrylate monomers and deep eutectic electrolyte system, while possessing excellent mechanical properties and scalable processing characteristics.

[0042] (2) The high voltage stabilizing layer of the present invention is self-supporting and has excellent mechanical and high voltage stability. It is located near the positive electrode side in the battery, which can solve the problem of poor high voltage stability of all-solid polymer electrolytes. The interface matching layer is formed on the lithium metal surface and has flexibility, which can buffer the growth of lithium dendrites. It can solve the problem of poor electrode interface matching of all-solid polymer electrolytes. The two layers are independently prepared and laminated to form an integral elastomer electrolyte membrane without interface defects, which has high ionic conductivity, flexible mechanical properties and excellent interface stability. Attached Figure Description

[0043] Figure 1 The EIS curve of the BA-AC monolayer solid elastomer electrolyte prepared in Example 1 at 30°C.

[0044] Figure 2 EIS curves of monolayer interface-matched solid elastomer electrolytes with different salt contents prepared in Example 2 are compared.

[0045] Figure 3 The LFP / Li full cell assembled in Example 3 with the layered solid-state elastomer electrolyte (in which propylene-1,3-sulfonyl lactone and lithium difluorosulfonyl imide are in a molar ratio of 2.5:1) was cycled.

[0046] Figure 4 The NCM811 / Li full cell assembled with the layered solid elastomeric electrolyte (in which propylene-1,3-sulfonyl lactone and lithium difluorosulfonyl imide are in a molar ratio of 2.5:1) in Example 3 was cycled at 4.5V.

[0047] Figure 5 The NCM811 / Li full cell assembled with the layered solid elastomeric electrolyte (in which propylene-1,3-sulfonyl lactone and lithium difluorosulfonyl imide are in a molar ratio of 2.5:1) in Example 3 was cycled at 4.7V.

[0048] Figure 6 The EIS curves of the NCM811 / Li full cell assembled with a monolayer BA-AC solid elastomer electrolyte in Comparative Example 1 are shown after cycling.

[0049] Figure 7 The NCM811 / Li full cell assembled with a monolayer BA-AC solid elastomer electrolyte in Comparative Example 1 was cycled at 4.5V.

[0050] Figure 8 The NCM811 / Li full cell assembled with monolayer HFA-PS solid elastomer electrolyte (in which propylene-1,3-sulfonyl lactone and lithium difluorosulfonyl imide are in a molar ratio of 2.5:1) in Comparative Example 2 was cycled at 4.5V. Detailed Implementation

[0051] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0052] Unless otherwise specified in the embodiments of this invention, the conditions shall be performed according to conventional conditions or conditions recommended by the manufacturer. All raw materials and reagents used, unless otherwise specified, are commercially available conventional products.

[0053] Example 1: Fabrication of a high-voltage stable layer near the positive electrode side

[0054] Butyl acrylate (BA) and cyanoacrylate (AC) were mixed at a mass ratio of 8:2 to obtain an acrylate mixture. Separate succinate (SN) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were mixed at a molar ratio of 10:1 to obtain a deep eutectic electrolyte system. The acrylate mixture and the deep eutectic electrolyte system were then mixed uniformly at a mass ratio of 2:1. 0.5 wt% of crosslinking agent ETPTA and 0.5 wt% of thermal initiator AIBN (both accounting for a percentage of the total mass of the high-voltage stabilizing layer of the electrolyte) were added. After uniform stirring, the mixture was coated onto a polytetrafluoroethylene (PTFE) plate and cured at 70°C for 12 hours to form a self-supporting film (BA-AC). The PTFE plate was removed, yielding a self-supporting film with a thickness of approximately 100 μm. EIS measurements showed an ionic conductivity of 4.2 × 10⁻⁶ at 30°C. -4 S•cm -1 .

[0055] Example 2: Fabrication of an interface matching layer near the negative electrode side

[0056] Solution A was prepared by mixing hexafluorobutyl acrylate (HFA) and propylene-1,3-sulfonyl lactone (PS) at a mass ratio of 1:1. A deep eutectic electrolyte system was prepared by mixing propylene-1,3-sulfonyl lactone (PS) and lithium difluorosulfonyl imide (LiFSI) at a molar ratio of 2.5:1. Solution A and the deep eutectic electrolyte system were then mixed uniformly at a mass ratio of 2:1. 0.5 wt% of crosslinking agent ETPTA and 0.5 wt% of thermal initiator AIBN (both accounting for the total mass of the electrolyte interface matching layer) were added to obtain solution B. Solution B was drop-coated onto a lithium metal surface and heated at 60°C for 12 hours to crosslink, forming a flexible interface layer with a thickness of approximately 3 μm supported by lithium metal. The thickness refers to the thickness of the flexible film, excluding the lithium metal.

[0057] By changing the molar ratios of propylene-1,3-sulfonolactone (PS) and lithium bisfluorosulfonylimide (LiFSI) in the deep eutectic electrolyte system to 2:1, 3:1, and 3.5:1, flexible interface layers with different salt contents were obtained.

[0058] Example 3: Layered Assembly and Electrochemical Performance Testing

[0059] The self-supporting membrane (BA-AC) of Example 1 and the lithium metal-supported flexible interface layer of Example 2 were laminated (mechanical-hydraulic, pressure 1 MPa) to form a monolithic electrolyte, and LFP / Li and NCM811 / Li full cells were assembled for cycle testing. The results showed that... Figure 3 As shown, the LFP / Li full cell can cycle stably for more than 300 cycles at room temperature, with stable interface and no dendrite penetration.

[0060] Comparative Example 1

[0061] The monolayer BA-AC prepared in Example 1 was used as the polymer electrolyte to assemble NCM811 / Li full cells for testing. The results are as follows: Figure 6 As shown, the interface impedance gradually increases, and the cycling performance deteriorates significantly.

[0062] Comparative Example 2

[0063] The monolayer HFA-PS prepared in Example 2 (in which propylene-1,3-sulfonyl lactone and lithium difluorosulfonyl imide were in a molar ratio of 2.5:1) was used as the polymer electrolyte to assemble NCM811 / Li full cells for testing. The results are as follows: Figure 8 As shown, its electrochemical stability is very poor above 4.5V, making it unsuitable for high-voltage cathode materials such as NCM811.

[0064] from Figure 4 , Figure 7 and Figure 8 The comparison shows that the combined effect of the NCM811 / Li full cell assembled with a single-layer BA-AC solid elastomer electrolyte at 4.5V (only 99.52% coulombic efficiency and 48.7 mAh / g specific capacity after 100 cycles) and the NCM811 / Li full cell assembled with a single-layer HFA-PS solid elastomer electrolyte (where propylene-1,3-sulfonyl lactone and lithium difluorosulfonyl imide are in a molar ratio of 2.5:1) at 4.5V (only 97.01% coulombic efficiency and 31.4 mAh / g specific capacity after 30 cycles) is still lower than the effect of the NCM811 / Li full cell assembled with a layered solid elastomer electrolyte (where propylene-1,3-sulfonyl lactone and lithium difluorosulfonyl imide are in a molar ratio of 2.5:1) at 4.5V (still 99.81% coulombic efficiency and 149.9 mAh / g specific capacity after 180 cycles), indicating that the two layers in the layered solid elastomer electrolyte of this application have a synergistic effect.

[0065] Comparative Example 3

[0066] The traditional in-situ polymerized electrolyte is used, specifically:

[0067] Butyl acrylate (BA) and cyanoacrylate (AC) were mixed at a mass ratio of 8:2 to obtain an acrylate mixture. Succinate (SN) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were mixed at a molar ratio of 10:1 to obtain a deep eutectic electrolyte system. The acrylate mixture and the deep eutectic electrolyte system were mixed evenly at a mass ratio of 2:1, and 0.5 wt% of thermal initiator AIBN (accounting for the total mass of the electrolyte slurry) was added to obtain an electrolyte slurry. After immersing the PE separator in the electrolyte slurry for 10 seconds, it was assembled into an NCM811 / Li full cell and then heat-cured at 70°C for 12 hours. The results showed that there were monomer residues and interface inhomogeneity problems, making it difficult to control the consistency and stability of the process.

[0068] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a layered solid elastomer electrolyte, characterized in that, Includes the following steps: (1) Mix the acrylate mixture, the deep eutectic electrolyte system, the crosslinking agent and the thermal initiator, and then heat-cur them to obtain a high-pressure stable layer with self-supporting properties; The deep eutectic electrolyte system in step (1) includes succinate and lithium bis(trifluoromethanesulfonyl)imide; (2) Mix butyl fluorinated acrylate and propylene-1,3-sulfonyl lactone to obtain solution A. Mix solution A, deep eutectic electrolyte system, crosslinking agent and thermal initiator to obtain mixture B. Drop mixture B onto lithium metal surface and heat-cur to obtain interface matching layer on lithium metal side. The deep eutectic electrolyte system in step (2) includes propylene-1,3-sulfonolactone and lithium difluorosulfonylimide; (3) The self-supporting high-voltage stabilizing layer and the interface matching layer on the lithium metal side are laminated together to obtain a layered solid elastomer electrolyte; In step (2), the mass ratio of butyl fluoroacrylate to propylene-1,3-sulfonolactone in solution A is (1-3):

1. In the deep eutectic electrolyte system described in step (2), the molar ratio of propylene-1,3-sulfonolactone to lithium difluorosulfonylimide is (2-3.5):1; The mass ratio of solution A and the deep eutectic electrolyte system in step (2) is (1-3):1; The acrylate mixture in step (1) includes at least one of butyl acrylate, butyl methacrylate, methyl methacrylate, and a mixture of cyanoacrylate; The mass ratio of at least one of butyl acrylate, butyl methacrylate, and methyl methacrylate to cyanoacrylate is (1-4):1; The molar ratio of succinate and lithium bis(trifluoromethanesulfonylimide) in step (1) is (5-10):1; The mass ratio of the acrylate mixture and the deep eutectic electrolyte system in step (1) is (1-3):

1.

2. The preparation method according to claim 1, characterized in that, The fluorobutyl acrylate in step (2) includes at least one of monofluorobutyl acrylate, difluorobutyl acrylate, trifluorobutyl acrylate, tetrafluorobutyl acrylate, pentafluorobutyl acrylate, hexafluorobutyl acrylate, heptafluorobutyl acrylate, octafluorobutyl acrylate and nonafluorobutyl acrylate.

3. The preparation method according to claim 1, characterized in that, The thickness of the self-supporting high-pressure stabilizing layer described in step (3) is 50-200 μm; And / or, in the interface matching layer on the lithium metal side described in step (3), the thickness of the interface matching layer is 3-10 μm.

4. The preparation method according to claim 1, characterized in that, The crosslinking agent in step (1) includes at least one of acrylate compounds and acrylamide compounds containing active hydrogen; And / or, the amount of crosslinking agent used in step (1) is 0.5-2.0 wt% of the high-pressure stabilizing layer; And / or, the thermal initiator in step (1) includes azo initiators, peroxide initiators, and combinations thereof; And / or, the amount of thermal initiator used in step (1) is 0.5-2.0 wt% of the high-pressure stabilizing layer; And / or, the temperature for heat curing in step (1) is 60-80°C and the time is 8-15 hours.

5. The preparation method according to claim 4, characterized in that, The crosslinking agent in step (1) includes at least one of ethoxylated trimethylolpropane triacrylate, polyethylene glycol methacrylate, and N,N-methyleneacrylamide; wherein the molecular weight of polyethylene glycol methacrylate is 200-1000; And / or, the thermal initiator in step (1) includes at least one of azobisisobutyronitrile and benzoyl peroxide.

6. The preparation method according to claim 1, characterized in that, The crosslinking agent in step (2) includes at least one of acrylate compounds and acrylamide compounds containing active hydrogen; And / or, the amount of crosslinking agent used in step (2) is 0.5-2.0 wt% of the interface matching layer. And / or, the thermal initiator in step (2) includes azo initiators, peroxide initiators, and combinations thereof; And / or, the amount of thermal initiator used in step (2) is 0.5-2.0 wt% of the interface matching layer; And / or, the temperature for heat curing in step (2) is 50-70°C and the time is 8-15 hours.

7. The preparation method according to claim 6, characterized in that, The crosslinking agent in step (2) includes at least one of ethoxylated trimethylolpropane triacrylate, polyethylene glycol methacrylate, and N,N-methyleneacrylamide; wherein the molecular weight of polyethylene glycol methacrylate is 200-1000; And / or, the thermal initiator in step (2) includes at least one of azobisisobutyronitrile and benzoyl peroxide.

8. The preparation method according to claim 1, characterized in that, The lamination process in step (3) includes at least one of manual lamination, mechanical rolling, and hydraulic lamination; And / or, the lamination pressure value in step (3) is 0.1-2 MPa.

9. A layered solid elastomer electrolyte obtained by the preparation method according to any one of claims 1-8.

10. The application of the layered solid elastomer electrolyte of claim 9 in a battery.

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