A method for preparing hyperbranched polycarbonate-ceramic composite solid electrolyte and its application

Abstract

This invention discloses a method for preparing a hyperbranched polycarbonate-ceramic composite solid electrolyte and its application. The method utilizes the unique branched structure of hyperbranched polycarbonate to provide numerous ion transport channels, and employs a rigid / flexible silane coupling agent to perform dual surface modification on the ceramic filler. Uniform composite formation is then achieved through in-situ polymerization. The hyperbranched structure itself is beneficial for improving ionic conductivity, while the dual modification of the filler fundamentally improves its dispersibility—the rigid portion enhances interfacial stability, and the flexible portion improves compatibility, thereby significantly reducing filler agglomeration. The highly uniform dispersion of the modified filler constructs a continuous ion conduction network, significantly reducing transport impedance and fundamentally solving the problems of uneven filler dispersion and poor interfacial contact. It also significantly lowers the ion migration barrier, enabling the composite material to achieve high ionic conductivity at room temperature and achieving a significant improvement in overall performance.

Description

Technical Field

[0001] This invention relates to the field of electrolyte technology, and more particularly to a method for preparing a hyperbranched polycarbonate-ceramic composite solid electrolyte and its application. Background Technology

[0002] With the continuous growth of energy demand and the increasing prominence of environmental issues, lithium-ion batteries, due to their high energy density and long cycle life, have become the main power source for portable electronic devices, electric vehicles, and energy storage systems. However, the organic liquid electrolytes used in traditional lithium-ion batteries pose safety hazards such as flammability, volatilization, and leakage, easily leading to problems like short circuits and thermal runaway, severely restricting their application in high-energy-density energy storage systems. To improve the safety of lithium batteries and broaden their application range, solid-state electrolytes have become one of the research hotspots in recent years.

[0003] Solid electrolytes can be classified into inorganic ceramic electrolytes, polymer electrolytes, and composite electrolytes. Among them, inorganic ceramic electrolytes (such as Li7La3Zr2O) 12 Li 1.3 Al 0.3 Ti 1.7 (PO4)3) has attracted widespread attention due to its excellent mechanical strength, wide electrochemical window, and high lithium-ion conductivity. However, the brittleness of ceramic materials makes it difficult to form good interfacial contact with electrodes, limiting their application in practical batteries. Polymer electrolytes (such as polyethylene oxide (PEO) and polycarbonate (PC) based electrolytes) have become an important research direction due to their good flexibility and processability, but their lithium-ion conductivity is relatively low, especially at room temperature, making it difficult to meet the requirements of high-performance batteries. Composite solid-state electrolytes, by introducing inorganic fillers into a polymer matrix, aim to combine the advantages of both, namely, improving ionic conductivity while maintaining good mechanical properties and interfacial contact. However, existing composite solid-state electrolytes still have the following problems: 1. Poor interfacial contact between polymer and inorganic filler leads to high interfacial impedance, affecting ion transport; 2. Discontinuous ion transport channels limit the improvement of overall ionic conductivity; 3. Inorganic fillers are prone to agglomeration in the polymer matrix, affecting the uniformity and stability of the electrolyte; 4. The preparation process of composite electrolytes is complex, making large-scale production difficult.

[0004] Polycarbonate polymers are considered promising solid-state electrolyte matrix materials due to their high dielectric constant, good electrochemical stability, and good compatibility with lithium salts. However, traditional linear polycarbonates suffer from high crystallinity and poor chain segment mobility, limiting lithium-ion transport. Hyperbranched polymers, with their unique three-dimensional spherical structure, low crystallinity, high terminal group density, and good solubility, exhibit superior performance in multiple fields. Introducing hyperbranched structures into polycarbonates holds promise for overcoming the limitations of traditional linear polycarbonates and providing more lithium-ion transport channels. Furthermore, the surface properties of inorganic fillers significantly influence the performance of composite electrolytes. Unmodified ceramic fillers exhibit poor compatibility with the polymer matrix and are prone to agglomeration, leading to a decline in composite electrolyte performance. Composite solid electrolytes prepared using unmodified ceramic fillers show uneven filler dispersion, poor interfacial contact, and low room-temperature ionic conductivity.

[0005] Therefore, developing a composite solid electrolyte based on hyperbranched polycarbonate and surface-modified ceramic filler, and constructing a three-dimensional interpenetrating network structure through in-situ polymerization, is of great significance for improving the overall performance of solid electrolytes and promoting the practical application of all-solid-state lithium batteries. Summary of the Invention

[0006] This invention overcomes the shortcomings of the prior art and provides a method for preparing hyperbranched polycarbonate-ceramic composite solid electrolyte and its application.

[0007] To achieve the above objectives, the technical solution adopted by this invention is as follows: a method for preparing a hyperbranched polycarbonate-ceramic composite solid electrolyte, comprising the following steps:

[0008] S1: Cyclic carbonate monomers, polyol initiators and catalysts are mixed and subjected to ring-opening polymerization to obtain hyperbranched polycarbonate;

[0009] S2: A ceramic filler is mixed with a rigid silane coupling agent in an organic solvent to undergo a surface modification reaction, yielding a primary modified ceramic filler; the primary modified ceramic filler is then mixed with a flexible silane coupling agent in an organic solvent to undergo a surface modification reaction, yielding a surface-modified ceramic filler.

[0010] S3: Hyperbranched polycarbonate, surface-modified ceramic filler and lithium salt are mixed in a predetermined ratio and subjected to in-situ polymerization under specific temperature and time conditions to obtain hyperbranched polycarbonate-ceramic composite solid electrolyte.

[0011] In a preferred embodiment of the present invention, the cyclic carbonate monomer is selected from one or more of the following: cyclic ethylene carbonate, cyclic propylene carbonate, and cyclic ethylene carbonate; the polyol initiator is selected from one or more of the following: glycerol, pentaerythritol, and polyol-modified polysiloxane; and the catalyst is selected from one or more of the following: tin catalysts, zinc catalysts, and organic base catalysts.

[0012] In a preferred embodiment of the present invention, the ceramic filler includes one of oxide ceramics, sulfide ceramics, and halide ceramics. The oxide ceramics include one or more of LLZO, LATP, and LAGP; the sulfide ceramics include one or more of LGPS and LPS; and the halide ceramics include Li3YCl6.

[0013] In a preferred embodiment of the present invention, the rigid silane coupling agent is one or more of γ-glycidyl ether propyltrimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane, and the flexible silane coupling agent is γ-aminopropyltriethoxysilane.

[0014] In a preferred embodiment of the present invention, the lithium salt is selected from one or more of the following: LiTFSI, LiFSI, LiPF6, LiBF4, LiClO4; the molar ratio of the cyclic carbonate monomer, polyol initiator and catalyst is 10-100 : 1-10 : 0.01-1.

[0015] In a preferred embodiment of the present invention, the mass ratio of the ceramic filler, the rigid silane coupling agent, and the flexible silane coupling agent is 5-20:0.3-0.5:0.5-0.7.

[0016] In a preferred embodiment of the present invention, the ring-opening polymerization reaction is carried out at a temperature of 60-150 °C for 1-24 h, and the surface modification reaction is carried out at a temperature of 40-100 °C for 2-24 h.

[0017] In a preferred embodiment of the present invention, the mass ratio of the hyperbranched polycarbonate, the surface-modified ceramic filler, and the lithium salt is 40-80 : 10-50 : 5-20; the in-situ polymerization reaction is carried out at a temperature of 60-120 °C for 2-12 h.

[0018] To achieve the above objectives, the second technical solution adopted by this invention is: a sulfide solid electrolyte multi-scale interface structure: the room temperature ionic conductivity of the sulfide solid electrolyte multi-scale interface structure is 1×10⁻⁶. –3 Up to 1×10 –2 S / cm, electrochemical stability window is 0-5 V (vs. Li) + / Li).

[0019] To achieve the above objectives, the third technical solution adopted by this invention is: the application of a polymer-sulfide solid electrolyte multi-scale interface design in an all-solid-state lithium battery, resulting in an all-solid-state lithium battery comprising a positive electrode, a sulfide solid electrolyte multi-scale interface structure, and a negative electrode.

[0020] The positive electrode includes LiCoO2, LiNiO2, LiMn2O4, LiFePO4, and LiNi x Co y Mn z One or more of O2 (x+y+z=1);

[0021] The negative electrode is one or more of metallic lithium, lithium alloy, carbon material, silicon-based material or tin-based material;

[0022] The positive electrode also includes a conductive agent and a binder in a mass ratio of 70-90 : 5-15 : 5-15;

[0023] The all-solid-state lithium battery retains no less than 90% of its capacity after 400 cycles at a 1 C current density.

[0024] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0025] In this invention, the unique branched structure of hyperbranched polycarbonate provides a large number of ion transport channels. A rigid / flexible silane coupling agent is used to perform dual surface modification of the ceramic filler, followed by in-situ polymerization to achieve uniform composite. The hyperbranched structure itself is beneficial for improving ionic conductivity, while the dual modification of the filler fundamentally improves its dispersibility—the rigid part enhances interfacial stability, and the flexible part improves compatibility, thereby significantly reducing filler agglomeration. The highly uniform dispersion of the modified filler constructs a continuous ion conduction network, significantly reducing transport impedance. Simultaneously, the strong interfacial bond established by the coupling agent between the filler and the polymer matrix effectively reduces interfacial defects and contact impedance, fundamentally solving the problems of uneven filler dispersion and poor interfacial contact, and significantly reducing the ion migration barrier. This results in high ionic conductivity of the composite material at room temperature, achieving a significant improvement in overall performance.

[0026] Through innovative hyperbranched polycarbonate molecular design, more lithium-ion transport channels are provided, reducing the crystallinity of the polymer matrix, improving lithium salt dissociation and chain segment mobility, and significantly enhancing the ionic conductivity of the composite electrolyte. Compared to the room-temperature ionic conductivity of traditional linear polycarbonate solid electrolytes, the room-temperature ionic conductivity of the composite solid electrolyte of this invention is improved.

[0027] This invention improves the compatibility between ceramic fillers and polymer matrices by modifying the surface of the ceramic filler, reduces filler agglomeration, forms a uniformly dispersed composite structure, improves interfacial contact, and reduces interfacial impedance. Compared with unmodified ceramic filler composite solid electrolytes, the composite solid electrolyte of this invention exhibits more uniform dispersion, tighter interfacial contact, improved ionic conductivity, and enhanced cycle performance.

[0028] This invention employs an in-situ polymerization process to construct a three-dimensional interpenetrating network structure, forming continuous ion transport channels and improving ion transport efficiency. Simultaneously, it simplifies the preparation process and reduces production costs. Compared to traditional physical mixing methods, the in-situ polymerization process of this invention not only improves the performance of the composite electrolyte but also simplifies the preparation process, integrating multiple steps into a single step, significantly reducing production costs and energy consumption.

[0029] The hyperbranched polycarbonate-ceramic composite solid electrolyte prepared by this invention possesses excellent comprehensive performance, including high ionic conductivity, a wide electrochemical window, good mechanical properties, and good interfacial contact, providing a new option for the practical application of all-solid-state lithium batteries. All-solid-state lithium batteries using this composite solid electrolyte maintain a capacity retention of 90.97% after 400 cycles at 1 C current density, far exceeding the levels of traditional inorganic LLZO solid electrolytes, traditional polyethylene oxide solid electrolytes, and traditional linear polycarbonate solid electrolytes. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a flowchart illustrating the preparation process of the hyperbranched polycarbonate-ceramic composite solid electrolyte of the present invention.

[0032] Figure 2 This is a schematic diagram of the hyperbranched polycarbonate molecular structure of the present invention;

[0033] Figure 3 The ion transference number is that of the composite solid electrolyte prepared in Example 3 of this invention;

[0034] Figure 4 The ionic conductivity of the composite solid electrolyte prepared in Example 3 of this invention;

[0035] Figure 5 The electrochemical stability window of the composite solid electrolyte prepared in Example 3 of this invention;

[0036] Figure 6 The cycle performance of the solid lithium metal symmetric battery assembled with the composite solid electrolyte prepared in Example 3 of this invention;

[0037] Figure 7 The cycling performance of the full battery assembled with the composite solid electrolyte prepared in Example 3 of this invention is shown. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] 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. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0040] like Figure 1 As shown, a method for preparing a hyperbranched polycarbonate-ceramic composite solid electrolyte includes the following steps:

[0041] S1: Cyclic carbonate monomers, polyol initiators and catalysts are mixed and subjected to ring-opening polymerization to obtain hyperbranched polycarbonate;

[0042] S2: Mix ceramic filler with rigid silane coupling agent in an organic solvent to carry out a surface modification reaction, and obtain a primary modified ceramic filler; mix primary modified ceramic filler with flexible silane coupling agent in an organic solvent to carry out a surface modification reaction, and obtain a surface modified ceramic filler.

[0043] S3: Hyperbranched polycarbonate, surface-modified ceramic filler and lithium salt are mixed in a predetermined ratio and subjected to in-situ polymerization under specific temperature and time conditions to obtain hyperbranched polycarbonate-ceramic composite solid electrolyte.

[0044] The cyclic carbonate monomer is selected from one or more of the following: cyclic ethylene carbonate, cyclic propylene carbonate, and cyclic ethylene carbonate; the polyol initiator is selected from one or more of the following: glycerol, pentaerythritol, and polyol-modified polysiloxane; the catalyst is selected from one or more of the following: tin catalysts, zinc catalysts, and organic base catalysts.

[0045] Ceramic fillers include one of oxide ceramics, sulfide ceramics, and halide ceramics. Oxide ceramics include one or more of LLZO, LATP, and LAGP; sulfide ceramics include one or more of LGPS and LPS; and halide ceramics include Li3YCl6.

[0046] The rigid silane coupling agent is one or more of γ-glycidyl ether propyltrimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane, while the flexible silane coupling agent is γ-aminopropyltriethoxysilane.

[0047] The lithium salt is selected from one or more of the following: LiTFSI, LiFSI, LiPF6, LiBF4, LiClO4; the molar ratio of cyclic carbonate monomer, polyol initiator and catalyst is 10-100 : 1-10 : 0.01-1.

[0048] The mass ratio of ceramic filler, rigid silane coupling agent and flexible silane coupling agent is 5-20:0.3-0.5:0.5-0.7.

[0049] The ring-opening polymerization reaction is carried out at a temperature of 60-150 ℃ for 1-24 h, while the surface modification reaction is carried out at a temperature of 40-100 ℃ for 2-24 h.

[0050] The mass ratio of hyperbranched polycarbonate, surface-modified ceramic filler, and lithium salt is 40-80 : 10-50 : 5-20; the in-situ polymerization reaction temperature is 60-120 ℃, and the time is 2-12 h.

[0051] To achieve the above objectives, the second technical solution adopted by this invention is: a sulfide solid electrolyte multi-scale interface structure: the room temperature ionic conductivity of the sulfide solid electrolyte multi-scale interface structure is 1×10⁻⁶. –3 Up to 1×10 –2 S / cm, electrochemical stability window is 0-5 V (vs. Li) + / Li).

[0052] To achieve the above objectives, the third technical solution adopted in this invention is: the application of a polymer-sulfide solid electrolyte multi-scale interface design in an all-solid-state lithium battery, resulting in an all-solid-state lithium battery comprising a positive electrode, a sulfide solid electrolyte multi-scale interface structure, and a negative electrode.

[0053] The positive electrode includes LiCoO2, LiNiO2, LiMn2O4, LiFePO4, and LiNi x Co y Mn z One or more of O2 (x+y+z=1);

[0054] The negative electrode is one or more of metallic lithium, lithium alloy, carbon materials, silicon-based materials, or tin-based materials;

[0055] The positive electrode also includes a conductive agent and a binder, with a mass ratio of 70-90 : 5-15 : 5-15;

[0056] After 400 cycles at a 1 C current density, the capacity retention rate of the all-solid-state lithium battery is no less than 90%.

[0057] Example 1: Preparation of a hyperbranched polycarbonate-LLZO composite solid electrolyte based on cyclic ethylene carbonate, specifically as follows:

[0058] (1) Synthesis of hyperbranched polycarbonate:

[0059] 20 g of cyclic ethylene carbonate, 2 g of glycerol, and 0.1 g of dibutyltin dilaurate catalyst were mixed and reacted at 80 °C for 6 hours under a nitrogen atmosphere to obtain hyperbranched polycarbonate. Its number-average molecular weight was determined to be 15,000 and its degree of branching was 0.35 by GPC analysis.

[0060] (2) Surface modification of LLZO ceramic filler:

[0061] LLZO powder was mixed with γ-glycidyl ether propyltrimethoxysilane in 50 mL of toluene and stirred at 60 °C for 12 hours, then filtered. The filtered product was mixed with γ-aminopropyltriethoxysilane in 50 mL of toluene and stirred at 60 °C for 12 hours. After filtration and washing, the mixture was vacuum dried at 80 °C for 24 hours to obtain surface-modified LLZO powder. The mass ratio of ceramic filler, rigid silane coupling agent and flexible silane coupling agent was 5:0.5:0.5.

[0062] (3) In-situ polymerization preparation of composite solid electrolytes:

[0063] 6g of hyperbranched polycarbonate, 3g of surface-modified LLZO powder and 1g of LiTFSI were mixed evenly in 20mL of tetrahydrofuran and stirred at 80℃ for 4 hours. The mixture was then cast into a polytetrafluoroethylene mold and dried under vacuum at 100℃ for 12 hours to obtain a hyperbranched polycarbonate-LLZO composite solid electrolyte membrane.

[0064] Example 2: The difference between this example and Example 1 is that the mass ratio of ceramic filler, rigid silane coupling agent and flexible silane coupling agent is 5:0.2:0.8, and the rest are the same.

[0065] Example 3: The difference between this example and Example 1 is that the mass ratio of ceramic filler, rigid silane coupling agent and flexible silane coupling agent is 5:0.3:0.7, and the rest are the same.

[0066] Example 4: The difference between this example and Example 1 is that the mass ratio of ceramic filler, rigid silane coupling agent and flexible silane coupling agent is 5:0.4:0.6, and the rest are the same.

[0067] Example 5: The difference between this example and Example 1 is that the mass ratio of ceramic filler, rigid silane coupling agent and flexible silane coupling agent is 5:0.6:0.4, while the rest are the same.

[0068] Comparative Example 1: Preparation of a conventional linear polycarbonate solid electrolyte, specifically as follows:

[0069] (1) Mix 20g of linear polycarbonate (PC) and 1g of LiTFSI in 20mL of tetrahydrofuran until homogeneous;

[0070] (2) Stir the reaction at 80℃ for 4 hours;

[0071] (3) The mixture is poured into a polytetrafluoroethylene mold;

[0072] (4) The linear polycarbonate solid electrolyte membrane was obtained by vacuum drying at 100°C for 12 hours.

[0073] Performance testing and characterization

[0074] 1. Ion mobility testing

[0075] The composite solid electrolyte prepared in Example 1 was pressed into a disc with a diameter of 16 mm and a thickness of 0.02 mm, and assembled into a CR2032 coin cell using a lithium metal anode as the electrode. Lithium-ion transport number (LTON) The steady-state current method was used for determination. The battery was characterized using DC polarization and AC impedance before and after polarization. Calculations were performed according to the formula.

[0076]

[0077] in I 0 For the initial current, I ss For steady-state current, R 0 The initial resistance of the passivation layer. R ss This represents the resistance of the passivation layer after polarization. In the experiment, a voltage bias was applied. ΔV = 10 mV.

[0078] Test results are as follows Figure 3As shown, the lithium-ion transference number is 0.52, indicating that lithium ions have strong migration ability in this electrolyte, which helps to improve the overall performance of solid-state batteries, especially during fast charge and discharge processes.

[0079] 2. Ionic conductivity test

[0080] The composite solid electrolyte prepared in Example 1 was pressed into a disc with a diameter of 16 mm and a thickness of 0.02 mm. Carbon paste was coated on both sides as electrodes, and the discs were assembled into CR2032 coin cells. AC impedance testing was performed at different temperatures using an electrochemical workstation, with a frequency range of 1 Hz to 1 MHz and an amplitude of 10 mV. The ionic conductivity was calculated using the formula σ = L / (R × S), where L is the electrolyte thickness, R is the impedance, and S is the electrode area.

[0081] Test results are as follows Figure 4 As shown, the calculated ionic conductivity of the composite solid electrolyte prepared in Example 1 at room temperature (25 °C) is 4.8 × 10⁻⁶. –3 The conductivity is significantly higher than that of traditional linear polycarbonate-based solid electrolytes. This is because LGPS itself has high ionic conductivity, and through surface modification and in-situ polymerization, good interfacial contact is formed, constructing a continuous ion transport channel.

[0082] 3. Electrochemical stability window testing

[0083] The electrochemical stability window of the composite solid electrolyte prepared in Example 3 was tested using linear sweep voltammetry (LSV). A three-electrode system was employed, with a stainless steel working electrode and lithium metal as both the counter and reference electrodes. The scan rate was 0.1 mV / s, and the voltage range was 0–6 V (vs. Li). + / Li).

[0084] Test results are as follows Figure 5 As shown, the hyperbranched polycarbonate-LGPS composite solid electrolyte prepared in Example 1 has a wide electrochemical stability window of 0-5 V (vs. Li+ / Li), which can meet the requirements of most cathode materials.

[0085] 3. Battery performance testing

[0086] The all-solid-state lithium metal symmetric battery prepared in Example 1 was subjected to cycle performance testing. The test was conducted at 1 mA cm⁻¹. –2 Current density and 1 mAh cm –2 It loops within a certain capacity.

[0087] like Figure 6As shown, the all-solid-state lithium metal symmetric battery prepared in Example 1 remained stable after 500 cycles, with the polarization voltage maintained at 33 mV, exhibiting good cycle stability. This is mainly due to the excellent interfacial contact performance and mechanical strength of the hyperbranched polycarbonate-ceramic composite solid electrolyte, which effectively suppressed the growth of interfacial impedance.

[0088] Cyclic performance tests were conducted on the all-solid-state batteries prepared in Example 1 and Comparative Example 1, which were assembled with lithium metal as the negative electrode and lithium iron phosphate as the positive electrode. The batteries were cycled at a current density of 1 C and the voltage range was 2.4-4 V.

[0089] like Figure 7 As shown, the all-solid-state lithium battery prepared in Example 1 was cycled at a 1 C current density. The first cycle capacity was 141.45 mAh g⁻¹. –1 After 400 cycles, the capacity retention rate reached 90.97%, demonstrating excellent cycling stability.

[0090] 4. Best Practice Implementation Test

[0091] The ionic conductivity of Examples 1-5 was tested at room temperature (25°C), and the test data are shown in Table 1.

[0092] Table 1 shows the ionic conductivity test data of Examples 1-5 at room temperature (25°C).

[0093]

[0094] As shown in Table 1, with the increasing mass proportion of rigid silane coupling agents among ceramic fillers, rigid silane coupling agents, and flexible silane coupling agents, the ionic conductivity initially increases and then decreases. This is because when the proportion of rigid coupling agents is moderately increased, they can more effectively form a robust rigid interface layer on the surface of the ceramic filler. This significantly enhances the interfacial bonding strength between the filler and the polymer matrix, reduces interfacial defects and contact resistance, and creates a smoother and more stable migration channel for ions. Simultaneously, the rigid surface modification helps suppress filler agglomeration and promotes its uniform dispersion in the matrix, thereby optimizing the continuous ion conduction network. However, when the proportion of rigid coupling agents is too high, the filler surface will be wrapped with excessive rigid long chains. On the one hand, these rigid chain segments themselves lack flexibility, restricting the local movement of the chain segments and increasing the energy barrier for ion migration. On the other hand, an excessively rigid interface reduces the overall flexibility and interfacial compatibility of the composite material, inducing microcracks or new interfacial resistance, and disrupting the already formed uniform conduction path. Therefore, after reaching an optimal rigidity / flexibility balance point, the ionic conductivity begins to decrease due to excessive interface rigidity. Example 1 is the preferred embodiment.

[0095] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a hyperbranched polycarbonate-ceramic composite solid electrolyte, comprising: Its features are, S1: Cyclic carbonate monomers, polyol initiators and catalysts are mixed and subjected to ring-opening polymerization to obtain hyperbranched polycarbonate; S2: A ceramic filler is mixed with a rigid silane coupling agent in an organic solvent to undergo a surface modification reaction, yielding a primary modified ceramic filler; the primary modified ceramic filler is then mixed with a flexible silane coupling agent in an organic solvent to undergo a surface modification reaction, yielding a surface-modified ceramic filler; the rigid silane coupling agent is one or more of γ-glycidyl ether propyltrimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane, and the flexible silane coupling agent is γ-aminopropyltriethoxysilane; the mass ratio of the ceramic filler, the rigid silane coupling agent, and the flexible silane coupling agent is 5-20:0.3-0.5:0.5-0.7; S3: Hyperbranched polycarbonate, surface-modified ceramic filler, and lithium salt are mixed in a predetermined ratio and subjected to in-situ polymerization under specific temperature and time conditions to obtain hyperbranched polycarbonate-ceramic composite solid electrolyte; the mass ratio of hyperbranched polycarbonate, surface-modified ceramic filler, and lithium salt is 40-80:10-50:5-20; the temperature of the in-situ polymerization reaction is 60-120℃, and the time is 2-12h.

2. The method for preparing a hyperbranched polycarbonate-ceramic composite solid electrolyte according to claim 1, characterized in that: The cyclic carbonate monomer is selected from one or more of the following: cyclic ethylene carbonate, cyclic propylene carbonate, and cyclic ethylene carbonate; the polyol initiator is selected from one or more of the following: glycerol, pentaerythritol, and polyol-modified polysiloxane; the catalyst is selected from one or more of the following: tin catalysts, zinc catalysts, and organic base catalysts.

3. The method for preparing a hyperbranched polycarbonate-ceramic composite solid electrolyte according to claim 1, characterized in that: The ceramic filler includes one of oxide ceramics, sulfide ceramics, and halide ceramics. The oxide ceramics include one or more of LLZO, LATP, and LAGP; the sulfide ceramics include one or more of LGPS and LPS; and the halide ceramics include Li3YCl6.

4. The method for preparing a hyperbranched polycarbonate-ceramic composite solid electrolyte according to claim 1, characterized in that: The lithium salt is selected from one or more of the following: LiTFSI, LiFSI, LiPF6, LiBF4, LiClO4; the molar ratio of the cyclic carbonate monomer, polyol initiator and catalyst is 10-100:1-10:0.01-1.

5. The method for preparing a hyperbranched polycarbonate-ceramic composite solid electrolyte according to claim 1, characterized in that: The ring-opening polymerization reaction is carried out at a temperature of 60-150℃ for 1-24 hours, and the surface modification reaction is carried out at a temperature of 40-100℃ for 2-24 hours.

6. A multi-scale interface structure for a sulfide solid electrolyte, based on a method for preparing a hyperbranched polycarbonate-ceramic composite solid electrolyte according to any one of claims 1-5, characterized in that: Including sulfide ceramics, the room temperature ionic conductivity of the multi-scale interface structure of sulfide solid electrolytes is 1×10⁻⁶. –3 Up to 1×10 –2 S / cm, electrochemical stability window is 0-5V (vs. Li) + / Li).

7. An application of a polymer-sulfide solid electrolyte multi-scale interface design in all-solid-state lithium batteries, based on the sulfide solid electrolyte multi-scale interface structure described in claim 6, characterized in that... A fully solid-state lithium battery is obtained, comprising a positive electrode, a sulfide solid electrolyte multi-scale interface structure, and a negative electrode: The positive electrode includes LiCoO2, LiNiO2, LiMn2O4, LiFePO4, and LiNi x Co y Mn z One or more of O2 (x+y+z=1); The negative electrode is one or more of metallic lithium, lithium alloy, carbon material, silicon-based material or tin-based material; The positive electrode also includes a conductive agent and a binder, with a mass ratio of 70-90:5-15:5-15; The all-solid-state lithium battery retains a capacity of no less than 90.97% after 400 cycles at a 1C current density.

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