Use of halogenated benzenes, electrolyte composition, solid electrolyte membrane, method for producing the same, and all-solid-state lithium battery

Abstract

The application relates to the field of electrochemistry, in particular to application of halogenated benzene series as electrolyte additives, an electrolyte composition, a solid-state electrolyte film, a preparation method of the solid-state electrolyte film and a full solid-state lithium battery. The full solid-state lithium battery of the application exhibits excellent cycle stability in a room temperature and below environment (<= 30 DEG C): the full solid-state lithium battery of the application can be stably cycled for 420 cycles under the condition of 30 DEG C, 0.1C charging and 0.5C discharging; the full solid-state lithium battery of the application can be stably cycled for 60 cycles under the condition of 20 DEG C, 0.1C charging and 0.1C discharging; the soft package battery exhibits excellent cycle stability at 30 DEG C, still exhibits stable discharging performance under external mechanical abuse (bending, shearing and needle puncture), does not appear to smoke and catch fire, and exhibits excellent safety, and the application provides a new selection for a practical room temperature full solid-state battery system.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, specifically to the application of a halobenzene compound as an electrolyte additive, an electrolyte composition, a solid electrolyte membrane and its preparation method, and an all-solid-state lithium battery. Background Technology

[0002] Since its commercialization, lithium-ion batteries have undergone thirty years of development, and their energy density has approached its limit (~300Wh / kg). -1 Solid-state electrolyte membrane technology is a key technical challenge that urgently needs to be overcome in the transformation of electrochemical energy systems towards safety and efficiency.

[0003] The mainstream technical routes fall into three categories: sulfides, oxides, and polymers. Among them, polymers have the advantages of excellent processability, low cost, and good solid-solid interface contact, but they also have the disadvantage of low room temperature ionic conductivity (<10). -5 Scm -1 Problems such as low ion mobility (25℃), low ion transference, and high interfacial impedance exist (Polymer, 1973, 14, 589; Nat. Rev. Mater., 2020, 5, 229-252). To address these bottlenecks in the room-temperature application of solid polymer electrolytes, researchers have conducted some studies. One paper (Adv. Funct. Mater., 2020, 30, 2007172) proposes that the plasticizing effect of succinonitrile (SN) reduces the crystallinity of the polymer and regulates the Li... + Coordination environment improves mass transfer kinetics. However, the continuous parasitic reaction between plasticizers and lithium metal leads to rapid deterioration of battery performance. Constructing a dense and stable solid electrolyte interphase (SEI) film to achieve long electrochemical lifetime is a problem we need to consider. The literature (Angew. Chem. Int. Ed., 2020, 59, 4131-4137) proposes to construct a high-ion conductor-polymer high-ion transport interface to improve room temperature ionic conductivity, but the current system does not meet the room temperature application requirements of all-solid-state batteries, and industrial application faces high production costs.

[0004] In the prior art, CN115769409A discloses an advanced solid electrolyte membrane that utilizes the excellent high ionic conductivity of cyano molecules, the good lithium salt dissociation characteristics of plasticizers, and the mechanical reinforcement properties of nano- and / or micro-sized particulate fillers to enable the solid electrolyte membrane to not only have good ionic conductivity and mechanical strength, but also excellent cycle stability.

[0005] CN115020818A discloses a polymer solid electrolyte membrane containing 2,3,4,5,6-pentafluorophenylboronic acid. 2,3,4,5,6-pentafluorophenylboronic acid, as an additive, can form a uniform and dense passivation layer in situ on the lithium metal anode side, thereby greatly reducing the reactivity of the lithium metal anode and effectively widening the electrochemical oxidation window of the electrolyte. This gives the solid electrolyte membrane excellent high-voltage stability of both the lithium metal anode and cathode, thus obtaining an all-solid-state lithium metal battery with excellent cycle performance and long-term stability.

[0006] US11881558B2 discloses a locally high-concentration electrolyte containing an aromatic fluorocarbon diluent, which reduces the electrolyte viscosity and regulates the Li... + The solvation structure reduces the number of carbonate solvent molecules in the solvent sheath, forming a uniform and dense passivation layer in situ, which gives the electrolyte excellent electrode interface stability and improves the cycle life of the full battery.

[0007] Although the above studies have attempted to improve the room temperature ion transport performance and interfacial mass transfer kinetics of lithium metal batteries from the perspectives of plasticizers, nanofillers, and electrode interfaces, the cumbersome additive processes and the progress made so far still cannot meet people's needs for room temperature cycle life and commercial applications. Summary of the Invention

[0008] The purpose of this invention is to overcome the problems of low room temperature ionic conductivity, low ion transference number, and high interfacial impedance of existing electrolytes, such as solid polymer electrolytes. This invention provides an application of halobenzene compounds as electrolyte additives, an electrolyte composition, a solid electrolyte membrane and its preparation method, and an all-solid-state lithium battery. This invention can improve lithium-ion transport performance and improve interfacial mass transfer kinetics, significantly improving the room temperature performance of all-solid-state lithium batteries.

[0009] To achieve the above objectives, a first aspect of the present invention provides the application of a halobenzene compound as an electrolyte additive, said halobenzene compound having the structure shown in formula (1):

[0010]

[0011] R1, R2, R3, R4, R5, and R6 are each halogen-containing groups.

[0012] A second aspect of the present invention provides an electrolyte composition comprising an ether-oxygenated polymer, a lithium salt, and an additive, wherein the additive has the structure shown in formula (1):

[0013]

[0014] R1, R2, R3, R4, R5, and R6 are each halogen-containing groups.

[0015] A third aspect of the present invention provides a solid electrolyte membrane formed from an electrolyte composition comprising the present invention.

[0016] A fourth aspect of the present invention provides a method for preparing a solid electrolyte membrane, the method comprising: providing an electrolyte solution containing the electrolyte composition described in the present invention, followed by forming a film and hot pressing to form a solid electrolyte.

[0017] The fifth aspect of the present invention provides an all-solid-state lithium battery, comprising the solid electrolyte membrane, positive electrode, and negative electrode described in the present invention.

[0018] This invention discovers that by utilizing the electron-deficient region at the tip of the halogen atom in the additive to form a halogen bond with the electron-rich region around the oxygen in the etheroxy polymer segment, the electron cloud density around the oxygen in the etheroxy polymer segment can be reduced, achieving lithium-ion "weak solvation." Furthermore, it can dynamically crosslink the etheroxy polymer segment, improving mechanical strength. During cycling, the etheroxy polymer electrolyte with the "weak solvation" structure preferentially forms a Li₂O-rich solid electrolyte interface film on the lithium metal surface, ensuring the strength of the interface structure. Thanks to the rapid lithium-ion diffusion within Li₂O, the interface impedance is significantly reduced, effectively suppressing lithium dendrite formation and improving the room temperature cycle life of the all-solid-state battery.

[0019] Applying the electrolyte additive of this invention to all-solid-state lithium batteries ensures stable cycling at 20°C-30°C. At 30°C, when matched with a lithium iron phosphate (LFP) cathode, it stably cycles 420 times under 0.1C charging and 0.5C discharging conditions. Even at 10°C, the all-solid-state lithium battery still achieves 60% of its theoretical capacity. At 30°C, the pouch cell exhibits excellent cycle stability.

[0020] The all-solid-state lithium battery of this invention exhibits excellent cycle stability at room temperature and below (≤30°C): It can stably cycle 420 times under 30°C, 0.1C charging, and 0.5C discharging conditions; it can stably cycle 60 times under 20°C, 0.1C charging, and 0.1C discharging conditions; at 30°C, the pouch battery exhibits excellent cycle stability, maintaining stable discharge performance even under external mechanical abuse (bending, shearing, and puncture), without smoke or fire, demonstrating excellent safety. This invention provides a new option for practical room-temperature all-solid-state battery systems. Attached Figure Description

[0021] Figure 1 The graph shows the rate performance of the Li||LFP all-solid-state batteries of Example 2 and Comparative Example 1 at 30°C.

[0022] Figure 2The graph shows the cycling performance (0.1C / 0.5C) of the Li||LFP all-solid-state batteries of Example 2 and Comparative Example 1 at 30°C.

[0023] Figure 3 The discharge curves (0.1C) of Example 2 are shown at 10°C, 20°C and 30°C.

[0024] Figure 4(a) shows the morphology of the lithium metal anode of the Li||LFP all-solid-state battery after 50 cycles in Example 2.

[0025] Figure 4(b) shows the morphology of the lithium metal anode of the Li||LFP all-solid-state battery in Comparative Example 1 after 50 cycles.

[0026] Figure 5 The graph shows the cycling performance (0.1C / 0.1C) of the Li||LFP all-solid-state battery in Example 2 at 20°C.

[0027] Figure 6 The discharge performance of the soft-pack battery in Example 2 under mechanical abuse conditions.

[0028] Figure 7 Impedance diagrams of the Li||LFP all-solid-state batteries of Example 2 and Comparative Example 1.

[0029] Figure 8 The image shows the O1s high-resolution X-ray photoelectron spectroscopy (XPS) spectra of the SEI on the surface of the lithium metal anode of the Li||LFP all-solid-state battery in Example 2 and Comparative Example 1. Detailed Implementation

[0030] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0031] This invention provides the application of a halobenzene compound as an electrolyte additive, the halobenzene compound having the structure shown in formula (1):

[0032]

[0033] R1, R2, R3, R4, R5, and R6 are each halogen-containing groups.

[0034] In this invention, all halobenzene compounds having the aforementioned structure can achieve the objectives of this invention. The range of possible choices for R1, R2, R3, R4, R5, and R6 is relatively wide. One embodiment is illustrated, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, R1, R2, R3, R4, R5, and R6 are each a halogen group. By employing the aforementioned preferred embodiment, high ionic conductivity, excellent mechanical strength, and good interfacial mass transfer kinetics can be achieved.

[0035] In this invention, the range of halogens that can be selected is relatively wide. One embodiment is illustrated by way of example, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the halogen group is -F, -Br, or -I.

[0036] In this invention, the number of each halogen group can be selected from a wide range. An exemplary embodiment is given, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, at least three of the substituents in R1, R2, R3, R4, R5, and R6 are -F, and the rest are -Br and / or -I.

[0037] The halobenzene compounds of the present invention have a wide range of applications. One embodiment is illustrated by example, but this does not limit the scope of the present invention. According to a preferred embodiment of the present invention, the halobenzene compounds of the present invention can be used as solid electrolyte additives or liquid electrolyte additives.

[0038] In this invention, the content of the halobenzene series in the electrolyte can be selected within a wide range. One embodiment is illustrated by way of example, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the content of the halobenzene series in the electrolyte is 5wt%-45%.

[0039] According to a preferred embodiment of the present invention, the halobenzene compound has the structures shown in formula (2), formula (3), and formula (4):

[0040]

[0041] By employing the aforementioned preferred embodiments, it is possible to achieve high ionic conductivity, excellent mechanical strength, and good interfacial mass transfer kinetics in all-solid-state batteries.

[0042] This invention provides an electrolyte composition comprising an ether-oxygenated polymer, a lithium salt, and an additive, wherein the additive has the structure shown in formula (1):

[0043]

[0044] R1, R2, R3, R4, R5, and R6 are each halogen-containing groups.

[0045] In this invention, additives having the aforementioned structures can achieve the objectives of this invention. The range of options for R1, R2, R3, R4, R5, and R6 is relatively wide. One embodiment is illustrated, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, R1, R2, R3, R4, R5, and R6 are each a halogen group. By employing the aforementioned preferred embodiment, high ionic conductivity, excellent mechanical strength, and good interfacial mass transfer kinetics can be achieved.

[0046] In this invention, the range of halogens that can be selected is relatively wide. One embodiment is illustrated by way of example, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the halogen group is -F, -Cl or -Br.

[0047] In this invention, the range of possible quantities of each halogen is relatively wide. One embodiment is illustrated by example, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, at least three of the substituents in R1, R2, R3, R4, R5, and R6 are -F, and the remainder are -Br and / or -I.

[0048] According to a preferred embodiment of the present invention, the halobenzene compound has the structures shown in formula (2), formula (3), and formula (4):

[0049]

[0050] By adopting the aforementioned technical solution, it is possible to achieve high ionic conductivity, excellent mechanical strength, and good interfacial mass transfer kinetics in all-solid-state batteries.

[0051] In this invention, the range of types of ether-oxygenated polymers is relatively wide. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the ether-oxygenated polymer is selected from one or more of polyethylene oxide (PEO), polyethylene glycol (PEG), and polyethylene glycol dimethyl ether (PEGDME).

[0052] In this invention, the number-average molecular weight of the ether-oxygenated polymer can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the number-average molecular weight of the ether-oxygenated polymer is 2,000-1,000,000, preferably 20,000-800,000, and more preferably 500,000-600,000.

[0053] Using the aforementioned preferred polymers can achieve high ionic conductivity, excellent mechanical strength, and good interfacial mass transfer kinetics in all-solid-state batteries.

[0054] In this invention, the range of lithium salts that can be selected is relatively wide. Commonly used lithium salts can all be used in this invention. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the lithium salt is selected from one or more of lithium bis(fluorosulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perchlorate, lithium hexafluorophosphate, lithium tetrafluoroborate, and lithium perfluoroalkyl sulfonate.

[0055] In this invention, the mass ratio of the additive to the total mass of the lithium salt and the ether-oxygenated polymer can be selected within a wide range. One embodiment is illustrated, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, the mass ratio of the additive to the total mass of the lithium salt and the ether-oxygenated polymer is 10-40:100, preferably 20-30:100. This enables the achievement of high ionic conductivity, excellent mechanical strength, and good interfacial mass transfer kinetics in all-solid-state batteries.

[0056] In this invention, the molar ratio of lithium salt to etheroxy polymer, based on the lithium:oxy molar ratio, has a wide selectable range. This is an illustrative embodiment, but does not limit the scope of the invention. According to a preferred embodiment of the invention, the molar ratio of lithium salt to etheroxy polymer, based on the lithium:oxy molar ratio, is 1:8-15. By employing the aforementioned preferred embodiment, high ionic conductivity, excellent mechanical strength, and good interfacial mass transfer kinetics can be achieved.

[0057] The present invention provides a solid electrolyte membrane formed from the electrolyte composition described herein.

[0058] In this invention, the thickness of the solid electrolyte membrane can be selected within a wide range. One embodiment is illustrated, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, the thickness of the solid electrolyte membrane is 5 μm-20 μm, preferably 10 μm-15 μm. This enables the achievement of high ionic conductivity, excellent mechanical strength, and good interfacial mass transfer kinetics in all-solid-state batteries.

[0059] The present invention provides a method for preparing a solid electrolyte membrane, the method comprising: providing an electrolyte solution containing the electrolyte composition described in the present invention, followed by film formation and hot pressing to form a solid electrolyte membrane.

[0060] In this invention, any method is used to dissolve the components of the electrolyte composition in a solvent to obtain an electrolyte solution containing the electrolyte composition described in this invention. One embodiment is illustrated by way of example, but it does not limit the scope of the invention. For example, in the presence of a solvent, the ether-oxygen polymer, lithium salt and additives are mixed evenly. Specifically, for example, the lithium salt and ether-oxygen polymer are added to the solvent first, and then the additives are added and mixed evenly.

[0061] More specifically, for example, in an argon-protected glove box (H2O < 0.01 ppm, O2 < 0.01 ppm), lithium salt is dissolved in a solvent, and an ether-oxygenated polymer is added and mixed evenly to form a blank control polymer electrolyte solution. Then, an additive is added to the blank control electrolyte solution and mixed evenly to obtain an electrolyte solution.

[0062] In this invention, as long as the purpose of this invention can be achieved, there are no special requirements for the mass ratio of the electrolyte composition to the solvent in the electrolyte solution. One embodiment is illustrated, but this does not limit the scope of the invention. For example, the mass ratio of the electrolyte composition to the solvent in the electrolyte solution is 0.1-0.5.

[0063] In this invention, the type of solvent selected during the preparation of the solid electrolyte membrane does not affect the performance of the solid electrolyte membrane and battery. Commonly used solvents can achieve the purpose of this invention. This invention is exemplified but does not limit the scope of the invention. For example, in the electrolyte solution, the solvent is selected from one or more of acetonitrile, tetrahydrofuran, and N,N-dimethylpyrrolidone.

[0064] In this invention, there are no special requirements for the method of forming the electrolyte solution into a film. Commonly used film-forming methods can be used in this invention, such as forming the electrolyte solution into a film by casting.

[0065] In this invention, there are no special requirements for the operating conditions of the casting method. The following is an illustrative description, but it does not limit the scope of the invention. For example, in the embodiments of this invention, the specific steps of the casting method include: applying an electrolyte solution to the surface of a substrate such as polyvinylidene fluoride (PVDF) using a doctor blade, and evaporating the solvent by heating a plate (40-80°C) to obtain an electrolyte film.

[0066] In this invention, there are no special requirements for the hot pressing operation steps and conditions. For example, the general steps include: forming a dense film by passing the film through a hot press, with the hot press plate temperature range being 80-100°C, and adjusting the electrolyte film thickness using a gasket such as a PVDF gasket.

[0067] In this invention, after hot pressing, drying is carried out as needed. There are no special requirements for the drying conditions. Generally, drying is carried out under vacuum conditions at a temperature of 60-100°C for 8-12 hours. Specifically, for example, baking is carried out in a vacuum drying oven at 60-100°C for 8-12 hours to remove residual organic solvents before assembly.

[0068] By employing the aforementioned preferred embodiments, high ionic conductivity, excellent mechanical strength, and good interfacial mass transfer kinetics can be achieved.

[0069] This invention provides an all-solid-state lithium battery, comprising the solid electrolyte membrane, positive electrode, and negative electrode described in this invention.

[0070] In this invention, the range of types of negative electrode active materials for the negative electrode of the all-solid-state lithium battery is relatively wide. Commonly used negative electrode active materials can all be used in this invention. One embodiment is illustrated by way of example, but it does not limit the scope of this invention. For example, the negative electrode active material is lithium metal and / or graphite.

[0071] In this invention, any commonly used positive electrode can achieve the purpose of this invention. There are no special requirements for the composition of the positive electrode active material layer. It is worth mentioning that an electrolyte component is generally added to the positive electrode active material layer, preferably the electrolyte composition described in this invention. There are no special requirements for the positive electrode active material, the type of conductive agent, and the binder and other substances and their specific composition in the positive electrode active material layer.

[0072] For example, the positive electrode active material is selected from lithium iron phosphate (LFP), sulfur, and nickel-cobalt-manganese ternary materials (NCM).

[0073] For example, the conductive agent is selected from one or more of Ketjen black, carbon nanotubes, and graphene.

[0074] There are no special requirements for the specific composition of the positive electrode active material layer. For example, the mass ratio of positive electrode active material LFP, electrolyte, and conductive agent is generally 5-10:1-5:1.

[0075] In this invention, the compaction density of the positive electrode can be selected from a wide range. One embodiment is illustrated, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, the compaction density of the positive electrode is 2.0 g / cm³. 3 -3.0g / cm 3 .

[0076] In this invention, the loading amount of the active material layer can be selected from a wide range based on the loading amount of the positive electrode active material. This is an illustrative embodiment, but does not limit the scope of the invention. According to a preferred embodiment of the invention, the loading amount of the positive electrode active material layer is 2.5-8.0 mg / cm³. 2 The aforementioned technical solution offers advantages such as high discharge specific capacity and good cycle stability.

[0077] In this invention, there are no special requirements for the preparation methods of the positive and negative electrodes, and they will not be described in detail here.

[0078] The all-solid-state lithium battery of this invention exhibits excellent cycle stability at room temperature and below (≤30°C): It can stably cycle 420 times under 30°C, 0.1C charging, and 0.5C discharging conditions; it can stably cycle 60 times under 20°C, 0.1C charging, and 0.1C discharging conditions; at 30°C, the pouch battery exhibits excellent cycle stability, maintaining stable discharge performance even under external mechanical abuse (bending, shearing, and puncture), without smoke or fire, demonstrating excellent safety. This invention provides a new option for practical room-temperature all-solid-state battery systems.

[0079] The present invention will be described in detail below through embodiments.

[0080] The organic solvents and lithium salt electrolytes used in the embodiments and comparative examples of this invention are all battery grade.

[0081] The ether-oxygenated polymer electrolyte solutions involved in this invention are all prepared in a glove box under an argon atmosphere with H2O and O2 content below 0.01ppm. Other battery components such as positive electrode, negative electrode, and solid electrolyte are all strictly dried. Solution preparation and battery assembly are all carried out at room temperature.

[0082] In the embodiments and comparative examples of this invention, the single-sided loading of active material on the positive electrode of the battery is 2.5 mg / cm³. 2 0.2C / 0.2C means charging at a rate of 0.2C and discharging at a rate of 0.2C; 0.1C / 0.5C means charging at a rate of 0.1C and discharging at a rate of 0.5C; 0.1C / 0.1C means charging at a rate of 0.1C and discharging at a rate of 0.1C.

[0083] Example 1

[0084] (1) Preparation of solid electrolyte membranes:

[0085] Under argon protection, 1.0 g of lithium bis(trifluoromethanesulfonylimide) and 1.5 g of polyethylene oxide with a number average molecular weight of 600,000 were measured in a glove box and added to 20 mL of anhydrous acetonitrile, and stirred until homogeneous. Then, additive 1,3,5-trifluoro-2,4,6-tribromobenzene was added at a mass ratio of 10:100 (additive / (lithium salt + polymer)) and mixed thoroughly. The electrolyte solution was then cast onto the surface of polyvinylidene fluoride (PVDF) using a casting method. Solvent was evaporated by heating on a hot plate (50°C) to obtain an electrolyte membrane. The electrolyte membrane was then formed into a dense membrane using a hot press at 80°C. The thickness of the electrolyte membrane was adjusted using PVDF gaskets. Before assembling the all-solid-state battery, the electrolyte membrane was baked in a vacuum drying oven at 70°C for 8 hours to remove residual organic solvents. The thickness of the solid electrolyte membrane was 10 μm.

[0086] The structural formula of 1,3,5-trifluoro-2,4,6-tribromobenzene is:

[0087] (2) Preparation of the positive electrode:

[0088] The preparation method of the positive electrode includes: using a common preparation method, the positive electrode active material LFP, the electrolyte composition (lithium bis(trifluoromethanesulfonyl)imide, polyethylene oxide with a number average molecular weight of 600,000, and additives in the same proportions as in step (1) above), and the conductive agent Ketjen black are uniformly dispersed in anhydrous acetonitrile at a mass ratio of 6:3:1. A uniform slurry is formed by using a planetary mixer. The slurry is then coated onto the surface of the current collector using a scraper. The slurry is pre-dried in a 70°C forced-air drying oven for 2 hours, followed by treatment in a 70°C vacuum drying oven for 12 hours to remove residual solvent. The resulting positive electrode sheet is compacted to a density of 2.5 g / cm³ using a roller press. 3 .

[0089] (3) Assembly of all-solid-state lithium batteries:

[0090] A positive electrode, a solid electrolyte membrane, and a lithium sheet (50 μm thick) are assembled into an all-solid-state lithium battery. The operation process is as follows: a stamped lithium sheet (14 mm in diameter) is attached to the electrolyte membrane (19 mm in diameter), and then the positive electrode (12 mm in diameter) is attached to the other side of the electrolyte membrane. The battery is then encapsulated with a 2032 button cell to form an all-solid-state lithium battery.

[0091] Example 2

[0092] (1) Preparation of solid electrolyte membranes:

[0093] Under argon protection, 1.0 g of lithium bis(trifluoromethanesulfonylimide) and 1.5 g of polyethylene oxide with a number average molecular weight of 600,000 were measured in a glove box and added to 20 mL of anhydrous acetonitrile, and stirred until homogeneous. Then, additive 1,3,5-trifluoro-2,4,6-tribromobenzene was added at a mass ratio of 30:100 (additive / (lithium salt + polymer)) and mixed thoroughly. The membrane preparation method was the same as in Example 1, and the thickness of the solid electrolyte membrane was 10 μm.

[0094] The preparation of the positive electrode and the assembly method of the all-solid-state lithium battery are the same as in Example 1.

[0095] Assembly of the pouch battery: A pouch battery was fabricated using a 3×4cm positive electrode, a 4×5cm solid electrolyte membrane, and a 3.5×4.5cm lithium metal negative electrode with a thickness of 45μm. An external LED bulb was used to characterize the discharge characteristics.

[0096] Example 3

[0097] (1) Preparation of solid electrolyte membranes:

[0098] Under argon protection, 1.0 g of lithium bis(trifluoromethanesulfonylimide) and 1.5 g of polyethylene oxide with a number average molecular weight of 600,000 were measured in a glove box and added to 20 mL of anhydrous acetonitrile, and stirred until homogeneous. Then, additive 1,3,5-trifluoro-2,4,6-tribromobenzene was added at a mass ratio of 50:100 (additive / (lithium salt + polymer)) and mixed thoroughly. The membrane preparation method was the same as in Example 1, and the thickness of the solid electrolyte membrane was 10 μm.

[0099] The preparation of the positive electrode and the assembly method of the all-solid-state lithium battery are the same as in Example 1.

[0100] Example 4

[0101] (1) Preparation of solid electrolyte membranes:

[0102] Under argon protection, 1.0 g of lithium bis(trifluoromethanesulfonylimide) and 1.5 g of polyethylene oxide with a number average molecular weight of 20,000 were measured in a glove box and added to 20 mL of anhydrous acetonitrile, and stirred until homogeneous. Then, additive 1,3,5-trifluoro-2,4,6-tribromobenzene was added at a mass ratio of 30:100 (additive / (lithium salt + polymer)) and mixed thoroughly. The membrane preparation method was the same as in Example 1, and the thickness of the solid electrolyte membrane was 10 μm.

[0103] The preparation of the positive electrode and the assembly method of the all-solid-state lithium battery are the same as in Example 1.

[0104] Example 5

[0105] (1) Preparation of solid electrolyte membranes:

[0106] Under argon protection, 1.0 g of lithium bis(fluorosulfonyl)imide (LiFSI) and 2.3 g of polyethylene oxide with a number average molecular weight of 600,000 were measured in a glove box and added to 20 mL of anhydrous acetonitrile, and stirred until homogeneous. Then, additive 1,3,5-trifluoro-2,4,6-tribromobenzene was added at a mass ratio of 30:100 (additive / (lithium salt + polymer)) and mixed thoroughly. The membrane preparation method was the same as in Example 1, and the thickness of the solid electrolyte membrane was 10 μm.

[0107] The preparation of the positive electrode and the assembly method of the all-solid-state lithium battery are the same as in Example 1.

[0108] Example 6

[0109] (1) Preparation of solid electrolyte membranes:

[0110] Under argon protection, 1.0 g of lithium bis(trifluoromethanesulfonylimide) and 1.5 g of polyethylene oxide with a number average molecular weight of 600,000 were measured in a glove box and added to 20 mL of anhydrous acetonitrile, and stirred until homogeneous. Then, additive 1,3,5-trifluoro-2,4,6-tribromobenzene was added at a mass ratio of 60:100 (additive / (lithium salt + polymer)) and mixed thoroughly. The membrane preparation method was the same as in Example 1, and the thickness of the solid electrolyte membrane was 10 μm.

[0111] The preparation of the positive electrode and the assembly method of the all-solid-state lithium battery are the same as in Example 1.

[0112] Example 7

[0113] (1) Preparation of solid electrolyte membranes:

[0114] Under argon protection, 1.0 g of lithium bis(trifluoromethanesulfonyl)imide and 1.5 g of polyethylene oxide with a number average molecular weight of 600,000 were measured in a glove box and added to 20 mL of anhydrous acetonitrile, and stirred until homogeneous. Then, additive 1,4-dibromotetrabenzene was added at a mass ratio of 30:100 (additive / (lithium salt + polymer)) and mixed thoroughly. The membrane preparation method was the same as in Example 1, and the thickness of the solid electrolyte membrane was 10 μm.

[0115] The preparation of the positive electrode and the assembly method of the all-solid-state lithium battery are the same as in Example 1.

[0116] The structural formula of 1,4-dibromotetrabenzene is:

[0117] Comparative Example 1

[0118] (1) Preparation of solid electrolyte membranes:

[0119] Under argon protection, 1.0 g of lithium bis(trifluoromethanesulfonylimide) and 1.5 g of polyethylene oxide with a number average molecular weight of 600,000 were measured in a glove box and added to 20 mL of anhydrous acetonitrile, and stirred until homogeneous. The membrane preparation method was the same as in Example 1, and the thickness of the solid electrolyte membrane was 10 μm.

[0120] The preparation of the positive electrode and the assembly method of the all-solid-state lithium battery are the same as in Example 1.

[0121] Comparative Example 2

[0122] (1) Preparation of solid electrolyte membranes:

[0123] Under argon protection, 1.0 g of lithium bis(trifluoromethanesulfonyl)imide and 1.5 g of polyethylene oxide with a number average molecular weight of 600,000 were measured in a glove box and added to 20 mL of anhydrous acetonitrile, and stirred until homogeneous. Then, additive 1,3,5-trifluorobenzene was added at a mass ratio of 30:100 (additive / (lithium salt + polymer)) and mixed thoroughly. The membrane preparation method was the same as in Example 1, and the thickness of the solid electrolyte membrane was 10 μm.

[0124] The structural formula of 1,3,5-trifluorobenzene is:

[0125] The preparation of the positive electrode and the assembly method of the all-solid-state lithium battery are the same as in Example 1.

[0126] Battery cycle performance test

[0127] The assembled Li||LFP batteries were left to stand overnight in a 60℃ oven before cycle performance testing. The all-solid-state batteries were first activated at 60℃ with 0.1C and 2.8V-3.8V, followed by electrochemical performance testing. The test and characterization results are shown in Table 1 and... Figures 1-8 .

[0128] Table 1 shows the cycle performance test results of the Li||LFP all-solid-state batteries in the examples and comparative examples. The active material loading was fixed in this test, and the electrochemical performance was evaluated based on the specific capacity.

[0129] Table 1

[0130]

[0131] The following tests were conducted using the all-solid-state battery from Example 2 as a test sample to illustrate the advantages of the method of the present invention:

[0132] Figure 1 The graph shows the rate performance of the Li||LFP all-solid-state batteries of Example 2 and Comparative Example 1 at 30°C; the batteries were charged and discharged sequentially at current densities of 0.1C, 0.2C, 0.5C, 1C, and 2C, followed by charge-discharge cycling at 0.5C. Figure 1 It is known that the solid electrolyte using the additives of the present invention has excellent rate performance in all-solid-state batteries, breaking through the bottleneck of the 1-rate performance of the comparative example. The battery still has highly reversible electrochemical performance after the rate test.

[0133] Figure 2 The graph shows the cycle performance (0.1C / 0.5C) of the Li||LFP all-solid-state batteries of Example 2 and Comparative Example 1 at 30°C; the batteries were charged and discharged at a charging current of 0.1C and a discharging current of 0.5C. Figure 2It can be seen that the solid electrolyte using the additives of the present invention has excellent room temperature electrochemical performance in all-solid-state batteries, breaking through the electrochemical performance bottleneck under room temperature conditions in Comparative Example 1.

[0134] Figure 3 The discharge curves (0.1C) for Example 2 are shown at 10°C, 20°C, and 30°C. Figure 3 It is known that the solid electrolyte using the additives of the present invention can achieve 60% of the theoretical capacity in all-solid-state batteries under 10°C testing conditions, demonstrating its potential for low-temperature operation.

[0135] Figure 4(a) shows the morphology of the lithium metal anode of the Li||LFP all-solid-state battery in Example 2 after 50 cycles. The battery was charged and discharged at a charging current of 0.1C and a discharging current of 0.5C. After 50 cycles, the battery was disassembled in an argon atmosphere glove box to obtain the lithium metal anode. The morphology of the lithium metal anodes of Example 2 and Comparative Example 1 was observed at the same magnification using an S-4800 scanning electron microscope (SEM). As shown in Figure 4(a), after the cycle test, the solid electrolyte using the additive of the present invention exhibits a smooth lithium deposition morphology in the lithium anode of the all-solid-state battery, indicating that the solid electrolyte using the additive of the present invention has high reversibility in the lithium anode of the all-solid-state battery. As shown in Figure 4(b), after the cycle test, the lithium anode of Comparative Example 1 showed a large amount of dendritic lithium deposition, indicating that the existing lithium anode has poor deposition / stripping reversibility, which limits the electrochemical lifetime.

[0136] Figure 5 This is a cycle performance graph (0.1C / 0.1C) of the Li||LFP all-solid-state battery of Example 2 at 20°C. The battery was charged and discharged at a charging current of 0.1C and a discharging current of 0.1C. Figure 5 It is known that the solid electrolyte using the additives of the present invention can be cycled in all-solid-state batteries at temperatures below room temperature.

[0137] Figure 6 The discharge performance of the pouch battery in Example 2 under mechanical abuse conditions is shown. An external LED bulb is used to characterize the discharge characteristics of the pouch battery. Figure 6 It is known that at 30°C, the pouch battery with solid electrolyte using the additive of the present invention exhibits excellent cycle stability. Under external mechanical abuse (bending, shearing, and puncture), it still exhibits stable discharge performance and does not smoke or catch fire, demonstrating excellent safety.

[0138] Figure 7Impedance plots of the Li||LFP all-solid-state batteries of Example 2 and Comparative Example 1 are shown. Electrochemical impedance spectroscopy (EIS) was performed after 10 charge-discharge cycles at a charging current of 0.1C and a discharging current of 0.5C. The EIS was measured using AC impedance analysis on a Princeton electrochemical workstation at test temperatures of 30°C and 60°C, and a frequency range of 0.01–100,000 Hz. Figure 7 As can be seen, compared with Comparative Example 1, the interface impedance of the present invention is significantly reduced, which helps the rapid mass transfer process at the electrode interface.

[0139] Figure 8 The image shows the O1s high-resolution X-ray photoelectron spectroscopy (XPS) spectra of the SEI on the surface of the lithium metal anode of the Li||LFP all-solid-state battery in Example 2 and Comparative Example 1. The battery was charged and discharged at a current of 0.1C and a current of 0.5C for 50 cycles. Afterward, the all-solid-state battery was disassembled in an argon-atmosphere glove box to obtain the lithium metal anode for XPS testing. The O1s high-resolution X-ray photoelectron spectroscopy (XPS) spectra of the SEI on the surface of the lithium metal anode of the all-solid-state lithium battery were obtained using D / max-2550 X-ray photoelectron spectroscopy combined with argon-ion sputtering conditions. Figure 8 It can be seen that Comparative Example 1 forms an organic component negative electrode SEI on the lithium metal surface, while the present invention forms a dense Li2O-rich solid electrolyte interface film on the lithium metal surface, thereby improving the interface transport kinetics and enhancing the lithium metal / electrolyte interface cycle stability of the room temperature all-solid-state battery.

[0140] The results above demonstrate that the all-solid-state battery using the solid electrolyte membrane described in this invention exhibits superior room-temperature cycling stability and lithium deposition morphology. The solid electrolyte membrane of this invention preferentially forms a dense Li₂O-rich solid electrolyte interface film on the lithium metal surface, improving interface transport dynamics, significantly reducing battery internal resistance, and thus effectively enhancing the cycling stability of the room-temperature all-solid-state battery.

[0141] The all-solid-state lithium battery of this invention exhibits excellent cycle stability at room temperature and below (≤30°C): It can stably cycle 420 times under 30°C, 0.1C charging, and 0.5C discharging conditions; it can stably cycle 60 times under 20°C, 0.1C charging, and 0.1C discharging conditions; at 30°C, the pouch battery exhibits excellent cycle stability, maintaining stable discharge performance even under external mechanical abuse (bending, shearing, and puncture), without smoke or fire, demonstrating excellent safety. This invention provides a new option for practical room-temperature all-solid-state battery systems.

[0142] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. Use of a halogenated benzene in an electrolyte as an additive, characterized in that, The halobenzene compounds have the structure shown in formula (1): R1, R2, R3, R4, R5, and R6 are each halogen-containing groups.

2. The application according to claim 1, wherein, R1, R2, R3, R4, R5, and R6 are each halogen groups; and / or The halogen group is -F, -Br, -I; and / or At least three of the substituents in R1, R2, R3, R4, R5, and R6 are -F, and the rest are -Br and / or -I; and / or The electrolyte is a solid electrolyte or a liquid electrolyte; and / or The content of the halobenzene series in the electrolyte is 5wt%-45wt%; Preferably, The halobenzene compounds have the structures shown in formula (2), formula (3), and formula (4):

3. An electrolyte composition, characterized in that, The composition comprises an ether-oxygenated polymer, a lithium salt, and an additive, wherein the additive has the structure shown in formula (1): R1, R2, R3, R4, R5, and R6 are each halogen-containing groups.

4. The composition according to claim 3, wherein, R1, R2, R3, R4, R5, and R6 are each halogen groups; and / or The halogen group is -F, -Br, or -I.

5. The composition according to claim 3 or 4, wherein, At least three of the substituents in R1, R2, R3, R4, R5, and R6 are -F, and the rest are -Br and / or -I; Preferably, the halobenzene compound has the structure shown in formula (2), the structure shown in formula (3), and the structure shown in formula (4):

6. The composition according to any one of claims 3-5, wherein, The ether-oxygenated polymer is selected from one or more of polyethylene oxide, polyethylene glycol, and polyethylene glycol dimethyl ether; and / or The number average molecular weight of the ether-oxygenated polymer is 2,000-1,000,000, preferably 20,000-800,000, more preferably 500,000-600,000; and / or The lithium salt is selected from one or more of lithium bis(fluorosulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perchlorate, lithium hexafluorophosphate, lithium tetrafluoroborate, and lithium perfluoroalkyl sulfonate.

7. The composition according to any one of claims 3-6, wherein, The total mass ratio of the additive to the lithium salt and the ether-oxygenated polymer is 10-40:100, preferably 20-30:100; and / or The molar ratio of the lithium salt to the ether-oxygen polymer is 1:8-15, based on the lithium:oxy molar ratio.

8. A solid electrolyte membrane formed from an electrolyte composition comprising any one of claims 3-7; Preferably, the thickness of the solid electrolyte membrane is 5μm-20μm, and more preferably 10μm-15μm.

9. A method for preparing a solid electrolyte membrane, characterized in that, The method includes: providing an electrolyte solution containing the electrolyte composition according to any one of claims 3-7, followed by film formation and hot pressing to form a solid electrolyte; Preferably, In the electrolyte solution, the mass ratio of the electrolyte composition to the solvent is 0.1-0.5; and / or In the electrolyte solution, the solvent is selected from one or more of acetonitrile, tetrahydrofuran, and N,N-dimethylpyrrolidone.

10. A fully solid-state lithium battery, characterized in that, It includes the solid electrolyte membrane of claim 8 or the solid electrolyte membrane prepared by the method of claim 9, a positive electrode, and a negative electrode.

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