A diaphragmless lithium ion battery

Abstract

The present application provides a diaphragm-free lithium ion battery. The battery comprises a positive electrode current collector, a positive electrode active material, a solid electrolyte, a solvent, a negative electrode active material, and a negative electrode current collector. The solid electrolyte is a solid porous organic polymer, which contains specific functional groups, including weakly coordinated anion groups, and the corresponding cation of the anion group is lithium ion. The porous polymer is a solid powder, which can act as a barrier between the positive electrode active material and the negative electrode active material, eliminating the need for a diaphragm and greatly improving the safety performance of the battery.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion batteries, specifically relating to a novel membrane-free lithium-ion battery. Background Technology

[0002] In response to the current problems with lithium-ion batteries in use, one widely concerned issue is how to improve the safety of lithium-ion batteries.

[0003] The main components of currently widely used lithium-ion batteries are the positive electrode, negative electrode, separator, and electrolyte. The electrolyte, primarily composed of solvents, additives, and lithium salts, is a key component of lithium-ion batteries, responsible for transferring lithium ions within the battery. The separator is a specially shaped polymer film with a microporous structure. Its main function is to separate the positive and negative electrodes, allowing lithium ions to pass freely but preventing electrons from passing through. Currently, separators are made of organic polymers, which present two main problems: firstly, they can shrink, melt, or even carbonize when the battery or battery system experiences abnormal temperatures, causing large-area contact between the positive and negative electrodes, leading to short circuits or even explosions; secondly, impurities and burrs within the battery can puncture the separator, causing direct contact between the positive and negative electrodes and resulting in a short circuit.

[0004] Currently, one approach to addressing the safety concerns of traditional liquid lithium-ion batteries in the research field is the development of solid-state lithium-ion batteries. Solid-state lithium-ion batteries use a non-flammable solid electrolyte instead of the traditional liquid electrolyte, which can significantly improve the safety of lithium-ion batteries and has broad application prospects. However, drawbacks such as high interfacial resistance, low energy density, and poor cycle stability hinder the commercialization of solid-state electrolytes.

[0005] CN111799513A discloses a membrane-free quasi-solid-state battery and a method for preparing its composite electrode. An inorganic solid electrolyte layer is first coated onto the surface of the negative electrode, followed by an organic polymer layer to replace the separator. On one hand, the inorganic solid electrolyte layer has lithium-ion conductivity and high strength, improving the conductivity and mechanical strength of the lithium-ion battery. On the other hand, the organic polymer layer acts as a thermal shutdown coating. At room temperature, the pores between particles ensure the smooth passage of lithium ions, while at higher temperatures, the coating particles melt and collapse, isolating lithium ions and improving the safety performance of the lithium-ion battery. However, this electrolyte design still uses inorganic electrolytes and does not solve the problems of traditional inorganic active fillers: (1) If metal oxide solid electrolytes are used, high-temperature treatment is usually required, such as LLZO (>900℃); (2) If metal oxide or sulfide solid electrolytes are used, these substances are very sensitive to water or carbon dioxide in the air and are prone to react to form an inert surface layer; (3) The density of metal compounds is high, and the proportion of effective lithium active material is low. Adding a large amount is not conducive to improving the overall energy density of the battery; (4) The interfacial resistance between the positive or negative electrode active material and the solid electrolyte layer is usually very large, which greatly hinders the improvement of the rate performance of the battery. (Angew.Chem.Int.Ed.,2007,46,7778-7781.J.Power Sources,2015,293,721-725.J.Electrochem.Soc.,2020,167,70524.)

[0006] Therefore, the industry has begun to seek to utilize the advantages of both liquid and solid-state lithium-ion batteries while minimizing their disadvantages. This has led to the development of various gel-like electrolytes and semi-solid-state batteries. Examples include the gel cells used by Sony and the jelly-like battery launched by Svolt Energy at its Battery Day in late 2020, both of which utilize gel-like electrolytes. Gel polymer electrolytes, due to their near-liquid ion transport number and charge carrier concentration, can achieve an ionic conductivity of up to 10⁻⁶ at room temperature. -3 The S / cm ratio is high, and the gel polymer electrolyte that adsorbs the electrolyte has a safety feature that liquid electrolytes do not possess. However, for gel batteries with a low degree of polymerization, the gel itself has very low strength and cannot truly isolate the positive and negative electrodes, so a separator is still required.

[0007] In addition, gel polymer electrolytes, because they do not contain active lithium ions themselves, whether pure gel polymer electrolytes or polymer electrolytes composited with nanoparticles, are used as carriers of liquid electrolytes. This necessitates the addition of lithium hexafluorophosphate (LiPF6), an electrolyte that provides lithium ions. The production of LiPF6 requires highly toxic fluorine chemical processes, and because LiPF6 is highly susceptible to decomposition in water, it severely impacts battery cycle life and safety performance. Current solutions for moisture control, especially for high-nickel materials and cells using high-nickel materials, involve numerous processes performed in dehumidified environments. This not only wastes energy but also negatively affects the consistency of materials and cells. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a novel lithium-ion battery. The lithium-ion battery provided by this invention not only eliminates the need for a separator material but also eliminates the use of lithium hexafluorophosphate. Simultaneously, it significantly improves the battery's mechanical properties and safety performance, and exhibits cycle stability comparable to traditional liquid lithium-ion batteries.

[0009] The present invention provides a membraneless lithium-ion battery, comprising a positive electrode, a negative electrode, an electrolyte layer and an electrolyte solvent, wherein the electrolyte layer comprises a solid porous organic polymer electrolyte.

[0010] In this invention, the solid porous organic polymer electrolyte is in the form of a powder solid.

[0011] In this invention, the BET specific surface area of ​​the solid porous organic polymer electrolyte is ≥300 m². 2 / g, preferably greater than or equal to 500m 2 / g.

[0012] In this invention, the solid porous organic polymer electrolyte has a small pore size, generally with an average pore size of less than or equal to 10 nm, preferably less than or equal to 3 nm.

[0013] In this invention, the solid porous organic polymer electrolyte has a large pore volume, generally ≥0.15 cm³. 3 / g, preferably greater than or equal to 0.3cm 3 / g.

[0014] In this invention, the solid porous organic polymer electrolyte has a specific weakly coordinating anionic functional group, and its corresponding cation is located outside the framework, wherein the cation is a lithium ion.

[0015] In this invention, the porous organic polymer electrolyte containing weakly coordinating anions comprises at least one of the following weakly coordinating anion structures: boron-centered tetracoordinated anions (such as WCA-1, WCA-6), aluminum-centered tetracoordinated anions (such as WCA-2), phosphorus-centered hexacoordinated anions (such as WCA-3, WCA-5), silicon-centered hexacoordinated anions (such as WCA-4), etc.

[0016] The weakly coordinating anion preferably has the following structure:

[0017]

[0018]

[0019]

[0020] Weakly coordinated anions, due to the high coordination number of their core atoms and the strong electron-withdrawing ligands connecting them, possess a large delocalized electron cloud, resulting in weak binding to para-cations and reducing the hindrance to cation solvation. Solid porous organic polymer electrolytes are poorly soluble in common solvents such as water, alcohols, ethers, and esters. When weakly coordinated anions are integrated into porous organic polymers, the large specific surface area of ​​the polymer allows cations outside the framework to fully contact the solvent, enabling rapid migration within the solvent under voltage.

[0021] In this invention, the organic ligand directly or indirectly connected to the core atom in the weakly coordinating anion has an aromatic or polycyclic aromatic hydrocarbon structure. The aromatic or polycyclic aromatic hydrocarbon ring connected to a carbon atom can be at least one of hydrogen, fluorine, chlorine, and bromine, preferably fluorine.

[0022] In this invention, the electrolyte layer may further include one or more of a binder and a thickener. The material of the binder is not particularly limited; as long as it meets the requirements, those skilled in the art can choose flexibly according to actual needs. For example, the material forming the binder can be styrene-butadiene rubber or polyvinylidene fluoride, etc. In practical use, the porous organic polymer, thickener, and binder can be mixed evenly in deionized water or an organic solvent to prepare an electrolyte slurry; the electrolyte slurry is then coated onto the negative or positive electrode sheet; dried, cold-pressed, and cut into the required shape.

[0023] In some preferred embodiments of the present invention, the mass content of porous organic polymer in the electrolyte layer is 60-99%.

[0024] In this invention, the positive electrode includes a positive electrode active material and a positive electrode current collector.

[0025] In this invention, the positive current collector is aluminum foil.

[0026] In this invention, the positive electrode active material is one or more of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel manganese oxide, lithium nickel cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium-rich manganese oxide, lithium iron phosphate, lithium vanadium phosphate, lithium manganese phosphate, lithium cobalt phosphate, lithium manganese iron phosphate, lithium cobalt iron phosphate, and lithium nickel iron phosphate.

[0027] The positive electrode may also include a binder and a conductive agent. There are no particular restrictions on the materials of the binder and conductive agent; as long as they meet the requirements, those skilled in the art can choose flexibly according to actual needs. For example, the material forming the binder can be styrene-butadiene rubber or polyvinylidene fluoride, and the material forming the conductive agent can be conductive carbon black (Super P) or carbon nanotubes (CNTs). In practical applications, the positive electrode can be processed into a positive electrode sheet. Specifically: the positive electrode active material, conductive agent, and binder are prepared into a positive electrode slurry in N-methylpyrrolidone (NMP) solvent; the positive electrode slurry is uniformly coated onto the current collector aluminum foil at 90% of the negative electrode capacity; it is then dried, cold-pressed, and cut into the required shape. In this invention, the electrolyte solvent is at least one of the following: carbonate solvents (such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), methyl propyl carbonate (MPC), etc.), carboxylic acid ester organic solvents (such as γ-butyrolactone (BL), methyl formate (MF), methyl acetate (MA), methyl butyrate (MB), and ethyl propionate (EP), etc.), ether organic solvents (such as tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), 1,3-dioxolane (DOL), dimethyl ether (DME), and 4-methyl-1,3-dioxolane (4-MeDOL), etc.), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and nitrile organic compounds (acetonitrile, etc.).

[0028] In this invention, the negative electrode includes a negative electrode active material and a negative electrode current collector.

[0029] In this invention, the negative electrode active material is at least one of graphite, graphene, mesophase carbon microspheres, lithium metal, hard carbon, soft carbon, silicon suboxide, silicon dioxide, lithium titanate, silicon, tin, and germanium.

[0030] In this invention, the negative electrode current collector is a copper foil.

[0031] The negative electrode may also include a binder and a conductive agent. According to embodiments of this application, the materials of the binder and conductive agent are not particularly limited; as long as the requirements are met, those skilled in the art can flexibly choose according to actual needs. For example, the material forming the binder can be styrene-butadiene rubber or polyvinylidene fluoride, etc., and the material forming the conductive agent can be conductive carbon black (Super P) or carbon nanotubes (CNT), etc. In practical use, the negative electrode can be processed into a negative electrode sheet. Specifically: the negative electrode active material, conductive agent, thickener, and binder are mixed evenly in deionized water to form a negative electrode slurry; the negative electrode slurry is coated onto the current collector copper foil; dried, cold-pressed, and cut into the required shape.

[0032] This invention utilizes porous organic polymers containing weakly coordinating anions and their corresponding cations. Compared with existing technologies, this invention has the following advantages.

[0033] The porous polymer used in this invention is a solid powder. When coated between the positive and negative electrode materials, its high mechanical strength can hinder the contact between the positive and negative electrodes and prevent trace amounts of metal foreign objects from piercing the polymer layer. Therefore, it can replace the traditional separator and greatly improve the safety of the battery.

[0034] This invention creatively utilizes the weakly coordinating anions and corresponding cationic lithium ions present in the polymer backbone, which can directly conduct lithium ions in the solvent, playing a dual role as an electrolyte and a membrane. Unlike currently used gel electrolytes, it no longer needs to be activated by soaking in a solvent containing lithium hexafluorophosphate, thus eliminating the need for easily hydrolyzed lithium hexafluorophosphate.

[0035] This invention utilizes the large specific surface area and high pore volume of porous organic polymers. Lithium ions within the porous organic polymer framework can fully contact the solvent, thus enabling rapid lithium ion conduction and achieving cycle and rate performance comparable to traditional liquid electrolytes.

[0036] Because this invention still uses a solvent, lithium ions can be transported in a liquid solvent, which effectively solves the problems of interfacial resistance and cycle stability in the solid-solid two-phase contact of all-solid electrolytes. The interfacial resistance is small and the cycle stability is good.

[0037] This invention improves the water tolerance of lithium-ion batteries. In traditional liquid electrolytes, lithium hexafluorophosphate decomposes into hydrofluoric acid upon contact with even trace amounts of water. Hydrofluoric acid is highly corrosive to the cathode material, leading to gas generation and decreased cycle stability. This invention, by replacing readily decomposable lithium hexafluorophosphate with a more water-stable porous polymer, achieves greater water tolerance in cathode material and battery manufacturing processes. This improves battery safety and cycle performance, eliminates the need for power-intensive dehumidifiers during material synthesis and battery assembly, and reduces production costs for manufacturers. Detailed Implementation

[0038] The present invention will be further illustrated below by way of examples, but the present invention is not limited to these examples. Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in the art or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0039] Raw material source:

[0040] Preparation of solid porous organic polymers:

[0041] 1. Li-ABN has a specific surface area of ​​890 m². 2 / g, pore volume 0.61cm³ 3 / g, with the following structure:

[0042]

[0043] The synthesis of Li-ABN is described in the literature (Angew. Chem. Int. Ed. 2013, 52, 12174–12178).

[0044] The specific synthesis steps are as follows.

[0045]

[0046] Under an inert atmosphere, 1 kg of 1,4-dibromotetrafluorobenzene (Aladdin) was dissolved in 15 L of diethyl ether. Then, 1.3 L of 2.5 M n-butyllithium hexane solution was added dropwise to the solution, and the mixture was stirred for 60 minutes. Next, 850 mL of 1 M boron trichloride dichloromethane solution was added dropwise while stirring. After 30 hours, 15 L of deionized water was added to the reaction mixture, and the aqueous and organic phases were separated. The aqueous phase was extracted twice with diethyl ether, followed by phase separation. The resulting mixed organic phase was dried over anhydrous magnesium sulfate, and the diethyl ether was distilled under reduced pressure and then dried at 170 °C to obtain C. 24 BBr4F 16 Approximately 500g of white Li powder (monomer 1).

[0047] Under an inert atmosphere, 186 g of monomer 1, 4.62 g of tetrakis(triphenylphosphine)palladium and 1.52 g of cuprous iodide were added to a mixture containing 4 L of anhydrous tetrahydrofuran and 4 L of triethylamine. The mixture was stirred for 30 minutes, then 45 g of 1,3,5-triethynylbenzene was added. The mixture was then heated to 90 °C and stirred for 72 hours. After solid-liquid separation, the solid fraction was washed sequentially with 2 L of deionized water, methanol, and dichloromethane, and then dried at 120 °C for 4 hours to obtain 82 g of Li-ABN solid.

[0048] Among them, 1,4-dibromotetrafluorobenzene, n-butyllithium hexane solution, boron trichloride, diethyl ether, tetra(triphenylphosphine)palladium, cuprous iodide, triethylamine, methanol, and dichloromethane were all derived from Aladdin.

[0049] 2. The specific synthesis steps of Si-Polymer are as follows. Specific surface area: 1145 m² 2 / g, pore volume 0.25cm³ 3 / g.

[0050] 53 g of benzene-1,2,4,5-tetraol, 10 L of anhydrous ethanol, 0.55 L of a 1 M lithium methoxide methanol solution, and 1 L of a 0.25 M tetramethoxysilane methanol solution were added to a hydrothermal reactor. The reactor was then sealed and heated at 180 °C for four days, yielding a yellow turbid mixture. This mixture was then filtered through a solid-liquid filter, washed with anhydrous ethanol and anhydrous acetone, and dried to obtain 100 g of yellow Si-Polymer powder.

[0051] The structure of Si-Polymer is as follows:

[0052]

[0053] Among them, benzene-1,2,4,5-tetraol, tetramethoxysilane, lithium methoxide, and anhydrous ethanol are derived from Aladdin.

[0054] 3. The specific synthesis steps of P-Polymer are as follows. Specific surface area: 859 m² 2 / g, pore volume 0.22cm³ 3 / g

[0055] Under an inert atmosphere, 91.8 g of phosphorus pentachloride and 3 L of anhydrous toluene were added to a hydrothermal reactor, and the mixture was stirred at 50 °C for half an hour. 93.7 g of benzene-1,2,4,5-tetraol was added to the mixed solution, and the hydrothermal reactor was then sealed and reacted at 80 °C for 5 days. Afterward, the reactor was opened, and 275 mL of 1.6 M n-butyllithium hexane solution was added under an inert atmosphere. The reactor was then sealed again, and the reaction was continued at 80 °C for 2 days. The final reaction mixture was filtered, washed with anhydrous toluene and anhydrous acetone, and dried to obtain 103 g of powdered P-Polymer.

[0056] Phosphorus pentachloride, benzene-1,2,4,5-tetraol, and the 1.6M n-butyllithium hexane solution were all derived from Aladdin. The structure of p-Polymer is as follows:

[0057]

[0058] 4. The specific synthesis steps of polymer 1 are as follows. Its specific surface area is 58 m². 2 / g, with an average pore size of 1.8nm.

[0059] Monomer 1 was prepared using the same method as in the preparation of Li-ABN. In a hydrothermal reactor, 0.7 L of 1,5-cyclooctadiene, 1125 g of nickel di(cyclooctadiene), and 640 g of 2,2'-bipyridine were first dissolved in 30 L of anhydrous N,N-dimethylformamide. Then, 400 g of monomer 1 was added to the hydrothermal reactor, which was then heated at 130 °C for 4 days. The final reaction mixture was filtered, washed with methanol and anhydrous acetone, and dried to obtain 258 g of polymer 1.

[0060] Among them, 1,5-cyclooctadiene, di(cyclooctadiene)nickel, 2,2'-bipyridine, and N,N-dimethylformamide are all derived from Aladdin.

[0061] The structure of organic polymer 1 is as follows:

[0062]

[0063] LiNi 0.5 Co 0.2 Mn 0.3 The O2 comes from Wanhua Chemical's commercially available product, model C5010.

[0064] Example 1:

[0065] 1. Preparation of positive electrode sheet

[0066] A positive electrode slurry was prepared by stirring the positive electrode material, conductive agent Super P, and binder polyvinylidene fluoride (PVDF) in N-methylpyrrolidone (NMP) solvent. The positive electrode active material was LiNi. 0.5 Co 0.2 Mn 0.3 O2. The solid content of the positive electrode slurry is 70wt%, and the mass ratio of positive electrode material, conductive agent Super P and PVDF in the solid components is 96:1.5:2.5. The positive electrode slurry is uniformly coated on the current collector aluminum foil at 90% of the negative electrode capacity; after drying at 120℃, it is cold pressed; then it is trimmed, cut into sheets, and slit, and dried under vacuum at 120℃ for 2 hours to produce the positive electrode sheet for lithium-ion batteries.

[0067] 2. Preparation of negative electrode sheet

[0068] Graphite, used as the negative electrode active material, was mixed evenly with conductive agent Super P, thickener sodium carboxymethyl cellulose (CMC), and binder styrene-butadiene rubber (SBR) in deionized water to prepare a negative electrode slurry. The negative electrode slurry contained 50 wt% solids, and the mass ratio of graphite, Super P, CMC, and SBR in the solid components was 97:1:0.5:1.5. The negative electrode slurry was coated onto a current collector copper foil and dried at 100°C for 2 hours to prepare a lithium-ion battery negative electrode sheet.

[0069] 3. Preparation of electrolyte electrodes

[0070] A porous organic polymer, Li-ABN, serving as the electrolyte, was uniformly mixed with sodium carboxymethyl cellulose (CMC) as a thickener and styrene-butadiene rubber (SBR) as a binder in deionized water to prepare an electrolyte slurry. The electrolyte slurry contained 35 wt% solids, and the mass ratio of Li-ABN, CMC, and SBR in the solid components was 97:1.5:1.5. The electrolyte slurry was coated onto a negative electrode and dried at 85°C. After trimming, cutting, and slitting, the slurry was dried under vacuum at 120°C for 4 hours to produce the lithium-ion battery electrolyte and negative electrode.

[0071] 4. Preparation of electrolyte solvent

[0072] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed evenly at a mass ratio of EC:EMC = 30:70 to obtain the electrolyte solvent.

[0073] 5. Preparation of lithium-ion batteries

[0074] The positive electrode, electrolyte, and negative electrode obtained above are stacked in sequence and wound to obtain a bare cell. After welding the tabs, the bare cell is placed in an aluminum-plastic film outer packaging. The electrolyte solvent prepared above is injected into the lithium-ion battery. After encapsulation, standing, hot pressing formation (0.05C constant current charging to 3.0V, then 0.3C constant current charging to 3.4V, then 0.5C constant current charging to 3.85V), shaping, and capacity testing, the lithium-ion battery is completed (the thickness of the soft pack battery is 4.0mm, the width is 85mm, and the length is 120mm).

[0075] 6. Testing of lithium-ion batteries

[0076] The lithium-ion batteries prepared above were charged at 1C in the range of 2.75-4.2V, left to stand for 5 minutes, and then discharged at 1C, 3C and 5C respectively, and left to stand for 30 minutes after discharge.

[0077] Example 2:

[0078] The positive electrode, negative electrode, and electrolyte electrode were prepared using the same method as in Example 1. The main difference was that phosphorus-based polymer P-Polymer was used as a porous organic polymer when preparing the electrolyte electrode. Then, the electrolyte solvent was prepared using the same method as in Example 1 to prepare the lithium-ion battery, and the battery was tested.

[0079] Example 3:

[0080] The positive electrode, negative electrode, and electrolyte electrode were prepared using the same method as in Example 1. The main difference was that silicon-based polymer Si-Polymer was used as the porous organic polymer when preparing the electrolyte electrode. Then, the electrolyte solvent was prepared using the same method as in Example 1 to prepare the lithium-ion battery, and the battery was tested.

[0081] Comparative Example 1:

[0082] 1. Preparation of positive electrode sheet

[0083] A positive electrode slurry was prepared by stirring the positive electrode material, conductive agent Super P, and binder polyvinylidene fluoride (PVDF) in N-methylpyrrolidone (NMP) solvent. The positive electrode active material was LiNi. 0.5 Co 0.2 Mn 0.3O2. The solid content of the positive electrode slurry is 70wt%, and the mass ratio of positive electrode material, conductive agent Super P and PVDF in the solid components is 96:1.5:2.5. The positive electrode slurry is uniformly coated on the current collector aluminum foil at 90% of the negative electrode capacity; after drying at 120℃, it is cold pressed; then it is trimmed, cut into sheets, and slit, and dried under vacuum at 120℃ for 2 hours to produce the positive electrode sheet for lithium-ion batteries.

[0084] 2. Preparation of negative electrode sheet

[0085] Graphite, used as the negative electrode active material, was mixed evenly with conductive agent Super P, thickener sodium carboxymethyl cellulose (CMC), and binder styrene-butadiene rubber (SBR) in deionized water to prepare a negative electrode slurry. The negative electrode slurry contained 50 wt% solids, and the mass ratio of graphite, Super P, CMC, and SBR in the solid components was 97:1:0.5:1.5. The negative electrode slurry was coated onto a current collector copper foil and dried at 100°C for 2 hours to prepare a lithium-ion battery negative electrode sheet.

[0086] 3. Preparation of electrolyte

[0087] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed evenly at a mass ratio of EC:EMC = 30:70, and then lithium hexafluorophosphate is added to make the molar concentration of lithium hexafluorophosphate 1 mol / L, thus obtaining the electrolyte.

[0088] 4. Preparation of lithium-ion batteries

[0089] The positive electrode, separator, and negative electrode obtained above are stacked in sequence and wound to obtain a bare cell. After welding the tabs, the bare cell is placed in an aluminum-plastic film outer packaging. The electrolyte prepared above is injected into the lithium-ion battery. After encapsulation, standing, hot pressing formation (0.05C constant current charging to 3.0V, then 0.3C constant current charging to 3.4V, then 0.5C constant current charging to 3.85V), shaping, and capacity testing, the lithium-ion battery is completed (the thickness of the soft pack battery is 4.0mm, the width is 85mm, and the length is 120mm).

[0090] 5. Testing of lithium-ion batteries

[0091] The lithium-ion batteries prepared above were charged at 1C in the range of 2.75-4.2V, left to stand for 5 minutes, and then discharged at 1C, 3C and 5C respectively, and left to stand for 30 minutes after discharge.

[0092] Comparative Example 2:

[0093] 1. Preparation of positive electrode sheet

[0094] A positive electrode slurry was prepared by stirring the positive electrode material, conductive agent Super P, and binder polyvinylidene fluoride (PVDF) in N-methylpyrrolidone (NMP) solvent. The positive electrode active material was LiNi. 0.5 Co 0.2 Mn 0.3 O2. The solid content of the positive electrode slurry is 70wt%, and the mass ratio of positive electrode material, conductive agent Super P and PVDF in the solid components is 96:1.5:2.5. The positive electrode slurry is uniformly coated on the current collector aluminum foil at 90% of the negative electrode capacity; after drying at 120℃, it is cold pressed; then it is trimmed, cut into sheets, and slit, and dried under vacuum at 120℃ for 2 hours to produce the positive electrode sheet for lithium-ion batteries.

[0095] 2. Preparation of negative electrode sheet

[0096] Graphite, used as the negative electrode active material, was mixed evenly with conductive agent Super P, thickener sodium carboxymethyl cellulose (CMC), and binder styrene-butadiene rubber (SBR) in deionized water to prepare a negative electrode slurry. The negative electrode slurry contained 50 wt% solids, and the mass ratio of graphite, Super P, CMC, and SBR in the solid components was 97:1:0.5:1.5. The negative electrode slurry was coated onto a current collector copper foil and dried at 100°C for 2 hours to prepare a lithium-ion battery negative electrode sheet.

[0097] 3. Preparation of electrolyte electrodes

[0098] Using the same weakly coordinating anionic group WCA-6 as in Example 1, and employing the same synthetic method as Li-ABN, but without using 1,3,5-triethynylbenzene, which can support a porous structure, as a ligand, organic polymer 1 was obtained. This polymer 1 has a BET specific surface area of ​​58 m². 2 / g, with a pore size of 1.8nm.

[0099] Organic polymer 1, serving as the electrolyte, was mixed evenly with sodium carboxymethyl cellulose (CMC) as a thickener and styrene-butadiene rubber (SBR) as a binder in deionized water to prepare an electrolyte slurry. The electrolyte slurry contained 35 wt% solids, and the mass ratio of Li-ABN, CMC, and SBR in the solid components was 97:1.5:1.5. The electrolyte slurry was coated onto a negative electrode and dried at 85°C. After trimming, cutting, and slitting, it was dried under vacuum at 120°C for 4 hours to produce the lithium-ion battery electrolyte and negative electrode.

[0100] 4. Preparation of electrolyte solvent

[0101] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed evenly at a mass ratio of EC:EMC = 30:70 to obtain the electrolyte solvent.

[0102] 5. Preparation of lithium-ion batteries

[0103] The positive electrode, electrolyte, and negative electrode obtained above are stacked in sequence and wound to obtain a bare cell. After welding the tabs, the bare cell is placed in an aluminum-plastic film outer packaging. The electrolyte solvent prepared above is injected into the lithium-ion battery. After encapsulation, standing, hot pressing formation (0.05C constant current charging to 3.0V, then 0.3C constant current charging to 3.4V, then 0.5C constant current charging to 3.85V), shaping, and capacity testing, the lithium-ion battery is completed (the thickness of the soft pack battery is 4.0mm, the width is 85mm, and the length is 120mm).

[0104] 6. Testing of lithium-ion batteries

[0105] The lithium-ion batteries prepared above were charged at 1C in the range of 2.75-4.2V, left to stand for 5 minutes, and then discharged at 1C, 3C and 5C respectively, and left to stand for 30 minutes after discharge.

[0106] Through the examples and Comparative Example 1, it can be found that the capacity retention rate of the membrane-free lithium-ion battery of the present invention is comparable to that of traditional liquid lithium-ion batteries, maintaining approximately 80% of its capacity at 5C. However, Comparative Example 2, which uses a non-porous polymer containing weakly coordinating anions, shows varying degrees of capacity decay at both 1C and high-rate conditions. This is because when using a non-porous polymer, the amount of lithium ions exposed to the electrolyte solvent decreases significantly, preventing rapid migration of lithium ions when needed and leading to capacity decay.

[0107] Table 1. Capacity and Capacity Retention Rate at Different Ratios

[0108] 1C capacity mAh 3C capacity mAh 5C capacity mAh 5C Capacity Retention Example 1 3489 2965 2795 80％ Example 2 3455 2904 2736 79％ Example 3 3492 2973 2747 80％ Comparative Example 1 3425 2911 2807 82％ Comparative Example 2 2578 1624 1082 42％

Claims

1. A membrane-free lithium-ion battery, characterized in that, It includes a positive electrode, a negative electrode, an electrolyte layer, and an electrolyte solvent, wherein the electrolyte layer includes a solid porous organic polymer electrolyte; Solid porous organic polymer electrolytes have specific weakly coordinating anions, and their corresponding cations are located outside the framework, wherein the cation is a lithium ion; The solid porous organic polymer electrolyte is selected from the following structures: A-3 A-4 A-6； The BET specific surface area of ​​the solid porous organic polymer electrolyte is ≥300m2 / g.

2. The lithium-ion battery according to claim 1, characterized in that, Solid porous organic polymer electrolytes are in the form of powdered solids.

3. The lithium-ion battery according to claim 1, characterized in that, The BET specific surface area of ​​solid porous organic polymer electrolytes is greater than or equal to 500 m2 / g.

4. The lithium-ion battery according to claim 1, characterized in that, The average pore size of the solid porous organic polymer electrolyte is less than or equal to 10 nm.

5. The lithium-ion battery according to claim 4, characterized in that, The average pore size of the solid porous organic polymer electrolyte is less than or equal to 3 nm.

6. The lithium-ion battery according to claim 1, characterized in that, The pore volume of solid porous organic polymer electrolytes is ≥0.15 cm3 / g.

7. The lithium-ion battery according to claim 6, characterized in that, The pore volume of solid porous organic polymer electrolytes is ≥0.3 cm3 / g.

8. The lithium-ion battery according to claim 1, characterized in that, The electrolyte layer also includes one or more of the following: binder and thickener.

9. The lithium-ion battery according to claim 1, characterized in that, The mass content of porous organic polymers in the electrolyte layer is 60-99%.

10. The lithium-ion battery according to claim 1, characterized in that, The positive electrode includes a positive electrode active material and a positive electrode current collector.

11. The lithium-ion battery according to claim 10, characterized in that, The positive current collector is aluminum foil.

12. The lithium-ion battery according to claim 10, characterized in that, The positive electrode active material is one or more of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel manganese oxide, lithium nickel cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium-rich manganese oxide, lithium iron phosphate, lithium vanadium phosphate, lithium manganese phosphate, lithium cobalt phosphate, lithium manganese iron phosphate, lithium cobalt iron phosphate, and lithium nickel iron phosphate.

13. The lithium-ion battery according to claim 10, characterized in that, The positive electrode also includes binders and conductive agents.

14. The lithium-ion battery according to claim 1, characterized in that, The electrolyte solvent is one or more of the following: carbonate solvents, carboxylic acid ester organic solvents, ether organic solvents, N,N-dimethylformamide, dimethyl sulfoxide, and nitrile organic compounds.

15. The lithium-ion battery according to claim 1, characterized in that, The negative electrode includes a negative electrode active material and a negative electrode current collector.

16. The lithium-ion battery according to claim 15, characterized in that, The negative electrode active material is at least one of graphite, graphene, mesophase carbon microspheres, lithium metal, hard carbon, soft carbon, silicon suboxide, silicon dioxide, lithium titanate, silicon, tin, and germanium.

17. The lithium-ion battery according to claim 15, characterized in that, The negative electrode current collector is copper foil.

18. The lithium-ion battery according to claim 1, characterized in that, The negative electrode also includes binders and conductive agents.

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