Composite electrolyte of lithium-ion battery, lithium-ion battery, and preparation methods therefor

Abstract

Provided are a composite electrolyte of a lithium-ion battery, a lithium-ion battery, and preparation methods therefor. The preparation method for the composite electrolyte of a lithium-ion battery comprises: subjecting a PSBNR-co-PTNI polymer to a heat treatment in an inert gas, so as to obtain a primary host matrix; compounding the primary host matrix with a solid electrolyte, so as to obtain a complex, wherein the solid electrolyte comprises LixLa3Zr1.4Ta0.6O12 and LiyAl0.5Ge1.5P3O12, where x=0.6 to 8, and y=0.6 to 4; dispersing the complex in a solvent, so as to obtain a dispersion; preparing the dispersion into a solid electrolyte film by using an electrostatic spinning method or a tape casting film-forming method; and subjecting the solid electrolyte film to a heat treatment in an inert gas, so as to obtain a composite electrolyte of a lithium-ion battery.

Description

Lithium ion battery composite electrolyte, lithium ion battery and preparation method thereof

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 4, 2024, with application number 2024100143511 and invention name "A lithium-ion battery composite electrolyte, lithium-ion battery and preparation method thereof", the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The embodiments of the present invention relate to, but are not limited to, the technical field of lithium-ion batteries, and specifically, to a lithium-ion battery composite electrolyte, a lithium-ion battery, and a preparation method thereof. Background Art

[0003] Compared with traditional liquid lithium batteries, solid-state lithium-ion batteries have higher safety and energy density, and are more environmentally friendly. They are one of the most promising technological directions in the current battery system.

[0004] Common solid-state lithium-ion batteries use inorganic solid electrolytes such as oxides or sulfides. However, the low ionic conductivity of oxide or sulfide electrolytes results in low electrical conductivity. Furthermore, the poor interfacial compatibility between oxide or sulfide electrolytes and electrode materials can lead to chemical reactions between the electrode materials and the electrolyte, easily forming an interfacial layer that affects the battery's cycle life and safety. These factors have limited the further promotion of solid-state lithium-ion batteries. In particular, solid-state polymer lithium-ion batteries (SPLBs) that use solid polymer electrolytes, such as the most widely used polyethylene oxide and its analogs, cannot meet practical application requirements due to their typically low energy density and the deterioration of electrolyte performance at high temperatures or high charge and discharge voltages. Summary of the Invention

[0005] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0006] The present invention discloses a method for preparing a composite electrolyte for a lithium-ion battery, comprising:

[0007] The PSBNR-co-PTNI polymer was heat-treated in an inert gas to obtain a basic host;

[0008] The basic host is compounded with a solid electrolyte to obtain a composite; wherein the solid electrolyte includes Li x La3Zr 1.4 Ta 0.6 O 12 He Li y Al 0.5 Ge1.5 P3O 12 , x = 0.6 to 8, y = 0.6 to 4;

[0009] dispersing the complex in a solvent to obtain a dispersion;

[0010] Using the dispersion liquid to prepare a solid electrolyte film by an electrostatic spinning method or a casting film forming method;

[0011] The solid electrolyte film is heat-treated under an inert gas to obtain a lithium-ion battery composite electrolyte.

[0012] Optionally, the heat treatment of the PSBNR-co-PTNI polymer in an inert gas includes: treating the PSBNR-co-PTNI polymer in a mixed gas of hydrogen and argon at 300° C. to 320° C. for 6 to 8 hours, wherein the volume fraction of the hydrogen in the mixed gas is 5%.

[0013] Optionally, the compounding of the basic host and the solid electrolyte to obtain the composite comprises: ultrasonically dispersing the basic host and the solid electrolyte in anhydrous ethanol, and drying to obtain the composite.

[0014] Optionally, the solid electrolyte film has a thickness of 3 μm to 20 μm and contains pores of 10 nm to 500 μm.

[0015] Optionally, heat-treating the solid electrolyte film under an inert gas comprises: keeping the solid electrolyte film in the inert gas at 300° C. to 350° C. for 3 hours to 6 hours.

[0016] The present invention also discloses a method for preparing an ion battery, comprising:

[0017] Sputtering a slurry of electrode material onto the front and back surfaces of a lithium-ion battery composite electrolyte by magnetron sputtering to prepare an electrode, wherein the lithium-ion battery composite electrolyte is prepared by the above-mentioned preparation method of the lithium-ion battery composite electrolyte;

[0018] The electrolyte is dripped onto the surface of the lithium ion battery composite electrolyte and the electrode to prepare a lithium ion battery.

[0019] Optionally, the electrode material includes a positive electrode material and a negative electrode material, wherein the positive electrode material is obtained by mixing a positive electrode active material, a binder polyvinylidene fluoride, a long-range conductive agent carbon nanotubes, and a short-range carbon-based conductive agent in a mass ratio of 96%:2%:1%:1%; and / or,

[0020] The negative electrode material is obtained by mixing a negative electrode active material, a binder styrene-butadiene rubber, a binder sodium carboxymethyl cellulose, and a short-range carbon-based conductive agent in a mass ratio of 96%:1.3%:1.8%:0.9%.

[0021] Optionally, the compaction density of the positive electrode material is 2.8 g / cm 3 to 3.8g / cm 3 The compaction density of the negative electrode material is 1.0 g / cm 3 to 1.8 / cm 3 ; and / or, the thickness of the electrode is 10μm to 150μm.

[0022] Optionally, the amount of the electrolyte added is 10 μL to 200 μL.

[0023] The embodiment of the present invention further discloses a lithium-ion battery, which is prepared by the above-mentioned method for preparing the lithium-ion battery composite electrolyte, or is prepared by the above-mentioned method for preparing the lithium-ion battery.

[0024] The lithium ion battery composite electrolyte, lithium ion battery and preparation method thereof of the embodiment of the present invention have the following beneficial effects: PSBNR-co-PTNI polymer is used as the basic host, and Li is filled inside. x La3Zr 1.4 Ta 0.6 O 12 He Li y Al 0.5 Ge 1.5 P3O 12 Solid electrolyte, and obtain a film composited with a polymer and a solid electrolyte by tape casting or electrostatic spinning. Among them, the PSBNR-co-PTNI polymer is heat-treated under an inert atmosphere before being compounded with the solid electrolyte to remove the oxygen-containing functional groups in the polymer, improve the chemical stability of the polymer material, and use it as a basic skeleton and thermochemical carrier, which can well control the thermal runaway of the electrochemical interface and help improve the safety and thermal stability of the battery. And after film formation, an inert gas heat treatment is carried out to remove the highly active negative groups on the surface of the film, so that the chemical properties of the surface of the electrolyte sheet are more stable, and the performance and reliability of the battery are further improved. The lithium-ion battery prepared by the embodiment of the present invention can greatly improve the energy density and safety performance of the battery. The battery energy density exceeds 300Wh / kg, and the battery can be normally charged and discharged under the conditions of acupuncture and heat spread, and the cost is relatively low.

[0025] Still other aspects will become apparent upon reading and understanding the detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1 is a flow chart of a method for preparing a composite electrolyte for a lithium-ion battery according to an embodiment of the present invention;

[0027] FIG2 is a schematic diagram of the internal structure of a lithium-ion battery according to an embodiment of the present invention;

[0028] FIG3 is a schematic diagram of a lithium-ion battery process flow in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the embodiments of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] The energy density, cost and high-temperature performance of existing large-scale mass-produced lithium-ion batteries need to be improved. Since the common LiPF6 / EC-DMC-EMC (LiPF6 lithium hexafluorophosphate, EC ethylene carbonate, DMC dimethyl carbonate, EMC ethyl methyl carbonate) electrolyte has poor electrode interface stability, it limits the large-scale application of high-nickel and silicon systems, thereby restricting the acquisition of high energy density of batteries. Common solid-state lithium-ion batteries or semi-solid-state lithium-ion batteries usually use oxide or sulfide electrolytes, but face the problems of ionic conductivity and interface compatibility that need to be improved. Common solid polymer electrolytes such as polyethylene oxide electrolytes will undergo severe decomposition at high temperatures or high voltages, resulting in poor cycle performance of high-nickel lithium batteries. They need to be improved through coating and other means, and the improvement effect is very limited.

[0031] Referring to FIG. 1 , a method for preparing a composite electrolyte for a lithium-ion battery according to an embodiment of the present invention includes:

[0032] The PSBNR-co-PTNI polymer is heat-treated in an inert gas to obtain a basic host;

[0033] The basic host and the solid electrolyte are compounded to obtain a composite; wherein the solid electrolyte includes Li x La3Zr 1.4 Ta 0.6 O 12 He Li y Al 0.5 Ge 1.5 P3O 12 , x=0.6 to 8; y=0.6 to 4;

[0034] dispersing the complex in a solvent to obtain a dispersion;

[0035] Using the dispersion liquid to prepare a solid electrolyte film by an electrostatic spinning method or a casting film forming method;

[0036] The solid electrolyte film is heat-treated under an inert gas to obtain a lithium-ion battery composite electrolyte (hereinafter referred to as composite electrolyte).

[0037] In this embodiment, PSBNR-co-PTNI polymer is used as the basic host, and Li x La3Zr 1.4 Ta 0.6 O 12 He Li y Al 0.5 Ge 1.5 P3O 12 Solid electrolyte, and by casting or electrospinning to obtain a film composite of polymer and solid electrolyte, and after the composite film is formed, an inert gas heat treatment is performed. Among them, the PSBNR-co-PTNI polymer is heat treated in an inert atmosphere before being composited with the solid electrolyte to remove the oxygen-containing functional groups in the polymer and improve the chemical stability of the polymer material. The polymer electrolyte of this embodiment does not deform at 200°C, and the material leakage current is 10 at a voltage of 300V. -6 A / cm 2 Compared to an alternative method such as polyethylene oxide decomposing under high temperature or high pressure, which leads to poor battery cycle performance, the polymer of this embodiment has better thermochemical stability, provides a very stable basic skeleton and thermochemical carrier, can well control the thermal runaway of the electrochemical interface, and help improve the safety and thermal stability of the battery. The inert gas heat treatment after composite film formation can remove the highly active negative groups on the surface of the film, making the chemical properties of the surface of the electrolyte sheet more stable, and further improving the performance and reliability of the solid-state battery. In addition, the polymer basic host is filled with a solid electrolyte, so that the composite electrolyte has higher ionic conductivity and interface compatibility.

[0038] The composite electrolyte prepared in this embodiment is used to prepare a battery, and the electrode interface has excellent stability. In charge and discharge tests under high temperature conditions, the battery does not experience obvious flatulence and interface side reactions. After testing, the battery can be normally charged and discharged at 80°C, and the battery has a coulombic efficiency of >97% at a 2C rate. At room temperature, it is cycled at 0.4C for 200 cycles, with a capacity retention rate of >90%, an energy density of more than 300Wh / kg, and a volume energy density of >700Wh / L, achieving the purpose of low-cost improvement of battery energy density and high-temperature performance.

[0039] In summary, since the energy density of existing batteries is not very high, it is difficult to meet the battery application requirements of more application scenarios. The improved solid electrolyte in this embodiment can match lithium-rich, high-nickel composite positive electrode materials and SiO x-graphite composite materials, resulting in a battery with high energy density, including both mass and volumetric energy density. The mass energy density reaches 300Wh / kg, and the volumetric energy density exceeds 700Wh / L. Furthermore, the polymer electrolyte treated with inert gas in this embodiment is safer and more reliable. The matrix polymer and lithium salt polymer composite effectively synergize the safety of the polymer matrix and the high-speed electron conduction capability of the lithium salt. Furthermore, electrospinning can be used to control the thickness, porosity, and microscopic pore size of the electrolyte membrane, thereby regulating the ion transport capacity of the polymer electrolyte.

[0040] An embodiment of the present invention further provides a method for preparing a lithium-ion battery, comprising:

[0041] Sputtering a slurry of electrode material onto the front and back surfaces of a lithium-ion battery composite electrolyte by magnetron sputtering to prepare an electrode, wherein the lithium-ion battery composite electrolyte is prepared by the preparation method of the lithium-ion battery composite electrolyte;

[0042] The electrolyte is dripped onto the surface of the lithium ion battery composite electrolyte and the electrode to prepare a lithium ion battery.

[0043] The electrode materials include positive electrode materials obtained by mixing positive electrode active materials, binders, and conductive agents, and negative electrode materials obtained by mixing negative electrode active materials, binders, and conductive agents.

[0044] This embodiment uses magnetron sputtering to produce a highly dense thin-film electrode material, enhancing the bonding between particles and improving the bonding between the electrode material and the electrolyte film. The electrode material is directly sputtered onto the surface of the solid electrolyte membrane, optimizing the battery manufacturing process and eliminating coating, rolling, and die-cutting processes, thereby reducing manufacturing costs. Furthermore, by dripping electrolyte onto the surface of the composite electrolyte and electrode material, lithium ion transport is enhanced, thereby improving the battery's ionic conductivity.

[0045] As shown in FIG2 and FIG3 , according to the present invention, in one embodiment, the specific steps of preparing a lithium-ion battery are as follows:

[0046] (1) First, the PSBNR-co-PTNI polymer is heat-treated in an inert gas, wherein the inert gas is a mixture of hydrogen and argon, wherein the volume fraction of hydrogen is 5%, the heat treatment temperature is 300°C to 320°C, and 300°C is optional. The treatment time is 6h to 8h, and 6h is optional.

[0047] The polymer was treated in an Ar / H2 (5% Vol) atmosphere at 300°C for 6 hours to remove oxygen-containing functional groups and improve the chemical stability of the polymer material. The molecular structure of the PSBNR-co-PTNI polymer is as follows:

[0048] The PSBNR-co-PTNI polymer electrolyte does not deform at 200°C and has a leakage current of 10 at 300V. -6 A / cm 2 The basic host of the electrolyte provides a very stable basic skeleton and thermochemical carrier, which provides excellent support for the safety and thermal stability of the battery system. After high-temperature inert gas treatment, the PSBNR-co-PTNI polymer has very good stability, constructing a three-dimensional thermochemically stable body, which can effectively control thermal runaway at the electrochemical interface, thereby improving battery safety.

[0049] In some embodiments, before the PSBNR-co-PTNI polymer is polymerized, the polymer monomer is frozen under liquid nitrogen to give the polymer a porous structure, and microscopically, an ultra-thin structure. Such a three-dimensional porous polymer can load more solid electrolytes, thereby increasing the effective electrolyte capacity of the battery, increasing the contact area between the electrode material and the electrolyte, promoting ion transport, and improving the energy density of the battery. In addition, more electrolyte is loaded in the porous structure of the polymer, which also reduces the leakage of the electrolyte to a certain extent, thereby improving the safety of the battery.

[0050] In some embodiments, the PSBNR-co-PTNI polymer is subjected to an arc treatment. This high-voltage arc treatment charges the polymer surface, resulting in microscopic polymer flakes electrostatically adsorbed onto the surface of the solid electrolyte, forming a polymer-encapsulated coating structure. This reduces direct contact between the solid electrolyte and the electrode material, minimizing electrolyte decomposition and electrode corrosion, and further improving the battery's temperature performance. Furthermore, the resulting coating structure can improve the battery's ion transport performance and interfacial stability, thereby increasing the battery's energy density.

[0051] (2) PSBNR-co-PTNI polymer and solid electrolyte (Li x La3Zr 1.4 Ta 0.6 O 12 He Li y Al 0.5 Ge 1.5 P3O 12 , wherein x=0.6 to 8; y=0.6 to 4) are ultrasonically dispersed in anhydrous ethanol, and these solid electrolytes are dispersed into the pores of the polymer by ultrasonic dispersion.

[0052] In this embodiment, a solid electrolyte is filled into the polymer electrolyte, and the mass ratio of the solid electrolyte to the polymer electrolyte is 1:2. The mass of the solid electrolyte is Li x La3Zr1.4 Ta 0.6 O 12 He Li y Al 0.5 Ge 1.5 P3O 12 The quality and. Thus, the dispersion and uniformity of the solid electrolyte in the polymer electrolyte are increased, thereby improving the ion transport performance and stability of the electrolyte, and improving the mechanical properties of the polymer electrolyte, and improving the overall electrochemical performance and cycle stability of the polymer solid electrolyte. Solid electrolyte Li x La3Zr 1.4 Ta 0.6 O 12 The chemical coefficient of Li can be from 0.6 to 8. y Al 0.5 Ge 1.5 P3O 12 The chemical coefficient of Li in the battery can be 0.6 to 4, and the chemical valence is regulated by oxygen ions. When the chemical coefficient of Li ions is less than 2, the active lithium concentration in the battery is low, the transfer rate is slow, and the energy density of the battery is about 305Wh / kg to 315Wh / kg. The lithium ion concentration in the material can reach 0.001moL / cm 2 to 0.009moL / cm 2 , the diffusion rate of lithium ions is 3*10 -5 cm 2 When the chemical coefficient of Li ions is greater than 2, the active lithium concentration and transfer speed in the battery will increase, the energy density of the battery can reach 315Wh / kg to 340Wh / kg, and the lithium ion concentration in the material can reach 0.01moL / cm 2 to 0.02moL / cm 2 , the diffusion rate of lithium ions is 3*10 -3 cm 2 / s, so Li can be adjusted according to needs + The concentration and transfer rate of solid electrolyte Li x La3Zr 1.4 Ta 0.6 O 12 Optional Li 6.4 La3Zr 1.4 Ta 0.6 O 12 (LLZTO), which has high ionic conductivity. Solid electrolyte Li y Al 0.5 Ge 1.5 P3O 12 Optional Li 1.5 Al 0.5 Ge 1.5P3O 12 (LAGP).

[0053] Ultrasonic dispersion allows solid electrolyte particles to be more evenly dispersed in the polymer matrix, improving the interfacial contact between the solid electrolyte and the polymer matrix, helping to form continuous ion transport channels and enhancing the ionic conductivity of the solid electrolyte. It also reduces the agglomeration of solid electrolyte particles and improves the dispersion and stability of the solid electrolyte.

[0054] (3) After drying the material mixed with the above-mentioned basic host and solid electrolyte, a composite is obtained. The composite has high ion transport performance and good mechanical stability, and can also improve the chemical stability and heat resistance of the electrolyte. The composite is dispersed in NMP (N-methylpyrrolidone) solvent to obtain an NMP dispersion of the polymer composite solid electrolyte. The NMP solvent has good adaptability to the dispersion and dissolution of the composite solid electrolyte, so that the dispersion has high dispersibility and solubility, which is convenient for subsequent use of casting or electrospinning process to form a uniform electrolyte layer, and helps to improve the quality and consistency of the electrolyte film.

[0055] (4) The dispersion is subjected to electrostatic spinning or casting to form a film to obtain a solid electrolyte film or a solid electrolyte sheet.

[0056] The thickness of the solid electrolyte sheet is 3μm to 20μm to provide sufficient mechanical support and ion transfer paths while maintaining low resistance. The length and width of the solid electrolyte sheet are designed and processed according to the morphology of the battery, mainly considering the overall performance and cost of the battery. The solid electrolyte sheet contains a large number of pores. The pore structure can provide more ion transfer channels and increase the load of electrode materials, thereby improving the energy density and cycle life of the battery. However, a pore size range that is too large will affect the mechanical properties of the material and the stability of the electrolyte. In this embodiment, the pore size inside the solid electrolyte sheet is 10nm to 500μm.

[0057] The tape casting method is a simple and efficient preparation process that facilitates large-scale production. Electrolyte sheets prepared using the tape casting method can be precisely controlled in thickness and compaction density, enabling fine-tuning of electrolyte properties. Furthermore, the tape casting method offers low cost and high efficiency, reducing battery production costs and improving production efficiency.

[0058] Electrolyte films produced by electrospinning have high porosity. Higher porosity means more ion transport channels, which helps improve the battery's charge-discharge performance and cycle life. By controlling the electrospinning process parameters, the thickness, porosity, and microscopic pore size of the electrolyte film can be precisely controlled, thereby achieving fine-tuning of the polymer electrolyte's ion transport capacity.

[0059] In this example, the distance between the electrospinning needle and the collecting plate is 10 to 15 cm, the needle diameter is 0.1 to 5 mm, the electrospinning voltage is 10 kV to 50 kV, and the feed rate is 0.1 mL / h to 1500 mL / h. The resulting fiber diameter is 0.01 μm to 10 μm. The pores and microfiber size of the electrospinning electrolyte film can be controlled, thereby regulating the porosity and pore size of the micropores, reducing the battery's DCR and improving battery life.

[0060] (5) After the electrolyte sheet is processed, it is kept warm in an inert gas atmosphere at 300°C to 350°C for 3 hours to 6 hours to remove impurities and highly active groups and improve the chemical stability inside the battery.

[0061] In this embodiment, the inert gas treatment further removes highly reactive negative groups on the material surface, making the surface chemically more stable and reducing adverse reactions with other electrode materials or electrolyte materials, thereby improving the cycle life and safety of solid-state batteries. Furthermore, by removing highly reactive groups and impurities, the electrolyte sheet can be treated to reduce potential side reactions during actual use, thereby improving the performance and reliability of solid-state batteries.

[0062] (6) The lithium-rich, high-nickel composite cathode material and the SiOx-graphite composite material system are dispersed in NMP, and the electrode material is sputtered on the front and back surfaces of the above-mentioned solid electrolyte film by magnetron sputtering.

[0063] In an alternative embodiment, the positive electrode material formula is: positive electrode active material: binder PVDF (polyvinylidene fluoride): long-range conductive agent CNTs (carbon nanotubes): short-range carbon-based conductive agent SP (carbon-based conductive agent) = 96%: 2%: 1%: 1%. PVDF as a binder helps improve the bonding between the positive electrode active material and the conductive agent, enhancing the mechanical stability of the electrode. The long-range conductive agent CNTs and the short-range carbon-based conductive agent SP can improve the electrode's conductivity, promote charge transfer and ion diffusion, and thus enhance battery performance and cycle life. The negative electrode material formula is: negative electrode active material: binder SBR (styrene-butadiene rubber): sodium carboxymethyl cellulose (sodium carboxymethyl cellulose): short-range carbon-based conductive agent SP = 96%: 1.3%: 1.8%: 0.9%. SBR and CMCNa as binders effectively fix the active material and conductive agent, improving the structural stability of the electrode. The short-range carbon-based conductive agent SP helps enhance the electrode's conductivity and improve the overall performance of the electrode material. The short-range carbon-based conductive agents used in the positive and negative electrode materials can be the same or different. Through the above configuration, the performance and stability of the active material can be balanced to a certain extent, while ensuring that the electrode material has good electrical conductivity and structural stability.

[0064] During magnetron sputtering, incident ions are generated using a low-pressure inert gas glow discharge. The cathode target is made of the coating material, and the substrate serves as the anode. Argon or other inert gas at a pressure of 0.1 to 10 Pa is introduced into the vacuum chamber. A negative DC voltage of 1 kV to 3 kV or a 13.56 MHz radio frequency voltage is applied to the cathode (target) to generate a glow discharge. The ionized argon ions bombard the target surface, causing target atoms to sputter and deposit on the substrate, forming an electrode film.

[0065] The thickness, compaction and surface density of the electrode materials on the front and back sides of the solid electrolyte are controlled by the voltage of the magnetron controller, the distance between the magnetron sputtering instrument and the electrolyte film, the diameter of the magnetron needle tube and the viscosity and solid content of the slurry. In this embodiment, the compaction density of the positive electrode material is 2.8g / cm 3 to 3.8g / cm 3 The compaction density of the negative electrode material is 1.0g / cm 3 to 1.8 / cm 3 , the thickness of the electrode material is between 10μm and 150μm.

[0066] In this embodiment, the lithium-rich, high-nickel composite positive electrode material, SiO x - Graphite composite material is coated on both sides of the electrolyte. Multiple electrolyte sheets, positive and negative electrodes, can produce batteries with higher energy density. Generally, more electrolyte layers require longer processing time and higher costs, and the battery cost is higher, but the power performance is also better. Considering the cost and power performance of the battery, the number of electrolyte sheets can be selected from 1 to 6 layers.

[0067] Since this embodiment adopts the composite form of polymer matrix and solid electrolyte, it avoids the poor interface between conventional electrodes and liquid electrolytes, thus being able to match lithium-rich, high-nickel composite positive electrode materials with low chemical stability and SiO x -graphite composite material, so that the energy density of the battery of this embodiment can exceed 300Wh / kg. 10 GeP2S 12 Solid electrolytes are relatively fragile and have relatively low chemical stability. When matched with the same material system as in this embodiment, the energy density is only 285Wh / kg, which is lower than the energy density of more than 300Wh / kg in this embodiment.

[0068] In this embodiment, the electrode material is directly sputtered onto the surface of the solid electrolyte membrane, which can optimize the battery manufacturing process, avoid coating, rolling and die-cutting processes, and reduce manufacturing costs. In addition, this embodiment adopts a high-nickel system, which can reduce the use of precious metal Co, while also giving play to the high capacity characteristics of high-nickel NCM and reducing the cost of electrode materials. In addition, in order to further reduce battery costs, the electrode material supported by the solid electrolyte can avoid the use of aluminum and copper, thereby saving material costs.

[0069] (7) Electrolyte solution (10 μL to 200 μL) was added dropwise onto the surface of the electrolyte and electrode materials.

[0070] By adding a small amount of electrolyte to the surface of the electrolyte and electrode materials, there is a very thin layer of liquid electrolyte inside the battery cell, which can graft the ion transmission channels of various interfaces, reduce the transmission impedance, and improve the lithium ion transmission behavior of the electrolyte.

[0071] The positive electrode and negative electrode of this embodiment can adopt a high-Ni positive electrode with a high gram capacity and a Si-based negative electrode. Therefore, in an optional embodiment, 2wt% tetramethyl silicate can be added to the electrolyte to construct a stable positive electrode interface film (SEI), and 1Wt% acetamide and 1Wt% sorbitol laurate can be added to stabilize the negative electrode SEI.

[0072] (8) The battery system is encapsulated using an aluminum-plastic film.

[0073] Since this embodiment uses an electrolyte with very good stability, the safety and reliability of the battery are greatly improved, so the battery packaging can be assembled using an aluminum-plastic film, thereby reducing the battery cost.

[0074] Example 1

[0075] The PSBNR-co-PTNI polymer was treated in an environment of Ar / H2 (5% VOL) ​​at 300 °C for 6 h, and the treated PSBNR-co-PTNI polymer and solid electrolyte Li x La3Zr 1.4 Ta 0.6 O 12 He Li y Al 0.5 Ge 1.5 P3O 12 (wherein, x=1.2; y=1.5) was ultrasonically dispersed in anhydrous ethanol, dried, and dispersed in NMP solvent. The PSBNR-co-PTNI polymer composite Li x La3Zr 1.4 Ta 0.6 O 12 He Li y Al 0.5 Ge1.5 P3O 12 Solid electrolyte NMP dispersion electrospinning, controlling the distance from the electrospinning needle to the collecting plate to be 10 cm to 15 cm, the diameter of the needle to be 0.1 mm to 5 mm, the electrospinning voltage to be 10 kV to 50 kV, the feed rate to be 0.1 mL / h to 1500 mL / h, the diameter of the obtained fiber to be 0.01 μm to 10 μm, to obtain an electrolyte film.

[0076] The film was kept warm in an inert gas atmosphere at 350°C for 3 hours, and the electrode materials were magnetron sputtered on both sides of the film. The content of the lithium-rich, high-nickel composite positive electrode material was 96%, and the SiO x -SiO in graphite composite material system x Finally, 10 μL to 200 μL of electrolyte solution was added dropwise onto the surface of the electrolyte and electrode materials, and the lithium-ion battery was encapsulated.

[0077] The differences between Examples 2-4 and Example 1, as well as performance data such as battery energy density, are shown in Table 1. The rest of the contents are the same and will not be repeated here.

[0078] Table 1

[0079] In this embodiment, PSBNR-co-PTNI polymer is used as a matrix, filled with solid electrolyte, and thin sheets are obtained by electrospinning or casting, and then heat-treated with inert gas. Liquid electrolyte is then added dropwise to assemble the composite electrolyte, which has high interface stability (interface compatibility) and ionic conductivity, with a conductivity of 1.1*10 -1 mS / cm to 9.9*10 -1 mS / cm, which is close to the conductivity level of liquid electrolyte. In addition, the battery prepared in this embodiment has a coulombic efficiency of >97% at a rate of 2C. At room temperature, 0.4C cycles for 200 cycles, and a capacity retention rate of >90%. It can be seen from Table 1 that the battery energy density exceeds 300Wh / kg, and with the increase of Li concentration in the solid electrolyte (changes from Example 1 to Example 4), the battery energy density is improved, and the energy density is increased from 310Wh / kg in Example 1 to 328Wh / kg in Example 4, and the volume energy density is increased from 710Wh / L in Example 1 to 736Wh / L in Example 4.

[0080] Conventional liquid batteries have poor electrode / electrolyte interface stability at high temperatures. When the temperature is greater than 60°C, the decomposition rate of the electrolyte on the electrode surface will accelerate, thereby increasing the internal pressure of the battery and causing phenomena such as rupture of the explosion-proof valve and contact between the electrolyte and the air. Under high temperature conditions, the electrolyte and the air are in direct contact, and the battery is prone to thermal runaway. The battery prepared in this embodiment has outstanding high temperature and safety reliability. It uses the PSBNR-co-PTNI polymer with very good chemical and thermal stability as the basic host to construct a three-dimensional thermochemical stable body, so that the chemical interface in the battery has high chemical stability. The thermal runaway risk of the liquid electrolyte is reduced in the battery, the thermal risk of the chemical interface is reduced, and the composite electrolyte will not undergo side reactions on the surface of the negative electrode. The measured data show that the battery can be charged and discharged normally at 80°C, and the battery has no obvious swelling and other phenomena.

[0081] In addition, this embodiment achieves cost reduction from multiple aspects, including: the use of low-Co materials in the positive electrode to achieve cost reduction; due to the use of low-cobalt content positive electrodes and electrolyte-supported electrode materials, at the level of precious metals and fluid materials, the battery of this embodiment can avoid the use of precious metals in metal current collectors and positive electrodes, and optimize the BOM cost (the standard cost of raw materials, parts, tools and labor required in the product manufacturing process); the solid electrolyte interface has excellent stability and can be manufactured on a large scale with reduced water content, thereby reducing process costs; the composite electrolyte of this embodiment can serve as both an ion conductor and a diaphragm, without using a diaphragm, thereby reducing the cost of the battery; in addition, the chemical system and electrode design of this embodiment can simplify the battery manufacturing process, can simplify the battery coating, rolling and die-cutting processes, and directly sputter the electrode material on the solid electrolyte surface, which can reduce the manufacturing cost of the battery, thereby achieving energy consumption and process cost reduction.

[0082] In summary, the lithium-ion battery prepared in this embodiment can greatly improve the energy density and safety performance of the battery. The battery energy density exceeds 300Wh / kg, and the battery can be charged and discharged normally under the conditions of battery needle puncture and heat spread, and the cost is relatively low.

[0083] Although the embodiments of the present invention are disclosed above, the protection scope of the embodiments of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the embodiments of the present invention, and these changes and modifications will fall within the protection scope of the embodiments of the present invention.

Claims

1. A preparation method of a lithium-ion battery composite electrolyte, comprising: Heat-treating a PSBNR-co-PTNI polymer in an inert gas to obtain a basic host; Composite the basic host with a solid electrolyte to obtain a composite; wherein, the solid electrolyte comprises Li x La3Zr 1.4 Ta 0.6 O 12 and Li y Al 0.5 Ge 1.5 P3O 12 , x = 0.6 to 8, y = 0.6 to 4; Disperse the composite in a solvent to obtain a dispersion; Use electrospinning or casting film method on the dispersion to prepare a solid electrolyte film; Heat-treat the solid electrolyte film under an inert gas to obtain a lithium-ion battery composite electrolyte.

2. The preparation method of the composite electrolyte for lithium ion battery according to claim 1, wherein, The heat-treatment of the PSBNR-co-PTNI polymer in an inert gas includes: Treat the PSBNR-co-PTNI polymer in a mixed gas of hydrogen and argon at 300°C to 320°C for 6 h to 8 h, wherein the volume fraction of hydrogen in the mixed gas is 5%.

3. The preparation method of the composite electrolyte for lithium ion battery according to claim 1, wherein, The compounding of the basic host and the solid electrolyte to obtain a composite includes: Ultrasonically disperse the basic host and the solid electrolyte in absolute ethanol, and after drying, obtain the composite.

4. The preparation method of the lithium-ion battery composite electrolyte according to claim 1, wherein, The thickness of the solid electrolyte film is 3 μm to 20 μm, and the interior contains pores of 10 nm to 500 μm.

5. The preparation method of the lithium-ion battery composite electrolyte according to claim 1, wherein, The heat-treatment of the solid electrolyte film under an inert gas includes: Keep the solid electrolyte film in the inert gas at 300°C to 350°C for 3 h to 6 h.

6. A preparation method of a lithium-ion battery, comprising: Sputter a slurry of an electrode material onto both the front and back sides of a lithium-ion battery composite electrolyte by magnetron sputtering to prepare an electrode, wherein the lithium-ion battery composite electrolyte is prepared by the preparation method of the lithium-ion battery composite electrolyte according to any one of claims 1-5; Drop an electrolyte solution onto the surfaces of the lithium-ion battery composite electrolyte and the electrode to prepare a lithium-ion battery.

7. The manufacturing method of the lithium ion battery according to claim 6, wherein, The electrode material includes a positive electrode material and a negative electrode material. The positive electrode material is obtained by mixing a positive electrode active material, a binder polyvinylidene fluoride, a long-range conductive agent carbon nanotube, and a short-range carbon-based conductive agent in a mass ratio of 96%:2%:1%:1%; and / or, The negative electrode material is obtained by mixing a negative electrode active material, a binder styrene-butadiene rubber, a binder sodium carboxymethyl cellulose, and a short-range carbon-based conductive agent in a mass ratio of 96%:1.3%:1.8%:0.9%.

8. The manufacturing method of the lithium ion battery according to claim 7, wherein, The tap density of the positive electrode material is 2.8 g / cm 3 to 3.8 g / cm 3 , and the tap density of the negative electrode material is 1.0 g / cm 3 to 1.8 / cm 3 ; and / or, the thickness of the electrode is from 10 μm to 150 μm.

9. The method for preparing a lithium-ion battery according to claim 1, wherein, The dropping amount of the electrolyte solution is 10 μL to 200 μL.

10. A lithium-ion battery is prepared by the preparation method of the lithium-ion battery composite electrolyte according to any one of claims 1-5, or by the preparation method of the lithium-ion battery according to any one of claims 6-9.

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