An all-solid-state lithium-ion battery and its application

Abstract

This invention proposes an all-solid-state lithium-ion battery and its application. The all-solid-state lithium-ion battery includes: a positive electrode; a modified lithium-based composite negative electrode, the modifying material including metal fluorides; and a solid electrolyte membrane disposed between the positive electrode and the modified lithium-based composite negative electrode, wherein the solid electrolyte membrane includes a sulfide electrolyte with the chemical formula Li. a P 1‑b M b S c O d X e , of which 5

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and particularly relates to a all-solid-state lithium-ion battery and its application. Background Art

[0002] With the continuous growth of the global demand for new energy vehicles, the requirements for the energy density, cycle life, safety, etc. of power batteries are becoming increasingly stringent. As a representative of the next-generation battery, solid-state batteries have become an important direction in the future energy storage field. Sulfide electrolytes for all-solid-state lithium-ion batteries have become a research hotspot in the energy storage field due to their ultra-high ionic conductivity and good processability. However, most sulfide electrolytes have problems such as poor air stability and poor compatibility with the lithium metal interface in practical applications, which limit the development of sulfide all-solid-state lithium-ion batteries. Summary of the Invention

[0003] The present invention provides a all-solid-state lithium-ion battery and its application. By using the all-solid-state lithium-ion battery and its application provided by the present invention, the conductivity stability of the sulfide electrolyte can be improved, the air stability can be enhanced, a stable negative electrode-solid electrolyte interface layer can be formed, which can block the direct contact between the sulfide electrolyte and the lithium metal negative electrode, make the current and lithium ion flux on the interface uniform, reduce the risk of lithium dendrite formation, and improve the energy density and cycle performance of the battery.

[0004] To solve the above technical problems, the present invention is realized by the following technical solutions.

[0005] The present invention provides a all-solid-state lithium-ion battery, which at least includes:

[0006] A positive electrode plate;

[0007] A modified lithium-based composite negative electrode, the modification raw material including a fluorine-containing compound; and

[0008] A solid electrolyte membrane, disposed between the positive electrode plate and the modified lithium-based composite negative electrode, the solid electrolyte membrane including a sulfide electrolyte, and the chemical formula of the sulfide electrolyte is Li a P 1-b M b S c O d X e , where 5 < a < 6, 0 < b < 1, 1.5 < c < 5, 0 < d < 2.5, 4 < c + d < 5, 1 < e < 2; M is selected from one or more of Al, Ga, In, Ti, Sc, As, Sb, Bi, V or Nb, and X is selected from one or more of Cl, Br or I.

[0009] In one embodiment of the present invention, M is selected from at least one of Sb, In or Bi, and X is selected from Cl.

[0010] In one embodiment of the present invention, the cation in the fluorine-containing compound is selected from Ag. + Al 3+ Zn 2+ Mg 2+ or Sn 2+ One or more of the following, wherein the anion in the fluorinated compound is selected from F - PF6 - FSI - TFSI - BF4 - PF2O2 - ODFB - or ODFP - One or more of them.

[0011] In one embodiment of the present invention, the cation is selected from Ag. + The anion is selected from PF2O2. - ODFB - or ODFP - At least one of them.

[0012] In one embodiment of the present invention, the modified lithium-based composite anode is obtained by the following method:

[0013] Lithium metal and a fluorine-containing compound were weighed into a stainless steel container according to the specified mass ratio, heated to a molten state, and allowed to react completely before cooling to room temperature to obtain a fluorine-modified lithium metal block; and

[0014] The modified lithium metal block containing fluorine compounds is placed on a roller press and repeatedly rolled to obtain the modified lithium-based composite anode.

[0015] In one embodiment of the present invention, the mass ratio of the fluorine-containing compound to the lithium metal is (10~60):100.

[0016] In one embodiment of the present invention, the heating and melting temperature is 200℃~300℃, and the reaction time is 0.5h~5h.

[0017] In one embodiment of the present invention, the thickness of the modified lithium-based composite anode is 10 μm to 100 μm, and the thickness of the solid electrolyte membrane is 30 μm to 100 μm.

[0018] In one embodiment of the present invention, the sulfide electrolyte has a particle size of 1 μm to 10 μm and an ionic conductivity greater than 3 mS / cm.

[0019] In one embodiment of the present invention, the solid electrolyte membrane includes a sulfide electrolyte and a binder, wherein the content of the sulfide electrolyte in the solid electrolyte membrane is 80wt%~99wt%; the binder is selected from one or more of polytetrafluoroethylene, polyvinylidene fluoride-based binders, silicone rubber, styrene-butadiene rubber, nitrile rubber or hydrogenated nitrile rubber.

[0020] The present invention also provides an electronic device comprising the all-solid-state lithium-ion battery described above.

[0021] In summary, this invention proposes an all-solid-state lithium-ion battery and its application, which can improve the stability of the conductivity of the sulfide electrolyte, enhance air stability, and improve the electrolyte / active material interface properties, thereby improving compatibility with active materials. The modified lithium-based composite anode forms LiF and alloy phases, with a high degree of overall alloy phase formation, which can accelerate lithium-ion transport and reduce side reactions between lithium metal and sulfide electrolyte at the interface, thus improving the performance of the all-solid-state lithium-ion battery. The modified lithium-based composite anode modified with fluorine compounds and the doped modified sulfide electrolyte are used in the all-solid-state lithium-ion battery to form a stable anode-solid electrolyte interface layer. This stable interface layer can prevent direct contact between the sulfide electrolyte and the lithium metal anode, and can also homogenize the current and lithium-ion flux at the interface, reducing the risk of lithium dendrite formation. Simultaneously, it can improve the battery's energy density and cycle performance. Detailed Implementation

[0022] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0023] It should be understood that the invention can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0024] The technical solution of the present invention will be further described in detail below with reference to several embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] This invention proposes an all-solid-state lithium-ion battery, which includes a positive electrode, a modified lithium-based composite negative electrode, and a solid electrolyte membrane. In this invention, the all-solid-state lithium-ion battery can be, for example, a primary battery or a secondary battery. A secondary battery can be, for example, a pouch battery, a hard-case battery, or a cylindrical battery. This invention does not impose specific limitations on the type or category of all-solid-state lithium-ion batteries.

[0026] In one embodiment of the present invention, the modifying raw material for the modified lithium-based composite anode includes, for example, a fluorinated compound, wherein the cation in the fluorinated compound is selected from Ag. + Al 3+ Zn 2+ Mg 2+ or Sn 2+ One or more of the metal ions that can undergo alloying reactions with lithium metal, and the anion in the fluorine-containing compound, for example, selected from F - PF6 - FSI - TFSI - BF4 - PF2O2 - ODFB - or ODFP - One or more of the following. In one embodiment of the invention, the cation is, for example, selected from Ag. + Anions, for example, are selected from PF2O2. - ODFB - or ODFP - At least one of the following can regulate the composition of the interface layer between the modified lithium-based composite anode and the solid electrolyte membrane, thereby improving the intrinsic ionic conductivity of the interface layer.

[0027] In one embodiment of the present invention, the modified lithium-based composite anode is obtained by the following method:

[0028] According to the mass ratio, metallic lithium and fluorine-containing compounds are weighed into a stainless steel container, heated to the molten state, and after the reaction is complete, cooled to room temperature to obtain fluorine-containing compound modified lithium metal blocks;

[0029] The modified lithium-based composite anode is obtained by repeatedly rolling a fluorine-containing compound-modified lithium metal block on a roller press.

[0030] In one embodiment of the present invention, the heating and melting temperature is 200℃~300℃, the reaction time is 0.5h~5h, or for example 0.5h~2h, and the heating is carried out under an inert atmosphere, such as one or two of argon or helium, to ensure sufficient reaction between the fluorinated compound and metallic lithium, while avoiding side reactions. The fluorinated compound reacts with metallic lithium in the molten state to form a lithium alloy phase with high ionic conductivity, which can rapidly convert lithium ions (Li...+ It is transported from the bulk to the solid electrolyte interface to compensate for lithium loss.

[0031] In one embodiment of the present invention, the mass ratio of the fluorinated compound to metallic lithium is (10~60):100, or for example (20~40):100, or for example 20:100, 30:100, 40:100, or 50:100. Controlling the content of the fluorinated compound allows for the formation of a stable interface layer between the modified lithium-based composite anode and the solid electrolyte membrane, and a higher degree of overall alloy phase in the modified lithium-based composite anode, which accelerates lithium-ion transport. However, when the content of the fluorinated compound is high, excessive LiF and alloy phase exist at the interface, and the excess LiF causes Li... + Diffusion kinetics across the interface deteriorate, and excessive alloy phase accelerates side reactions between lithium metal and sulfide electrolyte at the interface. When the content of fluorine-containing compounds is low, less lithium alloy phase is formed, resulting in little improvement in lithium-ion transport. Therefore, controlling the mass ratio of fluorine-containing compounds to metallic lithium can improve lithium-ion transport performance while reducing side reactions between lithium metal and sulfide electrolyte at the interface, thereby enhancing the performance of all-solid-state lithium-ion batteries.

[0032] In one embodiment of the present invention, the rolling time of the fluorine-containing compound modified lithium metal block on the roller press is 1h to 3h. By controlling the speed and roller torque of the roller press, the thickness of the obtained modified lithium-based composite anode is, for example, 10μm to 100μm, or, for example, 10μm to 80μm.

[0033] In one embodiment of the present invention, a solid electrolyte membrane is disposed between the positive electrode and the modified lithium-based composite negative electrode. The solid electrolyte membrane includes a sulfide electrolyte with the chemical formula Li. a P 1-b M b S c O d X e, where 5 < a < 6, 0 < b < 1, 1.5 < c < 5, 0 < d < 2.5, 4 < c + d < 5, 1 < e < 2, M is selected from one or more of Al, Ga, In, Ti, Sc, As, Sb, Bi, V, or Nb, etc., and X is selected from one or more of Cl, Br, or I, etc. Introducing M element and O element into the P site and O site of the sulfide electrolyte rich in halogen elements will form P-O and M-S bonds in the crystal structure, thereby enhancing the intrinsic resistance to atmospheric degradation and effectively reducing the generation of H2S, enhancing the air stability and chemical stability of the sulfide electrolyte. In addition, when using this sulfide electrolyte to assemble a all-solid-state lithium-ion battery, alloys such as LiCl, Li2O, LiF, and Li-M can be formed in the electrolyte / negative electrode interface layer, which can ensure good electron insulation performance and also ensure the rapid migration of ions on the interface, thereby improving the rate and cycle performance of the all-solid-state lithium-ion battery.

[0034] In an embodiment of the present invention, M is, for example, selected from at least one of Sb, In, or Bi. Due to the moderate ionic radii of Sb, In, or Bi, the ionic radii of these elements are close to those of the main elements in the sulfide electrolyte, such as sulfur and phosphorus. Therefore, during doping, they can more easily replace the positions of the main elements without causing excessive lattice distortion. And the electronegativity of Sb, In, or Bi is moderate, and they can form stable chemical bonds with the sulfur element in the sulfide, and are difficult to be damaged by external influences, so that the sulfide electrolyte has high stability and specific reactivity, can improve the stability of the conductivity of the sulfide electrolyte, enhance the air stability, and improve the electrolyte / active material interface properties, thereby improving the compatibility with the active material.

[0035] In an embodiment of the present invention, X is selected as a halogen element, and according to the different halogens, the degree of anion disorder between the 4a and 4c sites in the crystal structure of the sulfide electrolyte is different, from a small amount of anti-site defects with X being I to 60% site disorder with X being Cl, and the lithium ionic conductivity of these compounds mainly depends on the degree of disorder of anion and cation site occupancy. Therefore, X is, for example, also selected as Cl to improve the ionic conductivity and electrochemical stability of the sulfide electrolyte and improve the voltage stability. The value range of b is 0 < b ≤ 0.1. In a specific embodiment of the present invention, when M is +5 valence, b is preferably 0.04, and when M is +3 valence, b is preferably 0.02 to improve the cycle performance of the lithium-ion battery.

[0036] In one embodiment of the present invention, the sulfide electrolyte is obtained by the following preparation method: according to the chemical formula of the sulfide electrolyte, the Li source, P source, M source, S source and X source are mixed according to stoichiometry and then placed in a ball mill jar for ball milling to obtain sulfide electrolyte precursor powder; the sulfide electrolyte precursor powder is calcined at a preset temperature to obtain the sulfide electrolyte.

[0037] In one embodiment of the present invention, based on the chemical formula Li of the sulfide electrolyte... a P 1-b M b S c O d X e The Li source, P source, M source, S source, and X source are stoichiometrically mixed uniformly. The Li source is selected from one or more of LiCl, LiBr, LiI, or Li2S. The P source is selected from one or more of elemental P, P2S5, P4S6, PCl5, or PBr5. The M source is selected from one or more of oxides or sulfides of M. The S source is selected from one or more of elemental S, Li2S, P2S5, P4S6, As2S5, As2S3, Sb2S5, Sb2S3, Bi2S5, Bi2S3, Al2S3, Ga2S3, In2S3, or Sc2S3. The X source is selected from one or more of LiCl, PCl5, LiBr, PBr5, LiI, or I2. The O element in the chemical formula comes from the oxide of M. After the raw materials are mixed evenly, they are placed in a ball mill jar and ball milled under an inert atmosphere. The ball-to-material ratio is, for example, 1:1 to 100:1, the ball milling speed is, for example, 50 rpm to 1500 rpm, and the ball milling time is, for example, 1 h to 48 h, to obtain sulfide electrolyte precursor powder.

[0038] In one embodiment of the present invention, the sulfide electrolyte precursor powder is calcined at a preset temperature, wherein the preset temperature is 400℃~600℃ and the calcination time is 1h~18h, to obtain the sulfide electrolyte. In one embodiment of the present invention, the particle size of the sulfide electrolyte is, for example, 1μm~10μm, and the ionic conductivity is greater than 3mS / cm.

[0039] In one embodiment of the present invention, after obtaining the sulfide electrolyte, a solid electrolyte membrane is obtained, for example, by a dry method or a wet method. In this embodiment, the solid electrolyte membrane is obtained by a dry method, specifically by blending the sulfide electrolyte and a binder according to a mass ratio to obtain a mixed powder; the mixed powder is repeatedly rolled at a preset temperature for a preset time to obtain a solid electrolyte membrane. The sulfide electrolyte content in the solid electrolyte membrane is, for example, 80wt%~99wt%, and the binder is, for example, selected from one or more of polytetrafluoroethylene, polyvinylidene fluoride-based binders, silicone rubber, styrene-butadiene rubber, nitrile rubber, or hydrogenated nitrile rubber. The preset temperature is 60℃~100℃, the preset rolling time is 30min~120min, and the thickness of the obtained solid electrolyte membrane is, for example, 30μm~100μm.

[0040] In one embodiment of the present invention, a fluorinated compound-modified lithium-based composite anode and a doped sulfide electrolyte are used in a fully solid-state lithium-ion battery. The anions in the fluorinated compound generate LiF with low electronic conductivity at the interface, while the doped solid electrolyte film forms LiCl with high interfacial energy and Li2O with high ionic conductivity at the interface. LiF, Li2O, and LiCl together constitute a stable anode-solid electrolyte interface layer. This stable interface layer can prevent direct contact between the sulfide electrolyte and the lithium metal anode, while also allowing the current and Li at the interface to flow smoothly. + Flux homogenization reduces the risk of lithium dendrite formation.

[0041] In one embodiment of the present invention, the positive electrode sheet includes, for example, a positive current collector and a positive active layer disposed on at least one side of the positive current collector. The positive current collector is, for example, a foil formed by surface treatment of materials such as nickel, titanium, aluminum, silver, stainless steel, or carbon. Besides foil, the positive current collector can also be used in any one or more combinations of various forms such as film, mesh, porous, foam, or nonwoven fabric, and the thickness of the positive current collector is, for example, 8 μm to 15 μm.

[0042] In one embodiment of the present invention, the positive electrode active layer includes, for example, a positive electrode active material, a positive electrode electrolyte, a conductive agent, and a binder. The positive electrode active material is selected from layered positive electrode active materials, such as one or more combinations of lithium cobalt oxide (LCO), lithium nickel cobalt manganese oxide (NCM), or lithium nickel cobalt aluminum oxide (NCA). The positive electrode active material is selected from olivine-structured positive electrode active materials, such as one or more combinations of lithium iron phosphate (LFP) or lithium manganese iron phosphate (LFMP). The positive electrode active material is selected from spinel-structured positive electrode active materials, such as one or more combinations of lithium manganese oxide (LMO), lithium nickel manganese oxide (LNMO), or lithium-rich manganese (LMR).

[0043] In one embodiment of the present invention, the positive electrode active material is, for example, LiNbO3-coated LiNi. 0.9 Co 0.05 Mn 0.05 O2, wherein the thickness of the coating layer is, for example, 5 nm to 15 nm. In this embodiment, the positive electrode active material is obtained, for example, by a wet coating method. LiNbO3 coating can improve the discharge capacity and cycle stability of the all-solid-state lithium-ion battery, enhance the mechanical properties of the material, and extend the battery's lifespan.

[0044] In one embodiment of the present invention, the positive electrode electrolyte is, for example, the sulfide electrolyte described above. The conductive agent is selected from one or more combinations of conductive carbon black (Super P), vapor-grown carbon fiber (VGCF), Ketjen black, acetylene black, graphene, carbon nanotubes, porous carbon, etc., and the binder is selected from one or more combinations of polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polytetrafluoroethylene (PTFE), polyethylene oxide (PEO), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), nitrile butadiene rubber (NBR), hydrogenated nitrile butadiene rubber (HNBR), and polymerized styrene butadiene rubber (SBR), etc.

[0045] In one embodiment of the present invention, the positive electrode active material is, for example, LiNbO3-coated LiNi. 0.9 Co 0.05 Mn 0.05O2, positive electrode electrolyte (e.g., the aforementioned sulfide electrolyte), conductive agent (e.g., Super P and VGCF, with a mass ratio of Super P to VGCF of 1:1), and binder (e.g., HNBR). The positive electrode active material, positive electrode electrolyte, conductive agent, and binder are dispersed in a low-polarity solvent such as xylene at a mass ratio of 70:25:2:3, and the amount of xylene added is adjusted to control the solid content of the slurry to approximately 55%. The slurry is coated onto aluminum foil using a blade coating method. The coated aluminum foil is then dried in a forced-air drying process at 90°C to 110°C for 2 to 3 hours, followed by roller pressing at 60°C and a pressure of 95 MPa to obtain a positive electrode sheet with a positive electrode active layer thickness of, for example, 80 μm to 120 μm. This invention does not limit the mass ratio of the positive electrode active material, positive electrode electrolyte, positive electrode conductive agent, and positive electrode binder; these ratios can be selected according to actual needs.

[0046] In one embodiment of the present invention, the above-mentioned positive electrode, solid electrolyte membrane, and modified lithium-based composite negative electrode are placed sequentially, with the solid electrolyte membrane positioned between the positive electrode and the modified lithium-based composite negative electrode to act as an separator, and the layers are stacked to form a bare cell. The bare cell is then placed in a casing and sealed, such as an aluminum-plastic bag, followed by standing, formation, and capacity testing processes to obtain the finished soft-pack all-solid-state lithium-ion battery. The assembly process of the all-solid-state lithium-ion battery is completed in a glove box with an inert atmosphere.

[0047] The present invention will be explained in more detail below by referring to embodiments, which should not be construed as limiting. Appropriate modifications can be made within the scope of the present invention, and all such modifications fall within the technical scope of the present invention.

[0048] Example 1

[0049] Preparation of modified lithium-based composite anode: In an argon-atmosphere glove box, silver hexafluorophosphate and metallic lithium were mixed in a stainless steel container at a mass ratio of 20:100 and heated at 300°C for 1 hour to obtain a molten liquid. The molten liquid was then cooled to room temperature to obtain a fluorinated compound modified lithium metal block. The fluorinated compound modified lithium metal block was repeatedly rolled at room temperature until the thickness was 30µm to obtain the modified lithium-based composite anode.

[0050] Preparation of solid electrolyte membrane: Li 5.54 P 0.98 In 0.02 S 4.4 O 0.1 Cl 1.5 The PTFE binder was ground at a mass ratio of 99:1 for 5 minutes, and then rolled at 80°C, gradually reducing the gap between the rolls until it reached 40µm. The rolls were repeatedly rolled at this gap for 60 minutes to obtain a solid electrolyte membrane with a thickness of 40µm.

[0051] Preparation of positive electrode: LiNi coated with positive electrode active material LiNbO3 0.9 Co 0.05 Mn 0.05 O2, with a coating layer thickness of 10 nm. The positive electrode electrolyte is, for example, the aforementioned sulfide electrolyte, and the conductive agents include Super P and VGCF, with a mass ratio of Super P to VGCF of 1:1. The binder is HNBR. In an environment with a dew point of 30°C, the positive electrode active material, positive electrode electrolyte, conductive agent, and binder are dispersed in xylene, for example, at a mass ratio of 70:25:2:3, and the amount of xylene added is adjusted to control the solid content of the slurry to 55%. The slurry is coated onto aluminum foil using a blade coating method, and the coated aluminum foil is dried in a forced-air dryer at 100°C for 2 hours, followed by roller pressing at 60°C and a pressure of 95 MPa to obtain a positive electrode sheet, wherein the thickness of the positive electrode active layer is, for example, 100 μm.

[0052] Assembly of all-solid-state lithium-ion batteries: The prepared positive electrode, solid electrolyte membrane, and modified lithium-based composite negative electrode are stacked sequentially, with the solid electrolyte membrane positioned between the positive electrode and the modified lithium-based composite negative electrode to act as a separator. The stacked cells are then assembled into bare cells. The bare cells are placed in aluminum-plastic bags, followed by standing, formation, and capacity testing processes to obtain the finished soft-pack all-solid-state lithium-ion battery.

[0053] Example 2

[0054] The sulfide electrolyte in the solid electrolyte membrane and positive electrode is replaced with Li 5.54 P 0.98 Bi 0.02 S 4.47 O 0.03 Cl 1.5 Other operations remain the same as in Example 1.

[0055] Example 3

[0056] The sulfide electrolyte in the solid electrolyte membrane and positive electrode is replaced with Li 5.5 P 0.96 Sb 0.04 S 4.4 O 0.1 Cl 1.5 Other operations remain the same as in Example 1.

[0057] Example 4

[0058] The sulfide electrolyte in the solid electrolyte membrane and positive electrode is replaced with Li 5.54 P 0.98 Al 0.02 S 4.4 O 0.1 Cl 1.5Other operations remain the same as in Example 1.

[0059] Example 5

[0060] The sulfide electrolyte in the solid electrolyte membrane and positive electrode is replaced with Li 5.54 P 0.98 Ti 0.02 S 4.4 O 0.1 Cl 1.5 Other operations remain the same as in Example 1.

[0061] Example 6

[0062] The sulfide electrolyte in the solid electrolyte membrane and positive electrode is replaced with Li 5.54 P 0.99 Bi 0.01 S 4.485 O 0.015 Cl 1.5 Other operations remain the same as in Example 1.

[0063] Example 7

[0064] The sulfide electrolyte in the solid electrolyte membrane and positive electrode is replaced with Li 5.62 P 0.94 Bi 0.06 S 4.1 O 0.09 Cl 1.5 Other operations remain the same as in Example 1.

[0065] Example 8

[0066] The sulfide electrolyte in the solid electrolyte membrane and positive electrode is replaced with Li 5.5 PS 4.5 Cl 1.5 Other operations remain the same as in Example 1.

[0067] Example 9

[0068] In preparing the modified lithium-based composite anode, the mass ratio of silver hexafluorophosphate to metallic lithium was 10:100, and other operations were consistent with those in Example 1.

[0069] Example 10

[0070] In preparing the modified lithium-based composite anode, the mass ratio of silver hexafluorophosphate to metallic lithium was 60:100, and other operations were consistent with those in Example 1.

[0071] Example 11

[0072] In preparing the modified lithium-based composite anode, the mass ratio of silver hexafluorophosphate to metallic lithium was 100:100, and other operations were consistent with those in Example 1.

[0073] Example 12

[0074] In preparing the modified lithium-based composite anode, silver hexafluorophosphate was replaced with silver fluoride, and other operations were consistent with those in Example 1.

[0075] Example 13

[0076] In preparing the modified lithium-based composite anode, silver hexafluorophosphate was replaced with silver bis(fluorosulfonyl)imide, and other operations were consistent with those in Example 1.

[0077] Example 14

[0078] In preparing the modified lithium-based composite anode, silver hexafluorophosphate was replaced with silver tetrafluoroborate, and other operations were consistent with those in Example 1.

[0079] Example 15

[0080] In preparing the modified lithium-based composite anode, silver hexafluorophosphate was replaced with silver difluorooxalate borate, and other operations were consistent with those in Example 1.

[0081] Example 16

[0082] In the preparation of the modified lithium-based composite anode, silver hexafluorophosphate was replaced with zinc difluoride, and other operations were consistent with those in Example 1.

[0083] Example 17

[0084] In the preparation of the modified lithium-based composite anode, silver hexafluorophosphate was replaced with tin difluoride, and other operations were consistent with those in Example 1.

[0085] Example 18

[0086] In the preparation of the modified lithium-based composite anode, silver hexafluorophosphate was replaced with magnesium difluoride, and other operations were consistent with those in Example 1.

[0087] Comparative Example 1

[0088] In preparing the modified lithium-based composite anode, the mass ratio of silver hexafluorophosphate to lithium metal was 0:100, i.e., the anode was lithium metal, and other operations were consistent with those in Example 1.

[0089] Comparative Example 2

[0090] In preparing the modified lithium-based composite anode, the mass ratio of silver hexafluorophosphate to lithium metal was 0:100, i.e., the anode was lithium metal, and other operations were consistent with those in Example 8.

[0091] Comparative Example 3

[0092] In the preparation of the modified lithium-based composite anode, silver hexafluorophosphate was replaced with iron fluoride, and other operations were consistent with those in Example 1.

[0093] Comparative Example 4

[0094] The sulfide electrolyte in the solid electrolyte membrane and positive electrode is replaced with Li 5.54 P 0.98 In 0.02 S5Cl 1.5 Other operations remain the same as in Example 1.

[0095] Comparative Example 5

[0096] The sulfide electrolyte in the solid electrolyte membrane and positive electrode is replaced with Li 5.5 PS 4.4 O 0.1 Cl 1.5 Other operations remain the same as in Example 1.

[0097] Comparative Example 6

[0098] The sulfide electrolyte in the solid electrolyte membrane and positive electrode was replaced with Li-coated with a 15nm thick ZrO2 layer. 5.5 PS 4.5 Cl 1.5 Other operations remain the same as in Example 1.

[0099] In this invention, all-solid-state lithium-ion batteries were prepared using different sulfide electrolytes and modified lithium-based composite anodes in Examples 1-18 and Comparative Examples 1-6. Some characteristics of the sulfide electrolytes and modified lithium-based composite anodes are shown in Table 1. The all-solid-state lithium-ion batteries obtained in Examples 1-18 and Comparative Examples 1-6 were tested, and the test results are shown in Table 1.

[0100] In one embodiment of the present invention, the modified lithium-based composite anodes obtained in Examples 1-18 and Comparative Examples 1-6 were used to assemble a symmetrical battery in the following order: modified lithium-based composite anode, solid electrolyte membrane, and modified lithium-based composite anode. The solid electrolyte membrane was positioned between the two modified lithium-based composite anodes to act as an separator. The limiting current density (CCD) of the symmetrical battery was then measured. Specifically, a current of 0.1 mA / cm² was applied to the assembled symmetrical battery. 2 Lithium deposition and stripping tests were performed at a current density of 0.1 mA / cm² for 1 hour, followed by subsequent current density measurements. 2 The increase gradually increases, and the test is stopped when the symmetrical battery is short-circuited. The current density at this time is recorded.

[0101] In one embodiment of the present invention, the capacity retention test of the all-solid-state lithium-ion battery at 0.5C / 0.5C room temperature cycling is conducted at 25°C. The prepared all-solid-state lithium-ion battery is charged and discharged at a low rate of 0.1C / 0.1C for two cycles, with a test voltage range of 2.5~4.2V. Subsequently, charge and discharge cycles are performed at a rate of 0.5C / 0.5C, and the discharge capacity of the first cycle at 0.5C is recorded. When the discharge capacity reaches 80% (80% SOH) of the discharge capacity of the first cycle at 0.5C, the test is stopped, and the number of cycles at room temperature is recorded. The capacity retention rate is calculated as follows: Capacity retention rate (%) = (Discharge capacity / Discharge capacity of the first cycle) × 100%.

[0102] Table 1. Battery performance test results in Examples 1-18 and Comparative Examples 1-6

[0103]

[0104] Please refer to Table 1. Comparing Examples 1-18 and Comparative Examples 1-6, it can be seen that the combination of doped modified sulfide electrolyte and fluorinated compound modified lithium-based composite anode can effectively alleviate the interfacial side reactions between sulfide electrolyte and lithium metal, regulate the migration and deposition / stripping behavior of lithium ions at the anode, suppress the formation of lithium dendrites at high current rates, and thus improve the first efficiency and cycle performance of all-solid-state lithium-ion batteries.

[0105] Please refer to Table 1. Comparing Examples 1 and 8 with Comparative Examples 1 and 6, it can be seen that, compared to modifying the sulfide electrolyte alone or modifying the lithium metal anode alone, the present invention can significantly improve the cycle and rate performance of all-solid-state lithium-ion batteries. When the sulfide electrolyte is coated and modified and used in combination with a fluorine-containing modified lithium-based composite anode, the battery performance is weaker than that of the doped sulfide electrolyte provided in this application. This is because when the doped sulfide electrolyte and the fluorine-containing modified lithium-based composite anode are used in combination, the fluorine compound reacts with metallic lithium to generate a lithium alloy phase with high ionic conductivity and LiF with low electronic conductivity. The lithium alloy can quickly convert Li... + From the bulk electrolyte to the solid electrolyte interface to compensate for lithium loss, LiF can facilitate the current and Li at the interface. + Flux homogenization. Simultaneously, the doped and modified sulfide electrolyte forms high interfacial energy LiCl and high ionic conductivity Li₂O at the interface. LiF, Li₂O, and LiCl together constitute a stable negative electrode-solid electrolyte interface layer. This stable interface layer can prevent direct contact between the sulfide electrolyte and the lithium metal negative electrode, while also allowing the current and Li₂O at the interface to be homogenized. + Flux uniformity is achieved to prevent lithium dendrite formation from piercing the electrolyte membrane and causing a short circuit in the battery.

[0106] Please refer to Table 1. Comparing Examples 1-7, it can be seen that different elements and their contents doping the sulfide electrolyte have a significant impact on the limiting current density of the symmetric battery. Among them, the limiting current density of the symmetric battery doped with indium, bismuth, and antimony is better than that doped with aluminum and titanium, and the corresponding all-solid-state lithium-ion battery also has better cycle performance. Comparing Example 1 and Comparative Examples 4-5, it can be seen that when P-sites and O-sites are doped individually, the limiting current density of the symmetric battery is lower, and the battery cycle performance is worse. Therefore, when P-sites and O-sites are doped together, the limiting current density of the symmetric battery is better than that of single-site element doping, and the corresponding battery cycle life is also longer.

[0107] Please refer to Table 1. Comparing Examples 1, 9-11, it can be seen that as the proportion of fluorinated compounds and metallic lithium increases, the limiting current density and cycle number of the symmetric battery first increase and then decrease. This is because when the content of fluorinated compounds is high, there are excessive LiF and alloy phases at the interface. Excessive LiF causes Li... + Diffusion kinetics across the interface deteriorate, and excessive alloy phase accelerates side reactions between interfacial lithium metal and sulfide electrolytes. When the content of fluorine compounds is low, lithium metal dominates the bulk phase, while LiF is present in some areas of the interfacial layer, making it difficult to prevent the formation of lithium dendrites.

[0108] Please refer to Table 1. Comparative Examples 1 and 12-15 show that for different anions, when the anion contains atoms other than fluorine, substances such as Li3P, Li3B, or Li3N may appear in the interface layer to jointly regulate the transport of interfacial ions, resulting in a slight improvement in the cycle life of the corresponding battery. Comparative Examples 12, 16-18 and Comparative Example 3 show that different cations of fluoride have different effects on improving the limiting current density of symmetrical batteries and the number of cycles in all-solid-state lithium-ion batteries. This is because the lithium-ion conductivity of the alloys formed by the binding energies of different cations and lithium metal varies, leading to differences in the performance of all-solid-state lithium-ion batteries.

[0109] This invention also provides an electronic device comprising at least one of the aforementioned all-solid-state lithium-ion batteries, which provides electrical energy. The electronic device can be a vehicle, mobile phone, portable device, laptop, ship, spacecraft, electric toy, or power tool, etc. In one embodiment of this invention, the vehicle is, for example, a new energy vehicle, which can be a pure electric vehicle, a hybrid electric vehicle, or a range-extended electric vehicle, etc. The spacecraft includes airplanes, rockets, space shuttles, and spacecraft, etc. The electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. The power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. Since the electronic device includes the aforementioned all-solid-state lithium-ion battery, the advantages of including the aforementioned all-solid-state lithium-ion battery will not be elaborated further here.

[0110] In summary, this invention proposes an all-solid-state lithium-ion battery and its application, which can improve the stability of the conductivity of the sulfide electrolyte, enhance air stability, and improve the electrolyte / active material interface properties, thereby improving compatibility with active materials. The modified lithium-based composite anode forms LiF and alloy phases, with a high degree of overall alloy phase formation, which can accelerate lithium-ion transport and reduce side reactions between lithium metal and sulfide electrolyte at the interface, thus improving the performance of the all-solid-state lithium-ion battery. The modified lithium-based composite anode modified with fluorine compounds and the doped modified sulfide electrolyte are used in the all-solid-state lithium-ion battery to form a stable anode-solid electrolyte interface layer. This stable interface layer can prevent direct contact between the sulfide electrolyte and the lithium metal anode, and can also homogenize the current and lithium-ion flux at the interface, reducing the risk of lithium dendrite formation. Simultaneously, it can improve the battery's energy density and cycle performance.

[0111] The above description is merely a preferred embodiment of this application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept. For example, technical solutions formed by replacing the above-mentioned features with technical features with similar functions disclosed in this application (but not limited to) each other.

[0112] Apart from the technical features described in the specification, the other technical features are known to those skilled in the art. To highlight the innovative features of this invention, the other technical features will not be described in detail here.

Claims

1. A fully solid-state lithium-ion battery, characterized in that, include: Positive electrode sheet; A modified lithium-based composite anode, wherein the raw materials for the modified lithium-based composite anode include metallic lithium and a fluorine-containing compound, wherein the mass ratio of the fluorine-containing compound to the metallic lithium is (10~60):100; and the cation in the fluorine-containing compound is selected from Ag. + Al 3 + Zn 2+ Mg 2+ or Sn 2+ One or more of the following, wherein the anion in the fluorinated compound is selected from PF6. - FSI - TFSI - BF4 - PF2O2 - ODFB - or ODFP - One or more of the following; and A solid electrolyte membrane is disposed between the positive electrode sheet and the modified lithium-based composite negative electrode. The solid electrolyte membrane includes a sulfide electrolyte, and the chemical formula of the sulfide electrolyte is Li a P 1-b M b S c O d X e , where 5 < a < 6, 0 < b < 1, 1.5 < c < 5, 0 < d < 2.5, 4 < c + d < 5, 1 < e < 2; M is selected from one or more of Al, Ga, In, Ti, Sc, As, Sb, Bi, V or Nb, and X is selected from one or more of Cl, Br or I; The modified lithium-based composite anode is obtained by the following method: Lithium metal and a fluorine-containing compound were weighed into a stainless steel container according to the specified mass ratio, heated to a molten state, and allowed to react completely before cooling to room temperature to obtain a fluorine-modified lithium metal block; and The modified lithium metal block containing fluorine compounds is placed on a roller press and repeatedly rolled to obtain the modified lithium-based composite anode.

2. The all-solid-state lithium-ion battery according to claim 1, characterized in that, M is selected from at least one of Sb, In or Bi, and X is selected from Cl.

3. The all-solid-state lithium-ion battery according to claim 1, characterized in that, The cation is selected from Ag. + The anion is selected from PF2O2. - ODFB - or ODFP - At least one of them.

4. The all-solid-state lithium-ion battery according to claim 1, characterized in that, The heating and melting temperature is 200℃~300℃, and the reaction time is 0.5h~5h.

5. The all-solid-state lithium-ion battery according to claim 1, characterized in that, The thickness of the modified lithium-based composite anode is 10μm~100μm, and the thickness of the solid electrolyte membrane is 30μm~100μm.

6. The all-solid-state lithium-ion battery according to claim 1, characterized in that, The sulfide electrolyte has a particle size of 1 μm to 10 μm and an ionic conductivity greater than 3 mS / cm.

7. The all-solid-state lithium-ion battery according to claim 1, characterized in that, The solid electrolyte membrane comprises a sulfide electrolyte and a binder, wherein the content of the sulfide electrolyte in the solid electrolyte membrane is 80wt%~99wt%; the binder is selected from one or more of polytetrafluoroethylene, polyvinylidene fluoride binders, silicone rubber, styrene-butadiene rubber, nitrile rubber or hydrogenated nitrile rubber.

8. An electronic device, characterized in that, Includes the all-solid-state lithium-ion battery as described in any one of claims 1-7.

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