A coaxial flexible solid-state battery structure and its preparation method

Abstract

The present invention discloses a coaxial flexible solid-state battery structure, which includes a fibrous positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, a negative electrode current collector and an outer skin layer in the coaxial direction from the inside to the outside; the preparation method of the present invention is: 1. Preparation of positive electrode slurry; 2. Preparation of fibrous positive flexible electrode; 3. Construction of solid electrolyte layer; 4. Construction of negative electrode current collector; 5. Preparation of negative electrode slurry; 6. Preparation of negative electrode active material layer; 7. Shell packaging. The coaxial stacked structure in the battery structure of the present invention forms a gel-state composite electrolyte layer after activation, achieving good interface contact between each layer, and obtaining a high-performance coaxial flexible solid-state battery structure; the coating equipment of the present invention achieves uniform coating of each slurry, and maintains good interface contact between each layer, thereby improving the safety performance of the battery. The battery has multi-dimensional deformation adaptability and is suitable for the field of flexible wearable devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery manufacturing, and in particular relates to a coaxial flexible solid-state battery structure and a preparation method thereof. Background Art

[0002] Portable electronic products are increasingly becoming more flexible, lightweight, and miniaturized. Flexible wearable electronic devices hold broad application prospects in fields such as communications, healthcare, and smart clothing. Batteries, as their core components, are gaining increasing attention, and the development of high-energy-density flexible lithium-ion batteries has become a research hotspot.

[0003] Currently, research on flexible batteries focuses on planar batteries, but this type of flexible battery does not have the adaptability to multi-dimensional deformations such as bending, kinking, and buckling, which limits its application scenarios. One-dimensional fiber battery electrode materials have the characteristics of high flexibility, stable multi-curvature performance, and a wide range of applications. However, the current fiber batteries that use woven positive and negative electrodes have problems such as small positive and negative electrode contact area, low active material utilization, easy detachment of active coatings, and safety hazards of liquid electrolytes. Therefore, the preparation of high-performance flexible fiber batteries has attracted great attention from researchers. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and provide a coaxial flexible solid-state battery structure. In the coaxial flexible solid-state battery structure, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer are in a coaxial stacked structure, which forms a gel composite electrolyte layer after activation, thereby achieving good interface contact between the solid electrolyte layer and the positive and negative electrode active material coatings, improving interface stability, and reducing solid-solid poor contact. At the same time, the structure greatly increases the contact area between the positive and negative electrodes, improves the utilization rate of the positive and negative electrode active materials, and thus improves the energy density of the flexible solid-state battery, thereby obtaining a high-performance coaxial flexible solid-state battery structure.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a coaxial flexible solid-state battery structure, characterized in that it includes a fibrous positive electrode collector, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, a negative electrode collector and an outer skin layer from the inside to the outside along the coaxial direction.

[0006] In the coaxial flexible solid-state battery structure of the present invention, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer are distributed layer by layer from the inside to the outside along the coaxial direction between the fibrous positive electrode current collector and the negative electrode current collector, presenting a coaxial stacked structure. After activation, a gel composite electrolyte layer is formed, which realizes good interface contact between the solid electrolyte layer and the positive and negative electrode active material coatings, improves the interface stability, and reduces solid-solid poor contact; at the same time, this structure greatly increases the contact area between the positive and negative electrodes, improves the utilization rate of the positive and negative electrode active materials, and thereby improves the energy density of the flexible solid-state battery.

[0007] In addition, the present invention also discloses a method for preparing the above-mentioned coaxial flexible solid-state battery structure, characterized in that the method comprises the following steps:

[0008] Step 1: Preparation of positive electrode slurry: Add positive electrode material, conductive agent, binder, and inorganic solid electrolyte solid material into N-methylpyrrolidone solvent and stir thoroughly until stable to obtain positive electrode slurry;

[0009] Step 2, preparation of a fibrous positive flexible electrode: placing the positive electrode slurry obtained in step 1 as a working slurry in the funnel-shaped trough of the coating equipment, winding the fibrous positive electrode current collector on the pay-off device, and one end passes through the positive electrode slurry and is led out from the bottom discharge port of the funnel-shaped trough, pulling the fibrous positive electrode current collector so that the positive electrode slurry is evenly coated on the surface of the fibrous positive electrode current collector, and then baking it in a heating device to obtain a fibrous positive flexible electrode, which is then sent out and wound in a take-up device;

[0010] Step 3, construction of the solid electrolyte layer: add polyvinylidene fluoride-hexafluoropropylene to the organic solvent and stir continuously until it is fully dissolved to form a stable glue, then add nanoscale to submicron inorganic solid electrolyte and continue stirring to obtain a uniformly dispersed composite electrolyte slurry, and then place the composite electrolyte slurry as the working slurry in the funnel-shaped trough of the coating equipment, and wind the fibrous positive flexible electrode obtained in step 2 on the pay-off device, and one end passes through the composite electrolyte slurry and is led out from the bottom discharge port of the funnel-shaped trough, pulling the fibrous positive flexible electrode so that the composite electrolyte slurry is evenly coated on the surface of the fibrous positive flexible electrode, and then heated by a heating device to volatilize the solvent to obtain a flexible electrode with a solid electrolyte layer on the surface, and sent out to be wound in the take-up device;

[0011] Alternatively, the solid electrolyte membrane is adhered to the surface of the fibrous positive flexible electrode obtained in step 2 using a glue solution to obtain a flexible electrode having a solid electrolyte layer on the surface;

[0012] Step 4: Construction of the negative electrode current collector: Using a metal wire as the negative electrode current collector, uniformly winding it around the surface of the flexible electrode having the solid electrolyte layer obtained in step 3, and maintaining a distance between adjacent windings of the negative electrode current collector to obtain a coaxial fiber-shaped flexible battery structure;

[0013] Step 5: Preparation of negative electrode slurry: Add the negative electrode material, conductive agent, binder, and inorganic solid electrolyte solid material into N-methylpyrrolidone solvent and stir thoroughly until stable to obtain negative electrode slurry;

[0014] Step 6. Preparation of the negative electrode active material layer: The negative electrode slurry obtained in step 5 is placed as the working slurry in the funnel-shaped trough of the coating equipment, and the coaxial fibrous flexible battery structure obtained in step 4 is wound on the pay-off device, and one end passes through the negative electrode slurry and is led out from the bottom discharge port of the funnel-shaped trough, and the coaxial fibrous flexible battery structure is pulled so that the negative electrode slurry is evenly coated on the surface of the coaxial fibrous flexible battery structure, and then baked by a heating device to obtain a coaxial fibrous flexible battery core, which is then sent out and wound in the take-up device;

[0015] Step 7. Shell packaging: Place the coaxial fibrous flexible battery core obtained in step 6 in a polyolefin heat shrink tube, add liquid electrolyte to the polyolefin heat shrink tube and let it stand for activation, then allow the polyolefin heat shrink tube to shrink due to heat and tightly wrap around the surface of the coaxial fibrous flexible battery core. After sealing the two ends, a coaxial flexible solid-state battery structure is obtained.

[0016] The above method is characterized in that the positive electrode material in step one is at least one of lithium cobalt oxide, ternary material, lithium manganate, lithium iron phosphate and lithium-rich manganese-based material, the conductive agent is at least one of carbon black, activated carbon, carbon fiber and carbon nanotubes, the adhesive is polyvinylidene fluoride, and the inorganic solid electrolyte is at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide and lithium lanthanum titanium oxide, and the mass content of the positive electrode material in the solid material is 79% to 97%, the mass content of the conductive agent is 1% to 10%, the mass content of the binder is 1% to 10%, and the mass content of the inorganic solid electrolyte is 1% to 10%.

[0017] The above method is characterized in that the fibrous positive electrode current collector in step 2 is aluminum wire, stainless steel wire or nickel wire with a diameter of 0.1 mm to 2 mm.

[0018] The above method is characterized in that the organic solvent in step 3 is acetone, N-methylpyrrolidone, or N,N-dimethylformamide, the mass concentration of the glue is 5% to 20%, the inorganic solid electrolyte is at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide, and lithium lanthanum titanium oxide, and the mass content of the inorganic solid electrolyte in the composite electrolyte slurry is 10% to 30%. The present invention effectively regulates the adhesion of the composite electrolyte slurry by controlling the composition of the composite electrolyte slurry, which is beneficial to the combination of the solid electrolyte layer and the flexible positive electrode. The combination of organic and inorganic substances improves flexibility and optimizes ionic conductivity.

[0019] The above method is characterized in that the solid electrolyte membrane in step 3 is a polyethylene or polypropylene-based membrane coated with a lithium aluminum titanium phosphate or lithium lanthanum zirconium oxide solid electrolyte. The present invention uses a solid electrolyte membrane as the solid electrolyte layer, which has better flexibility and helps improve battery flexibility.

[0020] The above method is characterized in that the negative electrode current collector in step 4 is a copper wire, stainless steel wire or nickel wire with a diameter of 0.05 mm to 1 mm.

[0021] The above method is characterized in that the negative electrode material in step five is at least one of graphite, soft carbon and hard carbon, the conductive agent is at least one of carbon black, activated carbon, carbon fiber and carbon nanotubes, the adhesive is polyvinylidene fluoride, and the inorganic solid electrolyte is at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide and lithium lanthanum titanium oxide, and the mass content of the negative electrode material in the solid material is 79% to 97%, the mass content of the conductive agent is 1% to 10%, the mass content of the binder is 1% to 10%, and the mass content of the inorganic solid electrolyte is 1% to 10%.

[0022] The above method is characterized in that the liquid electrolyte in step seven is a carbonate electrolyte, which is composed of a lithium salt and an ester solvent, and the lithium salt is lithium hexafluorophosphate, and the ester solvent is at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate and ethyl methyl carbonate.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. In the coaxial flexible solid-state battery structure of the present invention, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer are in a coaxial stacked structure, and a gel composite electrolyte layer is formed after activation, thereby achieving good interface contact between the solid electrolyte layer and the positive and negative electrode active material coatings, improving the interface stability, and reducing solid-solid poor contact; at the same time, this structure greatly increases the contact area of the positive and negative electrodes, improves the utilization rate of the positive and negative electrode active materials, and thereby improves the energy density of the flexible solid-state battery, obtaining a high-performance coaxial flexible solid-state battery structure.

[0025] 2. In the coaxial flexible solid-state battery structure of the present invention, a solid electrolyte layer is arranged between the positive electrode active material layer and the negative electrode active material layer to isolate electrons and conduct ions, effectively replacing traditional liquid electrolytes, greatly reducing the risks of leakage, combustion, etc. that may occur in the battery, and enhancing its safety performance.

[0026] 3. The coaxial flexible solid-state battery structure of the present invention is bendable, can be bent and deformed in multiple directions, and has multi-dimensional deformation adaptability. It has broad application prospects in the field of flexible wearable devices.

[0027] 4. The present invention adopts a coating device to sequentially coat the surface of the fibrous positive electrode collector with positive electrode slurry and dry it to form a positive electrode active material layer, coat the composite electrolyte slurry or adhere the solid electrolyte membrane to form a solid electrolyte layer, wind the negative electrode collector, coat the negative electrode slurry and dry it to form a negative electrode active material layer. By controlling the composition of each slurry and thus controlling the solid content and viscosity index, it has excellent coating performance. Combined with controlling the bottom discharge port diameter of the funnel-shaped trough of the coating equipment to match the diameter of each coating object, and controlling the pulling rate of each, uniform coating of each slurry is achieved, thereby obtaining a coaxial flexible solid-state battery structure, and maintaining good interface contact between the layers, which solves the problems of small positive and negative electrode contact area, low active material utilization, easy shedding of active coating, and safety hazards of liquid electrolyte in the current fiber battery using positive and negative electrode winding and weaving.

[0028] 5. In the packaging process of the flexible inner core structure, the present invention adopts a polyolefin heat shrink tube with low heat shrinkage temperature, fast shrinkage and stable performance. After heating, it is tightly wrapped around the surface of the inner core, which produces a certain pressure on the inner core, helps to reduce the contact internal resistance and improve the cycle stability of the flexible solid-state battery.

[0029] 6. The preparation method of the present invention is simple and the preparation process is easy to control. Through the research and optimization of the electrode preparation process, slurry coating process, and battery assembly process, a new method for preparing a flexible solid-state battery structure has been developed.

[0030] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the coaxial flexible solid-state battery structure of the present invention.

[0032] Figure 2 This is a schematic structural diagram of the coating equipment used in the present invention.

[0033] Figure 3 This is a flow chart of the preparation process of the coaxial flexible solid-state battery structure of the present invention.

[0034] Figure 4 This is a physical picture of the coaxial fiber-shaped flexible battery structure prepared in Example 1 of the present invention.

[0035] Figure 5 This is a physical picture of the coaxial flexible solid-state battery structure in Example 2 of the present invention.

[0036] Description of Reference Numerals

[0037] 1—Fiber-shaped positive electrode current collector; 2—Positive electrode active material layer; 3—Solid electrolyte layer;

[0038] 4—negative electrode active material layer; 5—negative electrode current collector; 6—outer skin layer;

[0039] 7—Paying-off device; 8—Funnel-shaped trough; 9—Working slurry;

[0040] 10—Heating device; 11—Wire taking-up device. DETAILED DESCRIPTION

[0041] Example 1

[0042] like Figure 1 As shown, the coaxial flexible solid-state battery structure of this embodiment is characterized in that it includes a fibrous positive electrode current collector 1, a positive electrode active material layer 2, a solid electrolyte layer 3, a negative electrode active material layer 4, a negative electrode current collector 5 and an outer skin layer 6 in sequence along the coaxial direction from the inside to the outside.

[0043] like Figure 3 As shown, the method for preparing the coaxial flexible solid-state battery structure of this embodiment includes the following steps:

[0044] Step 1, preparation of positive electrode slurry: add positive electrode material lithium cobalt oxide (LiCoO2), conductive agent conductive carbon black (Super-P), binder polyvinylidene fluoride (PVDF), lithium aluminum titanium phosphate (LATP) solid electrolyte solid materials according to a mass ratio of 91:2:3:4 to N-methylpyrrolidone (NMP) solvent and stir thoroughly until stable to obtain a positive electrode slurry with a viscosity of 9000Pa·s to 11000Pa·s;

[0045] Step 2: Preparation of fibrous positive flexible electrode: The positive electrode slurry obtained in step 1 is used as working slurry 9 and placed in Figure 2 In the funnel-shaped trough 8 of the coating equipment shown, a fibrous positive electrode current collector, i.e., an aluminum wire with a diameter of 0.4 mm, is wound on a pay-off device 7, and one end passes through the positive electrode slurry and is drawn out from the bottom discharge port of the funnel-shaped trough 8. The fibrous positive electrode current collector is pulled at a rate of 1 m / min to 4 m / min so that the positive electrode slurry is evenly coated on the surface of the aluminum wire. The fibrous positive electrode current collector is then baked at 90°C to 110°C by a heating device 10 to obtain a fibrous positive flexible electrode, which is then sent out and wound in a take-up device 11.

[0046] Step 3, the construction of the solid electrolyte layer: polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) was added to N, N-dimethylformamide (DMF) and stirred continuously for 4 hours until it was fully dissolved to form a stable gel solution with a mass concentration of 20%, and then lithium aluminum titanium phosphate (LATP) inorganic solid electrolyte with a particle size of 0.6 μm was added and stirred continuously for 2 hours to obtain a uniformly dispersed composite electrolyte slurry, and the mass content of lithium aluminum titanium phosphate in the composite electrolyte slurry was 20%, and then the composite electrolyte slurry was placed as a working slurry 9 as shown in FIG. Figure 2 In the funnel-shaped trough 8 of the coating device shown, the fibrous positive flexible electrode obtained in step 2 is wound on the unwinding device 7, and one end is led out from the bottom discharge port of the funnel-shaped trough 8 through the composite electrolyte slurry, and the fibrous positive flexible electrode is pulled so that the composite electrolyte slurry is evenly coated on the surface of the fibrous positive flexible electrode, and then heated by the heating device (10) to volatilize the solvent, thereby obtaining a flexible electrode with a solid electrolyte layer on the surface, and then sent out and wound in the take-up device 11;

[0047] Step 4: Construction of negative electrode current collector: Use a copper wire with a diameter of 0.2 mm as the negative electrode current collector and evenly wind it on the surface of the flexible electrode with a solid electrolyte layer obtained in step 3, and keep a spacing of 1 mm to 5 mm between adjacent windings of the negative electrode current collector to obtain a coaxial fiber-shaped flexible battery structure, such as Figure 4 As shown;

[0048] Step 5, preparation of negative electrode slurry: adding the negative electrode material artificial graphite (AG), conductive agent conductive carbon black (SP), binder polyvinylidene fluoride (PVDF), and lithium aluminum titanium phosphate (LATP) inorganic solid electrolyte solid materials in a mass ratio of 90:3:3:4 to N-methylpyrrolidone solvent and stirring until stable to obtain a negative electrode slurry;

[0049] Step 6: Preparation of negative electrode active material layer: The negative electrode slurry obtained in step 5 is used as working slurry 9 and placed in Figure 2In the funnel-shaped trough 8 of the coating equipment shown, the coaxial fibrous flexible battery structure obtained in step 4 is wound on the pay-off device 7, and one end passes through the negative electrode slurry and is led out from the bottom discharge port of the funnel-shaped trough 8. The coaxial fibrous flexible battery structure is pulled at a rate of 1 m / min to 4 m / min, so that the negative electrode slurry is evenly coated on the surface of the coaxial fibrous flexible battery structure, and then baked at 90°C to 110°C by the heating device 10 to obtain the coaxial fibrous flexible battery core, which is then sent out and wound in the take-up device 11;

[0050] Step 7, shell packaging: Place the coaxial fibrous flexible battery core obtained in step 6 in a polyolefin transparent heat shrink tube with an inner diameter of 2.5 mm, add 1 mol / L lithium hexafluorophosphate (LiPF6) liquid electrolyte to the polyolefin transparent heat shrink tube and activate it at 45°C for 12 hours, then heat it to 100°C with a hot air blower, so that the polyolefin transparent heat shrink tube shrinks due to the heat and tightly wraps around the surface of the coaxial fibrous flexible battery core. After sealing the two ends, a coaxial flexible solid-state battery structure is obtained; the liquid electrolyte is a carbonate electrolyte, which is composed of lithium salt lithium hexafluorophosphate and an ester solvent, namely ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate in a volume ratio of 3:4:3.

[0051] In step 1 of this embodiment, the positive electrode material may be at least one of lithium cobalt oxide, ternary materials, lithium manganate, lithium iron phosphate, and lithium-rich manganese-based materials other than lithium cobalt oxide, the conductive agent may be at least one of carbon black other than conductive carbon black, activated carbon, carbon fiber, and carbon nanotubes, and the inorganic solid electrolyte may be at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide, and lithium lanthanum titanate other than lithium aluminum titanium phosphate;

[0052] The fibrous positive electrode current collector in step 2 may also be stainless steel wire or nickel wire;

[0053] In step 3, the solvent may also be acetone or N-methylpyrrolidone, and the inorganic solid electrolyte may also be at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide, and lithium lanthanum titanate oxide in addition to lithium aluminum titanium phosphate;

[0054] The negative electrode current collector in step 4 can also be stainless steel wire or nickel wire;

[0055] In step 5, the negative electrode material may also be at least one of graphite other than artificial graphite, soft carbon and hard carbon, the conductive agent may also be at least one of carbon black other than conductive carbon black, activated carbon, carbon fiber and carbon nanotubes, and the inorganic solid electrolyte may also be at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide and lithium lanthanum titanate other than lithium aluminum titanium phosphate;

[0056] The ester solvent in step seven may also be at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate and ethyl methyl carbonate other than the combination of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate.

[0057] Example 2

[0058] like Figure 1 As shown, the coaxial flexible solid-state battery structure of this embodiment is characterized in that it includes a fibrous positive electrode current collector 1, a positive electrode active material layer 2, a solid electrolyte layer 3, a negative electrode active material layer 4, a negative electrode current collector 5 and an outer skin layer 6 in sequence along the coaxial direction from the inside to the outside.

[0059] like Figure 3 As shown, the method for preparing the coaxial flexible solid-state battery structure of this embodiment includes the following steps:

[0060] Step 1, preparation of positive electrode slurry: add the positive electrode material lithium cobalt oxide (LiCoO2), conductive agent conductive carbon black (Super-P), binder polyvinylidene fluoride (PVDF), lithium aluminum titanium phosphate (LATP) solid electrolyte solid materials according to a mass ratio of 93:2:3:2 to N-methylpyrrolidone (NMP) solvent and stir thoroughly until stable to obtain a positive electrode slurry with a viscosity of 9000Pa·s to 11000Pa·s;

[0061] Step 2: Preparation of fibrous positive flexible electrode: The positive electrode slurry obtained in step 1 is used as working slurry 9 and placed in Figure 2 In the funnel-shaped trough 8 of the coating equipment shown, a fibrous positive electrode current collector, i.e., an aluminum wire with a diameter of 0.3 mm, is wound on a pay-off device 7, and one end passes through the positive electrode slurry and is drawn out from the bottom discharge port of the funnel-shaped trough 8. The fibrous positive electrode current collector is pulled at a rate of 1 m / min to 4 m / min so that the positive electrode slurry is evenly coated on the surface of the aluminum wire. The fibrous positive electrode current collector is then baked at 90°C to 110°C by a heating device 10 to obtain a fibrous positive flexible electrode, which is then sent out and wound in a take-up device 11.

[0062] Step 3. Construction of solid electrolyte layer: Add polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) to N,N-dimethylformamide (DMF) and stir continuously for 2 hours until it is fully dissolved to form a stable glue solution with a mass concentration of 15%. Then, use the glue solution to adhere a polypropylene-based separator with a thickness of 16 μm and coated on both sides with lithium titanium aluminum phosphate solid electrolyte to the surface of the fibrous positive flexible electrode obtained in step 2. After the solvent evaporates, a flexible electrode with a solid electrolyte layer on the surface is obtained;

[0063] Step 4: Construction of the negative electrode current collector: Use a copper wire with a diameter of 0.15 mm as the negative electrode current collector and evenly wind it on the surface of the flexible electrode with a solid electrolyte layer obtained in step 3, and maintain a spacing of 1 mm to 5 mm between adjacent windings of the negative electrode current collector to obtain a coaxial fiber-shaped flexible battery structure;

[0064] Step 5, preparation of negative electrode slurry: adding the negative electrode material artificial graphite (AG), conductive agent conductive carbon black (SP), binder polyvinylidene fluoride (PVDF), and lithium aluminum titanium phosphate (LATP) inorganic solid electrolyte solid materials in a mass ratio of 92:3:3:2 to N-methylpyrrolidone solvent and stirring until stable to obtain a negative electrode slurry;

[0065] Step 6: Preparation of negative electrode active material layer: The negative electrode slurry obtained in step 5 is used as working slurry 9 and placed in Figure 2 In the funnel-shaped trough 8 of the coating equipment shown, the coaxial fibrous flexible battery structure obtained in step 4 is wound on the pay-off device 7, and one end is passed through the negative electrode slurry and drawn out from the bottom discharge port of the funnel-shaped trough 8. The coaxial fibrous flexible battery structure is pulled at a rate of 1 m / min to 4 m / min, so that the negative electrode slurry is evenly coated on the surface of the coaxial fibrous flexible battery structure, and then baked at 90°C to 110°C by the heating device 10 to obtain the coaxial fibrous flexible battery core, which is then sent out and wound in the take-up device 11;

[0066] Step 7: Shell packaging: Place the coaxial fiber-shaped flexible battery core obtained in step 6 in a transparent heat-shrinkable polyolefin tube with an inner diameter of 2 mm, add 1 mol / L lithium hexafluorophosphate (LiPF6) liquid electrolyte to the transparent heat-shrinkable polyolefin tube and activate it at 45 ° C for 6 hours, then heat it to 100 ° C with a hot air blower, so that the transparent heat-shrinkable polyolefin tube shrinks and tightly wraps around the surface of the coaxial fiber-shaped flexible battery core. After sealing the two ends, a coaxial flexible solid-state battery structure is obtained. Figure 5 As shown; the liquid electrolyte is a carbonate electrolyte, which is composed of lithium salt lithium hexafluorophosphate and an ester solvent, namely ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate in a volume ratio of 3:4:3.

[0067] In step 1 of this embodiment, the positive electrode material may be at least one of lithium cobalt oxide, ternary materials, lithium manganate, lithium iron phosphate, and lithium-rich manganese-based materials other than lithium cobalt oxide, the conductive agent may be at least one of carbon black other than conductive carbon black, activated carbon, carbon fiber, and carbon nanotubes, and the inorganic solid electrolyte may be at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide, and lithium lanthanum titanate other than lithium aluminum titanium phosphate;

[0068] The fibrous positive electrode current collector in step 2 may also be stainless steel wire or nickel wire;

[0069] In step 3, the solvent may also be acetone or N-methylpyrrolidone, the solid electrolyte coated on the surface of the solid electrolyte diaphragm may also be lithium lanthanum zirconium oxide, and the diaphragm may also be a polyethylene diaphragm;

[0070] The negative electrode current collector in step 4 can also be stainless steel wire or nickel wire;

[0071] In step 5, the negative electrode material may also be at least one of graphite other than artificial graphite, soft carbon and hard carbon, the conductive agent may also be at least one of carbon black other than conductive carbon black, activated carbon, carbon fiber and carbon nanotubes, and the inorganic solid electrolyte may also be at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide and lithium lanthanum titanate other than lithium aluminum titanium phosphate;

[0072] The ester solvent in step seven may also be at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate and ethyl methyl carbonate other than the combination of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate.

[0073] Example 3

[0074] like Figure 1 As shown, the coaxial flexible solid-state battery structure of this embodiment is characterized in that it includes a fibrous positive electrode current collector 1, a positive electrode active material layer 2, a solid electrolyte layer 3, a negative electrode active material layer 4, a negative electrode current collector 5 and an outer skin layer 6 in sequence along the coaxial direction from the inside to the outside.

[0075] like Figure 3 As shown, the method for preparing the coaxial flexible solid-state battery structure of this embodiment includes the following steps:

[0076] Step 1: Preparation of positive electrode slurry: Prepare the positive electrode material ternary material (LiNi 0.5 Co 0.2 Mn 0.3 O2), conductive carbon black (Super-P) and carbon nanotubes (CNTs) as a conductive agent, polyvinylidene fluoride (PVDF) as a binder, and lithium aluminum titanium phosphate (LATP) as a solid electrolyte solid material are added to N-methylpyrrolidone (NMP) solvent in a mass ratio of 90:2.5:0.5:3:4 and fully stirred until stable to obtain a positive electrode slurry with a viscosity of 9000 Pa·s to 11000 Pa·s;

[0077] Step 2: Preparation of fibrous positive flexible electrode: The positive electrode slurry obtained in step 1 is used as working slurry 9 and placed in Figure 2In the funnel-shaped trough 8 of the coating equipment shown, a fibrous positive electrode current collector, i.e., an aluminum wire with a diameter of 0.5 mm, is wound on a pay-off device 7, and one end passes through the positive electrode slurry and is drawn out from the bottom discharge port of the funnel-shaped trough 8. The fibrous positive electrode current collector is pulled at a rate of 1 m / min to 4 m / min so that the positive electrode slurry is evenly coated on the surface of the aluminum wire. The fibrous positive electrode current collector is then baked at 90°C to 110°C by a heating device 10 to obtain a fibrous positive flexible electrode, which is then sent out and wound in a take-up device 11.

[0078] Step 3, the construction of the solid electrolyte layer: polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) was added to N, N-dimethylformamide (DMF) and stirred continuously for 2 hours until it was fully dissolved to form a stable gel solution with a mass concentration of 15%, and then lithium aluminum titanium phosphate (LATP) inorganic solid electrolyte with a particle size of 0.3 μm was added and stirred continuously for 3 hours to obtain a uniformly dispersed composite electrolyte slurry, and the mass content of lithium aluminum titanium phosphate in the composite electrolyte slurry was 12%, and then the composite electrolyte slurry was placed as a working slurry 9 as shown in FIG. Figure 2 In the funnel-shaped trough 8 of the coating device shown, the fibrous positive flexible electrode obtained in step 2 is wound on the unwinding device 7, and one end is led out from the bottom discharge port of the funnel-shaped trough 8 through the composite electrolyte slurry, and the fibrous positive flexible electrode is pulled so that the composite electrolyte slurry is evenly coated on the surface of the fibrous positive flexible electrode, and then heated by the heating device (10) to volatilize the solvent, thereby obtaining a flexible electrode with a solid electrolyte layer on the surface, and then sent out and wound in the take-up device 11;

[0079] Step 4: Construction of the negative electrode current collector: Use a copper wire with a diameter of 0.25 mm as the negative electrode current collector and evenly wrap it around the surface of the flexible electrode with a solid electrolyte layer obtained in step 3, and maintain a spacing of 1 mm to 5 mm between adjacent windings of the negative electrode current collector to obtain a coaxial fiber-shaped flexible battery structure;

[0080] Step 5, preparation of negative electrode slurry: adding the negative electrode material artificial graphite (AG), conductive agent conductive carbon black (SP), carbon fiber (VGCF), binder polyvinylidene fluoride (PVDF), and lithium aluminum titanium phosphate (LATP) inorganic solid electrolyte solid materials in a mass ratio of 90:3:2:1:4 to N-methylpyrrolidone solvent and stirring until stable to obtain a negative electrode slurry;

[0081] Step 6: Preparation of negative electrode active material layer: The negative electrode slurry obtained in step 5 is used as working slurry 9 and placed in Figure 2In the funnel-shaped trough 8 of the coating equipment shown, the coaxial fibrous flexible battery structure obtained in step 4 is wound on the pay-off device 7, and one end passes through the negative electrode slurry and is led out from the bottom discharge port of the funnel-shaped trough 8. The coaxial fibrous flexible battery structure is pulled at a rate of 1 m / min to 4 m / min, so that the negative electrode slurry is evenly coated on the surface of the coaxial fibrous flexible battery structure, and then baked at 90°C to 110°C by the heating device 10 to obtain the coaxial fibrous flexible battery core, which is then sent out and wound in the take-up device 11;

[0082] Step seven, shell packaging: place the coaxial fibrous flexible battery core obtained in step six in a polyolefin transparent heat shrink tube with an inner diameter of 3 mm, add 1 mol / L lithium hexafluorophosphate (LiPF6) liquid electrolyte to the polyolefin transparent heat shrink tube and activate it at 45°C for 12 hours, then heat it to 100°C with a hot air blower, so that the polyolefin transparent heat shrink tube shrinks due to the heat and tightly wraps around the surface of the coaxial fibrous flexible battery core. After sealing at both ends, a coaxial flexible solid-state battery structure is obtained; the liquid electrolyte is a carbonate electrolyte, which is composed of lithium salt lithium hexafluorophosphate and an ester solvent, namely ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate in a volume ratio of 1:1:1, and 2% by mass of vinylene carbonate is added.

[0083] In step 1 of this embodiment, the positive electrode material may be at least one of lithium cobalt oxide, ternary materials, lithium manganate, lithium iron phosphate, and lithium-rich manganese-based materials other than ternary materials. The conductive agent may be at least one of carbon black, activated carbon, carbon fiber, and carbon nanotubes other than a combination of conductive carbon black and carbon nanotubes. The inorganic solid electrolyte may be at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide, and lithium lanthanum titanate other than lithium aluminum titanium phosphate.

[0084] The fibrous positive electrode current collector in step 2 may also be stainless steel wire or nickel wire;

[0085] In step 3, the solvent may also be acetone or N-methylpyrrolidone, and the inorganic solid electrolyte may also be at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide, and lithium lanthanum titanate oxide in addition to lithium aluminum titanium phosphate;

[0086] The negative electrode current collector in step 4 can also be stainless steel wire or nickel wire;

[0087] In step 5, the negative electrode material may also be at least one of graphite, soft carbon and hard carbon other than artificial graphite, the conductive agent may also be at least one of carbon black, activated carbon, carbon fiber and carbon nanotube other than a combination of conductive carbon black and carbon fiber, and the inorganic solid electrolyte may also be at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide and lithium lanthanum titanate other than lithium aluminum titanium phosphate;

[0088] The ester solvent in step seven may also be at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate and ethyl methyl carbonate other than the combination of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate.

[0089] Example 4

[0090] The difference between this embodiment and embodiment 1 is that: in step 1, the mass ratio of the positive electrode material lithium cobalt oxide (LiCoO2), the conductive agent conductive carbon black (Super-P), the binder polyvinylidene fluoride (PVDF), and the lithium aluminum titanium phosphate (LATP) solid electrolyte solid materials is 97:1:1:1; the fibrous positive electrode current collector used in step 2 is an aluminum wire with a diameter of 0.1 mm; in step 3, polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) is added to N-methylpyrrolidone (NMP) and fully dissolved to form a stable glue with a mass concentration of 5%, and then a particle size of 100 is added. nm lithium aluminum titanium phosphate (LATP) inorganic solid electrolyte to obtain a uniformly dispersed composite electrolyte slurry, the mass content of lithium aluminum titanium phosphate in the composite electrolyte slurry is 10%; in step 4, the negative electrode current collector uses a copper wire with a diameter of 0.05 mm; in step 5, the negative electrode material artificial graphite (AG), conductive agent conductive carbon black (SP), carbon fiber (VGCF), binder polyvinylidene fluoride (PVDF), lithium aluminum titanium phosphate (LATP) inorganic solid electrolyte solid material mass ratio is 97:0.8:0.2:1:1; in step 7, a polyolefin heat shrink tube with an inner diameter of 2.5 mm is used.

[0091] Example 5

[0092] The difference between this embodiment and embodiment 3 is that the positive electrode ternary material (LiNi 0.5 Co 0.2 Mn 0.3 O2), conductive agent conductive carbon black (Super-P), binder polyvinylidene fluoride (PVDF), lithium aluminum titanium phosphate (LATP) solid electrolyte solid material mass ratio of 79:10:10:1; the fibrous positive electrode current collector used in step 2 is an aluminum wire with a diameter of 2 mm; in step 3, polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) is added to N-methylpyrrolidone (NMP) and fully dissolved to form a stable glue with a mass concentration of 15%; in step 4, the negative electrode current collector uses a copper wire with a diameter of 0.05 mm; in step 5, the negative electrode material artificial graphite (AG), conductive agent conductive carbon black (SP), carbon fiber (VGCF), binder polyvinylidene fluoride (PVDF), lithium aluminum titanium phosphate (LATP) inorganic solid electrolyte solid material mass ratio of 79:8:2:10:1; in step 7, a polyolefin heat shrink tube with an inner diameter of 4 mm is used.

[0093] Example 6

[0094] The difference between this embodiment and embodiment 3 is that the positive electrode ternary material (LiNi 0.5 Co 0.2 Mn 0.3 O2), conductive agent conductive carbon black (Super-P), binder polyvinylidene fluoride (PVDF), lithium aluminum titanium phosphate (LATP) solid electrolyte solid material mass ratio is 80:5:5:10; the fibrous positive electrode current collector used in step 2 is aluminum wire with a diameter of 2mm; in step 3, polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) is added to acetone and fully dissolved to form a stable mass concentration of 15% glue, and then lithium aluminum titanium phosphate (LATP) inorganic solid with a particle size of 0.8μm is added The electrolyte is prepared by mixing the electrolyte and obtaining a uniformly dispersed composite electrolyte slurry, wherein the mass content of lithium aluminum titanium phosphate in the composite electrolyte slurry is 30%; in step 4, a copper wire with a diameter of 1 mm is used as the negative electrode current collector; in step 5, the mass ratio of the negative electrode material artificial graphite (AG), conductive agent conductive carbon black (SP), carbon fiber (VGCF), binder polyvinylidene fluoride (PVDF), and inorganic solid electrolyte solid material of lithium aluminum titanium phosphate (LATP) is 80:4:1:5:10; in step 7, a polyolefin heat shrink tube with an inner diameter of 5 mm is used.

[0095] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the essence of the invention technology shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A coaxial flexible solid-state battery structure, characterized in that: The structure includes, from the inside to the outside along the coaxial direction, a fibrous positive electrode current collector (1), a positive electrode active material layer (2), a solid electrolyte layer (3), a negative electrode active material layer (4), a negative electrode current collector (5), and an outer skin layer (6); The method for preparing the coaxial flexible solid-state battery structure comprises the following steps: Step 1: Preparation of positive electrode slurry: Add positive electrode material, conductive agent, binder, and inorganic solid electrolyte solid material into N-methylpyrrolidone solvent and stir thoroughly until stable to obtain positive electrode slurry; Step 2, preparation of a fibrous positive flexible electrode: the positive electrode slurry obtained in step 1 is placed as a working slurry (9) in a funnel-shaped trough (8) of a coating device, the fibrous positive current collector is wound on a pay-off device (7), and one end is passed through the positive electrode slurry and led out from the bottom discharge port of the funnel-shaped trough (8), the fibrous positive current collector is pulled so that the positive electrode slurry is evenly coated on the surface of the fibrous positive current collector, and then baked in a heating device (10) to obtain a fibrous positive flexible electrode, which is then sent out and wound in a take-up device (11); Step 3, construction of solid electrolyte layer: adding polyvinylidene fluoride-hexafluoropropylene to an organic solvent and stirring continuously until fully dissolved to form a stable gel, then adding nanometer-scale to submicron-scale inorganic solid electrolyte and stirring continuously to obtain a uniformly dispersed composite electrolyte slurry, and then placing the composite electrolyte slurry as a working slurry (9) in a funnel-shaped trough (8) of a coating device, winding the fibrous positive flexible electrode obtained in step 2 on a pay-off device (7), and one end passes through the composite electrolyte slurry and is led out from the bottom outlet of the funnel-shaped trough (8), pulling the fibrous positive flexible electrode so that the composite electrolyte slurry is evenly coated on the surface of the fibrous positive flexible electrode, and then heating it through a heating device (10) to volatilize the solvent, thereby obtaining a flexible electrode with a solid electrolyte layer on the surface, and sending it out and winding it in a take-up device (11); Alternatively, the solid electrolyte membrane is adhered to the surface of the fibrous positive flexible electrode obtained in step 2 using a glue solution to obtain a flexible electrode having a solid electrolyte layer on the surface; Step 4: Construction of the negative electrode current collector: Using a metal wire as the negative electrode current collector, uniformly winding it around the surface of the flexible electrode having the solid electrolyte layer obtained in step 3, and maintaining a distance between adjacent windings of the negative electrode current collector to obtain a coaxial fiber-shaped flexible battery structure; Step 5: Preparation of negative electrode slurry: Add the negative electrode material, conductive agent, binder, and inorganic solid electrolyte solid material into N-methylpyrrolidone solvent and stir thoroughly until stable to obtain negative electrode slurry; Step 6, preparation of the negative electrode active material layer: the negative electrode slurry obtained in step 5 is placed as the working slurry (9) in the funnel-shaped trough (8) of the coating equipment, the coaxial fiber-shaped flexible battery structure obtained in step 4 is wound on the unwinding device (7), and one end passes through the negative electrode slurry and is led out from the bottom discharge port of the funnel-shaped trough (8), the coaxial fiber-shaped flexible battery structure is pulled so that the negative electrode slurry is evenly coated on the surface of the coaxial fiber-shaped flexible battery structure, and then baked by the heating device (10) to obtain the coaxial fiber-shaped flexible battery core, and then sent out and wound in the take-up device (11); Step 7. Shell packaging: Place the coaxial fibrous flexible battery core obtained in step 6 in a polyolefin heat shrink tube, add liquid electrolyte to the polyolefin heat shrink tube and let it stand for activation, then allow the polyolefin heat shrink tube to shrink due to heat and tightly wrap around the surface of the coaxial fibrous flexible battery core. After sealing the two ends, a coaxial flexible solid-state battery structure is obtained.

2. The coaxial flexible solid-state battery structure according to claim 1, characterized in that: The positive electrode material in step one is at least one of lithium cobalt oxide, a ternary material, lithium manganate, lithium iron phosphate and a lithium-rich manganese-based material, the conductive agent is at least one of carbon black, activated carbon, carbon fiber and carbon nanotubes, the binder is polyvinylidene fluoride, and the inorganic solid electrolyte is at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide and lithium lanthanum titanium oxide, and the mass content of the positive electrode material in the solid material is 79% to 97%, the mass content of the conductive agent is 1% to 10%, the mass content of the binder is 1% to 10%, and the mass content of the inorganic solid electrolyte is 1% to 10%.

3. The coaxial flexible solid-state battery structure according to claim 1, characterized in that: The fibrous positive electrode current collector in step 2 is aluminum wire, stainless steel wire or nickel wire with a diameter of 0.1 mm to 2 mm.

4. The coaxial flexible solid-state battery structure according to claim 1, characterized in that: The organic solvent in step three is acetone, N-methylpyrrolidone or N,N-dimethylformamide, and the mass concentration of the glue is 5% to 20%; the inorganic solid electrolyte is at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide and lithium lanthanum titanium oxide, and the mass content of the inorganic solid electrolyte in the composite electrolyte slurry is 10% to 30%.

5. The coaxial flexible solid-state battery structure according to claim 1, characterized in that: The solid electrolyte membrane in step three is a polyethylene or polypropylene-based membrane with a surface coated with lithium titanium aluminum phosphate or lithium lanthanum zirconium oxide solid electrolyte.

6. The coaxial flexible solid-state battery structure according to claim 1, characterized in that: The negative electrode current collector in step 4 is a copper wire, stainless steel wire or nickel wire with a diameter of 0.05 mm to 1 mm.

7. The coaxial flexible solid-state battery structure according to claim 1, characterized in that: The negative electrode material in step five is at least one of graphite, soft carbon and hard carbon, the conductive agent is at least one of carbon black, activated carbon, carbon fiber and carbon nanotubes, the binder is polyvinylidene fluoride, and the inorganic solid electrolyte is at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide and lithium lanthanum titanium oxide, and the mass content of the negative electrode material in the solid material is 79% to 97%, the mass content of the conductive agent is 1% to 10%, the mass content of the binder is 1% to 10%, and the mass content of the inorganic solid electrolyte is 1% to 10%.

8. The coaxial flexible solid-state battery structure according to claim 1, characterized in that: The liquid electrolyte in step seven is a carbonate electrolyte, which is composed of a lithium salt and an ester solvent, wherein the lithium salt is lithium hexafluorophosphate, and the ester solvent is at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate and ethyl methyl carbonate.

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